Sea surface temperature reconstruction for the middle Okinawa Trough during the last glacial-interglacial cycle using C-37 unsaturated alkenones

IEECAS SKLLQG

2-KLG产生菌混合发酵特性及最佳混生模式的研究

氧化葡萄糖酸杆菌合成的2－KLG对巨大芽孢杆菌的生长繁殖具有明显的抑制作用，可缩短其生长周期。发酵体系中巨大芽孢杆菌的存在是氧化葡萄糖酸杆菌的生长繁殖和合成2－KLG所必需的，发酵过程中巨大芽孢杆菌裂解所释放的活性物质可能是刺激氧化葡萄糖酸杆菌合成2－KLG的主要原因。二菌混合发酵需在适宜的混生模式下才可达到最佳效果。

33轮SHACAL-2的差分非线性攻击

利用SHACAL-2的一个17轮差分非线性区分器,结合被猜测子密钥空间分割的方法和快速傅立叶变换,提出了一种攻击33轮SHACAL-2的新方法.该方法攻击33轮SHACAL-2需要244的选择明文、2496.6的33轮SHACAL-2加密和2502次算术运算,攻击成功概率为99%.与已有的结果相比较,新攻击有效地提高了单密钥下SHACAL-2的攻击轮数.

Progress in Ru (bpy)(3)(2+) Electrogenerated Chemiluminescence

Among various ECL systems, such as 9,10-diphenylanthracene, lucigenin, tris(2,2'-bipyridyl) ruthenium, peroxyoxalate, luminol, graphene, and nanocrystals, Ru(bpy)(3)(2+) ECL is one of the most widely studied ECL systems in recent years due to its broad applications in immunoassays, DNA probe assays, coreactants analysis, and aptasensors. In this review, the progress in Ru(bpy)(3)(2+) ECL has been summarized on the whole, and the future research trends have been proposed.

微悬臂梁检测三肽Gly-Gly-His与Cu~(2+)的相互作用过程

将三肽Gly-Gly-His(GGH)共价键合到MPA修饰的微悬臂梁表面,研究了肽与Cu2+的相互作用过程。研究发现,在Cu2+浓度较高时,Cu2+能快速与不同肽链上的羧基和咪唑环配位,并通过连锁反应诱导悬臂梁向镀金面偏转;而后肽链上的氮原子与Cu2+配位,同时构象发生变化,由直链转变成折叠状,进而增加链间的作用力使悬臂梁反向偏转;而Cu2+浓度低时不能实现连锁反应诱导悬臂梁表面快速的形成向内的拉力,直接通过构象变化推动悬臂梁反向偏转。考察了溶液pH值、Cl-浓度对GGH与Cu2+作用的影响,结果表明,在pH7.0的条件下GGH与Cu2+作用导致悬臂梁偏转最大。Cl-的存在会与Cu2+形成CuCl2x?x配合物不易与肽链结合。

Microstructure, thermal stability and mechanical properties of the novel (W1-xAlx)C-Co (x=0.2, 0.33, 0.4, 0.5) cemented carbide

Bulk novel cemented carbides (W1-xAlx)C-10.1 vol% Co (x = 0.2, 0.33, 0.4, 0.5) are prepared by mechanical alloying and hot-pressing sintering. Hot-pressing (HP) is used to fabricate the bulk bodies of the hard alloys. The novel cemented carbides have good mechanical properties compared with WC-Co. The density and operating cost of the novel material is much lower than a WC-Co system. The material is easy to process and the processing leads to nano-scaled, rounded, particles in the bulk material. The hardness of (W1-xAlx)C-10.1 vol% Co (x = 0.2, 0.33, 0.4, 0.5) hard material is 20.37, 21.16, 21.59 and 22.16 GPa, and the bending strength is 1257, 1238, 1211 and 1293 MPa, with the aluminum content varying from 20% to 50%. The relationship between the microstructure and the mechanical properties of the novel hard alloy is also discussed.

Synthesis and characterization of optically active aromatic polyimides derived from 2,2 '-bis(2-trifluoro-4-aminophenoxy)-1,1 '-binaphthyl and aromatic tetracarboxylic dianhydrides

Optically active 2,2'-bis(2-trifluoro-4-aminophenoxy)-1,1'-binaphthyl and its corresponding racemate were prepared by a nucleophilic substitution reaction of 1,1'-bi-2-naphthol with 2-chloro-5-nitrotrifluorotoluene and subsequently by the reduction of the resulting dinitro compounds. a series of optically active and optically inactive aromatic polyimides also were prepared therefrom, These polymers readily were soluble in common organic solvents such as pyridine, N,N'-dimethylacetamide, and m-cresol and had glass-transition temperatures of 256 similar to 278 degrees C. The specific rotations of the chiral polymers ranged from 167 similar to 258 degrees, and their chiroptical properties also were studied. (C) 1999 John Wiley & Sons Inc.

