bluuebunny/crossref_metadata_2025_split huggingface dataset:
Dehydrogenation – Heterogeneous
Authors: Resasco Daniel E. 
Published: December 2022

AbstractThe dehydrogenation of alkanes is an important industrial reaction, widely used to produce olefins. This endothermic reaction is thermodynamically favored at high temperatures and low pressures. As a result, it typically operates under severely deactivating conditions. Therefore, the design of effective catalysts and processes is an interesting technical challenge. Catalytic dehydrogenation is employed in the production of propylene, isobutylene, C6–C19monoolefins, as well as styrene from ethylbenzene.Dehydrogenation is typically carried out on noble metal catalysts, such as Pt, or oxide catalysts, such as chromia. Promoters are used to improve the selectivity and stability of dehydrogenation catalysts. On Pt‐based catalyst, the preferred promoter is Sn, which modifies Pt geometrically and electronically to reduce the undesired side reactions, hydrogenolysis, and coking. On chromia‐based catalysts, the addition of alkali improves the performance. In addition to Pt‐ and chromia‐based catalysts, other catalytic materials have been used in dehydrogenation reactions. They include iron oxide, zinc titanates, and sulfided nickel.
Disilylation
Authors: Broene Richard D. , Baker R. Tom 
Published: December 2022

Abstract
The metal‐catalyzed addition of disilanes to unsaturated organic molecules—including alkenes, allenes, alkynes, carbonyls, and combinations of these groups—is reviewed, with emphasis given to synthetically useful transformations. Mechanistic details of the reaction are discussed. Examples of both intra‐ and intermolecular variants are given, with particular attention to reactions that proceed with good regio‐ and/or stereoselectivity, including those resulting from substrate diastereoselection and catalyst‐based enantioselection. Synthetically useful transformations of the resulting disilanes are also presented.
Hydrodenitrogenation – Heterogeneous
Authors: Ozkan Umit S. , Bunch Abdu Y. 
Published: December 2022

AbstractHydrodenitrogenation (HDN) is one of the most important catalytic hydrotreating reactions. Polycyclic nitrogen compounds that have a carbocycle and a five‐ or six‐membered heterocycle are the major nitrogen‐containing species in industrial feedstocks. In this review, thermodynamics, CN bond cleavage, HDN mechanisms of model compounds and reaction mixtures are discussed. Hydrotreating catalysts, kinetic modeling, and adsorption active sites are topics that are also covered.
Oxygenation and Oxygenases
Authors: May Sheldon W. 
Published: December 2022

AbstractBiological oxygenation reactions in which molecular oxygen is incorporated directly into organic subsrates are catalyzed by the enzymes known as oxygenases. These enzymes, first discovered in 1955, have since been found to be very widely distributed in nature. In dioxygenase‐catalyzed reactions, both atoms of the oxygen molecule are incorporated into the organic substrate, whereas monooxygenases incorporate only one of these oxygen atoms into the substrate. Currently, over 200 oxygenases enzymes are known, and these enzymes are all classified in EC groups 1.13 and 1.14. Among the reactions catalyzed by oxygenases are hydroxylations of methane and other alkanes, aromatics, flavonoids, menthol, and cholesterol; oxygenation of olefins, sulfur, and other heteroatoms; oxygenative cleavage of aromatic rings; and oxygenative decarboxylations. Oxygenases also catalyze the first step in the biosynthesis of prostaglandins; key steps in the biosynthesis and interconversion of antibiotics; and important bioremediation reactions critical to maintenance of the environment. A number of biotechnological applications for oxygenases have been emerging in recent years, and progress is also being made in the development of nonenzymatic model systems that might mimic the functional or structural properties of oxygenase enzymes.
Polymerization – Homogeneous
Authors: Vlád Gábor 
Published: December 2022

