bluuebunny/crossref_metadata_2025 huggingface dataset:
pH- and sodium-induced changes in a sodium/proton antiporter
Authors: Paulino Cristina , Kühlbrandt Werner
Published: January 2014

We examined substrate-induced conformational changes in MjNhaP1, an archaeal electroneutral Na+/H+-antiporter resembling the human antiporter NHE1, by electron crystallography of 2D crystals in a range of physiological pH and Na+ conditions. In the absence of sodium, changes in pH had no major effect. By contrast, changes in Na+ concentration caused a marked conformational change that was largely pH-independent. Crystallographically determined, apparent dissociation constants indicated ∼10-fold stronger Na+ binding at pH 8 than at pH 4, consistent with substrate competition for a common ion-binding site. Projection difference maps indicated helix movements by about 2 Å in the 6-helix bundle region of MjNhaP1 that is thought to contain the ion translocation site. We propose that these movements convert the antiporter from the proton-bound, outward-open state to the Na+-bound, inward-open state. Oscillation between the two states would result in rapid Na+/H+ antiport.
Single-molecule analysis reveals self assembly and nanoscale segregation of two distinct cavin subcomplexes on caveolae
Authors: Gambin Yann , Ariotti Nicholas , McMahon Kerrie-Ann , Bastiani Michele , Sierecki Emma , Kovtun Oleksiy , Polinkovsky Mark E , Magenau Astrid , Jung WooRam , Okano Satomi , Zhou Yong , Leneva Natalya , Mureev Sergey , Johnston Wayne , Gaus Katharina , Hancock John F , Collins Brett M , Alexandrov Kirill , Parton Robert G
Published: January 2014

In mammalian cells three closely related cavin proteins cooperate with the scaffolding protein caveolin to form membrane invaginations known as caveolae. Here we have developed a novel single-molecule fluorescence approach to directly observe interactions and stoichiometries in protein complexes from cell extracts and from in vitro synthesized components. We show that up to 50 cavins associate on a caveola. However, rather than forming a single coat complex containing the three cavin family members, single-molecule analysis reveals an exquisite specificity of interactions between cavin1, cavin2 and cavin3. Changes in membrane tension can flatten the caveolae, causing the release of the cavin coat and its disassembly into separate cavin1-cavin2 and cavin1-cavin3 subcomplexes. Each of these subcomplexes contain 9 ± 2 cavin molecules and appear to be the building blocks of the caveolar coat. High resolution immunoelectron microscopy suggests a remarkable nanoscale organization of these separate subcomplexes, forming individual striations on the surface of caveolae.
Earlier menarche is associated with a higher prevalence of Herpes simplex type-2 (HSV-2) in young women in rural Malawi
Authors: Glynn Judith R , Kayuni Ndoliwe , Gondwe Levie , Price Alison J , Crampin Amelia C
Published: January 2014

Remarkably little is known about associations between age at menarche and sexually transmitted infections, although girls with earlier menarche tend to have earlier sexual debut and school drop-out, so an association might be expected. In a population-based survey of >3000 women aged 15–30 in northern Malawi we show that those with earlier menarche had earlier sexual debut, earlier marriage and were more often Herpes simplex type-2 (HSV-2) positive. Compared to those with menarche aged <14, the age-adjusted odds ratios for HSV-2 were 0.89 (95%CI 0.71–1.1), 0.71 (0.57–0.89) and 0.69 (0.54–0.89) for menarche aged 14, 15 and 16+ respectively. This association persisted after adjusting for socio-economic factors, including schooling, and for sexual behaviour. No such association was seen with HIV infection, which is much less common and less uniformly distributed than HSV-2 in this population. The extra vulnerability of girls with earlier menarche needs to be recognised.
How HIV-1 Nef hijacks the AP-2 clathrin adaptor to downregulate CD4
Authors: Ren Xuefeng , Park Sang Yoon , Bonifacino Juan S , Hurley James H
Published: January 2014

The Nef protein of HIV-1 downregulates the cell surface co-receptor CD4 by hijacking the clathrin adaptor complex AP-2. The structural basis for the hijacking of AP-2 by Nef is revealed by a 2.9 Å crystal structure of Nef bound to the α and σ2 subunits of AP-2. Nef binds to AP-2 via its central loop (residues 149–179) and its core. The determinants for Nef binding include residues that directly contact AP-2 and others that stabilize the binding-competent conformation of the central loop. Residues involved in both direct and indirect interactions are required for the binding of Nef to AP-2 and for downregulation of CD4. These results lead to a model for the docking of the full AP-2 tetramer to membranes as bound to Nef, such that the cytosolic tail of CD4 is situated to interact with its binding site on Nef.
Effect of fracture roughness on seismic source and fluid transport responses
Authors: Raziperchikolaee S. , Alvarado V. , Yin S.
Published: January 2014

To explain how fracture roughness affects seismic source and transport response of deformed fractured rock, we developed a microscale fluid flow‐geomechanics‐seismicity model. The modeling method considers comprehensive grains and cement interactions. Fluid flow behavior is obtained through realistic network models of the pore space in the compacted assembly. In addition, forces and displacements in the grains involved in the bond breakage are measured to determine seismic moment tensor. The results of our work show that in addition to stress conditions in the target formation, geological properties of preexisting fractures affect volumetric deformation of the seismic source as well. The results of the model proves that roughness of fractures, applied in a Berea sample, causes deviation of source mechanism of acoustic emission events toward opening tensile part and enhances the permeability of the sample significantly during its failure even under confining pressure.
Observations of large infragravity wave runup at Banneg Island, France
Authors: Sheremet Alex , Staples Tracy , Ardhuin Fabrice , Suanez Serge , Fichaut Bernard
Published: January 2014

