Einflu? der Probenoberfl?che auf den Gasanalysenwert UF-gebundener Spanplatten

Ohne Zusammenfassung     

Multiple-wavelength integration in InGaAs-InGaAsP structures using pulsed laser irradiation-induced quantum-well intermixing

In this paper, we present the characteristics of a quantum-well intermixing technique using pulsed-photoabsorption-induced disordering. Photoluminescence, micro-Raman spectroscopy, and transmission electron microscopy were used to characterize the process. Using this technique, a differential wavelength shift between the intermixed and nonintermixed regions of over 160 nm has been observed from InGaAs-InGaAsP heterostructures. It was found from the micro-Raman measurements that a spatial resolution of better than 2.5 /spl mu/m can be achieved. A theoretical model has been developed to estimate the spatial resolution limit. Theoretical analysis has also been performed to investigate the effect of laser irradiation on the degree of intermixing in InGaAs-InGaAsP structures. To verify the capability of this process in monolithic photonic integration, high-quality bandgap tuned lasers, two-section extended cavity lasers, and multiple-wavelength laser chips have been fabricated.     

Cellulose-binding domains: potential for purification of complex proteins

The endoglucanase CenA and the exoglucanase Cex from Cellulomonasfimi each contain a discrete cellulose-binding domain (CBD),at the amino-terminus or carboxyl-terminus respectively. Thegene fragment encoding the CBD can be fused to the gene of aprotein of interest. Using this approach hybrid proteins canbe engineered which bind reversibly to cellulose and exhibitthe biological activity of the protein partner. Alkaline phosphatase(PhoA) from Escherichia coli, and a ß-glucosidase(Abg) from an Agrobacterium sp. are dimeric proteins. The fusionpolypeptides CenA-PhoA and Abg-CBC_cex are sensitive to proteolysisat the junctions between the fusion partners. Proteolysis resultsin a mixture of homo- and heterodimers; these bind to celluloseif one or both of the monomers carry a CBD, e.g. CenA-PhoA/CenA-PhoAand CenA-PhoA/PhoA. CBD fusion polypeptides could be used inthis way to purify polypeptides which associate with the fusionpartner.     

Hydrogen and Oxygen Bubble Attachment to a Bitumen Drop

Air bubble – bitumen attachment is a critical step in the flotation of bitumen from mined oil sand. In this study, single bubble – bitumen drop attachment was observed directly using a novel experimental technique. Induction time is determined and used as an indication of bubble‐bitumen attachment potency for both hydrogen and oxygen bubbles. The attachment tests were conducted in deaerated municipal water (City of Edmonton tap water) at temperatures ranging from 22–50°C. Induction times measured for hydrogen bubble attachment were shorter than those for oxygen bubbles. Coalescence tests were also conducted in the absence of bitumen, and showed that hydrogen bubbles coalesced more rapidly than oxygen bubbles in both deaerated municipal water and clear (solids‐free) process water.     

Investigation of solid particle erosion-related failures in once-through steam generators (OTSGs) in oil sands in-situ production: The limitations of the API RP 14E guideline in OTSG design or operational decision-making

The required steam for steam-assisted gravity drainage (SAGD) oil sands operations is generated using a once-through steam generator (OTSG) that is fed with relatively poor quality process water. Industries have reported possible solid particle erosion-related failure in the OTSG boiler tubes because of the transport of precipitated dense inorganic particles. However, the presence of other damage mechanisms, e.g. corrosion, flow accelerated corrosion (FAC), often masks the evidence of erosive wear. Also, industries set an upper limit operating velocity for the OTSG using the API RP 14E guideline, which provides no quantitative erosion rates to determine an operating envelope. This study presents a computational fluid dynamics (CFD) analysis of erosion damage in a SAGD OTSG boiler tube. The results revealed that API RP 14E may not be an effective decision-making tool for operating the OTSG system. For example, a 10% increase in velocity, even at conditions below the API RP 14E threshold, showed a decrease in the failure time of the boiler tubes by 40%–50%.     

Novel Type II Fatty Acid Biosynthesis (FAS II) Inhibitors as Multistage Antimalarial Agents

Malaria is a potentially fatal disease caused by Plasmodium parasites and poses a major medical risk in large parts of the world. The development of new, affordable antimalarial drugs is of vital importance as there are increasing reports of resistance to the currently available therapeutics. In addition, most of the current drugs used for chemoprophylaxis merely act on parasites already replicating in the blood. At this point, a patient might already be suffering from the symptoms associated with the disease and could additionally be infectious to an Anopheles mosquito. These insects act as a vector, subsequently spreading the disease to other humans. In order to cure not only malaria but prevent transmission as well, a drug must target both the blood‐ and pre‐erythrocytic liver stages of the parasite. P. falciparum (Pf) enoyl acyl carrier protein (ACP) reductase (ENR) is a key enzyme of plasmodial type II fatty acid biosynthesis (FAS II). It has been shown to be essential for liver‐stage development of Plasmodium berghei and is therefore qualified as a target for true causal chemoprophylaxis. Using virtual screening based on two crystal structures of PfENR, we identified a structurally novel class of FAS inhibitors. Subsequent chemical optimization yielded two compounds that are effective against multiple stages of the malaria parasite. These two most promising derivatives were found to inhibit blood‐stage parasite growth with IC₅₀ values of 1.7 and 3.0 μM and lead to a more prominent developmental attenuation of liver‐stage parasites than the gold‐standard drug, primaquine.     

Direct stamping and capillary flow patterning of solution processable piezoelectric polyvinylidene fluoride films

It is well known that the potential applications of polyvinylidene fluoride (PVDF) mainly come from the piezoelectricity and ferroelectricity of its polar β phase. Thus, we have investigated the effect of different preparation conditions namely evaporation temperature, type of solvent and additive to enhance the β crystal structures of PVDF thin film. Subsequently, facile and direct soft lithography technique; direct stamping and capillary flow were employed to demonstrate good pattern transfer of PVDF thin films. The piezoelectricity of the microstructure was characterized using piezoresponse force microscopy (PFM) where fairly good piezoresponse was obtained without further processing procedures i.e., annealing or applied pressure/electric field. As such, our solution processable and direct patterning of PVDF techniques offer facile and promising route to produce arrays of isolated microstructures with improved piezoelectric functionality.     

Effects of Turbulent Fluctuations on Nanoparticle Coagulation in Shear Flows

The effects of fluid turbulence on the coagulation of aerosols are studied quantitatively and qualitatively. Direct numerical simulation data is used to isolate the effect of the small or subgrid-scale (SGS) particle–particle interactions on nanoparticle coagulation in three-dimensional flows. The rate of particle growth is decomposed into the contribution of the large-scales and small-scales interactions. The contribution of the small-scale interactions is presented as a function of time, space, flow dynamics, and coagulation Damköhler number. Results show that small-scale interactions act to both increase and decrease particle growth. The probability density functions (PDFs) of the SGS growth rate exhibit a negative bias, which increases with time and coagulation Damköhler number. Additionally, PDFs conditioned on the Q-criterion suggest that the contribution of the small-scale interactions primarily act to reduce particle growth in regions characterized by fluid rotation.