Investigating the Integration of Nonwoven Carbon Fibers for Mechanical Enhancement in Compression Molded Fiber-Reinforced Polymer Bipolar Plates.

The demand for polymer composite solutions in bipolar plates for polymer electrolyte membrane fuel cells (PEMFCs) has risen due to advantages over metal plates such as longer lifetime, weight reduction, corrosion resistance, flexible manufacturing, freedom of design, and cost-effectiveness. The challenge with polymer composites is achieving both sufficient electrical conductivity and mechanical stability with high filler content. A carbon fiber fleece as reinforcement in a graphite-filled polypropylene (PP) matrix was investigated for use as bipolar plate material with increased mechanical and sufficient conductive properties. Plates with a thickness of 1 mm containing four layers of fleece impregnated in the PP-graphite compound were produced in a compression molding process. Particle and fiber interactions were investigated via microscopy. The plates were characterized with respect to the electrical conductivity and mechanical stability. High electric conductivity was reached for fiber-reinforced and plain PP-graphite compound plates, with increased filler content leading to a higher conductivity. The contact resistance remained largely unaffected by surface etching as no polymeric skin layer formed during compression molding. Fiber-reinforced plates exhibit twice the tensile strength, a significantly higher tensile modulus, and an increased elongation at break, compared to PP filled only with graphite.

High-Precision Thin Wall Bipolar Plates for Fuel Cell Applications via Injection Compression Molding with Dynamic Mold Temperature Control.

In recent years, the demand for polymer compound solutions for the application of bipolar plates in polymer electrolyte membrane fuel cells (PEMFC) has increased continuously due to significant cost and lifetime advantages compared to metallic solutions. The main challenge of the compounds is the high filler content required to ensure sufficient electrical conductivity of the bipolar plates. The associated increase in viscosity and simultaneously increased thermal conductivity limit the conventional injection molding process in terms of achievable flow path length to wall thickness ratios (plate aspect ratio). In order to evaluate the extent to which highly modified electrically conductive polymer material systems can be processed into thin-walled and highly dimensionally stable bipolar plates, an injection compression molding process with dynamic mold temperature control (ICM-DT) has been developed. For this purpose, a compound was prepared from polypropylene (PP) and graphite-flakes. The compound was characterized with respect to the achieved filler content, the electrical conductivity, as well as the pressure- and temperature-dependent solidification range. The ICM-DT experiments were carried out by varying the maximum mold temperature and the compression force. In addition, the process was designed with multiple compression and decompression steps to account for a possible pressure-dependent solidification of the compound. The plates were characterized with respect to the achieved plate aspect ratio and the flow-path-dependent dimensional thickness stability. It was shown that the plate aspect ratio could be increased by up to 125% with the maximum filler content compared to conventional injection molding processes provided in the literature. With the multi-stage ICM-DT process, it was also possible to optimize the thickness dimensional stability with a maximum deviation of 3% over the flow path.

Perceived environmental barriers for people with spinal cord injury in Germany and their influence on quality of life.

OBJECTIVE: The German Spinal Cord Injury Survey is part of the International Spinal Cord Injury Survey, which aims to collect data about the life experience of persons with spinal cord injury worldwide. This paper reports on the perceived environmental barriers of the German study population and their associations with quality of life. DESIGN: Cross-sectional explorative observational study using survey data. PARTICIPANTS: A total of 1,479 persons with spinal cord injury aged 18 years and older. METHODS: After descriptive analyses, exploratory factor analysis was used to build groups of environmental barriers. Logistic regressions were performed to assess correlates of perceived environmental barriers. Spearman's correlations were used to analyse the association between perceived barriers and quality of life. RESULTS: Barriers regarding infrastructure had a relatively large impact. Barriers in relation to people's attitudes towards spinal cord injury and the equipment of people with spinal cord injury had a relatively small impact on the lives of people with spinal cord injury. Several subpopulations showed a higher risk in experiencing barriers. Quality of life decreased with increasing experience of barriers. CONCLUSION: The most life-hardening barriers were identified related to infrastructure, a category in which most barriers are modifiable, for example, buildings or transportation.

[Spinal Cord Injury in Germany - a Survey on the Living and Care Situation of People with Spinal Cord Injury]. / Querschnittlähmung in Deutschland ­ eine Befragung zur Lebens- und Versorgungssituation von Menschen mit Querschnittlähmung.

