bluuebunny/crossref_metadata_2025 huggingface dataset:
Stereoregular Polymers
Authors: Takeuchi Daisuke
Published: May 2013

Control of structure of polymers is an important issue in polymer synthesis because it affects the properties of polymers. In this article, general aspects of stereoregular polymers, especially of monosubstituted vinyl monomers, including definition, evaluation, and brief mechanism of the formation of stereoregular polymers are presented. The mechanism of stereoselective polymerization (chain‐end control and enantiomorphic site control) is also described.

Recent progress in stereospecific polymerization of propylene, α‐olefins, and styrenes is also summarized. Metallocene catalysts of group 4 metals having
C
2
,
C
s
, or
C
1
‐symmetric structure are utilized for the stereospecific polymerization of propylene. Recently, a number of nonmetallocene complexes of Ti, Zr, Hf, Ni, and Fe were also found to be effective. Stereospecific polymerization of α‐olefins, such as 1‐hexene, is also achieved by the metallocene catalysts as well as nonmetallocene catalysts of Ti, Zr, Hf, and Sc. Half‐titanocene complexes and nonmetallocene titanium complexes, as well as rare earth catalysts, especially Sc, are utilized for the syndiospecific polymerization of styrene. Zirconocene complexes, lanthanocene complexes, and Ti complexes with OSSO ligands promote isospecific polymerization of styrene. Stereospecific living polymerization of those monomers as well as the synthesis of stereoblock copolymers is also mentioned.
Insight into the Cellular Internalization and Cytotoxicity of Graphene Quantum Dots
Authors: Wu Congyu , Wang Chong , Han Ting , Zhou Xuejiao , Guo Shouwu , Zhang Jingyan
Published: May 2013

Graphene quantum dots (GQDs), owing to their unique morphology, ultra‐small lateral sizes, and exceptional properties, hold great promise for many applications, especially in the biomedical field. In this work, the cellular internalization, distribution, and cytotoxicity of the GQDs are explored complementarily using transmission electron microscopy, confocal laser scanning microscopy, UV‐vis, and fluorescence spectroscopies, and flow cytometry with human gastric cancer MGC‐803 and breast cancer MCF‐7 cells. It is demonstrated that the GQDs are internalized primarily through caveolae‐mediated endocytosis. The effects of GQDs on the cell viability, internal cellular reactive oxygen species (ROS) level, mitochondrial membranes potential, and cell cycles show that the cytotoxicity of GQDs is lower than that of the micrometer‐sized graphene oxide (GO). The low cytotoxicity and size consistence render GQDs appropriate for biomedical application.
Using Functional Nanomaterials to Target and Regulate the Tumor Microenvironment: Diagnostic and Therapeutic Applications
Authors: Ji Tianjiao , Zhao Ying , Ding Yanping , Nie Guangjun
Published: May 2013

Malignant tumors remain a major health burden throughout the world and effective therapeutic strategies are urgently needed. Cancer nanotechnology, as an integrated platform, has the potential to dramatically improve cancer diagnosis, imaging, and therapy, while reducing the toxicity associated with the current approaches. Tumor microenvironment is an ensemble performance of various stromal cells and extracellular matrix. The recent progress in understanding the critical roles and the underlying mechanisms of the tumor microenvironment on tumor progression has resulted in emerging diagnostic and therapeutic nanomaterials designed and engineered specifically targeting the microenvironment components. Meanwhile, the bio‐physicochemical differences between tumor and normal tissues have recently been exploited to achieve specific tumor‐targeting for cancer diagnosis and treatment. Here, the major players in the tumor microenvironment and their biochemical properties, which can be utilized for the design of multifunctional nanomaterials with the potential to target and regulate this niche, are summarized. The recent progress in engineering intelligent and versatile nanomaterials for targeting and regulating the tumor microenvironment is emphasized. Although further investigations are required to develop robust methods for more specific tumor‐targeting and well‐controlled nanomaterials, the applications of tumor microenvironment regulation‐based nanotechnology for safer and more effective anticancer nanomedicines have been proven successful and will eventually revolutionize the current landscape of cancer therapy.
Organic Ternary Solar Cells: A Review
Authors: Ameri Tayebeh , Khoram Parisa , Min Jie , Brabec Christoph J.
Published: May 2013

Recently, researchers have paid a great deal of attention to the research and development of organic solar cells, leading to a breakthrough of over 10% power conversion efficiency. Though impressive, further development is required to ensure a bright industrial future for organic photovoltaics. Relatively narrow spectral overlap of organic polymer absorption bands within the solar spectrum is one of the major limitations of organic solar cells. Among different strategies that are in progress to tackle this restriction, the novel concept of ternary organic solar cells is a promising candidate to extend the absorption spectra of large bandgap polymers to the near IR region and to enhance light harvesting in single bulk‐heterojunction solar cells. In this contribution, we review the recent developments in organic ternary solar cell research based on various types of sensitizers. In addition, the aspects of miscibility, morphology complexity, charge transfer dynamics as well as carrier transport in ternary organic composites are addressed.
Triplet Harvesting with 100% Efficiency by Way of Thermally Activated Delayed Fluorescence in Charge Transfer OLED Emitters
Authors: Dias Fernando B. , Bourdakos Konstantinos N. , Jankus Vygintas , Moss Kathryn C. , Kamtekar Kiran T. , Bhalla Vandana , Santos José , Bryce Martin R. , Monkman Andrew P.
Published: May 2013

