bluuebunny/crossref_metadata_2025 huggingface dataset:
Association of a Positive Drug Screening for Cannabis With Mortality and Hospital Visits Among Veterans Affairs Enrollees Prescribed Opioids
Authors: Keyhani Salomeh , Leonard Samuel , Byers Amy L. , Zaman Tauheed , Krebs Erin , Austin Peter C. , Moss-Vazquez Tristan , Austin Charles , Sandbrink Friedhelm , Bravata Dawn M.
Published: December 2022

Importance

Cannabis has been proposed as a therapeutic with potential opioid-sparing properties in chronic pain, and its use could theoretically be associated with decreased amounts of opioids used and decreased risk of mortality among individuals prescribed opioids.

Objective

To examine the risks associated with cannabis use among adults prescribed opioid analgesic medications.

Design, Setting, and Participants

This cohort study was conducted among individuals aged 18 years and older who had urine drug screening in 2014 to 2019 and received any prescription opioid in the prior 90 days or long-term opioid therapy (LTOT), defined as more than 84 days of the prior 90 days, through the Veterans Affairs health system. Data were analyzed from November 2020 through March 2022.

Exposures

Biologically verified cannabis use from a urine drug screen.

Main Outcomes and Measures

The main outcomes were 90-day and 180-day all-cause mortality. A composite outcome of all-cause emergency department (ED) visits, all-cause hospitalization, or all-cause mortality was a secondary outcome. Weights based on the propensity score were used to reduce confounding, and hazard ratios [HRs] were estimated using Cox proportional hazards regression models. Analyses were conducted among the overall sample of patients who received any prescription opioid in the prior 90 days and were repeated among those who received LTOT. Analyses were repeated among adults aged 65 years and older.

Results

Among 297 620 adults treated with opioids, 30 514 individuals used cannabis (mean [SE] age, 57.8 [10.5] years; 28 784 [94.3%] men) and 267 106 adults did not (mean [SE] age, 62.3 [12.3] years; P < .001; 247 684 [92.7%] men; P < .001). Among all patients, cannabis use was not associated with increased all-cause mortality at 90 days (HR, 1.07; 95% CI, 0.92-1.22) or 180 days (HR, 1.00; 95% CI, 0.90-1.10) but was associated with an increased hazard of the composite outcome at 90 days (HR, 1.05; 95% CI, 1.01-1.07) and 180 days (HR, 1.04; 95% CI, 1.01-1.06). Among 181 096 adults receiving LTOT, cannabis use was not associated with increased risk of all-cause mortality at 90 or 180 days but was associated with an increased hazard of the composite outcome at 90 days (HR, 1.05; 95% CI, 1.02-1.09) and 180 days (HR, 1.05; 95% CI, 1.02-1.09). Among 77 791 adults aged 65 years and older receiving LTOT, cannabis use was associated with increased 90-day mortality (HR, 1.55; 95% CI, 1.17-2.04).

Conclusions and Relevance

This study found that cannabis use among adults receiving opioid analgesic medications was not associated with any change in mortality risk but was associated with a small increased risk of adverse outcomes and that short-term risks were higher among older adults receiving LTOT.
Outbreak of SARS-CoV-2 Omicron Infection in a Centralized Quarantine Location in Hangzhou, China
Authors: Jia Hexiang , Zheng Yongtao , Jia Yuxin , Jin Chenyang , Wang Yingjian , Zhuang Jiaqin , Ge Yang
Published: December 2022

This cohort study assesses whether transmission of COVID-19 occurred among individuals staying on different floors at a hotel used as a centralized quarantine location in Hangzhou, China.
Effectiveness of Fecal Microbiota Transplantation for Weight Loss in Patients With Obesity Undergoing Bariatric Surgery
Authors: Lahtinen Perttu , Juuti Anne , Luostarinen Markku , Niskanen Leo , Liukkonen Tarja , Tillonen Jyrki , Kössi Jyrki , Ilvesmäki Vesa , Viljakka Mikko , Satokari Reetta , Arkkila Perttu
Published: December 2022

Importance

Severe obesity is a major health concern. However, a few patients remain resistant to bariatric surgery and other treatments. Animal studies suggest that weight may be altered by fecal microbiota transplantation (FMT) from a lean donor.

Objective

To determine whether FMT from a lean donor reduces body weight and further improves the results of bariatric surgery.

Design, Setting, and Participants

This double-blinded, placebo-controlled, multicenter, randomized clinical trial was conducted in 2018 to 2021 among adult individuals with severe obesity treated at 2 bariatric surgery centers in Finland and included 18 months of follow-up. Patients eligible for bariatric surgery were recruited for the study. Data were analyzed from March 2021 to May 2022.

Interventions

FMT from a lean donor or from the patient (autologous placebo) was administered by gastroscopy into the duodenum. Bariatric surgery was performed 6 months after the baseline intervention using laparoscopic Roux-en-Y gastric bypass (LRYGB) or laparoscopic sleeve gastrectomy (LSG)

Main Outcomes and Measures

The main outcome was weight reduction measured as the percentage of total weight loss (TWL).

