Wide Band Research Articles

Broadband Millimeter-Wave Front-End Module Design Considerations in FD-SOI CMOS vs. GaN HEMTs

Millimeter-wave (mm-Wave) phased array systems need to meet the transmitter (Tx) equivalent isotropic radiated power (EIRP) requirement, and that depends mainly on the design of two key sub-components: (1) the antenna array and (2) the Tx power amplifier (PA) in the front-end-modules (FEMs). Simulations using an electromagnetic (EM) solver carried out in Cadence AWR with AXIEM suggest that for two uniform square patch antenna arrays at 24 GHz, the 4 element array has ~6 dB lower antenna gain and twice the half power beam width (HPBW) compared to the 16 element array. We also present measurements and post-layout parasitic-extracted (PEX) EM simulation data taken on two broadband mm-Wave PAs designed in our lab that cover the key portions of the fifth-generation (5G) FR2-band (i.e., 24.25–52.6 GHz) that lies between the super-high-frequency (SHF, i.e., 3–30 GHz) band and the extremely-high-frequency (EHF, i.e., 30–300 GHz) band: one designed in a 22 nm fully depleted silicon on insulator (FD-SOI) CMOS process, and the other in an advanced 40 nm Gallium Nitride (GaN) high-electron-mobility transistor (HEMT) process. The FD-SOI PA achieves saturated output power (POUT,SAT) of ~14 dBm and peak power-added efficiency (PAE) of ~20% with ~14 dB of gain and 3 dB bandwidth (BW) from ~19.1 to 46.5 GHz in measurement, while the GaN PA achieves measured POUT,SAT of ~24 dBm and peak PAE of ~20% with ~20 dB gain and 3 dB BW from ~19.9 to 35.2 GHz. The PAs’ measured data are in good agreement with the PEX EM simulated data, and 3rd Watt-level GaN PA design data are also presented, but with simulated PEX EM data only. Assuming each antenna element will be driven by one FEM and each phased array targets the same 65 dBm EIRP, millimeter wave (mm-Wave) antenna arrays using the Watt-level GaN PAs and FEMs are expected to achieve roughly 2× wider HPBW with 4× reduction in the array size compared with the arrays using Si FEMs, which shall alleviate the thorny mm-Wave line-of-sight (LOS)-blocking problems significantly.

Optical Centers in Cr-, Mn-, and O-Doped AlN and Their Thermodynamic Stability Designed by a Multiscale Computational Approach.

The optical centers in AlN can frequently exist in various charge states and can be accompanied by many coexisting defect species, creating a complex environment where mutual interactions are inevitable. Therefore, it is an immediate quest to design AlN crystal growth protocols that can target a specific optical center of interest and tune its concentration while preventing the formation of other unwanted point defects. Here, we provide a powerful workflow for point defect engineering in wide band gap, binary semiconductors that can be readily used to design optimal crystal growth protocols through combining CALPHAD-based phase analysis, and ab initio defect calculations. We investigate technologically relevant chromium- and manganese-induced optical centers in AlN, followed by studying the impact of oxygen that can be unintentionally incorporated during crystal growth. We present the dominant defects in all three cases as a function of process parameters along with the optical signatures. In the case of both Cr and Mn doping, the CrAl and MnAl defects are most likely, and increasing nitrogen partial pressure tends to enhance their concentration. We show that it is possible to use nitrogen fugacity as a tool for tuning the intensity of optical signatures. We calculate the CrAl charge transition levels with respect to the valence-band maximum at 2.60 eV (E+/-), 3.83 eV (E0/-), and 5.41 eV (E-/2-) and electron and hole capture transitions with luminescence bands centered at 2.82, 1.91, and 3.15 eV. Unlike the Cr doping, Mn aggregation is unlikely, and the MnAl-VN is the most abundant defect after MnAl under most synthesis conditions. Oxygen tends to form complexes with VAl, and ON-VAl is a prominent defect following ON, with near-UV emission bands at 3.17, 3.26, and 3.81 eV. Our results agree with the available experimental optical signatures of Cr-, Mn-, and O-related centers and provide pathways on how to tune the luminous intensity of these centers through changes in growth conditions.

Computational investigation of the phase stability, electronic, optical, phonon spectrum, and elastic behavior of layered perovskites Ca2XO4 (X = Zr, Hf) for optoelectronic applications.

