Membrane-Active Peptides and the Clustering of Anionic Lipids

AbstractThere is some overlap in the biological activities of cell-penetrating peptides (CPPs) and antimicrobial peptides (AMPs). We compared nine AMPs, seven CPPs, and a fusion peptide with regard to their ability to cluster anionic lipids in a mixture mimicking the cytoplasmic membrane of Gram-negative bacteria, as measured by differential scanning calorimetry. We also studied their bacteriostatic effect on several bacterial strains, and examined their conformational changes upon membrane binding using circular dichroism. A remarkable correlation was found between the net positive charge of the peptides and their capacity to induce anionic lipid clustering, which was independent of their secondary structure. Among the peptides studied, six AMPs and four CPPs were found to have strong anionic lipid clustering activity. These peptides also had bacteriostatic activity against several strains (particularly Gram-negative Escherichia coli) that are sensitive to lipid clustering agents. AMPs and CPPs that did not cluster anionic lipids were not toxic to E. coli. As shown previously for several types of AMPs, anionic lipid clustering likely contributes to the mechanism of antibacterial action of highly cationic CPPs. The same mechanism could explain the escape of CPPs from intracellular endosomes that are enriched with anionic lipids

ИССЛЕДОВАНИЕ РЕЖИМНыХ ПАРАМЕТРОВ СЕПАРАТОРА СісП-1,4-МПт

В настоящее время для переработки техногенных месторождений, содержащих уголь, применяются обогатительные установки на базе пневматических сепараторов

Mindfulness-based cognitive therapy in obsessive-compulsive disorder – A qualitative study on patients’ experiences

BACKGROUND: Cognitive behavioral therapy (CBT) with exposure and response prevention (ERP) is the first-line treatment for patients with obsessive-compulsive disorder (OCD). However, not all of them achieve remission on a longterm basis. Mindfulness-based cognitive therapy (MBCT) represents a new 8-week group therapy program whose effectiveness has been demonstrated in various mental disorders, but has not yet been applied to patients with OCD. The present pilot study aimed to qualitatively assess the subjective experiences of patients with OCD who participated in MBCT. METHOD: Semi-structured interviews were conducted with 12 patients suffering from OCD directly after 8 sessions of a weekly MBCT group program. Data were analyzed using a qualitative content analysis. RESULTS: Participants valued the treatment as helpful in dealing with their OCD and OCD-related problems. Two thirds of the patients reported a decline in OCD symptoms. Benefits included an increased ability to let unpleasant emotions surface and to live more consciously in the present. However, participants also discussed several problems. CONCLUSION: The data provide preliminary evidence that patients with OCD find aspects of the current MBCT protocol acceptable and beneficial. The authors suggest to further explore MBCT as a complementary treatment strategy for OCD

Drivers of Change or Cut-Throat Competitors? Challenging Cultures of Innovation of Chinese and Nigerian Migrant Entrepreneurs in West Africa

L'afflux remarquable des entrepreneurs migrants chinois dans différents pays d'Afrique occidentale au cours des dernières années a été heurtée à une résistance de plus en plus farouche par des entrepreneurs locaux établis. Que le premiers ont un avantage concurrentiel sur ce dernier en raison de traits socio-culturels distinctifs, ou si l'efficacité supposée chinoise est juste une caractéristique de toutes les diasporas mercantiles, est ouvert à la question. Cette étude exploratoire des migrants entrepreneuriales chinois et nigérians au Ghana et au Bénin tente de répondre à cette question. Apparemment, les forces culturels des agents du changement migrants ne sont pas limités à des systèmes de valeurs héritées ou religions, comme une éthique protestante ou le confucianisme, mais ils sont adaptés en permanence et ont inventé de nouveau par des réseaux transnationaux de la migration dans un monde globalisé. Il n'y a aucune preuve d'une prétendue supériorité de la culture d’innovation chinois par rapport aux cultures d’innovation africains des migrants entrepreneuriales. Plutôt, il existe une capacité accrue d'innovation d'une diaspora mercantile en général vis à vis des entrepreneurs locaux, indépendamment de l'origine de la culture nationale dans lequel il est intégré. En outre, la rivalité des entrepreneurs migrants chinois et nigérians dans les marchés africains ne conduit pas nécessairement à la concurrence coupe-gorge souvent suspectée sous l'impact de la mondialisation. Souvent, les deux groupes agissent plutôt complémentaires. Cela contribue, sous certaines conditions, même à la réduction de la pauvreté dans le pays d'accueil

