bluuebunny/crossref_metadata_2025_split huggingface dataset:
Nitrogen fixation in shallow‐water sediments: Spatial distribution and controlling factors
Authors: Andersson Björn , Sundbäck Kristina , Hellman Maria , Hallin Sara , Alsterberg Christian 
Published: October 2014

Nitrogenase activity (NA) in shallow‐water (< 1 m) sediments was investigated at 60 randomly selected sites along a 150 km stretch on the brackish‐water Swedish west coast, without targeting any specific type of sediments, such as microbial mats. Benthic nitrogen (N) fixation and diazotrophs (nifH genes) were found at all sites, regardless of the presence of cyanobacterial or microbial mats. The majority of sites showed N fixation rates between 0.03 and 1 mmol N m−2 d−1. These rates were similar to those of benthic denitrification previously measured in the area. Maximum rates up to 3.4 mmol N m−2 d−1 were measured. A structural equation model was used to investigate direct and indirect effects of biogeochemical and physical factors on NA. Number of nifH genes had the largest direct positive influence on NA, whereas increasing wave exposure had an indirect negative effect on NA through its influence on the diazotrophic abundance. Increased salinity, previously been shown to suppress NA in coastal waters, was found to directly stimulate benthic N fixation, likely by generating favorable conditions for diazotrophic sulfate‐reducing bacteria. Our field data confirmed previously observed negative effects of dissolved inorganic nitrogen on NA, which have so far mainly been experimentally studied. Both NA rates and the number of nifH genes correlated positively with pore‐water dissolved inorganic phosphorus concentrations. These findings show that the potential for N fixation in illuminated sediments can be considerable, stretching beyond cyanobacterial mats, being controlled by complex interactions between biotic and abiotic factors.
Turbidity influences trophic interactions in estuaries
Authors: Lunt Jessica , Smee Delbert L. 
Published: October 2014

We investigated how changes in abiotic conditions resulting from human activities indirectly alter trophic interactions using turbidity in estuaries as a model system. Development and nutrient input are causing turbidity to increase in many coastal areas. Using an 18 yr data set from Aransas and San Antonio Bays in Texas, we found fish abundance (Sciaenops ocellatus, Pogonias cromis, Archosargus probatocephalus) to be highest in low turbidity (< 30 nephelometric turbidity units [NTU]; p < 0.01), while crab (Callinectes sapidus) abundance was highest in high turbidity (> 30 NTU; p < 0.05). In field studies, mud crabs (Panopeus spp.), an important intermediate predator on oyster reefs that are not targeted in the 18 yr data set, were more abundant on oyster reefs in St. Charles Bay, Texas, when turbidity exceeded 30 NTU (p = 0.03). Fish predation on tethered Panopeus herbstii was greatest when turbidity was low (< 30 NTU, p < 0.05), but predation by crabs (p = 0.003) and overall predation (p = 0.02) were greatest in high turbidity (> 30 NTU). Predation on oyster spat was not different between low‐ and high‐turbidity sites (p = 0.64). However, oysters devoted more resources to shell growth (p < 0.01) at a cost of less somatic growth and fecundity, a reaction known to occur in response to crab predators. Elevated turbidity can alter trophic interactions in estuaries by altering species composition and trophic interactions, leading to an increase in crab abundance, which can alter predation rates as well as growth in juvenile oysters.
Présentation
Authors: Parent Frédéric 
Published: October 2014

Avocat de formation, traducteur de profession et sociologue à temps partiel, Léon Gérin a durablement marqué l’histoire de la sociologie d’ici. Reconnu comme le fondateur de la sociologie canadienne, il a laissé une oeuvre imposante et diversifiée, objet privilégié pour réfléchir aux conditions sociales d’émergence et de développement de la pensée sociologique aux 19e et 20e siècles. Ses écrits intéresseront aussi les chercheurs en sciences sociales préoccupés par l’épreuve empirique du réel et l’articulation entre l’expérience et le sens de la vie en société. Soulignant le 150e anniversaire de naissance du pionnier des études monographiques ou ethnographiques au Québec, ce texte introductif propose une réflexion générale sur la démarche scientifique de la sociologie du triple point de vue de l’enjeu social de connaissance (l’énigme du réel), de la définition de l’objet disciplinaire et de l’élaboration d’une théorie de la connaissance sociologique. Nous présentons en terminant les articles du numéro qui abordent tous, d’une manière ou d’une autre, ces trois aspects de la constitution de la sociologie.
Loss of geosynchronous relativistic electrons by EMIC wave scattering under quiet geomagnetic conditions
Authors: Hyun K. , Kim K.‐H. , Lee E. , Kwon H.‐J. , Lee D.‐H. , Jin H. 
Published: October 2014

