bluuebunny/crossref_metadata_2025_split huggingface dataset:
Oxychlorination – Heterogeneous
Authors: Taârit Younès Ben 
Published: December 2022

Abstract

A brief account of the halogenation of organic compounds to manufacture products of practical use, such as halomethanes, chloroaromatics, chloroaliphatics, and vinyl chlorides, is given as an introduction. The production of chlorine, the chief halogenation agent, starting from HCl, a major by‐product, is also briefly reviewed. The Deacon process, particularly its thermodynamic aspects, is surveyed. The oxychlorination of ethene and methane is then covered in depth. The reaction thermodynamics shows its advantage against the plain Deacon. Most of the operating processes use the favourite Cucl
2
‐based catalyst. The role of alkali chlorides is examined. The formation of the complex salt is thought to provide increased mobility and availability of the active species and a more effective reoxidation, an otherwise slow step. Agglomeration of the active species is also prevented owing to appropriate coordination. The overall kinetics are reviewed. The influence of the support is emphasized with respect to stickiness. The nature of the active sites is examined based on spectroscopic and catalytic performance studies. Finally, mechanistic speculations, in line with well‐established schemes in homogeneous catalysis, are offered and potential zeolite‐based catalysts are suggested.
Radicals in Catalysis – Heterogeneous
Authors: Sojka Zbigniew , Giamello Elio , Cristina Paganini Maria 
Published: December 2022

AbstractSeveral reactions in heterogeneous catalysis take place via radical intermediates. The present article illustrates the typical aspects of the radical chemistry in heterogeneous catalysis that very often differ from those in the radical chemistry in fluid homogeneous phases because of the role of the surface in the generation, stabilization, and transformation of radical species. The various routes for the formation of radicals on a surface will be taken into consideration including electron transfer, atom transfer, and molecular dissociation. A particular emphasis is given to the electron magnetic resonance techniques, which have the paramount role in the detection and also in the description of the radical species because of their high sensitivity that allows the detection of low abundance species. In the final part of the article some selected examples of heterogeneous catalytic processes involving radical steps will be discussed with particular emphasis on catalytic oxidation on metal oxides.
Selective Oxidation – Homogeneous
Authors: Sheldon R. A. , ten Brink G. J. , Arends I. W. C. E. 
Published: December 2022

AbstractIn the manufacture of fine chemicals there is a considerable pressure to replace traditional oxidation techniques, using stoichiometric quantities of high valent metal salts, with cleaner, catalytic alternatives. This article focuses on homogeneous catalysis of liquid‐phase oxidations employing dioxygen, hydrogen peroxide, or alkyl hydroperoxides as the primary oxidant. Where relevant, heterogeneous equivalents are also discussed. Following a general introduction, which includes a discussion of the different reaction mechanisms and of the design of ligands for oxidation catalysts, the different classes of substrates are discussed. These are alkenes (epoxidation, vicinal dihydroxylation, oxidative cleavage, ketonization, and allylic oxidation), alkanes and alkyl aromatics (side‐chain versus aromatic‐ring oxidation), oxygen‐containing compounds (alcohols, diols, aldehydes, ketones, phenols, and ethers), amines, and sulfur‐containing compounds. A separate section is devoted to asymmetric catalysis (epoxidation and dihydroxylation of olefins, sulfoxidation, and Baeyer–Villiger oxidation).
Selective Oxidation – Biological
Authors: Dunford H. Brian 
Published: December 2022

AbstractThe oxiding properties of metalloenzymes are reviewed. The reactive oxygen‐containing species formed by successive one‐electron reductions of dioxygen to water are discussed. Emphasis is on iron‐containing enzymes and in particular heme enzymes. Details of peroxidase, catalase, cytochrome P450, nitric oxide synthase, guanylate cyclase, and cytochrome c oxidase reactions are summarized. A brief sojourn looks at the role of sulfur, which converts iron‐containing enzymes from oxidation catalysts to reduction catalysts. An example is nitrogenase where iron–sulfur clusters contribute to the molybdenum‐catalyzed reduction of dinitrogen to ammonia. Copper enzymes and in particular copper‐zinc superoxide dismutase are also examined.
Selenium in Biocatalysis
Authors: Lacourciere Gerard M. 
Published: December 2022

