bluuebunny/crossref_metadata_2025 huggingface dataset:
Estimating surface temperature changes of lakes in the Tibetan Plateau using MODIS LST data
Authors: Zhang Guoqing , Yao Tandong , Xie Hongjie , Qin Jun , Ye Qinghua , Dai Yufeng , Guo Ruifang
Published: June 2014

Temperature changes over the Tibetan Plateau (TP) exhibit a dependence on altitude, as observed from meteorological station data and Moderate Resolution Imaging Spectroradiometer (MODIS) land surface temperature (LST) data. However, little is known about the changes in water surface temperature (WST) of lakes in the TP under the warming climate conditions over the past few decades. In this study, lake WST was examined using a MODIS/Terra 8 day LST (nighttime) product (MOD11A2) over the period 2001–2012. It was found that 52 lakes included in the analysis of WST exhibited an average rate of change of 0.012 ± 0.033°C/yr. Of these 52 lakes, 31 lakes (60%) displayed a temperature increase with a mean warming rate of 0.055 ± 0.033°C/yr and 21 lakes (40%) displayed a temperature decrease with a mean cooling rate of −0.053 ± 0.038°C/yr. The rates of change in WST for 13 lakes were statistically significant, and these included nine warming and four cooling lakes. Of the 17 lakes with nearby weather stations, nine lakes (53%) showed faster warming than nearby air/land. The warming lakes could be attributed to locally rising air and land surface temperatures as well as other factors such as the decreased lake ice cover. The cooling lakes were mostly located at high elevations (>4200 m), and the trend could have been due to increased cold water discharge to the lakes from accelerated glacier/snow melts. Therefore, both warming and cooling lake temperatures in the TP were possibly the result of increased air temperatures (0.036 ± 0.027°C/yr) under global warming conditions.
Dimethyl sulfide: Less important than long‐range transport as a source of sulfate to the remote tropical Pacific marine boundary layer
Authors: Simpson Rebecca M. C. , Howell Steven G. , Blomquist Byron W. , Clarke Antony D. , Huebert Barry J.
Published: June 2014

During the Pacific Atmospheric Sulfur Experiment (PASE), dimethyl sulfide (DMS) was not the principal source of non–sea salt sulfate (NSS) mass in the remote marine boundary layer (MBL), according to an Eulerian sulfur budget based on observations of chemical concentrations from the NCAR C‐130 in relatively dry, subsiding regions of the tropical Pacific. Our three (DMS, SO2, and NSS) monthly‐average budgets are mutually consistent. The PASE‐average DMS emission was 3.0 ± 0.5μmol m−2 d−1 (our budget “units”). SO2 sources include DMS + OH (1.4 ± 0.4 units, assuming 75% of reacted DMS forms SO2) and entrainment from the free troposphere (FT) (0.8 ± 0.2 units). Clouds were the most important chemical reactors for SO2 (−1.0 ± 0.5 units). SO2 loss terms also include divergence (−0.9 ± 0.3 units), dry deposition (−0.5 ± 0.2 units), and OH + SO2 (−0.22 ± 0.05 units). The total SO2 loss balanced the SO2 source. We assume that no SO2 was lost to ozone oxidation on sea salt particles; we found negligible NSS on particles from 2.6 μm (the sea salt mass peak) to 10 μm diameter. Fine‐particle NSS sources include in‐cloud oxidation of SO2 by H2O2 (1.0 ± 0.5 units), OH + SO2 (0.19 ± 0.05 units), and entrainment (1.1 ± 0.3 units in clean conditions; twice that when continental pollution is present). NSS sources balance NSS loss to divergence. Only about one fourth of emitted DMS becomes NSS. FT entrainment supplied two thirds and DMS oxidation produced one third of MBL NSS, rather similar source terms.
Systematic assessment of the uncertainty in integrated surface water‐groundwater modeling based on the probabilistic collocation method
Authors: Wu Bin , Zheng Yi , Tian Yong , Wu Xin , Yao Yingying , Han Feng , Liu Jie , Zheng Chunmiao
Published: June 2014

Systematic uncertainty analysis (UA) has rarely been conducted for integrated modeling of surface water‐groundwater (SW‐GW) systems, which is subject to significant uncertainty, especially at a large basin scale. The main objective of this study was to explore an innovative framework in which a systematic UA can be effectively and efficiently performed for integrated SW‐GW models of large river basins and to illuminate how process understanding, model calibration, data collection, and management can benefit from such a systematic UA. The framework is based on the computationally efficient Probabilistic Collocation Method (PCM) linked with a complex simulation model. The applicability and advantages of the framework were evaluated and validated through an integrated SW‐GW model for the Zhangye Basin in the middle Heihe River Basin, northwest China. The framework for systematic UA allows for a holistic assessment of the modeling uncertainty, yielding valuable insights into the hydrological processes, model structure, data deficit, and potential effectiveness of management. The study shows that, under the complex SW‐GW interactions, the modeling uncertainty has great spatial and temporal variabilities and is highly output‐dependent. Overall, this study confirms that a systematic UA should play a critical role in integrated SW‐GW modeling of large river basins, and the PCM‐based approach is a promising option to fulfill this role.
Luminescent Graphene Oxide with a Peptide‐Quencher Complex for Optical Detection of Cell‐Secreted Proteases by a Turn‐On Response
Authors: Kwak Seon‐Yeong , Yang Jin‐Kyoung , Jeon Su‐Ji , Kim Hye‐In , Yim Joonhyuk , Kang Homan , Kyeong San , Lee Yoon‐Sik , Kim Jong‐Ho
Published: June 2014

