Low-energy proton-induced defects in n/p InGaP solar cells

The effects of low-energy proton-induced degradation of photovoltaic properties and generation of deep-level defects in n⁺/p InGaP solar cells have been investigated. Energy-dependent effects included decreased solar cell efficiency and increase the carrier removal rate with decreasing proton energy. The spectral response depicts that the degradation is more at longer wavelengths with the increase of proton fluence. A new majority (hole) trap HP1 has been observed in low-energy proton irradiated p-InGaP at 0.90±0.05 eV above the valence band for the first time. The carrier removal rates were found to be 61433 and 8640 cm⁻¹ for 100 and 380-keV proton irradiation, respectively.     

An improved analytical model of 4H-SiC MESFET incorporating bulk and interface trapping effects

An improved analytical model for the current-voltage (I-V) characteristics of the 4H-SiC metal semiconductor field effect transistor (MESFET) on a high purity semi-insulating (HPSI) substrate with trapping and thermal effects is presented. The 4H-SiC MESFET structure includes a stack of HPSI substrates and a uniformly doped channel layer. The trapping effects include both the effect of multiple deep-level traps in the substrate and surface traps between the gate to source/drain. The self-heating effects are also incorporated to obtain the accurate and realistic nature of the analytical model. The importance of the proposed model is emphasised through the inclusion of the recent and exact nature of the traps in the 4H-SiC HPSI substrate responsible for substrate compensation. The analytical model is used to exhibit DC I-V characteristics of the device with and without trapping and thermal effects. From the results, the current degradation is observed due to the surface and substrate trapping effects and the negative conductance introduced by the self-heating effect at a high drain voltage. The calculated results are compared with reported experimental and two-dimensional simulations (Silvaco^®-TCAD). The proposed model also illustrates the effectiveness of the gate-source distance scaling effect compared to the gate-drain scaling effect in optimizing 4H-SiC MESFET performance. Results demonstrate that the proposed I-V model of 4H-SiC MESFET is suitable for realizing SiC based monolithic circuits (MMICs) on HPSI substrates.     

Antimicrobial Microwebs of DNA–Histone Inspired from Neutrophil Extracellular Traps

Neutrophil extracellular traps (NETs) are decondensed chromatin networks released by neutrophils that can trap and kill pathogens but can also paradoxically promote biofilms. The mechanism of NET functions remains ambiguous, at least in part, due to their complex and variable compositions. To unravel the antimicrobial performance of NETs, a minimalistic NET‐like synthetic structure, termed “microwebs,” is produced by the sonochemical complexation of DNA and histone. The prepared microwebs have structural similarity to NETs at the nanometer to micrometer dimensions but with well‐defined molecular compositions. Microwebs prepared with different DNA to histone ratios show that microwebs trap pathogenic Escherichia coli in a manner similar to NETs when the zeta potential of the microwebs is positive. The DNA nanofiber networks and the bactericidal histone constituting the microwebs inhibit the growth of E. coli. Moreover, microwebs work synergistically with colistin sulfate, a common and a last‐resort antibiotic, by targeting the cell envelope of pathogenic bacteria. The synthesis of microwebs enables mechanistic studies not possible with NETs, and it opens new possibilities for constructing biomimetic bacterial microenvironments to better understand and predict physiological pathogen responses.     

Direct comparison of charge transport and electronic traps in polymer–fullerene blends under dark and illuminated conditions

A direct comparison of charge transport and electronic traps in representative polymer–fullerene blend, poly (3-hexylthiophene) (P3HT) and 1-(3-methoxycarbonyl)-propyl-1-phenyl-(6,6)C61 (PCBM), is carried out in dark and illuminated conditions based on the measurements of temperature-dependent current–voltage characteristics. In dark condition, the charge transport presents a transition from Ohmic to trap-limited current. While the trap-filled space charge limited current is observed under illumination at the same applied bias. From evaluations of trap density and energy distribution by a differential method, it is reveal that the diverse charge transport in dark and illuminated conditions is mainly caused by the different trap states distribution, which strongly affects the space charges and the electrical field in P3HT: PCBM blends.     

Odors in traps: Does most recent occupant influence capture rates for house mice?

Responses of house mice (Mus domesticus) to odors in live traps were studied in a series of eight 0.1-ha outdoor field enclosures. It was assumed that the most recent mouse capture would provide the predominant odor in a trap for at least one week. Three different populations were tested, one in 1989 and two in 1992, involving over 800 different mice. Similar response patterns were recorded from all three groups. Two types of questions were tested: (1) Were there any biases contingent upon what had been previously caught? (2) Were there consistent responses of mice of particular age, sex, or reproductive classes to trap odors? Traps soiled by juvenile females caught adult females significantly less often than expected, but there were no consistent relationships in terms of the effects of specific residual odors on the subsequent capture at a particular trap. For various age, sex, and reproductive classes, (1) adult males preferred odors from juvenile and estrous females and avoided odors of other males significantly more than expected, (2) juvenile females selected traps with odors of other juvenile females and avoided all other types of female odors significantly more than expected, (3) nonestrous females exhibited a significant preference for adult male odor, and (4) estrous females selected traps containing odors from adult males but avoided those that had previously contained either nonestrous or pregnant/lactating females significantly more than expected. These findings have potential implications with regard to both the methods used for trapping small rodents and the social biology of house mice.     

Effect of engine-based thermal aging on surface morphology and performance of Lean NOx Traps

A small single-cylinder diesel engine is used to thermally age model (Pt + Rh/Ba/γ-Al₂O₃) lean NO_x traps (LNTs) under lean/rich cycling at target temperatures of 600 °C, 700 °C, and 800 °C. During an aging cycle, fuel is injected into the exhaust to achieve reproducible exotherms under lean and rich conditions with the average temperature approximating the target temperature. Aging is performed until the cycle-average NO_x conversion measured at 400 °C is approximately constant. Engine-based NO_x conversion decreased by 42% after 60 cycles at 600 °C, 36% after 76 cycles at 700 °C and 57% after 46 cycles at 800 °C. The catalyst samples were removed and characterized by XRD and using a microreactor that allowed controlled measurements of surface area, precious metal size, NO_x storage, and reaction rates. Three aging mechanisms responsible for the deactivation of LNTs have been identified: (i) loss of dispersion of the precious metals, (ii) phase transitions in the washcoat materials, and (iii) loss of surface area of the storage component and support. These three mechanisms are accelerated when the aging temperature exceeds 850 °C—the γ to δ transition temperature of Al₂O₃. Normalization of rates of NO reacted at 400 °C to total surface area demonstrates the biggest impact on performance stems from surface area losses rather than from precious metal sintering.     

核电厂蒸汽管道疏水器选型计算关键参数研究

为快速获得核电厂蒸汽管道的疏水量。通过启动阶段和正常运行阶段蒸汽管道疏水量的计算,分析并绘制了各种常用规格的蒸汽管道正常运行时产生的散热量图,通过散热量图可在疏水器选型时快速获得核电厂蒸汽管道疏水量。为延长疏水器使用寿命和降低成本,对比分析了不同疏水器安全系数(k)对疏水器性能的影响,推荐适合核电厂蒸汽管道的k,以提高蒸汽利用效率和经济效益,并延长疏水器使用寿命,降低疏水器成本。