bluuebunny/crossref_metadata_2025_split huggingface dataset:
Vibrational properties of polysiloxanes: from dimer to oligomers and polymers. 1. Structural and vibrational properties of hexamethyldisiloxane (CH3)3SiOSi(CH3)3
Authors: Carteret C. , Labrosse A. 
Published: November 2009

AbstractThe hexamethyldisiloxane (HMDS)(CH3)3SiOSi(CH3)3 molecule is one of the basic building blocks of silicones and polysiloxanes, as it is used for many chain terminations. Far‐infrared, mid‐infrared, and polarized Raman spectroscopic studies, combined with quantum chemical calculations and vibrational normal mode analyses, were performed for the HMDS molecule. The internal rotation of the trimethylsilyl group was calculated to be nearly free. The large‐amplitude bending motion was found very anharmonic with a barrier to linearity below 4 kJ/mol. Exhaustive assignments of observed wavenumbers have been performed on the basis of calculated potential energy distributions (PED) and atomic displacements. By isotopic 16O18O substitution, the SiOSi symmetric and antisymmetric stretching modes shift from 521 and 1074 cm−1 to 514 and 1028 cm−1, respectively. This spectroscopic observation provides convincing evidence that the molecule is bent with an angle estimated at around 150°. The comparison of HMDS vibrational spectra with the vibrational spectra of some siloxane derivatives reveals strong effects of silicon substituents on the SiOSi symmetric and antisymmetric stretchings. The SiOSi siloxane bridge group plays a key role in the properties of the HMDS molecule and may also account for some important silicone polymer properties such as their very low glass transition, their high compressibility, and their low surface tension. Copyright © 2009 John Wiley & Sons, Ltd.
Carbon‐based stock feed additives: a research methodology that explores ecologically delivered C biosequestration, alongside live weights, feed use efficiency, soil nutrient retention, and perennial fodder plantations
Authors: McHenry Mark P 
Published: November 2009

AbstractThere is considerable interest in reliable and practical methods to sequester carbon (C) into agricultural soils to both reduce atmospheric greenhouse gas concentrations and improve conventional productivity. This article outlines a research methodology to refine the efficacy and economics of using long‐lived C species (biochars) as stock feed additives, produced from farm waste biomass, for ecologically delivered soil biosequestration, while generating renewable bioenergy. This article also draws attention to potential parallel outputs including annual feed use efficiency, fodder species expansion, soil nutrient retention, aquatic habitat protection, and forestry revegetation, using nitrogen‐fixing perennial fodder plant species. A methodology to generate parallel results including standing fodder tree C sequestration, optimised production of Acacia spp. biochar, animal growth on high‐tannin fodder with biochar feed additives, soil nutrient and stable C fractions, and economics of Acacia spp. bioenergy production. This form of research is contextually dependent on the regional agricultural production system, legislation, and surrounding ecosystem. Therefore, this article suggests the use of a scenario approach to include regionally specific levels of biochar integration with respect to the local prices for C, fossil fuels, meat and livestock, fertilisers, fodder, feed additives, water, renewable energy, revegetation and capital. Copyright © 2009 Society of Chemical Industry
Predictions of chromatographic retention indices of alkylphenols with support vector machines and multiple linear regression
Authors: Fatemi Mohammed Hossein , Baher Elham , Ghorbanzade'h Mehdi 
Published: November 2009

AbstractIn this study, quantitative structure–retention relationship (QSRR) was used for the prediction of Kováts retention indices of 180 alkylphenols and their derivatives using the multiple linear regression (MLR) and support vector machine (SVM). After the calculation of some molecular descriptors for all molecules, the data set was randomly divided into training and test sets. The diversity of training and test sets was examined by molecular diversity validation test. Then stepwise MLR was used for the selection of the most important descriptors and development of MLR models. Descriptors which appeared in these QSRR models are number of H atoms, relative number of O atoms, Balaban index, relation yz‐shadow/yz‐rectangle and partial charges hydrogen bond donor atoms HDCA2 index. These descriptors were used as inputs for developing the SVM model. After optimizing the SVM parameters, it was used for the calculation of chromatographic retention of interest molecules. The values of SE in calculation of Kováts retention indices for training and test sets are 0.34 and 0.63, respectively, for MLR model and 0.35 and 0.63, respectively, for SVM model. The overall values of average absolute relative error were 13.24 and 13.83 for MLR and SVM models, respectively. In addition, the cross‐validation tests were performed to further examine the obtained model. The calculated values of cross‐validation correlation coefficient (Q2) and standard deviation based on predicted residual sum of square are 0.896 and 0.680 for MLR model and 0.893 and 0.67 for SVM model. These values and other obtained statistical parameters for these models reveal the suitability of QSRR in prediction of Kováts retention indices of alkylphenols using MLR and SVM techniques.
Ionic liquid surfactant‐mediated ultrasonic‐assisted extraction coupled to HPLC: Application to analysis of tanshinones in Salvia miltiorrhiza bunge
Authors: Wu Kangkang , Zhang Qianli , Liu Qian , Tang Fei , Long Yiming , Yao Shouzhuo 
Published: November 2009

