The particle and astrophysical xenon experiment III (PandaX-III) is aimed to search for the Neutrinoless Double Beta Decay (NLDBD) using 200-kg radio-pure high-pressure gaseous xenon time projection chamber (TPC) with Micromegas detectors at both ends. A small-scale prototype TPC equipped with seven Microbulk Micromegas modules has been developed. Each Micromegas module has 128 anode strip signals to be processed. Highly integrated front-end electronics composed of four front-end cards (FECs) with 1024 channels are designed to read out the charge of Micromegas anode signals digitize the waveform after shaping and send compressed data to the data collection module (DCM). The cornerstone of the front-end electronics is a 64-channel application-specific integrated circuit (ASIC) named AGET, which is based on switched capacitor arrays (SCAs). According to the test results, the integral nonlinearity (INL) of the front-end electronics is less than 1%, and the noise of each readout channel with the input floating is less than 0.9 fC on the condition of 1-mu s peaking time and 1-pC dynamic range. Joint tests of front-end electronics with the prototype TPC were carried out using the radioactive sources Cs-137 and Am-241. The hit map of the Micromegas modules and the energy spectrum have been reconstructed successfully, and the results are satisfying.
An advanced optical design for a low-cost and astigmatism-corrected spectrometer with a high resolution is presented. The theory and method of astigmatism correction are determined with the use of a concave toroidal mirror. The performances of a modified spectrometer and a traditional spectrometer are compared, and the analysis is verified. Experimentally, the limiting resolution of our spectrometer is 0.1 nm full width at half-maximum, as measured for 579.1 nm. (C) 2016 Optical Society of America
The urbanized world has brought social, economic, and environmental sustainability into challenged surroundings in rapidly rising countries, thereby requiring the exploration of their intertwined relationships. This study regarded Brazil, India, and China as "BIC" countries to be the representative study areas for our investigation of sustainability in the context of rapid urbanization. In general, our work was synthesized into a comparison framework in four aspects: rural-urban relation, industrial development, city development, and urban landscape pattern. We determined that rural-urban dichotomy exists in all study areas, with India and China having a high degree. China was identified as a manufacturing-based country in the past half-century, whereas Brazil and India have the service sector as their primary industry. The distribution of large cities follows a regional pattern, with Brazil being northeast-focused, China being southeast-focused, and India being comparatively balanced. The Amazon forest in the north brings great challenges to Brazil with respect to the conservation of its biodiversity and eco-environment. India and China have encountered tremendous urban expansion or sprawl in the past several decades. The sustainability issues in social, economic, and environmental aspects for Brazil, India, and China were summarized in the context of rapid urbanization to provide references for other countries.
Adenovirus is widely used in gene therapy and vaccination as a viral vector, and its hypervariable regions (HVRs) on hexon are the main antigen recognition sites of adenovirus. The modification of this area by genetic engineering will change the antigenic specificity of the virus. In addition, recent studies have demonstrated the importance of coagulation factor X (FX) in adenovirus serotype 5-mediated liver transduction in vivo. The binding site of adenovirus to FX is the HVRs on hexon. By constructing five proteins containing chimeric HVRs from different adenovirus serotypes, we focused on the antigenic specificity and the affinity for FX of these proteins compared with the corresponding viruses. Our data showed that HVR5 and HVR7 had only a part of hexon activity to neutralizing antibodies (NAbs) compared with the complete activity of HVR1-7. Results also demonstrated a differential high-affinity interaction of the HVRs proteins with FX and indicated that HVRs protein had a similar binding ability with corresponding adenovirus serotype. These results highlighted some properties of chimeric HVRs proteins and revealed the influence on the structure and function of hexon proteins and adenovirus resulting from the HVRs. (C) 2012 Elsevier Inc. All rights reserved.
Surface emitting distributed feedback (SE-DFB) semiconductor lasers with second-order grating have become one of research hotspots due to be in terms of high beam quality, narrow linewidth and so on. The diffraction and feedback of the second-order grating are utilized to achieve wavelength stabilization and surface emitting. In the paper, SE-DFB laser with asymmetric waveguide is designed, and the effect of waveguide structures on slope efficiency is discussed. The results show that the slope efficiency of SE-DFB laser with P-asymmetric waveguide is 1.04 W/A which enhances 0.12 W/A than the device with symmetric waveguide. It provides an idea for SE-DFB laser research.
