Влияние способа сильного легирования на композиционную однородность и оптические свойства монокристаллов LiNbO-=SUB=-3-=/SUB=- : Mg

Raman spectroscopy, laser conoscopy and photoinduced light scattering methods have been applied to comparatively study composition uniformity of strongly doped LiNbO3 crystals with a magnesium concentration close to a threshold value ≈5 mol% MgО, grown from a charge synthesized using precursor Nb2O5:Mg (homogeneous doping method) and at direct addition of magnesium to the melt (direct doping method). It has been shown that application of homogeneous doping method allows one to obtain compositionally more homogeneous heavily doped LiNbO3:Mg crystal than direct melt doping method.

INFLUENCE OF THE METHOD OF DOPING ON UNIFORMITY AND OPTICAL PROPERTIES OF LiNbO:Mg CRYSTALS

Представлены результаты сравнительных комплексных исследований методами спектроскопии комбинационного рассеяния света и лазерной коноскопии композиционной однородности и некоторых оптических свойства близких по составу сильно легированных монодоменизированных кристаллов LiNbO: Mg (5,03 мол. % MgO и LiNbO: Mg (4,75 мол. % MgO), с концентрацией магния, близкой к пороговому значению ≈ 5 мол. % MgO, выращенных из шихты, синтезированной с использованием прекурсора NbO : Mg (метод гомогенного легирования), а также выращенных при непосредственном добавлении магния в расплав (метод прямого легирования). Показано, что методом гомогенного легирования с использованием прекурсора NbO : Mg можно получать отличающиеся низким коэрцитивным полем более композиционно однородные сильно легированные монокристаллы LiNbO : Mg, чем методом прямого легирования расплава магнием. При этом более однородное распределение легирующей добавки в кристаллах гомогенного легирования начинает формироваться уже на стадии синтеза прекурсора NbO : Mg и шихты ниобата лития при формировании химически активных комплексов, определяющих преимущественно кислородно-октаэдрическую структуру прекурсора NbO : Mg. The paper considers results for strongly doped turned to a single domain state crystals LiNbO: Mg (5,03 mol % MgO and LiNbO: Mg (4,75 mol % MgO). Magnesium concentration in these crystals is close to each other and to threshold ≈ 5 mol % MgO . Crystals were grown from a charge synthesized using precursor LiNbO: Mg (homogeneous doping method) and from a charge obtained at a direct addition of magnesium to the charge (direct doping method). Complex studies were carried out by Raman spectroscopy and laser conoscopy. Compositional homogeneity and some optical properties of studied crystals are considered. Homogeneous doping with precursor NbO: Mg method allows us to obtain heavily doped LiNbO: Mg single crystals with low coercive field and more compositionally homogeneous than method of direct melt doping with magnesium. In this case, a more uniform distribution of the dopant in homogeneously doped crystals begins to form at the stage of NbO: Mg precursor synthesis during the formation of chemically active complexes that predominantly determine the oxygen-octahedral structure of the NbO: Mg precursor.

Environmental safety monitoring of heavy metals accumulation in some species of Sambucus L.

The aim in this work was to monitor heavy metals in plants of elderberry species. The objective of the research was to identify the actual concentrations of heavy metals in the fruits and leaves of the studied elderberry species. The need to determine deviations in the content of heavy metals in various parts of plants arose because the current ecological situation in Belgorod’s area requires special attention. The presence and concentration of heavy metals in different elderberry species and different parts of plants vary greatly and have the following features. Increased magnesium content was observed in almost all elderberry species, especially in red-fruited (Sambucus racemosa ‘Aurea’, S. sibirica Nakai, S. racemosa L., S. racemosa ‘Plumosa’, S. coreana Nakai), And its concentration much higher in fruits than in leaves. The highest deviation of the magnesium content from the norm was noted in the fruits and leaves of S. sibirica (2 and 1.5 times, respectively). Black elderberry species (S. nigra L., S. canadensis L., S. canadensis ‘Plumosa’) have a lower magnesium concentration in fruits and leaves. On the other hand, the concentration of copper in fruits and leaves in elderberry species is many times higher than the norm.

Association between magnesium in drinking water and atrial fibrillation incidence: a nationwide population-based cohort study, 2002–2015

