Sodium Hydrogen Research Articles

Photochemical degradation of dexamethasone by UV/Persulphate, UV/Hydrogen peroxide and UV/free chlorine processes in aqueous solution using response surface methodology (RSM)

ABSTRACT Dexamethasone (DEX) degradation was investigated using three UV-based advanced oxidation processes combined with sodium persulphate, hydrogen peroxide, and free chlorine in aqueous solutions in a bench-scale reactor. The goal was to determine which process would be the best option in terms of DEX degradation without the subsequent generation of toxic compounds. The process performance for DEX degradation followed the UV/S2O8 2−> UV/H2O2> UV/HOCl order under equal conditions. In the UV/S2O8 2− process, sulphate radicals led to a 70.4% DEX degradation. The experimental mineral inhibitory factors showed that nitrite and bicarbonate further decrease the efficiency of the UV/S2O8 2− process. In the optimal conditions, the UV/S2O8 −2 process removed DEX by 100% and had a 74.1% mineralisation. Furthermore, the intermediates were detected using LC-MS/MS, and the cytotoxicity of the UV/S2O8 −2 process effluent was evaluated using human embryonic kidney cultured cells. The treatment of DEX solution by the UV/S2O8 −2 process significantly decreased the toxicity of the effluent. Therefore, it can be concluded that the UV/S2O8 −2 process can be a reliable process for DEX degradation and detoxification in aqueous solutions.

Behavior Estimation Focusing on the Existing Form of Hydrogen in Sodium in Sodium-Cooled Fast Reactors

In the cooling system of sodium-cooled fast reactors, it is required to identify and rapidly detect hydrogen explosively produced by the sodium-water reaction when a water leak occurs due to damage of a heat exchanger tube in a steam generator (SG), in contrast to low-concentration background hydrogen permeating through SG tubes during normal operation. In the present study, we focus on the difference between the background hydrogen and the hydrogen generated by the sodium-water reaction, and theoretically estimate the hydrogen behavior in liquid sodium by using computational chemistry methods. We find that dissolved H or NaH, rather than H2, is the predominant form of the background hydrogen in liquid sodium, and that hydrogen produced in large amounts by the sodium-water reaction can exist stably as fine bubbles with a NaH layer on their surface.

Treatment of Egg Shells with Hydrogen Peroxide and Sodium Carbonate as a Disinfectant with Bactericidal Effect to Eliminate Salmonella Entereditis

The objective of this study was to discover the effects of applying two antimicrobial drugs (sodium carbonate and hydrogen peroxide) on chicken eggshell on a poultry farm in Kosovo. Salmonella infections in egg contents may be related to external contamination of the eggshell. The first study was performed by applying sodium carbonate to the eggshell at different concentrations and pH of 10, 11 and 12 versus some Salmonella concentrations found in the analyzed eggs. A high amount of total bacteria was observed in all samples, but after the application of disinfectants we saw a decrease of these bacteria. The second study was performed to determine which concentration of H2O2 would give the maximum reduction of bacteria. In work 2, treatments were performed on 1) dry sample, 2) 0.5% H2O2, 3) 1% H2O2, 4) 1.5% H2O2, 5) 2% H2O2, 6) 2.5% H2O2 and 7) 3% H2O2.For shell tests, inactivation of Salmonella Enteritidis occurred at lower concentrations at pH 12 than at pH 11 and pH 10. The time of contact between the chemicals and Salmonella apparently results in accelerated bacterial inactivation.

Treatment of Egg Shells with Hydrogen Peroxide and Sodium Carbonate as a Disinfectant with Bactericidal Effect to Eliminate Salmonella Entereditis

The objective of this study was to discover the effects of applying two antimicrobial drugs (sodium carbonate and hydrogen peroxide) on chicken eggshell on a poultry farm in Kosovo. Salmonella infections in egg contents may be related to external contamination of the eggshell. The first study was performed by applying sodium carbonate to the eggshell at different concentrations and pH of 10, 11 and 12 versus some Salmonella concentrations found in the analyzed eggs. A high amount of total bacteria was observed in all samples, but after the application of disinfectants we saw a decrease of these bacteria. The second study was performed to determine which concentration of H2O2 would give the maximum reduction of bacteria. In work 2, treatments were performed on 1) dry sample, 2) 0.5% H2O2, 3) 1% H2O2, 4) 1.5% H2O2, 5) 2% H2O2, 6) 2.5% H2O2 and 7) 3% H2O2.For shell tests, inactivation of Salmonella Enteritidis occurred at lower concentrations at pH 12 than at pH 11 and pH 10. The time of contact between the chemicals and Salmonella apparently results in accelerated bacterial inactivation.

