Morphology dependent effect of γ-Al2O3 for ethanol dehydration: nanorods and nanosheets

CrystEngComm ◽  
2022 ◽  
Author(s):  
Li Deng ◽  
Shaobo Han ◽  
Di Zhou ◽  
Yong Li ◽  
Wenjie Shen
Keyword(s):  
Ethanol Dehydration ◽  
Dependent Effect ◽  
Ph Values ◽  
Tetrapropylammonium Bromide ◽  
Acidic Conditions

Boehmite (γ-AlOOH) nanorods and nanoplates were hydrothermally fabricated with the aid of tetrapropylammonium bromide by modifying the pH values of solutions. Under acidic conditions, the adsorption of anions like Br-...

Removal of Dyes from Aqueous Solutions by Adsorption on Chrome-Tanned Solid Wastes Generated in the Leather Industry

2003 ◽  
Vol 38 (2) ◽  
pp. 393-411 ◽  
Author(s):  
Soufiane Tahiri ◽  
Ali Messaoudi ◽  
Abderrahman Albizane ◽  
Mohamed Azzi ◽  
Mohamed Bouhria ◽  
...  
Keyword(s):  
Aqueous Solutions ◽  
Operating Conditions ◽  
Solid Wastes ◽  
Cationic Dyes ◽  
Optimum Operating ◽  
Leather Industry ◽  
Anionic Dyes ◽  
Ph Values ◽  
Acidic Conditions ◽  
Dyes Adsorption

Abstract In this work, the ability of chrome shavings and of crust leather buffing dusts to remove dyes from aqueous solutions has been studied. Buffing dusts proved to be a much better adsorbent than chrome shavings for cationic dyes. The adsorption of anionic dyes is very important on two studied wastes. The pH has an obvious influence on the adsorption of dyes. Adsorption of cationic dyes is less favourable under acidic conditions (pH <3.5) and at high pH values (pH >10.5). The adsorption of anionic dyes on both adsorbents is more favourable under acidic conditions (pH <3). The adsorption on chrome shavings is improved by the use of finer particles. The kinetic adsorption was also studied. Adsorption isotherms, at the optimum operating conditions, were determined. Adsorption follows the Langmuir model. The isotherm parameters have been calculated. The column technique could be applied to treat significant volumes of solutions.

Resistance of Acid-Adapted Salmonellae to Organic Acid Rinses on Beef†

1995 ◽  
Vol 58 (9) ◽  
pp. 973-976 ◽  
Author(s):  
J. S. DICKSON ◽  
M. R. KUNDURU
Keyword(s):  
Organic Acid ◽  
Parent Strain ◽  
Good Growth ◽  
Acid Solutions ◽  
Bacterial Populations ◽  
Acid Adaptation ◽  
Ph Values ◽  
Atcc Strain ◽  
Lean Beef ◽  
Acidic Conditions

Four strains of salmonellae, including three bovine isolates and an ATCC strain, were adapted to growth in acidic conditions by sequential transfer in tryptic soy broth with reduced pH values. The cultures were transferred until good growth (approximately log107 CFU/ml) was obtained within 24 h at 37°C at pH 5.0. Lean beef tissue was inoculated by immersion into either the acid-adapted or the homologous parent strain of each bacterium. The inoculated tissue was rinsed for 10s in 1.5% or 3.0% lactic acid solutions at 23°C or 55°C. Reductions in bacterial populations were compared between the parent and acid-adapted strains to determine if the acid-adapted strains were more resistant to the organic acid rinses. Acid-adapted strains had either equal or greater sensitivity to organic acid rinses than their homologous parent strains, indicating that acid adaptation did not result in bacteria which were resistant to organic acid rinses. Acid-adapted strains had significantly lower D55°C− values than their homologous parent strains.

scholarly journals Large Differences in Urinary Benzene Metabolite S-Phenylmercapturic Acid Quantitation: A Comparison of Five LC–MS-MS Methods

2020 ◽  
Author(s):  
Denise S Tevis ◽  
Andrew Willmore ◽  
Deepak Bhandari ◽  
Brett Bowman ◽  
Chloe Biren ◽  
...  
Keyword(s):  
Human Urine ◽  
Analytical Methods ◽  
Urine Samples ◽  
Genotoxic Carcinogen ◽  
Human Urine Samples ◽  
Ph Values ◽  
Wide Range ◽  
Acidic Conditions ◽  
Hematological Abnormalities ◽  
Reference Samples

