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Abstract: The effect of chickpea processing (i.e. defatting, isoelectric precipitation vs ultrafiltration/diafiltration) on the composition, protein recovery and antinutritional factors of protein concentrates was studied for two varieties (Mylese and Xena). Defatting did not affect significantly the content of antinutritional factors in the flours. However, production of concentrates from defatted flours by isoelectric precipitation resulted in higher phosphorous and phenolic contents compared to the concentrates produced by the same process using the full fat flours as starting material, while trypsin inhibitor content was not affected. When processed by ultrafiltration/diafiltration, protein concentrates produced from defatted flour showed a slightly lower trypsin inhibitor content than the ones produced from full fat flours in most cases, while the inverse was true for the phosphorous content, and for the phenolic content; this effect was a function of chickpea variety. Overall, UF pH 9/DF pH 6 resulted in concentrates with the lowest phosphorous content, while isoelectric precipitation and UF pH 9/DF pH 9 resulted in concentrates with lower phenolic content compared to the ones produced by UF pH 9/DF pH 6; for both processes the trypsin inhibitor content of the concentrates remained high. Industrial relevance: Chickpea production is one of the major agricultural sectors of significant importance to Canada. Although chickpeas are grown in Canada for export, very little is exported in the value-added or processed form. Development of new extraction technologies and value-added products such as the ones presented in this paper is of interest for Canada since it would have a significant impact on the growth of the industry domestically, thus, creating opportunities to strengthen rural development in Canada. Successful implementation of these technologies would make interested Canadian companies viable competitors in the global plant protein production industry and would put Canada in a good position to enjoy a large share of this market both locally and internationally. More specifically, we are the first research group to compare the use of isoelectric precipitation and ultrafiltration/diafiltration for the production of chickpea protein concentrates from full fat and defatted flours of Kabuli and Desi chickpea variety, and to quantify the effect of these processes on the composition and on the antinutritional factors (i.e. phytic acid, total phenolics and trypsin inhibitors) of the resulting concentrates. Overall, it was observed that isoelectric precipitation was effective to an extent in producing concentrates with low phosphorous and phenolic contents. UF pH 9/DF pH 9 was also effective to an extent in producing concentrates with low phenolic content, while UF pH 9/DF pH 6 was more efficient in producing concentrates with low phosphorous content. High-quality chickpea protein concentrates with improved nutritional properties and good functional properties could beneficially be combined with other protein sources, such as soy protein, or be used in the formulation of foods, such as meat analogues, dairy, and bakery products. [Copyright &y& Elsevier]

We used a combination of 16S rRNA gene clone library surveys, quantitative PCR (qPCR) analysis, and fluorescent in situ hybridization to investigate the diversity, abundance, and distribution of members of candidate division SR1 in multiple habitats. Using SR1-specific 16S rRNA gene primers, we identified multiple novel SR1 lineages in four different anaerobic environments: sediments from Zodletone Spring, a sulfide- and sulfur-rich spring in southwestern Oklahoma; inner layers of microbial mats obtained from Sperm Pool, a high-temperature, low-pH pool (55°C, pH 2.5) in Yellowstone National Park; fresh bovine ruminal contents; and anaerobic freshwater pond sediments (Duck Pond) in Norman, Oklahoma. qPCR analysis indicated that SRi members constitute a small fraction (<0.01%) of the microbial communities in Duck Pond and ruminal samples but constitute a significant fraction (11.6 and 48.7%) of the total number of bacterial 16S rRNA genes in Zodletone Spring and the inner layers of Sperm Pool microbial mat samples, respectively. By using SR1-specific fluorescent probes, filamentous cells were identified as the sole SR1 morphotype in all environments examined, with the exception of Sperm Pool, where a second bacillus morphotype was also identified. Using a full-cycle 16S rRNA approach, we show that each of these two morphotypes corresponds to a specific phylogenetic lineage identified in the Sperm Pool clone library. This work greatly expands the intralineage phylogenetic diversity within candidate division SR1 and provides valuable quantification and visualization tools that could be used for investigating the ecological roles, dynamics, and genomics of this as-yet-uncultured bacterial phylum. [ABSTRACT FROM AUTHOR]

Abstract: Benzaldehyde lyase from Pseudomonas fluorescens (BAL, EC 4.1.2.38) is a versatile catalyst for stereoselective carboligations. Nevertheless, rather inconsistent data about its biochemical properties are reported in literature. In this study, the dependency of BAL activity on ionic strength, pH, and concentration of DMSO was for the first time systematically investigated and interpreted. It was found that the activity of BAL strongly depends on all three parameters, and a correlation exists between the dependency on pH and DMSO concentration. This correlation could be explained by an interaction of DMSO with an ionic amino acid in the catalytic site. A model-based analysis indicated that the pKa of this residue shifts to the alkaline milieu upon addition of DMSO. Consequently, the optimum pH also shifts to alkaline values when DMSO is present. Potentiometric experiments confirmed that the pKa can most probably be attributed to Glu50 which governs the activity increase of BAL on the acidic limb of its pH-activity profile. With these findings, the apparently contradicting data from literature become comprehensible and optimal reaction conditions for synthesis can easily be deduced. [Copyright &y& Elsevier]

Abstract  Carbon paste electrode modified with aminated Mobil Catalytic Material Number 41 (MCM-41) was prepared and used for immobilization of K3[Fe(CN)6] in acidic medium, and then electrochemical behavior of modified electrode containing ferricyanide was studied in detail, including pH-dependence and scan rate effect. Cyclic voltammetry studies showed that the electrode reaction is a surface-controlled process at the scan rate range from 5 to 60 mV s−1. Also, the electrocatalytic behavior of modified electrode toward the reduction of H2O2 is reported and the effect of pH on catalytic peak current was discussed. According to experimental results, with increasing solution pH, the catalytic effect of this modified electrode is decreased. Catalytic reduction current of H2O2 increases linearly with its concentration. It has been demonstrated that ferricyanide immobilized on the aminated MCM-41 is a stable catalyst for the electrocatalytic reduction of H2O2. [ABSTRACT FROM AUTHOR]

Abstract: Fenton reaction is thought to play an important role in wood degradation by brown-rot fungi. In this context, the effect of oxalic acid and pH on iron reduction by a biomimetic fungal chelator and on the adsorption/desorption of iron to/from wood was investigated. The results presented in this work indicate that at pH 2.0 and 4.5 and in the presence of oxalic acid, the phenolate chelator 2,3-dihydroxybenzoic acid (2,3-DHBA) is capable of reducing ferric iron only when the iron is complexed with oxalate to form Fe3+-mono-oxalate (Fe(C2O4)+). Within the pH range tested in this work, this complex formation occurs when the oxalate:Fe3+ molar ratio is less than 20 (pH 2.0) or less than 10 (pH 4.5). When aqueous ferric iron was passed through a column packed with milled red spruce (Picea rubens) wood equilibrated at pH 2.0 and 4.5, it was observed that ferric iron binds to wood at pH 4.5 but not at pH 2.0, and the bound iron could then be released by application of oxalic acid at pH 4.5. The release of bound iron was dependent on the amount of oxalic acid applied in the column. When the amount of oxalate was at least 20-fold greater than the amount of iron bound to the wood, all bound iron was released. When Fe–oxalate complexes were applied to the milled wood column equilibrated in the pH range of 2–4.5, iron from Fe–oxalate complexes was bound to the wood only when the pH was 3.6 or higher and the oxalate:Fe3+ molar ratio was less than 10. When 2,3-DHBA was evaluated for its ability to release iron bound to the milled wood, it was found that 2,3-DHBA possessed a greater affinity for ferric iron than the wood as 2,3-DHBA was capable of releasing the ferric iron bound to the wood in the pH range 3.6–5.5. These results further the understanding of the mechanisms employed by brown-rot fungi in wood biodegradation processes. [Copyright &y& Elsevier]

