Magnetic properties of the low-dimensional spin-1/2 magnet \alpha-Cu_2As_2O_7

In this work we study the interplay between the crystal structure and magnetism of the pyroarsenate \alpha-Cu_2As_2O_7 by means of magnetization, heat capacity, electron spin resonance and nuclear magnetic resonance measurements as well as density functional theory (DFT) calculations and quantum Monte Carlo (QMC) simulations. The data reveal that the magnetic Cu-O chains in the crystal structure represent a realization of a quasi-one dimensional (1D) coupled alternating spin-1/2 Heisenberg chain model with relevant pathways through non-magnetic AsO_4 tetrahedra. Owing to residual 3D interactions antiferromagnetic long range ordering at T_N\simeq10K takes place. Application of external magnetic field B along the magnetically easy axis induces the transition to a spin-flop phase at B_{SF}~1.7T (2K). The experimental data suggest that substantial quantum spin fluctuations take place at low magnetic fields in the ordered state. DFT calculations confirm the quasi-one-dimensional nature of the spin lattice, with the leading coupling J_1 within the structural dimers. QMC fits to the magnetic susceptibility evaluate J_1=164K, the weaker intrachain coupling J'_1/J_1 = 0.55, and the effective interchain coupling J_{ic1}/J_1 = 0.20.Comment: Accepted for publication in Physical Review

Researches of air and fuel rate influence on oxygen level in emissions of new type medium power coal boiler

The article deals with sustained fire coal boilers requirements engineering from a creating energy saving and ecological compatibility point of view. The article gives experimental data obtained on boilers which was made by LLP "Карплаз", Karaganda, Republic of Kazakhstan

LEDs based upon AlGaInP heterostructures with multiple quantum wells: comparison of fast neutrons and gammaquanta irradiation

The paper presents the research results of watt and volt characteristics of LEDs based upon AlGaInP heterostructures with multiple quantum wells in the active region. The research is completed for LEDs (emission wavelengths 624 nm and 590 nm) under irradiation by fast neutron and gamma-quanta in passive powering mode. Watt-voltage characteristics in the average and high electron injection areas are described as a power function of the operating voltage. It has been revealed that the LEDs transition from average electron injection area to high electron injection area occurs by overcoming the transition area. It disappears as it get closer to the limit result of the irradiation LEDs that is low electron injection mode in the entire supply voltage range. It has been established that the gamma radiation facilitates initial defects restructuring only 42% compared to 100% when irradiation is performed by fast neutrons. Ratio between measured on the boundary between low and average electron injection areas current value and the contribution magnitude of the first stage LEDs emissive power reducing is established. It is allows to predict LEDs resistance to irradiation by fast neutrons and gamma rays

Experimental Study of the Efficacy and Safety of a New PEG-Based Laxative

Bowel-cleansing PEG-based agents, including Moviprep®, are commonly used to prepare the large intestine for diagnostic examinations. PLNV-next is a newly developed fixed combination medicinal product with a composition similar to that of Moviprep®.The aim of the study was to estimate the pharmacological efficacy and toxicity of PLNV-next.Materials and methods: The study evaluated pharmacological efficacy of four formulations of PLNV-next in comparison with Moviprep® after a single administration in a therapeutic dose to outbred rats. The evaluation was carried out based on the laxative effect of the medicinal products. The authors recorded diarrhoea onset latency and the number of defecation boluses and diarrhoea spots produced during the 6-hour observation period. Toxicity of PLNV-next was studied in the formulation containing maximum amounts of the ingredients according to the patent. In the single-dose toxicity study, PLNV-next was administered intragastrically to rats at doses of 4.2 g/kg (maximum human therapeutic dose, MHTD), 21 g/kg (5 MHTD), and 42 g/kg (10 MHTD) and to ferrets at doses of 4.2 g/kg (MHTD) and 21 g/kg (5 MHTD). In the repeated-dose toxicity study, PLNV-next was administered for 14 days at 4.2 g/kg (rats and ferrets), 21 g/kg (5 MHTD, rats), and 12.6 g/kg (3 MHTD, ferrets). Additionally, the repeated-dose toxicity study evaluated safety pharmacology parameters for the cardio-vascular, respiratory and central nervous systems.Results: All PLNV-next formulations tested exerted a laxative effect equivalent to that of Moviprep®. No clinical signs of toxicity were observed in rats, with the exception of the laxative effect. Ferrets demonstrated decreased behavioral activity and diarrhoea. Nausea or emesis were noted in 75–90% of the ferrets receiving the doses exceeding the MHTD. A single administration of PLNV-next affected blood sodium concentrations: a slight increase was noted in the 5 MHTD and 10 MHTD groups of rats and in the 5 MHTD group of ferrets. The repeated-dose toxicity study in rats revealed a slight increase in sodium levels with both test doses. After a single administration of 5 MHTD to ferrets, the authors observed a decrease in potassium levels. All the changes were mild and within physiological ranges. PLNV-next toxic effects observed in the rat and ferret studies were similar to those reported in rat and dog toxicity studies of Moviprep®. Conclusion: PLNV-next exerts a marked laxative effect and has a favourable safety profile

