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Molybdenum (Mo) is one important mineral element for plants because it participates actively in many metabolic essential functions like the synthesis of molybdenum cofactor and nitrogen metabolism. Mo is available on soil in an anionic form, and its activity increases with pH elevation. Few studies in the literature reported the identification and characterization of Mo transporter genes. Given the above, we describe a comprehensive in silico analysis of Mo transporters in six Panicoideae species. We identified 15 candidates genes associated with Mo transporters. The subcellular location shows that all predicted genes were present in the plasma membrane. The genomic structure revealed that most of the Mo transporters genes showed no introns, while two sequences of P. virgatum presented one intron. Five conserved motifs and nine putative transmembrane domains were identified. Phylogenetic analysis revealed two groups (A1 and A2), showing close or conserved phylogenetic relationships. Synteny analysis identified 45 pairs of syntenic Mo orthologous among the six genomes of Panicoideae species, and purifying selection played a critical role in the evolution of Mo transporter genes. Efforts need to be undertaken to understand and improve molybdenum uptake and utilization in Panicoideae species for the sustainability of these species. This study will serve as a biotechnological basis for the characterization of candidate genes (Mo) involved in the regulation of gene expression under adverse conditions, allowing the development of future strategies to ensure greater sustainability of the important species of Panicoideae.

The biochemical drivers of phosphorus (P) availability and cycling are sensitive to changes in soil pH. However, reports of lime-induced pH modification effects on P availability are (1) inconsistent, (2) focused mainly on chemical changes, and (3) often limited to the bulk soil. Using lupin as an indicator species, we aimed to evaluate the effects of lime-induced soil pH change, from 5.3 to 6.0, on biochemical processes responsible for P mobilization and dynamics in the rhizosphere of two different lupin species. Indicator species, blue lupin (Lupinus angustifolius) and Russell lupin (Lupinus polyphyllus), were grown in a P-deficient acid grassland soil without P inputs for 11 weeks in a glasshouse. The rhizosphere soils were analyzed for enzyme activity, microbial P, and carboxylates. Both bulk and rhizosphere soils were analyzed for P fractions, exchangeable aluminum (Al), and pH. Plant yields and shoot P uptake were measured. Labile inorganic P (Pi) increased in the rhizospheres of both lupin species, likely due to Pi desorption combined with labile organic P (Po) mineralization, induced by rhizosphere pH elevation after liming. Soil pH increase promoted microbial P immobilization and reduced phosphomonoesterase activity in the rhizosphere, leading to an accumulation of Po mainly as moderately labile and stable Po forms. Total carboxylate concentration (TCC) increased with soil pH increase. Variation in shoot P uptake was mostly explained by TCC. These results indicate that (1) lime application strongly affects P biochemical processes and dynamics in the rhizosphere of lupins. (2) Russell lupin utilizes less P than blue lupin and is unresponsive to liming.

The pathogenic model of hidradenitis suppurativa is in the midst of a paradigm shift away from a disorder of primary follicular occlusion to an autoinflammatory keratinization disease. Observational, experimental, and therapeutic evidence supports the concept of hidradenitis suppurativa as a primarily inflammatory disorder, a disorder of autoimmunity, or both, in contrast to the current prevailing paradigm of primary follicular occlusion. The lack of reliable and high-fidelity disease models has limited the available experimental and mechanistic evidence to support or refute one pathogenic model over another. This scholarly review synthesizes the existing clinical, histologic, and molecular data to evaluate the extant evidence supporting the autoinflammatory paradigm and further informing the molecular mechanisms of hidradenitis suppurativa pathogenesis. Follicular hyperkeratosis/occlusion and perifollicular inflammation coexist in histologic specimens, with interleukin 1α demonstrated to stimulate comedogenesis in the infundibulum. pH elevation in occluded body sites alters the microbiome and amplifies existing T-helper cell type 17 immunoresponses. Known metabolic comorbidities and smoking are known to upregulate interleukin 1α in follicular keratinocytes. Identified genetic variants may alter epidermal growth factor receptor signaling, leading to upregulated keratinocyte inflammatory responses. The process of follicular rupture and dermal tunnel formation can be explained as secondary responses to inflammatory activation of fibroblasts and epithelial-mesenchymal transition, with antibody production associated with inflammatory amplification in advanced disease. This review aims to reevaluate and integrate the current clinical, histologic, and molecular data into a pathogenic model of hidradenitis suppurativa. This is essential to advance our understanding of the disease and identify novel therapeutic targets and approaches.

The Chinese government has exerted strict emission controls to mitigate air pollution since 2013, which has resulted in significant decreases in the concentrations of air pollutants such as SO2. Strict pollution control actions also reduced the average PM2.5 concentration to the low level of 39.7 µg m−3 in urban Beijing during the winter of 2017. To investigate the impact of such changes on the physiochemical properties of atmospheric aerosols in China, we conducted a comprehensive observation focusing on PM2.5 in Beijing during the winter of 2017. Compared with the historical record (2014–2017), SO2 decreased to the low level of 3.2 ppbv in the winter of 2017, but the NO2 level was still high (21.4 ppbv in the winter of 2017). Accordingly, the contribution of nitrate (23.0 µg m−3) to PM2.5 far exceeded that of sulfate (13.1 µg m−3) during the pollution episodes, resulting in a significant increase in the nitrate-to-sulfate molar ratio. The thermodynamic model (ISORROPIA II) calculation results showed that during the PM2.5 pollution episodes particle pH increased from 4.4 (moderate acidic) to 5.4 (more neutralized) when the molar ratio of nitrate to sulfate increased from 1 to 5, indicating that aerosols were more neutralized as the nitrate content elevated. Controlled variable tests showed that the pH elevation should be attributed to nitrate fraction increase other than crustal ion and ammonia concentration increases. Based on the results of sensitivity tests, future prediction for the particle acidity change was discussed. We found that nitrate-rich particles in Beijing at low and moderate humid conditions (RH: 20 %–50 %) can absorb twice the amount of water that sulfate-rich particles can, and the nitrate and ammonia with higher levels have synergetic effects, rapidly elevating particle pH to merely neutral (above 5.6). As moderate haze events might occur more frequently under abundant ammonia and nitrate-dominated PM2.5 conditions, the major chemical processes during haze events and the control target should be re-evaluated to obtain the most effective control strategy.

Summary Lysosomal dysfunction is considered pathogenic in Alzheimer Disease (AD). Loss of Presenilin-1 (PSEN1) function causing AD impedes acidification via defective vATPase V0a1 subunit delivery to lysosomes. We report that isoproterenol and related β2-adrenergic agonists re-acidify lysosomes in PSEN1 KO cells and fibroblasts from PSEN1 familial AD(FAD) patients, which restores lysosomal proteolysis, calcium homeostasis, and normal autophagy flux. We identify a novel rescue mechanism involving PKA-mediated facilitation of ClC-7 delivery to lysosomes which reverses markedly lowered Cl- content in PSEN1 KO lysosomes. Notably, PSEN1 loss-of-function impedes ER-to-lysosome delivery of ClC-7. Transcriptomics of PSEN1-deficient cells reveal strongly down-regulated ER-to-lysosome transport pathways and reversibility by isoproterenol thus accounting for lysosomal Cl- deficits that compound pH elevation due to deficient vATPase and rescue by β2-adrenergic agonists. Our findings uncover a broadened PSEN1 role in lysosomal ion homeostasis and novel pH modulation of lysosomes through β2-adrenergic regulation of ClC-7, which can potentially be modulated therapeutically.

