bluuebunny/crossref_metadata_2025 huggingface dataset:
Analysis of the formation of fog and haze in North China Plain (NCP)
Authors: Quan J. , Zhang Q. , He H. , Liu J. , Huang M. , Jin H.
Published: April 2011

Abstract. North China Plain (NCP) is one of the most populated and polluted regions in China. During the recent years, haze and fog occur frequently and cause severely low visibility in this region. In order to better understand the impact of aerosol particles on the formation of haze and fog, a long-term record of haze and fog occurrences in the past 56 years (from 1954–2009) over NCP is analyzed. The results show that there are rapid changes in the occurrences of haze and fog over NCP. The occurrences of haze and fog were low during 1970–1980, and reached a maximum during 1981–1998. After 1999, the occurrences of haze and fog slightly decreased. There was a nonlinear relationship between the occurrences of haze and fog. When the occurrence of haze was lower than 40 days yr−1, the occurrence of fog was strongly proportional to the occurrence of haze. However, when the occurrence of haze was high (larger than 75 days yr−1), the occurrence of fog was not sensitive to the occurrence of haze. In order to better understand the relationship between the occurrences of haze and fog as well as the effect of aerosol particles on the formation of haze and fog, an in-situ field experiment was conducted during a period with a mixed occurrence of haze and fog. The analysis of the experiment suggests that there were considerably high aerosol concentrations during the measurement period, with an averaged aerosol number concentration of 24 000 cm−3. The measurement also shows that a large amount of aerosol particles can act as condensation nuclei to enhance the formation of fog droplets. As a result, a large amount of fog droplets (>1000 cm−3) with small size in radius (5–6 μm) were observed during the fog period, resulting in extremely low visibility (less than 100 m).
Snow optical properties at Dome C, Antarctica – implications for snow emissions and snow chemistry of reactive nitrogen
Authors: France J. L. , King M. D. , Frey M. M. , Erbland J. , Picard G. , MacArthur A. , Savarino J.
Published: April 2011

Abstract. Measurements of $e$-folding depth, nadir reflectivity and stratigraphy of the snowpack around Concordia station (Dome C, 75.10° S, 123.31° E) were undertaken and used to determine wavelength dependent coefficients (350 nm to 550 nm) for light scattering and absorption and to calculate potential fluxes of nitrogen dioxide (NO2) from the snowpack due to nitrate photolysis within the snowpack. The stratigraphy of the top 80 cm of Dome C snowpack generally consists of three main layers: a surface of soft windpack (not ubiquitous), a hard windpack and a hoar-like layer beneath the windpack(s). The $e$-folding depths are ~10 cm for the two windpack layers and ~20 cm for the hoar-like layer for solar radiation at a wavelength of 400 nm, about a factor 2–4 larger than previous model estimates for South Pole. Depth integrated photochemical reaction rates of nitrate photolysis in the Dome C snowpack were calculated to give molecular fluxes of NO2 of 5.3×1012 molecules m−2 s−1, 2.3×1012 molecules m−2 s−1 and 8×1011 molecules m−2 s−1 for solar zenith angles of 60°, 70° and 80° respectively for clear sky conditions using the TUV-snow radiative-transfer model. Depending upon the snowpack stratigraphy, a minimum of 85% of the NO2 originates from within the top 20 cm of the Dome C snowpack. It is found that on a multi-annual scale, nitrate photolysis can remove up to 80% of nitrate from surface snow, confirming independent isotopic evidence that photolysis is an important driver of nitrate loss occurring in the EAIS snowpack. However, the model cannot account for the total observed nitrate loss of 90–95% or the shape of the observed nitrate depth profile. A more complete model will need to include also physical processes such as evaporation, re-deposition or diffusion between the quasi-liquid layer on snow grains and firn air to account for the discrepancies.
Intra-annual variability of carbon and nitrogen stable isotopes in suspended organic matter in waters of the western continental shelf of India
Authors: Maya M. V. , Karapurkar S. G. , Naik H. , Roy R. , Shenoy D. M. , Naqvi S. W. A.
Published: April 2011

Abstract. The δ13C and δ15N of water-column suspended particulate organic matter (SPOM), elemental carbon and nitrogen concentrations, and C/N ratios in SPOM, along with ancillary chemical and biological variables including phytoplankton pigment abundance, were determined every month, with the partial exception of the southwest (SW) monsoon period, from March 2007 to September 2008 at a fixed site located off Goa (central west coast of India). The results reveal significant shifts in isotopic signatures, especially δ15N, of SPOM before and after the onset of the SW monsoon. Very low δ15N values, reaching a minimum of −4.17‰, are found during the pre-monsoon period. Although the average δ15N values for the SW monsoon (6.55‰) and post-monsoon (6.19‰) are substantially higher, these values are lower than expected from a region that experiences intense water-column denitrification, as well as those reported previously from the open Arabian Sea. Our results provide the first direct evidence for the addition of substantial amounts of isotopically light nitrogen by the diazotrophs, especially Trichodesmium, in the region. The δ15N of SPOM is generally lower than the mean value (7.38‰) for surficial sediments in the region, presumably because of diagenetic enrichment. The results support the notion that sedimentary δ15N may not necessarily reflect denitrification intensity in the overlying waters due to diverse sources of nitrogen and variability of its isotopic composition. The observed intra-annual variability of δ13C of SPOM is small (seasonal averages: pre-monsoon: −21.40‰, SW monsoon: −20.41‰ and post-monsoon: −22.15‰). Phytoplankton production and probably species composition could drive the observed changes. Occasional shifts in δ13C toward more negative values are suggestive of terrestrial inputs, but by and large the SPOM in the region seems to be of marine origin with relatively low and constant C/N ratios (5.8–6.5) occurring throughout the study period.
Extension of the Hapke bidirectional reflectance model to retrieve soil water content
Authors: Yang G.-J. , Zhao C.-J. , Huang W.-J. , Wang J.-H.
Published: April 2011

