Site‐Selective Labeling of a Lysine Residue in Human Serum Albumin

Conjugation to human serum albumin (HSA) has emerged as a powerful approach for extending the in vivo half‐life of many small molecule and peptide/protein drugs. Current HSA conjugation strategies, however, can often yield heterogeneous mixtures with inadequate pharmacokinetics, low efficacies, and variable safety profiles. Here, we designed and synthesized analogues of TAK‐242, a small molecule inhibitor of Toll‐like receptor 4, that primarily reacted with a single lysine residue of HSA. These TAK‐242‐based cyclohexene compounds demonstrated robust reactivity, and Lys64 was identified as the primary conjugation site. A bivalent HSA conjugate was also prepared in a site‐specific manner. Additionally, HSA‐cyclohexene conjugates maintained higher levels of stability both in human plasma and in mice than the corresponding maleimide conjugates. This new conjugation strategy promises to broadly enhance the performance of HSA conjugates for numerous applications.     

Affinity‐Labeling‐Based Introduction of a Reactive Handle for Natural Protein Modification

A new chemical method to site‐specifically modify natural proteins without the need for genetic manipulation is described. Our strategy involves the affinity‐labeling‐based attachment of a unique reactive handle at the surface of the target protein, and the subsequent selective transformation of the reactive handle by a bioorthogonal reaction to introduce a variety of functional probes into the protein. To demonstrate this approach, we synthesized labeling reagents that contain: 1) a benzenesulfonamide ligand that directs specifically to bovine carbonic anhydrase II (bCA), 2) an electrophilic epoxide group for protein labeling, 3) an exchangeable hydrazone bond linking the ligand and the epoxide group, and 4) an iodophenyl or acetylene handle. By incubating the labeling reagent with bCA, the reactive handle was covalently attached at the surface of bCA through epoxide ring opening. Either after or before removing the ligand by a hydrazone/oxime‐exhange reaction, which restores the enzymatic activity, the reactive handle incorporated could be derivatized by Suzuki coupling or Huisgen cycloaddition reactions. This method is also applicable to the target‐specific multiple modification in a protein mixture. The availability of various (photo)affinity‐labeling reagents and bioorthogonal reactions should extend the flexibility of this strategy for the site‐selective incorporation of many functional molecules into proteins.     

Purification and Characterization of Three Galactose Specific Lectins from Sajna (Moringa Oleifera L.) Leaves

Three lectins designated as SLL‐1, SLL‐2 and SLL‐3 were purified from small sized Sajna (Moringa oleifera L.) leaves by gel filtration of 100% ammonium sulfate saturated crude protein extract on Sephadex G‐75 followed by ion‐exchange chromatography on DEAE and affinity chromatography on Sepharose‐4B. The molecular weight of the lectins SLL‐1, SLL‐2 and SLL‐3 were 1,55,000, 1,15,000 and 85,000, respectively, as determined by gel filtration on Sephadex G‐150 and 1,60,000; 1,20,000 and 85,500, respectively, by SDS‐polyacrylamide slab gel electrophoresis. SLL‐1 and SLL‐2 are dimer in nature held together by disulfide bond (s), while SLL‐3 is a monomer. The lectins agglutinated specifically rat red blood cells and the agglutination was inhibited specifically by methyl‐α‐D‐galactopyranoside, methyl‐β‐D‐galactopyranoside and D‐galactose. The lectins SLL‐1, SLL‐2 and SLL‐3 contain 3.9, 3.4 and 2.8% neutral sugar, respectively, and the sugar compositions were glucose for SLL‐1, mannose for SLL‐2 and SLL‐3 contained either N‐acetyl‐D‐glucosamine or N‐acetyl‐D‐galactosamine or both. The lectins exhibited cytotoxicity in brine shrimp lethality bioassay.     

由相对不确定度研究气体比热容比的测量仪器选择

该实验利用测量气体比热容比的经典装置,证明小球装置中做简谐振动,并依据周期推导气体比热容比理论公式,分析了测定气体比热容比的误差来源采用计算机实时测量技术获得气体在任意时刻的压强,利用比热容比的相对不确定度确定了测量仪器,从而利用精确的测量量求得气体比热容比值,利用确定的仪器测量,最终实验相对百分误差控制在0.5％.     