This study investigated the long-term leachability of antimony (Sb) in a smelting residue immobilized by three commercial micro-sized zero-valent iron (ZVI) products. Effect of oxic incubation time (14 days and 120 days) on the immobilization efficiency of Sb were compared, and the long-term leaching risk was evaluated by an accelerated exposure test, in which the slag was consecutively extracted by simulated strong acid rain (SSAR, HNO3: H2SO4 = 1:2, pH = 3.20). Notably, all ZVI treatments efficiently immobilized the Sb in this slag in a short term (14 days); the one-step SSAR-leached Sb was reduced by 89%–91% compared to the original slag (5.9 mg/L) and was far below the environmental standard (0.6 mg/L) established by the US EPA. The sequential SSAR leaching results reflected that the 14-d incubated slags after ZVI treatments had strong H+ resistance, and the immobilized Sb was not easily activated by continuous SSAR corrosion. The binding of Sb with amorphous phase Fe oxyhydroxides (e.g. ferrihydrite) derived from ZVI corrosion played a dominant role in the Sb immobilization efficiency. However, the longer aging process (120 days) easily resulted in the reduction of Sb immobilization by ZVI treatments. The changes in crystallinity of Fe oxyhydroxides (transformation from poorly-crystalline to crystalline ones) and the pH elevation to alkaline range might explain the weakening of the immobilization of Sb in ZVI-amended slags with 120 days of incubation. In total, the effectiveness of Sb immobilization in smelting residue greatly depended on the type of ZVI and the aging process. Our work has demonstrated that the ZVI treatment was potentially feasible to mitigate the Sb leaching risk from smelting slags; however, the ZVI type needs to be carefully selected and its long-term performance should be adequately verified before practical application.

The aim of this study was to examine the effect of bioactive glass (BAG) loading on the ion release, pH changes, and cell response of the experimental pit and fissure sealant containing sol–gel derived 58S BAG. The BAG and silica filler in different proportion were incorporated into a resin matrix with the final filler loading of 50% in all groups. The specimens were immersed in deionized water (pH 5.8) or lactic acid solution (pH 4.0) at different time points (6 h, 1, 7, 14, 30, and 45 days) for ion release and pH changes assessment. Biological properties were evaluated using MTS assay, alkaline phosphatase (ALP) assays, and alizarin red staining. In the deionized water, the BAG50% group pH reaches to 9.3 and in lactic acid solution to 4.31 after 45 days. The BAG filler percentage did not have a significant effect on ion release in the deionized water. However, ion release increased with the pH reduction, particularly in the BAG50% group. The BAG50% group showed less cytotoxicity and higher ALP activity and calcified nodule formation. The experimental pit and fissure sealant with 50% BAG filler loading exhibited an appropriate increase in pH elevation, ion release, and cell proliferation and differentiation. Therefore, it can be concluded that this bioactive sealant has the potential to hinder secondary caries and can be used as a caries-inhibiting material.

Biofouling of seawater reverse osmosis (SWRO) membranes is a major problem that SWRO freshwater production facilities face worldwide. A three-step pretreatment scheme, initially designed to assist the SWRO process in boron rejection, was examined as a potential membrane biofouling inhibitor. The conventional pretreatment procedure in this study includes acidification, CO2 stripping and pH elevation, and its effect on planktonic cell mortality and biofilm formation on the membrane was analyzed. An in-situ electrolytic production of free chlorine in seawater, during the low pH phase, was suggested as an additional pretreatment step, with the goal of serving as an aggressive disinfection course. In addition, 48-hour enhanced biofouling experiments using an RO membrane cell assembly were conducted in order to observe the flux decline pattern as affected by the various treatments. The conventional pretreatment scheme was found to have a moderate effect on membrane biofouling, increasing the membrane permeability by 25% relative to an untreated experimental run. Moreover, the conventional pretreatment did not significantly promote cell mortality; however, it caused an increase in extracellular polysaccharide production during biofilm formation. The additional chlorination step increased the biofouling phenomenon, causing the production of particulate matter, likely due to cell wall oxidation.

The adaptive treatment tolerance (ATT) of cancer cells is the main encumbrance to cancer chemotherapy. A potential solution to this problem is to treat cancer cells with multiple drugs using nanoparticles (NPs). In this study, we tested the co-administration of curcumin (Cur) and doxorubicin (Dox) to MCF-7 resistant breast cancer cells to block the ATT and elicit efficient cell killing. Drugs were co-administered to cells both sequentially and simultaneously. Sequential drug co-administration was carried out by pre-treating the cells with albumin nanoparticles (ANPs) loaded with Cur (Cur@ANPs) followed by treatment with Dox-loaded ANPs (Dox@ANPs). Simultaneous drug co-administration was carried out by treating the cells with ANPs loaded with both the drugs (Cur/Dox@ANPs). We found that the simultaneous drug co-administration led to a greater intra-cellular accumulation of Dox and cell killing with respect to the sequential drug co-administration. However, the simultaneous drug co-administration led to a lower intra-cellular accumulation of Cur with respect to the sequential drug co-administration. We showed that this result was due to the aggregation and entrapment of Cur in the lysosomes as soon as it was released from Cur@ANPs, a phenomenon called lysosomotropism. In contrast, the simultaneous release of Dox and Cur from Cur/Dox@ANPs into the lysosomes led to lysosomal pH elevation, which, in turn, avoided Cur aggregation, led to lysosome swelling and drug release in the cytosol, and finally provoked efficient cell killing. Our study shed the light on the molecular processes driving the therapeutic effects of anti-cancer drugs co-administered to cancer cells in different manners.

A conservative element in seawater, uranium is readily incorporated into the aragonitic skeletons of scleractinian corals, making them an important paleoclimate archive that can be absolutely dated with U-Th techniques. In addition, uranium concentrations (U/Ca ratios) in corals have been suggested to be influenced by the temperature and/or carbonate ion concentration of the ambient seawater based on empirical calibrations. Microsampling techniques have revealed strong heterogeneities in U/Ca within individual specimens in both surface and deep-sea corals, suggesting a biological control on the U incorporation into the skeletons. Here we further explore the mechanism of uranium incorporation in coral skeletons with the deep-sea species Desmophyllum dianthus, an ideal test organism for the biomineralization processes due to its relatively constant growth environment. We find a negative correlation between bulk coral U/Ca and temperature as well as ambient pH and [CO32–] that is consistent with previous studies. By sampling the growth bands of individual corals, we also find a twofold change in U/Ca within individual corals that is strongly correlated with the δ18O, δ13C, and other Me/Ca ratios of the bands. A similar correlation between U/Ca and stable isotopes as well as other Me/Ca ratios are observed in bulk deep-sea coral samples. With a numerical coral calcification model, we interpret the U/Ca-stable isotope correlation as a result of changes in uranium speciation in response to internal pH elevations in the extracellular calcifying fluid (ECF) of the corals, and suggest that the Ca2UO2(CO3)3(aq) complex, the dominant U species in seawater, may be the major species incorporated into the coral skeleton. Therefore, the correlation between U/Ca and ambient [CO32–] is likely a result of the response of the biomineralization process, especially the magnitude of internal pH elevation, to the growth environment of the corals. Our data suggest overall lower alkalinity pump rates in corals from low saturation seawater compared to those from high saturation seawater, and possible increases in Ca2+ supply from active pumping relative to seawater transport in response to the environmental stress of low saturation.

Alexandrium catenella is a harmful algal bloom (HAB)-forming dinoflagellate that causes significant damage to the cultivation and harvest of shellfish due to its synthesis of paralytic shellfish toxins. To evaluate the potential for macroalgae aquaculture to mitigate A. catenella blooms, we determined the effects of three cultivable macroalgae - Saccharina latissima (sugar kelp), Chondrus crispus (Irish moss), and Ulva spp. - on A. catenella in culture- and field-based experiments. Co-culture growth assays of A. catenella exposed to environmentally realistic concentrations of each macroalgae showed that all species except low levels of C. crispus caused cell lysis and significant reductions in A. catenella densities relative to control treatments of 17–74% in 2–3 days and 42–96% in ~one week (p Ulva spp. > C. crispus. Seaweeds’ primary anti-A. catenella activity were allelopathic, while nutrient competition, pH elevation, and macroalgae-attached bacteria may have played a contributory role in some experiments. Collectively, these results suggest that the integration of macroalgae with shellfish-centric aquaculture establishments should be considered as a non-invasive, environmentally friendly, and potentially profit-generating measure to mitigate A. catenella-caused damage to the shellfish aquaculture industry.

