Effect Of Alkaline Hydrolysis Research Articles

Yessotoxins in Mollusks of the Galician Coast from 2014 to 2022: Variability, Biotransformation, and Resistance to Alkaline Hydrolysis.

The presence of yessotoxins (YTXs) was analyzed in 10,757 samples of Galician bivalves from 2014 to 2022. Only YTX and 45-OH YTX were found. YTX was detected in 31% of the samples, while 45-OH YTX was found in 11.6% of them. Among the samples containing YTX, 45-OH YTX was detected in 37.3% of cases. The maximum recorded levels were 1.4 and 0.16 mg of YTX-equivalentsg-1, for YTX and 45-OH YTX, respectively, which are well below the regulatory limit of the European Union. The YTX and 45-OH YTX toxicities in the raw extracts and extracts subjected to alkaline hydrolysis were strongly and linearly related. Due to the lack of homo-YTX in Galician samples, the effect of alkaline hydrolysis on homo-YTX and 45OH-Homo-YTX was only checked in 23 additional samples, observing no negative effect but a high correlation between raw and hydrolyzed extracts. Hydrolyzed samples can be used instead of raw ones to carry out YTXs determinations in monitoring systems, which may increase the efficiency of those systems where okadaic acid episodes are very frequent and therefore a higher number of hydrolyzed samples are routinely analyzed. The presence of YTX in the studied bivalves varied with the species, with mussels and cockles having the highest percentages of YTX-detected samples. The presence of 45-OH YTX was clearly related to YTX and was detected only in mussels and cockles. Wild populations of mussels contained proportionally more 45-OH YTX than those that were raft-cultured. Spatially, toxin toxicities varied across the sampling area, with higher levels in raft-cultured mussels except those of Ría de Arousa. Ría de Ares (ARE) was the most affected geographical area, although in other northern locations, lower toxin levels were detected. Seasonally, YTX and 45-OH YTX toxicities showed similar patterns, with higher levels in late summer and autumn but lower toxicities of the 45-OH toxin in August. The relationship between the two toxins also varied seasonally, in general with a minimum proportion of 45-OH YTX in July-August but with different maximum levels for raft-cultured and wild mussel populations. Interannually, the average toxicities of YTX decreased from 2014 to 2017 and newly increased from 2018 to 2021, but decreased slightly in 2022. The relationship between 45-OH YTX and YTX also varied over the years, but neither a clear trend nor a similar trend for wild and raft mussels was observed.

Effect of alkaline hydrolysis on low-stress mechanical properties of polyester/cotton blended weft knitted fabrics

Effect of alkaline hydrolysis on low-stress mechanical properties of polyester/cotton blended weft knitted fabrics

Radiolysis effect on Eu(III)-superplasticiser interactions in artificial cement and squeezed cement pore waters.

In the framework of the French deep geological repository for radioactive waste, cement-based materials are envisaged to immobilize radionuclides and/or provide protection from radiation to the environment. Superplasticisers (SPs) are added to these materials to increase their workability. SPs will undergo degradation by coupled radiolytic and hydrolytic effects in the pore solution leading to the formation of potentially complexing degradation products. The objective was to study the potential effect of radiolyzed superplasticizers contained in cement-based materials on radionuclide uptake. The Eu speciation and solubility with organic ligands resulting from the degradation of SPs were studied for the two solutions and the results were compared. Two different SPs were selected, a polycarboxylate ether and a polynapthalene sulfonate. Two different protocols were followed: direct irradiation of the solution containing the superplasticizer, and irradiation of the compacted cement sample followed by extraction of the pore water. Solubility enhancements observed in artificial cement waters are not representative of real cement pore water interactions, in agreement with other studies. Finally, the effects of alkaline hydrolysis and radiolysis of SPs on Eu solubility in pore water are limited.

