A flexible, lightweight and stretchable all-solid-state supercapacitor based on warp-knitted stainless-steel mesh for wearable electronics

Highly conductive, flexible, stretchable and lightweight electrode substrates are essential to meet the future demand on supercapacitors for wearable electronics. However, it is difficult to achieve the above characteristics simultaneously. In this study, ultrafine stainless-steel fibers (with a diameter of ≈30 μm) are knitted into stainless-steel meshes (SSMs) with a diamond structure for the fabrication of textile stretchable electrodes and current collectors. The electrodes are fabricated by utilizing an electrodeposited three-dimensional network graphene framework and poly(3,4-ethylenedioxythiophene) (PEDOT) coating on the SSM substrates via a two-step electrodeposition process, which show a specific capacitance of 77.09 F g−1 (0.14 A g−1) and superb cycling stability (91% capacitance retention after 5000 cycles). Furthermore, the assembled flexible stretchable supercapacitor based on the PEDOT/reduced graphene oxide (RGO)@SSM electrodes exhibits an areal capacitance (53 mF cm−2 at 0.1 mA cm−2), a good cycling stability (≈73% capacitance retention after 5000 cycles), rate capability (36 mF cm−2 at 5 mA cm−2), stretchable stability (≈78% capacitance retention at 10% strain for 500 stretching cycles) and outstanding flexibility and stability under various bending deformations. The assembled supercapacitors can illuminate a thermometer and a light-emitting diode, demonstrating their potential application as stretchable supercapacitors. This simple and low-cost method developed for fabricating lightweight, stretchable and stable high-performance supercapacitors offers new opportunities for future stretchable electronic devices.

New Advances in Graphene-Based Three-Dimensional Structures

Graphene is defined as a two-dimensional network of carbon atoms with a single atom thickness and a hexagonal crystalline structure with sp2 hybridization compacted by covalent bonds. Due to its structure and geometry, graphene has unique properties, including a large specific surface area, rapid mobility of load carriers, and high thermal and electrical conductivity. However, these characteristics are limited due to the restructuring of graphene sheets. For this reason, there are many studies devoted to the synthesis of three-dimensional structures that prevent the agglomeration of the sheets and the loss of properties of the graphene structure. These three-dimensional structures have low density, high porosity and surface area, stable mechanical properties, and good mass and electron transfer properties. This chapter aims to summarize the synthesis methods of the different three-dimensional structures derived from graphene as well as their wide range of applications in environmental remediation, sensors, biomedical and energy-related applications, among many others.

Preparation and Characterization of Gaphene-Doped Carbon-Aerogel Electrode

Carbon-aerogel is a kind of nano-porous carbon material with special three-dimensional network structure. Electrode materials with high specific surface area, high porosity, superior conductivity and low density were obtained by adding graphene to prepare graphene-doped carbon-aerogels.

Crystal structure, Hirshfeld surface, and DFT studies of 4-((pyrrolidin-1-ylsulfonyl)methyl)aniline

The crystal structure investigation of the title compound 4-((pyrrolidin-1-ylsulfonyl) methyl)aniline (PSMA) C11H16N2O2S shows that the molecule is essentially coplanar with a dihedral angle of 26.70(14)°between the pyrrolidine and the benzene rings. A pair of strong N-H···O hydrogen bonds produces continuous two-dimensional sheets with R22(18) ring motifs. The crystal structure also features a weak C-H···π interaction resulting in a three-dimensional network. Density functional theory (DFT) calculations reveal that the experimental and calculated geometric parameters of the molecule are nearly the same. Hirshfeld surface analysis has been carried out to study the various intermolecular interactions responsible for the crystal packing. Theoretical calculations indicate an excellent correlation between the experimental and the simulated UV spectra.