This article reviews a number of studies over the last decades, which may contribute to a more coherent understanding of the complicated thermal behaviour of β-lactoglobulin during heat treatments at pH>6.8. Many research papers on β-lacto-globulin ignore studies published before the digital period, which means that useful information from the past has been lost or is repeated. In this review results of former studies are compared with recent research data in order to get a more complete and consistent overview over the temperature range up to 150°C. All results indicate that the dissociation and conformational changes are reversible after heat treatments up to 60°C. Irreversible modifications of monomers appear between 60 and 70°C, starting as a slight conformational change, called the “molten globule state”. Increased exposure of thiol groups at temperatures between 65 and 75°C causes small oligomers mainly by oxidation of the thiols. Thiol/disulphide exchange reactions dominate between 75 and 85°C (at pH>7.0), and aspecific non-covalent aggregation induces larger aggregates. The formation of large aggregates is prevented at temperatures between 85 and 105°C, followed by fast cooling. Unfolding of residual structures of β-lactoglobulin is observed above 125°C, possibly induced by the chemical breakdown of disulphide bonds. [Copyright &y& Elsevier]

Abstract  Solid-contact electrode for pH measurements in acidic media is described. The sensor membrane is made of polyvinyl chloride plasticized with bis(2-ethylhexyl)phthalate and contains neutral pH-selective ionophore hexabutyltriamidophosphate and potassium tetrakis-p-Cl-phenylborate cation exchanger. The transducer layer of the solid-contact electrode contains the same membrane composition and also carbon black and electron–ion-exchanger resin EI-21(a cation exchange resin containing fine dispersion of metal copper) for stabilization of the electrode potential. The electrode is suitable for measurements of pH in the range 0–6 and works also in hydrofluoric acid (HF) solutions up to 0.1 M HF. Chronopotentiometric measurements show diffusion-limited polarization at the interface between sensor membrane and transducer layer. The slope of the linearized polarization curve correlates with the long-term stability of the electrode potentials providing a tool for prediction of the long-term stability of solid-contact potentiometric sensors. [ABSTRACT FROM AUTHOR]

AbstractThe biochemical properties of the digestive alpha-amylase from Tecia solanivoralarvae, an important and invasive insect pest of potato (Solanum tuberosum), were studied. This insect has three major digestive ?-amylases with isoelectric points 5.30, 5.70 and 5.98, respectively, which were separated using native and isoelectric focusing gels. The alpha-amylase activity has an optimum pH between 7.0 and 10.0 with a peak at pH 9.0. The enzymes are stable when heated to 50?C and were inhibited by proteinaceous inhibitors from Phaseolus coccineus(70% inhibition) and P. vulgariscv. Radical (87% inhibition) at pH 6.0. The inhibitors present in an amaranth hybrid inhibited 80% of the activity at pH 9.0. The results show that the alpha-amylase inhibitor from amaranth seeds may be a better candidate to make genetically-modified potatoes resistant to this insect than inhibitors from common bean seeds. [ABSTRACT FROM AUTHOR]

Abstract: The interest of application of liquid membrane (pertraction) processes for recovery of biosurfactants from aqueous media was demonstrated. Transport of pure surfactin in three-liquid-phase system was studied. Surfactin was successfully extracted from slightly acid media (pH 5.65–6.05) applying batch pertraction in a rotating discs contactor and using n-heptane as liquid membrane. The process efficiency was found to be strongly affected by the feed solution acidity (83% at pHF 6.05 and 97% at pHF 5.65 after 4h pertraction). An atypical pH effect was observed when the behaviour of surfactin extraction from aqueous media by non-polar solvents (n-heptane and n-octane) was studied. The obtained high extraction degrees from both acid and basic media and the clearly reduced degree of extraction from neutral media could be attributed to the different conformations of surfactin in these media. [Copyright &y& Elsevier]

Abstract: The simultaneous formation of mevinolinic acid (lovastatin; antihypercholesterolemia drug) and (+)-geodin (by-product) by Aspergillus terreus ATCC 20542 in the batch and fed-batch cultivation in the stirred tank bioreactor was investigated and described in this paper. The main factors influencing the formation of these two secondary metabolites were the initial nitrogen concentration and the aeration rate of the medium. The experiments aimed at achieving as high as possible lovastatin titre accompanied by as low as possible (+)-geodin concentration. The application of lactose-fed discontinuous fed-batch process allowed increasing lovastatin formation, in comparison with the batch process. Nevertheless (+)-geodin titre increased too. But the control of pH at the levels of 7.6 and 7.8 was successfully applied to repress the formation of the by-product both in batch and fed-batch experiments. Additionally, apart from pH control, the supplementation of the medium with nicotinamide and calcium pantothenate was used to facilitate the formation of lovastatin. The simultaneous pH control and B-group vitamin supplementation allowed achieving the best results in the batch cultivation. [Copyright &y& Elsevier]

Abstract  In this paper, a new highly sensitive potentiometric pH electrode is proposed based on the solid-state PbO2 film electrodeposited on carbon ceramic electrode (CCE). Two different crystal structures of PbO2, α and β were examined and the similar results were obtained. Moreover, the experimental results obtained for the proposed pH sensor and a conventional glass pH electrode were in good agreement. The electromotive force (emf) signal between the pH-sensitive PbO2-coated CCE and SCE reference electrode was linear over the pH range of 1.5–12.5. Near-Nernstian slopes of −64.82 and −57.85 mV/pH unit were obtained for α- and β-PbO2 electrodes, respectively. The interferences of some mono-valence and multi-valence ions on potentiometric response of the sensor were studied. The proposed pH sensor displayed high ion selectivity with respect to K+, Na+, Ca2+, and Li+, with log $$K_{H,M}^{{\text{pot}}} $$ values around −12 and has a working lifetime of about 30 days. Key parameters important for the pH sensor performance, including kind of PbO2 film, selectivity, response time, stability, and reproducibility, have been characterized. The proposed electrode showed a good efficiency for direct pH-metry after calibration and pH-metric titrations without calibration step. The response time was about 1 s in acidic medium and less than 30 s in alkaline solutions. The pH values of complex matrix samples such as fruit juices measured by the proposed sensor and a conventional glass pH electrode were in good agreement. [ABSTRACT FROM AUTHOR]

Abstract: Oyster shell, a byproduct of shellfish-farming in Korea and containing a high amount of CaCO3, has a high potential to be used as a liming material in agriculture. However, the agricultural utilization of oyster shell is limited due to its high concentration NaCl. The oyster-shell meal collected had a low concentration of water soluble NaCl (mean 2.7gkg−1), which might be a result of stacking the material for 6 months in the open field. It has a very similar liming potential with calcium carbonate, with 3.4 and 3.8Mgha−1 for silt loam (SiL, pH 6.2) and sandy loam (SL, pH 5.8) to bring the soil pH to 6.5, respectively. To determine the effect of crushed oyster-shell meal on improving soil chemical and biological properties and crop plant productivity, oyster-shell meal was applied at rates of 0, 4, 8, 12, and 16Mgha−1 before transplanting Chinese cabbage (Brassica campestris L.) in the two soils mentioned above. Soil pH was significantly increased to 6.9 and 7.4 by 16Mgha−1 shell meal application (4 times higher level than the recommendation) in SiL and SL, respectively, at harvesting stage. The effect of liming was found higher in SL compared to SiL soil, probably due to the different buffering capacity of the two soils. The concentration of NaCl and EC value of soils were found slightly increased with shell meal applications, but no salt damage was observed. Oyster-shell meal application increased soil organic matter, available P, and exchangeable cations concentrations. The improved soil pH and nutrient status significantly increased the microbial biomass C and N concentrations and stimulated soil enzyme activities. With the exception of acid phosphomonoesterase (PMEase) activity, which decreased with increasing soil pH in SL but slightly increased in SiL, the activities of urease and alkali PMEase increased markedly with increasing soil pH by shell meal application. The improved soil chemical and biological properties resulted in increased crop productivity. The highest yield in Chinese cabbage was achieved following the application of 8Mgha−1 oyster-shell meal. Conclusively, crushed oyster shell could be used as an alternative liming material to restore the soil chemical and microbial properties in upland soil and to increase crop productivity. [Copyright &y& Elsevier]