This work aims at investigating the pH-regulated relationship between the structural features and emulsifying properties of chicken liver protein (CLP) during succinylation and related mechanisms behind. The results demonstrated that the major succinylation sites occurred at lysine, histidine and tyrosine of CLP, and the succinylation degree increased by 30.66% as pH increased to 10. The succinylation pH elevation increased the solubility and oil absorption capacity of CLP, thus favoring its improvement in emulsifying properties, due to the succinylation process-induced increase in surface charge density and amphiphilic balance as well as modified network structure. However, the surface hydrophobicity of succinylated products decreased by 10.75% when the pH increased from 7 to 10. Besides, succinylation-induced variations in electrostatic repulsive and particle size distribution greatly improved the storability of the emulsions. These results suggested the great potential of pH-modulated succinylation to regulate the structure-property relationship of protein-based products.

Reverse osmosis (RO) is a widely applied technique for wastewater effluent reuse and landfill leachate treatment. The latter generates a refractory RO leachate concentrate (ROLC), for which cost-effective treatment is required. This study focuses on a two-step electrochemical method consisting of aluminum-based electrocoagulation (EC), and simultaneous electrooxidation-electrocoagulation with a titanium-based lead dioxide (Ti/s-PbO2) anode and aluminum cathode (EOEC) assembly. The sequence and electrode arrangements of the combined electrochemical process were investigated to determine the organic transformation, Ti/s-PbO2 anode viability, and energy consumption. Series-based EC-EOEC decreased the total chemical oxygen demand (COD) from 8750 mg L−1 to 380 mg L−1, a 96% removal efficiency, in 3.5 hours at 141 A m−2. Under a low energy consumption of 28.7 kWh kgCOD−1, the ROLC biodegradability (BOD5/COD) significantly increased from 0.015 to 0.530, which was ascribed to aromatic removal (e.g., -C=C) and an increase in -COOH functional groups. Furthermore, the rapid removal of natural organic matter and increase in pH elevation from EC suppressed the dissolution of Pb from the Ti/s-PbO2 anode during the subsequent EOEC, thereby leaving 0.061 mg L−1 in the ROLC after treatment. The treatment cost was 3.86 USD kgCOD−1, which was approximately 34% lower than that of previously reported electrochemical processes for ROLC treatment. These findings obtained with a real RO concentrate provide a foundation for scaling up this new electrochemical treatment approach.

Stressed organelles are often challenging to image with canonical organelle probes owing to their propensity to dissipate from stressed organelles. We herein report the imaging of stressed lysosomes with color-switchable glyco-probes that contain an entity of mannose-6-carboxylate or sialic acid for targeting to and long-term retention in stressed lysosomes, and a diad of fluorescein/rhodamine-X-lactam exhibiting dramatic red-to-green fluorescence shift upon pH elevation. Relative to acidotropic dyes prone to dissipate from pH-elevated lysosomes, both glyco-probes are stably trapped in lysosomes without resorting to lysosomal acidity. Importantly, these probes are red emissive in acidic lysosomes (pH 4.5-5.8), but switched to green fluorescence in lysosomes of pH 6.0-7.4, allowing dual color discrimination of lysosomal pH alterations in cell starvation. These results support the use of sugar-armed sensors to investigate stressed lysosomes in biology and disease.

Chronic acid deposition affects many temperate hardwood forests of the northeastern United States, reduces soil pH and phosphorus (P) availability, and can alter the structure and function of soil microbial communities. The strategies that microorganisms possess for survival in acidic, low P soil come at a carbon (C) cost. Thus, how microbial communities respond to soil acidification in forests may be influenced by plant phenological stage as C allocation belowground varies, however, this remains largely unexplored. In this study, we examined microbial communities in an ecosystem level manipulative experiment where pH and/or P availability were elevated in three separate forests in Northeastern Ohio. Tag-encoded pyrosequencing was used to examine bacterial and fungal community structure at five time points across one year corresponding to plant phenological stages. We found significant effects of pH treatment and time on fungal and bacterial communities in soil. However, we found no interaction between pH treatment and time of sampling for fungal communities and only a weak interaction between pH elevation and time for bacterial communities, suggesting that microbial community responses to soil pH are largely independent of plant phenological stage. In addition, fungal communities were structured largely by site, suggesting that fungi were responding to differences between the forests, such as plant community differences.

Reef-building corals are surrounded by complex microenvironments (i.e. concentration boundary layers) that partially isolate them from the ambient seawater. Although the presence of such concentration boundary layers (CBLs) could potentially play a role in mitigating the negative impacts of climate change stressors, their role is poorly understood. Furthermore, it is largely unknown how heat stress-induced bleaching affects O2 and pH dynamics across the CBLs of coral, particularly in branching species. We experimentally exposed the common coral species Acropora aspera to heat stress for 13 d and conducted a range of physiological and daytime microsensor measurements to determine the effects of bleaching on O2 and pH gradients across the CBL. Heat stress equivalent to 24 degree heating days (3.4 degree heating weeks) resulted in visible bleaching and significant declines in photochemical efficiency, photosynthesis rates and photosynthesis to respiration (P/R) ratios, whereas dark respiration and calcification rates were not impacted. As a consequence, bleached A. aspera had significantly lower (− 13%) surface O2 concentrations during the day than healthy corals, with concentrations being lower than that of the ambient seawater, thus resulting in O2 uptake from the seawater. Furthermore, we show here that Acropora, and potentially branching corals in general, have among the lowest surface pH elevation of all corals studied to date (0.041 units), which could contribute to their higher sensitivity to ocean acidification. Additionally, bleached A. aspera no longer elevated their surface pH above ambient seawater values and, therefore, had essentially no [H+] CBL. These findings demonstrate that heat stress-induced bleaching has negative effects on pH elevation and [H+] CBL thickness, which may increase the overall susceptibility of coral to the combined impacts of ocean acidification and warming.

Partial oxidation of defined Fe2+ solutions is a well-known method for magnetite synthesis in batch systems. The partial oxidation method could serve as basis for an iron removal process in drinking water production, yielding magnetite (Fe3O4) as a compact and valuable product. As a first step toward such a process, a series of experiments was carried out, in which magnetite was synthesized from an Fe2+ solution in a 2 L continuous stirred tank reactor (CSTR) at atmospheric pressure and 32 °C. In four experiments, elevating the pH from an initial value of 5.5 or 6.0 to a final value of 6.8, 7.0 or 7.5 caused green rust to form, eventually leading to magnetite. Formation of NH4+ in the reactor indicated that NO3− and subsequently NO2− served as the oxidant. However, mass flow analysis revealed an influx of O2 to the reactor. In a subsequent experiment, magnetite formation was achieved in the absence of added nitrate. In another experiment, seeding with magnetite particles led to additional magnetite precipitation without the need for a pH elevation step. Our results show, for the first time, that continuous magnetite formation from an Fe2+ solution is possible under mild conditions, without the need for extensive addition of chemicals.