Graphene oxide (GO) is an emerging luminescent nanomaterial with photostable and unique photoluminescence (PL) in the visible and near‐infrared region. Herein, a GO PL‐based optical biosensor consisting of a luminescent GO donor covalently linked with a peptide‐quencher complex is reported for the simple, rapid, and sensitive detection of proteases. To this end, the quenching efficiency of various candidate quenchers of GO fluorescence, such as metalloprotoporphyrins and QXL570, are examined and their quenching mechanisms investigated. A fluorescence resonance energy transfer‐based quencher, QXL570, is found to be much more effective for quenching the intrinsic fluorescence of GO than other charge transfer‐based quenchers. The designed GO–peptide–QXL system is then able to sensitively detect specific proteases—chymotrypsin and matrix metalloproteinase‐2—via a “turn‐on” response of quenched GO fluorescence after proteolytic cleavage of the quencher. Finally, the GO–peptide–QXL hybrid successfully detects MMP‐2 secreted from living cells—human hepatocytes HepG2—with high sensitivity.
Nanometric Micelles with Photo‐Triggered Cytotoxicity
Authors: Anilkumar Parambath , Gravel Edmond , Theodorou Ioanna , Gombert Karine , Thézé Benoit , Ducongé Frédéric , Doris Eric
Published: June 2014

The development of a photo‐responsive micellar system capable of triggering cell death is reported. Precursors of the micelles are synthesized by connecting a lipophilic chain to a hydrophilic polyethylene glycol via a photo‐labile nitrobenzyl group. The resulting amphiphilic units are self‐assembled in water forming 12 nm micelles that are readily internalized into cells. Upon photo‐irradiation, micelles undergo cleavage and yield a cytotoxic nitrosobenzaldehyde derivative, which significantly inhibits the proliferation of MDA‐MB‐231 cells under standard in vitro conditions.
One‐Pot Synthesis of Hydroxamic Acids from Aldehydes and Hydroxylamine
Authors: Dettori Giovanna , Gaspa Silvia , Porcheddu Andrea , De Luca Lidia
Published: June 2014

A one‐pot oxidative transformation of aldehydes into hydroxamic acids by the use of an aqueous solution of hydroxylamine is reported. The methodology gives high yields and makes use of cheap, abundant and easily available reagents.

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Palladium‐Catalyzed Hydrophosphonylation of Alkenes with Dialkyl H‐Phosphonates
Authors: Candy Mathieu , Rousseaux Sophie A. L. , San Román Alberto Cirugeda , Szymczyk Monika , Kafarski Pawel , Leclerc Eric , Vrancken Emmanuel , Campagne Jean‐Marc
Published: June 2014

The palladium‐catalyzed hydrophosphonylation of alkenes with previously unreactive acyclic dialkyl H‐phosphonates has been developed. A catalyst system based on palladium/DavePhos or palladium/SPhos enables the transformation of various alkenes to phosphonates in moderate to good yields and with excellent levels of regioselectivity. Hydrophosphonylations with internal, disubstituted and/or unactivated alkenes are also reported.

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Recent Advances in Catalytic Functionalization of N‐Oxide Compounds via CH Bond Activation
Authors: Yan Guobing , Borah Arun Jyoti , Yang Minghua
Published: June 2014

N‐Oxide compounds are very important intermediates in synthetic organic chemistry as well as in the chemical industry. Numerous efforts have been devoted to the development of efficient approaches for the CH bond activation and functionalization of N‐oxides in recent years, including arylation, alkenylation, alkylation, acyloxylation, amination, amidation and sulfonylation. In this review, recent advances in this area are summarized and their mechanisms are discussed.

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Synthesis of Fully Substituted 3‐Formyl‐4‐iodofurans via a Gold(I)‐Catalyzed Oxidation/1,2‐Alkynyl Migration/Cyclization/Iodination Cascade
Authors: Wang Tao , Shi Shuai , Rudolph Matthias , Hashmi A. Stephen K.
Published: June 2014

A highly efficient gold(I)‐catalyzed cascade reaction for the synthesis of fully substituted 3‐formyl‐4‐iodofurans has been developed. Mechanistic investigations indicate a reaction pathway that involves a direct iodination reaction of the organogold intermediate via functionalization of the AuC(sp2) bond, instead of a direct iodination of the 3‐formylfurans.

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Temperature and Voltage Effect on Barrier Height and Ideality Factor in Au/PVC + TCNQ/p‐Si Structures
Authors: Kaya A. , Demirezen S. , Tecimer H. , Altindal Ş.
Published: June 2014

The forward bias current conduction mechanisms of Au/PVC + TCNQ/p‐Si structures have been investigated in a wide temperature range of 120–420 K for various applied bias voltage. The analysis of the main electrical parameters such as zero‐bias barrier height (BH) (ΦBo), ideality factor (n), and interface states (Nss) was found strongly dependent on temperature and voltage. The obtained results show that, while ΦBo increases, n decreases with increasing temperature. The plot of Φapp versus q/2kT was drawn to show a Gaussian distribution (GD) of the BHs, and this plot shows two distinct linear regions. The ΦBo and standard deviation (σs) values were found from the slope and intercept of these plots for two regions as 1.16 eV and 0.161 V for the first region and 0.71 eV and 0.093 V for the second region, respectively. Such behavior is typical of a double GD (DGD) of the BHs due to the BH inhomogeneities at the metal–semiconductor interface. The slope and intercept of the modified (ln(I0/T2) – q2σ02/2k2T2) versus q/kT plot gives the and ¯ΦBo and effective Richardson constant (A*) as 1.16 and 0.76 eV and 36.7 and 83.8 A/cm2K2, respectively. The value of the A* (36.7 A/cm2 K2) is very close to the theoretical value of 32 A/cm2 K2 for p‐Si. In addition, to interrupt the voltage‐dependent activation energy, the ln(Is/T2) versus q/kT plot was drawn in the voltage range of 0–0.3 V in 0.05 V steps. All of experimental results confirmed that the BH or Ea values depend on the temperature as well as bias voltages.
Postnatal growth velocity and overweight in early adolescents: A comparison of rural and urban African boys and girls
Authors: Chirwa E.D. , Griffiths P. , Maleta K. , Ashorn P. , Pettifor J.M. , Norris S.A.
Published: June 2014

Objectives

To compare growth velocity of two African child cohorts and examine the relationship between postnatal growth velocity in infancy/early childhood and the risk of overweight/stunting in early adolescence.

