bluuebunny/crossref_metadata_2025 huggingface dataset:
Quality Evaluation of Eggs from ISA Brown as Influenced by Natural Antioxidants and Storage Time
Authors: Akinwumi A. O. , Oshodi O. A. , Atandah R. A. , Okunlola O. O. , Adeosun O. , Odeleye B. D. , Abdulhameed K. O. , Akinwumi B. S.
Published: December 2022

This study aimed to assess the effect of natural antioxidants on storage time, physical and chemical properties of egg. A total of 200 laying ISA brown birds were distributed into eight dietary groups, each dietary group with 25 birds (5 birds per replicate). They were fed with roselle, black pepper, green tea, combine (roselle + black pepper + green tea) at 0.5 g/kg and 1.0 g/kg in basal diet respectively and a control feed. At the end of eight (8) weeks of feeding trial, twelve eggs were collected from each dietary group (six eggs per dietary group were analyzed for the internal and external properties while the remaining six were stored). Data collected include; Egg shape index, egg weight, shell thickness, membrane weight, yolk index, haugh unit, meat and blood spot, yolk colour, lipid profile, lipid peroxidation and proximate analysis. Data generated were subjected to Analysis of variance using the General Linear Model for factorial within a completely randomized design. The natural antioxidants significantly (P<0.05) improves the proximate composition of the poultry eggs. Both Green tea and Black pepper have significant effect (P<0.05) on the yolk percentage. Black pepper increases (P<0.05) the Haugh unit while it shows to be lower (P>0.05) in the combination of the antioxidants. The inclusion levels of the natural antioxidants on the internal and external quality of egg reveals that there were no significant (P>0.05) differences in the two inclusion level of 0.5 g/kg and 1.0 g/kg of feed but they have numerically higher values in the external parameters and internal parameters. Eggs stored for 4 weeks had the lowest value (P>0.05) for the proximate and lipid profiles, though there are no significant (P>0.05) differences in their values. The fresh eggs show high moisture content (P<0.05) but the value for nitrogen free extract is low (P>0.05) in the fresh eggs. The natural antioxidants improved significantly (P<0.05) the proximate composition of the poultry eggs, with the green tea having the highest value (P<0.05) for Moisture contents and CP, black pepper the highest (P<0.05) for CP Based on the result obtained from this study, the natural antioxidants (black pepper, green tea and roselle) in layers’ diet shows significant effects on the physical qualities of egg and the yolk color was also preferred with the inclusion of the natural antioxidants compared to the control. The chemical properties also deteriorate with the storage time. Natural antioxidants are hereby recommended for better and improved chemical qualities of eggs.
Comparison of Anthropometric Parameters of Women and Men Agricultural Workers Pertaining to Tractor Operator Workspace
Authors: Arya K. T. , Ramana C. , Reddy B. Ravindra , HariBabu B. , Ramana M. V.
Published: December 2022

Women are equally capable of carrying all the works that the men can do at the agricultural field. But it is strange that they were not selected for operating agricultural machineries. Especially they were not well expert in tractor operation. So a study was conducted to analyse the anthropometric and strength parameters required for the tractor operator workspace design. The comparison of anthropometric data indicated that out of twenty seven anthropometric parameters except ten parameters via. Buttock Popliteal height, elbow rest height, wall to acromian, shoulder grip length, thigh clearance sitting, hip breadth sitting, grip diameter, grip span and span akimbo were having higher values for female workers than that of male workers.
Effect of Organic and Inorganic Plant Growth Promoters on Yield Attribute, Yield and Economics of Wheat (Triticum aestivum L.) Varieties
Authors: Prajapati Sunil Kumar , Verma V. K. , Singh Gurwaan , Singh Shivendra , Verma Shikhar , Prajapati Bimlesh Kumar , Kumari Pooja
Published: December 2022