Kinetics Study of Co-Solvent effect in Alkaline Hydrolysis of Diethyl Pathalate Ester

The base catalyzed hydrolysis of diethyl pathalate has been carried out titrometically in water-ethanol binary solvent mixture covering range of 30 to 70% (v/v) of solvent composition at different Temperature (20 to 400C). The reaction followed second order rate constant which decreases with increase of solvent composition. The salvation and desolvation concept are used to explain the solvent influence on rate and mechanism is the reaction. The relation between changes in dielectric constant due to variation of reaction mixture and change in specific rate constant has been explained on the basis of electrostatic and non-electrostatic contribution of solvent mixture. Calculated value of Iso-composition activation energy is found to be increases with increase of solvent composition. The thermodynamic parameters (G*, H*&S*) has been determined with help of Wynne Jone and Eyring equation which show the great dependency on solvent composition.

Effects of alkaline hydrolysis and storage conditions on the biological activity of ostrich egg white

This study aimed to improve the biological activity of ostrich egg white (OEW) using alkaline hydrolysis (0.25 M NaOH at 40°C for 8 hr), and studied the effects of packing materials and temperature on biological and physical properties of OEW hydrolysate (hOEW). The results show that alkaline hydrolysis clearly enhanced several biological activities, including ABTS radical scavenging (61.35%), anti-microbial (51.66% against Bacillus subtilis and 38.58% against Escherichia coli) and anti-angiotensin converting enzyme activity (39.19%). The hydrolysate maintained biological activities after gastrointestinal digestion and showed non-toxicity toward human red blood cells. In storage study, the best storage conditions were packing hOEW powder in an Al-foil-laminated bag at 4°C, resulting in slightly decreased biological activity after 6 months storage and significantly lower moisture content than plastic zipper bag. Additionally, SEM revealed smooth surfaces of hOEW powder for the best condition, while air pores and bridges were found in the worst conditions. Practical applications The alkaline hydrolysis method (incubation in 0.25 M NaOH at 40°C for 8 hr) used in this study can be used to enhance the antioxidant, antimicrobial, and anti-ACE inhibition activity of egg white protein. This study also reports the optimal packaging and storage conditions for egg white hydrolysate powder, which are beneficial for maintaining the antioxidant, antimicrobial, and anti-angiotensin converting enzyme activity as well as the texture of the egg white hydrolysate powder.

Effect of alkaline hydrolysis on cyclization reaction of PAN nanofibers

Polyacrylonitrile (PAN) nanofibers were prepared via electrospinning, and the PAN nanofibers were then subjected to alkaline hydrolysis with different treatment times. The alkaline hydrolysis behavior of the PAN nanofibers was investigated with ATR-IR and XPS analyses. The results indicate that the nitrile (CN) groups of PAN were converted into amide (CONH2) and carboxylic (COOH) groups. The effect of the alkaline hydrolysis on the cyclization of the PAN nanofibers was then investigated using ATR-IR, DSC, and TGA analyses. The functional groups introduced through the hydrolysis of PAN initiated the cyclization reaction at a faster rate, and thus the exothermic cyclization temperature shifted to a lower temperature. In addition, the extent of the stabilization reaction (EOS) of the hydrolyzed PAN nanofibers was higher than that of the PAN nanofibers. It was conclusively demonstrated that the alkaline hydrolysis was effective in improving the cyclization efficiency of the PAN nanofibers.

Erratum to: Effects of alkaline hydrolysis and autoclaving on inorganic components present in healthcare waste

Erratum to: Effects of alkaline hydrolysis and autoclaving on inorganic components present in healthcare waste

Effects of alkaline hydrolysis and autoclaving on inorganic components present in healthcare waste

