bluuebunny/crossref_metadata_2025_split huggingface dataset:
Enantioselective Copper‐Catalyzed Decarboxylative Propargylic Alkylation of Propargylic Esters with β‐Keto Acids
Authors: Zhu Fu‐Lin , Wang Ya‐Hui , Zhang De‐Yang , Hu Xin‐Hu , Chen Song , Hou Chuan‐Jin , Xu Jie , Hu Xiang‐Ping 
Published: June 2014

AbstractThe first copper‐catalyzed intermolecular enantioselective decarboxylative propargylic alkylation of propargylic esters with β‐keto acids as surrogates of ketones has been successfully developed by using a ketimine P,N,N‐ligand. High yields and excellent enantioselectivities (up to 98% ee) have been achieved under the mild reaction conditions.magnified image
Laccase/2,2,6,6‐Tetramethylpiperidinoxyl Radical (TEMPO): An Efficient Catalytic System for Selective Oxidations of Primary Hydroxy and Amino Groups in Aqueous and Biphasic Media
Authors: Díaz‐Rodríguez Alba , Martínez‐Montero Lía , Lavandera Iván , Gotor Vicente , Gotor‐Fernández Vicente 
Published: June 2014

AbstractCopper salts/2,2,6,6‐tetramethylpiperidinoxyl radical (TEMPO) catalytic systems enable efficient aerobic oxidations of primary alcohols but they generally show a reduced reactivity in aqueous medium. Herein, we report an oxidative catalytic system composed of Trametes versicolor laccase and TEMPO, which is able to work in buffer solutions at room temperature using ambient air. Although this catalytic system displays great efficiency in aqueous systems, the addition of methyl tert‐butyl ether allows the reduction of TEMPO loading, also enhancing the solubility of hydrophobic compounds. This practical methodology promotes the chemoselective aerobic oxidation of hydroxy or amino groups, leading to interesting organic derivatives such as aldehydes, lactones, hemiaminals or lactams.magnified image
Chiral N,N′‐Dioxide–Scandium(III)‐Catalyzed Asymmetric Epoxidation of 2‐Arylidene‐1,3‐diketones with Hydrogen Peroxide
Authors: Chu Yangyang , Hao Xiaoyu , Lin Lili , Chen Weiliang , Li Wei , Tan Fei , Liu Xiaohua , Feng Xiaoming 
Published: June 2014

AbstractThe catalytic asymmetric epoxidation of 2‐arylidene‐1,3‐diketones using aqueous 30% H2O2 as oxidant has been successfully realized by a N,N′‐dioxide–scandium(III) triflate [Sc(OTf)3] complex, giving the corresponding products in moderate to good yields (up to 85%) with excellent enantioselectivities (up to 99% ee) under mild reaction conditions without extra additives.magnified image
Asymmetric Synthesis of α‐Amino Acids under Operationally Convenient Conditions
Authors: Jörres Manuel , Chen Xia , Aceña José Luis , Merkens Carina , Bolm Carsten , Liu Hong , Soloshonok Vadim A. 
Published: June 2014

AbstractA new multipurpose glycine equivalent for the general asymmetric synthesis of α‐amino acids is introduced. The chiral reagent can be transformed to various amino acids by alkylations with alkyl halides as well as aldol and Michael addition reactions under operationally convenient reaction conditions at room temperature with virtually complete stereochemical control.magnified image
Intergenerational effects of early life nutrition: Maternal leg length predicts offspring placental weight and birth weight among women in rural Luzon, Philippines
Authors: Chung Green C. , Kuzawa Christopher W. 
Published: June 2014