The field experiment was carried out during Rabi season of 2021-22 at “Students’ Instructional Farm” of Chandra Shekhar Azad University of Agriculture and Technology, Kanpur. The experiment included two factors, viz. timely shown wheat varieties, V1-DBW-187, V2-K-1006, and V3-K-607 in main-plot and plant growth promoters (PGPs), G0- Control, G1- Nitrobenzene @ 3ml l-1, G2-Gibberellic acid @ 2000 ppm, G3-Seaweed extract solid @ 25 kg ha-1, G4-Seaweed extract liquid @ 625 ml ha-1, G5-Micronutrients (Zn, Fe, B, Cu) @ 0.5% were selected in sub-plots. The overall 18 treatment combinations were accommodated in Split Plot Design and replicated thrice. The results of this study showed significant increases in yield attributes, yield and economics, viz. no. of ears m-2 (426.29, 417.63), length of ear (10.97, 10.53 cm), no. of grains ear-1 (69.55, 69.81), test weight (40.67, 39.66 g), grain yield (4764.67, 4402.33 kg ha-1) and  gross income (INR. 141547.00, 131446.90), net income (INR. 96773.00, 86672.74) and B: C ratio (3.14, 2.93) in  wheat varieties DBW-187, K-1006 respectively as compared to variety K-607. Among plant growth promoters,  G6-mixture of micronutrients (Zn, Fe, Cu, B) @ 0.5% foliar spray at tillering stage, resulted significant increments in yield attributes, yield and economics, viz. no. of ears m-2 (445.43), length of ear (11.96 cm), no. of grains ear-1 (73.67), test weight (41.87g), grain yield (4813.67 kg ha-1), gross income (INR. 139707.40), net income (INR. 94263.00) and B: C ratio (3.06) as compared to control treatment. G3-Gibberellic acid @ 2000 ppm and G5-Seaweed extract liquid @ 625 ml ha-1 show significant result also. The maximum No. of ears m-2, Length of ear, No. of grains ear-1, Test weight, grain yield, gross income, net income and B: C ratio was recorded under the variety DBW-187 and   mixture nutrients (Zn Fe, Cu, and B).
Influence of Seed Size and Bio-fertilizer on Growth, Yield and Yield Parameter of Groundnut [Arachis hypogaea (L.)] Crop under Rainfed Condition
Authors: Dabhi R. V. , Surve Vaishali H. , Raj A. D. , Sankhla P. M.
Published: December 2022

A field experiment was conducted during kharif season 2021 to study the effect of seed size and bio-fertilizers on growth, yield and yield parameter of crop. The treatments include different categories of seed size viz., mixed (S1), bold (S2) and small seed size (S3) and bio-fertilizer viz., control (B1), Rhizobium + PSB + KMB (B2) and Trichoderma harzianum + Aspergillus niger (B3). Large seed size and bio-fertilizer shows significant effect on growth parameter viz., plant height, number of branches plant-1, number of pegs plant-1 and root nodules plant-1 and yield parameter viz., number of pods plant-1, number of seeds per pod-1, seed index, shelling percentage and seed yield of groundnut except harvest index. Large seed size shows significant increase in number of pegs plant-1 and pods plant-1 which increase the yield of groundnut. In case of bio-fertilizer, Rhizobium + PSB + KMB shows significant effect on growth and yield parameter viz., plant height, number of branches plant-1, number of pegs plant-1, root nodules plant-1, yield parameter viz., number of pods plant-1, number of seeds per pod-1, seed index, shelling percentage and seed yield of groundnut except harvest index.
Meeting notes
Authors: - -
Published: December 2022

Meeting notes for 14 May 1894.
Anniversary meeting
Authors: - -
Published: December 2022

Several Fellows and one Lady Associate were elected at this Anniversary meeting. A list of deceased Fellows was then read, before the Secretary read the Annual Report on the number of visitors, purchases and donations to the Society's museum and library.

 

Meeting notes for 10 December, 1894 are appended.
Meeting notes
Authors: - -
Published: December 2022

Meeting notes for 13 April 1896.
Lugar e Animismo
Authors: Souza Júnior Carlos Roberto Bernardes de
Published: December 2022

