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In-situ thermal reduction synthesis of porous carbon nitride doped gadolinium sulfide nanocomposite: An emerging electrode material for high-performance supercapacitor

2023-12Journal of Energy Storage, v.74, no.Part A

The multiple-step synthesis, harmful organic solvents, and hazardous binders are the major obstacles for supercapacitor (SC) designers. A conventional synthesis of nanocomposite is normally involves complex steps and time-consuming. To reduce these multiple steps and process time, we report carbon nitride-doped gadolinium sulfide (CN/Gd2S3) nanocomposite obtained via a one-step in situ thermal reduction method. In our study, we introduce poly(3,4-ethylenedioxythiophenes): polystyrene sulfonate (PEDOT–PSS) to act as a dual role of binder and conducting additive, and we use DI water as the solvent for the SC electrode. Despite the reduced fabrication steps, our electrode exhibits an extraordinary specific capacity value of 1831 F g−1 at 1 A g−1 in an aqueous 2 M KOH electrolyte, as well as 98.5 % retention after 5000 cycles. Moreover, a solid-state asymmetric SC (ASC) was further made up with activated carbon (AC) as a negative electrode and CN/Gd2S3 as a positive electrode, providing a high energy density of 70.95 W h kg−1 at a specific power density of 250 W kg−1 at 1 A g−1. The remarkable specific capacitance retention of the ASC could maintain 86.8 % after 5000 cycles, indicating the potential application of CN/Gd2S3 electrode material for energy storage devices. This device (CN/Gd2S3//AC) showcased its practical application by powering twenty-six light-emitting diodes (LEDs) (each of 2.7 V) and appeared as an attractive energy storage unit for portable devices. © 2023 The Authors. Published by Elsevier Ltd.

Influence of calcination temperature on Cd0.3Co0.7Fe2O4 nanoparticles: Structural, thermal and magnetic properties

2015-11Journal of Magnetism and Magnetic Materials, v.394, pp.70 - 76

Cadmium substituted cobalt ferrite nanoparticles are synthesis using the chemical method. The as-prepared ferrite nanoparticles are calcinated at 300 °C and 600 °C respectively. The samples are studied using; Powder XRD, SEM with EDX, TEM, FT-IR, TG-DTA and vibrating sample magnetometer (VSM) in order to study the calcination temperature effect on structural, morphological and magnetic properties. The magnetic properties, like saturation magnetization and coercivity increases with increasing the calcination temperature. This enhancement is attributed to the transition from amulti-domain to a single-domain nature. The absorption bands observed at 588 cm-1 (ν1) and 440 cm-1 (ν2) are attributed to the vibrations of tetrahedral and octahedral complexes. The TG-DTA curves reveal the thermal stability of the prepared ferrite nanoparticles. The calcination temperature influences the magnetic properties, surface morphology and crystalline size. © 2015 Elsevier B.V. All rights reserved.

A Microfluidic Approach to Investigating a Synergistic Effect of Tobramycin and Sodium Dodecyl Sulfate on Pseudomonas aeruginosa Biofilms

2016-01Analytical Sciences, v.32, no.1, pp.67 - 73

In recent years, a microfluidic technology has contributed a significant role in biological research, specifically for the study of biofilms. Bacterial biofilms are a source of infections and contamination in the environment due to an extra polymeric matrix. Inadequate uses of antibiotics make the bacterial biofilms antibiotic resistant. Therefore, it is important to determine the effective concentration of antibiotics in order to eliminate bacterial biofilms. The present microfluidic study was carried out to analyze the activities of tobramycin and sodium dodecyl sulfate (SDS) against Pseudomonas aeruginosa biofilms with a continuous flow in order to achieve a greater delivery of the agents. The results show that a co-treatment of tobramycin and SDS significantly reduced the biomass of biofilms (by more than 99%) after 24 h. Tobramycin and SDS killed and detached bacteria in the cores of biofilms. Evidently, our data suggest that a microchannel would be effective for both quantitative and qualitative evaluations in order to test combinatorial effect of drugs and chemicals on a complexed biological system including biofilm. © 2016 The Japan Society for Analytical Chemistry.