A series of new rigid distibines, 1,8-bis(R2Sb)naphthalene (R = Me: (1); R = Ph: (2)), and chiral distibines, 2,2′-bis(R2Sb)-1,1′-binaphthyl (R = Me: (3); R = Ph: (4) obtained as racemic mixtures) and the discrete enantiomers of 4,5-bis((R2Sb)methyl)-2,2-dimethyl-1,3-D/L-dioxolane (R = Me: (5) (l), (7) (d); R = Ph: (6) (l), (8) (d)) have been obtained in high yields, using either electrophilic halostibine reagents with di-lithium reagents ((1)–(4)) or nucleophilic stibide reagents with dibromo-derivatives ((5)–(8)). The distorted octahedral complexes [Mo(CO)4(L)], L = (1)–(8), planar [PtCl2(L)], L = (1), (2), (3), (5), and neutral, five-coordinate [RhCl(cod)(L)], L = (2), (4), (6), are reported and trends in the spectroscopic data are discussed in terms of the ligand donor properties. Crystal structures of (3) and [Mo(CO)4(3)] reveal significant structural changes occur upon coordination, and these are also reflected in the solution NMR spectroscopic parameters. Changes in the C–Sb–C angles and C–Sb bond distances upon coordination of (3) are discussed in term of increased s/p orbital mixing. Air oxidation of (1) forms a very unusual stibine oxide, the structure of which shows a distorted Sb4O4 cubane core (bridging O atoms) with two orthogonal naphthalene units. [ABSTRACT FROM AUTHOR]

To understand the influence of the pH parameter on crystal growth, six compounds prepared at different pH values have been explored, namely {Cu(H2bptc)(bpa)(μ2-H2O)}n(1) {[Cu3(Hbptc)2(bpa)3(H2O)8]·4H2O}n(2), {[Cu2(bptc)(bpa)2(H2O)]·6.5H2O}n(3), {[Mn2(bptc)(bpa) (μ2-H2O)(H2O)5]·H2O}n(4), {[Co2(bptc)(bpe)(μ2-H2O)(H2O)5]·H2O}n(5) and {[Mn2(bptc)(bpe) (μ2-H2O)(H2O)5]·H2O}n(6) (H4bptc = 3,3′,4,4′- benzophenonetetracarboxylic acid, bpa = 1,2-bis(4-pyridy)ethane and bpe = 1,2-bis(4-pyridy)ethene). The structure of 1displays a 3D open rhombic framework based on an infinite metal-aqua chain. Compound 2contains two different motifs: a cationic 1D chain of [Cu(bpa)(H2O)4]2+, and an anionic 2D network of [Cu2(Hbptc)2(bpa)2(H2O)4]2−. Compound 3, a microporous open-framework structure, presents an uncommon 3D, trinodal, 4-connected self-penetrating network. Compounds 4, 5and 6present the same arrangement with 4,6-connected 3D networks. Comparing the experimental results, it is clear that the pH value plays a crucial role in the formation of the resulting structures. The thermal stabilities of compounds 1–6are discussed. The magnetic properties for 2and 4are also studied and they both exhibit a weak antiferromagnetic coupling through the O2C–C–C–CO2bridge and μ2-aqua bridge, respectively. [ABSTRACT FROM AUTHOR]

Abstract: The general objectives of this study were (i) to determine the kinetics and mechanisms of Mn(II) removal from solution by a representative plant-growth substrate; (ii) to assess the role of biotic components on Mn(II) cycling in this system; and (iii) to assess the roles of pH and temperature in determining Mn(II) partitioning between the solution and the solid phases. The Mn(II) solubility in typical growth medium (perlite) was predominantly controlled by pH-dependent reactions, i.e., adsorption and oxidation. The role of precipitation, including formation of new solid phases of Mn-P or Mn-carbonates, as possible contributing factors to Mn(II) removal from perlite suspensions was assessed and ruled out. Under acidic pH (below pH 6), Mn(II) was elevated above concentrations expected in an inert medium; it was attributed to releases from indigenous sources, on one hand, and both low adsorptive capacity and Mn-bacteria activity, on the other hand. The Mn(II) concentration declined sharply above pH 6, and at pH 7.7 dropped almost to zero, 48h after application. On a time scale of seconds to a few hours after application to perlite media the Mn(II) solubility was controlled by adsorption reactions, mainly onto the organic constituents accumulated from root excretions or decomposition and rhizosphere biota. With advancing time, biotic oxidation became important and it became the predominant mechanism of Mn(II) removal. [Copyright &y& Elsevier]

New α-aminoaldimines with the formula of Et2NCMe2CHNR (R = iPr, tBu, Ph) and their dichloro or diacetato complexes of Ni, Pd, Pt are prepared and structurally characterized. A nickel complex is in a distorted tetrahedral configuration, and the Pd and Pt complexes (4–6) are of square planar form. The α-aminoaldimines can chelate to the metal in a C2-unsymmetric bidentate motif through the hetero functionalities of amine and imine, which show comparable transinfluence. Square planar organometallic palladium derivatives bearing α-aminoaldimines, including Pd–methyl, Pd–acetyl, and Pd–(η2-acetylnorboryl) (7–10), are also synthesized. The latter two species are a result of CO-insertion into Pd–methyl complexes and ensuing norbornene-insertion, respectively. The geometrical isomerism is found in the transconfiguration in most studied cases. Such a stereoselectivity results from the thermodynamic stability governed predominantly by steric control. The stereoselectivity is also supported by DFT calculations. [ABSTRACT FROM AUTHOR]

The nitrile ligands in trans-[PtX2(PhCN)2] (X = Cl, Br, I) undergo sequential 1,3 dipolar cycloadditions with nitrones R1R2CN+(Me)–O− (R1 = H, R2 = Ph; R1 = CO2Et, R2 = CH2CO2Et) to selectively form the Δ4-1,2,4-oxadiazoline complexes trans-[PtX2(PhCN) {NC(Ph)–O–N(Me)–CR1R2}] or trans-[PtX2{NC(Ph)–O–N(Me)–CR1R2}2] in high yields. The reactivity of the mixed ligand complexes trans-[PtX2(PhCN){NC(Ph)–O–N(Me)–CR1R2}] towards oxidation and ligand substitution was studied in more detail. Oxidation with Cl2 or Br2 provides the Pt(iv) species trans-[PtX2Y2(PhCN){NC(Ph)–O–N(Me)–CH(Ph)}] (X, Y = Cl, Br). The mixed halide complex (X = Cl, Y = Br) undergoes halide scrambling in solution to form trans-[PtX(4−n)Yn(PhCN){NC(Ph)–O–N(Me)–CH(Ph)}] as a statistical mixture. Ligand substitution in trans-[PtCl2(PhCN){NC(Ph)–O–N(Me)–CR1R2}] allows for selective replacement of the coordinated nitrile by nitrogen heterocycles such as pyridine, DMAP or 1-benzyl-2-methylimidazole to produce mixed ligand Pt(ii) complexes of the type trans- [PtX2(heterocycle){NC(Ph)–O–N(Me)–CR1R2}]. All compounds were characterised by elemental analysis, mass spectrometry, IR and 1H, 13C and 195Pt NMR spectroscopy. Single-crystal X-ray structural analysis of (R,S)-trans-[PtBr2{NC(Ph)–O–N(Me)–CH(Ph)}2] and trans-[PtCl2(C5H5N){NC(Ph)–O–N(Me)–CH(Ph)}] confirms the molecular structure and the trans configuration of the heterocycles relative to each other. [ABSTRACT FROM AUTHOR]

