Design of XS2 (X = W or Mo)-Decorated VS2 Hybrid Nano-Architectures with Abundant Active Edge Sites for High-Rate Asymmetric Supercapacitors and Hydrogen Evolution Reactions

Two-dimensional layered transition metal dichalcogenides have emerged as promising materials for supercapacitors and hydrogen evolution reaction (HER) applications. Herein, the molybdenum sulfide (MoS₂)@vanadium sulfide (VS₂) and tungsten sulfide (WS₂)@VS₂ hybrid nano-architectures prepared via a facile one-step hydrothermal approach is reported. Hierarchical hybrids lead to rich exposed active edge sites, tuned porous nanopetals-decorated morphologies, and high intrinsic activity owing to the strong interfacial interaction between the two materials. Fabricated supercapacitors using MoS₂@VS₂ and WS₂@VS₂ electrodes exhibit high specific capacitances of 513 and 615 F g⁻¹, respectively, at an applied current of 2.5 A g⁻¹ by the three-electrode configuration. The asymmetric device fabricated using WS₂@VS₂ electrode exhibits a high specific capacitance of 222 F g⁻¹ at an applied current of 2.5 A g⁻¹ with the specific energy of 52 Wh kg⁻¹ at a specific power of 1 kW kg⁻¹. For HER, the WS₂@VS₂ catalyst shows noble characteristics with an overpotential of 56 mV to yield 10 mA cm⁻², a Tafel slope of 39 mV dec⁻¹, and an exchange current density of 1.73 mA cm⁻². In addition, density functional theory calculations are used to evaluate the durable heterostructure formation and adsorption of hydrogen atom on the various accessible sites of MoS₂@VS₂ and WS₂@VS₂ heterostructures.     

An Intriguing Array of Extrudate Patterns in Long-Chain Branched Polymers During Extrusion

The present study highlights a range of surface and volume extrudate patterns that can be detected during the extrusion flow of long-chain branched polymers. Thus, four linear low-density polyethylenes (LDPEs) have been extruded using a single-screw extruder coupled to an inline optical imaging system. The selected LDPEs are selected to outline the influence of molecular weight and long-chain branching on the types of melt flow extrusion instabilities (MFEI). Through the inline imaging system, space–time diagrams are constructed and analyzed via Fourier-transformation using a custom moving window procedure. Based on the number of characteristic frequencies, peak broadness, and whether they are surface or volume distortions, three main MFEI types, distinct from those typically observed in linear and short-chain branched polymers, are identified. The higher molecular weight, low long-chain branching LDPEs exhibited all three instability types, including a special type volume instability. Independently of the molecular weight, higher long-chain branching appeared to have a stabilizing effect on the transition sequences by suppressing volume extrudate distortions or limiting surface patters to a form of weak intensity type.     

Novel Linear,Piezoresistive, Auxetic Sensors Coated by AAA Battery Active Carbons with Supreme Sensitivity for Human Body Movement Detection

Herein, a novel strategy for creating low-cost, sustainable, piezoresistive auxetic sensors using the active carbon in consumed AAA batteries, promoting a circular economy, is presented. An auxetic structure with a fixed Poisson's ratio during the strain is designed for sensing. The sensor substrate is silicone RTV2, and the sensing element is the active carbon in AAA batteries chopped to microscale particles using an ultrasonic wave. The sensor mold is designed using Solidworks software and produced using a computer numerical control device and EdgeCam2014 software. The coating process is performed by spraying the prepared particles on the molded auxetic structure and putting the coated auxetic structure under ultraviolet ray to prepare the final sensor. Sensitivity tests are performed, and the results show that the proposed sensor has a better sensitivity of about 1000% and 410% than the previous mixed and layered composite auxetic counterparts. The proposed sensor has linear sensitivity during the strain (estimated with a line with a slope of 0.64) while previous ones have a nonlinear performance (estimated at least with two lines). The sustainable sensor is implemented to detect the movements of the human body, including the movements of the wrist, finger, elbow, and forearm.     

Community detection and service discovery on Social Internet of Things

Due to the increasing growth of objects and problems such as increased traffic, overload, delay in response, and low search volume in the service discovery process in the complex Social Internet of Things (SIoT) environment, we provide an effective mechanism in the service discovery process by grouping objects based on common criteria that help us improve service search performance. In this article, we present a new method for clustering objects so that we can group objects that have common services and can work together. Hence, we create a set of different associations for the type of service and reciprocal cooperation of objects. With its help, instead of a global network search, we can perform service searches locally more efficiently and ensure the accuracy and correctness of searches and their answers. Then, we have provided a new mechanism for the service discovery process. In addition, we categorized communities based on their size to compare our proposed algorithm with other approaches using factors such as modularity in SIoT. Finally, we achieved sufficient efficiency in service discovery (86.81% and 88.28%) and demonstrated better performance of the proposed approach in identifying communities.     