Results

Forty-one patients were recruited to participate in the study and were included in the final analysis (29 women [71.1%]; mean [SD] age, 48.7 [8.7] years; mean [SD] body mass index, 42.5 [6.0]). A total of 21 patients received FMT from a lean donor, and 20 received an autologous placebo. Six months after FMT, 34 patients underwent LRYGB and 4 underwent LSG. Thirty-four patients (82.9%) attended the last visit 18 months after the baseline visit. The percentage of TWL at 6 months was 4.8% (95% CI, 2.7% to 7.0%; P < .001) in the FMT group and 4.6% (95% CI, 1.5% to 7.6%; P = .006) in the placebo group, but no difference was observed between the groups. At 18 months from the baseline (ie, 12 months after surgery), the percentage of TWL was 25.3% (95% CI, 19.5 to 31.1; P < .001) in the FMT group and 25.2% (95% CI, 20.2 to 30.3; P < .001) in the placebo group; however, no difference was observed between the groups.

Conclusions and Relevance

FMT did not affect presurgical and postsurgical weight loss. Further studies are needed to elucidate the possible role of FMT in obesity.

Trial Registration

ClinicalTrials.gov Identifier: NCT03391817
Bases and Base Catalysis – Industrial
Authors: Davis Robert J.
Published: December 2022

Strong solid bases are effective catalysts for a wide range of organic transformations such as condensation, double‐bond shift, alkylation (and alkenylation), and etherification. They also catalyze important chemical reactions that involve reagents containing heteroatoms like nitrogen, sulfur, and iodine, all of which adversely interact with solid acids. Moreover, acid–base bifunctional catalysts are used or reactions such as dehydration and hydrogenation. The focus of this article is on industrial processes that utilize solid base catalysts in the production of chemicals.
Bioorganic Catalysts and Catalysis
Authors: Pannuri Sachin , DiSanto Rocco , Kamat Sanjay
Published: December 2022

Bioorganic catalysis is emerging as a powerful tool to complement traditional catalytic reactions in organic synthesis. A wide range of reactions can be catalyzed using biocatalysts, and this article attempts to introduce the reader to the variety of reactions that have been demonstrated. Although these reactions are possible in the laboratory, the challenge is to make them economically feasible on an industrial scale. Each biotransformation process has some unique obstacles to overcome before it is translated from the laboratory to commercial scale, and some of these problems are discussed. Biocatalytic properties are amenable to dramatic modification using genetic and solvent engineering, setting them apart from traditional catalysts. Many biocatalytic processes are being run on a commercial scale and one such reaction utilizing a transaminase is presented as a case study.
Catalyst Deactivation/Regeneration
Authors: Bartholomew Calvin
Published: December 2022

This article focuses on the causes, mechanisms, prevention, modeling, and treatment (experimental and theoretical) of deactivation. The causes of deactivation are basically of three kinds: chemical, mechanical, and thermal. The five intrinsic mechanisms of catalyst decay, (1) poisoning, (2) fouling, (3) thermal degradation, (4) chemical degradation, and (5) mechanical failure, vary in their reversibility and rates of occurrence. Poisoning and thermal degradation are generally slow, irreversible processes while fouling with coke and carbon is generally rapid and reversible by regeneration with O2or H2. Catalyst deactivation is more easily prevented than cured. Poisoning by impurities can be prevented through careful purification of reactants. Carbon deposition and coking can be prevented by minimizing the formation of carbon or coke precursors through gasification, careful design of catalysts and process conditions and by controlling reaction conditions to minimize effects of carbon and coke formation on activity. Sintering is best avoided by minimizing and controlling the temperature of reaction. Regeneration of deactivated catalysts is possible for many catalytic processes and is widely practiced. Modeling and experimental assessment of deactivation processes are useful in providing (1) accelerated simulations of industrial processes, (2) predictive insights into effects of changing process variables on activity, selectivity, and life, (3) estimates of kinetic parameters needed for design and modeling, (4) estimates of size and cost for scale‐up of a process, and (5) a better understanding of the basic decay mechanisms. Accordingly, there are important economic benefits that can be derived by from investments in these activities.
Catalysts for Fuel Cells – Industrial
Authors: Williams Keith R. , McNicol Brian D.
Published: December 2022

A fuel cell is a primary voltaic cell that directly converts the chemical energy of a fuel into electricity. Not being a heat engine its efficiency is not subject to the Carnot limitation and in suitable circumstances very high efficiencies can be attained, although progress has been limited by a number of constraints.