Organic light‐emitting diodes (OLEDs) have their performance limited by the number of emissive singlet states created upon charge recombination (25%). Recently, a novel strategy has been proposed, based on thermally activated up‐conversion of triplet to singlet states, yielding delayed fluorescence (TADF), which greatly enhances electroluminescence. The energy barrier for this reverse intersystem crossing mechanism is proportional to the exchange energy (ΔEST) between the singlet and triplet states; therefore, materials with intramolecular charge transfer (ICT) states, where it is known that the exchange energy is small, are perfect candidates. However, here it is shown that triplet states can be harvested with 100% efficiency via TADF, even in materials with ΔEST of more than 20 kT (where k is the Boltzmann constant and T is the temperature) at room temperature. The key role played by lone pair electrons in achieving this high efficiency in a series of ICT molecules is elucidated. The results show the complex photophysics of efficient TADF materials and give clear guidelines for designing new emitters.
Effect of Hf Concentration on Thermoelectric Properties of Nanostructured N‐Type Half‐Heusler Materials HfxZr1–xNiSn0.99Sb0.01
Authors: Chen Shuo , Lukas Kevin C. , Liu Weishu , Opeil Cyril P. , Chen Gang , Ren Zhifeng
Published: May 2013

Half‐Heusler n‐type thermoelectric materials MNiSn (M = Hf, Zr) have been shown to exhibit peak thermoelectric dimensionless figure‐of‐merit (ZT) of ∼1.0 at 600–700 °C with a composition of Hf0.75Zr0.25NiSn0.99Sb0.01. This work demonstrates that it is possible to achieve the same ZT by reducing the concentration of the most expensive component Hf to one third of the previously reported best composition, i.e., Hf0.25Zr0.75NiSn0.99Sb0.01, which corresponds to an overall 50% reduction on material cost. The samples are prepared by ball milling the arc melted ingot and hot pressing the finely ground powders. The reduction of Hf concentration is crucial for such materials to be used in large‐scale waste heat recovery.
The generalized bone phenotype in children with neurofibromatosis 1: A sibling matched case–control study
Authors: Armstrong Linlea , Jett Kimberly , Birch Patricia , Kendler David L. , McKay Heather , Tsang Erica , Stevenson David A. , Hanley David A. , Egeli Deetria , Burrows Melonie , Friedman J.M.
Published: May 2013

People with neurofibromatosis 1 (NF1) have low bone mineralization, but the natural history and pathogenesis are poorly understood. We performed a sibling‐matched case–control study of bone mineral status, morphology, and metabolism. Eighteen children with NF1 without focal bony lesions were compared to unaffected siblings and local population controls. Bone mineral content at the lumbar spine and proximal femur (dual energy X‐ray absorptiometry (DXA)) was lower in children with NF1; this difference persisted after adjusting for height and weight. Peripheral quantitative computed tomography (pQCT) of the distal tibia showed that trabecular density was more severely compromised than cortical. Peripheral QCT‐derived estimates of bone strength and resistance to bending and stress were poorer among children with NF1 although there was no difference in fracture frequencies. There were no differences in the size or shape of bones after adjusting for height. Differences in markers of bone turnover between cases and controls were in the directions predicted by animal studies, but did not reach statistical significance. Average serum calcium concentration was higher (although within the normal range) in children with NF1; serum 25‐OH vitamin D, and PTH levels did not differ significantly between cases and controls. Children with NF1 were less mature (assessed by pubertal stage) than unaffected siblings or population controls. Children with NF1 have a generalized difference of bone metabolism that predominantly affects trabecular bone. Effects of decreased neurofibromin on bone turnover, calcium homeostasis, and pubertal development may contribute to the differences in bone mineral content observed among people with NF1. © 2013 Wiley Periodicals, Inc.
Is summer monsoon rainfall over the west coast of India decreasing?
Authors: Prakash Satya , Sathiyamoorthy V. , Mahesh C. , Gairola R. M.
Published: May 2013

In this study, long‐term changes in the summer monsoon rainfall over the west coast of India and adjoining eastern Arabian Sea (WCA) have been examined independently using rain gauge adjusted multisatellite rainfall data available since 1979. Present analysis using the satellite‐based rainfall data agrees with the long‐term rainfall decrease reported in the earlier studies. However, close examination of the data reveals that the rainfall in the recent years (since 2002) has started increasing over the WCA. Hence, it is stressed that a detailed analysis using the satellite‐derived rainfall data of longer period is required to arrive at a firm conclusion.
Determination of salbutamol by direct chiral reversed‐phase HPLC using teicoplanin as stationary phase and its application to natural water analysis
Authors: Rosales‐Conrado Noelia , Dell'Aica Margherita , de León‐González María Eugenia , Pérez‐Arribas Luis Vicente , Polo‐Díez Luis María
Published: May 2013

A direct chiral LC‐UV method was optimized for the determination of salbutamol (SAL) β2‐agonist in environmental water. Two commercially available columns were evaluated: teicoplanin Chirobiotic‐T™ (150 × 2.1 mm i.d., 5 µm) and vancomycin Chirobiotic‐V™ (150 × 2.1 mm i.d., 5 µm). Finally, teicoplanin chiral stationary phase was selected for SAL enantiomer resolution. In order to preserve its integrity and maintain the column performance for longer time, the use of additives such as triethylamine (TEA) in the mobile phase was avoided. Experimental design was applied to simultaneously evaluate the influence of several parameters involved in enantiomer separation and to establish the conditions for acceptable resolution and performance in short analysis time. Optimum mobile phase was methanol–20 mM ammonium acetate buffer at pH 4.5 (98:2, v/v). A solid‐phase extraction procedure for sample pre‐concentration and clean‐up allowed the determination of chiral SAL residues in natural water samples spiked at low concentrations in the range 1.0–20 ng mL−1. Reproducible recoveries, between 77 and 98%, were obtained and matrix effect was negligible. Injection of sample solutions at low elution strength permitted the SAL enantioresolution in the natural water complex matrix with satisfactory sensitivity and precision. Copyright © 2013 John Wiley & Sons, Ltd.
Construct Measurement Quality Improves Predictive Accuracy in Violence Risk Assessment: an Illustration Using the Personality Assessment Inventory
Authors: Hendry Melissa C. , Douglas Kevin S. , Winter Elizabeth A. , Edens John F.
Published: May 2013

