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We perform a first-principle computation on the magnetic properties of 3d transition metal (TM)-doped silicane. All the substituted systems are energetically stable. Robust half-metallic properties are found in Ti-, V- and Mn-substituted silicane. At the dopant concentration of 12.5%, we evaluate that the Curie temperature of Ti- and Mn-substituted silicane is at 340 and 666 K respectively in the mean-field approximation. Consequently, room-temperature ferromagnetism is easily achievable in Ti- and Mn-substituted silicane. Our work demonstrates potential application of Ti and Mn-substituted silicane for room-temperature spintronic devices.

Carbon quantum dots (CQDs) due to its high fluorescent output is evolving as novel sensing material and is considered as future building blocks for nano sensing devices. Hence, in this investigation we report microwave assisted preparation and multi sensing application of CQDs. The microwave derived CQDs are characterized by Dynamic Light Scattering (DLS) experiment and Fourier Infrared spectra (FTIR) to investigate the size distribution and chemical purity respectively. Fluorescent emission spectra recorded at varying pH shows varying fluorescence emission intensities. Further, emission spectra recorded at different temperatures shows that fluorescence emission of CQDs greatly depends on temperature. Therefore, we demonstrate the pH and temperature sensing characteristics of CQDs by fluorescence quenching behaviour. In addition, the interaction and sensing behaviour of CQDs for dopamine is also presented in this work with a detection limit of 0.2 mM. The steady state and time-resolved methods have been employed in fluorescence quenching methods for sensing dopamine through CQDs at room temperature. The bimolecular quenching rate constants for different concentration have been measured. The interaction between CQDs and dopamine indicates fluorescence quenching method is an elegant process for detecting dopamine through CQDs.

The readout requirements for instruments based on transition-edge sensors (TESs) have dramatically increased over the last decade as demand for systems with larger arrays and faster sensors has grown. Emerging systems are expected to contain many thousands of sensors and/or sensors with time constants as short as 100 ms. These requirements must be satisfied while maintaining low noise, high dynamic range, and low crosstalk. A promising readout candidate for future TES arrays is the microwave SQUID multiplexer, which offers several gigahertz of readout bandwidth per pair of coaxial cables. In microwave SQUID multiplexing, sensor signals are coupled to RF-SQUIDs embedded in superconducting microwave resonators, which are probed via a common microwave feedline and read out using gigahertz signals. This form of SQUID multiplexing moves complexity from the cryogenic stages to room temperature hardware and digital signal processing firmware which must synthesize the microwave tones and process the information contained within them. To demultiplex signals from the microwave SQUID multiplexer, we have implemented an FPGA-based firmware architecture that is flexible enough to read out a variety of differently optimized TESs. A gamma-ray spectrometer targeted at nuclear materials accounting applications, known as SLEDGEHAMMER, is an early adopter of microwave SQUID multiplexing and is driving our current firmware development effort. This instrument utilizes 300 kHz full-width half-maximum resonators with 256 channels in a one gigahertz wide band. We have recently demonstrated undegraded readout of 128 channels using two ROACH2s on a single pair of coaxial cables. This manuscript describes the firmware implementation for the readout electronics of these early array-scale demonstrations.

This study focuses on an experimental investigation of the fluid flow in round bloom continuous casting using a 1:3 model of the industrial casting process. A swirling flow nozzle, represented by the specific design of the RHI Magnesita GYRONOZZLE, is used to produce a swirling motion in the cylindrical mold. The test section is integrated into the Mini-LIMMCAST facility at HZDR, which is operated at room temperature using the ternary alloy GaInSn. Systematic measurements of horizontal and vertical velocity profiles are performed by means of the Ultrasound Doppler Velocimetry. The second part of the study focuses on the interaction between the flow driven by the GYRONOZZLE and concurrent electromagnetic stirring in the mold (M-EMS) by applying rotating magnetic fields (RMFs) at different magnetic flux densities. The effect of the GYRONOZZLE on the flow pattern inside the mold is examined with and without superimposed RMFs and compared to those of a standard single-port nozzle. The measurements reveal that the GYRONOZZLE induces a swirling flow in the whole mold. It is further shown that the influence of a simultaneously applied RMF is mainly restricted to the lower part of the mold since the transport of angular momentum to the top is suppressed by the jets pouring out from the GYRONOZZLE.

Ferrite-polyaniline (PANI) composites were prepared by in situ polymerization of polyaniline with the general formula (1 − x) ferrite + (x) PANI where x = 0, 0.25, 0.5, 0.75, 1. The samples were characterized by XRD, SEM, electrical resistivity, and dielectric measurements. X-ray diffraction reveals single phase formation of CaBaCo2Al0.5Fe11.5O22 Y-type ferrite, whereas polyaniline exhibits an amorphous nature. At room temperature, the resistivity of nano-composites increases with the increase of ferrite filler contents from 3.17 × 104 to 3.19 × 107 Ω cm. Real and imaginary parts of the complex permittivity of the PANI-ferrite composites follow the Maxwell-Wagner model. Based on the Jonscher Law, the AC conductivity of PANI-ferrite composites experiences an increase with the increase in frequency. The exponent calculated from AC conductivity reveals that the hopping is the likely conduction mechanism. The activation energy obtained from temperature-dependent measurements is consistent with room temperature resistivity. Due to the light weight, low cost and flexibility of design, the ferrite-polymer composites are considered useful for microwave devices.