AbstractIonic liquid surfactants are a class of ionic liquids (ILs), which can form micelles in the aqueous solution. In this paper, we demonstrate a novel extracting system based on the use of IL surfactants in ultrasonic‐assisted extraction followed by HPLC analysis. No organic solvents were used in the extraction, making this method environmentally friendly and more attractive than the conventional organic solvent‐based extraction methods. As an example, this method was applied to determine tanshinones in Chinese herbal medicine Salvia miltiorrhiza bunge. The effect of the carbon chain length of the IL cation, as well as other influencing factors on ultrasonic‐assisted extraction, was investigated in detail. Under the optimized conditions, satisfactory extraction efficiency was achieved with the recoveries ranging from 87.5 to 107.6%, and the RSDs were lower than 6%. This work shows a promising prospect of the IL surfactants in the extraction of active ingredients from herbs.
Nitrogen‐protected microwave‐assisted extraction of ascorbic acid from fruit and vegetables
Authors: Yu Yingjia , Chen Bin , Chen Yile , Xie Meifen , Duan Haotian , Li Yan , Duan Gengli 
Published: November 2009

AbstractIn this study, nitrogen‐protected microwave‐assisted extraction (NPMAE), in which microwave‐assisted extraction was performed under nitrogen protection, was initially developed and combined with HPLC separation for the determination of ascorbic acid (AA), an oxidizable component, from fruit and vegetables. The extraction conditions of NPMAE were investigated by extraction of AA from guava, and the chosen conditions were as follows: extraction solvent of 0.25% metaphosphoric acid solution, solid/liquid ratio of 1:10 g/mL, microwave power of 400 W and irradiation time of 10 min. Subsequently, this novel NPMAE method was evaluated by extraction of AA from different fruit and vegetables, such as guava, yellow pepper, green pepper and cayenne pepper. Compared with conventional MAE and solvent extraction methods, the oxidation of AA was significantly reduced or prevented in the process of NPMAE, providing higher extraction yield of AA. These results suggested the potential of NPMAE method for the extraction of oxidizable compounds from different spices of matrices.
Development of a new method for improved identification and relative quantification of unknown metabolites in complex samples: Determination of a triterpenoid metabolic fingerprint for the in situ characterization of Ganoderma bioactive compounds
Authors: Adamec Jiri , Jannasch Amber , Dudhgaonkar Shailesh , Jedinak Andrej , Sedlak Miroslav , Sliva Daniel 
Published: November 2009

AbstractGanoderma lucidum is a mushroom with a long history of medical applications. Research has demonstrated chemotherapeutic effects of G. lucidum in tissue culture, and bioactive fractions of the mushroom have been shown to contain high levels of triterpenoids and polysaccharides. In this study, we developed a new method for the detection of ganoderic acids and other triterpenes in Ganoderma mushroom extracts based on a post‐biosynthetic stable isotope encoding technique. Overall, 57 doublets were identified as potential ganoderic acids and 11 of those matched with the database. Ganoderic acid A, F and H were confirmed by standards and their absolute concentrations were measured in GLT (GA A: 3.88 mg/g; GA F: 0.95 mg/g and GA H: 1.74 mg/g) and ReishiMax (GA A: 2.32 mg/g; GA F: 0.43 mg/g and GA H: 0.85 mg/g) extracts. The method was also used for the evaluation of bioavailability of triterpenes after an oral application and demonstrated the presence of G. lucidum triterpenes in plasma.
Mathematical Modeling and Optimization of Run Parameters of Crystallization Analysis Fractionation (CRYSTAF)
Authors: Fischlschweiger Michael , Aust Nicolai , Oberaigner Eduard R. , Kock Cornelia 
Published: November 2009