A significant class of solid-state materials, Ruddlesden-Popper (RP) perovskites are well-known for their rich chemical compositions that make them excellent electrocatalysts. Therefore, in this work, we conduct thorough analysis of RP perovskites, specifically Ca2XO4 (X = Zr, Hf). We delve into the structural, electronic, optical, and mechanical properties presenting their insights for the first time. Our investigations reveal that Ca2XO4 (X = Zr, Hf) exhibits stable tetragonal phase structures, with energies (E0) of - 10,522.93eV and - 33,520.14eV, respectively. The calculated in terms of the ground state determines to possess distinct values such as - 4.79 eV/atom for LiScTe2 and - 3.95 eV/atom for Ca2ZrO4 and Ca2HfO4. Notably, the semiconductor characteristics of Ca2ZrO4 and Ca2HfO4 are underscored by their respective wide direct band gap of 5.02eV and 5.30eV. Then, we discuss the optical parameters encompassing the dielectric function, absorption coefficient, optical conductivity, refractive index, and energy loss function. is described as ductile, whereas is defined as brittle. Our outcomes underscore remarkable ability of these materials to absorb ultraviolet radiation from the electromagnetic spectrum, positioning them as promising candidates for optoelectronic applications. We made these calculations by employing first-principles approach rooted in density functional theory (DFT) and utilizing the Perdew-Burke-Ernzerhof-Generalized Gradient Approximation (PBE-GGA) and Tran and Blaha-modified Becke-Johnson (TB-mBJ) functional within the WEIN2K framework. In this framework, Kramers-Kronig relations are used to obtain crucial optical parameters. Mechanical behavior is assessed by employing Voigt-Reuss-Hill approximation (VRH) fulfilling the Born's criteria which emphasizes that these materials are equally appropriate for a broad range of mechanical applications.

Plasma etching of silicon carbide trenches with high aspect ratio and rounded corners

Silicon carbide (SiC) is a representative third-generation semiconductor known for its superior properties, including a wide band gap, high electron saturation velocity, high thermal conductivity, and high physical/chemical stability, making it highly promising for high-power electronic devices. In SiC power devices, superjunction architecture can reduce specific on-resistance without compromising breakdown voltage, while trench-gate structures provide better control over channel conductivity. In this work, we demonstrate high aspect ratio (>5:1) SiC trenches for superjunction devices and corner-rounded SiC trenches for gate trench power devices through plasma etching. The high aspect ratio trenches were achieved by optimizing the gas ratio in the etching process, and the corner-rounded trenches were directly formed by introducing nitrogen dilution during plasma etching. These results are significant for enhancing the performance of SiC trench-based power devices.

Dual- and triple-band quasi-elliptic bandpass filters based on single-cavity multi-mode hybrid cavities

In this paper, a novel construction method for a single hybrid cavity is proposed for the first time, which integrates a quarter-mode substrate integrated waveguide structure into a patch cavity (QMSIWP), and a novel single-cavity multi-mode resonator is realized through the incorporation of cross-slot lines. A detailed analysis of its characteristics, combined with a specialized feed structure, leads to the design of multiple dual-band quasi-elliptic bandpass filters (BPFs) with varying frequency ratios and a triple-band quasi-elliptic BPF. The finite frequency transmission zeros (FTZs) and bandwidths (BWs) can be controlled by adjusting various parameters. For the demonstration, a triple-band quasi-elliptic BPF is fabricated and measured to validate the performance and design method of the proposed QMSIWP hybrid cavity and feed structure. The measured results agree with the synthesized and simulated results, confirming the proposed method's feasibility and universality. The proposed filter exhibits advantages such as compact size, high selectivity, and excellent group delay, which expands its application prospects and potential value.

Two types of stimulated emission in HPHT diamond with a high concentration of NV centers

