TY - JOUR. T1 - Electrostatic energy calculation on the pH-induced conformational change of influenza virus hemagglutinin. AU - Ho, Sup Choi. AU - Huh, June. AU - Won, Ho Jo. PY - 2006. Y1 - 2006. N2 - The pH-induced conformational change of influenza virus hemagglutinin (HA) has been investigated by calculating the change of electrostatic energy of the fragment of HA2 upon pH change. The average charge and electrostatic free energy are calculated as a function of pH for the fusion peptide (residues 1-20 of HA2) and the polypeptide of residues 54-77 of HA2 by using the finite difference Poisson-Boltzmann method. It is found that as pH decreases from 8 to 5, the electrostatic free energy of the fusogenic state is lowered by ∼2 kcal/mol and the fusogenic state is less ionized compared to that of the native state for both polypeptides. For the fusion peptide at the fusogenic state, most of ionizable residues are neutral at acidic pH except Glu-11. For the polypeptide of residues 54-77 at the ...
Authors: MURAT CENGİZ, GÜLÇE HEPBOSTANCI Abstract: In this study, combination antimicrobial therapy, due to its higher potential against resistant bacteria, was evaluated for the inhibition of multidrug-resistant E. coli strains. The influence of pH as an environmental variable on the activity of antimicrobial combinations was evaluated by calculating the factional concentration indexes at pH values 5.0, 6.0, 7.3, and 8.0. The highest synergistic activity rates of ceftriaxone + colistin, danofloxacin + colistin, danofloxacin + ceftiofur, and ceftiofur + gentamicin combinations were 50%, 33%, 100%, and 50%, respectively measured at ≥7.3 pH. The lowest synergistic activity rates for all combinations were observed at the acidic pH values of 5.0 and 6.0. The results of this study clearly demonstrated that acidic pH of the medium impaired the activity of the antimicrobial combinations. Although ceftriaxone and ceftiofur exert optimal activity at acidic pH values, the synergistic activity of the ...
Increasing the extracellular pH over the range pH 7.4-8.9 stimulated protein synthesis by about 60% in the rat heart preparation anterogradely perfused in vitro. Protein degradation was inhibited by this pH increase. The magnitudes of the effects at pH 8.9 on protein synthesis and degradation were similar to those of high concentrations of insulin. Cardiac outputs were increased, as were cardiac phosphocreatine contents, indicating that the alterations in extracellular pH did not adversely affect the physiological viability of the preparation. ATP contents were unaltered. The creatine kinase equilibrium was used to assess the magnitude of the change in intracellular pH induced by these treatments. The increase in intracellular pH was about 0.2 for a 1-unit increase in extracellular pH. Thus small changes in intracellular pH have dramatic effects on cardiac protein turnover. ...
In the new study, Young and his colleagues found that toxin entry occurred at near neutral pH conditions when it was bound to the TEM8 receptor, but at strongly acidic conditions when bound to CMG2. The researchers in Young s lab at Salk revealed the two different pH levels when they created cells that had only TEM8 receptors or CMG2 receptors, but not both. They then used a drug that neutralizes the pH inside cells to test how it affected toxin entry in both cell types ...
Understanding and predicting the effect of various environments that differ in terms of pH and the presence of cosolutes and macromolecules on protein properties is a formidable challenge. Yet this knowledge is crucial in understanding the effect of cellular environments on a protein. By combining thermodynamic theories of solution condition effects with statistical mechanics and computer simulations we develop a molecular perspective of protein folding and amyloid formation that was previously unobtainable. The resulting Molecular Transfer Model offers, in some instances, quantitatively accurate predictions of cosolute and pH effects on various protein properties. We show that protein denatured state properties can change significantly with osmolyte concentration, and that residual structure can persist at high denaturant concentrations. We study the single molecule mechanical unfolding of proteins at various pH values and varying osmolyte and denaturant concentrations. We find that the the ...
In this work, the near-neutral photo-Fenton process, as a means of wastewater disinfection, was enhanced by the addition of Organic Acids (OAs), namely citric, ascorbic, tartaric and caffeic acid. The addition of OAs exhibited significant bacterial inactivation enhancement, compared to the classic photo-Fenton systems (Fe2+/H2O2/solar and Fe3+/H2O2/solar). The improved disinfection performance was not attributed to pH variations by the addition of OAs, but to the increase of the initial dissolved iron in the system, facilitating the Fe3+/Fe2+ turnover in the catalytic photo-Fenton reaction and consequently, the hydroxyl radicals production. For citric and tartaric acid, increased photo-activity of the complexes was associated with their high capability to complex Fe3+ and to promote ligand-to-metal charge transfer (LMCT), which is of key importance to feed Fe2+ to the Fenton process. On the other hand, for ascorbic and caffeic acid, the acceleration of the homogeneous Fenton reaction was ...
When some strong acid is added to an equilibrium mixture of the weak acid and its conjugate base, the equilibrium is shifted to the left, in accordance with Le Châteliers principle. Because of this, the hydrogen ion concentration increases by less than the amount expected for the quantity of strong acid added. Similarly, if strong alkali is added to the mixture the hydrogen ion concentration decreases by less than the amount expected for the quantity of alkali added. The effect is illustrated by the simulated titration of a weak acid with pKa = 4.7. The relative concentration of undissociated acid is shown in blue and of its conjugate base in red. The pH changes relatively slowly in the buffer region, pH = pKa ± 1, centered at pH = 4.7 where [HA] = [A−]. The hydrogen ion concentration decreases by less than the amount expected because most of the added hydroxide ion is consumed in the reaction ...
Many E. coli genes show pH-dependent expression during logarithmic growth in acid (pH 5-6) or in base (pH 8-9). The effect of rapid pH change, however, has rarely been tested. Rapid acid treatment could distinguish between genes responding to external pH, and genes responding to cytoplasmic acidification, which occurs transiently following rapid external acidification. It could reveal previously unknown acid-stress genes whose effects are transient, as well as show which acid-stress genes have a delayed response. Microarray hybridization was employed to observe the global gene expression of E. coli K-12 W3110 following rapid acidification of the external medium, from pH 7.6 to pH 5.5. Fluorimetric observation of pH-dependent tetR-YFP showed that rapid external acidification led to a half-unit drop in cytoplasmic pH (from pH 7.6 to pH 6.4) which began to recover within 20 s. Following acid treatment, 630 genes were up-regulated and 586 genes were down-regulated. Up-regulated genes included amino-acid
TY - JOUR. T1 - A new technique for measurement of pharyngeal pH. T2 - Normal values and discriminating pH threshold. AU - Ayazi, S.. AU - Lipham, J. C.. AU - Hagen, J. A.. AU - Tang, A. L.. AU - Zehetner, J.. AU - Leers, J. M.. AU - Oezcelik, A.. AU - Abate, E.. AU - Banki, F.. AU - DeMeester, S. R.. AU - DeMeester, T. R.. PY - 2009/7/1. Y1 - 2009/7/1. N2 - Introduction Identifying gastroesophageal reflux disease as the cause of respiratory and laryngeal complaints is difficult and depends largely on the measurements of increased acid exposure in the upper esophagus or ideally the pharynx. The current method of measuring pharyngeal pH environment is inaccurate and problematic due to artifacts. A newly designed pharyngeal pH probe to avoid these artifacts has been introduced. The aim of this study was to use this probe to measure the pharyngeal pH environment in normal subjects and establish pH thresholds to identify abnormality. Methods Asymptomatic volunteers were studied to define the normal ...
We show that pH homeostasis varies among individual bacterial cells, both among planktonic cells adhered to a slide and among cells within a biofilm grown on a slide. This variability implies that the pH response and recovery measurements obtained for cell suspensions miss important aspects of pH homeostasis of individual cells. The variation we saw could be associated with substrate adherence and with variability among suspended cells. Properties of adherent cells are highly important for medical, environmental, and industrial applications.. To measure pH homeostasis, we used ratiometric GFP combined with fluorescence microscopy, both for E. coli (Fig. 4) and for B. subtilis (Fig. 8). Ratiometric pHluorin (18) combines the advantages of GFP fluorimetry (14, 15, 36) and fluorescence microscopy. Fluorimetry reports only the average response of cell populations, with no capacity to monitor individual cells. For single cells, cytoplasmic pH has been measured previously by ratio imaging with a ...