Face à crise socioambiental contemporânea, as ciências humanas têm buscado outras formas de compreender a realidade que superam as dicotomias do pensamento cartesiano. Uma das alternativas é a reabilitação do animismo como potencial de descentramento do antropocentrismo, de forma a valorizar formas de consciência não-humana. Nesse sentido, o presente ensaio visa problematizar o conceito de lugar da geografia cultural e humanista por meio das influências do animismo contemporâneo, especialmente de sua vertente eco-fenomenológica. Considera-se que a lugaridade conflui por nexos mais-que-humanos nos quais formas de sentir e pensar intersubjetivos, intercorporais e de interanimalidade se manifestam como condições do coabitar na Terra. Pelo entendimento das polinizações cruzadas de sentidos de lugares humanos e não-humanos, salientam-se as multiplicidades experienciais da realidade geográfica. Esse processo decorre do estranho parentesco que enovela animais, plantas, rochas, atmosferas e outros fenômenos outros-que-humanos em uma teia de inerências e co vulnerabilidades terrestres. Conclui-se que mais que concernir à habitação, os lugares convergem em reversibilidades, interdependências, comunicações e tensões referentes ao (com) partilhar polifônico de coabitação.
Percepção dos agentes públicos municipais e dos sindicatos dos trabalhadores rurais sobre governança territorial e participação
Authors: Carvalho Fernanda Cunha de
Published: December 2022

Esta pesquisa preocupa-se com a temática da governança territorial e da participação, tendo como objetivo geral avaliar a participação do Sindicato dos Trabalhadores Rurais nas decisões e ações das Secretarias Municipais de Agricultura, bem como suas dinâmicas institucionais. A observação de duas microrregiões do estado do Maranhão foi o recorte escolhido: Baixada Maranhense e Litoral Ocidental Maranhense. Nesses processos é fundamental analisar se as organizações públicas e de interesse dos agentes econômicos e dos atores sociais perpassam em torno de um projeto econômico e social para o setor e o seu território. Para tanto, houve oauxílio de referenciais bibliográficos e a realização de pesquisas quantitativas sobre organizações associativas e qualitativas, alimentadas por entrevistas, com os atores citados. Constatou-se a inexistência das práticas de governança entre essas duas instituições. Os elementos da governança demonstram que na área em análise não existe uma dimensão operacional do termo, desconsiderando os princípios básicos de uma proposta difusa e democrática sobre um desenvolvimento aplicado em âmbito local, com pouco ou quase nenhum grau de participação dos sindicatos no contexto das políticas de agricultura.
Cicloturismo e políticas públicas:
Authors: Silva Matheus Oliveira Martins da , Meneguzzo Isonel Sandino
Published: December 2022

O cicloturismo é uma ramificação do turismo de aventura e seu diferencial está no caminho percorrido pelo cicloturista e não no destino a ser alcançado. O objetivo geral da pesquisa é o de compreender a implantação do circuito de cicloturismo “Pé Vermelho” no norte do Paraná e suas potencialidades enquanto política pública para o desenvolvimento local e regional. Trata-se de uma pesquisa qualitativa, de caráter exploratório e descritiva. Os resultados apontam que, embora as discussões do cicloturismo no Paraná enquanto possível política pública tenham sido evidenciadas nos últimos três anos, questões técnicas e regionais não foram consideradas para uma efetiva consolidação da prática no estado. O Circuito Pé Vermelho, foco da análise, é um exemplo de como a sociedade civil se organizou para estruturar um circuito que, por fim, tornou-se alvo de interesses políticos que desconfiguraram o roteiro estabelecido e exigem novas possibilidades de organização.
Acylation – Homogeneous
Authors: Smyth Timothy P.
Published: December 2022

The main thrust of this article is to draw together the salient features relevant to understanding the nature of catalysis in acyl‐group transfer. In doing so, an attempt is made to identify common elements of catalysis across diverse acylation processes involving both Lewis and Brønsted acids. Acyl‐group transfer to carbon‐based substrates is the most synthetically useful implementation of this reaction and, as such substrates are frequently moderate nucleophiles, catalysis is most required in acylation of these materials. Procedures and processes aimed at cleaner, more atom‐efficient Friedel–Crafts acylation chemistry are also covered, as are other acylation reactions: these include use of organometallic species and catalysis of acyl‐group transfer to heteroatoms such as O and N in instances where chemo‐ and enantioselective control is important.
Aldol Reaction – Biological and Biomimetic
Authors: Dickerson Tobin J. , Córdova Armando , Chen Da‐Wei , Janda Kim D.
Published: December 2022