On Banneg Island, France, very high water‐level events (6.5 m above the astronomical tide) have been observed on the western cliff, exposed to large swells from the North Atlantic. The analysis of hydrodynamic measurements collected during the storm of 10 February 2009 shows unusually high (over 2 m) infragravity wave runup events. By comparing runup observations to measurements in approximately 7 m of water and numerical simulations with a simplified nonlinear model, two distinct infragravity bands may be identified: an 80 s infragravity wave, produced by nonlinear shoaling of the storm swell; and a 300 s wave, trapped on the intertidal platform of the island and generating intermittent, low‐frequency inundation. Our analysis shows that the 300 s waves are a key component of the extreme water levels recorded on the island.
Evolution of an oceanic anticyclone in the lee of Madeira Island: In situ and remote sensing survey
Authors: Caldeira Rui M. A. , Stegner Alexandre , Couvelard Xavier , Araújo Isabel B. , Testor Pierre , Lorenzo Alvaro
Published: January 2014

Island wakes are areas of a strong eddy activity influencing the availability and transport of organic matter in the ocean which, in turn impact biological productivity. Despite this, eddy formation in the lee of North Atlantic tropical islands is scarcely documented, except for the Canary Islands. Moreover, the occurrence of anticyclones leeward of Madeira has seldom been detected. During the summer of 2011, a multiplatform approach, combining satellite data with in situ measurements, was used to study an anticyclonic eddy generated in the lee of the Madeira Island. The main objective was to confirm recent numerical evidence suggesting that orographically perturbed winds can induce anticyclonic eddies leeward of Madeira, particularly during summer months. The high resolution sampling of the eddy's interior shows a strong downwelling of ≈100 m of the isopycnal layer below the mixed layer, typical of intrathermocline eddies. The 25 km radius of this anticyclonic structure exceeds the local deformation radius by a factor of 2. The vortex Rossby number remained moderate (Ro = 0.26) even if the relative core vorticity reached a finite value (ζ/f = −0.7). The occurrence of strong trade winds (10–15 m s−1) prior to the detection of the first surface eddy signatures (July 2011) concurrent with opposite flowing geostrophic currents, shows that the orographic wind forcing is the main mechanism for generating this mesoscale long‐lived eddy. After leaving the shelter of the island, the eddy traveled northwesterly following a perpendicular net Ekman transport pathway at a speed of 5 km/d, for at least 2 months. An interaction with a cyclonic partner generated in the area helped precipitate the northward trajectory. This study presents the first clear evidence of a wind‐induced mesoscale anticyclone in the lee of Madeira.
New high‐resolution record of middle to late Miocene climate evolution
Authors: Balcerak Ernie
Published: January 2014

After the fairly warm Miocene climate optimum about 17–15 million years ago, Earth's climate began to cool. Holbourn et al. present a new high‐resolution record of climate evolution over the middle to late Miocene, from 12.9 to 8.4 million years ago, based on stable isotopes in sedimentary benthic foraminifera in the western Pacific Ocean. They also combined their data with previously published data going back to 16 million years ago from the same location to study the transition from a warmer climate to a cooler one. They focus on the relationship between climate and changes in the eccentricity and obliquity of Earth's orbit around the Sun.
Eliminating error in satellite observations of surface elevation
Authors: Schultz Colin
Published: January 2014

From 2003 to 2009, NASA's Ice, Cloud, and Land Elevation Satellite (ICESat) captured detailed elevation measurements of the Earth's surface. Unfortunately, as with all instruments, ICESat's observations experienced sensor drift throughout its lifetime, a changing bias that introduced error into the satellite's observations. Correcting for such creeping biases is difficult but crucial for maximizing the value of the observational record.
Detection of supershear rupture in 2013 Craig, Alaska, earthquake
Authors: Schultz Colin
Published: January 2014

Seismic ruptures are akin to opening a zipper—a gap in the crust starts in one location and travels along the fault in a particular direction. When a strained fault ruptures in an earthquake, seismic waves also spread out from the epicenter. In some cases, the waves' passage can trigger the initiation of a new rupture ahead of the initial expanding rupture in locked portions of the fault. If the triggered rupture grows successfully, the overall rupture front can then outpace the passage of the shear waves, secondary seismic waves that travel slowly after the earthquake begins and are responsible for the bulk of violent shaking. These earthquakes display what is known as supershear rupture; only seven such earthquakes have previously been recorded.
Novel Near‐Infrared Squaraine Sensitizers for Stable and Efficient Dye‐Sensitized Solar Cells
Authors: Qin Chuanjiang , Numata Youhei , Zhang Shufang , Yang Xudong , Islam Ashraful , Zhang Kun , Chen Han , Han Liyuan
Published: January 2014

A new molecular design strategy for tuning the energy levels of cis‐configured squaraine sensitizers for dye‐sensitized solar cells is described. The Hammett substituent constant and the π‐conjugation length are used as quantitative indicators to modify the central squarate moiety of the sensitizer dyes; specifically, novel near‐infrared squaraine dyes HSQ3 and HSQ4 are synthesized by incorporation of an electron‐withdrawing and π‐extending ethyl cyanoacetate unit on the central squarate moiety. The solution absorption maximum of HSQ4 occurs at 703 nm, and the energy levels of the lowest unoccupied molecular orbital and the highest occupied molecular orbital are in the ideal range for energetically efficient electron injection and regeneration of the oxidized dye. A solar cell sensitized with HSQ4 exhibits a broad incident photo­n‐to‐current conversion efficiency spectrum, extending into the near‐infrared region with a maximum value of 80% at 720 nm, which is is the highest value reported for a squaraine dye–based dye‐sensitized solar cell. The HSQ4‐sensitized solar cell also exhibits excellent durability during light soaking, owing to the double anchors attaching the dye to the TiO2 surface and to the long alkyl chains extending outward from the surface.
Unexpected Stereoselective Synthesis of (Z)‐β‐Alkenyl Substituted β‐Amino Phosphonates through β,γ‐Dihydrogen Shift Reaction Catalyzed by a Copper(I) Complex and Iodine [Cu(MeCN)4]PF6/I2
Authors: Cai Yan , Lyu Hairong , Yu Chengbin , Miao Zhiwei
Published: January 2014