Abstract. Soil moisture links the hydrologic cycle and the energy budget of land surfaces by regulating latent heat fluxes. An accurate assessment of the spatial and temporal variation of soil moisture is important to the study of surface biogeophysical processes. Although remote sensing has proven to be one of the most powerful tools for obtaining land surface parameters, no effective methodology yet exists for in situ soil moisture measurement based on a Bidirectional Reflectance Distribution Function (BRDF) model, such as the Hapke model. To retrieve and analyze soil moisture, this study applied the soil water parametric (SWAP)-Hapke model, which introduced the equivalent water thickness of soil, to ground multi-angular and hyperspectral observations coupled with, Powell–Ant Colony Algorithm methods. The inverted soil moisture data resulting from our method coincided with in situ measurements (R2 = 0.867, RMSE = 0.813) based on three selected bands (672 nm, 866 nm, 2209 nm). It proved that the extended Hapke model can be used to estimate soil moisture with high accuracy based on the field multi-angle and multispectral remote sensing data.
Building hazard maps of extreme daily rainy events from PDF ensemble, via REA method, on Senegal River Basin
Authors: Giraldo J. D. , García Galiano S. G.
Published: April 2011

Abstract. The Sudano-Sahelian zone of West Africa, one of the poorest of the Earth, is characterized by high rainfall variability and rapid population growth. In this region, heavy storm events frequently cause extensive damage. Nonetheless, the projections for change in extreme rainfall values have shown a great divergence between Regional Climate Models (RCM), increasing the forecast uncertainty. Novel methodologies should be applied, taking into account both the variability provided by different RCMs, as well as the non-stationary nature of time series for the building of hazard maps of extreme rainfall events. The present work focuses in the probability density functions (PDFs)-based evaluation and a simple quantitative measure of how well each RCM considered can capture the observed annual maximum daily rainfall (AMDR) series on the Senegal River basin. Since meaningful trends have been detected in historical rainfall time series for the region, non-stationary probabilistic models were used to fit the PDF parameters to the AMDR time series. In the development of PDF ensemble by bootstrapping techniques, Reliability Ensemble Averaging (REA) maps were applied to score the RCMs. The REA factors were computed using a metric to evaluate the agreement between observed -or best estimated- PDFs, and that simulated with each RCM. The assessment of plausible regional trends associated to the return period, from the hazard maps of AMDR, showed a general rise, owing to an increase in the mean and the variability of extreme precipitation. These spatial-temporal distributions could be considered by local stakeholders in such a way as to reach a better balance between mitigation and adaptation.
Estimation of friction parameters in gravity currents by data assimilation in a model hierarchy
Authors: Wirth A.
Published: April 2011

Abstract. This paper is the last in a series of three investigating the friction laws and their parametrisation in idealised gravity currents in a rotating frame. Results on the dynamics of a gravity current (Wirth, 2009) and on the estimation of friction laws by data assimilation (Wirth and Verron, 2008) are combined to estimate the friction parameters and discriminate between friction laws in non-hydrostatic numerical simulations of gravity current dynamics, using data assimilation and a reduced gravity shallow water model. I demonstrate, that friction parameters and laws in gravity currents can be estimated using data assimilation. The results clearly show that friction follows a linear Rayleigh law for small Reynolds numbers and the estimated value agrees well with the analytical value obtained for non-accelerating Ekman layers. A significant and sudden departure towards a quadratic drag law at an Ekman layer based Reynolds number of around 800 is shown, in agreement with classical laboratory experiments. The drag coefficient obtained compares well to friction values over smooth surfaces. I show that data assimilation can be used to determine friction parameters and discriminate between friction laws and that it is a powerful tool in systematically connecting models within a model hierarchy.
Numerical modelling of thermodynamics and dynamics of sea ice in the Baltic Sea
Authors: Herman A. , Jedrasik J. , Kowalewski M.
Published: April 2011

Abstract. In this paper, a numerical dynamic-thermo-dynamic sea-ice model for the Baltic Sea is used to analyze the variability of ice conditions in three winter seasons. The modelling results are validated with station (water temperature) and satellite data (ice concentration) as well as by qualitative comparisons with the Swedish Meteorological and Hydrological Institute ice charts. Analysis of the results addresses two major questions. One concerns effects of meteorological forcing on the spatio-temporal distribution of ice concentration in the Baltic. Patterns of correlations between air temperature, wind speed, and ice-covered area are demonstrated to be different in larger, more open sub-basins (e.g., the Bothnian Sea) than in the smaller ones (e.g., the Bothnian Bay). Whereas the correlations with the air temperature are positive in both cases, the influence of wind is pronounced only in large basins, leading to increase/decrease of areas with small/large ice concentrations, respectively. The other question concerns the role of ice dynamics in the evolution of the ice cover. By means of simulations with the dynamic model turned on and off, the ice dynamics is shown to play a crucial role in interactions between the ice and the upper layers of the water column, especially during periods with highly varying wind speeds and directions. In particular, due to the fragmentation of the ice cover and the modified surface fluxes, the ice dynamics influences the rate of change of the total ice volume, in some cases by as much as 1 km3 per day. As opposed to most other numerical studies on the sea-ice in the Baltic Sea, this work concentrates on the short-term variability of the ice cover and its response to the synoptic-scale forcing.
A Pulsatile Simulator for the in Vitro Analysis of the Mitral Valve with Tri-Axial Papillary Muscle Displacement
Authors: Vismara Riccardo , Pavesi Andrea , Votta Emiliano , Taramasso Maurizio , Maisano Francesco , Fiore Gianfranco B.
Published: April 2011