MOLECULAR-DYNAMIC SIMULATION OF MIXTURES OF MODIFIED FULLERENES AND 1,8-OCTANDITHIOL

В данной работе мы сообщаем о результатах сравнительного атомистического моделирования двух систем, содержащих функцианализированные фуллерены метилового эфира фенил- C-масляной кислоты (PCBM ) и фенил- C-масляной кислоты (PCBM ) в присутствии растворителя 1,8-октандитиола (ODT). Для реализации расчетов использовался метод молекулярной динамики на базе программного пакета LAMMPS. Зафиксировано принципиальное различие в упаковке молекул PCBM и PCBM . В случае систем с PCBM наблюдается тенденция к постепенному разделению растворителя и фуллеренов. При этом в образцах с PCBM наблюдается тенденция к формированию устойчивых трехмерных сетчатых структур, образованных двумя взаимопроникающими фазами: фуллеренами и молекулами ODT. С целью проверки масштабируемости наблюдаемого структурного упорядочения для смеси PCBM с ODT было выполнено моделирование в ячейке с удвоенным размером ребер. В этом случае мы также наблюдаем формирование биконтинуальных структур из фуллеренов и растворителя. In this work, we report on the results of comparative atomistic modeling of two systems containing functionalized fullerenes of phenyl-C-butyric acid methyl ester (PCBM ) and phenyl- C -butyric acid (PCBM ) in the presence of a high-boiling solvent 1,8 -octanedithiol (ODT). The calculations were performed by full atomistic molecular dynamics with using LAMMPS software package. A fundamental difference in the packaging of PCBM and PCBM molecules was detected. In the case of systems with PCBM , there is a tendency towards gradual separation of the solvent and fullerenes. At the same time, in samples with PCBM , there is a tendency to the formation of stable three-dimensional network structures formed by two interpenetrating phases: fullerenes and ODT molecules. In order to check the scalability of the observed structural ordering for the mixture of PCBM with ODT, an additional simulation was performed in a cell with doubled edge size. In this case, we also observe the formation of bicontinual structures from fullerenes and the solvent.

Methyl α-L-sorboside monohydrate

Methyl L-sorboside monohydrate, C7H14O6·H2O, was prepared from the rare sugar L-sorbose, C6H12O6, and crystallized. It was confirmed that methyl L-sorboside formed α-pyranose with a 2 C 5 conformation and crystallized with one water molecule of crystallization. In the crystal, molecules are linked by O—H...O hydrogen bonds, forming a three-dimensional network. The unit-cell volume of the title compound, methyl L-sorboside monohydrate, is 481.13 (2) Å3 (Z = 2), which is about 108.16 Å3 (29.0%) greater than that of half the amount of the chemical α-L-sorbose [745.94 (2) Å3 (Z = 4)].

A Cleanable Self-Assembled Nano-SiO2/(PTFE/PEI)n/PPS Composite Filter Medium for High-Efficiency Fine Particulate Filtration

A silicon dioxide/polytetrafluoroethylene/polyethyleneimine/polyphenylene sulfide (SiO2/PTFE/PEI/PPS) composite filter medium with three-dimensional network structures was fabricated by using PPS nonwoven as the substrate which was widely employed as a cleanable filter medium. The PTFE/PEI bilayers were firstly coated on the surfaces of the PPS fibers through the layer-by-layer self-assembly technique ten times, followed by the deposition of SiO2 nanoparticles, yielding the SiO2/(PTFE/PEI)10/PPS composite material. The contents of the PTFE component were easily controlled by adjusting the number of self-assembled PTFE/PEI bilayers. As compared with the pure PPS nonwoven, the obtained SiO2/(PTFE/PEI)10/PPS composite material exhibits better mechanical properties and enhanced wear, oxidation and heat resistance. When employed as a filter material, the SiO2/(PTFE/PEI)10/PPS composite filter medium exhibited excellent filtration performance for fine particulate. The PM2.5 (particulate matter less than 2.5 μm) filtration efficiency reached up to 99.55%. The superior filtration efficiency possessed by the SiO2/(PTFE/PEI)10/PPS composite filter medium was due to the uniformly modified PTFE layers, which played a dual role in fine particulate filtration. On the one hand, the PTFE layers not only increase the specific surface area and pore volume of the composite filter material but also narrow the spaces between the fibers, which were conducive to forming the dust cake quickly, resulting in intercepting the fine particles more efficiently than the pure PPS filter medium. On the other hand, the PTFE layers have low surface energy, which is in favor of the detachment of dust cake during pulse-jet cleaning, showing superior reusability. Thanks to the three-dimensional network structures of the SiO2/(PTFE/PEI)10/PPS composite filter medium, the pressure drop during filtration was low.

A comparative simulation of normalization methods for machine learning-based intrusion detection systems using KDD Cup’99 dataset

Network Intrusion detection systems (NIDS) detect malicious and intrusive information in computer networks. Presently, commercial NIDS is based on machine learning approaches that have complex algorithms and increase intrusion detection efficiency and efficacy. These machine learning-based NIDS use high dimensional network traffic data from which intrusive information is to be detected. This high-dimensional network traffic data in NIDS needs to be preprocessed and normalized to make it suitable for machine learning tools. A machine learning approach with appropriate normalization and prepossessing increases NIDS performance. This paper presents an empirical study on various normalization methods implemented on a benchmark network traffic dataset, KDD Cup’99, that has been used to evaluate the NIDS model. The present study shows decimal normalization has a better prediction performance than non-normalized traffic data categorized into ‘normal’ or ‘intrusive’ classes.