Microbial electrolysis batch reactor systems were studied employing different conditions, paying attention on the effect that biocathode potential has on pH and system performance, with the overall aim to distinguish sulphate reduction from H2 evolution. Inocula from pure strains (Desulfovibrio paquesii and Desulfobacter halotolerans) were compared to a natural source conditioned inoculum. The natural inoculum possess the potential for sulphate reduction on serum bottles experiments due to the activity of mutualistic bacteria (Sedimentibacter sp. and Bacteroides sp.) that assist sulphate-reducing bacterial cells (Desulfovibrio sp.) present in the consortium. Electrochemical batch reactors were monitored at two different potentials (graphite-bar cathodes poised at -900 and -400mV versus standard hydrogen electrode) in an attempt to isolate bioelectrochemical sulphate reduction from hydrogen evolution. At -900mV all inocula were able to reduce sulphate with the consortium demonstrating superior performance (SO42- consumption: 25.71gm-2day-1), despite the high alkalinisation of the media. At -400mV only the pure Desulfobacter halotolerans inoculated system was able to reduce sulphate (SO42- consumption: 17.47gm-2day-1) and, in this potential condition, pH elevation was less for all systems, confirming direct (or at least preferential) bioelectrochemical reduction of sulphate over H2 production.

The pellicles formation, microbial changes and lactic acid utilisation during the aerobic deterioration of Sichuan pickle were discussed in this study. By plate counting, chemical detection and HPLC analysis, the aerobic deterioration of Sichuan pickle was featured by microbial growth, pellicle formation, lactic acid decrease and pH elevation. Bacteria dominated in pellicles and the pellicles present morphological change from smooth to wrinkly along with the aerobic deteriorating process. Nine species of bacteria were identified and responsible for the pellicle formation. Combined with Lactobacillus plantarum, eight pellicle‐forming bacteria were the dominant lactic acid consuming organisms in deteriorating Sichuan pickle. Especially under the harsh acid condition of the early deteriorating period, Lb. plantarum, pellicle‐forming bacteria Bacillus amyloliquefaciens, B. subtilis and Citrobacter freundii participated in the pellicles, utilised lactic acid and increased the brine pH effectively. Sequence analysis of 16S rDNA libraries suggested that the resulting pH of 4.8–5.0 initiated the growth of more undesirable organisms, and the pellicle bacterial diversity changed greatly compared with that in the early deteriorating period. The study indicated the important role of pellicles in the initiation of Sichuan pickle's aerobic deterioration and enhanced our ability to understand and potentially control the aerobic deterioration.

One of the main problems of waste stabilization ponds (WSP) is that they cannot remove nutrients when treating wastewater. Polishing ponds (PP) can efficiently remove nitrogen and phosphorus from effluents after efficient anaerobic pretreatment. It shown that the feasibility of nutrient removal is directly related to the pH that is established in the ponds. WSP normally operate at near neutral pH, but the biological processes that develop in PP tend to cause an elevation of pH and this, in turn, triggers the mechanisms of nutrient removal in ponds. In PP oxygen production by photosynthesis predominates over the oxidation of organic material. The net oxygen production has an equivalent CO2 consumption and this induces an increase in pH. The mechanism for nitrogen removal was identified as the desorption of ammonia from the liquid phase of the ponds. It was established that in ponds with a uniform concentration profile in the liquid phase the process developed in accordance with Fick’s law. The governing mechanism of phosphorus removal was precipitation with ions present in the wastewater, presumably calcium and magnesium. Polishing ponds can be operated with two different hydrodynamic regimes: flow-through (FTPP) and sequential batch (SBPP) ponds. The SBPP have the advantage that the pH elevation is more rapid, and that the final pH is higher.

Veverimer is a polymer being developed as a potential treatment for metabolic acidosis in patients with chronic kidney disease. Veverimer selectively binds and removes hydrochloric acid from the gastrointestinal tract, resulting in an increase in serum bicarbonate. Veverimer is not systemically absorbed, so potential drug-drug interactions (DDIs) are limited to effects on the absorption of other oral drugs through binding to veverimer in the gastrointestinal tract or increases in gastric pH caused by veverimer binding to hydrochloric acid. In in vitro binding experiments using a panel of 16 test drugs, no positively charged, neutral or zwitterionic drugs bound to veverimer. Three negatively charged drugs (furosemide, aspirin, ethacrynic acid) bound to veverimer; however, this binding was reduced or eliminated in the presence of normal physiological concentrations (100-170 mM) of chloride. Veverimer increased gastric pH in vivo by 1.5-3 pH units. This pH elevation peaked within 1 hour and had returned to baseline after 1.5-3 hours. Omeprazole did not alter the effect of veverimer on gastric pH. The clinical relevance of in vitro binding and the transient increase in gastric pH was evaluated in human DDI studies using two drugs with the most binding to veverimer (furosemide, aspirin) and two additional drugs with pH-dependent solubility effecting absorption (dabigatran, warfarin). None of the four drugs showed clinically meaningful DDI with veverimer in human studies. Based on the physicochemical characteristics of veverimer and results from in vitro and human studies, veverimer is unlikely to have significant DDIs. Significance Statement Patients with chronic kidney disease, who are usually on many drugs, are vulnerable to drug-drug interactions (DDIs). The potential for DDIs with veverimer was evaluated based on the known site of action and physicochemical structure of the polymer, which restricts the compound to the gastrointestinal tract. Based on the findings from in vitro and human studies, we conclude that veverimer is unlikely to have clinically significant DDIs.

The enhancement effect of an environmentally friendly reducing agent, ascorbic acid (AA), on trichloroethene (TCE) degradation by Fe(III)-activated calcium peroxide (CP) was evaluated. The addition of AA accelerated the transformation of Fe(III) to Fe(II), and the complexation of Fe(III)/Fe(II) with AA and its products alleviated the precipitation of dissolved iron. These impacts enhanced the generation of reactive oxygen species (ROSs). Investigation of ROSs using chemical probe tests, electron paramagnetic resonance (EPR) tests, and radical scavenger tests strongly confirm large production of hydroxyl radicals (HO•) that is responsible for TCE degradation. The generation of Cl− from the degraded TCE was complete in the enhanced CP/Fe(III)/AA system. The investigation of solution matrix effects showed that the TCE degradation rate decreases with the increase in solution pH, while Cl−, SO42− and NO3− anions have minor impact. Conversely, HCO3− significantly inhibited TCE degradation due to pH elevation and HO• scavenging. The results of experiments performed using actual groundwater indicated that an increase in reagent doses are required for effective TCE removal. In summary, the potential effectiveness of the CP/Fe(III)/AA oxidation system for remediation of TCE contaminated groundwater has been demonstrated. Additional research is needed to develop the system for practical implementation.

Although c-type cytochrome (c-Cyt) involvement in many biological Fe(II) oxidation processes under microaerobic or anoxic conditions has been proposed, the detailed understanding of the molecular redox reaction of c-Cyts in the presence of Fe2 + is still lacking. In this study, the in situ spectral kinetics and spectroelectrochemistry of a commercial c-Cyt as a model protein was investigated under various environmental conditions (Fe(II) concentration, pH, and ionic strength). The concentrations of reduced c-Cyt (c-Cytred) increased gradually over time and then reached a steady state. The c-Cytred generation rate constants (k) increased with increasing initial Fe(II) concentrations (5–1000 μM), because the redox potentials (Eh) of Fe(II)/Fe(III) were lower with higher Fe(II) concentrations. The k values for c-Cytred generation increased with pH (5.5–8.0). The Eh of Fe(II)/Fe(III) decreased substantially with a slope of 0.177 per pH unit, revealing that the reduction capacity of Fe2 + increased dramatically with pH elevation. In addition, spectroelectrochemistry results revealed that the extent of c-Cytred was strongly dependent on pH, indicating that H+ was involved in the c-Cyt reduction process. Hence, the pH effects were attributed to the involvements of H+ in the reactions between Fe2 + and c-Cyt. The k values for c-Cytred generation decreased with increasing NaCl concentrations (0–1.0 M). The correlations between the kinetic rates and the concentrations/activities of Fe(II) species are discussed, with the results demonstrating that Fe2 + activity was the major factor influencing the reaction kinetics with different ionic strength. This study provides insights into the mechanisms of enzymatic iron oxidation process under anoxic conditions at the molecular level.

