bluuebunny/crossref_metadata_2025 huggingface dataset:
A novel diacetylenic bilirubin
Authors: Tu Bilirubin Bin , Lightner David A.
Published: March 2009

An etiobilirubin‐IIβ analog with the central C(10) CH2 group replaced by a diacetylene unit (1) was synthesized by base‐catalyzed condensation of bis‐[3‐methyl‐4‐ethyl‐5‐formylpyrrol‐2‐yl]‐diacetylene (3) with 3‐methyl‐4‐ethyl‐5‐p‐toluenesulfonyl‐2‐pyrrolinone (10). Diacetylenic rubin 1 is a dark red solid, giving orange solutions with uv‐visible absorption maxima near 460 nm.
Palladium‐catalyzed amination with benzophenone imine as a new, safe and practical alternative to nitration for the synthesis of 7‐amino‐2,1,3‐benzothiadiazoles
Authors: Liu Yugang , Prashad Mahavir , Repič Oljan , Blacklock Thomas J.
Published: March 2009

Palladium‐catalyzed amination of 7‐bromo‐4‐methyl‐2,1,3‐benzothiadiazole (7) with benzophenone imine as an ammonia equivalent is described as a new, safe and practical alternative to nitration for the synthesis of 7‐amino‐4‐methyl‐2,1,3‐benzothiadiazole (1) in high yield. This methodology was successfully scaled‐up in the pilot plant on 14.0‐kg scale of 7 and was also utilized for the synthesis of 7‐amino‐4,6‐dimethyl‐2,1,3‐ben‐zothiadiazole (12) by the amination of 7‐bromo‐4,6‐dimethyl‐2,1,3‐benzothiadiazole (10).
Asymmetric conjugate addition reaction using pyrazole derivatives as a chiral catalyst
Authors: Kashima Choji , Yokoyama Hiroyo , Shibata Saori , Fujisawa Kiyoshi , Nishio Takehiko
Published: March 2009

The conjugate addition of Grignard reagent (2) onto 1‐α,β‐unsaturated)acyl 3,5‐dimethylpyrazole (1) was enantioselectively catalyzed by the copper complex from cuprous compounds and 3‐phenyl‐l‐mentho‐pyrazole (3).
Synthesis of some furo‐thiazolidine derivatives starting from aldimines
Authors: Öcal Niiket , Aydoǧan Feray , Yolaçan Çiǧdem , Turgut Zuhal
Published: March 2009

Alkyl and aryl substituted furothiazolidine derivatives have been synthesized by the reaction of Wittig reagent with benzylidene derivatives of 4‐thiazolidinones obtained from aldimines and thioglicolic acid.
Micowave assisted synthesis of benzo‐substituted macrocyclic diamides and their corresponding macrocyclic dithiodiamides
Authors: Elwahy Ahmed H. M. , Masaret Ghada S.
Published: March 2009

A synthesis of a series of macrocyclic diamides 3 in good yields by reacting the corresponding bis phenols 4 with the appropriate dihalo alkanes 6 either in solvent or in dry media under microwave irradiation. Thiation of 3 with P2S5 or Lawesson's reagent in solvent free conditions under microwave irradiation is also described.
One pot diastereoselective synthesis of new chiral spiro‐1,3,4‐thiadiazoles and 1,4,2‐oxathiazoles from (1R)‐thiocamphor
Authors: Feddouli Amal , Itto Moulay Youssef Ait , Hasnaoui Aïssa , Villemin Didier , Jaffrès Paul‐Alain , Santos Jana Sopkova‐De Oliveira , Riahi Abdelkhalek , Huet FranÇOis , Daran Jean‐Claude
Published: March 2009

Herein we report an efficient one pot synthesis of new chiral 4,5‐dihydro‐4‐arylspiro[1,3,4‐thiadiazole]‐5,2′‐camphane‐2‐carboxylic acid ethyl esters 5–7 and 4,5‐dihydro‐3‐arylspiro[1,4,2‐oxathiazole]‐5,2′‐camphane 11–13, using 1,3‐dipolar cycloaddition of nitrilimines 2–4 and nitrile oxides 8–10 to (1R)‐thiocamphor 1 respectively. The structure of the newly prepared 1,3,4‐thiadiazoles 5–7 (obtained as pure diastereoisomers) were fully established via spectroscopic analysis and X‐ray structural analysis which proved the absolute configuration of the C5 spiranic carbon to be (R). NMR spectral analysis were also very useful to show the new 1,4,2‐oxathiazoles 11–13 are mixtures of two (5R)/(5S) diastereoisomers with the ratio 6:4,7:3 and 6:4 respectively.
Structural characterization of isomeric 2,3,5‐substituted tetrahydropyrrolo[3,4‐d]isoxazole‐4,6‐diones prepared by cycloaddition of N‐methyl‐C‐arylnitrones to N‐phenyl‐ or N‐methylmaleimide
Authors: Pihlaja Kalevi , Tähtinen Petri , Shaikhutdinov Roustem , Hartikainen Heli , Ovcharenko Vladimir , Agirbas Hikmet , Güner Selahaddin
Published: March 2009

1,3‐Dipolar cycloaddition reactions of N‐methyl‐C‐arylnitrones with N‐phenyl‐ or N‐methylmaleimide were studied. The reaction of p‐dimethylamino‐, 4‐benzyloxy‐3‐methoxy‐, p‐nitro‐ and p‐chloro‐substituted phenylnitrones with N‐phenylmaleimide gave cis and trans cycloadducts but that of the corresponding phenylnitrones with N‐methylmaleimides only the cis adducts in the case of p‐dimethylamino and 4‐benzyloxy‐3‐methoxy substitution. All cis adducts attain a biased conformation whereas the trans forms are shown (by 1H NMR at 233 K and 13C NMR at 208 K) to be mixtures of two invertomers, namely o‐(N‐lone pair antiperiplanar to 3H; minor) and i‐conformations (3H‐C‐C‐3aH dihedral angle close to 90°; major). PM3 and DFT calculations at the B3LYP/6–31G(d) level of theory prove qualitatively that these two conformers of the trans adduct are of comparable stability and represent energy minima.
On the reactivity of isoxazoles with Mo(CO)6
Authors: Donati Donato , Ferrini Serena , Fusi Stefania , Ponticelli Fabio
Published: March 2009