In this article low temperature fuel cells operating with acid and alkaline electrolytes are described as well as high temperature cells with both fused carbonate and solid oxide electrolytes. In all cases catalysis of the reactions at both fuel and oxygen (air) electrodes is crucial to satisfactory performance.
Clays and Other Layered Materials
Authors: Szostak Rosemarie
Published: December 2022

Clays are layered silicate‐based materials that are used as binders, supports, and catalysts. The aluminosilicate compositions exhibit Brønsted acidity, when the counterions are replaced with protons, that fall between amorphous aluminosilicates and zeolites. These clays are versatile acid catalysts for organic reactions in the gas as well as solution phase. Propping up the spacing between the layers increases the surface area and allows improved access to the acid sites. Both the pillars and the layers of these clays can be unstable at high temperature and high steam content and are not feasible substitutes for the zeolite cracking catalysts under the severe conditions needed for petroleum refining. In solution phase, the use of the acid clays can substantially impact the organic reaction mechanism. It is in the regime of organic synthesis that clays as solid catalysts have found utility.
Cofactors in Biocatalysis
Authors: Panza Janice L.
Published: December 2022

Some enzymes require the participation of chemical compounds called cofactors for biocatalysis. A cofactor is either a simple inorganic metal ion or a complex organic molecule called a coenzyme. Common metal ion cofactors are copper, iron, and zinc. Metal ions aid the enzyme either structurally or catalytically. Coenzymes have physiocochemical properties not found in the enzyme, which are necessary to assist the enzyme to catalyze a reaction. The function of a coenzyme is to accept the transfer of a specific functional group from a substrate in order for the substrate to be converted to the product. After coenzymes participate in a reaction, they may be regenerated back to their original form. Coenzymes are classified according to whether they are self‐regenerating, regenerated by oxidation using molecular oxygen, or regenerated using an appropriate substrate other than O
2
for regeneration. Furthermore, several coenzymes have been immobilized onto solid supports for economical biocatalysis.
Dehalogenation – Industrial
Authors: Allen David , Mullins C. B. , Meyer Randall J.
Published: December 2022

Catalytic dehalogenation is used in the treatment of halogenated organic waste streams and in partial hydrogenation of halogenated organics. Waste treatment applications are primarily directed at complete dehalogenation of chlorinated wastes, including waste solvents and heavy ends from chlorinated chemical manufacturing; these processes generally employ transition metal catalysts. Partial hydrogenation applications are predominantly in the reprocessing of chlorofluorocarbons (CFCs) and in the synthesis of CFC replacements; these processes employ noble metal catalysts. Many of these processes are still in the developmental stages, and relatively few industrial installations are in place. Nevertheless, these processes are likely to become increasingly important as costs associated with managing waste materials escalate.
Dehydrogenation – Biological
Authors: Yang Fangxiao
Published: December 2022

Dehydrogenation plays a very important role in both nature and human civilization. In chemical industry, dehydrogenations are used to produce propene, butene, butadiene, isobutene, and isopropene from the corresponding alkanes. In living organisms (both animals and plants), respiration is actually a process of oxidation wherein some steps involve dehydrogenation. Almost all dehydrogenation reactions require a catalyst. Catalysts for dehydrogenation can be classified into two main categories: conventional catalysts (including inorganic and organic) and enzymes. This article focuses on the application of biological catalysts in dehydrogenation and oxidation reactions occurring in nature. Biological dehydrogenation is illustrated from two aspects: chemistry of biocatalytic dehydrogenation and biocatalysts of dehydrogenation. Biological dehydrogenation reactions usually occur at very mild conditions and have very high selectivity. The catalysts for these processes are usually enzymes (or cells producing these enzymes). Enzymes having dehydrogenation capacities are usually dehydrogenases, oxidases, etc., and most of them need a coenzyme or a cofactor to work with them.
Distannylation
Authors: Broene Richard D. , Baker R. Tom
Published: December 2022

The catalyzed addition of distannanes, silylstannanes, borastannes, and borasilanes to unsaturated organic molecules is reviewed, with an emphasis on the scope of substrates and catalysts and synthetically useful transformations. Reactions include additions to alkenes, allenes, alkynes as well as to molecules containing combinations of these functional groups. Examples for further transformation of the resulting organic products are given. Issues of regioselectivity and diastereoselectivty in the additions are discussed in the context of catalyst choice as are differences seen in the addition of various element–element bonds to given substrates.
Epoxidation – Homogeneous
Authors: Merlau Melissa L. , Borg‐Breen Caryn C. , Nguyen SonBinh T.
Published: December 2022

In this article, catalyst systems for homogeneous epoxidation are reviewed with an emphasis on reaction elements that are of foremost interest to synthetic chemists: catalyst systems, substrate scope, and selectivity. General mechanisms and reaction conditions for each catalyst system are discussed followed by more detailed summaries of the epoxidation of specific classes of olefins: unfunctionalized terminal olefins, cis‐disubstituted, trans‐disubstituted, tri‐ and tetrasubstituted olefins, functionalized olefins including allylic alcohols, and electron‐deficient olefins. Major classes of catalysts addressed are early transition metal‐peroxo forming catalysts (inclusive of the Sharpless titanium tartrate catalyst for the asymmetric epoxidation of allylic alcohols and MTO), metal‐oxo forming catalysts (such as metalloporphyrin and Jacobsen/Katsuki salen catalysts), dioxirane and oxaziridine catalysts, Lewis acid and lanthanide catalysts, phase‐transfer and polyamino acid catalysts, and finally sulfur ylide catalysts for the formation of epoxides from aldehydes.