Methods

The study used data from two child cohorts from urban (Birth to Twenty Cohort, South Africa) and rural (Lungwena Child Survival Study, Malawi) African settings. Mixed effect modelling was used to derive growth and peak growth velocities. T‐tests were used to compare growth parameters and velocities between the two cohorts. Linear and logistic regression models were used to determine the relationship between growth velocity and early adolescent (ages 9–11 years) body mass index and odds of being overweight.

Results

Children in the BH cohort were significantly taller and heavier than those in the Lungwena cohort, and exhibited faster weight and height growth velocity especially in the first year of life (P < 0.05). No significant association was shown between baseline weight (αw) and overweight in early adolescence (OR = 1.25, CI = 0.67, 2.34). The weight growth velocity parameter βw was highly associated with odds of being overweight. Association between overweight in adolescence and weight velocity was stronger in infancy than in early childhood (OR at 3 months = 4.80, CI = 2.49, 9.26; OR at 5 years = 2.39, CI = 1.65, 3.47).

Conclusion

High weight and height growth velocity in infancy, independent of size at birth, is highly associated with overweight in early adolescence. However, the long term effects of rapid growth in infancy may be dependent on a particular population's socio‐economic status and level of urbanization. Am. J. Hum. Biol. 26:643–651, 2014. © 2014 The Authors American Journal of Human Biology Published by Wiley Periodicals, Inc.
Common variants in BDNF, FAIM2, FTO, MC4R, NEGR1, and SH2B1 show association with obesity‐related variables in Spanish Roma population
Authors: Poveda Alaitz , Ibáñez María Eugenia , Rebato Esther
Published: June 2014

Objectives

The objective of this study is to investigate the association between previously GWAS identified genetic variants predisposing to obesity in Europeans and obesity‐related phenotypes in Roma population.

Methods

A total of 24 representative single nucleotide polymorphisms (SNPs) were genotyped in 372 individuals belonging to 50 extended families of Roma population. SNPs were tested for association with seven quantitative obesity‐related phenotypes in the PLINK program.

Results

Risk variants in NEGR1, FAIM2, FTO, and SH2B1 genes were associated with increased adiposity accumulation in Roma population with effect sizes between 0.21 and 0.34 Z‐scores for each copy of the BMI increasing allele. Additionally, variants in BDNF and MC4R were significantly associated with adiposity distribution but not with overall fatness. No significant association was detected between obesity‐related phenotypes and variants in the first intron of the FTO gene (e.g., rs9939609).

Conclusions

The results of this study suggest that SNPs in or near six genes (BDNF, FAIM2, FTO, MC4R, NEGR1, and SH2B1) are significantly associated with body fat accumulation and distribution in Roma people. However, the association observed among variants in the first intron of FTO and obesity in European derived populations is not evident in the analyzed Roma sample. Am. J. Hum. Biol. 26:660–669, 2014. © 2014 Wiley Periodicals, Inc.
Hypersensitivity pneumonitis in workers exposed to metalworking fluids
Authors: Barber Christopher M. , Burton Clare M. , Hendrick David J. , Pickering C Anthony C. , Robertson Alastair S. , Robertson Wendy , Burge P Sherwood
Published: June 2014

Background

This study used data from a large UK outbreak investigation, to develop and validate a new case definition for hypersensitivity pneumonitis due to metalworking fluid exposure (MWF‐HP).

Methods

The clinical data from all workers with suspected MWF‐HP were reviewed by an experienced panel of clinicians. A new MWF‐HP Score was then developed to match the “gold standard” clinical opinion as closely as possible, using standard diagnostic criteria that were relatively weighted by their positive predictive value.

Results

The new case definition was reproducible, and agreed with expert panel opinion in 30/37 cases. This level of agreement was greater than with any of the three previously utilized case definitions (agreement in 16–24 cases). Where it was possible to calculate, the MWF‐HP Score also performed well when applied to 50 unrelated MWF‐HP cases.

Conclusions

The MWF‐HP Score offers a new case definition for use in future outbreaks. Am. J. Ind. Med. 57:872–880, 2014. © 2014 The Authors. American Journal of Industrial Medicine Published by Wiley Periodicals, Inc.
Development and validation of a SNP‐based assay for inferring the genetic ancestry of rhesus macaques (Macaca mulatta)
Authors: Kanthaswamy Sree , Johnson Zachary , Trask Jessica Satkoski , Smith David G. , Ramakrishnan Ranjani , Bahk Jason , Ng Jillian , Wiseman Roger , Kubisch H. Michael , Vallender Eric J. , Rogers Jeffrey , Ferguson Betsy
Published: June 2014