Purpose

We developed a new pulsatile hydrodynamic simulator for the in vitro testing of mitral valve (MV) samples. The required specifications included a 3D positioning system for the papillary muscles (PMs) that is accurate and simple to manage; measurement of the force exerted by the chordae tendineae on the PMs; and the possibility to visually inspect the MV for kinematic analysis.

Methods

An atrial/ventricular chamber system was developed. The ventricular chamber housed a triaxial actuator system that was aligned to a morphometric Cartesian frame, allowing for PM positioning even while tests are running. Each PM holder had an embedded load cell for force measurement. The atrial chamber was designed so as to permit MV visual inspection, maintaining a non-disturbed flow at the sample inlet. The setup was subjected to trials with fresh porcine MVs. Flow and pressure difference across the MVs and PM forces were measured in different MV configurations, with different PM spatial dislocations. High speed video recordings were acquired.

Results

The positioning accuracy was assessed. Tests with MVs showed good usability, even by the non-engineering personnel. The effects of PM displacement on valve function (valve competence and PM forces) was consistent with previously published data, thus confirming the general soundness of the design principles.

Conclusions

The developed simulator is a promising instrument for performing MV in vitro tests in a precise, well-repeatable manner. The ability to completely adjust the PM position while a test is running boosts the simulator's potential for detailed investigations of the pathological and surgically treated MV.
Economic Benefit to Gardeners and Retailers from Cultivating and Marketing Vegetables in Niamey, Niger
Authors: Diogo Rodrigue V.C. , Buerkert Andreas , Schlecht Eva
Published: April 2011

Little is known about the effects of season and marketplace on the return obtained by urban gardeners and retailers in West African cities from the cultivation and sale of amaranth, cabbage, lettuce and tomato. To fill this knowledge gap, measurements of yields and weekly price interviews were conducted in Niamey, Niger, during the rainy season (August–October) and the cool dry season (November–January) of 2007–08. Using gross margin (GM) analysis, net profits (NP) and returns (R) on investments were calculated. During the rainy season, farm-gate prices of tomato averaged 660 FCFA kg−1 fresh matter, compared with 450 FCFA kg−1 fresh matter (p < 0.05) in the cool dry season, while prices of amaranth, lettuce and cabbage were more stable across seasons (100 FCFA = 0.15 Euro). The estimated GM (FCFA per hectare and season) and R (FCFA per FCFA invested) were 5.83m (R = 12.78) for amaranth, 10.09m (R = 18.98) for cabbage, 5.90m (R = 12.21) for lettuce and 6.40m (R = 16.58) for tomato during the cool dry season, compared with 4.71m (R = 8.44, amaranth), 9.50m (R = 13.48, cabbage), 6.52m (R = 7.08, lettuce) and 15.17m (R = 23.46, tomato) in the rainy season. Inputs in terms of labour, fertilizers and seeds strongly affected returns. Cabbage and tomato market prices (per kg FM) averaged 804 FCFA and 832 FCFA in the rainy season, compared with 410 FCFA (p < 0.05) and 574 FCFA (p < 0.05) in the cool dry season. For amaranth and lettuce, the NP of market retailers depended only on marketplace, whereas the NP of cabbage and tomato strongly depended on season and marketplace. Reducing mineral fertilizer use would lower production costs and thus increase gardeners' profits; at the same time, it would reduce environmental hazards ensuing from urban vegetable production in Niamey
Evaluation of a Distance Education Radio Farm School Programme in India: Implications for Scaling up
Authors: Sasidhar P.V.K. , Suvedi Murari , Vijayaraghavan K. , Singh Baldev , Babu Suresh
Published: April 2011

Distance education radio programmes on poultry farming with registered participants were organized using the local language in an effort to link researchers to rural poultry farmers through radio broadcasts. This study, based on data from 74 participants and 60 non-participants, assesses the impact of the radio farm school on participants using Bennett's hierarchy. Information gathered from the participants included the inputs used, the production activities carried out, the outputs obtained and the reactions of the participants with respect to listening behaviour, opinions, knowledge, attitudes, adoption changes and SWOT parameters. Overall, the evaluation found that the farm school on radio with registered participants had a major impact on developing awareness, knowledge and changes in attitude and in involving end-users in outreach activities. The related implications for scaling up and harnessing the medium of radio to disseminate outreach information are discussed.
Critical External Factors behind Hotels' Investments in Innovation and Technology in Emerging Urban Destinations
Authors: Fernández Juan Ignacio Pulido , Cala Antonia Sáez , Domecq Cristina Figueroa
Published: April 2011