Vertical-slate-like MoS2 nanostructures on 3D-Ni-foam for binder-free,low-cost,and scalable solid-state symmetric supercapacitors

Here, we report binder-free vertical-slate-like MoS₂ nanostructures on 3D-Ni-Foam (VSL-MoS₂@3D-Ni foam) for low-cost high-performance solid-state symmetric supercapacitors (SSCs). The cost-effective, ecofriendly and scalable solvothermal method and its direct incorporation of VSL-MoS₂@3D-Ni-foam yield SSCs with excellent electrochemical properties with a wide potential window of 1.0?V. Furthermore, high specific capacitance of 34.1?F?g^?1 at a current density of 1.3?A?g^?1, an energy density of 4.7?W?h?kg^?1 at a high-power density of 650?W?kg^?1, and excellent stability with ～82.5% capacitance retention after 10,000 cycles were demonstrated even for SSCs with a binder free MoS₂ electrodes on 3D-Ni-foam. These excellent features of the SSCs with VSL-MoS₂@3D-Ni-foam substantiate their potential opportunity for future energy applications.     

Efficiency of Pd impregnated sol-gel derived γ-alumina porous spheres as catalyst

Porous γ-alumina spheres having surface area as large as 300 m ² /gm are obtained by using sol-gel process. γ-alumina supported Pd catalyst is synthesized by soaking it in PdCl ₂ solution followed by drying and heating at 300 ^° C/1 hr in hydrogen atmosphere. Specific Surface Area of Pd coated alumina remained unaltered. The scanning electron microscopy revealed uniform coating of Pd metal on the surface. The equivalent spherical diameter (ESD) of the coated Pd metal particles is estimated to be 50. The catalytic efficiency is evaluated by H ₂ -O ₂ combination reaction. The performance of this supported catalyst is found to be much superior in comparison with Pd catalyst realized on commercially available alumina having surface area of 80 m ² /gm. The improved efficiency of the catalyst could be co-related to enhanced surface of nano-structured Pd available for catalytic action. The added advantage of spherical shape of the support material appeared in uniform and homogeneous loading of the catalyst bed. The results highlight the important role played by support material in these type of catalysts. Received 24 November 2000     

Profiling the Supersonic Part of a Plug Nozzle with a Nonuniform Transonic Flow

The effect of transonic flow nonuniformity on the profiling of optimal plug nozzles is studied in the inviscid gas approximation. Sonic and supersonic regions providing maximum thrust for given nozzle dimensions and a given outer pressure are designed for given subsonic contours and calculated nonuniform transonic flows. As in the case of uniform flow on a cylindrical sonic surface, the initial regions of the designed contours satisfy the condition that in these regions the flow Mach number is unity or near-unity. In all the examples calculated, the optimal plug nozzles produce a greater thrust than the optimal axisymmetric and annular nozzles with a near-axial flow for the same lengths and the same gas flow rates through the nozzle. It is established that contouring without regard for transonic flow nonuniformity can result in considerable thrust losses. However, these losses are due only to a decrease in the flow rate, while the specific thrust may even increase slightly.     

捷联惯导中的划船效应及其补偿算法

重点介绍了比力转换积分中存在的划船效应，对其进行了较为详细分析和指导，同时提出了一种有效的划船修正算法进行了仿真。仿真结果表明：该算法可有效提高速度更新中比力的转换精度。     

复合圆柱管撞击吸能特性实验研究

本文研究了外部缠有玻璃纤维增强环氧的金属圆柱管（简称为“复合管”）在轴向撞击载荷下的能量吸收特性。总结了复合管撞击渐进破坏压缩历程的瞬时速度、位移、载荷等的变化规律。从破坏模式、压缩速率（与准静态实验比较）、金属材料的性能、复合材料层的厚度、纤维的缠绕角这几个角度研究了复合管的吸能性能的影响因素。     

Magneto-optical Kerr effect in bilayer structures

This paper describes the magneto-optical effects and the reflectivity behaviors of bilayers based on magnetic and isotropic ()/anisotropic () layers under the condition of total internal reflection. In the framework of Green's dyadic technique, we show accurately the optical properties of anisotropic layers deposited on a substrate. We present numerical simulations which account for the variation of angle of incidence at the HeNe laser wavelength. The Kerr rotation is found to increase significantly around the optical modes in total reflection. We also discuss the importance of anisotropic effects due to the crystallization of the dielectric material () which occur in the reflectivity and Kerr rotation spectra. Received 26 January 2000