Abstract Benzene is a known genotoxic carcinogen linked to many hematological abnormalities. S-phenylmercapturic acid (PHMA, N-acetyl-S-(phenyl)-L-cysteine, CAS# 4775-80-8) is a urinary metabolite of benzene and is used as a biomarker to assess benzene exposure. Pre-S-phenylmercapturic acid (pre-PHMA) is a PHMA precursor that dehydrates to PHMA at acidic pH. Published analytical methods that measure urinary PHMA adjust urine samples to a wide range of pH values using several types of acid, potentially leading to highly variable results depending on the concentration of pre-PHMA in a sample. Information is lacking on the variation in sample preparation among laboratories regularly measuring PHMA and the effect of those differences on PHMA quantitation in human urine samples. To investigate the differences in PHMA quantitation, we conducted an inter-laboratory comparison that included the analysis of 50 anonymous human urine samples (25 self-identified smokers and 25 self-identified non-smokers), quality control samples and commercially available reference samples in five laboratories using different analytical methods. Observed urinary PHMA concentrations were proportionally higher at lower pH, and results for anonymous urine samples varied widely among the methods. The method with the neutral preparation pH yielded results about 60% lower than the method using the most acidic conditions. Samples spiked with PHMA showed little variation, suggesting that the variability in results in human urine samples across methods is driven by the acid-mediated conversion of pre-PHMA to PHMA.

Heat Resistance of Alicyclobacillus acidoterrestris Spores as Affected by Various pH Values and Organic Acids‡

1998 ◽  
Vol 61 (1) ◽  
pp. 41-46 ◽  
Author(s):  
APRIL J. PONTIUS ◽  
JOHN E. RUSHING ◽  
PEGGY M. FOEGEDING
Keyword(s):  
Heat Resistance ◽  
Fruit Juice ◽  
Ion Concentration ◽  
Thermal Processes ◽  
Alicyclobacillus Acidoterrestris ◽  
Hydrogen Ion Concentration ◽  
Ph Values ◽  
Acid Type ◽  
Acidic Conditions ◽  
D Values

Alicyclobacillus acidoterrestris, a thermoacidophilic sporeformer, has caused spoilage of fruit juices which had been treated with thermal processes intended to commercially sterilize the juice. The objective of this research was to document the effect of pH, acid, and temperature on the heat resistance of spores of three fruit-juice isolates of A. acidoterrestris. The thermal resistance of spores of A. acidoterrestris strains VF, WAC, and IP were studied in a model fruit-juice system composed of 12% glucose and 30 mM of either citric, malic, or tartaric acid, adjusted to selected pH values ranging from 2.8 to 4.0. Decimal reduction times (D values) and inactivation rates were determined. Spores of strains VF and WAC were similarly resistant to heat under acidic conditions, while strain IP spores were less resistant. In the range of pH 2.8 to 4.0, a statistically significant effect of hydrogen ion concentration on heat resistance was observed at lower temperatures, but not at the higher temperatures. For example, at 91 °C and pH 3.1 and 3.7, D values were 31.3 and 54.3 min, respectively, while at 97°C D values at pH 3.1 and 3.7 were 7.9 and 8.8 min, respectively. The type of acid did not significantly affect the heat resistance. The zD values ranged from 5.9 to 10°C, depending on the acid, pH, and the strain. The models generated from this research can be used to determine adequate thermal processes, accounting for the acid type, pH, and temperature, to destroy A. acidoterrestris spores in beverages, since this organism is able to survive the typical hot-fill and hold process (2 min at 88 to 96°C) currently used to process fruit juice.

scholarly journals Survival of Probiotic Lactobacilli in Acidic Environments Is Enhanced in the Presence of Metabolizable Sugars

2005 ◽  
Vol 71 (6) ◽  
pp. 3060-3067 ◽  
Author(s):  
B. M. Corcoran ◽  
C. Stanton ◽  
G. F. Fitzgerald ◽  
R. P. Ross
Keyword(s):  
Gastric Juice ◽  
Lactobacillus Rhamnosus ◽  
Probiotic Strain ◽  
Iodoacetic Acid ◽  
Glucose Effect ◽  
Ph Values ◽  
Gapdh Activity ◽  
Acidic Conditions ◽  
Probiotic Lactobacilli ◽  
Effect Of Glucose