An older method for terazosin was reworked in order to reduce the analysis time from 90 min (2 × 45 min) to below 5 min. The method in European Pharmacopoeia (Ph.Eur.) investigates the specified impurities separately. The reason of the different methods is that the retention of two impurities is not adequate in reversed phase, not even with 100% water. Therefore ion-pair-chromatography has to be applied and since that two impurities absorb at low UV-wavelength they had to be analyzed by different method than the other specified impurities. In our new method we could improve the retention with pH elevation using a new type of stationary phases available for high pH applications. Also a detection wavelength could be selected that is appropriate for the detection and quantification of all impurities. The method development is the bottleneck of liquid chromatography even today, when more and more fast chromatographic systems are used. Expert knowledge with intelligent programs is available to reduce the time of method development and offer extra information about the robustness of the separation. Design of Experiments (DoE) for simultaneous optimization of gradient time (tG), temperature (T) and ternary eluent composition (tC) requires 12 experiments. A good alternative way to identify a certain peak in different chromatograms is the molecular mass of the compound, due to its high specificity. Liquid Chromatography–Mass Spectrometry (LC–MS) is now a routine technique and increasingly available in laboratories. In our experiment for the resolution- and retention modeling the DryLab4 method development software (Version 4.2) was used. In recent versions of the software the use of (m/z)-MS-data is possible along the UV-peak-area-tracking technology. The modelled and measured chromatograms showed excellent correlations. The average retention time deviations were ca. 0.5 s and there was no difference between the predicted and measured Rs,crit −values.

The pH is a primary index reflecting water quality in rivers. The Jian River and Chaobai River are two reclaimed water intake areas which have elevated pH. This elevated pH has a marked effect on both the phytoplankton, species in water and vegetation on the shore. Understanding the main reasons causing pH elevation in river water has important implications for river ecosystem management and the improvement of water quality and can provide a theoretical basis for the direction of water quality improvement. For this reason, each biogeochemical and physical process influencing pH changes in water was quantified along the flow direction in the Wenyu to Chaobai reclaimed water diversion project, in which proton consumption and production by such processes were monitored and calculated at five monitoring sections. The calculations indicated that photosynthesis and denitrification were the primary reasons for the increase of pH in the Jian River and Chaobai River. Oppositely, carbonate precipitation and sediment decomposition restricted the increase of pH in both rivers. In addition, CO2 emission to the air also promoted a increase of pH in the Jian River, while CO2 absorption from the air restricted the increase of pH in the Chaobai River. NO3- nitrogen in reclaimed water was not efficiently removed and the reclaimed water flow condition in the intake area created favorable conditions for photosynthesis of algae breeding and denitrification by microorganisms. Therefore, biogeochemical and physical processes that promoted the increase of pH were greater than inhibiting processes and the pH gradually increased along the flow direction. The contribution rates of photosynthesis and denitrification for the increase of pH were 55.48 and 27.09%, respectively, in the Jian River and 78.08 and 21.92%, respectively, in the Chaobai River. In addition, CO2 emission contributed 17.43% of the increase in pH in the Jian River.

Particle acidity is crucial to understand secondary formation processes in pollution events because of its substantial impacts on the physiochemical properties of PM2.5. Recently, particle pH predicted by thermodynamic modeling were used to elucidate the sulfate formation mechanism in China, but the results were biased and controversial. In this article, particle pH was found to be increase as a result of effective sulfur emission control. Benefit from strict pollution control actions, average PM2.5 concentration reduced to a low level (39.7 μg/m3) in urban Beijing during winter of 2017. Compare to history record (2014–2017), SO2 gradually decreased to a low level (3.2 ppbv in 2017 winter) while NO2 kept increasing (21.4 ppbv in 2017 winter). As a response, nitrate's contribution (23.0 μg/m3) to PM2.5 become dominant over sulfate (13.1 μg/m3) during the PM2.5 pollution. The nitrate to sulfate molar ratio significantly increased from 1 to 2.7 (value of 1999 and 2017). As particulate nitrate fraction significantly elevated, particle pH was also found to increase in winter Beijing given sufficient ammonia (average concentration 7.1 μg/m3, 12.9 μg/m3 during pollution). During PM2.5 pollution episodes, the particle pH predicted increased from 4.4 (moderate acidic) to 5.4 (near neutral) as nitrate to sulfate molar ratio increased from 1 to 5. It is found that the major H+ contributor S(VI) was mostly in the form of sulfate, showing anions were more neutralized as nitrate content enriched. In the final part, future prediction of particle acidity change was discussed via sensitivity tests: On one hand, nitrate rich particles would absorb more water compared to the sulfate rich particles. This absorption contrast doubles with low to moderate RH (20 % ~ 50 %). On the other hand, increased level of nitrate and ammonia would have synergetic effects leading to rapid elevation of particle pH to merely neutral (above 5.6). As moderate haze might occur more frequently with high ammonia and particulate nitrate concentration, the major chemical processes during haze events and the control target shall be re-evaluated to obtain the most effective control strategy.

Conditions responsible for growth and pH elevation by selected strains of Bacillus subtilis and Bacillus licheniformis were studied in order to assess the potential hazard of metabiosis occurring between Clostridium botulinum and mesophilic Bacillus species in aseptically packaged tomato juice. The effects of the initial tomato juice pH on the growth of these Bacillus strains were evaluated. Cultures of B. licheniformis previously identified by Fields et al. (6) were reclassified as B. subtilis because none grew under strict anaerobic conditions nor used propionate. B. subtilis did not grow under strict anaerobic conditions but could use oxygen if present in the environment. None of the B. subtilis or B. licheniformis strains grew at pH 4.0 or 4.2. Only B. subtilis 075-T-09 and B. licheniformis 64-83-46 strains isolated from acidic foods were able to grow at pH 4.4 in tomato juice. Anaerobically, B. licheniformis strains did not grow in tomato juice or tomato juice with added nitrate and thiamine and even showed a loss of viability. Both B. licheniformis and B. subtilis require oxygen for growth in tomato juice at pH 4.4.

Scleractinian corals promote the precipitation of their carbonate skeleton by elevating the pH and dissolved inorganic carbon (DIC) concentration of their calcifying fluid above that of seawater. The fact corals actively regulate their calcifying fluid chemistry implies the potential for acclimation to ocean acidification. However, the extent to which corals can adjust their regulation mechanism in the face of decreasing ocean pH has not been rigorously tested. Here I present a numerical model simulating pH and DIC up-regulation by corals, and use it to determine the relative importance of physiological regulation versus seawater conditions in controlling coral calcifying fluid chemistry. I show that external seawater temperature and buffering capacity exert the first-order control on the extent of pH elevation in the calcifying fluid and explain most of the observed inter- and intra-species variability. Conversely, physiological regulation, represented by the interplay between enzymatic proton pumping, carbon influx and the exchange of calcifying fluid with external seawater, contributes to some variability but remain relatively constant as seawater conditions change. The model quantitatively reproduces variations of calcifying fluid pH in natural Porites colonies, and predicts an average 0.16 unit decrease in Porites calcifying fluid pH, i.e., ~43% increase in H+ concentration, by the end of this century as a combined result of projected ocean warming and acidification, highlighting the susceptibility of coral calcification to future changes in ocean conditions. In addition, my findings support the development of coral-based seawater pH proxies, but suggest the influences of physicochemical and biological factors other than seawater pH must be considered.

