Effects of Surfactant Volume Fraction on the Antioxidant Efficiency and on The Interfacial Concentrations of Octyl and Tetradecyl p-Coumarates in Corn Oil-in-Water Emulsions

Surfactants have been used for decades in the food industry for the preparation of lipid-based emulsified food stuffs. They play two main roles in the emulsification processes: first they decrease the interfacial tension between the oil and water, facilitating droplet deformation and rupture; second, they reduce droplet coalescence by forming steric barriers. However, addition of surfactants to binary oil-water mixtures also brings up the formation of three-dimensional interfacial layers, surrounding each emulsion droplet, that significantly alter chemical reactivity. This is the case, for instance, in the inhibition reaction between antioxidants and the lipid radicals formed in the course of the spontaneous oxidation reaction of unsaturated lipids, which are commonly employed in the preparation of food-grade emulsions. The rate of the inhibition reaction depends on the effective concentrations of antioxidants, which are mostly controlled by the amount of surfactant employed in the preparation of the emulsion. In this work, we analyze the effects of the surfactant Tween 20 on the oxidative stability and on the effective concentrations of two model antioxidants derived from cinnamic acid, determining their interfacial concentrations in the intact emulsions to avoid disrupting the existing equilibria and biasing results. For this purpose, a recently developed methodology was employed, and experimental results were interpreted on the grounds of a pseudophase kinetic model.

A case of pseudotuberculosis with lethal outcome

A rare case of pseudotuberculosis with lethal outcome in the child aged two months and 20 days is described. Y. pseudotuberculosis infection of the child occurred likely in using milk, for the second time contaminated by the pseudotuberculosis pathogene. The inhibition reaction of indirect hemagglutination is more sensitive method of revealing Y. pseudotuberculosis than the bacteriologic method.

Efficiency of fire extinguishing with general purpose fire extinguishing powder in case of non-stationary interaction of its particles with burning material

Evaluation of the effectiveness of fire extinguishing by jet systems of powder fire extinguishing in conditions of non-stationary heat exchange processes and heterogeneous inhibition of active flame centers by powder particles was the aim of the work. The theoretical dependence of the amount of heat, absorbed by the particles of fire extinguishing powder, and the reaction rate of heterogeneous active centers of flame, inhibiting them, in non-stationary conditions of heat transfer, as well as inhibition reaction for fire extinguishing ink jet systems were obtained. The extinguishing of a flame with a fire extinguishing powder under non-stationary conditions is more effective, the smaller is the effective size of the powder particles, the longer is their stay in the combustion zone, and the shorter are the characteristic times of heat transfer and inhibition reaction. Comparison of the estimates of the characteristic duration of heat transfer and inhibition reaction for widely used fire extinguishing powders has shown a large inertia of the thermal mechanism of fire extinguishing, which greatly reduces its effectiveness at high speeds of powder particles in the combustion zone.

Profiling of Cholinesterase Extracted from The Brain Tissue of Diodon hystrix and Its Inhibition Reaction Towards Carbamates

Diodon hystrix, commonly known as spot-fin porcupine fish is a salt-water fish belonging to the Diodontidae family. It is widely distributed in Sabah wet market due to its commercial value. This study exploits the effectiveness of Cholinesterase (ChE) obtained from the brain tissue of D. hystrix in detecting carbamates inhibitory activities. Carbamate pesticides known to inhibit ChE and toxic towards living organisms can contaminate the water bodies. By using diethylaminoethanol (DEAE) Sepharose ion exchange chromatography, a total of 40% recovery yield of ChE was obtained with a 165.77 purification fold. Furthermore, the ChE showed a high affinity towards acetylthiocholine iodide (ATC) with an optimum activity at pH 7.45 and temperature ranging from 20 to 40℃. Among five different types of carbamates, methomyl was found to have the highest percentage of inhibition analyzed using ChE inhibitory assay, followed by carbofuran, bendiocarb, carbaryl and propoxur with >85% inhibition rate. The results concluded that ChEs extracted from the brain tissue of D. hystrix are applicable to be used as a bioindicator in detecting the presence of carbamates.

Efficiency of heterogeneous inhibition of active flame centers by fire extinguishing powder particles under non-stationary interaction conditions

Предложена модель механизма гетерогенного ингибирования активных центров пламени частицами огнетушащего порошка общего назначения при нестационарном взаимодействии. Проведена оценка эффективности гетерогенного ингибирования активных центров пламени частицами огнетушащего порошка в нестационарном режиме их взаимодействия. Полученные результаты могут быть использованы для оптимизации условий и режимов подачи огнетушащего порошка в зону горения в целях достижения максимального эффекта тушения пожара. The relevance of the work is due to the need to improve the efficiency of powder fire extinguishing systems. The aim of this work is to evaluate the effectiveness of the mechanism of heterogeneous inhibition of active flame centers by particles of fire extinguishing powder under non-stationary conditions of interaction. It was achieved by the method of theoretical modeling. There are obtained theoretical dependences of the reaction rate of heterogeneous inhibition of active flame centers by fire extinguishing powder particles on their dispersed and dynamic characteristics under non-stationary conditions of active particles interaction with the inhibitor surface. The efficiency of heterogeneous inhibition of active flame centers by fire extinguishing powder particles in a non-stationary mode of their interaction was evaluated. Fire fighting with fire extinguishing powder under non-stationary conditions is more effective the smaller the effective size of powder particles, the effective duration of the inhibition reaction and the longer the interaction time of powder particles with active flame centres. It was established that inhibition efficiency depends either on the kinetic parameters of active centers and disperse characteristics of the powder particles or on the ratio of interaction time of powder particles with the active centers as well as the characteristic duration of inhibition reaction. The results obtained allow optimizing the conditions and modes of fire extinguishing powder supply to the combustion zone in order to achieve the maximum effect of fire extinguishing.

