Myxobacterial epothilones and tubulysins as promising anticancer agents

Tubulin-binding agents play a pivotal role in current cancer therapy and there are many efforts in pre-clinical and clinical development of known and novel cytotoxic agents ongoing. In this article a known class, epothilones, as well as a novel class, tubulysins, are presented.     

Preparation of tissue samples for X-ray fluorescence microscopy

As is well-known, trace elements, especially metals, play an important role in the pathogenesis of many disorders. The topographic and quantitative elemental analysis of pathologically changed tissues may shed some new light on processes leading to the degeneration of cells in the case of selected diseases. An ideal and powerful tool for such purpose is the Synchrotron Microbeam X-ray Fluorescence technique. It enables the carrying out of investigations of the elemental composition of tissues even at the single cell level.

The tissue samples for histopathological investigations are routinely fixed and embedded in paraffin. The authors try to verify the usefulness of such prepared tissue sections for elemental analysis with the use of X-ray fluorescence microscopy. Studies were performed on rat brain samples. Changes in elemental composition caused by fixation in formalin or paraformaldehyde and embedding in paraffin were examined.

Measurements were carried out at the bending magnet beamline L of the Hamburger Synchrotronstrahlungslabor HASYLAB in Hamburg.

The decrease in mass per unit area of K, Br and the increase in P, S, Fe, Cu and Zn in the tissue were observed as a result of the fixation. For the samples embedded in paraffin, a lower level of most elements was observed. Additionally, for these samples, changes in the composition of some elements were not uniform for different analyzed areas of rat brain.     

Interaction of a vinyl acetate—vinyl chloride based wetting binder with metal particles for magnetic recording

The interaction of two commercially available iron alloy particles with a wetting binder based on a vinyl chloride and vinyl acetate copolymer has been investigated. The interaction was studied using the techniques of flow microcalorimetry, X-ray photoelectron spectroscopy (XPS) and microelectrophoresis. The results obtained indicate that whereas both particles interact strongly with the wetting binder, particles of low nickel content are characterized by very high heats of interaction (about 37–47 kcal mol⁻¹). The adsorption on both particles appears to obey the Freundlich equation. Binder adsorption on particles results in the development of rather large zeta potentials in tetrahydrofuran solutions. XPS experiments are unable to provide any conclusive evidence for the interaction mechanism.     

The Sol-Gel Process as a Basic Technology for Nanoparticle-Dispersed Inorganic-Organic Composites

Nanoparticles containing hybrid materials became of interest for many areas in the last decade. The reason for this is the fact that, in addition to the molecular inorganic-organic hybrid network, the physical, electronical, optical or catalytical properties of nanoparticles resulting from the inorganic crystalline, glassy or metallic properties also can be used for the material tailoring. For this reason, a survey is given over some interesting developments. Furthermore, in case studies, examples are given for the effect of nanoparticles on the two component Ormosil type of hybrids composed of ethyl ortho-silicate (TEOS) and methylethoxy(methoxy)triethoxy silane (MTEOS, MTMOS). It was shown that the 6 nm SiO₂-containing nanocomposite hybrid sols can be dried in form of thick films up to 14 m after a one step dip-coating process and densified crack-free. This is attributed to the increase of relaxation ability and flexibility. This nanocomposite based on TEOS, MTEOS and particulate SiO₂ has been used to develop an industrial process for a new type of environmentally friendly glass fiber mat with a temperature resistance up to 600°C.     

Bench-Scale Testing of Zinc Ferrite Sorbent for Hot Gas Clean-up

Advanced integrated gasification combined cycle (IGCC) power generation systems require the development of high-temperature, regenerable desulfurization sorbents, which are capable of removing hydrogen sulfide from coal gasifier gas to very low levels. In this paper, zinc ferrites prepared by co-precipitation were identified as a novel coal gas desulfurization sorbent at high temperature. Preparation of zinc ferrite and effects of binders on pore volume, strength and desulfurization efficiency of zinc ferrite desulfurizer were studied. Moreover, the behavior of zinc ferrite sorbent during desulfurization and regeneration under the temperature range of 350-400℃are investigated. Effects of binders on the pore volume, mechanical strength and desulfurization efficiency of zinc ferrite sorbents indicated that the addition of kaolinite to zinc ferrite desulfurizer seems to be superior to other binders under the experimental conditions.     

