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With the development of microelectronic technology, the reliability of devices in a complex electromagnetic environment has become one of the greatest challenges in the semiconductor industry. On this basis, a phenomenon of nonlinear transient response is observed in high-power microwave (HPM)-radiating AlGaAs/InGaAs pseudomorphic high-electron-mobility transistors (pHEMTs). This abnormal response is induced before the thermal failure, causing disturbances to the circuit. To understand this phenomenon, a detailed mechanism analysis is proposed. The analysis shows that the nonlinear response is initially associated with the 2DEG velocity saturation, then a breakdown process is induced by the tunneling and impact ionization combined effect. Within each radiation period, the channel current changes its direction twice under the influence of the HPM field. The nonlinear response current Id is derived from the theoretical analysis. TCAD simulations demonstrate the saturation and breakdown process. Corresponding experiments are performed using a Ka-band low-noise amplifier (LNA) chip. The results support the theory well.

Although spice extracts are well known to exhibit antibacterial properties, there is lack of a comprehensive evaluation of the antibacterial effect of spices against antibiotic-resistant bacteria. In the present study, ethanolic extracts from a total of 67 spices were comprehensively investigated for their in vitro antibacterial activities by agar well diffusion against two common food-borne bacteria, Staphylococcus aureus and Salmonella enteritidis, with multi-drug resistance. Results showed that S. aureus was generally more sensitive to spice extracts than S. enteritidis. Of the 67 spice extracts, 38 exhibited antibacterial activity against drug-resistant S. aureus, while only four samples were effective on drug-resistant S. enteritidis. In addition, 11 spice extracts with inhibition zones greater than 15 mm were further verified for their broad-spectrum antibacterial properties using another 10 drug-resistant S. aureus strains. It was found that five spice extracts, including galangal, fructus galangae, cinnamon, yellow mustard seed, and rosemary, exhibited the highest antibacterial capacity. Further cytotoxicity of these 11 spices was determined and LC50 values were found to be more than 100 μg/mL except for galangal, rosemary, and sage, whose LC50 values were 9.32 ± 0.83, 19.77 ± 2.17, and 50.54 ± 2.57, respectively. Moreover, the antioxidant activities (ferric-reducing antioxidant power (FRAP) and trolox equivalent antioxidant capacity (TEAC) values) and total phenolic content (TPC) of spice extracts were determined to establish possible correlations with the antibacterial activity. Although the antibacterial effect was positively correlated with the antioxidant activities and TPC, the correlation was weak (r < 0.5), indicating that the antibacterial activity could also be attributed to other components besides antioxidant polyphenols in the tested spice extracts. In conclusion, dietary spices are good natural sources of antibacterial agents to fight against antibiotic-resistant bacteria, with potential applications as natural food preservatives and natural alternatives to antibiotics in animal feeding.

Abstract   Chlorella is a promising alternative resource of lutein (xanthophyll) production as it can be cultivated heterotrophically in fermentors. In this paper, a kinetic model for lutein production by heterotrophic Chlorella pyrenoidosa was developed based on batch cultivations in 250-ml flasks and a 19-l fermentor. The model was validated by experimental data from two fed-batch cultivations performed in the same fermentor. The dynamic behavior of lutein production by C. pyrenoidosa with various concentrations of glucose and nitrogen was analyzed based on the kinetic model. Model-based analyses suggested that glucose concentrations between 5 and 24 g/l and nitrogen concentrations between 0.7 and 12 g/l during the cultivation were favorable for lutein production by heterotrophic C. pyrenoidosa. It also showed that fed-batch cultivations are more suitable for efficient production of lutein than batch ones. The results obtained in this study may contribute to commercial lutein production by heterotrophic Chlorella. [ABSTRACT FROM AUTHOR]

The instantaneous reversible soft logic upset induced by the electromagnetic interference (EMI) severely affects the performances and reliabilities of complementary metal–oxide–semiconductor (CMOS) inverters. This kind of soft logic upset is investigated in theory and simulation. Physics-based analysis is performed, and the result shows that the upset is caused by the non-equilibrium carrier accumulation in channels, which can ultimately lead to an abnormal turn-on of specific metal–oxide–semiconductor field-effect transistor (MOSFET) in CMOS inverter. Then a soft logic upset simulation model is introduced. Using this model, analysis of upset characteristic reveals an increasing susceptibility under higher injection powers, which accords well with experimental results, and the influences of EMI frequency and device size are studied respectively using the same model. The research indicates that in a range from L waveband to C waveband, lower interference frequency and smaller device size are more likely to be affected by the soft logic upset. [ABSTRACT FROM AUTHOR]