The DArk Matter Particle Explorer (DAMPE) is a space experiment designed to search for dark matter indirectly by measuring the spectra of photons, electrons, and positrons up to 10 TeV. The BGO electromagnetic calorimeter (ECAL) is its main sub-detector for energy measurement. In this paper, the instrumentation and development of the BGO ECAL is briefly described. The calibration on the ground, including the pedestal, minimum ionizing particle (MIP) peak, dynode ratio, and attenuation length with the cosmic rays and beam particles is discussed in detail. Also, the energy reconstruction results of the electrons from the beam test are presented. (C) 2016 Elsevier B.V. All rights reserved.
Inspired by lotus leaves, self-floating Janus cotton fabric is successfully fabricated for solar steam generation with salt-rejecting property. The layer-selective soot-deposited fabrics not only act as a solar absorber but also provide the required superhydrophobicity for floating on the water. With a polyester protector, the prepared Janus evaporator exhibits a sustainable evaporation rate of 1.375 kW m(-2) h(-1) and an efficiency of 86.3% under 1 sun (1 kW m(-2)) and also performs well under low intensity and inclined radiation. Furthermore, no special apparatus and/or tedious processes are needed for preparing this device. With a cost of less than $1 per m(2), this flexible Janus absorber is a promising tool for portable solar vapor generator.
Background: Efficacy of recombinant adenovirus serotype 5 (rAd5) vaccine vectors for human immunodeficiency virus type 1 (HIV-1) and other pathogens have been shown to be limited by high titers of pre-existing Ad5 neutralizing antibodies (NAbs) in the developing world. Results: Using a secreted embryonic alkaline phosphatase (SEAP) neutralization assay, 50% serum neutralization titers against rAd2 and rAd5 vectors were measured in samples from 274 infants and young children in northeast China. The pediatric population was found to be 59.6% and 43.3% seropositive for rAd2 and rAd5, respectively. Of all participants, 44.9% had moderate and high (> 200) and 25.6% had high (> 1000) Ad2 NAb titers, compared with the corresponding rates of 26.6% and 9.3% against Ad5. Marked age-dependent increases in NAb titers to both Ad serotypes were observed across five age groups, with the exception of infants in the 0-6-month group commonly having relatively high titers due to pre-existing maternal antibodies. Conclusions: Our data suggest that Ad-based therapies may be suitible for children in the 7-12-month age range in this region.
Despite of the extensive effort made to construct a superhydrophobic surface in labs, achieving a short processing time and via a sustainable production route remains a challenge for practical applications. Here, with tetrahydrofuran and n-hexane as co-solvent, we demonstrate that roughness can be induced on polydimethylsiloxane (PDMS) coatings to achieve superhydrophobic coatings on different types of substrates including woven fabrics, non-woven fabrics, and melamine sponge. The sample constructed without adding particles exhibited excellent performance for versatile oil-water separation of mixtures of heavy oil and water, light oil and water, as well as oil-water emulsion. Due to the good solubility of the PDMS in the co-solvent, the dipping solution exhibited a long-time stability. Moreover, the abundant CH3 provided by the self-roughness PDMS coating helped the substrates recover its superhydrophobic property even after destroyed by plasma for 10 times. We believe that this extremely easy dipping-curing method would open up a new direction for fabricating a series of self-roughed superhydrophobic surface with self-healing property. Besides, the developed strategy is fast and easily scalable for industrial applications.
Sluggish kinetics of the multielectron transfer process is still a bottleneck for efficient oxygen evolution reaction (OER) activity, and the reduction of reaction overpotential is crucial to boost reaction kinetics. Herein, a correlation between the OER overpotential and the cobalt-based electrode composition in a "Microparticles-in-Spider Web" (MSW) superstructure electrode is revealed. The overpotential is dramatically decreased first and then slightly increased with the continuous increase ratio of Co/Co3O4 in the cobalt-based composite electrode, corresponding to the dynamic change of electrochemically active surface area and charge-transfer resistance with the electrode composition. As a proof-of-concept, the optimized electrode displays a low overpotential of 260 mV at 10.0 mA cm(-2) in alkaline conditions with a long-time stability. This electrochemical performance is comparable and even superior to the most currently reported Co-based OER electrocatalysts. The remarkable electrocatalytic activity is attributed to the optimization of the electrochemically active sites and electron transfer in the MSW superstructure. Theoretical calculations identify that the metallic Co and Co3O4 surface catalytic sites play a vital role in improving electron transport and reaction Gibbs free energies for reducing overpotential, respectively. A general way of boosting OER kinetics via optimizing the electrode configurations to mitigate reaction overpotential is offered in this study.
