Catalytic hydrogen transfer due to FeSO4 and Co&z.sbnd;Mo in coal liquefaction

The liquefaction behaviour of a Kentucky coal was studied in batch autoclave experiments at 410 °C under either a H₂ or a N₂ atmosphere (≈ 13.8 MPa) for reaction times of up to 2 h. To understand the catalytic roles of FeSO₄ and a Co&z.sbnd;Mo catalyst in coal liquefaction and to assess the feasibility of using FeSO₄ as a model for coal pyrites, effects of impregnation of the coal with FeSO₄ and direct charges of a Co&z.sbnd;Mo catalyst on coal liquefaction and tetralin dehydrogenation were examined. Both catalysts increase the conversion to benzene-soluble material by 7–10%, and improve the selectivity values for conversion to oil and gas. In addition they are also active in the dehydrogenation of tetralin. The dehydrogenation activities of these catalysts correlate with their catalytic activities during coal liquefaction. Analyses of the mean chemical structures and the product distributions of the coal-derived liquid from liquefaction in H₂ and in N₂ atmospheres indicate that:

1. (1) H-transfer from tetralin is the only major mechanism of coal liquefaction; and

2. (2) both pyrrhotite, generated in-situ from FeSO₄, and Co&z.sbnd; Mo catalyst can provide a major liquefaction mechanism by catalysing the H-transfer from the donor solvent to the coal or the coal-derived liquid.

     

Chemically-speciated on-road PM2.5 motor vehicle emission factors in Hong Kong

PM_2.5 (particle with an aerodynamic diameter less than 2.5 µm) was measured in different microenvironments of Hong Kong (including one urban tunnel, one Hong Kong/Mainland boundary roadside site, two urban roadside sites, and one urban ambient site) in 2003. The concentrations of organic carbon (OC), elemental carbon (EC), water-soluble ions, and up to 40 elements (Na to U) were determined. The average PM_2.5 mass concentrations were 229 ± 90, 129 ± 95, 69 ± 12, 49 ± 18 µg m^− 3 in the urban tunnel, cross boundary roadside, urban roadside, and urban ambient environments, respectively. Carbonaceous particles (sum of organic material [OM] and EC) were the dominant constituents, on average, accounting for ∼ 82% of PM_2.5 emissions in the tunnel, ∼ 70% at the three roadside sites, and ∼ 48% at the ambient site, respectively. The OC/EC ratios were 0.6 ± 0.2 and 0.8 ± 0.1 at the tunnel and roadside sites, respectively, suggesting carbonaceous aerosols were mainly from vehicle exhausts. Higher OC/EC ratio (1.9 ± 0.7) occurred at the ambient site, indicating contributions from secondary organic aerosols. The PM_2.5 emission factor for on-road diesel-fueled vehicles in the urban area of Hong Kong was 257 ± 31 mg veh^− 1 km^− 1, with a composition of ∼ 51% EC, ∼ 26% OC, and ∼ 9% SO₄⁼. The other inorganic ions and elements made up ∼ 11% of the total PM_2.5 emissions. OC composed the largest fraction (∼ 51%) in gasoline and liquid petroleum gas (LPG) emissions, followed by EC (∼ 19%). Diesel engines showed higher emission rates than did gasoline and LPG engines for most pollutants, except for V, Br, Sb, and Ba.     

SARS-CoV-2 Spike Protein and Mouse Coronavirus Inhibit Biofilm Formation by Streptococcus pneumoniae and Staphylococcus aureus

The presence of co-infections or superinfections with bacterial pathogens in COVID-19 patients is associated with poor outcomes, including increased morbidity and mortality. We hypothesized that SARS-CoV-2 and its components interact with the biofilms generated by commensal bacteria, which may contribute to co-infections. This study employed crystal violet staining and particle-tracking microrheology to characterize the formation of biofilms by Streptococcus pneumoniae and Staphylococcus aureus that commonly cause secondary bacterial pneumonia. Microrheology analyses suggested that these biofilms were inhomogeneous soft solids, consistent with their dynamic characteristics. Biofilm formation by both bacteria was significantly inhibited by co-incubation with recombinant SARS-CoV-2 spike S1 subunit and both S1 + S2 subunits, but not with S2 extracellular domain nor nucleocapsid protein. Addition of spike S1 and S2 antibodies to spike protein could partially restore bacterial biofilm production. Furthermore, biofilm formation in vitro was also compromised by live murine hepatitis virus, a related beta-coronavirus. Supporting data from LC-MS-based proteomics of spike–biofilm interactions revealed differential expression of proteins involved in quorum sensing and biofilm maturation, such as the AI-2E family transporter and LuxS, a key enzyme for AI-2 biosynthesis. Our findings suggest that these opportunistic pathogens may egress from biofilms to resume a more virulent planktonic lifestyle during coronavirus infections. The dispersion of pathogens from biofilms may culminate in potentially severe secondary infections with poor prognosis. Further detailed investigations are warranted to establish bacterial biofilms as risk factors for secondary pneumonia in COVID-19 patients.     

