bluuebunny/crossref_metadata_2025_split huggingface dataset:
Microwave‐assisted extraction of total bioactive saponin fraction from Gymnema sylvestre with reference to gymnemagenin: a potential biomarker
Authors: Mandal Vivekananda , Dewanjee Saikat , Mandal Subhash C. 
Published: August 2009

AbstractObjective – To develop a fast and ecofriendly microwave assisted extraction (MAE) technique for the effective and exhaustive extraction of gymnemagenin as an indicative biomarker for the quality control of Gymnema sylvestre.Methodology – Several extraction parameters such as microwave power, extraction time, solvent composition, pre‐leaching time, loading ratio and extraction cycle were studied for the determination of the optimum extraction condition. Scanning electron micrographs were obtained to elucidate the mechanism of extractionResults – The final optimum extraction conditions as obtained from the study were: 40% microwave power, 6 min irradiation time, 85% v/v methanol as the extraction solvent, 15 min pre‐leaching time and 25 : 1 (mL/g) as the solvent‐to‐material loading ratio. The proposed extraction technique produced a maximum yield of 4.3% w/w gymnemagenin in 6 min which was 1.3, 2.5 and 1.95 times more efficient than 6 h of heat reflux, 24 h of maceration and stirring extraction, respectively. A synergistic heat and mass transfer theory was also proposed to support the extraction mechanismConclusion – Comparison with conventional extraction methods revealed that MAE could save considerable amounts of time and energy, whilst the reduction of volume of organic solvent consumed provides an ecofriendly feature. Copyright © 2009 John Wiley & Sons, Ltd.
Synthesis and characterization of hydrophilic copolymers of maleimide derivatives with 2‐hydroxyethyl methacrylate: electrochemical and thermal behavior
Authors: Pizarro Guadalupe del C , Marambio Oscar G , Jeria‐Orell Manuel , Oyarzún Diego P , Rivas Bernabé L , Habicher Wolf D 
Published: August 2009

AbstractBACKGROUND: The high‐technology industries have been the driving force in the development of new synthetic polymers that combine thermal stability with specific functional properties. In this study p‐chlorophenylmaleimide, p‐hydroxyphenylmaleimide and p‐nitrophenylmaleimide (R‐PhMI) with 2‐hydroxyethyl methacrylate (HEMA) were synthesized by free radical polymerization to obtain hydrophilic polymers, in order to study the effect of the p‐chloroaryl, p‐hydroxyaryl or p‐nitroaryl group on the copolymer composition, electrochemical behavior and thermal properties.RESULTS: The thermal behavior was correlated with the copolymer composition and functional groups, maleimide derivatives, on the copolymers. Thermal decomposition temperature (TDT) and glass transition temperature (Tg) were influenced by the functional groups of R‐PhMI moiety on the copolymer. The polymers showed an electrochemically irreversible reduction process under the conditions tested.CONCLUSION: Poly[(p‐chloromaleimide)‐co‐(2‐hydroxyethyl methacrylate)] copolymer shows a higher TDT than poly[(p‐hydroxymaleimide)‐co‐(2‐hydroxyethyl methacrylate)] or poly[(p‐nitromaleimide)‐co‐(2‐hydroxyethyl methacrylate)] (NPHE). Tg decreases in going from nitro to hydroxyl to chloro groups. The NPHE copolymer shows a lower stability, losing weight at 200 °C. The NPHE copolymer shows a well‐defined reduction wave which is similar to those of the other copolymers and it also shows an additional quasi‐reversible reduction wave corresponding to the nitrobenzene group. Copyright © 2009 Society of Chemical Industry
Synthesis of poly(ether amide)s from p‐xylylene glycol and bis(ether nitrile)s
Authors: Lakouraj Moslem Mansour , Mokhtary Masoud 
Published: August 2009