Hydrogen sensors for comprehensive detection of steam leak in sodium-cooled fast reactors

A comprehensive hydrogen detection system is developed to track steam leak into sodium by monitoring hydrogen in liquid sodium and in argon cover gas simultaneously and its performance is demonstrated. A fraction of hydrogen, generated from steam leaks, gets dissolved in liquid sodium while the other enters the cover gas and its relative distribution depends on the sodium temperature. Detectors for hydrogen in sodium and argon cover gas are deployed to track the hydrogen in liquid sodium and in cover gas to assess the extent of the steam leak.

Effect of sodium borohydride and hydrogen peroxide pretreatments on soda pulping of sugar maple (Acer saccharum)

For recovering value-added wood-based organic material prior to delignification, sodium borohydride (NaBH4) and hydrogen peroxide (H2O2) pretreatments under alkaline conditions were performed before soda pulping of sugar maple (Acer saccharum) chips with sodium hydroxide (NaOH). In this investigation, it was determined whether the pulp yield could be increased by partly stabilizing the hemicelluloses by these pretreatments, and simultaneously obtains lower pulp kappa numbers. The results indicated that when aiming to the same kappa numbers (i.e., kappa numbers 14.3-20.5), roughly 3% higher pulp yield could be achieved if the chips were pretreated with alkaline 0.5% NaBH4 solutions, compared to those produced without such pretreatment or pretreated only with NaOH (i.e., without NaBH4). In contrast, pretreatments conducted with alkaline 2.5% H2O2 did clearly lower pulp yields at the same kappa number range (14.0-22.7) when compared to the reference cooks conducted with NaOH pretreated materials. However, an increase in the H2O2 charge of the pretreatment from 2.5% to 5.0% had a clearly beneficial effect, as the pulp yield and kappa numbers after pulping of 5.0% H2O2 pretreated pulps were comparable to the reference cooks.

The effect of treatment with sodium carbonate and hydrogen on the activity and selectivity of polymeric Pd-containing catalysts for hydrogenation of acetylene compounds

Catalytic hydrogenation of the triple carbon-carbon bond of acetylene compounds is an important industrial process. High selectivity to the olefin compound should be provided in the process. This study considers the effect exerted by sodium carbonate treatment of the palladium catalysts containing super-cross-linked polystyrene (SPS) on their activity and selectivity in the hydrogenation of 2-methyl- 3-butin-2-ol and phenylacetylene. The effect of such treatment was shown to depend on the chosen palladium precursor and the type of polymeric support (non-functionalized SPS or that containing ternary amino groups). At atmospheric pressure of hydrogen and a temperature of 90 °C in a toluene medium, the 1%-Pd/SPS catalysts treated with Na2CO3 provided a 98 % selectivity in the hydrogenation of 2-methyl-3-butin-2-ol (at a 95 % conversion of the substrate), while selectivity in the hydrogenation of phenylacetylene reached 99.5 %.