The paper presents the results of experimental observation of two types of stimulated emission (SE) under pulsed laser pumping at 532 nm in diamond with NV centers. A comprehensive spectroscopic characterization of multisectorial HPHT diamond plate was performed. At low pumping power, the stimulated emission from NV¯ centers was recorded as a broad (≥80 nm wide) band with a maximum at 706 nm in the {111} and {311} sectors of the diamond plate. As the pump power increased in the {111} sector, narrow-band stimulated emission (<10 nm wide) was detected, with a maximum at 716 nm and a luminescence impulse duration of 1.5–3 ns. As the pump density increased, a fine structure in the spectrum of narrow-band stimulated emission was revealed for the first time. The concentration of NV¯ centers in the {111} and {311} growth sectors was ≈10 ppm. However, there were considerable differences in the concentrations of C (35 and 3.5 ppm) and C+ centers (6.1 and 3.2 ppm, respectively). It was demonstrated that the presence of a high concentration of NV¯ centers is not the only necessary condition for the initiation of narrow-band SE in the 710–720 nm range. In the {311} sector, lighting at 360, 405, and 488 nm reduced the concentration of NV¯ centers by 15 % while increasing the concentration of C+ centers in the {311} sector. This effect is weak in the {111} sector. The authors suggested a model for narrow-band SE at the transition Valence Band → C+ with charge-state conversion of C↔C+ and NV0↔NV¯ centers. Further research on the dynamic processes is required in order to a detailed understanding of the operation of NV centers in diamond during SE generation.

Synergistic effects of gadolinium oxide into the matrix of zeolitic imidazolate frameworks (ZIFs) for supercapacitor applications

In this study, we synthesized ZIF-8, ZIF-67, Gd₀.₀₁/ZIF-8, & Gd₀.₀₁/ZIF-67 electrodes using the direct combination technique. Both electrodes are being used for energy storage devices. We extensively evaluated these nanocomposites using a variety of electrochemical methods, including retention analysis, galvanostatic charge-discharge (GCD), cyclic voltammetry (CV), and electrochemical impedance spectroscopy (EIS). ZIF-8 exhibits a wide band gap of approximately 2.58 eV, suggesting its main absorption is of UV light. The peaks in the absorbance spectrum vary slightly in wavelength due to the presence of different metal centers. Peaks between 1400-1600 cm⁻1 indicate C–N stretching vibrations from the imidazolate linkers. Peaks between 1600-1700 cm⁻1 are associated with C=C stretching vibrations. ZIF-8 exhibits well-defined peaks in its XRD pattern, indicating a high level of crystallinity. Peaks can be observed at specific 2θ values, typically at 22.09°, 26.62°, 38.49°, and 47.27°, which correspond to the (110), (200), (211), and (220) planes. The calculated specific capacitances for ZIF-8 and ZIF-67 are 223.95 and 255.20 F/g. For Gd0.01/ZIF-8, & Gd0.01/ZIF-67 specific capacitances are 575.00 and 587.50 F/g. The ZIF-8, ZIF-67, Gd0.01/ZIF-8, & Gd0.01/ZIF-67 electrodes exhibited specific capacitances of (78.30, 192.59, 342.57, and 1164) F/g at current densities of 1 A/g from the GCD calculation. The retention plot of ZIF-8, ZIF-67, Gd0.01/ZIF-8, & Gd0.01/ZIF-67 electrode shows efficiency of 71%, 71%, 105% and 75%, respectively, indicating their suitability for supercapacitor applications.

Hollow and heterojunction-structured Janus nanomotors for pyroelectrodynamic and nanozyme-catalyzed tumor therapy

Pyroelectrodynamic therapy (PEDT) has emerged as an attractive therapeutic modality for tumors, but is dramatically discounted by inherent defects of wide band gap, fast electron − hole recombination and low photothermal utilization. Herein, hollow-structured Janus nanoparticles (NPs) are developed to improve tumor accumulation and PEDT generation of reactive oxidative species (ROS) for antitumor treatment. Hollow barium titanate (hBT) NPs were prepared by the template and hydrothermal method for in situ deposition of CuS nanodots and then partially coated with polydopamine (PDA) caps to obtain hBT-CuS@PDA. Finite element analysis reveals that the unique thin shell of hBT benefits transportation of pyroelectrically generated charge carriers through shortening diffusion distance to the interface. The CuS deposition forms heterojunctions with hBT to accelerate electron − hole separation and leads to a larger pyroelectric current. The hollow structure facilitates light absorption and conversion, and the photothermal effect of the half-coated PDA caps generates asymmetric temperature gradient to drive NP locomotion across biological barriers. The in situ generated pyroelectric field selectively affects membrane potential and fluidity of tumor cells to enhance the specific NP internalization. The pyroelectric effect enhances the peroxidase-like activity of CuS nanodots to generate toxic ·OH and the glutathione peroxidase-like activity to inhibit glutathione consumption of ROS. The integration of photothermal, pyroelectric, nanozyme catalysis and self-protrusion effects promotes NP accumulation and penetration throughout tumors to exhibit therapeutic effect at a mild-temperature, reducing the possible high-temperature ablation of normal tissues. The hollow and heterjunction structure generates abundant intracellular ROS and efficient diffusion in tumor tissues to inhibit tumor growth and extend animal survival, offering a safe and effective PEDT strategy.

