bluuebunny/crossref_metadata_2025 huggingface dataset:
Routing bandwidth guaranteed paths for traffic engineering in WiMAX mesh networks
Authors: Misra Sudip , Ghosh Tushar I. , Obaidat Mohammad S.
Published: April 2013

In this paper, the authors present a novel algorithm for computing bandwidth guaranteed paths for traffic engineering in WiMAX IEEE 802.16 standard based networks using the mesh topology. The underlying algorithm fulfills routing requests ‘on the fly’ without a priori knowledge of future requests. This problem is motivated by the need for efficient handling of traffic and network resource utilization. The key idea behind the solution is the use of heuristic methods to defer routing through certain nodes, which have a higher chance of getting selected because of hop constraints, so that they can be prevented from congestion. Simulation‐based performance evaluation shows that the proposed algorithm performs well in comparison with the selected benchmarks on metrics such as the number of rejected requests and the active links present in the network. Copyright © 2013 John Wiley & Sons, Ltd.
Wheat genotypes differing in aluminum tolerance differ in their growth response to CO2 enrichment in acid soils
Authors: Tian Qiuying , Zhang Xinxin , Gao Yan , Bai Wenming , Ge Feng , Ma Yibing , Zhang Wen‐Hao
Published: April 2013

Aluminum (Al) toxicity is a major factor limiting plant growth in acid soils. Elevated atmospheric CO2 [CO2] enhances plant growth. However, there is no report on the effect of elevated [CO2] on growth of plant genotypes differing in Al tolerance grown in acid soils. We investigated the effect of short‐term elevated [CO2] on growth of Al‐tolerant (ET8) and Al‐sensitive (ES8) wheat plants and malate exudation from root apices by growing them in acid soils under ambient [CO2] and elevated [CO2] using open‐top chambers. Exposure of ET8 plants to elevated [CO2] enhanced root biomass only. In contrast, shoot biomass of ES8 was enhanced by elevated [CO2]. Given that exudation of malate to detoxify apoplastic Al is a mechanism for Al tolerance in wheat plants, ET8 plants exuded greater amounts of malate from root apices than ES8 plants under both ambient and elevated [CO2]. These results indicate that elevated [CO2] has no effect on malate exudation in both ET8 and ES8 plants. These novel findings have important implications for our understanding how plants respond to elevated [CO2] grown in unfavorable edaphic conditions in general and in acid soils in particular.
Spatial scales of genetic structure and gene flow in Calochortus albus (Liliaceae)
Authors: Henss Jillian M. , Moeller Jackson R. , Theim Terra J. , Givnish Thomas J.
Published: April 2013

Calochortus (Liliaceae) displays high species richness, restriction of many individual taxa to narrow ranges, geographic coherence of individual clades, and parallel adaptive radiations in different regions. Here we test the first part of a hypothesis that all of these patterns may reflect gene flow at small geographic scales. We use amplified fragment length polymorphism variation to quantify the geographic scales of spatial genetic structure and apparent gene flow in Calochortus albus, a widespread member of the genus, at Henry Coe State Park in the Coast Ranges south of San Francisco Bay. Analyses of 254 mapped individuals spaced 0.001–14.4 km apart show a highly significant decline in genetic identity with ln distance, implying a root‐mean‐square distance of gene flow σ of 5–43 m. STRUCTURE analysis implies the existence of 2–4 clusters over the study area, with frequent reversals among clusters over short distances (<200 m) and a relatively high frequency of admixture within individuals at most sampling sites. While the intensity of spatial genetic structure in C. albus is weak, as measured by the Sp statistic, that appears to reflect low genetic identity of adjacent plants, which might reflect repeated colonizations at small spatial scales or density‐dependent mortality of individual genotypes by natural enemies. Small spatial scales of gene flow and spatial genetic structure should permit, under a variety of conditions, genetic differentiation within species at such scales, setting the stage ultimately for speciation and adaptive radiation as such scales as well.
Homogeneous metal complex catalyzed conjugation of methyl linoleate
Authors: Behr Arno , Witte Henning , Bayrak Zeynep
Published: April 2013

Conjugated methyl linoleates (CML) can be produced by homogeneous transition metal catalysis under mild reaction conditions, low catalyst concentrations and short reaction times in nearly quantitative yield from methyl linoleate (ML), an easily accessible intermediate product of the oleochemical industry. The best catalyst proved to be the Wilkinson‐catalyst RhCl(PPh3)3 (1 mol%) activated by the co‐catalyst tin(II)chloride‐dihydrate (2.5 mol%) in the solvent methanol. A yield of 93% of conjugated methyl linoleates can be obtained under mild reaction conditions at 60°C and low reaction times of 3 h.

See commentary by Philippaerts et al. [p. 717–720], http://dx.doi.org/10.1002/ejlt.201300101
Halogenated Benzene Cation Radicals
Authors: Molski Matthias J. , Khanfar Monther A. , Shorafa Hashem , Seppelt Konrad
Published: April 2013

The benzene cation radicals [C6F5‐CF3]+, [1,4‐C6F4(CF3)2]+, [1,2,4,5‐C6H2Cl4]+, [C6F5‐C6F5]+, and [C6Br6]+ have been obtained as salts with fluoroarsenic and fluoroantimony counterions. Their structures have been obtained by single‐crystal structure determinations, and supported by ESR measurements and DFT calculations. [C6F5‐CF3]+, [1,4‐C6F4(CF3)2]+, and [1,2,4,5‐C6H2Cl4]+ have the predicted bisallyl type structure. [C6F5‐C6F5]+ can be described as having a quinoid form with a strengthened central C–C bond and a smaller dihedral angle as compared to the neutral C6F5‐C6F5. [C6Br6]+ is the missing link between [C6F6]+, [C6Cl6]+, and [C6I6]+. It has a Jahn–Teller distortion, though weaker than [C6F6]+ and [C6Cl6]+, in contrast to [C6I6]+, which remains in a regular hexagon structure.
Anion‐π Interaction: An Influential Force in Solid State Molecular Microstructures
Authors: Giese Michael , Albrecht Markus , Valkonen Arto , Rissanen Kari
Published: April 2013