Adenoviruses (Ads) are non-enveloped DNA viruses that have been extensively studied and used as vectors for gene therapy and several potential vaccines. There are 57 Ad serotypes in seven species (A-G), and Ad neutralizing antibody (NAb) titres can vary by serotype and geographical location. Until now serotype- and species-specific antibodies have been detected by neutralization or haemagglutination inhibition assays. These expensive and cumbersome methods of adenovirus typing have mainly been used in epidemiological studies. Our prior work demonstrated that NAbs against the fiber protein are commonly generated during natural Ad infection in humans and the trimeric knob is preferentially recognized by fiber-induced NAbs. In this study, we expressed nine trimeric knob proteins from representative Ad serotypes of human Ad (HAdV)-A-F in Escherichia coli and found no cross-reactivity of these recombinant proteins with rabbit hyperimmune sera (among HAdV-A-F or within HAdV-C). Results of the ELISA based on Ad2 and Ad5 (both HAdV-C) knob proteins were consistent with those of neutralization assays, indicating that the trimeric knob protein would be a good candidate antigen for detecting Ad serotype-specific NAbs in sera from naturally infected subjects. We also demonstrated the primary seroepidemiology of nine Ad serotypes in 274 children using the knob-based ELISA. These results have potential implications for epidemiology of Ad serotypes and future development of Ad-based vaccines and gene therapy. =C2=A9 2014 The Authors.
The primary challenge of photocatalytic hydrogen generation is to exploit a catalyst with good durability and low cost. Here, we designed a facile and efficient process of loading silver nanoparticles (Ag NPs) in situ on the core-shell nanocomposite of the elongated titanium dioxide nanotubes with a carbon layer (C@TiO2 NTs) by polydopamine (PDA) without addition of any binder. The combination of C@TiO2 NTs with Ag NPs has excellent performance toward photocatalytic hydrogen production and degradation of rhodamine B (RhB) under visible light irradiation. The characterizations (SEM, TAM, XRD, XPS, etc.) showed that the carbon layer on nanotubes could conformably cover the whole of TiO2 NTs to form the core-shell structure, which not only prevented Ag NPs from aggregating but also acted as the electronic transport channel. Meanwhile, Ag NPs were uniformly distributed on the surface of C@TiO2 NTs. In conclusion, under the synergistic effect of Ag nanoparticles and the outer-carbon layer, the utilization efficiency of visible light has been enhanced, and the recombination of electrons/holes has been suppressed for Ag@C@TiO2 NTs nanocomposites. Therefore, the degradation efficiency of RhB and hydrogen generation rate are 2.5 times and 4.8 times higher than those of the pure TiO2 NTs, respectively. This work may provide fruitful experience for developing a novel strategy into the design and fabrication of stable and highly active visible-light catalysts with noble metal modification toward sustainable hydrogen production in the energy filed.
The ability to reproducibly create a surface enhanced Raman scattering (SERS) substrate renders an effective means of detecting and degrading organic contaminants. Vertically aligned (VA) nanomaterials have been extensively explored as highly efficient catalysts due to their excellent electron transportability and high concentration of exposed active edge sites. Herein, we report on a ternary ultrafast-electron-transfer heterostructure composed of Pt nanoparticles in-situ grown on VA-MoS2 nanosheet edge sites decorated on TiO2 nanotube arrays (NTAs) (denoted Pt/VA-MoS2/NTAs). Compared with pristine TiO2 NTAs, the Pt/VA-MoS2/NTAs possess a strong resonant SERS effect for detecting rhodamine 6G and an outstanding UV-assisted self-cleaning effect, displaying an excellent photocatalytic performance under visible light irradiation. Such markedly improved performance of the ternary Pt/VA-MoS2/TiO2 NTAs nanocomposites can be attributed to the synergy of catalytic activity of Pt-deposited MoS2 edge sites, the ultrafast electron transfers of VA-MoS2 NS/TiO2 NTAs, and the appropriate band alignment among these three constituents. As such, it represents a robust mean of developing advanced energy utilization nanocomposites for high-performance catalysts and sensors.