AbstractPolymers are among the largest manufactured industrial products. Their extremely diversified properties render a widespread presence possible in everyday life. Polymers can be synthesized either by homogeneous or heterogeneous processes. This article focuses on the homogeneous procedures. The first part of the article summarizes the polymerization of monomers containing at least one carbon–carbon double bond or carbon–carbon triple bond. This is followed by a description of the environmentally accepted and biocompatible poly(lactic acid)s and epoxide–carbon dioxide alternating copolymers. The next two paragraphs focus on special procedures, living and enzymatic polymerization, by which polymers can be synthesized with exotic architectures. The article concludes is finished with the description of step‐growth polymerizations of aromatic systems.
Selective Oxidation—Industrial
Authors: Centi Gabriele , Perathoner Siglinda 
Published: December 2022

AbstractSelective oxidation processes are one of the central building blocks of the chemicals industry. This article describes the main industrial processes and relevant engineering issues in this area and includes also a short historical background description. General aspects of the reaction mechanisms are briefly discussed, but attention is centered on the description of the main industrial processes and relevant cases both regarding liquid‐phase and vapor‐phase processes. A schematic flow sheet for the most relevant processes is also included. Aspects such as the relationship between catalyst and reactor design and the use of pure O2instead of air as the oxidizing agent are also discussed. The processes discussed in the liquid phase section include alkylaromatics and cyclohexane oxidation, new processes using hydrogen peroxide, the oxidation of cumene, the synthesis of propene oxide and ethene to acetaldehyde conversion. The section of gas‐phase processes on solid catalysts include the oxidative dehydrogenation of methanol to formaldehyde, the synthesis of ethene oxide, ethene oxychlorinaton and acetoxylation, propene oxidation to acrolein and acrolein oxidation to acrylic acid, the synthesis of methyl methacrylate, propene ammoxidation to acrylonitrile, the ammoxidation of alkylaromatics, and the synthesis of maleic anhydride fromn‐butane and of phthalic anhydride fromo‐xylene.
Sulfur Oxides Removal – Heterogeneous
Authors: Flytzani‐Stephanopoulos Maria , Liu Wei 
Published: December 2022

AbstractThis article describes the significant progress made in recent years in the development and fundamental understanding of catalysts for the reduction of sulfur dioxide by CO, synthesis gas, or methane. The direct catalytic reduction of SO2to elemental sulfur offers several advantages to power plants and industrial boilers using heavy fossil fuels, the main one being a simple process flowsheet for exhaust gas desulfurization with incorporated sulfur recovery. The environmental benefit is the recovery of sulfur in an innocuous form, which can be safely disposed of. Combined SO2/NOxremoval can also be envisioned with such catalysts with ensuing overall system efficiency gains. Several high activity and high selectivity catalysts are presently available for SO2reduction by CO or syngas (CO + H2), while under development are also catalysts for the reduction of sulfur dioxide with natural gas. These catalysts and the particulars of the associated SO2reduction processes are described in the article. Emphasis is given to catalysts based on cerium oxide which show promise for SO2reduction by either CO or methane, over a wide temperature window and in the presence of water and NOx. Mechanistic explanations are offered for the observed activity and selectivity of several of these catalyst compositions.
Whole Cell Catalysis
Authors: Chen Wilfred , Bruhlmann Fredi , Lee Kelvin H. , Deshusses Marc 
Published: December 2022

AbstractSignificant advances have been made in our understanding about the use of whole cell catalysis in different applications, some of which have been realized on industrial scale. Although the ability to predict which of the given microorganisms is suitable for whole cell catalysis remains an overwhelming task, the increasing understanding of fundamental mechanistic principles generated from both basic research rapid screening and genetic engineering, will likely lead to the emergence of novel solutions for improved whole cell catalysis. This article, attempts to summarize the recent developments in the area of whole cell biocatalysis and their practical applications.
Use of Synthetic Metalloporphyrins as Oxidation Catalysts
Authors: Kim Cheal , Watanabe Yoshihito 
Published: December 2022

