Applying the selective Cu electroplating technique to light-emitting diodes

[[abstract]]We successfully fabricated a predefined patterned copper (Cu) substrate for thin GaN light-emitting diodes without barriers by the selective electroplating technique. The contours of Cu bumps fabricated using different electroplating modes and parameters were measured. We observed that the average thickness diminished with increasing current density. The current density conditions to obtain the best upright structure in the process were 40 and 80 mA/cm2.[[notice]]補正完畢[[incitationindex]]SCI[[booktype]]紙本[[booktype]]電子

Worksite health screening programs for predicting the development of Metabolic Syndrome in middle-aged employees: a five-year follow-up study

<p>Abstract</p> <p>Background</p> <p>Metabolic syndrome (MetS) management programs conventionally focus on the adults having MetS. However, risk assessment for MetS development is also important for many adults potentially at risk but do not yet fulfill MetS criteria at screening. Therefore, we conducted this follow-up study to explore whether initial screening records can be efficiently applied on the prediction of the MetS occurrence in healthy middle-aged employees.</p> <p>Methods</p> <p>Utilizing health examination data, a five-year follow-up observational study was conducted for 1384 middle-aged Taiwanese employees not fulfilling MetS criteria. Data analyzed included: gender, age, MetS components, uric acid, insulin, liver enzymes, sonographic fatty liver, hepatovirus infections and lifestyle factors. Multivariate logistic regression was used to estimate the adjusted odds ratios (OR) and 95% confidence interval (CI) of risk for MetS development. The synergistic index (SI) values and their confidence intervals of risk factor combinations were calculated; and were used to estimate the interacting effects of coupling MetS components on MetS development.</p> <p>Results</p> <p>Within five years, 13% (175 out of 1384) participants fulfilled MetS criteria. The ORs for MetS development among adults initially having one or two MetS components were 2.8 and 7.3, respectively (both p < 0.01), versus the adults having zero MetS component count at screening. Central obesity carried an OR of 7.5 (p < 0.01), which far exceeded other risk factors (all ORs < 2.7). Synergistic effects on MetS development existed between coupling MetS components: 1. High blood pressure plus low-HDL demonstrated an OR of 11.7 (p < 0.01) for MetS development and an SI of 4.7 (95% CI, 2.1-10.9). 2. High blood pressure plus hyperglycemia had an OR of 7.9 (p < 0.01), and an SI of 2.7 (95% CI, 1.2-6.4).</p> <p>Conclusion</p> <p>MetS component count and combination can be used in predicting MetS development for participants potentially at risk. Worksite MetS screening programs simultaneously allow for finding out cases and for assessing risk of MetS development.</p

Graphene and molybdenum disulfide hybrids: Synthesis and applications

Graphene and related inorganic two-dimensional (2D) nanomaterials are an exceptional class of compounds with exotic properties that are technologically intriguing. While graphene itself is chemically inert and a gapless semimetal, its isostructural analog, molybdenum disulfide (MOS2) is chemically versatile with band gaps, thereby finding significant use in a myriad of applications. Although these 2D nanomaterials individually possess tremendous authority for various applications, the combination of these materials in the recent past has created a new paradigm in emerging applications. Here, we summarize the current state-of-the-art and progress over the past three years on the development of hybrids of these layered materials. We highlight their pivotal role in electrochemical energy storage, sensing, hydrogen generation by photochemical water splitting and electronic device applications such as field-effect transistors. Perspectives on the challenges and opportunities for the exploration of these 2D layered hybrid materials are put forwardopen1

Identification and reconstruction of low-energy electrons in the ProtoDUNE-SP detector

