Hydroxyapatite as a filler for biosynthetic PHB homopolymer and P(HB–HV) copolymers

This paper deals with some of the fundamental problems encountered when using a semicrystalline polymer as the matrix phase for a particulate‐filled composite. As our model system we adopted poly‐(R)‐3‐hydroxybutyrate, PHB, and two copolymers of (R)‐3‐hydroxybutyrate and (R)‐3‐hydroxyvalerate, P(HB–HV), for the matrix phase, and the mineral calcium hydroxyapatite as a particulate filler. The structure and properties of compression‐moulded films of various compositions were investigated by polarized light microscopy, wide‐angle X‐ray scattering and mechanical testing. It was found that the degree of crystallinity of the matrix was lower in filled samples, and that the spherulitic crystallization of the matrix appeared to cause the filler particles to form agglomerates, which would not be as effective a reinforcement as finely dispersed primary filler particles. The tensile strength, strain‐to‐break and tensile modulus of samples of different compositions were analysed using well‐known theories for composite behaviour. Copyright © 2003 Society of Chemical Industry     

络合剂在优化纺织品湿加工整理中的应用

新型络合剂在多种工序中的应用,可以为单道工序甚至整个生产过程节约大量成本,加速生产循环,省去部分加工步骤,同时还提高了不稳定配方的生产可靠性.极简化的操作水平也可以节约大量能源.现代技术和设计应将络合剂作为重要的过程控制参数,因为这关系到整个工艺的成败.     

A novel extraction method for peanut allergenic proteins in chocolate and their detection by a liposome-based lateral flow assay

In this study, conditions for extracting the major peanut allergen (Ara h1) from chocolate were optimized, and the extracted samples were analyzed by a lateral flow assay (LFA) using liposomal nanovesicles. The optimal conditions using peanut-spiked chocolate were found to be extraction with a mixture of phosphate buffered saline and hexane for 30 min at 35 °C. After centrifugation, the buffer portion was treated with insoluble poly(vinylpolypyrrolidone) to remove phenolic compounds, and then analyzed by the LFA. The entire analysis, including sample preparation and LFA, could be easily completed within 2 h, and the detection limit was 158 g of peanuts/g of chocolate.     

Is there a future for antioxidants in atherogenesis?

Antioxidants, preferentially those of dietary origin, have for a long time been considered to help against diseases that are presumably aggravated by oxidative stress, such as cardiovascular diseases, cancer, and neurodegenerative disorders. The outcome of clinical trials undertaken to corroborate this hypothesis, however, remained largely inconclusive. Evidence is now emerging that some dietary "antioxidants" influence signaling pathways and the expression of genes relevant in atherosclerosis by mechanisms other than antioxidative ones. By concrete examples we show that (1) vitamin E has gene regulatory functions which might be more important than acting as an antioxidant in vivo, (2) selenium itself is not an antioxidant at all, and even not in general when incorporated into glutathione peroxidases, and (3) a moderate oxidative stress is beneficial rather than detrimental since it can induce defense mechanisms counteracting xenobiotic and oxidative stress. Thus, there is only a future for antioxidants in the prevention of any disease if their real mechanism of action is considered and suitable read-outs and biomarkers are established.     

Present aspects of bacterial endocarditis in infants and children. Observation during the years 1969-1976 (author's transl)

21 infants and children with proven bacterial endocarditis were observed at the Unviersity Children Hospital of Düsseldorf from January 1969 to December 1976. There was high incidence of cases in the infant group and again among the 6 to 8 years old children. Some important aspects of the disease were characteristic for the infant group (N=5): No congenital cardiac abnormality was present, but a surgical cerebro-atrial connection in two cases of hydrocephalus and a prolonged artifical respiration in a third patient could have been predisposing factors. Staphylococci were the pathologic organisms in three infants. The course of the disease consistently resembled that of septicemia and the outcome was always lethal. The diagnosis of bacterial endocarditis was disclosed only by the post mortem examination. The mitral and the tricuspid valves were affected twice respectively, the pulmonary cusps only once. In the children group (N=16) fifteen patients had a congenital malformation of the heart confirmed by previous catheterization. 8 were cyanotic and 5 of them had a tetralogy of Fallot with previous aorto-pulmonary shunting procedure (Waterston). Unlike the spectrum of micro-organisms presently found in adults, the streptococcus viridans prevailed as before, it was isolated in 11 of the 13 blood cultures which yielded positive results. The disease displayed a subacute course and mortality remained with 3 deaths relatively low. In 3 other cases a valve lesion subsisted, in two instances severe enough to necessitate surgery (aortic valve prosthesis, mitral annular narrowing). No relapse was observed during the mean follow up period of 2;8 years.     