In this work, samples of components usually present in healthcare waste, such as cotton, diapers, transfusion tubes, surgical gloves, examination gloves, adhesives, surgical masks, urine bag collectors, serum bottles and syringes, were subjected to alkaline hydrolysis or autoclaving and the effects of these treatments were assessed. Both treatments were carried out at 135 °C, and the weight loss and the carbon loss of the components as well as the total organic carbon and the chemical oxygen demand in the effluents were determined. The biodegradability of effluents was assessed by measuring the biochemical oxygen demand after 5 days. Alkaline hydrolysis caused appreciable degradation in most of the components, with the adhesives and the diapers having the highest weight losses and carbon losses. Components made with low-density polyethylene, high-density polyethylene and polypropylene showed good chemical resistance with 2 M NaOH solution. The effluents obtained after alkaline treatment of healthcare waste are hazardous due to their very high alkalinity. The effluent obtained after treatment of a mixture of all components using a 2 M NaOH solution was biodegradable with the following parameters: 6.5 g C/l of total organic carbon, 29.8 g O2/l of chemical oxygen demand and 14.9 g O2/l of biochemical oxygen demand after 5 days. Although the autoclaving treatment degraded the components much less than alkaline hydrolysis, the effluents obtained from some components showed an appreciable organic load.

Prediction of ortho substituent effect in alkaline hydrolysis of phenyl esters of substituted benzoic acids in aqueous acetonitrile

Abstract The second-order rate constants k for the alkaline hydrolysis of phenyl esters of meta-, para- and ortho-substituted benzoic acids, X-C6H4CO2C6H5, in aqueous 50.9% acetonitrile have been measured spectrophotometrically at 25°C. The log k values for meta and para derivatives correlated well with the Hammett σm,p substituent constants. The log k values for ortho-substituted phenyl benzoates showed good correlations with the Charton equation, containing the inductive, σI, resonance, σ○ R, and steric, E s B, and Charton υ substituent constants. For ortho derivatives the predicted (log k X)calc values were calculated with equation (log k ortho)calc = (log k H AN)exp + 0.059 + 2.19σI + 0.304σ○ R + 2.79E s B − 0.0164ΔEσI — 0.0854ΔEσ○ R, where DE is the solvent electrophilicity, ΔE = E AN — E H20 = −5.84 for aqueous 50.9% acetonitrile. The predicted (log k X)calc values for phenyl ortho-, meta- and para-substituted benzoates in aqueous 50.9% acetonitrile at 25°C precisely coincided with the experimental log k values determined in the present work. The substituent effects from the benzoyl moiety and aryl moiety were compared by correlating the log k values for the alkaline hydrolysis of phenyl esters of substituted benzoic acids, X-C6H4CO2C6H5, in various media with the corresponding log k values for substituted phenyl benzoates, C6H5CO2C6H4-X.

Prediction of ortho substituent effect in alkaline hydrolysis of substituted phenyl benzoates in aqueous acetonitrile

The second-order rate constants k (dm3mol−1s−1) for alkaline hydrolysis of meta-, para- and ortho-substituted phenyl esters of benzoic acid, C6H5CO2C6H4-X, in aqueous 50.9% (v/v) acetonitrile have been measured spectrophotometrically at 25 °C. In substituted phenyl benzoates, C6H5CO2C6H4-X, the substituent effects log kX − log kH in aqueous 50.9% acetonitrile at 25 °C for para, meta and ortho derivatives showed good correlations with the Taft and Charton equations, respectively. Using the log k values for various media at 25 °C, the variation of the ortho substituent effect with solvent was found to be precisely described with the following equation: Δlog kortho = log kortho − log kH = 1.57σI + 0.93σ°R + 1.08EsB − 0.030ΔEσI − 0.069ΔEσ°R, where ΔE is the solvent electrophilicity, ΔE = ES − EH20, characterizing the hydrogen-bond donating power of the solvent. We found that the experimental log k values for ortho-, para- and meta-substituted phenyl benzoates in aqueous 50.9% acetonitrile at 25 °C, determined in the present work, precisely coincided with the log k values predicted with the equation (log kX)calc = (log kHAN)exp + (Δlog kX)calc where the substituent effect (Δlog kX)calc was calculated from equation describing the variation of the substituent effect with the solvent electrophilicity parameter, using for aqueous 50.9% CH3CN the solvent electrophilicity parameter, ΔE = −5.84. In going from water to aqueous 50.9% CH3CN, the ortho inductive term grows twice less as compared with the para polar effect. Copyright © 2013 John Wiley & Sons, Ltd.