A series of dialkyl α‐diazophosphonates has been prepared from natural amino acids. The diazo decomposition of these diazophosphonate compounds with tetrakis(acetonitrile)copper(I) hexafluorophosphate/iodine, [Cu(MeCN)4]PF6/I2, as catalyst has been investigated. It was found that the diazo decomposition of dialkyl α‐diazophosphonates gave a mixture of β,γ‐dihydrogen shift and 1,2‐hydride migration products and afforded β‐alkenyl‐substituted β‐amino phosphonates with the Z configuration. The mechanism of this novel diazo decomposition process was discussed.

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Multiway continuous hidden Markov model‐based approach for fault detection and diagnosis
Authors: Sen Deepthi , Raihan Dilshad , Chidambaram M.
Published: January 2014

A fault detection and classification scheme that uses probabilistic inference based on multiway continuous hidden Markov models (MCHMM) which is capable of capturing complex system dynamics and uncertainty is proposed. A set of observations from normal and faulty runs of the system was collected and used to generate the training dataset. The training data is assumed to follow a finite Gaussian mixture model. The number of mixture components and associated parameters for the optimal Gaussian mixture fit of the observed data was computed subsequently by clustering using the Figueiredo–Jain algorithm for unsupervised learning. The segmental k‐means algorithm was used to compute the HMM parameters. The applicability of the proposed scheme is investigated for the case of an inverted pendulum system and a fluidized catalytic cracker. The monitoring results for the above cases with the proposed scheme was found to be superior to the multiway discrete hidden Markov model (MDHMM) based scheme in terms of the accuracy of fault detection, especially in case of noisy observations. © 2014 American Institute of Chemical EngineersAIChE J, 60: 2035–2047, 2014
Skeletal robustness and bone strength as measured by anthropometry and ultrasonography as a function of physical activity in young adults
Authors: Scheffler Christiane , Gniosdorz Birgit , Staub Kaspar , Rühli Frank
Published: January 2014

Background

During the last 10 years, skeletal robustness in children has generally decreased. The reasons for this phenomenon, as well as its outcomes, are undetermined so far.

Aim

The present study explores the association between anthropometric skeletal measurements, bone quality measurements, and physical activity in young adults.

Subjects and Methods

118 German young men (N = 68; 19–25 years old) and women (N = 50; 19–24 years old) were investigated by anthropometric methods (i.e., height, weight, shoulder, elbow breadth, and pelvic breadth) and quantitative ultrasound measurement (QUS). Strength and stability of Os calcis have been determined by speed of sound (in m/s) and broadband ultrasound attenuation (in dB/Mhz); individual physical activity was analyzed by a pedometer and by questionnaire.

Results

The results show a correlation between sports hours per week and bone quality index in males. But no correlation exists between anthropometric data and QUSs for either sexes, as well as no correlation between total steps per day and internal bone quality or external bone dimensions.

Conclusion

These results are discussed in the context of generally decreasing physical activity, the outcomes of prevention programs as well as evolutionary adaptation of human phenotypic plasticity in a changing environment. Am. J. Hum. Biol. 26:215–220, 2014. © 2014 Wiley Periodicals, Inc.
Short‐term heat acclimation is effective and may be enhanced rather than impaired by dehydration
Authors: Garrett A.T. , Goosens N.G. , Rehrer N.J. , Patterson M.J. , Harrison J. , Sammut I. , Cotter J.D.
Published: January 2014

Most heat acclimation data are from regimes longer than 1 week, and acclimation advice is to prevent dehydration. Objectives: We hypothesized that (i) short‐term (5‐day) heat acclimation would substantially improve physiological strain and exercise tolerance under heat stress, and (ii) dehydration would provide a thermally independent stimulus for adaptation. Methods: Nine aerobically fit males heat acclimated using controlled‐hyperthermia (rectal temperature 38.5°C) for 90 min on 5 days; once euhydrated (EUH) and once dehydrated (DEH) during acclimation bouts. Exercising heat stress tests (HSTs) were completed before and after acclimations (90‐min cycling in Ta 35°C, 60% RH). Results: During acclimation bouts, [aldosterone]plasma rose more across DEH than EUH (95%CI for difference between regimes: 40–411 pg ml−1; P = 0.03; n = 5) and was positively related to plasma volume expansion (r = 0.65; P = 0.05), which tended to be larger in DEH (CI: −1 to 10%; P = 0.06; n = 9). In HSTs, resting forearm perfusion increased more in DEH (by 5.9 ml 100 tissue ml−1 min−1: −11.5 to −1.0; P = 0.04) and end‐exercise cardiac frequency fell to a greater extent (by 11 b min−1: −1 to 22; P = 0.05). Hydration‐related effects on other endocrine, cardiovascular, and psychophysical responses to HSTs were unclear. Rectal temperature was unchanged at rest but was 0.3°C lower at end exercise (P < 0.01; interaction: P = 0.52). Conclusions: Short‐term (5‐day) heat acclimation induced effective adaptations, some of which were more pronounced after fluid‐regulatory strain from permissive dehydration, and not attributable to dehydration effects on body temperature. Am. J. Hum. Biol. 26:311–320, 2014. © 2014 Wiley Periodicals, Inc.
Correlation of 2D:4D digit ratio and craniofacial shape in prepubertal children
Authors: Valla Kalliopy , Halazonetis Demetrios J.
Published: January 2014

Objectives

The 2D:4D ratio is sexually dimorphic and is considered a proxy of prenatal androgen levels, or, according to recent evidence, is related to genes involved in ocular and palate development. Our aim was to investigate correlation between the 2D:4D ratio and the shape of the craniofacial skeleton in a population of prepubertal children.

