Luminescence properties of the Ca-alpha-sialon:Eu solid solution

The Ca,Eu-α-sialon powders with the mixed solid solution composition have been manufactured via the solid-state reaction process in flowing nitrogen in a graphite furnace at a relatively low temperature of 1650 °C without an external overpressure. XRD data with Rielveld refinement and XPS measurements were used for characterization of the lattice constants and the surface chemical composition. The monophase Ca-Eu-α-sialon was obtained with the nominal composition of Eu_0.048Ca_0.702Si_7.75Al_2.25O_0.75N_15.25. The highest emission intensity in a yellow-orange region at 590 nm and quantum efficiency of 66% was found for this pure Ca,Eu-α-sialon. Estimation of m,n values from the lattice constant and EDS results showed a small deviation from the nominal composition of designed α-sialon. XPS results demonstrated significant changes of the chemical composition in the oxidized surface of phosphor particles. Possible reasons of emission redshift and relationship between the actual solid solution composition and luminescence properties are discussed in terms of simultaneous presence of Eu²⁺ and Eu³⁺ ions in the sialon crystal lattice and residual oxynitride glass.     

α钛富氧层增厚动力学模型

为了实现在工业化生产中对α钛富氧层厚度预测和控制,通过实验研究α钛富氧层在高温空气环境中的形成及增厚过程,讨论热处理温度和时间的影响作用,建立高温(750~850℃)空气环境下关于温度、时间的富氧层增厚动力学模型。结果表明:当恒温热处理温度为750~850℃时,α钛富氧层厚度x与保温时间t0.5呈正比例关系,且升高热处理温度可显著提高富氧层增厚速度。在此温度范围内,氧原子的扩散激活能约为203473 J/mol,计算曲线与实验数据吻合性较好。结合文献中已有的扩散系数方程和实验测得的富氧层厚度数据,推导得到5个富氧层增厚动力学方程,其中3个方程的计算曲线与实验数据吻合性较好,可为实际生产中预估富氧层厚度提供理论支持。     

Concentration dependence of hydrogen diffusion in α-iron from atomistic perspectives

Evaluation of hydrogen diffusion in structural materials is essential to predict the leakage and embrittlement of hydrogen storage applications. In this work, we investigate the atomic-scale diffusion of interstitial hydrogen (H) in α-iron (Fe) over a temperature range from 350 to 900 K with different H concentrations (0.01–5%), employing classical molecular dynamics (MD) simulations. The self-diffusivity of H atoms increases with increasing temperature and decreasing concentration. With low concentrations, the calculated diffusion properties agree well with prior experiments. However, with a higher concentration (≥1%), the H diffusivity at low temperatures deviates from a high-temperature Arrhenius behavior. Through the energetic and structural analysis, we suggest that this deviation is attributed to a reduced mobility due to increased energy barrier by other H interstitials. This work contributes to the effective design of H storage applications by identifying temperature and concentration effects on permeability and addressing possible microstructural transformation.     

Extraction optimisation,antioxidant activity and inhibition on α-amylase and pancreatic lipase of polyphenols from the seeds of Syzygium cumini

The objectives of this study were to determine the optimal extraction conditions of polyphenols from Syzygium cumini seeds by response surface methodology and investigate their antioxidant activity and inhibition on α-amylase and pancreatic lipase. As results, the optimal extraction conditions in the ultrasonic extraction process which maximised total polyphenols content, minimised the IC₅₀ values of α-amylase and pancreatic lipase were determined as follows: extraction time 60 min, ethanol concentration 63% and solvent/solid ratio 44 mL g⁻¹. The main phenolic compounds in partially purified fraction of Syzygium cumini seeds were catechin, epicatechin, kaempferol, gallic, 5-caffeoylquinic, caffeic and ferulic acids. In addition, the partially purified fraction inhibited 87.66 ± 5.55 and 86.61 ± 3.15% of α-amylase and pancreatic lipase, respectively. The results suggested that Syzygium cumini seeds could be explored as a natural antioxidant and could be used as a source of highly antidiabetic and anti-obesity bioactive compounds.     

Process Optimization,Physical Properties,and Environmental Stability of an α-Tocopherol Nanocapsule Preparation Using Complex Coacervation Method and Full Factorial Design

α-Tocopherol (α-Toc) has valuable biological activity, but its activity is limited when exposed to environmental factors. Nanocapsules can be used to overcome this problem. Using nanocapsules in the range of 100–200 nm is more beneficial. A 2⁴ full factorial design was carried out to optimize the size of nanocapsules using the complex coacervation method. The four factors were the amount of the wall material, the ratio of core material to wall material, the pH of the solution, and the speed of the homogenizer. The smallest nanocapsules (176 nm) were obtained at a wall content (gelatine and pectin) of 0.8 mg, a percentage of core material (α-Toc) to wall material of 20%, a pH = 4.5, and a homogenizer speed of 12,000 rpm. The encapsulation efficiency was 90.6 ± 1.1%, and the encapsulation yield was 83.4 ± 1.6%. Assessment of the stability of α-Toc after 1 month showed that encapsulation could improve its stability in the presence of three influential factors: humidity, light, and temperature.     