The decision-making processes of tourism firms are being conditioned by the profound transformations taking place in both client demand and destination dynamics. This new scenario requires an increased level of information, innovation and technology if tourism firms are to remain competitive. In particular, information and communication technologies (ICTs) can provide competitive advantages by improving a firm's knowledge of its own internal structures and of the milieu in which it is operating. This study therefore identifies and analyses the critical external factors that influence innovation and ICT investment in hotel businesses by evaluating the impact of hotel investment strategies. The methodological approach taken is an adaptation of the PESTEL model to the particular case of hotel management. This model identifies the factors (political, economic, social, environmental, technological and legal) that affect any given organization. The authors also apply Porter's ‘five forces model’, which assesses the competitive environment in which firms act, taking into account the power of buyers, intermediaries, current and potential competitors and substitutive products. The study area is the region of Madrid (MAC), since this has only lately emerged as a major tourist destination and its hotel market is recent and of medium to high quality.
What's Pushing International Tourism Expenditures?
Authors: Vietze Christoph
Published: April 2011

This paper examines the socio-economic determinants that contribute to outbound tourism expenditures in countries of origin. The author finds a strict, robust, positive impact of all economic factors, such as per capita income and openness to trade, on tourism expenditure per capita, as well as on tourism expenditure per GDP. There seems to be a mutual openness to tourism as countries able to attract high inbound tourism receipts per capita also have high outbound tourism expenditures per capita. A further important finding is that people in democratic countries spend a higher share of income on travelling abroad. The results offer an encouraging suggestion that it makes sense for developing countries to invest in the tourism sector, as an increasing willingness to pay for outbound tourism goes hand in hand with an increasing per capita income.
Research Note: Internationalization of US Publicly Traded Restaurant Companies – a Transaction Cost Economics Perspective
Authors: Lee Seoki , Koh Yoon , Heo Cindy Yoonjoung
Published: April 2011

In the internationalization literature of economics, many theories have been applied to various issues, but transaction cost economics remains significant among other prominent theories. The original intention of transaction cost economics was to explain the nature of firms in general; however, the approach has subsequently been applied to international operations. Despite the prevalent use of the theory to explain internationalization issues, few empirical examinations have been undertaken through its application in the hospitality literature. This study therefore examines the internationalization of US publicly traded restaurant companies through transaction cost economics.
A Theoretical Study of the Hidden Wounds of War: Disenfranchised Grief and the Impact on Nursing Practice
Authors: Aloi Janice A.
Published: April 2011

Combat veterans face enormous challenges upon the return to civilian life, one of which is the ability to integrate incidences of death and killing into a healthy postdeployment life. This paper presents the lived experience of grief and loss resulting from the trauma of war. Social constructionist theory, due to its emphasis on meaning-making, serves as the theoretical framework. The effects of inhibited mourning due to the inability to mourn in combat and lack of nurturing upon returning home are described. Personal excerpts derived from interviews of warfare from veterans that experienced death and killing are presented. It is suggested that combat veterans experience a unique form of grief and therefore require a style of grieving that differs from those that have not served on the battlefield. Regardless of the point of care, nurses are positioned to help with the challenges of readjustment. A better understanding of combat veterans as a disenfranchised group would enable nurses to intervene in ways that contribute to the readjustment process.
Sodium Hydroxide
Authors: Eggeman Tim
Published: April 2011

Alkali and chlorine products are a group of commodity chemicals which includes sodium hydroxide (caustic soda). Electrolysis of sodium chloride accounts for nearly all of today's installed capacity for sodium hydroxide. Electrolysis is done in one of the three types of cells: mercury cell; diaphragm cell; and membrane cell. Phase‐out of the mercury cell is recommended. New installations call for the membrane cell since they give good performance with low energy requirements. Caustic soda is classified as a corrosive material. Dow is the largest producer of caustic soda in the world. Caustic soda is corrosive to all body tissue. The main environmental concern is for producers that use mercury cells. The pulp and paper industry, producers of inorganic and organic chemicals and aluminum manufacturers are the primary users. Other significant end uses include textiles, soaps and detergents, and water treatment.
Sustainable Development and Chemistry
Authors: Cavani Fabrizio , Centi Gabriele
Published: April 2011

The review covers the new trends in the design of industrial chemical processes that can reduce the impact on environment and at the same time be sustainable from the economic point of view. Significant attention is also given to the opportunities given from new technologies, catalysts and materials, and process control to develop sustainable industrial processes.

Aspects that are covered include the use of alternative or renewable raw materials (and biomasses), the reducing of the risks and number of steps in chemical processes, the reduction of energy consumption (and the use of alternative energy sources in chemical processes), the design of intrinsically safe processes, the down‐sizing of the chemical production and the opportunities offered from micro‐reactor and integrated reaction/separation technologies, the possibilities deriving from process intensification, and the reduction of waste by introducing new catalytic routes and/or solvents. Emphasis is given to the role of catalysis to develop new sustainable industrial processes, with also an overview of the new opportunities given from advanced catalytic materials and technologies.
Acetylenic Polymers
Authors: Liu Jianzhao , Lam Jacky W. Y. , Tang Ben Zhong
Published: April 2011

