Влияние условий осаждения из паров металлоорганических соединений на получение эпитаксиальных слоев n-CdTe с использованием изопропилиодида

The dependence of iodine incorporation in CdTe layers on the deposition conditions during metalorganic vapor phase epitaxy is investigated. The growth of the layers was carried out from dimethylcadmium and diethyltellurium in the hydrogen flow in a vertical reactor with a hot wall condition at a total pressure of 20 kPa. The total iodine concentration was determined by secondary ion mass spectrometry, the electrically active concentration was determined from the Hall effect measurement. The iodine incorporation depends on the crystallographic orientation of the substrate (were studied (100), (310), (111)A, (111)B, (211)A and (211)B), the concentration of the doping precursor (flux range 5·10–8–3·10–6 mol/min), the mole ratio of organometallic compounds (DMCd/DETe=0.25–4), growth temperature (335–390°C) and the walls of the reactor above the pedestal (hot wall zone 290–320°C). The total iodine concentration reached 5·1018 cm–3 and the activation efficiency was ~4 %. After thermal annealing in cadmium vapor at 500°C the activation efficiency was ~100 %.

Leaf extracts as green substitute to toxic zinc chromate and zinc phosphate additives in Polyurethane primers for corrosion inhibition of steel

Corrosion inhibition of steel by Polyurethane Extract-primer (PEP) containing plant leaf extracts was compared with Polyurethane Conventional primer (PCP) containing zinc phosphate and zinc chromate as inhibitors. The primers were investigated using gasometric technique in 5 °C steps of temperature increase from 25 to 50 °C in 1.0 M HCl as corrodent. The PEP of 34.24 percent actives compared with PCP of 56.35 percent actives gave the same inhibition efficiencies of 82.4%. Extract primers of low percent active concentration were more effective and less expensive than that of conventional primers.

Human Recombinant Leptin Shows Dose and Time-Dependent Release of Nitric Oxide from Endothelial Nitric Oxide Synthase in Endothelium While on Angiogenesis

Nitric Oxide (NO) modulates various assortments of the angiogenic process. The endogenous hormone leptin is able to induce different physiological process such as angiogenesis at low concentration because of its high receptor specific affinity. Various studies speculated leptin’s ability to induce endothelium‐dependent vascular relaxation by stimulating NO through different signaling pathways. So far, no studies have reported the dose and time dependent potential of human recombinant leptin on NO release. Hence, an attempt has been made to understand the optimal concentration and time of incubation of human recombinant leptin for the enzymatic release of NO from endothelial Nitric Oxide Synthase (eNOS). Leptin induced changes in the localization and phosphorylation pattern of eNOS in cultured endothelium under various concentrations and time of incubation is studied. The 5 Nanomolar concentration of human recombinant leptin within 6 minutes of incubation could induce significant levels of NO from the activated eNOS in cultured endothelium through plasma membrane localization and phosphorylation of eNOS. Our findings suggest that human recombinant leptin can modulate NO-dependent new therapeutic avenue for angiogenesis-related disorders such as wound healing if used within the active concentration and time of incubation.

System Suitability Testing of the Method Developed to Measure the Active Concentration of a Fab Fragment Via Surface Plasmon Resonance