AbstractSelenium has long been considered a toxic element. Its toxicity has been attributed to its incorporation into the amino acids cysteine and methionine in place of sulfur. This incorporation results in an alteration in the structure of proteins which directly affects its function. Today it is well documented that at low concentrations, selenium is an essential element. The discovery of several prokaryotic and eukaryotic proteins that contain selenium as the amino acid selenocysteine or as an unstable perselenide adduct demonstrated that selenium is directly involved in biocatalysis.
Sulfate Activation
Authors: Moura José J. G. , Bursakov Sergey A. , Gavel Olga , Moura Isabel 
Published: December 2022

AbstractSulfate is an inert molecule that must be chemically activated before it can be involved in biochemical pathways. This article deals with biological sulfate activation via adenylylation. The activation of inorganic sulfate involves the formation of a “high energy” phosphosulfate anhydride bond in adenosine‐5′‐phosphosulfate (APS) and is catalyzed by the enzyme ATP sulfurylase. A consecutive step, catalyzed by APS kinase, produces another form of activated sulfate: 3′‐phosphoadenosine 5′‐phosphosulfate (PAPS). APS and PAPS are used in the formation of the thiol groups of sulfur containing amino acids and their derivatives, as well as specialized sulfur compounds, and also have other diverse functions.
Shape‐Selective Catalysis – Heterogeneous
Authors: Csicsery Sigmund M. , Kiricsi Imre 
Published: December 2022

AbstractMolecular sieves have uniform pores. If the pores are small, the fate of the reactants and the probability of forming products are determined by molecular dimensions and configurations as well as by the types of catalytically active sites present. Reactant shape selectivity occurs when some of the molecules in a reactant mixture are too large to enter the pores. Product selectivity occurs when, among all the product molecules formed within the pores, only those with the proper dimensions can diffuse out and appear as products. In restricted transition state type selectivity certain reactions are prevented because the corresponding transition state requires more space than is available inside the pores.Shape selective processes include acid‐ or base‐catalyzed reactions, oxidations, and reductions. Commercial applications of shape selectivity (1) form desirable isomers instead of undesirable ones, (2) crack undesirable molecules to smaller, easily removable fragments, or (3) avoid undesirable competing reactions such as coking and transalkylation.Ordered mesoporous materials, pillared layer structures, heteropolyacids, and carbon molecular sieves and nanotubes extend shape‐selective application to reactions of molecules too large to fit in the pores of aluminosilicate zeolites. Designing new molecular sieves and modifying existing ones can amplify shape selective effects and thus help to meet future challenges: diminishing raw material supplies, more stringent environmental regulations, changing fuel requirements, and the desire for more flexible, more economical, and environmentally more friendly processes.
Combinatorial Catalysis – Homogeneous
Authors: Tuba Róbert 
Published: December 2022

AbstractCombinatorial chemistry is a high throughput experimental technique that has significantly changed the drug discovery process in the pharmaceutical industry and become common practice for drug research. Combinatorial synthesis and rapid screening techniques have been applied to the development of homogeneous catalysts and for the optimization of reaction conditions. In contrast to classical experimental design, well‐designed high throughput screening systems can test more catalysts a week than was previously done in a year. This could lead to significant savings in research and development costs.This article provides a survey of the most frequently used combinatorial methods and screening systems applied in homogeneous catalysts discovery. Several examples are presented on the identification of most effective homogeneous catalysts for hydrogenation, hydrosilylation, cyclopropanation, epoxidation, etc.
Fréchet Classes
Authors: Durante Fabrizio , Sempi Carlo 
Published: December 2022

Abstract
We describe the notion of Fréchet class as introduced originally by Maurice Fréchet and as it has evolved in present‐day probability and statistics. The main properties of a Fréchet class are described. We also point out how this notion has given rise to that of a copula in order to describe the dependence among the marginals.
System Signatures: A Review
Authors: Asadi Majid , Hashemi Marzieh 
Published: December 2022

Abstract
The signature of coherent systems, as a structure‐dependent concept, is a useful tool for assessing the reliability and stochastic properties of multicomponent systems. In this article, we give various notions of signatures that can be applied to evaluate the reliability of coherent systems when the system components fail under different scenarios. We also briefly review the recent works on applications of signatures in the preventive maintenance of coherent systems.
All‐Visible‐Light Triggered Photoswitch of Dithienylethene Derivatives with Molecular Conformation Changes Excess 5 Å
Authors: Luo Miao , Zhao Juan , Liu Yanyan , Mao Zhu , Wang Sheng , Chi Zhenguo 
Published: December 2022

