Presence Of Aq Research Articles

Data-driven models for the prediction of H2 generation through chemical reaction and performance evaluation of on-board hydrogen fuelled sintering tube furnace

Hydrogen is emerging as a sustainable fuel for the future. In this present work, data-driven modelling tools viz. Radial Basis Function Neural Network (RBFNN) and Least Square Fit (LSF) method, are employed to determine the rate of production of H2 gas by the chemical reaction between aluminium and water in the presence of aq. NaOH. Reactions are carried out at NaOH concentrations of 1M–5M, water temperatures 303K–333K. Hydrogen gas obtained at 333K/4M is found to have a yield of ⁓88 % of the theoretical yield. The activation energy of the reaction is found to be 57.62 kJ mol−1. The fitted models are validated with experimental results for two unknown conditions. The correlation coefficient obtained for the RBFNN model is 0.999, which indicates the high reliability of the model. On-board production of H2 gas by the chemical reaction was used for heating a sintering tube furnace. The hot products of the combustion of hydrogen and air at various fuel-air ratios were used to heat the sintering tube furnace. The maximum thermal efficiency obtained for the furnace is 76.22 % at a fuel-air ratio of 1:60 corresponds to a fuel-air equivalent ratio (λ) of 0.57.

Blends of Organic Acids Are Weaponizing the Host iNOS and Nitric Oxide to Reduce Infection of Piscirickettsia salmonis in vitro.

For the last 30 years, Piscirickettsia salmonis has caused major economic losses to the aquaculture industry as the aetiological agent for the piscirickettsiosis disease. Replacing the current interventions, based on antibiotics, with natural alternatives (e.g., organic acids) represents a priority. With this study, we aimed to better understand their biological mechanism of action in an in vitro model of infection with salmon epithelial cells (CHSE-214). Our first observation revealed that at the sub-inhibitory concentration of 0.5%, the organic acid blend (Aq) protected epithelial cell integrity and significantly reduced P. salmonis invasion. The MIC was established at 1% Aq and the MBC at 2% against P. salmonis. The sub-inhibitory concentration significantly increased the expression of the antimicrobial peptides Cath2 and Hepcidin1, and stimulated the activity of the innate immune effector iNOS. The increase in iNOS activity also led to higher levels of nitric oxide (NO) being released in the extracellular space. The exposure of P. salmonis to the endogenous NO caused an increase in bacterial lipid peroxidation levels, a damaging effect which can ultimately reduce the pathogen's ability to attach or multiply intracellularly. We also demonstrate that the increased NO release by the host CHSE-214 cells is a consequence of direct exposure to Aq and is not dependent on P. salmonis infection. Additionally, the presence of Aq during P. salmonis infection of CHSE-214 cells significantly mitigated the expression of the pro-inflammatory cytokines IL-1β, IL-8, IL-12, and IFNγ. Taken together, these results indicate that, unlike antibiotics, natural antimicrobials can weaponize the iNOS pathway and secreted nitric oxide to reduce infection and inflammation in a Piscirickettsia salmonis in vitro model of infection.

Bioactivity of chitosan nanoparticles synthesized by a novel route towards Escherichia coli and Bacillus subtilis

Chitosan nanoparticles (CSNP) with an average size of 25.67 nm were synthesized via a novel wet chemical route and characterized using scanning electron microscopy (SEM) and Fourier Transform Infrared (FTIR) spectroscopy. Comparative antibacterial assays of Chitosan NP suspensions prepared in water (at neutral pH) and in dilute acetic acid and chitosan gel prepared in dilute acetic acid/hydrochloric acid (all at concentrations up to 1%) were performed against Escherichia coli ( E. coli) and Bacillus subtilis ( B. subtilis) bacteria using spread plate method. A parallel viability test was conducted to confirm the presence of surviving cells in the bulk test volume. Minimum bactericidal concentration (MBC) of chitosan gel was 0.5 mg/ml for the bulk chitosan dissolved in 0.05% v/v aq. acetic acid and 0.1 mg/ml for chitosan dissolved in 0.01% v/v aqueous (aq.) hydrochloric acid. In comparison, Chitosan NP were found to be growth promoter at neutral pH and exhibited cell protective efficacy in presence of aq. acetic acid. The biocidal activity of chitosan gel in acidic media was higher when prepared in strong inorganic acid, that is, aq. HCl in comparison with the gel prepared in a relatively weak organic acid that is, aq. CH3COOH at the same concentration. Antibacterial action also showed pH dependence with higher activity at lower pH. However, respective aq. acids also gave comparable bactericidal action; indicating that chitosan may not have any inherent antibacterial property and basically it acts as a growth promoter.