Prospects of soft biopotential interfaces for wearable human-machine interactive devices and applications

2023-09Soft Science, v.3, no.3

Human interaction with machines can be made easy, comfortable, and accessible by introducing user-friendly interfaces. In the case of wearable devices, their sensors and other interfacing elements are very well within the proximity of users. Since biopotential signals can be accessed from the surface of the human skin, users can have seamless interaction with wearable human-computer interactive devices. Rigid interfaces can hinder the user experience, and therefore, the need for soft biopotential interfaces is important. Imperceptible and unobtrusive soft biopotential interfaces will drastically enhance many aspects of human-computer interaction. This paper reviews the use of soft, flexible, and stretchable biopotential interfaces in wearable human-machine interactive devices. Additionally, attention is brought to the scope of other possible applications of soft biopotential interfaces in wearable devices. © The Author(s) 2023.

Effect of calcination temperature on cobalt substituted cadmium ferrite nanoparticles

2015-07Journal of Materials Science: Materials in Electronics, v.26, no.7, pp.5078 - 5084

The Cd0.9Co0.1Fe2O4 nanoparticles are synthesized using chemical co-precipitation method. The as-prepared samples are calcinated at 300 and 600 °C for 2 h. The thermal effects on structural, morphological and magnetic properties are reported. The X-ray diffraction data confirm the formation of single-phase cubic spinel structure. The Surface morphology and compositional features are studied using SEM with EDX and TEM measurements. The Magnetic properties of samples are evaluated using vibrating sample magnetometer. The magnetic properties, like saturation magnetization and coercivity are increases with increasing calcination temperature. The enhancement is attributed to the transition from a multi-domain to a single-domain nature. From the FTIR spectra, it is confirmed that the vibrations of tetrahedral and octahedral complexes corresponds to absorption bands at 590 cm−1 (ν1) and 460 cm−1 (ν2) respectively. The particle size enhances significantly with increasing the calcinated temperature. © 2015, Springer Science+Business Media New York.

Precoding Design for Ensuring Data Freshness in Multi-user MISO Networks

ACCEPTIEEE Transactions on Wireless Communications

The existing multiple-input single-output (MISO) design to transmit data reliably to multiple mobile users (MUs) has become insufficient as MUs require fresh data, not just data. Therefore, in this paper, we consider multi-user MISO networks, where a base station (BS) equipped with multiple antennas serves MUs that want to maintain data freshness. To analyze the data freshness in this network, we first define the age-of-information (AoI) violation ratio, which is the ratio of duration that the AoI is larger than the AoI violation threshold to a sensing period. We then obtain the upper bound on the AoI violation ratio using the smooth maximum/minimum unit. We consider an optimization problem that minimizes the AoI violation ratio of multiple MUs. We propose a generalized power iteration (GPI) precoding algorithm to find a principal precoding vector that satisfies a first-order optimality condition of the optimization problem. Furthermore, for the scenario where the BS has the imperfect channel state information (CSI) of MUs, we provide the upper bound on the AoI violation time using the lower bound on the ergodic spectral efficiency, and also design the GPI precoding algorithm. Simulation results show proposed methods outperform baseline methods and demonstrate the effect of network parameters on the AoI violation probability. IEEE

Bifunctional Fenton-like catalyst enabling oxidative and reductive removal of contaminants synergically in chemical reagent-free aerated solution

2024-02Applied Catalysis B: Environmental, v.341

This study demonstrated the performance of Fe2O3 nanorods-loaded carbon nanofiber sheet (Fe2O3/CNF) as a heterogeneous Fenton-like catalyst for simultaneous removal of various organic and inorganic contaminants without external energy input and chemical reagents. Fe2O3/CNF exhibited notable activities for spontaneous oxidative degradation and reductive transformation in ambient solution, with a synergistic effect for removing dual contaminants (organic||inorganic). The synergistic redox conversions on Fe2O3/CNF were facilitated by the in-situ generation of oxidant and reductant. The additional oxidant can be generated by the reaction of chromium species with in-situ produced H2O2 while the additional reductant can be generated by the incomplete oxidation of organic contaminants. Various spectroscopic characterizations and mechanistic analyses suggest that simultaneous redox conversions are induced by spontaneous electron transfers on Fe2O3/CNF. Furthermore, a flow-reactor equipped with Fe2O3/CNF achieved the simultaneous removal of dual contaminants, making it an effective reactive filter that operates without chemical reagents for water treatment. © 2023 Elsevier B.V.