SPR methods are increasingly accepted by the biopharmaceutical industry in quality control (QC), R&D and clinical research. However, there are few reports on method validation and system suitability testing (SST), in particular on concentration determination methods related to the potency of the drug. System compliance must be demonstrated with certain tests in order, for the method validation to be ensured, as agreed by the scientific community and the industry, and specified in the guidelines. To contribute to the alleviation of the deficiency in this matter, we developed a system suitability testing of an SPR-based active concentration measurement method using Fab-fragment as a model. High amounts of anti-FAB1 were captured onto sensor chip surfaces via biotin/neutravidin interaction. The unknown concentration of FAB1 measured via calibration curve dependent concentration measurement. Controls were run between unknown samples to check the reliability of the method. The standard four-parameter logistic equation was used to determine the unknown concentration. CV % of samples and Difference % of controls form standards were calculated from obtained data. The CV % and Diff. % values were less than or equal to 10 % at each parameter. The 100 % level of unknown sample measured as 105 %. Obtained CV % values and repeated analyses showed that the system and method are suitable for the concentration analysis of the FAB1 fragment. The system suitability parameters evaluated in the study can be applied for all SPR analyzes. Resumen. Los métodos SPR (Surface Plamon Resonance) son cada vez más aceptados por la industria biofarmacéutica en el control de calidad (QC), investigación y desarrollo (R & D) e investigación clínica. Sin embargo, existen pocos informes sobre la validación de los métodos y las pruebas de idoneidad del sistema (SST), en particular sobre los métodos de determinación de la concentración relacionados con la potencia del fármaco. La idoneidad del sistema debe demostrarse para garantizar la validación del método, según la normatividad acordada por la comunidad científica y la industria. Con el fin de contribuir al alivio de la deficiencia en este asunto, se desarrolló una prueba de idoneidad del sistema con un método de medición de concentración activa basado en SPR utilizando el fragmento Fab como modelo. Se capturaron grandes cantidades de anti-FAB1 en las superficies del chip sensor mediante la interacción biotina/neutravidina. Se estableció la concentración desconocida de FAB1 a través de la determinación de la concentración dependiente de la curva de calibración. Se ejecutaron controles entre muestras desconocidas para comprobar la fiabilidad del método. Se utilizó una ecuación estándar de cuatro parámetros para determinar la concentración desconocida. A partir de los datos obtenidos se determinó el porcentaje de CV de las muestras y la diferencia respecto a los controles. Los valores de % CV y % Diff. fueron menores o iguales al 10 % en cada parámetro. Los valores de % CV obtenidos y los análisis repetidos mostraron que el sistema y el método son adecuados para el análisis de concentración del fragmento FAB1. Los parámetros de idoneidad del sistema evaluados en el estudio se pueden aplicar a todos los análisis SPR.

Lichen Polyphenolic Compounds for the Eradication of Candida albicans Biofilms

Lichens, due to their symbiotic nature (association between fungi and algae), constitute a chemical factory of original compounds. Polyphenolic compounds (depsides and depsidones) are the main constituents of lichens and are exclusively biosynthesized by these organisms. A panel of 11 polyphenols was evaluated for their anti-biofilm activity against Candida albicans biofilms on the maturation phase (anti-maturation) (MMIC50) as well as on preformed 24-h-old biofilm (anti-biofilm) (MBIC50) using the XTT assay. Minimum inhibitory concentrations of compounds (MICs) against C. albicans planktonic yeast were also determined using a broth microdilution method. While none of the tested compounds were active against planktonic cells (IC50 > 100 µg/ml), three depsides slowed the biofilm maturation (MMIC50 ≤12.5 µg/ml after 48 h of contact with Candida cells). Evernic acid was able to both slow the maturation and reduce the already formed biofilms with MBIC50 ≤12.5 µg/ml after 48 h of contact with the biofilm. This compound shows a weak toxicity against HeLa cells (22%) at the minimal active concentration and no hemolytic activity at 100 µg/ml. Microscopic observations of evernic acid and optimization of its solubility were performed to further study this compound. This work confirmed the anti-biofilm potential of depsides, especially evernic acid, and allows to establish the structure–activity relationships to better explain the anti-biofilm potential of these compounds.

Chitosan Pesticides for Control Aphids (Aphis craccivora) on High Population in Long Bean (Vigna sesquipedalis) Cultivation

Pesticides with chitosan as an alternative are still relevant for aphids which are important pesticides in vegetable crops. This research was conducted to see the effect of several types of pesticides with chitosan active ingredients, the concentration of pesticides, and interactions between types of pesticides and concentrations of aphids on long bean plants. The study used factorial methods with randomized block designs. The first factor was the type of pesticide made from chitosan, which consisted of control (JO), pure chitosan (Jl), soft guard (J2), super biovit (13). The second factor was the concentration of pesticides that consisted of 0.1% (Kl), 0.3% (K2), and 1% (K3). There were 48 experimental units consisting of 12 treatment combinations and 4 replications. Data were analysed using Analysis of variance (ANOVA), and comparison between averages using Duncan Multiple Range Test (DMRT). The results showed the effect of the treatment was single or there was no interaction between the types of pesticides made from chitosan with an active concentration in all parameters of observation. Furthermore, the effect of the type of pesticide with active chitosan was significantly different only on the average aphid population I and 3 days after the first application. Whereas pesticides made from active chitosan soft guard type tended to control the aphid population higher than other types of pesticides, then the effect of pesticide concentration was not significantly different from all parameters. However, the concentration of 1% indicated to inhibit the population of aphids higher than other concentrations. The high early aphid population, the behaviour of aphid colonies, the application method, and the nature of the active ingredient of chitosan were thought to be factors that reduce the ability of pesticides to control aphids on long bean plants.

