Epitaxial Magnetic Oxide Nanocrystals Via Phase Decomposition of Bismuth Perovskite Precursors

The phase instability of bismuth perovskite (BiMO₃), where M is a ferromagnetic cation, is exploited to create self‐assembled magnetic oxide nanocrystal arrays on oxide supports. Conditions during pulsed laser deposition are tuned so as to induce complete breakdown of the perovskite precursor into bismuth oxide (Bi₂O₃) and metal oxide (M‐O_x) pockets. Subsequent cooling in vacuum volatizes the Bi₂O₃ leaving behind an array of monodisperse nanocrystals. In situ reflective high energy electron diffraction beam is exploited to monitor the synthesis in real‐time. Analysis of the patterns confirms the phase separation and volatization process. Successful synthesis of M‐O_x, where M = Mn, Fe, Co, and Cr, is shown using this template‐free facile approach. Detailed magnetic characterization of nanocrystals is carried out to reveal the functionalities such as magnetic anisotropy as well as larger than bulk moments, as expected in these oxide nanostructures.     

Dietary exposure of Hong Kong secondary school students to total mercury and methylmercury from fish intake

Fish is the main source of dietary exposure to methylmercury (MeHg), which is a public health concern owing to its potential neurotoxicity. To evaluate the public health risk, this study estimated the total mercury (tHg) and MeHg exposure from fish intake in Hong Kong secondary school students. Median tHg and MeHg concentrations of 280 samples purchased from different commercial outlets (covering 89 species of whole fish and three types of canned tuna), together with the local food consumption data of secondary school students obtained by semi-quantitative food frequency questionnaire in 2000, were used to estimate dietary exposure from fish intake for the average and high consumer (95th percentile exposure). For tHg, the median concentration was 63 µg kg^–1 (range 3–1370 µg kg^–1) and estimated exposures ranged 0.5–0.6 µg kg^–1 body weight (bw) week^–1 for an average consumer and 1.6–1.9 µg kg^–1 bw week^–1 for a high consumer. For MeHg, median concentration was 48 µg kg^–1 (range 3–1010 µg kg^–1) and estimated dietary exposures were 0.4–0.5 µg kg^–1 bw week^–1 for an average consumer and 1.2–1.4 µg kg^–1 bw week^–1 for a high consumer. These values are below the respective provisional tolerable weekly intake (PTWI) established by the Joint Food and Agriculture Organization/World Health Organization Expert Committee on Food Additives (JECFA). The health risk is greater for high consumers since MeHg exposures may approach or exceed the PTWI when other dietary sources are taken into account.     

Chitosan/Clotrimazole microcapsules for Tinea pedis treatment: in-vitro antifungal and cytotoxicity study

To derive a form of treatment for Tinea pedis (also known as athlete’s foot), an attempt has been made to synthesize chitosan microcapsules that contain an antifungal agent using a coacervation technique. The antifungal agent, namely, clotrimazole, is encapsulated in different amounts: 25, 50, 75, and 100?mg. Optical and scanning electron microscopies demonstrate that the newly developed microcapsules have spherical core–shell forms with smooth surfaces and the particle sizes range from 2 to 10?μm. It is observed that chitosan microcapsules with a drug input of 25?mg clotrimazole show the highest encapsulation efficiency when compared with microcapsules that have 50, 75, and 100?mg of drug input. An analysis of the in vitro antifungal activity confirms that the chitosan/clotrimazole microcapsules show obvious inhibition of Trichophyton rubrum growth. The cytotoxicity results show that the newly developed microcapsules are non-cytotoxic to skin cell lines. The prepared drug-loaded microcapsules could be applied onto bandages or socks, and will continuously release antifungal drugs in a controlled manner under pressure.     

Automated online solid-phase extraction of albendazole and its metabolites in Chinese mitten crabs followed by stable isotope dilution UPLC–MS/MS analysis

The determination of albendazole (ABZ) and its metabolites, albendazole sulfoxide, albendazole sulfone, and albendazole 2-aminosulfone in crab tissue is a complex analysis involving the extraction of trace levels of potentially unstable analytes from a solid matrix. Here, we report on an online solid-phase extraction (SPE) for automated trapping of ABZ and its metabolites in Chinese mitten crab, Eriocheir sinensis H. Milne Edwards (E. sinensis), followed by stable isotope dilution UPLC–MS/MS analysis. The performance of online SPE was fully validated. Good linearity was obtained with correlation coefficients >0.99. In the analytical range, the intra-day and inter-day precision and accuracies (RSD %) were 1.44–4.62 and 3.28–6.93 %, respectively. The mean recoveries were in the range of 78.2–109.3 %. All these demonstrated that the online SPE is an excellent technique for trapping and purification of ABZ and its metabolites in crab tissue samples. Finally, this online SPE–UPLC–MS/MS strategy was successfully applied to analyze the crude extracts from several crab tissue samples.     