Ring opening with molybdenum hexacarbonyl of functionalized isoxazoles is a valuable synthetic process. Tetrazolopyridine 4 and pyrazolopyridine 9 were obtained from isoxazolopyridines 3 and 6, respectively, whereas the isoxazole 14 gave ketone 16 through the intermediate 17.
Synthesis and characterization of 2‐iminoperhydro‐1,3‐selenazin‐4‐ones by reaction of N,N'‐disubstituted selenoureas with acryloyl chloride
Authors: Koketsu Mamoru , Taura Masayasu , Ishihara Hideharu
Published: March 2009

2‐Iminoperhydro‐1,3‐selenazin‐4‐ones were synthesized by the reaction of N,N'‐disubstituted selenoureas with acryloyl chloride.
Synthesis and antifolate activity of new pyrrolo[2,3‐d]pyrimidine and thieno[2,3‐d]pyrimidine inhibitors of dihydrofolate reductase
Authors: Vaidya Chitra , Wright Joel E. , Rosowsky Andre
Published: March 2009

Three previously undescribed dihydrofolate reductase (DHFR) inhibitors, Nα‐[4‐[N‐[(2,4‐diaminopyrrolo[2,3‐d]pyrimidin‐5‐yl)methyl]amino]benzoyl]‐Nδ‐hemiphthaloyl‐L‐ornithine (7), Nα‐ [4‐ [N‐[(2,4‐diaminothieno[2,3‐d]pyrimidin‐5‐yl)methyl]amino]benzoyl]‐ Nδ‐hemiphthaloyl‐L‐ornithine (8), and N‐[4‐[N‐[(2,4‐diaminothieno[2,3‐d]pyrimidin‐5‐yl)methyl]amino]benzoyl]‐L‐glutamic acid (12), were synthesized and their antifolate activity was assessed. The ability of 7 and 8 to bind to DHFR and inhibit the growth of CCRF‐CEM human lymphoblastic leukemia cells in culture were dramatically reduced in comparison with the corresponding pteridine analogue, Nα‐(4‐amino‐4‐deoxypteroyl)‐Nδ‐hemiphmaloyl‐L‐ornithine (1, PT523). In a similar manner, the antifolate activity of 12 was markedly reduced in comparison with that of the corresponding glutamate analogue, aminopterin (5, AMT). In contrast, 7, 8, and 12 all displayed excellent affinity for the reduced folate carrier (RFC) of CCRF‐CEM cells as measured by a standard competitive influx assay. Lack of a consistent correlation between the results of the growth inhibition assays and those of the DHFR and RFC binding assays results suggest that additional factors also play a role in the antifolate activity of these compounds.
Synthesis of 2,9‐diacyl‐1, 10‐phenanthrolines
Authors: Paul Krapcho A. , Ali Akbar
Published: March 2009

A convenient high yield synthetic route leading to 2,9‐diacyl‐1,10‐phenanthrolines has been developed. The reaction of bis‐amide 1 with 2‐pyridyllithium, 6‐bromo‐2‐pyridyllithium or 2‐thienyllithium led to the diacyl compounds 5,6 and 7, respectively. Attempts to prepare 8 by intramolecular coupling of 6 or by treatment of 1 with dilithio analogue 9b were unsuccessful. Treatment of 1 with butyllithium or aryllithium reagents led to 10a, 10b and 10c.
Microclimate modelling of street tree species effects within the varied urban morphology in the Mediterranean city of Tel Aviv, Israel
Authors: Shashua‐Bar Limor , Potchter Oded , Bitan Arieh , Boltansky Dalia , Yaakov Yaron
Published: March 2009

Microclimate formation and its significance in urban planning was examined through two components that predominate in affecting the city's climate: built‐up morphology and urban shade trees.

The methodological approach focus is on a generalization procedure for quantifying the thermal effect of any studied situation through parameterization of the vegetated variables and the built‐up forms. The analysis is integrative, using empirical climatic data followed by an analytical study for generalization and sensitivity analysis using an integrative model, the Green CTTC model.

Three urban tree species predominant in the Tel Aviv gardens and streets, with different canopy characteristics, and three levels of building densities were analysed to determine their thermal effect on an urban street microclimate. The variables were parameterized according to six basic cooling attributes for the studied tree species in urban gardens in Tel Aviv, and according to three geometric built‐up parameters for the studied urban street.

The integrative modelling approach of considering all changes simultaneously was illustrated on an urban boulevard in Tel Aviv. The analysis demonstrates the shortcomings of piecemeal modelling and the merits of the integrative approach.

The study indicates the importance of urban trees in alleviating the heat island effect in a hot and humid summer. The tree cooling effect was found to be strongly related to the built form geometry. In all the studied cases, the thermal effect of the tree was found to depend mainly on its canopy coverage level and planting density in the urban street and little on other species characteristics.

The methodology of analysis presented in this paper can be applied to develop an operational tool in assessing for an urban open space the integrative thermal effects of different tree species, and of the varied urban morphology and the interaction between them. Copyright © 2009 Royal Meteorological Society
The effects of a seaweed extract in addition to nitrogen and boron fertilization on productivity, fruit maturation, leaf nutritional status and oil quality of the olive (Olea europaea L.) cultivar Koroneiki
Authors: Chouliaras Vassilios , Tasioula Maria , Chatzissavvidis Christos , Therios Ioannis , Tsabolatidou Eleftheria
Published: March 2009

BACKGROUND: There is not adequate literature on effects of seaweed extracts (SWE) on yield and nutritional status of olive trees as well as olive oil quality. In this work, a study of the effects of a seaweed extract applied foliarly (0.5% v/v) in addition to soil application of N (500 g NH4NO3 per tree) and B (150 g borax per tree) on productivity, fruit parameters, nutritional status and olive oil quality of a Greek olive cultivar was performed.

