bluuebunny/crossref_metadata_2025 huggingface dataset:
Quantifying upper ocean turbulence driven by surface waves
Authors: D'Asaro E. A. , Thomson J. , Shcherbina A. Y. , Harcourt R. R. , Cronin M. F. , Hemer M. A. , Fox‐Kemper B.
Published: December 2013

Nearly all operational ocean models use air‐sea fluxes and the ocean shear and stratification to estimate upper ocean boundary layer mixing rates. This approach implicitly parameterizes surface wave effects in terms of these inputs. Here we test this assumption using parallel experiments in a lake with small waves and in the open ocean with much bigger waves. Under the same wind stress and adjusting for buoyancy flux, we find the mixed layer average turbulent vertical kinetic energy in the open ocean typically twice that in the lake. The increase is consistent with models of Langmuir turbulence, in which the wave Stokes drift, and not wave breaking, is the dominant mechanism by which waves energize turbulence in the mixed layer. Applying these same theories globally, we find enhanced mixing and deeper mixed layers resulting from the inclusion of Langmuir turbulence in the boundary layer parameterization, especially in the Southern Ocean.
Gypsum crystals observed in experimental and natural sea ice
Authors: Geilfus N.‐X. , Galley R. J. , Cooper M. , Halden N. , Hare A. , Wang F. , Søgaard D. H. , Rysgaard S.
Published: December 2013

Although gypsum has been predicted to precipitate in sea ice, it has never been observed. Here we provide the first report on gypsum precipitation in both experimental and natural sea ice. Crystals were identified by X‐ray diffraction analysis. Based on their apparent distinguishing characteristics, the gypsum crystals were identified as being authigenic. The FREeZing CHEMistry (FREZCHEM) model results support our observations of both gypsum and ikaite precipitation at typical in situ sea ice temperatures and confirms the “Gitterman pathway” where gypsum is predicted to precipitate. The occurrence of authigenic gypsum in sea ice during its formation represents a new observation of precipitate formation and potential marine deposition in polar seas.
Linking Northern Hemisphere blocking and storm track biases in the CMIP5 climate models
Authors: Zappa G. , Masato G. , Shaffrey L. , Woollings T. , Hodges K.
Published: December 2013

The relationship between biases in Northern Hemisphere (NH) atmospheric blocking frequency and extratropical cyclone track density is investigated in 12 CMIP5 climate models to identify mechanisms underlying climate model biases and inform future model development. Biases in the Greenland blocking and summer Pacific blocking frequencies are associated with biases in the storm track latitudes, while biases in winter European blocking frequency are related to the North Atlantic storm track tilt and Mediterranean cyclone density. However, biases in summer European and winter Pacific blocking appear less related with cyclone track density. Furthermore, the models with smaller biases in winter European blocking frequency have smaller biases in the cyclone density in Europe, which suggests that they are different aspects of the same bias. This is not found elsewhere in the NH. The summer North Atlantic and the North Pacific mean CMIP5 track density and blocking biases might therefore have different origins.
Three‐dimensional MHD simulation of FTEs produced by merging at an isolated point in a sheared magnetic field configuration
Authors: Santos J. C. , Sibeck D. G. , Büchner J. , Gonzalez W. D. , Ferreira J. L.
Published: December 2013

We present predictions for the evolution of FTEs generated by localized bursts of reconnection on a planar magnetopause that separates a magnetosheath region of high densities and weak magnetic field from a magnetospheric region of low densities and strong magnetic field. The magnetic fields present a shear angle of 105 degrees. Reconnection forms a pair of FTEs each crossing the magnetopause in the field reversal region and bulging into the magnetosphere and magnetosheath. At their initial stage they can be characterized as flux tubes since the newly reconnected magnetic field lines are not twisted. Reconnection launches Alfvenic perturbations that propagate along the FTEs generating high‐speed jets, which move the pair of FTEs in opposite directions. As the FTE moves, it displaces the ambient magnetic field and plasma producing bipolar magnetic field and plasma velocity signatures normal to the nominal magnetopause in the regions surrounding the FTE. The combination of the ambient plasma with the FTE flows generates a vortical velocity pattern around the reconnected field lines. During its evolution the FTE evolves to a flux rope configuration due to the twist of the magnetic field lines. The alfvenic perturbations propagate faster along the part of the FTE bulging into the magnetosphere than in the magnetosheath, and due to the differences between the plasma and magnetic field properties the perturbations have slightly different signatures in the two regions. As a consequence, the FTEs have different signatures depending on whether the satellite encounters the part bulging into the magnetosphere or into the magnetosheath.
Open boundary particle‐in‐cell simulation of dipolarization front propagation
Authors: Klimas Alex , Hwang Kyoung‐Joo , ‐Viñas Adolfo F. , Goldstein Melvyn L.
Published: December 2013

First results are presented from an ongoing open boundary 2½D particle‐in‐cell simulation study of dipolarization front (DF) propagation in Earth's magnetotail. At this stage, this study is focused on the compression, or pileup, region preceding the DF current sheet. We find that the earthward acceleration of the plasma in this region is in general agreement with a recent DF force balance model. A gyrophase bunched reflected ion population at the leading edge of the pileup region is reflected by a normal electric field in the pileup region itself, rather than through an interaction with the current sheet. We discuss plasma wave activity at the leading edge of the pileup region that may be driven by gradients, or by reflected ions, or both; the mode has not been identified. The waves oscillate near but above the ion cyclotron frequency with wavelength several ion inertial lengths. We show that the waves oscillate primarily in the perpendicular magnetic field components, do not propagate along the background magnetic field, are right handed elliptically (close to circularly) polarized, exist in a region of high electron and ion beta, and are stationary in the plasma frame moving earthward. We discuss the possibility that the waves are present in plasma sheet data, but have not, thus far, been discovered.
Carbonate chemistry in the Mertz Polynya (East Antarctica): Biological and physical modification of dense water outflows and the export of anthropogenic CO2
Authors: Shadwick E. H. , Tilbrook B. , Williams G. D.
Published: December 2013