Method for evaluating the neuraminidase activity of receptor-destroying enzyme (RDE) compounds using the influenza virus

Introduction. The classic hemagglutination inhibition reaction (RTGA) is used to determine the level of antiviral antibodies in human and animal serum specimens. During the performance of RTGA the tested sera must be treated with a receptor-destroying enzyme (RDE) to remove serum glycans that degrade the accuracy of the RTGA results. To optimize the amounts of RDE compounds used, it is necessary to know their real neuraminidase activity. This article describes a simple and economical method for testing the neuraminidase activity of receptor-destroying compounds using standard reagents and laboratory equipment.Aims of investigation. Design of an improved simple and convenient method for evaluating the neuraminidase activity using the flu virus.Material and methods. Here, we propose a convenient method for evaluating the activity of neuraminidase by double-fold dilution procedure with human or animal erythrocytes followed by hemagglutination assay with influenza A virus.Results and discussion. The method is based on the ability of neuraminidase to hydrolyze sialic acid residues on the cell surface of erythrocytes, that deprives red blood cells to be agglutinated with the flu virus, since these sialic glycans provide virus attachment and hemagglutination.Conclusion. The designed method allows the accurate measurement of the receptor-destroying (neuraminidase) activity of RDE compounds and the comparison of the compounds with each other. This test is necessary to optimize the RTGA protocol when monitoring blood sera of animals and humans after influenza infection and/or Acute Respiratory diseases (ARD). The designed method can be included in the guidelines of regulations for the RTGA protocol, which is used in different laboratories to monitor the epidemic process of influenza and ARD infections.

Preparation of ferrocene core dendrimers and immobilization of AChE for detection of diclofop-methyl herbicide

The aim of this work was to investigate diclofop-methyl detection (found in a variety of herbicides) using novel dendrimers that have ferrocene cores, as well as their Pt(II) and Pt(IV) complexes. Novel dendrimer structures were synthesized and characterized by molar conductivity, magnetic susceptibility, FTIR, UV-Vis, 1H-NMR and LC-MS methods. Then, the AChE (acetylcholine esterase) enzyme was immobilized on the novel dendrimers, and the optimal parameters (pH, temperature, repeated use, storage stability, substrate concentration) were determined for immobilized AChE. Lastly, changes in absorbance intensity were measured, and calibration graphs were plotted that reflect the inhibition reaction of immobilized AChE with diclofop-methyl. The inhibition interaction of the enzyme immobilized to the Pt(II) ion containing dendrimers was higher than that of the Pt(IV) ion containing dendrimers.

Simulasi Docking Senyawa Aktif Daun Binahong Sebagai Inhibitor Enzyme Aldose Reductase

The metabolic syndrome is the cause of death around the world caused by diabetic mellitus. Binahong leaf is a kind of plant that is widely used to treat various diseases. This study aims to investigate the inhibitory activity of binahong leaves compound in inhibiting the aldose reductase which has role of converting glucose into sorbitol by docking simulation. The compound of binahong leaves consists of ursolic acid, vitexin, and oleonolic acid (ligand testing). These compound were taken from PubChem site, while aldose reductase enzyme (receptor) was obtained from the world protein bank with PDB 2HV5 code. This study incorporated in silica technique by using Auto dock vina software, Discovery Studio and Ligplot as visualization. The result of grid box optimization by redocking comparative ligand was 0.7Å RMSD. The docking result showed that the free Gibbs energy (∆G) of aldose reductase was (-11.7), Vitexin (-8.3), Ursolic acid (-7.7) and Oleonolic acid (-8.6). These value suggested that there was a stable inhibition reaction from the binahong leaves compound and the comparative ligand. Based on the Lipinski Rule, the composition of binahong leaves compound meets the Lipinski Rule criteria which means this medicine can be used orally except for vitexin and comparative ligands of zopolrestate which exceed the number of the atom.

Kallikrein-related peptidase 14 is the second KLK protease targeted by the serpin vaspin

Kallikrein-related peptidases KLK5, KLK7 and KLK14 are important proteases in skin desquamation and aberrant KLK activity is associated with inflammatory skin diseases such as Netherton syndrome but also with various serious forms of cancer. Previously, we have identified KLK7 as the first protease target of vaspin (Serpin A12). Here, we report KLK14 as a second KLK protease to be inhibited by vaspin. In conclusion, vaspin represents a multi-specific serpin targeting the kallikrein proteases KLK7 and KLK14, with distinct exosites regulating recognition of these target proteases and opposing effects of heparin binding on the inhibition reaction.