bluuebunny/crossref_metadata_2025 huggingface dataset:
Electrophilic Selenium/Tellurium Reagents: Reactivity and their Contribution to Green Chemistry
Authors: Santi Claudio , Tidei Caterina
Published: June 2013

Selenium moieties are conveniently introduced into an organic molecule using electrophilic selenenylating reagents and the process is generally highly chemo‐, regio and stereoselective requiring mild experimental conditions. In addition, organoselenium derivatives can be directly converted into a number of different functional groups and the organoselenium moiety can be employed for further stereoselective manipulation of the molecule. Several applications are described for the inter‐ and intramolecular carbon–oxygen, carbon–nitrogen and carbon–carbon bond formation as well as for the α‐functionalization of carbonyl derivatives and the nucleophilic aromatic substitution reactions. More recently, the development of simple and efficient procedures for the preparation of chiral selenium reagents allowed their successful application in electrophilic asymmetric synthesis. Nowadays, probably the most recent aspect of this kind of chemistry is correlated with some new reactions that can be effected using organoselenium compounds as catalysts in renewable or alternative non‐toxic media (water, glycerol, ionic liquids) bringing this kind of research in line with the concept of ‘Green and Sustainable Chemistry’. During the last half century, the application of tellurium reagents has undergone a notable improvement, overcoming the reluctance of several researchers mainly due to the characteristic persistent smell of many tellurium derivatives. In this chapter some general aspects of the chemistry promoted by electrophilic selenium and tellurium compounds are described exploiting also the differences between these two reagents.
Generation and Reactivity of Lipid Hydroperoxides in Biological Systems
Authors: Girotti Albert W. , Korytowski Witold
Published: June 2013

Numerous reviews have been published about the structural/functional damage caused by peroxidation of unsaturated lipids (phospholipids, glycolipids, cholesterol) in model membranes, cellular membranes, and lipoproteins. Less attention has been given to hydroperoxide species (LOOHs), which arise as intermediates of free radical‐mediated (chain) peroxidation or by direct ene‐addition of singlet molecular oxygen. This chapter focuses on nonenzymatic LOOH formation and on LOOH reactivity in biological systems, including cell membranes and lipoproteins. Specialized techniques for analyzing these processes are described. Two competing LOOH reaction pathways are discussed in detail: (i) iron‐catalyzed one‐electron reduction to oxyl radicals (LO•), which expand chain peroxidation, and (ii) enzyme‐catalyzed two‐electron reduction to alcohols (LOH), which inhibits further chain propagation. In addition to these competing fates, LOOHs can undergo spontaneous or protein‐assisted translocation between membranes, lipoproteins, and membranes and lipoproteins, a more recently recognized phenomenon. Intracellular LOOH transfer could result in damage/toxicity enhancement or abatement, depending on prooxidant vs. antioxidant availability. We also discuss a novel, but still poorly understood response to LOOH trafficking, namely, activation of redox signaling pathways. We postulate that LOOHs, unlike the better known signaling molecule, H2O2, will be targeted to relatively hydrophobic “sensor” sites and that these sites are distinct from those targeted by H2O2. Thus, the authors' intent in preparing this chapter was to discuss not only the well‐established chemistry of LOOH generation and turnover, but also LOOH involvement in signal transduction, the importance of which in the field of redox signaling is only beginning to be appreciated.
High‐Mobility Air‐Stable Naphthalene Diimide‐Based Copolymer Containing Extended π‐Conjugation for n‐Channel Organic Field Effect Transistors
Authors: Kim Ran , Amegadze Paul S. K. , Kang Il , Yun Hui‐Jun , Noh Yong‐Young , Kwon Soon‐Ki , Kim Yun‐Hi
Published: June 2013

A high‐performance naphthalene diimide (NDI)‐based conjugated polymer for use as the active layer of n‐channel organic field‐effect transistors (OFETs) is reported. The solution‐processable n‐channel polymer is systematically designed and synthesized with an alternating structure of long alkyl substituted‐NDI and thienylene–vinylene–thienylene units (PNDI‐TVT). The material has a well‐controlled molecular structure with an extended π‐conjugated backbone, with no increase in the LUMO level, achieving a high mobility and highly ambient stable n‐type OFET. The top‐gate, bottom‐contact device shows remarkably high electron charge‐carrier mobility of up to 1.8 cm2 V−1 s−1 (Ion/Ioff = 106) with the commonly used polymer dielectric, poly(methyl methacrylate) (PMMA). Moreover, PNDI‐TVT OFETs exhibit excellent air and operation stability. Such high device performance is attributed to improved π–π intermolecular interactions owing to the extended π‐conjugation, apart from the improved crystallinity and highly interdigitated lamellar structure caused by the extended π–π backbone and long alkyl groups.
Hotel housekeeping work influences on hypertension management
Authors: Sanon Marie‐Anne
Published: June 2013

Background

Characteristics of hotel housekeeping work increase the risk for hypertension development. Little is known about the influences of such work on hypertension management.

Methods

For this qualitative study, 27 Haitian immigrant hotel housekeepers from Miami‐Dade County, FL were interviewed. Interview transcripts were analyzed with the assistance of the Atlas.ti software for code and theme identification.

Results

Influences of hotel housekeeping work on hypertension management arose both at the individual and system levels. Factors at the individual level included co‐worker dynamics and maintenance of transmigrant life. Factors at the system level included supervisory support, workload, work pace, and work hiring practices. No positive influences were reported for workload and hiring practices.