Dedicated to Professor K. Barry Sharpless on the occasion of his 60th birthday.
Epoxidation – Industrial
Authors: Kobe J. M. , Evans W. E. , June R. L. , Lemanski M. F.
Published: December 2022

The direct oxidation of ethylene to ethylene oxide (EO) is the largest commercial epoxidation process. The original chlorohydrin‐based plants were made obsolete by air‐based processes. These in turn have almost entirely been replaced by oxygen‐based processes, which are gas‐phase, low conversion, and utilize a recycle loop. The primary engineering issues in an EO process are heat removal from the reactor and the removal of EO and carbon dioxide from the recycle stream. All EO production now occurs over silver‐based catalysts at temperatures between 220 and 300°C. Depending on process conditions and the catalyst employed, selectivities to EO in commercial processes range from less than 70% to greater than 90%. The only other epoxide manufactured on an industrial scale is propylene oxide (PO). Some companies still produce PO using a chlorohydrin‐based process, which is liquid‐phase, non catalytic, and is practical only for those companies that also produce chlorinated compounds. The second commercial route is a hydroperoxide‐based process. In addition to PO, these processes also produce a coproduct, usually either styrene or methyl
tert
‐butyl ether. The hydroperoxide‐based processes are liquid‐phase, are carried out between 100 and 130°C, and use either homogeneous Mo‐based catalysts or heterogeneous Ti‐based catalysts. Propylene‐based selectivities for the chlorohydrin process exceed 90%, while selectivities for the hydroperoxide‐based process can exceed 98%.
Heme Proteins and Model Systems
Authors: Ozaki Shin‐ichi , Watanabe Yoshihito
Published: December 2022

This article describes mechanistic aspects of the active intermediate formation and a variety of reactions catalyzed by peroxidases. In two‐electron oxidations, a ferryl porphyrin π‐cation radical intermediate (the so‐called compound I) is generally involved, while one‐electron oxidation of substrates such as amines and phenols could proceed even when the active species is compound II, which is one‐electron reduced form of compound I (FeIVO species). Many efforts have been made to utilize peroxidases as two‐electron oxidants rather than one‐electron oxidation cataysts. Site‐directed mutagenesis of peroxidases and myoglobin to construct highly efficient and enantioselective oxidation catalysts is an example of these efforts. In addition, random mutagenesis coupled with screening is a way of directed evolution to find biocatalysts suitable for desired oxidations. Chemical modification of amino acid residues and the heme prosthetic group is also an important strategy for the construction of enzymatic activities that are very different from those of the native enzymatic reactions.
Hydroamination – Homogeneous
Authors: Müller T. E.
Published: December 2022

The principal systems that have been developed as homogeneous catalysts for the direct arnination of nonactivated alkenes and alkynes (hydroamination) are discussed. The focus is on the different ways of activating the reactants and the challenges encountered during the development of the catalyst systems. The basic reaction mechanisms and the most recent applications of hydroamination reactions in organic syntheses are discussed.
Hydrodesulfurization – Heterogeneous
Authors: Vanrysselberghe V. , Froment G. F.
Published: December 2022

The article deals with hydrodesulfurization and hydrodearomatization of oil fractions.

In the first part the composition of hydrotreatment catalysts, their preparation, activation, and deactivation, and the nature of their active phase and its interaction with the reaction mixture are reviewed.

In the second part the article concentrates on various levels of kinetic modeling, extending from lumped first‐ or second‐order models to sets of kinetic equations based on detailed reaction schemes of the process, distinguishing between the hydrogenolysis and the hydrogenation routes. A methodology for the kinetic modeling of the hydrodesulfurization of oil fractions is presented, in which the sulfur components are considered individually, instead of lumped. The rate equations of substituted S‐containing components of the thiophenic families are related to those of the heads of the families or “parent” molecules through “structural contirbutions” entering into the kinetic and adsorption coefficients of the Hougen–Watson‐type kinetic equations. These structural contributions are derived from experimental work on, eg, thiophenic model components such as (substituted) (di)benzothiophene. By way of example, the approach is applied to a complex mixture such as light cycle oil fractions and the extension to other fractions is outlined.

A one‐dimensional heterogeneous plug‐flow model is applied to the simulation of an adiabatic reactor for diesel hydrodesulfurization and hydrodearomatization. The kinetic equations of the S‐removal are of the Hougen–Watson type and are based upon the structural contribution approach. The feasibility of achieving the drastic reduction in S‐levels set by the new legislations is discussed.

Finally, flow schemes of industrial hydrotreatment processes are described.
Immobilization – Homogeneous
Authors: Tóth Imre , van Geem Paul
Published: December 2022

Supported or immobilized homogeneous catalysts combine the merit of easy separation of a heterogeneous catalyst with the uniform active sites and high performance of the homogeneous analogue. In ideal cases, these hybrid catalysts can provide higher selectivity/activity than that of the homogeneous counterparts because of synergetic effects with the support material or reluctance of the supported metal complexes to undergo undesirable dimerization or cluster formation. The immobilization of homogeneous catalyst to a chosen inorganic or polymer support can be achieved with various methods, which are reviewed and evaluated in this article. Thus, entries are made for physically attached catalysts, which are obtained by adsorbing metal complexes or their solutions (supported liquid‐phase) to solids, and by encapsulating or by entangling homogeneous catalysts to microporous solids or in polymers, respectively. Chemically attached catalysts are classified by the nature of binding to the support, ie, covalent or ionic binding of metal centers and/or ligands to supports. Furthermore, support materials and site isolation are also addressed in the article. Although the type of reaction with immobilized catalysts was not the basis for the overview, numerous examples are given for specific applications.
Metal Carbonyls
Authors: Sukcharoenphon Kengkaj , Hoff Carl
Published: December 2022

