星载光学系统遮光罩消杂光结构优化设计方法

本文对星载光学系统遮光罩消杂光结构的优化设计做了初步探讨。提出了遮光罩和挡光环消杂光设计的基本原则。给出了一种二级遮光罩结构寸的优化设计方法和一种遮光罩内壁上挡光环位置优化设计方法,并对一级和二级遮光罩进行了初步的分析比较。     

Development of xylose-fermenting yeasts for ethanol production at high acetic acid concentrations

Mutants resistant to comparatively high levels of acetic acid were isolated from the xylose-fermenting yeastsCandida shehatae andPichia stipitis by adapting these cultures to increasing concentrations of acetic acid grown in shake-flask cultures. These mutants were tested for their ability to ferment xylose in presence of high acetic acid concentrations, in acid hydrolysates of wood, and in hardwood spent sulfite liquor, and compared with their wild-type counterparts and between themselves. TheP. stipitis mutant exhibited faster fermentation times, better tolerance to acid hydrolysates, and tolerance to lower pH.     

一种三次非旋转对称的相位板的检测系统设计

作为零位干涉检测方法中非常有前途的一种方法.计算全息可以用于非旋转对称的非球面的检测.以三次相位板为例,阐述了利用计算全息图检测非旋转对称的非球面的基本原理.分析并推导了三次相位传播过程引入的高阶波像差的理论公式,给出了三次相位板的检测系统的没计结果.详细讨论了计算全息图衍射级次的分离以及计算全息图的二元化,给出了振幅型的计算全息图的图样.计算全息图的刻线最小问隔是40μm,计算全息图的制作精度对检测结果的波前误差的影响仅仅为0.005λ.对检测系统作了详细的公差分析,结果表明所有调整公差对整个检测系统的影响和方根值为83.954 nm.     

P2X7 Receptors in Astrocytes: A Switch for Ischemic Tolerance

A sub-lethal ischemic episode (preconditioning [PC]) protects neurons against a subsequent lethal ischemic injury. This phenomenon is known as ischemic tolerance. PC itself does not cause brain damage, but affects glial responses, especially astrocytes, and transforms them into an ischemia-resistant phenotype. P2X7 receptors (P2X7Rs) in astrocytes play essential roles in PC. Although P2X7Rs trigger inflammatory and toxic responses, PC-induced P2X7Rs in astrocytes function as a switch to protect the brain against ischemia. In this review, we focus on P2X7Rs and summarize recent developments on how astrocytes control P2X7Rs and what molecular mechanisms they use to induce ischemic tolerance.     

Investigation on the Stability of the Dispersion System of Cross-Linked Polyacrylamide Microspheres

The salt resistance, temperature resistance, and shear stability of a cross-linked polyacrylamide microsphere system are studied by microfiltration, light diffraction analysis, and optical microscopy. The results show that other conditions being equal, the particle diameter of cross-linked polyacrylamide microspheres decreases with increased NaCl concentration. When NaCl concentration is lower than 10,000 mg/L, its effect on the plugging performance of a cross-linked polyacrylamide microsphere system in regard to the nuclear pore membrane is weak in comparison with a linked polymer solution, but the former system has better salt tolerance. Particle diameter decreases with increased swelling temperature. When the swelling temperature is below 90°C, its effect on the plugging performance of the cross-linked polyacrylamide microsphere system in regard to nuclear pore membrane is weak in comparison with the linked polymer solution, but has better temperature tolerance. Particle size shows little change, with shearing rate being increased, while the shape remains about the same and the effect of shearing on the plugging performance of the cross-linked polyacrylamide microsphere dispersion system in regard to the nuclear pore membrane is weak in comparison with the linked polymer solution, but has better shear stability. The salt tolerance, temperature tolerance, and shear stability of microspheres are associated with a particular cross-linked structure.     

Head group specificity of novel functionalized surfactants: synthesis,self-assembly and calcium tolerance

The present work describes the synthesis, characterization and application of functionalized surfactants derived through simple organic reaction steps. These surfactants have been particularly tailor made to resist hardness due to calcium ions in water. It is unique of its kind because here the surfactants have an analogous hydrophobic chain but differ structurally in the composition of the head groups in terms of the position of attachment of the chain. The effect of this small variability in the head group on the surfactant property, adsorption, self assembly and calcium tolerance behaviour has been studied in detail. This kind of phenol–keto surfactants has not been reported before. It was also found that one of the surfactants was more tolerant towards Ca²⁺ ion than the other. The individual packing behaviour of the surfactants at the air–water interface has been projected to cause this difference which is very interesting.     

Oral delivery of therapeutic proteins bioencapsulated in plant cells: Preclinical and clinical advances

Oral delivery of protein drugs (PDs) made in plant cells could revolutionize current approaches to their production and delivery. Expression of PDs reduces their production cost by elimination of prohibitively expensive fermentation, purification, cold transportation/storage, and sterile injections and increases their shelf life for several years. The ability of plant cell wall to protect PDs from digestive acids/enzymes, commensal bacteria to release PDs in gut lumen after lysis of plant cell wall, and the role of gut-associated lymphoid tissue in inducing tolerance facilitate prevention or treatment of allergic, autoimmune diseases or antidrug antibody responses. The delivery of functional proteins facilitates treatment of inherited or metabolic disorders. Recent advances in making PDs free of antibiotic resistance genes in edible plant cells, long-term storage at ambient temperature maintaining their efficacy, production in Current Good Manufacturing Practice (cGMP) facilities, Investigational New Drug (IND)-enabling studies for clinical advancement, and Food and Drug Administration approval of orally delivered PDs augur well for advancing this novel drug delivery platform technology.     