Conclusions

Workplace interventions may be beneficial for effective hypertension management among hotel housekeepers. These work influences must be considered when determining effective methods for hypertension management among hotel housekeepers. Am. J. Ind. Med. 56:1402–1413. © 2013 Wiley Periodicals, Inc.
Chimpanzee‐red colobus encounter rates show a red colobus population decline associated with predation by chimpanzees at Ngogo
Authors: Watts David P. , Amsler Sylvia J.
Published: June 2013

Chimpanzees (Pan troglodytes) hunt various primates, but concentrate on red colobus monkeys (Piliocolobus spp.) wherever the two species are sympatric. The extraordinarily large Ngogo chimpanzee community in Kibale National Park, Uganda, preys heavily on the local population of red colobus (P. tephrosceles). Census data showed a steep decline in this population in the center of the chimpanzees' home range between 1975 and 2007 [Lwanga et al., 2011; Teelen, 2007b]. Given no obvious change in food availability, predation by chimpanzees was the most likely cause [ibid.; Teelen, 2008]. However, census data from other parts of the home range raised the possibility that the decline was restricted to this central area [Teelen, 2007a] We present data from 1998 to 2012 on the rate of encounters between chimpanzees and red colobus that provide a chimpanzee‐centered estimate of red colobus density, thus of predation opportunities, throughout the home range. These corroborate census data by showing a long‐term decline in encounters near the center. They also show that encounters become relatively more common at increasing distances from the center, but encounter rates have decreased even in peripheral areas and, by implication, the red colobus population has declined throughout the study area. These data corroborate Teelen's [2008] conclusion that chimpanzee predation on red colobus during the 1990s and early 2000s was unsustainable. Hunting rates and prey offtake rates have also declined markedly; whether this will allow the red colobus population to recover is unknown. In contrast, rates at which chimpanzees encountered redtail monkeys (Cercopithecus ascanius) and grey‐cheeked mangabeys (Lophocebus albigena) did not decrease. Neither did they increase, however, contrary to long‐term census data from the center of the study area [Lwanga et al., 2011]. Am. J. Primatol. 75:927–937, 2013. © 2013 Wiley Periodicals, Inc.
Gastrointestinal symbionts of chimpanzees in Cantanhez National Park, guinea‐bissau with respect to habitat fragmentation
Authors: Sá Rui M. , Petrášová Jana , Pomajbíková Kateřina , Profousová Ilona , Petrželková Klára J. , Sousa Cláudia , Cable Joanne , Bruford Michael W. , Modrý David
Published: June 2013

One of the major factors threatening chimpanzees (Pan troglodytes verus) in Guinea‐Bissau is habitat fragmentation. Such fragmentation may cause changes in symbiont dynamics resulting in increased susceptibility to infection, changes in host specificity and virulence. We monitored gastrointestinal symbiotic fauna of three chimpanzee subpopulations living within Cantanhez National Park (CNP) in Guinea Bissau in the areas with different levels of anthropogenic fragmentation. Using standard coproscopical methods (merthiolate‐iodine formalin concentration and Sheather's flotation) we examined 102 fecal samples and identified at least 13 different symbiotic genera (Troglodytella abrassarti,Troglocorys cava,Blastocystisspp.,Entamoebaspp.,Iodamoeba butschlii,Giardia intestinalis,Chilomastix mesnili,Bertiellasp.,Probstmayria gombensis, unidentified strongylids,Strongyloides stercoralis,Strongyloides fuelleborni, andTrichurissp.). The symbiotic fauna of the CNP chimpanzees is comparable to that reported for other wild chimpanzee populations, although CNP chimpanzees have a higher prevalence ofTrichurissp. Symbiont richness was higher in chimpanzee subpopulations living in fragmented forests compared to the community inhabiting continuous forest area. We reported significantly higher prevalence ofG. intestinalisin chimpanzees from fragmented areas, which could be attributed to increased contact with humans and livestock. Am. J. Primatol. 75:1032–1041, 2013. © 2013 Wiley Periodicals, Inc.
Der gewundene Pfad zum Erythropoietin entlang der Grenze von Chemie und Biologie
Authors: Wilson Rebecca M. , Dong Suwei , Wang Ping , Danishefsky Samuel J.
Published: June 2013

Die Totalsynthese eines homogenen Erythropoietins (EPO), das die native Aminosäuresequenz aufweist und Chitobioseglycane an jeder der drei N‐glycosylierten Wildtyp‐Stellen trägt, wurde in unserem Laboratorium erzielt. Wir beschreiben in diesem Kurzaufsatz unsere ein Jahrzehnt dauernden Forschungsbemühungen um die Synthese dieser anspruchsvollen Zielverbindung. Entscheidend für den Erfolg war das Zusammenspiel zwischen Biologie und Chemie, den beiden Grundpfeilern der Naturwissenschaften.
Study of uranium sorption using D2EHPA‐impregnated polymeric beads
Authors: Singh Krishan Kant , Pathak Sanjay K. , Kumar Manmohan , Mahtele A. K. , Tripathi S. C. , Bajaj Parma N.
Published: June 2013