Methods

We conducted a cross‐sectional study in a group of 58 male and 59 female prepubertal children aged 7–12 years. Craniofacial shape was evaluated using 15 skeletal landmarks on lateral cephalometric radiographs and fingers were measured with a computer‐assisted procedure that involved tracing the finger outline. Geometric morphometric analysis was applied to the craniofacial landmarks and multivariate regression between digit ratios and craniofacial shape was computed in shape space and form space.

Results

The male 2D:4D ratio was smaller than the female ratio (Cohen's d: 0.275 left hand, 0.126 right hand), but the difference was not statistically significant. Craniofacial shape did not show sexual dimorphism, but males were larger than females. No correlation was found between digit ratio and craniofacial shape in prepubertal children, either for the whole sample or for any of the two sex groups.

Conclusions

As several factors might be involved in the development and growth of both the craniofacial complex and fingers, the 2D:4D ratio, a putative proxy for fetal sex‐hormone levels, is probably unable to impose a measurable effect within the variation of a normal population. Future research needs to examine an adult sample for potential covariation arising after the pubertal growth spurt. Am. J. Hum. Biol. 26:337–346, 2014. © 2014 Wiley Periodicals, Inc.
Photonische Kristalle für die Chemo‐ und Biosensorik
Authors: Fenzl Christoph , Hirsch Thomas , Wolfbeis Otto S.
Published: January 2014

Dieser Aufsatz beschreibt die Funktionsweise photonischer Kristalle (PhCs) und deren Einsatz in der Sensorik chemischer und biochemischer Analyte. Ein besonderes Augenmerk liegt dabei auf den verwendeten Materialien. Die einzelnen Abschnitte beschreiben a) die Grundlagen natürlicher und synthetischer photonischer Nanoarchitekturen, b) die verschiedenen Arten photonischer Kristallstrukturen, c) Reflexion und Lichtbrechung in PhCs, d) Aspekte der Sensorik auf der Grundlage mechanischer, thermischer, optischer, elektrischer, magnetischer und rein chemischer Einflüsse, e) biosensorische Anwendungen basierend auf Biomolekülen, die in den PhC eingebettet wurden, und f) aktuelle Trends und Einschränkungen solcher Sensoren.
Palladium‐Catalyzed Oxidative Carbonylation of N‐Allylamines for the Synthesis of β‐Lactams
Authors: Li Wu , Liu Chao , Zhang Heng , Ye Keyin , Zhang Guanghui , Zhang Wangzheng , Duan Zhengli , You Shuli , Lei Aiwen
Published: January 2014

β‐Lactam scaffolds are considered to be ideal building blocks for the synthesis of nitrogen‐containing compounds. A new palladium‐catalyzed oxidative carbonylation of N‐allylamines for the synthesis of α‐methylene‐β‐lactams is reported. DFT calculations suggest that the formation of β‐lactams via a four‐membered‐ring transition state is favorable.
A 200‐fold Quantum Yield Boost in the Photoluminescence of Silver‐Doped AgxAu25−x Nanoclusters: The 13 th Silver Atom Matters
Authors: Wang Shuxin , Meng Xiangming , Das Anindita , Li Tao , Song Yongbo , Cao Tiantian , Zhu Xiuyi , Zhu Manzhou , Jin Rongchao
Published: January 2014

The rod‐shaped Au25 nanocluster possesses a low photoluminescence quantum yield (QY=0.1 %) and hence is not of practical use in bioimaging and related applications. Herein, we show that substituting silver atoms for gold in the 25‐atom matrix can drastically enhance the photoluminescence. The obtained AgxAu25−x (x=1–13) nanoclusters exhibit high quantum yield (QY=40.1 %), which is in striking contrast with the normally weakly luminescent AgxAu25−x species (x=1–12, QY=0.21 %). X‐ray crystallography further determines the substitution sites of Ag atoms in the AgxAu25−x cluster through partial occupancy analysis, which provides further insight into the mechanism of photoluminescence enhancement.
Crystallization and thermal properties of polylactide/palygorskite composites
Authors: Pillai Sreejarani Kesavan , Ojijo Vincent , Ray Suprakas Sinha
Published: January 2014

Polylactide palygorskite (fibrous clay) composites were prepared by solvent casting method. Both pristine and organically modified palygorskite were used for composite preparation. The detailed crystallization behavior, morphology, and thermal properties of neat polylactide and the corresponding composites were investigated by using differential scanning calorimetry, polarized optical microscopy, scanning electron microscopy and wide angle X‐ray diffraction techniques. The results showed that the crystallization and thermal characteristics of neat PLA were influenced significantly by the presence of palygorskite nanoparticles. © 2014 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2014, 131, 40414.
Fabrication and characterization of in situ synthesized iron oxide‐modified polyimide nanoweb by needleless electrospinning
Authors: Jain Naintara , Chakraborty Joy , Tripathi Santosh Kumar , Nasim Mohammed
Published: January 2014

