Search

The failure mechanism of single-event burnout (SEB) in 4H-SiC inverter is studied by experiments and simulations. The most sensitive location for heavy ions striking in the 4H-SiC inverter circuit has been identified by pulsed laser experiments. Experimental results demonstrate that the maximum linear energy transfer (LET) value that the 4H-SiC inverter circuit can withstand is exceeding 64.07 MeV $\cdot $ cm2/mg but not surpassing 92.25 MeV $\cdot $ cm2/mg. Sentaurus TCAD is utilized to reveal the failure mechanism. The incident heavy-ion radiation triggers the activation of parasitic p-n-p and n-p-n transistors, resulting in a latch-up phenomenon within the circuit, consequently leading to the circuit burnout. The revealed failure mechanism gives a guidance for further hardened circuits design.

This brief reports a 200 V all-SiC integration process platform integrating low-voltage (LV) and high-voltage (HV) devices, such as LV nMOS, LV pMOS, resistor, capacitor, HV lateral DMOS (LDMOS), and HV diode. A P-buffer layer is adopted to increase vertical blocking voltage. The high-temperature tolerance of fabricated HV and LV devices are evaluated. Based on the LV and HV devices, a 200 V monolithic all-SiC half-bridge driver composed of a low-side drive circuit and a high-side drive circuit is designed in this brief. Thanks to HV LDMOS and HV diode, the LV drive signal can be converted to an HV signal through the level-shift circuit, which realizes a high-side floating gate driver. Combined with a low-side CMOS driver, a 200 V half-bridge driver operating at 200 ° C has been verified based on this SiC platform.

Vulcanization accelerators (VAs) serve as crucial additives in synthetic rubber on a global scale. Despite their widespread use, the environmental presence, distribution, and associated exposure risks of VAs remain poorly understood. This study compiled a target list and conducted a screening for eight classes encompassing 42 VAs in diverse urban dust samples from South China. A total of 40 of the 42 target VAs were detectable across all four studied regions, among which 30 were identified for the first time in the environment. Among the eight structure-classified VA classes, xanthates exhibited the highest concentrations (median: 3810–81,300 ng/g), followed by thiazoles, guanidines, sulfenamides, dithiocarbamates, thiurams, thioureas, and others. The median total concentrations of all target VAs (∑VAs) were determined to be 5060 ng/g in road dust, 5730 ng/g in parking lot dust, 29,200 ng/g in vehicle repair plant dust, and 84,300 ng/g in household dust, indicating the widespread presence of numerous rubber-derived VAs in various urban environments. This study marked the first systematic effort to identify a wide range of emerging rubber-derived VAs prevalent in urban environments. The findings call for increased attention to these widely utilized but less well-evaluated chemicals in future research and environmental management efforts.

In this letter, the leakage performances of 4H-SiC CMOS devices, as well as inverter (INV) and NOR logic gate circuits, are evaluated after being exposed to irradiation. It has been observed that the output voltage swing of the SiC INV and NOR gate circuits decreases evidently and large leakage currents appear at the total irradiation dose of 300kGy. The mechanism of leakage current is revealed by conducting Emission Microscope test and analysis of leakage paths based on the layout. The inversion layer forms on the P-epi surface under the polysilicon gate and VDD metal after irradiation, which causes the electron leakage current flowing from N-well to P-epi. At last, suggestion on hardening 4H-SiC CMOS gate circuits is given.

Particles were the most frequent foulants in seawater reverse osmosis (SWRO) desalination. In this study, the fouling characteristic of particles in a large scale SWRO desalination plant from northern China was analyzed systematically by multiple methods. The particle fouling pattern, particle size distribution (PSD), and mineralogical composition were investigated by optical microscopy, scanning electron microscopy with energy dispersive spectrometer, laser diffraction particle size analyzer, X-ray diffraction, and wavelength dispersive X-ray fluorescence spectrometer. Chemical analysis indicated that Na, Mg, Si, and Al were the predominant elements contributing to the fouling particles. The particle deposition had a very broad PSD including ultrafine particles, fine particles, and medium particles due to the failure of the ultrafiltration (UF) system. The mineralogical components were quartz, muscovite, talc, albite, microcline, clinochlore, hematite, and amphibole in descending order. Finally, the long immersing experiment shows that 2.5% hydrofluoric acid processing could eliminate the particles effectively and improve the water flux of the fouled membrane obviously. On the basis of the above results, an in-depth understanding and mitigation of the particles fouling behavior during SWRO desalination would be put forward.