AbstractWe have examined relativistic electron flux losses at geosynchronous orbit under quiet geomagnetic conditions. One 3 day period, from 11 to 13 October 2007, was chosen for analysis because geomagnetic conditions were very quiet (3 day average of Kp< 1), and significant losses of geosynchronous relativistic electrons were observed. During this interval, there was no geomagnetic storm activity. Thus, the loss processes associated with geomagnetic field modulations caused by ring current buildup can be excluded. The >2 MeV electron flux at geosynchronous orbit shows typical diurnal variations with a maximum near noon and a minimum near midnight for each day. The flux level of the daily variation significantly decreased from first day to third day for the 3 day period by a factor of >10. The total magnetic field strength (BT) of the daily variation on the third day, however, is comparable to that on the first day. Unlike electron flux decreases, the flux of protons with energies between 0.8 and 4 MeV adiabatically responses to the daily variation of BT. That is, there is no significant decrease of the proton flux when the electron flux decreases. During the interval of quiet geomagnetic conditions, well‐defined electromagnetic ion cyclotron (EMIC) waves were detected at geosynchronous spacecraft. Low‐altitude polar‐orbiting spacecraft observed the precipitation of energetic protons and relativistic electrons in the interval of EMIC waves enhancement. From these observations, we suggest that the EMIC waves at geosynchronous orbit cause pitch angle scattering and relativistic electron losses to the atmosphere under quiet geomagnetic conditions.
Secular trends in physical fitness of Mozambican school‐aged children and adolescents
Authors: Dos Santos Fernanda Karina , Prista António , Gomes Thayse Natacha Queiroz Ferreira , Daca Timóteo , Madeira Aspacia , Katzmarzyk Peter T. , Maia José António Ribeiro 
Published: October 2014

ObjectiveThis study presents information about secular trends in physical fitness (PF) levels among Mozambican youth.MethodsThe sample comprises 3,851 subjects (1,791 boys; 2,060 girls) aged 8–15 years who were evaluated at three time points (1992, 1999, 2012). PF tests included handgrip strength, 10 m × 5 m shuttle‐run, sit‐and‐reach, and 1‐mile run/walk. Biological maturity was assessed by sexual characteristics, and percentage body fat was predicted using triceps and subscapular skinfolds. ANCOVA (controlling for age, maturity status, and percentage body fat) was used to compare mean differences in PF tests among the three time points, by sex.ResultsChildren in 1992 were more flexible than those from 2012; boys handgrip strength increased from 1992 to 2012, while girls decreased their handgrip strength; youth in 1992 were faster and more agile than their 2012 peers; and a decrease was observed in cardiorespiratory fitness between 1992 and 1999 and between 1992 and 2012 for both sexes.ConclusionsA negative secular trend among Mozambican children's PF was observed over the last two decades, suggesting that socio‐political, educational, and economical changes occurring during this period had a relevant effect on their PF. This negative trend suggests that development of intervention programs/strategies to improve PF among youth is warranted. Am. J. Hum. Biol. 27:201–206, 2015. © 2014 Wiley Periodicals, Inc.
The digit ratio (2D:4D) in China: A meta‐analysis
Authors: Xu Yin , Zheng Yong 
Published: October 2014

ObjectivesTo explore the 2D:4D in China (mainland and Taiwan) and to analyze the influences of ethnicity, digit measurement methods, age, and latitude on Chinese 2D:4D.MethodsWe here conducted a meta‐analysis of the results of 28 studies. A total of 112 independent samples and 19,093 participants were included.ResultsThe sex difference in left 2D:4D only approached significance when outliers were removed (P = 0.078), whereas the right 2D:4D was significantly lower in males compared to females, showing that the magnitude of sex difference was greater for the right hand than for the left hand. No significant differences were found in the 2D:4D between Han and ethnic minorities. The 2D:4D of samples measured using indirect digit measurement tended to be lower than in samples measured using direct digit measurement. Moreover, there were no effects of age and latitude on the 2D:4D in China.ConclusionsWe concluded that the sex differences in Chinese 2D:4D are consistent with the results from western studies, and that genetic pool differences rather than latitude‐related environmental variables affect the 2D:4D in China. In addition, 2D:4D measurements obtained by different digit measurement techniques should not be combined within one study, or used together in comparative studies. Am. J. Hum. Biol. 27:304–309, 2015. © 2014 Wiley Periodicals, Inc.
Morphological relationship between the cranial and supraorbital regions in Homo sapiens
Authors: Nowaczewska Wioletta , Kuźmiński Łukasz , Biecek Przemysław 
Published: October 2014

