Visible-light-driven photocatalytic inactivation of E. coli K-12 by bismuth vanadate nanotubes: bactericidal performance and mechanism

Bismuth vanadate nanotube (BV-NT), synthesized by a template-free solvothermal method, was used as an effective visible-light-driven (VLD) photocatalyst for inactivation of Escherichia coli K-12. The mechanism of photocatalytic bacterial inactivation was investigated by employing multiple scavengers combined with a simple partition system. The VLD photocatalytic bacterial inactivation by BV-NT did not allow any bacterial regrowth. The photogenerated h(+) and reactive oxidative species derived from h(+), such as OH(ads), H(2)O(2) and HO(2)/O(2)(-), were the major reactive species for bacterial inactivation. The inactivation by h(+) and OH(ads) required close contact between the BV-NT and bacterial cells, and only a limited amount of H(2)O(2) could diffuse into the solution to inactivate bacterial cells. The direct oxidation effect of h(+) to bacterial cells was confirmed by adopting F(-) surface modification and anaerobic experiments. The bacterial cells could trap e(-) in order to minimize e(-)-h(+) recombination, especially under anaerobic condition. Transmission electron microscopic study indicated the destruction process of bacterial cell began from the cell wall to other cellular components. The OH(ads) was postulated to be more important than OH(bulk) and was not supposed to be released very easily in the BV-NT bacterial inactivation system.     

超细硫酸沙丁胺醇药物颗粒的制备与表征

以沙丁胺醇和硫酸为反应物,在异丙醇溶液中采用反应结晶法制备超细硫酸沙丁胺醇颗粒。对影响产物粒度和产率的因素,如:硫酸浓度、反应温度、搅拌转速、反应时间等进行了系统研究。实验结果表明:当硫酸浓度为1.0mol.L-1、反应温度为15℃、搅拌转速为900r.min-1、反应时间为10min时,可以得到短轴为50~60nm、长径比为20~35且粒度分布较窄的针状硫酸沙丁胺醇颗粒。产品经IR、XRD等验证,符合中国、英国药典的要求,纯度大于98%。     

Synergistic bimetallic Ru–Pt catalysts for the low-temperature aqueous phase reforming of ethanol

Aqueous phase reforming (APR) of ethanol has been studied over a series of Ru and Pt catalysts supported on carbon and titania, with different metal loadings and particle sizes. This study proposed that, on both metals, ethanol is first dehydrogenated to acetaldehyde, which subsequently undergoes C C cleavage followed by different paths, depending on the catalyst used. For instance, although monometallic Pt has high selectivity toward H₂ via dehydrogenation, it has a low efficiency for C C cleavage, lowering the overall H₂ yield. Large Ru particles produce CH₄ through methanation, which is undesirable because it consumes H₂. Small Ru particles have lower activity but higher selectivity toward H₂ rather than CH₄. On these small particles, CO blocks low-coordination sites, inhibiting methanation. The combination of the two metals in bimetallic Ru–Pt catalysts results in improved performance, benefiting from the desirable properties of each Ru and Pt, without the negative effects of either. © 2018 American Institute of Chemical Engineers AIChE J, 65: 151–160, 2019     

Sonochemical fabrication, characterization and photocatalytic properties of Ag/ZnWO4 nanorod catalyst

A ZnWO₄ nanocrystal catalyst with rod-like structure was first synthesized by powerful ultrasonic irradiation method at room temperature. Then, Ag was introduced to ZnWO₄ nanorods by a photodeposited method. The as-synthesized Ag/ZnWO₄ catalysts have been investigated by photocatalytic reaction tests and some physicochemical characterizations like XRD, BET, IR, TEM, EDX, XPS, PL, and UV–vis DRS. The results show that the prepared samples have good crystallinity and Ag addition can improve the photocatalytic performance of ZnWO₄ in degradation of rhodamine-B (RhB) under UV light irradiation. The deposition of 1 wt% Ag over ZnWO₄ leads to about a one-time increase in the photocatalytic performance with the reference of ZnWO₄. The high performance of Ag/ZnWO₄ could be attributed to the fact that the high dispersed Ag particles could act as electron traps promoting the electron–hole separation then enhancing the photocatalytic reaction.     

