bluuebunny/crossref_metadata_2025_split huggingface dataset:
Heme Proteins and Model Systems
Authors: Ozaki Shin‐ichi , Watanabe Yoshihito 
Published: December 2022

AbstractThis 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

AbstractThe 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

AbstractThe 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

AbstractSupported 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

AbstractThe 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

AbstractThe 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

AbstractA 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

Abstract
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

AbstractThe 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

Abstract
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

AbstractThe 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

Abstract

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

AbstractBark 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 ConceptsBark 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.
Detergents and Detergency
Authors: Lynn Jesse L. , Nguyen Thu 
Published: December 2022

AbstractDetergency 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

AbstractFats 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.
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

AbstractSmart 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

AbstractZero‐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.
Optimizing Acetylene Sorption through Induced‐fit Transformations in a Chemically Stable Microporous Framework
Authors: Tian Jindou , Chen Qihui , Jiang Feilong , Yuan Daqiang , Hong Maochun 
Published: December 2022

AbstractDeveloping practical storage technologies for acetylene (C2H2) is important but challenging because C2H2is useful but explosive. Here, a novel metal–organic framework (MOF) (FJI‐H36) with adaptive channels was prepared. It can effectively capture C2H2(159.9 cm3 cm−3) at 1 atm and 298 K, possessing a record‐high storage density (561 g L−1) but a very low adsorption enthalpy (28 kJ mol−1) among all the reported MOFs. Structural analyses show that such excellent adsorption performance comes from the synergism of active sites, flexible framework, and matched pores; where the adsorbed‐C2H2can driveFJI‐H36to undergo induced‐fit transformations step by step, including deformation/reconstruction of channels, contraction of pores, and transformation of active sites, finally leading to dense packing of C2H2. Moreover,FJI‐H36has excellent chemical stability and recyclability, and can be prepared on a large scale, enabling it as a practical adsorbent for C2H2. This will provide a useful strategy for developing practical and efficient adsorbents for C2H2storage.