Synthesis and properties of a mitochondrial peripheral benzodiazepine receptor conjugate

Peripheral benzodiazepine receptors are potential targets for cancer therapeutics through the use of specific ligands such as the pro-apoptotic benzodiazepine RO5-4864. However, the poor water solubility of this compound has been a limitation to its application in vivo. Herein we describe an efficient synthesis for the conjugation, via a cleavable linker arm, of RO5-4864 to a novel tumour-delivery tool, the B-subunit of Shiga toxin (STxB). The conjugate is water soluble and specifically targets cancer cells that overexpress the glycolipid Gb3, the cellular Shiga toxin receptor that is found on several human tumours. After internalisation via retrograde transport, the prodrug is cleaved inside cells to release the active principle. Delivery by STxB therefore increases the cytotoxic activity of RO5-4864 and its tumour specificity.     

电工钢片磁性的计量问题

综述了电工钢片计量的当前水平和最新进展,重点讨论了在交变场中的标准测试方法:Epstein方圈法和单片(SST)法.所讨论的相关条款是有关磁通密度控制、数据获取和数据计算的最新电子方法,以及磁路设计对这两种方法的准确性和精度特性的影响,也讨论了系统误差来源、再现特性和经济因素等.     

Atomic force microscopy-derived nanoscale chip for the detection of human pathogenic viruses

Native-protein nanolithography (NPNL) was used to fabricate stable bioactive arrays of viral receptor spots. The arrays were specific for the cognate virus and devoid of nonspecific protein and virus adsorption under physiologic conditions. The spot size ranged from 200 nm x 200 nm to 2 microm x 2 microm and up to 3 x 3 spots were arranged per array. With proper force adjustment in the patterning experiments, His(6)-tagged bovine serum albumin (BSA) molecules were selectively removed from the underlying self-assembled monolayer (SAM) while leaving the latter intact. Injection of His(6)-tagged very low density lipoprotein receptor (VLDLR-His(6)) constructs resulted in specific, oriented binding to the Ni(2+)-loaded bis-(nitrolotriacetic acid) (bis-NTA) groups to the re-exposed SAM areas. The arrays of viral receptors were used for the detection of human rhinovirus particles (serotype 2; HRV2) under native conditions by topographical imaging at high signal-to-noise ratio. The kinetic on-rate of the HRV2-VLDLR interaction was derived from the time-dependent binding of the virions to the VLDL receptor spots. No significant binding was observed for the major group virus HRV14 that uses the unrelated receptor ICAM-1.     

Effective Work Function Reduction of Practical Electrodes Using an Organometallic Dimer

The control of the cathode work function (WF) is essential to enable efficient electron injection and extraction at organic semiconductor/cathode interfaces in organic electronic devices. In this paper, ultraviolet photoelectron spectroscopy is used to confirm that depositing an ultrathin layer of the moderately air‐stable pentamethylrhodocene dimer onto various conducting electrodes, by either vacuum deposition or drop casting from solution, substantially reduces their WF to less than 3.6 eV, with 2.7 eV being the lowest attainable value. Detailed measurements of the Rh core levels with X‐ray photoelectron spectroscopy reveal that the electron transfer from the molecule to the respective substrates is responsible for the appreciable WF reduction. Notably, even after air exposure, the WF of the donor‐covered electrodes remains below those of typically used clean cathode metals, such as Al and Ag, rendering the approach appealing for practical applications. The WF reduction, together with the observed air stability of the covered electrodes, demonstrates the ability of the pentamethylrhodocene dimer to reduce the WF for a wide range of electrodes used in all‐organic or organic–inorganic hybrid devices.     