Noncontact optical sensing plays an important role in various applications, for example, motion tracking, pilotless automobile, precision machining, and laser radars. A device with features of high resolution, fast response, and safe detection (operation wavelength at infrared (IR)) is highly desired in such applications. Here, a near IR position-sensitive detector constructed by graphene-Ge Schottky heterojunction has been demonstrated. The device shows high responsivity (minimum detectable power of ∼10 nW), excellent spatial resolution (<1 μm), fast response time (∼μs), and could operate in a wide spectral range (from visible to ∼1600 nm). Applications of precise angle (∼5 × 10–6degree) and vibration frequency (up to 10 kHz) measurements, as well as the trajectory tracking of a high-speed infrared target (∼100 km/h), have been realized based on this device. This work therefore provides a promising route for a high-performance noncontact IR optical sensing system.

Waterborne coatings have gained more and more attention as a method to protect the environment. However, the application of waterborne coatings to metals, especially for sufficient long-term protection in harshly corrosive environments, is still limited. Here, we report a self-curing waterborne coating with good corrosion resistance. First, a self-curing waterborne epoxy resin (SWEP) was synthesized by a chemical reaction between the epoxy resin and titanium diisopropoxide bisacetylacetonate in water. The structural characterizations via Fourier transform infrared spectroscopy and 13C nuclear magnetic resonance spectrsocopy confirmed the successful preparation of the SWEP resin. Differential scanning calorimetry and thermogravimetric analysis showed that the SWEP resin could be cured by heating without the use of any curing agents, and the cured coating exhibited good thermal resistance. The mechanical properties of the cured coatings were discussed in the context of the corresponding standards. The results confirmed that the physical properties of the SWEP coating were as good as those of a traditional two-component waterborne epoxy resin (DCWEP) coating. The chemical resistance analysis revealed that the water, acid and alkaline resistances of the SWEP coating all have significant improvements compared to those of the DCWEP coating. The electrochemical impedance spectroscopy and potentiodynamic polarization test implied that the SWEP coating provided better corrosion protection for metal substances than the DCWEP coating.

Literature showed that sugar-sweetened beverages (SSBs) could increase the risk of developing hypertension in school students, but there is no reported evidence from China yet, so this study aims to investigate the association of the SSBs consumption and school students’ hypertension in urban areas of Nanjing, China. A cross-sectional survey was conducted among primary and junior high school students selected from 32 primary schools and 16 junior high schools using a multi-stage random sampling method, with a total number of 10,091 participants involved. The mean age of Grade 4 is 9.04 ± 0.38, while the mean age of Grade 7 is 12.03 ± 0.41. Blood pressure was measured and SSBs consumption was reported using a validated questionnaire. The overall prevalence of hypertension was 4.5% among the participants. After adjustment for school, parental education, physical activity, diet intake including meat and snacks, participants who had an experience of SSBs intake were at a higher risk of developing hypertension (odds ratio (OR) = 1.40, 95% confidence interval (CI) = 1.15, 1.70) compared with those who had no experience of SSBs intake. A significant association between the consumption of SSBs and hypertension was observed among the students who were at a healthy weight (OR = 1.78, 95% CI = 1.20, 2.65), as well as who were overweight or obese (OR = 1.28, 95% CI = 1.01, 1.61). SSBs may play a contributing role in developing childhood hypertension in this population in China, which is of important implications for future population-based childhood hypertension intervention in China and other countries.

The chemical mechanism (CM) of surface-enhanced Raman scattering (SERS) has been recognized as a decent approach to mildly amplify Raman scattering. However, the insufficient charge transfer (CT) between the SERS substrate and molecules always results in unsatisfying Raman enhancement, exerting a substantial restriction for CM-based SERS. In principle, CT is dominated by the coupling between the energy levels of a semiconductor-molecule system and the laser wavelength, whereas precise tuning of the energy levels is intrinsically difficult. Herein, two-dimensional transition-metal dichalcogenide alloys, whose energy levels can be precisely and continuously tuned over a wide range by simply adjusting their compositions, are investigated. The alloys enable on-demand construction of the CT resonance channels to cater to the requirements of a specific target molecule in SERS. The SERS signals are highly reproducible, and a clear view of the SERS dependences on the energy levels is revealed for different CT resonance terms.