Dense shelf water (DSW) is formed in East Antarctica from enhanced sea‐ice production driven by air‐sea interaction in coastal polynyas. Cross‐shelf export and downslope mixing of this DSW produces Antarctic Bottom Water, contributing to the lower limb of the global overturning circulation. We present biogeochemical observations from the Mertz Polynya region in summer 2007/2008, with additional observations from spring 2001 and winter 1996. The seasonal changes in mixed‐layer carbonate chemistry are driven by a combination of air‐sea CO2 exchange, biological activity and the formation and melt of sea‐ice. The air‐sea fluxes in 2008 were ∼15 mmol C m−2 d−1, and net community production, estimated from the summertime surface dissolved inorganic carbon (DIC) deficit, ranged from 0.9 to 1.2 mol C m−2 yr−1. We show that biological modification of carbonate chemistry over the shelf in summer preconditions the DSW outflows from the Adélie Depression. This process appears to supply both organic material, and water depleted in CO2, and with enhanced carbonate saturation state (relative to inflowing water), to coral communities on the slope. We combined model‐based transports of exported DSW with the natural and anthropogenic (Cant) carbon concentrations and estimate that the annual outflows of DIC and Cant from the Mertz Polynya range from 320 to 560 Tg C yr−1, and from 3 to 6 Tg Cant yr−1, respectively. The formation and export of dense water from this region, and by extension all similar polynyas around Antarctica, is an effective mechanism for the transfer of anthropogenic carbon into the deep ocean.
Regional differences of relative sea level changes in the Northwest Atlantic: Historical trends and future projections
Authors: Han Guoqi , Ma Zhimin , Bao Huizhi , Slangen Aimée
Published: December 2013

Mean sea level is one of the most important indicators for climate variability and change. Here, we use tide‐gauge data and satellite measurements to examine recent trends in the mean relative sea level (RSL) in the Northwest Atlantic. We then combine model output and satellite observations to provide sea level projections in the 21st century. The mean RSL trend based on historical tide‐gauge data shows large regional variations, from 2 to 4 mm/yr (above the global mean RSL rise rate) in the southeast to −2 mm/yr in the northwest along East Canada. This spatial difference can to a large degree be attributed to that in the vertical land motion measured by the Global Positioning System (GPS). The combination of altimeter‐measured sea level change with the GPS data can approximately account for tide‐gauge measurements at most stations over 1993–2011. When the GPS data are used, the projected mean RSL rise between 1980–1999 and 2090–2099 ranges from 38 to 63 cm along the Scotia‐Fundy and Newfoundland coasts and smaller along Labrador, the northern Gulf of St. Lawrence, and the St. Lawrence Estuary. In spite of considerable uncertainties the ocean steric and dynamical effect is the dominant contributor (35–70 cm) to the RSL rise along the Canadian east coast. The land‐ice (glaciers and ice sheets) melt contributes to the RSL rise by 10–15 cm except at Nain where it is negligible. The effect of the vertical land uplift is large (40–50 cm) at Nain, Sept‐iles and Rimouski, significantly reducing the magnitude of the RSL rise.
Case study of absorption aerosol optical depth closure of black carbon over the East China Sea
Authors: Koike M. , Moteki N. , Khatri P. , Takamura T. , Takegawa N. , Kondo Y. , Hashioka H. , Matsui H. , Shimizu A. , Sugimoto N.
Published: December 2013

Absorption aerosol optical depth (AAOD) measurements made by sun‐sky photometers are currently the only constraint available for estimates of the global radiative forcing of black carbon (BC), but their validation studies are limited. In this paper, we report the first attempt to compare AAODs derived from single‐particle soot photometer (SP2) and ground‐based sun‐sky photometer (sky radiometer, SKYNET) measurements. During the Aerosol Radiative Forcing in East Asia (A‐FORCE) experiments, BC size distribution and mixing state vertical profiles were measured using an SP2 on board a research aircraft near the Fukue Observatory (32.8°N, 128.7°E) over the East China Sea in spring 2009 and late winter 2013. The aerosol extinction coefficients (bext) and single scattering albedo (SSA) at 500 nm were calculated based on aerosol size distribution and detailed BC mixing state information. The calculated aerosol optical depth (AOD) agreed well with the sky radiometer measurements (2 ± 6%) when dust loadings were low (lidar‐derived nonspherical particle contribution to AOD less than 20%). However, under these low‐dust conditions, the AAODs obtained from sky radiometer measurements were only half of the in situ estimates. When dust loadings were high, the sky radiometer measurements showed systematically higher AAODs even when all coarse particles were assumed to be dust for in situ measurements. These results indicate that there are considerable uncertainties in AAOD measurements. Uncertainties in the BC refractive index, optical calculations from in situ data, and sky radiometer retrieval analyses are discussed.
Do sophisticated parameterizations of aerosol‐cloud interactions in CMIP5 models improve the representation of recent observed temperature trends?
Authors: Ekman Annica M. L.
Published: December 2013