A novel struvite crystallization method induced by electrochemical acidolysis of cheap magnesite was investigated to recover phosphorus from aqueous solution. Magnesite was confirmed to continuously dissolve in the anolyte whose pH stabilized at about 2. Driven by the electrical field force, over 90% of the released Mg2+ migrated to the cathode chamber via passing through the cation exchange membrane. The pH of the phosphate-containing aqueous solution in the cathode chamber was elevated to the appropriate pH fit for struvite crystallization. The products were identified as struvite crystals by scanning electron microscopy and X-ray diffraction. Increasing the magnesite dosage from 0.83 to 3.33 g L−1 promoted the phosphorus recovery efficiency from 2.2% to 78.3% at 3 d, which was attributed to sufficient Mg2+ supply. Increasing the applied voltage from 3 to 6 V improved the recovery efficiency from 43.6% to 76.4% at 1 d, since the enhanced current density of the electrochemical system markedly accelerated both the magnesite acidolysis and the catholyte pH elevation. The initial catholyte pH between 3 and 5 was found to benefit the phosphorus recovery due to the final catholyte pH fit for the struvite crystallization.

Liming is beneficial for plants as it promotes pH elevation, neutralization of toxic aluminum, increase in calcium (Ca²+) and magnesium (Mg²+) supply, and provides greater root systems. However, it is known that different species, mainly those native to the Cerrado, respond in different ways to this technique. Given the above, the objective of this study was to determine how Hymenaea stigonocarpa (“Jatobá-do-Cerrado”) seedlings respond to liming in Dystrophic Red Latosol. The plants were cultivated in four-liter pots, submitted to different base saturation (natural soil, 30, 45, 60 and 75% V) and maintained in a greenhouse. Biometrics, biomass, nutritional content and physiological parameters were evaluated. A difference in Ca²+ and Mg²+ contents between leaves and stems was observed, leading to significant reductions in stomatal conductance, transpiration, internal CO2 concentration and internal and external CO2 concentration ratios, resulting in a reduction of the investment in growth and biomass. Given these results, there is no need for liming in the production of H. stigonocarpa seedlings in a Dystrophic Red Latosol. RESUMO A calagem é benéfica para as plantas por promover a elevação do pH, neutralização do alumínio tóxico, aumentar o fornecimento de cálcio (Ca²+) e magnésio (Mg²+) e propiciar maior sistema radicular. No entanto, sabe-se que as espécies, principalmente nativas do Cerrado, respondem de formas distintas a essa técnica. Diante do exposto, o objetivo deste estudo foi determinar de que forma mudas de Hymenaea stigonocarpa (“Jatobá-do-Cerrado”) respondem a calagem em Latossolo Vermelho Distrófico. As plantas foram cultivadas em vasos de quatro litros, submetidas a diferentes saturações de bases (solo natural, 30, 45, 60 e 75% de V) e mantidas em casa de vegetação. Foram avaliadas a biometria, biomassa, teor nutricional e parâmetros fisiológicos. Houve diferença para o teor de Ca²+ e Mg²+ nas folhas e caule e isso culminou na redução significativa da condutância estomática, transpiração, concentração interna de CO2 e a relação concentração interna e externa de CO2, o que levou a redução do investimento em crescimento e biomassa. Diante dos resultados obtidos, para a produção de mudas de H. stigonocarpa em Latossolo Vermelho Distrófico não há necessidade de realizar calagem.

Biogas purification via water scrubbing produces effluent containing dissolved CH4, H2S, and CO2, which should be removed to reduce greenhouse gas emissions and increase its potential for water regeneration. In this study, a reactor built with air supplies at the top and bottom was utilized for the treatment of biogas purification effluent through biological oxidation and physical stripping processes. Up to 98% of CH4 was removed through biological treatment at a hydraulic retention time of 2 hr and an upper airflow rate of 2.02 L/day. Additionally, a minimum CH4 concentration of 0.04% with no trace of H2S gas was detected in the off gas. Meanwhile, a white precipitate was captured on the carrier showing the formation of sulfur. According to the developed mathematical model, an upper airflow rate of greater than 2.02 L/day showed a small deterioration in CH4 removal performance after reaching the maximum value, whereas a 50 L/day bottom airflow rate was required to strip the CO2 efficiently and raise the effluent pH from 5.64 to 7.3. Microbiological analysis confirmed the presence of type 1 methanotroph communities dominated by Methylobacter and Methylocaldum. However, bacterial communities promoting sulfide oxidation were dominated by Hyphomicrobium.

Reverse osmosis (RO) seawater desalination is a widely applied technological process to supply potable water worldwide. Recently, saline groundwater (SGW) pumped from beach wells in coastal aquifers that penetrate beneath the freshwater-seawater interface is considered as a better alternative water source to RO seawater desalination as it is naturally filtered within the sediments which reduces membrane fouling and pre-treatment costs. The SGW of many coastal aquifers is anoxic – and thus, in a low redox stage – has elevated concentrations of dissolved manganese, iron and sulfides. We studied the influence of the SGW redox stage and chemistry on the performance - permeate flux and fouling properties - of RO desalination process. SGWs from three different coastal aquifers were sampled and characterized chemically, and RO desalination experiments were performed under inert and oxidized conditions. Our results show that all three aquifers have anoxic saline groundwater and two of them have intensive anaerobic oxidation of organic matter. Two aquifers were found to be in the denitrification stage or slightly lower and the third one in the sulfate reduction stage. Our results indicate that the natural redox stage of SGWs from coastal aquifers affects the performance of RO desalination. All SGW types showed better RO performance over seawater desalination. Furthermore, air oxidation of the SGW was accompanied with pH elevation, which increased the membrane fouling. Hence, keeping the feed water unexposed to atmospheric conditions for maintaining the natural reducing stage of the SGW is crucial for low fouling potential. The observed benefits of using naturally reduced SGW in RO desalination have significant implications for reduction in overall process costs.

Much research has been performed to synthesize precipitated calcium carbonate (PCC) from calcium extracted from blast furnace (BF) slag. A significant challenge has been obtaining a chemically pure sample with a homogeneous crystal structure and narrow particle size distribution, which can have profitable marketability (e.g. in the papermaking industry). The aim of this study was to investigate the influence of alternative and combinatory processing strategies on the chemical, morphological and mineralogical properties of BF slag-derived PCC. In a first phase, the physicochemical removal of impurities from the leachate, prior to the carbonation, was investigated, by means of temperature reduction (20 → 1°C) and pH elevation (4.4 → 8.4); this led to selective precipitation of Al, Mg and Si. In a second phase, the operational conditions of the carbonation step were optimized, by lessening the severity of the operational conditions (90 → 30°C and 6 → 2 bar,CO2) and by reducing the amount of acid-neutralizing base (1.0 → 0.85 M,Na+/M,CH3COO–) added during the carbonation process; this led to more selective calcium carbonation. Using these strategies, it was possible to synthesize chemically pure PCC (>98% Ca) with uniform morphology (scalenohedral), homogeneous mineralogy (>88% calcite) and narrow (1.09 uniformity), small (D50 = 1.1 μm) particle size distribution. KU Leuven Industrial Research Fund (IOF); KU Leuven Special Research Fund (BOF).