Vanadium silyl complexes of the type Cp(dmpe)VSiHRR′ are formed by reaction of Cp(dmpe)VMe ( 1) with RR′SiH 2( 2, R, R′ = Ph; 3, R = Mes, R′ = H) in benzene at room temperature with concomitant release of CH 4gas. These complexes are paramagnetic, with high-spin d 3configurations, and exhibit broad 1H NMR resonances. They possess three-legged piano-stool geometries, and each silicon atom adopts a tetrahedral structure with no agostic V···HSi interaction. The V−Si bond length of 2is 2.5629(8) Å, and the V−P bond lengths are 2.4613(8) and 2.4621(8) Å. A KIE value of 2.1 ± 0.1 was observed for the reaction of Cp(dmpe)VCH 2Ph ( 4) with Ph 2SiH 2/Ph 2SiD 2at room temperature. The reaction of 2with Ph 2SiHCl in benzene resulted in silyl group exchange to give Cp(dmpe)VSiClPh 2( 5) in 82% yield. A vanadium(III) silyl complex was obtained by oxidation of 5with Ph 3CCl to give Cp(dmpe)V(Cl)SiClPh 2( 6). The V−Si and V−Cl bond lengths of 6are 2.573(1) and 2.388(1) Å, respectively. The Si−Cl bond length of 2.160(1) Å is longer than those typically observed (ca. 2.023 Å). Reaction of 2with CO afforded Cp(dmpe)V(CO) 2( 7) via homoleptic cleavage of the V−Si bond. The reaction of 5with Li(Et 2O) 3B(C 6F 5) 4generated what appears to be the silylene complex [Cp(dmpe)VSiPh 2]B(C 6F 5) 4, on the basis of elemental analysis. [ABSTRACT FROM AUTHOR]

Abstract  The effect of the arbuscular mycorrhizal (AM) fungus (Glomus versiforme) on iron contents by two citrus rootstocks (trifoliate orange [Poncirus trifoliata L. Raf] and red tangerine [Citrus reticulata Blanco]) was studied in sand culture under different pH conditions. Seeds were sown in a mixed substrate (perlite/sand, 1:1 [v/v]) inoculated with or without mycorrhizal inoculum. The experiment was carried out at four pH levels by applying nutrient solution at pH 5.0, 6.0, 7.0, or 8.0 to P. trifoliata and pH 5.2, 6.2, 7.2, or 8.2 to C. reticulata. No AM colonization was found in uninoculated control (NM) and plants, and root colonization in AM plants was depressed under iron deficiency at high pH. Colonization by G. versiforme led to higher dry weights of shoots compared with NM treatments, suggesting that G. versiforme enhanced plant growth. Higher concentration of chlorophyll and active iron, lower ratios of P/Fe and 50(10P)/Fe were present in AM plants than NM treatments. Nevertheless, G. versiforme improved root Fe (III) chelate reductase activity of P. trifoliata and C. reticulata. The data indicate that plant uptake and translocation of iron were enhanced and AM fungi may be considered as a potential tool for bioremediation of citrus iron deficiency. [ABSTRACT FROM AUTHOR]

Abstract: Dendrimer-containing multilayer thin films have successfully been prepared by a layer-by-layer deposition of carboxyl-terminated poly(amidoamine) dendrimer (PAMAM–COOH) and poly(methacrylic acid) (PMA) on a solid surface at pH 4.0, while the multilayer film did not form at pH 7.0. The PMA/PAMAM–COOH multilayer films prepared at pH 4.0 are decomposed at neutral pH due to electrostatic repulsion between negatively-charged carboxylate residues. The results suggest that the primary force for the successful deposition of PAMAM–COOH and PMA at pH 4.0 is hydrogen bonding between COOH residues on the surface of the dendrimer and PMA. The multilayer films are decomposed also at strongly acidic pH, suggesting an electrostatic force of attraction between the protonated tertiary amino groups in PAMAM–COOH and a small fraction of COO− residues in PMA contributes in part to the multilayer formation at pH 4.0. The PMA/PAMAM–COOH thin films can accommodate model dyes, Rose Bengal and 5,10,15,20-tetraphenyl-21H,23H-porphinetetrasulfonate, and the release can be controlled by changing pH. [Copyright &y& Elsevier]

Abstract: A series of tests on the fermentation of vegetable kitchen wastes to produce hydrogen were conducted at pHs of 5.5, 6.0, 6.5, and 7.0 under a thermophilic condition. Microorganisms used in fermentation were enriched from kitchen-waste composts, and a high vegetable-content kitchen-waste was utilized. The initial substrate to microorganism ratio was kept at 10g COD/g VSS under a thermophilic (55°C) condition. A maximum specific hydrogen production rate of 0.48mmol H2/g VSS/h was achieved at pH=6.0, and the highest hydrogen yield of 0.57mmol H2/g COD occurred at pH=7.0. No hydrogen production occurred at pH=5.5. At pHs controlled at 6.0, 6.5, and 7.0, the major volatile acid produced was butyrate. Using a terminal restriction fragment length polymorphism (TRFLP) analysis for microbial identification, T-RFs of 227bps were found to be a dominant population when hydrogen was produced efficiently at pHs of 6.0, 6.5, and 7.0. [Copyright &y& Elsevier]

Abstract: A fermentative hydrogen-producing bacterium was isolated from a food waste treatment process. The biological hydrogen production rate by the pure isolate (designated as Clostridium tyrobutyricum JM1) was dependent on various nutritional and environmental conditions. In this study, to enhance hydrogen production rate, the individual and mutual effects of three key process variables such as glucose concentration, pH and temperature were investigated through response surface methodology (RSM) in a batch system. A Box–Behnken design was employed to determine the effect of the three independent variables on the hydrogen production rate and to find the optimum condition of each variable for improved hydrogen production. Experimental results showed that a maximum hydrogen production rate of 5089ml H2 (g dry cellh)−1 was obtained under the condition of glucose concentration of 102.08mM, temperature 35°C and pH 6.5, and all three factors had significant influences on the specific hydrogen production rate. The RSM with the Box–Behnken design was a useful tool for achieving the high rate of hydrogen production by C. tyrobutyricum JM1. [Copyright &y& Elsevier]

Abstract: Biologically produced hydrogen using biomass and mixed bacterial cultures is one approach to generate renewable H2. Response surface methodology (RSM) was used to study the effect of initial pH (3.88–8.12) and initial substrate concentration (0.86–29.14g/L) on both hydrogen molar yield (HMY) and volumetric H2 production rate (VHPR). Lactose, cheese whey powder (CWP) and glucose were used as substrates and heat-treated anaerobic granular sludge as inoculum. For lactose, 3.6molH2/mol lactose and 5.6mmolH2/L/h were found at pH 7.5 and 5glactose/L. CWP yielded 3.1molH2/mol lactose at pH 6 and 15gCWP/L while 8.1mmolH2/L/h were attained at pH 7.5 and 25gCWP/L. Glucose yielded 1.46molH2/mol substrate (pH 7.5, 5gglucose/L), with a VHPR of 8.9mmolH2/L/h, at pH 8.12 and 15gglucose/L. Acetic and butyric acids were the main organic metabolites detected. HMY and VHPR obtained in this study were found at initial pH above the reported optimum pH value for hydrogen production. These findings could be of significance when alkaline pretreatments are performed on organic feedstock by eliminating the need to lower the pH to acidic levels before fermentation start-up. [Copyright &y& Elsevier]