PURPOSE: Multiple organizations like UN and WHO call for the collection of internationally comparable data on living and supply conditions of people with disabilities. Furthermore, reliable national data are necessary for ensuring appropriate care. Regarding patients with Spinal Cord Injury (SCI) in Germany, only data on diagnostics or therapeutic interventions is currently available. The International Spinal Cord Injury Survey aims at collecting reliable data of people with SCI in 21 countries and developing recommendations for actions to be taken by policy-makers and other decision-makers. METHODS: In 2017, eight specialized SCI-centers across Germany sent a standardized questionnaire to their patients who had diagnosis of SCI, and were older than 18 years (n=5,598). The questionnaire could be completed paper-based or online. RESULTS: 1,479 patients participated in the study and were included in data analysis. On average, participants were 55.3 years (SD=14.6) old, ¾ were male. The mean time of onset of paralysis was 13.9 years. Two thirds of the spinal cord injury causes were traumatic. In 51.2% SCI was classified as paraplegia. The most frequently cited health problem was sexual dysfunction. Medical treatment for this problem was rarely used. Serious environmental barriers were the inadequate accessibility of private households and public places. 42.5% of the respondents in working age were employed, which is 10% less than in Switzerland. DISCUSSION: Serious problems in environmental barriers, medical care and labor market participation were identified for people with SCI. The results will be reported to and discussed with political decision makers and further actors to create solutions. This requires extensive efforts, like modification in building law and home support.

Plasmid-Mediated Transmission of KPC-2 Carbapenemase in Enterobacteriaceae in Critically Ill Patients.

Carbapenem-resistant Enterobacteriaceae (CRE) cause health care-associated infections worldwide, and they are of severe concern due to limited treatment options. We report an outbreak of KPC-2-producing CRE that was caused by horizontal transmission of a promiscuous plasmid across different genera of bacteria and hospitals in Germany. Eleven isolates (8 Citrobacter freundii, 2 Klebsiella oxytoca, and 1 Escherichia coli) were obtained from seven critically ill patients during the six months of the outbreak in 2016. One patient developed a CRE infection while the other six patients were CRE-colonized. Three patients died in the course of the hospital stay. Six of the seven patients carried the same C. freundii clone; one K. oxytoca clone was found in two patients, and one patient carried E. coli and C. freundii. Molecular analysis confirmed the presence of a conjugative, bla KPC-2-carrying 70 kb-IncN plasmid in C. freundii and E. coli and an 80 kb-IncN plasmid in K. oxytoca. All transconjugants harbored either the 70 or 80 kb plasmid with bla KPC-2, embedded within transposon variant Tn4401g. Whole genome sequencing and downstream bioinformatics analyses of all plasmid sequences showed an almost perfect match when compared to a bla KPC-2-carrying plasmid of a large outbreak in another German hospital two years earlier. Differences in plasmid sizes and open reading frames point to the presence of inserted mobile genetic elements. There are few outbreak reports worldwide on the transmission of bla KPC-2-carrying plasmids across different bacterial genera. Our data suggest a regional and supraregional spread of bla KPC-2-carrying IncN-plasmids harboring the Tn4401g isoform in Germany.

Modified primers for rapid and direct electrochemical analysis of coeliac disease associated HLA alleles.

Direct detection of PCR product via hybridisation assay, would facilitate the development of rapid tools for genetic analysis. Here, a PCR primer designed to generate a PCR amplicon tagged with single stranded DNA tails at each end of the duplex, which can be used for direct hybridisation with a surface immobilised probe and an enzyme labelled reporter probe is presented. Four modified sequence specific primers (SSP) pairs were designed for the selective amplification of coeliac disease associated alleles (DQA1*05, DQB1*02, DQB1*03:02 alleles), and human growth hormone (positive control). Multiplex PCR products were electrochemically detected in less than 5 min at 37 °C via direct hybridisation to short probes immobilised on individual electrodes of a genosensor array, and subsequent hybridisation to an enzyme labelled reporter probe. The developed electrochemical genosensor array exploiting the modified primers for the direct detection of PCR products was applied to the genotyping of real patient samples.

The proteome of the bacterium Mycoplasma pneumoniae: comparing predicted open reading frames to identified gene products.

An existing proteome map of the bacterium Mycoplasma pneumoniae comprising proteins from 224 genes was extended to 305 genes. This corresponds to about 44% of the 688 proposed genome sequence derived open reading frames (ORFs). The newly assigned gene products were enriched, separated by one-dimensional or two-dimensional (2-D) gel electrophoresis and identified by mass spectrometry. The enrichment procedures included differential centrifugation, anion and cation exchange chromatography, affinity chromatography with heparin as a ligand and isolation of biotinylated proteins by binding to immobilized streptavidin. A comparative analysis of the identified proteins from 305 genes with the as yet unverified 383 ORFs concerning isoelectric point, molecular weight and number of transmembrane segments revealed that proteins with more than three predicted transmembrane segments and an isoelectric point above 10.5 are most likely not to be separated by 2-D gel electrophoresis. The mutual benefits of genomics and proteomics were shown by the identification of a todate unannotated 128 amino acid long protein.