A series of poly(amic acid) (PAA) solutions were prepared by sol–gel condensation of 4,4′‐oxydianiline (ODA) and 4,4′‐oxydiphthalic anhydride (ODPA), containing various wt % (5, 10, 15) of an iron oxide precursor, that is, tris(acetylacetonato)iron(III) complex. The resulting PAA solutions were electrospun at 78 kV and collected as webs of nonwoven nanofibers of diameter ∼60–70 nm and subsequently converted to iron oxide‐modified polyimide (PI) nanofibers by slow thermal imidization. Aminopropyl triethoxysilane (APTES) and tetraethoxyorthosilicate (TEOS) were used as coupling agent and silica precursor, respectively, to enhance the compatibility between organic polymer matrix and inorganic moieties. SEM images reveal smooth and defect‐free surface morphologies of the nanofibers. Superparamagnetic properties of the nanofibers were revealed by vibrating sample magnetometer (VSM). FT‐infrared spectroscopy (IR), powder XRD, thermogravimetric analysis, and differential scanning calorimetry were employed to systematically characterize material structural properties, thermal stabilities, etc. Nanowebs showed excellent thermal stability around 446°C, with a glass transition temperature around 270°C. The above study demonstrates a good example for fabrication of highly thermally stable bead‐free nanofiber webs by needleless electrospinning. © 2014 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2014, 131, 40432.
Elucidation of the Enantioselective Cyclohexane‐1,2‐dione Hydrolase Catalyzed Formation of (S)‐Acetoin
Authors: Loschonsky Sabrina , Waltzer Simon , Brecht Volker , Müller Michael
Published: January 2014

Thiamine diphosphate (ThDP) dependent enzymes catalyze the formation of acetoin (3‐hydroxybutan‐2‐one) through one of three different pathways: homocoupling of pyruvate, homocoupling of acetaldehyde, or cross‐coupling of acetaldehyde (as acceptor) and pyruvate (as donor). The enantioselectivity of the resulting acetoin is highly dependent on the particular enzyme. We established that ThDP‐dependent cyclohexane‐1,2‐dione hydrolase (CDH) is able to form (S)‐acetoin with particularly high enantioselectivity (up to 95 % ee) by all three pathways. Mechanistic studies utilizing 13C‐labeled substrates revealed an unprecedented non‐acetolactate pathway for the homocoupling of pyruvate, which explains the high enantioselectivity in the CDH‐catalyzed formation of (S)‐acetoin.
Mediatorless Immunoassay with Voltage‐Controlled Intrinsic Amplification for Ultrasensitive and Rapid Detection of Microorganism Pathogens
Authors: Wang Jiapeng , Xu Yan , Yau Siu‐Tung
Published: January 2014

A mediator‐less immunodetection method for microorganisms is realized by incorporating the newly developed field‐effect enzymatic detection (FEED) technique with the conventional electrochemical immunosensing approach. The gating voltage of FEED facilitates the transduction of electrical signal through the bulky immune complex so that the detection does not rely on the use of mediators or other diffusional substances. The voltage‐controlled intrinsic amplification provided by the detection system allows detection in low‐concentration samples without target pre‐enrichment, leading to ultrasensitive and rapid detection. The detection approach is demonstrated with E. coli O157:H7, a model microorganism, in milk with an estimated detection limit of 20 CFU mL−1 (where CFU is a colony‐forming unit) without performing sample pre‐enrichment and centrifugation of sample followed by the resuspension of the pellet in a buffer solution, resulting in a significantly shortened assay time of 67 min. Optimizing the gating voltage resulted in the detection of 12 CFU mL−1 of the bacterium in milk. The novel detection approach can be used as a detection platform for ultrasensitive, specific and rapid detection of microorganism pathogens.
An accurate test for the equality of covariance matrices from decomposable graphical Gaussian models
Authors: Wu Yanyan , Massam Hélène , Wong Augustine
Published: January 2014

This paper derives a saddlepoint based approximation for the cumulative distribution function of the Bartlett–Box M‐statistic that tests the equality of covariance matrices for several samples from graphical Gaussian models Markov with respect to a decomposable graph. The proposed saddlepoint‐based method has third‐order accuracy (). Simulation results show that the proposed method has extremely good coverage properties even when the sample size is small. We apply our method to the well‐known Call Centre data set and show that the covariance matrix is not constant through time.The Canadian Journal of Statistics42: 61–77; 2014 © 2014 Statistical Society of Canada
Targeted Fluorination of a Nonsteroidal Anti‐inflammatory Drug to Prolong Metabolic Half‐Life
Authors: Shaughnessy Maxwell J. , Harsanyi Antal , Li Jingji , Bright Tara , Murphy Cormac D. , Sandford Graham
Published: January 2014

In drug design, one way of improving metabolic stability is to introduce fluorine at a metabolically labile site. In the early stages of drug design, identification of such sites is challenging, and a rapid method of assessing the effect of fluorination on a putative drug’s metabolic stability would be of clear benefit. One approach to this is to employ micro‐organisms that are established as models of drug metabolism in parallel with the synthesis of fluorinated drug analogues. In this study, we have used the filamentous fungus Cunninghamella elegans to identify the metabolically labile site of the nonsteroidal anti‐inflammatory drug flurbiprofen, to aid in the design of fluorinated derivatives that were subsequently synthesised. The effect of the additional fluorine substitution on cytochrome P450‐catalysed oxidation was then determined via incubation with the fungus, and demonstrated that fluorine substitution at the 4′‐position rendered the drug inactive to oxidative transformation, whereas substitution of fluorine at either 2′ or 3′ resulted in slower oxidation compared to the original drug. This approach to modulating the metabolic stability of a drug‐like compound is widely applicable and can be used to address metabolic issues of otherwise good lead compounds in drug development.
Design and performance of a transformer‐coupled double resonant quadrature birdcage coil for localized proton and phosphorus spectroscopy in the human calf muscle at 7 T
Authors: Brand Robert C. , Webb Andrew G. , Beenakker Jan‐Willem M.
Published: January 2014