The extractant‐impregnated polymeric beads (EIPBs), containing Di(2‐ethylhexyl) phosphonic acid (D2EHPA) as an extractant and polyethersulfone as base polymer, were prepared by phase‐inversion method. These beads were characterized by fourier transform infrared spectroscopy (FTIR), thermogravimetric analysis (TGA), and scanning electron microscope (SEM) analysis to gain insight into the composition and morphology of beads. The beads exhibited good acid stability as no significant structural deformation or leaching out of the extractant was observed in 6M HNO3 solution, up to the studied equilibration time of 15 days. The synthesized EIPBs were evaluated, for their ability to absorb uranium from aqueous solution, at different concentration and pH values. The kinetics measurement showed that about 90 min of equilibration time was enough to remove saturation amount of uranium from the solution. Kinetic modeling analysis of the extraction results was carried out using pseudo‐first‐order, pseudo‐second‐order, and intraparticle diffusion equations and the corresponding rate constants were determined. The equilibrium data were fitted into different isotherm models and were found to be represented well by the Freundlich isotherm equation. Reusability of the beads was also established by multiple sorption–desorption experiments. © 2013 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 130: 3355–3364, 2013
Mechanical characteristics of swollen gellan gum hydrogels
Authors: De Silva D. Awanthi , Poole‐Warren Laura A. , Martens Penny J. , in het Panhuis Marc
Published: June 2013

The behavior of swollen gellan gum hydrogels in terms of mechanical properties, weight loss, and cell growth inhibition of leachates is presented. Low‐acyl gellan gum (LAGG), high‐acyl gellan gum (HAGG), and a HAGG–LAGG blend were soaked in phosphate‐buffered saline (PBS) at pH 7.4 and 37°C for up to 168 days. The gels exhibited their maximum mass loss and swelling after 28 days of immersion in PBS. LAGG gels exhibited lower value for mass loss and the chain‐release diffusion coefficient than gels consisting of HAGG and the HAGG–LAGG blend. The change in mechanical and rheological characteristics during soaking of the three hydrogels was attributed to mass loss, while LAGG hydrogels also showed evidence of effects because of cation exchange with the surrounding medium. The mechanical characteristics of the LAGG, HAGG, and blend hydrogels relative to each other did not change during swelling (although the magnitude changed). L929 fibroblasts growth inhibition tests showed that the leachate products of the three gels can be considered noncytotoxic, which is important for their future application in tissue engineering. © 2013 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 130: 3374–3383, 2013
Effect of molecular architecture on the crystalline structure and stiffness of iPP homopolymers: Modeling based on annealing experiments
Authors: Horváth Zsuzsanna , Menyhárd Alfréd , Doshev Petar , Gahleitner Markus , Tranninger Cornelia , Kheirandish Saeid , Varga József , Pukánszky Béla
Published: June 2013

Five polypropylene (PP) homopolymers were selected and their molecular structure was thoroughly characterized to determine the effect of molecular architecture on their annealing behavior and on the ultimate stiffness achieved by heat treatment. Molecular mass and its distribution were characterized by rheological measurements, while chain regularity was determined by differential scanning calorimetry (DSC) using stepwise isothermal segregation technique (SIST). The samples were annealed in two different ways. Tensile bars were treated in an oven at 165 °C for increasing times to determine changes in stiffness. Various defects (microcracks and voids) developed during the annealing of tensile specimens that did not allow the reliable determination of modulus by direct measurement. On the other hand, the second approach, the annealing of small samples in a DSC cell clearly showed the changes occurring in crystalline structure and also the effect of nucleation and molecular architecture on them. The large molecular weight fraction used to facilitate nucleation hinders crystal perfection, whereas the presence of a heterogeneous nucleating agent increases overall crystallinity, but does not influence recrystallization during annealing. Melting traces were transformed into lamella thickness distributions from which average lamella thickness was derived. Lamella thickness and crystallinity, the independent variables of the model equation used for the calculation of modulus, were extrapolated to infinite annealing time to predict maximum stiffness. The value obtained, 3.5 GPa, is very far from the theoretically predicted 40 GPa of oriented crystals, which cannot be achieved under practical conditions. © 2013 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 130: 3365–3373, 2013
Image and multimedia resources in an academic environment: A qualitative study of students' experiences and literacy practices
Authors: Matusiak Krystyna K.
Published: June 2013

The digital environment provides an abundance of images and multimedia and offers a new potential for using resources in multiple modes of representation for teaching and learning. This article reports the findings of a case study that investigated the use of image and multimedia resources in an undergraduate classroom. The study assumed a contextual approach and focused on different class contexts and students' literacy practices. The class, which took place in a resource‐rich, multimodal environment, was perceived by students as a positive learning experience. The distribution of resources and their role in teaching and learning varied and depended on the context of use. The findings indicate that images fulfilled important descriptive and mnemonic functions when students were introduced to new concepts, but their role was limited in practices that required students to analyze and synthesize knowledge.
Different electromagnetic field waveforms have different effects on proliferation, differentiation and mineralization of osteoblasts in vitro
Authors: Zhou Jian , Wang Jia‐Qi , Ge Bao‐Feng , Ma Xiao‐Ni , Ma Hui‐Ping , Xian Cory J. , Chen Ke‐Ming
Published: June 2013

