Gezielte Nutzung biologischer Systeme

Directed exploitation of biological systems . During the past few decades, our knowledge of molecular process responsible for genetics has increased dramatically. Discovery of the giant molecule deoxyribonucleic acid – abbreviated as DNA – as the carrier of genetic information heralded in a development which nowadays permits us to effect directed changes in the genetic material of an organism. Thus we can provide easily cultured microorganisms with genes which were previously located in a completely different genetic environment. This helps us to obtain high yields of proteins or other substances which were formerly very difficult to obtain. Higher organisms such as animals and plants can also undergo modification of their genetic equipment. This adds a new dimension to the breeding of such species. Above all, genetic engineering provides new insights into the enormously complex interplay of molecules which go to make up a living cell. The resulting understanding of life processes on a molecular level permits recognition of malfunction and therapy of the ensuring disease by new drugs. In addition to these positive aspects, genetic engineering provides scope for conducting experiments whose ethical implications demand very earnest consideration.     

Cold drawing of polyethylene terephthalate/polyethylene films

Films made from a 77/23 weight percent polyethylene terephthalate/polyethylene blend were stretched using an Instron apparatus. The structures of the samples were examined by methods which included ion beam etching and electron microscopy. The drawn samples exhibited a metallically lustrous and highly reflective surface up to a draw temperature, T_R, of 70°C and a draw ratio of about 5. Under certain conditions the change in structure caused by the stretching resulted in the formation of a highly uniform fibril-void structure. The voids are up to 3 μm in width and 160 μm in length and are formed primarily as a result of aggregation and then separation of the microfibrils of the individual polymer components.     

New inhibitors of the Tat-TAR RNA interaction found with a "fuzzy" pharmacophore model

TAR RNA is a potential target for AIDS therapy. Ligand-based virtual screening was performed to retrieve novel scaffolds for RNA-binding molecules capable of inhibiting the Tat-TAR interaction, which is essential for HIV replication. We used a "fuzzy" pharmacophore approach (SQUID) and an alignment-free pharmacophore method (CATS3D) to carry out virtual screening of a vendor database of small molecules and to perform "scaffold-hopping". A small subset of 19 candidate molecules were experimentally tested for TAR RNA binding in a fluorescence resonance energy transfer (FRET) assay. Both methods retrieved molecules that exhibited activities comparable to those of the reference molecules acetylpromazine and chlorpromazine, with the best molecule showing ten times better binding behavior (IC50 = 46 microM). The hits had molecular scaffolds different from those of the reference molecules.     

Hybrid systems in seawater desalination—practical design aspects, present status and development perspectives

Ever since seawater desalination has been applied on an industrial scale, and particular in the countries of the Arabian Gulf, the application of desalination processes in dual-purpose facilities—water and power—as a hybrid configuration has been discussed in many feasibility investigations and also planning concepts. It is above all the combination of reverse osmosis with thermal processes that has found increasing interest with the aim of ensuring, as economically as possible, uniform water supplies under the specific, greatly varying load conditions in the Gulf countries. Such design concepts for hybrid configurations encompass straightforward structures with a low degree of coupling between membrane and thermal desalination processes, but range up to very complex configurations with strong interconnections on both the water side and thermally, as well as with several desalination processes connected in series or in parallel. Classical hybrid concepts in which the permeate from an RO desalination component is mixed with distillate from thermal desalination have already been implemented in Saudi Arabian dual-purpose plants, like Jeddah and Yanbu-Medina. Although hybrid systems of greater complexity have been addressed in many design studies and publications, up to now none has been brought to fruition. Coming into consideration asthe design basis for determining the capacity shares of the various desalination processes operated in a hybrid configuration are: arrangement of thermal cycle of the power plant component; water/power ratio of the dual-purpose seawater desalination and power plant; provision of undiminished water production of the desalination plant as electricity generation varies; provision of a specified drinking water quality with regard to composition and salt content; combination of all these aspects. Also gaining in importance are concerns of environmental pollution and sustainable development when selecting seawater desalination and power plant configurations, as well as their optimization when considering desalination and electricity generation as a whole. In the practical design of hybrid membrane and thermal systems, aspects come to light, though, that restrict linking of the two systems and joint utilization of facilities, as conceived in studies and conceptual design investigations. This applies both for common utilization of intakes and the use of heated up cooling water from thermal processes as a feed stream for the RO part of the desalination process. Additionally, requirements of drinking water composition, particularly chloride content, TDS and compliance with a specific residual content of boron, influence specifically the design of the membrane process part and its share in the total desalination capacity. Such practical aspects have greatly influenced the design and configuration of the Fujairah hybrid plant for which, from a total desalination capacity of 100 MIGD (454,600 m³/d), the share of 37.5 MIGD (170,500 m³/d) makes its seawater RO plant the biggest currently being constructed anywhere in the world. From the findings of the engineering of this plant and the idea that, by increasing interconnection between the two processes on the water side, it is possible to advance a hybrid configuration of this type with regard to cost optimization in the membrane installation, but also by joint utilization of the intake equipment, perspectives result for applied research efforts over the near and long terms, for example: long-term behavior of membranes at elevated temperatures; tendency for biofouling in membrane process with common utilization of cooling water and brine; influences of such interconnections on the overall availability of the facility. But also for the operation and maintenance organization of such large facilities, consequences can be foreseen for the future development of hybrid plants, particularly for operation management and organisation of the interplay of the different power plant and desalination systems, monitoring of SWRO membrane replacement and cleaning, as well as controlling water quality.     