Exploring wide gap semiconductor characteristics in -pinene crystals: insights from density functional theory.

-Pinene, a bicyclic monoterpene found extensively in the essential oils of conifers, has shown potential in pharmacological applications. This study theoretically investigates the structural and electronic properties of the (1S)- - -pinene crystal, focusing on its potential for nanoelectronic applications due to the observed wide band gap. Structural analysis revealed that the crystal's unit cell contains 104 atoms with orthorhombic symmetry, and its lattice parameters show excellent agreement with experimental data. Electronic analysis indicated an indirect band gap of 3.58 eV for LDA-PZ and 4.32 eV for GGA-PBE, suggesting that (1S)- - -pinene behaves as a wide band-gap semiconductor. The electronic structure is primarily influenced by contributions from the orbitals of Carbon atoms and the s orbital of Hydrogen atoms, highlighting potential sites for chemical interaction. DFT calculations were performed using the Quantum Espresso software. They employed both the local density approximation (LDA-PZ) and the generalized gradient approximation (GGA-PBE), parameterized by the Perdew-Burke-Ernzerhof exchange-correlation functional. Norm-conserving pseudopotentials were applied to represent the core electrons accurately.

Design of Circularly Polarized Koch Snowflake Fractal Antenna With Schottky Band Diode Rectifiers for RF Energy Harvesting Applications

ABSTRACTRadio frequency (RF) energy harvesting has recently become an effective way of powering wireless devices, reducing the requirement of batteries along with their related storage as well as lifespan restrictions. One of the main obstacles to RF energy harvesting is the limited quantity of energy that can be obtained from wireless sources due to weak signal strength, low efficiency, and poor gain. To address these shortcomings, the proposed method is designed based on the circularly polarized Koch snowflake fractal antenna with the Jerusalem cross (JC)–based frequency‐selective surface (FSS) and Schottky diode–based rectifiers for RF energy harvesting applications at the resonance frequency of 5.8 GHz. The electromagnetic energy from the environment can effectively captured using a proposed wide band and high gain antenna designed using a Koch snowflake array based on FSSs. Flame Retardant‐4 (FR‐4) material has good dielectric qualities for electronics, and it is employed as the dielectric substrate in this model; copper serves as the ground plane. The squid game optimizer (SGO) determines the ideal outer snowflake dimensions by maximizing the resonance frequency in order to achieve high gain. The optimally selected outer snowflake length and width are 40 and 23.09 mm. The designed antenna model uses a rectifier based on Schottky diodes for RF energy harvesting applications, which involves converting electromagnetic waves into direct current. The fractal antenna model and RF energy harvesting are designed and simulated using the ANSYS HFSS and Matlab RF toolbox. The model is used to evaluate the antenna's performance by concentrating on gain radiation patterns, S11, and voltage standing wave ratio (VSWR). The Koch snowflake fractal antenna, which uses a JC–based FSS, has been measured for performance at 5.8‐GHz frequency; the values obtained for impedance bandwidth, gain, S11, and VSWR are 7.61%, 9.962 dB, −33 dB, and 1.01, respectively. The analysis of the experimental data demonstrates that the Koch snowflake fractal antenna, which is being proposed for energy harvesting applications, outperforms several other existing designs in terms of effectiveness.

Bilayer Boost to UV Assisted Supercapacitors: Enhanced Performance with Transparent TiO2/MoO3 Heterojunction Electrode

AbstractPhoto‐assisted supercapacitor is a promising smart device component for achieving both energy conversion and storage. The photo‐assisted functionality in a supercapacitor is realized through the choice of photo responsive electrode material under suitable illumination conditions. The well‐known electrochemically active electrode materials are wide band gap semiconductors which absorb strongly in UV light. However, most of the prior studies on photo‐assisted supercapacitors used visible light. Herein, we present a transparent TiO2/MoO3 bi‐layer heterojunction made by simple solution process as an efficient electrode for photo‐assisted supercapacitors under UV light illumination. The electrochemical performance of the electrode is significantly enhanced even with a less intense (0.05 mW/cm2) UV light, compared to dark as well as the single layer electrode under same illumination condition. The highest areal capacitance of 63.25 mF/cm2 at 0.1 mA/cm2 is achieved, that surpasses most of the recent relevant reports. The synergetic effect of UV illumination and the built‐in potential at the type II heterojunction interface encourages ion insertion and better collection of the photo‐generated carriers. The unique bi‐layer design also leads to better rate capability features. Thus, the work presents a new prospect for the development of transparent energy storage devices to be used in future smart technologies.