Much of the risk assessment literature has focused on the predictive validity of risk assessment tools. However, these tools often comprise a list of risk factors that are themselves complex constructs, and focusing on the quality of measurement of individual risk factors may improve the predictive validity of the tools. The present study illustrates this concern using the Antisocial Features and Aggression scales of the Personality Assessment Inventory (Morey, 1991). In a sample of 1,545 prison inmates and offenders undergoing treatment for substance abuse (85% male), we evaluated (a) the factorial validity of the ANT and AGG scales, (b) the utility of original ANT and AGG scales and newly derived ANT and AGG scales for predicting antisocial outcomes (recidivism and institutional infractions), and (c) whether items with a stronger relationship to the underlying constructs (higher factor loadings) were in turn more strongly related to antisocial outcomes. Confirmatory factor analyses (CFAs) indicated that ANT and AGG items were not structured optimally in these data in terms of correspondence to the subscale structure identified in the PAI manual. Exploratory factor analyses were conducted on a random split‐half of the sample to derive optimized alternative factor structures, and cross‐validated in the second split‐half using CFA. Four‐factor models emerged for both the ANT and AGG scales, and, as predicted, the size of item factor loadings was associated with the strength with which items were associated with institutional infractions and community recidivism. This suggests that the quality by which a construct is measured is associated with its predictive strength. Implications for risk assessment are discussed. Copyright © 2013 John Wiley & Sons, Ltd.
Probing Substrate Promiscuity of Amylosucrase from Neisseria polysaccharea
Authors: Daudé David , Champion Elise , Morel Sandrine , Guieysse David , Remaud‐Siméon Magali , André Isabelle
Published: May 2013

The amylosucrase from Neisseria polysaccharea (NpAS) naturally catalyzes the synthesis of a variety of products from sucrose and shows signs of plasticity of its active site. To explore further this promiscuity, the tolerance of amylosucrase towards different donor and acceptor substrates was investigated. The selection of alternate donor substrates was first made on the basis of preliminary molecular modeling studies. From 11 potential donors harboring selective derivatizations that were experimentally evaluated, only p‐nitrophenyl‐α‐D‐glucopyranoside was used by the wild‐type enzyme, and this underlines the high specificity of the −1 subsite of NpAS for glucosyl donor substrates. The acceptor substrate promiscuity was further explored by screening 20 hydroxylated molecules, including D‐ and L‐monosaccharides as well as polyols. With the exception of one compound, all were successfully glucosylated, and this showcases the tremendous plasticity of the +1 subsite of NpAS, which is responsible for acceptor recognition. The products obtained from the transglucosylation reactions of three selected acceptors were characterized, and they revealed original structures and enzyme enantiopreference, which were more particularly analyzed by in silico docking analyses.
Explicit Roles of Au and TiO2 in a Bifunctional Au/TiO2 Catalyst for the Water‐Gas Shift Reaction: A DFT Study
Authors: Hussain Akhtar , Gracia Jose , Nieuwenhuys Ben E. , Niemantsverdriet J. W. (Hans)
Published: May 2013

The water–gas shift reaction has been investigated by using DFT applied to Au(1 0 0), stepped Au(3 1 0), and TiO2 anatase (0 0 1) surfaces. The results show that neither Au nor TiO2 can catalyze the reaction by themselves. Of CO, CO2, H2O, and H2, only CO adsorbs with moderate adsorption energy at low‐coordinated sites, whereas other molecules interact only weakly with Au. The activation of H2O is impossible on Au surfaces. However, H2O adsorbs dissociatively on the anatase (0 0 1) surface and the diffusion of OH and H is feasible. The energetic data indicate that the rest of the process is possible on the Au surface. Two mechanisms were investigated and compared for the water–gas shift reaction, with H2O dissociation on the TiO2 surface and diffusion of OH and H on Au surfaces in common. The latter is, in principle, the rate‐limiting step. The first mechanism occurs through the disproportionation of two OH groups on Au into H2O and an O atom. The latter reacts with CO. In the alternative mechanism, CO combines with OH to give a COOH intermediate, which subsequently reacts with another OH group to form CO2 and H2O. Finally, H atoms recombine on the Au surface to complete the catalytic cycle.
Calcium‐Based Lewis Acid Catalysts
Authors: Begouin Jeanne‐Marie , Niggemann Meike
Published: May 2013

Recently, Lewis acidic calcium salts bearing weakly coordinating anions such as Ca(NTf2)2, Ca(OTf)2, CaF2 and Ca[OCH(CF3)2]2 have been discovered as catalysts for the transformation of alcohols, olefins and carbonyl compounds. High stability towards air and moisture, selectivity and high reactivity under mild reaction conditions render these catalysts a sustainable and mild alternative to transition metals, rare‐earth metals or strong Brønsted acids.
Aptamer‐Based Turn‐On Detection of Thrombin in Biological Fluids Based on Efficient Phosphorescence Energy Transfer from Mn‐Doped ZnS Quantum Dots to Carbon Nanodots
Authors: Zhang Lu , Cui Peng , Zhang Baocheng , Gao Feng
Published: May 2013