Conductance stable and mechanically durable bi-layer EGaIn composite-coated stretchable fiber for 1D bioelectronics

2023-07Nature Communications, v.14, no.1

Deformable semi-solid liquid metal particles (LMP) have emerged as a promising substitute for rigid conductive fillers due to their excellent electrical properties and stable conductance under strain. However, achieving a compact and robust coating of LMP on fibers remains a persistent challenge, mainly due to the incompatibility of conventional coating techniques with LMP. Additionally, the limited durability and absence of initial electrical conductivity of LMP restrict their widespread application. In this study, we propose a solution process that robustly and compactly assembles mechanically durable and initially conductive LMP on fibers. Specifically, we present a shearing-based deposition of polymer-attached LMP followed by additional coating with CNT-attached LMP to create bi-layer LMP composite with exceptional durability, electrical conductivity, stretchability, and biocompatibility on various fibers. The versatility and reliability of this manufacturing strategy for 1D electronics are demonstrated through the development of sewn electrical circuits, smart clothes, stretchable biointerfaced fiber, and multifunctional fiber probes. © 2023, The Author(s).

(NH4)2V7O16 as a Cathode Material for Rechargeable Calcium-Ion Batteries: Structural Transformation and Co-Intercalation of Ammonium and Calcium Ions

2023-09Chemistry of Materials, v.35, no.19, pp.7974 - 7983

Calcium-ion batteries (CIBs) are viable alternatives to lithium-ion batteries. However, few cathode materials can reversibly intercalate Ca ions in anhydrous electrolytes. Most high-capacity materials contain crystal water, causing unwanted reactions on the anode. Herein, we report a crystal-water-free ammonium vanadate, (NH4)2V7O16, as a CIB host material. Synthesized via a microwave-assisted hydrothermal method, (NH4)2V7O16 exhibits a layered structure with stacked V7O16 layers and interlayer ammonium ions hydrogen-bonded to adjacent oxygen atoms. We demonstrate the reversible electrochemical intercalation of Ca2+ ions into (NH4)2V7O16, achieving a reversible capacity of 89 mA h g-1 and an average discharge voltage of ∼3.21 V vs Ca/Ca2+. Although (NH4)2V7O16 displays poor rate capability and cycling performance, we reveal a unique reaction mechanism. During the initial charge, an irreversible structural change occurs, removing all ammonium ions and inserting a small amount of Ca ions, forming Ca0.37V7O16. This suggests an ion-exchange reaction between calcium and ammonium ions. Subsequent cycles exhibit the reversible coinsertion and coextraction of calcium and ammonium ions. We observe that V7O16 lacks structural stability without interlayer cations. Our findings offer insight into electrochemical reaction processes in crystal-water-free layered materials containing interlayer ammonium ions, highlighting the importance of cointercalation between ammonium and carrier ions for reversible cycling. © 2023 American Chemical Society.

GPUTucker: Large-Scale GPU-Based Tucker Decomposition Using Tensor Partitioning

2024-03Expert Systems with Applications, v.237, no.Part A

Tucker decomposition is used extensively for modeling multi-dimensional data represented as tensors. Owing to the increasing magnitude of nonzero values in real-world tensors, a growing demand has emerged for expeditious and scalable Tucker decomposition techniques. Several graphics processing unit (GPU)-accelerated techniques have been proposed for Tucker decomposition to decrease the decomposition speed. However, these approaches often encounter difficulties in handling extensive tensors owing to their huge memory demands, which exceed the available capacity of GPU memory. This study presents an expandable GPU-based technique for Tucker decomposition called GPUTucker. The proposed method meticulously partitions sizable tensors into smaller sub-tensors, which are referred to as tensor blocks, and effectively implements the GPU-based data pipeline by handling these tensor blocks asynchronously. Extensive experiments demonstrate that GPUTucker outperforms state-of-the-art Tucker decomposition methods in terms of the decomposition speed and scalability. © 2023 Elsevier Ltd