AbstractBlends of a random poly(propylene) copolymer with different types of polyethylene were used to develop a sample independent statistic mathematical model which describes the quality of phase separation of polymer blends obtained by CRYSTAF. By coupling the abstract model with experimental data, process parameters influencing the non‐equilibrium CRYSTAF separation process can be determined. It could be shown that the stirring speed applied during the fractionation process strongly influences the resolution of the derived CRYSTAF profile and thus the quality of fractionation. Nonlinear optimization of the models' response function leads to optimized run parameters for the CRYSTAF process which results in CRYSTAF profiles of high resolution and thus to a high quality in fractionation.magnified image
A Novel High Throughput Method to Investigate Polymer Dissolution
Authors: Zhang Ying , Mallapragada Surya K. , Narasimhan Balaji 
Published: November 2009

AbstractThe dissolution behavior of polystyrene (PS) in biodiesel was studied by developing a novel high throughput approach based on Fourier‐transform infrared (FTIR) microscopy. A multiwell device for high throughput dissolution testing was fabricated using a photolithographic rapid prototyping method. The dissolution of PS films in each well was tracked by following the characteristic IR band of PS and the effect of PS molecular weight and temperature on the dissolution rate was simultaneously investigated. The results were validated with conventional gravimetric methods. The high throughput method can be extended to evaluate the dissolution profiles of a large number of samples, or to simultaneously investigate the effect of variables such as polydispersity, crystallinity, and mixed solvents.magnified image
New Low Bandgap Dithienylbenzothiadiazole Vinylene Based Copolymers: Synthesis and Photovoltaic Properties
Authors: Liu Bo , Najari Ahmed , Pan Chunyue , Leclerc Mario , Xiao Dequan , Zou Yingping 
Published: November 2009

AbstractTwo new low‐bandgap block copolymers derived from dithienylbenzothiadiazole (DTBT) and different electron‐rich functional groups (dioctoxyl benzene and N‐octyl‐diphenylamine), poly(1,4‐dioctoxyl‐2,5‐divinylbenzene‐co‐4,7‐dithiophene‐2′‐yl‐2,1,3‐benzothiadiazole) (PPV‐DTBT), poly(3,8‐divinyl‐N‐octyl‐diphenylamine‐co‐4,7‐dithiophene‐2′‐yl‐2,1,3‐benzothiadiazole) (PDPAV‐DTBT), were synthesized by Heck cross‐coupling polymerization. PPV‐DTBT and PDPAV‐DTBT are easily soluble in common organic solvents such as o‐dichlorobenzene and chloroform. DSC and TGA results indicate that these copolymers possess good thermal stabilities. PPV‐DTBT and PDPAV‐DTBT films exhibit broad absorption bands at 300–765 nm (with an optical bandgap of 1.62 eV) and 300–733 nm (with an optical bandgap of 1.69 eV), respectively. The highest occupied molecular orbital (HOMO) and the lowest unoccupied molecular orbital (LUMO) of PPV‐DTBT were estimated by cyclic voltammetry to be −5.43 and −3.74 eV, respectively, and the HOMO and LUMO of PDPAV‐DTBT were −5.37 and −3.7 eV, respectively. Preliminary photovoltaic cells based on the composite structure of ITO/PEDOT: PSS/PPV‐DTBT:PCBM (1: 2, w/w)/Al showed an open‐circuit voltage of 0.75 V, a power conversion efficiency of 0.6%, and a short circuit current of 1.7 mA · cm−2.magnified image
Physicochemical properties and thermal stability of Lep w 1, the major allergen of whiff
Authors: Griesmeier Ulrike , Bublin Merima , Radauer Christian , Vázquez‐Cortés Sonia , Ma Yan , Fernández‐Rivas Montserrat , Breiteneder Heimo 
Published: November 2009