Coordination of NK cell markers expression and IgG response in hCMV infection

Human cytomegalovirus (hCMV) is a prevalent virus that affects a large proportion of the population worldwide. Natural Killer (NK) cells are essential immune cells that play a crucial role in controlling hCMV infection. Despite the wide spread of hCMV infection, there is still not enough data related to the association between innate and adaptive immunity. This study investigated the coordination between some of the NK cell markers expression and humoral immune response during hCMV infection. Thirty-three samples obtained from different healthy donors were investigated. The anti-hCMV IgG antibody titer was measured in serum samples, and expression of NKG2C, HLA-DR, CD57, KIR2DL2/DL3, and KIR2DL1 were analyzed in CD56+CD3- cells in PBMC samples by flow cytometry. To evaluate the dependence of proportions of different NK cell subsets on IgG titers, cluster analysis was first performed on all the obtained data, resulting in the identification of four main clusters. The identified clusters demonstrated a dependence on the levels of hCMV antibodies, according to which clusters corresponding to seronegative and low-positive were grouped. The results confirmed that hCMV infection leads to an expansion of NK cell populations expressing the NKG2C marker, which correlates with higher levels of IgG response to hCMV. Besides, we identified increased HLA-DR+ and decreased of KIR2DL1+ NK cells proportions in the middle anti-CMV-IgG level group compared to samples obtained from seronegative and low-positive donors. Moreover, the statistically significant negative correlation was found between KIR2DL1+NK cell percentage and anti-CMV IgG antibody titer, while the positive correlation between HLA-DR+NK cell proportion and the IgG level was noticed only without the cluster corresponded to high level of anti-hCMV IgG. In this cohort, we did not find any association between KIR2DL3 and CD57 expression in NK cells and levels of IgG response to hCMV. This may indicate that different subsets of NK cells may have distinct roles in regulating humoral immunity to hCMV. Overall, the results of the study provide valuable insights into the coordination of NK cell marker expression and IgG response in hCMV infection

Comparative Preclinical Evaluation of the Safety, Antifungal Activity, and Pharmacokinetics of Sertaconazole Products for External Use

The high prevalence of fungal skin infections motivates expanding the range of sertaconazole products for external use.The aim of the study was a preclinical comparison of the safety, antifungal activity, and pharmacokinetics of Sertaverin® 2% medicated shampoo (VERTEX JSC, Russia) with those of Sertamicol® 2% solution for external use (Glenmark Pharmaceuticals Ltd, India) and Nizoral® 2% shampoo (Janssen Pharmaceuticals N.V., Belgium) approved in the Russian Federation.Materials and methods. In the toxicity study, the medicinal products were applied to the skin of male and female outbred rats at doses of 0.5 or 1.5 mL/animal for 28 days. The authors evaluated the pharmacokinetics of two sertaconazole formulations (shampoo and solution) following a single administration to adult male rats at the same dose. Nizoral® was not used in the pharmacokinetics study because it contains a different active substance, ketoconazole. The minimum inhibitory concentration (MIC) was determined using the serial microdilution method in a wide range of concentrations.Results. The medicinal products did not exhibit any significant toxic effects in laboratory animals after 28 days of repeated dermal application. Plasma sertaconazole concentrations were negligible. Sertaconazole was intensively distributed in the liver, which is a highly vascularised organ, and in the target organ (skin at the site of application). The relative bioavailability of sertaconazole from the shampoo relative to that from the solution for external use was approximately 30% in liver tissues and approximately 363% in skin tissues at the application site. Sertaverin® was comparable to sertaconazole in the active substance form in terms of inhibiting the growth of Malassezia furfur strains. The MICs calculated on the active substance basis were ≤16–64 μg/mL.Conclusions. With its synergistic dual mechanism of action, broad-spectrum antifungal activity, lipophilic properties, and low systemic absorption, Sertaverin® may provide a more effective and safe alternative to marketed medicinal products for scalp diseases