Filamentous fungi have the ability to efficiently decompose plant biomass, and thus are widely used in the biofuel and bioprocess industries. In process, ambient pH has been reported to strongly affect the performance of the applied functional filamentous fungi. In this study, Trichoderma guizhouense NJAU4742 was investigated under the fermentation of rice straw at different initial pH values for a detailed study. The results showed that NJAU4742 strain could tolerate ambient pH values ranging from 3.0 to 9.0, but had significantly higher growth speed and extracellular enzyme activities under acidic conditions. At low ambient pH (| 4), NJAU4742 strain achieved rapid degradation of rice straw by elevating the ambient pH to an optimal range through environmental alkalinization. Further proteomic analysis identified a total of 1139 intracellular and extracellular proteins during the solid-state fermentation processes, including the quantified 190 carbohydrate-active enzymes (CAZymes) responsible for rice
1. An accurate quantitative method of measuring the penetration of dye into the living cell is described. 2. Cresyl blue is unable to penetrate rapidly unless the pH outside the cell is decidedly greater than that inside. The rate of penetration increases with increasing pH. 3. Around pH 9 penetration of the dye is rapid while the reverse is true of exosmosis. At low pH values (5.9) exosmosis is rapid and penetration is very slow. ...
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H3O+ + OH-. The position of any equilibrium is given by an equilibrium constant, K, which for the dissociation of water according to the acid-base reaction just described is:. K = a(H3O+)a(OH-)/a2(H2O). In this equation, the chemical activities a can be approximated by the appropriate molar concentrations, indicated here by the use of square brackets in the form K = [H3O+][OH-]/[H2O]2 Since the concentration of water is approximately constant, it is normally included with the equilibrium constant of water (in other words, the chemical activity of water is taken as that of pure water, which is unity). In that case the equilibrium constant above is known as the ion product of water or the autoionization constant of water and indicated by the subscript w, so that by definition:. Kw = [H3O+][OH-]. The ionization constants of acids and bases other than water are dealt with in a similar way. The ionization of acetic acid in water is described by the equilibrium. CH3COOH(aq) + H2O ...
Comparative Evaluation of Magnesium Bisulfite Pretreatment under Different pH Values for Enzymatic Hydrolysis of Corn Stover. Jiwei Ren,a Lei Liu,b Qianqian Xu,b Xin Li,b Qiang Yong,c and Jia Ouyang b,c,*. During pretreatment, the pretreatment pH often plays an important role in removing hemicelluloses and lignin for improving the conversion of biomass to sugars. In this study, corn stover was subjected to magnesium bisulfite pretreatment (MBSP) under various pH conditions. The obtained data showed that the hemicelluloses and lignin were solubilized by MBSP, which led to changes in the structural and chemical properties of the pretreated material. The pretreatment pH could alter the existing forms of SO2, and magnesium bisulfite was the most effective reagent for removing lignin. A relatively neutral MBSP (pH 5.13) not only considerably improved the enzymatic hydrolysis yield (80.18%), but also produced a large amount of high-value xylo-oligosaccharides in the spent liquor. Furthermore, only the ...
The hydrogen ion concentration is extremely important to the structural and functional integrity of living systems. Even slight changes in may cause profound changes in the large molecules and
Toxic chemicals and both prescription and over-the-counter drugs lower body`s pH levels, which is the reason why they come with a wide range of side effects and little or no effectiveness. Enzymes are deactivated when the pH drops below 6.4, which in turn compromises both digestion and assimilation of vitamins, minerals, and food supplements. Acid reduces the energy production on cellular level, the ability to detoxify heavy metals, the capacity to repair cells, and makes the body more prone to illness and fatigue.. It has been scientifically shown that disease cannot thrive in an alkaline environment, and that bacteria, yeast, mold, candida, fungus, and cancer cells thrive in an acidic and low pH environment. The most common causes of an acidic pH include emotional stress, toxic overload, an acid forming diet, and depletion of oxygen and nutrients. In turn, the body tries to compensate for acid by using alkaline mineral reserves, which then leads to development of a wide array of ...
Ethanol oxidation in 0.1 M NaOH on single-crystal electrodes has been studied using electrochemical and FTIR techniques. The results show that the activity order is the opposite of that found in acidic solutions. The Pt(111) electrode displays the highest currents and also the highest onset potential of all the electrodes. The onset potential for the oxidation of ethanol is linked to the adsorption of OH on the electrode surface. However, small (or even negligible) amounts of COads and carbonate are detected by FTIR, which implies that cleavage of the ...
The pH levels in dental biofilms are highly variable and frequently shift from above pH 7.0 in the resting pH state to as low as pH 3.0 during the ingestion of dietary carbohydrates by the host. Thus, pH exerts a significant ecological pressure on S. mutans, and its ability to tolerate and grow in low pH environments is crucial to its survival and eventual dominance in dental plaque, leading to caries (27). Considerable evidence has shown that S. mutans has evolved a number of sophisticated mechanisms to survive these pH changes including induction of an ATR in which exposure of S. mutans cells to a mild or moderately acidic pH (5.0-6.0) results in enhanced survival of a significant proportion of the cell population in a lower pH of 3.0-3.5 (28). This ATR involves a number of de novo proteins that appear to be important for adaptation to an acidic environment (29). Although many of the molecular mechanisms of the ATR in S. mutans remain unclear, this signal pH that results in synthesis of ...
The pH effect on the bleached hair was presented by Dr. Ernesta Malinauskyte during the Hair S19 Conference, organized by DWI in September of 2019. We have received many requests to share our findings by attendees of the conference, as well as those who attended our seminar held at TRI at the end of 2019. Unfortunate
Background Cytoplasmic pH homeostasis in Escherichia coli includes numerous mechanisms involving pH-dependent catabolism and ion fluxes. An important contributor is transmembrane K+ flux, but the actual basis of K+ compensation for pH stress remains unclear. Osmoprotection could mediate the pH protection afforded by K+ and other osmolytes. Methods and Principal Findings The cytoplasmic pH of E. coli K-12 strains was measured by GFPmut3 fluorimetry. The wild-type strain Frag1 was exposed to rapid external acidification by HCl addition. Recovery of cytoplasmic pH was enhanced equally by supplementation with NaCl, KCl, proline, or sucrose. A triple mutant strain TK2420 defective for the Kdp, Trk and Kup K+ uptake systems requires exogenous K+ for steady-state pH homeostasis and for recovery from sudden acid shift. The K+requirement however was partly compensated by supplementation with NaCl, choline chloride, proline, or sucrose. Thus, the K+ requirement was mediated in part by osmolarity, possibly by
1. Na+/H+ antiport activity was measured in peripheral blood polymorphonuclear and mononuclear cells of 12 healthy subjects by using an intracellular pH clamp technique to determine the external Na(+)-dependent H+ efflux rate in cells loaded with a pH-sensitive fluorescent dye, bis(carboxyethyl)carboxyfluorescein. The change in external Na+ concentrations for all pH measurements was similar in both cell types. 2. A significant difference between the two types of cells was found, the polymorphonuclear leucocytes having a higher Na+/H+ antiport activity than the lymphocytes. Cellular intrinsic buffering capacity measured in the absence of HCO3- was also higher in the polymorphonuclear cells than in the lymphocytes. 3. These differences may be associated with a difference in the role of the Na+/H+ exchanger in these two types of cells, although in vivo the presence of HCO3-/Cl- exchangers may also contribute to intracellular pH homoeostasis.