ABSTRACT Lactobacillus rhamnosus GG is an industrially significant probiotic strain with proven health benefits. In this study, the effect of glucose on L. rhamnosus GG survival was analyzed in simulated gastric juice at pH 2.0. It was found that the presence of 19.4 mM glucose resulted in up to 6-log10-enhanced survival following 90 min of exposure. Further work with dilute HCl confirmed that glucose was the sole component responsible. Comparative analysis with other Lactobacillus strains revealed that enhanced survival was apparent in all strains, but at different pH values. The presence of glucose at concentrations from 1 to 19.4 mM enhanced L. rhamnosus GG survival from 6.4 to 8 log10 CFU ml−1 in simulated gastric juice. The mechanisms behind the protective effect of glucose were investigated. Addition of N′,N′-dicyclohexylcarbodiimide to simulated gastric juice caused survival to collapse, which was indicative of a prominent role in inhibition of F0F1-ATPase. Further work with neomycin-resistant mutants that exhibited 38% to 48% of the F0F1-ATPase activity of the parent confirmed this, as the survival in the presence of glucose of these mutants decreased 3 × 106-fold compared with the survival of the wild type (which had a viability of 8.02 log10 CFU ml−1). L. rhamnosus GG survival in acidic conditions occurred only in the presence of sugars that it could metabolize efficiently. To confirm the involvement of glycolysis in the glucose effect, iodoacetic acid was used to inhibit glyceraldehyde-3-phosphate dehydrogenase (GAPDH) activity. The reduction in GAPDH activity caused survival to decrease by 8.30 log10 CFU ml−1 in the presence of glucose. The data indicate that glucose provides ATP to F0F1-ATPase via glycolysis, enabling proton exclusion and thereby enhancing survival during gastric transit.

The distribution of scaled chrysophytes along a pH gradient

1989 ◽  
Vol 67 (7) ◽  
pp. 2120-2130 ◽  
Author(s):  
Peter A. Siver
Keyword(s):  
Acid Deposition ◽  
Significant Decline ◽  
Water Bodies ◽  
Ph Gradient ◽  
Weighted Mean ◽  
Scaled Chrysophytes ◽  
Frequency Distributions ◽  
Ph Values ◽  
Adirondack Lakes ◽  
Acidic Conditions

Frequency distributions versus pH and weighted mean pH values are reported for 25 and 40 species of scaled chrysophytes, from water bodies in Connecticut and the Adirondacks, respectively, and are compared with those assembled from a survey of the literature. For most species, similar distributions with respect to a pH gradient and weighted mean pH values were found. However, in Connecticut and Adirondack lakes, Mallomonas punctifera and Synura spinosa were more restricted to slightly acidic conditions and M. hamata was more abundant in conditions below a pH of 5.5. Groups of taxa with similar distributions with respect to pH were clearly defined. One group, consisting of Mallomonas acaroides var. muskokana, M. paludosa, M. pugio, M. canina, M. hindonii, S. sphagnicola, and S. echinulata, was dominant in waters with a pH < 5.5. Another group, including M. acaroides var. acaroides, M. corymbosa, M. tonsurata, M. psuedocoronata, and M. alpina, was primarily restricted to pH values above 6.5. A third group, including M. punctifera, M. akrokomas, M. crassisquama, M. galeiformis, M. caudata, Spiniferomonas bourrellyi, Sp. serrata, S. spinosa, and Chrysosphaerella longispina, had a significant decline in occurrence as the pH lowered to the 5–5.5 interval. The importance of scaled chrysophytes as a group in the biomonitoring of acid deposition is discussed.

scholarly journals Neonicotinoids stimulate H2-limited methane emission in Periplaneta americana through the regulation of gut bacterium community

2020 ◽  
Author(s):  
Haibo Bao ◽  
Haoli Gao ◽  
Jianhua Zhang ◽  
Haiyan Lu ◽  
Na Yu ◽  
...  
Keyword(s):  
Methane Emission ◽  
Methane Production ◽  
Periplaneta Americana ◽  
Insect Pests ◽  
Community Change ◽  
Insect Species ◽  
Atmospheric Methane ◽  
Ph Values ◽  
Acidic Conditions ◽  
Control Insect