AbstractWhiff (Lepidorhombus whiffiagonis) is a fish frequently consumed in Spain. Lep w 1, its major allergen, is a calcium‐binding β‐parvalbumin. The resistance of Lep w 1 to heat denaturation and to digestion were studied by circular dichroism spectroscopy and by in vitro gastric digestion systems. Purified Lep w 1 was thermally stable up to 65°C at neutral pH. Calcium depletion resulted in a change of its structure as determined by circular dichroism spectroscopy. A partial loss of structure was also observed at acidic pH; however, the allergen retained its full IgE‐binding ability. The partially denatured Lep w 1 was easily digested by pepsin within 2 min. Further, the IgE reactivity of proteins extracted from cooked fish and their stability to proteolysis were analyzed. The extract revealed a higher number of IgE reactive bands than an extract from uncooked fish. IgE binding to these proteins could not be inhibited by an extract from uncooked fish. In contrast to a raw fish extract, the cooked extract showed higher resistance to pepsinolysis. The stability of Lep w 1 to thermal denaturation and digestion explains the high allergenicity of whiff.
Absorption, metabolism, and excretion of green tea flavan‐3‐ols in humans with an ileostomy
Authors: Stalmach Angélique , Mullen William , Steiling Heike , Williamson Gary , Lean Michael E. J. , Crozier Alan 
Published: November 2009

AbstractGreen tea containing 634 μmol of flavan‐3‐ols was ingested by human subjects with an ileostomy. Ileal fluid, plasma, and urine collected 0–24 h after ingestion were analysed by HPLC‐MS. The ileal fluid contained 70% of the ingested flavan‐3‐ols in the form of parent compounds (33%) and 23 metabolites (37%). The main metabolites effluxed back into the lumen of the small intestine were O‐linked sulphates and methyl‐sulphates of (epi)catechin and (epi)gallocatechin. Thus, in subjects with a functioning colon substantial quantities of flavan‐3‐ols would pass from the small to the large intestine. Plasma contained 16 metabolites, principally methylated, sulphated, and glucuronidated conjugates of (epi)catechin and (epi)gallocatechin, exhibiting 101–256 nM peak plasma concentration and the time to reach peak plasma concentration ranging from 0.8 to 2.2 h. Plasma pharmacokinetic profiles were similar to those obtained with healthy subjects, indicating that flavan‐3‐ol absorption occurs in the small intestine. Ileostomists had earlier plasma time to reach peak plasma concentration values than subjects with an intact colon, indicating the absence of an ileal brake. Urine contained 18 metabolites of (epi)catechin and (epi)gallocatechin in amounts corresponding to 6.8±0.6% of total flavan‐3‐ol intake. However, excretion of (epi)catechin metabolites was equivalent to 27% of the ingested (−)‐epicatechin and (+)‐catechin.
An optimally convergent discontinuous Galerkin‐based extended finite element method for fracture mechanics
Authors: Shen Yongxing , Lew Adrian 
Published: November 2009

AbstractThe extended finite element method (XFEM) enables the representation of cracks in arbitrary locations of a mesh. We introduce here a variant of the XFEM rendering an optimally convergent scheme. Its distinguishing features are as follows: (a) the introduction of singular asymptotic crack tip fields with support on only a small region around the crack tip (the enrichment region), (b) only one and two enrichment functions are added for anti‐plane shear and planar problems, respectively and (c) the relaxation of the continuity between the enrichment region and the rest of the domain, and the adoption of a discontinuous Galerkin (DG) method therein. The method is provably stable for any positive value of a stabilization parameter, and by weakly enforcing the continuity between the two regions it eliminates ‘blending elements’ partly responsible for the suboptimal convergence of some early XFEMs. Moreover, the particular choice of enrichment functions results in a surprisingly sparse stiffness matrix that remains reasonably conditioned as the mesh is refined. More importantly, the stress intensity factors can be extracted with a satisfactory accuracy as primary unknowns. Quadrature strategies required for the optimal convergence are also discussed. Finally, the DG method was modified to retain stability based on an inf‐sup condition. Copyright © 2009 John Wiley & Sons, Ltd.
Additional evidence for the affective dimension of dyspnea in patients with COPD
Authors: Carrieri‐Kohlman Virginia , Donesky‐Cuenco DorAnne , Park Soo Kyung , Mackin Lynda , Nguyen Huong Q. , Paul Steven M. 
Published: November 2009

AbstractThe primary purpose of this secondary analysis was to determine whether 103 participants with chronic obstructive pulmonary disease rated the affective dimension of dyspnea (dyspnea‐related anxiety and dyspnea‐related distress) separately from the sensory dimension (intensity) during baseline exercise testing conducted as part of a randomized clinical trial. A secondary purpose was to determine if dyspnea‐related anxiety and distress were rated distinctly different from other measurements of anxiety. At the end of a 6‐minute walk and an incremental treadmill test, participant ratings of the magnitude of dyspnea‐related anxiety and distress on the Modified Borg Scale were significantly different from their ratings of the intensity of dyspnea. Dyspnea‐related anxiety and distress also appeared to be concepts independent from measures of state anxiety, negative affect, and anxiety before a treadmill test. © 2009 Wiley Periodicals, Inc. Res Nurs Health 33:4–19, 2010
Increasingly restrictive definitions of hyperkalemia outcomes in a database study: effect on incidence estimates
Authors: Raebel Marsha A. , Ross Colleen , Cheetham Craig , Petersen Hans , Saylor Gwyn , Smith David H. , Wright Leslie A. , Roblin Douglas W. , Xu Stanley 
Published: November 2009