Model output from the Coupled Model Intercomparison Project phase 5 (CMIP5) archive was compared with the observed latitudinal distribution of surface temperature trends between the years 1965 and 2004. By comparing model simulations that only consider changes in greenhouse gas forcing (GHG) with simulations that also consider the time evolution of anthropogenic aerosol emissions (GHGAERO), the influence of aerosol forcing on modeled surface temperature trends, and the dependence of the forcing on the model representation of aerosols and aerosol indirect effects, was evaluated. One group of models include sophisticated parameterizations of aerosol activation into cloud droplets; viz., the cloud droplet number concentration (CDNC) is a function of the modeled supersaturation as well as the aerosol concentration. In these models, the temperature trend bias was reduced in GHGAERO compared to GHG in more regions than in the other models. The ratio between high‐ and low‐latitude warming also improved compared to observations. In a second group of models, the CDNC is diagnosed using an empirical relationship between the CDNC and the aerosol concentration. In this group, the temperature trend bias was reduced in more regions than in the model group where no aerosol indirect effects are considered. No clear difference could be found between models that include an explicit aerosol module and the ones that utilize prescribed aerosol. There was also no clear difference between models that include aerosol effects on the precipitation formation rate and the ones that do not. The results indicate that the best representation of recent observed surface temperature trends is obtained if the modeled CDNC is a function of both the aerosol concentration and the supersaturation.
A comparative evaluation of impact of domain size and parameterization scheme on simulation of tropical cyclones in the Bay of Bengal
Authors: Goswami Prashant , Mohapatra G. N.
Published: December 2013

A large number of processes and factors control the quality of simulations with a numerical weather prediction model and especially with mesoscale models; identification and optimization of these processes are critical for improving forecast skill. The importance of cumulus parameterization schemes in simulation of tropical cyclones was recognized early, and a large number of studies have addressed this issue. However, certain other aspects have received relatively less attention. In particular, unlike simulation with a global circulation model, a mesoscale simulation is characterized by a limited domain and hence inhomogeneous lateral boundary conditions that strongly affect the quality of the simulation. In this work, we investigate the relative impact of size of the model domain and the cumulus parameterization scheme on simulation of 10 cyclones over the Bay of Bengal during the period 1999–2009. For five domains with different spatial extents, simulations were carried out for three different cumulus parameterization schemes (Anthes‐Kuo, Grell, and Kain‐Fritsch2) for each of the 10 events (using the mesoscale model MM5). Our results show that the size of the domain also plays an equally critical role as the parameterization scheme in simulation of maximum intensity, track, and spatial structure of the cyclones. The impact of domain size is not linear; while each domain chosen is large enough, neither the largest nor the smallest domain provides the best simulation. However, there is consistency in the sense that a single domain emerges as best for intensity and track among the five considered. While the specific conclusions may depend on the ocean basin, the methodology is generic and can be applied to any ocean basin of cyclogenesis.
Vegetation collection efficiency of ultrafine particles: From single fiber to porous media
Authors: Lin Ming‐Yeng , Khlystov Andrey , Katul Gabriel G.
Published: December 2013

A number of parameterization schemes are available to determine the collection efficiency of ultrafine particles (UFP) onto vegetated surfaces. One approach represents the vegetated elements as a fibrous filter with a characteristic fiber size that is difficult to a priori determine, while the other, a more conventional approach, represents vegetation as a porous medium. To date, no attempts have been made to compare the performance of these two distinct approaches or bridge them so as to show the necessary conditions leading to their potential equivalence. In a wind tunnel study, the UFP collection efficiencies of pine branches at five different wind speeds, two branch orientations, and two packing densities were measured and analyzed using these two vegetation representations. This vegetation type was selected because pines are a dominant species in the Southeastern United States and pine needles geometrically resemble fibrous material with a well‐defined foliage diameter. The porous media and the fibrous filter representations described well observed UFP deposition at the branch scale. Conditions promoting their equivalence are thus explored. The difficult to determine effective fiber diameter was recovered from conventional canopy attributes such as the leaf area index by matching the collection efficiencies of UFP for the two vegetation representations. These results provide a working “aerodynamic” definition of the effective single‐fiber diameter thereby rendering the simplified single‐fiber formulation usable in large‐scale atmospheric deposition models. Furthermore, the aerodynamic correction factor allows upscaling of pine needles to an effective leaf area index and provides some quantification of the effect of needle spatial clustering on UFP deposition. The applicability of the results to other vegetation species remains to be verified.
Intercomparison of spring soil moisture among multiple reanalysis data sets over eastern China
Authors: Liu Li , Zhang Renhe , Zuo Zhiyan
Published: December 2013

