Syntheses and properties of triborane(5)s possessing bulky diamino substituents on terminal boron atoms

The present communication reports the chemistry of three linear triborane(5) compounds possessing bulky diamino substituents on the terminal boron atoms. Fluorotriborane 2 was synthesized by a reaction of boryllithium and BF(3)·OEt(2). Halogen exchange reaction of 2 took place by a treatment with ClSiMe(3) to give the corresponding chlorotriborane(5) 3. Addition of silver tetraarylborate to 3 in ether afforded a hydroxylated triborane(5) compound 5 probably via an unstable cationic boron intermediate 4.     

A lateral speckle tracking algorithm for ultrasound elastography

Journal of the Korean Physical Society - Speckle tracking is widely used for elastography in ultrasound imaging. Traditional speckle tracking algorithms accurately detect axial motion, but have...     

Interaction of Cupidin/Homer2 with two actin cytoskeletal regulators, Cdc42 small GTPase and Drebrin, in dendritic spines

Background  

Homer is a postsynaptic scaffold protein that links various synaptic signaling proteins, including the type I metabotropic glutamate receptor subunits 1α and 5, the inositol 1,4,5-trisphosphate receptor, Shank and Cdc42 small GTPase. Overexpression of Homer induces changes in dendritic spine morphology in cultured hippocampal neurons. However, the molecular basis underpinning Homer-mediated spine morphogenesis remains unclear. In this study, we aimed to elucidate the structural and functional properties of the interaction between Cupidin/Homer2 and two actin-cytoskeletal regulators, Cdc42 small GTPase and Drebrin.     

冻存人淋巴细胞凝集的成因分析

本文对长期冻存的人外周血淋巴细胞的细胞膜形态和功能变化及其与细胞凝集的关系进行了研究,并对凝集的成因作了分析,初步提出了降低凝集作用的综合措施. 采用含to劣二甲基亚矾和40}人AB型血清的RPMI 164。培养液作为冻存液,将淋巴细胞在液氮中冻存1年,复温后,检测其存活率,细胞凝集现象和细胞电泳速率,并观察了细胞表面超微结构的变化. 冻存淋巴细胞复苏后,部分细胞呈现凝集状态,这是由于细胞膜结构和功能受到损伤所致,表现在细胞表面净负电荷密度的降低,电泳率减缓,细胞轻度皱缩,膜表面微绒毛增粗,出现粗大的指状突起.二甲基亚讽是造成膜结构与功能变化的一个重要因素,在常温下更加明显,它具有较强的促凝集作用.此外,淋巴细胞悬液内混杂血小板,也是促进细胞凝集的因素.     

Determination of tetrahydrocannabinolic acid—carrier protein conjugate by matrix-assisted laser desorption/ionization mass spectrometry and antibody formation

In order to form the monoclonal antibody against tetrahydrocannabinolic acid (THCA), THCA was coupled with bovine serum albumin (BSA) or human serum albumin (HSA) using β-alanine as a linker or without β-alanine to produce individual antigen conjugates. The number of haptens contained in the antigen conjugates was determined by matrix-assisted laser desorption ionization mass spectrometry using BSA or HSA as an internal standard. The formation of monoclonal antibody is also discussed.     

Novel quartz flow-cell as a post-column photochemical reactor for high-performance liquid chromatography

The construction of a new post-column photochemical reactor with quartz flow cells in series for high-performance liquid chromatography (HPLC) is described. The performance of the new reactor was compared with a conventional open tubular PTFE coil reactor. The sensitivity, accuracy and precision obtained with both reactors are comparable. The new reactor has the obvious advantages of smaller cell volume as well as inertness and resistance to not only light and heat produced by the UV lamp, but also to organic solvents in the mobile phases, which results in greatly improved durability, reduced peak broadening and shorter chromatographic run times. Application of the new reactor to the fluorescence detection of DU-6859a, a new fluoroquinolone antimicrobial agent, in human serum is reported.     

Reversible thermoresponsive aggregation/deaggregation of water-dispersed polymeric nanospheres exhibiting structural transformation

Crystalline polymeric nanospheres composed of poly{stearyl methacrylate (SMA)-co-poly(ethylene glycol) monomethacrylate (PEGm)}s were prepared by the dispersion radical polymerization of SMA and PEGm in an ethanol/water solution. Scanning electron microscopy showed that the nanospheres were highly spherical, and had a narrow size distribution. Electron spectroscopy for chemical analysis and X-ray diffraction studies of the nanospheres suggested a core-corona-type structure; the hydrophilic PEGm corona accumulated on the nanosphere surface, while the hydrophobic SMA core formed a layered structure. Heat treatment caused a melting of the SMA layers, but successive cooling allowed it to re-form. Accompanying this reversible order-disorder transition, the nanospheres also showed a reversible aggregation/deaggregation behavior in their water-dispersion state.     

Carbon-carbon bond construction on solid support: triethylborane-induced radical reactions of oxime ethers

The triethylborane-induced solid-phase radical reaction was studied. The solid-phase radical reaction of oxime ether anchored to Wang resin proceeded smoothly to give the α-amino acid derivatives. The carbon-carbon bond-forming radical reaction of TentaGel OH resin-bound glyoxylic oxime ether proceeded even in aqueous media.     

Direct alkenylation of arylamines at the ortho-position

Treatment of magnesium alkylidene carbenoids, which were generated from 1-chlorovinyl p-tolyl sulfoxides with isopropylmagnesium chloride at −78 °C in toluene, with N-lithio arylamines gave ortho-alkenylated arylamines in moderate to good yields. The reaction was found to proceed in a highly stereospecific manner at the carbenoid carbon. This reaction offers a quite novel and direct alkenylation of arylamines at the ortho-position of the aromatic ring.