Optical properties of highly transparent polypropylene cast films: Influence of material structure,additives, and processing conditions

Polypropylene homopolymers and ethylene/propylene‐random‐copolymers formulated with and without anti‐blocking additives were extruded to cast films with an industrial scale extruder equipped with a soft box, a specific air knife that expels a higher volume of air at lower velocity. The films were analyzed as to their optical properties haze and clarity. A comprehensive topographical characterization was performed using atomic force microscopy (AFM) and confocal microscopy. To obtain morphological information on a nanometer scale AFM phase imaging, micro‐thermal analysis and small angle X‐ray scattering (SAXS) were done. A significant effect of additives and processing conditions on the film topography and the optical properties was revealed. The films without anti‐blocking and antacid aids showed the best optical properties and lowest vertical roughness fluctuations. In contrast, the addition of anti‐blocking and antacid aids reduced the optical properties associated with an increase in surface roughness. While for films without anti‐blocking aids an enhanced soft box condition resulted in lower vertical fluctuations of roughness and better optical properties, the behavior was in reverse for films with anti‐blocking aid. By means of SAXS crystalline lamellae with a thickness of about 2.5 nm were detected. High‐resolution phase imaging AFM yielded thicker crystal lamellae on the film surface. POLYM. ENG. SCI., 46:520–531, 2006. © 2006 Society of Plastics Engineers.     

Avalanche‐Discharge‐Induced Electrical Forming in Tantalum Oxide‐Based Metal–Insulator–Metal Structures

Oxide‐based metal–insulator–metal structures are of special interest for future resistive random‐access memories. In such cells, redox processes on the nanoscale occur during resistive switching, which are initiated by the reversible movement of native donors, such as oxygen vacancies. The formation of these filaments is mainly attributed to an enhanced oxygen diffusion due to Joule heating in an electric field or due to electrical breakdown. Here, the development of a dendrite‐like structure, which is induced by an avalanche discharge between the top electrode and the Ta₂O_5‐x layer, is presented, which occurs instead of a local breakdown between top and bottom electrode. The dendrite‐like structure evolves primarily at structures with a pronounced interface adsorbate layer. Furthermore, local conductive atomic force microscopy reveals that the entire dendrite region becomes conductive. Via spectromicroscopy it is demonstrated that the subsequent switching is caused by a valence change between Ta⁴⁺ and Ta⁵⁺, which takes place over the entire former Pt/Ta₂O_5‐x interface of the dendrite‐like structure.     

Uranium sorption on various forms of titanium dioxide--influence of surface area, surface charge, and impurities

Titanium dioxide (TiO(2)) has often served as a model substrate for experimental sorption studies of environmental contaminants. However, various forms of Ti-oxide have been used, and the different sorption properties of these materials have not been thoroughly studied. We investigated uranium sorption on some thoroughly characterized TiO(2) surfaces with particular attention to the influence of surface area, surface charge, and impurities. The sorption of U(VI) differed significantly between samples. Aggressive pretreatment of one material to remove impurities significantly altered the isoelectric point, determined by an electroacoustic method, but did not significantly impact U sorption. Differences in sorption properties between the various TiO(2) materials were related to the crystallographic form, morphology, surface area, and grain size, rather than to surface impurities or surface charge. In-situ attenuated total reflection Fourier-transform infrared (ATR FT-IR) spectroscopic studies showed that the spectra of the surface species of the TiO(2) samples are not significantly different, suggesting the formation of similar surface complexes. The data provide insights into the effect of different source materials and surface properties on radionuclide sorption.     

Antibiotic resistance in bacteria isolated from vegetables with regards to the marketing stage (farm vs. supermarket)

The aim of this study was to elucidate whether and to what extent fresh produce from Germany plays a role as a carrier and reservoir of antibiotic resistant bacteria. For this purpose, 1001 vegetables (fruit, root, bulbous vegetables, salads and cereals) were collected from 13 farms and 11 supermarkets in Germany and examined bacteriologically. Phenotypic resistance of Enterobacter cloacae (n = 172); Enterobacter gergoviae (n = 92); Pantoea agglomerans (n = 96); Pseudomonas aeruginosa (n = 295); Pseudomonas putida (n = 106) and Enterococcus faecalis (n = 100) against up to 30 antibiotics was determined by using the microdilution method. Resistance to ß-lactams was most frequently expressed by P. agglomerans and E. gergoviae against cefaclor (41% and 29%). Relatively high resistance rates were also observed for doxycycline (23%), erythromycin (21%) and rifampicin (65%) in E. faecalis, for spectinomycin (28%) and mezlocillin (12%) in E. cloacae, as well as for streptomycin (19%) in P. putida. In P. aeruginosa, relatively low resistance rates were observed for the aminoglycosides amikacin, apramicin, gentamicin, neomycin, netilmicin and tobramycin (< 4%); 11% was resistant to streptomycin. No glycopeptide-resistant enterococci were observed. Resistance rates of bacteria isolated from farm samples were higher than those of the retail markets whenever significant differences were observed. This suggests that expressing resistance is at the expense of bacterial viability, since vegetables purchased directly at the farm are probably fresher than at the supermarket, and they have not been exposed to stress factors. However, this should not keep the customer from buying directly at the farm, since the overall resistance rates were not higher than observed in bacteria from human or animal origin. Instead, peeling or washing vegetables before eating them raw is highly recommended, since it reduces not only the risk of contact with pathogens, but also that of ingesting and spreading antibiotic resistant bacteria.     