Time dependent solid-state 13C NMR study on alkaline hydrolysis of polyacrylonitrile hollow fiber ultrafiltration membranes

The effects of alkaline hydrolysis on the chemical structure of polyacrylonitrile (PAN) hollow fiber ultrafiltration (UF) membrane were studied using solid-state 13C NMR spectroscopy. The PAN membrane was hydrolyzed in an NaOH solution of pH 13, which is generally used in water industry for anti-fouling treatments of UF membranes but is much weaker than the alkaline concentrations (0.5–2.5N) used so far in conventional 13C NMR studies. All of the carbon sites of the PAN were characterized by the solid-state 1H–13C CPMAS and HETCOR NMR spectra. Upon the alkaline treatments, the chemical conversion from the cyano functional groups of the PAN to the carboxylates was observed. The analysis of the 13C CPMAS NMR spectra obtained as a function of the treatment time for 4–96h showed that the chemical modification occurred very rapidly in the early stage (≤6h) of the reaction but then proceeded slowly up to 96h. The relative amount of the hydrolyzed acrylonitrile units after 96h of the reaction at room temperature was estimated to be only 3.8%. We suggested that the alkaline hydrolysis of the PAN membrane proceeds at two distinct rates, a rapid conversion of the cyano groups on or near the membrane surface and a slow conversion of the bulk.

Kinetic study of hydrolysis of benzoates. part xxvii. ortho substituent effect in alkaline hydrolysis of phenyl esters of substituted benzoic acids in aqueous Bu4NBr

The second-order rate constants k (in dm3 mol–1 s–1) for alkaline hydrolysis of phenyl esters of meta-, para- and ortho-substituted benzoic acids, X-C6H4CO2C6H5, have been measured spectrophotometrically in aqueous 0.5 and 2.25 M Bu4NBr at 25 °C. The substituent effects for para and meta derivatives were described using the Hammett relationship. For the ortho derivatives the Charton equation was used. For ortho-substituted esters two steric scales were involved: the EsB and the Charton steric (υ) constants. When going from pure water to aqueous 0.5 and 2.25 M Bu4NBr, the meta and para polar effects, the ortho inductive and resonance effects in alkaline hydrolysis of phenyl esters of substituted benzoic acids, became stronger nearly to the same extent as found for alkaline hydrolysis of C6H5CO2C6H4-X. The steric term of ortho-substituted esters was almost independent of the media considered. The rate constants of alkaline hydrolysis of ortho-, meta- and para-substituted phenyl benzoates (X-C6H4CO2C6H5, C6H5CO2C6H4-X) and alkyl benzoates, C6H5CO2R, in water, 0.5 and 2.25 M Bu4NBr were correlated with the corresponding IR stretching frequencies of carbonyl group, (ΔνCO)X.

Kinetic Study of Hydrolysis of Benzoates. Part XXV. Ortho Substituent Effect in Alkaline Hydrolysis of Phenyl Esters of Substituted Benzoic Acids in Water