Lactic Acid Bacteria against Listeria monocytogenes

Background: Listeria monocytogenes is a pathogenic bacterium that can contaminate food and cause public health problems due its ability to form biofilms and resistance to sanitizers, it is responsible for sanitary and economic losses in food producing establishments. The difficulties in controlling biofilms and increasing resistance to traditional antibacterial agents is motivating studies of alternative potential biological agents for the control of pathogenic biofilms, among which lactic acid bacteria (LABs) are included. The objective of this work was to evaluate the activity of LABs against Listeria monocytogenes biofilm formation on polystyrene plates, a surface commonly used in the food industry.Materials, Methods & Results: Lyophilized commercial strains of Bifidobacterium animalis, Lactobacillus fermentum, Lactobacillus plantarum, Lactobacillus salivaris and Lactobacillus acidophilus were used. The strain of Listeria monocytogenes (L4) was isolated from polystyrene mats from a poultry slaughterhouse cutting room and demonstrated the ability to attach to microplates and resistance to sanitizers (sodium hypochlorite and hydrogen peroxide) at all times, temperatures and tested surfaces. The antimicrobial activity of LABs was evaluated by the agar diffusion method. The LABs that presented action on Listeria monocytogenes were selected for the inhibition and/or removal of biofilms in microplates, and all experiments were carried out in triplicate. Only Bifidobacterium animalis and Lactobacillus plantarum demonstrated action against Listeria. monocytogenes in the agar diffusion assays and were selected for inhibition and competition assays. Furthermore, competition of LABs against Listeria monocytogenes adhesion was evaluated. There was no significant difference between LABs and Listeria monocytogenes, alone or in combination, at temperatures of 30ºC and 37ºC in the Listeria monocytogenes inhibition assays on polystyrene surface. The lactic acid bacteria evaluated did not demonstrate inhibition of Listeria monocytogenes adhesin testes with optical density visualization, however, it was possible to identify a reduction in Listeria monocytogenes counts with the application of Bifidobacterium animals and Lactobacillus plantarum in the testes of competition against biofilm formation. In competition tests Bifidobacterium animalis and Lactobacillus plantarum have an injunction in Listeria monocytogenes, indicating that these lactic acid bacteria can retard Listeria biofilm formation on polystyrene surfaces and thus help control the pathogen in the food industry.Discussion: A potential mechanism to control biofilm adhesion and formation of pathogens for nutrients and fixation on surfaces, multiplication factors and surfaces are a challenge in controlling biofilms of pathogenic microorganisms, alternative measures to traditional methods for inactivating pathogens and biofilm formers bacteria are necessary. In this sense, lactic acid bacteria generate high levels of bacteriocin and are effective in inhibiting the biofilm of pathogenic bacteria, however, our study did not reveal this. We verified that Bifidobacterium animalis and Lactobacillus plantarum have an inhibitory action on Listeria monocytogenes, indicating that these lactic acid bacteria can be used to delay the formation of biofilms by Listeria on polystyrene surfaces, helping to control this pathogen in food industry.Keywords: control of biofilm, pathogenic bacteria, food industry, polystyrene surface, FTDs.