Noninvasive electromagnetic fields (EMFs) have been known to be able to improve bone health; however, their optimal application parameters and action mechanisms remain unclear. This study compared the effects of different forms of EMFs (sinusoidal, triangular, square, and serrated, all set at 50 Hz frequency and 1.8 mT intensity) on proliferation, differentiation and mineralization of rat calvarial osteoblasts. Square EMFs stimulated osteoblast proliferation but sinusoidal EMFs inhibited it. Sinusoidal and triangular EMFs produced significantly greater alkaline phosphatase (ALP) activity, ALP staining areas, calcium deposition, mineralized nodule areas, and mRNA expression of Runx‐2, osteoprotegerin and insulin‐like growth factor‐I than square and serrated EMFs (P < 0.01). Triangular EMFs had a greater effect than sinusoidal EMFs on every indices except for Runx‐2 mRNA expression (P < 0.05). These results indicated that while square EMFs promoted proliferation and had no effect on the differentiation of osteoblasts, sinusoidal EMFs inhibited proliferation but enhanced osteogenic differentiation. Triangular EMFs did not affect cell proliferation but induced the strongest osteogenic activity among the four waveforms of EMFs. Thus, the effects of EMFs on proliferation and differentiation of osteoblasts in vitro were dependent on their waveforms. Bioelectromagnetics. 35:30–38, 2014. © 2013 Wiley Periodicals, Inc.
Legitimating status: perceptions of meritocracy and inequality among undergraduates at an elite British university
Authors: Warikoo Natasha Kumar , Fuhr Christina
Published: June 2013

Given the frequent critiques of elite universities for admitting low numbers of state school graduates and, more recently, British Afro‐Caribbean students, how do students attending those universities make meaning of the admissions process? Through an analysis of 46 one‐on‐one in‐depth interviews with undergraduates attending Oxford University, we show that students believe in the fairness of the admissions process, while lamenting the lack of opportunities for educational advancement faced by some disadvantaged youth in British society. Despite their understanding that many British youth do not have access to educational experiences that make Oxbridge an attainable goal, most students do not support changes to make access more equitable across class or racial/ethnic lines. This perspective, which legitimates the status students gain through matriculation at an elite university, supports the maintenance of unequal access to an Oxford education despite the advantages that education is known to confer to graduates. The findings demonstrate elites acknowledging the disadvantages of particular groups in society without acknowledging their own advantages in the same system. They do so by recognizing two elements of merit: (1) intelligence, which most students assumed led to their own admission; and (2) cultivation of that intelligence, which requires elite secondary schools and which most students see as disadvantaging particular groups in society. In the paper we highlight differences in meaning‐making between graduates of grammar, comprehensive and private schools.
Cost-effectiveness of laparoscopic fundoplication versus continued medical management for the treatment of gastro-oesophageal reflux disease based on long-term follow-up of the REFLUX trial
Authors: Faria R , Bojke L , Epstein D , Corbacho B , Sculpher M
Published: June 2013

Background

Laparoscopic fundoplication surgery has been shown to be a cost-effective alternative to continued medical management over 1 year for patients with gastro-oesophageal reflux disease (GORD). The longer-term cost-effectiveness is, however, uncertain. This study evaluated the long-term health benefits, costs and cost-effectiveness of laparoscopic fundoplication compared with continued medical management in patients with GORD.

Methods

Individual patient data were used from the 5-year follow-up of the REFLUX trial, a large multicentre, pragmatic, randomized trial in which 357 patients with GORD for at least 12 months at trial entry were allocated randomly to early laparoscopic fundoplication or continued medical management. Health outcomes were expressed in quality-adjusted life-years (QALYs). A UK National Health Service perspective was used for costs.

Results

The group randomized to surgery experienced better health outcomes in each year of follow-up, but the difference narrowed over time. At 5 years, the surgery group had experienced 0·216 (95 per cent confidence interval 0·021 to 0·412) more QALYs but also accrued €1832 (1214 to 2448) more costs. The incremental cost-effectiveness ratio was €8481 per QALY gained. The probability that surgery is the most cost-effective intervention was 0·932 at a threshold of €24 134/QALY (£20 000/QALY). Results were robust to most sensitivity analyses, except where patients with missing data randomized to surgery were assumed to have worse health outcomes.

Conclusion

Laparoscopic fundoplication is a cost-effective alternative to continued medical management over 5 years. No evidence was found to suggest that the cost-effectiveness of laparoscopic fundoplication diminishes over time.
The posttreatment mean apparent diffusion coefficient of primary tumor is superior to pretreatment ADCmean of primary tumor as a predictor of prognosis with cervical cancer
Authors: Nakamura Keiichiro , Kajitani Satoshi , Joja Ikuo , Haruma Tomoko , Fukushima Chikako , Kusumoto Tomoyuki , Seki Noriko , Hiramatsu Yuji
Published: June 2013

The objective of this study was to investigate the correlation of pretreatment and posttreatment measurements as the mean apparent diffusion coefficient (ADCmean) by diffusion‐weighted magnetic resonance imaging (DWI) findings with prognostic factors in patients with squamous cell carcinoma (SCC) of primary cervical cancer. The pretreatment and posttreatment ADCmean of the primary tumor were examined for their correlations with the prognosis in 69 patients with SCC of primary cervical cancer by radiotherapy (RT) with or without concurrent chemotherapy (CCRT). The median disease‐free survival (DFS) and overall survival (OS) times of patients were 20.97 and 23.47 months (follow‐up periods for DFS and OS: 1–72 and 1–72 months). The DFS and OS rates of patients with low pretreatment and posttreatment ADCmean of the primary tumor were also significantly worse than those of patients exhibiting high pretreatment and posttreatment ADCmean of the primary tumor (DFS; P = 0.0130 and P < 0.0001, OS; P = 0.0010 and P < 0.0001). Multivariate analyses showed that low posttreatment ADCmean of the primary tumor was an independent prognostic factor for DFS and OS (P < 0.0001 and P < 0.0001). The low posttreatment ADCmean of the primary tumor is a useful clinical prognostic biomarker for recurrence and survival in patients with cervical cancer.
Dual‐Mesoporous ZSM‐5 Zeolite with Highly b‐Axis‐Oriented Large Mesopore Channels for the Production of Benzoin Ethyl Ether
Authors: Zhou Xiaoxia , Chen Hangrong , Zhu Yan , Song Yudian , Chen Yu , Wang Yongxia , Gong Yun , Zhang Guobin , Shu Zhu , Cui Xiangzhi , Zhao Jinjin , Shi Jianlin
Published: June 2013