AbstractMethane emitted by insects is considered to be an important source of atmospheric methane. Here we report the stimulation of methane emission in Periplaneta americana, an insect species with abundant methanogens, by neonicotinoids, insecticides widely used to control insect pests. The application of cycloxaprid (CYC) and imidacloprid (IMI) caused foregut expansion in P. americana, and increased the methane production and emission. Antibiotics could mostly eliminate the stimulatory effects. In P. americana gut, hydrogen levels increased and pH values decreased, which could be significantly explained by the gut bacterium community change. The proportion of several bacterium genera increased in guts following CYC treatment, and four genera from five with increased proportions could generate hydrogen at anaerobic conditions. Hydrogen is a central intermediate in methanogenesis. Gut methanogens could use the increased hydrogen to produce more methane, especially at acidic conditions. Following neonicotinoid applications, all increased methanogens in both foregut and hindgut used hydrogen as electron donor to produce methane. Besides, the up-regulation of mcrA, encoding the enzyme that catalyzes the final step of methanogenesis, suggested an enhanced methane production ability in present methanogens. In the termite Coptotermes chaohuensis, another methanogen-abundant insect species, hydrogen levels in gut and methane emission significantly increased after neonicotinoid treatment, which was similar to the results in P. americana. In summary, neonicotinoids changed bacterium community in P. americana gut to generate more hydrogen, which then stimulate gut methanogens to produce and emit more methane. The finding raised a new concern over neonicotinoid applications, and might be a potential environmental risk associated with global warming.

scholarly journals Schlesneria paludicola gen. nov., sp. nov., the first acidophilic member of the order Planctomycetales, from Sphagnum-dominated boreal wetlands

2007 ◽  
Vol 57 (11) ◽  
pp. 2680-2687 ◽  
Author(s):  
Irina S. Kulichevskaya ◽  
Anastasia O. Ivanova ◽  
Svetlana E. Belova ◽  
Olga I. Baulina ◽  
Paul L. E. Bodelier ◽  
...  
Keyword(s):  
Dna Hybridization ◽  
Type Strain ◽  
Sequence Similarity ◽  
Rrna Gene ◽  
16S Rrna Gene Sequences ◽  
Ph Values ◽  
Novel Genus And Species ◽  
Acidic Conditions ◽  
Northern Russia ◽  
Moderately Acidophilic

Three strains of budding, ellipsoid-shaped and rosette-forming bacteria were isolated from acidic Sphagnum-dominated boreal wetlands of northern Russia and were designated strains MPL7T, MOB77 and SB2. The presence of crateriform pits and numerous fibrillar appendages on the cell surface and an unusual spur-like projection on one pole of the cell indicated a planctomycete morphotype. These isolates are moderately acidophilic, mesophilic organisms capable of growth at pH values between 4.2 and 7.5 (with an optimum at pH 5.0–6.2) and at temperatures between 4 and 32 °C (optimum 15–26 °C). The major fatty acids are C16 : 0 and C16 : 1 ω7c; the major quinone is MK-6. The G+C content of the DNA is 54.4–56.5 mol%. Strains MPL7T, MOB77 and SB2 possess nearly identical 16S rRNA gene sequences and belong to the planctomycete lineage defined by the genus Planctomyces, being most closely related to Planctomyces limnophilus DSM 3776T (86.9–87.1 % sequence similarity). However, strain MPL7T showed only 28 % DNA–DNA hybridization with P. limnophilus DSM 3776T. Compared with currently described members of the genus Planctomyces, the isolates from northern wetlands do not form long and distinctive stalks, have greater tolerance of acidic conditions and low temperatures, are more sensitive to NaCl, lack pigmentation and degrade a wider range of biopolymers. The data therefore suggest that strains MPL7T, MOB77 and SB2 represent a novel genus and species, for which the name Schlesneria paludicola gen. nov., sp. nov., is proposed. Strain MPL7T (=ATCC BAA-1393T =VKM B-2452T) is the type strain of Schlesneria paludicola.

Role of Molecular Structure of Complexing/Chelating Agents in Copper CMP Slurries

2005 ◽  
Vol 867 ◽  
Author(s):  
Udaya B. Patri ◽  
S. Pandija ◽  
S.V. Babu
Keyword(s):  
Molecular Structure ◽  
Functional Groups ◽  
Chelating Agents ◽  
Carbon Chain ◽  
Carbon Chain Length ◽  
Removal Rates ◽  
Ph Values ◽  
Amino Butyric Acid ◽  
Acidic Conditions

AbstractThe role of the molecular structure - different functional groups, the length of the carbon chain and the relative positions of different functional groups – of several complexing/chelating agents (acetic acid, glycine, ethylene diamine, succinic acid, alanine and amino butyric acid (ABA)) in controlling copper (Cu) removal rates was investigated. The results are consistent with the known activity of –COOH groups at acidic conditions and that of –NH2 groups in an alkaline environment. In comparison with glycine, it was also observed that an increase in the carbon chain length increased the removal rates at acidic pH values and decreased the removal rates at alkaline pH values. Also, Cu removal rates decreased with an increase in the distance between the –NH2 and –COOH groups in an amino acid at all pH values except at 4.

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