具有优异甲醇耐受性的Rh掺杂PdCu有序金属间化合物纳米粒子增强氧还原电催化

Direct methanol fuel cells (DMFCs), as one of the important energy conversion devices, are of great interest in the fields of energy, catalysis and materials. However, the application of DMFCs is presently challenged because of the limited activity and durability of cathode catalysts as well as the poisoning issues caused by methanol permeation to the cathode during operation. Herein, we report a new class of Rh-doped PdCu nanoparticles (NPs) with ordered intermetallic structure for enhancing the activity and durability of the cathode for oxygen reduction reaction (ORR) and achieving superior methanol tolerance. The disordered Rh-doped PdCu NPs can be prepared via a simple wet-chemical method, followed by annealing to convert it to ordered phases. The results of transmission electron microscopy (TEM), scanning electron microscopy-energy dispersive X-ray spectroscopy (SEM-EDS), power X-ray diffraction (PXRD) analysis and high resolution TEM (HRTEM) successfully demonstrate the formation of near-spherical NPs with an average size of 6.5 ± 0.5 nm and the conversion of the phase structure. The complete phase transition temperatures of Rh-doped PdCu NPs and PdCu are 500 and 400 ℃, respectively. The molar ratio of Rh/Pd/Cu in the as-synthesized Rh-doped PdCu NPs is 5/48/47. Benefitting from Rh doping and the presence of the ordered intermetallic structure, the Rh-doped PdCu intermetallic electrocatalyst achieves the maximum ORR mass activity of 0.96 A·mg^-1 at 0.9 V versus reversible hydrogen electrode (RHE) under alkaline conditions—a 7.4-fold enhancement compared to the commercial Pt/C catalyst. For different electrocatalysts, the ORR activities follow the sequence, ordered Rh-doped PdCu intermetallics > ordered PdCu intermetallics > disordered Rh-doped PdCu NPs > disordered PdCu NPs > commercial Pt/C catalyst. In addition, the distinct structure endows the Rh-doped PdCu intermetallics with highly stable ORR durability with unaltered half-wave potential (E_1/2) and mass activity after continuous 20000 cycles, which are higher than those of other electrocatalysts. Furthermore, the E_1/2 of the Rh-doped PdCu intermetallics decreases by only 5 mV after adding 0.5 mol·L^-1 methanol to the electrolyte, while the commercial Pt/C catalyst negatively shifts by 235 mV and a distinct oxidation peak can be observed. The results indicate that the ORR activity of the Rh-doped PdCu intermetallic electrocatalyst can be well maintained even in the presence of poisoning environment. Our results have demonstrated that Rh-doped PdCu NPs with ordered intermetallic structures is a potential electrocatalyst toward the next-generation high-performance DMFCs.     

Tolerance,bioaccumulation and biotransformation of arsenic in freshwater prawn (Macrobrachium rosenbergii)

Tolerance bioaccumulation and biotransformation of arsenic compounds by a freshwater prawn (Macrobrachium rosenbergii) were investigated. M. rosenbergii was exposed to 10, 20, 30 and 35 μg As cm⁻³ of disodium arsenate [abbreviated as As(V)], 25, 50, 100 and 120 μg As cm⁻³ of methylarsonic acid (MMAA), or 100,200, 300 and 350 μg As cm⁻³ of dimethylarsinic acid (DMAA). Tolerances (50% lethal concentration: LC₅₀) of the prawn against As(V), MMAA, and DMAA were 30, 100, and 300 μg As cm⁻³, respectively. The prawn accumulated arsenic compounds directly from aqueous phase and biotransformed them in part. Both methylation and demethylation of the arsenicals were observed in vivo. Highly methylated and less toxic arsenicals were less accumulated in M. rosenbergii.     

Screening of Yeast in Various Vineyard Soil and Study on Its Flavor Compounds from Brewing Grape Wine

In order to screen out Saccharomyces cerevisiae suitable for table grape fermentation, and compare it with commercial Saccharomyces cerevisiae in terms of fermentation performance and aroma producing substances, differences of fermentation flavor caused by different strains were discussed. In this experiment, yeast was isolated and purified from vineyard soil, 26s rDNA identification and fermentation substrate tolerance analysis were carried out, and the causes of flavor differences of wine were analyzed from three aspects: GC-MS, PCA and sensory evaluation. The results showed that strain S1 had the highest floral aroma fraction, corresponding to its high production of ethyl octanoate and other substances, and it had the characteristics of high sugar tolerance. The fruit sensory score of S3 wine was the highest among the six wines. Through exploration and analysis, it was found that compared with commercial Saccharomyces cerevisiae, the screened strains had more advantages in fermenting table grapes. The flavor of each wine was directly related to the growth characteristics and tolerance of its strains.