Low SAR ultra compact UWB vivaldi non-uniform slot antennas for breast cancer detection

Abstract Breast cancer is one of the growing issues among women. Current ultrawideband (UWB) antennas utilized for Microwave Imaging (MI) present several limitations, such as resolution and penetration trade-offs, large dimensions of the antennas degrade patient comfort, and clutter in the received signal. To tackle these restrictions, this study presents the design, fabrication, and testing of ultra-compact Vivaldi antennas based on the new Vivaldi non-uniform slot profile antenna (VNSPA) theory. These antennas, with their significant slot length reductions of 50 % and 60 %, and circuit area reductions of 72.74 % (Antenna A) and 81.8 % (Antenna B), hold great promise for modern wireless communication and medical fields. Antenna A and B provide matching S11 values of less than −11.36 dB and −10.21 dB and peak gains of 5.9 dBi and 6 dBi through 2.63–12.33 GHz and 3.16–14.34 GHz, respectively. Although Antenna B is 30.58 % smaller than Antenna A, it provides 13.24 % bandwidth (BW) with a 1.7 % gain enhancement, highlighting the significance of the exponential nonuniform slot profile (ENSP) shape on the antenna’s performance. Antenna B provides good Breast Cancer Detection (BCD) results through UWB MI. The simulation in this work, which is performed using computer simulation technology (CST) software, agrees well with the practical results to prove the antenna’s capabilities in detecting tumors in a breast. These results, like the directive stable radiation patterns and low specific absorption rate (SAR) values, ensure the proposed antennas are good candidates for modern wireless communication applications such as reader antennas in body area networks and high-resolution medical applications such as BCD.

Ultrahigh-resolution broadband spectrometer based on grating-beamsplitter interferometer

An ultrahigh-resolution broadband spectrometer based on a grating-beamsplitter interferometer is presented, in which a transmission grating serves not only as a beamsplitter for the interferometer but also as a dispersive element to divide a wide spectral band into multiple narrow spectral bands. The distinctive design reduces the number of optical components of the instrument and simplifies the structure of the instrument. For one scan period, this spectrometer generates multiple interferograms simultaneously, each interferogram covering a separate wavelength range is received by a separate pixel of the linear detector, and the sum of the spectra recovered from all interferograms constitutes a continuous broadband spectrum. The relevant formulas and preliminary design calculation are provided. The simulation is shown by two examples within the spectral range from 300 nm to 500 nm and 900 nm to 1600 nm. This spectrometer will be suitable for ultrahigh-resolution broadband spectral measurements.

Ligand-Directed Valence Band Engineering in Pb2+ Hybrid Crystals: Achieving Dispersive Bands and Shallow Valence Band Maximum.

While crystalline hybrid solids hold great potential as novel semiconductors, most semiconductive hybrids utilize transition metal ions, which inherently limit carrier mobility due to the small band dispersion derived from the d orbitals. The filled s orbitals of post-transition metal ions offer the potential to design dispersed valence bands, but a method to translate the local structure design of these metal ions to valence band engineering is still in development. This study focuses on Pb2+-containing hybrid crystals, developing a simple strategy to control the Pb2+ coordination geometry through the molecular design of azole ligands. By preprogramming the coordination number of Pb2+ with azolate ligands, we succeeded in obtaining an isotropic coordination environment at a higher coordination number, resulting in a dispersed valence band and shallow valence band maximum while having a wide band gap. Detailed analysis of the band structures reveals that the energy levels and symmetry of the molecular orbitals of the anions play important roles in realizing these antinomic properties. This ligand-directed approach achieves both isotropy and covalency in the coordination bond by exploiting the diversity of the molecular orbitals. Our findings provide a foundation for future design strategies to optimize electronic structures in hybrid materials, advancing their application in semiconductive devices.