Reduction of a low-grade nickel laterite ore with carbon monoxide to produce Fe-Ni alloy was investigated using a thermo-gravimetric analysis (TGA) method. Non-isothermal reduction tests with a fixed heating rate of 10 °C/min from room temperature to 1200 °C were carried out to determine the different reduction stages and reaction products in each state. Combining measured mass losses with theoretically calculated values together with X-ray diffraction analysis, the products of different reduction stages were identified and a reaction path was established. Isothermal reduction tests with temperatures ranging from 500 °C to 1100 °C were performed to evaluate the temperature dependence of the reduction kinetics. Various kinetic models were fitted to the experimental data to further determine the rate-controlling step in the isothermal tests. Then, two groups of TG experiments were carried out to study the effect of CO flow rate and sample mass on the rate of reaction. The results indicated that the reduction rate increases with the increase of the reduction temperature from 500 °C to 1100 °C. More alloy products are formed and the apparent activation energies increase from 8.6 to 14.7 kJ/mol with the increase of the reduction temperature from 700 °C to 1100 °C. Accordingly, it was proposed that diffusion of CO in the gas bulk and through the pores of the laterite ore sample bed are the rate limiting steps.

Pure and erbium-doped ZnO nanoparticles (Zn1−xErxO), (0.00 ≤ x ≤ 0.10), were synthesized by wet chemical co-precipitation method. The structural, optical, and magnetic properties of the prepared samples were investigated using x-ray powder diffraction (XRD), transmission electron microscopy (TEM), ultraviolet-visible spectroscopy (UV), Fourier transform infrared spectroscopy (FTIR), M-H magnetic hysteresis, and electron paramagnetic resonance (EPR). XRD studies exhibit the presence of a single ZnO wurtzite hexagonal crystal structure for 0.00 ≤ x ≤ 0.06. A secondary phase of Er2O3 appears for x > 0.06. This means that the solubility limit for doping Zn2+ ions by Er3+ ions is about x = 0.06 under our preparations condition. The lattice parameter a is not affected by the Erbium doping. On the other hand, the lattice parameter c and the unit cell volume V increase with the increase of x up to x = 0.06. This is attributed to the larger ionic size of Er3+ ions (0.88 Å) compared to Zn2+ ions (0.74 Å). Both c and V decrease for x > 0.06. TEM micrographs indicate that the shape and the size of the ZnO nanoparticles are modified by changing the doping level of Er. The UV measurements point out that band gap energy Eg decreases with the increase of x up to x = 0.06. Then, it increases for both x = 0.08 and 0.10. FTIR spectra confirm the presence of O–H and Zn–O stretching modes at 3451.963 and 428.901 cm− 1, respectively, in pure and doped ZnO samples. The Zn–O stretching mode shifts toward a lower wavenumber for x = 0.06 and toward a higher wavenumber for x = 0.10. M-H hysteresis analysis, at room temperature, reveals that the pure ZnO has a ferromagnetic signal combined with diamagnetic and paramagnetic contributions. This ferromagnetism is reduced for the doped samples up to x = 0.02, and an antiferromagnetic alignment appears for 0.04 ≤ x ≤ 0.10. The saturation magnetization (Ms), the coercivity (Hc), the retentivity (Mr), the anisotropy constant (Ka), and the magnetic moment (μm) were estimated and discussed in terms of erbium doping for the different samples. EPR spectra for Zn1−xErxO were measured at room temperature in order to study the effect of Er substitution on the g value, resonance field (Hr), peak to peak line width (ΔHpp) and spin–spin relaxation time constant (T2).

A novel polyethylene oxide (PEO)/polylactic acid (PLA) solid polymer electrolyte (SPE) doped with Liquid crystal ionomer (LCI) was prepared by automatic scraping membrane technology and the liquid crystal property of LCI was proposed as an effective strategy to improve the conductivity. The highest conductivity of the SPE with 0.5 wt% LCI achieve a value of 2.19 × 10−4 S/cm at 17 °C which is approximately four orders of magnitude higher than that of the original PEO solid polymer electrolyte, conductivity at room temperature is 10−7–10−8 S/cm. This is because the crystallinity is reduced by 25.3% compared to the pure PEO host. Differential Scanning Calorimetry (DSC) and polarizing microscope (POM) characterize the structure and properties of LCI. Electrochemical Impedance Spectroscopy (EIS) shows that the conductivity of the polymer electrolyte with 0.5 wt% LCI increased abruptly at 35 °C as the temperature is higher than Tg of LCI, reaching 6.37 × 10−4 S/cm which is 191% higher than that at 17 °C. There ionic conductivity has been improved extremely by continuous channel for efficient ion transportation, especially at the microtherm. And this change is greater at the elevated temperature regions, in line with the VTF equation. In summary, LCI’s liquid crystal performance can be used as an effective strategy to improve the low temperature conductivity of SPE.

Single-mode lasing at room temperature in quantum-cascade lasers (QCLs) with arched cavity design has been demonstrated. The output optical power in single-mode lasing regime at ~7.7-μm lasing wavelength was above 6 mW with a side-mode suppression ratio of up to 25 dB. The QCL heterostructure for the arched cavities was grown by molecular-beam epitaxy (MBE) based on a heterojunction of In 0.53 Ga 0.47 As/Al 0.48 In 0.52 As solid alloys, lattice-matched with InP substrate, and InP layers performing the function of waveguide claddings.

Molecular beam epitaxy techniques were used to grow a quantum-cascade laser (QCL) heterostructure based on an In 0.53 Ga 0.47 As/Al 0.48 In 0.52 As heteropair lattice-matched with an InP substrate. InP layers were used to form an optical waveguide. The obtained QCL heterostructure ensured room-temperature lasing in the 8-μm wavelength range at a maximum output optical power of 0.45 W from one facet in a standard ridge geometry of the Fabry–Pérot cavities formed by cleaved facets.