Around here, we talk a lot about feedback loops. A feedback loop is simply some way to objectively quantify some measurement to gain insight to our current location.. An example we commonly use to bring light to this idea of a feedback loop is how we find our way around a shopping mall weve never been in before.. Of course, we would go find the kiosk/map of the mall. And the first thing we look for is the You Are Here big red arrow, right?. Why? Because knowing where we are gives us perspective to determine if whatever action we undertake helps us to move in the right direction or not.. Saliva pH is a helpful feedback loop to see how well our systems are doing managing an optimal oral pH environment. If the saliva pH is too high, were asking for trouble. And if the pH is too low, this provokes more tooth decay because the bugs implicated with tooth decay thrive in a low pH environment.. Heres an article that dives into this fascinating subject, titled Tracking your saliva pH - part 2 ...
1. Pyridine reacts with alkaline haematin to form a dipyridine dihydroxy dimeric haematin in which there is no competition between pyridine and OH− for coordination positions on the iron of haematin. 2. Imidazole competes directly with OH− to form the monomeric imidazole parahaematin in alkaline media. 3. The monomeric imidazole parahaematin aggregates readily to form a species that is precipitated on standing. 4. A structure is proposed for the haematin-pyridine compound in alkaline media.. ...
1 ml of urine is diluted to 4 ml with a phosphate buffer at pH 6. 1ml of blood is de-proteinized by mean of sonication (15 minutes), vortex mixing (30 sec) and added with a phosphate buffer at pH 6. 5 min. Centrifugation is following (5 min. 300 r/min) and the precipitate eliminated. The B.E.C. column is conditioned with 2 ml of Methanol, 2 ml of water and 3 ml of a phosphate buffer solution at pH 6. Conditioning flow rate is 1.5 ml/min. The sample is then loaded onto the column at a flow rate of 1 ml/min. Before elution, the column is rinsed with 1 ml of buffer solution and dried under vacuum for 5 min. Column pH is lowered to the value of 3 by Acetic Acid teatment at a flow rate of 1.0 ml/min. Stationary phase is dried again under vacuum for 5 min and wet with 1.0 ml of hexane. Elution is performed at a flow rate of 0.5 ml/min with the following conditions: ...
TY - JOUR AU - Tripković, Amalija AU - Popović, Ksenija AU - Lović, Jelena PY - 2007 UR - http://cer.ihtm.bg.ac.rs/handle/123456789/290 AB - The electrochemical oxidation of methanol in NaOH solution was examined on a thin film Pt2Ru3/C electrode. The XRD pattern revealed that the Pt2Ru3 alloy consisted of a solid solution of Ru in Pt and a small amount of Ru or a solid solution of Pt in Ru. It was shown that in alkaline solution, the difference in activity between Pt/C and Pt2Ru3/C is significantly smaller than in acid solution. It is proposed that the reaction follows a quasi bifunctional mechanism. The kinetic parameters indicated that the chemical reaction between adsorbed COad and OHad species could be the rate limiting step. AB - Elektrohemijska oksidacija metanola ispitivana je na nanokatalizatoru Pt2Ru3 dispergovanom na aktivnom uglju kao nosaču u alkalnoj sredini. Katalizator je karakterisan difrakcijom X-zraka (XRD) i dobijeni rezultati su pokazali da se legura Pt2Ru3 sastoji od ...
All growers should do their own media pH and EC testing every week, at least on key crops. They can then send in periodic samples to a reputable testing lab for complete media (and tissue) analysis to back up their own findings, when they have problems showing up, or when they change something big such as the media or fertilizer program. Samples should be taken from commercial mixes out of the bag or your own hopper before sowing or planting the crop. To determine the true effect of the lime in the media, I suggest you also take samples after watering the flats or trays for one and two weeks with just your water, no feed. You should be able to see how the lime will affect the media pH within the first two weeks. Afterwards, I tell growers to monitor key crops, the ones more likely to show problems with media pH or EC. Here are my recommendations:. If you test one or more crops from each list weekly, you can avoid problems on those crops before they show up. All other crops will fall somewhere in ...
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For improving the therapeutic efficiency of tumors and decreasing undesirable side effects, ternary complexes were developed by coating pH-sensitive PEG-b-PLL-g-succinylsulfathiazole (hereafter abbreviated as PPSD) with DNA/PEI polyplexes via electrostatic interaction. PPSD can efficiently shield the surface charge of DNA/PEI. The gene transfection efficiency of ternary complexes was lower than that of DNA/PEI at pH 7.4; however, it recovered to the same level as that of DNA/PEI at pH 6.0, attributed to the pH-triggered release of DNA/PEI from ternary complexes. Cell uptake results also exhibited the same trend as transfection at different pH values. The suitable ability for pH-triggered shielding/deshielding estimated that PPSD demonstrates potential as a shielding system for use in in vivo gene delivery.
Accurate predictions of pKa values of titratable groups require taking into account all relevant processes associated with the ionization/deionization. Frequently, however, the ionization does not involve significant structural changes and the dominating effects are purely electrostatic in origin allowing accurate predictions to be made based on the electrostatic energy difference between ionized and neutral forms alone using a static structure. On another hand, if the change of the charge state is accompanied by a structural reorganization of the target protein, then the relevant conformational changes have to be taken into account in the pKa calculations. Here we report a hybrid approach that first predicts the titratable groups, which ionization is expected to cause conformational changes, termed
Several inwardly-rectifying (Kir) potassium channels (Kin l 1, Kir41 and Kir4 2) are characterised by their sensitivity to inhibition by intracellular H+ within the physiological range The mechanism by which these channels are regulated by intracellular pH has been the subject of intense scrutiny for over a decade, yet the molecular identity of the titratable pH-sensor remains elusive In this study we have taken advantage of the acidic intracellular environment of S cerevisiae and used a K+-auxotrophic strain to screen for mutants of Kin 1 1 with impaired pH-sensitivity In addition to the previously identified K80M mutation, this unbiased screening approach identified a novel mutation (S172T) in the second transmembrane domain (TM2) that also produces a marked reduction in pH-sensitivity through destabilization of the closed-state However, despite this extensive mutagenic approach, no mutations could be identified which removed channel pH-sensitivity or which were likely to act as a separate H+-sensor
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CheY, the 129 amino acid chemotactic protein from Escherichia coli, is a good model for studies of folding of parallel alpha/beta proteins. We report here the thermodynamic characterization of the wild-type CheY at different pH values and in different buffers and denaturation conditions. The denaturation of CheY by urea monitored by circular dichroism and fluorescence fits the two-state unfolding model. The stability of the protein is ionic strength dependent, probably due to the presence of three Asp residues in very close proximity in its active site. The presence of a Mg2+ ion, which seems to interact with Asp 13 in the active site, stabilizes the native structure by up to 6.9 kJ mol-1. The CheY maximum stability (31.7 +/- 2.1 kJ mol-1), without magnesium, is reached at pH 5.1. Analysis of scanning calorimetry data has shown that temperature-induced unfolding of CheY is not a two-state process and proceeds through a highly populated intermediate state, corresponding to protein dimers, as was ...