The coming global phosphorus (P) crisis makes P recovery from wastewater become an inevitable choice. Hydroxyapatite (HAP) crystallization is an important approach for P recovery, but its requirements for high alkali and acid are unaffordable. Thus, a microbial electrolysis phosphorus-recovery cell (MEPRC) was developed to cut down the alkali cost via raising the wastewater pH (over 11) in the cathode chamber, and the acid cost via producing acid in the acid-production chamber. HAP was confirmed to be the final recovered products, and P recovery efficiency over 80% was achieved at 24-h operation. To optimize the P recovery performance of this system, the effects of the key factors including applied voltage, P initial concentration and Ca/P ration were investigated. High voltage could promote the rate of P recovery but had slight effect on the eventual recovery efficiency (elevated from 88.5 to 91.1%). High P initial concentration (15.0 mM) could slow down the pH elevation, contributing to the low P recovery efficiency (50.1%) within 24 h. However, prolonging the operation could break the buffering and obtain a satisfactory P recovery efficiency (87.2%) at 36 h. Besides, sufficient calcium ions were favorable to the P recovery. In addition, P recovery cost analyses of the MEPRC indicated that it might be a low-cost technology for P recovery. Moreover, the simultaneously produced acid could be used to neutralize the effluent after P recovery with high pH value. These results demonstrate the feasibility of MEPRC for cost-effective P recovery from wastewater.

Great efforts have been paid to develop methodologies for cancer stem-like cell (CSLC) isolation in anti-cancer research. The major obstacle lies in the lack of generic biomarkers for different cancer types and the requirement of complicated immuno-labeling procedures. The purpose of this study is to establish a label-free platform for CSLC isolation using pH-responsive chitosan. Based on the adhesive heterogeneity, 15.7 ± 1.9 % of human non-small cell lung cancer (NSCLC) cell line A549 detached from the chitosan substrate following medium pH elevation from 6.99 to 7.65 within 1 h. As a result, this subpopulation of cells with low adhesiveness exhibited superior CSLC hallmarks, including self-renewal, invasive and metastatic potential, therapeutic-resistance, colony formation in vitro, as well as nude mice xenograft in vivo for tumorigenesis, in comparison with their high-adhesive counterpart. Furthermore, integrin β4 is decisive in controlling CSLC detachment of NSCLC. Conclusively, this pH-dependent isolation provides new insights into biomaterial-based CSLC isolation.

This study evaluates whether a higher level of dietary protein could alleviate pH stress in Chinese mitten crab. Three diets with protein levels at 30%, 35% and 40% were used to feed crab for 8 weeks to determine the differential effect of dietary protein on growth, antioxidant capacity, inflammatory response and apoptotic factors at normal pH (7.8) and high pH (9.5) values. The pH elevation depressed growth performance in terms of weight gain (WG), specific growth rate (SGR) and feed conversion rate (FCR), but this effect significantly depended on the level of dietary protein. The higher level of protein significantly improved WG, SGR and FCR at high pH. Besides, high pH weakened the antioxidant capacity of crab fed the 30% protein diet by decreasing glutathione (GSH) in the hepatopancreas, and resulting significantly higher malondialdehyde crab fed 30% protein than those fed other two protein levels. The dependent effect of dietary protein and pH was also found in antioxidant capacity. The higher protein diet increased GSH, superoxide dismutase and glutathione S-transferase in the hepatopancreas at high pH. In addition, high pH triggered pro-inflammatory and pro-apoptotic factors in the 30% protein group by upregulating the pro-apoptotic and pro-inflammatory genes including lipopolysaccharide-induced TNF-alpha factor, p38 mitogen-activated protein kinase, a disintegrin and metalloproteinase domain-containing protein 17, Bcl-2-associated X and Cysteine-aspartic acid protease 3. The higher protein diets downregulated pro-apoptotic and pro-inflammatory genes at high pH. In conclusion, the high pH caused a marked growth retardation and poor feed efficiency, triggered oxidative stress and pro-inflammatory and increased pro-apoptotic factors in crab fed the low protein diet. Higher protein diets alleviated the negative effect of pH in the Chinese mitten crab. This study suggests that a higher protein diet can counteract the negative effect of high pH in Chinese mitten crab farming.

Large amount of high-strength ammonium industrial wastewater was discharged in China causing serious environmental pollution. In this work, an electrochemically assisted sulfate reduction autotrophic denitrification and nitrification integrated (e-SANI) process was developed by coupling a microbial electrolysis cell (MEC) with a conventional SANI process for high-strength ammonium wastewater treatment. In the e-SANI process, the MEC cathode was used for hydrogen-oxidizing autotrophic denitrification and simultaneously for pH elevation, while the MEC anode oxidized residual sulfide in effluent for elemental sulfur recovery. As a key operational parameter, the cathode potential was controlled at −0.8, −0.9 and −1.0 V (vs. Ag/AgCl, saturated KCl) to evaluate the total nitrogen removal efficiency in the e-SANI process. The results indicated the maximum total nitrogen removal efficiency was significantly improved in the e-SANI system (56.9 ± 1.4% at −1.0 V) compared to the conventional SANI system (34.8 ± 2.3%). With the assistance of the anode, residual sulfide in effluent can be significantly eliminated through oxidation to elemental sulfur. Furthermore, microbial community in the e-SANI system was analyzed and Bacteroides and Thiobacillus were identified as the predominant denitrification bacteria in the cathode chamber. Conclusively, the developed e-SANI system extends the application of the SANI process and can be a promising technology for high-strength ammonium wastewater treatment.

Summer cyanobacterial blooms caused an elevation in pH (9 to ~10.5) that lasted for weeks in the shallow and tidal-fresh region of the Sassafras River, a tributary of Chesapeake Bay (USA). Elevated pH promoted desorption of sedimentary inorganic phosphorus and facilitated conversion of ammonium (NH4+) to ammonia (NH3). In this study, we investigated pH effects on exchangeable NH4+ desorption, pore water diffusion and the flux rates of NH4+, soluble reactive phosphorus (SRP) and nitrate (NO3−), nitrification, denitrification, and oxygen consumption. Elevated pH enhanced desorption of exchangeable NH4+ through NH3 formation from both pore water and adsorbed NH4+ pools. Progressive penetration of high pH from the overlying water into sediment promoted the mobility of SRP and the release of total ammonium (NH4+ and NH3) into the pore water. At elevated pH levels, high sediment-water effluxes of SRP and total ammonium were associated with reduction of nitrification, denitrification and oxygen consumption rates. Alkaline pH and the toxicity of NH3 may inhibit nitrification in the thin aerobic zone, simultaneously constraining coupled nitrification–denitrification with limited NO3− supply and high pH penetration into the anaerobic zone. Geochemical feedbacks to pH elevation, such as enhancement of dissolved nutrient effluxes and reduction in N2 loss via denitrification, may enhance the persistence of cyanobacterial blooms in shallow water ecosystems.

For pathogenic microbes to survive ingestion by macrophages, they must subvert powerful microbicidal mechanisms within the phagolysosome. After ingestion, Candida albicans undergoes a morphological transition producing hyphae, while the surrounding phagosome exhibits a loss of phagosomal acidity., For pathogenic microbes to survive ingestion by macrophages, they must subvert powerful microbicidal mechanisms within the phagolysosome. After ingestion, Candida albicans undergoes a morphological transition producing hyphae, while the surrounding phagosome exhibits a loss of phagosomal acidity. However, how these two events are related has remained enigmatic. Now Westman et al. (mBio 9:e01226-18, 2018, https://doi.org/10.1128/mBio.01226-18) report that phagosomal neutralization results from disruption of phagosomal membrane integrity by the enlarging hyphae, directly implicating the morphological transition in physical damage that promotes intracellular survival. The C. albicans intracellular strategy shows parallels with another fungal pathogen, Cryptococcus neoformans, where a morphological changed involving capsular enlargement intracellularly is associated with loss of membrane integrity and death of the host cell. These similarities among distantly related pathogenic fungi suggest that morphological transitions that are common in fungi directly affect the outcome of the fungal cell-macrophage interaction. For this class of organisms, form determines fate in the intracellular environment.