RESULTS: In contrast to the trees treated with N (NH4NO3) or N + B (NH4NO3 + borax), the additional application of seaweed extract (treatments N + SWE and N + B orax + SWE) increased the productivity and oil content and accelerated maturation of the olive fruits. In particular, the best results concerning productivity, oil content and earliness of maturity (colour and firmness) were observed in the trees treated with N + B + SWE. The additional application of SWE also increased K, Fe and Cu concentrations and reduced the concentrations of Mn in olive leaves compared to the corresponding treatments without SWE. Total phenol concentration in oil was minimized in all fertilization treatments but, particularly, the additional application of SWE did not affect it. The application of N + B + SWE led to a significant increase in linolenic as well as oleic acid concentrations, and to a decline in palmitoleic, stearic and linoleic acid concentrations in olive oil.

CONCLUSION: The fertilizer treatments of this experiment and especially the combination of NH4NO3 + borax + SWE should be recommended for the studied olive orchards, in order to increase tree productivity and improve their nutrition status and various olive oil quality parameters. Copyright © 2009 Society of Chemical Industry
Qualitative changes in Pleurotus ostreatus (Jacq.: Fr.) Kumm. mushrooms resulting from different methods of preliminary processing and periods of frozen storage
Authors: Jaworska Grażyna , Bernaś Emilia
Published: March 2009

BACKGROUND: The aim of this study was to investigate the effect of different methods of preliminary processing and periods of frozen storage on the quality of Pleurotus ostreatus (Jacq.: Fr.) Kumm. mushrooms. In pre‐processing, mushrooms were blanched or soaked and blanched in water as well as in aqueous solutions of citric acid, L‐ascorbic acid and/or lactic acid. During 12 months of storage at −25 °C, sensory evaluations, instrumental colour measurements and chemical analyses of the frozen products were carried out every 4 months.

RESULTS: The greatest changes resulting from technological treatment were found in flavour. At the end of the storage period the content of thiamine and riboflavin decreased by 14–65% and 3–13% respectively compared with the raw material. This was accompanied by changes in total acidity and vitamin C content within the ranges − 56 to + 61% and − 97 to + 5% respectively.

CONCLUSION: Based on the results of the sensory evaluation, a maximum storage period of 4 months was set for the frozen product obtained from unblanched mushrooms. Mushroom products pre‐processed in aqueous solutions with added substances may be stored for 8 months and those blanched in water for 12 months. Copyright © 2009 Society of Chemical Industry
Finding social benefits after a collective trauma: Perceiving societal changes and well‐being following 9/11
Authors: Poulin Michael J. , Silver Roxane Cohen , Gil‐Rivas Virginia , Holman E. Alison , McIntosh Daniel N.
Published: March 2009

Individuals frequently perceive positive changes in themselves following adversity; after a collective trauma, they may perceive such benefits in others or in their society as well. We examined perceived benefits of the September 11, 2001 (9/11) terrorist attacks in a 3‐year study of a national sample of adults (N = 1382). Many individuals (57.8%) perceived social benefits of 9/11, including increased prosocial behavior, religiousness, or political engagement. Individuals who found increased national religiosity as a benefit 2 months post‐9/11 reported greater positive affect and life satisfaction and lower distress and posttraumatic stress up to 3 years post‐9/11. Pre‐9/11 religiousness and Republican political affiliation predicted perceiving religion‐related social benefits post‐9/11. Perceptions of social change are important but understudied responses to stressful events.
Posttraumatic anger in crime victims: Directed at the perpetrator and at the self
Authors: Orth Ulrich , Maercker Andreas
Published: March 2009

This study investigated the targets of anger that are most strongly involved in posttraumatic anger. Using a sample of 218 crime victims, the authors assessed the levels of anger at potential targets (perpetrator, criminal justice system, third persons, and the self) and their association with severity of posttraumatic stress disorder (PTSD) symptoms. The results revealed that anger was most strongly directed at the perpetrator and at the self, and that anger at other targets was low. Moreover, anger at the perpetrator and at the self showed strong associations with PTSD symptoms, whereas the associations of anger at other targets with PTSD symptoms were low.
Multivariate analyses and spatial distribution of Manganese minerals in soils close to an abandoned Manganese mine
Authors: Ekosse G.‐I. E.
Published: March 2009

Four hundred soil samples were obtained from a 4 km2area close to the abandoned Kgwakgwe Mn oxide ore mine in order to investigate the environmental association of Mn minerals and concentrations in the soils. Manganese minerals and Mn concentrations in samples were identified by X‐ray diffractometry and atomic absorption spectrometry, respectively, and results statistically analysed. Bixbyte, Mn2O3; braunite, Mn+2MnSiO12; ramsdellite, MnO2; pyrolusite,β‐MnO2and cryptomelane, K2 − xMn8O16were identified in soil samples at the study site but none of these minerals found in soil samples from the control site. Manganese concentrations in samples from the study area were significantly higher than those from the control site. Statistical data yielded seven clusters with distribution of the Mn minerals and concentrations as follows: cluster 1 dominated by Mn concentrations in soil, cluster 2 by none of the seven Mn minerals, cluster 3 by pyrolusite, cluster 4 by braunite, cluster 5 by cryptomelane, cluster 6 by bixbyite and cluster 7 by ramsdellite. Very weak associations of these minerals were depicted from their correlations. The clusters had a bearing on the spatial distribution of the different minerals. Comparing results obtained from the control site, and geological materials, to the soils from the study area, it is certain that Mn minerals and high Mn concentrations in soils originated from the surrounding geological materials. The mining activities most possibly have affected Mn concentrations' and minerals' occurrences in the soils at the study area. Copyright © 2009 John Wiley & Sons, Ltd.
Benefits and value of meteorological information services—the case of the Finnish Meteorological Institute
Authors: Leviäkangas Pekka , Hautala Raine
Published: March 2009