pH dependent ion exchange matrices are provided, with methods for making such matrices, and methods for using such matrices to isolate a target nucleic acid, such as plasmid DNA, chromosomal DNA, or RNA from contaminants, including proteins, lipids, cellular debris, or other nucleic acids. Each pH dependent ion exchange matrix of this invention comprises at least two different ion exchange functional groups, one of which is capable of acting as an anion exchanger at a first pH, and the other of which is capable of acting as a cation exchanger at a second, higher pH. The matrix has an overall neutral charge in a pH range between the first and second pH. The pH dependent ion exchange matrices of the present invention are designed to bind to the target nucleic acid at a pH wherein the overall charge of the matrix is positive, and to release the target nucleic acid as the pH of the surrounding solution is increased. The target nucleic acid can be released from the pH dependent matrix in little or no salt
Urine PH Measurement Device PHS-2F for Sale, US $120 / Piece, Guangdong, China, OEM, PHS-2F.Source from Guangzhou Allfine Medlab Co., Ltd. on Alibaba.com. According to Florida State Universtiy, pH affects enzyme activity by altering or inhibiting an enzyme from catalyzing a reaction. Changes in pH affect polar and non-polar forces, alter the shape of... A free platform for explaining your research in plain language, and managing how you communicate around it - so you can understand how best to increase its impact. I know cancer develops in an acid environment and can not survive in an alkaline medium; I usually have with me an alkalizing called Alkalife; I soaked a cotton ball directly with Alkalife, which is extremely alkaline and to my surprise after passing the cotton by the swelling it went away as if would be just a patch of foam; in this area remains today a small sink but the problem disappeared until today; I burned an area of adjacent good tissues because of the extreme alkalinity, but I no longer worried about the matter, as I have reviewed many times the area and has no symptoms of reproduction; I think I should have diluted a little the preparation. ... HPLC Application #16098: Non-Polar Acids at pH 2.5 using Onyx C18 3.0mm ID. Column used: Onyx™ Monolithic C18, LC Column 100 x 3 mm, Ea Part#: CH0-8158 The enzymatic controlled metabolic processes in cells occur at their optimized pH ranges, therefore cellular pH homeostasis is fundamental for life. TY - JOUR. T1 - Biliverdin-copper complex at physiological pH. AU - Dimitrijević, Milena S.. AU - Bogdanović Pristov, Jelena. AU - Žižić, Milan. AU - Stanković, Dalibor M.. AU - Bajuk-Bogdanović, Danica. AU - Stanić, Marina. AU - Spasić, Snežana. AU - Hagen, Wilfred. AU - Spasojević, Ivan. N1 - Accepted Author Manuscript. PY - 2019. Y1 - 2019. N2 - Biliverdin (BV), a product of heme catabolism, is known to interact with transition metals, but the details of such interactions under physiological conditions are scarce. Herein, we examined coordinate/redox interactions of BV with Cu 2+ in phosphate buffer at pH 7.4, using spectrophotometry, HESI-MS, Raman spectroscopy, 1 H NMR, EPR, fluorimetry, and electrochemical methods. BV formed a stable coordination complex with copper in 1:1 stoichiometry. The structure of BV was more planar and energetically stable in the complex. The complex showed strong paramagnetic effects that were attributed to an unpaired delocalized e - . The delocalized ... Interpretations of pH values are soundest when associated with dilute aqueous solutions of simple solutes; they become unsound when associated with nonaqueous solvents, colloids, or solutions of high ionic strength. For most applications the pH value may be regarded as a practical and comparative measure of acidity, and no attempt need be made to interpret it rigorously in terms of single-ion activity. In many calculations the hydrogen ion concentration is more accessible than the activity. For example, the electroneutrality condition is written in terms of concentrations rather than activities. Ka CA- + [HI] Solution of strong acid A strong acid, by definition, is one for which (3-11) is complete to the right, so that [HA] is essentially zero. From (3-14) [H] = + CHA [OH-] (3-18) The total concentration of hydrogen ion is that from the strong acid plus that from the water (equal to [OH-]). Unless the solution is extremely dilute (CHA< M), the second term may be neglected. Consider, for ... The surface enhanced Raman scattering (SERS) spectrum of a reporter molecule attached to gold or silver nanostructures, which is pH-sensitive, can deliver information on the local pH in the environment of the nanostructure. Here, we demonstrate the use of a mobile SERS nanosensor made from gold nanaoaggregates and 4-mercaptobenzoic acid (pMBA) attached as a reporter for monitoring changes in local pH of the cellular compartments of living NIH/3T3 cells. We show that SERS nanosensors enable the dynamics of local pH in individual live cells to be followed at subendosomal resolution in a timeline of cellular processes. This information is of basic interest for a better understanding of a broad range of physiological and metabolic processes as well as for a number of biotechnological applications ... This website uses cookies to help you receive a better online experience. By using this website, you are agreeing to the use of cookies as explained in our privacy policy ... Supplementary MaterialsSupplementary data 1 mmc1. acids that become pH sensors. Since the membrane fusion event happens in the pH range of 5C6, the most likely residues to function as pH detectors are histidines, aspartates and/or glutamates, which possess pKa in the appropriate pH range (Zhou et al., 2014). Based on a number of studies, multiple pH detectors are involved. First, from biochemical, x-ray, EM and virological studies, HA is known to undergo multiple reversible conformational changes when exposed to low pH (Xu and Wilson, 2011, Fontana et al., 2012, Leikina et al., 2002). Second, despite a high degree of structural homology within HA subtypes, examination of HA sequences does not reveal totally conserved titratable residues (Zhou et al., 2014, Mair et al., 2014). Third, membrane fusion happens at different pH ideals for different HA subtypes (Scholtissek, 1985, Puri et al., 1990, Korte et Rabbit Polyclonal to VAV3 (phospho-Tyr173) al., 2007). Fourth, mutagenesis studies possess ... This free online seminar addresses various ways in which temperature impacts pH measurements and discusses temperature compensation during calibration of instruments with buffers and measurement of pH in samples. Effect of Intraluminal pH on the Absorption of Pteroylmonoglutamic Acid: The administration of pteroylmonoglutamic acid and either sodium bicarbonate or phenyto A base is also called alkaline, is the opposite of an acid. Some examples of a base substance are baking soda and ammonia. The body needs balance to function optimally, but the number 7 is not necessarily the magic number for all parts of the body. Inside, the bodys biochemical environment prefers to be on the slightly more on the alkaline side. The optimal measurement here actually is 7.39.. The blood however, functions properly only as long as the pH measurement falls within the range of 7.36 (a bit more acidic) to 7.45 (a bit more alkaline). This range of 7.36 and 7.45 is vital to persons well being. The body will go through great lengths to maintain the appropriate, slightly alkaline, nature of its internal environment. Measurements outside this range significantly compromise the bloods ability to function properly and can even result in death.. Alkalosis results when the bloods pH measurement falls between 7.42 and 7.8. Acidosis results when the bloods pH measurement ranges from 7 to ... 1) solvent phase , 2) aqueous phase , 3) precipitates , 4) both ( and ( Four WIN compounds with anti-picornavirus activities were tested for their ability to stabilize human rhinovirus serotype 2 (HRV-2) against low pH-induced conformational changes in vitro, as determined by specific immunoprecipitation. These results were compared to the minimal inhibitory concentration (MIC) as measured in a plaque reduction assay. A direct relationship was observed between the concentration of the compound that prevented the low pH-induced conformational changes and the MIC, indicating that stabilization is an important element in the mode of action of these drugs against HRV-2. The hydrogen ion concentration in the lesions of experimental pneumococcus infection has been estimated directly by pH determinations on exudates from living animals. For indirect evidence of an increase in hydrogen ion concentration within the lesions, the difference in sugar content between exudate and blood from animals with pneumococcus infection has been measured.. With sanguinous exudate from the consolidated lungs of dogs with experimental pneumococcus pneumonia, the findings were not always consistent, but usually there was either direct or indirect evidence of increased hydrogen ion concentration. The physicochemical changes in exudate from animals treated with artificial pneumothorax showed no important differences from those in other specimens. In concurrence with Lords (1, 2) observation of increased acidity in pneumonia exudate obtained at autopsy, sugar concentrations, which are low in the