Statistical characteristics of spring soil moisture in different reanalysis data sets of ERA‐Interim, Modern Era Retrospective‐Analysis for Research and Applications (MERRA), Japanese 25‐year Reanalysis, Climate Forecast System Reanalysis, and National Centers for Environmental Prediction/National Center for Atmospheric Research‐Reanalysis 1 (NCEP/NCAR‐R1) are intercompared with each other and with the observations over China. The spring soil moisture is largest in southeastern China and smallest in northwestern China in climatology. It exhibits a pronounced interannual variability with opposite variation in the midlatitude zone and northeastern China. There exist a wet trend at midlatitudes and a dry trend in northeastern China. The intercomparison shows that, except NCEP/NCAR‐R1, the reanalyses can reproduce the observed gradual increases of climatological soil moisture in China from the northwest to the northeast and to the southeast. MERRA presents the best climatological soil moisture. Only ERA‐Interim can well represent the interannual variations of observed soil moisture. The first empirical orthogonal function mode of observed soil moisture demonstrates that the variability of soil moisture is most robust in the midlatitude zone of eastern China and the ERA‐Interim is the best in reproducing the spatial and temporal features. The reasons causing differences between reanalyses of soil moisture are also investigated in terms of two main factors affecting soil moisture, precipitation and evaporation. The ERA‐Interim can well reproduce the precipitation and evaporation from observations as well as their relations to soil moisture, resulting in a preferable ability to represent the spatial and temporal characteristics of observed soil moisture. Although the other four reanalysis data sets reproduce precipitation well, their poor ability to describe the evaporation causes large differences of soil moisture between their simulations and observations.
Pressure observations by the Curiosity rover: Initial results
Authors: Harri A.‐M. , Genzer M. , Kemppinen O. , Kahanpää H. , Gomez‐Elvira J. , Rodriguez‐Manfredi J. A. , Haberle R. , Polkko J. , Schmidt W. , Savijärvi H. , Kauhanen J. , Atlaskin E. , Richardson M. , Siili T. , Paton M. , de la Torre Juarez M. , Newman C. , Rafkin S. , Lemmon M. T. , Mischna M. , Merikallio S. , Haukka H. , Martin‐Torres J. , Zorzano M.‐P. , Peinado V. , Urqui R. , Lapinette A. , Scodary A. , Mäkinen T. , Vazquez L. , Rennó N. , the REMS/MSL Science Team
Published: December 2013

REMS‐P, the pressure measurement subsystem of the Mars Science Laboratory (MSL) Rover Environmental Measurement Station (REMS), is performing accurate observations of the Martian atmospheric surface pressure. It has demonstrated high data quality and good temporal coverage, carrying out the first in situ pressure observations in the Martian equatorial regions. We describe the REMS‐P initial results by MSL mission sol 100 including the instrument performance and data quality and illustrate some initial interpretations of the observed features. The observations show both expected and new phenomena at various spatial and temporal scales, e.g., the gradually increasing pressure due to the advancing Martian season signals from the diurnal tides as well as various local atmospheric phenomena and thermal vortices. Among the unexpected new phenomena discovered in the pressure data are a small regular pressure drop at every sol and pressure oscillations occurring in the early evening. We look forward to continued high‐quality observations by REMS‐P, extending the data set to reveal characteristics of seasonal variations and improved insights into regional and local phenomena.
Fuel Cell Powered Vehicles
Authors: Zhao Hengbing , Burke Andrew
Published: December 2013

Hydrogen fuel cell vehicles are considered as one of the best sustainable transportation solutions that have the potential to significantly reduce our dependence on fossil oil and lower harmful emissions. This chapter reviews and discusses different powertrain arrangements and onboard hydrogen storage technologies in a fuel cell vehicle and various hydrogen generation and refueling approaches. Optimal varying pressure operation of a fuel cell system is studied. Compared to fixed pressure operation, optimal operation shows higher system efficiency over the full load range. However, optimal operation of a fuel cell system requires coordinated reactant flow control in both cathode and anode sides to minimize the mechanical stress on theMEA. Hybridization of the vehicle powertrain is an effective approach to mitigate the stress on the fuel cell stack by shifting most of the dynamic power demand to a second power source such as batteries and/or ultracapacitors. Different power splitting strategies in a hybrid fuel cell vehicle are discussed. Simulations over various driving cycles are performed to compare fuel cell vehicles with other advanced technology vehicles in terms of fuel savings.
Engine Management Systems
Authors: Lahti John
Published: December 2013

Engine models are now commonly used within the electronic control unit (ECU) to predict parameters that are not measured. The models may also be used for calculating the required actuator positions. These models and their use in the control structure are described. Strategies are explained for modeling and controlling the airflow, exhaust gas recirculation (EGR), variable geometry turbocharger (VGT) vane position, fuel injection, and spark advance. Model fidelity is discussed and a new individual cylinder engine model is introduced.
Sandwich Materials
Authors: Palkowski Heinz , Sokolova Olga A. , Carradò Adele
Published: December 2013

Multifunctionality and the demand for improving the properties of construction materials make it necessary to use hybrid systems, such as combinations of metals with polymers. In the following, “sandwich materials” are understood to be metal–polymer–metal sandwich sheets bonded together by adhesive layers. Their applications involve many topics; such as manufacturing methods, mechanical and thermal properties, working capacity, and of course an understanding of internal structure as well as the static, dynamic, or cyclic behavior in different applications.

Joining different materials for specific applications is a challenge that has kept the scientists being busy for more than recent half century. The problem is to find the right way to combine dissimilar materials to a composite. In this chapter, a short theoretical background of composites used in the automotive industry is presented. Moreover, thermal and mechanical joining processes, fabricating processes and forming methods for composites are briefly introduced. Furthermore, a study ofAISI SS316L/polypropylene copolymer/AISI SS316Lsandwich sheets, manufactured in a roll bonding process, is introduced. Their mechanical behavior and formability by deep drawing with and without using different local, embedded solid and mesh steel inlays are discussed.
Reparability and Insurance Ratings in the Development of Cars
Authors: Leimbach Frank , Kiebach Helge
Published: December 2013

