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Silicon carbide (SiC) is a kind of structural ceramics with excellent properties and it is widely used in industrial fields. Stereolithography (SL) is a potential additive manufacturing technique to fabricate fine complex SiC components, the resin-based SiC slurry with superior rheological and photo-polymerization properties is important for SL. In this paper, we investigated the influence of SiC powder on the properties of the SiC slurries for SL. The physical characteristics of SiC powder such as particle size, size distribution and appearance were tested and observed, and their influence on the dispersion, sedimentation and photo-polymerization property of the SiC slurry were investigated and discussed in detail based on their correlative theory, we finally prepared SiC slurry with superior rheological and photo-polymerization properties, and fabricated the fine complex SiC green body with low defects, high accuracy and high bending strength successfully. The SiC slurry with the solid content of 40 vol% was fabricated by the SiC powder with the median diameter D50 ≈ 10.0 μm and a narrow particle size distribution, it is Bingham fluid with good fluidity and the viscosity of it is 464.40 mPa s under the shear rate of 51.08 s−1, the cured SiC parts with Z – axis dimension change of 0.75% was finally fabricated, the three points bending strength of it is 50.18 MPa. Our research work provides some fundamental understanding of the SL technique for fabricating fine complex SiC components, explored a suitable way to fabricate high quality SiC green parts through SL, and offers some valuable references for preparing SiC slurry with superior rheological and photo-polymerization properties.

The COVID-19 pandemic made clear how our society requires quickly available tools to address emerging healthcare issues. Diagnostic assays and devices are used every day to screen for COVID-19 positive patients, with the aim to decide the appropriate treatment and containment measures. In this context, we would have expected to see the use of the most recent diagnostic technologies worldwide, including the advanced ones such as nano-biosensors capable to provide faster, more sensitive, cheaper, and high-throughput results than the standard polymerase chain reaction and lateral flow assays. Here we discuss why that has not been the case and why all the exciting diagnostic strategies published on a daily basis in peer-reviewed journals are not yet successful in reaching the market and being implemented in the clinical practice. We acknowledge funding from the European Union Horizon2020 Programme under Grant No. 881603 (Graphene Flagship Core 3). We acknowledge Consejo Superior de Investigaciones Científicas (CSIC) for the project “COVID19-122” granted in the call “Nuevas ayudas extraordinarias a proyectos de investigación en el marco de las medidas urgentes extraordinarias para hacer frente al impacto económico y social del COVID-19 (Ayudas CSIC–COVID-19)”. We acknowledge the MICROB-PREDICT Project for partially supporting the work. The MICROB-PREDICT project has received funding from the European Union’s Horizon 2020 research and innovation programme under Grant No. 825694. This reflects only the author’s view, and the European Commission is not responsible for any use that may be made of the information it contains. We also acknowledge Agencia Estatal de Investigación (AEI) and Fondo Europeo de Desarrollo Regional (FEDER) for the project MAT2017-87202-P. A.I. was supported by a PROBIST postdoctoral fellowship funded by European Research Council (Marie Skłodowska-Curie Grant No. 754510). C.C.C.S. acknowledges funding through CAPES–PRINT (Programa Institucional de Internacionalização; Grant Nos. 88887.310281/2018-00 and 88887.467442/2019-00) and Mackpesquisa-UPM. L.H. acknowledges funding through the China Scholarship Council. ICN2 is funded by the CERCA Programme/Generalitat de Catalunya and supported by the Severo Ochoa programme (MINECO Grant No. SEV-2017-0706).

For high power and high voltage (HV) applications, low power subsystems must have an auxiliary power supply that can take wide-range high voltage input and can generate low DC voltage at the output. In order to improve the efficiency, silicon carbide (SiC) MOSFET with smaller on resistance are considered to replace silicon (Si) MOSFET, and the static and dynamic characteristics of two devices are compared and analyzed. Besides, the Quasi-Resonant (QR) topology is selected to reduce losses and Electromagnetic Interference (EMI) level. In this paper, a SiC-based QR flyback auxiliary power supply for high voltage applications is proposed, and the design scheme for auxiliary power supply is validated.