The development of fundamental synthetic chemistry of acetylenic polymers, which not only refers to polyacetylenes but also to all the polymers synthesized from acetylenic monomers containing single or multiple carbon–carbon triple bonds, is summarized in this review. The design of new monomers with one, two, and three triple bonds, explorations of functional tolerant organic and organometallic catalysts, and development of effective linear and nonlinear triple bond‐based polymerization processes have led to successful syntheses of a large variety of acetylenic polymers with miscellaneous structures and advanced specialty properties.
Fabrics, Coated
Authors: Teumac Fred M.
Published: April 2011

Desirable properties of a fabric can be supplemented by coating it with a polymer. The fabric provides tensile, tear, and elongation control. The coating reduces porosity, protects the fabric from the chemical (water, acid or base, solvents) and physical (temperature, stress, flexing) environment, and, in some cases, provides decorative effects. Different fabrics and coating materials are discussed, as well as an overview of different coating methods.
Flocculation
Authors: Rose Gerard R. , John Michael R. St.
Published: April 2011

The process of flocculation is the gathering together or aggregation of small masses, usually in a liquid media, into larger masses called flocs. Although this definition is generally applicable, various other definitions or refinements, especially when used in conjunction with the term coagulation, may be found in the literature. Small suspended particles or colloids impede the separation of solids and liquids, resulting, for example, in excessively long sedimentation or filtration times. Increasing the particle size by flocculation alleviates these difficulties. The objectives of flocculation are to allow rapid separation or drainage of the liquid phase from a suspended solid phase, minimize the solids remaining in the liquid phase, and maximize the solids content in the solid phase (dewatering). In order for flocculation to occur, chemicals called flocculants or coagulants are introduced to the solid suspension. Most of these chemicals are water‐soluble polymers The principal practical applications of flocculation are in raw and waste‐water clarification, sludge dewatering, mineral processing, and paper making.
On the Formation of White‐Spot Defects in a Superalloy VAR Ingot
Authors: Grignard Jean François , Soller Aude , Jourdan Julien , Bellot Jean‐Pierre , Jardy Alain
Published: April 2011

For the production of nickel‐based superalloys for the aerospace industry, strict control of the macrostructure of the product is necessary to avoid the appearance of potentially fatal defects. Our study focuses on the prevention of “white spots” in the alloy IN 718. These defects, which are small volumes of a few millimeters of characteristic length, are depleted in niobium. They are known to result from the fall of metal fragments in the liquid pool during VAR processing. According to their history in the liquid metal, these fragments could not being remelted before being trapped in the mushy zone and then give rise to defects. A model calculates the heat transfer in such a precursor to simulate its melting during his stay in the bath. The validation of the predicted melting kinetics requires a series of immersive experiences of synthetic defects in a metal bath. The model and experiments have demonstrated the initial solidification of a layer of metal around the precursor.
Smart Homopolymer Modification to Single Glass Conical Nanopore Channels: Dual‐Stimuli‐Actuated Highly Efficient Ion Gating
Authors: Zhang Li‐Xiang , Cai Sheng‐Lin , Zheng Yu‐Bin , Cao Xiao‐Hong , Li Yao‐Qun
Published: April 2011

For the first time, the integration of a smart homopolymer poly[2–(dimethylamino) ethyl methacrylate] (PDMAEMA), which undergoes both pH‐ and temperature‐induced conformational transitions, is demonstrated in a single glass conical nanopore channel, to achieve a smart nanodevice that can be reversibly switched between the high conducting “on” state and low conducting “off” state with high gating efficiency due to the conformational changes of the homopolymer brush effected by varying the pH and temperature of the surrounding media.
Amine‐Linked N‐Heterocyclic Carbenes: The Importance of an Pendant Free‐Amine Auxiliary in Assisting the Catalytic Reaction
Authors: Li Chia‐Yi , Kuo Yi‐Yin , Tsai Jie‐Hong , Yap Glenn P. A. , Ong Tiow‐Gan
Published: April 2011

We have successfully expanded the library of amino–NHCs with varying substituents on the amine group, leading to insight about the instability of NHCs arising from the intermolecular interaction of the dangling amine side‐arm. However, the pendant amine plays an important role with respect to the catalytic process, resuscitating the catalytic activity of unsaturated NHC’s through a synergistic effect invoked by the secondary amine. This proof of concept allows us to expand the spectrum of catalysis to CC, as well as CB bond formation.
Syntheses and Structures of Ruthenium(II) N,S‐Heterocyclic Carbene Diphosphine Complexes and their Catalytic Activity towards Transfer Hydrogenation
Authors: Ding Nini , Hor T. S. Andy
Published: April 2011