ИНТЕГРАЛЬНАЯ ПРОМЫШЛЕННАЯ СИСТЕМА УТИЛИЗАЦИИ ТЕХНОГЕННЫХ ОТХОДОВ ГОРНЫХ ПРЕДПРИЯТИЙ, ТЕРРИТОРИАЛЬНО ОБЪЕДИНЁННЫХ

At present, there is a need for import substitution (including technologies) in Russia, so the manuals development and regulation of the best available technologies (BAT, Best Available Technologies) are underway. BAT manuals, for example, for the mining industry are basic documents that provide a step-by-step description of BAT, ensuring compliance with obligatory environmental performance indicators. However, these are isolated, unrelated short versions that do not allow for a comprehensive solution to the problems of available mineral resources (AMR) deficit and reduction of environmental degradation risks. To solve the above problems, it is necessary to develop an integrated system for the disposal of man-made waste from mining and mining processing enterprises, geographically united, in order to identify, select effective technologies from alternative proposals and their implementation. The purpose of the study is to develop an integrated system for the disposal of technogenic waste from mining enterprises that are geographically united. Research objectives: study of waste disposal facilities included in the State Register of the Russian Federation; development of a technological scheme for the joint processing of technogenic raw materials of various types; development of a stationary cuvette for year-round heap leaching (KV) of gold in the cryolithozone; conducting experimental studies of KV gold with an effective reagent complex; development of an integrated industrial system for the disposal of technogenic waste from mining enterprises, geographically united; development of alternative options for the production of gold in order to choose an effective technology, depending on the nature of gold mineralization and the form of finding the precious metal in man-made waste. The authors have scientifically substantiated and developed the variants of the integrated industrial system of the closed cycle, using mobile operatively tunable flow lines consisting of independent modules for technogenic waste processing of Darasunsky mine - the enterprise for extraction and ore enrichment of Darasunsky, Teremkinsky and Talatuysky gold deposits (Tungokochensky and Transbaikal regions). According to the cadastre of technogenic accumulations, the sources of mine wastes with the volume of 14410.2 thousand tons are waste dumps of overburden rocks and poor ores, technogenic raw materials of tailing dumps, other accumulations of technogenic raw materials. Experimental studies of gold heap leaching (HL) by the reagent complex including solutions of sodium cyanide and hydrogen peroxide in the ratio – H2O2:NaCN=10:1 have been carried out. Optimal technological parameters of ore preparation and gold leaching process from waste pelletized granules of different types at a ratio of 1:0.5:0: 5 are established, accordingly, out of balance ores of the Talatuy deposit (βAu – 0.7 g/t), underlaid tailings (βAu – 1.45 g/t) and tailings of the current ore processing of Darasunsky gold concentration plant (GCP) (βAu – 0.3 g/t). Gold recovery has amounted 87.1%. In order to implement year-round heap leaching in the cryolite zone, a deepened concrete ditch with multilayer shielding of the upper surface of the stack by injecting warm air through specially equipped perforated vinyl pipes has been installed and a special pelletized granules placement has been carried out. After neutralization KV waste has been proposed to be used in the road construction industry. The industrial system developed by the authors makes it possible to carry out all year round KV, to commercialize utilization of man-caused deposits, both for a long conservation period and the current production and processing, to improve the environmental safety of the city-forming enterprises of the mining cluster. Alternative options are proposed in order to choose an effective technology

Preventive Guidelines for Disinfection and Microbiological Processes During Handling of COVID-19 Samples

Since the first detection and emergence of SARS-CoV-2 in Wuhan, China in December 2019, it has become a worldwide health concern. Human to human airborne transmission and persistence of SARS-CoV-2 on inanimate surfaces or contaminated hands have been documented. Droplets transmission has been recognized as a major source of virus spread. Most of the samples received in the pathology laboratories were for the diagnosis of the corona virus disease-2019 (COVID-19). The highest concentration of SARS-CoV-2 has been observed in the respiratory specimens compared to the non-respiratory specimens as the virus is present in lower concentration in urine, blood, and stool. The guidelines in this article present the procedures for disinfection and microbiological processes that should minimize the risk of infection to the laboratory personnel. Surface disinfection with sodium hypochlorite (0.1%), ethanol (62%-71%), or hydrogen peroxide (0.5%) with an exposure time of 1 min is likely to be efficient against SARS-CoV-2. However, the ultraviolet light at 254 nm, glutaraldehyde, formalin, heat treatment of 65 ◦C or above, and acidic (pH <3) may be effective for inactivating SARS-CoV-2. The SARS-CoV-2 can remain infectious on the inanimate surfaces for up to 9 days so laboratory personnel should be aware of the need for following the biosafety protocols while processing the specimens.

In Vivo Comparison of Chlorine-Based Antiseptics versus Alcohol Antiseptic for Surgical Hand Antisepsis.

Despite being commonly used as effective preparation for surgical hand antisepsis, alcohol solutions have major drawbacks, such as drying effect, emergence of hand eczema, and other diseases. This study aimed to demonstrate the effectiveness of sodium hypochlorite (NaOCl) and hydrogen peroxide (H2O2) as antiseptic in comparison to single sodium hypochlorite and 70% ethanol. In 5-day tests, the effects of 3 antiseptics were established according to standard test methods. The antiseptics were applied to the hands of 82 volunteers, and samples of bacteria were collected on days 1 and 5, immediately after drying and 6 hours later after antiseptic application. Student's t test and ANOVA were applied in a statistical study. The NaOCl with H2O2 composition demonstrated noninferiority to both sodium hypochlorite only and alcohol products and superiority to these antiseptics on day 5 (P < 0.05 at a significance level of 5% for each comparative trial in this day) at equivalence margin of 20%. The effectiveness of the NaOCl plus H2O2 composition as an antiseptic was explained by the formation of singlet oxygen in the system. Together, these data suggest that NaOCl and H2O2 may be an effective hand antisepsis that avoids the drawbacks seen with alcohol solutions.