Differently sized native milk fat globules separated by microfiltration: fatty acid composition of the milk fat globule membrane and triglyceride core

The aim of this study was to characterize the fatty acid composition of the core and membrane of differently sized milk fat globules separated by microfiltration, which can now be used to manufacture dairy products. Native milk fat globules of various mean diameters, ranging from d₄₃ = 2.3 µm to 8.0 µm, were obtained using microfiltration of raw whole milk. After milk fat globule washing, the milk fat globule membrane (MFGM) and the triglyceride core (TC) were separated by manual churning. After total lipid extraction from each fraction, their fatty acid composition was characterized using methyl ester analysis by gas chromatography. Regardless of season, no significant differences were observed in the fatty acid composition of the MFGM phospholipids. Conversely, significant differences were found in the fatty acid composition of TC; particularly, small fat globule TC contained more medium‐chain fatty acids and less stearic acid than large fat globule TC. These results show that the previously observed differences in total fatty acid composition among differently sized milk fat globules are due to their triglyceride composition and MFGM amount rather than to the composition of the MFGM.     

Processing of Particle-Stabilized Wet Foams Into Porous Ceramics

Direct foaming of colloidal suspensions is a simple and versatile approach for the fabrication of macroporous ceramic materials. Wet foams produced by this method can be stabilized by long-chain surfactants or by colloidal particles. In this work, we investigate the processing of particle-stabilized wet foams into crack-free macroporous ceramics. The processing steps are discussed with particular emphasis on the consolidation and drying process of wet foams. Macroporous alumina ceramics prepared using different consolidation and drying methods are compared in terms of their final microstructure, porosity, and compressive strength. Consolidation of the wet foam by particle coagulation before drying resulted in porous alumina with a closed-cell structure, a porosity of 86.5%, an average cell size of 35 μm, and a remarkable compressive strength of 16.3 MPa. On the other hand, wet foams consolidated via gelation of the liquid within the foam lamella led to porous structures with interconnected cells in the size range from 100 to 150 μm. The tailored microstructure and high mechanical strength of the macroporous ceramics can be of interest for the manufacture of bio-scaffolds, thermal insulators, impact absorbers, separation membranes, and light weight ceramics.     

Reverse osmosis in the desalination of brackish water and sea water

To make RO an economical process, plant and operating costs have been reduced by developing compact modules, led by polyamide hollow fibre modules which recover energy from the reject when desalinating highly saline brackish water and seawater. Such plants only start to pay their way at product rates of around 400m³ /d +. Energy costs for desalination systems with lower capacities can also be reduced considerably by operating the RO plants at conversion rates of more than 30%. To what extent the required higher conversion rates can be obtained for a particular application depends on concentration of scales-forming content matter (calcium sulphate, strontium sulphate, barium sulphate and calcium carbonate), salt content of the raw water, concentration of fouling substances such as iron, manganese, anorganic and organic matter, risk of biological growth due to algae, shells and bacteria. The scope and type of conditioning and pre-treatment are based on these factors.     

Measuring Cognitive Load Using Linguistic Features: Implications for Usability Evaluation and Adaptive Interaction Design

An intelligent adaptable system, aware of a user’s experienced cognitive load, may help improve performance in complex, time-critical situations by dynamically deploying more appropriate output strategies to reduce cognitive load. However, measuring a user’s cognitive load robustly, in real-time is not a trivial task. Many research studies have attempted to assess users’ cognitive load using different measurements, but these are often unsuitable for deployment in real-life applications due to high intrusiveness. Relatively novel linguistic behavioral features as potential indices of user’s cognitive load is proposed. These features may be collected implicitly and nonintrusively supporting real-time assessment of users’ cognitive load and accordingly allowing adaptive usability evaluation and interaction. Results from a laboratory experiment show significantly different linguistic patterns under different task complexities and cognitive load levels. Implications of the research for adaptive interaction are also discussed, that is, how the cognitive load measurement-based approach could be used for user interface evaluation and interaction design improvement.