This paper presents the first example of a sensitive, selective, and stable phosphorescent sensor based on phosphorescence energy transfer (PET) for thrombin that functions through thrombin–aptamer recognition events. In this work, an efficient PET donor–acceptor pair using Mn‐doped ZnS quantum dots labeled with thrombin‐binding aptamers (TBA QDs) as donors, and carbon nanodots (CNDs) as acceptors has been constructed. Due to the π–π stacking interaction between aptamer and CNDs, the energy donor and acceptor are taken into close proximity, leading to the phosphorescence quenching of donors, TBA QDs. A maximum phosphorescence quenching efficiency as high as 95.9 % is acquired. With the introduction of thrombin to the “off state” of the TBA‐QDs‐CNDs system, the phosphorescence is “turned on” due to the formation of quadruplex‐thrombin complexes, which releases the energy acceptor CNDs from the energy donors. Based on the restored phosphorescence, an aptamer‐based turn‐on thrombin biosensor has been demonstrated by using the phosphorescence as a signal transduction method. The sensor displays a linear range of 0–40 nM for thrombin, with a detection limit as low as 0.013 nM in pure buffers. The proposed aptasensor has also been used to monitor thrombin in complex biological fluids, including serum and plasma, with satisfactory recovery ranging from 96.8 to 104.3 %. This is the first time that Mn‐doped ZnS quantum dots and CNDs have been employed as a donor–acceptor pair to construct PET‐based biosensors, which combines both the photophysical merits of phosphorescence QDs and the superquenching ability of CNDs and thus affords excellent analytical performance. We believe this proposed method could pave the way to a new design of biosensors using PET systems.
A finite element‐based constrained mixture implementation for arterial growth, remodeling, and adaptation: Theory and numerical verification
Authors: Valentín A. , Humphrey J.D. , Holzapfel G.A.
Published: May 2013

We implemented a constrained mixture model of arterial growth and remodeling in a nonlinear finite element framework to facilitate numerical analyses of diverse cases of arterial adaptation and maladaptation, including disease progression, resulting in complex evolving geometries and compositions. This model enables hypothesis testing by predicting consequences of postulated characteristics of cell and matrix turnover, including evolving quantities and orientations of fibrillar constituents and nonhomogenous degradation of elastin or loss of smooth muscle function. The nonlinear finite element formulation is general within the context of arterial mechanics, but we restricted our present numerical verification to cylindrical geometries to allow comparisons with prior results for two special cases: uniform transmural changes in mass and differential growth and remodeling within a two‐layered cylindrical model of the human aorta. The present finite element model recovers the results of these simplified semi‐inverse analyses with good agreement. Copyright © 2013 John Wiley & Sons, Ltd.
MapReduce delay scheduling with deadline constraint
Authors: Li Hongliang , Wei Xiaohui , Fu Qingwu , Luo Yuan
Published: May 2013

MapReduce programming paradigm has been widely applied to solve large‐scale data‐intensive problems. Intensive studies of MapReduce scheduling have been carried out to improve MapReduce system performance. Delay scheduling is a common way to achieve high data locality and system performance. However, inappropriate delays can lead to low system throughput and potentially break the original job priority constraints. This paper proposes a deadline‐enabled delay (DLD) scheduling algorithm that optimizes job delay decisions according to real‐time resource availability and resource competition, while still meets job deadline constraints. Experimental results illustrate that the resource availability estimation method of DLD is accurate (92%). Compared with other approaches, DLD reduces job turnaround time by 22% in average while keeping a high locality rate (88%).Copyright © 2013 John Wiley & Sons, Ltd.
Tailoring Copper Oxide Semiconductor Nanorod Arrays for Photoelectrochemical Reduction of Carbon Dioxide to Methanol
Authors: Rajeshwar Krishnan , de Tacconi Norma R. , Ghadimkhani Ghazaleh , Chanmanee Wilaiwan , Janáky Csaba
Published: May 2013

Solar photoelectrochemical reduction of carbon dioxide to methanol in aqueous media was driven on hybrid CuO/Cu2O semiconductor nanorod arrays for the first time. A two‐step synthesis was designed and demonstrated for the preparation of these hybrid copper oxide one‐dimensional nanostructures on copper substrates. The first step consisted in the growth of CuO nanorods by thermal oxidation of a copper foil at 400 °C. In the second step, controlled electrodeposition of p‐type Cu2O crystallites on the CuO walls was performed. The resulting nanorod morphology with controllable wall thickness by adjusting the Cu2O electrodeposition time as well as their surface/bulk chemical composition were probed by scanning electron microscopy, X‐ray diffraction and Raman spectroscopy. Photoelectrosynthesis of methanol from carbon dioxide was demonstrated at −0.2 V vs SHE under simulated AM1.5 solar irradiation on optimized hybrid CuO/Cu2O nanorod electrodes and without assistance of any homogeneous catalyst (such as pyridine or imidazole) in the electrolyte. The hybrid composition, ensuring double pathway for photoelectron injection to CO2, along with high surface area were found to be crucial for efficient performance in methanol generation under solar illumination. Methanol formation, tracked by gas chromatography/mass spectrometry, indicated Faradaic efficiencies of ∼95 %.
Mono‐ and Trinuclear Tripodal Platinum(II) Chelated Complexes Containing a Pyridine/Sulfoxide Based Anchoring Framework
Authors: Barattucci Anna , Plutino M. Rosaria , Faggi Cristina , Bonaccorsi Paola , Monsù Scolaro Luigi , Aversa Maria Chiara
Published: May 2013