Dual‐mesoporous ZSM‐5 zeolite with highly b axis oriented large mesopores was synthesized by using nonionic copolymer F127 and cationic surfactant CTAB as co‐templates. The product contains two types of mesopores—smaller wormlike ones of 3.3 nm in size and highly oriented larger ones of 30–50 nm in diameter along the b axis—and both of them interpenetrate throughout the zeolite crystals and interconnect with zeolite microporosity. The dual‐mesoporous zeolite exhibits excellent catalytic performance in the condensation of benzaldehyde with ethanol and greater than 99 % selectivity for benzoin ethyl ether at room temperature, which can be ascribed to the zeolite lattice structure offering catalytically active sites and the hierarchical and oriented mesoporous structure providing fast access of reactants to these sites in the catalytic reaction. The excellent recyclability and high catalytic stability of the catalyst suggest prospective applications of such unique mesoporous zeolites in the chemical industry.
Synthesis of Trisubstituted Ureas by a Multistep Sequence Utilizing Recyclable Magnetic Reagents and Scavengers
Authors: Kainz Quirin M. , Zeltner Martin , Rossier Michael , Stark Wendelin J. , Reiser Oliver
Published: June 2013

Unprecedented magnetic borohydride exchange (mBER), magnetic Wang aldehyde (mWang) and magnetic amine resins were prepared from highly magnetic polymer‐coated cobalt or iron nanoparticles. Microwave irradiation was used to obtain excellent degrees of functionalization (>95 %) and loadings (up to 3.0 mmol g−1) in short reaction times of 15 min or less. A small library of ureas and thioureas was synthesized by the exclusive application of these magnetic resins. As a first step, a reductive amination of aromatic and aliphatic aldehydes was carried out with mBER. The excess of primary amine needed to complete the reaction was subsequently scavenged selectively by mWang. Simple magnetic decantation from the resins resulted in secondary amines in good to excellent yields and purities. The used magnetic resins were efficiently regenerated and reused for the next run. In a second step, the secondary amines were converted to trisubstituted (thio)ureas in excellent yields and purities by stirring with an excess of iso(thio)cyanate, which was scavenged by addition of the magnetic amine resin after completion of the reaction. The whole reaction sequence is carried out without any purification apart from magnetic decantation; moreover, conventional magnetic stirring can be used as opposed to the vortexing required for polystyrene resins.
Synthesis and Characterization of Various Photosensitive Copper(II) Complexes with 5‐(1‐Methylhydrazinyl)‐1H‐tetrazole as Ligand and Perchlorate, Nitrate, Dinitramide, and Chloride as Anions
Authors: Joas Manuel , Klapötke Thomas M. , Stierstorfer Jörg , Szimhardt Norbert
Published: June 2013

The preparation of 5‐(1‐methylhydrazinyl)‐1H‐tetrazole monohydrate (1⋅H2O) and various copper(II) complexes with perchlorate (2 and 3), nitrate (4, 5, and 6), dinitramide (7), and chloride (8) is described. The coordination compounds (monomers, dimers, and polymers) were characterized through infrared spectroscopy and elemental analysis. Further, the structures of 2 and 4–8 were determined by single‐crystal X‐ray diffraction. Compound 1 can act as a bidentate ligand in its neutral form (HMHT) and as a μ2‐ or μ3‐bridging ligand in its deprotonated form (MHT). The energetic properties of the synthesized complexes, such as their sensitivities toward impact and friction, were determined, and laser ignition tests were performed. New information about the laser initiation process and the role of the anion in the initiation criterion was obtained. The perchlorate complexes 2 (Tdecomp=217 °C) and 3 (Tdecomp=206 °C) are potential primary explosives.
Highly Active and Selective Catalysis of Copper Diphosphine Complexes for the Transformation of Carbon Dioxide into Silyl Formate
Authors: Motokura Ken , Kashiwame Daiki , Takahashi Naoki , Miyaji Akimitsu , Baba Toshihide
Published: June 2013

Copper diphosphine complexes have been found to be highly active and selective homogeneous catalysts for the hydrosilylation of CO2. The structure of the phosphine ligands strongly affects their catalytic activity. Turnover number (TON) reaches 70 000 after 24 hours with 1,2‐bis(diisopropylphosphino)benzene as a ligand under 1 atmosphere of CO2. 1H and 13C NMR spectra, carried out under the reaction conditions, showed the reaction mechanism through insertion of CO2 into CuH to afford Cu/formate species.
Application of Functionalized N,S‐Ketene Acetals–Microwave‐Assisted Three‐Component Domino Reaction for Rapid Direct Access to Imidazo[1,2‐a]pyridines
Authors: Li Ming , Li Tengfei , Zhao Kelong , Wang Mingda , Wen Lirong
Published: June 2013

Imidazo[1,2‐a]pyridines have been successfully synthesized in moderate to good yields via a tandem three‐component reaction of ethyl 2‐(3‐oxo‐3‐arylpropanethioamido)acetates with aromatic aldehydes and malononitrile by means of microwave irradiation using DABCO as the catalyst. The advantages of this method including high chemo‐ and regioselectivity make this new strategy highly attractive.
A Long‐Wavelength Fluorescent Probe for Saccharides Based on Boronic‐Acid Receptor
Authors: Bai Hongyan , Sun Qian , Tian Haiyu , Qian Junhong , Zhang Lingyi , Zhang Weibing
Published: June 2013