In order to develop new methodology for stereospecific and catalytic aldol reactions, synthetic organic chemists are now exploring the utility of biological catalysts. There has been significant progress in this field and several efficient, selective, and predictable biological catalysts are now available for the asymmetric aldol reaction. Critical to metabolism, the aldolases catalyzein vivoaldol reactions with high chemo‐, regio‐, diastereo‐, and enantioselectivity. These enzymes are divided into four distinct areas: DHAP‐dependent, pyruvate/phosphoenol pyruvate‐dependent, acetaldehyde‐dependent, and glycine‐dependent aldolases based upon their donor dependence. Catalytic antibodies that operate via a mechanism reminiscent of a type I aldolase also have been developed. These antibodies have remarkable rate accelerations and broader substrate specificity compared to naturally occurring aldolases. However, both aldolases and catalytic antibodies share a common feature critical to their success as synthetically useful catalysts—both are capable of tolerating substrates with unprotected functional groups in aqueous solutions and give readily predictable products. This article will focus on the development of these two areas of biological aldol catalysts and discuss relevant examples as appropriate.
Biphasic Catalysis – Industrial
Authors: Cornils Boy
Published: December 2022

Biphasic techniques are among the recent improvements in homogeneous catalysis. Biphasic catalysis is thus the most successful variant of an immobilization technique that anchors the catalyst on a liquid support. Till date, processes that have been applied industrially are the oligomerization of ethylene to α‐olefins (Shell's SHOP process), the hydroformylation of propylene ton‐butyraldehyde (Ruhrchemie/Rhône‐Poulenc process), and the hydrodimerization of butadiene ton‐octanol or 1,9‐nonanediol (Kuraray process). While these are operated with capacities of roughly 2 million tons annually, there are also small‐scale applications yielding intermediates. Because of the inherent advantage of this method, especially in environmental respects, biphasic processes of catalysis will grow further and reach top relevance.
Carbon Dioxide Conversion
Authors: Heyn Richard H.
Published: December 2022

A summary of the catalytic transformations of CO2is presented. The review is divided into five sections according to the broad categories of homogeneous, polymerization, heterogeneous, electro‐ and photochemical, and biological catalysis. The section on homogeneous catalysis focuses mainly on CO2hydrogenation and the coupling reactions between CO2and unsaturated hydrocarbons. The discussion on polymerization catalysis encompasses primarily the production of polycarbonates from CO2and epoxides. The heterogeneous catalysis of CO2is nearly entirely devoted to either the hydrogenation of CO2or the dry‐reformation of methane. Heterogeneous examples of homogeneous catalyses are also included. Electro‐ and photochemical catalyses are distinguished from each other by the source of the reducing electrons. These processes are further subdivided into those that occur via homogeneous catalysts and those that occur heterogeneously at an electrode or semiconductor surface. The section on biological catalyses discusses first the enzyme carbonic anhydrase, followed by CO2‐assimilation pathways under both aerobic and anaerobic conditions, and it covers both naturally occurring and biomemetic systems.
Dehydrogenation – Homogeneous
Authors: Goldman Alan S.
Published: December 2022

Homogeneous catalysts for the dehydrogenation of organic substrates, particularly alkanes and other hydrocarbons, are reviewed. The dehydrogenation of hydrocarbons results in the addition of an unsaturated site to an organic substrate; it is therefore, in principle, a reaction with almost unlimited potential value in the areas of commodity‐ and fine‐chemical synthesis. Most of this potential has not yet been realized; with respect to the use of heterogeneous catalysts the major obstacles involve the difficulty in achieving regio‐ and chemoselectivity. Homogeneous dehydrogenation catalysts offer the promise of much greater selectivity, but thus far have not afforded economically viable yields and turnover numbers. Thus, at present, homogeneous hydrocarbon dehydrogenation is an active area of research rather than an important industrial process. Several platinum‐group transition metal complexes have shown particular promise for alkane dehydrogenation; these are discussed in detail. Selectivity and high yields are both more readily achieved in the case of dehydrogenation of HCCH units that are adjacent to functional groups; several catalysts for such reactions are examined.
Dehydrogenation – Heterogeneous
Authors: Resasco Daniel E.
Published: December 2022

The 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

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

Hydrodenitrogenation (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

Biological 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

Polymers 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

Selective 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

This 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

Significant 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

While 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.
Radicals in Catalysis – Homogeneous
Authors: Gansäuer Andreas , Fielenbach Doris
Published: December 2022