blood, were markedly reduced in exudates from animals which had died of the ... Methanol electro-oxidation reaction over carbon-supported platinum nanoparticles, including methanol adsorption, apparent reaction order and activation energy, in acidic and alkaline media was investigated comparatively. The results show that the rate constant for methanol adsorption in 1 M NaOH is significantly higher than that in 0.5 M H2SO4 at the relatively low potential and the COad removal in alkaline media is easier, due to the availability of oxygen-containing species, than in acidic media at the same potential. The apparent activation energy for the MOR in alkaline media is 25.3-14.6 kJ mol(-1), significantly lower than that in acidic media (34.9-28.5 kJ mol(-1)). The better MOR activity of Pt/C in alkaline media is attributed to the faster methanol adsorption and the availability of oxygen-containing species. Crown Copyright (c) 2012 Published by Elsevier B.V. All rights reserved ... |p|Oxidation of isatins (isatin, 5-methylisatin, 5-bromoisatin and 5-nitroisatin) to their anthranilic acids was performed efficiently with sodium N-chlorobenzenesulfonamide or chloramine-B (CAB) in alkaline medium at 35±0.1°C. The reactions follow identical kinetics for all the isatins, being first-order dependence each in [CAB]o and [Isatin]o and inverse fractional-order on [NaOH]. Addition of halide ions and benzenesulfonamide, reduction product of CAB, do not significantly affect the rate. Variation of ionic strength of the medium had no effect on the rate, while the dielectric effect is negative. The solvent isotope effect was studied using D2O. Activation parameters for the overall reaction have been computed. The rates satisfactorily correlate with the Hammett σ relationship and the reaction constant ρ is −0.31 signifies that electron releasing groups accelerate the reaction while the electron withdrawing groups retard the rate. Values of ΔH≠ and ΔS≠ are linearly Acid-Treated Nickel-Rich Platinum-Nickel Alloys for Oxygen Reduction and Methanol Oxidation Reactions in Alkaline MediaAcid-Treated Nickel-Rich Platinum-Nickel Alloys for Oxygen Reduction and Methanol Oxidation Reactions in Alkaline Media ... Near-neutral electrolytes based on zinc chloride and ammonium chloride are examined for rechargeable zinc-air battery application. The effects of pH value, salt concentration, and polyethylene glycol and thiourea additives are investigated and a chloride electrolyte is developed. The reversible zinc deposition and zinc stripping processes are studied by cyclic voltammetry with rotating-disc electrode technique. The zinc anode and air cathode behaviors in near-neutral chloride electrolyte are characterized by quasi steady-state polarization and impedance spectroscopy. Prototyped zinc-air battery with near-neutral chloride electrolytes can sustain more than 1000 hours and hundreds of discharge-charge cycles with minimized zinc dendrite formation and no carbonate formation problem, under discharge-charge capacity ranging from 20 to 120 mAh. The near-neutral chloride electrolyte provides a safer and more robust alternative to traditional alkaline electrolyte for rechargeable zinc-air batteries. © ... Water pH level is a measure of how acidic the water is. Water is considered acidic if it has a pH level below seven, and it is considered alkaline if it has a pH level above seven. If the water has a pH level of exactly seven, it is considered neutral. A safe pH level range for drinking water is considered to be between six and 8.5.. You may notice some issues with your water if it falls outside the acceptable pH range. For example, water with a high pH level may feel slippery, have a taste similar to baking soda, and leave deposits on your sinks and fixtures. Alkaline water can be caused by mineral deposits such as limestone in groundwater, or contamination of drinking water from wastewater that contains cleaning agents. Water with a low pH level may have a metallic taste, and cause corrosion on your sink and fixtures. Acidic water can be found in areas that are affected by acid rain, and is sometimes found in glacier water due to dissolved carbon dioxide. The EPA also warns that drinking ... We have used Thomas-type recessed-tip pH-sensitive microelectrodes to measure the intracellular pH (pHi) in Xenopus eggs during both fertilization and ionophore activation. The average pHi in unfertilized eggs is 7.33 +/- 0.11 (SD; n = 21) with a resting membrane potential of -10.1 +/- 3.5 (SD; n = 38) mV. Within 2 min after the onset of the fertilization potential, there is a slight, transient pHi decrease of 0.03 +/- (SD, n = 8), followed by a distinct, permanent pHi increase of 0.31 +/- 0.11 (SD; n = 7) beginning approximately 10 min after the start of the fertilization potential and becoming complete approximately 1 h later. The pHi remains near this level of 7.67 +/- 0.13 (SD, n = 10) through at least 10 cleavage cycles, but it is possible to discern pHi oscillations with a mean amplitude of 0.03 +/- 0.02 (SD, n = 38). Eggs perfused for at least 2 h in Na+-free solution with 1 mM amiloride exhibited all of these pHi changes, so these changes do not require extracellular Na+. Similar ... Strong ions are cations and anions that exist as charged particles dissociated from their partner ions at physiologic pH. The SID (Strong Ion Difference) is the difference between the positively- and negatively-charged strong ions in plasma. This method of evaluating acid-base disorders was developed to help determine the mechanism of the disorder rather than simply categorizing them into metabolic vs. respiratory acidosis/alkalosis as with the Henderson-Hasselbalch equation. Strong cations predominate in the plasma at physiologic pH leading to a net positive plasma charge of approximately +40: SID = [strong cations] - [strong anions] = [Na+ + K+ + Ca2+ + Mg2+] - [Cl- + lactate- + SO42-] Disturbances that increase the SID increase the blood pH while disorders that decrease the SID lower the plasma pH. According to the law of electroneutrality the sum of positive charges is equal to the sum of negative charges. Therefore the SID must be equal to the sum of weak anions in the body (such as ... Spawning market squid lay embryo capsules on the seafloor of the continental shelf of the California Current System (CCS), where ocean acidification, deoxygenation and intensified upwelling lower the pH and [O2]. Squid statolith geochemistry has been shown to reflect the squids environment (e.g., seawater temperature and elemental concentration). We used real-world environmental levels of pH and [O2] observed on squid-embryo beds to test in the laboratory whether or not squid statolith geochemistry reflects environmental pH and [O2]. We asked whether pH and [O2] levels might affect the incorporation of element ratios (B:Ca, Mg:Ca, Sr:Ca, Ba:Ca, Pb:Ca, U:Ca) into squid embryonic statoliths as (1) individual elements and/or (2) multivariate elemental signatures, and consider future applications as proxies for pH and [O2] exposure. Embryo exposure to high and low pH and [O2] alone and together during development over four weeks only moderately affected elemental concentrations of the statoliths, and A preparation of ATPase from the membranes of Micrococcus lysodeikticus, solubilized and more than 95% pure, showed two main bands in analytical polyacrylamide gel electrophoresis. They did not correspond to isoenzymes because one band could be converted into the other by exposure to a mildly alkaline pH value. The conversion was paralleled by changes in molecular weight, circular dichroism and catalytic properties. Denaturation by pH at 25 degrees C was followed by means of circular dichroism, ultracentrifugation and polyacrylamide gel electrophoresis. A large conformational transition took place in the acid range with midpoints at about pH = 3.6 (I = 10(-4) M), 4.3 (I = 0.03 M) and 5.3 (I = 0.1 M). The transition was irreversible. Strong aggregation of the protein occurred in this range of pH. The final product was largely random coil, but even at pH 1.5 dissociation into individual subunits was not complete. However, partial dissociation took place at pH 5 (I = 0.028 M). At this pH value the enzyme Growth of C. thermarum strain TA2.A1 on nonfermentable carbon sources is pH dependent.When strain TA2.A1 was grown in non-pH-controlled batch culture at an initial pH of 7.5 on a nonfermentable carbon source, such as sucrose, glutamate, or succinate, the final pH was always ,9.0 regardless of the carbon source (data not shown). These data demonstrated that the medium used to grow strain TA2.A1, even though strongly buffered (i.e., 100 mM NaHCO3), lacked the necessary buffering capacity to hold the external pH near neutral pH. Uninoculated medium was tested in parallel, and the pH remained unchanged over the same time period of incubation. On the basis of these observations, all growth experiments were performed in pH-controlled batch culture.. The pH limits for growth of strain TA2.A1 were examined using alkaline basal medium supplemented with either succinate, malate, or sucrose under pH-controlled conditions. Strain TA2.A1 grew at a doubling time (td) of 1.5 h in basal medium with no added ... TY - JOUR. T1 - Methods for accelerating nitrate reduction using zerovalent iron at near-neutral pH. T2 - Effects of H2-reducing pretreatment and copper deposition. AU - Liou, Y. H.. AU - Lo, S. L.. AU - Lin, C. J.. AU - Hu, C. Y.. AU - Kuan, W. H.. AU - Weng, S. C.. PY - 2005/12/15. Y1 - 2005/12/15. N2 - Both surface treatments, H2-reducing pretreatment at 400 °C and the deposition of copper as a catalyst, were attempted to enhance the removal of nitrate (40 (mg N) L-1) using zerovalent iron in a HEPES buffered solution at a pH of between 6.5 and 7.5. After the iron surface was pretreated with hydrogen gas, the removal of the passive oxide layers that covered the iron was indicated by the decline in the oxygen fraction (energy dispersive X-ray analysis) and the overlap of the cyclic polarization curves. The reaction rate was doubled, and the lag of the early period disappeared. Then, the deposition of copper onto freshly pretreated iron promoted nitrate degradation more effectively than that ... SUMMARY: Upon repeated subculture in media of gradually increasing pH value a strain of Bacillus cereus developed the ability to grow under strongly akaline conditions. Organisms with the highest alkali resistance could grow at pH 10·3, and stocks of intermediate resistance were also obtained. When growing on alkaline agar, resistant bacteria underwent marked morphological changes. In liquid media, the bacteria retained the ability to synthesize lecithinase. Resistance was not lost upon several transfers on a neutral medium. Resistant bacteria when growing in alkaline media caused a rapid decrease in pH value. A similar pH decrease was caused by sensitive bacteria in media of the highest degree of alkalinity in which they could grow. The decline of pH value accompanied, but did not precede, growth; acid production by the resistant bacteria does not appear to be a primary mechanism of resistance. In the Bochevarov et al. implementation the user defines the titrateable group for which the apparent pKa is computed. However, in my approach all possible protonation states so the assignment of the apparent pKa value to a particular ionizable group is not immediately obvious. Inspection of Eq$\ref{eqn:pkapp}$shows that the largest microscopic pKa values will dominate the sum over$N$, while the smallest of these maximum pKa values will dominate the sum over$M$. Thus, the apparent pKa is assigned to the functional group corresponding to the microscopic ... In the Bochevarov et al. implementation the user defines the titrateable group for which the apparent pKa is computed. However, in my approach all possible protonation states so the assignment of the apparent pKa value to a particular ionizable group is not immediately obvious. Inspection of Eq$\ref{eqn:pkapp}$shows that the largest microscopic pKa values will dominate the sum over$N$, while the smallest of these maximum pKa values will dominate the sum over$M\$. Thus, the apparent pKa is assigned to the functional group corresponding to the microscopic ...
Semantic Scholar extracted view of Blood and erythrocyte hydrogen ion concentrations in acid-base imbalance from respiratory disorders. by A. Rizzo et al.
This is 100th anniversary of the glass pH electrode yet we still do not know much about what affects their life. Not much has been published about application problems and practices. There have been a few academic studies on the effect of process conditions on the glass electrode but these are over 20 years old. The best book on the theory of pH measurement The Determination of pH is over 35 years old. The glass electrode is more important than ever because of its extraordinary rangeability and sensitivity to hydrogen ion concentration. What other measurement can cover 14 orders of magnitude of concentration and detect changes as small as 0.00000000000001 (0 to 14 pH scale).. While the fundamentals of the glass pH electrode have not changed in a hundred years, there have been significant improvements in the glass formulation and construction so that it can handle high pH and high temperature fluids and repeated sterilizations. For example a new high temperature electrode increases the life ...
The kinetics of the auto-oxidation of 2-aminophenol (OAP) to 2-amino-phenoxazin-3-one (APX) was followed in air-saturated aqueous solutions and the influence of temperature and pH on the auto-oxidation rate was studied. The kinetic analysis was based on a spectrophotometric method following the increase of the absorbance of APX. The process follows first order kinetics according to the rate law-d[OAP]/dt=k′[OAP]. The experimental data, within the pH range 4-9.85, were analyzed using both differential and incremental methods. The temperature variation of the overall rate constant was studied at pH=9.85 within the range 25-50°C and the corresponding activation energy was evaluated ...
A robust pH sensor from Endress+Hauser can now solve the problem of reference contamination commonly experienced during pH measurement in ultra harsh conditions such as mining slurries and paper & pulp applications.. pH measurement within ultra harsh applications that include high solid content poses several challenges. Because of the harmful ions that defuse into the pH electrode reference system and the high solid content, the potential to disable the electrode by blocking the diaphragm under these extreme conditions is high. The surface area of the pH electrode diaphragm therefore needs to be enlarged to avoid blockage. However this increases the risk of reference contamination as the diaphragm is porous and more harmful ions can now enter the reference system of the pH electrode.. Traditionally, these enlarged diaphragms have been made from wood due to its resistance to contamination, but the wooden diaphragm is relatively thick and slows down the electrodes response time. In most critical ...
TY - GEN. T1 - Respiration gating and Bloch fitting improve pH measurements with acidoCEST MRI in an ovarian orthotopic tumor model. AU - Jones, Kyle M.. AU - Randtke, Edward A.. AU - Howison, Christine M.. AU - Pagel, Mark Marty. PY - 2016. Y1 - 2016. N2 - We have developed a MRI method that can measure extracellular pH in tumor tissues, known as acidoCEST MRI. This method relies on the detection of Chemical Exchange Saturation Transfer (CEST) of iopamidol, an FDA-approved CT contrast agent that has two CEST signals. A log10 ratio of the two CEST signals is linearly correlated with pH, but independent of agent concentration, endogenous T1 relaxation time, and B1 inhomogeneity. Therefore, detecting both CEST effects of iopamidol during in vivo studies can be used to accurately measure the extracellular pH in tumor tissues. Past in vivo studies using acidoCEST MRI have suffered from respiration artifacts in orthotopic and lung tumor models that have corrupted pH measurements. In addition, the ...
AWV #17B: In this experiment, you will Use a Gas Pressure Sensor to measure the production of oxygen gas as hydrogen peroxide is destroyed by the enzyme catalase or peroxidase at various enzyme concentrations. Measure and compare the initial rates of reaction for this enzyme when different concentrations of enzyme react with H2O2. Measure the production of oxygen gas as hydrogen peroxide is destroyed by the enzyme catalase or peroxidase at various temperatures. Measure and compare the initial rates of reaction for the enzyme at each temperature. Measure the production of oxygen gas as hydrogen peroxide is destroyed by the enzyme catalase or peroxidase at various pH values. Measure and compare the initial rates of reaction for the enzyme at each pH value.
API Freshwater/Saltwater High Range pH Test Kit, Test kit of 250 tests Use to measure pH changes in marine aquariums, aquariums with African cichlids, and very alkaline tap water. Reads the pH of water within the high range of 7.4 to 8.8.250 tests per kit.Freshwater/Saltwater High Range pH Test Inst
Introduction. How does pH affect the activity of the Amylase? In this investigation I am going to consider how different pH levels will affect the rate in which amylase will break down the starch molecules. I will be measuring the time it takes for a yellow brown liquid to be shown, which would show that there is no starch present in the solution because it would have been broken down by amylase in solutions under ph levels. Hypothesis I would expect that when the pH is increasing towards the optimum level the rate of reaction would be at the highest point but when it has reached its optimum level the rate of the activity of the enzyme would decrease. The change in pH would affect the ionisation of the side groups in the enzymes amino acid residues this would then affect the overall shape of the enzyme molecule and would then affect the efficiency of formation of enzyme-substrate complexes. Variables The independent variable is pH as I am adjusting the pH in each experiment, the pHs that are ...
Green colour in green vegetables is due to the presence of a pigment known as chlorophyll, which is affected by pH. In an acid medium the colour of a green vegetable changes to olive green and in alkaline medium it changes to bright green. This is the reason why some cooks add cooking soda or any other alkaline medium while cooking greens. When a green vegetable is cooked covered, the plants natural acid is leached into the cooking liquid and is trapped there creating an acidic cooking medium. This, combined with the heat present, destroys the pigment. Green vegetables should also be cooked uncovered so that the natural acids present, are expelled into the air. ...