Geometric strategies for attainment of identical outflows through all of the exit ports of a distribution manifold in a manifold system

The focus of this investigation is to identify strategies whose application is capable of perfecting manifold design to achieve the same rate of mass outflow through each of the exit ports of a distribution manifold. A quantitative systematic study based on numerical simulation is performed in which each of eight proposed strategies is evaluated with regard to its capability for producing the same per-exit-port mass outflow. Each of the strategies is geometric in nature and is characterized by geometrical parameters which can be varied systematically in order to attain outflow uniformity. A quantitative metric, the standard deviation from uniformity of the individual outflows through the exits of the distribution manifold, was used to identify the degree of mass outflow uniformity that was achieved by the use of the various parameter values which characterize each strategy. The end result of the study is the identification of the certain strategies that are most effective for the attainment of the goal of outflow uniformity. These are: (a) enlargement of the cross-sectional area of the distribution manifold (Section 4.1), (b) variation of the cross-sectional areas of the outflow channels (Section 4.5), (c) linear tapering of the cross-sectional area of the distribution manifold, and (d) non-linear tapering of the cross-sectional area of the manifold by means of quarter-elliptical contouring of the manifold wall (Section 4.3).     

Effect of surface charge on the cellular uptake and cytotoxicity of fluorescent labeled cellulose nanocrystals

Probing of cellular uptake and cytotoxicity was conducted for two fluorescent cellulose nanocrystals (CNCs): CNC-fluorescein isothiocyanate (FITC) and newly synthesized CNC-rhodamine B isothiocyanate (RBITC). The positively charged CNC-RBITC was uptaken by human embryonic kidney 293 (HEK 293) and Spodoptera frugiperda (Sf9) cells without affecting the cell membrane integrity. The cell viability assay and cell-based impedance spectroscopy revealed no noticeably cytotoxic effect of the CNC-RBITC conjugate. However, no significant internalization of negatively charged CNC-FITC was observed at physiological pH. Indeed, the effector cells were surrounded by CNC-FITC, leading to eventual cell rupture. As the surface charge of CNC played an important role in cellular uptake and cytotoxicity, facile surface functionalization together with observed noncytotoxicity rendered modified CNC as a promising candidate for bioimaging and drug delivery systems.     

What is a Hole? Discovering Access Holes in Disaster Rubble with Functional and Photometric Attributes

The collapse of buildings and other structures in heavily populated areas often results in human victims becoming trapped within the resulting rubble. This rubble is often unstable, difficult to traverse, and dangerous for emergency first responders tasked with finding, stabilizing, and extricating entombed or hidden victims through access holes in the rubble. Recent work in scene mapping and reconstruction using photometric color and metric depth (RGB‐D) data collected by unmanned aerial vehicles (UAVs) suggests the possibility of automatically identifying potential access holes into the interior of rubble. This capability would greatly improve search operations by directing the limited human search capacity to areas where access holes might exist. This paper presents a novel approach to automatically identifying access holes in rubble. The investigation begins by defining an access hole in terms that allow for their algorithmic identification as a potential means of accessing the interior of rubble. This definition captures the functional and photometric attributes of holes. From this definition, a set of hole‐related features for detection is presented. Experiments were conducted using RGB‐D data collected over a real‐world disaster training facility using a UAV. Empirical evaluation suggests the efficacy of the proposed approach for successfully identifying potential access holes in disaster rubble.     

Effect of brine immersion freezing on the determination of ecological tracers in fish

The use of a multi-ecological tracer approach provides valuable and complementary insights to investigate the complex biology and ecology of large pelagic fish. Brine immersion freezing is the most common preservation technique used onboard for large fish to be frozen whole until they are delivered for sale and processing. We evaluated the effect of brine freezing on lipid and fatty acid composition, C and N stable isotope ratios, and organochlorine contaminant levels of yellowfin tuna (Thunnus albacares) and skipjack tuna (Katsuwonus pelamis). Fresh tunas were stored in a saturated sodium chlorine brine immersion tank maintained at ?20 °C for 6 weeks, and ecological tracers were analysed on dorsal muscle samples collected before and after brine freezing. No significant effect of the fish preservation technique was found except for δ¹⁵N whose signatures slightly increased after a 6-week period of brine immersion. Because N isotopic shift was close to the analytical precision and probably related to a higher risk of salt penetration in small tunas with abraded skin, we consider our results as conservative and conclude that ecological tracers can indeed be analysed on brine-freezing-preserved tunas.     

Knowledge-based qualification tests for electronic components in harsh environments

The objectives of this paper are to propose a practical procedure for knowledge-based reliability qualification, and provide a checklist of required information for qualification analysis and testing. The paper investigates the common failure mechanisms of electronic components in automotive environments, and addresses the role of physics-of-failure approach in component reliability qualification.