以猪小肠黏膜提取物作为α-葡萄糖苷酶和二肽基肽酶Ⅳ的酶活力分析体系的建立

α-葡萄糖苷酶和二肽基肽酶IV(dipeptidyl peptidase 4,DPP-4)是II型糖尿病治疗中2种重要的靶向酶。这两种商品化酶价格昂贵且主要来源于微生物,难以有效用于两种酶抑制剂的筛选,而这两种酶均普遍存在哺乳动物的小肠中。为了获得经济有效、来源于哺乳动物体内的α-葡萄糖苷酶和DPP-4,本研究收集新鲜的猪小肠黏膜分泌物及上皮细胞,对比分析了猪小肠不同部位黏膜提取物的α-葡萄糖苷酶和DPP-4的活力。以猪小肠黏膜提取物作为α-葡萄糖苷酶和DPP-4的酶反应体系,并且利用这两种酶的阳性药(阿卡波糖和抑二肽素A(diprotin A,IPI))分别进行了抑制率验证和评价。阿卡波糖对商品和猪回肠源α-葡萄糖苷酶的半数有效抑制质量浓度(median inhibition concentration,IC50)分别是1.1024、0.2447 mg/mL;IPI对商品和猪回肠源DPP-4的IC50分别为19.1197、41.2684μg/mL。通过比较发现,猪回肠黏膜提取物的α-葡萄糖苷酶和DPP-4比活力分别为0.0841、0.0534 U/mg,在3种黏膜提取物中均为最高,因此选择猪回肠黏膜提取物作为商品化α-葡萄糖苷酶和DPP-4的替代物进行抑制剂的筛选。

Two-dimensional MOF/MOF derivative arrays on nickel foam as efficient bifunctional coupled oxygen electrodes

Oxygen electrocatalysis,exemplified by the oxygen reduction reaction(ORR)and oxygen evolution reaction(OER),is central to energy storage and conversion technologies such as fuel cells,metal-air batteries,and water electrolysis.However,highly effective and inexpensive earth-abundant materials are sought after to replace the noble metal-based electrocatalysts currently in use.Recently,metal-organic frameworks(MOFs)and carbon-based MOF derivatives have attracted considerable attention as efficient catalysts due to their exceedingly tunable morphologies,structures,compositions,and functionalization.Here,we report two-dimensional(2D)MOF/MOF derivative coupled arrays on nickel foam as binder-free bifunctional ORR/OER catalysts with enhanced electrocatalytic activity and stability.Their remarkable electrochemical properties are primarily attributed to fully exposed active sites and facilitated charge-transfer kinetics.The coupled and hierarchical nanosheet arrays produced via our growth-pyrolysis-regrowth strategy offer promise in the development of highly active electrodes for energy-related electrochemical devices.

Development of multi-physics numerical simulation model to investigate thermo-mechanical fatigue crack propagation in an autofrettaged gun barrel

In this research,a detailed multi-physics study has been carried out by numerically simulating a solid fractured gun barrel for 20 thermo-mechanical cycles.The numerical model is based on thermal effects,mechanical stress fields and fatigue crack mechanics.Elastic-plastic material data of modified AISI 4340 at temperatures ranging from 25 to 1200℃and at strain rates of 4,16,32 and 48 s^(-1) was acquired from high-temperature compression tests.This was used as material property data in the simulation model.The boundary conditions applied are kept similar to the working gun barrel during continuous firing.A methodology has been provided to define thermo-mechanically active surface-to-surface type interface between the crack faces for a better approximation of stresses at the crack tip.Comparison of results from non-autofrettaged and autofrettaged simulation models provide useful information about the evolution of strains and stresses in the barrel at different points under combined thermo-mechanical loading cycles in both cases.The effect of thermal fatigue under already induced compressive yield due to autofrettage and the progressive degradation of the accumulated stresses due to thermo-mechanical cyclic loads on the internal surface of the gun barrel(mimicking the continuous firing scenario)has been analyzed.Comparison between energy release rate at tips of varying crack lengths due to cyclic thermo-mechanical loading in the non-autofrettaged and autofrettaged gun has been carried out.