Design and Implementation of a Technique for Iterative Magnetorheological Jet Polishing

This article introduces a technique for iterative high precision freeform lens polishing, with operations alternating between a fabrication and a measurement unit. The technique is implemented using a Magnetorheological Jet Polishing (MJP) machine as fabrication unit, and a sub-aperture stitching interferometric system as measurement unit. The two units are separately located and have different internal coordinate references. Precision integration of the two is the key to realize high performance iterative polishing. In our study, application of the proposed technique yields a peak to valley (PV) value of 1/7λ in polishing flat optical elements.     

Current production by bacterial communities in microbial fuel cells enriched from wastewater sludge with different electron donors

Electricity production by bacterial communities enriched from wastewater sludge with lactate, succinate, N-acetyl-D-glucosamine (NAG), acetate, formate, and uridine were monitored in dual-chamber microbial fuel cells (MFCs). Stable electricity production was observed after 300 h for communities enriched from lactate, acetate, and formate, while communities enriched with succinate, NAG, and uridine stabilized only after 700 h. The average peak current densities and maximum power densities generated from bacterial consortia were significantly higher than those generated from pure cultures of Shewanella oneidensis MR-1. Microbial assemblages were analyzed by DGGE, and planktonic and anode-attached bacterial communities varied as a function of electron donors: Firmicutes, β-Proteobacteria, and Bacteroidetes dominated the planktonic bacterial communities while anode-attached communities consisted mainly of δ-Proteobacteria, β-Proteobacteria, and Firmicutes. Similar bacterial populations were enriched in MFCs fed with lactate, NAG, and uridine and with succinate, acetate, and formate. Cross-feeding experiments with different fuels indicated that enriched microbial consortia were able to utilize a variety of fuel sources and displayed considerable stability, efficiency, and robustness of power generation in comparison to pure cultures. In addition, characterizations of cultivated Shewanella strains suggested that DGGE analysis likely missed active members of exoelectrogenic populations.     

Etching of <Superscript>10</Superscript>Boron with SF<Subscript>6</Subscript>-based Electron Cyclotron Resonance Plasmas for Pillar-Structured Thermal Neutron Detectors

Isotopically enriched ¹⁰boron for use in pillar-structured neutron detectors was successfully etched in an electron cyclotron resonance (ECR) plasma using SF₆-based plasmas. The effects of radio frequency (RF) power, ECR power, gas flow rate, H₂ and O₂ incorporation into the plasma, and gas mixture ratios were examined. Etch rates up to approximately 1.35 μm/min were realized. In addition, etch morphology was examined, and the final shape of ¹⁰boron-coated pillars could be controlled through the etch gas mixture utilized. Selectivity to the underlying Si structure was apparent from scanning electron microscopy (SEM) micrographs of completed etches.     

An efficient retinex-like brightness normalization method for coding camera flashes and strong brightness variation in videos

Conventional hybrid video coding systems rely on the assumption that the brightness is constant. This does not take inter-frame brightness variations into consideration during motion estimation and compensation processes. Under the influence of inter-frame lighting variations like camera flashes, video motion activities are not accurately estimated and the pixel prediction is poor which directly increases the bits for prediction error coding. In this paper, we propose an efficient algorithm based on the retinex-like system which allows inter-frame brightness being normalized before applying the conventional motion estimation and compensation. Experimental results show that our approach is superior to all similar approaches in the literature and demonstrate that our proposed system is very robust against the inter-frame brightness variations. Further experimental works have been done using the verification models of the MPEG-4 and the H.264 on sequences with brightness variations, results of which show that our proposed system outperforms these coding systems, including the weighted prediction feature in H.264, which were specifically designed for this purpose.     

Exploiting Reactive Mobility for Collaborative Target Detection in Wireless Sensor Networks

Recent years have witnessed the deployments of wireless sensor networks in a class of mission-critical applications such as object detection and tracking. These applications often impose stringent Quality-of-Service requirements including high detection probability, low false alarm rate, and bounded detection delay. Although a dense all-static network may initially meet these Quality-of-Service requirements, it does not adapt to unpredictable dynamics in network conditions (e.g., coverage holes caused by death of nodes) or physical environments (e.g., changed spatial distribution of events). This paper exploits reactive mobility to improve the target detection performance of wireless sensor networks. In our approach, mobile sensors collaborate with static sensors and move reactively to achieve the required detection performance. Specifically, mobile sensors initially remain stationary and are directed to move toward a possible target only when a detection consensus is reached by a group of sensors. The accuracy of final detection result is then improved as the measurements of mobile sensors have higher Signal-to-Noise Ratios after the movement. We develop a sensor movement scheduling algorithm that achieves near-optimal system detection performance under a given detection delay bound. The effectiveness of our approach is validated by extensive simulations using the real data traces collected by 23 sensor nodes.