ABSTRACTAlthough some hypotheses that attempt to explain the variation in supraorbital region morphology in modern humans have been proposed, this issue is still not well understood. In this study, the craniofacial size and spatial models were tested using a sample of modern human crania from geographically diverse populations, and the co‐occurrence of the degrees of glabella (GL) and superciliary arch (ST) expression were analyzed. The two supraorbital structures were examined by visual assessment, and eight quantitative variables were included in the three‐way ANOVA, canonical variates analysis and partial rank correlation. The influences of sex and the region of origin of the cranial samples on the relationships between the examined variables and the degrees of supraorbital structures expression were also considered. The results only partially supported the craniofacial size and spatial models and suggested that GL and ST experienced separate influences during development. In the sample of all crania, the neurocranial size more strongly influenced the morphological variation of the ST than of the GL, and sex influenced both of these structures the most. The results suggest that sex may be the main factor (having an influence independent of the other traits) on the morphological variation of the GL and ST. Am J Phys Anthropol 156:110–124, 2015 © 2014 Wiley Periodicals, Inc.
Reversible Ca2+ Switch of An Engineered Allosteric Antioxidant Selenoenzyme
Authors: Zhang Chunqiu , Pan Tiezheng , Salesse Christian , Zhang Dongmei , Miao Lu , Wang Liang , Gao Yuzhou , Xu Jiayun , Dong Zeyuan , Luo Quan , Liu Junqiu 
Published: October 2014

AbstractA Ca2+‐responsive artificial selenoenzyme was constructed by computational design and engineering of recoverin with the active center of glutathione peroxidase (GPx). By combining the recognition capacity for the glutathione (GSH) substrate and the steric orientation of the catalytic selenium moiety, the engineered selenium‐containing recoverin exhibits high GPx activity for the catalyzed reduction of H2O2 by glutathione (GSH). Moreover, the engineered selenoenzyme can be switched on/off by Ca2+‐induced allosterism of the protein recoverin. This artificial selenoenzyme also displays excellent antioxidant ability when it was evaluated using a mitochondrial oxidative damage model, showing great potential for controlled catalysis in biomedical applications.
Reactive Oxygen Species‐Responsive Protein Modification and Its Intracellular Delivery for Targeted Cancer Therapy
Authors: Wang Ming , Sun Shuo , Neufeld Caleb I. , Perez‐Ramirez Bernardo , Xu Qiaobing 
Published: October 2014

AbstractHerein we report a convenient chemical approach to reversibly modulate protein (RNase A) function and develop a protein that is responsive to reactive oxygen species (ROS) for targeted cancer therapy. The conjugation of RNase A with 4‐nitrophenyl 4‐(4,4,5,5‐tetramethyl‐1,3,2‐dioxaborolan‐2‐yl) benzyl carbonate (NBC) blocks protein lysine and temporarily deactivates the protein. However, the treatment of RNase A–NBC with hydrogen peroxide (one major intracellular ROS) efficiently cleaves the NBC conjugation and restores the RNase A activity. Thus, RNase A–NBC can be reactivated inside tumor cells by high levels of intracellular ROS, thereby restoring the cytotoxicity of RNase A for cancer therapy. Due to higher ROS levels inside tumor cells compared to healthy cells, and the resulting different levels of RNase A–NBC reactivation, RNase A–NBC shows a significant specific cytotoxicity against tumor cells.
Constraining Cyclic Peptides To Mimic Protein Structure Motifs
Authors: Hill Timothy A. , Shepherd Nicholas E. , Diness Frederik , Fairlie David P. 
Published: October 2014