Analysis of real world accidents determined that most accidents happen at low speeds. Statistics revealed that 85% of all frontal impacts occur at velocities below 9 mph (15 km/h). From an insurance cost view, the requirements are to limit the deformation or damage to structural parts and cost‐intensive components. The crash safety performance could be implemented relatively easily, that is, in the design of rigid bumpers and beams. However, the design of car front structures is a very complex process, including marketing and visual design criteria, as well as pedestrian safety. Along with the insurance cost aspects, other regulatory and consumerism low speed crash tests are often employed to reduce damage and improve the repairability of vehicles. In addition to frontal testing, low speed tests for the rear and side areas of the vehicle have also been introduced for similar purposes. This chapter addresses the history of low speed repair crash tests and the relevance of crash repair tests in the calculation of insurance premiums for fully comprehensive cover. Various standards and crash tests for consumer information and insurance tests have been introduced in many markets. Research Council for Automobile Repairs provides an overview of the variety of low speed test procedures.
A multiscale, biophysical model of flow‐induced red blood cell damage
Authors: Vitale Flavia , Nam Jaewook , Turchetti Luca , Behr Marek , Raphael Robert , Annesini Maria Cristina , Pasquali Matteo
Published: December 2013

A new model for mechanically induced red blood cell damage is presented. Incorporating biophysical insight at multiple length scales, the model couples flow‐induced deformation of the cell membrane (∼10 µm) to membrane permeabilization and hemoglobin transport (∼100 nm). We estimate hemolysis in macroscopic (above ∼1 mm) 2‐D inhomogeneous blood flow by computational fluid dynamics (CFD) and compare results with literature models. Simulations predict the effects of local flow field on RBC damage, due to the combined contribution of membrane permeabilization and hemoglobin transport. The multiscale approach developed here lays a foundation for a predictive tool for the optimization of hydrodynamic and hematologic design of cardiovascular prostheses and blood purification devices. © 2014 American Institute of Chemical Engineers AIChE J, 60: 1509–1516, 2014
Visualization study of flow condensation in hydrophobic microchannels
Authors: Chen Yongping , Shen Chaoqun , Shi Mingheng , Peterson George P.
Published: December 2013

A visualization study on flow condensation in hydrophobic rectangular silicon microchannels with hydraulic diameter of approximately 150 μm is conducted. Thin Au film with thickness of 200 nm is sputtered on channel surfaces to create a hydrophobic surface with an equilibrium contact angle of approximately 96°. In addition to traditional droplet flow, droplet‐annular compound flow, droplet‐injection compound flow, and droplet‐bubble/slug compound flow are also observed. The results indicate that injection location is postponed, and injection frequency increases with increasing inlet vapor Reynolds number and condensate Weber number. An empirical correlation of the injection location and injection frequency are presented and discussed. In particular, for a larger inlet vapor Reynolds number, the injection flow is closer to the channel outlet and the condensation heat transfer is enhanced. © 2014 American Institute of Chemical Engineers AIChE J, 60: 1182–1192, 2014
Epstein‐Barr virus antibody titer and its association with the domain scores from the World Health Organization's Quality of Life questionnaire: Findings from Rural Hainan Province, China
Authors: Inoue Yosuke , Yazawa Aki , Li Dandan , Du Jianwei , Jin Yuming , Chen Yan , Watanabe Chiho , Umezaki Masahiro
Published: December 2013

Objective

Epstein‐Barr virus (EBV) antibody titer has recently been used as a biomarker of psychological stress. This is the first study to investigate the association between EBV antibody titer and perceived quality of life (QOL) in Hainan Island, China.

Methods

Participants from two regions of Hainan Island, recruited into a larger study investigating the health impact of rapid economic development among rural residents, were stratified by age, sex, and region; 15 people were randomly selected from each of the 16 subgroups, to give a total sample size of 240. EBV antibody titer in dried blood spot samples was measured by enzyme‐linked immunosorbent assay. The abbreviated version of the World Health Organization's Quality of Life questionnaire was used to gather information on six categories of QOL. Multiple linear regression analysis was used to examine the relationship between EBV antibody titer and QOL.

Results

After adjusting for the effects of age, sex, region and C‐reactive protein concentration, EBV antibody titer was negatively associated with the physical (P = 0.044) and psychological QOL domains (P = 0.039).

Conclusion

This study suggests that among individuals living in an environment in the initial stages of economic development EBV antibody titer, a biomarker of psychological stress, is not only associated with the psychological aspects of QOL but is also linked to physical problems. Am. J. Hum. Biol. 26:51–55, 2014. © 2013 Wiley Periodicals, Inc.
Selective Hydrogen Production from Methanol with a Defined Iron Pincer Catalyst under Mild Conditions
Authors: Alberico Elisabetta , Sponholz Peter , Cordes Christoph , Nielsen Martin , Drexler Hans‐Joachim , Baumann Wolfgang , Junge Henrik , Beller Matthias
Published: December 2013

Molecularly well‐defined iron pincer complexes promote the aqueous‐phase reforming of methanol to carbon dioxide and hydrogen, which is of interest in the context of a methanol and hydrogen economy. For the first time, the use of earth‐abundant iron complexes under mild conditions for efficient hydrogen generation from alcohols is demonstrated.
Gold(I)‐katalysierte diastereoselektive Hydroacylierung terminaler Alkine mit Glyoxalen
Authors: Shi Shuai , Wang Tao , Weingand Vanessa , Rudolph Matthias , Hashmi A. Stephen K.
Published: December 2013