The crystal structures of simple triphenyl(pentafluorobenzyl)phosphonium salts provide crucial data on the influence of anion size on the molecular structure of bis(pentafluorobenzyl)phosphonium cations containing two adjacent electron‐deficient moieties. Whereas the bromide anions interact by anion‐π interaction in a 1:1 mode with the pentafluorobenzene unit Z‐configured, the bulkier anions iodide, tetrafluoroborate, and hexafluorophosphate result in a 1:2 tweezer‐like anti‐configuration in which one anion interacts simultaneously with two pentafluorobenzene units. When spatial separation of the two electron‐deficient rings match the size of the anion, anion‐π interactions induce a conformational change from the anti‐form observed for the smaller anion to the tweezer‐like syn‐form.
Tuning the Halide Affinity of Quinoline‐Based Anion Receptors
Authors: Sun Zhan‐Hu , Albrecht Markus , Fröhlich Roland
Published: April 2013

The binding behaviour of (thio)urea‐ and amide‐functionalized quinoline‐based anion receptors towards halide anions was investigated in detail in CDCl3 and [D6]DMSO solutions by using 1H and 19F NMR spectroscopic methods. The electronic, solvent, and fluoro‐substitution effects were studied. The (thio)urea‐ and amide‐functionalized quinoline‐based anion receptors showed medium to strong anion affinity and good selectivity in solution. Single crystals of key compounds were obtained and studied by X‐ray diffraction spectroscopy.
Peptoid‐Based Rare‐Earth (Group 3 and Lanthanide) Transporters
Authors: Kölmel Dominik K. , Rudat Birgit , Schepers Ute , Bräse Stefan
Published: April 2013

Group 3 and lanthanide metals have been complexed by peptoid transporters [polycationic oligo(N‐substituted glycines)]. To achieve this, the rare‐earth‐complexing DTPA ligand was coupled with the peptoids, and afterwards lanthanide salts were added. The photopysical and biological properties of these complexes were investigated.
Photochromism of Diarylethene‐Functionalized 7‐Deazaguanosines
Authors: Singer Marco , Nierth Alexander , Jäschke Andres
Published: April 2013

In a prior report we introduced a novel class of photochromic nucleosides (PCNs) that combine the structural features of adenine with the photochromic properties of diarylethenes. Herein, we translated this concept to the nucleoside guanosine, generating reversibly switching guanosine‐like PCNs. These switches consist of a 7‐deazaguanosine unit and a second aryl functionality, which are linked through a cyclopentene unit. Irradiation of the open‐form isomer with light at 300 nm induces a pericyclic reaction that can be reversed with visible light. In addition to optical stimulation, these switches respond to light‐independent stimuli, such as the presence of acid or complexation with metal ions.
Methane production from anaerobic co‐digestion of maize and cow dung
Authors: Abdoli Mohammad Ali , Amiri Leila , Baghvand Akbar , Nasiri Javad , Madadian Edris
Published: April 2013

Anaerobic digestion (AD) treatment of agricultural and animal waste can be considered as a means of enabling environmental remediation. This research investigated two conditions of anaerobic co‐digestion of maize waste and cow dung. This was done by placing a mixture of cow dung and maize waste together in a floating drum digester that was run at two different cow dung/maize ratios of 10:1 and 10:5. Batch conditions were on a bench‐scale of AD, 5 L in volume, developed to operate under mesophilic (36 ± 1°C).

Results showed that biogas and methane yields from mesophilic digestion at the ratio of 10:1 were lower than yields obtained at ratio tested in the second run (10:5). Biogas yields were 250 and 480 L/kg VS for first and second runs, respectively. In the case of methane, these amounts were presented at 130 and 300 L/kg VS. Furthermore, the average methane content of biogas was calculated as 51 and 62%, in first and second runs respectively. The total biogas production of the reactor increased by 92% when substrates were fed in second condition ratio compared to biogas production during the first condition ratio. In continue the effect of adding maize waste on biogas yield from cow dung was evaluated in batch digesters under mesophilic conditions. The addition of maize waste to cow dung presents a viable method to improve biogas yield, as well as a means to use maize waste. © 2013 American Institute of Chemical Engineers Environ Prog, 33: 597–601, 2014
Numerical simulation of the impact of sediment supply and streamflow variations on channel grain sizes and Chinook salmon habitat in mountain drainage networks
Authors: Neupane Sagar , Yager Elowyn M.
Published: April 2013