The structural, mechanical, elastic anisotropic, and electronic properties of the monoclinic phase of m-Si3N4, m-Si2GeN4, m-SiGe2N4, and m-Ge3N4 are systematically investigated in this work. The calculated results of lattice parameters, elastic constants and elastic moduli of m-Si3N4 and m-Ge3N4 are in good agreement with previous theoretical results. Using the Voigt–Reuss–Hill method, elastic properties such as bulk modulus B and shear modulus G are investigated. The calculated ratio of B/G and Poisson’s ratio v show that only m-SiGe2N4 should belong to a ductile material in nature. In addition, m-SiGe2N4 possesses the largest anisotropic shear modulus, Young’s modulus, Poisson’s ratio, and percentage of elastic anisotropies for bulk modulus and shear modulus , and universal anisotropic index among m-SixGe3−xN4 (x = 0, 1, 2, 3.) The results of electronic band gap reveal that m-Si3N4, m-Si2GeN4, m-SiGe2N4, and m-Ge3N4 are all direct and wide band gap semiconducting materials. [ABSTRACT FROM AUTHOR]

The thermal failure induced by high power microwave (HPM) in a complementary metal oxide semiconductor (CMOS) inverter is investigated and its dependence on microwave parameters is discussed in detail. An analytical model of the temperature distribution is established and the relationships between hotspot temperature and pulse width and between hotspot temperature and frequency are predicted, which reveals a more severe rise in temperature under the influence of microwave with longer width and lower frequency. The temperature variation mechanism and the theoretical temperature model are validated and explained by the simulation. Furthermore, variation trend of damage threshold with microwave parameters is derived theoretically, and the conclusions are consistent with simulation results and reported data. [ABSTRACT FROM AUTHOR]

The latch-up effect induced by high-power microwave (HPM) in complementary metal–oxide–semiconductor (CMOS) inverter is investigated in simulation and theory in this paper. The physical mechanisms of excess carrier injection and HPM-induced latch-up are proposed. Analysis on upset characteristic under pulsed wave reveals increasing susceptibility under shorter-width pulsed wave which satisfies experimental data, and the dependence of upset threshold on pulse repetitive frequency (PRF) is believed to be due to the accumulation of excess carriers. Moreover, the trend that HPM-induced latch-up is more likely to happen in shallow-well device is proposed.Finally, the process of self-recovery which is ever-reported in experiment with its correlation with supply voltage and power level is elaborated, and the conclusions are consistent with reported experimental results. [ABSTRACT FROM AUTHOR]

An electromagnetic pulse (EMP)-induced damage model based on the internal damage mechanism of the GaAs pseudomorphic high electron mobility transistor (PHEMT) is established in this paper. With this model, the relationships among the damage power, damage energy, pulse width and signal amplitude are investigated. Simulation results show that the pulse width index from the damage power formula obtained here is higher than that from the empirical formula due to the hotspot transferring in the damage process of the device. It is observed that the damage energy is not a constant, which decreases with the signal amplitude increasing, and then changes little when the signal amplitude reaches up to a certain level. [ABSTRACT FROM AUTHOR]

Sequence analysis demonstrated that all reported primers based on the thermonuclease (TNase) gene (nuc ) used in the detection of the foodborne pathogen Staphylococcus aureus were derived from the nuclease gene, instead of the thermonuclease gene. In this study, two pairs of primers targeting the sequences of the nuc and 16S ribosomal RNA genes were designed in a duplex polymerase chain reaction (PCR) assay for the detection of S. aureus , particularly those of the enterotoxigenic strains. After optimization of the amplification conditions by uniform design, two specific products were amplified in the PCR detection system: a 223-bp nuc fragment and a 565-bp 16S rDNA fragment. Evaluation tests demonstrated that this duplex PCR method has high specificity for only S. aureus . The detection limit of the assay was 9.35 pg/µL using S. aureus genomic DNA. The sensitivity for direct detection of milk samples sparked with S. aureus was 104–105 cfu/mL, and the sensitivity was 1 cfu/mL as an initial concentration when an enrichment process was used. A PCR-based detection assay for enterotoxin gene was performed in parallel with the detection of the nuc -encoded TNase activity in several S. aureus strains, and a good correlation between TNase production and enterotoxigenicity was demonstrated in all the strains tested. [ABSTRACT FROM AUTHOR]