The benefits of meteorological information services have been widely studied, but a coherent view of the impacts of these services remains elusive. Meteorological information services must be seen primarily to have potential positive impacts on the functions of society: only in that light will their true worth emerge. This paper looks at the value of the services for society as a whole. In addition to their methodological contribution to the value assessment of meteorological services in general, the services of the Finnish Meteorological Institute represent an empirical case. Evidently the value of information is set to play an increasing role as societies grow increasingly information intensive. The results of the empirical case were explicit. The total value of benefits generated each year by the Institute's services exceeded the annual budget of the Institute many times over. Copyright © 2009 Royal Meteorological Society
Direct detection of alkylphosphonic acids in environmental matrices by proton coupled phosphorus NMR
Authors: Sharma Mamta , Gupta A. K. , Mewar Sujeet , Beldar Anil , Suryanarayana M. V. S. , Raza S. K.
Published: March 2009

A simple, convenient, and direct one‐dimensional (1D) 31P NMR technique is demonstrated for the detection of alkylphosphonic acids (marker of nerve agents). The results of detection were validated after conducting various in‐house exercises. The confidence generated by this study was found very useful in detection of different alkylphosphonic acids spiked in various official interlaboratory proficiency tests conducted by Organisation for the Prohibition of Chemical Weapons (OPCW). Copyright © 2009 John Wiley & Sons, Ltd.
Suppression of reflex urethral responses by sacral dermatome stimulation in an acute spinalized feline model
Authors: Mariano Timothy Y. , Bhadra Narendra , Gustafson Kenneth J.
Published: March 2009

Aims

Reflex contractions of the external urethral sphincter (EUS) are a major component of voiding dysfunction after neurological injury or disease. Aberrant urethral reflexes can prevent voiding and cause serious medical complications. Characterizing these urethral reflexes during genitourinary studies is necessary for evaluating novel pharmacological or neuroprosthetic approaches. The objectives of the present study were to generate urethral reflexes in the acute spinal feline, to quantify these reflexes, and to suppress them with electrical stimulation of the sacral dermatomes.

Methods

This study comprised eight male cats. Anaesthesia was maintained with alpha‐chloralose or sodium pentobarbital. The spinal cord was transected between T10 and T12, and nerve cuff electrodes were placed on the extradural S2 sacral roots to provide bladder activation. Bladder and urethral pressures were recorded during and after bladder contractions. Electrical stimulation was applied non‐invasively to the sacral dermatomes with commercial surface electrodes.

Results

Urethral reflexes were elicited consistently in six cats. The corresponding urethral pressure spikes were quantified. Putative metrics of urethral reflex activity such as the rate and average magnitude of reflex pressure spikes correlated significantly with standard urodynamic variables. Electrical stimulation of the sacral dermatomes suppressed urethral reflexes in three cats.

Conclusions

These findings in an acute spinal feline preparation demonstrate a non‐invasive means of suppressing undesirable urethral reflexes. Translation of this work to clinical use could improve neuroprostheses for restoring bladder function and enhance treatment of aberrant urethral reflexes in humans. Neurourol. Urodynam. 29:494–500, 2010. © 2009 Wiley‐Liss, Inc.
Convergence analysis of a balancing domain decomposition method for solving a class of indefinite linear systems
Authors: Li Jing , Tu Xuemin
Published: March 2009

A variant of balancing domain decomposition method by constraints (BDDC) is proposed for solving a class of indefinite systems of linear equations of the form (K−σ2M)u=f, which arise from solving eigenvalue problems when an inverse shifted method is used and also from the finite element discretization of Helmholtz equations. Here, both K and M are symmetric positive definite. The proposed BDDC method is closely related to the previous dual–primal finite element tearing and interconnecting method (FETI‐DP) for solving this type of problems (Appl. Numer. Math. 2005; 54:150–166), where a coarse level problem containing certain free‐space solutions of the inherent homogeneous partial differential equation is used in the algorithm to accelerate the convergence. Under the condition that the diameters of the subdomains are small enough, the convergence rate of the proposed algorithm is established, which depends polylogarithmically on the dimension of the individual subdomain problems and which improves with a decrease of the subdomain diameters. These results are supported by numerical experiments of solving a two‐dimensional problem. Copyright © 2009 John Wiley & Sons, Ltd.
Energy‐minimizing coarse spaces for two‐level Schwarz methods for multiscale PDEs
Authors: Van lent Jan , Scheichl Robert , Graham Ivan G.
Published: March 2009

Two‐level overlapping Schwarz methods for elliptic partial differential equations combine local solves on overlapping domains with a global solve of a coarse approximation of the original problem. To obtain robust methods for equations with highly varying coefficients, it is important to carefully choose the coarse approximation. Recent theoretical results by the authors have shown that bases for such robust coarse spaces should be constructed such that the energy of the basis functions is minimized. We give a simple derivation of a method that finds such a minimum energy basis using one local solve per coarse space basis function and one global solve to enforce a partition of unity constraint. Although this global solve may seem prohibitively expensive, we demonstrate that a one‐level overlapping Schwarz method is an effective and scalable preconditioner and we show that such a preconditioner can be implemented efficiently using the Sherman–Morrison–Woodbury formula. The result is an elegant, scalable, algebraic method for constructing a robust coarse space given only the supports of the coarse space basis functions. Numerical experiments on a simple two‐dimensional model problem with a variety of binary and multiscale coefficients confirm this. Numerical experiments also show that, when used in a two‐level preconditioner, the energy‐minimizing coarse space gives better results than other coarse space constructions, such as the multiscale finite element approach. Copyright © 2009 John Wiley & Sons, Ltd.
On the essence and the evaluation of the shape functions for the smoothed finite element method (SFEM)
Authors: Liu G. R. , Nguyen‐Thoi T. , Nguyen‐Xuan H. , Dai K. Y. , Lam K. Y.
Published: March 2009

This paper is written in response to the recently published paper (Int. J. Numer. Meth. Engng 2008; 76:1285–1295) at IJNME entitled ‘On the smoothed finite element method’ (SFEM) by Zhang HH, Liu SJ, Li LX.