One of the major advantages of high field magnets is the increased signal‐to‐noise and spectral resolution for in vivo localized spectroscopy. In muscle studies, for example, the combination of proton and heteronuclear spectroscopy allows quantification of lipid content, fiber orientation, and cellular metabolic status. For clinical utilization it is important that spectra can be acquired in relatively short acquisition times for patient comfort and minimizing the effects of motion. Radiofrequency coils should ideally be fixed tuned and have relatively small effects with loading. Here, the design process and performance of a transformer‐coupled double‐tuned quadrature proton/phosphorus birdcage coil is described. The resulting coil is highly load‐independent in terms of tuning, and despite the intrinsic reduced proton sensitivity compared to a single‐tuned coil, clinically useful proton and phosphorus spectra can be acquired in a total time of less than 30 min. © 2014 Wiley Periodicals, Inc. Concepts Magn Reson Part A 42A: 155–164, 2013.
Accurate metabolic images of the human myocardium by means of 31P magnetic resonance chemical shift imaging with spatial saturation pulses
Authors: Geier Oliver , Weng Andreas Max , Ruff Jan , Machann Wolfram , Horn Michael , Hahn Dietbert , Spindler Matthias , Beer Meinrad , Köstler Herbert
Published: January 2014

The aim of this study was to demonstrate that acquisition‐weighted 31P magnetic resonance spectroscopy with spatial saturation allows for generation of metabolite maps showing the distribution of 31P metabolites, such as phosphocreatine (PCr) and adenosine triphosphate (ATP) in the human myocardium. The method presented here allowed for a considerable shortening of the normally complicated and time‐consuming post‐processing. All examinations were performed on a 1.5 T scanner. Contamination from adjacent organs to the myocardial signal was suppressed using spatial saturation pulses and an acquisition‐weighted sampling scheme. All measurements were ECG‐triggered and performed in prone position. Both healthy subjects and patients with infarcted myocardium were examined. For comparison of the spectroscopic findings to a conventional technique, the infarcted myocardium was additionally examined with a late‐enhancement technique. The distribution of PCr of the whole left ventricular myocardium could be determined both in healthy subjects and in patients. The measured distribution of PCr in the infarcted myocardium revealed an obvious reduction of signal in the infarcted area, whereas the distributions of the metabolites in healthy myocardium reflected no discontinuities. The study could demonstrate that the application of spatial saturation pulses facilitates the visual representation of 31P metabolites with a post‐processing procedure easy to apply. © 2014 Wiley Periodicals, Inc. Concepts Magn Reson Part A 42A: 187–195, 2013.
A prospective study of anxiety, depression, and behavioral changes in the first year after a diagnosis of childhood acute lymphoblastic leukemia
Authors: Myers Regina M. , Balsamo Lyn , Lu Xiaomin , Devidas Meenakshi , Hunger Stephen P. , Carroll William L. , Winick Naomi J. , Maloney Kelly W. , Kadan‐Lottick Nina S.
Published: January 2014

BACKGROUND

The authors prospectively assessed anxiety, depression, and behavior in children with standard‐risk acute lymphoblastic leukemia (SR‐ALL) during the first year of therapy and identified associated risk factors.

METHODS

A cohort study was performed of 159 children (aged 2 years‐9.99 years) with SR‐ALL who were enrolled on Children's Oncology Group protocol AALL0331 at 31 sites. Parents completed the Behavior Assessment System for Children, the General Functioning Scale of the Family Assessment Device, and the Coping Health Inventory for Parents at approximately 1, 6, and 12 months after diagnosis.

RESULTS

Overall, mean scores for anxiety, depression, aggression, and hyperactivity were similar to population norms. However, more children scored in the at‐risk/clinical range for depression than the expected 15% at 1 month (21.7%; P = .022), 6 months (28.6%; P < .001), and 12 months (21.1%; P = .032). For anxiety, more children scored in the at‐risk/clinical range at 1 month (25.2% vs 15%; P = .001), but then reverted to expected levels. On adjusted analysis, unhealthy family functioning was found to be predictive of anxiety (odds ratio [OR], 2.24; P = .033) and depression (OR, 2.40; P = .008). Hispanic ethnicity was associated with anxiety (OR, 3.35; P = .009). Worse physical functioning (P = .049), unmarried parents (P = .017), and less reliance on social support (P = .004) were found to be associated with depression. Emotional distress at 1 month predicted anxiety (OR, 7.11; P = .002) and depression (OR, 3.31; P = .023) at 12 months.

CONCLUSIONS

Anxiety is a significant problem in a subpopulation of patients with SR‐ALL immediately after diagnosis, whereas depression remains a significant problem for at least 1 year. Children of Hispanic ethnicity or those with unhealthy family functioning may be particularly vulnerable. These data suggest that clinicians should screen for anxiety and depression throughout the first year of therapy. Cancer 2014;120:1417–1425. © 2014 American Cancer Society.
Differing impact of a major biogeographic barrier on genetic structure in two large kangaroos from the monsoon tropics of Northern Australia
Authors: Eldridge Mark D. B. , Potter Sally , Johnson Christopher N. , Ritchie Euan G.
Published: January 2014