Amine-functionalized titanium dioxide supported dioxidomolybdenum(VI) complexes as functional model for phenoxazinone synthase enzyme

Two dioxidomolybdenum(VI) complexes, [MoVIO2{H2dfba(bhz)2}(H2O)] (1) and [MoVIO2{H2dfba(fah)2}(H2O)] (2) of ligands H4dfba(bhz)2 (I) and H4dfba(fah)2 (II) (H2dfba = 3,5-diformyl-4-hydroxybenzoic acid, Hbhz = benzoylhydrazide and Hfah = 2–furanoylhydrazide), respectively and their corresponding heterogenized complexes [MoVIO2{Hdfba(bhz)2}(H2O)]@APTMS-TiO2 (3) and [MoVIO2{Hdfba(fah)2}(H2O)]@APTMS-TiO2 (4) supported on amine-functionalized titanium dioxide (APTMS-TiO2, III) have been isolated and characterized by various spectroscopic techniques (FT-IR, UV–vis, diffusion reflectance, 1H and 13C NMR), elemental analysis (C, H and N), thermal, TEM and powder-XRD studies. Single-crystal X-ray study of [MoVIO2{H2dfba(bhz)2}(EtOH)]·EtOH (1a·EtOH) confirms the octahedral structure. Both homogeneous and heterogeneous complexes have been explored as phenoxazinone synthase mimicking catalysts in the oxidation of 2-aminophenol to 2-aminophenoxazine-3-one in acetonitrile in the presence of aq. H2O2. The kcat value for the phenoxazinone synthase-like activity was found to be 1.46 × 10–3 and 3.26 × 1 0–3 min–1 for catalysts 1 and 2, respectively. Catalysts 1, 2, 3 and 4 also gave 91, 86, 94 and 88 % yield of 2–aminophenoxazine-3-one (APX), respectively, under the optimized reaction conditions.

Production of xylose, levulinic acid, and lignin from spent aromatic biomass with a recyclable Brønsted acid synthesized from d-limonene as renewable feedstock from citrus waste

This work aimed to develop a green protocol for chemical processing of spent aromatic biomass to obtain xylose, levulinic acid, and lignin in good yields via treatment with p-cymene-2-sulphonic acid (p-CSA), a Brønsted acid synthesised from d-limonene as a renewable feedstock from citrus waste. Chemical processing of palmarosa biomass with p-CSA under heating in an autoclave resulted in hydrolysate containing xylose (~16% yield). Further processing of pre-treated biomass with p-CSA in presence of aq. HCl under refluxing caused a selective degradation of cellulose to levulinic acid (~22% yield with respect to biomass). The residual biomass was used to afford lignin in good yields.

Asymmetric Michael Addition Organocatalyzed by α,β-Dipeptides under Solvent-Free Reaction Conditions.

The application of six novel α,β-dipeptides as chiral organocatalysts in the asymmetric Michael addition reaction between enolizable aldehydes and N-arylmaleimides or nitroolefins is described. With N-arylmaleimides as substrates, the best results were achieved with dipeptide 2 as a catalyst in the presence of aq. NaOH. Whereas dipeptides 4 and 6 in conjunction with 4-dimethylaminopyridine (DMAP) and thiourea as a hydrogen bond donor proved to be highly efficient organocatalytic systems in the enantioselective reaction between isobutyraldehyde and various nitroolefins.