Climatically driven changes in streamflow and hillslope sediment supply could potentially alter stream surface grain size distribution patterns and thereby impact habitat for a number of threatened and endangered in‐stream fish species. Relatively little is known about hydrograph (shape, peak flow) influence or the relative importance of chronic and episodic hillslope inputs on channel conditions. To better understand these external drivers, we calculated sediment routing through a gravel‐bedded river network using a one‐dimensional (1D) bedload transport model. We calculated changes in grain sizes and estimated Chinook salmon habitat suitability caused by a dry year and an extreme flood hydrograph, and chronic (diffusive, overland flow) or pulse (landslide, debris flow) hillslope sediment supplies. To obtain accurate channel conditions, a relatively high reference Shields stress, representative of steep mountain streams, was needed. An extreme event flood without any hillslope sediment inputs caused widespread bed coarsening and a decrease in aquatic habitat. Chronic sediment input combined with this hydrograph eliminated any changes in grain size and habitat, although when combined with a dry year flow, caused systematic bed fining. The influence of a given hydrograph therefore highly depends on the hillslope sediment supply. Regardless of the flow hydrograph or sediment pulse timing, grain size distribution or location, pulse sediment inputs did not cause widespread grain size changes despite being 100 times the total chronic input volume. Widespread and continuous hillslope sediment inputs may influence channel grain sizes and aquatic habitat more than a single discrete sediment pulse. Depending on the magnitudes of flow hydrograph and sediment supply alterations, climate change may induce no differences in grain sizes or very dramatic changes with significant consequences for long‐term sustainability. Copyright © 2013 John Wiley & Sons, Ltd.
Expiration‐Day Effects of Stock and Index Futures and Options in Sweden: The Return of the Witches
Authors: Xu Caihong
Published: April 2013

Recently, the NASDAQ‐OMX Nordic Exchange announced a change of expiration day for the OMXS 30 index futures and options. The OMXS 30 index derivatives used to expire on the fourth Friday of the expiry month while derivatives on individual stocks expired on the third Friday. After the change, derivatives on both the index and individual stocks expire on the third Friday of the expiry month making the third Friday the “quadruple witching Friday” as stock futures, stock options, index futures, and index options expire simultaneously. This contractual change provides a unique opportunity to investigate its impact on expiration‐day effects. The results show that there is hardly any expiration‐day effect due to the derivatives' expirations before or after the contractual change, except the abnormally higher trading volumes at the stock derivatives' expirations before the change, and on the quadruple witching Fridays after the change. Most importantly, there is no significantly intensified abnormal volume, volatility, or price distortion effect due to the seemingly “extraordinary” change in the OMXS 30 index derivatives, despite the quadruple witching expirations after the change. © 2013 Wiley Periodicals, Inc. Jrl Fut Mark 34:868–882, 2014
Turbidite record of frequency and source of large volume (>100 km3) Canary Island landslides in the last 1.5 Ma: Implications for landslide triggers and geohazards
Authors: Hunt J. E. , Wynn R. B. , Talling P. J. , Masson D. G.
Published: April 2013

During the last two decades, numerous studies have focused on resolving the landslide histories of the Canary Islands. Issues surrounding the preservation and dating of onshore and proximal submarine landslide deposits precludes accurate determination of event ages. However, submarine landslides often disaggregate and generate sediment gravity flows. Volcaniclastic turbidites sampled from Madeira Abyssal Plain piston cores represent a record of eight large‐volume failures from the Western Canary Islands in the last 1.5 Ma. During this time, there is a mean recurrence rate of 200 ka, while the islands of El Hierro and Tenerife have individual landslide recurrences of 500 ka and 330 ka, respectively. Deposits from the 15 ka El Golfo landslide from El Hierro and 165 ka Icod landslide from Tenerife are examined. This study also identifies potential deposits associated with the Orotava (535 ka), Güímar (850 ka), and Rogues de García landslides (1.2 Ma) from Tenerife, El Julan (540 ka), and El Tiñor (1.05 Ma) landslides from El Hierro, and the Cumbre Nueva landslide (485 ka) from La Palma. Seven of eight landslides occurred during major deglaciations or subsequent interglacial periods, which represent 55% of the time. However, all of the studied landslides occur during or at the end of periods of protracted island volcanism, which generally represent 60% of the island histories. Although climate may precondition failures, it is suggested that volcanism presents a more viable preconditioning and trigger mechanism for Canary Island landslides.
A rootless rockies—Support and lithospheric structure of the Colorado Rocky Mountains inferred from CREST and TA seismic data
Authors: Hansen Steven M. , Dueker Ken G. , Stachnik Josh C. , Aster Richard C. , Karlstrom Karl E.
Published: April 2013

Support for the Colorado high topography is resolved using seismic data from the Colorado Rocky Mountain (CRM) Experiment and Seismic Transects. The average crustal thickness, derived from P wave receiver function imaging, is 48 km. However, a negative correlation between Moho depth and elevation is observed, which negates Airy‐Heiskanen isostasy. Shallow Moho (<45 km depth) is found beneath some of the highest elevations, and therefore, the CRM are rootless. Deep Moho (45–51 km) regions indicate structure inherited from the Proterozoic assembly of the continent. Shear wave velocities from surface wave tomography are mapped to density employing empirical velocity‐to‐density relations in the crust and mantle temperature modeling. Predicted elastic plate flexure and gravity fields derived from the density model agree with observed long‐wavelength topography and Bouguer gravity. Therefore, low‐density crust and mantle are sufficient to support much of the CRM topography. Centers of Oligocene volcanism, e.g., the San Juan Mountains, display reduced crustal thicknesses and lowest average crustal velocities, suggesting that magmatic modification strongly influenced modern lithospheric structure and topography. Mantle velocities span 4.02–4.64 km/s at 73–123 km depth, and peak lateral temperature variations of 600°C are inferred. S wave receiver function imaging suggests that the lithosphere‐asthenosphere boundary is 100–150 km deep beneath the Colorado Plateau, and 150–200 km deep beneath the High Plains. A region of negative arrivals beneath the CRM above 100 km depth correlates with low mantle velocities and is interpreted as thermally modified/metasomatized lithosphere resulting from Cenozoic volcanism.
Semidiurnal perturbations to the surge of Hurricane Sandy
Authors: Valle‐Levinson Arnoldo , Olabarrieta Maitane , Valle Alvaro
Published: April 2013