The corrosion resistance of the waterborne epoxy coating is poor during long-term service, which greatly limits its widespread application. In this paper, the halloysite nanotubes (HNTs) were modified by polyaniline (PANI) and then used as nanocontainers to encapsulate the green corrosion inhibitor praseodymium (III) cations (Pr3+), obtaining HNTs@PANI@Pr3+nanoparticles. A scanning electron microscope, transmission electron microscopy, energy dispersive spectroscopy, Fourier transform infrared spectroscopy, X-ray diffraction, and thermogravimetric analysis were applied to characterize the formation of PANI and the absorption of Pr3+cations. The corrosion-inhibiting ability of the HNTs@PANI@Pr3+nanoparticles for iron sheets and the anticorrosion properties of the nanocomposite coatings were evaluated by the electrochemical impedance spectroscopy technique. The results indicated that the coating containing HNTs@PANI@Pr3+nanoparticles exhibited excellent anticorrosion performance. After immersion in 3.5 wt % NaCl solution for 50 days, its Zf=0.01 Hzvalue was still as high as 9.4 × 108Ω cm2. The icorrvalue was 3 orders of magnitude lower than that of the pure WEP coating. The excellent anticorrosion property of the HNTs@PANI@Pr3+coating could be attributed to the synergy of three beneficial factors, including evenly distributed nanoparticles, PANI, and Pr3+cations. This research will provide theoretical and technical support for the development of waterborne coatings with high corrosion resistance.

Large scale NiFe2O4nanowires were synthesized with NiO nanosheets as precursor by means of the topochemical solid state method. The morphologies and magnetic properties of NiFe2O4annealed at different temperatures were studied. An appropriate annealing temperature was requested to transfer NiO nanosheets and Fe–ions into NiFe2O4nanowires. In the beginning stage of synthesizing process, the shape of NiO nanosheets remained unchanged at low temperatures. And then, NiO nanosheets split into nanowires from 400 °C to 600 °C. At last they transformed into nanoparticles from 700 °C to 1000 °C. Thus, the optimized annealing temperature was selected as 600 °C because the NiFe2O4obtained at 600 °C(N600) exhibited a maximum aspect ratio of 50 with a diameter of 20 nm and a length of 1 μm. Furthermore, N600 also displayed the largest magnetization value of 26.86 A·m2/kg and the lowest coercivity(Hc) of 8914 A/m.

Acetaminophen (APAP) overdose is the leading cause of drug-induced liver injury. Compensatory liver regeneration is crucial for the final outcome of toxicant-induced injury. However, the molecular mechanisms underlying compensatory liver regeneration in mice after APAP-induced liver injury are not completely understood. This study aimed to investigate the role of dynamic and coordinated regulation of Kelch-like ECH-associated protein 1 (KEAP1)–nuclear factor erythroid 2–related factor 2 (NRF2)– antioxidant response element (ARE) and p53/p21 pathways in APAP injury-responsive liver regeneration. We found that mice exhibited massive hepatic toxicity during the first 12 hours after 400 mg/kg APAP treatment, but responsive liver recovery occurred beyond 24 hours as demonstrated by histopathological and biochemical assessments. The expression and nuclear accumulation of NRF2 was increased after APAP treatment. The expression of NAD(P)H:quinone oxidoreductase 1, glutamate-cysteine ligase modifier subunit, and heme oxygenase-1 was inhibited during the first 24 hours and then induced to limit oxidative damage. The content of p53 and its downstream target p21 were significantly increased upon APAP exposure and subsequently decreased to normal levels at 48 hours. Furthermore, levels of cyclin D1, cyclin D–dependent kinase 4, proliferating cell nuclear antigen, and augmenter of liver regeneration at 48 hours were enhanced, suggesting initiation of hepatocyte proliferation and tissue repair. These results demonstrated that dynamic and coordinated regulation of KEAP1-NRF2-ARE and p53/p21 signaling pathways was associated with compensatory liver regeneration after APAP-induced acute liver injury.

ChemInform is a weekly Abstracting Service, delivering concise information at a glance that was extracted from about 200 leading journals. To access a ChemInform Abstract of an article which was published elsewhere, please select a “Full Text” option. The original article is trackable via the “References” option.