The nature of the bond between metal complexes and carbon monoxide is discussed and an introduction to the literature of this topic is provided. The broad scope of CO as a ligand in organometallic chemistry is compared to the role of H2O in coordination chemistry. A brief history of metal carbonyl chemistry is followed by a discussion of the properties of carbon monoxide as a molecule, and how these properties change on coordination to a metal. The preparation, reactions, and importance of metal carbonyls to catalysis are also discussed.
Molecular Modeling of Heterogeneous Catalytic Reactivity
Authors: van Santen R. A. , Neurock M.
Published: December 2022

The approach to model heterogeneous catalysis based on mechanistic molecular insights derived from quantum chemical methods is explained by addressing key fundamental issues that control catalysis and using many examples. The Sabatier principle is used as the leading concept to understood and predict catalyst activity—catalyst composition relationships. The reaction energy diagram approach is used to help assess rate‐limiting steps and selectivity principles for catalytic reaction. In order to predict catalytic kinetics, quantum chemical mechanistic information has to be complemented with information on the effects of reaction environment on the elementary steps. This includes changes due to interactions between adsorbed species as well as adsorbate‐induced surface reconstruction.

QM results can subsequently be used along with transition state reaction theory to predict elementary rate constants for elementary steps that make up the overall catalytic cycle. This information along with data on the effects of the reaction environment provide the input for dynamic Monte Carlo methods that can ultimately simulate overall catalytic kinetics. This approach can be used to follow both catalytic activity as well as selectivity. Periodic trends in surface reactivity are discussed for transition metal oxide, reducible oxide, hydrodesulfurization, and zeolite catalysis.
Multimetallic Catalysts – Homogeneous
Authors: Gueorguieva Petia G. , Stanley George G.
Published: December 2022

A review of some of the best examples of two or more metal centers cooperating in a variety of homogeneous catalytic reactions is presented. Catalytic reactions covered include hydroformylation, cyclopropanation and diazoalkane cyclization, hydrogenation, oxidations, asymmetric epoxide ring openings, asymmetric aldol, thietane ring‐opening cyclizations, and tandem catalysis. Many enzymes have long been recognized to make use of two or more metal centers in activating substrates for further reaction. A few representative enzymatic systems are presented as part of the introductory material. A number of examples of multimetallic fragmentations to reactive monometallic catalyst species, a serious ongoing problem, are also presented and discussed.
Oxidative Carbonylation – Heterogeneous
Authors: Rivetti Franco , Delledonne Daniele
Published: December 2022

Oxidative carbonylation of alcohols is mainly exploited for the production of carbonate and oxalate esters. Most important is the manufacture of dimethyl carbonate (DMC), an intermediate in the non‐phosgene route to aromatic polycarbonates. Two processes are industrially adopted. In the one‐step EniChem process, DMC is produced by copper chloride catalyzed, liquid‐phase methanol oxy‐carbonylation. In the two‐step Ube process, methanol is first converted to methyl nitrite, which in turn undergoes palladium‐catalyzed, gas‐phase carbonylation to DMC. Further potentially important industrial applications of oxidative carbonylation relate to the production of diphenyl carbonate, carbamate, and acrylate esters.
Photocatalysis – Heterogeneous
Authors: Domen Kazunari
Published: December 2022

The definition and basic principle as well as the reaction mechanism of heterogeneous photocatalysis are described in detail. Several typical examples, such as organic synthesis, oxidation, reduction, and mineralization, are also cited. Especially, TiO2photocatalysis is mentioned in detail because it is the most extensively used photocatalyst for various kinds of reactions. Photocatalytic decomposition of water is also described.
Transport Effects – Heterogeneous
Authors: Schweich D.
Published: December 2022

The competition between the catalytic reaction and mass and heat transfer processes is presented with two objective: interpreting laboratory data and predicting full‐scale reactor performance. Internal and external mass transfer at the catalyst scale and gas–liquid resistance are first dealt with. Then heat transfer and possible ignition and extinction phenomena are reviewed. The consequence of these resistances are related to the operating conditions and reactor technology (batch/continuous, fixed bed, suspended catalyst, monolith). Simple experiments and more or less sophisticated calculations are provided to discriminate among the predominant resistances and to select appropriate experimental conditions.
Tungsten Enzymes and Models
Authors: Roy Roopali , Adams Michael W. W.
Published: December 2022