Characterization of Surface Modified Nettle Fibers for Composite Reinforcement

ABSTRACT One of the major issues associated with the use of plant fibers in composite fabrication is their hydrophilic nature, which leads to poor interfacial interaction between the fibers and matrix. Therefore, it is essential to modify the plant fibers prior to composite fabrication. Several researchers investigated the potential use of chemically treated cellulosic bast fibers such as jute, flax, hemp, ramie, and kenaf in composite development. However, there is another natural bast fiber ‘nettle’, which is least investigated for making biocomposites. In this study, nettle fibers were treated with chemicals such as sodium hydroxide, hydrogen peroxide, and sodium chlorite and the influence of chemical treatment on the characteristics of nettle fibers were investigated. The characteristics of raw and chemically treated nettle fibers were investigated through chemical composition analysis, thermogravimetric analysis, Fourier transform infrared spectroscopy, scanning electron microscopy and water sorption test. The results showed that the nettle fiber is a potential reinforcement material for composite fabrication.

Phenolic substances as regulators of the intensity of lipid peroxidation processes of the strains Pleurotus eryngii, Fistulina hepatica and Agrocybe cylindracea

The work is devoted to the calculation, comparison of indicators and the development of a method for regulating the intensity of lipid peroxidation processes (LPP) of strains of basidiomycetes. The purpose of the investigation is to study the effect of phenolic type chemicals and hydrogen peroxide on the lipid peroxidation of certain strains of basidiomycetes under laboratory cultivation. Cultivation of strains of basidiomycetes was carried out by periodic surface method on glucose-peptone medium (GPM) in flasks. The influence of sodium lignosulfonate, tannin, gallic acid and hydrogen peroxide at 0.1% concentration at 24 and 48 hours of exposure on the intensity of lipid peroxidation processes of the strains Pleurotus eryngii P-er, Fistulina hepatica Fh-08 and Agrocybe cylindracea 960, fungi of the phylum Basidiomycota, orderAgaricales has been investigated. It was established that the used phenolic-type chemical compounds that are part of the lignocellulose complex of wood or are the products of its decomposition to a certain extent affect the lipid peroxidation processes of mycelial cell lipids in the studied cultures of basidium fungi. The individual reaction of LPP of cultures to the applied substance and the time of its exposure are determined. The highest degree of LPP induction was recorded upon addition of tannin – by 161%, after 48 hours of exposure in the mycelium of strain Fh-08; sodium lignosulfonate – by 192%, after 48 hours in the mycelium of strain P-er; gallic acid – by 182%, after 24 hours, in the mycelium of strain P-er; hydrogen peroxide – by 257%, after 24 hours, in the CR of strain 960. The biotechnological significance of this is the possibility of regulation (induction or repression) of LPP of producer strains. From a biomedical point of view, the possibility of changing the activity of lipid peroxidation processes of mycelium and culture fluid makes it possible to obtain and use more effective functional products of fungal origin.

The reaction of lignin model compounds during enzymatic bleaching with a Curvularia verruculosa haloperoxidase: impact on chlorination

AbstractRecent developments in enzymatic bleaching processes have led to replacement strategies of harsh chemicals by haloperoxidases. For this purpose, it is important to control the haloperoxidase-mediated formation of adsorbable organic halides (AOX). In this study, we studied the chlorination of monomeric and dimeric lignin model substrates. Guaiacol, acetovanillone, veratryl alcohol, pinoresinol and adlerol were treated with Curvularia verruculosa haloperoxidase and compared to a sodium hypochlorite treatment. High-performance liquid chromatography-diode array detection-mass spectrometry (HPLC-DAD-MS) analysis was employed for the characterization of the reaction products. Our results show that while treatment with haloperoxidases in the presence of sodium chloride and hydrogen peroxide leads to no improvement in AOX formation compared to chemical treatment with NaOCl, addition of ammonium chloride substantially lessens chlorination and promotes β-O-4 ether bond cleavage. The use of ammonium chloride in conjunction with enzymatic haloperoxidase-based bleaching could be a route to minimize lignin chlorination.