In this paper we

repeat briefly the important essence of the original SFEM presented in (Comp. Mech. 2007; 39: 859–877; Int. J. Numer. Meth. Engng 2007; 71:902–930; Int. J. Numer. Meth. Engng 2008; 74:175–208; Finite Elem. Anal. Des. 2007; 43:847–860; J. Sound Vib. 2007; 301:803–820), and

examine further issues in the evaluation of the shape functions used in the SFEM.

It will be shown that the ‘SFEM’ presented in paper (Int. J. Numer. Meth. Engng 2008; 76:1285–1295) is not at all our original SFEM presented in (Comp. Mech. 2007; 39:859–877; Int. J. Numer. Meth. Engng 2007; 71:902–930; Int. J. Numer. Meth. Engng 2008; 74:175–208; Finite Elem. Anal. Des. 2007; 43:847–860; J. Sound Vib. 2007; 301:803–820). Therefore, all these ‘Theorems’, ‘Corollaries’ and ‘Remarks’ presented in paper (Int. J. Numer. Meth. Engng 2008; 76:1285–1295) have nothing to do with our original SFEM. The properties of the original SFEM stand as they were presented in our original papers (Comp. Mech. 2007; 39:859–877; Int. J. Numer. Meth. Engng 2007; 71:902–930; Int. J. Numer. Meth. Engng 2008; 74:175–208; Finite Elem. Anal. Des. 2007; 43:847–860; J. Sound Vib. 2007; 301:803–820). Finally, we brief on our advancements made far beyond our original SFEM and our visions on future numerical methods. Copyright © 2009 John Wiley & Sons, Ltd.
Development of core‐shell structure aided by SiC‐coated MWNT in ABS/LCP blend
Authors: Bose S. , Mukherjee M. , Pal K. , Nayak G. C. , Das C. K.
Published: March 2009

Agglomeration is an issue of major concern for unmodified multi‐walled carbon nanotubes (MWNTs)‐aided polymeric composites. To overcome the above‐mentioned problem, multi‐walled carbon nanotubes (MWNTs) are modified by polycarbosilane (PCS)‐derived Silicone carbide (SiC). Acrylonitrile Butadiene Styrene (ABS)/Liquid Crystalline polymer (LCP)/MWCNT nanocomposites are prepared through melt blending in a twin screw extruder. X‐Ray Diffraction (XRD) studies authenticate the creation of ß‐SiC particles. Field Emission Scanning Electron Microscopy (FESEM) and Transmission Electron Microscopy (TEM) studies reveal the formation of core–shell morphology involving MWNT as the core and SiC‐coated MWNT as the shell. The degree of dispersion of MWNT is far better when it has been coated with SiC. As viewed from Thermo‐gravimetric analysis (TGA), the thermal stability is substantially increased in SiC‐aided nanocomposite in comparison to ABS/LCP/unmodified CNT blend. Glass transition temperature as well as mechanical properties are improved significantly (in the presence of SiC‐coated MWNT) as a result of homogeneous dispersion exhibited by MWNT. Copyright © 2009 John Wiley & Sons, Ltd.
Incipient bubble formation during bulk polymerization of methyl methacrylate under near‐isothermal conditions using a ribbon agitator
Authors: Singh Gurpreet J. , Gupta Santosh K.
Published: March 2009

The polymerization of methyl methacrylate (MMA) is carried out under near‐isothermal conditions in a 1‐liter stainless steel stirred batch reactor with a glass bottom. A ribbon agitator is used to study the incipient stable‐bubble formation point, Bi, during the bulk polymerization of MMA. A camcorder has been used to get images of the bubbles from the beginning of the polymerization till just beyond the incipient stable‐bubble formation point. Experimental data on the monomer conversion, xm,Bi, the weight average molecular weight, Mw,Bi, and the viscosity, ηBi, of the reaction mass have been generated at this important point. Data have been taken at several values of the (near‐isothermal) temperature, initiator loading, reactor pressure, and the RPM of the ribbon stirrer. No significant effect of pressure and the RPM of the stirrer were observed over the ranges of these variables studied. Correlations have been developed for xm,Bi, Mw,Bi, and ηBi, relating these to the initiator loading and the temperature. POLYM. ENG. SCI., 2009. © 2009 Society of Plastics Engineers
Preparation, characterization, and physical properties of multiwall carbon nanotube/elastomer composites
Authors: Perez Leon D. , Zuluaga Manuel A. , Kyu Thein , Mark James E. , Lopez Betty L.
Published: March 2009

The present article describes preparation, characterization, and physical properties of nanoparticles‐filled composites consisting of multiwall carbon nanotubes (MWCNT) and styrene‐butadiene rubber and nitrile‐ butadiene rubber. The reinforcing MWCNT fillers were synthesized by chemical vapor deposition on iron and cobalt catalysts supported by calcium carbonate substrates. These MWCNT were further treated with nitric acid to produce hydroxyl and carbonyl functional groups on the carbon nanotubes (CNT) surfaces. Of particular importance is that these functionalized CNTs were found to exert profound influence on the elastomeric matrices, particularly the vulcanization activation energy, resistance to solvent swelling, enhanced glass transition temperature, and improved storage and loss moduli. POLYM. ENG. SCI., 2009. © 2009 Society of Plastics Engineers
Frequency‐dependent resistivity and magnetoresistivity of iodine doped conducting polyaniline
Authors: Chakraborty G. , Sarkar A. , Ghosh P. , Meikap A.K. , Chowdhury P.
Published: March 2009