The chemical properties of the metals tungsten (W) and molybdenum (Mo) are very similar. Mo plays a key role in biological systems and molybdoenzymes are ubiquitous; however, it is only recently that a biological role for W has been established, and so far only in a few microorganisms. Three different types of tungstoenzyme have been purified and these are abbreviated as AOR, F(M)DH, and AH. Members of the AOR group catalyze the reversible oxidation of aldehydes and include three ferredoxin‐dependent oxidoreductases that oxidize various aldehydes (AOR), formaldehyde (FOR), and glyceraldehyde‐3‐phosphate (GAPOR). The F(M)DH group utilizes carbon dioxide as a substrate and is represented by formate dehydrogenase (FDH) and formyl methanofuran dehydrogenase (FMDH), while acetylene hydratase (AH) is the sole member of the AH class. These tungstoenzymes catalyze reduction–oxidation reactions of very low potential (less than ‐420 mV) except one (AH), which catalyzes a hydration reaction. All of these enzymes contain a single W atom in the +IV, +V, or +VI redox state that is coordinated to the protein via an organic moiety known as a pterin. The pterin is similar to that found in molybdoenzymes. The crystal structure of the first W‐containing (or pterin‐containing) enzyme, that of AOR fromPyrococcus furiosus, revealed a catalytic site with one W atom coordinated of four sulfur atoms from two pterin molecules. The two pterins are also bridged by a magnesium ion. the catalytic and spectroscopic propeties of tungstoenzymes and synthetic analogues of their active sites are discussed, together with the factors that might contribute to the biochemical utilization of W rather than Mo.
Nitrogen Oxides Removal with Supported Metals and Oxides
Authors: Burch R. , Breen J. P. , Meunier F. C.
Published: December 2022

The literature on nontransition/transition metal oxides and platinum group metal (PGM) catalysts for NO

x

reduction by hydrocarbons under lean‐burn conditions is critically evaluated. Alumina and silver‐promoted alumina catalysts are described in detail with respect to the various reaction mechanisms that have been proposed. The effects of the nature of the reducing agent, and the preparation and structure of the catalysts are also discussed and rationalized for several other systems. For these metal oxides strongly adsorbed species such as nitrates/nitrites and acetates are thought to be key intermediates in the formation of various reduced and oxidized species of nitrogen, whose reaction leads eventually to the formation of molecular nitrogen. For the PGMs a number of different mechanisms have been proposed in the literature and these are critically assessed. It is concluded that although there is indirect evidence for various reaction intermediates it is difficult to confirm that any of these are involved in a critical mechanistic step. A simple mechanism that involves the dissociation of NO on a reduced metal surface to give N (ads) and O (ads), with subsequent desorption of N
2
and N
2
O and removal of O (ads) by the reductant, can explain many of the results with the PGM catalysts.
Bark
Authors: Lev‐Yadun Simcha
Published: December 2022

Bark comprises all the tissues outside the vascular cambium of seed plants. Most of the bark of woody plants develops from three secondary meristems: the vascular cambium that gives rise to the secondary phloem, the phellogen that gives rise to the cork and the dilatation meristem that produces parenchyma cells to prevent cracking when the axis increases in diameter. Some of the outer bark in young organs is made of primary tissues originating in the procambium, the ground meristem and the protoderm. Bark tissues have a critical role in defending plants from pathogens and herbivores through their physical and chemical properties. They also defend from environmental hazards such as sun irradiation, desiccation, wind, flooding, hail, snow and when the cork is thick, also from fire. The bark has a critical role in storage and transport of organic molecules and water, and in many plants contributes to photosynthesis. Many of the various defensive and toxic substances found in barks are used by humans as medicines, spices and for various industries. Gene exploring in barks that became more common in recent years is expected to result in identifying many beneficial molecules for agriculture, medicine, food and the industry.

Key Concepts

Bark comprises all the tissues outside the vascular cambium of a vascular plant.

The majority of the bark of woody plants develops from three meristems: the vascular cambium that gives rise to the secondary phloem, the phellogen that gives rise to the cork and dilatation meristem that produces parenchyma cells to avoid cracking when the axis increases in diameter.

The formation of the bark is regulated by several plant hormones, mainly auxin, ethylene, jasmonates and gibberellins.

After wounding, the induced rise in the hormones ethylene and jasmonic acid induces the formation of defensive (wound) cork and traumatic resin or gum ducts in many species.

The bark functions in storage, transport and defence from herbivores, pathogens and environmental stresses including sun irradiation and fire.

Many bark products (e.g. fibres, food, medicine, resins, rubber, pigments, poisons, cork) have been used by humans since antiquity.

Defence from herbivores included prickles, thorns, toxins, mechanical hardness, aposematic (warning) colouration, plant camouflage and undermining herbivore camouflage.
Political Mediation Model
Authors: Amenta Edwin
Published: December 2022

The political mediation model is a theory seeking to explain the influence of social movements in politics, mainly over policy. This theory builds on ideas in political science and sociology and begins with the political institutions, processes, and outcomes movements seek to influence. It recognizes that movement actors typically lack power and have no direct control over political outcomes of interest and thus influence them only occasionally. The main version of the model focuses on combinations of movement organizational forms and strategies and political contexts that are hypothesized to produce impacts for movements. There is considerable empirical support for the model. Versions of the mediation model have been applied also to the influence of movements over other institutions.
Protest Event Research
Authors: Soule Sarah A.
Published: December 2022