AbstractWhile heme enzymes use iron porphyrin (heme) as the prosthetic group, a variety of metal ions can be introduced into the porphyrin ring to produce metalloporphyrin complexes. In addition to the change of the central metal ions, we are able to synthesize the porphyrin bearing many types of substituents. Thus, the use of synthetic metalloporphyrin complexes is not limited to model reactions of heme enzymes such as peroxidase and P‐450. Although a major concern of this review is oxidations catalyzed by metalloenzymes, many oxidants such as iodosylbenzene (C6H5IO),m‐chloroperbenzoic acid (mCPBA), and sodium hypochlorite (NaOCl) can be used in addition to hydrogen peroxide and reductive oxygen activation as observed for P‐450. In early part of this article, the use of metalloporphyrin as synthetic model systems of heme enzymes is discussed. Preparation and characterization of high valent oxo‐metal intermediates are reviewed in detail. Then, applications of synthetic metalloporphyrins as catalysts for oxidation reactions are described. Highly efficient, robostic against the heme destruction, and stereo‐ and enantioselective reaction systems are the major concerns.
Neural Crest: Origin, Migration and Differentiation
Authors: Sutton Gemma , Kelsh Robert N 
Published: December 2022

Abstract

The neural crest is a population of cells that emigrates from the dorsal neural tube during early embryogenesis and migrates extensively to give rise to a myriad of cell types. Patterns of migration are controlled largely by extracellular cues in the environment. Neural crest cells are initially multipotent, but the mechanism whereby cells choose and become committed to individual fates remains a longstanding source of contention. Cell fate specification – the selection of an individual cell fate from all the possibilities available to a multipotent progenitor – is generally considered to be a progressive process. However, a recent flurry of single‐cell transcriptional profiling studies indicates a more dynamic process in which cells with retained multipotency display expression of competing genetic modules specifying different fates. Extracellular cues in the migratory and postmigratory environment act together with intrinsic transcription factors to ensure that specific fates are chosen.

Key Concepts

The neural crest is an important tissue, as reflected in its nickname, ‘the fourth germ layer’.

Neural crest cells give rise to many different cell types.

Neural crest cells are induced at the boundary of the developing neural plate and prospective epidermis.

Neural crest induction depends on BMP signalling in the prospective epidermis and Wnt signalling from the underlying mesoderm.

These signals induce neural crest in two phases, specification of the neural plate border, and specification/maintenance of definitive neural crest.

Neural crest migration patterns are complex, and usually specific to the derivative fate adopted.

Neural crest migration is controlled by the environmental distribution of repellent and attractive/permissive signals, with specific receptor expression in the neural crest cells determining their response.

All neural crest cells are initially multipotent, with specification of individual derivative fates resulting from competition between genetic modules controlling pairs of fates.

Nevertheless, it is proposed that these specified cells retain a cryptic full multipotency, most visible in adult neural crest‐derived stem cells.

Neural crest fate specification is then a dynamic process in which extracellular factors influence the transcriptional state of the cell, eventually driving it towards a specific fate choice.

Fate specification results from transcriptional activation of key genes encoding (a combination of) specific transcription factors.

These transcription factors, together with ongoing extracellular signals, activate and maintain the fate‐specific gene regulatory networks that characterise each cell type.
Plant Organ Primordia
Authors: Dobry Emily , Campbell Michael 
Published: December 2022

Abstract

Plant organ primordia are central to defining the shape and success of the plant through ever‐changing environmental conditions. The shoot (SAM) and root (RAM) apical meristems, which are composed of totipotent cells, generate the major plant organs including leaves, flowers and roots by initiating primordium formation. While the process of organ generation is unique to each meristem, major overarching themes have been observed, including important hormonal and gene interactions. The phytohormones auxin and cytokinin work to establish organ formation and define overall organ positioning, while homeotic genes work with the hormones to maintain stem cell fate and define meristem structure. These interactions, in conjunction with environmental pressures, govern the aerial and terrestrial form of the plant. In perennial plants, seasonal cues alter primordia development resulting in shifts between growth and growth suppression or senescence. The mechanisms and signals underlying these transitions remain unclear.

Key Concepts

Apical meristems are complex plant organs that give rise to above‐ and below‐ground tissues that define the overall plant structure.

Interaction between members of the
WUSCHEL
and
CLAVATA
gene families regulate growth of the apical meristem.