The second-order rate constants k2 for alkaline hydrolysis of phenyl esters of meta-, para- and ortho-substituted benzoic acids, X-C6H4CO2C6H5 (X = H, 3-Cl, 3-NO2, 3-CH3, 4-NO2, 4-Cl, 4-F, 4-CH3, 4-OCH3, 4-NH2, 2-NO2, 2-CN, 2-F, 2-Cl, 2-Br, 2-I, 2-CH3, 2-OCH3, 2-CF3, 2-NH2), and of substituted phenyl esters of benzoic acid, C6H5CO2C6H4-X (X = 2-I, 2-CF3, 2-C(CH3)3, 4-Cl, 4-CH3, 4-OCH3, 4-NH2), have been measured spectrophotometrically in water at 25 °C. The substituent effect in alkaline hydrolysis of phenyl esters of para-substituted benzoic acids, similar to that for ethyl esters of para-substituted benzoic acids, was found to be precisely described by the Hammett relationship (ρ = 1.7 in water). The log k value for alkaline hydrolysis of phenyl and ethyl esters of meta-, para- and ortho-substituted benzoic acids, X-C6H4CO2R, was nicely correlated with log km,p,ortho = log ko + (ρ)m,pσ + (ρI)orthoσI + (ρ°R)orthoσ°R + δorthoEsB where σ, σI, σ°R are the Hammett polar, Taft inductive and Taft resonance (σ°R = σ° - σI) substituent constants, respectively. EsB is the steric scale for ortho substituents calculated on the basis of the log k values for the acid hydrolysis of ortho- substituted phenyl benzoates in water owing to the ortho substituent in the phenyl of phenyl benzoates. In water, the main factors responsible for changes in the ortho substituent effect in alkaline hydrolysis of phenyl and ethyl esters of ortho-substituted benzoic acids, X-C6H4CO2R, were found to be the inductive and steric factors while the role of the resonance term was negligible ((ρ°R)ortho ca. 0.3). In alkaline hydrolysis of substituted benzoates in neat water, the ortho inductive effect appeared to be 1.5 times and steric influence 2.7 times higher than the corresponding influences from the ortho position in the phenyl of phenyl benzoates. The contributions of the steric effects in alkaline hydrolysis of esters of ortho-substituted benzoic acids was found to be approximately the same as in acid hydrolysis of esters of ortho-substituted benzoic and acid esterification of ortho-substituted benzoic acids.

Effects of alkaline hydrolysis and dynamic coating on the electroosmotic flow in polymeric microfabricated channels.

Protocols are described for control of the electroosmotic flow in microfabricated channels in Vivak copolyester. Alkaline hydrolysis of surface ionizable groups alone or such hydrolysis in combination with dynamic coating with cetyltrimethylammonium bromide (CTAB) is shown to provide reproducible electroosmotic flows. Dynamic coating with CTAB can be used to eliminate electroosmosis or to reverse its direction, depending on the concentration employed.

Mechanism of the inhibiting action of electrolytes on the micellar effect in alkaline hydrolysis of p-nitrophenyl ethyl chloromethylphosphonate

The influence of KCl, KBr and sodium salicylate (NaSal) on the micellar effect of cetylpyridinium bromide in the alkaline hydrolysis of p-nitrophenyl ethyl chloromethylphosphonate has been studied and the effects of electrolytes on the rate constant and surface potential compared; based on the data obtained, it can be concluded that the reaction inhibition is determined both by a change in the structure and properties of the micellar aggregates and by a decrease in the concentration of the nucleophile in the micelles due to a decrease in the surface potential.

Adsorption of albumin, collagen, and fibronectin on the surface of poly(hydroxybutyrate-hydroxyvalerate) (PHB/HV) and of poly(ε-caprolactone) (PCL) films modified by an alkaline hydrolysis and of poly(ethylene terephtalate) (PET) track-etched membranes

The effect of alkaline hydrolysis on several surface properties of poly(hydroxybutyratehydroxyvalerate) (92/8) (PHB/HV) and poly(ε-caprolactone) (PCL) films and of poly(ethylene terephtalate) (PET) track-etched membranes have been characterized, as well as the adsorption of three proteins normally encountered by mammalian cells in vivo, namely albumin, collagen, and fibronectin. The water contact angle decreases and the number of -COOH functions accessible to a chemical reaction at the surface of PCL increases with alkaline hydrolysis. Analysis by atomic force microscopy pictures reveals a change in surface morphology. The modifications of surface properties are correlated with a two times increase of the adsorption of three radiolabelled proteins. The hydrolysis results in a slight increase in the water contact angle of one face of the PHB/HV film and a sharp increase in the number of -COOH functions. Important morphology changes are also induced. The adsorption of the radiolabelled proteins is almost 100 times higher on the hydrolyzed polymer than on the native surface. The increase in hydrophilicity of different PET batches correlates to an increase in the number of -COOH functions. Nevertheless, the surface chemical composition and rugosity are constant and no significant difference in the amount of radiolabelled fibronectin adsorbed on the different surfaces is detectable. In conclusion, the effect of hydrolysis on the surface properties of each of the polyesters studied as well as the proteins adsorption on the different surfaces are different. The results strongly support the hypothesis that, in the system studied, parameters other than hydrophilicity influence protein adsorp