Abstract  We developed a model for plant available sulfur (S) in Ohio soils to predict potential crop plant S deficiency. The model includes inputs of plant available S due to atmospheric deposition and mineralization of soil organic S and output due to leaching. A leaching index was computed using data on annual precipitation; soil pH and clay content that influence sulfate adsorption; and pore water velocity based upon percent sand, silt, and clay. There are five categories of S status ranging from highly deficient to highly sufficient, and the categories are defined based on whether the crop S requirement was 15 or 30kg S ha−1 year−1. The final database derived from the model includes 1,473 soil samples representing 443 of the 475 soil series in Ohio. For a crop requiring 15kg S ha−1 year−1, most soils (68.6%) were classified as variably deficient, which implies that the response to S fertilization will be variable but often positive depending on specific crop conditions. For a crop requiring 30kg S ha−1 year−1, 43.2% of soils were classified as variably deficient, but 49.7% were classified as moderately or highly deficient, implying that a response to S fertilization will usually or always occur. The model predicts crop S status for a single state in the USA, but with proper inputs, it should be applicable to other areas. [ABSTRACT FROM AUTHOR]

Abstract: The effects of pH and dissolved O2 on the γ-radiolysis of water were studied at an absorbed dose rate of 2.5Gys−1. Argon- or air-saturated water with no headspace was irradiated and the aqueous samples were analyzed for molecular radiolysis products (H2 and H2O2) as a function of irradiation time. The experimental results were compared with computer simulation results using a comprehensive water-radiolysis kinetic model, consisting of the primary radiolysis production, subsequent reactions and related acid–base equilibria. Both the experimental and computer model results were discussed based on the steady-state kinetic analysis of smaller reaction sets consisting of key production and removal reactions. While the main production path for a water decomposition product is the primary radiolysis, the main removal path varies. For H2O2 the main removal path is the reactions with eaq − and OH, whereas for H2 it is the reaction with OH. As a result, the presence of a dissolved species, or a change in chemical environment, affects the concentrations of H2O2 and H2 through interaction with radicals eaq − and OH. Over a wide range of conditions, there exist quantitative but simple relationships between the radical and the molecular product concentrations. The experimental and model analyses show that dissolved oxygen increases the steady-state concentrations of H2O2 and H2 by reacting with OH and eaq –, and the impact of oxygen is more noticeable at pH below 8. The steady-state concentrations of water decomposition products are nearly independent of pH in the range 5–8. However, raising pH above the pKa value of the acid–base equilibrium of H (⇆ eaq −+H+) significantly increases [H2O2] and [H2] at the expenses of [ OH] and [ eaq –]. At pH >10, the radiolytical production of O2 becomes significant, but at a finite rate. This considerably increases the time for the irradiated system to reach a steady state, and is responsible for different impacts on [H2O2] and [H2] due to radically produced O2, compared to impacts due to initially dissolved O2. Model sensitivity analysis has shown that at higher pHs (pH >10) transient species such as O2 − and O3 − play a major role in determining the steady-state concentration of molecular products H2 and H2O2. Further validation of the water radiolysis model, particularly at higher pHs, is also discussed. [Copyright &y& Elsevier]

Abstract  A new salicylate-selective electrode based on the complex (2,3;6,7;10,11;14,15-tetraphenyl-4,9,13,16-tetraoxo-1,5,8,12-tetraazacyclohexadecane) copper(II) [CuL] as the membrane carrier was developed. The electrode exhibits a good Nernstian slope of −60.9 ± 1.0 mV/decade and a linear range from 1.0 × 10−6 to 1.0 × 10−1 M for salicylate. The detection limit is 5.0 × 10−7 M. The electrode has a fast response time (5–15 s) and can be used for more than three months. The selective coefficients were determined by the fixed interference method (FIM) and separate solution method (SSM). The salicylate-selective electrode could be used in the pH range 3.5–10.5. It was employed as an indicator electrode for direct determination of salicylate in pharmaceutical samples. [ABSTRACT FROM AUTHOR]

Treatment of [Re(CO)3(THF)(μ-Br)]2 with 4,4-dichloro-1,1-diphenyl-2-azabuta-1,3-diene [Cl2CC(H)–NCPh2] (1a) yields the di-nuclear benzophenone azine-bridged compound [(OC)3Re(μ-Ph2CN–NCPh2)(μ-Br)2Re(CO)3] (2a), albeit in low yield. Alternatively, compounds [(OC)3Re(μ-Ph2CN–NCPh2)(μ-X)2Re(CO)3] (2a,b) (X = Br, Cl) are obtained in high yields by direct reaction of [Re(CO)3(THF)(μ-Br)]2 or [Re(CO)5Cl] with benzophenone azine. Nucleophilic attack of NaSPh on 1a affords the 2-azabutadiene derivative [(PhS)(Cl)CC(H)–NCPh2] (1b), which upon reaction with [Re(CO)3(THF)(μ-Br)]2 forms the S,N-chelate complex fac-[(OC)3ReBr{(PhS)(Cl)CC(H)–NCPh2}] (3). The crystal structures of 1b, 2a and 3 have been determined and the luminescence properties of 2 and 3 have been investigated. [Copyright &y& Elsevier]

A fast and accurate method to compute the total solvation free energies of proteins as a function of pH is presented. The method makes use of a combination of approaches, some of which have already appeared in the literature; (i) the Poisson equation is solved with an optimized fast adaptive multigrid boundary element (FAMBE) method; (ii) the electrostatic free energies of the ionizable sites are calculated for their neutral and charged states by using a detailed model of atomic charges; (iii) a set of optimal atomic radii is used to define a precise dielectric surface interface; (iv) a multilevel adaptive tessellation of this dielectric surface interface is achieved by using multisized boundary elements; and (v) 1:1 salt effects are included. The equilibrium proton binding/release is calculated with the Tanford−Schellman integral if the proteins contain more than ∼20−25 ionizable groups; for a smaller number of ionizable groups, the ionization partition function is calculated directly. The FAMBE method is tested as a function of pH (FAMBE-pH) with three proteins, namely, bovine pancreatic trypsin inhibitor (BPTI), hen egg white lysozyme (HEWL), and bovine pancreatic ribonuclease A (RNaseA). The results are (a) the FAMBE-pH method reproduces the observed p Kaʼs of the ionizable groups of these proteins within an average absolute value of 0.4 p Kunits and a maximum error of 1.2 p Kunits and (b) comparison of the calculated total pH-dependent solvation free energy for BPTI, between the exact calculation of the ionization partition function and the Tanford−Schellman integral method, shows agreement within 1.2 kcal/mol. These results indicate that calculation of total solvation free energies with the FAMBE-pH method can provide an accurate prediction of protein conformational stability at a given fixed pH and, if coupled with molecular mechanics or molecular dynamics methods, can also be used for more realistic studies of protein folding, unfolding, and dynamics, as a function of pH. [ABSTRACT FROM AUTHOR]

In a continuing study on discovery of more potent derivatives of sinomenine ( 1), a clinically available alkaloid for rheumatoid arthritis (RA) treatment, oxidation of sinomenine provided two unique stereoisomers, disinomenines 2and 3. The structure of 3was determined by MS, NMR, and X-ray analysis. The formation of 2and 3via oxidation of sinomenine by potassium permanganate (KMnO 4) exhibited a pH-dependent stereoselectivity. The bioassay results using human synovial sarcoma cells (SW982) showed that 2inhibited, while 3stimulated, IL-6 production. [ABSTRACT FROM AUTHOR]