Hormone interaction between auxin and cytokinin initiates formation and determines position of aerial organs through hormonal gradients and inhibitory fields.

Gravistimulation and auxin oscillation determine positioning of future lateral roots by priming cells, but environmental factors dictate whether initiation occurs.

Shoot apical meristems experience vegetative and reproductive phases in which they produce either leaves or reproductive meristems.

Perennial plants also experience a period of quiescence known as dormancy, which is induced by external cues such as day length and temperature.

As shoot apical meristems prepare for dormancy, they switch from production of leaves and flowers to production of bud scales.

Entrance into dormancy is regulated by an increase in abscisic acid, while dormancy release is accompanied first by an increase in cytokinin activity followed by an increase in gibberellic acid metabolism.
Insights into computational thinking from think‐aloud interviews: A systematic review
Authors: Pan Zexuan , Cui Ying , Leighton Jacqueline P. , Cutumisu Maria 
Published: December 2022

AbstractThis systematic review examines 35 empirical studies featuring the use of think‐aloud interviews in computational thinking (CT) research. Findings show that think‐aloud interviews (1) are typically conducted in Computer Science classrooms and with K‐12 students; (2) are usually combined with other exploratory CT assessment tools; (3) have the potential to benefit learners with special needs and identify the competency gaps through involving diverse participants; (4) are conducted in the absence of cognitive models and standard procedures; and (5) display insufficient definitional and methodological rigor. Theoretically, this review presents a systematic assessment about the application of think‐aloud interviews in CT studies and identifies the limitations in existing CT‐related think‐aloud studies. Practically, this review serves as a reference for studying the cognitive processes during CT problem‐solving and provides suggestions for CT researchers who intend to incorporate think‐aloud interviews in their studies.
Biomimetic Aerogel for Moisture‐Induced Energy Harvesting and Self‐Powered Electronic Skin
Authors: Zhang Xuezhong , Wang Min , Wu Yanan , Chen Xin , Wu Kai , Fu Qiang , Deng Hua 
Published: December 2022

AbstractMoisture–electric generator (MEG)‐based blue energy is widely studied. There is still a significant challenge in improving the power of the MEGs system and expanding its application in self‐powered electronic skin. Inspired by the structure of ferns, a biomimetic moisture–electric aerogel is designed to collect energy. Polyvinyl alcohol dendritic colloids act as “roots” and “stems” to provide support and channels to transport water molecules. Meanwhile, “leaf‐like” graphene oxide sheets generate electricity through direct interaction with water. Besides, based on the above biomimetic structure, this work further enhances the output performance of MEGs by increasing the specific surface area (120.4 m2 g−1) and introducing an ultra‐high ion density gradient (from −35 to +37 mV). Meanwhile, due to the excellent water absorption, the MEGs show good salt resistance and cyclic stability. By constructing unique biomimetic structures, ultra‐high ion density gradient, and regulating environmental conditions, a high‐performance MEG is obtained, including ultra‐high open‐circuit voltage (1.9 V) and short‐circuit current (82.5 µA), the industry‐leading power density among MEGs with continuous output is reported in the literature (22.55 µW cm−2). Besides, the MEGs can accurately respond to environmental and pressure changes, showing its application potential in self‐powered electronic skin.
Efficient and Bright Deep‐Red Light‐Emitting Diodes based on a Lateral 0D/3D Perovskite Heterostructure
Authors: Ke You , Guo Jingshu , Kong Decheng , Wang Jingmin , Kusch Gunnar , Lin Chen , Liu Dawei , Kuang Zhiyuan , Qian Dongmin , Zhou Fuyi , Zhang Guangbin , Niu Meiling , Cao Yu , Oliver Rachel A. , Dai Daoxin , Jin Yizheng , Wang Nana , Huang Wei , Wang Jianpu 
Published: December 2022