AbstractMany proteins exert their biological activities through small exposed surface regions called epitopes that are folded peptides of well‐defined three‐dimensional structures. Short synthetic peptide sequences corresponding to these bioactive protein surfaces do not form thermodynamically stable protein‐like structures in water. However, short peptides can be induced to fold into protein‐like bioactive conformations (strands, helices, turns) by cyclization, in conjunction with the use of other molecular constraints, that helps to fine‐tune three‐dimensional structure. Such constrained cyclic peptides can have protein‐like biological activities and potencies, enabling their uses as biological probes and leads to therapeutics, diagnostics and vaccines. This Review highlights examples of cyclic peptides that mimic three‐dimensional structures of strand, turn or helical segments of peptides and proteins, and identifies some additional restraints incorporated into natural product cyclic peptides and synthetic macrocyclic peptidomimetics that refine peptide structure and confer biological properties.
Cascade Multicomponent Synthesis of Indoles, Pyrazoles, and Pyridazinones by Functionalization of Alkenes
Authors: Matcha Kiran , Antonchick Andrey P. 
Published: October 2014

AbstractThe development of multicomponent reactions for indole synthesis is demanding and has hardly been explored. The present study describes the development of a novel multicomponent, cascade approach for indole synthesis. Various substituted indole derivatives were obtained from simple reagents, such as unfunctionalized alkenes, diazonium salts, and sodium triflinate, by using an established straightforward and regioselective method. The method is based on the radical trifluoromethylation of alkenes as an entry into Fischer indole synthesis. Besides indole synthesis, the application of the multicomponent cascade reaction to the synthesis of pyrazoles and pyridazinones is described.
Enantio‐ and Diastereoselective Access to Distant Stereocenters Embedded within Tetrahydroxanthenes: Utilizing ortho‐Quinone Methides as Reactive Intermediates in Asymmetric Brønsted Acid Catalysis
Authors: Hsiao Chien‐Chi , Liao Hsuan‐Hung , Rueping Magnus 
Published: October 2014

AbstractA protocol for the highly enantioselective synthesis of 9‐substituted tetrahydroxanthenones by means of asymmetric Brønsted acid catalysis has been developed. A chiral binol‐based N‐triflyphosphoramide was found to promote the in situ generation of ortho‐quinone methides and their subsequent reaction with 1,3‐cyclohexanedione to provide the desired products with excellent enantioselectivities. In addition, a highly enantio‐ and diastereoselective Brønsted acid catalyzed desymmetrization of 5‐monosubstituted 1,3‐dicarbonyl substrates with ortho‐quinone methides gives rise to valuable tetrahydroxanthenes containing two distant stereocenters.
Chemoenzymatic Synthesis of Spinosyn A
Authors: Kim Hak Joong , Choi Sei‐hyun , Jeon Byung‐sun , Kim Namho , Pongdee Rongson , Wu Qingquan , Liu Hung‐wen 
Published: October 2014

AbstractFollowing the biosynthesis of polyketide backbones by polyketide synthases (PKSs), post‐PKS modifications result in a significantly elevated level of structural complexity that renders the chemical synthesis of these natural products challenging. We report herein a total synthesis of the widely used polyketide insecticide spinosyn A by exploiting the prowess of both chemical and enzymatic methods. As more polyketide biosynthetic pathways are characterized, this chemoenzymatic approach is expected to become readily adaptable to streamlining the synthesis of other complex polyketides with more elaborate post‐PKS modifications.
Salt and pH sensitive semi‐interpenetrating polyelectrolyte hydrogels poly(HEMA‐co‐METAC)/PEG and its BSA adsorption behavior
Authors: Hu Yan‐Yan , Zhang Jing , Fang Qi‐Chen , Jiang Dong‐Mei , Lin Chu‐Cheng , Zeng Yi , Jiang Ji‐Sen 
Published: October 2014

ABSTRACTA novel semi‐interpenetrating poly(2‐hydroxyethyl methacrylate) (pHEMA) based polyelectrolyte hydrogel [p(HEMA‐co‐METAC)/PEG] was prepared by copolymerizing HEMA with the cationic monomer 2‐methacryloyloxyethyltrimethyl ammonium chloride (METAC) in the presence of polyethylene glycol (PEG) with different content and molecular weight (MW 4000 and 400). The chemical structure of the gels was confirmed by FT‐IR spectroscopy, morphology study was performed by scanning electron microscope (SEM), thermal stability was revealed by thermogravimetric analysis (TGA), and the mechanical properties were determined by electronic universal testing machine. Swelling studies showed introduction of cationic monomer METAC led to high water content, and the obvious salt and pH sensitive properties were observed which proved the smart behavior of the semi‐interpenetrating polymer networks (IPNs) gels. In addition, the effect of temperature and some important biological solution on swelling behavior were reported. Cytotoxicity test demonstrated that synthesized gels owned satisfactory cytocompatibility and were convenient for the application as biomaterials. Finally, the weak bovine serum albumin (BSA) adsorption on semi‐IPNs by introducing METAC and controlling the content of PEG in gels demonstrated that they were of good protein resistance effect in biomedical applications. © 2014 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2015, 132, 41537.
The Claisen Rearrangement – Part 1: Mechanisms and Transition States, Revisited with Quantum Mechanical Calculations and Ultrashort Pulse Spectroscopy
Authors: Zelentsov Sergei , Hessel Volker , Shahbazali Elnaz , Noël Timothy 
Published: October 2014