Background Atrial fibrillation (AF) is a common heart rhythm disorder and a risk factor of adverse cardiovascular diseases. Established causes do not fully explain the risk of AF and unexplained risk factors might be related to the environment, e.g. magnesium in drinking water. Low magnesium levels in drinking water might be associated with higher risk of cardiovascular diseases including AF. With detailed individual data from nationwide registries and long-term magnesium exposure time series, we had a unique opportunity to investigate the association between magnesium in drinking water and AF. Objective We evaluated the association between magnesium concentration in drinking water and AF risk. Methods A nationwide register-based cohort study (2002–2015) was used including individuals aged ≥30 years. Addresses were linked with water supply areas (n = 2418) to obtain time-varying drinking water magnesium exposure at each address. Five exposure groups were defined based on a 5-year rolling time-weighted average magnesium concentration. AF incidence rate ratios (IRRs) between exposure groups were calculated using a Poisson regression of incidence rates, adjusted for sex, age, and socioeconomic position. Robustness of results was investigated with different exposure definitions. Results The study included 4,264,809 individuals (44,731,694 person-years) whereof 222,998 experienced an incident AF. Magnesium exposure ranged from 0.5 to 62.0 mg/L (mean = 13.9 mg/L). Estimated IRR (95% CI) compared to the referent exposure group (< 5 mg/L) was 0.98 (0.97–1.00) for the second lowest exposure group (5–10 mg/L), and 1.07 (1.05–1.08) for the two highest exposure groups (15–62 mg/L). Strongest positive associations were observed among those aged ≥80 years and with lowest education group. An inverse association was found among individuals with highest education group. Conclusion There might be a small beneficial effect on AF of an increase in magnesium level in drinking water up to 10 mg/L, though an overall positive association was observed. The unexpected positive association and different associations observed for subgroups suggest a potential influence of unaccounted factors, particularly in vulnerable populations. Future research on magnesium in drinking water and cardiovascular diseases needs to focus on contextual risk factors, especially those potentially correlating with magnesium in drinking water.

Study of effect of serum magnesium concentration on clinical outcome of critically sick patients in medical intensive care unit

Background: Deficiency of magnesium is common and often ignored. It is associated with cardiac irregularity, cardiac insufficiency, seizure and electrolyte imbalance. As this element has multiple functions in our body it is important in the pathophysiology of several critical illnesses in intensive care unit (ICU). Hence the present study was undertaken to determine the usefulness of admission serum magnesium levels with regards to patient outcome considering mortality, need and duration of ventilator support, and acute physiologic assessment and chronic health evaluation 2 (APACHE 2) score.Methods: Demographic data such as age and sex were recorded. Patients were assessed for presenting complaints, history of other diseases and habits through an interview with the patients or care giver. These findings were recorded on a predesigned proforma patients was followed up for the outcomes such as mortality, need of ventilator support, duration of ICU stay and APACHE 2 score.Results: Regarding comparison between outcome of patients between two groups, 44% patients with magnesium level <1.7 mg/dl have improved and 72% patient didn’t improve. 44% patients with magnesium level >1.7 mg/dl have improved and 28% patient didn’t improve.Conclusions: From present observational study we can conclude that hypomagnesaemia is more common in patients more than 50 years of age and with male predominance. Pneumonia with septicaemia and cerebrovascular accident (CVA) was commonly associated with hypomagnesaemia. In present study we have observed that hypomagnesaemia is associated with high APACHE 2 score, poor outcome and more requirement of ventilatory support.

Effect of Dapagliflozin and Magnesium Supplementation on Renal Magnesium Handling and Magnesium Homeostasis in Metabolic Syndrome

The prevalence of metabolic syndrome (MetS) is increasing, and patients with MetS are at an increased risk of cardiovascular disease and diabetes. There is a close link between hypomagnesemia and MetS. Administration of sodium-glucose transporter 2 (SGLT2) inhibitors has been reported to increase serum magnesium levels in patients with diabetes. We investigated the alterations in renal magnesium handling in an animal model of MetS and analyzed the effects of SGLT2 inhibitors. Adult rats were fed a fructose-rich diet to induce MetS in the first 3 months and were then treated with either dapagliflozin or magnesium sulfate-containing drinking water for another 3 months. Fructose-fed animals had increased insulin resistance, hypomagnesemia, and decreased urinary magnesium excretion. Dapagliflozin treatment improved insulin resistance by decreasing glucose and insulin levels, increased serum magnesium levels, and reduced urinary magnesium excretion. Serum vitamin D and parathyroid hormone levels were decreased in fructose-fed animals, and the levels remained low despite dapagliflozin and magnesium supplementation. In the kidney, claudin-16, TRPM6/7, and FXDY expression was increased in fructose-fed animals. Dapagliflozin increased intracellular magnesium concentration, and this effect was inhibited by TRPM6 blockade and the EGFR antagonist. We concluded that high fructose intake combined with a low-magnesium diet induced MetS and hypomagnesemia. Both dapagliflozin and magnesium sulfate supplementation improved the features of MetS and increased serum magnesium levels. Expression levels of magnesium transporters such as claudin-16, TRPM6/7, and FXYD2 were increased in fructose-fed animals and in those administered dapagliflozin and magnesium sulfate. Dapagliflozin enhances TRPM6-mediated trans-epithelial magnesium transport in renal tubule cells.