We used the pH-sensitive fluorescent dye BCECF to study intracellular pH (pHi) regulation in primary cultures of rat astrocytes and C6 glioma cells. Both cell types contain three pH-regulating transporters: (1) alkalinizing Na+/H+ exchange; (2) alkalinizing Na+ + HCO3 −/Cl−exchange; and (3) acidifying Cl−/HCO3− exchange. Na+/H+ exchange was most evident in the absence of CO2; recovery from acidification was Na+ dependent and amiloride sensitive. Exposure to CO2 caused a cell alkalinization that was inhibited by DIDS, dependent on external Na+, and inhibited 75% in the absence of Cl− (thus mediated by Na+ + HCO3−/Cl− exchange). When pHi was increased above the normal steady-state pHi, a DIDS-inhibitable and Na+ -independent acidifying recovery was evident, indicating the presence of Cl− /HCO3−exchange. Astrocytes, but not C6 cells, contain a fourth pH-regulating transporter, Na+ −HCO3− cotransport; in the presence of CO2, depolarization caused an alkalinization of 0.12 +− 0.01 (n
The effect of pH on the formation of biogenic amines has mainly been studied in broths in which pH has been fixed before incubation. However, in the fermentation of dry sausage, pH quite rapidly decreases from the initial value to a certain level. In this study glucono-delta-lactone (GDL) was used to decrease pH in meat, Six minced meat samples were each divided into three portions (A-C): 0% (A), 0.5% (B), or 1.0% (C) of GDL was added and the samples were incubated at 20-22°C for 7 d. The amounts of biogenic amines (histamine, tyramine, putrescine, cadaverine, phenylethylamine, tryptamine, spermine, and spermidine) as well as pH, water activity, and the bacterial counts of lactic acid bacteria, fecal streptococci, coliforms, and total plate count were measured. Addition of GDL resulted in a significant decrease in pH and in the levels of histamine and putrescine as well as in the levels of fecal streptococci, coliforms, and total plate counts. Of 87 fecal streptococci, seven Enterococcus ...
Carbon-14 (radiocarbon, 14C) is a long-lived radionuclide (5730 yr) of interest regarding the safety for the management of intermediate level wastes (ILW). The present study gives an overview of the release of 14C from irradiated Zircaloy cladding in alkaline media. 14C is found either in the alloy part of Zircaloy cladding due to the neutron activation of 14N impurities by 14N(n,p)14C reaction, or in the oxide layer (ZrO2) formed at the metal surface by the neutron activation of 17O from UO2 or (U-Pu)O2 fuel and water from the primary circuit in the reactor by 17O(n,α)14C reaction. Various irradiated and unirradiated Zircaloys have been studied. The total 14C inventory has been determined both experimentally and by calculations. The results seem to be in good agreement. Leaching experiments were conducted in alkaline media for several time durations. 14C was mainly released as carboxylic acids. Further, corrosion measurements were performed by using both hydrogen measurements and ...
Table 1: |i|N|/i|-Terminal Region of GbIspH1, |i|Ginkgo biloba|/i| IspH Type 1, May Be Involved in the pH-Dependent Regulation of Enzyme Activity
TY - JOUR. T1 - Administration and 1H MRS, detection of histidine in human brain. T2 - Application to in vivo pH measurement. AU - Vermathen, Peter. AU - Capizzano, Aristides A.. AU - Maudsley, Andrew A.. PY - 2000/5/17. Y1 - 2000/5/17. N2 - Measurement of histidine in vivo offers the potential for tissue pH measurement using routinely performed 1H MR spectroscopy. In the brain, however, histidine concentrations are generally too low for reliable measurement. By using oral loading of histidine, this study demonstrates that brain concentrations can be significantly increased, enabling detection of histidine by localized 1H MR measurements and making in vivo pH measurement possible. In studies carried out on healthy human subjects at 1.5 T, a consistent spectral quality downfield from water was achieved using a PRESS sequence at short echo times. Measurements at different TE values helped to characterize the downfield spectral region. Histidine loading of 400 mg/kg of body weight increased brain ...
E+h Ph Meter, Wholesale Various High Quality E+h Ph Meter Products from Global E+h Ph Meter Suppliers and E+h Ph Meter Factory,Importer,Exporter at Alibaba.com.
What Is The pH Meter Principle? Working principle of pH sensor electrode and pH meter used in quality control and manufacturing area. A pH meter is used to determine the acidity or alkalinity of the solution. pH is the concentration of hydrogen ions in the solution. A solution containing more H+ ions
ABSTRACT: Spironucleus vortens were cultivated in either an artificial medium at different temperatures, or in medium at various pH conditions or supplemented with different bile concentrations at 25°C. Temperature, pH and bile requirements for the optimal growth of the parasite were determined. Parasites multiplied quickly at 28 and 31°C and reached maximum numbers on Day 4 of cultivation, whereafter they did not survive. At 25°C, parasites survived longer than those at 28 and 31°C with no difference in multiplication rate during the exponential phase. The longest survival period was seen at 22°C, although the growth rate of the parasite was not as high as those at 25°C. At a higher temperature of 37°C, no parasites were observed alive after the second day of cultivation. Optimal pH range for the parasite¹s growth was 6.5 to 7.5, with the highest cell number at pH 7.5. Parasites survived longest (15 d) at pH 6.0, although the maximum number of cells was lower than those at the optimal ...
The link between cancer metabolism and immunosuppression, inflammation and immune escape has generated major interest in investigating the effects of low pH on tumor immunity. Indeed, microenvironmental acidity may differentially impact on diverse components of tumor immune surveillance, eventually contributing to immune escape and cancer progression. Although the molecular pathways underlying acidity-related immune dysfunctions are just emerging, initial evidence indicates that antitumor effectors such as T and NK cells tend to lose their function and undergo a state of mostly reversible anergy followed by apoptosis, when exposed to low pH environment. At opposite, immunosuppressive components such as myeloid cells and regulatory T cells are engaged by tumor acidity to sustain tumor growth while blocking antitumor immune responses. Local acidity could also profoundly influence bioactivity and distribution of antibodies, thus potentially interfering with the clinical efficacy of therapeutic antibodies
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Two nanofiltration membranes, a Dow NF 270 polyamide thin film and a TriSep TS 80 polyamide thin film, were investigated for their retention of ionic species when filtering mine influenced water streams at a range of acidic pH values. The functional iso-electric point of the membranes, characterized by changes in retention over a small pH range, were examined by filtering solutions of sodium sulphate. Both membranes showed changes in retention at pH 3, suggesting a zero net charge on the membranes at this pH. Copper mine drainage and synthetic solutions of mine influenced water were filtered using the same membranes. These solutions were characterized by pH values within 2 and 5, thus crossing the iso-electric point of both membranes. Retention of cations was maximized when the feed solution pH was less than the iso-electric point of the membrane. In these conditions, the membrane has a net positive charge, reducing the transmission rate of cations. From the recoveries of a range of cations, the ...
Alkaline protease from Bacillus amyloliquefaciens SP1 has been characterized in detail for its ecofriendly application of release of silver particles from gelatin layers of used X-ray films. It exhibited optimum activity at broad temperature range and maximum at 60⁰C under alkaline pH environment (8-12). Thermal inactivation of the crude enzyme followed ﬁrst order kinetics. The half-life of the enzyme at 50, 60 and 65⁰C was 70, 15 and 12.6 min, respectively and the denaturation energy was 114.87 kJ/mol. Enzyme retained 53.83 and 108.33% of its initial activity after heating for 15 min at pH 8.0 and temperature 60⁰C, in presence and absence of 10 mM MnSO4, respectively. Enzymatic decomposition of gelatin layers was enhanced by increase of enzyme concentration from 38 to 3630 µg/ml/min, at 60⁰C and pH 8.0. This study reported the shortest time of 1.30 min at 3630 µg/ml/min and 4 : 30 min at 74 µg/ml/min of enzyme concentration for hydrolysis of gelatin layers. Keeping in mind that, ...