One iterative in Grover's original quantum search algorithm consists of two Hadamard-Walsh transformations, a selective amplitude inversion and a diffusion amplitude inversion. We concentrate on the relation among the probability of success of the algorithm, the phase shifts, the number of target items and the number of iterations via replacing the two amplitude inversions by phase shifts of an arbitrary ph = ph(0 [?] ph, ph [?] 2p). Then, according to the relation we find out the optimal phase shifts when the number of iterations is given. We present a new quantum search algorithm based on the optimal phase shifts of 1.018 after 0.5p/ iterations. The new algorithm can obtain either a single target item or multiple target items in the search space with the probability of success at least 93.43%. [ABSTRACT FROM AUTHOR]

Poly(acrylic acid) (PAA) chains exhibit conformational change in response to pH, whereas bromate−sulfite−ferrocyanide (BSF) solution shows pH oscillation between 3.2 and 6.6. By use of quartz crystal microbalance with dissipation (QCM-D), we have investigated the pH induced conformational change of PAA brushes under a continuous flow of BSF solution in real time. The changes in frequency and dissipation clearly indicate the periodic swelling and collapse of brushes with pH oscillation. The changes in thickness, viscosity, and elastic modulus further indicate the oscillation of the interface. [ABSTRACT FROM AUTHOR]

The pH inside a dissolved polyelectrolyte coil or a swollen ionic polymer network is not accessible to direct measurement. It is here calculated through a simple model, based on Donnan equilibrium, counterion condensation (for charge density exceeding the critical value), and balance of mobile ions, without any assumption on the p Kaof the ionizable groups. The data needed for the calculation with this model are polymer concentration, pH value in the initial solution, and pH value in the bath at equilibrium. All three can be determined experimentally by a batch method where the polymer is immersed in a different pot for each starting pH. The model is applied to a sample system, namely, chemically cross-linked poly( N-vinylimidazole) immersed in acidic baths of different pH values. The imidazole units are basic and become protonated by the acid, thus changing the pH of the initial bath. The model shows how the pH developed inside the swollen gel is several units higher than the pH of the bath at equilibrium, both with or without the correction for counterion condensation. Consequently, when the p Kaof the polyelectrolyte is determined in the usual way (with the pH measured in the external bath), it gives an apparent value that is several units below the p Kadetermined from the actual pH inside the swollen gel at equilibrium. The inclusion of the counterion condensation decreases very slightly the polymer basicity. Surface effects and intramolecular association between protonated and unprotonated imidazole rings are discussed to explain the p Kabehavior in the limit of low degree of ionization. [ABSTRACT FROM AUTHOR]

Abstract: Extracellular acidic pH-activated chloride channel I Cl, acid, has been characterized in HEK 293 cells and mammalian cardiac myocytes. This study was designed to characterize I Cl,acid in human umbilical vein endothelial cells(HUVECs). The activation and deactivation of the current rapidly and repeatedly follows the change of the extracellular solution at pH 4.3, with the threshold pH 5.3. In addition, at very positive potentials, the current displays a time-dependent facilitation. pH-response relationship for I Cl,acid revealed that EC50 is pH 4.764 with a threshold pH value of pH 5.3 and nH of 14.545. The current can be blocked by the Cl− channel inhibitor DIDS (100μM). In summary, for the first time we report the presence of proton-activated, outwardly rectifying chloride channel in HUVECs. Because an acidic environment can develop in local myocardium under pathological conditions such as myocardial ischemia, I Cl,acid would play a role in regulation of EC function under these pathological conditions. [Copyright &y& Elsevier]

The zwitterionic vinyliminium complex [Fe2{μ-η1:η3-C(R′)ᆖC(S)CᆖN(Me)(Xyl)}(μ-CO)(CO)(Cp)2] (2a) (R′ = p-Me-C6H4 (Tol), Xyl = 2,6-Me2C6H3) undergoes electrophilic addition at the S atom by HSO3CF3, MeSO3CF3, SiMe3Cl, BrCH2Ph, ICH2CHᆖCH2 affording the complexes [Fe2{μ-η1:η3-C(Tol)ᆖC(SX)CN(Me)(Xyl)}(μ-CO)(CO)(Cp)2][Y] (X = H, Y = SO3CF3, 4a; X = Me, Y = SO3CF3, 4b; X = SiMe3, Y = Cl, 4c; X = CH2Ph, Y = Br, 4d; X = CH2CHᆖCH2, Y = I, 4e). Compound 2a and the corresponding vinyliminium complexes 2b and 2c (R′ = CH2OH, 2b; R′ = Me, 2c) react also with etherated BF3 leading to the formation of the corresponding S-adducts [Fe2{μ-η1:η3-C(R′)ᆖC(SBF3)CᆖN(Me)(Xyl)}(μ-CO)(CO)(Cp)2] (R′ = Tol, 5a; R′ = CH2OH, 5b; R′ = Me, 5c). In analogous reactions, the zwitterionic vinyliminium complexes undergo S-metalation upon treatment with in situ generated [Fp]+[SO3CF3]− [Fp = Fe(CO)2(Cp)], leading to the formation of [Fe2{μ-η1:η3-C(R′)ᆖC(S–Fp)CᆖN(Me)(Xyl)}(μ-CO)(CO)(Cp)2][SO3CF3](R′ = CH2OH, 6a; R′ = Me, 6b; R′ = Bun, 6c). Similarly, zwitterionic vinyliminium containing Se in the place of S also undergo Se-electrophilic addition. Thus, the complexes [Fe2{μ-η1:η3-C(R′)ᆖC(SeX)CᆖN(Me)(R)}(μ-CO)(CO)(Cp)2][SO3CF3] (R = X = Me, R′ = Tol, 7a; R = Xyl, R′ = Me, X = Fp+, 7b) are obtained upon treatment of the neutral zwitterionic precursors with MeSO3CF3 and [Fp][SO3CF3], respectively. Alkylation at the S or Se atom of the bridging ligand is also accomplished by CH2Cl2, used as solvent, although the reaction is slower compared to more efficient alkylating reagents. The complexes formed by this route are [Fe2{μ-η1:η3-C(R′)ᆖC(E-CH2Cl)CᆖN(Me)(R)}(μ-CO)(CO)(Cp)2][X] [E = S, R = Xyl, R′ = Tol, X = Cl, 8a; E = S, R = Xyl, R′ = Me, X = Cl, 8b; E = Se, R = R′ = Me, X = BPh4, 8c]. Finally, treatment of the zwitterionic vinyliminium complexes with I2 results in the oxidative coupling with formation of S–S (disulfide) or Se–Se (diselenide) bond. The reactions, performed in the presence of NaBPh4 afford the tetranuclear complexes [Fe2{μ-η1:η3-C(R′)ᆖC(E)CᆖN(Me)(R)}(μ-CO)(CO)(Cp)2]2[BPh4]2 [R = Xyl, R′ = CH2OH, E = S, 9a; R = Xyl, R′ = Me, E = S, 9b; R = Xyl, R′ = Bun, E = S, 9c; R = Xyl, R′ = Me, E = Se, 9d; R = Me, R′ = Bun, E = Se, 9e]. The molecular structures of 4a, 8c and 9e have been determined by X-ray diffraction studies. [Copyright &y& Elsevier]

Abstract: A new copper(II) complex with chloride bridges and mixed blocking ligands, [{Cu(pzPh)(Opo)}2(μ-Cl)2] (1), whereby pzPh =3-phenyl-pyrazolyl, and OpoH=2-hydroxypyridine-N-oxide, has been obtained by degrading tris(pyrazolyl)borate in the presence of hydrated CuCl2 salt and the ligand Opo−. The molecular structure of 1 was solved by X-ray diffraction. The two Cu(II) atoms of the dinuclear complex have a pyramidal arrangement in which the two pyramids share one base-to-apex edge with parallel basal planes. Magnetic susceptibility measurements revealed ferromagnetic coupling between the Cu atoms, with J =+8.72cm−1. X-band EPR spectra of CH2Cl2 solutions of 1 were recorded at different temperatures. [Copyright &y& Elsevier]