Rhesus macaques (Macaca mulatta) are an important primate model species in several areas of biomedical research. The wide geographic distribution of this species has led to significant genetic differentiation among local and regional populations. These regional differences can be important factors in the selection of the most appropriate subjects for particular research studies, as animals from different populations can respond differently to the same experimental treatment. Consequently, it is valuable to confirm the ancestry of individual rhesus monkeys from geographically distinct populations. Using DNA samples obtained from rhesus macaques from six National Primate Research Centers, we tested a set of 384 potential ancestry informative single nucleotide polymorphisms (SNPs) and identified a final panel of 91 SNPs that can reliably distinguish Indian‐origin from Chinese‐origin rhesus monkeys. This genetic test can be used to determine the ancestral origin of animals and to detect individuals that are hybrids between these two regional populations. To demonstrate use of the SNP panel, we investigated the ancestry of 480 animals from the Yerkes NPRC (YNPRC) for which the colony records were insufficient to clearly establish ancestry. Three of the YNPRC animals tested were determined to be hybrids. This SNP ancestry tool will be useful to researchers, colony managers, and others who wish to evaluate the ancestral origin of individual rhesus macaques, and therefore will facilitate more effective and efficient use of these animals in biomedical research. Am. J. Primatol. 76:1105–1113, 2014. © 2014 Wiley Periodicals, Inc.
Sources of tooth wear variation early in life among known‐aged wild ring‐tailed lemurs (Lemur catta) at the Bezà Mahafaly Special Reserve, Madagascar
Authors: Cuozzo Frank P. , Head Brian R. , Sauther Michelle L. , Ungar Peter S. , O'Mara M. Teague
Published: June 2014

Ring‐tailed lemurs (Lemur catta) at the Bezà Mahafaly Special Reserve (BMSR), Madagascar display a high frequency of individuals with notable and sometimes extreme tooth wear. Adult lemurs display a range of tooth wear even among individuals of the same age, but we do not know at what age this variation first appears. This study's goal was to determine whether wear variation occurs in younger wild lemurs. Based on the decade‐long study of ring‐tailed lemur feeding and dental ecology at BMSR, we hypothesized that younger, natal lemurs (under 5 years of age), would display variation in their degree of tooth wear that would correspond to microhabitat differences, given differences in food availability in different troops' home ranges. We also hypothesized that wear would differ between sexes at this young age, given differences in feeding between males and females in this population. Hypotheses were tested using dental topographic analyses using dental impressions collected from known‐aged lemurs across 10 years at BMSR. Results illustrate significant differences in wear‐related tooth topography (i.e., relief and slope, presented here as “occlusal lift”) for microhabitat, sex and troop affiliation among lemurs under 5 years of age in this population. Although, all lemurs in this population consume mechanically challenging tamarind fruit, those in more disturbed habitats eat additional introduced foods, some of which are also mechanically challenging. Thus, dietary variation is the likely cause of variation in tooth wear. The wear variation we show at a young age suggests caution when assigning age based on tooth wear in living and fossil primates. These wear‐related tooth shape changes early in life, which reflects sex, habitat variation and levels of anthropogenic disturbance, may potentially impact reproductive fitness later in life. Am. J. Primatol. 76:1037–1048, 2014. © 2014 Wiley Periodicals, Inc.
Nambu's Nobel Prize, the meson and the mass of visible matter
Authors: Schumacher Martin
Published: June 2014

The electroweak Higgs boson has been discovered in ongoing experiments at the LHC, leading to a mass of this particle of 126 GeV. This Higgs boson mediates the generation of mass for elementary particles, including the mass of elementary (current) quarks. These current‐quark masses leave 98% of the mass of the atom unexplained. This large fraction is mediated by strong interaction, where instead of the Higgs boson the σ meson is the mediating particle. Though already introduced in 1957 by Schwinger, the σ meson has been integrated out in many theories of hadron properties because it had not been observed and was doubted to exist. With the observation of the σ meson in recent experiments on Compton scattering by the nucleon at MAMI (Mainz) it has become timely to review the status of experimental and theoretical researches on this topic.
Evading the Goldstone theorem
Authors: Higgs Peter W.
Published: June 2014

Peter W. Higgs describes in detail his interest from 1960 in the work of Nambu and Goldstone and the background events leading to the papers of 1964 that showed how one can evade the Goldstone theorem using a gauge theory. He also discusses how these ideas have been developed by others to culminate in the electroweak theory of the Standard Model.
Heterogenität der Luft/Wasser‐Grenzfläche gezeigt durch 2D‐HD‐SFE‐Spektroskopie
Authors: Hsieh Cho‐Shuen , Okuno Masanari , Hunger Johannes , Backus Ellen H. G. , Nagata Yuki , Bonn Mischa
Published: June 2014

Wassermoleküle wechselwirken stark miteinander durch Wasserstoffbrücken. Diese effiziente intermolekulare Kopplung verursacht eine starke Delokalisierung der Molekülschwingungen im Inneren des Wassers. Wir untersuchen die intermolekulare Kopplung der Schwingungen an der Luft/Wasser‐Grenzfläche und beobachten, dass die intermolekulare Kopplung 1) signifikant reduziert ist und 2) für verschiedene Wassermoleküle an der Grenzfläche stark variiert – während im Inneren des Wassers die Kopplung homogen ist. Für stark Wasserstoffbrücken‐gebundene O‐H‐Gruppen ist die Kopplung etwa zweimal geringer als im Inneren des Wassers, aufgrund der geringeren Dichte in der grenzflächennahen Region. Für schwach Wasserstoffbrücken‐gebundene O‐H‐Gruppen, die bei 3500 cm−1 absorbieren, ist diese Kopplung um einen weiteren Faktor ≈2 reduziert. Diese O‐H‐Gruppen werden den äußersten, jedoch Wasserstoffbrücken‐gebundenen Wassermolekülen zugeordnet, deren andere O‐H‐Gruppe zur Gasphase zeigt. Trotz der geringen strukturellen Einschränkungen durch die umgebenden Wasserstoffbrücken auf diese Wassermoleküle ist – bemerkenswerterweise – deren Strukturrelaxation langsam und die intermolekulare Kopplung schwach.
Two‐Coordinate Fe0 and Co0 Complexes Supported by Cyclic (alkyl)(amino)carbenes
Authors: Ung Gaël , Rittle Jonathan , Soleilhavoup Michele , Bertrand Guy , Peters Jonas C.
Published: June 2014