Synthesis and characterization of soluble polyimides from 2,2-bis(4-aminophenyl)cycloalkane derivatives

New aromatic diamines [(1) and (2)] containing polycycloalkane structures between two benzene rings were synthesized by HCl-catalyzed condensation reaction of aniline hydrochloride and corresponding polycycloalkanone derivatives. The structures of diamines were identified by H-1-NMR, C-13-NMR, FTIR spectroscopy, and elemental analysis. The polyimides were synthesized from the obtained diamines with various aromatic dianhydrides by one-step polymerization in m-cresol. The inherent viscosities of the resulting polyimides were in the range of 0.34-1.02 dL/g. The polyimides showed good thermal stabilities and solubility. All the polymers were readily soluble in N-methyl-2-pyrrolidone, m-cresol, tetrachloroethane, etc. Some of them were soluble even in chloroform at room temperature. The glass transition temperatures were observed in the range of 323-363 degrees C, and all of the polymers were stable up to 400 degrees C under nitrogen atmosphere. (C) 1999 John Wiley & Sons, Inc.

Synthesis and properties of aromatic polyimides derived from 2,2,' 3,3 '-biphenyltetracarboxylic dianhydride

2,2,'3,3' -Biphenyltetracarboxylic dianhydride (2,2,'3,3'-BPDA) was prepared by a coupling reaction of dimethyl 3-iodophthalate. The X-ray single-crystal structure determination showed that this dianhydride had a bent and noncopolanar structure, presenting a striking contrast to its isomer, 3,3,'4,4'-BPDA. This dianhydride was reacted with aromatic diamines in a polar aprotic solvent such as N,N-dimethylacetamide (DMAc) to form polyamic acid intermediates, which imidized chemically to polyimides with inherent viscosities of 0.34-0.55 dL/g, depending on the diamine used. The polyimides from 2,2,'3,3'-BPDA exhibited a good solubility and were dissolved in polar aprotic solvents and polychlorocarbons. These polyimides have high glass transition temperatures above 283 degrees C. Thermogravimetric analyses indicated that these polyimides were fairly stable up to 500 degrees C, and the 5% weight loss temperatures were recorded in the range of 534-583 degrees C in nitrogen atmosphere and 537-561 degrees C in air atmosphere. All polyimides were amorphous according to X-ray determination. (C) 1999 John Wiley & Sons, Inc.

Use of lanthanide metal complexes for the hydrolysis of 3 ',5 '- and 2 ',3 ' cyclic nucleotides

Lutetium(III) and lanthanum(III) complexes of 2-carboxyethylgermanium sesquioxide (Ge-132) can hydrolyze the phosphodiester linkage of 3',5'-cyclic adenosine monophosphate (cAMP), 3',5'-cyclic deoxyadenosine monophosphate (dcAMP) and 2',3'-cyclic adenosine monophosphate (2',3'-cAMP). Both cAMP and dcAMP are hydrolyzed with high selectivity, yielding predominantly 3'-monophosphates. 2',3'-cAMP is converted to 3'-AMP and 2'-AMP, the ratio of 3'-AMP to 2'-AMP produced being 1.4.

2,2′-联吡啶的吸附行为与其对细胞色素c电化学反应的促进作用

2,2′-联吡啶在金电极上需长达10 h 左右才能达到吸附平衡和有足够量的分子来促进细胞色素 c 的电化学反应.需用长时间浸泡膜转移法,减小因促进剂分子吸附强度的变化而造成的差别.

STUDIES OF ELECTROCHEMICAL CATALYTIC REDUCTION REACTIONS OF TETRAPHENYLPORPHINATOCOBALT 1,2-DIBROMOETHANE AND 1,2-DICHLOROETHANE SYSTEMS IN NONAQUEOUS MEDIA

Electrochemical catalytic reactions of tetraphenylporphinatocobalt were studied in DMF and EtCl2 solutions in the presence of 1,2-dibromoethane and 1, 2-dichloroethane utilizing cyclic voltammetry, thin-layer electrochemistry, in situ UV-visible spectroel