Dr. William Kelly, author, Cancer Cure.. Over the past decade, there has been a growing interest in alkaline diets and living an alkaline lifestyle. Part of this interest may involve drinking alkaline, ionized water from a water ionizer as a way to improve wellness, enhance performance, and prolong vitality. Alkaline, ionized water is water that has been selectively altered in a water ionizer to raise pH from neutral to pH 9 or more and also to display negative change (-ORP). Water above a pH 7 is alkaline and water below pH 7 is acidic. pH can be easily measured by using pH reagent or a meter, and ORP is measured using an ORP meter.. Life on earth depends on appropriate pH levels in and around living organisms and cells. Human life requires a tightly controlled pH level in the serum of about 7.4 (a slightly alkaline range of 7.35 to 7.45) to survive. The ability of the body to maintain this level of pH can be compromised by poor diet, lack of or excessive exercise, pollutants, dehydration, and ...
What other measures or recommendations should be taken in order to minimize the risk of corrosion?. As we have seen, the extraordinary alloy combination design and manufacturing process of CLIMETALs coils assure a very low risk of corrosion. However, you should also think of your HVAC unit as a whole. Once we understand the nature of aluminum and how galvanic corrosion works there are some simple rules you should take into account to make your coils last for years:. 1. Avoid extreme pH environments.. 2. Avoid contact between aluminum and other metals by using some plastic, rubber or polymer washers. Be aware that there are some materials that have a high metal content like pressure treated wood (plywood) and concrete.. 3. Avoid grounding electrical circuits to aluminum coils. Make sure your AC systems are completely ground isolated and that there is no electrical derivation going through the coil.. 4. Cleaning: Pollutants with extreme pH levels can attack the aluminum oxide layer. Therefore, ...
1. It is well known that neutral salts depress the osmotic pressure, swelling, and viscosity of protein-acid salts. Measurements of the P.D. between gelatin chloride solutions contained in a collodion bag and an outside aqueous solution show that the salt depresses the P.D. in the same proportion as it depresses the osmotic pressure of the gelatin chloride solution.. 2. Measurements of the hydrogen ion concentration inside the gelatin chloride solution and in the outside aqueous solution show that the difference in pH of the two solutions allows us to calculate the P.D. quantitatively on the basis of the Nernst formula. See PDF for Equation. if we assume that the P.D. is due to a difference in the hydrogen ion concentration on the two sides of the membrane.. 3. This difference in pH inside minus pH outside solution seems to be the consequence of the Donnan membrane equilibrium, which only supposes that one of the ions in solution cannot diffuse through the membrane. It is immaterial for this ...
Experimental Methods.Microsomal binding incubations. Microsomal binding in human liver microsomes was performed in triplicate using a 96-well equilibrium dialysis as adapted from a previous described method (Banker et al., 2003). Each dialysis membrane strip was conditioned sequentially for 15 min in deionized water, 30% ethanol, and then 0.1 M potassium phosphate buffer, pH 7.4. A conditioned membrane strip was then loaded into a 96-well dialysis apparatus. Experimental compound was diluted in dimethyl sulfoxide to a concentration of 100 μM. Human liver microsomes were thawed and diluted with 0.1 M potassium phosphate buffer (pH 7.4) to a final protein concentration of 0.76 mg/ml. Experimental compound was then further diluted 100-fold to yield 1 μM final concentration with the diluted microsomal solution. The compound and microsomes were thoroughly mixed, and 150 μl of the resulting solution was added to one side of the dialysis well as a donor side and 20 μl of this solution was retained ...
1. Interactions of proteins with neutral polysaccharides and such polyacids as polygalacturonic acid, chondroitin sulphate, RNA and DNA in a two-phase system composed of phenol and aqueous buffers in the
The hydrolysis rate of dodecamethylcyclohexasiloxane (D6) has been estimated using two different methods (Dow Corning Corporation, 2009). In the first method, acid and alkali catalysed rate constants were extrapolated from reliable measured data for the related siloxanes hexamethylcyclotrisiloxane (D3), octamethylcyclotetrasiloxane (D4) and decamethylcyclopentasiloxane (D5). The rate constants at pH 4, 7 and 9 were then calculated using the equation: k(pred)/h-1= K(H+)[H+] + k(-OH)[-OH] Hydrolysis half-lives of 42 h at pH 4, 401 d (approximately 9600 h) at pH 7 and 125 h at pH 9 and 25°C were determined. In the second method, screening experiments were carried out at elevated temperature and basic pH (40°C and pH 10, and 60°C and pH 9). A hydrolysis half-life of 4600-7500 h at pH 9 was determined; half-lives at pH 4 and 7 could not be determined using the data from this method. The two results obtained by method 2 were in reasonable agreement with each other but differ significantly from the ...
FracBlack® Near-neutral buoyancy proppant (NBP) is designed for stimulation of unconventional wells to provide significantly greater fracture conductivity via unparalleled proppant placement in the far field fracture area and improved reservoir contact. FracBlack® is an advanced thermoset nanocomposite bead, featuring near-neutral buoyancy, high strength and thermal stability for application in most reservoirs with or without conventional proppants. This breakthrough NBP provides technical resolution to the primary limitations which impair conventional proppant placement and performance. The high strength and near-neutral specific gravity of FracBlack® NBPis designed to optimize proppant transport, placement, and conductivity longevity allowing you to Prop What You Frac.. Utilization: FracBlack® NBPis used to provide effective propped fracture conductivity throughout the fracture network due to the materials low specific gravity and near-neutral buoyancy in water-based fluids. The ...
FracBlack® Near-neutral buoyancy proppant (NBP) is designed for stimulation of unconventional wells to provide significantly greater fracture conductivity via unparalleled proppant placement in the far field fracture area and improved reservoir contact. FracBlack® is an advanced thermoset nanocomposite bead, featuring near-neutral buoyancy, high strength and thermal stability for application in most reservoirs with or without conventional proppants. This breakthrough NBP provides technical resolution to the primary limitations which impair conventional proppant placement and performance. The high strength and near-neutral specific gravity of FracBlack® NBPis designed to optimize proppant transport, placement, and conductivity longevity allowing you to Prop What You Frac.. Utilization: FracBlack® NBPis used to provide effective propped fracture conductivity throughout the fracture network due to the materials low specific gravity and near-neutral buoyancy in water-based fluids. The ...
The question of bioaccessibility of nutrients within a food matrix has become of increasing interest in the fields of nutrition and food science as bioaccessibility is the precursor to bioavailability. By analyzing the propagation of the wetting front of acidic water in raw carrot core and Edam cheese as model systems, we show that the diffusion of the acidic water is dependent on the pH of the gastric fluid and the food matrix. In addition, we demonstrate that the diffusion of NaCl during cheese brining is also dependent upon the concentration of the NaCl. This demonstrates that Fickian diffusion, along with a concentration dependent diffusion coefficient, is a valid model for describing concentration profiles in multiple food systems.Utilizing the diffusion rates found at various pH levels (1.50, 2.00, 3.50, 4.30, 5.25 and 7.00), we developed a model to describe the measured non-linear rate of soluble solid loss during digestion at various constant pH levels. Additionally, we have developed a ...
1. It is shown that a neutral salt depresses the potential difference which exists at the point of equilibrium between a gelatin chloride solution contained in a collodion bag and an outside aqueous solution (without gelatin). The depressing effect of a neutral salt on the P.D. is similar to the depression of the osmotic pressure of the gelatin chloride solution by the same salt.. 2. It is shown that this depression of the P.D. by the salt can be calculated with a fair degree of accuracy on the basis of Nernsts logarithmic formula on the assumption that the P.D. which exists at the point of equilibrium is due to the difference of the hydrogen ion concentration on the opposite sides of the membrane.. 3. Since this difference of hydrogen ion concentration on both sides of the membrane is due to Donnans membrane equilibrium this latter equilibrium must be the cause of the P.D.. 4. A definite P.D. exists also between a solid block of gelatin chloride and the surrounding aqueous solution at the ...