АПРОБАЦИЯ МЕТОДА ОЦЕНКИ ФОТОТОКСИЧЕСКИХ ЭФФЕКТОВ ЛЕКАРСТВЕННЫХ ПРЕПАРАТОВ В УСЛОВИЯХ IN VIVO

At present all new medicinal products and cosmetics that absorb medium-wavelength UVB, long-wavelength UVA, or visible light in the range 290–700 nm need to be tested for potential phototoxicity. phototoxicity is evaluated by both in vitro and in vivo methods. There are guidelines for in vitro phototoxicity evaluation, however, there are no formally validated protocols for in vivo phototoxicity evaluation. The purpose of this study was to test an economically viable and informative method for in vivo evaluation of tetracycline and ketorolac phototoxicity using outbred rats. Two medicinal products potentially capable of causing clinically established phototoxic reactions were used in this study: tetracycline (tablets, 200 mg/kg and 300 mg/kg) and ketorolac (gel, 13.4 mg/kg, 26.8 mg/kg and 40.3 mg/kg). The medicines were administered in both single and multiple doses. Ultraviolet irradiator OUFK-03 (OOO «Solnyshko», Russia) was used as a light source. The UV exposure (5 J/cm2 and 15 J/cm2) was performed once 1 h after medicine administration. The skin reaction was evaluated 30 minutes and 24 hours after irradiation and then daily for 2 weeks. As a result, the following optimal parameters were determined for in vivo evaluation of phototoxic reactions caused by the medicines: radiation intensity — 15 J/cm2 for single systemic administration and 5 J/cm2 for single topical (dermal) administration; recommended period of skin reaction evaluation for outbred rats is not less than 7 days.Фототоксическое действие должно быть оценено для всех лекарственных и косметических средств, которые поглощают средний (UVB), длинноволновой (UVA) или видимый свет в диапазоне от 290 до 700 нм. Для оценки фототоксичности применяют как in vitro, так и in vivo методы. Для исследований in vitro разработаны рекомендации, но для исследований in vivo на сегодняшний день каких-либо общепринятых протоколов не существует. Цель работы состояла в апробации экономически целесообразного и информативного метода для оценки фототоксичности препаратов тетрациклина, кеторолака в условиях in vivo с использованием аутбредных крыс. При разработке протокола использовали лекарственные препараты, потенциально способные вызывать фототоксические реакции при клиническом применении: тетрациклин (таблетки, 200 и 300 мг/кг) и кеторолак (гель, 13,4, 26,8 и 40,3 мг/кг). Препараты применяли как однократно, так и многократно. Для УФ-экспозиции использовали облучатель ультрафиолетовый ОУФК-03  (ООО «Солнышко», Россия). Облучение (5 и 15 Дж/см2) проводили однократно через 1 ч после введения/нанесения препарата. Кожную реакцию оценивали через 30 мин, 24 ч после облучения и далее ежедневно на протяжении двух недель. Установлены оптимальные параметры, позволяющие оценивать фототоксические реакции лекарственных препаратов in vivo: интенсивность излучения при однократном системном введении составляет 15 Дж/см2, при однократном местном применении (накожном) — 5 Дж/см2; продолжительность наблюдения для оценки кожной реакции на аутбредных крысах не менее семи суток

АНТИАГРЕГАНТНАЯ ТЕРАПИЯ В ПРОФИЛАКТИКЕ НАРУШЕНИЙ МОЗГОВОГО КРОВООБРАЩЕНИЯ

Currently the problem of preventing cerebrovascular disorders, in which antiplatelet therapy takes one of the leading places, remains relevant. The efficiency of the therapy depends on a large number of modifiable and non-modifiable factors. There are many methods to assess the severity of the response to antiplatelet therapy, but there is no common approach to the assessment of the results and their prognostic significance. Further studies of this issue are essential with the aim of individualization of antiplatelet therapy thereby increasing its efficiency and safety.В настоящее время сохраняется проблема профилактики нарушений мозгового кровообращения, в которой антиагрегант­ ная терапия занимает одно из ведущих мест. Эффективность данной терапии зависит от большого числа модифицируемых и не модифицируемых факторов. Существует множество методов оценки ответа на антиагрегантную терапию, но нет единого подхода к оценке получаемых результатов и их прогностической значимости. Необходимы дальнейшие исследования данного вопроса с целью индивидуализации антиагрегантной терапии и, тем самым, повышения ее эффективности и безопасности