Novel Synthesis of β-Keto Cycloacetals via Organoboranes

(Z)-1-Bromo-1-alkenylboronate esters were easily synthesized from the hydroboration of terminal alkynes with dibromoborane dimethyl complex under nitrogen atmosphere followed by treatment with propne-1,3-diol. These boronate esters are readily reacted with 1,3-dioxan-2-ylethyl)magnesium bromide in ether and tetrahydrofuran at -78 ºC for 1 h. The resulting "ate" complex upon addition of sodium methoxide in methanol undergo intramolecular nucleophilic substitution reactions to produce the corresponding (E)-alkenylboronate esters containing (1,3-dioxan-2-ylethyl) moiety in 70-82% isolated yields. The resulting intermediates are oxidized with sodium acetate and hydrogen peroxide to provide the corresponding β-keto cycloacetals in good yields (68-84%).

Optimization of Alkaline Degumming Process of Hemp Fibers

ABSTRACT The optimization of the alkaline degumming process of the hemp fibers was carried out in this study. The degumming parameters were optimized in such a way that the minimum strength loss of hemp fibers and elementary fibers was achieved. The main aim of this research work was to individualize and segregate the fibers uniformly by the removal of lignin content. Hemp single fiber tensile strength was carried out before and after the degumming process to determine the strength loss. It was carried out using a padding mangle and steamer technique. The best-suited alkali degumming method was investigated with the optimized parameters of heating time 45 min and heating temperature 120°C. The chemicals that provided the finest results were sodium hydroxide, wetting agent and hydrogen peroxide.

Stabilization of Silver Nanoparticles with a Dithiocarbamate Ligand and Formation of Nanocomposites by Combination with Polythiophene Derivative Nanoparticles

Spherical morphology for silver nanoparticles (Ag NPs) stabilized with dithiocarbamate (DTC) by reducing silver nitrate with sodium borohydride was obtained, while the addition of sodium citrate and hydrogen peroxide allowed the formation of silver nanotriangles (Ag NTs). Solutions of bright yellow and blue colors characteristic of both morphologies were observed. UV-vis optical analysis of NPs stabilized with DTC showed a plasmonic absorption band at 393 nm characteristic for spherical morphology, while two bands were observed at 332 nm and 762 nm, and a shoulder around 500 nm for the triangular morphology; with these spectra each morphology was confirmed. In these spectra an absorption band between 250 and 260 nm confirms the presence of DTC ligand. The stability of the NPs was achieved using an 8.69 × 10-3 mM solution of 4-(ethylaminodithiocarbamate) methylpyridine di-n-butyltin (IV) through a transmetallation reaction. Silver nanoparticles (Ag NPs) with spherical morphology of average diameter of 12.7 ± 1.2 nm and triangular morphology with 28.9 ± 0.8 nm for each side of the triangles were analyzed by high resolution scanning electron microscopy (HR-SEM). UV-vis spectra also showed the stability of NPs with DTC for more than three months. A copolymer derived of 3-hexylthiophene with (E)-2-(ethyl(4-((4-nitrophenyl) diazenyl) phenyl) amino) ethyl 2-(thiophen-3-yl) acetate (PA) was tested to get polymer NPs by reprecipitation method using THF/water systems. PA Polymer NPs having average diameter of 9.0 ± 1.7 nm were found. By quick and easy procedure, the formation of nanocomposite (NC) of spherical Ag NPs and PA polymer NPs was reached. This NC could be used as imaging agent, electrochemical biosensor, and photonic and optoelectronic device materials.

