Electron transport and optical properties of shallow GaAs/InGaAs/GaAs quantum wells with a thin central AlAs barrier

Shallow GaAs/InGaAs/GaAs quantum well structures with and without a three monolayer thick AlAs central barrier have been investigated for different well widths and Si doping levels. The transport parameters are determined by resistivity measurements in the temperature range 4-300 K and magnetotransport in magnetic fields up to 12 T. The (subband) carrier concentrations and mobilities are extracted from the Hall data and Shubnikov-de Haas oscillations. We find that the transport parameters are strongly affected by the insertion of the AlAs central barrier. Photoluminescence spectra, measured at 77 K, show an increase of the transition energies upon insertion of the barrier. The transport and optical data are analyzed with help of self-consistent calculations of the subband structure and envelope wave functions. Insertion of the AlAs central barrier changes the spatial distribution of the electron wave functions and leads to the formation of hybrid states, i.e. states which extend over the InGaAs and the delta-doped layer quantum wells.Comment: 14 pages, pdf fil

Morphological changes of the gastric mucosa in patients with duodenogasric reflux: relationship with acidity and helicobacter pylori

Purpose: to reveal the peculiarities of the duodenogastric reflux (DGR) impact on acidity and morphological features of the gastric mucosa in patients with "primary" reflux gastritis, as well as in cases of reflux gastritis in combination with H. pylori. Methods: 66 patients with chronic reflux gastritis were examined, 15 people formed a control group. All patients had gastric endoscopy with determination of the gastric acidity and concentration of bile acids. Biopsy material for histological examination was obtained from 55 patients, in 12 cases of suspected intestinal metaplasia additional histochemical (PAS and alcian blue) and immunohistochemical (cytokeratin 20, Villin, carcinoembriogenic antigen, MUC2, CD45) assays were performed. Results: the level of acidity in patients with DGR was higher (pH = 3.55 ± 2.3) compared to the control group (pH = 6.85 ± 1.34). Cases of DGR differed from the control group regarding the mononuclear infiltration (p=0,001), foveolar hyperplasia (p=0,001) in both antral and fundic parts of the stomach, mucosal edema (p=0,022) and atrophy (p=0,02) at the level of the antrum, and intestinal metaplasia (p=0,022) at the level of the body. In the presence of H. pylori infection, in addition to the abovementioned signs, infiltration by cells of acute inflammation (p = 0.005) was detected, which indicates an increase in the damaging effect of H. pylori infection in DGR. Conclusion: DGR may lead to "oxidation" of gastric contents. The effect of DGR leads to intestinal metaplasia of the body and atrophy of the antral part of stomach, chronic inflammation and foveolar hyperplasia. The presence of H. pylori boosts the morphological changes in the gastric mucosa caused by DGR.Цель: выявить характер воздействия дуоденогастрального рефлюкса (ДГР) на морфологические показатели слизистой оболочки желудка при «первичном» рефлюкс-гастрите, в том числе, в сочетании с H.pylori, исследовать связь ДГР с уровнем кислотности. Материалы и методы: обследовано 66 пациентов с рефлюкс-гастритом, 15 человек составили группу контроля. Всем пациентам проведена эзофагогастродуоденоскопия с определением кислотности и концентрации желчных кислот в желудочном содержимом. 55 пациентам проведено гистологическое обследование биопсийного материала слизистой оболочки желудка, при наличии признаков кишечной метаплазии 12 пациентам проведено дополнительное гистохимическое (окраска Шифф-йодной кислотой и альциановым синим) и иммуногистохимическое (определение экспрессии цитокератина 20, виллина, MUC2, ракового эмбрионального антигена, CD45) исследование. результаты: Уровень кислотности у пациентов с ДГР был выше (рН=3,55±2,3) по сравнению с группой контроля (рН=6,85±1,34). Из морфологических признаков при дГр значимо отличались от группы контроля мононуклеарная инфильтрация (р=0,001), фовеолярная гиперплазия (р=0,001) в обоих отделах желудка, отек (р=0,022) и атрофия (р=0,02) антрального отдела, кишечная метаплазия (р=0,022) на уровне тела желудка. При наличии инфекции H. pylori, помимо уже выявленных признаков, выявляется инфильтрация клетками острого воспаления (р=0,005), что свидетельствует об усилении повреждающего действия инфекции H. pylori при ДГР. Выводы: Воздействие ДГР приводит к «окислению» желудочного содержимого. Воздействие ДГР приводит к кишечной метаплазии тела и атрофии антрального отдела желудка на фоне хронического воспаления и фовеолярной гиперплазии. Присутствие H. pylori усиливает вызванные ДГР морфологические изменения слизистой оболочки желудка

Effect of the combined action of Quercus cortex extract and probiotic substances on the immunity and productivity of broiler chickens

Aim: This study was designed to investigate the synergistic effect of the combined action of probiotic bacterial strains (Bifidobacterium adolescentis and Lactobacillus acidophilus) and Quercus cortex extract as biologically active substances in the feed on the immunity and productivity of Gallus gallus domesticus. Materials and Methods: For the experiment, 120 7-day-old broiler chickens were selected (4 groups, n=30, 3 replicates with 10 birds in each group). The groups were as follows: The reference group - basic diet (BD); experimental Group I - BD + Q. cortex extract (Q. cortex), 2.5 ml/kg of body weight; experimental Group II - BD + probiotic preparation based on B. adolescentis, 80.0 million colony-forming units (CFU), and L. acidophilus, 1.0 million CFU (dosage in accordance with the recommendations of the manufacturer); and experimental Group III - BD + probiotic + extract of Q. cortex. The following methods of study were used: Chemiluminescence and biochemical and hematological analysis. Results: The results of the experiment showed a slight decrease in the level of leukocytes in Groups II (p≤0.05) and III, and of hemoglobin in Group III (p≤0.05), compared to the reference group. The level of alanine aminotransferase and aspartate aminotransferase in Group II was higher than both the reference group (p≤0.05) and the other groups. Introduction of Q. cortex extract into the diet increased the level of triglycerides (p≤0.05) and urea in the blood serum. The combined use of probiotic preparations and the extract resulted in an increase in the level of iron in the blood serum by 78.1% (p≤0.05) in Group III. An increase in indicators of the antioxidant system (catalase increased in Group I by 27.2% (p≤0.05) and by 3.0-12.7% in other groups; superoxide dismutase increased by 3.0-13.2%) and nonspecific immunity (β-lysine increased by 8.8-16.0%) was noted. Introduction of the extract and probiotic preparation into the diet contributed to increasing the live weight of chickens at the age of 15 days by 5.9 and 7.4%, respectively (p≤0.05). In experimental Group II, this trend continued, and by the end of the period, the weight of animals exceeded that of their peers in other groups by 0.7-7.0%. Given the high preservation rate of poultry in the II and III Groups, and the low feed consumption per 1 kg of live weight gain (by 3.1-6.7%), the efficiency of growth was higher than in the reference group. Conclusion: Thus, the combined use of probiotic strains of bacteria and Q. cortex extract helped to increase the antioxidant activity of the organism and antimicrobial components of blood plasma compared with broiler chickens with similar growth rates but without the supplementation of this combination