A single boronic acid‐based fluorescent probe (compound CSP) for saccharides was designed and synthesized. The probe, with an α,β‐unsaturated ketone conjugated into the coumarin fluorophore, was synthesized by 4 steps from the commercial material 4‐diethylamino salicylaldehyde. The electron push‐pull effect is enhanced with the N,N‐diethyl amino as the electron donor and the carbonyl as the electron acceptor. Both the absorption (463 nm) and emission (616 nm) maxima of CSP are in the visible wavelength region with a Stokes shift of about 150 nm, which ensures CSP a potential probe for biological application. Under near physiological conditions, significant fluorescence enhancement of CSP was observed upon the addition of some saccharides, namely, D‐sorbitol, D‐fructose, D‐glucose, D‐mannose and D‐galactose. The probe showed relatively high sensitivity towards D‐fructose and D‐sorbitol, and their detection limits were 0.05 mmol/L and 0.1 mmol/L, respectively.
Transient analysis of the cooling process and influence of bottom insulation on the stress in the multicrystalline silicon ingot
Authors: Wang S. , Fang H. S. , Wei G. H. , Zhou L. , Zhou N. G.
Published: June 2013

Directional solidification is one of the most popular techniques for massive production of multicrystalline silicon. After growth and annealing, the ingot is cooled down by a designed cooling process, which is initialized by descending bottom insulation, and then is controlled both by power ramp‐down rate and by motion of the bottom insulation. Thermal stress is piled up during cooling, and associated crystal defects, such as dislocation and micro‐cracks, may generate and propagate in the ingot. In the paper, transient modeling is applied to study the effect of bottom insulation on the cooling process. Temperature, velocity and thermal stress fields are obtained with linear, parabolic and sinusoidal motions of the insulation. The measured and predicted temperatures at two points of the ingot are found consistent. Distributions of von Mises stress in the ingot at different cooling time are obtained, and the maximum von Mises stresses are presented as a function of the cooling time. Specifically, dislocation‐free regions, evaluated by the critical resolved shear stress model, at certain cooling time, and area fractions of the regions as a function of the cooling time are proposed. The linear motion is further discussed with different moving rates, considering its wide applications in the current industry and convenient realization in control.
Self‐Biasing Photoelectrochemical Cell for Spontaneous Overall Water Splitting under Visible‐Light Illumination
Authors: Chen Quanpeng , Li Jinhua , Li Xuejin , Huang Ke , Zhou Baoxue , Shangguan Wenfeng
Published: June 2013

A self‐biasing photoelectrochemical (PEC) cell that could work for spontaneous overall water splitting in a neutral solution was established based on the mismatched Fermi levels between the photoelectrodes. A Pt‐catalyst‐decorated crystalline silicon photovoltaic cell (Pt/PVC) was prepared and employed as an effective photocathode. This was coupled with a poly(ethylene glycol)‐directed WO3/W photoanode prepared by a hydrothermal process. Both of the photoelectrodes showed a response to visible light. The WO3/W photoanode had a positively located valence band edge, the energy level of which was enough for water oxidation, and the Pt/PVC photocathode possessed a negatively located conduction band edge, which was capable of water reduction. More importantly, the Fermi level of the WO3/W photoanode was more positive than that of the Pt/PVC photocathode because of the p–n junction of the PVC that decoupled the band bending and enlarged the photovoltage. Under visible‐light irradiation, the WO3/W photoanode provided a negative bias for the Pt/PVC photocathode, and the Pt/PVC photocathode provided a positive bias for the WO3/W photoanode. An interior bias was generated that could relax the strict criteria of overall water splitting by cooperatively separating the hole–electron pairs at both photoelectrodes. In this system, the short‐circuit current and the open‐circuit voltage increased with increasing light intensity (AM 1.5 illumination) to reach 121 μA cm−2 and 0.541 V, respectively, at a light intensity of 100 mW cm−2. Such a combination provides a promising method for the fabrication of self‐driven devices for solar‐energy storage.
Drosophila semaphorin2b is required for the axon guidance of a subset of embryonic neurons
Authors: Emerson Mark M. , Long Jennifer B. , Vactor David Van
Published: June 2013

COVER PHOTOGRAPH: Drosophila embryonic axons visualized for expression of Fasciclin II (red) and a transgene that marks sema‐phorin2b‐positive cells (green). semaphorin2b‐positive axons deviate from their normal Fasciclin II tracts in both the lateral and ventral direction in semaphorin2b mutants (upper right) compared to wildtype (upper left). From Drosophila semaphorin2b is Required for the Axon Guidance of a Subset of Embryonic Neurons, Mark M. Emerson, Jennifer B. Long, and David Van Vactor, Developmental Dynamics 242:861–873, 2013.
Deployment control of wireless multihop‐relay mobile robots based on voronoi partition
Authors: Imaizumi Takaaki , Murakami Hiroyuki , Uchimura Yutaka
Published: June 2013

This paper describes a new method for the deployment of wireless relay nodes. When using rescue robots in a building or underground city, radio signals are attenuated significantly, and therefore, multihop extension involving wireless communication relays is required. The goal of this research is to deploy wireless relay nodes to maintain connectivity between the base station and the leader robot that explores around the front line. To move the relay robot autonomously, a distributed algorithm is required.