New tripodal ligands 2,4,6‐triethyl‐1,3,5‐tris{[1‐(2‐pyridinyl)ethenyl]sulfinylmethyl}benzenes 6, characterized by three pendant chains each containing both sulfoxide and pyridine moieties, were synthesized from the corresponding sulfenic acid and 2‐ethynylpyridine. Two diastereomeric mixtures were obtained and separated, one racemic mixture 6a, having a C3 symmetry axis and the other 6b with no symmetry. With the aim of studying the coordination ability of these chelating‐κN,κS type ligands, monobranched racemic [1‐(2‐pyridinyl)ethenyl]sulfinylbenzene 9 was also synthesized. Upon addition of an equivalent amount of the monochelating ligand 9 or the tripodal species 6a to a CD3CN solution of a platinum(II) complex of the type cis‐[PtMe2(Me2SO)2] (Pt1) or trans‐[PtMeCl(Me2SO)2] (Pt2), platinum(II) coordination and chelation occurred, as definitively indicated by a sharp change in the 1H NMR spectrum towards the final corresponding chelated platinum(II) species and free dimethyl sulfoxide. The prepared platinum(II) species contain one or three fragments of the type {PtMe2}(10 or 12) and {PtMeCl}(11 or 13) bound to the pyridinyl/sulfinyl skeleton in the coordinating ligands 9 and 6a. All the prepared species were fully characterized by NMR spectroscopy from the connectivities in 2D‐COSY, 1H‐13C HSQC and phase‐sensitive 2D‐NOESY spectra which confirm the molecular mechanics calculation predictions.
The Reactivity of Arylphosphorus Acid Amides Under Birch Reduction Conditions
Authors: Stankevič Marek , Włodarczyk Adam , Nieckarz Damian
Published: May 2013

Several classes of arylphosphorus acid amides have been tested in reactions with alkali metal solutions in liquid ammonia. The outcomes of such reactions depend on the structures of the starting materials. Generally, two processes – Birch reduction or cleavage of the P–aryl bond – can be operative. Diarylphosphinic amides tend to undergo double Birch reduction to afford bis(cyclohexadienyl)phosphinic amides.
The Multidimensional Optimal Order Detection method in the three‐dimensional case: very high‐order finite volume method for hyperbolic systems
Authors: Diot S. , Loubère R. , Clain S.
Published: May 2013

The Multidimensional Optimal Order Detection (MOOD) method for two‐dimensional geometries has been introduced by the authors in two recent papers. We present here the extension to 3D mixed meshes composed of tetrahedra, hexahedra, pyramids, and prisms. In addition, we simplify the u2 detection process previously developed and show on a relevant set of numerical tests for both the convection equation and the Euler system that the optimal high order of accuracy is reached on smooth solutions, whereas spurious oscillations near singularities are prevented. At last, the intrinsic positivity‐preserving property of the MOOD method is confirmed in 3D, and we provide simple optimizations to reduce the computational cost such that the MOOD method is very competitive compared with existing high‐order Finite Volume methods.Copyright © 2013 John Wiley & Sons, Ltd.
Probabilistic analysis of risks to us drinking water intakes from 1,4-dioxane in domestic wastewater treatment plant effluents
Authors: Simonich Staci Massey , Sun Ping , Casteel Ken , Dyer Scott , Wernery Dave , Garber Kevin , Carr Gregory , Federle Thomas
Published: May 2013

The risks of 1,4-dioxane (dioxane) concentrations in wastewater treatment plant (WWTP) effluents, receiving primarily domestic wastewater, to downstream drinking water intakes was estimated using distributions of measured dioxane concentrations in effluents from 40 WWTPs and surface water dilution factors of 1323 drinking water intakes across the United States. Effluent samples were spiked with a d8-1,4-dioxane internal standard in the field immediately after sample collection. Dioxane was extracted with ENVI-CARB-Plus solid phase columns and analyzed by GC/MS/MS, with a limit of quantification of 0.30 μg/L. Measured dioxane concentrations in domestic wastewater effluents ranged from <0.30 to 3.30 μg/L, with a mean concentration of 1.11 ± 0.60 μg/L. Dilution of upstream inputs of effluent were estimated for US drinking water intakes using the iSTREEM model at mean flow conditions, assuming no in-stream loss of dioxane. Dilution factors ranged from 2.6 to 48 113, with a mean of 875. The distributions of dilution factors and dioxane concentration in effluent were then combined using Monte Carlo analysis to estimate dioxane concentrations at drinking water intakes. This analysis showed the probability was negligible (p = 0.0031) that dioxane inputs from upstream WWTPs could result in intake concentrations exceeding the USEPA drinking water advisory concentration of 0.35 μg/L, before any treatment of the water for drinking use. Integr Environ Assess Manag 2013;9:554–559. © 2013 SETAC
WHY IMPROVING IRRIGATION EFFICIENCY INCREASES TOTAL VOLUME OF CONSUMPTIVE USE
Authors: Contor Bryce A. , Taylor R. Garth
Published: May 2013

The common prescription for dealing with limited supplies of water is to improve irrigation efficiency, that is, to reduce gross delivery to farm fields while maintaining full crop production. The public and some policy makers continue to assume that the water thus saved constitutes a new supply that may be applied to other uses. Scientists and hydrologists have long understood that the nonconsumed fraction of applied water often becomes the source for another human or ecosystem purpose after leaving the field, and irrigation improvements interrupt these uses. Thoughtful researchers have provided valuable guidance in conceptual frameworks and analysis procedures to address this issue. Researchers have also noted empirically that total consumptive use often increases when efficiency improves, and have cited case‐specific reasons that this occurs. This paper shows it is a general case arising from rational producer behavior in equating the marginal cost of a production input (irrigation water) with its marginal benefit. At any nonzero marginal cost of water, improving irrigation efficiency enables the irrigator to be willing and able to purchase a quantity of irrigation water that sustains more consumptive use than was possible with the prior, less efficient system.