Recent developments in the control of radical generation and radical reactivity utilizing homogeneous catalysts are described. Special emphasis is put on the recently emerging field of redox catalysis in pinacol couplings and epoxide openings. A typical enantioselective reaction is also discussed.
Neural Crest: Origin, Migration and Differentiation
Authors: Sutton Gemma , Kelsh Robert N
Published: December 2022

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

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.
Political Opportunity/Political Opportunity Structure
Authors: della Porta Donatella
Published: December 2022

Social movements not only challenge political institutions, but also interact with them in diverse arenas. The characteristics of these interactions affect the form and intensity of the challenge as well as its probabilities of success. These are the main tenets of the so‐called political process approach that pointed at the links between social movements and politics. Developed especially by political scientists, this approach allowed a correction of a vision of social movements as belonging to a civil society, separated from the political system.
Resonance, Frame
Authors: McCammon Holly
Published: December 2022

One of the most utilized concepts in social movement framing studies is “frame resonance.” Snow and Benford introduced the term to account for the ability of a collective action frame to resonate or appeal to a targeted audience. To understand why a frame has resonance, one must explore both the properties of the frames themselves and the characteristics of the broader cultural environment in which collective action framing takes place. That is, the source of frame resonance lies at the
conjunction
of framing content and ideational elements in the wider cultural milieu. Frames resonate because individuals find them convincing, appealing, or even familiar. Identifying the precise circumstances in which movement frames achieve this persuasive status, then, is the critical question researchers confront. When will a collective action frame rouse the interests of bystander publics, elected officials, institutional authorities, or potential social movement recruits?
Social Class and Social Movements
Authors: Eder Klaus
Published: December 2022

The link between social class and social movements refers back to the assumption of Karl Marx that in some specified cases the formation of social classes is connected with the mobilization of these classes. Social movements then become what Marx has called “Klassen für sich,” classes conscious of themselves. Marx points to the small tenants in France as a famous example of a class not capable of developing a collective consciousness of itself and therefore being unable to act collectively. He referred to them as a “sack of potatoes.” Regarding the industrial worker, Marx was much more optimistic because of the intersection of two critical factors: (i) the presumed centrality of the conflict this emerging class would address; and (ii) the social conditions that link the proletarian workers via their concentration in the industrial workplace and the urban housing conditions which make communication and strong relationships among them more probable.
Targets
Authors: Martin Andrew
Published: December 2022

Most scholarly interest on social movements has been focused on movements themselves; the types of tactics they employ, what resources they use, and how they mobilize rank‐and‐file to bring about social change. The actual target of movement activism is less well examined. Generally, in modern democratic societies, the assumption is the state is the primary granter of benefits, and therefore the most logical target of protest, although other institutions also function in that capacity. Moreover, targets vary in their vulnerabilities to movement pressure; some are more susceptible to challenges than others. This entry explores the importance of targets in relation to social movements and protest.
Voluntary Associations and Social Movements
Authors: Walker Edward T.
Published: December 2022

Voluntary associations are organized collectivities in which most take part for reasons other than to receive compensation for their participation. The concept of a “voluntary association” has deep roots in the history and thought of American political development. Indeed, as de Tocqueville wrote in
Democracy in America
, his celebrated account of his 1831 visit to the US, “no country in the world has made better use of association than the United States and nowhere has that powerful instrument been applied to a wider range of purposes.” Indeed, long traditions in US political thought have held that associations are schools of self‐reliant citizenship and democratic practice through which interests and preferences are newly formed rather than predetermined. Associations offer a space outside the bureaucratic and electoral demands of the state, while also remaining relatively insulated from the pecuniary interests and competitive pressures of the market. Scholars of voluntary associations have highlighted the means by which nonpolitical forms of civic organization, such as neighborhood groups, fraternal organizations, and, in a well‐known instance, choral groups, provide not only social integration and the participatory norms, social networks, and feelings of trust that accompany it, but they also indirectly socialize participants into active and engaged citizenship.
Asylum Rights Protest Campaigns
Authors: Monforte Pierre
Published: December 2022