Phosphine exchange of [RuIIBr(MeCOO)(PPh3)2(3‐RBzTh)] (3‐RBzTh=3‐benzylbenzothiazol‐2‐ylidene) with a series of diphosphines (bis(diphenylphosphino)methane (dppm), 1,2‐bis(diphenylphosphino)ethylene (dppv), 1,1′‐bis(diphenylphosphino)ferrocene (dppf), 1,4‐bis(diphenylphosphino)butane (dppb), and 1,3‐(diphenylphosphino)propane (dppp)) gave mononuclear and neutral octahedral complexes [RuBr(MeCOO)(η2‐P2)(3‐RBzTh)] (P2=dppm (2), dppv (3), dppf (4), dppb (5), or dppp (6)), the coordination spheres of which contained four different ligands, namely, a chelating diphosphine, carboxylate, N,S‐heterocyclic carbene (NSHC), and a bromide. Two geometric isomers of 6 (6a and 6 b) have been isolated. The structures of these products, which have been elucidated by single‐crystal X‐ray crystallography, show two structural types, I and II, depending on the relative dispositions of the ligands. Type I structures contain a carbenic carbon atom trans to the oxygen atom, whereas two phosphorus atoms are trans to bromine and oxygen atoms. The type II system comprises a carbene carbon atom trans to one of the phosphorus atoms, whereas the other phosphorus is trans to the oxygen atom, with the bromine trans to the remaining oxygen atom. Complexes 2, 3, 4, and 6a belong to type I, whereas 5 and 6 b are of type II. The kinetic product 6 b eventually converts into 6a upon standing. These complexes are active towards catalytic reduction of para‐methyl acetophenone by 2‐propanol at 82 °C under 1 % catalyst load giving the corresponding alcohols. The dppm complex 2 shows the good yields (91–97 %) towards selected ketones.
The Role of Water for the Phase‐Selective Preparation of Hexagonal and Cubic Cobalt Oxide Nanoparticles
Authors: Shim Jae Ha , Nam Ki Min , Seo Won Seok , Song Hyunjoon , Park Joon T.
Published: April 2011

A selective preparation and the formation mechanism of hexagonal and cubic CoO nanoparticles from the reaction of [Co(acac)2] (acac=acetylacetonate) and amine have been investigated. CoO nanoparticles with a hexagonal pyramidal shape were yielded under decomposition conditions with amine. Importantly, the addition of water altered the final phase to cubic and comprehensively changed the reaction mechanism. The average sizes of the hexagonal and cubic CoO nanoparticles could be controlled either by changing the amine concentration or by using different reaction temperatures. Detailed formation mechanisms are proposed on the basis of gas chromatography–mass spectrometry data and color changes of the reaction mixture. The hexagonal CoO phase is obtained through two distinct pathways: solvolysis with CC bond cleavage and direct condensation by amine. On the other hand, the cubic CoO nanoparticles were synthesized by strong nucleophilic attack of hydroxide ions from water and subsequent CC bond breaking. The resulting caboxylate ligand can stabilize a cobalt hydroxide intermediate, leading to the generation of a thermodynamically stable CoO phase.
Phosphane‐Free Green Protocol for Selective Nitro Reduction with an Iron‐Based Catalyst
Authors: Sharma Upendra , Verma Praveen Kumar , Kumar Neeraj , Kumar Vishal , Bala Manju , Singh Bikram
Published: April 2011

Iron phthalocyanine with iron sulfate has been successfully applied for high chemo‐ and regioselective reduction of aromatic nitro compounds to give the corresponding amines in a green solvent system without using any toxic ligand. The catalytic systems were also compatible with a large range of other reducible functional groups, such as keto, acid, amide, ester, halogen, lactone, nitrile, N‐benzyl, O‐benzyl, hydroxy, and heterocycles. In the present study, dinitro compounds have been regioselectively reduced to the corresponding amines with high yield. In most of the cases the conversion and selectivity was greater than 99 % as determined by GC‐MS analysis.
Maximizing the data transmission rate of a cooperative relay system in an underwater acoustic channel
Authors: Babu A. V. , Joshy Susan
Published: April 2011

In this paper, we investigate the problem of maximizing the data transmission rate of a cooperative relay system in an underwater acoustic communication channel. With amplify‐and‐forward relaying and adaptive source transmission, we present optimal transmit signal power adaptation policies that maximize the data transmission rate, considering both frequency and time domains. The analysis takes into account a physical model of acoustic path loss and ambient noise power spectral density. Typical characteristics of underwater channel such as frequency‐dependent fading and time variations are also considered. Capacity bounds for channel state information (CSI) only at the receiver and CSI at both transmitter and receiver are presented. To maximize the data rate, we use the notion of an optimal bandwidth which corresponds to efficient allocation of signal power across the transmission bandwidth. Under the constraint of an average transmit power, the optimal transmit power adaptation policy is found to be ‘water‐pouring’ in frequency‐time domain, while the transmit power adaptation policy with a total power constraint is ‘water‐pouring’ in frequency domain. Results show that both frequency domain and frequency‐time domain power adaptation schemes provide much greater improvement in average data rate over that of the constant power case. Copyright © 2011 John Wiley & Sons, Ltd.
In vitro production of gymnemic acid from cell suspension cultures of Gymnema sylvestre R. Br
Authors: Nagella Praveen , chung Ill‐Min , Murthy Hosakatte Niranjana
Published: April 2011

Gymnema sylvestre is an important medicinal plant that bears bioactive compound namely gymnemic acids. The present work deals with the optimization of a cell suspension culture system of Gymnema sylvestre for the production of biomass and gymnemic acid, which has anti‐diabetic properties. We investigated the effect of inoculum densities (2.5–20.0 g/L), the strength of the Murashige and Skoog (MS) medium (0.25–2.0), carbon source (sucrose, glucose, fructose, maltose), and the concentration of the sucrose (1–8% w/v) to determine their effects on biomass accumulation and production of gymnemic acid. Overall, 10 g/L of inoculum density, full‐strength MS medium supplemented with 2,4‐dichlorophenoxy acetic acid (2.0 mg/L) and Kinetin (0.1 mg/L), and 3% w/v sucrose was found best for the accumulation of biomass and gymnemic acid content (9.95 mg/g dry weight). The results of the current study will be useful for bioprocess and biochemical engineers for large‐scale production of gymnemic acid in cell culture.
Relationship of resting EEG with anatomical MRI measures in individuals at high and low risk for depression
Authors: Bruder Gerard E. , Bansal Ravi , Tenke Craig E. , Liu Jun , Hao Xuejun , Warner Virginia , Peterson Bradley S. , Weissman Myrna M.
Published: April 2011