Effect of Annealing Atmosphere Induced Crystallite Size Changes on the Electrochemical Properties of TiO2 Nanotubes Arrays

TNAs （Titanium dioxide nanotube arrays） were synthesized by electrochemical anodization and these TNAs were annealed in different gas atmosphere such as argon, air, hydrogen and nitrogen. This annealing in different atmosphere brought variation in crystallite size （27 - 33 nm）, which influences on electrochemical properties. The specific capacity of Ar, Air, N2 and H2-annealed TNAs was around ~165, 185, 177 and 190 mAh g~, respectively. The crystallite size of anatase TNAs seemed to be responsible for the change in lithium storage capacity, indicating that structural changes of TNAs were playing major role in electrochemical properties.

Studies on Productivity and Performance of Spring Sugarcane Sown in Different Planting Configurations

Row spacing has a pivotal role in enhancing sugarcane yield and improving its quality. A study was undertaken to evaluate the influence of different planting techniques on performance of sugarcane at Agronomic Research Area, Department of Agronomy, University of Agriculture Faisalabad during Kharif 2014. Experimental treatments comprised of: 180 cm spaced trenches with tripple row strips, 180 cm spaced trenches with alternate row strips, 120 cm spaced trenches with double row strips and 60 cm spaced furrows with single rows. Sugarcane cultivar HSF-240 was used as experimental material. The experimental was conducted in RCBD with four replications. The expeimental results revealed that sugarcane number of tillers, plant height, cane length, stripped cane weight and stripped cane yield increased progressively with the increase in row spacing from 60 to 180 cm. While germination percentage and number of millable canes were not affected by different sowing techniques, maximum number of tillers (15.96 m-2), plant height (333.25 cm), stripped cane weight (0.94 kg) and stripped cane yield (107 t·ha-1) were recorded from 180 cm spaced trenches with tripple row strips.

Wet-milling synthesis of immobilized Pt/Ir nanoclusters as promising heterogeneous catalysts

Being a typical state of the art heterogeneous catalyst,supported noble metal catalyst often demonstrates enhanced catalytic properties.However,a facile synthetic method for realizing large-scale and low-cost supported noble metal catalyst is strictly indispensable.To this end,by making use of the strong metal-support interaction(SMSI)and mechanochemical reaction,we introduce an efficient synthetic route to obtain ultrafine Pt and Ir nanoclusters immobilized on diverse substrates by wet chemical milling.We further demonstrate the scaling-up effect of our approach by large-scale ball-milling production of Pt nanoclusters immobilized on TiO_(2)substrate.The synthesized Pt/Ir@Co_(3)O_(4)catalysts exhibit superior oxygen evolution reaction(OER)performance with only 230 and 290 mV overpotential to achieve current density of 10 and 100 mA·cm^(-2),beating the catalytic performance of Co_(3)O_(4)supported Pt or Ir clusters and commercial Ir/C.It is envisioned that the present work strategically directs facile ways for fabricating supported noble metal heterogeneous catalysts.

Large-area, transferable sub-lO nm polymer membranes at the air-water interface

Large-area, pinhole-free, and ultrathin polymer membranes with thicknesses of only a few nanometers have attracted increasing attention for their applications in molecular separation, flexible optoelectronics, and sensors. They can potentially be developed for surface protection as well. In this study, we report an effective way to obtain large-scale polymer coatings with a thickness down to 10 nm, which effectively protects metals from corrosion. We develop a facile and scalable method to fabricate freestanding polymer membranes with thickness below 10 nm by dropping the precursor polymer solution on a water surface. By optimizing the surface tension of the polymer solution, the solution could spontaneously spread on the water surface to form a continuous and uniform solid membrane, collected as a freestanding thin membrane. The obtained polymer membranes could then easily be transferred on a metal substrate as highly flexible and stable anti-corrosion coatings. Electrochemical measurements performed in a 0.1 M Na2SO4 solution demonstrated the excellent anti-corrosion properties of the sub-10 nrn polymer membranes whose corrosion rate was less than 1% of the corrosion rate of the bare metal. We also demonstrate that the polymer membrane exhibits high performance as a protection layer for flexible circuits.