Measurements of electrons from $\nu_e$ interactions are crucial for the Deep Underground Neutrino Experiment (DUNE) neutrino oscillation program, as well as searches for physics beyond the standard model, supernova neutrino detection, and solar neutrino measurements. This article describes the selection and reconstruction of low-energy (Michel) electrons in the ProtoDUNE-SP detector. ProtoDUNE-SP is one of the prototypes for the DUNE far detector, built and operated at CERN as a charged particle test beam experiment. A sample of low-energy electrons produced by the decay of cosmic muons is selected with a purity of 95%. This sample is used to calibrate the low-energy electron energy scale with two techniques. An electron energy calibration based on a cosmic ray muon sample uses calibration constants derived from measured and simulated cosmic ray muon events. Another calibration technique makes use of the theoretically well-understood Michel electron energy spectrum to convert reconstructed charge to electron energy. In addition, the effects of detector response to low-energy electron energy scale and its resolution including readout electronics threshold effects are quantified. Finally, the relation between the theoretical and reconstructed low-energy electron energy spectrum is derived and the energy resolution is characterized. The low-energy electron selection presented here accounts for about 75% of the total electron deposited energy. After the addition of lost energy using a Monte Carlo simulation, the energy resolution improves from about 40% to 25% at 50~MeV. These results are used to validate the expected capabilities of the DUNE far detector to reconstruct low-energy electrons.Comment: 19 pages, 10 figure

Impact of cross-section uncertainties on supernova neutrino spectral parameter fitting in the Deep Underground Neutrino Experiment

A primary goal of the upcoming Deep Underground Neutrino Experiment (DUNE) is to measure the $\mathcal{O}(10)$ MeV neutrinos produced by a Galactic core-collapse supernova if one should occur during the lifetime of the experiment. The liquid-argon-based detectors planned for DUNE are expected to be uniquely sensitive to the $\nu_e$ component of the supernova flux, enabling a wide variety of physics and astrophysics measurements. A key requirement for a correct interpretation of these measurements is a good understanding of the energy-dependent total cross section $\sigma(E_\nu)$ for charged-current $\nu_e$ absorption on argon. In the context of a simulated extraction of supernova $\nu_e$ spectral parameters from a toy analysis, we investigate the impact of $\sigma(E_\nu)$ modeling uncertainties on DUNE's supernova neutrino physics sensitivity for the first time. We find that the currently large theoretical uncertainties on $\sigma(E_\nu)$ must be substantially reduced before the $\nu_e$ flux parameters can be extracted reliably: in the absence of external constraints, a measurement of the integrated neutrino luminosity with less than 10\% bias with DUNE requires $\sigma(E_\nu)$ to be known to about 5%. The neutrino spectral shape parameters can be known to better than 10% for a 20% uncertainty on the cross-section scale, although they will be sensitive to uncertainties on the shape of $\sigma(E_\nu)$. A direct measurement of low-energy $\nu_e$-argon scattering would be invaluable for improving the theoretical precision to the needed level.Comment: 25 pages, 21 figure

Highly-parallelized simulation of a pixelated LArTPC on a GPU

The rapid development of general-purpose computing on graphics processing units (GPGPU) is allowing the implementation of highly-parallelized Monte Carlo simulation chains for particle physics experiments. This technique is particularly suitable for the simulation of a pixelated charge readout for time projection chambers, given the large number of channels that this technology employs. Here we present the first implementation of a full microphysical simulator of a liquid argon time projection chamber (LArTPC) equipped with light readout and pixelated charge readout, developed for the DUNE Near Detector. The software is implemented with an end-to-end set of GPU-optimized algorithms. The algorithms have been written in Python and translated into CUDA kernels using Numba, a just-in-time compiler for a subset of Python and NumPy instructions. The GPU implementation achieves a speed up of four orders of magnitude compared with the equivalent CPU version. The simulation of the current induced on 10^3 pixels takes around 1 ms on the GPU, compared with approximately 10 s on the CPU. The results of the simulation are compared against data from a pixel-readout LArTPC prototype