ObjectivesLeg length is the component of stature most sensitive to early life nutrition; as such, it provides an opportunity to retrospectively evaluate the relationship between a woman's infancy and early childhood nutrition and offspring birth weight (BW). Here we explore the relationship between maternal leg length and offspring BW in a rural Philippine community, while also investigating the potential role of placental size as a pathway.MethodsAnthropometric and questionnaire data were obtained among pregnant women (ages 17–42 years) at a birthing clinic in Antipolo City, Philippines (n = 80). Offspring BW and placental weight were collected upon delivery.ResultsMaternal leg length, but not trunk length, was a positive predictor of infant BW. This relationship was strengthened after adjusting for gestational age and maternal body mass index (BMI). Further adjustment for placental weight attenuated the relationship between leg length and BW, while placental weight was unrelated to maternal trunk length. The relationship between maternal BMI and BW was also attenuated after adjustment for placental weight.ConclusionMaternal leg length is the component of stature that most strongly predicts offspring placental weight and BW in this sample. These findings suggest that fetal nutrition and growth in the present generation are influenced, in part, by the mother's own early life growth conditions. Our results add to evidence that fetal nutrition tracks the mother's past nutritional experiences, while also suggesting that ensuring favorable growth conditions during infancy and early childhood may benefit not only the present generation, but future offspring. Am. J. Hum. Biol. 26:652–659, 2014. © 2014 Wiley Periodicals, Inc.
The changing patterns of psychosocial exposures at work in the South of Europe: Spain as a labor market laboratory
Authors: Utzet Mireia , Moncada Salvador , Molinero Emilia , Llorens Clara , Moreno Neus , Navarro Albert 
Published: June 2014

AimsTo examine the pattern of psychosocial risk exposures at work among wage‐earners in Spain in 2005 and 2010, and to analyze changes in exposure inequalities by gender and job category.MethodsPsychosocial exposures were compared using the COPSOQ‐ISTAS21 method, based on two surveys representative of the Spanish wage‐earning population (2005 and 2010). Statistical analysis was conducted using correspondence analysis.ResultsThere was an increase in exposure to high Double Presence, low Social Support, high Work Pace, and high Insecurity about finding a job; and reduction in exposure to high Insecurity about losing a job, and to high Insecurity over worsening of employment conditions. A gender‐ and occupation‐related gradient was maintained.ConclusionAlthough this study analyzes wage‐earner “survivors” after the outbreak of the current economic crisis, it shows a worsening of harmful exposures to some psychosocial risks. In a context of job destruction, concerns about worsening working conditions appear to be subordinate to insecurity about job loss. Am. J. Ind. Med. 57:1032–1042, 2014. © 2014 Wiley Periodicals, Inc.
Cancer incidence in California farm workers, 1988–2010
Authors: Mills Paul K. , Shah Purvi 
Published: June 2014

BackgroundFarmers and farm workers have previously been found to experience decreased risk of some causes of death but elevated risks of certain types of cancer. A previous report on cancer incidence in a farm worker labor union between 1987 and 1997 found increased leukemia, brain, stomach, and uterine cervix cancer rates in this working population.MethodsA roster of farm workers was created and electronically linked to the database of the California Cancer Registry. Proportionate cancer incidence (PCIR), stage, and age at diagnosis and histological subtypes of cancer were compared between the United Farm Workers (UFW) members and the Hispanic population of California as well as to the non‐Hispanic whites (NHW).ResultsIn this population of 139,000 farm workers in California, more than 3,600 cancer diagnoses were recorded between 1988 and 2010. Proportionately more cancer was noted in the UFW than among California NHW for kidney and renal pelvis cancer (PCIR = 1.60), liver (PCIR = 4.24), prostate (PCIR = 1.13), and uterine cervix cancer (PCIR = 2.08). Proportionately less breast (PCIR = 0.85), lung (PCIR = 0.75), skin melanoma (PCIR = 0.18), and urinary bladder cancer (PCIR = 0.59) was found. Stage at diagnosis was more advanced in the farm workers for several cancer sites, although, not for colorectal cancer.ConclusionsThese farm workers experience proportionally more prostate, kidney and renal pelvis, brain, liver, stomach, cervix and leukemia and less breast, melanoma, and colorectal cancer than reference populations. For many sites, cancer is not diagnosed as early in the farm workers as in the comparison groups, except for colorectal cancer in females and melanoma in males. Am. J. Ind. Med. 57:737–747, 2014. © 2014 Wiley Periodicals, Inc.
Fatal and non‐fatal occupational injuries and diseases among migrant and native workers in South Korea
Authors: Cha Seungman , Cho Youngtae 
Published: June 2014