Rate of precipitation of ferrous iron and formation of mixed iron-calcium carbonates by naturally occurring carbonate materials

The precipitation of iron from an iron sulphate containing wastewater by aragonite, calcite and a variety of limestones and limesands was examined at pH values near 6 in an atmosphere of carbon dioxide. Siderite (ferrous carbonate) and a calcium siderite containing 10 mol% calcium were the only iron-containing products detected by XRD, and accounted for substantially all the iron removed from solution. Calcium siderite was the major product and constituted between 50 and 100% of the iron containing product.The rate of precipitation of iron was proportional to the square of the supersaturation of the solution with respect to siderite, and increased with increase in pH and alkalinity. Precipitation occurred at different rates with different carbonate materials, tending to increase with increasing proportion of aragonite in the material. Precipitation did not occur in suspensions of calcite and was slow even in suspensions of aragonite where equilibrium was not reached within 40 days.These data suggest that the frequent occurrence of groundwaters apparently supersaturated with respect to siderite may be due either to slow precipitation of siderite, or to equilibrium of the groundwater with respect to a more soluble calcium siderite. The minerals present in an aquifer thus need to be identified before the saturation state of the associated groundwater with respect to siderite can be ascertained.     

Lizard Epidermal Gland Secretions I: Chemical Characterization of the Femoral Gland Secretion of the Sungazer, <Emphasis Type="Italic">Cordylus giganteus</Emphasis>

The giant girdled lizard or sungazer, Cordylus giganteus, is endemic to South Africa. It has been suggested that in this species, as in other lizard species, epidermal glands in the femoral, pre-cloacal regions, and cloacal glands are the main sources of semiochemicals and that these secretions could play an important role at different levels of the social biology of the animals. To gain a better understanding of the nature of the femoral gland secretions of the sungazer, characterization of the constituents of the secretions was carried out. By using GC-MS analysis, in conjunction with auxiliary techniques, such as solventless sample introduction and trimethylsilyl derivatization, 53 relatively involatile compounds, including carboxylic acids, alcohols, ketones, esters, and steroids, were identified in the secretions of both sexes. The study showed that the secretions of male and female sungazers contain only semi-volatile chemicals.     

Sex Pheromone of <Emphasis Type="Italic">Elater ferrugineus</Emphasis> L. (Coleoptera: Elateridae)

The rare European click beetle, Elater ferrugineus L., develops exclusively in old, hollow deciduous trees. As a result of massive habitat loss caused by modern forestry, it is threatened throughout its entire distribution range and regarded as an indicator species for undamaged natural forests. As E. ferrugineus lives cryptically and its populations are frequently overlooked, we investigated its sex pheromone to develop a reliable detection tool. Pheromone gland extracts of single female E. ferrugineus were examined by using gas chromatography–mass spectrometry (GC–MS). All samples contained 7-methyloctyl 5-methylhexanoate, 7-methyloctyl octanoate, 7-methyloctyl 7-methyloctanoate, and 7-methyloctyl (Z)-4-decenoate in a ratio of approximately 1:1:3:3. Structures of all four esters, which have not been reported as pheromone compounds before, were confirmed by synthesis. A blend of the components was tested in the field and proved to be attractive for E. ferrugineus males, which were found to swarm exclusively during the day. This blend provides a noninvasive and effective monitoring method for this cryptic species, promising future collection records of E. ferrugineus in regions where it exists below the limit of detection by conventional collecting methods.     

Transfer printing of DNA by "click" chemistry

This paper describes a straightforward procedure to immobilize oligonucleotides on glass substrates in well-defined micropatterns by microcontact printing with a dendrimer-modified stamp. The oligonucleotides are efficiently immobilized by "click" chemistry induced by microcontact printing. Acetylene-modified oligonucleotides were treated with an azide-terminated glass slide under the confinement of the dendrimer-modified stamp, without the use of a Cu(I) catalyst. The immobilization is an irreversible, covalent, and one-step reaction that results in stable attachment of the oligonucleotides. Oligonucleotides with the acetylene-modification at the 5' terminus hybridize selectively with full-length, complementary targets. Strands with more than one acetylene linker do not hybridize with complementary strands.