Thin n-i-p radiation-resistant solar cell feasibility study

Silicon solar cells were fabricated to verify the predictions that: (1) thin n(+)pp(+) cells can provide high values of open circuit voltage even when high resistivity base material ( 1000 omega-cm) is used; (2) cells with good p(+) back contacts will display an increase in open circuit voltage with decreasing cell thickness; and (3) high quality, thin, high resistivity, solar cells can be made using processing compatible with conventional practice. Analysis of I-V and spectral response measurements of these cells confirmed theoretical predictions and thereby pointed to voltages beyond the near 600 mV obtained in this study

Gallium Arsenide solar cell radiation damage experiment

Gallium arsenide (GaAs) solar cells for space applications from three different manufactures were irradiated with 10 MeV protons or 1 MeV electrons. The electrical performance of the cells was measured at several fluence levels and compared. Silicon cells were included for reference and comparison. All the GaAs cell types performed similarly throughout the testing and showed a 36 to 56 percent power areal density advantage over the silicon cells. Thinner (8-mil versus 12-mil) GaAs cells provide a significant weight reduction. The use of germanium (Ge) substrates to improve mechanical integrity can be implemented with little impact on end of life performance in a radiation environment

Modeling and control of a DC upset resistance butt welding process

This paper presents the analysis and synthesis of modeling and control of the DC upset resistance butt welding process used in rim production lines. A new control strategy is developed, enabling active control of the welding seam temperature and the upset size. As a result, set-up times and energy consumption are reduced significantly

Mixed matrix carbon stainless steel (MMCSS) hollow fibres for gas separation

This work reports the preparation and investigation of novel mixed matrix carbon stainless steel (MMCSS) membranes. The study involves the production of MMCSS hollow fibres using SS particles of 6, 10, 16 and 45\ua0μm in diameter, polyetherimide as a polymeric binder and pyrolysis using a N inert atmosphere. As a result, the binder pyrolysed to carbon was retained in the hollow fibre structure, filling the voids between the SS particles. Smaller SS particles (6\ua0μm) yielded a bi-modal pore size distribution and superior mechanical properties. An interesting morphological feature was the formation of honeycomb-like carbon structures between the SS particles, attributed to the densification of the hollow fibre during pyrolysis at 1050\ua0°C. The MMCSS hollow fibres (6\ua0μm) delivered almost pure N for the separation of a synthetic flue gas composition (13% CO and 87% N). It was found that CO had a strong affinity to the surface of the MMCSS materials (isosteric heat of adsorption of 38\ua0kJ\ua0mol) whilst N was a non-absorbing gas. Therefore, CO permeation was controlled by surface diffusion whilst N was controlled by the faster Knudsen diffusion mechanism. For CO feed concentrations in excess of 13%, the CO diffusion increased as the excess CO could not adsorb on the fully saturated surface of the MMCSS hollow fibres, thus slightly reducing the N purity in the permeate stream

Relation between composition and vacant oxygen sites in the mixed ionicelectronic conductors La5.4W1 yMyO12 delta M Mo, Re; 0 lt; y lt; 0.2 and their mother compound La6 xWO12 delta 0.4 lt; x lt; 0.8

A detailed analysis of specimen composition, water uptake and their interrelationship in the systems La6 xWO12 amp; 948; 0.4 amp; 8804; x amp; 8804;0.8 and La6 xW1 yMyO12 amp; 948; 0 amp; 8804;y amp; 8804;0.2; M Mo, Re is presented. The three specimen series were investigated in dry and wet D2O conditions. A systematic trend in mass loss and onset temperature variation was observed in La6 xWO12 amp; 948; 0.4 amp; 8804;x amp; 8804;0.8 . Even very small amounts lt; 1 wt of secondary phases were found to notably modify the specimen s water uptake and onset temperature of mass loss. The theoretical model for vacancy concentration available was used to calculate the vacant oxygen sites starting from mass loss values determined by thermogravimetry. A discrepancy between the calculated and observed concentration of vacant oxygen sites is observed for all three systems. The effect of substitution of W by Re or Mo on the vacancy amount is explained taking into account diffraction measurements and information on the oxidation state of the substituting elements Mo and R

Replication-Competent Recombinant Porcine Reproductive and Respiratory Syndrome (PRRS) Viruses Expressing Indicator Proteins and Antiviral Cytokines

Porcine reproductive and respiratory syndrome virus (PRRSV) can subvert early innate immunity, which leads to ineffective antimicrobial responses. Overcoming immune subversion is critical for developing vaccines and other measures to control this devastating swine virus. The overall goal of this work was to enhance innate and adaptive immunity following vaccination through the expression of interferon (IFN) genes by the PRRSV genome. We have constructed a series of recombinant PRRS viruses using an infectious PRRSV cDNA clone (pCMV-P129). Coding regions of exogenous genes, which included Renilla luciferase (Rluc), green and red fluorescent proteins (GFP and DsRed, respectively) and several interferons (IFNs), were constructed and expressed through a unique subgenomic mRNA placed between ORF1b and ORF2 of the PRRSV infectious clone. The constructs, which expressed Rluc, GFP, DsRed, efficiently produced progeny viruses and mimicked the parental virus in both MARC-145 cells and porcine macrophages. In contrast, replication of IFN-expressing viruses was attenuated, similar to the level of replication observed after the addition of exogenous IFN. Furthermore, the IFN expressing viruses inhibited the replication of a second PRRS virus co-transfected or co-infected. Inhibition by the different IFN subtypes corresponded to their anti-PRRSV activity, i.e., IFNω5 ° IFNα1 > IFN-β > IFNδ3. In summary, the indicator-expressing viruses provided an efficient means for real-time monitoring of viral replication thus allowing high‑throughput elucidation of the role of host factors in PRRSV infection. This was shown when they were used to clearly demonstrate the involvement of tumor susceptibility gene 101 (TSG101) in the early stage of PRRSV infection. In addition, replication‑competent IFN-expressing viruses may be good candidates for development of modified live virus (MLV) vaccines, which are capable of reversing subverted innate immune responses and may induce more effective adaptive immunity against PRRSV infection

Experimental Observation of Quantum Confinement in the Conduction Band of CdSe Quantum Dots

Recent theoretical descriptions as to the magnitude of effect that quantum confinement has on he conduction band (CB) of CdSe quantum dots (QD) have been conflicting. In this manuscript, we experimentally identify quantum confinement effects in the CB of CdSe QDs for the first time. Using X-ray absorption spectroscopy, we have unambiguously witnessed the CB minimum shift to higher energy with decreasing particle size and have been able to compare these results to recent theories. Our experiments have been able to identify which theories correctly describe the CB states in CdSe QDs. In particular, our experiments suggest that multiple theories describe the shifts in the CB of CdSe QDs and are not mutually exclusive