Social movement research has developed a rich tradition of using data on collective action and protest events (hereafter “events”) that are culled from various sources (e.g. news reports, police records). Event data have been used by scholars to answer questions about the causes of ethnic violence and collective action, citizen protest of various types, and strikes. Event data has also been used to analyze the outcomes of social movements, including the policing of protest. A major benefit of these types of data is that it facilitates both comparative and historical research, while also allowing for quantitative research on social movements. Additionally, there is often no better alternative.
Social Movements
Authors: Snow David A.
Published: December 2022

Social movements are important agents of social, political, and cultural change, dating back from the present to at least the far‐reaching empires of the Greco‐Roman world and the various rebellions and religious movements spawned during that era. This entry sketches a general overview of social movements, accenting their role as carriers of social change, providing a working conceptualization, elaborating the varieties or types of social movements, and identifying the focal issues and questions that animate most research on social movements.
Solidarity and Movements
Authors: Benford Robert D.
Published: December 2022

Participation in a social movement often occurs out of a sense of solidarity. People become movement
adherents
when they feel they share with others a sense of enthusiasm and devotion for the group. Herbert Blumer referred to such shared feelings as esprit de corps. From his vantage point, esprit de corps has two dimensions: a body of confederates that are seen as a collectivity and a spirit that entails feelings of close identification with that group. The
corpus
feature of solidarity calls attention to the body of actors that comprise a group. Some organizations, such as the military, police, athletic teams, marching bands, and so on, project an image of an actual corporal entity by having members wear uniforms and engaging in coordinated drills such as marching. In the present context, social movement organizations employ banners, placards, T‐shirts, and bumper stickers to mark their membership boundaries. The
spiritus
feature of solidarity pertains to the feelings of belonging to a collectivity.
Survey Research
Authors: Klandermans Bert
Published: December 2022

Survey research is a frequently employed research design in social movement studies. As there are quite a few excellent source books for researchers who want to apply survey methodology, I will restrict myself in this entry to the specificities of survey research in the context of social movement studies.
Friedan, Betty
Authors: Threlfall Monica
Published: December 2022

Betty Friedan (1921–2006) is widely considered to be the founder of modern feminism, as the “second wave” of feminism in Europe and later in the rest of the world sees its roots as emerging from the USA from the 1960s onwards. Second‐wave feminism took off in Europe and later sparked off new “first waves” in many other countries until it became a worldwide movement. It is not surprising that Friedan sometimes claimed to have changed the course of human history, granting the individual a key role in forging change, an ongoing debate. Certainly Betty, born soon after World War I, was well in advance of her era's thinking when she undertook her original project to examine empirically, not conceptually, whether housewives were happy with their lot. But her first book, containing the empirical bombshell of women's pervasive discontent, was also timely as it was published in the same year as the official Kennedy Commission on the Status of Women's report “American Women,” which also questioned women's exclusion from any nondomestic life. Discrimination against women was on the agenda, and the moment for sex equality had come.
Detergents and Detergency
Authors: Lynn Jesse L. , Nguyen Thu
Published: December 2022

Detergency refers to the removal of unwanted foreign matters from a surface in a liquid bath containing a detergent formulation. A detergent formulation is composed of active ingredients like surfactants and inactive ingredients such as builders, alkalis, antiredeposition agents, enzymes, and hydrotropes. The main active ingredient of the detergent formulation is surfactants that can alter the interfacial effects at the various phase boundaries within the detergent system. Detergent formulations can contain from one to three surfactants. Thus, a typical detergent system consists of a solid object to be cleaned, called the substrate, soil, or dirt to be removed from the substrate surface and a washing liquid bath to be applied to the soiled substrate. Each of these elements in the detergent system can vary widely in properties and composition.

This article describes the role of each element in a detergent system. In addition, cleaning mechanisms and the measurement of detergency power in different types of detergent systems are discussed. These systems include fabric detergency and hard surface cleaning. Although it is impossible to list all the practical detersive systems that might be encountered, a large proportion falls in a small number of classes. This classification disregards surfactant structure and type of substrate (fibrous or hard surface) and is restricted to a consideration of the soil present on the substrate, mechanical action employed, bath ratio, and detergent used. Some of the commonly encountered detersive systems are classified on this basis here.
Pharmaceutical and Cosmetic Use of Lipids
Authors: Hernandez Ernesto M.
Published: December 2022

Fats and oils in general are considered reliable ingredients, excipients or carriers in many pharmaceutical and cosmetic formulations. More recently, biological and functional properties as well as health benefits of many fatty acids and lipid phytochemicals have been studied for their potential applications in health products and disease prevention. This has resulted in the development of new products and applications of these bioactives into more specialized pharmaceutical and cosmetic products such as coadjuvants, skin emolliency agents, and transdermal carriers. New, more specifically targeted applications of lipids in pharma and cosmeceutical fields also include the manufacture of lipid vesicles with entrapped bioactive elements able to partition into the skin layers and deliver drugs and bioactive cosmetics transdermally. Lipids used in pharmaceutical and cosmetics require higher standards of purity and have to fulfill more stringent regulatory specifications. Therefore it is necessary to conduct additional processing steps to remove contaminants and other impurities to trace or non‐detectable levels. In order to make lipids more functional and recover lipid biological actives new processing techniques have to be applied such as molecular distillation, supercritical extraction, and fractionation techniques.
Games and Public Anthropology
Authors: Harper Krista M. , Collins Samuel G. , Durington Matthew , Dumit Joseph , González‐Tennant Edward , Lorenc Marc , Mizer Nicholas J. , Salter Anastasia
Published: December 2022

