We demonstrate an average power of 2 mW at λ≈11.5 μm and 233 K, for a GaAs-based quantum cascade laser mounted on a Peltier cooler. Furthermore, a maximum operating temperature of 285 K has also been demonstrated. These results are attributed to the excellent intrinsic thermal characteristics of these lasers and good heat management, achieved through the structural design and epi-side down mounting. Measurements show a thermal resistance of 6.7 K/W at 233 K, in good-agreement with our models 相似文献
High-resolution small-angle X-ray scattering (SAXS), complemented by small-angle neutron scattering (SANS) and dynamic light scattering (DLS) experiments, was used to study the effect of curvature on the bilayer structure of dioleoyl-phosphatidylcholine (DOPC) and dioleoyl-phosphatidylserine (DOPS) unilamellar vesicles (ULVs). Bilayer curvature, as a result of finite vesicle size, was varied as a function of vesicle radius and determined by DLS and SANS measurements. Unilamellarity of large DOPC ULVs was achieved by the addition of small amounts (up to 4 mol %) of the charged lipid, DOPS. A comparison of SANS data over the range of 0.02 < q <0.2 A-1 indicated no change in the overall bilayer thickness as a function of ULV diameter (620 to 1840 A). SANS data were corroborated by high-resolution (0.06 < q <0.6 A-1) SAXS data for the same diameter ULVs and data obtained from planar samples of aligned bilayers. Both the inner and outer leaflets of the bilayer were found to be indistinguishable. This observation agrees well with simple geometric models describing the effect of vesicle curvature. However, 1220-A-diameter pure DOPS ULVs form asymmetric bilayers whose structure can most likely be rationalized in terms of geometrical constraints coupled with electrostatic interactions, rather than curvature alone. 相似文献
Microalgae are unique photosynthetic organisms that are known to accumulate storage lipids in large quantitites and thrive
in saline waters. Before these storage lipids can be used, they must be extracted from the microalgae and converted into usable
fuel. Transesterification of lipids produces fatty acid methyl esters that can be used as a diesel fuel substitute.
Three solvents, 1-butanol, ethanol, and hexane/2-propanol, were evaluated for extraction efficiency of microalgal lipids.
Type of catalyst, concentration of catalyst, time of reaction, temperature of reaction, and quality of lipid were examined
as variables for transesterification. The most efficient solvent of the three for extraction was 1-butanol (90% efficiency),
followed by hexane/2-propanol and ethanol. Optimal yield of fatty acid methyl esters was obtained using 0.6N hydrochloric
acid in methanol for 0.1 h at 70°C. 相似文献
In this proceedings, we review the current status of experimental searches for novel forms of nuclear matter, namely strange quark matter states. A detailed summary of H-dibaryon results is given and implications on the stability of such a state is reviewed. Final results from the BNL-AGS and CERN-SPS strangelet searches are presented and put in the context of coalescence and plasma production models. 相似文献
Sensitivity, repeatability, and discernment are three major issues in any classification problem. In this study, an electronic nose with an array of 32 sensors was used to classify a range of odorous substances. The collective time response of the sensor array was first partitioned into four time segments, using four smooth time-windowing functions. The dimension of the data associated with each time segment was then reduced by applying the Karhunen-Loéve (truncated) expansion (KLE). An ensemble of the reduced data patterns was then used to train a neural network (NN) using the Levenberg-Marquardt (LM) learning method. A genetic algorithm (GA)-based evolutionary computation method was used to devise the appropriate NN training parameters, as well as the effective database partitions/features. Finally, it was shown that a GA-supervised NN system (GANN) outperforms the NN-only classifier, for the classes of the odorants investigated in this study (fragrances, hog farm air, and soft beverages). 相似文献
Early evaluations of the bioconversion potential for combined wastes such as tuna sludge and sorted municipal solid waste (MSW) were conducted at laboratory scale and compared conventional low-solids, stirred-tank anaerobic systems with the novel, high-solids anaerobic digester (HSAD) design. Enhanced feedstock conversion rates and yields were determined for the HSAD system. In addition, the HSAD system demonstrated superior resiliency to process failure. Utilizing relatively dry feedstocks, the HSAD system is approximately one-tenth the size of conventional low-solids systems. In addition, the HSAD system is capable of organic loading rates (OLRs) on the order of 20-25 g volatile solids per liter digester volume per d (gVS/L/d), roughly 4-5 times those of conventional systems
Current efforts involve developing a demonstration-scale (pilot-scale) HSAD system. A two-ton/d plant has been constructed in Stanton, CA and is currently in the commissioning/startup phase. The purposes of the project are to verify laboratory- and intermediate-scale process performance; test the performance of large-scale prototype mechanical systems; demonstrate the long-term reliability of the process; and generate the process and economic data required for the design, financing, and construction of full-scale commercial systems. This study presents conformational fermentation data obtained at intermediate-scale and a snapshot of the pilot-scale project