Immigration and asylum are, by definition, global issues which concern transnational actors. However, the construction and implementation of immigration and asylum policies relate to state borders and are therefore traditionally entrenched in national contexts. For this reason, even if social movements mobilizing to defend the rights of migrants and refugees have regularly used international norms to increase their rights at the national level, they have rarely organized collective actions across borders and they have mainly addressed their demands to state authorities. However, since the mid‐1990s, groups and networks mobilizing for the rights of migrants and refugees have constructed networks, frames, and collective actions which go beyond national borders, and they have organized significant and regular transnational campaigns to target international – and in particular European – institutions. The transnationalization of pro‐refugee movements has accelerated significantly in the context of the 2015 “refugee crisis,” when new actors have gained a significant role in this field.
Gay and Lesbian Movement
Authors: Valocchi Stephen
Published: December 2022

The gay and lesbian movement refers to the manifold collective efforts to benefit people with same‐sex desire. The emergence of “the homosexual” as a distinct person emerged in the late nineteenth and early twentieth centuries as the result of the efforts of sexologists and medical elites to define and control non‐normative sexual and gender practices emerging in Europe and the US. Although an organized movement to reverse the negative discourse of the sexologists first appeared in Germany in the late nineteenth century and the United States in the 1920s, these efforts were short‐lived.
Disability Rights Movement(s) (United States)
Authors: Lessor Roberta G. , Blaser Arthur W.
Published: December 2022

This entry reviews the disability rights movement over the last eight decades. It reveals a radically changing movement history intersecting with social and political forces, impacted by technological developments, and shaped by its own successes. An entire generation has grown up since the passage of the Americans with Disability Act (ADA) of 1990, seeing themselves in a light different than pioneer activists and defining broader and sometimes conflicting movement goals. The breadth of movement activity has come to be understood in conjunction with race, class, gender, and sexuality, with scholars suggesting that disability constitutes an additional “field” of inquiry to be included in social movement study. Disability rights activists continue to question definitions of normality, care, and interdependence, often in tandem with a host of other social movements.
Memes
Authors: Campbell Baird
Published: December 2022

Though the concept of memes is as old as culture itself, modern memes are a direct outcome of our particular technological and cultural landscape. As such, memes as units of cultural transferal and preservation have much to offer anthropology. As we continue our quest to better understand human sociality, memes provide a rare window into how cultural norms arise, crystallize, and resonate. Perhaps most importantly, they provide crucial insight into the role of communication and sociality in shaping our individual and group identities and values, which in turn makes social change increasingly possible. Though we may be tempted to dismiss memes as silly or ephemeral, through deeper analysis, memes can help us better understand our social worlds, our values, and ourselves.
Culture of Publishing
Authors: Finnegan Ruth
Published: December 2022

Publishing is in essence the purposeful dissemination of some work by its creator beyond just him‐ or herself, whether orally or using one of the many writing systems, always, as with any social institution, intermingled with politics, power, and social constraints. There have been many changes in the culture and conventions of publishing over the years, in large part because of changing technologies—in particular, print and digital reproduction. Recent developments include an arguably greater role for authors in the form of self‐publishing, print on demand, ebooks, audiobooks, online publication, and open access, together with online selling and services for authors. This entry summarizes the current technological, logistical, and economic conditions under which academic publishing currently takes place.
Reconstructing Social Networks: Transitional Changes from a Mobile Hunter‐Gatherer to a Sedentary Neolithic Agrarian System
Authors: Coward Fiona
Published: December 2022

The increasingly permanent, large‐scale communities that developed in Southwest Asia in the early Neolithic, and that have been the norm in many societies ever since, mark a significant break with the highly mobile, fission–fusion forms of social organization shared by all earlier human and, indeed, other primate forebears. While economic, ecological, and cultural changes were clearly an important part of the transition, the social changes that accompanied them have received considerably less attention, despite the fact that they may have been critical elements of the transition. Network methods specifically designed for visualizing and analyzing changes in social structure thus offer enormous potential for examining the momentous social changes that occurred at this time.
Velia (Elea)
Authors: Colivicchi Fabio
Published: December 2022

Summary of the history and archaeology of the ancient town of Velia.
Insights into computational thinking from think‐aloud interviews: A systematic review
Authors: Pan Zexuan , Cui Ying , Leighton Jacqueline P. , Cutumisu Maria
Published: December 2022

This 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

Moisture–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

Bright 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.