Characteristics and electrochemical performances of nickel@nano-silicon/carbon nanofibers composites as anode materials for lithium secondary batteries

2023-05Bulletin of the Korean Chemical Society, v.44, no.10, pp.852 - 864

Si is a next-generation ideal anode material for Li-ion batteries (LIBs) because of its high-theoretical capacity (4200 mAh/g) and natural abundance. However, severe volume expansion and unstable solid electrolyte interface (SEI) film formation during lithiation/delithiation, and poor electron conductivity have significantly restricted the commercial application of Si. In this study, transition metal-coated Si was synthesized and used as the anode material of LIBs. The transition metal salt of Ni was dissolved in an aqueous solution and used to coat the metal surface of Si nanoparticles. The coating was achieved by dropwise addition of metal solutions into Si dispersions. Thereafter, carbon nanofibers (CNFs) were grown on the transition metal-coated Si nanoparticles via chemical vapor deposition method. The morphologies, compositions, and crystal quality of transition metal@Si/CNFs composites were characterized by transmission electron microscopy, scanning electron microscopy, x-ray diffraction, Raman spectroscopy, and thermogravimetric analysis. The electrochemical characteristics of the hybrid anodes were investigated using a coin cell and battery tester. Voltage profile measurements at 0.1 A/g of 0.02 M-Ni@Si/CNFs composite showed satisfactory initial Coulombic efficiency of 85.6%; 0.01 M-Ni@Si/CNFs composite exhibited high initial capacity of 1300.9 mAh/g retained to 828.4 mAh/g after 100 cycles, corresponding to 63.7% capacity retention. Even at high current densities, the 0.02 M-Ni@Si/CNFs composite delivered 342.78 mAh/g of capacity at 5 A/g. This work realizes a Si-based hybrid anode from Ni-coated Si catalyst used for direct CNFs synthesis with a stable SEI layer, superior initial Coulombic efficiency with satisfactory cycle and rate performance suitable for commercialized advanced battery applications. © 2023 Korean Chemical Society, Seoul & Wiley-VCH GmbH.

Acetate-Mediated Odorant Receptor OR51E2 Activation Results in Calcitonin Secretion in Parafollicular C-Cells: A Novel Diagnostic Target of Human Medullary Thyroid Cancer

2023-06Biomedicines, v.11, no.6

Medullary thyroid cancer originates from parafollicular C-cells in the thyroid. Despite successful thyroidectomy, localizing remnant cancer cells in patients with elevated calcitonin and carcinoembryonic antigen levels remains a challenge. Extranasal odorant receptors are expressed in cells from non-olfactory tissues, including C-cells. This study evaluates the odorant receptor signals from parafollicular C-cells, specifically, the presence of olfactory marker protein, and further assesses the ability of the protein in localizing and treating medullary thyroid cancer. We used immunohistochemistry, immunofluorescent staining, Western blot, RNA sequencing, and real time-PCR to analyze the expression of odorant receptors in mice thyroids, thyroid cancer cell lines, and patient specimens. We used in vivo assays to analyze acetate binding, calcitonin secretion, and cAMP pathway. We also used positron emission tomography (PET) to assess C11-acetate uptake in medullary thyroid cancer patients. We investigated olfactory marker protein expression in C-cells in patients and found that it co-localizes with calcitonin in C-cells from both normal and cancer cell lines. Specifically, we found that OR51E2 and OR51E1 were expressed in thyroid cancer cell lines and human medullary thyroid cancer cells. Furthermore, we found that in the C-cells, the binding of acetate to OR51E2 activates its migration into the nucleus, subsequently resulting in calcitonin secretion via the cAMP pathway. Finally, we found that C11-acetate, a positron emission tomography radiotracer analog for acetate, binds competitively to OR51E2. We confirmed C11-acetate uptake in cancer cells and in human patients using PET. We demonstrated that acetate binds to OR51E2 in C-cells. Using C11-acetate PET, we identified recurrence sites in post-operative medullary thyroid cancer patients. Therefore, OR51E2 may be a novel diagnostic and therapeutic target for medullary thyroid cancer. © 2023 by the authors.