DESIGN, FACILE SYNTHESIS, AND BIOLOGICAL EVALUATION OF NOVEL 1,3-THIAZINE DERIVATIVES AS POTENTIAL ANTICONVULSANT AGENTS

ABSTRACTObjective: Chalcones and their heterocyclic analogs represent an important class of small molecules having anticonvulsant activities. Therefore, inthis study, the synthesis and anticonvulsant activity of some new chalcones and 1,3-thiazines were described.Methods: The reaction of 1-acetylnaphthalene with substituted aromatic aldehydes in the presence of aq. NaOH afforded corresponding chalconeswhich upon further cyclization with thiourea resulted in 1,3-thiazine derivatives. The newly synthesized compounds were tested for anticonvulsantactivity by pentylenetetrazole-induced seizures method using diazepam as standard.Results: Most of the compounds showed good anticonvulsant activity but is less than diazepam. 1,3-thiazines were more potent than chalconesand among them, compound P4 containing 4-fluorophenyl substituents on the thiazine moiety was more potent as it has prolonged the onset ofconvulsions by 155.2 seconds.Conclusion: We described the synthesis and anticonvulsant activity of novel chalcones and 1,3-thiazine derivatives. 1,3-thiazines are more activeanticonvulsant agents than chalcones and in particular compounds with electron withdrawing substituents.Keywords: Chalcone, 1,3-thiazine, Pentylenetetrazole.

Conductive polymer-mediated Cr(VI) reduction in a dual-chamber microbial fuel cell under neutral conditions

Microbial fuel cell (MFC) technology for Cr(VI) removal offers the advantage of simultaneous electricity generation and Cr-laden wastewater treatment, but Cr(VI) removal at neutral pH proceeds with slow kinetics. We herein report the use of conductive polymer as a mediator shuttling electron transfer from the cathode to Cr(VI), facilitating Cr(VI) reduction in MFCs under neutral conditions. It has been found that PPy films synthesized by electropolymerization on the graphite felt cathode considerably improved Cr(VI) removal from the aqueous solution. The surface morphology of PPy, which is correlated to performance of the PPy-modified cathode, was highly dependent on the type of dopants that were incorporated during electropolymerization. The PPy/AQS(9,10-anthraquinone-2-sulfonic acid sodium salt)-modified cathode with nanowire structure enabled higher Cr(VI) removal rate and exhibited larger power output than the PPy/ClO4−-modified cathode with compact globular structure. These results are attributed to the increased surface area of electrode and the presence of AQS that is electrochemically active for reaction with Cr(VI). Cr(III) precipitates were the primary end-products of Cr(VI) reduction under neutral conditions, with no soluble Cr(III) detected.

Anthraquinone 2-sulfonic acid-mediated reduction of Cr(VI) by Bacillus sp. BT1

Bacillus sp. BT1 exhibited enhanced efficiency as well as rate of Cr(VI) reduction in the presence of anthraquinone-2-sulfonic acid (AQS), a quinone compound analogous to humic acid. The culture exhibited 5.67-fold higher Cr(VI) reduction rate in Luria broth containing 100 mg Cr(VI)/L augmented with 1mM AQS. Furthermore, in the absence of AQS, Bacillus sp. BT1 reduced only 100 mg Cr(VI)/L, whereas in the presence of AQS, it reduced a total of 400 mg Cr(VI)/L, added in form of repeated spikes of 100 mg Cr(VI)/L in each cycle. The activation energy of mediated Cr(VI) reduction was found to be 2.1-fold lower in comparison to nonmediated Cr(VI) reduction. The Cr(VI) and AQS, both induced intracellular quinone and chromate reductases in Bacillus sp. BT1. The results demonstrate the potential of AQS-mediated Cr(VI) reduction by Bacillus sp. BT1 in bioremediation of Cr(VI) containing wastewaters.

ChemInform Abstract: A New and Efficient Approach to Isoxazolines. First Synthesis of 3‐Aryl‐5‐dichloromethyl‐2‐isoxazolines.