The CAAC [CAAC=cyclic (alkyl)(amino)carbene] family of carbene ligands have shown promise in stabilizing unusually low‐coordination number transition‐metal complexes in low formal oxidation states. Here we extend this narrative by demonstrating their utility in affording access to the first examples of two‐coordinate formal Fe0 and Co0 [(CAAC)2M] complexes, prepared by reduction of their corresponding two‐coordinate cationic FeI and CoI precursors. The stability of these species arises from the strong σ‐donating and π‐accepting properties of the supporting CAAC ligands, in addition to steric protection.
Redox and Anion Exchange Chemistry of a Stibine–Nickel Complex: Writing the L, X, Z Ligand Alphabet with a Single Element
Authors: Jones James S. , Wade Casey R. , Gabbaï François P.
Published: June 2014

According to the covalent bond classification (CBC) method, two‐electron donors are defined as L‐type ligands, one‐electron donors as X‐type ligands, and two‐electron acceptors as Z‐type ligands. These three ligand functions are usually associated to the nature of the ligating atom, with phosphine, alkyl, and borane groups being prototypical examples of L‐, X‐ and Z‐ligands, respectively. A new SbNi platform is reported in which the ligating Sb atom can assume all three CBC ligand functions. Using both experimental and computational data, it is shown that PhICl2 oxidation of (o‐(Ph2P)C6H4)3SbNi(PPh3) (1) into [(o‐(Ph2P)C6H4)3ClSb]NiCl (2) is accompanied by a conversion of the stibine L‐type ligand of 1 into a stiboranyl X‐type ligand in 2. Furthermore, the reaction of 2 with the catecholate dianion in the presence of cyclohexyl isocyanide results in the formation of [(o‐(Ph2P)C6H4)3(o‐O2C6H4Sb)]Ni(CNCy) (4), a complex featuring a nickel atom coordinated by a Lewis acidic, Z‐type, stiborane ligand.
Ein‐, Zwei‐ und Drei‐Elektronen‐Reduktion eines CAAC‐SbCl3‐ Addukts
Authors: Kretschmer Robert , Ruiz David A. , Moore Curtis E. , Rheingold Arnold L. , Bertrand Guy
Published: June 2014

Die Reaktion eines cyclischen Alkyl(amino)carbens mit SbCl3 führt zur Bildung des entsprechenden SbIII‐Addukts. Durch Ein‐Elektronen‐Reduktion kann daraus das erste Beispiel eines neutralen Antimon‐zentrierten Radikals in Lösung erhalten werden. Zwei‐Elektronen‐Reduktion führt zu einem Lewis‐Base‐stabilisierten Chlorstibiniden, und Drei‐Elektronen‐Reduktion ergibt schließlich eine diatomare Antimonspezies, die durch zwei Carbene stabilisiert ist. Das Radikal wurde mit EPR‐Spektroskopie charakterisiert, während die Strukturen der anderen drei Verbindungen durch Einkristall‐Röntgenbeugung bestimmt wurden. In diesen vier Spezies fällt die formale Oxidationsstufe des Metalloids von III auf II, auf I und schließlich auf 0.
Organocatalytic Asymmetric Hydrolysis of Epoxides
Authors: Monaco Mattia Riccardo , Prévost Sébastien , List Benjamin
Published: June 2014

The hydrolytic ring opening of epoxides is an important biosynthetic transformation and is also applied industrially. We report the first organocatalytic variant of this reaction, exploiting our recently discovered activation of carboxylic acids with chiral phosphoric acids via heterodimerization. The methodology mimics the enzymatic mechanism, which involves an enzyme‐bound carboxylate nucleophile. A newly designed phosphoric acid catalyst displays high stereocontrol in the desymmetrization of meso‐epoxides. The methodology shows wide generality with cyclic, acylic, aromatic, and aliphatic substrates. We also apply our method in the first highly enantioselective anti‐dihydroxylation of simple olefins.
Exploring Bis(cyclometalated) Ruthenium(II) Complexes as Active Catalyst Precursors: Room‐Temperature Alkene–Alkyne Coupling for 1,3‐Diene Synthesis
Authors: Zhang Jing , Ugrinov Angel , Zhang Yong , Zhao Pinjing
Published: June 2014

Described is the development of a new class of bis(cyclometalated) ruthenium(II) catalyst precursors for CC coupling reactions between alkene and alkyne substrates. The complex [(cod)Ru(3‐methallyl)2] reacts with benzophenone imine or benzophenone in a 1:2 ratio to form bis(cyclometalated) ruthenium(II) complexes (1). The imine‐ligated complex 1 a promoted room‐temperature coupling between acrylic esters and amides with internal alkynes to form 1,3‐diene products. A proposed catalytic cycle involves CC bond formation by oxidative cyclization, β‐hydride elimination, and CH bond reductive elimination. This RuII/RuIV pathway is consistent with the observed catalytic reactivity of 1 a for mild tail‐to‐tail methyl acrylate dimerization and for cyclobutene formation by [2+2] norbornene/alkyne cycloaddition.
Aqueous Heterogeneity at the Air/Water Interface Revealed by 2D‐HD‐SFG Spectroscopy
Authors: Hsieh Cho‐Shuen , Okuno Masanari , Hunger Johannes , Backus Ellen H. G. , Nagata Yuki , Bonn Mischa
Published: June 2014