Hurricane Sandy drove storm surges throughout the eastern seaboard of the United States, from Miami to Maine, at the end of October 2012. The surge was particularly high (>3 m) in coastal New York. In the southeastern United States, the surge was <1 m but had striking semidiurnal perturbations that reached a range of ~0.5 m in northern Florida and southern Georgia. These oscillations are typically not considered in surge forecasts and their origin needs to be understood for future forecasts. Analytical and numerical approaches indicated that semidiurnal perturbations arose from an interaction between astronomical tide and wind forcing. This combination of forcing caused phase shifts between incident and reflected tidal waves that customarily produce quasi‐standing tidal conditions in the area. Atmospheric forcing of sufficient strength, which threshold remains to be established, disrupted such quasi‐standing tidal behavior through Coriolis accelerations and triggered the semidiurnal perturbations.
Seismic evidence for high pore pressures in the oceanic crust: Implications for fluid‐related embrittlement
Authors: Shiina Takahiro , Nakajima Junichi , Matsuzawa Toru
Published: April 2013

We estimated the P wave velocity structure of the crust of the subducting Pacific plate beneath northeast Japan using arrival time data of P‐to‐S‐converted waves. The results show that the P wave velocity of the subducting crust varies along the arc and increases abruptly at a depth of ~100 km, from 6.5–7.0 km/s in the fore arc to 7.5–8.5 km/s in the back arc. The P wave velocity in the fore arc is ~10% lower than theoretically expected values for the metamorphosed mid‐ocean ridge basalt material. Seismicity in the subducting crust is most active at depths of 70–80 km where P wave velocities are lowest. The marked reduction of P wave velocity suggests the coexistence of aqueous fluids with hydrous minerals. Abundant fluids elevate pore fluid pressures and reduce effective normal stress, promoting intensive seismic activity in the low‐velocity crust. Our observations provide seismic evidence that earthquakes in the subducting crust are facilitated by fluid‐related embrittlement.
An inter‐basin backwater overflow (the Buhai Brook and the Ezer reservoir on the Jijia River, Romania)
Authors: Romanescu Gheorghe , Stoleriu Cristian
Published: April 2013

During the last few years, the north‐western part of Romania has been affected by catastrophic floods with most of the watercourses reaching their highest recorded discharges. This study reports the generation of a numerical terrain model and the simulation of a backwater phenomenon at elevation steps according to the volume of water accumulated at the confluence of the Buhai Brook with the Jijia River. The hydrological data are complemented by rainfall data and the careful recording of the flood behaviour during the entire period of its development. The main aim of the study is to identify the causes of the backwater phenomenon and to highlight the material damage inflicted on the town of Dorohoi. At the same time, the study uses cartographic model that was developed to establish which areas are at risk of flooding at various levels of probability. The catastrophic flood began on the Buhai Brook, a slow‐flowing stream that drains the areas to the west of the town of Dorohoi and discharged into the upstream sector of the Jijia confluence. The flood caused two types of backwater waves: one behind the bridges and the houses built on the floodplain and a second that followed the course of the main stem (Jijia) upstream from the confluence, flooding the Ezer Lake, which was created specifically to attenuate such floods. The spillway backwater phenomenon was inter‐basin as it did not occur in a single hydrographic basin. The causes of the catastrophic flash flood and of the inter‐basin backwater overflow are natural but also reflect anthropogenic influence. After the lake filled, the discharge into the Jijia was controlled and the flooding downstream was thus greatly diminished. Though fortuitous, the backwater flooding was important in mitigating the impact of the flood wave from the Jijia River. Copyright © 2013 John Wiley & Sons, Ltd.
Environmentally sustainable management of water demands under changing climate conditions in the Upper Ganges Basin, India
Authors: Sapkota Pratibha , Bharati Luna , Gurung Pabitra , Kaushal Nitin , Smakhtin Vladimir
Published: April 2013

Allocation of water to cities, industries and agriculture has been a common practice in river basin planning and management. It is widely accepted that water also needs to be allocated for the aquatic environment, i.e. alongside the demands of other users. This paper describes the application of a basin planning model (Water Evaluation and Planning Model) to assess present and alternative water management options, which include incorporation of environmental flows (EFs) in the Upper Ganges River, India. Furthermore, the impacts of projected climate changes are also considered. The paper also briefly summarizes the EF assessment methodology, which was conducted through a multidisciplinary, multi‐stakeholder approach (Building Blocks methodology). This is the first time that a comprehensive EF assessment has been done in India. Results from this study show that annual water demands for the domestic, industrial and irrigation water use are 1375, 1029 and 6680 MCM, respectively. Unmet demands, i.e. when there is not enough water to fulfil the required demands, were a problem during December and January for the past climate and during December, January and February under climate change‐projected conditions. Adding EFs increased unmet demands in the same winter months. During March–November, unmet water demands were less than 5 MCM even with the addition of EFs. Reducing crop type to less water intense crops was more effective in reducing unmet demands than decreasing the cropped area. Improving irrigation systems through improved efficiency and water saving technologies as well as conjunctive use of surface and ground water is also viable options. However, the most effective water management solution is from managing upstream storage structures such as the Tehri dam for increased dry season flows. Dry season releases from Tehri dam can be used to reduce the downstream unmet demands, which include EFs to less than 5 MCM/month. Copyright © 2013 John Wiley & Sons, Ltd.
The effect of PTH(1-34) on fracture healing during different loading conditions
Authors: Ellegaard Maria , Kringelbach Tina , Syberg Susanne , Petersen Solveig , Beck Jensen Jens-Erik , Brüel Annemarie , Jørgensen Niklas Rye , Schwarz Peter
Published: April 2013