AbstractThe method is based on the conversion of β,γ‐enones (I) into oximes which are readily cyclize to the desired isoxazolines in the presence of aq.

OCCURRENCE OF AMPELOMYCES QUISQUALIS ON THE CUCURBIT POWDERY MILDEW SPECIES IN THE CZECH REPUBLIC

From 2002 to 2006, in the Czech Republic (CR), 585 leaf samples with powdery mildew symptoms collected from cucurbits (mainly from Cucurbita pepo, Cucurbita maxima, Cucumis sativus) were microscopically examinated for presence of hyperparasitic fungus Ampelomyces quisqualis Ces. (Aq). Identification of cucurbit powdery mildew species (Golovinomyces cichoracearum /Gc/, Podosphaera xanthii /Px/) was carried out by microscopic examination of the morphological characters of dry conidia in a 3% KOH solution. In total of 443 samples was determined as Gc, 106 samples as mixed infection (Gc, Px) and 36 samples as Px. Aq was detected on 12% of collected samples from the CR. However, frequency of its occurrence varied among the years. In 2002 and 2006, Aq was more frequent (18-20%) as compared with the years 2003-2005 (only 6-8%). Pycnidia of Aq were recorded mainly on Gc hyphae and basal cells of conidiophores (12%) or on mixed infection (Gc, Px) (14%). Occurrence of Aq on Px was only sporadic (only 3 CPM samples/2 locations - 2/1 in 2005 and 1/1 in 2006). Its distribution was recorded in 52 locations of the CR, it was not restricted to limited areas, nevertheless the most of Aq locations originated from the South Moravia. In some locations its presence was recorded repeatedly, in some others it was detected only once. The majority of samples with presence of Aq were collected in August and September.

Synthesis and conformational features of sym N,N′,N″-triarylguanidines

A one pot reaction involving sym N,N′-diarylthiourea and the respective arylamine in the presence of aq. KOH in nitrobenzene at ≥105°C afforded sym N,N′,N″-triarylguanidine in fair to good yield and the products have been characterized. Sym N,N′,N″-tri(4-tolyl)guanidine possesses (7) anti-anti conformation, sym N,N′,N″-tri(2-tolyl)guanidine (8) and sym N,N’,N″-tris(2,4-xylyl)guanidine (11) each possess anti-anti αβα conformation whereas sym N,N′,N″-tris(2-anisyl)guanidine possesses (9) syn-anti αββ conformation as determined by single crystal X-ray diffraction data. The observed conformations appear to result from a subtle balance between steric factor associated with the aryl substituent and multiple electronic factors namely n-π conjugation/negative hyperconjugation and non-covalent interactions in the crystal lattice.

Effects of Prior Administration of Amodiaquine on the Disposition of Halofantrine in Healthy Volunteers

The prevalence of multidrug-resistant malaria parasites brings about the switch from an antimalarial drug with poor therapeutic outcome to an effective alternative, resulting in overlap in the plasma drug levels. In this study, the influence of prior administration of amodiaquine on the pharmacokinetics and electrocardiographic effect of halofantrine (HF) was investigated in healthy volunteers. Ten healthy male subjects were each given single oral doses of 500 mg HF alone or with 600 mg of amodiaquine hydrochloride (AQ) administered 24 hours before the HF dose in a crossover fashion. Blood samples, collected at predetermined time intervals, were analyzed for HF and its major metabolite, desbutylhalofantrine (HFM) using a validated high-performance liquid chromatography method. Electrocardiogram for each volunteer was taken at predetermined time points. Results showed that prior administration of amodiaquine resulted in no significant changes (P > 0.05) in any of the pharmacokinetic parameters of HF. For example, the parameter values for HF alone and with AQ were: Cmax 144 +/- 53 versus 164 +/- 58 microg/L; T1/2beta 142 +/- 23 versus 139 +/- 28 hours; Cl/F 37.3 +/- 13.9 versus 32.3 +/- 11.4 L/h; and metabolic ratio 1.2 +/- 0.5 vs 1.1 +/- 0.6 Similarly, the disposition of HFM was not significantly altered (P > 0.05) after an earlier exposure to amodiaquine. In addition, the presence of AQ was linked with a further lengthening of the QT interval compared with the effect of HF alone. This study suggests that prior administration of AQ does not result in a significant alteration of the pharmacokinetics of HF but may be associated with an increased risk of QT prolongation. It may be necessary to exercise caution in the use of HF for malaria treatment in persons who have recently received AQ.