Tropical savannas cover 20–30% of the world's land surface and exhibit high levels of regional endemism, but the evolutionary histories of their biota remain poorly studied. The most extensive and unmodified tropical savannas occur in Northern Australia, and recent studies suggest this region supports high levels of previously undetected genetic diversity. To examine the importance of barriers to gene flow and the environmental history of Northern Australia in influencing patterns of diversity, we investigated the phylogeography of two closely related, large, vagile macropodid marsupials, the antilopine wallaroo (Macropus antilopinus; n = 78), and the common wallaroo (Macropus robustus; n = 21). Both species are widespread across the tropical savannas of Australia except across the Carpentarian Barrier (CB) where there is a break in the distribution of M. antilopinus. We determined sequence variation in the hypervariable Domain I of the mitochondrial DNA control region and genotyped individuals at 12 polymorphic microsatellite loci to assess the historical and contemporary influence of the CB on these species. Surprisingly, we detected only limited differentiation between the disjunct Northern Territory and Queensland M. antilopinus populations. In contrast, the continuously distributed M. robustus was highly divergent across the CB. Although unexpected, these contrasting responses appear related to minor differences in species biology. Our results suggest that vicariance may not explain well the phylogeographic patterns in Australia's dynamic monsoonal environments. This is because Quaternary environmental changes in this region have been complex, and diverse individual species’ biologies have resulted in less predictable and idiosyncratic responses.
Synthesis, Crystal Structure, and Biological Study of PtII Complexes with 4‐Acyl‐5‐pyrazolones
Authors: De Pascali Sandra A. , Migoni Danilo , Monari Magda , Pettinari Claudio , Marchetti Fabio , Muscella Antonella , Fanizzi Francesco P.
Published: January 2014

The syntheses of new PtII complexes with 4‐acyl‐5‐pyrazolones [HQPh = 1‐phenyl‐3‐methyl‐4‐benzoylpyrazol‐5‐one, a; HQpy,CF3 = 1‐(2‐pyridyl)‐3‐methyl‐trifluoroacetylpyrazol‐5‐one, b] are reported: trans‐[PtCl2(DMSO)(HQPh)] (1a), cis‐[PtCl2(DMSO)(HQPh)] (2a), [PtCl(DMSO)(Qpy,CF3)] (1b), and [PtCl2(KQpy,CF3)] (2b). All complexes were characterized by multinuclear (1H, 13C, 19F, and 195Pt), multidimensional NMR spectroscopy and single‐crystal X‐ray diffraction analyses. The isomer trans‐[PtCl2(DMSO)(HQPh)] (1a) crystallizes in two polymorphic forms, which correspond to two different conformers. In the trans–syn conformer (1aM) (monoclinic, space group P21/c), the H atom of the enol group [O(1)H(1)] establishes an intramolecular hydrogen bond with the ketone oxygen (O2), whereas in the trans–anti conformer (1aO) (orthorhombic, space group Pca21), the same groups are involved in an analogous intermolecular H bond. Interestingly, the cis isomer (2a) showed in solution and at room temperature slow rotation around both the Pt–N1 and the Pt–S bonds, which restrained both the acylpyrazolone and DMSO ligand motion. Moreover, the water solubility of the complexes trans‐ and cis‐[PtCl2(DMSO)(HQPh)] (1a and 2a) and [PtCl2(KQpy,CF3)] (2b) allowed to perform in vitro biological assays on platinum‐sensitive human endometrium (HeLa) and platinum‐resistant human breast (MCF‐7) cancer cell lines. It was also possible to compare their cytotoxicity to cisplatin. Interestingly, trans isomer 1a showed higher cytotoxicity on HeLa cells compared to the cis isomer 2a.
Total Synthesis of the Proposed Structure of Heronamide C
Authors: Sakanishi Kohei , Itoh Shunya , Sugiyama Ryosuke , Nishimura Shinichi , Kakeya Hideaki , Iwabuchi Yoshiharu , Kanoh Naoki
Published: January 2014

The total synthesis of the proposed structure of heronamide C was accomplished through a Sato–Micalizio reductive alkyne–alkyne coupling strategy and remote‐amine controlled stannylcupration. However, the physical data for the synthetic and natural samples differ from each other, which suggests that the proposed structure should be reinvestigated.
Short‐Step Anodic Access to Emissive RNA Homonucleosides
Authors: Okada Yohei , Shimada Kouhei , Kitano Yoshikazu , Chiba Kazuhiro
Published: January 2014

Emissive RNA homonucleosides were added to the growing library of synthetic probes. The emissive nucleobases were constructed in one step from the methallyl C‐glycoside of D‐ribofuranose, which was prepared stereoselectively. The homonucleosides displayed various emission colors by using a single excitation wavelength that could be fine‐tuned merely by changing the carbonyl substituent on the methoxyphenol.
Convenient Synthesis of Arylboronates through a Synergistic Pd/Cu‐Catalyzed Miyaura Borylation Reaction under Atmospheric Conditions
Authors: Ratniyom Jadsada , Dechnarong Nattanee , Yotphan Sirilata , Kiatisevi Supavadee
Published: January 2014

A highly efficient and practical borylation reaction of aryl iodides with bis(pinacolato)diboron has been established. By using Pd(OAc)2, CuI, and PPh3 as a ligand at room temperature under air in the presence of Cs2CO3, the protocol proved to be general. Various functionalized arylboronates were obtained in moderate to excellent yields. In addition, a possible reaction mechanism was proposed.
Cross‐Conjugation vs. Linear Conjugation in Donor–Bridge–Acceptor Nitrophenol Chromophores
Authors: Christensen Mikkel Andreas , Della Pia Eduardo Antonio , Houmøller Jørgen , Thomsen Sean , Wanko Marius , Bond Andrew D. , Rubio Angel , Brøndsted Nielsen Steen , Brøndsted Nielsen Mogens
Published: January 2014