Parathyroid hormone (PTH) and PTH(1-34) have been shown to promote bone healing in several animal studies. It is known that the mechanical environment is important in fracture healing. Furthermore, PTH and mechanical loading has been suggested to have synergistic effects on intact bone. The aim of the present study was to investigate whether the effect of PTH(1-34) on fracture healing in rats was influenced by reduced mechanical loading. For this purpose, we used female, 25-week-old ovariectomized rats. Animals were subjected to closed midshaft fracture of the right tibia 10 weeks after ovariectomy. Five days before fracture, half of the animals received Botulinum Toxin A injections in the muscles of the fractured leg to induce muscle paralysis (unloaded group), whereas the other half received saline injections (control group). For the following 8 weeks, half of the animals in each group received injections of hPTH(1-34) (20 µg/kg/day) and the other half received vehicle treatment. Fracture healing was assessed by radiology, dual-energy X-ray absorptiometry (DXA), histology, and bone strength analysis. We found that unloading reduced callus area significantly, whereas no effects of PTH(1-34) on callus area were seen in neither normally nor unloaded animals. PTH(1-34) increased callus bone mineral density (BMD) and bone mineral content (BMC) significantly, whereas unloading decreased callus BMD and BMC significantly. PTH(1-34) treatment increased bone volume of the callus in both unloaded and control animals. PTH(1-34) treatment increased ultimate force of the fracture by 63% in both control and unloaded animals and no interaction of the two interventions could be detected. PTH(1-34) was able to stimulate bone formation in normally loaded as well as unloaded intact bone. In conclusion, the study confirms the stimulatory effect of PTH(1-34) on fracture healing, and our data suggest that PTH(1-34) is able to promote fracture healing, as well as intact bone formation during conditions of reduced mechanical loading. © 2013 American Society for Bone and Mineral Research.
A Cheap and Efficient Methodology for the Solvent‐Free, One‐pot and Multi‐component Synthesis of 3,4‐Dihydropyrimidin‐2(1H)‐ones Catalyzed by Mesoporous NH4H2PO4/MCM‐48 and Comparison of Its Catalytic Efficacy with NH4H2PO4/MCM‐41
Authors: Tayebee Reza , Abdollahi Nasrin , Ghadamgahi Malihe
Published: April 2013

The catalytic efficiency of ammonium dihydrogenphosphate was evaluated in the two heterogeneous forms of NH4H2PO4/MCM‐48 and NH4H2PO4/MCM‐41, as mesoporous catalysts, in the solvent free synthesis of 3,4‐dihydropyrimidin‐2(1H)‐ones through one‐pot three‐component condensation of ethyl acetoacetate, an aryl aldehyde and urea. Different reaction parameters including catalytic efficacy, solvent effect, and urea concentration are considered.
Highly Thermal‐Stable Supramolecular Assembly of a Hydrogen‐Bonded Mononuclear Nickel(II) Histidine Compound
Authors: Ke Szu‐Yu , Wang Chih‐Chieh , Lee Gene‐Hsiang , Chuang Yu‐Chun , Lu Kuang‐Lieh
Published: April 2013

A chiral nickel histidine compound, [Ni(L‐his)2]×H2O (1, L‐his = anion of L‐histidine), was synthesized in high yield from the reaction of Ni(OAc)2×4H2O and L‐histidine in the presence of 4,4′‐bipyridine under mild reaction conditions. A single‐crystal X‐ray diffraction analysis showed that compound 1 crystallizes in the monoclinic system, space group C2, with a chemical formula of C12H18N6NiO5, cell parameters: a = 29.416(2) Å, b = 8.2667(7) Å, c = 6.3137(5) Å, β = 90.066(2)°, V = 1535.3(2) Å3 and Z = 4. Each nickel(II) ion in 1 is six coordinated, bonded to two oxygen donors and four nitrogen donors from two crystallographically independent L‐his− ligands with a tridentate coordination mode to form a monomeric species. Monomeric forms of 1 undergo self‐assembly to form a three‐dimensional (3D) supramolecular architecture via subtle combinations of N‐H···O type hydrogen bonding interactions among the adjacent L‐his−ligands and π‐π stacking interactions among the imidazole rings of the L‐his− ligands. The supramolecular entity exhibits an unusually high thermal stability, at temperatures of up to 360 °C and shows reversible de‐/re‐hydration properties.
Ruthenium Complexes with an Anthyridine‐based Ligand. Synthesis, Characterization and Catalytic Activity
Authors: Lo Ying‐Hao , Liu Yi‐Hung , Peng Shie‐Ming , Liu Shiuh‐Tzung
Published: April 2013

Complexation of 2,7‐bis(2‐pyridinyl)‐9‐phenylanthyridine (4) with [RuCl2(CO)3(THF)] and [(η6‐p‐cymene)RuCl2]2 provided the mono‐nuclear complex [(4)Ru(CO)3Cl][RuCl3(CO)3] (5) and the dinuclear complex [(4)Ru2(p‐cymene)2Cl2] (6), respectively. Both complexes have been characterized by spectroscopic, elemental and crystallographic analyses. Complex 6 is an efficient catalyst for the oxidative cyanation of various tertiary arylamines.
Hydrogen production from meat processing and restaurant waste derived crude glycerol by anaerobic fermentation and utilization of the spent broth
Authors: Sarma Saurabh Jyoti , Brar Satinder Kaur , Le Bihan Yann , Buelna Gerardo , Soccol Carlos Ricardo
Published: April 2013

BACKGROUND

Crude glycerol (CG), the major by‐product of the biodiesel production process, could be used for biohydrogen production. However, fermentative hydrogen production is limited by the cost of buffer and additional nutrients required for the process. Thus, the purpose of the present study was to determine maximum H2 production potential of CG in the absence of any additional expensive supplement. Another objective was sustainable utilization of the waste from the H2 production process.