Nickel and chromium existing in stainless-steel crowns (SSCs, used in pediatric dentistry) might be cytotoxic and allergenic. However, no in vivo studies have examined their salivary levels in children using SSCs, or in young children without SSCs. Also, the effect of acidity on metal ion release has not yet been evaluated in any previous in vivo studies in the whole literature. Therefore, this preliminary before-after clinical trial was conducted. Salivary nickel/chromium levels of 30 children before and after 2 months of placement of SSCs were measured using atomic absorption spectrophotometry. Salivary pH was measured with a digital pH meter. The effects of treatment, pH, number of SSCs, gender, and age on salivary ions were analyzed statistically (α = 0.05, β = 0.15). Salivary nickel concentrations increased from 4.9010 ± 4.7390 to 5.6320 ± 4.7210 μg/L (P = 0.000, paired t test). Chromium increased from 0.3273 ± 0.5214 to 0.4199 ± 0.6404 μg/L (P = 0.016). Saliva pH increased from 6.81 ± 0.52 to 7.04 ± 0.47 (P = 0.000). Ion levels were not correlated with pH (P > 0.14), except chromium in the follow-up (rho = − 0.435, P = 0.016). Nickel increase (but not chromium increase) was correlated with pH increase (rho = 0.367, P = 0.046). Age was only correlated with baseline chromium (rho = 0.373, P = 0.042). Being male was associated with baseline/follow-up nickel levels (P ≤ 0.030). SSC number was not correlated with ions or pH (P > 0.36). It was shown for the first time that SSCs might increase salivary nickel and chromium concentrations and reduce saliva acidity. Nickel increase might be in line with pH elevation. The raised pH might be associated with reduced chromium release. Boys might have higher nickel levels than might girls, with or without SSCs.

The boron isotope composition of foraminifera provides a powerful tracer for CO2 change over geological time. This proxy is based on the equilibrium of boron and its isotopes in seawater, which is a function of pH. However while the chemical principles underlying this proxy are well understood, its reliability has previously been questioned, due to the difficulty of boron isotope (δ11B) analysis on foraminferal samples and questions regarding calibrations between δ11B and pH. This chapter reviews the current state of the δ11B-pH proxy in foraminfera, including the pioneering studies that established this proxy’s potential, and the recent work that has improved understanding of boron isotope systematics in foraminifera and applied this tracer to the geological record. The theoretical background of the δ11B-pH proxy is introduced, including an accurate formulation of the boron isotope mass balance equations. Sample preparation and analysis procedures are then reviewed, with discussion of sample cleaning, the potential influence of diagenesis, and the strengths and weaknesses of boron purification by column chromatography versus microsublimation, and analysis by NTIMS versus MC-ICPMS. The systematics of boron isotopes in foraminifera are discussed in detail, including results from benthic and planktic taxa, and models of boron incorporation, fractionation, and biomineralisation. Benthic taxa from the deep ocean have δ11B within error of borate ion at seawater pH. This is most easily explained by simple incorporation of borate ion at the pH of seawater. Planktic foraminifera have δ11B close to borate ion, but with minor offsets. These may be driven by physiological influences on the foraminiferal microenvironment; a novel explanation is also suggested for the reduced δ11B-pH sensitivities observed in culture, based on variable calcification rates. Biomineralisation influences on boron isotopes are then explored, addressing the apparently contradictory observations that foraminifera manipulate pH during chamber formation yet their δ11B appears to record the pH of ambient seawater. Potential solutions include the influences of magnesium-removal and carbon concentration, and the possibility that pH elevation is most pronounced during initial chamber formation under favourable environmental conditions. The steps required to reconstruct pH and pCO2 from δ11B are then reviewed, including the influence of seawater chemistry on boron equilibrium, the evolution of seawater δ11B, and the influence of second carbonate system parameters on δ11B-based reconstructions of pCO2. Applications of foraminiferal δ11B to the geological record are highlighted, including studies that trace CO2 storage and release during recent ice ages, and reconstructions of pCO2 over the Cenozoic. Relevant computer codes and data associated with this article are made available online.

Amyloid fibril polymorphism is not well understood despite its potential importance for biological activity and associated toxicity. Controlling the polymorphism of mature fibrils including their morphology and supramolecular chirality by postfibrillation changes in the local environment is the subject of this study. Specifically, the effect of pH on the stability and dynamics of HET-s (218-289) prion fibrils has been determined through the use of vibrational circular dichroism (VCD), deep UV resonance Raman, and fluorescence spectroscopies. It was found that a change in solution pH causes deprotonation of Asp and Glu amino acid residues on the surface of HET-s (218-289) prion fibrils and triggers rapid transformation of one supramolecular chiral polymorph into another. This process involves changes in higher order arrangements like lateral filament and fibril association and their supramolecular chirality, while the fibril cross-β core remains intact. This work suggests a hypothetical mechanism for HET-s (218-289) prion fibril refolding and proposes that the interconversion between fibril polymorphs driven by the solution environment change is a general property of amyloid fibrils.

Treatment of ship ballast water with sodium hydroxide (NaOH) is one method currently being developed to minimize the risk to introduce aquatic invasive species. The bactericidal capability of sodium hydroxide was determined for 148 bacterial strains from ballast water collected in 2009 and 2010 from the M/V Indiana Harbor, a bulk-freight carrier plying the Laurentian Great Lakes, USA. Primary culture of bacteria was done using brain heart infusion agar and a developmental medium. Strains were characterized based on PCR amplification and sequencing of a portion of the 16S rRNA gene. Sequence similarities (99+ %) were determined by comparison with the National Center for Biotechnology Information (NCBI) GenBank catalog. Flavobacterium spp. were the most prevalent bacteria characterized in 2009, comprising 51.1% (24/47) of the total, and Pseudomonas spp. (62/101; 61.4%) and Brevundimonas spp. (22/101; 21.8%) were the predominate bacteria recovered in 2010; together, comprising 83.2% (84/101) of the total. Testing was done in tryptic soy broth (TSB) medium adjusted with 5 N NaOH. Growth of each strain was evaluated at pH 10.0, pH 11.0 and pH 12.0, and 4 h up to 72 h. The median cell count at 0 h for 148 cultures was 5.20 × 10(6) cfu/mL with a range 1.02 × 10(5)-1.60 × 10(8) cfu/mL. The TSB adjusted to pH 10.0 and incubation for less than 24 h was bactericidal to 52 (35.1%) strains. Growth in pH 11.0 TSB for less than 4 h was bactericidal to 131 (88.5%) strains and pH 11.0 within 12 h was bactericidal to 141 (95.3%). One strain, Bacillus horikoshii, survived the harshest treatment, pH 12.0 for 72 h.

Impairment of gastric digestion due to pH elevation increases the risk for food allergy induction. As patients after Roux-en-Y gastric bypass (RYGB) surgery have lower gastric acidity and less gastric gland secretion, we aimed to analyse in a prospective study the effect of limiting gastric digestion capacity by surgical intervention on the immune response towards allergens. Nine patients undergoing RYGB surgery for morbid obesity and one control patient having undergone surgery for treatment of an incisional hernia were enrolled in the study. Before and 1, 3, 6, 9 and 12 months after surgery, blood was collected for analysis of specific IgE antibodies, and patients were subjected to skin prick testing with 16 food and 18 aeroallergens. Skin prick test results revealed an increase of positive reactions indicating sensitisations towards the tested food and aeroallergens in 77.8 and 88.9 % of the patients, respectively, after surgical elimination of gastric digestion. These results were in line with elevated titers of food- and aeroallergen-specific IgE antibodies in 7 out of 9 (7/9) and 5/9 patients, respectively, after RYGB surgery. Serum cytokine levels revealed a mixed response for IFN-γ and were mostly beneath detection limit for IL-4. A change of IgE reactivity pattern occurred after impairment of gastric digestion due to surgical elimination underlining the important gastric gatekeeping function during oral sensitisation. Even though this study indicates an increased allergy risk for gastric bypass patients, further studies are needed to investigate in-depth the immunological changes associated with RYGB surgery.