The electrical transport properties of hydroiodic acid doped polyaniline in the temperature range 77 ≤ T ≤ 300 K were studied. The magnetic field strength was varied to a maximum of 1T in the frequency range of 20 Hz–1 MHz. The ac conductivity followed the universal dielectric response σ′(f) ∞ fs. The trend in the variation of ‘s’, the temperature dependence of the frequency exponent, indicated that correlated barrier hopping is the dominating charge transport mechanism. The ac conductivity also shows a positive variation with magnetic field, which can be interpreted by Maxwell‐Wagner capacitor model. POLYM. ENG. SCI., 2009. © 2009 Society of Plastics Engineers
Ex‐ante environmental and economic evaluation of polymer photovoltaics
Authors: Roes A. L. , Alsema E. A. , Blok K. , Patel M. K.
Published: March 2009

The use of polymer materials for photovoltaic applications is expected to have several advantages over current crystalline silicon technology. In this paper, we perform an environmental and economic assessment of polymer‐based thin film modules with a glass substrate and modules with a flexible substrate and we compare our results with literature data for multicrystalline (mc‐) silicon photovoltaics and other types of PV. The functional unit of this study is ‘25 years of electricity production by PV systems with a power of 1 watt‐peak (Wp)’. Because the lifetime of polymer photovoltaics is at present much lower than of mc‐silicon photovoltaics, we first compared the PV cells per watt‐peak and next determined the minimum required lifetime of polymer PV to arrive at the same environmental impacts as mc‐silicon PV. We found that per watt‐peak of output power, the environmental impacts compared to mc‐silicon are 20–60% lower for polymer PV systems with glass substrate and 80–95% lower for polymer PV with PET as substrate (flexible modules). Also in comparison with thin film CuInSe and thin film silicon, the impacts of polymer modules, per watt‐peak, appeared to be lower. The costs per watt‐peak of polymer PV modules with glass substrate are approximately 20% higher compared to mc‐silicon photovoltaics. However, taking into account uncertainties, this might be an overestimation. For flexible modules, no cost data were available. If the efficiency and lifetime of polymer PV modules increases, both glass‐based and flexible polymer PV could become an environment friendly and cheap alternative to mc‐silicon PV. Copyright © 2009 John Wiley & Sons, Ltd.
Ring‐banded spherulites in PCL and PCL/MWCNT solution‐casting films and effect of compressed CO2 on them
Authors: Hua Chengwu , Chen Zhimin , Xu Qun , He Linghao
Published: March 2009

The ring‐banded spherulites in poly(ε‐caprolactone) (PCL) solution‐casting films in the absence and presence of multi‐walled carbon nanotube (MWCNT) are studied by atomic force microscopy (AFM), polarized optical microscopy (POM), transmission electron microscopy (TEM), and scanning electronic microscopy (SEM). The results indicate that birefringent ring‐banded spherulites of PCL can grow from solution below 50 °C, and the temperature is much lower than that from pure PCL melt. We also find out that the presence of MWCNT apparently widen the temperature range of forming ring‐banded structure. Furthermore, the mechanism for the ring‐banded structure forming is studied, and it is attributed to the twisting of lamellae crystals, and the driving force is suggested including the deflexion of lamellae bundles. In addition, effect of compressed CO2 on the morphology of PCL and PCL/MWCNT solution‐casting film is also investigated, and the results reveal that both PCL and PCL/MWCNT films undergo recrystallization with the treatment of compressed CO2 and accordingly, the related properties can be adjusted. © 2009 Wiley Periodicals, Inc. J Polym Sci Part B: Polym Phys 47: 784–792, 2009
The solidification behavior of a PBT/PET blend over a wide range of cooling rate
Authors: Stocco Antonio , La Carrubba Vincenzo , Piccarolo Stefano , Brucato Valerio
Published: March 2009

In recent years, much attention has been paid to the development of high‐performance polyester blends, among which blends of polybutylene terephthalate/polyethylene terephthalate (PBT/PET) are expected to exhibit remarkable properties as far as their crystallization behavior is concerned. Through trial and error, appropriate commercial compositions have been chosen which could not be otherwise explained by a suitable interpretation of the mechanisms determining their solidification behavior. The solidification behavior of a 60/40 w/w PBT/PET blend was studied in a wide range of cooling conditions, according to a continuous cooling transformation (CCT) procedure developed previously, aiming at emulating the typical conditions encountered in polymer processing. Several samples characterized by a homogeneous structure were solidified from the melt at various cooling rates and the resulting structure and properties were subsequently evaluated by analyzing the density, microhardness (MH), and wide angle x‐ray diffraction (WAXD). The resulting solidification behavior was then compared to that exhibited by the individual constituents of the blend (i.e., PBT and PET). The blend displayed a unique solidification behavior, conversely to those of the pure components which showed characteristics not recognized in the blend except at certain restricted cooling rates ranges. The cooling rate dependence observed in the blend does not bring similarities to the crystallization behavior of individual constituents since the fall down of density with cooling rate should be related to the rate controlling demixing stage of the two moieties just before crystallization occurs. The kinetics observed is thus a measure of the kinetics of demixing. © 2009 Wiley Periodicals, Inc. J Polym Sci Part B: Polym Phys 47: 799–810, 2009
Antibody response to Pseudomonas aeruginosa in children with cystic fibrosis
Authors: Milagres Lucimar G. , Castro Tatiana L.A. , Garcia Daniely , Cruz Aline C. , Higa Laurinda , Folescu Tânia , Marques Elizabeth A.
Published: March 2009