Synthesis of Core-shell Nano-particulate Polyelectrolyte

[[abstract]]The nano-particle consists two principal constituent monomers, of which one is electrolyte with sulfonic acid group: 2-Acrylamido-2-methyl-1-propane sulfonic acid (AMPS), and the other is multi-vinyl: 1,1,1-Trimethylolpropane triacrylate (TMPTA). Synthesis was found to be composed of two stages. The early precipitation polymerization leads to the formation of nuclei, which grow gradually to particulate core of size about 10 to 20 nm at least. Subsequent emulsion-assisted polymerization permits the formation of electrolytic shell part over the core. The reaction control was facilitated through the photo-initiation mechanism at ambient temperature. The particle composition was revealed by FTIR, and the characterization of particle size was effectuated by both DLS and FESEM. IR spectrum as shown below confirms that TMTPA (n ̅ = 1732 cm-1, ester C=O) and AMPS (n ̅ = 1040 cm-1, symmetric stretching sulfonic SO3 hydrated) both constitute significantly the particle. The particle size was measured to be about 20~30 nm by FESEM as indicated in the micrograph below, whereas, about 60~70 nm by DLS. This large difference, between dry vacuum state and aqueous solution state, reveals the fact that the hydrodynamic volume of particle may represent the tremendous swelling of polyelectrolyte shell part in aqueous solution. The quantitative composition of particle will be pursued by elemental analysis, EDS, XPS. And the morphologic core-shell structure will be characterized by TEM and SAXS.[[sponsorship]]Elsvier[[conferencetype]]國際[[conferencedate]]20150520~20150522[[booktype]]紙本[[iscallforpapers]]Y[[conferencelocation]]Riva del Garda (on Lake Garda), Ital

Network Nano-Porous Poly(vinylidene fluoride-co-hexafluoropropene) Membranes by Nano-Gelation Assisted phase Separation of Poly(vinylidene fluoride-co-hexafluoropropene)/Poly(methyl methacrylate) Blend Precursor in Toluene

[[abstract]]Network nanoporous poly(vinylidene fluoride-co-hexafluoropropene (PVDF–HFP) membrane formation mechanism via poly(methyl methacrylate) (PMMA) leaching from PVDF–HFP/PMMA blend film was studied. The blends of PVDF–HFP with PMMA comprise miscible amorphous phase much larger in quantity than those of poly(vinylidene fluoride) (PVDF) with PMMA. The residual PVDF–HFP crystalline phase which may present in very small fraction was characterized by SAXS, which permitted estimation of the critical composition of phase boundary of blend. The FESEM micrograph revealed the network morphology of the membranes being composed of interconnected tiny sheaves of recrystallized PVDF–HFP. Nanogelation mechanism is proposed to describe the crystallization of disentangled PVDF–HFP chain segments under spatial confinement during PMMA leaching from amorphous solution phase in blend film. The crystallinities of membranes determined by DSC are found to be consistent with the theoretically calculated values. Present research suggested a novel approach for the formation of network nanoporous membranes from semicrystalline polymers.[[incitationindex]]SCI[[booktype]]紙本[[booktype]]電子

Strong effect of precursor preparation on the morphology of semicrystalline phase inversion poly(vinylidene fluoride) membranes

[[abstract]]This work documents the role of precursor preparation as an overlooked important factor in the control of membrane structures obtained by the phase inversion (PI) of solutions of crystallizable polymers. The effect of precursor-solution preparation temperature on the structure of a phase inversion poly(vinylidene fluoride) (PVDF) membrane is examined. The phase inversion example explored is the coagulation of a PVDF solution in dimethyl formamide (DMF) by the action of 1-octanol, which is a soft non-solvent. Polymer dissolution temperature is varied from 50 to 110 °C and the immediate consequence is a substantial variation in the density of nuclei available for the initiation of crystallization. Membrane structure is defined through a competition between solid–liquid (s–l) and liquid–liquid (l–l) equilibria; such competition can be strongly affected by changes in the density of crystallization nuclei. As a result, it is found possible to generate a wide spectrum of membrane morphologies without resorting to a variation of any of the standard parameters, such as dope and coagulant compositions and temperatures, usually employed for the control of phase inversion membrane morphology. It is also found that aging time can be used as a further structure-control parameter and a ‘maturation time–dissolution temperature’ equivalence is demonstrated.[[journaltype]]國外[[incitationindex]]SCI[[incitationindex]]EI[[booktype]]紙本[[countrycodes]]NL