AbstractBACKGROUND: Poly(ether amide)s have been well studied in terms of improving the physical and thermal properties of aromatic polyamides. Poly(ether amide)s of high enough molecular weight to be useful for industrial purposes are generally difficult to prepare. The objective of this project was to introduce a simple and commercially feasible process to prepare poly(ether amide)s by a polymerization reaction at relatively low temperature.RESULTS: A series of poly(ether amide)s were prepared by direct polyamidation of p‐xylylene glycol with bis(ether nitrile)s via the Ritter reaction using concentrated H2SO4 in acetic acid. The synthesized poly(ether amide)s showed good solubility in polar aprotic solvents. The resultant poly(ether amide)s had inherent viscosities in the range 0.36–1.03 dL g−1. The glass transition temperatures of the poly(ether amide)s were determined using differential scanning calorimetry to be in the range 190–258 °C. Thermogravimetric analysis data for these polymers indicated the 10% weight loss temperatures to be in the range 290–390 °C in nitrogen atmosphere.CONCLUSION: The Ritter reaction was applied for the synthesis of a variety of poly(ether amide)s with moderate to high molecular weights. This procedure provides a simple polymerization process for the convenient preparation of poly(ether amide)s in high yield at room temperature. Copyright © 2009 Society of Chemical Industry
Preparation of nanosize polyaniline by solid‐state polymerization and determination of crystal structure
Authors: Bhadra Sambhu , Kim Nam Hoon , Rhee Kyong Yop , Lee Joong Hee 
Published: August 2009

AbstractBACKGROUND: Nanosize polyaniline has several advantages in both the fabrication of nanodevices and for preparing nanoscale electrical connections in highly conducting polymer composites.RESULTS: Nanosize polyaniline with a diameter of 30–60 nm was prepared using a solid‐state polymerization process (PANI‐S) by mixing an equimolar quantity of ammonium persulfate and anilinium chloride crystals with a mortar and pestle. Polyaniline was also synthesized using a conventional oxidative polymerization method (PANI‐C) in an aqueous medium for comparison. Conductivity and contact angle measurements, infrared spectroscopy, ultraviolet spectroscopy, transmission electron microscopy and thermogravimetric analysis were carried out. An in‐depth investigation of the crystal structure of these polymers was carried out through powder X‐ray diffraction analysis.CONCLUSION: PANI‐S exhibited lower conductivity due to the presence of less emeraldine base form, lower crystallinity, greater d‐spacing and greater inter‐chain separation than PANI‐C. The hydrophilicity and thermal stability of PANI‐S were higher than those of PANI‐C. The unit cell volume of PANI‐S was much higher, resulting in a larger crystallite size and a greater number of atoms in the unit cell than PANI‐C. Copyright © 2009 Society of Chemical Industry
Phosphorylation of the SSBP2 and ABL proteins by the ZNF198‐FGFR1 fusion kinase seen in atypical myeloproliferative disorders as revealed by phosphopeptide‐specific MS
Authors: Kasyapa Chitta , Gu Ting‐Lei , Natarajan Lalitha , Polakiewicz Roberto , Cowell John K. 
Published: August 2009

AbstractThe ZNF198‐fibroblast growth factor receptor‐1 (FGFR1) fusion kinase is a constitutively activated tyrosine kinase associated with a specific atypical myeloproliferative disease. The chimeric protein localizes to the cytoplasm, unlike the wild type FGFR1 receptor kinase, and presumably inappropriately phosphorylates specific targets as part of the oncogenic signaling cascade. Other than known targets of the FGFR1 kinase itself, few specific targets of ZNF198‐FGFR1 have been identified. Using a genetically engineered HEK 293 cell system, we have identified proteins that are specifically phosphorylated in the presence of the fusion kinase using anti‐phosphotyrosine immunoprecipitation and MS. Compared with 293 cells expressing exongenous wild type FGFR1, ZNF198‐FGFR1 is associated with phosphorylation of several proteins including SSBP2, ABL, FLJ14235, CALM and TRIM4 proteins. The specificity of the phosphorylation events in the SSBP2 and ABL proteins, which have previously been implicated in leukemogenesis, was further confirmed independently using immunoprecipitation with protein‐specific antibodies and Western blotting. The MS analysis also identified the phosphorylation events in the ZNF198 moiety in the chimeric protein that might be related to its function. These studies identify the intersection of several different leukemia‐related pathways in the development of this myeloproliferative disorder and provide new insights into the substrates of FGFR1 under defined conditions.
The interaction profile of homologous recombination repair proteins RAD51C, RAD51D and XRCC2 as determined by proteomic analysis
Authors: Rajesh Changanamkandath , Gruver Aaron M. , Basrur Venkatesha , Pittman Douglas L. 
Published: August 2009