Cystic fibrosis (CF) is the most frequent life threatening autosomal recessive disease in white subjects. The primary cause of morbidity and mortality in children with CF is chronic pulmonary infection, mainly caused by Pseudomonas aeruginosa. The purpose of this study was to assess the value of the measurement of antibodies to P. aeruginosa in diagnosing lung infection by the bacteria in CF patients. We assessed P. aeruginosa antibody titers in CF patients from Rio de Janeiro, Brazil, using cell lysate antigens as well as recombinant PcrV, a Type III Secretion System protein. Sputum (more than 70% of the specimens) or oropharyngeal swabs were obtained whenever patients were regularly followed for their pulmonary disease. Blood samples were obtained with an average interval of 6 months for a period of 2 years. The ELISA cut‐offs were assigned as the positive 95% confidence interval of the mean antibody levels from non‐fibrocystic controls. Our data showed that most CF patients (81%) of whom were not chronically infected by P. aeruginosa (Groups I and II), had their first serology positive for rPcrV. Cell‐lysate ELISA was able to detect P. aeruginosa antibodies before positive culture in the first serum sample of 44% of the patients from Groups I and II. When serum reactivity to rPcrV and cell lysate were combined, 94% of CF patients from Groups I and II (n = 16) had the first serology positive for P. aeruginosa over a mean time of 20 months before the first isolation of P. aeruginosa. In conclusion, longitudinal P. aeruginosa serology should become part of respiratory care follow‐up, in conjunction with other lung parameter functions. Pediatr Pulmonol. 2009; 44:392–401. © 2009 Wiley‐Liss, Inc.
Relationship between antimicrobial proteins and airway inflammation and infection in cystic fibrosis
Authors: Sagel Scott D. , Sontag Marci K. , Accurso Frank J.
Published: March 2009

Antimicrobial proteins are important in lung defense and are potential therapeutic agents in chronic airways infection such as seen in cystic fibrosis (CF). In preparation for future clinical studies, we sought (1) to determine levels of three antimicrobial proteins [lactoferrin, lysozyme, and secretory leukoprotease inhibitor (SLPI)] in the CF airway and (2) to examine the relationships between these antimicrobial proteins and airway inflammation and infection. We examined bronchoalveolar lavage fluid (BALF) from 45 individuals with CF and 23 disease control individuals. Airway inflammation was measured through BALF neutrophil counts and neutrophil elastase activity. Infection was assessed through quantitative counts of CF‐related bacterial pathogens. BALF lysozyme activity and lactoferrin levels were elevated in individuals with CF compared to controls whereas SLPI levels were not different between the groups. Among the CF subjects, lysozyme activity and lactoferrin increased with age while SLPI decreased with age. Lysozyme activity and lactoferrin concentrations correlated positively with neutrophil counts but not with bacterial colony counts. SLPI levels were inversely related to both neutrophil counts and bacterial colony counts. This study provides information concerning the levels of antimicrobial proteins present in the CF airway that are relevant to future clinical trials of these compounds and demonstrates clear relationships between antimicrobial protein‐specific levels and airway inflammation and infection. Pediatr Pulmonol. 2009; 44:402–409. © 2009 Wiley‐Liss, Inc.
Relationship Between the Electrostatic Sensitivity of Nitramines and Their Molecular Structure
Authors: Hossein Keshavarz Mohammad , Moghadas Mohammad Hassan , Kavosh Tehrani Masoud
Published: March 2009

In this paper, a new approach is introduced to predict the electrostatic sensitivity of nitramines on the basis of their molecular structure. The ratio of carbon to oxygen and the existence of two specific structural parameters can be used for the prediction of the electrostatic sensitivity of nitramines. The results are also compared with quantum mechanical computations from [9] so that the new method gives better predictions with respect to the measured data. Electrostatic sensitivities calculated by the new method for two new nitramines CL‐20 [2,4,6,8,10,12‐hexanitro‐2,4,6,8,10,12‐hexaazaisowurtzitane] and TNAZ [1,3,3‐trinitroazatidine] are also close to the experimental data.
Epitaxial LSMO films grown on GaAs substrates with MgO buffer layer
Authors: Španková Marianna , Chromik Štefan , Vávra Ivo , Štrbík Vladimír , Liday Jozef , Vogrinčič Peter , Espinós Juan Pedro , Lobotka Peter
Published: March 2009

La0.67Sr0.33MnO3 (LSMO) manganite thin films were deposited using a magnetron dc sputtering on single crystalline GaAs(001) substrates covered by MgO buffer layers with the goal to fabricate, using MEMS technology, a microbolometer operating at room temperature. The crystalline perfection of the thin film structures are characterized by X‐ray diffraction technique, rocking curve measurements, and transmission electron microscopy (TEM). TEM analyses give evidence of the epitaxial growth of the annealed LSMO. Auger Electron Spectroscopy as well as X‐ray Photoemission Spectroscopy are used to investigate compositional properties of the films. The analyses show a stoichiometric LSMO film without any contamination except of the surface where we register some traces of As, C and Mg. The temperature dependence of resistance, measured by a standard four‐probe technique, exhibits a peak at a temperature of 280 K. The maximum temperature coefficient of resistance reaches a value of ∼2.3% K–1 at T = 249 K. (© 2009 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)
Controlled enlargement of pores by annealing of porous silicon
Authors: Salonen J. , Mäkilä E. , Riikonen J. , Heikkilä T. , Lehto V.‐P.
Published: March 2009

In the present work, a possibility to use thermal annealing of porous silicon to enlarge the pore sizes has been studied. The size of the pores can be increased by controlling the annealing temperature and time. The pore enlargements from 10 nm even up to 100 nm can be obtained without destroying the pore structure. In all studied cases, annealing was found to decrease the surface areas and pore volumes of porous silicon, but the effects of annealing as a function of temperature were found to be strongly dependent on the initial porosity of samples. The crystallinity of the annealed samples was studied with XRD and the obtained results were used to explain differences observed in the pore sizes after the HF treatment of annealed samples. (© 2009 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)
Photoexcited silicon nanocrystals: mediators for the excitation of organic molecules
Authors: Goller Bernhard , Polisski Sergej , Kovalev Dmitry
Published: March 2009