Theoretical analysis on the electronic properties of bubble-wrap carbon nanostructure: fullerene-doped graphene

Journal of Computational Electronics - The bubble-wrap carbon nanostructure as a hybrid structure of fullerene with graphene sheet is studied in this research. The chosen structure has fullerene...     

Pore-to-mesoscale network modeling of heat transfer and fluid flow in packed beds with application to process design

A dual-network model (DNM) representing the topological characteristics of both the pore space and solid fraction of a packed bed was developed to study coupled incompressible water flow and heat transport from the pore-scale to mesoscale (μm-cm) with the consideration of temperature-dependent fluid viscosity. The DNM was validated and used to study the temperature and velocity at the pore scale and their effects on fluid flow and heat transfer. Then the pore volume of the DNM was varied to illustrate the effect of bed porosity on transport processes, quantifying the trade-off between flow conditions and heat transfer. This work demonstrates the ability of the DNM to simulate pore-scale fluid flow and heat transfer simultaneously, which can then be averaged over the entire simulation domain to approximate meso/macroscopic parameters efficiently in relation to the pore geometry.     

Recent Advances in Nanomaterials-Based FETs for SARS-CoV-2 (COVID-19 Virus) Diagnosis

The emergence of infectious diseases that are quickly spreading, like the coronavirus (COVID-19), necessitates the development of efficient biosensors that can quickly detect and identify pathogens. It is essential to create sensitive virus detection methods in order to stop a virus from spreading throughout the world. It is determined that field-effect transistors (FETs) made of nanomaterials are potential candidates for rapid virus identification due to how easily the electronic transport characteristics of such an atomically thin nanomaterial can be affected by perturbations. Various FETs in this review article are investigated that are based on nanoparticles, carbon nanotubes (CNT), graphene, graphene-oxide, and semiconducting transition metal dichalcogenides (TMDs) WSe₂ in order to show that they are promising biosensors in regards to quickly and precisely detect COVID-19. The conjugation of nanomaterials with proteins enables the direct delivery of antiviral agents to the host cells. This method also minimizes the off-target effects and enables the targeted interactions. This mechanism has produced encouraging results in regards to sensing or treating COVID-19. The high surface area and extremely small size of nanomaterials make them crucial in regards to the development of new detection methods. The point-of-care test method of detection is quick, simple, and user-friendly, and it only requires a small amount of a patient's blood. It does not require a laboratory or trained professionals. This overview of the current research that is conducted on nanomaterials will prove to be useful in the process of formulating strategies for the diagnosis, treatment, and vaccination of viruses in opinion. Finally, the conclusion of this review provides a summary of the current challenges and the future prospects.     

Understanding the Diffusion-Dominated Properties of MOF-Derived Ni–Co–Se/C on CuO Scaffold Electrode using Experimental and First Principle Study

Batteries and supercapacitors continue to be one of the most researched topics in the class of energy storage devices. The continuous development of battery and supercapacitor cell components has shown promising development throughout the years—from slabs of pure metal to porous and tailored structures of metal-based active materials. In this direction, metal–organic frameworks (MOFs) serve great advantages in improving the properties and structure of the derived metal-based active materials. This research provides a novel electrode material, Ni–Co–Se/C@CuO, derived from Ni–Co-MOF integrated with pre-oxidized Cu mesh. The superior electrochemical performance of Ni–Co–Se/C@CuO over Ni–Co-MOF@CuO is evident through its higher specific capacity, lower resistivity, richer redox activity, and more favorable diffusion-dominated storage mechanism. When assembled as a hybrid supercapacitor (HSC), the hybrid device using rGO and Ni–Co–Se/C@CuO as electrodes exhibits a high energy density of 42 W h kg⁻¹ at a power density of 2 kW kg⁻¹, and maintains its capacity retention even after 20 000 cycles. The improved capacity performance is also evaluated using first-principle investigations, revealing that the unique and preserved heterostructure of Ni–Co–Se/C@CuO portrays enhanced metallic properties. Such evaluation of novel electrodes with superior properties may benefit next-generation electrodes for supercapacitor devices.     

Point-of-Care Diagnostic Platforms for Loop-Mediated Isothermal Amplification

The loop-mediated isothermal amplification (LAMP) method is one of the Nucleic acid amplification tests (NAATs) that allows for the amplification of target regions without using a thermal cycle. With its unique primer design, LAMP ensures the rapid replication of the targeted DNA region with high specificity and high efficiency. LAMP technology is used for diagnostic purposes in pathogen detection due to its ease of use, low cost, and simplicity without requiring complex equipment. A wide range of LAMP diagnostic platforms have been developed for applications in bacteria, virus, and parasitic pathogen detection. Herein, the methodology of LAMP technology and its applications in pathogen detection and SNP genotyping and mutation detection are discussed. Point-of-care (PoC) LAMP platforms designed with the principles of microfluidic chip technology, including LAMP-on-a-chip, paper-based LAMP, and smartphone-based LAMP applications have been elaborated. LAMP technology represents a fast, robust, and reliable diagnostic platform for point-of-care testing.