The proposed method is suitable when it is applied for wireless relay purposes. In this method, a virtual force drives a node to the centroid of Voronoi neighbors so that the connectivity of wireless communication is maintained. The proposed method is evaluated by conducting numerical simulations and experiments. In the simulation, one or two leader robots are assumed. In the experiment, a mobile robot equipped with omni‐wheels is used. © 2013 Wiley Periodicals, Inc. Electr Eng Jpn, 184(4): 42–51, 2013; Published online in Wiley Online Library (wileyonlinelibrary.com). DOI 10.1002/eej.22413
The Quest for Cobalt‐Free Alkyd Paint Driers
Authors: de Boer Johannes W. , Wesenhagen Philana V. , Wenker Erica C. M. , Maaijen Karin , Gol Franjo , Gibbs Hugh , Hage Ronald
Published: June 2013

Paint formulations, based either on organic solvents or on water, often contain alkyd resins that depend on catalysts for their oxidative curing. Cobalt carboxylates are the most widely used to date, but the use of these compounds is under pressure because classification as carcinogens under the REACh system is probable, and as a consequence there is great interest in the development of alternative driers to cobalt‐based ones. A variety of manganese and iron carboxylates have been studied as paint drying catalysts in the last two decades, but these often show drawbacks with respect to activity, level of application, colour of the paint drier or cost in use. More recently, several reports on active manganese and iron paint driers containing polydentate ligands have been published. In particular, one iron‐based catalyst, identified originally for stain bleaching in laundry cleaning, shows good paint drying activity at very low dosage levels, outperforming cobalt carboxylates in a wide range of applications.
Metal‐Free Oxidative Carbon‐Heteroatom Bond Formation Through C–H Bond Functionalization
Authors: Samanta Rajarshi , Matcha Kiran , Antonchick Andrey P.
Published: June 2013

Direct methods of carbon‐heteroatom bond formation through functionalization of non‐reactive C–H bonds represent an attractive approach to the synthesis of interesting products. This review focuses on the development of metal‐free coupling methods for unactivated compounds under oxidative reaction conditions. The utility of these methods in syntheses of desired products and the mechanisms of their formation are discussed with numerous examples.
Synthesis of Highly Functionalized Enantiopure Halocyclopropanes Derived from Carbohydrates
Authors: Rodríguez‐Solla Humberto , Concellón Carmen , del Amo Vicente , Díaz‐Pardo Ainhoa , Blanco Elena G. , García‐Granda Santiago , Díaz M. Rosario , Llavona Ricardo , Soengas Raquel G.
Published: June 2013

A chromium‐mediated synthesis of enantiopure sugar‐based halocyclopropanecarboxamides is reported. This reaction can be stereospecifically carried out on (E)‐ or (Z)‐α,β‐unsaturated amides and takes place with the formation of a new C‐Hal stereogenic center, which is generated with total stereoselectivity. Synthetic applications of the obtained halocyclopropanecarboxamides are also reported. The structure of the halocyclopropanes and derivatives were established by X‐ray analysis. A mechanism to explain these transformations is proposed.
An Aerobic and Very Fast Pd/C‐Catalyzed Ligand‐Free and Aqueous Suzuki Reaction Under Mild Conditions
Authors: Liu Chun , Rao Xiaofeng , Zhang Yixia , Li Xinmin , Qiu Jieshan , Jin Zilin
Published: June 2013

An aerobic, ligand‐free Suzuki reaction catalyzed by Pd/C in aqueous media has been developed. This method is a very simple, efficient and mild protocol for the cross‐coupling of aryl bromides with arylboronic acids, and the reactions proceeded smoothly in excellent yields within short reaction times. Control experiments demonstrated that the Pd/C‐catalyzed Suzuki reaction was much quicker when performed in air or oxygen than in nitrogen. Furthermore, this protocol could be used for the synthesis of fluorinated liquid‐crystalline compounds. The Pd/C catalyst could be recovered and recycled efficiently at least ten times without significant loss of catalytic activity.
Metabolomics approaches for characterizing metabolic interactions between host and its commensal microbes
Authors: Xie Guoxiang , Zhang Shucha , Zheng Xiaojiao , Jia Wei
Published: June 2013

It is increasingly evident that the gut microbiota is involved in the regulation of multiple mammalian metabolic pathways through a series of interactive host‐microbiota metabolic, signaling, and immune‐inflammatory axes that physiologically connect the gut, liver, brain, and other organs. Correlation of the metabotypes with the gut microbial profiles derived from culture‐independent molecular techniques is increasingly useful for deciphering inherent and intimate host–microbe relationships. Real‐time analysis of the small molecule metabolites derived from gut microbial‐host co‐metabolism is essential for understanding the metabolic functions of the gut microbiome and has tremendous implications for personalized healthcare strategies. Metabolomics, an array of analytical techniques that includes high resolution NMR spectroscopy and chromatography‐MS in conjunction with chemometrics and bioinformatics tools, enables characterization of the metabolic footprints of mammalian hosts that correlate with the microbial community in the intestinal tract. The metabolomics approach provides important information of a complete spectrum of metabolites produced from the gut microbial‐mammalian co‐metabolism and is improving our understanding of the molecular mechanisms underlying multilevel host–microbe interactions. In this review, the interactions of gut microbiota with their host are discussed and some examples of NMR‐ or MS‐based metabolomics applications for characterizing the metabolic footprints of gut microbial‐host co‐metabolism are described. Advances in the metabolomic analysis of bile acids, short‐chain fatty acids, and choline metabolism are also summarized.
Evaluation of the oligosaccharide composition of commercial follicle stimulating hormone preparations
Authors: Lombardi Angela , Andreozzi Concetta , Pavone Vincenzo , Triglione Valeria , Angiolini Luca , Caccia Paolo
Published: June 2013