Electrospun nanofibrous TiO 2 /g-C 3 N 4 heterojunction photocatalysts with different TiO 2 content have been synthesized via a facile electrospinning and subsequent in situ evaporation and calcination process for the first time, which are examined in terms of morphology, component content, optical properties, PL spectra, photocurrent response, EIS measurement, photocatalytic activity and mechanism. SEM images exhibit TiO 2 /g-C 3 N 4 -4 heterojunction photocatalyst possesses the excellent 1D structure. HRTEM and element mapping images confirm the formation of heterojunction structure. DRS tests identify that TiO 2 /g-C 3 N 4 -4 heterojunction exhibits the intensitive absorption in both UV and visible light region. The photoelectrochemical tests prove that the recombination between electrons and holes are effectively inhibited. Based on TG analysis and photodegradation experiments, TiO 2 /g-C 3 N 4 -4 heterojunction photocatalyst with TiO 2 content of 29.30 wt% possesses the best photocatalytic degradation efficiency for the RhB among the g-C 3 N 4 , TiO 2 and their mixture under simulated sunlight irradiation. Moreover, 1D morphology of TiO 2 /g-C 3 N 4 -4 heterojunction photocatalyst is in favor of separating from solution for reuse and transferring the electrons, and maintains a very high photocatalytic degradation efficiency of 96% even after four recycles experiments, which is beneficial for practical application.

In adaptive optical (AO) systems, deformable mirrors are used to correct wavefront aberrations. In this study, we introduce various structural deformable mirrors used in low temperature environments: discrete actuators deformable mirror, bimorph deformable mirror, membrane deformable mirror and MEMS deformable mirror. And the basic working principle of these deformed mirrors is briefly described; the research results of low temperature deformable mirrors are presented in detail. According to formerly researches, we found out the two main factors influencing the performance of low temperature deformable mirrors. The advantages and disadvantages of various structural low temperature deformable mirrors are analyzed. Finally, the development trend of low temperature deformable mirrors is prospected.

In order to study the mechanism of the Vacuum Cavity explosion venting technology in the gas pipe, An L type simulation model referred to the experimental pipe is established in this paper, in which the Vacuum Cavity explosion venting is simulated by means of Fluent software. The change law of the pressure field, temperature field and velocity vector is obtained in the numerical simulation. After the data analysis, the conclusion is that, the propagation of the shock wave in the pipe accords with the fluid water-hammer phenomenon. The gas components which enter into the Cavity impact and neutralize each other before they vanish eventually and suspend the reaction chain of the combustion. The broken timing of weak panel of the cavity and the change of Cavity volume are the important factors that affect the Vacuum Cavity explosion venting.

For a special functional regression model, i.e., both the dependent and independent variables are functions, we propose the concept of continuous-time perturbation analysis. For three perturbation schemes which correspond to the independent variable, dependent variable and weight function respectively,we obtain the closed form of the diagnosis function based on the functional optimization theory.As an application, we applied this approach to the system of ordinary differential equations (ODEs) and discovered the so-called boundary effect of two-step estimation ofODEs which leaves the possibility for future improvement of two-step estimation.

High-brightness tapered laser diode at 850 nm was fabricated based on the AlGaInAs/A1GaAs chip with graded-index waveguide separate confinement hetero-structure.The tapered laser has better performance than the broad laser under the same condition.The lateral divergence angles of the tapered laser and the broad laser were 4° and 6° at the output power of 1 W,while the beam propagation factor M2 were 2.8 and 9.2,respectively.The slope efficiency of the tapered laser had a high value of 0.58 W/A and the conversion efficiency reached 30% in the output power 1.40 W under the injection current of 3 A.The facts indicated the tape-red laser would be an ideal choice for high brightness high power laser diodes.