Inhibition of proteases activity in intestine needs a sustainable acidic environment rather than a transient

α-Chymotrypsin (α-CT) and trypsin are important components of the enzymatic barrier. They could degrade the therapeutic proteins and peptides, inhibit their activity consequently, and thereby reduce their oral bioavailability. Acidic agents, as one type of indirect protease inhibitors, have shown proof of concept in clinical trials. We report here the inactivated proteases due to acid influence can be reactivated immediately by environmental pH recovery regardless of how long the inactivation last. To keep the inactivation time of proteases for 4–5?h, we designed and prepared a sustained-release tablet containing citric acid (CA) which can effectively reduce the pH below 5.0 and maintain it for 5?h in the dissolution-reaction medium. The activity of α-CT and trypsin was quantified by analyzing the residual amount of their respective substrates BTEE and TAME. More than 80% of the substrates were survived in 5.0?h of incubation, whereas the common tablet inhibited the proteases activity for only two hours in the same experimental medium. It indicates that the sustained-release tablet loaded with CA can efficiently inhibit the α-CT and trypsin activity longer than the common tablet. The results will be beneficial for designing and formulating the peroral administration of peptide and protein drugs.     

Selenium dioxide reaction of substituted diphenacyl sulfides: generation of α -ketoacids

The attempted selenium dioxide oxidation of substituted diphenacyl sulfides in anticipation of further functionalization led to a series of α -ketoacids 3 via oxidation followed by C?S bond cleavage. Two minor products, 5 and 6, have also been isolated and a mechanistic pathway for the formation of 3, 5 and 6 has been proposed.     

Preparation of luminescent layered zirconium phosphate nanocomposites by the layer-by-layer technique

In the present work, photoactive cation N, N′-Dimenthyl-9, 9’-bisacridinium nitrate (BNMA) was assembled with exfoliated layered α-zirconium phosphate (α-ZrP) via an electrostatic layer-by-layer (LBL) assembly method. As a result, the luminescent films which were well-aligned and periodical had been successfully fabricated. Surprisingly, the lifetimes of (BNMA/ZrP)_n were found to be prolonged by 16-fold for the first time, due to the isolation effect of inorganic nanosheets and hydrogen ion migration between the interlayers. Therefore, it is testified that α-ZrP can be used as the laminate and has remarkable influences on enhancing the lifetimes of chromophores. We expect that this new discovered effect can enable α-ZrP a kind of new potential material to develop novel light-emitting materials and optical devices.     

狼毒多糖对TNF-α诱导的内皮细胞P-selectin表达的影响

目的:探讨狼毒多糖(EFP-AW1)对TNF-α诱导的内皮细胞P-selectin表达的影响。方法:以TNF-α诱导HUVECs建立内皮细胞分泌P-selectin模型,流式细胞术检测EFP-AW1对TNF-α诱导的HUVECs细胞P-selectin蛋白表达的影响;Real-time PCR检测EFP-AW1对TNF-α诱导的HUVECs细胞P-selectin m RNA表达的影响。结果:HUVECs经TNF-α刺激后P-selectin表达较空白对照组明显增强(P<0.05),而经过EFP-AW1预处理的HUVECs P-selectin m RNA和蛋白表达水平与TNF-α刺激组比较明显降低(P<0.05),并具有一定的剂量依赖性。结论:EFP-AW1能够降低TNF-α诱导的内皮细胞黏附分子P-selectin表达,从而抑制P-selectin介导的肿瘤细胞与内皮细胞的黏附。     

Potential risk indicators of retained placenta and other diseases in multiparous cows

Retained placenta (RP), defined as fetal membranes not being expelled within 24 h after calving, is a costly disease in multiparous dairy cows that has been linked to immune suppression, infections, elevated lipid mobilization, and depleted status of antioxidants including α-tocopherol, and that increases the risk of other diseases (OD) in early lactation. Early detection of cows at increased risk of developing RP, OD, or both in early lactation could improve treatment success and result in improved milk production and reproductive performance. To identify risk indicators of RP, OD, or both, we used a nested case-control design and compared multiparous dairy cows that developed RP (n = 32) with cows that remained healthy (H; n = 32) or cows that developed OD (n = 32) in early lactation. We compared peripartal body condition score (BCS) as well as serum concentrations of α-tocopherol, metabolites [β-hydroxybutyrate (BHBA), cholesterol, glucose, nonesterified fatty acids (NEFA), and urea N], haptoglobin, and macrominerals (i.e., calcium, magnesium, and phosphorus) on d −21, −14, −7, −3, −1, 0, 1, 3, 7, 14, 21, 28, 35, 42, and 49 postpartum. In addition, average serum concentrations were calculated for each cow for the last 3 wk prepartum, for 3 and 2 wk prepartum combined, for the last week prepartum, and for the morning after calving and compared between groups. The RP cows had lower BCS than the H or OD cows until 2 wk postpartum. During the prepartal periods, RP and OD cows had lower α-tocopherol concentrations (corrected or not for cholesterol concentration) and higher NEFA and BHBA concentrations than H cows. Thus, lower prepartal BCS could be an early predictor for RP risk, and lower α-tocopherol concentrations and higher NEFA and BHBA concentrations could be early predictors for disease.