AbstractDeveloping new all‐visible‐light driven fluorescent molecular switches has attracted much interests due to their important application prospects in materials science and life science. Herein, three novel all‐visible‐light triggered fluorescent molecular photoswitches (2P3, 4F, and 4Cl) are designed and prepared, which are realized by prolonging π‐conjugation length with aggregated‐induced emission units. These photoswitches show reversible photochromic and fluorescent switching in dilute solutions and films under 420 nm and 560 nm irradiations. Meanwhile, upon alternating irradiations with 450 nm/560 nm light, effective photochromic and fluorescent switching in powder states are also achieved. More interestingly, two distinct conformations with different photochromic abilities can be altered by solvents polarity. The size difference of the two conformations is over 5 Å in the vertical direction which is one of the largest changes among photochromic molecules based on dithienylethene. The accompanying conformational changes are analysed to understand the relationship between solvent characteristics and crystal structure, as well as the intermolecular interaction in solid state for all‐visible‐light triggered photoswitching molecules.
Nanoparticle‐Mediated Radiotherapy Remodels the Tumor Microenvironment to Enhance Antitumor Efficacy
Authors: Zhen Wenyao , Weichselbaum Ralph R. , Lin Wenbin 
Published: December 2022

AbstractRadiotherapy (RT) uses ionizing radiation to eradicate localized tumors and, in rare cases, control tumors outside of the irradiated fields via stimulating an antitumor immune response (abscopal effect). However, the therapeutic effect of RT is often limited by inherent physiological barriers of the tumor microenvironment (TME), such as hypoxia, abnormal vasculature, dense extracellular matrix (ECM), and an immunosuppressive TME. Thus, it is critical to develop new RT strategies that can remodel the TME to overcome radio‐resistance and immune suppression. In the past decade, high‐Z‐element nanoparticles have been developed to increase radiotherapeutic indices of localized tumors by reducing X‐ray doses and side effects to normal tissues and enhance abscopal effects by activating the TME to elicit systemic antitumor immunity. In this review, the principles of RT and radiosensitization, the mechanisms of radio‐resistance and immune suppression, and the use of various nanoparticles to sensitize RT and remodel TMEs for enhanced antitumor efficacy are discussed. The challenges in clinical translation of multifunctional TME‐remodeling nanoradiosensitizers are also highlighted.
Holographically Activatable Nanoprobe via Glutathione/Albumin‐Mediated Exponential Signal Amplification for High‐Contrast Tumor Imaging
Authors: Li Ting , Tan Shuangxiu , Li Mengjuan , Luo Jie , Zhang Yueyue , Jiang Zhen , Deng Yibin , Han Liang , Ke Hengte , Shen Junkang , Tang Yong'an , Liu Fan , Chen Huabing , Yang Tao 
Published: December 2022

AbstractGlutathione (GSH)‐activatable probes hold great promise for in vivo cancer imaging, but are restricted by their dependence on non‐selective intracellular GSH enrichment and uncontrollable background noise. Here, a holographically activatable nanoprobe caging manganese tetraoxide is shown for tumor‐selective contrast enhancement in magnetic resonance imaging (MRI) through cooperative GSH/albumin‐mediated cascade signal amplification in tumors and rapid elimination in normal tissues. Once targeting tumors, the endocytosed nanoprobe effectively senses the lysosomal microenvironment to undergo instantaneous decomposition into Mn2+ with threshold GSH concentration of ≈ 0.12 mm for brightening MRI signals, thus achieving high contrast tumor imaging and flexible monitoring of GSH‐relevant cisplatin resistance during chemotherapy. Upon efficient up‐regulation of extracellular GSH in tumor via exogenous injection, the relaxivity‐silent interstitial nanoprobe remarkably evolves into Mn2+ that are further captured/retained and re‐activated into ultrahigh‐relaxivity‐capable complex by stromal albumin in the tumor, and simultaneously allows the renal clearance of off‐targeted nanoprobe in the form of Mn2+ via lymphatic vessels for suppressing background noise to distinguish tiny liver metastasis. These findings demonstrate the concept of holographic tumor activation via both tumor GSH/albumin‐mediated cascade signal amplification and simultaneous background suppression for precise tumor malignancy detection, surveillance, and surgical guidance.
Light‐Fueled Nonreciprocal Self‐Oscillators for Fluidic Transportation and Coupling
Authors: Deng Zixuan , Zhang Hang , Priimagi Arri , Zeng Hao 
Published: December 2022