Polypropylene as a potential matrix for the creation of shape stabilized phase change materials

Phase change materials, based on isotactic polypropylene (PP) blended with soft and hard Fischer−Tropsch paraffin wax respectively, were studied in this paper. DSC, DMA, TGA and SEM were used to determine the structure and properties of the blends. While paraffin waxes in the blend changed state from solid to liquid, the PP matrix kept the material in a compact shape. Strong phase separation was observed in both cases, which was more pronounced in the case of soft paraffin wax. Despite the fact that both grades of paraffin wax are not miscible with PP due to different crystalline structures, it was shown that the hard Fischer−Tropsch paraffin wax is more compatible with PP than the soft one. Both waxes plasticized the PP matrix. TGA showed that PP blended with the hard Fischer−Tropsch wax degrades in just one step, whereas blends containing soft paraffin wax degrade in two distinguishable steps. SEM exposed a completely different morphology for the two paraffin waxes and confirmed the lower compatibility of PP and soft paraffin wax. The soft and hard characters of the waxes were manifested in the viscoelastic properties, where the blends containing soft paraffin wax exhibited a lower elastic modulus than pure polypropylene, whereas the hard Fisher−Tropsch paraffin wax solidified the matrix. However, both kinds of blends were able to sustain the dynamic forces applied by the DMA within five cycle runs implying good shape stability.     

3,3-双(叠氮甲基)环氧丁烷-四氢呋喃共聚醚的合成及其链结构分析

３，３ 双（叠氮甲基）环氧丁烷 四氢呋喃共聚醚的合成及其链结构分析屈红翔冯增国谭惠民（北京理工大学化工与材料学院北京１０００８１）许保国周集义（化工部黎明化工研究院洛阳４７１００１）关键词叠氮粘合剂，阳离子开环共聚，序列长度，链节比，竞聚率将叠...     

Preparation and Characterization of Binder for Inorganic Composites Made from Amorphous Mineral Raw Material

The preparation and characterization of a composite binder made through a sol-gel route from an amorphous mineral raw material has been studied. The amorphous mineral raw material is alumino-silicate based but contains also alkaline earth and some transition metal oxides. A stable sol can be prepared by dissolving the raw materials in formic acid. The drying and heat treatment of the subsequent gel has been studied by thermogravimetry, nuclear magnetic resonance, infrared spectroscopy as well as X-ray diffraction studies. The different constituents of the raw material have shown to play a major role during the drying and heat treatment of the gels. The binding effect of the binder was evaluated to be good by studying paper-binder composites as well as wetting properties.     

Crystal structure of the lithium ion specific binder 1,3-bis(8-quinolyloxy)propane

The X-ray crystal structure of 1,3-bis(8-quinolyloxy)propane, monoclinic, space group C2/c(No. 15),a=25.367(4);b=4.923(5) andc=14.418(4)Å; =111.18(2)^o;Z=4 has been determined by direct methods. A final least squares refinement based on 812 observed reflections (I>2(I)) gave finalR values ofR _f=0.043 andR _w=0.034.     

Surface chemical and geometrical properties of pure copper powder intended for binder jetting and sintering

One novel important application of sinter-based additive manufacturing involving binder jetting is copper-based products. Three different variants of nominally pure copper powder having particle size distributions with D90 < 16, 22, or 31 μm were investigated in this study. The packing behavior and the flow properties using dynamic test and shear cell, as well as specific surface area were evaluated. The analyses employed illustrate the multidimensional complexity. Because different measurements capture different aspect of the powder, it is imperative to apply a characterization approach involving different methods. Surface chemical analysis by means of X-ray photoelectron spectroscopy (XPS) showed that all powder variants were covered by Cu₂O, CuO, and Cu (OH)₂, with Cu₂O being dominant in all cases. The finest powder with D90 < 16 μm tended to have higher relative amount of copper in divalent state. The average apparent oxide thickness estimated by XPS depth profiling showed that the two coarser variants had similar overall average oxide thickness, whereas the finest one possessed smaller oxide thickness. The surface chemistry of the powder grades is found to be related to their rheological behavior in dynamic condition. Considering the specific surface areas in combination with the average oxide thicknesses, the amount of surface bound oxygen was estimated to be about ~220 ppm for all three variants. Specific concerns need to be taken during the sintering of powder to keep oxygen level below that of electrolytic pitch copper (400 ppm).