Liebfrauenkirche

interior, vaulting of first chape

C/C-SiC telescope structure for the laser communication terminal in TerraSAR-X

In the frame of global networking, the modern information society is requiring faster and faster exchange of data. Thereby, conventional microwave technologies are touching their technological and economical limits. Laser communication terminals (LCT) based on optical high speed satellite links offer new possibilities for a technology leap in data exchange rates. Thereby, data links of 4 to 10 GBit/s have been in the focus of the development for the last 30 years. Due to the high frequency of light of about 500 THz (microwave < 10 GHz) and the very low wavelengths, highest data transmission rates at low power consumption can be build up at very large distances, using optical data transmission systems. Additionally, the divergence of the transmitting laser beam is significantly lower and the antenna gain is some orders of magnitude higher compared to microwave technology, leading to compact systems with low masses and volume. The current highlights in LCT development are the data links built up between the German satellite TerraSAR-X and the U.S. satellite NFIRE as well as between TerraSAR-X and the ground station at DLR in Oberpfaffen-hofen, both links built up in 2008 initially. Thereby, using a diode pumped laser beam with a wavelength of 1064 nm and a transmission power of only 1 W, bidirectional data links with a transmission rate of 5.5 GBit/s could be built up between the LEO satellites flying at an altitude of about 500 km, a distance of 5 000 km and a relative velocity of 25 000 km/h [1] as well as to the ground station at distances of 500 to 2 000 km. This equals a data transfer of about 200 000 DIN A4 pages/s or 400 DVD/hour, which is about 20 times faster compared to state of the art microwave technology. The technological challenge of LCT systems is the extremely high accuracy, requiring highly precise telescope structures (fig. 1and 2) for long term operation (> 5 years) in space environment. The main task of the telescope structure is the accurate positioning of the mirrors in order to minimise angular deviations of the receiving (RX) and transmitting (TX) laser beam, ensuring a reliable data transfer. Main sources for possible deviations are deformations of the telescope, caused by thermal expansion due to solar irradiation, or by vibrations, induced by different sources in the satellite. To obtain this extremely high accuracy of telescope structures, e.g. made of lightweight aluminium, active heating/cooling systems are needed in order to stabilize the temperature and finally the geometry of the structure. To avoid or reduce the high cost and masses of these tempering systems, passive telescope systems based on thermally stable materials are favoured. INVAR and Zerodur are typical representatives of materials, offering very low or zero CTE (table 1). However, the relatively high densities of these materials lead to high structural masses. Additionally, Zerodur is a very brittle ceramic material, leading to high machining costs. As a typical Weibull material, the reliability of Zerodur structures is decreasing with increasing volume or sur-face of the structure. Therefore, large structures require high wall thick-nesses, again leading to high masses. Another possible candidate is carbon fibre reinforced plastic (CFRP), offering very low density (CFRP 1.5 g/cm³) and high specific stiffness. However, due to the polymer matrix, the long term stability in space is critical. Additionally, swelling, caused by humidity, leads to changes in geometry during assembly and orbit release. Carbon fibre reinforced Carbon (C/C) offers low density and high stiffness as well as insensitivity to humidity. Main disadvantages are its generally high open porosity of about 10 %, making cleaning processes difficult and leading to particle release. At DLR, C/C-SiC materials, manufactured via the LSI (liquid silicon infiltra-tion) process originally have been developed for lightweight structures in thermal protection systems of reusable spacecraft [2]. Thereby, in the first process step, a preform made of carbon fibre reinforced plastics (CFRP) is manufactured via well known technologies like resin transfer moulding (RTM) autoclave technique or warm pressing. In the second step, the CFRP preform is prolysed at temperatures of up to 1650 °C in inert gas atmos-phere, leading to a highly porous carbon fibre reinforced carbon (C/C) preform. In the third and last process step, molten silicon is infiltrated in the C/C preform by capillary forces only. Parallel to the infiltration, the silicon reacts with a small amount of the C-matrix and C-fibres, forming SiC. The resulting C/C-SiC material is characterized by dense bundles of C-fibres embedded in C-matrix, again embedded in a dense SiC matrix with a small amount of not converted, free Si. In contrast to monolithic ceramics, C/C-SiC materials offer a high damage tolerance and a quasiductile fracture behaviour, comparable to grey cast iron. Thereby, large and thin walled, light weight structures can be realized at reasonable cost. Due to the high content of carbon fibres in the CFRP (F = 50 – 60 Vol.-%) and C/C perform, which are protected against Si attack very well, the properties of the C/C-SiC materials are generally dominated by the C-fibres. Thereby, C/C-SiC materials based on laminated C-fibre fabrics show an highly anisotropic material behaviour, offering relatively high strength and Young`s modulus in the in plane direction, parallel to the fibres. For the same reason, the CTE of the C/C-SiC XB material, based on high tenacity C-fibres (Tenax HTA), is generally very low in the in plane direction (-0.2 to +2.5 x 10-6 K-1 between 0 and 1500°C, depending on SiC content [3]), whereas significantly higher values of 2 to 7 x 10-6 K-1 are obtained in the direction perpendicular to the fibre orientation