This document summarizes and extends definitions and notations for the description of tactic polymers and the diad structures of which they are composed. It formally recognizes and resolves apparent inconsistencies between terminology used in the polymer field to describe tactic polymers and terminology in more common use in organic chemistry. Specifically, the terms m and r diads are recommended to replace the terms meso and racemo diads. The definitions are also updated from those in the existing Stereochemistry Document to use the term ‘stereogenic centre’, rather than ‘chiral or prochiral atoms’. Further, the terms relating to tacticity have been defined for the constituent macromolecules, rather than for the polymers composed of those macromolecules. Therefore, this document also forms an addendum and corrigendum to the 1981 document, ‘Stereochemical definitions and notations relating to polymers’.
The waste stream of obsolete electronic equipment grows exponentially, creating a worldwide pollution and resource problem. Electrical and electronic waste (e-waste) comprises a heterogeneous mix of glass, plastics (including flame retardants and other additives), metals (including rare Earth elements), and metalloids. The e-waste issue is complex and multi-faceted. In examining the different aspects of e-waste, informal recycling in developing countries has been identified as a primary concern, due to widespread illegal shipments; weak environmental, as well as health and safety, regulations; lack of technology; and inadequate waste treatment structure. For example, Nigeria, Ghana, India, Pakistan, and China have all been identified as hotspots for the disposal of e-waste. This article presents a critical examination on the chemical nature of e-waste and the resulting environmental impacts on, for example, microbial biodiversity, flora, and fauna in e-waste recycling sites around the world. It highlights the different types of risk assessment approaches required when evaluating the ecological impact of e-waste. Additionally, it presents examples of chemistry playing a role in potential solutions. The information presented here will be informative to relevant stakeholders seeking to devise integrated management strategies to tackle this global environmental concern.
This glossary provides a formal vocabulary of terms for concepts in surface analysis and gives clear definitions to those who utilize surface chemical analysis or need to interpret surface chemical analysis results but are not themselves surface chemists or surface spectroscopists.
As increasingly smaller molecular materials and material structures are devised or developed for technological applications, the demands on the processes of lithography now routinely include feature sizes that are of the order of 10 nm. In reaching such a fine level of resolution, the methods of lithography have increased markedly in sophistication and brought into play 2terminology that is unfamiliar, on the one hand, to scientists tasked with the development of new lithographic materials or, on the other, to the engineers who design and operate the complex equipment that is required in modern-day processing. Publications produced by scientists need to be understood by engineers and vice versa, and these commonly arise from collaborative research that draws heavily on the terminology of two or more of the traditional disciplines. It is developments in polymer science and material science that lead progress in areas that cross traditional boundaries, such as microlithography. This document provides the exact definitions of a selection of unfamiliar terms that researchers and practitioners from different disciplines might encounter.
Chemical names can be so long that, when a manuscript is printed, they have to be hyphenated/divided at the end of a line. Many names already contain hyphens, but in some cases, using these hyphens as end-of-line divisions can lead to illogical divisions in print, as can also happen when hyphens are added arbitrarily without considering the ‘chemical’ context. The present document provides guidelines for authors of chemical manuscripts, their publishers and editors, on where to divide chemical names at the end of a line, and instructions on how to avoid these names being divided at illogical places. Readability and chemical sense should prevail when authors insert hyphens. The software used to convert electronic manuscripts to print can now be programmed to avoid illogical end-of-line hyphenation and thereby save the author much time and annoyance when proofreading. The Recommendations also allow readers of the printed article to determine which end-of-line hyphens are an integral part of the name and should not be deleted when ‘undividing’ the name. These Recommendations may also prove useful in languages other than English.
These recommendations are a vocabulary of basic radioanalytical terms which are relevant to radioanalysis, nuclear analysis and related techniques. Radioanalytical methods consider all nuclear-related techniques for the characterization of materials where ‘characterization’ refers to compositional (in terms of the identity and quantity of specified elements, nuclides, and their chemical species) and structural (in terms of location, dislocation, etc. of specified elements, nuclides, and their species) analyses, involving nuclear processes (nuclear reactions, nuclear radiations, etc.), nuclear techniques (reactors, accelerators, radiation detectors, etc.), and nuclear effects (hyperfine interactions, etc.). In the present compilation, basic radioanalytical terms are included which are relevant to radioanalysis, nuclear analysis and related techniques.
Nanomaterials with enzyme-like activity, generally referred to as ‘nanozymes’, find myriad potential in various biomedical fields. More importantly, the nanoparticles that can functionally mimic the activity of cellular antioxidant enzymes attract tremendous interest owing to their possible therapeutic candidature in oxidative stress-mediated disorders. Oxidative stress culminating due to excess reactive oxygen species (ROS) level and dysregulated cellular antioxidant machinery is implicated in the development and progression of various pathophysiological disorders such as cancer, diabetes, cardiovascular and neurodegenerative diseases. Moreover, the optimum essentiality of ROS due to its pivotal role in cell signaling evokes the requirement of novel artificial antioxidant enzymes that can circumvent the detrimental effects of enhanced ROS levels without perturbing the basal redox status of cells. In recent years, the fast emanating artificial enzymes, i.e. nanozymes with antioxidant enzyme-like activity, has made tremendous progress with their broad applications in therapeutics, diagnostic medicine, bio-sensing, and immunoassay. Among various antioxidant nanoparticles reported till-date, the metal oxide nanozymes have emerged as the most efficient and successful candidates in mimicking the activity of first-line defense antioxidant enzymes, i.e. superoxide dismutase, catalase, and glutathione peroxidase. This review intends to exclusively highlight the development of representative metal oxide-based antioxidant nanozymes capable of maintaining the cellular redox homeostasis and their potential therapeutic significance.
Risks of a false decision on conformity of the chemical composition of a multicomponent material or object due to measurement uncertainty are defined using the Bayesian approach. Even if the conformity assessment for each particular component of a material is successful, the total probability of a false decision (total consumer’s risk or producer’s risk) concerning the material as a whole might still be significant. This is related to the specific batch, lot, sample, environmental compartment, or other item of material or object (specific consumer’s and producer’s risks), or to a population of these items (global consumer’s and producer’s risks). A model of the total probability of such false decisions for cases of independent actual (‘true’) concentrations or contents of the components and the corresponding measurement results is formulated based on the law of total probability. It is shown that the total risk can be evaluated as a combination of the particular risks in the conformity assessment of components of the item. For a more complicated task, i.e. for a larger number of components under control, the total risk is greater. When the actual values of the components’ concentrations or contents, as well as the measurement results, are correlated, they are modelled by multivariate distributions. Then, a total global risk of a false decision on the material conformity is evaluated by the calculation of integrals of corresponding joint probability density function. A total specific risk can be evaluated as the joint posterior cumulative function of actual property values of a specific item lying outside the multivariate specification (tolerance) domain when the vector of measured values obtained for the item is inside this domain. The effect of correlation on the risk is not easily predictable. Examples of the evaluation of risks are provided for conformity assessment of denatured alcohols, total suspended particulate matter in ambient air, a cold/flu medication, and a PtRh alloy.