Analysis of Step-Velocity-Dependent Concentration of Magnesium in GaN Based on Burton−Cabrera−Frank Theory and Step-Edge Segregation Model

Based on Burton−Cabrera−Frank theory and the step-edge segregation model, we analyzed the reported difference in the sheet concentration of doped magnesium under naturally formed surface stripes on homo-epitaxially grown layers on a freestanding GaN substrate misoriented from a c-plane by 0.3°. By assuming the step height being equal to the peak-to-valley height of the surface stripes, we considered the growth steps on gently and sharply sloped surfaces to be supplied, respectively, from mixed dislocations and the misorientation from the c-plane. The step-velocity dependence of the magnesium concentration was reproduced with the reported magnesium diffusivity of 3×10−14 cm2s−1.

Ionic homeostasis, acid-base balance and the risk of citrate accumulation in patients after cardiovascular surgery treated with continuous veno-venous haemofiltration with post-dilution regional citrate anticoagulation – An observational case-control stud

Background: Patients after cardiovascular surgery, requiring renal replacement therapy, can benefit from adequate non-heparin circuit anticoagulation. Simplified regional citrate anticoagulation (RCA) protocol proposes the use of citric acid dextrose formula A (ACD-A) during post-dilutional continuous veno-venous hemofiltration (CVVH) with standard bicarbonate buffered calcium containing replacement solution. Citrate accumulation diagnosed upon total to ionized calcium ratio (tCa/iCa) and low ionized calcium (iCa) are considered as the biggest risks related to regional citrate accumulation. Methods: This prospective observational case-control study evaluated electrolyte and acid-base homeostasis in cardiovascular surgery patients treated with post-dilution CVVH with a simplified RCA protocol with ACD-A. In total, 50 consecutive cardiovascular surgery patients were evaluated. Base excess, pH, bicarbonate, lactate, Na+, Cl-, Mg++, and inorganic phosphate concentrations, the total to ionized calcium ratio (tCa/iCa), and high anion gap metabolic acidosis were assessed during haemofiltration treatment in survivors and non-survivors. Results: Thirty-three (66%) patients died. The therapies were very well balanced in sodium and chloride homeostasis. The lactate concentration and anion gap decreased during CVVH sessions lasting longer than 72 hours, but no inter-group difference was observed. The tCa/iCa ratio exceeded 4.5% and was significantly higher in non-survivors (p=0.037). Initial lactate concentration did not correlate with tCa/iCa ratio during haemofiltration. Magnesium and phosphate concentrations decreased and additional supplementation with magnesium was necessary. The magnesium concentration was lower in the non-survivors. Conclusions: The incidence of citrate accumulation exceeded 4% and was significantly higher in non-survivors. Supplementation with magnesium and phosphate ions is needed in CVVH with RCA.

Therapeutic Artemether-Lumefantrine Modulated Monosodium Glutamate-Related Adversity on Rats’ Kidney Histology and Antioxidant Response Bio-Indicators

Co-intake-related interactive-synergistic influence of artemether-lumefantrine, AL and monosodium glutamate, MSG that separately mediated oxidative stress could be significant on the kidney actively involved in xenobiotic detoxification and elimination. Thus, influence of AL on rats’ kidney histomorphology and antioxidant bio-indicators following MSG-challenge was assessed. For 7 days, thirty rats (n = 5) were respectively exposed to vehicle (distilled water), therapeutic AL (TAL), high AL (HAL), MSG, MSG plus TAL or MSG plus HAL. Significant (P<0.05) results comparison showed highest and least (P<0.05) albumin concentration (Mg/dl) in TAL-fed (3.76±0.33) and MSG-fed (1.88±0.70), rats. Total protein concentration (Mg/dl) in MSG-fed (4.04±2.04) and HAL-fed (4.76±1.92), rats lowered markedly. Highest glutathione peroxidase activity (IU/L) in TAL-fed (30.74±12.46) lowered in MSG plus HAL-fed (20.11±6.08) and MSG-fed (20.33±4.85), rats. Catalase activity (IU/L) in control was highest (4.89 ± 0.26) but least (2.58 ± 1.06) in MSG-fed rats. Zinc and Magnesium concentration (Mg/dl) was respectively highest (58.99±5.10) and least (3.48±0.31) in MSG plus HAL-fed but least (18.80±7.77) and highest (4.38±1.67) in MSG-fed, rats. Malondialdehyde concentration (µmol/ml) in MSG plus HAL-fed rats (4.04±0.67) was highest (P<0.05) and least (P<0.05) in HAL-fed rats (1.18±0.11). Differences in superoxide dismutase activity (IU/L) were, however, non-significant (P>0.05).Rats’ kidney photomicrographs (H&E × 400) revealed normal histo-architecture in control but varied degree of fibroplasias (TAL- ,HAL- and MSG plus TAL-fed) and necrosis with infiltrations (MSG plus HAL-and MSG-fed), rats. These demonstrated MSG-related adversity and significant modulation response of TAL, unlike HAL, on the rats’ kidney histology and studied antioxidant response bio-indicators.