A case study indicates that improving efficiency from 60 to 80% reduces field delivery of irrigation water by 15% but increases consumptive use by 3%. Copyright © 2013 John Wiley & Sons, Ltd.
Toxicity assessment of manganese oxide micro and nanoparticles in Wistar rats after 28 days of repeated oral exposure
Authors: Singh Shailendra Pratap , Kumari Monika , Kumari Srinivas I. , Rahman Mohammed F. , Mahboob M. , Grover Paramjit
Published: May 2013

In the near future, nanotechnology is envisaged for large‐scale use. Hence health and safety issues of nanoparticles (NPs) should be promptly addressed. Twenty‐eight‐day oral toxicity, genotoxicity, biochemical alterations, histopathological changes and tissue distribution of nano and microparticles (MPs) of manganese oxide (MnO2) in Wistar rats was studied. Genotoxicity was assessed using comet, micronucleus and chromosomal aberration assays. The results demonstrated a significant increase in DNA damage in leukocytes, micronuclei and chromosomal aberrations in bone marrow cells after exposure of MnO2‐NPs at 1000, 300 mg kg–1 bw per day and MnO2‐MPs at the dose of 1000 mg kg–1 bw per day. Our findings showed acetylcholinestrase inhibition at 1000 as well as at 300 mg kg–1 bw per day in blood and with all the doses in the brain indicating the toxicity of MnO2‐NPs. Further, the doses significantly inhibited different ATPases in the brain P2 fraction. Significant changes were observed in aspartate aminotransferase (AST), alanine aminotransferase (ALT) and lactate dehydrogenase (LDH) in the liver, kidney and serum in a dose‐dependent manner. MnO2‐MPs at 1000 mg kg–1 bw per day were found to induce significant alterations in biochemical enzymes. A significant distribution was found in all the tissues in a dose‐dependent manner. MnO2‐NPs showed a much higher absorptivity and tissue distribution as compared with MnO2‐MPs. A large fraction of MnO2‐NPs and MnO2‐MPs was cleared by urine and feces. Histopathological analysis revealed that MnO2‐NPs caused alterations in liver, spleen, kidney and brain. The MnO2‐NPs induced toxicity at lower doses compared with MnO2‐MPs. Further, this study did not display gender differences after exposure to MnO2‐NPs and MnO2‐MPs. Therefore, the results suggested that prolonged exposure to MnO2 has the potential to cause genetic damage, biochemical alterations and histological changes. Copyright © 2013 John Wiley & Sons, Ltd.
The Influence of Lentinan on the Capacity of Repair of DNA Damage and Apoptosis Induced by Paclitaxel in Mouse Bone Marrow Cells
Authors: Attia Sabry M. , Harisa Gamaleldin I. , Abd‐Allah Adel R. , Ahmad Sheikh Fayaz , Bakheet Saleh A.
Published: May 2013

The ability of the flavonoid lentinan (LAN) to enhance the repair of paclitaxel (PAC)‐induced DNA damage and apoptosis in mouse bone marrow cells was investigated. Moreover, the possible mechanism underlying this modulation was determined. LAN was neither genotoxic nor apoptogenic at doses equivalent to 1 or 2 mg/kg/day. Pretreatment of mice with LAN significantly enhances the repair of PAC‐induced DNA damage and bone marrow suppression in a dose dependent manner. Moreover, LAN affords significant protection against PAC‐induced apoptosis. A significant increase of reactive oxygen species and a decrease in reduced glutathione levels were observed after PAC treatment and prior administration of LAN before PAC challenge ameliorated these oxidative stress markers. Conclusively, our study provides, for the first time, that LAN enhances the repair of PAC‐induced DNA damage and apoptosis that resides, at least in part, on its ability to modulate the cellular antioxidant levels and consequently protect bone marrow cells from PAC genotoxicity. © 2013 Wiley Periodicals, Inc. J BiochemMol Toxicol 27:370‐377, 2013; View this article online at wileyonlinelibrary.com. DOI 10.1002/jbt.21499
The relationship of flow velocities to vessel diameters differs between extracranial carotid and vertebral arteries of stroke patients
Authors: Owolabi Mayowa O. , Agunloye Atinuke M. , Ogunniyi Adesola
Published: May 2013

Background

Chronic changes in flow rate through arteries produce adjustment of arterial diameters. We compared the relationship between flow velocity and diameter in the carotid and in the vertebral arteries of stroke patients.

Methods

Using triplex ultrasonography, the internal diameter and flow velocities of the common carotid, internal carotid, and vertebral arteries of 176 consecutive stroke patients were measured. Correlations were examined with Pearson's statistics at an alpha level of 0.05.

Results

Mean age of the patients was 59.3 ± 12 years, and 66% had cerebral infarcts. Diameter and blood flow velocities showed significant negative correlations (−0.115 ≥ r ≥ −0.382) in the carotid arteries on both sides, but positive correlations (0.211 ≤ r ≤ 0.320) in the vertebral arteries, even after controlling for age, gender, and blood pressure.