Glycosylation is an important PTM in proteins, and it is of paramount importance for the manufacture and efficacy of therapeutic glycoproteins. The elucidation of the glycosylation patterns is greatly hampered by the structural heterogeneity, which involves the oligosaccharide moieties, and sometimes also the protein chain. Several strategies are used to map the glycosylation state of glycoproteins: they generally involve analysis of the glycopeptides obtained upon glycoprotein proteolytic digestion, and/or analysis of the glycans, enzymatic or chemically released from the glycoproteins. These approaches are efficient in determining the total glycan content, as well as the glycan structures; nevertheless, information regarding the whole protein is lost. Recent advances in MS allowed us to directly analyze human follicle stimulating hormone (hFSH). RP‐HPLC/IT‐TOF MS, coupled to bioinformatic algorithms, was used to determine the glycan content of intact hFSH preparations, either urinary‐derived or recombinant. More traditional and complementary analytical methods (oligosaccharide profiling, IEF, and peptide mapping analyses) were employed to compare the obtained results. Our analysis shows a predominance of highly sialylated, highly branched glycans in a urinary hFSH preparation as compared to recombinant hFSH expressed in rodent cell lines. Noteworthy, high‐resolution mass spectra may allow to evaluate the glycosylation profile during the manufacturing process of different preparations.
Graphene nanoparticles as pseudostationary phase for the electrokinetic separation of nonsteroidal anti‐inflammatory drugs
Authors: Benítez‐Martínez Sandra , Simonet Bartolomé M. , Valcárcel Miguel
Published: June 2013

The exceptional properties of graphene (G) were exploited here to facilitate capillary electrokinetic separations. Two types of commercially available G consisting of nanoparticles containing—one to three and—four to six G sheets, respectively, were compared for this purpose. Both proved effective in separating the arylpropyl derivatives of nonsteroidal anti‐inflammatory drugs. The highest resolution and shortest migration times were obtained with G containing high amount of single and double G nanosheets. G affords higher resolution than other types of nanoparticles; stable suspensions can be easily prepared and used as BGE without the need of adding an additional surfactant. This results in a high reproducibility in migration times and stability in background noise. The LOD and LOQ obtained by using G nanoparticles as pseudostationary phases spanned the range 0.29–1.18 mg/L and 0.95–3.95 mg/L, respectively, and the RSD was less than 4.7% in all instances.
Two‐dimensional modelling of large wood transport during flash floods
Authors: Ruiz Villanueva Virginia , Bladé Castellet Ernest , Díez‐Herrero Andrés , Bodoque José M. , Sánchez‐Juny Martí
Published: June 2013

Large woody material (LWM) transported by rivers may be entrapped at critical stream geometry configurations (e.g. bridges) and therefore dramatically increase the destructive power of floods. This was the case in a Spanish mountain river where a flood event with a high degree of LWM transport took place in 1997. The aim of this study was to simulate a bridge clogging process and reconstruct the wood deposit patterns, modelling individual pieces of wood moving with the water flow and interacting among them and with the bridge. A two‐dimensional numerical model was developed to simulate the transport of LWM and its effect on hydrodynamics. Different scenarios for the wood transport rate allowed us to study the influence of inlet boundary conditions on bridge clogging. For the studied event, the scenario which best reproduced the bridge clogging effect and flood characteristics was one in which 60% of the total wood entered before the peak discharge. This dropped to 30% at the peak itself, and finally fell to 10% during the recession curve. In addition, the accumulation patterns of LWM along the reach were computed and compared with post‐event field photographs, showing that the model succeeded in predicting the deposition patterns of wood and those areas prone to form wood jams. Copyright © 2013 John Wiley & Sons, Ltd.
Alleviation of chromium toxicity by hydrogen sulfide in barley
Authors: Ali Shafaqat , Farooq Muhammad Ahsan , Hussain Sabir , Yasmeen Tahira , Abbasi G.H. , Zhang Guoping
Published: June 2013

A hydroponic experiment was carried out to examine the effect of hydrogen sulfide (H2S) in alleviating chromium (Cr) stress in barley. A 2-factorial design with 6 replications was selected, including 3 levels of NaHS (0 μM, 100 μM, and 200 μM) and 2 levels of Cr (0 μM and 100 μM) as treatments. The results showed that NaHS addition enhances plant growth and photosynthesis slightly compared with the control. Moreover, NaHS alleviated the inhibition in plant growth and photosynthesis by Cr stress. Higher levels of NaHS exhibited more pronounced effects in reducing Cr concentrations in roots, shoots, and leaves. Ultrastructural examination of plant cells supported the facts by indication of visible alleviation of cell disorders in both root and leaf with exogenous application of NaHS. An increased number of plastoglobuli, disintegration, and disappearance of thylakoid membranes and starch granules were visualized inside the chloroplast of Cr-stressed plants. Starch accumulation in the chloroplasts was also noticed in the Cr-treated cells, with the effect being much less in Cr + NaHS-treated plants. Hence, it is concluded that H2S produced from NaHS can improve plant tolerance under Cr stress. Environ Toxicol Chem 2013;32:2234–2239. © 2013 SETAC