Tuning the bandgap and photoluminescence properties of Ge/Al2O3 multilayer thin films using annealing and ion beam irradiation

Abstract The present work reports high energy ion beam irradiation induced modifications in Ge/Al2O3 multilayers (MLs). Ge and Al2O3 multilayer thin films were deposited using the electron beam evaporation technique. Afterward, the as-deposited films were annealed using Rapid thermal annealing (RTA) at different temperatures ranging from 500 to 800°C under high vacuum. At a constant fluence of 5×1012 ions /cm2, the annealed films were subjected to irradiation with 80 MeV Ag ions. X-ray diffraction patterns show the crystalline nature of films that were annealed above 500°C, and the increase in crystallite size of Ge nanocrystals from 4.5 to 5.7 nm is observed for annealed samples. After Ag ion irradiation, the crystallinity of the films deteriorates. The crystallinity and optical bandgap are found to vary with Ag ion irradiation. The band gap of annealed films decreased from 1.1 to 0.97 eV with increase in crystallite size. The band gap of irradiated samples increased than that of pristine films. In addition, photoluminescence (PL) measurements were carried out to investigate the luminescence characteristics of annealed and irradiated multilayer films, and a wide emission band in the visible region was observed. The basic mechanism for tailoring the optical band gap and PL emission using RTA and ion irradiation is discussed.&amp;#xD;&amp;#xD;

INFRARED FOURIER SPECTROSCOPY OF DIFFUSE REFLECTION OF THE AZ nLOF SERIES NEGATIVE PHOTORESISTS FILMS ON MONOCRYSTALLINE SILICON

Films of the AZ nLOF 2020, AZ nLOF 2070 and AZ nLOF 5510 negative photoresists (PR) with a thickness of 0,95 – 6,1 μm, deposited on the surface of silicon wafers by the centrifugation method, were studied by the method of IR-Fourier diffuse reflection spectroscopy. In the diffuse reflectance spectra of PR/silicon structures, absorption bands were observed against the background of interference fringes. It allows the technique to be used to measure film thickness or its refractive index. The most intense bands in the AZ nLOF series PR spectra are the bands of stretching vibrations of the aromatic ring, pulsation vibrations of the carbon skeleton of the aromatic ring, a wide structured band with several maxima in the range of 1050 – 1270 cm–1 and a band associated with the CH2 bridge. The structure of the absorption spectrum of photoresists of the AZ nLOF series is similar to the structure of the spectrum of phenol-formaldehyde photoresist FP9120. It was shown that the vibration band of CH3 groups at 2945 cm-1 is due to the solvent.

A wide-frequency triboelectric vibration sensor for self-powered machinery health monitoring

Abnormal vibration is usually a precursor to structural damage and performance degradation industrial equipment and transportation. Vibration detection at critical locations such as electrical motors and bearings within large equipment has emerged as an indispensable method for machinery health monitoring. Current vibration detection instruments mostly need to be powered by cables or batteries, which has application limitations in complex moving equipment and restricted space. In this paper, a disc-like triboelectric nanogenerator (DL-TENG) with a multi-sized honeycomb structure is proposed as an innovative solution for achieving wide band and high precision acceleration detection of the vibration. Multi-diameter polytetrafluoroethylene (PTFE) balls are used as friction materials to achieve the high voltage output of the TENG, providing sufficient energy for the detection circuit. By carefully designing suitable honeycomb structures for PTFE balls of different diameters, the ability to detect broadband vibration signals is obtained. The experimental results demonstrate that DL-TENG with honeycomb structure and multi-size PTFE balls can detect acceleration signals ranging from 10 to 2000 Hz, and the acceleration measurement range can reach 1–11 m/s2 with an acceleration resolution of 0.1 m/s2. Moreover, DL-TENG can output more than 80 V peak-to-peak under vibration conditions of 11 m/s2. And under vibration conditions of 8 m/s2, the DL-TENG can fully charge a 100 μF capacitor to 5 V in just 100 seconds. By equipping a special circuit for DL-TENG, wireless self-powered vibration detection is realized. This study is expected to be applied in the scenario of vibration information collection in complex ring vibration environment and provides a new paradigm for the realization of self-powered vibration sensors.