Studies have found abnormalities of resting EEG measures of hemispheric activity in depressive disorders. Similar EEG findings and a prominent thinning of the cortical mantle have been reported for persons at risk for depression. The correspondence between EEG alpha power and magnetic resonance imaging (MRI) measures of cortical thickness was examined in a multigenerational study of individuals at risk for depression. Seventy‐five participants underwent resting EEG and approximately 5 years later underwent MRI scanning. High‐risk participants (n = 37) were biological descendants of probands having major depression and low‐risk participants (n = 38) were descendants of individuals without a history of depression. EEG alpha power was interpolated across the surface of a template brain and coregistered with measures of cortical thickness. Voxel‐wise correlations of cortical thickness and alpha power were computed while covarying for age and gender. The high‐risk group, when compared to the low‐risk group, showed greater alpha asymmetry in an eyes‐closed condition, with relatively less activity over right parietal cortex. Alpha power correlated inversely with cortical thickness, particularly over the right posterior region, indicating that EEG evidence of reduced cortical activity was associated with increased cortical thinning. This is the first report of widespread correlation of EEG alpha activity with MRI measures of cortical thickness. Although both EEG and MRI measures are associated with risk for depression, we did not detect evidence that cortical thickness mediated the alpha asymmetry findings. Thus, alpha asymmetry, alone or in combination with MRI, may be a marker of vulnerability for a familial form of depression. Hum Brain Mapp, 2011. © 2011 Wiley Periodicals, Inc.
Spatiotemporal brain mapping of spatial attention effects on pattern‐reversal ERPs
Authors: Di Russo Francesco , Stella Alessandra , Spitoni Grazia , Strappini Francesca , Sdoia Stefano , Galati Gaspare , Hillyard Steven A. , Spinelli Donatella , Pitzalis Sabrina
Published: April 2011

Recordings of event‐related potentials (ERPs) were combined with structural and functional magnetic resonance imaging (fMRI) to investigate the timing and localization of stimulus selection processes during visual‐spatial attention to pattern‐reversing gratings. Pattern reversals were presented in random order to the left and right visual fields at a rapid rate, while subjects attended to the reversals in one field at a time. On separate runs, stimuli were presented in the upper and lower visual quadrants. The earliest ERP component (C1, peaking at around 80 ms), which inverted in polarity for upper versus lower field stimuli and was localized in or near visual area V1, was not modulated by attention. In the latency range 80–250 ms, multiple components were elicited that were increased in amplitude by attention and were colocalized with fMRI activations in specific visual cortical areas. The principal anatomical sources of these attention‐sensitive components were localized by fMRI‐seeded dipole modeling as follows: P1 (ca. 100 ms—source in motion‐sensitive area MT+), C2 (ca. 130 ms—same source as C1), N1a (ca. 145 ms—source in horizontal intraparietal sulcus), N1b (ca. 165 ms—source in fusiform gyrus, area V4/V8), N1c (ca. 180 ms—source in posterior intraparietal sulcus, area V3A), and P2 (ca. 220 ms—multiple sources, including parieto‐occipital sulcus, area V6). These results support the hypothesis that spatial attention acts to amplify both feed‐forward and feedback signals in multiple visual areas of both the dorsal and ventral streams of processing. Hum Brain Mapp, 2011. © 2011 Wiley‐Liss, Inc.
Encapsulation of Drug Molecules by Cucurbiturils: Effects on their Chemical Properties in Aqueous Solution
Authors: Macartney Donal H.
Published: April 2011

The effects of the encapsulation of drugs and other molecules of biomedical interest by cucurbit[n]uril (n=5–8, 10) host molecules on the chemical properties of the drugs in aqueous solution are reviewed. The cucurbituril complexation of drug molecules has been shown to generally increase the guests’ pKa values through preferential inclusion of the protonated species, modulate other equilibria involving the guest, improve the solubility in aqueous solution, reduce the toxicity and other side effects, as well as enhance the stability and targeted delivery of the drug molecule. These benefits have led to an increasing interest in the applications of cucurbit[n]urils in novel drug formulations.
Synthesis of novel acyclonucleosides containing pyridazine
Authors: Park Jung‐Won , Kweon Deok‐Heon , Kang Young‐Jin , Lee Woo Song , Cho Su‐Dong , Yoon Yong‐Jin
Published: April 2011

This paper presents the synthesis of some novel acyclonucleosides involving pyrrolo[2,3‐c]pyridazine and 4‐hydroxybutyl side chain.
Money over man versus caring and compassion? Challenges for today's organizations and their leaders
Authors: Peus Claudia
Published: April 2011

This commentary discusses three important topics in organizational behavior that have been largely ignored previously: Organizational responses to terrorism, positive deviance in organizations, and the creation of caring and compassionate organizations. The article highlights the challenges these three topics pose for organizational leaders. Furthermore, it explores future directions of research that might facilitate a deeper understanding of these topics as well as organizational behavior in general. Copyright © 2011 John Wiley & Sons, Ltd.
Chromatographic characteristics of poly(1‐vinylimidazole)‐grafted silica in normal‐phase HPLC
Authors: Sun Min , Feng Juanjuan , Liu Shujuan , Wang Xusheng , Liu Xia , Jiang Shengxiang
Published: April 2011