We report on spin‐flip activation of organic molecules from the ground state to one of the excited states having different electronic spin configurations. Based on photoexcitations in silicon (Si) nanocrystals, stored electronic energy can be transferred to other substances. The huge hydrogen passivated surface being accessible for acceptor molecules, the tunable confinement energy of excitons and their very long radiative lifetime allow Si nanocrystals to act efficiently as photosensitizers. We demonstrate that the energy transfer is governed by electron exchange mechanism. Therefore a good overlap of the electron wave functions, of donor and acceptor, is crucial for the efficiency of this type of interaction. (© 2009 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)
Ternary magnetic semiconductors: recent developments in physics and technology
Authors: Tsurkan V. , von Nidda H.‐A. Krug , Krimmel A. , Lunkenheimer P. , Hemberger J. , Rudolf T. , Loidl A.
Published: March 2009

Recent results in physics and technology of ternary magnetic oxide and chalcogenide spinels AB2X4 (A = Fe, Mn, Co, Cd, Zn, Hg; B = Cr, Co, Sc, Al; X = O, S, Se) are reviewed. Using magnetic susceptibility, specific heat, thermal expansion, electron‐spin resonance, neutron diffraction, broad‐band dielectric spectroscopy, and infrared optical spectroscopy, the spin, charge, orbital, and lattice correlations in these compounds were investigated. The novel magnetic ground states, e.g., spin liquid, spin–orbital liquid, and orbital glass, and in triguing effects, like colossal magnetocapacitive coupling, negative thermal expansion, and spin‐driven Jahn–Teller structural transformations were revealed. In considering the origin of these phenomena, the concept of geometrical and bond frustration is explored. It relates the interplay of charge, spin, and orbital degrees of freedom with the inherent topological frustration and competing exchange interactions between the magnetic ions. (© 2009 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)
Spatially resolved characterization of chemical species and crystal structures in CuInS2 and CuGax Sey thin films using Raman microscopy
Authors: Schmid Thomas , Camus Christian , Lehmann Sebastian , Abou‐Ras Daniel , Fischer Christian‐Herbert , Lux‐Steiner Martha Christina , Zenobi Renato
Published: March 2009

This study demonstrates the potential of Raman microscopy in the analysis of thin film cross‐sections. Raman maps of the photovoltaic material CuInS2 (CIS), which was prepared by the spray ion layer gas reaction method, revealed the spatial distribution of two different CIS modifications – chalcopyrite‐type and CuAu I‐type CIS – as well as contaminants and segregates with a lateral resolution of approx. 400 nm. Additionally, the chemical heterogeneity of a CuGaSe2/CuGa3Se5 bi‐layer stack was clearly resolved. Raman microscopy provides a convenient way to simultaneously probe the chemical and structural properties of a sample. Based on Raman spectra, chemical species and even different crystal structures of inorganic compounds can be identified. Knowledge of the distribution of different phases and contaminants in thin films is crucial for further improvements of the coating process. (© 2009 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)
Raman scattering and structural analysis of electrodeposited CuInSe2 and S‐rich quaternary CuIn(S,Se)2 semiconductors for solar cells
Authors: Izquierdo‐Roca Víctor , Saucedo Edgardo , Ruiz Carmen M. , Fontané Xavier , Calvo‐Barrio Lorenzo , Álvarez‐Garcia Jacobo , Grand Pierre‐Philippe , Jaime‐Ferrer Jesus Salvador , Pérez‐Rodríguez Alejandro , Morante Joan Ramón , Bermudez Verónica
Published: March 2009

This work reports the Raman scattering characterisation of CuInSe2 precursors grown by single step electrodeposition and the corresponding layers recrystallised under sulphurising conditions for solar cell devices. The analysis of the spectra measured on the as‐grown precursors has allowed identifying the main secondary phases in these layers with elemental Se, Cu–Se phases and chalcopyrite Cu‐poor ordered vacancy domains. To deepen in the identification of the Cu–Se phases, these measurements have been correlated with the analysis of binary Cu–Se layers. The experimental data indicate that formation of both Se and Cu–Se phases is likely controlled by the Se content in the layers. For values of stoichiometry below 1.15, excess Cu in the layers is accommodated in a phase with very low Raman efficiency (as Cu2Se). Increasing the content of Se leads to an increase in the spectral contribution from both Se and Cu2–x Se, being the formation of these phases likely favoured under high excess Se conditions. The characterisation of the corresponding recrystallised layers has allowed analysing the impact of the presence of the secondary phases in the as‐grown absorbers on the performance of the final solar cells. (© 2009 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)
Room temperature characterisation of InGaAlAs quantum well laser structures using electro‐modulated reflectance and surface photovoltage spectroscopy
Authors: Fox Natasha E. , Sharma Tarun K. , Sweeney Stephen J. , Hosea T. J. C.
Published: March 2009

In this study, two tri‐metal quaternary InGaAlAs quantum well (QW) laser structures grown on InP are compared to a conventional InGaAsP QW structure, also grown on InP, all designed to lase at 1.55 μm. Several spectroscopic methods are used to study the samples including surface photo‐voltage (SPV) and electro‐modulated reflectance (ER). In the tri‐metal samples the ground‐ and two excited‐state QW transitions are detectable in both types of spectroscopy. The SPV and ER give results in agreement to within a few meV of each other. By comparing the position of the measured QW transitions with those predicted theoretically, the conduction band offsets of the tri‐metal samples can be determined and compared to that in the InGaAsP sample. It is found that the tri‐metal samples have a much larger conduction band offset of ∼66% compared to the ∼40% in the InGaAsP sample. (© 2009 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)