RESULTS

A maximum production of 2022.5 mL H2 L−1 media was achieved by CG bioconversion (without any additional nutrient) and 10 g L−1 CG was found to be optimum. Further, the addition of spent biomass (50 mg L−1) from the process into a subsequent process was found to improve production by 32.5% with a maximum rate of 1040 mL L−1 day−1. Similarly, nearly 75% of total H2 was produced at a pH as low as 3.8, indicating high acid tolerance of the strain (Enterobacter aerogenes NRRL B407) used.

CONCLUSION

Meat processing and restaurant waste based CG has been characterized and evaluated for maximum H2 production potential. Utilization of spent biomass from the CG bioconversion process (as supplement) was found to improve process performance. © 2013 Society of Chemical Industry
Prevalence and clinical relevance of extracardiac findings at cardiac MRI
Authors: Sohns Jan Martin , Schwarz Alexander , Menke Jan , Staab Wieland , Spiro Judith Eva , Lotz Joachim , Unterberg‐Buchwald Christina
Published: April 2013

Purpose

To assess the incidence of extracardiac findings in patients undergoing clinical cardiac magnetic resonance imaging (CMRI) of the heart, and to determine the influence of those findings on patient management.

Materials and Methods

During 40 months, 854 CMRI were performed at 1.5 T. Extracardiac findings were classified as significant (group A), if recommended for additional diagnostics or therapeutic interventions, and as nonsignificant (group B).

Results

The most frequent indication for CMRI was evaluation of cardiac stress ischemia. In all, 631 CMRI (74% of 854) showed no extracardiac pathologies. In the remaining 223 CMRI (26% of 854), a total of 286 extracardiac findings were detected. Among these findings, 49 were considered significant (group A) and 237 nonsignificant (group B). In group A, the most common findings were suspicious pulmonary nodules or masses. In group B, the most frequent findings were hepatic cysts or hemangiomas. Eight malignancies were observed with certainty at CMRI. Seven of them had been incidentally diagnosed on CMRI for the first time, and subsequently changed the patients' management.

Conclusion

Extracardiac findings in clinically indicated CMRI are common (about 26%). Radiologists and cardiologists should be aware of relevant extracardiac findings that might require additional diagnostics or treatment. J. Magn. Reson. Imaging 2014;39:68–76. © 2013 Wiley Periodicals, Inc.
Potential relationship between BK virus and renal cell carcinoma
Authors: Bulut Yasemin , Ozdemir Enver , Ozercan Halil Ibrahim , Etem Ebru Onalan , Aker Fugen , Toraman Zulal Asci , Seyrek Adnan , Firdolas Fatih
Published: April 2013

The objective of the present study was to investigate the potential association between the presence of BK virus (BKV) DNA and mRNA and renal cell carcinoma and bladder transitional cell carcinoma. The formalin‐fixed and paraffin‐embedded tissue samples were obtained from 50 cancer patients with renal cell carcinoma, 40 cancer patients with bladder transitional cell carcinoma, 45 control patients with the benign renal pathology, and from another 25 control patients with benign bladder pathology. The samples were subjected to nested PCR for detection of BKV DNA and real‐time reverse transcription PCR (real‐time RT‐PCR) for determining mRNA levels of BKV. The results of the nested PCR indicated that 23 (14.3%) of 160 samples were positive for BKV DNA. The relationship between the cancer and the presence of BKV DNA was significant (P < 0.05). The BKV DNA positivity was significantly associated with the histological diagnosis of renal cell carcinoma (P = 0.03), but not with that of bladder transitional cell carcinoma. The results of real‐time RT‐PCR showed that the mRNA of BKV VP1 was present in 69.5% of the BKV DNA positive samples. The levels of BKV mRNA were significantly higher in the renal cell cancer samples than in the control samples (P < 0.05). The results of the present study confirm the association between BKV and renal cell cancer. The findings also indicated that the presence of BKV DNA resulted in a fivefold increase in the risk of development of renal cell carcinoma. J. Med. Virol. 85: 1085–1089, 2013. © 2013 Wiley Periodicals, Inc.
In search of influence of stratospheric Quasi‐Biennial Oscillation on tropical cyclones tracks over the Bay of Bengal region
Authors: Fadnavis S. , Ernest Raj P. , Buchunde Pallavi , Goswami B. N.
Published: April 2013

The ability of the stratospheric Quasi‐Biennial Oscillation (QBO) to modulate tropospheric circulation allows it to modulate tracks of tropical cyclones (TCs). This possibility is examined using data on the cyclone tracks over the Bay of Bengal (BOB) during the period 1948–2010. TC tracks (excluding the El Niño‐Southern Oscillation years) when stratified as per the phases of QBO show the evidence of influence of stratospheric QBO on tracks. In pre‐monsoon and post‐monsoon seasons, during easterly phase of QBO, cyclones move westward/northwestward while during westerly phase they move northward/northeastward. The evidence of influence of QBO on modulation of TC tracks is reported for the first time during pre‐satellite period (1948–1978) and satellite period (1979–2010) over the BOB. The QBO influence is observed to be significantly stronger during easterly phase as compared to that in the westerly phase. Numbers of cyclones are more during easterly phase (during pre‐monsoon and post‐monsoon) than during the westerly phase. A mechanism is proposed whereby QBO of the zonal winds in the stratosphere influences the movement of cyclone tracks in the BOB by redistributing deep convection associated with cyclones by modulating steering winds. The possible interaction between QBO and cyclone activity is investigated through the variation of tropopause height, geo‐potential height and Outgoing Longwave Radiations. © 2013 Royal Meteorological Society
Long-term follow-up of endoscopic therapy for stenosis of the biliobiliary anastomosis associated with orthotopic liver transplantation
Authors: Albert Jörg G. , Filmann Natalie , Elsner Julia , Moench Christian , Trojan Jörg , Bojunga Jörg , Sarrazin Christoph , Friedrich-Rust Mireen , Herrmann Eva , Bechstein Wolf Otto , Zeuzem Stefan , Hofmann Wolf Peter
Published: April 2013