Kinetics of the chromium(III)/l‐glutamic acid complexation reaction: Formation, decay, and UV‐vis spectrum of a long‐lived intermediate

AbstractThe kinetics of the aqueous reaction of Cr(III) with either l‐glutamic acid or sodium hydrogen l‐glutamate at pH 2.46‐5.87 have been followed by means of absorbance readings. The rate of formation of the reaction products showed acceleration‐deceleration periods, caused by the accumulation and posterior decay of an intermediate in nonnegligible concentration. A double‐exponential integrated rate law allowed obtaining two rate constants for each absorbance‐time experimental series, associated with the appearance (k1) and decay (k2) of the long‐lived intermediate. An increase of the initial concentrations of either hydrogen l‐glutamate (apparent kinetic orders &lt; 1) or hydroxide (kinetic orders = 1) ions resulted in an increase of both k1 and k2, but addition of an inert electrolyte (KNO3) resulted in opposite effects on k1 (decrease) and k2 (increase). The experimental activation energies were 83 ± 10 (for k1) and 95 ± 5 (for k2) kJ mol−1. The electronic spectrum of the low reactivity detected intermediate resembled more closely to that of the blue/green reactant than that of the violet reaction product. The low number of protons set free by the complexating hydrogen l‐glutamate ligand seems to suggest that some polymerization of the coordinated amino acid (to form a di‐ or tripeptide) might take place. The available experimental data indicate that the coordination of the organic ligand must be preceded by the breakdown of a strong Cr(III)–H2O chemical bond in the slow steps of the mechanism.

Effect of sequential treatments with sodium dodecyl sulfate and citric acid or hydrogen peroxide on the reduction of some foodborne pathogens on eggshell.

The aim of this study was to investigate the effect of sodium dodecyl sulfate (SDS), citric acid, and hydrogen peroxide (H2O2), alone or in combination, on reducing the population of four foodborne pathogens, including Escherichia coli, Listeria monocytogenes, Salmonellatyphimurium, and Staphylococcus aureus on eggshells. In each series of tests, eight fresh eggs were inoculated with each bacterial strain by being immersed in a bacterial suspension and exposed to SDS (1.5%), H2O2 (0.5%), citric acid (1%), or sequential treatments with SDS + citric acid and SDS + H2O2. Viable cell counts were made and the bacterial concentrations results compared to pre-treatment levels. Results showed that all washing solutions except citric acid significantly (P<0.05) reduced the concentration of all tested bacteria (~2-4 log reductions). The sensitivity of S. typhimurium and E. coli to SDS and H2O2 was similar (~2.5 log reduction). Listeria monocytogenes (4.1 Log reduction) and S. aureus (4.3 Log reduction) were more sensitive to SDS and H2O2, respectively. The combination of SDS and citric acid or H2O2 in comparison to SDS alone, generally did not produce significant additive reductions in the viability of the bacteria on eggshells. These data suggest that SDS potentially could be used alone or in combination with citric acid or H2O2 as an effective and inexpensive method to reduce bacteria, such as L. monocytogenes, on eggshells. Additionally, application of SDS may be useful for bacterial decontamination of other materials and surfaces in food industries.

Treatment modalities of discoloured tooth-A review article

Aesthetics by definition is the science of beauty or that particular detail of an animate/inanimate object that makes it appealing to the eye. Discolouration of the tooth can erode the sparkle from a smile. This is one of the most frequent reasons why a patient seeks dental care. Tooth discolouration varies in aetiology, appearance, localisation, severity, and adherence to tooth structure. Many techniques have been used to achieve considerable results in the treatment of discoloured teeth. Commonly used techniques include oral prophylaxis, resin infiltration, composites, bleaching, veneers, Porcelain fused metal crowns and zirconia crowns. In recent decades, the management of carious lesions has shifted the paradigm of drilling and filling into the paradigm of prevention, control and minimally invasive restoration. Ceramic laminate veneers have opened a new era in the field of dentistry known as ‘aesthetic dentistry'. Laminate veneers are a good and conservative alternative to full coverage crowns for improving the appearance of an anterior tooth. Bleaching included the length of time to achieve a lightening effect and technique sensitivity, with teeth often reverting back to their original colour. The current techniques involve a broad-spectrum approach utilising hydrogen peroxide (3–38%) with or without heat or laser, carbamide peroxide (10–30%), or a mixture of sodium perborate and hydrogen peroxide. New technologies for whitening teeth involve the use of activating agents such as light activation, ultrasound activation and others to enhance the production of hydrogen peroxide.