Design of band reconfigurable Koch fractal antenna for wideband applications

In this communication, a band reconfigurable fractal antenna with modified partial ground is proposed for wireless applications. Four switches using PIN diodes supported by the antenna biasing circuit provide frequency reconfigurability, while star-shaped fractal geometry is used to achieve both miniaturisation and wideband functioning in the proposed antenna. The surface current distribution of the radiating patch is altered by the ON and OFF states of the PIN diode, which leads to the multiband resonance and reconfiguration features of the designed structure. The designhas an overall electrical size of 70 × 45 × 1.6 mm3 and is made on a commonly available FR4 substrate with a thickness of 1.6 mm and a dielectric constant of 4.4. The three operational bands are as follows: case I, which covers 3.7–5 GHz (30 %); case II, which covers 1.7–3.5 GHz (71 %); and case III, which covers 1.4–4 GHz (96 %). Two distinct bands are obtained in cases I and II; and case III nearly covers the frequency band of cases I and II. Therefore, the impedance bandwidth (IBW)offers continuous wideband frequency coverage from 1.4 to 5 GHz (110 %). To sense the full band and then modify its bandwidth to choose the appropriate sub-band and prefilter out the others, the proposed antenna may switch between a wide operational band of 1.4–5 GHz with three distinct subbands. The antenna could potentially be useful for wireless communication systemsin the future due to its frequency-selective feature and stable radiation patterns.

The investigation on the structural, electronic and optical properties of wide band gap semiconductor material Bi24M2O40 (M = Si, Ge, As, P)

The mechanical, optical, electrical and thermal properties of Bi24M2O40 (M = Si, Ge, As, P) are calculated by using the first-principles calculations based on density functional. The results show that Bi24Si2O40 has the highest elastic constant C11 (195.27), strong crush resistance on the A-axis, the largest bulk modulus (111.9GPa) and shear modulus (60.1GPa), the greatest crush resistance and the strongest shear deformation resistance. Bi24As2O40 has the highest hardness (9.0GPa). According to Pugh’s rule, Bi24Si2O40 and Bi24Ge2O40 are inherently ductile, while Bi24P2O40 and Bi24As2O40 are inherently brittle. The structural energy band curves show that Bi24M2O40 (M = Si, Ge, As, P) belongs to the direct band gap semiconductor. The static dielectric functions of Bi24Si2O40, Bi24Ge2O40, Bi24P2O40 and Bi24As2O40 are 4.37, 4.45, 4.47 and 4.49, respectively. The maximum absorption coefficient of Bi24P2O40 is greater than that of the other three crystals and its maximum absorption coefficient is close to 2 × 105cm−1. In the far ultraviolet region, Bi24Ge2O40 has the highest reflectivity and can be used in semiconductor shading devices. In the range of 0–10 eV, the dielectric function curves of EX direction and EZ direction have high anisotropy. If it is greater than 10 eV, it is isotropic. Bi24P2O40 has the best thermodynamic stability at high temperatures. The order of phase stability of four semiconductor is Bi24As2O40 > Bi24P2O40 > Bi24Ge2O40 > Bi24Si2O40.

Antibacterial Activity, GC MS Analysis and In Silico Validation of Bioactive Compound from Endophytic Fungus Lasiodiplodia pseudotheobromae EF-9.

Secondary metabolites synthesized by endophytic fungi have garnered significant interest for their broad applications in treating various ailments. In this study involving 20 plant samples, 11 endophytic fungi were isolated and cultured, and Lasiodiplodia pseudotheobromae EF-9, derived from Hibiscus rosa-sinensis, demonstrated greater antibacterial efficacy than the other isolated endophytes. Phylogenetic analyses using 18S rRNA gene confirmed the EF-9 identity as L. pseudotheobromae. Following mass production, the active compound was partially purified using column chromatography. The fraction collected at the 60th min exhibited good antibacterial activity against Bacillus coagulans (MTCC 6735) and Shigella flexneri (ATCC 12022), with an inhibition zone of approximately 20 mm in diameter. UV spectral studies revealed a wide absorption band at 430 nm. High Performance Liquid Chromatography (HPLC) of the active fraction showed a distinct peak with a retention time of 4.216 min at 430 nm absorbance. Gas Chromatography-Mass Spectrometry (GC-MS) identified the active compound in the L. pseudotheobromae EF-9 culture broth extract as Bis(2-ethylhexyl) phthalate, which displayed a peak at 16.856 min and covered 66.69% of the area in the spectral analysis.