Water molecules interact strongly with each other through hydrogen bonds. This efficient intermolecular coupling causes strong delocalization of molecular vibrations in bulk water. We study intermolecular coupling at the air/water interface and find intermolecular coupling 1) to be significantly reduced and 2) to vary strongly for different water molecules at the interface—whereas in bulk water the coupling is homogeneous. For strongly hydrogen‐bonded OH groups, coupling is roughly half of that of bulk water, due to the lower density in the near‐surface region. For weakly hydrogen‐bonded OH groups that absorb around 3500 cm−1, which are assigned to the outermost, yet hydrogen‐bonded OH groups pointing towards the liquid, coupling is further reduced by an additional factor of 2. Remarkably, despite the reduced structural constraints imposed by the interfacial hydrogen‐bond environment, the structural relaxation is slow and the intermolecular coupling of these water molecules is weak.
Continuous Flow Magnesiation of Functionalized Heterocycles and Acrylates with TMPMgCl⋅LiCl
Authors: Petersen Trine P. , Becker Matthias R. , Knochel Paul
Published: June 2014

A flow procedure for the metalation of functionalized heterocycles (pyridines, pyrimidines, thiophenes, and thiazoles) and various acrylates using the strong, non‐nucleophilic base TMPMgCl⋅LiCl is reported. The flow conditions allow the magnesiations to be performed under more convenient conditions than the comparable batch reactions, which often require cryogenic temperatures and long reaction times. Moreover, the flow reactions are directly scalable without further optimization. Metalation under flow conditions also allows magnesiations that did not produce the desired products under batch conditions, such as the magnesiation of sensitive acrylic derivatives. The magnesiated species are subsequently quenched with various electrophiles, thereby introducing a broad range of functionalities.
Mixed bis(morpholine‐4‐dithiocarbamato‐S,S′)antimony(III) complexes: synthesis, characterization and biological studies
Authors: Chauhan H. P. S. , Carpenter Jaswant , Joshi Sapana
Published: June 2014

Some mixed bis(morpholine‐4‐dithiocarbamato‐S,S′)antimony(III) complexes [(OC4H8NCS2)2SbL] with oxygen or sulfur donor ligands [L= ―OOCCH3(1), ―OOCC6H5(2), ―SOCCH3(3), ―SCH2COOH (4), ―OOCC6H4(OH) (5), ―SCH2CH2CH3(6), ―OC6H5(7), ½ ―SCH2CH2S― (8)] have been synthesized by reacting the chloro‐bis(morpholine‐4‐dithiocarbamato‐S,S′)antimony(III) with corresponding oxygen or sulfur donor ligands in 1:1 or 2:1 stoichiometries. These have been characterized by melting point, molecular weight determination (cryoscopically), antimony (iodometrically) and sulfur (gravimetrically) estimation, elemental analyses (C, H and N), UV–visible, FT‐IR, far IR, multinuclear NMR (1H and13C)], TG/DTA analysis, ESI–mass and powder X‐ray diffraction studies. The splitting of the strong band observed at 1046–1066 cm−1due to υ(C―S) indicated anisobidentate mode of binding of the dithiocarbamate group, which was further supported by a13C NMR signal appearing at aroundδ200 due to NCS2moiety. The base peak observed atm/z444.9 supports the strong chelating nature of the morpholine‐4‐dithiocarbamate compared to the other hetero ligands used. TGA revealed that, complexes 21 and4were decomposed in three steps; also6was decomposed in two steps, followed by the formation of Sb2S3. The results obtained by antimicrobial screening tests indicate that complex3showed a maximum zone of inhibition (20 mm) againstTrichoderma ressieat a concentration of 200 µg ml−1. Complexes2,3and8are most active (zone of inhibition (ZI) 17–20 mm) against both of the fungal speciesAspergillus nigerandTrichoderma ressieas well as complex4(ZI 17 mm) and6(ZI 18 mm) againstTrichoderma ressie. Copyright © 2014 John Wiley & Sons, Ltd.
NaOH modified P(acrylamide) hydrogel matrices for in situ metal nanoparticles preparation and their use in H2 generation from hydrolysis of NaBH4
Authors: Seven Fahriye , Sahiner Nurettin
Published: June 2014

Crosslinked poly(acrylamide) (p(AAm)) as neutral hydrogel is synthesized via photo polymerization technique, and the amide groups within p(AAm) matrices are converted to strongly ionizable carboxylic acids groups via facile modification route by simple treatment of NaOH to obtained NaOH‐p(AAm) hydrogels. Because of the highly ionizable nature of carboxylate groups within mod‐p(AAm), the swelling and metal ion absorbing capacities are increased tremendously, almost 40 and 7.5 folds, respectively. The Co(II) and Ni(II) metal ions are loaded into NaOH‐p(AAm) hydrogels, and are treated with NaBH4 to form corresponding metal nanoparticles in situ within mod‐p(AAm) matrices, and used in H2 generation production from hydrolysis of NaBH4. Various parameters such as functionality of polymeric matrices, the kinds and the amount of metal nanoparticles, and the temperature effecting the H2 generation are investigated. Comparable low Ea with the similar researches in the literature, Ea = 20.07 ± 0.05 kJ mol−1 is obtained in NaBH4 hydrolysis catalyzed by NaOH‐p(AAM)‐Co composite system. © 2014 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2014, 131, 41106.
Abundance and movements of sperm whales in the western Mediterranean basin
Authors: Rendell L. , Simião S. , Brotons J. M. , Airoldi S. , Fasano D. , Gannier A.
Published: June 2014

Sperm whales in the Mediterranean are classified as ‘Endangered’ by the IUCN. They are apparently isolated from adjacent Atlantic populations, and subject to anthropogenic pressures including interactions with illegal driftnet fisheries, ship strikes, ingestion of debris and underwater noise.

Photo‐identification data opportunistically collected from the western Mediterranean basin show that individual sperm whales regularly move in excess of 500 km across the western basin, suggesting that this area is occupied by a single population.

The best abundance estimate for this region is approximately 400 animals, with confidence intervals between 200 and 1000.