Abstract: The single and combined effects, in a synthetic medium at selected pH values, of sorbic and benzoic acids on a yeast cocktail (Saccharomyces cerevisiae, Pichia anomala, Issatchenkia occidentalis, and Candida diddensiae, isolated from table olives) have been studied. Applying the checkerboard method the minimum inhibitory concentration (MIC) obtained for the respective individual preservatives (expressed as undissociated acid) were: sorbic acid, 5.94, 3.85 and 3.19mM at pH of 4.5, 4.0, and 3.5, respectively; and benzoic acid, not detected (at total 20.5mM), 10.40 and 6.83mM, respectively, for the same pH levels. The estimated fractional inhibitory concentrations (FIC) indexes showed additive effects between inhibitors. Fractional area (fa), modelled by the (extended) Lambert and Lambert [2003. A model for the efficacy of combined inhibitors. J. Appl. Microbiol. 95, 734–743] equation (ELPM), also showed additives of both preservatives but different shapes in the dose–response curves; the individual MIC (as undissociated acid) deduced from this method were: 5.60, 3.31, and 3.26mM for sorbic acid at pH of 4.5, 4.0, and 3.5, respectively; and 29.65 (extrapolated), 10.00, and 6.25mM for benzoic acid at the same pH levels. Mixtures above the curves connecting the limits (MIC) at each pH were also inhibitory. There was agreement between MIC values from FIC and ELPM, although the last one provided further information on the inhibition behaviour. I. occidentalis was the most resistant yeast of the cocktail to sorbic and benzoic acids. [Copyright &y& Elsevier]

Abstract: Starting from the efficient hexahydropyridoindole antioxidant stobadine, a series of carboxymethylated tetrahydro- and hexahydropyridoindole derivatives was synthesized and tested for the inhibition of aldose reductase, an enzyme involved in the etiology of diabetic complications. In vitro inhibiton of rat lens aldose reductase was determined by a conventional method. Kinetic analysis of (2-benzyl-2,3,4,5-tetrahydro-1H-pyrido[4,3-b]indole-8-yl)-acetic acid (5b) and (2-phenethyl-2,3,4,5-tetrahydro-1H-pyrido[4,3-b]indole-8-yl)-acetic acid (5c), the most potent compounds in this series with activities in micromolar range, showed uncompetitive inhibition. In addition to the importance of the acidic function, the inhibition efficacy was highly influenced by the steric conformation of the lipophilic aromatic backbone when comparing tetrahydro- and hexahydropyridoindole congeners. Selectivity with respect to the closely related aldehyde reductase was determined by measuring the corresponding inhibitory activities. Antioxidant action of the novel compounds was documented in a DPPH test and in a liposomal membrane model, oxidatively stressed by peroxyl radicals. The presence of a basicity center at the tertiary nitrogen, in addition to the acidic carboxylic function, predisposes these compounds to form double charged zwitterionic species, a characteristic which may remarkably affect their pH-lipophilicity profile. For compounds 5b and 5c, a maximal distribution ratio in a system comprised of 1-octanol/phosphate buffer was recorded near the neutral physiological pH, the region where the isoelectric point lies. Molecular docking simulations into the ALR2 active site performed for the zwitterionic species provided an explanation for the observed structure–activity relationships and the calculated parameters were in agreement with characteristic differences in the stereoelectronic profiles of the tetrahydro- versus hexahydropyridoindoles. ‘Drug-likeness’ of the novel aldose reductase inhibitors was assessed by applying the criteria of Lipinski’s ‘rule of five’. [Copyright &y& Elsevier]

Incubation of soil with CaCO3 is generally considered a reliable method to determine the lime requirement (LR) of acid soils. Because of their considered reliability, these incubations are often used to calibrate buffer methods; however, one study reported that the use of room temperature incubation with CaCO3 overestimated the actual LR determined by field testing. The objective of this study was to compare the pH change following CaCO3 incubations for 60 d with those following 3-d incubations with Ca(OH)2 and to determine the possible role of soil N reactions causing any differences in pH change. Seventeen soils were incubated with either CaCO3 for 60 d at approximately 85% field capacity or for 3 d with an equivalent amount of Ca(OH)2 solution plus water to maintain a 1:1 soil/solution ratio. Both were incubated at room temperature (23 ± 2°C), followed by measurement of pH (1:1 in water). Ammonium-N and NO3--N were analyzed at Days 0 and 60 of the incubation. Soil pH was lower following the 60-d CaCO3 incubation than after the 3-d incubation with Ca(OH)2. The analysis of N transformations indicated that positive values of H+ (more H+ was produced than consumed) were generated from nitrification after 60 d of incubation in 14 out of 17 soils. Furthermore, incubations with soils that have been air dried produced a flush of nitrification that increased the ionic strength and decreased pH even further. These effects from long-term incubation would erroneously increase the LR. Incubation with Ca(OH)2 for 2 to 4 d avoids these errors. [ABSTRACT FROM AUTHOR]

X-ray photoemission electron microscopy (XPEEM) using synchrotron radiation illumination has been used to study the adsorption of human serum albumin (HSA) onto a phase segregated polystyrene/polymethylmethacrylate (PS/PMMA) blend surface from solutions of five different pH values. The absolute coverage of albumin on each of three chemically distinct components of the surface, PS domains, PMMA domains, and the interface between the domains, was determined from a quantitative analysis of C 1s image sequences. At all pH values, the preferred adsorption site is the interface. At neutral pH (7.0), albumin showed a slight preference for PS regions relative to PMMA. At strongly acidic pH (2.0) and strongly basic pH (10.0), similar amounts of albumin adsorb on the PS and PMMA regions. However, at pH 4.0, the amount of albumin adsorbed on PMMA domains is ∼1.6 times greater than that on PS domains, while at pH 8.6 the amount of albumin adsorbed on PMMA is one-half that adsorbed on PS domains. The pH dependence of the site preference is rationalized in terms of the known changes of albumin conformation with pH Peters, T., Jr. All About Albumin:  Biochemistry, Genetics, and Medical Applications; Academic Press:  New York, 1995. We infer from our results that the site preference of albumin adsorption on PS/PMMA blends is related mainly to changes in hydrophobic interactions, which are driven by pH-dependent electrostatic effects, that is, changes to the protein surface structure as the charge on the protein changes. The results provide insight into changes in the secondary structure of albumin in acid and basic media. [ABSTRACT FROM AUTHOR]

Abstract: The Zr-catalyzed methylalumination of heterosubstituted arylethynes containing O, S, Cl, and Si can proceed in high yields (>70%) and in a highly regio- and stereoselective manner (⩾98–99%), although SO2Ph, Br, and Cl in a benzylic position present serious chemoselectivity-related problems. The low regioselectivity of 60% initially observed with o-ethynylphenol (1a) has been elevated to ⩾98% through the use of either a catalytic amount of Zr(ebi)Cl2 or Zr(2-Me-Ind)2Cl2 or, more conveniently, the stoichiometric amount of ZrCp2Cl2, ZrCp2MeCl, or ZrCp2Me2 in conjunction with the use of a deficient amount (0.9molar equiv.) of I2 for subsequent iodinolysis. [Copyright &y& Elsevier]