The influence of cross‐conjugation vs. linear conjugation on the electronic communication between donor and acceptor groups in phenol(ate)–bridge–nitrobenzene chromophores was investigated by solution and gas‐phase absorption spectroscopy, fluorescence spectroscopy, and quantum chemical calculations. The compounds studied include, among others, geminally and trans‐substituted diethynylethenes prepared by stepwise Sonogashira cross‐coupling reactions, and the cross‐conjugated analogue of stilbene. A butadiyne‐bridged donor–acceptor chromophore was prepared by an unsymmetrical Pd‐catalysed coupling between a chloroalkyne and a terminal alkyne. While the linearly conjugated chromophores showed a strong and redshifted charge‐transfer (CT) absorption maximum upon deprotonation in solution, a new redshifted absorption was either absent or present as a weak shoulder for the cross‐conjugated derivatives. Calculations on the nonplanar 1,1‐diaryl‐substituted ethylene derivative revealed that the S0–S1 absorption has a very low oscillator strength due to insignificant coupling between the donor and acceptor ends. The energy of this CT absorption for a nonsolvated molecule is smaller than that of the linearly conjugated stilbene analogue by 0.4 eV. This result cannot directly be inferred from the solution studies. A gas‐phase absorption spectrum of this chromophore was measured by action spectroscopy, which only revealed a higher‐energy absorption band. Based on calculations, this band was assigned to a higher‐lying π–π* transition. For the planar diethynylethene chromophores, cross‐conjugation leads to a decrease of 0.3 eV in the excitation energy, according to the calculations. Finally, in contrast to the linearly conjugated chromophores, the cross‐conjugated ones did not show any fluorescence, which may be due to deexcitation via the low‐lying CT “dark” state.
Progress in Asymmetric Organocatalytic Synthesis of β‐Lactams
Authors: Magriotis Plato A.
Published: January 2014

The success of the application of transition‐metal catalysts in asymmetric synthesis was recognized in the form of the 2001 Nobel Prize in Chemistry, but since then the field of asymmetric organic synthesis has been dominated by organocatalysts, due to their ability to catalyze a variety of fundamentally important transformations. One example is the Staudinger synthesis of β‐lactams, which continue to provide unique opportunities for the design and synthesis of new derivatives with unprecedented biological profiles. During the last two decades, medicinal chemists have convincingly demonstrated that structural modification of monocyclic β‐lactams (monobactams) is an effective procedure for the discovery of new pharmacological properties other than antibacterial activity. This microreview covers the progress in asymmetric organocatalytic synthesis of β‐lactams since 2001, including the initial work on processes based on chirally modified transition‐metal catalysts, because these have led the way to the more significant advances presented here.
Effects of yeast and maltose concentration on ultrasonic velocity and attenuation coefficient and its application for process monitoring
Authors: Geier Dominik , Heermann Katrin , Hussein Mohamed , Becker Thomas
Published: January 2014

Monitoring substrate and cell concentration is important for controlling yeast propagation and fermentation processes. This usually requires two instruments, a density meter, and an optical turbidity meter. This paper presents a method for simultaneously determining yeast and maltose concentration with a single ultrasonic sensor. Ultrasonic velocity and attenuation were measured at varying maltose and yeast cell concentrations from 0 to 4 wt%. Ultrasonic velocity increased linearly with both yeast (R2 = 0.999) and maltose concentration (R2 = 0.996). In contrast, while attenuation coefficient depended linearly on yeast concentration (R2 = 0.998), it did not significantly depend on maltose concentration (R2 = 0.476). To draw conclusions about the main mechanisms of attenuation, the measured attenuation coefficients for yeast cells at 2 MHz were compared to predicted values. With a mean absolute percentage error of 0.25%, intrinsic absorption, thermal effects, and, to a lesser extent, viscous effects were identified as the main reason for damping. These results support the feasibility of combining ultrasonic velocity and attenuation measurements for estimating yeast cell and maltose concentration.
Perfectionism and Eating Psychopathology Among Dancers: The Role of High Standards and Self‐criticism
Authors: Goodwin Huw , Arcelus Jon , Geach Nicole , Meyer Caroline
Published: January 2014

This study examined the associations between conscientious perfectionism (high standards), self‐evaluative perfectionism (self‐criticism) and eating psychopathology among dancers. A sample of 244 female dancers, with a mean age of 20.11 years (standard deviation = 1.97) completed the Perfectionism Inventory and Eating Disorder Examination Questionnaire. Self‐evaluative perfectionism predicted eating psychopathology (eating restraint, eating concern, weight concern and shape concern). This relationship was not moderated by conscientious perfectionism. The mediation analyses showed that although conscientious perfectionism predicted eating psychopathology, this relationship was fully mediated by self‐evaluative perfectionism. These findings demonstrate the greater influence of self‐evaluative perfectionism, rather than conscientious perfectionism, on eating psychopathology in dancers. Copyright © 2014 John Wiley & Sons, Ltd and Eating Disorders Association.
A two‐step monolithic method for the efficient simulation of incompressible flows
Authors: Ryzhakov P. , Cotela J. , Rossi R. , Oñate E.
Published: January 2014

We propose a simple technique for improving computationally the efficiency of monolithic velocity–pressure solvers for incompressible flow problems. The idea consists in solving the discrete nonlinear system of governing equations in two steps: introducing ‘artificial’ compressibility first and afterwards correcting the solution by solving the original incompressible system. The speed‐up is obtained because of a better conditioning of the modified discrete system solved at the prediction step. The formulation can be easily implemented into existing monolithic codes requiring minor modification only. The paper concludes with two examples validating the formulation and facilitating the estimation of the obtained speed‐up. For the tests chosen, an average speed‐up is approximately double, suggesting that the method is a feasible approach for incompressible flows' simulation. Copyright © 2014 John Wiley & Sons, Ltd.