Determination of Intraprostatic and Intratesticular Androgens

Androgens represent the main hormones responsible for maintaining hormonal balance and function in the prostate and testis. As they are involved in prostate and testicular carcinogenesis, more detailed information of their active concentration at the site of action is required. Since the introduction of the term intracrinology as the local formation of active steroid hormones from inactive precursors of the adrenal gland, mainly dehydroepiandrosterone (DHEA) and DHEA-S, it is evident that blood circulating levels of sex steroid hormones need not reflect their actual concentrations in the tissue. Here, we review and critically evaluate available methods for the analysis of human intraprostatic and intratesticular steroid concentrations. Since analytical approaches have much in common in both tissues, we discuss them together. Preanalytical steps, including various techniques for separation of the analytes, are compared, followed by the end-point measurement. Advantages and disadvantages of chromatography-mass spectrometry (LC-MS, GC-MS), immunoanalytical methods (IA), and hybrid (LC-IA) are discussed. Finally, the clinical information value of the determined steroid hormones is evaluated concerning differentiating between patients with cancer or benign hyperplasia and between patients with different degrees of infertility. Adrenal-derived 11-oxygenated androgens are mentioned as perspective prognostic markers for these purposes.

Copper(II) Complexes with Mixed Heterocycle Ligands as Promising Antibacterial and Antitumor Species

Complexes with mixed ligands [Cu(N-N)2(pmtp)](ClO4)2 ((1) N-N: 2,2′-bipyridine; (2) L: 1,10-phenanthroline and pmpt: 5-phenyl-7-methyl-1,2,4-triazolo[1,5-a]pyrimidine) were synthesized and structurally and biologically characterized. Compound (1) crystallizes into space group Pa and (2) in P-1. Both complexes display an intermediate stereochemistry between the two five-coordinated ones. The biological tests indicated that the two compounds exhibited superoxide scavenging capacity, intercalative DNA properties, and metallonuclease activity. Tests on various cell systems indicated that the two complexes neither interfere with the proliferation of Saccharomyces cerevisiae or BJ healthy skin cells, nor cause hemolysis in the active concentration range. Nevertheless, the compounds showed antibacterial potential, with complex (2) being significantly more active than complex (1) against all tested bacterial strains, both in planktonic and biofilm growth state. Both complexes exhibited a very good activity against B16 melanoma cells, with a higher specificity being displayed by compound (1). Taken together, the results indicate that complexes (1) and (2) have specific biological relevance, with potential for the development of antitumor or antimicrobial drugs.

Indomethacin Increases Quercetin Affinity for Human Serum Albumin: A Combined Experimental and Computational Study and Its Broader Implications

Human serum albumin (HSA) is the most abundant carrier protein in the human body. Competition for the same binding site between different ligands can lead to an increased active concentration or a faster elimination of one or both ligands. Indomethacin and quercetin both bind to the binding site located in the IIA subdomain. To determine the nature of the HSA-indomethacin-quercetin interactions, spectrofluorometric, docking, molecular dynamics studies, and quantum chemical calculations were performed. The results show that the indomethacin and quercetin binding sites do not overlap. Moreover, the presence of quercetin does not influence the binding constant and position of indomethacin in the pocket. However, binding of quercetin is much more favorable in the presence of indomethacin, with its position and interactions with HSA significantly changed. These results provide a new insight into drug-drug interactions, which can be important in situations when displacement from HSA or other proteins is undesirable or even desirable. This principle could also be used to deliberately prolong or shorten the xenobiotics’ half-life in the body, depending on the desired outcomes.