AbstractBright and efficient deep‐red light‐emitting diodes (LEDs) are important for applications in medical therapy and biological imaging due to the high penetration of deep‐red photons into human tissues. Metal‐halide perovskites have potential to achieve bright and efficient electroluminescence due to their favorable optoelectronic properties. However, efficient and bright perovskite‐based deep‐red LEDs have not been achieved yet, due to either Auger recombination in low‐dimensional perovskites or trap‐assisted nonradiative recombination in 3D perovskites. Here, a lateral Cs4PbI6/FAxCs1−xPbI3 (0D/3D) heterostructure that can enable efficient deep‐red perovskite LEDs at very high brightness is demonstrated. The Cs4PbI6 can facilitate the growth of low‐defect FAxCs1−xPbI3, and act as low‐refractive‐index grids, which can simultaneously reduce nonradiative recombination and enhance light extraction. This device reaches a peak external quantum efficiency of 21.0% at a photon flux of 1.75 × 1021 m−2 s−1, which is almost two orders of magnitude higher than that of reported high‐efficiency deep‐red perovskite LEDs. Theses LEDs are suitable for pulse oximeters, showing an error <2% of blood oxygen saturation compared with commercial oximeters.
Over 19% Efficiency Organic Solar Cells by Regulating Multidimensional Intermolecular Interactions
Authors: Han Chenyu , Wang Jianxiao , Zhang Shuai , Chen Liangliang , Bi Fuzhen , Wang Junjie , Yang Chunming , Wang Pengchao , Li Yonghai , Bao Xichang 
Published: December 2022

AbstractResearch on organic solar cells (OSCs) has progressed through material innovation and device engineering. However, well‐known and ubiquitous intermolecular interactions, and particularly their synergistic effects, have received little attention. Herein, the complicated relationship between photovoltaic conversion and multidimensional intermolecular interactions in the active layers is investigated. These interactions are dually regulated by side‐chain isomerization and end‐cap engineering of the acceptors. The phenylalkyl featured acceptors (LA‐series) exhibit stronger crystallinity with preferential face‐on interactions relative to the alkylphenyl attached isomers (ITIC‐series). In addition, the PM6 and LA‐series acceptors exhibit moderate donor/acceptor interactions compared to those of the strongly interacting PM6/ITIC‐series pairs, which helps to enhance phase separation and charge transport. Consequently, the output efficiencies of all LA series acceptors are over 14%. Moreover, LA‐series acceptors show appropriate compatibility, host/guest interactions, and crystallinity relationships with BTP‐eC9, thereby leading to uniform and well‐organized “alloy‐like” mixed phases. In particular, the highly crystalline LA23 further optimizes multiple interactions and ternary microstructures, which results in a high efficiency of 19.12%. Thus, these results highlight the importance of multidimensional intermolecular interactions in the photovoltaic performance of OSCs.
Strategies to Extend the Lifetime of Perovskite Downconversion Films for Display Applications
Authors: Kim Jae Il , Zeng Qingsen , Park Sunghee , Lee Hyejin , Park Jinwoo , Kim Taejun , Lee Tae‐Woo 
Published: December 2022

AbstractMetal halide perovskite nanocrystals (PeNCs) have outstanding luminescent properties that are suitable for displays that have high color purity and high absorption coefficient; so they are evaluated for application as light emitters for organic light‐emitting diodes, light‐converters for downconversion displays, and future near‐eye augmented reality/virtual reality displays. However, PeNCs are chemically vulnerable to heat, light, and moisture, and these weaknesses must be overcome before devices that use PeNCs can be commercialized. This review examines strategies to overcome the low stability of PeNCs and thereby permit the fabrication of stable downconversion films, and summarizes downconversion‐type display applications and future prospects. First, methods to increase the chemical stability of PeNCs are examined. Second, methods to encapsulate PeNC downconversion films to increase their lifetime are reviewed. Third, methods to increase the long‐term compatibility of resin with PeNCs, and finally, how to secure stability using fillers added to the resin are summarized. Fourth, the method to manufacture downconversion films and the procedure to evaluate their reliability for commercialization is then described. Finally, the prospects of a downconversion system that exploits the properties of PeNCs and can be employed to fabricate fine pixels for high‐resolution displays and for near‐eye augmented reality/virtual reality devices are explored.