BackgroundMigrant workers now represent an increasing percentage of workers in Korea, but few studies have evaluated work‐related health risks in this population. In this study, we explored the relative risk of occupational injuries and diseases in migrant workers compared with native Korean workers.MethodAn analysis of work‐related injuries and diseases among migrant workers in Korea during 2005–2007 was conducted in each industrial subsector using nationwide data.ResultsRisks of fatal and non‐fatal occupational injuries for migrant workers were considerably higher than their Korean counterparts. The industry‐adjusted standard mortality ratios of fatal occupational injuries were 1.89 (1.45–2.47), 2.29 (1.81–2.88), and 1.73 (1.36–2.22) for 2005, 2006, and 2007, respectively.ConclusionsA greater proportion of migrant workers is exposed to higher risks of occupational safety and health issues than their Korean counterparts, demonstrating that the occupational safety and health of migrant workers requires more attention than that of Korean workers. Am. J. Ind. Med. 57:1043–1052, 2014. © 2014 Wiley Periodicals, Inc.
Prebiotic Cell Membranes that Survive Extreme Environmental Pressure Conditions
Authors: Kapoor Shobhna , Berghaus Melanie , Suladze Saba , Prumbaum Daniel , Grobelny Sebastian , Degen Patrick , Raunser Stefan , Winter Roland 
Published: June 2014

AbstractAttractive candidates for compartmentalizing prebiotic cells are membranes comprised of single‐chain fatty acids. It is generally believed that life may have originated in the depth of the protoocean, that is, under high hydrostatic pressure conditions, but the structure and physical–chemical properties of prebiotic membranes under such conditions have not yet been explored. We report the temperature‐ and pressure‐dependent properties of membranes composed of prebiotically highly‐plausible lipids and demonstrate that prebiotic membranes could not only withstand extreme temperatures, but also serve as robust models of protocells operating in extreme pressure environments. We show that pressure not only increases the stability of vesicular systems but also limits their flexibility and permeability to solutes, while still keeping the membrane in an overall fluid‐like and thus functional state.
Highly Enantioselective Construction of Tricyclic Derivatives by the Desymmetrization of Cyclohexadienones
Authors: Martín‐Santos Cecilia , Jarava‐Barrera Carlos , del Pozo Sandra , Parra Alejandro , Díaz‐Tendero Sergio , Mas‐Ballesté Rubén , Cabrera Silvia , Alemán José 
Published: June 2014

AbstractThe asymmetric synthesis of tricyclic compounds by the desymmetrization of cyclohexadienones is presented. The reaction tolerated a large variety of substituents at different positions of the cyclohexadienone, and heterocyclic rings of different sizes were accessible. Density functional theory calculations showed that the reaction proceeds through an asynchronous [4+2] cycloaddition.
Dynamic and Quantitative Control of the DNA‐Mediated Growth of Gold Plasmonic Nanostructures
Authors: Shen Jianlei , Xu Lifeng , Wang Chunpeng , Pei Hao , Tai Renzhong , Song Shiping , Huang Qing , Fan Chunhai , Chen Gang 
Published: June 2014