Bioluminescent Optogenetics: A Novel Experimental Therapy to Promote Axon Regeneration after Peripheral Nerve Injury

Functional recovery after peripheral nerve injury (PNI) is poor, mainly due to the slow and incomplete regeneration of injured axons. Experimental therapies that increase the excitability of the injured axons have proven remarkably successful in promoting regeneration, but their clinical applicability has been limited. Bioluminescent optogenetics (BL-OG) uses luminopsins, fusion proteins of light-generating luciferase and light-sensing ion channels that could be used to increase neuronal excitability if exposed to a suitable substrate. Excitatory luminopsins were expressed in motoneurons of transgenic mice and in wildtype mice transduced with adeno-associated viral vectors. Intraperitoneal administration of coelenterazine (CTZ), a known luciferase substrate, generated intense bioluminescence in peripheral axons. This bioluminescence increased motoneuron excitability. A single administration of CTZ immediately after sciatic nerve transection and repair markedly enhanced motor axon regeneration. Compound muscle action potentials were 3–4 times larger than controls by 4 weeks after injury. The results observed with transgenic mice were comparable to those of mice in which the luminopsin was expressed using viral vectors. Significantly more motoneurons had successfully reinnervated muscle targets four weeks after nerve injury in BL-OG treated mice than in controls. Bioluminescent optogenetics is a promising therapeutic approach to enhancing axon regeneration after PNI.     

Apolipoprotein AI-CIII, B, and CII gene polymorphisms in patients with non-insulin dependent diabetes mellitus. Association with hyperlipemia

BACKGROUND: Dislipidaemia is an usual feature in patients affected by non insulin dependent diabetes mellitus. Several studies show that this disease could be genetically determined. The aim of this study was to ascertain whether any of the genetic polymorphism remaining in three apolipoprotein loci (apolipoprotein AI-CIII, B100 and CII) is related with the presence of dislipidaemia in non insulin dependent diabetes mellitus patients. PATIENTS AND METHODS: 53 non insulin dependent diabetes mellitus patients with less than 5 years evolution and treated only with diet, were included. 86 healthy persons were included as the control group. The lipidic parameters analyzed were: cholesterol, LDL cholesterol, HDL cholesterol, triglycerides, apolipoprotein AI, B and lipoprotein (a). The following polymorphic variants were analyzed: RFLP-Sacl of the apolipoprotein AI-CIII-AIV cluster, RFLP-Xbal of the apolipoprotein B100 region and the RFLP-Taql of the apolipoprotein E-CI-CII cluster. RESULTS: There were no genetic nor allelic differences in the distribution of the genes, between controls and diabetic patients. Regarding the apolipoprotein CII gen, the diabetic patients with the T2T2 genotype had higher triglyceride levels (p < 0.01) compared with the remaining genotypes and compared with the control group having the same genotype (p < 0.01) matched for sex, age and body mass index. There was no difference in the metabolic parameters' distribution related to the genotypic distribution of the apolipoproteins AI-CIII and B100 genes. CONCLUSIONS: The apolipoprotein CII can be related with the presence of hypertriglyceridaemia in non insulin dependent diabetes mellitus patients.     

A comparative analysis of EIA practice for wastewater treatment plants in great Britain and Germany

This article reports the findings of an investigation of the practice of environmental impact assessment (EIA) for wastewater treatment plants in the United Kingdom and Germany. It demonstrates that both EIA systems have a number of common deficiencies but that the differences between the practice of EIA in Britain and Germany are considerable. These indicate that one of the objectives of the European Directive—to harmonize environmental controls—has not been met. The differences can be explained by examining: (1) the context in which EIAs for wastewater treatment plants take place in both countries; (2) the ways in which EIA procedures are implemented in both countries; and (3) the attitudes of the competent authorities in both countries to EIA.     

Trends in the production and storage of fresh meat – the holistic approach to bacteriological meat quality

The aim of this review paper is to introduce readers to the modern approach to meat production as recommended by public authorities. No part of the food chain can be regarded alone but has to be seen as part of the whole. A holistic approach to fresh meat storage and retailing must therefore start with the living animal and cannot end with the sale of the meat. It must also include the consumers. One of the highest priority issues for consumers, producers and governments is food safety, and with it, consumer safety. Here we briefly describe the possibilities of keeping initial amounts of bacteria in meat low and modern storage of fresh meat. In future, the consumer must be incorporated in the meat food chain.     

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