Given the mortality levels reported in the literature, this figure suggests that the conservation status of sperm whales in this region is very serious. Immediate priority should be placed both on conducting systematic surveys for abundance estimation and on measures to reduce the mortality associated with driftnet fishing.

Copyright © 2014 John Wiley & Sons, Ltd.
Photo‐identification of sperm whales in the north‐western Mediterranean Sea: an assessment of natural markings
Authors: Alessi Jessica , Aïssi Mehdi , Fiori Cristina
Published: June 2014

Photo‐identification is an important, non‐invasive tool that can be used to obtain data about cetacean population dynamics that are essential for proper environmental management. A standardized protocol is crucial for obtaining optimal results, particularly for long‐lived and highly migratory species such as sperm whales (Physeter macrocephalus) but also to study resident populations.

Photo‐identification of individuals using natural marks has been widely used to study sperm whales in the Mediterranean Sea. However, the prevalence of the marks used for identification is unknown. Thus, the goal of this study was to identify which mark types are most useful for identifying individual sperm whales.

A photo‐identification catalogue of sperm whales from the north‐western Mediterranean Sea was produced and examined to determine the most frequent mark types present on whales in the study area. Mark types and their distribution were described, prevalence and the size of each mark type were calculated, variability in visibility was investigated, and gain and loss rates were analysed.

Analysis of natural pigmentation may characterize sperm whale flanks in this study area as the best and most convenient element on which matching technique can be based. Indeed, this technique led to the identification of 97% of photographed individuals.

Copyright © 2014 John Wiley & Sons, Ltd.
Ecotoxicological status of seven sperm whales (Physeter macrocephalus) stranded along the Adriatic coast of Southern Italy
Authors: Marsili Letizia , Maltese Silvia , Coppola Daniele , Carletti Laura , Mazzariol Sandro , Fossi M. Cristina
Published: June 2014

In December 2009 seven male sperm whales (Physeter macrocephalus) stranded along the Adriatic coast of Southern Italy. Genetic and photo‐identification data indicated that these specimens belonged to the Mediterranean Sea population.

Complete necropsies were performed on the three best preserved animals. Blubber and muscle samples were collected from all seven specimens for contaminants analysis (DDTs, PCBs and PAHs) and biomarker responses (CYP1A1 and CYP2B) were evaluated from the three better preserved animals using western blot analysis.

Fibroblast cell cultures from two specimens were set up by culturing cell lines from integument tissue, to explore the susceptibility of these marine mammals to different xenobiotic compounds.

The levels of CYP1A1 and CYP2B, proteins that are induced by some POPs (DDTs and PCBs) and PAHs were detected using the indirect immunofluorescence assay. The results showed relatively high levels of contaminants, in particular from organochlorine xenobiotics, and strong responses of CYP1A1 and CYP2B reflecting toxicological stress of these sperm whales.

This is not considered to be their cause of death, but may have contributed to lowering the defences of their immune system.

Copyright © 2014 John Wiley & Sons, Ltd.
Spatial abilities of medical graduates and choice of residency programs
Authors: Langlois Jean , Wells George A. , Lecourtois Marc , Bergeron Germain , Yetisir Elizabeth , Martin Marcel
Published: June 2014

Spatial abilities have been related in previous studies to three‐dimensional (3D) anatomy knowledge and the performance in technical skills. The objective of this study was to relate spatial abilities to residency programs with different levels of content of 3D anatomy knowledge and technical skills. The hypothesis was that the choice of residency program is related to spatial abilities. A cohort of 210 medical graduates was enrolled in a prospective study in a 5‐year experiment. Spatial abilities were measured with a redrawn Vandenberg and Kuse Mental Rotations Test (MRT) in two (MRTA) and three (MRTC) dimensions. Medical graduates were enrolled in Family Medicine (n = 76, 36.2%), Internal Medicine (64, 30.5%), Surgery (52, 24.8%), and Anesthesia (18, 8.6%). The assumption was that the level of 3D anatomy knowledge and technical skills content was higher in Surgery and Anesthesia compared to Family Medicine and Internal Medicine. Mean MRTA score of 12.4 (±SD 4.6), 12.0 (±4.3), 14.1 (±4.3), and 14.6 (±4.0) was obtained in Family Medicine, Internal Medicine, Surgery, and Anesthesia, respectively (P = 0.0176). Similarly, mean MRTC score of 8.0 (±4.4), 7.5 (±3.6), 8.5 (±3.9), and 7.9 (±4.1) was obtained (P = 0.5647). Although there was a tendency for lower MRTA score in Family Medicine and Internal Medicine compared to Surgery and Anesthesia, no statistically significant main effect of residency, year, sex, or the interactions were observed for the MRTA and MRTC. Studied sample of medical graduates was not found to choose their residency programs based on their innate spatial abilities. Anat Sci Educ 8: 111–119. © 2014 American Association of Anatomists.
Stereoselective Bromocyclization of Allylated Aldoxime Ethers
Authors: Egart Boris , Czekelius Constantin
Published: June 2014

The intramolecular bromoamination of allylated aldoxime ethers leads first to isoxazolidinium salts which then undergo a skeletal rearrangement to form bromo‐5,6‐dihydro‐4H‐1,3‐oxazines. Aliphatic aldoxime ethers with α‐protons undergo multiple brominations before rearrangement.
Small area estimation for semicontinuous data
Authors: Chandra Hukum , Chambers Ray
Published: June 2014