AbstractReproducible and controllable growth of nanostructures with well‐defined physical and chemical properties is a longstanding problem in nanoscience. A key step to address this issue is to understand their underlying growth mechanism, which is often entangled in the complexity of growth environments and obscured by rapid reaction speeds. Herein, we demonstrate that the evolution of size, surface morphology, and the optical properties of gold plasmonic nanostructures could be quantitatively intercepted by dynamic and stoichiometric control of the DNA‐mediated growth. By combining synchrotron‐based small‐angle X‐ray scattering (SAXS) with transmission electron microscopy (TEM), we reliably obtained quantitative structural parameters for these fine nanostructures that correlate well with their optical properties as identified by UV/Vis absorption and dark‐field scattering spectroscopy. Through this comprehensive study, we report a growth mechanism for gold plasmonic nanostructures, and the first semiquantitative revelation of the remarkable interplay between their morphology and unique plasmonic properties.
Enantioselective Organocatalytic Michael/Aldol Sequence: Anticancer Natural Product (+)‐trans‐Dihydrolycoricidine
Authors: McNulty James , Zepeda‐Velázquez Carlos 
Published: June 2014

AbstractA total synthesis of the anticancer natural product (+)‐trans‐dihydrolycoricidine is reported from α‐azidoacetone and cinnamaldehyde precursors. Key elements include an asymmetric organocatalytic sequence proceeding by a regiospecific secondary‐amine‐catalyzed syn Michael addition followed by an intramolecular aldol reaction. The sequence results in the formation of an advanced intermediate, containing three stereogenic centers, in one step which and was converted into the title compound in eight steps.
Hydrogen Abstraction/Acetylene Addition Revealed
Authors: Parker Dorian S. N. , Kaiser Ralf I. , Troy Tyler P. , Ahmed Musahid 
Published: June 2014

AbstractFor almost half a century, polycyclic aromatic hydrocarbons (PAHs) have been proposed to play a key role in the astrochemical evolution of the interstellar medium (ISM) and in the chemistry of combustion systems. However, even the most fundamental reaction mechanism assumed to lead to the simplest PAH naphthalene—the hydrogen abstraction–acetylene addition (HACA) mechanism—has eluded experimental observation. Here, by probing the phenylacetylene (C8H6) intermediate together with naphthalene (C10H8) under combustion‐like conditions by photo‐ionization mass spectrometry, the very first direct experimental evidence for the validity of the HACA mechanism which so far had only been speculated theoretically is reported.
Occurrence and spatio‐temporal distribution of sperm whale (Physeter macrocephalus) in the submarine canyon of Cuma (Tyrrhenian Sea, Italy)
Authors: Mussi Barbara , Miragliuolo Angelo , Zucchini Antonio , Pace Daniela S. 
Published: June 2014

ABSTRACT

Boat surveys aimed at studying sperm whales in the Tyrrhenian Sea were conducted between 2002 and 2011. During 768 daily surveys, a total effort of 32 602 km was achieved within an area of 8800 km2 resulting in 92 encounters with 229 sperm whale individuals.
Average encounter rates of sperm whales was 0.5 groups per 100 km2, with a higher concentration in the vicinity of the submarine canyon of Cuma, confirming the importance for the species of this small hotspot in the Mediterranean Sea.
Encounter rates increased with increasing distance from the coast. It is possible that the intense boat traffic and anthropogenic disturbance in the area may be moving animals away from the coast leading to habitat loss.
The species–habitat relationship documented in this study has implications for conservation. Copyright © 2014 John Wiley & Sons, Ltd.
Variability in Premolar and Molar Root Number in a Modern Population of Pan troglodytes verus
Authors: Emonet Edouard‐Georges , Kullmer Ottmar 
Published: June 2014