SbW 9O 33]-based polyoxometalate combined with a phase transfer catalyst: A highly effective catalyst system for selective oxidation of alcohols with H 2O 2, and spectroscopic investigation

Na 9[SbW 9O 33] in conjunction with a phase transfer catalyst, methyltricapryl ammonium chloride, is highly efficient for selective oxidation of variety of alcohols with aq. H 2O 2 to yield corresponding carbonyls. Most importantly the reactions are carried out in the absence of any organic solvents especially halogenated solvents. In case of allylic alcohols, the catalyst is highly selective for the alcohol oxidation reaction and least selective for epoxidation reaction in the presence of aq. H 2O 2. IR studies support the formation of W-peroxo intermediate species and also support the stability of the catalyst in the presence of phase transfer compound under the present experimental condition. The catalyst can be reused after careful decomposition of peroxide of the final reaction mixture.

Reduction of nitrobenzene and formation of corrosion coatings in zerovalent iron systems

Batch tests were conducted to investigate reduction of nitrobenzene in a zerovalent iron system (Fe0) under various conditions. The results indicated that a limited amount of nitrobenzene (ArNO2) could be reduced to aniline by Fe0, but formation of a lepidocrocite (γ-FeOOH) coating could significantly slow down the reaction. However, augmenting Fe0 with substoichiometric FeCl2 could dramatically accelerate the reaction. Surface-adsorbed Fe(II), not pH nor Cl−, was found to be responsible for rejuvenating the system. O2 and nitrobenzene could be concomitantly reduced by Fe0 in the presence of Fe2+. In the Fe0 system, both nitrobenzene and O2 favored formation of lepidocrocite; in the presence of aq. Fe(II), a stratified corrosion coating could develop, with magnetite (Fe3O4) as the inner layer and lepidocrocite as the outer layer. Fe2+ was not the main reductant for the reactions, but might accelerate the autoreduction of lepidocrocite to magnetite by the underlying Fe0. Our understanding on the role of Fe(II) in conjunction with a stratified, evolving corrosion coating may be useful for establishing an iron aquatic corrosion model.

Seasonal variability of 1-chloropyrene on atmospheric particles and photostability in toluene

The occurrence of a mutagenic compound, 1-chloropyrene (Cl-Py), in extracts of ambient particulate matter at an urban site in Japan has been investigated. Samples were collected with a high-volume air sampler for 24 h periods over the course of 1 week in winter (February), spring (May), summer (August), and autumn (November) 2002. The Cl-Py levels showed seasonal variation, ranging from 2.4 pg/m 3 (summer) to 18.9 pg/m 3 (winter). This variation would indicate that the lower temperatures in winter results in an increased distribution of Cl-Py from vapor phase to the particle phase. In addition, there is also the possibility that ambient Cl-Py is emitted from seasonal sources or is susceptible to photodegradation by sunlight, or both. The photodegradation of Cl-Py in a laboratory experiment was conducted to simulate the compound’s fate on airborne particle surfaces. The degradation of Cl-Py proceeded by a first-order reaction with a rate constant of 0.72 h −1. In the presence of a radical sensitizer, 9,10-anthraquinone (AQ), the photodegradation rate of Cl-Py was elevated in comparison with the rate in the absence of AQ. In addition, the dechlorination of Cl-Py (i.e., the formation of Py) occurred in the presence of AQ.