A stationary phase based on poly(1‐vinylimidazole)‐grafted silica has been prepared by the surface radical chain‐transfer reaction. The stationary phase was characterized by infrared spectra, X‐ray photoelectron spectroscopy and elemental analysis. Chromatographic characteristics of the stationary phase were investigated in normal‐phase HPLC. The results showed that both weak polar compounds (polycyclic aromatic hydrocarbons, dialkyl phthalates) and polar compounds (anilines, phenols) could be successfully separated on this stationary phase, implying better separation performance than blank silica and conventional aminopropyl‐bonded silica under the same conditions. The excellent performance can be attributed to multiple interactions between surface modifier and the analytes that might include dipole, hydrogen bonding, H‐π, electrostatic and inductive interactions.
Biodegradable Glutaraldehyde‐crosslinked Casein Conduit Promotes Regeneration after Peripheral Nerve Injury in Adult Rats
Authors: Wang Walter , Lin Jia‐Horng , Tsai Chin‐Chuan , Chuang Hao‐Che , Ho Chien‐Yi , Yao Chun‐Hsu , Chen Yueh‐Sheng
Published: April 2011

In this study, GCC protein was used for the first time to construct a biodegradable conduit for peripheral nerve repair. The GCC was highly stable with a sufficiently high level of mechanical properties and it was non‐toxic and non‐apoptotic which could maintain the survival and outgrowth of Schwann cells. Noninvasive bioluminescence imaging accompanied with histochemical assessment showed the GCC was highly biocompatible after subcutaneous implantation in transgenic mice. Electrophysiology, labeling of calcitonin gene‐related peptide in the lumbar spinal cord and histology analysis also showed a rapid morphological and functional recovery for disrupted rat sciatic nerves repaired with the GCC conduits. Therefore, we conclude that the GCC can offer great nerve regeneration characteristics and can be a promising material for the successful repair of peripheral nerve defects.

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A Highly Efficient One‐Pot Method for the Synthesis of Carbon Black/Poly(4,4′‐Diphenylether‐1,3,4‐Oxadiazoles) Composites
Authors: Loos Marcio R. , Abetz Volker , Schulte Karl
Published: April 2011

A series of polyoxadiazoles (PODs) based composites containing carbon black (CB) are prepared through a fast polycondensation reaction of hydrazine sulfate and dicarboxylic acid monomers using poly(phosphoric acid) (PPA) as reaction medium. In order to achieve a homogeneous dispersion of CB, a predispersion step is applied to the CB prior to the synthesis. The moderate acidic nature and high viscosity of the PPA medium promote the oxidation of the CB and suppress reaggregation after dispersion. The carboxylic groups generated on the surface of the CB effectively anchored the growing of POD chains, improving the interfacial interaction between the CB and the surrounding matrix. An increase of 22% in storage modulus at 100 °C is observed. The tensile strength increases up to 48% with the CB addition and the elongation at break increases up to 118% at a low concentration of CB (0.5 wt.‐%). The resultant CB/POD composites, which can be cast as dense films, are soluble in several polar aprotic solvents and their POD matrix have molecular weights in the range of 105 g · mol−1. The high‐performance, high‐temperature light‐weight materials obtained are thermally stable at temperatures as high as 450 °C.

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Origin of Piezoelectricity in an Electrospun Poly(vinylidene fluoride‐trifluoroethylene) Nanofiber Web‐Based Nanogenerator and Nano‐Pressure Sensor
Authors: Mandal Dipankar , Yoon Sun , Kim Kap Jin
Published: April 2011

A single stage electrospinning process can give rise to preferentially oriented induced dipoles in poly(vinylidene fluoride‐trifluoroethylene) [P(VDF‐TrFE)] nanofibers. The piezoelectricity of as‐electrospun P(VDF‐TrFE) nanofiber webs opens up new possibilities for their use as a flexible nanogenerators and nano‐pressure sensors. In this work, the origin of the piezoelectricity has been spotlighted by randomization of the induced dipoles at the Curie temperature and analyzed by polarized FT‐IR spectroscopic techniques as well as by detecting the piezoelectric signal from a nano‐pressure sensor.

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Computational geomechanics: The heritage of Olek Zienkiewicz
Authors: Pastor M. , Chan A. H. C. , Mira P. , Manzanal D. , Fernández Merodo J. A. , Blanc T.
Published: April 2011

Geotechnical engineering design is based on mathematical, constitutive and numerical models implemented in computer codes which are able to predict the behaviour of geostructures and foundations under a wide variety of loading conditions, sometimes demanding or extreme. Prediction is fundamental in areas such as seismic engineering, marine foundations or landslide hazard analysis. No computer code is better than the mathematical, constitutive and numerical models which it implements. This paper is devoted to (i) reviewing the decisive contributions of Professor Olek Zienkiewicz to the development of mathematical, constitutive and numerical models in geotechnical engineering and (ii) presenting some extensions based on his work which have been proposed by the authors. The extensions to be described here are the following: (i) a particularization of the u − prmw Zienkiewicz model to the case of fast catastrophic landslides (ii) an extension of the generalized plasticity model proposed by him and (iii) an SPH numerical model for the propagation of fast catastrophic landslides. Copyright © 2011 John Wiley & Sons, Ltd.