Die Reaktion eines α‐Ketoaldehyds und eines terminalen Alkins in Gegenwart von Piperidin und einer katalytischen Menge von AuCl liefert 1,2‐Dicarbonyl‐3‐ene, Produkte einer formalen Hydroacylierung der Dreifachbindung. Die Anwendungsbreite der Methode ist groß, verschiedene Arylsubstituenten an der Dicarbonyleinheit oder dem Alkin werden gut toleriert. Die Produkte können selektiv in Vinylchinoxaline überführt werden. Mechanistische Studien, inklusive Isotopenmarkierungsexperimente, weisen darauf hin, dass zunächst eine A3‐Umsetzung zu Propargylaminen führt und eine darauffolgende basenvermittelte Alkin/Allen‐Umlagerung und eine Hydrolyse der Enaminteilstruktur während der Aufarbeitung das formale Hydroacylierungsprodukt liefern.
PhI(OAc)2‐Mediated Radical Trifluoromethylation of Vinyl Azides with Me3SiCF3
Authors: Wang Yi‐Feng , Lonca Geoffroy Hervé , Chiba Shunsuke
Published: December 2013

The fluorine‐containing organic motif is becoming privileged in pharmaceuticals, agrochemicals, and functional materials, owing to its unique properties such as electron‐withdrawing character, metabolic stability, and lipophilicity. Described herein is the PhI(OAc)2‐mediated radical trifluoromethylation of vinyl azides with Me3SiCF3 to efficiently generate α‐trifluoromethyl azines. The resulting α‐trifluoromethyl azines were successfully transformed to valuable fluorine‐containing molecules such as α‐trifluoromethyl ketones, β‐trifluoromethyl amines, 5‐fluoropyrazoles, and trifluoroethyl isoquinolines.
Influence of the Absolute Configuration of NPE‐Caged Cytosine on DNA Single Base Pair Stability
Authors: Steinert Hannah S. , Schäfer Florian , Jonker Hendrik R. A. , Heckel Alexander , Schwalbe Harald
Published: December 2013

Photolabile protecting groups are a versatile tool to trigger reactions by light irradiation. In this study, we have investigated the influence of the absolute configuration of the 1‐(2‐nitrophenyl)ethyl (NPE) cage group on a 15‐base‐pair duplex DNA. Using UV melting, we determined the global stability of the unmodified and the selectively (S)‐ and (R)‐NPE‐modified DNA sequences, respectively. We observe a differently destabilizing effect for the two NPE stereoisomers on the global stability. Analysis of the temperature dependence of imino proton exchange rates measured by NMR spectroscopy reveals that this effect can be attributed to decreased base pair stabilities of the caged and the 3′‐neighbouring base pair, respectively. Furthermore, our NMR based structural models of the modified duplexes provide a structural basis for the distinct effect of the (S)‐ and the (R)‐NPE group.
Sb2Se3‐Sensitized Inorganic–Organic Heterojunction Solar Cells Fabricated Using a Single‐Source Precursor
Authors: Choi Yong Chan , Mandal Tarak Nath , Yang Woon Seok , Lee Yong Hui , Im Sang Hyuk , Noh Jun Hong , Seok Sang Il
Published: December 2013

The photovoltaic performance of Sb2Se3‐sensitized heterojunction solar cells, which were fabricated by a simple deposition of Sb2Se3 on mesoporous TiO2 by an approach that features multiple cycles of spin coating with a single‐source precursor solution and thermal decomposition, is reported. Poly[2,6‐(4,4‐bis(2‐ethylhexyl)‐4H‐cyclopenta[2,1‐b;3,4‐b′]dithiophene)‐alt‐4,7(2,1,3‐benzothioadiazole)] was used as the hole‐transporting material. The most efficient cell exhibited a short‐circuit current density of 22.3 mA cm−2, an open‐circuit voltage of 304.5 mV, and a fill factor of 47.2 %, yielding a power conversion efficiency of 3.21 % under standard test conditions (irradiation of 1000 W m−2, air mass=1.5 G). The results of this study imply that the developed approach has a high potential as a simple and effective route for the fabrication of efficient and inexpensive solar cells.
Combined Inhibitor Free‐Energy Landscape and Structural Analysis Reports on the Mannosidase Conformational Coordinate
Authors: Williams Rohan J. , Iglesias‐Fernández Javier , Stepper Judith , Jackson Adam , Thompson Andrew J. , Lowe Elisabeth C. , White Jonathan M. , Gilbert Harry J. , Rovira Carme , Davies Gideon J. , Williams Spencer J.
Published: December 2013

Mannosidases catalyze the hydrolysis of a diverse range of polysaccharides and glycoconjugates, and the various sequence‐based mannosidase families have evolved ingenious strategies to overcome the stereoelectronic challenges of mannoside chemistry. Using a combination of computational chemistry, inhibitor design and synthesis, and X‐ray crystallography of inhibitor/enzyme complexes, it is demonstrated that mannoimidazole‐type inhibitors are energetically poised to report faithfully on mannosidase transition‐state conformation, and provide direct evidence for the conformational itinerary used by diverse mannosidases, including β‐mannanases from families GH26 and GH113. Isofagomine‐type inhibitors are poor mimics of transition‐state conformation, owing to the high energy barriers that must be crossed to attain mechanistically relevant conformations, however, these sugar‐shaped heterocycles allow the acquisition of ternary complexes that span the active site, thus providing valuable insight into active‐site residues involved in substrate recognition.
Single‐Molecule Sensing of Environmental pH—an STM Break Junction and NEGF‐DFT Approach
Authors: Li Zhihai , Smeu Manuel , Afsari Sepideh , Xing Yangjun , Ratner Mark A. , Borguet Eric
Published: December 2013