AbstractPurposeTo determine the incidence of hyperkalemia‐associated adverse outcomes among ambulatory patients with diabetes newly initiating renin‐angiotensin‐aldosterone system (RAAS) inhibitor therapy and to examine to what extent increasingly restrictive definitions of hyperkalemia‐associated outcomes influenced incidence estimates.MethodsRetrospective cohort study of 27 355 individuals with diabetes who were new users of RAAS inhibitors at three integrated healthcare systems.ResultsUsing the least restrictive definition of hyperkalemia‐associated outcome, an ambulatory visit (AV), inpatient hospitalization (IP), or emergency department (ED) visit co‐occurring within 7 days of coded hyperkalemia diagnosis and/or potassium concentration of ≥5.5 mmol/L, the incidence rate of hyperkalemia was 30.1 per 1000 person‐years (p‐y). Restricting to only IP or ED visits co‐occurring within 24 hours of coded diagnosis and/or potassium ≥6 mmol/L, the incidence rate was 10.2 per 1000 p‐y. When this latter definition was further restricted by removing available potassium laboratory values, the incidence rate declined to 9.5 per 1000 p‐y.ConclusionsModifying the definition of hyperkalemia‐associated outcome resulted in up to threefold differences in incidence rate estimates. Our results demonstrate the value of including potassium laboratory results and AVs in identifying hyperkalemia from electronic data. Comparing incidence estimates across published studies requires consideration of differences in outcome definitions. Copyright © 2009 John Wiley & Sons, Ltd.
Theoretical and visual study of bubble dynamics in foam injection molding
Authors: Mahmoodi Mehdi , Behravesh Amir Hossein , Rezavand Seyyed Abdol Mohammad , Golzar Mohammad 
Published: November 2009

AbstractThis article presents an experimental observation and a theoretical prediction of bubble dynamics in foam injection molding process with a main focus on the cell collapse phenomenon under pressure. Using a visualizing setup, cell growth behavior under a nonisothermal condition was monitored. In conjunction with the growth behavior, dynamics of cell collapse under different pressures and the effect of growing time on collapse behavior and final cell size were studied. Theoretical simulation of bubble behavior included power law model, which predicted bubble dynamics during foaming process. The results show that collapse phenomenon strongly depends on both exerted holding pressure and growth time. The presented model can also give a reasonable prediction of growth and collapse of cells and could give insight to control of cell size in injection foaming process. POLYM. ENG. SCI., 2010. © 2009 Society of Plastics Engineers
Sodium 1, 4‐dihydroxy‐9, 10‐anthraquinone‐ 2‐sulphonate interacts with calf thymus DNA in a way that mimics anthracycline antibiotics: an electrochemical and spectroscopic study
Authors: Guin Partha Sarathi , Das Saurabh , Mandal P. C. 
Published: November 2009

AbstractThe anthracycline drugs, adriamycin and daunorubicin, efficient in the treatment of various human cancers, form strong intercalation complexes with DNA. The therapeutic efficiency and toxic properties of the drugs are associated with electron transfer processes, which correlate well with the redox behaviour of the compounds. Sodium 1,4‐dihydroxy 9,10‐anthraquinone‐2‐sulphonate (sodium quinizarin‐2‐sulphonate, NaLH2) (Na‐Qz‐2S) is a molecule that resembles anthracycline drugs and has a simpler structure in comparison to these drugs. Two electrons in the course of chemical action reduce this molecule like the anthracyclines. Electrochemical methods were used to identify this process. UV‐Vis and fluorescence spectroscopy were used to analyse binding of the compound to calf thymus DNA. The binding constant and site size were evaluated for Na‐Qz‐2S and the same compared to that of the anthracyclines. Such comparisons are essential in order to understand whether the simpler hydroxy‐anthraquinones can be a substitute for anthracycline drugs in cancer chemotherapy. Copyright © 2009 John Wiley & Sons, Ltd.