There are many factors that affect the groundwater contamination in the highway environment. This paper reports a two-dimensional numerical simulation of the movement of contamination with water into the sub-grade and water table beneath a road to determine the major factors affecting transport of contaminants. The modelling parameters were assembled from various literature sources and eight scenarios were adopted to simulate the possible controlling conditions. Analyses were undertaken to simulate 2–4 years of water percolation through the pavement sub-structure, some contamination arriving at an underlying ground water table and other arriving at a lateral drain. Overall, the potential for ground water table contamination above probable limit values is very low except in extreme permeability and low sorption cases. Results show, firstly, that the sorption capacity of aggregates should be taken into account, especially as the runoff is likely to be a more important consideration than the possibility of l...

In order to predict incremental spacing in press bend forming of Aluminum alloy integral panel,the typical integral panel test piece was taken as an example. By using numerical simulation method,this paper analyzed the effects of different incremental spacing on integral panel forming quality which included stress and strain distribution,curvature continuity,and surface profile. According to simulation results, experimental verification was implemented. The verification results show that the numerical simulation method to predict the incremental spacing is effective.

The capability of an assay to detect Listeria monocytogenes from artificially inoculated fresh-cut produce such as cantaloupe and mixed salad was demonstrated. An oligonucleotide probe that becomes fluorescent upon hybridization to the target DNA (Molecular Beacon, MB) was used in a real-time polymerase chain reaction (PCR) assay. As few as 4 to 7 colony-forming units (CFU) of L. monocytogenes per 25 g of artificially contaminated produce could be detected. A comparison of 2 commercially available kits using MB-PCR (iQ-Check, Bio-Rad Laboratories) and conventional PCR (BAX, Dupont Qualicon) was performed on artificially inoculated produce. The time required to detect L. monocytogenes (from produce to PCR) was considerably shorter for the iQ-Check protocol (approximately 26 h) compared with the BAX-PCR (approximately 52 h). The iQ-Check protocol was also used to confirm the identity of the L. monocytogenes isolates obtained during a microbiological screen of conventional and organic leaf lettuce and alfalfa sprout samples from local supermarkets. The iQ check protocol was successful in differentiating L. monocytogenes isolates from other Listeria spp. such as L. welshimeri, L. innocua, and L. ivanovii. This is the 1st report of the application of the MB probe being used for real-time detection of L. monocytogenes in whole and fresh-cut produce.

Understanding the acid-tolerance ability of enteric human pathogens is critical in determining microbial food safety and the associated risk. We have discovered naturally occurring compounds in the spent growth media, which inhibit the acid-tolerance ability of several enteric human pathogens when challenged at pH 3.0 for 2 h at 37 degrees C. The compounds were detected in the spent growth media obtained from Escherichia coli O157:H7, Salmonella spp., and Vibrio cholera, but not from Shigella flexneri. The compounds were effective in reducing pathogen survival by 5-logs during acid-challenge assay. The low molecular weight (300 Da) and heat resistant nature (121 degrees C, 15 min, at 15 psi) of the compounds make them excellent candidates to explore their suitability as food additives that would increase microbial food safety.

With the development of science technology, the computer networks systems has been widely used in all fields. However, threat to the security of computer networks systems has been a serious problem at present. So, this paper research and study on the computer networks systems from two main parts–main threat to the computer networks systems and computer networks systems security detecting technology.

This paper presented a pipelined 8B10B encoder for a high speed SerDes. To overcome the drawback of the speed limitation due to the conventional architecture, a pipelined encoding architecture is proposed. By splitting the longer path into two shorter paths with registers, the delay of the critical path is shortened greatly. Based on the pipelined architecture, a high-speed 8B10B encoder is implemented using 0.18 µm CMOS technology and standard cell library. Post-simulation results show that the encoder can work up to the rate of 7Gbps with a core are of 76.86 µm × 76.86 µm and the power consumption is 5.0317 mW under a 1.8V power supply voltage.