ABSTRACTWhile teeth are the most common fossil remains for hominoids, little is known of the tooth root morphology in Primates. With the exception of modern humans, the variability of the number of roots within a species is scarcely documented and not conclusively quantified. This lack of knowledge hinders the interpretation of observed evolutionary trends, such as the reduction of the number of roots of premolars within the hominins. Here, we present the first quantification of the variability of the number of roots in a nonhuman ape population including 405 specimens. Our sample is made of a single biological population of Pan troglodytes verus from Liberia, which is compared to other extant hominoids. Both permanent and deciduous teeth were analyzed and comprise premolars and molars from maxillaries and mandibles. The estimated variability is very low for each tooth position; more than 97% of the specimens displaying the same number of roots except for P4 (94%), M1 (89%), and P4 (57%). No variability at all was observed for lacteal teeth. Males and females are statistically identical, and no difference linked to the tooth size (estimated by the occlusal surface) was observed. When compared to the observation in other hominoid species, these results emphasize that the difference of the number of roots observed between modern humans and apes is significant, and suggests that the evolution of premolar root number is mosaic, with the common ancestor of Pan and Homo probably displaying a reduced number of roots for P4 and maybe P3, but a plesiomorphic morphology of the roots of lower premolars. Anat Rec, 297:1927–1934, 2014. © 2014 Wiley Periodicals, Inc.
Quantitative evaluation of biliary elimination of gadoxetate, a magnetic resonance imaging contrast agent, via geometrical isomer‐specific transporting system in rats
Authors: Ogawa Junji , Yokota Azusa , Araki Takuya , Aomori Tohru , Nakamura Tomonori , Yamamoto Koujirou , Koshiishi Ichiro 
Published: June 2014

ABSTRACTGadoxetate, a magnetic resonance imaging contrast agent, is eliminated into bile. Gadoxetate geometrical isomers are chromatographically classified into two groups by differences between their ionic states (GIs‐I and GIs‐II; 65:35 w/w); however, the elimination mechanism of each isomer in vivo remains controversial. Thus, the contribution of carrier‐mediated transport systems on the biliary elimination of gadoxetate was examined. Gadoxetate was injected intravenously into rats, and the time courses of the plasma concentrations and biliary elimination of GIs‐I and GIs‐II were examined by high‐performance liquid chromatography techniques. The results showed that 34.7% of GIs‐I (GIs‐I(s); 22.6% of gadoxetate) was quickly eliminated into bile within 30 min after injection. The contents of the residual GIs‐I (GIs‐I(r)) and GIs‐II in plasma similarly decreased according to a first‐order elimination process (t1/2 = 23–27 min), and 64.0% of GIs‐I(r) and GIs‐II (49.6% of gadoxetate) was eliminated into the bile within 2 h after injection. There was no significant difference between the elimination half‐lives of GIs‐I(r) and GIs‐II in rats. In conclusion, the geometrical isomer with specific conformation corresponding to 22.6% of gadoxetate was eliminated into bile in rats via a carrier‐mediated transport system no later than 30 min after intravenous injection. Copyright © 2014 John Wiley & Sons, Ltd.
DNA Nanoarchitectures: Steps towards Biological Applications
Authors: Tintoré Maria , Eritja Ramon , Fábrega Carmen 
Published: June 2014

AbstractDNA's remarkable molecular recognition properties, flexibility, and structural features make it one of the most promising scaffolds to design a variety of nanostructures. During recent decades, two major methods have been developed for the construction of DNA nanomaterials in a programmable way; both generate nanostructures in one, two, and three dimensions. The tile‐based assembly process is a useful tool to construct large and simple structures; the DNA origami method is suitable for the production of smaller, more sophisticated and well‐defined structures. Proteins, nanoparticles and other functional elements have been specifically positioned into designed patterns on these structures. They can also act as templates to study chemical reactions, help in the structural determination of proteins, and be used as platform for genomic and drug delivery applications. In this review we examine recent progresses towards the potential use of DNA nanostructures in molecular and cellular biology.
Fast Multipoint Immobilized MOF Bioreactor
Authors: Liu Wan‐Ling , Wu Cheng‐You , Chen Chien‐Yu , Singco Brenda , Lin Chia‐Her , Huang Hsi‐Ya 
Published: June 2014

AbstractAn enzyme–NBD@MOF bioreactor with exemplary proteolytic performance, even after successive reuse and storage, was produced through a novel, rapid and simple multipoint immobilization technique without chemical modification of the solid support. Enzyme loading and distribution could be directly monitored from the fluorescence emission of the bioreactor. The dye molecular dimension plays a role in its overall performance.
Sortagging: A Robust and Efficient Chemoenzymatic Ligation Strategy
Authors: Ritzefeld Markus 
Published: June 2014