AbstractLight‐fueled self‐oscillators based on soft actuating materials have triggered novel designs for small‐scale robotic constructs that self‐sustain their motion at non‐equilibrium states and possess bioinspired autonomy and adaptive functions. However, the motions of most self‐oscillators are reciprocal, which hinders their use in sophisticated biomimetic functions such as fluidic transportation. Here, an optically powered soft material strip that can perform nonreciprocal, cilia‐like, self‐sustained oscillation under water is reported. The actuator is made of planar‐aligned liquid crystal elastomer responding to visible light. Two laser beams from orthogonal directions allow for piecewise control over the strip deformation, enabling two self‐shadowing effects coupled in one single material to yield nonreciprocal strokes. The nonreciprocity, stroke pattern and handedness are connected to the fluidic pumping efficiency, which can be controlled by the excitation conditions. Autonomous microfluidic pumping in clockwise and anticlockwise directions, translocation of a micro‐object by liquid propulsion, and coupling between two oscillating strips through liquid medium interaction are demonstrated. The results offer new concepts for non‐equilibrium soft actuators that can perform bio‐like functions under water.
Safety of cold snare polypectomy vs conventional hot polypectomy for 4 to 10 mm gastric polyps: A single‐center retrospective study
Authors: Ma Te‐Ling , Yang Shih‐Cheng , Wu Cheng‐Kun , Lu Long‐Sheng , Liang Chih‐Ming , Tai Wei‐Chen , Chuah Seng‐Kee 
Published: December 2022

AbstractEndoscopic polypectomy has become standard in the management of most polyps in the gastrointestinal tract, but bleeding is the most common adverse event. Polypectomy with a cold snare (CSP) has been increasingly utilized in recent years, but further evidence is required to establish its safety of gastric polypectomy. The aim of this study was to compare intraprocedure and postprocedure adverse events in patients who underwent CSP vs conventional hot snare polypectomy (HSP) of gastric polyps. Electronic medical records and endoscopy reports of all patients who underwent gastric polypectomy at the Kaohsiung Chang Gung Memorial Hospital between January 2019 and June 2021 were retrospectively reviewed. Data on patient demographics, polyp characteristics, method of polypectomy, and adverse events were collected. A total of 193 gastric polyps removed from 111 patients were reviewed. The mean age was 58.1 years, and 74.8% were female. Of these, 142 polyps were removed from 78 patients by HSP, compared to 51 polyps removed from 33 patients by CSP. The mean polyp size was 7.9 mm in the HSP group and 7.5 mm in the CSP group (P = .306). Nine patients (11.5%) from HSP group and 5 (15.2%) from CSP group presented with immediate bleeding that were managed by endoscopic treatment (P = .755). There was no serious adverse event, such as delayed bleeding or perforation, occurred in this study. In multivariate logistic regression, only the number of polyps resected >1 was identified as independent risk factor of immediate post‐polypectomy bleeding. Therefore, the safety of CSP was non‐inferior to HSP and could be an additional option for removal of gastric polyps ≤10 mm.
Yoichiro Nambu and the Concept of Apparent Vacuum: A Stepping Stone to Spontaneous Symmetry Breaking
Authors: Gaudenzi Rocco 
Published: December 2022

AbstractThe processes of discovery and concept formation are as mysterious as they are intriguing. In this article, they give a sketch of Yoichiro Nambu's long path toward the concept of spontaneous symmetry breaking focusing on the pivotal role played by his notion of “apparent vacuum”. This is instrumental to draw the original analogical correspondence between the vacuum of quantum field theory and solid matter, which, transforming over time in its use and purpose, enables Nambu to arrive at the concept of spontaneous symmetry breaking. From this historical episode they draw a methodological lesson and emphasise the broad cultural influences that conditioned the conceptual development.
Structurally Diverse Bench‐Stable Nickel(0) Pre‐Catalysts: A Practical Toolkit for In Situ Ligation Protocols**
Authors: Tran Van T. , Kim Nana , Rubel Camille Z. , Wu Xiangyu , Kang Taeho , Jankins Tanner C. , Li Zi‐Qi , Joannou Matthew V. , Ayers Sloan , Gembicky Milan , Bailey Jake , Sturgell Emily J. , Sanchez Brittany B. , Chen Jason S. , Lin Song , Eastgate Martin D. , Wisniewski Steven R. , Engle Keary M. 
Published: December 2022