Survey data often contain measurements for variables that are semicontinuous in nature, i.e. they either take a single fixed value (we assume this is zero) or they have a continuous, often skewed, distribution on the positive real line. Standard methods for small area estimation (SAE) based on the use of linear mixed models can be inefficient for such variables. We discuss SAE techniques for semicontinuous variables under a two part random effects model that allows for the presence of excess zeros as well as the skewed nature of the nonzero values of the response variable. In particular, we first model the excess zeros via a generalized linear mixed model fitted to the probability of a nonzero, i.e. strictly positive, value being observed, and then model the response, given that it is strictly positive, using a linear mixed model fitted on the logarithmic scale. Empirical results suggest that the proposed method leads to efficient small area estimates for semicontinuous data of this type. We also propose a parametric bootstrap method to estimate the MSE of the proposed small area estimator. These bootstrap estimates of the MSE are compared to the true MSE in a simulation study.
Metabolite of tryptophan promoting changes in EEG signal and the oxidative status of the brain
Authors: Ferrari Rosana , Pugini Silvana Maria Picolli , Arce Aldo Ivan Cespedes , Costa Ernane Jose Xavier , de Melo Mariza Pires
Published: June 2014

Tryptophan is an essential amino acid precursor of neurotransmitter serotonin and triptamine. During its metabolism, indole‐3‐acetic acid (IAA) is generated; this substance presents both antioxidant and prooxidant effects in different biological systems in addition to hipoglicemic effects. To date, electroencephalography (EEG) has been used to evaluate the temporal effect of several substances in neurotransmission. The goal of this study was to characterize the effect of IAA in the brain by analysing the EEG signal and evaluate the oxidative status by means of biochemical parameters. The EEG was acquired by using a noninvasive method, and the brain electric signal was analysed by advanced digital signal processing techniques to determinate the energy signal filtered in different band frequencies. Furthermore, the oxidative status of the brain was investigated by measuring the activity of antioxidant enzymes and lipid peroxidation as well as blood glucose rates of the animals treated with different doses of IAA. Our results showed the relationship of IAA administration with changes in EEG signals. The oxidative status of the brain was modified by IAA after 14 days of treatment. Copyright © 2014 John Wiley & Sons, Ltd.
Sequence Elements Distal to the Ligand Binding Pocket Modulate the Efficiency of a Synthetic Riboswitch
Authors: Weigand Julia E. , Gottstein‐Schmidtke Sina R. , Demolli Shemsi , Groher Florian , Duchardt‐Ferner Elke , Wöhnert Jens , Suess Beatrix
Published: June 2014

Synthetic riboswitches can serve as sophisticated genetic control devices in synthetic biology, regulating gene expression through direct RNA–ligand interactions. We analyzed a synthetic neomycin riboswitch, which folds into a stem loop structure with an internal loop important for ligand binding and regulation. It is closed by a terminal hexaloop containing a U‐turn and a looped‐out adenine. We investigated the relationship between sequence, structure, and biological activity in the terminal loop by saturating mutagenesis, ITC, and NMR. Mutants corresponding to the canonical U‐turn fold retained biological activity. An improvement of stacking interactions in the U‐turn led to an RNA element with slightly enhanced regulatory activity. For the first position of the U‐turn motif and the looped out base, sequence–activity relationships that could not initially be explained on the basis of the structure of the aptamer–ligand complex were observed. However, NMR studies of these mutants revealed subtle relationships between structure and dynamics of the aptamer in its free or bound state and biological activity.
Regio‐Selective Chemical‐Enzymatic Synthesis of Pyrimidine Nucleotides Facilitates RNA Structure and Dynamics Studies
Authors: Alvarado Luigi J. , LeBlanc Regan M. , Longhini Andrew P. , Keane Sarah C. , Jain Niyati , Yildiz Zehra F. , Tolbert Blanton S. , D'Souza Victoria M. , Summers Michael F. , Kreutz Christoph , Dayie T. Kwaku
Published: June 2014

Isotope labeling has revolutionized NMR studies of small nucleic acids, but to extend this technology to larger RNAs, site‐specific labeling tools to expedite NMR structural and dynamics studies are required. Using enzymes from the pentose phosphate pathway, we coupled chemically synthesized uracil nucleobase with specifically 13C‐labeled ribose to synthesize both UTP and CTP in nearly quantitative yields. This chemoenzymatic method affords a cost‐effective preparation of labels that are unattainable by current methods. The methodology generates versatile 13C and 15N labeling patterns which, when employed with relaxation‐optimized NMR spectroscopy, effectively mitigate problems of rapid relaxation that result in low resolution and sensitivity. The methodology is demonstrated with RNAs of various sizes, complexity, and function: the exon splicing silencer 3 (27 nt), iron responsive element (29 nt), Pro‐tRNA (76 nt), and HIV‐1 core encapsidation signal (155 nt).
Mechanisms of hippocampal astrocytes mediation of spatial memory and theta rhythm by gliotransmitters and growth factors
Authors: Hassanpoor Hossein , Fallah Ali , Raza Mohsin
Published: June 2014

Our knowledge about encoding and maintenance of spatial memory emphasizes the integrated functional role of the grid cells and the place cells of the hippocampus in the generation of theta rhythm in spatial memory formation. However, the role of astrocytes in these processes is often underestimated in their contribution to the required structural and functional characteristics of hippocampal neural network operative in spatial memory. We show that hippocampal astrocytes, by the secretion of gliotransmitters, such as glutamate, d‐serine, and ATP and growth factors such as BDNF and by the expression of receptors and channels such as those of TNFα and aquaporin, have several diverse fuctions in spatial memory. We specifically focus on the role of astrocytes on five phases of spatial memory: (1) theta rhythm generation, (2) theta phase precession, (3) formation of spatial memory by mapping data of entorhinal grid cells into the place cells, (4) storage of spatial information, and (5) maintenance of spatial memory. Finally, by reviewing the literature, we propose specific mechanisms mentioned in the form of a hypothesis suggesting that astrocytes are important in spatial memory formation.