Bestandsaufnahme Grundwasser nach der EU-Wasserrahmenrichtlinie im Koordinierungsraum Mulde-Elbe-Schwarze Elster

Die Wasserrahmenrichtlinie regelt den Schutz von Grund- und Oberflächengewässern und fordert eine nachhaltige Wassernutzung. Sie legt einen Zeitplan fest, um bis zum Jahr 2015 für alle Gewässer einen guten Zustand zu erreichen. Der erste Schritt ist eine Bestandsaufnahme der Gewässer. Für das Grundwasser besteht diese aus einer erstmaligen Beschreibung, einer weitergehenden Beschreibung und der Prüfung der Auswirkungen menschlicher Tätigkeit auf das Grundwasser. Die Wasserrahmenrichtlinie wird unabhängig von administrativen Grenzen innerhalb von hydrologischen Einzugsgebieten umgesetzt. Im deutschen Teil des Flusseinzugsgebietes der Elbe wurden 5 Koordinierungsräume gegründet. Der Koordinierungsraum Mulde-Elbe-Schwarze Elster (MES) wird vorgestellt. Beispielhaft für die angewandten Methoden wird die Beurteilung diffuser Stoffeinträge in das Grundwasser bei der erstmaligen Beschreibung erläutert. Die Ergebnisse der Bestandsaufnahme Grundwasser im Koordinierungsraum MES werden präsentiert. Von 54 Grundwasserkörpern ist für 25 Körper aufgrund der Belastungen durch Punktquellen und diffuse Quellen, wegen des mengenmäßigen Zustands oder sonstiger anthropogener Einwirkungen die Zielerreichung nach der Wasserrahmenrichtlinie unklar/unwahrscheinlich.     

景观设计展望:国际性和中国特色

中国的当代景观设计仍然在传统的范例和国际的范例之间探寻其自己的风格。北京土人景观规划设计研究院所做的项目展示了当代的、同时又是自己的设计语言,彰显了全球化背景下当代中国人的身份。     

Influence of electron irradiation on the crystallisation,molecular weight and mechanical properties of poly-(<Emphasis Type="Italic">R</Emphasis>)-3-hydroxybutyrate

Biosynthetic poly[(R)-3-hydroxybutyrate] (PHB) undergoes a deleterious ageing process which has been attributed to progressive crystallisation. In this work an attempt has been made to arrest this crystallisation behaviour by an irradiation treatment which is known to induce cross-linking in many polymers. PHB films were irradiated with different doses of electrons and at different times after the initiation of crystallisation. The degree of crystallinity was subsequently determined as a function of time after irradiation using wide-angle X-ray scattering measurements. In addition, melting endotherms were obtained by differential scanning calorimetry (DSC) and molecular weights by gel permeation chromatography (GPC). Corresponding tensile stress–strain experiments were performed in order to obtain information on the mechanical properties of the sample films. The melting point and molecular weights were found to decrease linearly with radiation dose indicating that higher radiation doses cause degradation due to chain scission. However, lower doses applied to samples still in their amorphous state indicate a high degree of cross-linking, in which a network is formed and the ageing process can be prevented to some extent. The tensile modulus and breaking strain were influenced strongly by the point in time at which the material was irradiated during crystallisation.     

Steroid conjugates of dichloro(6-aminomethylnicotinate)platinum(II): effects on DNA, sex hormone binding globulin, the estrogen receptor, and various breast cancer cell lines

Esters of 6-aminomethylnicotinic acid with various steroidal alcohols were treated with K(2)PtCl(4) to give the N,N-chelated dichloroplatinum(II) complex conjugates 4. Their interaction with plasmid DNA was monitored by electrophoretic mobility measurements. Their affinities towards sex hormone binding globulin (SHBG) and towards the nuclear estrogen receptor ER(alpha) were assessed by competitive displacement radioassays. The inhibitory effect of 4 on breast tumour cells MCF-7 ER(+)/ER(-) and MDA-MB-231 was investigated in vitro. Conjugates with 3-O-linked estrogens 4 a,b or 17-O-linked androgens 4 g bound strongly to SHBG. The conjugate complex 4 b, featuring a 3-O-linked estradiol, also bound strongly and agonistically to the estrogen receptor. It also elicited distinct growth retardation of MCF-7 (ER(+)) cells, presumably by a mechanism different from that of cisplatin.