Multimodal anthropologists are using games and game design as a method for producing ethnographic knowledge collaboratively with research participants and as a genre for communicating anthropological knowledge with varied publics. As a methodological approach and a rhetorical genre, games offer unique affordances in that they highlight the dynamic interplay of structures, systems, rules, and norms on the one hand, and contingency, interaction, and agency, on the other. Games are marked by uncertain outcomes, open‐endedness, and contingency, reflecting Clifford Geertz's observation that “cultural analysis is intrinsically incomplete.” Public anthropology has much to gain from games as an engaging modality for scholarly research, public communication, and pedagogy.
From Representation to Care: Emerging Shifts in Laboratory Studies
Authors: Suzuki Wakana
Published: December 2022

From the 1970s to the early 1990s, the first ethnographic explorations of science—so‐called laboratory studies—started to be written by sociologists, anthropologists, and philosophers. In the 2020s, anthropologists of science and science and technology studies scholars have returned to laboratory studies but with a wider range of topical and analytical interests. Inspired by feminist science and technology studies scholarship, in this latest generation of laboratory studies, some ethnographers have turned their attention to enmeshed relationality—for instance, questions of care, the senses, and ethics in science. This entry tracks this shift from the first to second generation of laboratory studies. Then, it shares insights from the entry author's ethnography of a stem‐cell science laboratory in Japan. In particular, it focuses on the how laboratory members care for cells using onomatopoeia—a specific type of linguistic representation that has not yet received attention within laboratory studies.
Thermally Responsive Fibers for Versatile Thermoactivated Protective Fabrics
Authors: Sun Chuanyue , Luo Jiabei , Yan Shengchang , Li Kerui , Li Yaogang , Wang Hongzhi , Hou Chengyi , Zhang Qinghong
Published: December 2022

Smart textiles with good mechanical adaptability play an important role in personal protection, health monitoring, and aerospace applications. However, most of the reported thermally responsive polymers has long response time and poor processability, comfort, and wearability. Skin‐core structures of thermally responsive fibers with multiple commercial fiber cores and temperature‐responsive hydrogel skins are designed and fabricated, which exhibit rapid mechanical adaptability, good thermohardening, and thermal insulation. This universal method enables tight bonding between various commercial fiber cores and hydrogel skins via specific covalently anchored networks. At room temperature, prepared fibers show softness, flexibility, and skin compatibility similar to those of ordinary fibers. As temperature rises, smart fibers become hard, rigid, and self‐supporting. The modulus of hydrogel skin increases from 304% to 30883%, showing good mechanoadaptability and impact resistance owing to the synergy between hydrophobic interactions and ionic bonding. Moreover, this synergistic effect leads to an increase in heat absorption, and fibers exhibit good thermal insulation, which reduces the contact temperature of the body surface by ≈25 °C under the external temperature of 95 °C, effectively preventing thermal burns. Notably, the active mechanoadaptability of these smart fibers using conductive fibers as cores is demonstrated. This study provides feasibility for fabricating environmentally adaptive intelligent textiles.
Efficient Red Light Emitting Diodes Based on a Zero‐Dimensional Organic Antimony Halide Hybrid
Authors: Liu He , Shonde Tunde Blessed , Gonzalez Fabiola , Olasupo Oluwadara Joshua , Lee Sujin , Luong Derek , Lin Xinsong , Vellore Winfred J.S. Raaj , Lochner Eric , Fatima Iqra , Hanson Kenneth , Ma Biwu
Published: December 2022

Zero‐dimensional (0D) organic metal halide hybrids (OMHHs) have recently emerged as a new class of light emitting materials with exceptional color tunability. While near‐unity photoluminescence quantum efficiencies (PLQEs) are routinely obtained for a large number of 0D OMHHs, it remains challenging to apply them as emitter for electrically driven light emitting diodes (LEDs), largely due to the low conductivity of wide bandgap organic cations. Here, the development of a new OMHH, triphenyl(9‐phenyl‐9H‐carbazol‐3‐yl) phosphonium antimony bromide (TPPcarzSbBr4), as emitter for efficient LEDs, which consists of semiconducting organic cations (TPPcarz+) and light emitting antimony bromide anions (Sb2Br82−), is reported. By replacing one of the phenyl groups in a well‐known tetraphenylphosphonium cation (TPP+) with an electroactive phenylcarbazole group, a semiconducting TPPcarz+ cation is developed for the preparation of red emitting 0D TPPcarzSbBr4 single crystals with a high PLQE of 93.8%. With solution processed TPPcarzSbBr4 thin films (PLQE of 86.1%) as light emitting layer, red LEDs are fabricated to exhibit an external quantum efficiency (EQE) of 5.12%, a peak luminance of 5957 cd m−2, and a current efficiency of 14.2 cd A−1, which are the best values reported to date for electroluminescence devices based on 0D OMHHs.