Endoscopic treatment for stenosis of an anastomotic biliary stricture (ABS) after orthotopic liver transplantation (OLT) has been proven to be effective and safe, but the long-term outcomes and the risk factors for recurrence are unknown. All 374 patients who underwent OLT at Frankfurt University Hospital were screened for the occurrence of ABSs. ABSs were treated via the endoscopic insertion of a plastic endoprosthesis (29.8%), balloon dilation (12.8%), or a combination of the two (57.4%). The mean follow-up time was 151 weeks, and the mean survival time was 3.4 years. ABSs were observed in 47 patients (12.6%). The mean time from OLT to an ABS was 16.25 months (median = 3.25 months). The cumulative incidence rates for ABSs were 0.09 after 12 months, 0.10/24 m. and 0.11/36 m. In 12 cases (25.5%), ABSs were observed more than 12 months after OLT. ABSs recurred in 16 of the 47 patients (34%). The occurrence of an ABS 6 weeks or more after OLT was a significant predictor of ABS recurrence [P = 0.04, hazard ratio (HR) = 0.235]. There was a trend of hepatitis C virus (HCV) infections being predominant in patients experiencing ABS recurrence (30% for HCV etiology versus 4% for non-HCV etiology) in comparison with patients not experiencing recurrence (36% for HCV etiology versus 30% for non-HCV etiology, P > 0.05). The severity of the initial stricture predicted ABS recurrence (P = 0.046, HR = 2.78), but it did not influence overall survival. The long-term resolution of ABSs was observed in 45 of the 47 patients (95.7%), and ABS recurrence was treated with another attempt (n = 16 or 34%) or 2 more attempts (n = 1) at endoscopic treatment. In conclusion, the long-term success of the endoscopic treatment of ABSs is highly probable if recurrent strictures are again treated endoscopically. ABSs might occur late (>36 months) after OLT, and lifelong follow-up is essential for identifying OLT patients with ABSs. Liver Transpl 19:586–593, 2013. © 2013 AASLD.
Echocardiography for the detection of portopulmonary hypertension in liver transplant candidates: An analysis of cutoff values
Authors: Raevens Sarah , Colle Isabelle , Reyntjens Koen , Geerts Anja , Berrevoet Frederik , Rogiers Xavier , Troisi Roberto I. , Van Vlierberghe Hans , De Pauw Michel
Published: April 2013

Portopulmonary hypertension (POPH), a complication of chronic liver disease, may be a contraindication to liver transplantation (LT) because of the elevated risk of peritransplant and posttransplant morbidity and mortality. Because POPH is frequently asymptomatic, screening with echocardiography is recommended. The only reliable technique, however, for diagnosing POPH is right heart catheterization (RHC). The aims of this study were to evaluate the current estimated systolic pulmonary artery pressure (sPAP) cutoff value of 30 mm Hg and to determine a better cutoff value. One hundred fifty-two patients underwent pretransplant echocardiography between January 2005 and December 2010. These echocardiographic results were compared with pulmonary artery pressures measured during the pretransplant workup or at the beginning of the transplantation procedure (both by catheterization). With a cutoff value of 30 mm Hg, 74 of the 152 patients met the criteria for POPH on echocardiography, although the diagnosis was confirmed in only 7 patients during catheterization; this resulted in a specificity of 54%. It would have been more accurate to use a cutoff value of 38 mm Hg, which had a maximal specificity of 82% and, at the same time, guaranteed a sensitivity and negative predictive value of 100%. With the incorporation of the presence or absence of right ventricular dilatation, the specificity even increased to 93% for this new cutoff value. In conclusion, the prevalence of POPH was 4.6% among LT candidates in this study. We can recommend that LT candidates with an sPAP > 38 mm Hg should be referred for RHC. With the cutoff value increased from 30 to 38 mm Hg, the number of patients undergoing invasive RHC during their evaluation could be safely reduced. Liver Transpl 19:602–610, 2013. © 2013 AASLD.
Morphology, Dielectric and Thermal Properties of Poly(sulfobutylbetaine)/Montmorillonite (PMBS‐4/MMT) Nanocomposites as Solid Polymer Electrolytes
Authors: Cardoso Judith , Vázquez Gerardo , García Pedro R. , González Ignacio
Published: April 2013

Polymeric electrolyte composites based on polymer poly(sulfobutylbetaines) (PMBS‐4) and 1%, 3% and 5% montmorillonite (MMT) modified with organic ions, dodecyldimethyl(3‐sulfo‐propyl) ammonium hydroxide (C12SB) were synthesized. The structural modification and electrochemical properties of samples were investigated to understand the effects of organic MMT in a polymer matrix on ionic conductivity. The modification of the clay with organic ions resulted in a larger d‐spacing which makes easier the penetration of PMBS‐4 into the interlayer galleries. The values of Tg obtained from differential scanning calorimetry are 18 °C, 20 °C, 20 °C and 27 °C for PMBS‐4, PMBS‐4/C12SB‐MMT 1%, PMBS‐4/C12SB‐MMT 3% and PMBS‐4/C12SB‐MMT 5% respectively. Since PMBS‐4 and PMBS/C12SB‐MMT were examined in the absence of Li salt, the conductivity of samples was attributed to the motion of dipoles in chains of zwitterionic PMBS‐4. The increase in conductivity with increasing temperature was explained as a local structural relaxation and segmental motion of polymer. The values of σ, at 25 °C, for: PMBS‐4, PMBS‐4/C12SB‐MMT 1%, PMBS‐4/C12SB‐MMT 3% and PMBS‐4/C12SB‐MMT 5% were 6.2 × 10−6 S/cm, 1.2 × 10−6 S/cm, 1.7 × 10−6 S/cm and 9.1 × 10−6 S/cm respectively.
High‐Throughput Method for RAFT Kinetic Investigations and Estimation of Reactivity Ratios in Copolymerization Systems
Authors: Guerrero‐Sanchez Carlos , Harrisson Simon , Keddie Daniel J.
Published: April 2013