Sensors play a significant role in the detection of toxic species and explosives, and in the remote control of chemical processes. In this work, we report a single‐molecule‐based pH switch/sensor that exploits the sensitivity of dye molecules to environmental pH to build metal–molecule–metal (m‐M‐m) devices using the scanning tunneling microscopy (STM) break junction technique. Dyes undergo pH‐induced electronic modulation due to reversible structural transformation between a conjugated and a nonconjugated form, resulting in a change in the HOMO–LUMO gap. The dye‐mediated m‐M‐m devices react to environmental pH with a high on/off ratio (≈100:1) of device conductivity. Density functional theory (DFT) calculations, carried out under the non‐equilibrium Green’s function (NEGF) framework, model charge transport through these molecules in the two possible forms and confirm that the HOMO–LUMO gap of dyes is nearly twice as large in the nonconjugated form as in the conjugated form.
Investigation of the Structure and Dynamics of the Capsid–Spacer Peptide 1–Nucleocapsid Fragment of the HIV‐1 Gag Polyprotein by Solution NMR Spectroscopy
Authors: Deshmukh Lalit , Ghirlando Rodolfo , Clore G. Marius
Published: December 2013

Structural studies of HIV‐1 Gag, the primary structural polyprotein involved in retroviral assembly, have been challenging, owing to its flexibility and conformational heterogeneity. Using residual dipolar couplings, we show that the four structural units of the capsid (CA)–spacer peptide 1 (SP1)–nucleocapsid (NC) fragment of HIV‐1 Gag (namely, the N‐ and C‐terminal domains of capsid, and the N‐ and C‐terminal Zn knuckles of nucleocapsid) have the same structures as their individually isolated counterparts, and tumble semi‐independently of one another in the absence of nucleic acids. Nucleic acids bind exclusively to the nucleocapsid domain and fix the orientation of the two Zn knuckles relative to one another so that the nucleocapsid domain/nucleic acid complex behaves as a single structural unit. The low 15N–{1H} heteronuclear NOE values (≤0.4), the close to zero values for the residual dipolar couplings of the backbone amides, and minimal deviations from random‐coil chemical shifts for the C‐terminal tail of capsid and SP1, both in the absence and presence of nucleic acids, indicate that these regions are intrinsically disordered in the context of CA–SP1–NC.
Activation of a Photodissociative Ruthenium Complex by Triplet–Triplet Annihilation Upconversion in Liposomes
Authors: Askes Sven H. C. , Bahreman Azadeh , Bonnet Sylvestre
Published: December 2013

Liposomes capable of generating photons of blue light in situ by triplet–triplet annihilation upconversion of either green or red light, were prepared. The red‐to‐blue upconverting liposomes were capable of triggering the photodissociation of ruthenium polypyridyl complexes from PEGylated liposomes using a clinical grade photodynamic therapy laser source (630 nm).
Cobalt Imidazolate Metal–Organic Frameworks Photosplit CO2 under Mild Reaction Conditions
Authors: Wang Sibo , Yao Wangshu , Lin Jinliang , Ding Zhengxin , Wang Xinchen
Published: December 2013

Metal–organic frameworks (MOFs) have shown great promise for CO2 capture and storage. However, the operation of chemical redox functions of framework substances and organic CO2‐trapping entities which are spatially linked together to catalyze CO2 conversion has had much less attention. Reported herein is a cobalt‐containing zeolitic imidazolate framework (Co‐ZIF‐9) which serves as a robust MOF cocatalyst to reduce CO2 by cooperating with a ruthenium‐based photosensitizer. The catalytic turnover number of Co‐ZIF‐9 was about 450 within 2.5 hours under mild reaction conditions, while still keeping its original reactivity during prolonged operation.
Reversible Self‐Assembly of Terpyridine‐Functionalized Graphene Oxide for Energy Conversion
Authors: Song Shungang , Xue Yuhua , Feng Lianfang , Elbatal Hany , Wang Pingshan , Moorefield Charles N. , Newkome George R. , Dai Liming
Published: December 2013

Terpyridine‐functionalized graphene oxides were prepared for self‐assembly into 3D architectures with various metal ions (e.g., Fe, Ru). The resulting electrode materials showed significantly improved electroactivities for efficient energy conversion and storage. They showed promise for application in the oxygen reduction reaction (ORR), photocurrent generation, and supercapacitance.
Efficacious Anticancer Drug Delivery Mediated by a pH‐Sensitive Self‐Assembly of a Conserved Tripeptide Derived from Tyrosine Kinase NGF Receptor
Authors: Moitra Parikshit , Kumar Krishan , Kondaiah Paturu , Bhattacharya Santanu
Published: December 2013

We present herein a short tripeptide sequence (Lys–Phe–Gly or KFG) that is situated in the juxtamembrane region of the tyrosine kinase nerve growth factor (Trk NGF) receptors. KFG self‐assembles in water and shows a reversible and concentration‐dependent switching of nanostructures from nanospheres (vesicles) to nanotubes, as evidenced by dynamic light scattering, transmission electron microscopy, and atomic force microscopy. The morphology change was associated with a transition in the secondary structure. The tripeptide vesicles have inner aqueous compartments and are stable at pH 7.4 but rupture rapidly at pH≈6. The pH‐sensitive response of the vesicles was exploited for the delivery of a chemotherapeutic anticancer drug, doxorubicin, which resulted in enhanced cytotoxicity for both drug‐sensitive and drug‐resistant cells. Efficient intracellular release of the drug was confirmed by fluorescence‐activated cell sorting analysis, fluorescence microscopy, and confocal microscopy.
An Unusual Example of Hypervalent Silicon: A Five‐Coordinate Silyl Group Bridging Two Palladium or Nickel Centers through a Nonsymmetrical Four‐Center Two‐Electron Bond
Authors: Nova Ainara , Suh Hee‐Won , Schmeier Timothy J. , Guard Louise M. , Eisenstein Odile , Hazari Nilay , Maseras Feliu
Published: December 2013