AbstractA flurry of recent research has centered on harnessing the power of nickel catalysis in organic synthesis. These efforts have been bolstered by contemporaneous development of well‐defined nickel (pre)catalysts with diverse structure and reactivity. In this report, we present ten different bench‐stable, 18‐electron, formally zero‐valent nickel–olefin complexes that are competent pre‐catalysts in various reactions. Our investigation includes preparations of novel, bench‐stable Ni(COD)(L) complexes (COD=1,5‐cyclooctadiene), in which L=quinone, cyclopentadienone, thiophene‐S‐oxide, and fulvene. Characterization by NMR, IR, single‐crystal X‐ray diffraction, cyclic voltammetry, thermogravimetric analysis, and natural bond orbital analysis sheds light on the structure, bonding, and properties of these complexes. Applications in an assortment of nickel‐catalyzed reactions underscore the complementary nature of the different pre‐catalysts within this toolkit.
Das Alarmon Diadenosintetraphosphat als Cosubstrat für die AMPylierung von Proteinen
Authors: Frese Matthias , Saumer Philip , Yuan Yizhi , Herzog Doreen , Höpfner Dorothea , Itzen Aymelt , Marx Andreas 
Published: December 2022

AbstractDiadenosinpolyphosphate (ApnAs) sind nicht‐kanonische Nukleotide, deren zelluläre Konzentrationen bei Stress als Signal eines homöostatischen Ungleichgewichts ansteigen und die daher als Alarmone bezeichnet werden. Ihre zelluläre Rolle ist nur unzureichend verstanden. In dieser Arbeit haben wir untersucht, ob ApnAs als Cosubstrat für die AMPylierung von Proteinen verwendet werden. AMPylierung ist eine posttranslationale Modifikation, bei der Adenosinmonophosphat (AMP) auf Proteine übertragen wird. Beim Menschen ist die AMPylierung, die durch den AMPylator FICD mit ATP als Cosubstrat vermittelt wird, eine Reaktion auf ER‐Stress. Hier zeigen wir, dass Ap4A für die AMPylierung durch FICD effizient verwendet wird. Durch chemische Proteomik unter Verwendung einer neuen chemischen Sonde haben wir neue potenzielle AMPylierungsziele identifiziert. Interessanterweise haben wir festgestellt, dass sich die AMPylierungsziele von FICD je nach Nukleotid‐Cosubstrat unterscheiden können. Diese Ergebnisse könnten darauf hindeuten, dass sich die Signalübertragung bei erhöhten Ap4A‐Spiegeln während zellulärem Stress von derjenigen bei niedrigen Ap4A Konzentrationen unterscheidet, und damit eine Reaktion auf extrazelluläre Signale ermöglicht.
Three‐Component Synthesis of Dioxaphosphorane‐Fused Diphosphacycles Exhibiting Unique Dynamic Fluorescence “On/Off” Properties
Authors: Li Chenchen , Huang Haiyang , Sun Longgen , Huang Mingqing , Ding Haixin , Bai Jiang , Cao Ban‐Peng , Xiao Qiang 
Published: December 2022

AbstractRigidly planar polycyclic phosphacycles featuring an internal dioxaphosphorane are promising photofunctional materials. However, the lack of efficient synthetic methods resulted in limited structural diversities which significantly hampered extensive study. Herein, we report a straightforward three‐component synthesis of novel dioxaphosphorane‐fused diphosphacycles with distinctive photophysical properties. Control experiments and theory calculations were performed to account for a plausible reaction mechanism. We also systematically investigated the structure‐property relationships of these unprecedented platforms by combining experiments (X‐ray analysis, optical and redox properties) and theoretical computations. Based on their unique structure and properties, a novel fluorescent switch for pH sensing was revealed by a dynamic ring‐opening/ring‐closing process.