Conclusions

Our study demonstrated different diameter/flow relationships in the carotid and the vertebral arteries of stroke patients, which may suggest pathologic changes in the adaptive processes governing vessel diameter and growth, especially in the carotid arteries. © 2013 Wiley Periodicals, Inc. J Clin Ultrasound 42:16–23, 2014
Effect of trends of middle atmosphere gases on the mesosphere and thermosphere
Authors: Qian Liying , Marsh Daniel , Merkel Aimee , Solomon Stanley C. , Roble Raymond G.
Published: May 2013

We conducted model simulations to examine how changes in concentration of radiatively active trace gases in the middle atmosphere affect long‐term changes in the upper atmosphere. We focused our model study on the impact of increases in carbon dioxide (CO2), methane (CH4), and water vapor (H2O), and decreases in ozone (O3) between 1983 and 2003. We used both the National Center for Atmospheric Research Whole Atmosphere Community Climate Model and the Thermosphere‐Ionosphere‐Mesosphere‐Electrodynamics General Circulation Model, global mean version, in this study. The model simulations indicate that CO2 is the main forcing mechanism of long‐term changes in the thermsophere, with minor influences from O3, CH4, and H2O. At 400 km altitude, global mean thermospheric neutral density decreased by ~4.5% due to CO2 forcing alone, whereas it decreased by ~4.8% due to the combined forcing from all four gases. O3 depletion caused cooling in the stratosphere and mesosphere (maximum decrease of 0.5 K) due to reduced absorption of solar ultraviolet radiation, but had nearly no cooling effect in the thermosphere. However, due to thermal contraction in the stratosphere and mesosphere, O3 depletion caused a small decrease in thermospheric neutral density of ~0.25%. Increases in both CH4 and H2O may slightly warm the upper mesosphere and thermosphere due to increased chemical heating and absorption of solar ultraviolet radiation.
Comparison of statistical estimates of potential seasonal predictability
Authors: Feng X. , DelSole T. , Houser P.
Published: May 2013

Four methods for estimating potential seasonal predictability from a single time series are compared. The methods are: an analysis of variance procedure proposed by Shukla and Gutzler (SG), a spectral method proposed by Madden (MN), a bootstrap method proposed by the authors, and an analysis of covariance (ANOCOVA) method proposed by the authors. The time series used for comparison are taken from Monte Carlo simulations, an atmospheric general circulation model (AGCM), and reanalysis data. The comparison clearly reveals that SG systematically underestimates weather noise variance more strongly than the other methods and is therefore not a generally useful method. MN produces the least biased estimates of weather noise variance, but it tends to have a higher probability of identifying insignificant predictability than the other methods. Unfortunately, no simple, universally corrected statements can be made regarding the relative performances of MN, ANOCOVA, and bootstrap based on the AGCM output. Overall, the reanalysis‐based estimates of potential predictability of seasonal mean temperature derived from these methods is generally in accord with previous estimates, both in spatial structure and in magnitude. Omitting SG, the other three methods consistently identify about 80% of the globe as significantly predictable, and about 5% of the globe as insignificantly predictable. The remaining 15% of the globe, mostly over extratropical land, yields inconsistent assessments of potential predictability, indicating sensitivity to the assumptions underlying each of the methods. Interestingly, winter mean temperature over most of North America is found to be insignificantly predictable by all three methods.
The early Martian atmosphere: Investigating the role of the dust cycle in the possible maintenance of two stable climate states
Authors: Kahre Melinda A. , Vines Sarah K. , Haberle Robert M. , Hollingsworth Jeffery L.
Published: May 2013

C. Leovy (personal communication, 2007) speculated that two stable climate states on early Mars could have resulted from interactions between the dust and CO2 cycles. In one state, a highly active dust cycle would prevent atmospheric collapse, and in the second, the collapsed atmosphere would not maintain an active dust cycle. An initial assessment of this idea is presented based on a Mars general circulation model parameter study. A range of global dust loadings, CO2 ice albedos, and obliquities are investigated to explore conditions in which increasing the atmospheric dust content stabilizes an otherwise unstable atmosphere. We find that dust only stabilizes the atmosphere at high obliquity and when the CO2 ice albedo is high. Although results suggest that two stable states could have existed on early Mars under limited conditions, further work is needed to know if the conditions necessary are physically plausible.
Deltaic deposits at Aeolis Dorsa: Sedimentary evidence for a standing body of water on the northern plains of Mars
Authors: DiBiase Roman A. , Limaye Ajay B. , Scheingross Joel S. , Fischer Woodward W. , Lamb Michael P.
Published: May 2013

A fundamental long‐standing question regarding Mars history is whether the flat and low‐lying northern plains ever hosted an ocean. The best opportunity to solve this problem is provided by stratigraphic observations of sedimentary deposits onlapping the crustal dichotomy. Here, we use high‐resolution imagery and topography to analyze a branching network of inverted channel and channel lobe deposits in the Aeolis Dorsa region, just north of the dichotomy boundary. Observations of stacked, cross‐cutting channel bodies and stratal geometries indicate that these landforms represent exhumed distributary channel deposits. Observations of depositional trunk feeder channel bodies, a lack of evidence for past topographic confinement, channel avulsions at similar elevations, and the presence of a strong break in dip slope between topset and foreset beds suggest that this distributary system was most likely a delta, rather than an alluvial fan or submarine fan. Sediment transport calculations using both measured and derived channel geometries indicate a minimum delta deposition time on the order of 400 years. The location of this delta within a thick and widespread clastic wedge abutting the crustal dichotomy boundary, unconfined by any observable craters, suggests a standing body of water potentially 105 km2in extent or greater and is spatially consistent with hypotheses for a northern ocean.
Liver lesion detection and characterization: Role of diffusion‐weighted imaging
Authors: Galea Nicola , Cantisani Vito , Taouli Bachir
Published: May 2013