Pd and Ni dimers supported by PSiP ligands in which two hypervalent five‐coordinate Si atoms bridge the two metal centers are reported. Crystallographic characterization revealed a rare square‐pyramidal geometry at Si and an unusual asymmetric M2Si2 core (M=Pd or Ni). DFT calculations showed that the unusual structure of the core is also found in a model in which the phosphine and Si centers are not part of a pincer group, thus indicating that the observed geometry is not imposed by the PSiP ligand. NBO analysis showed that an asymmetric four‐center two‐electron (4c‐2e) bond stabilizes the hypervalent Si atoms in the M2Si2 core.
Gold(I)‐Catalyzed Diastereoselective Hydroacylation of Terminal Alkynes with Glyoxals
Authors: Shi Shuai , Wang Tao , Weingand Vanessa , Rudolph Matthias , Hashmi A. Stephen K.
Published: December 2013

The reaction of an α‐ketoaldehyde and a terminal alkyne in the presence of piperidine and a catalytic amount of AuCl delivers 1,2‐dicarbonyl‐3‐enes, products of the formal hydroacylation of the triple bond. The scope of the method is broad; different aryl substituents on the dicarbonyl unit and on the alkyne are well tolerated. The products can be transformed selectively into vinylquinoxalines. Mechanistic studies, including isotope‐labeling experiments, indicate that after an initial A3‐type conversion to propargylic amines, a subsequent base‐mediated alkyne‐to‐allene isomerization and a hydrolysis of the enamine substructure during the workup deliver the formal hydroacylation products.
Attenuation of the Aggregation and Neurotoxicity of Amyloid‐β Peptides by Catalytic Photooxygenation
Authors: Taniguchi Atsuhiko , Sasaki Daisuke , Shiohara Azusa , Iwatsubo Takeshi , Tomita Taisuke , Sohma Youhei , Kanai Motomu
Published: December 2013

Alzheimer’s disease (AD), a progressive severe neurodegenerative disorder, is currently incurable, despite intensive efforts worldwide. Herein, we demonstrate that catalytic oxygenation of amyloid‐β peptides (Aβ) might be an effective approach to treat AD. Aβ1–42 was oxygenated under physiologically‐relevant conditions (pH 7.4, 37 °C) using a riboflavin catalyst and visible light irradiation, with modifications at the Tyr10, His13, His14, and Met35 residues. The oxygenated Aβ1–42 exhibited considerably lower aggregation potency and neurotoxicity compared with native Aβ. Photooxygenation of Aβ can be performed even in the presence of cells, by using a selective flavin catalyst attached to an Aβ‐binding peptide; the Aβ cytotoxicity was attenuated in this case as well. Furthermore, oxygenated Aβ1–42 inhibited the aggregation and cytotoxicity of native Aβ.
A TRYPSIN‐LIKE PROTEINASE IN THE MIDGUT OF Ectomyelois ceratoniae ZELLER (LEPIDOPTERA: PYRALIDAE): PURIFICATION, CHARACTERIZATION, AND HOST PLANT INHIBITORS
Authors: Ranjbar Mina , Zibaee Arash , Sendi Jalal Jalali
Published: December 2013

A trypsin‐like proteinase was purified and characterized in the midgut of Ectomyelois ceratoniae. A purification process that used Sepharyl G‐100 and DEAE‐cellulose fast flow chromatographies revealed a proteinase with specific activity of 66.7 μmol/min/mg protein, recovery of 27.04 and purification fold of 23.35. Molecular weight of the purified protein was found to be 35.8 kDa. Optimal pH and temperature were obtained 9 and 20°C for the purified trypsin proteinase, respectively. The purified enzyme was significantly inhibited by PMSF, TLCK, and SBTI as specific inhibitors of trypsins in which TLCK showed the highest inhibitory effect. Trypsin proteinase inhibitors were extracted from four varieties of pomegranate including Brait, Torsh‐Sabz, May‐Khosh, and Shirin by ion exchange chromatography. It was found that fractions 17–20 of Brait; fractions 18 and 21–26 of Torsh‐Sabz; fractions 1–7, 11–17, and 19–21 of May‐Khosh and fraction 8 for Shirin showed presence of trypsin inhibitor in these host. Comparison of their inhibitory effects on the purified trypsin proteinase of E. ceratoniae demonstrated that fractions from May‐khosh variety had the highest effect on the enzyme among other extracted fractions. Characterization of serine proteinases of insects mainly trypsins is one of the promising methods to decrease population and damages via extracting their inhibitors and providing resistant varieties.
Difluorophenylglycinols as New Modulators of Proteolytic Processing of Amyloid Precursor Proteins
Authors: Chen Chia‐Yu , Liao Yung‐Feng , Chang Ming‐Yun , Hu Ming‐Kuan
Published: December 2013

Synthesis and evaluation of difluorophenylglycinols as new modulators of proteolytic processing of the amyloid‐β precursor proteins for Alzheimer's therapies were described. A range of N‐substituted (R)‐ and (S)‐difluorophenylglycinols, structured on the amino alcohol framework, were explored by incorporating the arylsulfonyl moieties and various N‐substituents. Evans' chiral auxiliary strategy was employed for the asymmetric synthesis of these enantiomeric difluorophenylglycinols. Compounds with effects on the γ‐secretase inhibition and ERK‐mediated signaling pathways were evaluated on cell‐based assays. Among them, N‐cyclopropylmethyl derivatives R‐12c and R‐13c showed modest γ‐secretase inhibition as well as ERK‐dependent activation.