AbstractThe Claisen rearrangement is an ideal candidate for mechanistic and transition‐state analysis. Recently, physical‐chemistry investigations, in particular relying on quantum mechanics and modern fs‐pulse (‘short‐time') laser spectroscopy, have given totally new insights here. At the same time, flow chemistry has emerged, offering considerable processing advances over batch processing. It is also known to be much powerful with inline flow sensing techniques. Yet, both key innovations have not been bridged so far and thus there is an eminent knowledge gap in mechanistic analysis of reactions. This two‐review compilation is a first step to close this gap. Part 1 focuses on the insight which quantum‐mechanical calculations can add to the existing knowledge based on heuristic, handy interpretation of reaction experiments in the light of electrodensity distributions. Quantum‐mechanical calculation can provide geometric key data and short‐time laser spectroscopy can verify this and deepen it in the sense of a comprehensive vibration analysis. In this way, prior structural assumptions can be confirmed or turned to be falsified and there is potential to resolve the uncertainty.
Subdural hemorrhage – a serious complication post‐intrathecal chemotherapy. A case report and review of literature
Authors: Chia Xiu Xian , Bazargan Ali 
Published: October 2014

Key Clinical MessageWe need to have a high index of suspicion for subdural hemorrhage (SDH) post‐lumbar puncture in hematological patients given their increased risk and the significant morbidity and mortality associated with SDHs.
New Cofactor‐Independent Hydration Biocatalysts: Structural, Biochemical, and Biocatalytic Characteristics of Carotenoid and Oleate Hydratases
Authors: Hiseni Aida , Arends Isabel W. C. E. , Otten Linda G. 
Published: October 2014

AbstractIn industrial biocatalytic processes the class of lyases (EC 4) is underrepresented and only a few enzymes are used in industrial scale reactions. Hydro‐lyases (EC 4.2.1) catalyze the non‐hydrolytic and non‐oxidative addition of water to a CC bond. Without a biocatalyst, this reaction proceeds under strong acidic conditions with no enantioselectivity. From a chemical point of view carotenoid 1,2‐hydratase (CrtC) performs a very challenging addition of water to an isolated CC bond. This hydration reaction proceeds without assistance of electron withdrawing groups or transition metals, which makes it very interesting from both an industrial, as well as enzymatic point of view. Oleate hydratase (OHase) catalyzes the enantioselective conversion of oleic acid into 10‐hydroxystearic acid. The crystal structure of OHase from Lactobacillus acidophilus was published recently, which contributes to the understanding of this enzyme. These enzymes could broaden the organic chemist’s toolbox.
Microkinetic Modeling of the Fischer–Tropsch Synthesis over Cobalt Catalysts
Authors: Azadi Pooya , Brownbridge George , Kemp Immanuel , Mosbach Sebastian , Dennis John S. , Kraft Markus 
Published: October 2014

AbstractWe present a detailed microkinetic analysis of the Fischer–Tropsch synthesis on a Co/γ‐Al2O3 catalyst over the full range of syngas conversions. The experiments were performed in a Carberry spinning basket batch reactor at initial H2/CO ratios between 1.8 and 2.9, temperatures of 469 and 484 K, and initial pressures of 2 MPa. A reaction mechanism based on the H2‐assisted CO activation pathway, which comprises 128 elementary reactions with 85 free parameters, was proposed to explain the experimental results. Each of these elementary reactions belongs to one of the following reaction groups: adsorption–desorption, monomer formation, chain growth, hydrogenation–hydrogen abstraction, or water–gas shift. A two‐stage parameter estimation method, based on a quasi‐random global search followed by a gradient‐free local optimization, has been used to calculate the values of pre‐exponential factors and activation energies. The use of data obtained from batch experiments enabled an effective analysis of dominating reactions at different stages of syngas conversions.