Diffusion‐weighted imaging (DWI) plays an emerging role for the assessment of focal and diffuse liver diseases. This growing interest is due to that fact that DWI is a noncontrast technique with inherent high contrast resolution, with promising results for detection and characterization of focal liver lesions. Recent advances in diffusion image quality have also added interest to this technique in the abdomen. The purpose of this review is to describe the current clinical roles of DWI for the detection and characterization of focal liver lesions, and to review pitfalls, limitations, and future directions of DWI for assessment of focal liver disease. J. Magn. Reson. Imaging 2013;37:1260–1276. © 2012 Wiley Periodicals, Inc.
Comparative study on modulation dynamic characteristics of laser diodes using RZ and NRZ bit formats
Authors: Ahmed Moustafa , Mahmoud Safwat W. Z. , Mahmoud Alaa A.
Published: May 2013

A comprehensive study on semiconductor laser characteristics under gigabit‐per‐second digital modulation is presented. Comparison of the modulation characteristics under both formats of the return to zero (RZ) and non‐return to zero (NRZ) bit formats is introduced. The modulation characteristics include the eye diagram, turn‐on jitter (TOJ) and frequency chirp. The study elucidates how the laser modulation performance changes with variation of the modulation bit rate relative to the maximum bit rate and the setting bit rate of the relaxation oscillations. The relative contributions of the intrinsic noise of the laser and the pseudorandom bit‐pattern effect to the modulation characteristics are differentiated. The results showed that when the bit rate is higher than the setting bit rate, the eye diagram is partially closed and becomes completely closed when the bit rate increases beyond the maximum bit rate. When the bit rate is higher than 2.25 Gbps, the TOJ values under NRZ modulation are smaller than those under RZ modulation near the threshold level. Under both RZ and NRZ formats, chirp increases with the bit rate with the chirp under the RZ format being higher than that under the NRZ format. Copyright © 2013 John Wiley & Sons, Ltd.
Relationship between membrane damage, leakage of intracellular compounds, and inactivation of Escherichia coli treated by pressurized CO2
Authors: Yao Chunyan , Li Xiaodong , Bi Weiwei , Jiang Chen
Published: May 2013

The relationship between membrane damage, leakage of intracellular compounds, and inactivation of Escherichia coli treated by pressurized CO2 was investigated by assessing the inactivation, bacterial cell membrane permeability, the leakage of protein, nucleic acid, and K+ and Mg2+ of E. coli. The results indicated that pressurized CO2 treatment induced the leakage of protein in E. coli, but the time of leakage was lagged behind the time of 99% E. coli inactivation, so it was only the secondary phenomenon of inactivation. The inactivation of E. coli was related to the leakage of nucleic acid, K+, Mg2+ induced by the pressurized CO2 treatment. There was direct relationship between the inactivation of E. coli and the damaging effect of pressurized CO2 treatment on the cell membrane of E. coli.
Safety of intra‐operative vasopressor in free jejunal flap reconstruction
Authors: Chan Jimmy Yu Wai , Chow Velda Ling Yu , Liu Lawrence Hin Lun
Published: May 2013

Background

Microvascular surgeons always hold strong belief against the use of vasopressors during free flap surgery. Our aim is to study the safety of intra‐operative vasopressors on free jejunal flap reconstruction.

Methods

A retrospective chart review was performed on patients undergoing free jejunal flap reconstruction, aiming at investigating the intra‐operative use of vasopressors and the potential complications associated.

Results

Between 1984 and 2012, 110 free jejunal flaps were performed for reconstruction of circumferential pharyngeal defects created after resection of cancers of the hypopharynx. Intra‐operative vasopressor was given in 81 (73.6%) patients. The most common vasopressors used were ephedrine (42.7%), phenylephrine (14.5%) or both (42.8%). They were administered to the patients before the start of flap harvesting (n = 32, 29.1%), during the flap harvesting (n = 30, 27.3%), during microvascular anastomosis (n = 20, 18.2%), or they were given more than once during the whole operation (n = 28, 25.4%). The incidence of intra‐operative re‐anastomosis due to thrombosis was 4.5% and the post‐operative flap failure rate was 5.4%. There was no significant relationship between the administration of vasopressor during surgery and the need for intra‐operative re‐anastomosis, post‐operative flap failure and the timing of flap failure. Similarly, there was also no relationship between the timing of vasopressor administration and the above variables. The long‐term stricture rate was 2.7%, the risk of which was not increased by the intra‐operative use of vasopressors.

Conclusion

The intra‐operative use of vasopressors is safe in free jejunal flap reconstruction. © 2013 Wiley Periodicals, Inc. Microsurgery 33:358–361, 2013.
Facial artery myomucosal free flap for cheek mucosa reconstruction: A case report
Authors: Massarelli Olindo , Gobbi Roberta , Biglio Andrea , Tullio Antonio
Published: May 2013

Squamous cell carcinoma (SCC) of the buccal mucosa is an aggressive form of oral cancer. It tends to spread to adjacent tissues and often metastasizes to occult cervical node. There are multiple techniques for cheek reconstruction after tumor removal, including temporalis myocutaneous and temporoparietal fascial pedicled flaps and a forearm free flap. In this report, a case of a 76‐year‐old man with SCC of the left cheek mucosa and extending to the posterolateral superior alveolar ridge is presented. The patient underwent radical excision of the tumor, omolateral modified radical neck dissection (MRND‐III), and contralateral selective neck dissection (levels I–III). Reconstruction was performed with a facial artery myomucosal free flap. The flap was transplanted successfully, and there were no donor or recipient site complications. This technique is a good reconstructive option because of its adherence to the plastic surgery principle of “replacing like with like” and its minimal donor‐site morbidity. © 2013 Wiley Periodicals, Inc. Microsurgery 33:401–405, 2013.