Nucleophilic aromatic substitution: transmission of substituent effects in alkaline hydrolysis of 4-aminophenylazobenzothiazolium dyes

Alkaline fading of 2′-, 5-, and 6-substituted 2-(4′-aminophenyl)azobenzothiazolium dyes (I) possesses [graphic omitted] a second-order rate constant (kOH). The value of kOH is shown to predicted by equation (i) where σN is log kOH= 0.76σN+ 0.24σS+ 1.69σ++ log[10–0.15(pK–9.5)/(1 + 100.25(pK–9.5))]+ 0.74 (i)σ+ for 6- and σ for 5-substituents, σs is σ– for 5- and σ for 6-substituents, σ+ is for 2′-substituents, and the pK is that of the leaving 4′-amine. The dye fading is not very sensitive to substituents in the benzothiazole phenyl ring but the charge is transmitted more effectively through nitrogen than through sulphur.

An Improved Method for Identifying 8-O-Acetyl-N-Acetylneuraminic Acid

The periodic acid/thionin-Schiff/potassium hydroxide/periodic acid/fuchsin-Schiff sequence developed by Culling et al. frequently causes damage to sections and gives inconsistent results because of insufficient primary oxidation and difficulties in making the thionin-Schiff reagent. These disadvantages have been largely eliminated by more thorough primary oxidation and by replacing the original thionin-Schiff with a new cold thionin-Schiff. The effect of alkaline hydrolysis on thionin-aldehyde complexes was also studied and the reduction of color caused by this treatment was restored by a second thionin-Schiff reaction. The new sequence gives consistent results and imparts greater color to the thionin-Schiff reaction.

Substituent and solvent effects in alkaline hydrolysis of thioamides

Substituent and solvent effects in alkaline hydrolysis of thioamides

Ortho Effect in Alkaline Hydrolysis of ortho-Substituted Benzoylcholine Esters

Second-order rate constants were determined for the alkaline hydrolysis of ortho-substituted benzoylcholine esters in 0.1 M aqueous NaCl at pH 9.0. Activation parameters for the reactions were calculated from the slopes of Arrhenius plots, with all plots being linear in the range of 25–45°. One derivative, o-methylbenzoylcholine, exhibited an abrupt change in the Arrhenius slope above 50°. Over the same extended temperature range, benzoylcholine and o-chlorobenzoylcholine gave no such change. An average isergonic temperature, ß = 267°K., was calculated for the series from three independent correlations involving activation (∆H±versus ∆S±), rate (log k1versus log k2), and linear free energy (pT versus 1/T) data. The parameters ∆G±, AH±, and ∆S± each correlate independently with σ1) the Taft inductive constant, indicating that the hydrolysis reactions are “well behaved.” By comparison, thermodynamic parameters for acetic acid ionizations (i.e., a model process defining σ1) are not well behaved: ∆H° versus ∆S° is nonlinear, but ∆G°, ∆H°int, and ∆S° correlate independently with σ1. Rho–sigma correlations and an isergonic relationship for the benzoylcholine reactions are interpreted on the basis of the Hammett and Hepler analyses, respectively. Entropy values for this congeneric series are discussed in relation to the positive charge on the quaternary nitrogen and its effect in potentially neutralizing the substituent charge.