Rapid synthesis of tetrahydro-4 H-pyrazolo[1,5- a]diazepine-2-carboxylate

Hydrazines condense with dimethyl 2-pyrrolidino-4-oxo-2-pentenedioate in the presence of aq. HCl to form N-substituted pyrazole-3,5-dicarboxylates 2 . Complex bicyclic derivatives, such as pyrazolo-oxazine 3a , pyrazolo-oxazepine 3b , pyrazolo-pyrazine 4a , and pyrazolo-diazepine 4b , were generated using 2-hydrazinoethanol, 3-hydrazinopropanol, 2-hydrazinoethylamine, and 3-hydrazinopropylamine.

FORMATION OF ALIPHATIC CARBOXYLIC ACIDS DURING ALKALINE PULPING OF MULI BAMBOO

ABSTRACT A study on the formation of aliphatic carboxylic acids, i.e., formic and acetic acids and various hydroxy monocarboxylic and dicarboxylic acids, during soda-AQ, kraft, and kraft-AQ pulping of muli bamboo (Melocanna baccifera) was carried out. Detailed gas chromatographic analyses revealed that the most abundant hydroxy carboxylic acids were 2-hydroxybutanoic, lactic, glucoisosaccharinic, glycolic, xyloisosaccharinic, 3,4-dideoxypentonic, and 3-deoxypentonic acids. The presence of AQ depressed the formation of 2-hydroxybutanoic, xyloisosaccharinic, and glucoisosaccharinic acids, and accelerated the formation of glycolic and 3-deoxypentonic acids as well as 3-deoxytetronic acid but had only a small effect on that of lactic and 3,4-dideoxypentonic acids. The total amount of aliphatic carboxylic acids corresponded to 12–15% of o.d. bamboo.

Synthesis and characterization of triallylphenoxytriazine and the properties of its copolymer with bismaleimide

AbstractA new modifier for bismaleimide (BMI), 2,4,6‐tris(2‐allylphenoxy)‐1,3,5‐triazine (TAPT), with higher yield was prepared by a phase‐transfer catalyzing (PTC) procedure through the reaction of cyanuric chloride with 2‐allylphenol in the presence of aq. NaOH using tetrabutyl ammonium bromide in chloroform. The thermo‐homopolymerization behavior of TAPT was investigated by differential scanning calorimetry (DSC), and the results showed that TAPT does not polymerize on heating. The copolymerization reaction of TAPT and 4,4'–(bismaleimidophenyl) methane (BMDPM) was also studied. and the results showed that TAPT can effectively improve mechanical properties of BMDPM. The better results were obtained when the TAPT composition was in the range 30–40 wt %. The glass fabric reinforced TAPT/BMDPM matrix composite with excellent mechanical and electric properties could be prepared by processing the resin (30 wt % TAPT) in dimethylformamide (DMF)/toluene (1:1, v/v) solution. © 2001 John Wiley & Sons, Inc. J Appl Polym Sci 81: 1248–1257, 2001

Novel base-catalysed formation of benzo[b]furano[60]- and -[70]fullerenes

Reaction of C60Cl6 with phenol in the presence of aq. KOH and under nitrogen, produces benzo[b]furano[2′,3′∶1,2][60]fullerene arising from substitution/elimination occurring across the 1,2-positions of the hexachloro precursor. Use of either 4-fluorophenol or 4-methoxyphenol produces the corresponding fluoro- and methoxy-substituted derivatives. Reaction with an excess of phenolic reagent results in nucleophilic replacement of some of the other chloro addends in the precursor by phenoxy groups, which may also participate in oxidative ring closure. C70Cl10 reacts with phenol in the presence of aq. KOH to give benzo[b]furano[2′,3′∶7,8][70]fullerene. The corresponding reaction of aniline with C60Cl6 produces derivatives of benzo[b]pyrrolo[2′,3′∶1,2][60]fullerene, but thiophenol does not react. Removal of eclipsing steric hindrance accounts for the ready ring-closure formation of the cycloadducts across bonds containing adjacent chlorines.