AbstractBioorthogonal, chemoselective ligation methods are an essential part of the tools utilized to investigate biochemical pathways. Specifically enzymatic approaches are valuable methods in this context due to the inherent specificity of the deployed enzymes and the mild conditions of the modification reactions. One of the most common strategies is based on the transpeptidation catalyzed by sortase A derived from Staphylococcus aureus. The procedure is well established and a wide variety of applications have been published to date. Here, implementations of sortase A, which range from protein labeling using fluorescence dyes and the preparation of cyclic proteins to the modification of entire cells, are summarized. Furthermore, there is a focus on the optimization approaches established to solve the drawbacks of sortase‐mediated transpeptidation.
Allosteric Binding of Capsaicin by a Bis(β‐cyclodextrin)‐2,2′‐bipyridine Receptor
Authors: Kremer Christopher , Lützen Arne 
Published: June 2014

AbstractA new β‐cyclodextrin‐based receptor that showed allosteric binding behavior towards capsaicin in aqueous solution was prepared. By NMR titration and nonlinear regression, we obtained binding constants, which increased more than fivefold when an effector (Zn2+) was bound to a central 2,2′‐bipyridine that acts as the allosteric center.
ChemInform Abstract: Variable Framework Structures and Centricities in Alkali Metal Yttrium Selenites, AY(SeO3)2 (A: Na, K, Rb, and Cs).
Authors: Bang Seong‐eun , Lee Dong Woo , Ok Kang Min 
Published: June 2014

AbstractSingle crystals of the title compounds are hydrothermally prepared from aqueous mixtures of Y(NO3)3, M2CO3 (M: Na, K, Rb, and Cs), and SeO2 (autoclave, 230 °C, 4 d, 98, 99, 99, and 90% yield for Na, K, Rb, and Cs compounds, resp.).
ChemInform Abstract: Immobilized Pd Complexes over HMMS as Catalysts for Heck Cross‐Coupling and Selective Hydrogenation Reactions.
Authors: Wang Peng , Liu Hengzhi , Liu Mengmeng , Li Rong , Ma Jiantai 
Published: June 2014

AbstractA novel Pd(0) compound immobilized on the surface of hollow magnetic mesoporous spheres, with Fe3O4 nanoparticles embedded in the mesoporous shell is prepared.
ChemInform Abstract: 2‐Arylacetic Anhydrides as Ammonium Enolate Precursors.
Authors: Morrill Louis C. , Ledingham Lyndsay A. , Couturier Jean‐Philippe , Bickel Jasmine , Harper Andrew D. , Fallan Charlene , Smith Andrew D. 
Published: June 2014

AbstractReadily prepared 2‐arylacetic anhydrides (I) act as convenient ammonium enolate precursors in isothiourea‐mediated catalytic asymmetric intermolecular Michael addition‐lactonization processes.
ChemInform Abstract: Diastereoselective Synthesis of a Highly Functionalized Cyclohexene Embedded with a Quaternary Stereogenic Centre by Self Diels—Alder Dimerization of a [3]Dendralene Attached to a (‐)‐Menthol Auxiliary.
Authors: Singh Rekha , Ghosh Sunil K. 
Published: June 2014

AbstractPhosphonate (I) is olefinated in a Horner‐Wadsworth‐Emmons reaction by para‐bromobenzaldehyde followed by a highly diastereoselective and spontaneous Diels—Alder dimerization.
ChemInform Abstract: Rh‐Catalyzed Allylic C—F Bond Activation: The Stereoselective Synthesis of Trisubstituted Monofluoroalkenes and a Mechanism Study.
Authors: Zhang He , Lin Jin‐Hong , Xiao Ji‐Chang , Gu Yu‐Cheng 
Published: June 2014

AbstractThe conversion of allylic difluoro‐homoallylic alcohols (I) into trisubstituted monofluoroalkenes (II)/(III) in good yields and with high stereoselectivity is described.