A new high‐throughput experimental technique, namely automated parallel freeze‐evacuate‐thaw degassing method, is applied for the facile, rapid and reliable determination of reactivity ratios in copolymerization systems. The approach allowed carrying out a detailed kinetic investigation of the reversible addition‐fragmentation chain transfer (RAFT) copolymerization of methyl acrylate (MA) with vinyl acetate (VAc) monomers in 2‐methyl‐2‐butanol at 60 °C. Thereafter, the reactivity ratios of this copolymerization system were estimated utilizing the obtained kinetic data and a computer program based on the visualization of the sum of residual space method. The obtained reactivity ratios of the system (rMA = 8.2 and rVAc = 0.17) are comparable to values previously reported in the literature, which demonstrates the utility of this approach.
TEMPO Mediated Radical Emulsion Polymerization of Styrene by Stepwise and Semibatch Processes
Authors: González‐Blanco Roberto , Saldívar‐Guerra Enrique , Herrera‐Ordóñez Jorge , Cano‐Valdez Andrés
Published: April 2013

In the present study we carried out nitroxide mediated radical polymerizations (NMRP) of styrene in emulsion using 2,2,6,6‐tetramethylpiperidine‐N‐oxyl (TEMPO) by stepwise and semibatch processes obtaining polystyrene (PS) with a dispersity (Đ) lower than 1.5 and average particle diameter (Dp) between 180 and 520 nm when methanol was used. Otherwise, when the polymerization was carried out in the absence of methanol, a bimodal particle size distribution (PSD) was obtained. This is attributed to the super‐swelling effect, which causes the particles to grow considerably and also to lower the nitroxide efficiency reducing chain formation and thus drastically reducing the particle nucleation. These polymerizations did not require a separate macroinitiator synthesis step, which represents an important simplification for further applications.
Synthesis and Characterization of Ionic Graphene Oxides (GO) for the Generation of New Multilayered Structures and Hybrid GO/Polymer Nanocomposites
Authors: Ledezma Raquel , Arizmendi Layza , Rodríguez J. Alberto , Castañeda Adali , Ziolo Ronald F.
Published: April 2013

The chemical surface modification of graphene and graphene oxide materials is a burgeoning area of investigation. We report the preparation of new ionic forms of graphene oxide by wet chemical modification and metathesis reactions. Graphene oxide (GO) was prepared by a modified Hummers method and functionalized to form cationic and anionic species. The former were prepared via nucleophilic substitution of alkyl amines at the epoxy and hydroxyl groups on the GO while the latter, consisting of sulfonated GO, was prepared via an aryl diazonium salt. The functionalized graphene oxide sheets consist of quaternary ammonium ion substituted GO, GO+, with Cl‐ or I‐ as counter ion and sulfonated GO, GO‐, with H+, Ba2+ or tetraphenylphosphonium (TPP+) ion as counter ions. The addition reaction between GO+ and GO‐ in aqueous solution by metathesis to form a black [GO+][GO‐] precipitate was also investigated. Materials were characterized by XRD, FTIR, Raman, STEM and TEM/HRTEM. Chemically modified graphene and graphene oxides are expected to facilitate further understanding of the chemistry and physics of graphene materials in general and contribute to the formation and further understanding of advanced hybrid graphene and graphene oxide polymer nanocomposites.1,2
The Ring‐Opening Polymerization of ε‐Caprolactone Catalyzed by Molybdenum Trioxide: A Kinetic Approach Study Using NMR and DSC Data
Authors: Reyes‐López Simón Yobanny , Richa Antonio Martinez
Published: April 2013

The bulk ring‐opening polymerization (ROP) of ε‐caprolactone (CL), catalyzed by molybdenum trioxide (α‐MoO3), was investigated under nitrogen atmosphere at 150°C. Effect of monomer/initiator ([CL]0/[I]0, I = MoO3) and monomer/initiator/co‐initiator ([CL]0/[I]0/[CoI]0, CoI = ROH and H2O) ratios on monomer conversion and molecular weight were determined. Bulk polymerization of CL was completed within 20 hours at 150°C for [CL]0/[I]0 = 100. Propagation was first order in CL concentration and initiator at this temperature, being the rate constant of propagation kp equal to 2.27 × 10−4 mol−1 l s−1. Polymerization reaction was accelerated by the addition of small amounts of water and n‐octanol. In the presence of water (up to [CL]0/[H2O]0 = 120), polymerization rate increases and was completed within 6 hours at 150°C; for higher amounts of water (150 to 180), lower conversions are observed. However, control of number‐average molecular weight was only efficient for [CL]0/[H2O]0 = 20 and 30. In the presence of n‐octanol, degradation of polyester occurs at early stages of polymerization. Kinetic data for polymerization (obtained by 1H‐NMR) were fitted to 14 different model reaction functions. It was found that a linear model represents better the conversion versus time plots for bulk polymerization, in agreement with the pseudo living nature of polymerization.