溶解性有机物的快速表征技术及其应用

综合介绍了溶解性有机物(DOM)及其去除特性,重点阐述了DOM快速表征技术的特点,并对树脂吸附分级、HPSEC/超滤以及S::CAN在线检测技术的研究现状、技术应用与实际案例进行了系统分析与讨论.表明快速分级法(RF)是表征饮用水NOM的简便、有效的方法,运用该方法可及时掌握原水变化和状态,为水厂运行和管理提供指导.     

Using 10 Gb/s remodulation DPSK signal in self-restored colorless WDM-PON system

In this investigation, we propose and experimentally demonstrate the remodulation technique using DPSK format in both downlink and uplink traffics with high extinction ratio (ER) in colorless WDM-PON; together with a simple self-restored architecture against fiber fault. Error free operation was achieved in a 20-km-reach 10-Gb/s WDM-PON without dispersion compensation. Comparison with other wavelength remodulation schemes for WDM-PONs is also performed, showing the proposed scheme can be a potential candidate for next generation wavelength reuse WDM-PONs. In addition, the performance of self-protection has also been discussed and analyzed.     

Interpenetrating polymer network structured thermosets prepared from epoxidized soybean oil/diglycidyl ether of bisphenol A

Epoxidized soybean oil (ESO)/diglycidyl ether of bisphenol A (DGEBA) in various blend ratios (i.e. 100/0, 90/10, 80/20, 70/30, 60/40, 50/50) was thermally cured using methylhexahydrophthalic anhydride in the presence of 2‐ethyl‐4‐methylimidazole catalyst. The tensile properties and fracture toughness of the ESO/DGEBA thermoset blends were determined. Thermal properties of the blends were characterized using dynamic mechanical analysis, differential scanning calorimetry and thermogravimetric analysis. Blending of ESO and DGEBA gave synergistic effects on the modulus, strength, glass transition temperature and thermal stability. However, the fracture toughness and elongation at break of ESO/DGEBA blends are lower than those of ESO, as expected. The enhancement in certain mechanical and thermal properties of ESO/DGEBA can be associated with the crosslink density, gel content and possible interpenetrating network of the resulting thermoset blends. © 2013 Society of Chemical Industry     

Experimental evaluation of ventilated glazing performance in Hong Kong

Window glazing affects much the indoor environment and the energy use in buildings. While double glazing has better thermal performance than single glazing, the airflow window options carry additional advantage of directly removing the absorbed solar energy in glass panes. This paper reports an experimental study in Hong Kong in evaluating the thermal/energy performance of the above‐mentioned glazing systems. A new approach of using numerical simulation technique to improve the quality of experimental analysis was introduced. Our findings show that the natural‐ventilated glazing system has a better thermal performance than the double‐glazing system since the latter received 13.6% more convective heat gain. The main advantage of the exhaust‐ventilated glazing system lies in the decrease of convective heat transfer to 34.3% of the double glazing, and 19.4% of the single‐glazing types. The results showed that the ventilated glazing schemes in association with daylight utilization could lead to substantial electricity savings in the office environment. Copyright © 2008 John Wiley & Sons, Ltd.     

Scanning Electron Microscopy of Fe79.5B6.5C14 Network Alloys: Part I

Molten Fe_79.5B_6.5C₁₄ melts can be cast into ingots of networklike microstructure. According to microstructural classification, a Fe_79.5B_6.5C₁₄ network specimen can be divided into three zones. Zone A is occupied by a random network, zone B by a uniformly aligned network, and zone C by a severely aligned network that exhibits network patterns.     

New symmetrical buffer design for VLSI applications

Novel fast buffers by the transient part circuit technique are described in this paper. The proposed circuits are fully symmetrical in their structure, therefore the design is straightforward and the well balanced speed can be easily obtained. As compared with prior work, the delay ratio of this work is over 300% and 10% balance improvement, respectively. While based on a design criterion of the same area the proposed buffer circuit shows 27% and 76% average speed enhancements on propagation delays with only 7.3% average increase in its power consumption.     

Experimental Demonstration of Novel High-Voltage Epilayer RESURF GaN MOSFET

We report on the experimental demonstration of a novel n-channel GaN epilayer RESURF GaN MOSFET with good tradeoff between breakdown voltage and specific on-resistance for the first time. Device with 4-mum channel length and 16-mum RESURF length has breakdown voltage up to 730 V with specific on-resistance 34 mOmegamiddotcm² (V_G - V_T = 20 V), best reported to date.