Abstract: We report the fabrication of a novel composite membrane with high flux and good selectivity which may find application in protein separations under ultrafiltration conditions by modifying the surface of a microfiltration membrane (Supor 450, 0.45μm pore size, polyethersulfone membrane) with a uniform coating of chitosan(CHI)/polystyrene sulfonate(PSS) polyelectrolyte multilayer. The transport of bovine serum albumin (BSA), ovalbumin and lysozyme at their isoelectric point (pI), pH below and above their isoelectric points (pI), through these multilayer membranes have been studied. We observed a dramatic change in the transport behavior of the proteins through these multilayers depending on the number of deposited layers and the solution pH. The transport studies through the composite membranes shows 95% rejection of BSA by a 9-bilayer (bl) CHI/PSS multilayer (permeate flux of 0.49m3/m2 day) at 10psi. Ovalbumin showed permeate enrichment and more than 100% of ovalbumin is permeated (permeate flux of 25.7m3/m2 day) and 98% lysozyme is rejected (permeate flux of 11.7m3/m2 day) at 10psi by a 5bl membrane at pH 8.8. The individual transport studies of ovalbumin and lysozyme indicates that these egg white proteins could be separated using this multilayer system. [Copyright &y& Elsevier]

The role played by the carbonyl group in the antenna system of a naturally occurring photochromic chromene, flindersine (FL), has been experimentally investigated and compared with that of a carbonyl group present in a structurally related unreactive heterocyclic compound, 6(5H)-phenanthridinone (PH). Through stationary and time-resolved absorption and emission techniques, the excited-state relaxation dynamics after UV irradiation were determined for FL and PH. The presence of a carbonyl group in both compounds entails the existence of two close-lying, strongly coupled electronic excited states, having n, and , character, respectively. Their coupling can be modulated by a careful choice of the solvent proticity and temperature. Moreover, in the case of strong coupling between the n, and , states, we have proved that the relaxation dynamics can involve transitions in which the upper of the coupled states acts as an intermediate for radiationless decay, bypassing the lowest emissive state, whereby the fluorescence quantum yield becomes a function of the excitation wavelength. [ABSTRACT FROM AUTHOR]

Abstract: The effects of the pH and protein content on the properties and compositional changes of protein-based films from bigeye snapper (Priacanthus tayenus) surimi were investigated. Tensile strength of bigeye snapper surimi films prepared at the acidic (pH 3) and alkaline (pH 11) conditions were not significantly different (P >0.05). Nevertheless, elongation at break of films prepared at pH 3 was higher than that at pH 11 (P <0.05). The acidic and alkaline conditions had no effect on water vapor permeability of the films obtained. However, the film prepared at acidic condition was more yellowish than that prepared at alkaline pH. Protein content influenced the mechanical properties and color of films. [Copyright &y& Elsevier]

Many soil analysis labs routinely determine lime requirement of acidic soils using different buffer solutions for optimum plant growth. The Adams‐Evans lime determination solution was introduced more than 40 years ago and has been used by many soil analysis labs. Even though many buffer solutions have been developed since then, very little attention has been paid to address the toxic nature of chemicals involved in buffer solutions. The most commonly used buffer solutions, such as the Adams-Evans, Shoemaker‐McLean‐Pratt (SMP), Woodruff, and others, contain p ‐nitrophenol, which is toxic to humans and the environment. Use of p ‐nitrophenol requires prescribed containment and disposal procedures, that creates extra burden on soil analysis labs that provide their invaluable service at low cost. Replacing p ‐nitrophenol with monobasic potassium phosphate (KH 2 PO 4 ), which has similar buffering capacity but with no known toxicity, is beneficial to soil testing labs and the environment. The original Adams‐Evans buffer solution was compared with the modified Adams‐Evans buffer solution with soils of different pH, cation exchange capacity and lime requirement. The linear regression between the buffer pH values and lime recommendations made by Adams‐Evans and the modified Adams‐Evans solutions were highly significant. Thus, the modified Adams‐Evans buffer solution can be used without loss of established recommendation criteria as the original buffer solution. [ABSTRACT FROM AUTHOR]

The construction and characteristics of the stable and well-structured α4W protein are described. The 117-residue, single-chain protein has a molecular weight of 13.1 kDa and is designed to fold into a four-helix bundle. Experimental characterization of the expressed and purified protein shows a 69.8 ± 0.8% helical content over a 5.5–10.0 pH range. The protein is thermostable with a TM > 355 K and has a free energy of unfolding as measured by chemical denaturation of −4.7 kcal mol−1 at 25°C and neutral pH. One-dimensional (1D) proton and 2D 15N-HSQC spectra show narrow, well-dispersed spectral lines consistent with a uniquely structured α-helical protein. Analytical ultracentrifugation and NMR data show that the protein is monomeric over a broad protein concentration range. The 324 nm emission maximum of the unique Trp-106 is consistent with a sequestered position of the aromatic residue. Additionally, differential pulse voltammetry characterization indicates an elevated peak potential for Trp-106 when the protein is folded (pH range 7.0–8.5) relative to partly unfolded (pH range 11.4–13.2). The oxidation of Trp-106 is coupled to proton release as shown by a 53 ± 3 mV/pH unit dependence of the peak potential over the 7.0–8.5 pH range. [ABSTRACT FROM AUTHOR]

Directing the self-assembly of colloidal particles into nanostructures is of great interest in nanotechnology. Here, reversible end-to-end assembly of gold nanorods (GNR) is induced by pH-dependent changes in the secondary conformation of a disulfide-modified poly(L-glutamic acid) (SSPLGA). The disulfide anchoring group drives chemisorption of the polyacid onto the end of the gold nanorods in an ethanolic solution. A layer of poly(vinyl pyrrolidone) is adsorbed on the positively charged, surfactant-stabilized GNR to screen the surfactant bilayer charge and provide stability for dispersion of the GNR in ethanol. For comparison, irreversible end-to-end assembly using a bidentate ligand, namely 1,6-hexanedithiol, is also performed. Characterization of the modified GNR and its end-to-end linking behavior using SSPLGA and hexanedithiol is performed using dynamic light scattering (DLS), UV-vis absorption spectroscopy and transmission electron microscopy (TEM). Experimental results show that, in a colloidal solution of GNR-SSPLGA at a pH[?]3.5, where the PLGA is in an a-helical conformation, the modified GNR self-assemble into one-dimensional nanostructures. The linking behavior can be reversed by increasing the pH (>8.5) to drive the conformation of the polypeptide to a random coil and this reversal with pH occurs rapidly within minutes. Cycling the pH multiple times between low and high pH values can be used to drive the formation of the nanostructures of the GNR and disperse them in solution. [ABSTRACT FROM AUTHOR]

Recent results from heavy-ion collisions at the CERN SPS are discussed. Measurements of the production of K*(890), light nuclei, and identified particles at medium pT are presented. New analyses concerning the ph puzzle are discussed. Results of lepton pair production at low and intermediate mass as well as in the charmonium region are reviewed. Evidence for the onset of deconfinement at the SPS is recalled and the status of the search for the critical point of QCD is discussed. [ABSTRACT FROM AUTHOR]

Abstract: Micro-spot arrays with different pH and polarity sensitive fluorescence dyes were prepared using a piezo dispensing head. A polyethylene glycol matrix was used to immobilize the dyes covalently. The polymer matrix was cross-linked to ensure stable dye bonding and for controlling the swelling and permeability of the thin film. Analytical experiments were carried out in the fluidic phase with specially developed micro-fluidic and CCD imaging optical set-up. As a result, different solvents and solutions could be distinguished for their pH and polarity using fluorescence digital imaging. After calibration, a quantitative determination of the solution composition was also possible. The chemo-chips were tested against different solvent species leading to confirmation of the applicability of the developed spot array for the reproducible recognition of different liquid types focusing on polarity and pH as parameters. [Copyright &y& Elsevier]