An oligonucleotide probe that becomes fluorescent upon hybridization to the target DNA (molecular beacon; MB) was evaluated in a real-time polymerase chain reaction (PCR) assay to detect the presence of Salmonella species. As few as 1-4 colony-forming units (CFU) per PCR reaction could be detected. The capability of the assay to detect Salmonella species from artificially inoculated fresh-cut produce such as cantaloupe, mixed-salad, cilantro, and alfalfa sprouts was demonstrated. A comparison of two commercially available kits utilizing MB-PCR (iQ-Check, Bio-Rad Laboratories) and conventional Association of Official Analytical Chemists (AOAC)-approved PCR (BAX, Dupont Qualicon) was performed on artificially inoculated produce. As few as 4 CFU/25 g of produce were detected after 16 h of enrichment in buffered peptone broth. These assays could be carried out entirely in sealed PCR tubes, enabling a rapid and high-throughput detection of Salmonella species in a large number of food and environmental samples. This is the first report of the application of MB probe being used for real-time detection of Salmonella species in whole and fresh-cut fruits and vegetables.

A novel process for the wet cleaning of GaAs surface is presented. It is designed for technological simplicity and minimum damage generated within the GaAs surface. It combines GaAs cleaning with three conditions consisting of (1) removal of thermodynamically unstable species and (2) surface oxide layers must be completely removed after thermal cleaning, and (3) a smooth surface must be provided. Revolving ultrasonic atomization technology is adopted in the cleaning process. At first impurity removal is achieved by organic solvents; second NH4OH:H2O2:H2O = 1:1:10 solution and HCl: H2O2:H2O = 1:1:20 solution in succession to etch a very thin GaAs layer, the goal of the step is removing metallic contaminants and forming a very thin oxidation layer on the GaAs wafer surface; NH4OH:H2O = 1:5 solution is used as the removed oxide layers in the end. The effectiveness of the process is demonstrated by the operation of the GaAs wafer. Characterization of the oxide composition was carried out by X-ray photoelectron spectroscopy. Metal-contamination and surface morphology was observed by a total reflection X-ray fluorescence spectroscopy and atomic force microscope. The research results show that the cleaned surface is without contamination or metal contamination. Also, the GaAs substrates surface is very smooth for epitaxial growth using the rotary ultrasonic atomization technology.

This manuscript aims at raising the attention of the scientific community to the need for better characterised bioreceptors for fast development of point-of-care diagnostic devices able to support mass frequency testing. Particularly, we present the difficulties encountered in finding suitable antibodies for the development of a lateral flow assay for detecting the nucleoprotein of SARS-CoV-2., We acknowledge Consejo Superior de Investigaciones Científicas (CSIC) for the project “COVID19-122” granted in the call “Nuevas ayudas extraordinarias a proyectos de investigación en el marco de las medidas urgentes extraordinarias para hacer frente al impacto económico y social del COVID-19 (Ayudas CSIC-COVID-19)”. We acknowledge also the MICROB-PREDICT project that has received funding from the European Union's Horizon 2020 research and innovation programme under grant agreement No. 825694. Financial support from the EU Graphene Flagship Core 3 Project (No. 881603) is also acknowledged. This article reflects only the authors' view, and the European Commission is not responsible for any use that may be made of the information it contains. ICN2 is funded by the CERCA programme/Generalitat de Catalunya. ICN2 is supported by the Severo Ochoa Centres of Excellence programme, funded by the Spanish Research Agency (AEI, grant no. SEV-2017-0706). E. C. acknowledges Ministerio de Ciencia e Innovación of Spain and Fondo Social Europeo for the Fellowship PRE2018-084856 awarded under the call ‘Ayudas para contratos predoctorales para la formación de doctores, Subprograma Estatal de Formación del Programa Estatal de Promoción del Talento y su Empleabilidad en I+D+i’, under the framework of ‘Plan Estatal de Investigación Científica y Técnica y de Innovación 2017–2020’. L. H. acknowledges the China Scholarship Council. L. H., E. C. and C. F.-C. acknowledge the Autonomous University of Barcelona (UAB) for their support. C. P. (ISGlobal) also acknowledges support from the Spanish Ministry of Science and Innovation and State Research Agency through the “Centro de Excelencia Severo Ochoa 2019–2023” Program (CEX2018-000806-S), and support from the Generalitat de Catalunya through the CERCA Program. A. I. was supported by a PROBIST postdoctoral fellowship funded by the European Research Council (Marie Skłodowska-Curie grant agreement No. 754510).