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Topic Review
NTC-Properties of a Geomorphic Clinoptilolite Sample
Negative temperature coefficient (NTC) materials are usually based on ceramic semiconductors, and electrons are involved in their transport mechanism. A new type of NTC material, adequate for alternating current (AC) applications, is represented by zeolites. Indeed, zeolites are single charge carrier ionic conductors with a temperature-dependent electrical conductivity. In particular, electrical transport in zeolites is due to the monovalent charge-balancing cations, like K+, capable of hopping between negatively charged sites in the aluminosilicate framework. Owing to the highly non-linear electrical behavior of the traditional electronic NTC materials, the possibility to have alternative types of materials, showing linearity in their electrical behavior, is very desirable. Among different zeolites, natural clinoptilolite has been selected for investigating NTC behavior since it is characterized by high zeolite content, a convenient Si/Al atomic ratio, good mechanical strength due to its compact microstructure, and low toxicity. Clinoptilolite has shown a rapid and quite reversible impedance change under heating, characterized by a linear dependence on temperature.
  • 3.1K
  • 11 Jul 2024
Topic Review
NPECs for Rheumatoid Arthritis Therapy
Natural plant extracts and compounds (NPECs), which originate from herbs or plants, have been used in the clinical treatment of rheumatoid arthritis (RA) for many years. 
  • 518
  • 25 Jun 2021
Topic Review
Novichok Agent
A Novichok agent (Russian: Новичо́к, "newcomer", "novice", "newbie") is a group of nerve agents, some of which are binary chemical weapons. The agents were developed at the GosNIIOKhT state chemical research institute by the Soviet Union and Russia between 1971 and 1993.[lower-alpha 1] Some Novichok agents at STP are solids while others are liquids. It is thought that dispersal for the solids is possible by ultrafine powder. Russian scientists who developed the nerve agents claim they are the deadliest ever made, with some variants possibly five to eight times more potent than VX, and others up to ten times more potent than soman. As well as Russia, Novichok agents have been known to be produced in Iran. In the 21st century, Novichok agents came to public attention after they were used to poison opponents of the Russian government, including the Skripals and two others in Amesbury, UK (2018) and Alexei Navalny (2020), but civil poisonings with this substance have been known since at least 1995. In November 2019, the Organisation for the Prohibition of Chemical Weapons (OPCW), which is the executive body for the Chemical Weapons Convention (CWC), added the Novichok agents to "list of controlled substances" of the CWC "in one of the first major changes to the treaty since it was agreed in the 1990s" in response to the 2018 poisonings in the UK.
  • 1.1K
  • 11 Nov 2022
Topic Review
Novel Spinel Nanomaterials for Photocatalytic Hydrogen Evolution Reactions
The energy demand generated by fossil fuels is increasing day by day, and it has drastically increased after the COVID-19 pandemic as industries and household utilities rejuvenate. Renewable sources are thus becoming more essential as easily available, alternative methods of low-cost energy generation. Among these renewables, solar energy, i.e., solar power, is a promising energy source and can be used for solar-based H2 evolution because H2 technology is a leading source of eco-friendly electricity generation, and most of the worldwide efforts to develop this method involve heterogeneous catalysis for H2 evolution via water splitting and its storage, i.e., using a fuel cell. In the current scenario, there is a need to develop a stable, recyclable, and reusable heterogeneous catalyst system, which is a great challenge. 
  • 411
  • 21 Aug 2023
Topic Review
Novel Nanomaterials for Hydrogen Production and Storage
Using hydrogen energy as an alternative renewable source of fuel is no longer an unrealized dream, it now has real-world application. The influence of nanomaterials on various aspects of hydrogen energy, such as hydrogen production, storage, and safety, is considerable.
  • 556
  • 29 Jan 2023
Topic Review
Novel Materials for Semi-Transparent Organic Solar Cells
The rapid development of photovoltaic technology has driven the search for novel materials that can improve the cost-effectiveness and efficiency of solar cells. Organic semiconductors offer unique optical tunability and transparency, allowing customization for the absorption of specific optical spectra like near-infrared radiation. Through the molecular engineering of electron donors and acceptors, these materials can be optimized for targeted optical selectivity. This adaptability enables the development of efficient energy-harvesting devices tailored for specific spectral regions. Consequently, organic semiconductors present a promising avenue for specialized applications such as semi-transparent organic solar cells. 
  • 192
  • 23 Jan 2024
Topic Review
Novel Excipients Used in Modified Release Vaginal Formulations
The formulation of an ideal vaginal drug delivery system (DDS), with the requisite properties, with respect to safety, efficacy, patient compliance, aesthetics, harmonization with the regulatory requirements, and cost, requires a meticulous selection of the active ingredients and the excipients used. Novel excipients defined by diversity and multifunctionality are used in order to ameliorate drug delivery attributes. Synthetic and natural polymers are broadly used in pharmaceutical vaginal formulations (solid, semi-solid dosage forms, implantable devices, and nanomedicines) with a promising perspective in improving stability and compatibility issues when administered topically or systemically. Moreover, the use of biopolymers is aiming towards formulating novel bioactive, biocompatible, and biodegradable DDSs with a controllable drug release rate. 
  • 1.5K
  • 14 Jan 2022
Topic Review
Novel Agent with the Terminal Phenoxy Group
The terminal phenoxy group is a moiety of many drugs in use today. Numerous literature reports indicated its crucial importance for biological activity; thus, it is a privileged scaffold in medicinal chemistry. Most often, the presence of the phenoxy moiety provided the chances for the compound to match the target, ensuring selectivity, the π–π interaction, or increase the ability to form the hydrogen bonds by the oxygen ether atom.
  • 581
  • 01 Sep 2022
Topic Review
Nonwoven Electrospun Membranes
A flexible and dependable method that has been extensively employed to construct nanofibrous scaffolds that resemble the extracellular matrix made from polymeric materials is electrospinning (ES). ES is superior to other techniques because of its unique capacity to create nanofibers with a high surface-to-volume ratio, low cost, simplicity of setup, freedom in material choice, and ability to alter the surface attributes and usefulness of the nanofibers. 
  • 444
  • 04 Dec 2023
Topic Review
Nonprecious Metal Homogeneously Catalyzed Formic Acid Dehydrogenation
Formic acid (FA) possesses a high volumetric concentration of H2 (53 g L−1). Moreover, it can be easily prepared, stored, and transported. Therefore, FA stands out as a potential liquid organic hydrogen carrier (LOHC), which allows storage and transportation of hydrogen in a safe way. The dehydrogenation to produce H2 and CO2 competes with its dehydration to give CO and H2O. For this reason, research on selective catalytic FA dehydrogenation has gained attention in recent years. Several examples of highly active homogenous catalysts based on precious metals effective for the selective dehydrogenation of FA have been reported. Among them are the binuclear iridium-bipyridine catalysts described by Fujita and Himeda et al. (TOF = 228,000 h−1) and the cationic species [IrClCp*(2,2′-bi-2-imidazoline)]Cl (TOF = 487,500 h−1). However, examples of catalytic systems effective for the solventless dehydrogenation of FA, which is of great interest since it allows to reduce the reaction volume and avoids the use of organic solvents that could damage the fuel cell, are scarce. 
  • 597
  • 30 Nov 2021
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