AbstractThe RAD51 family of proteins is involved in homologous recombination (HR) DNA repair and maintaining chromosome integrity. To identify candidates that interact with HR proteins, the mouse RAD51C, RAD51D and XRCC2 proteins were purified using bacterial expression systems and each of them used to co‐precipitate interacting partners from mouse embryonic fibroblast cellular extracts. Mass spectroscopic analysis was performed on protein bands obtained after 1‐D SDS‐PAGE of co‐precipitation eluates from cell extracts of mitomycin C treated and untreated mouse embryonic fibroblasts. Profiling of the interacting proteins showed a clear bias toward nucleic acid binding and modification proteins. Interactions of four candidate proteins (SFPQ, NONO, MSH2 and mini chromosome maintenance protein 2) were confirmed by Western blot analysis of co‐precipitation eluates and were also verified to form ex vivo complexes with RAD51D. Additional interacting proteins were associated with cell division, embryo development, protein and carbohydrate metabolism, cellular trafficking, protein synthesis, modification or folding, and cell structure or motility functions. Results from this study are an important step toward identifying interacting partners of the RAD51 paralogs and understanding the functional diversity of proteins that assist or regulate HR repair mechanisms.
Spectral clustering in peptidomics studies helps to unravel modification profile of biologically active peptides and enhances peptide identification rate
Authors: Menschaert Gerben , Vandekerckhove Tom T. M. , Landuyt Bart , Hayakawa Eisuke , Schoofs Liliane , Luyten Walter , Van Criekinge Wim 
Published: August 2009

AbstractWhen studying the set of biologically active peptides (the so‐called peptidome) of a cell type, organ, or entire organism, the identification of peptides is mostly attempted by MS. However, identification rates are often dismally unsatisfactory. A great deal of failed or missed identifications may be attributable to the wealth of modifications on peptides, some of which may originate from in vivo post‐translational processes to activate the molecule, whereas others could be introduced during the tissue preparation procedures. Preliminary knowledge of the modification profile of specific peptidome samples would greatly improve identification rates. To this end we developed an approach that performs clustering of mass spectra in a way that allows us to group spectra having similar peak patterns over significant segments. Comparing members of one spectral group enables us to assess the modifications (expressed as mass shifts in Dalton) present in a peptidome sample. The clustering algorithm in this study is called Bonanza, and it was applied to MALDI‐TOF/TOF MS spectra from the mouse. Peptide identification rates went up from 17 to 36% for 278 spectra obtained from the pancreatic islets and from 21 to 43% for 163 pituitary spectra. Spectral clustering with subsequent advanced database search may result in the discovery of new biologically active peptides and modifications thereof, as shown by this report indeed.
Synthesis of four‐arm star poly(L‐lactide) oligomers using an in situ‐generated calcium‐based initiator
Authors: George Karina A. , Schué François , Chirila Traian V. , Wentrup‐Byrne Edeline 
Published: August 2009

AbstractUsing an in situ‐generated calcium‐based initiating species derived from pentaerythritol, the bulk synthesis of well‐defined four‐arm star poly(L‐lactide) oligomers has been studied in detail. The substitution of the traditional initiator, stannous octoate with calcium hydride allowed the synthesis of oligomers that had both low PDIs and a comparable number of polymeric arms (3.7–3.9) to oligomers of similar molecular weight. Investigations into the degree of control observed during the course of the polymerization found that the insolubility of pentaerythritol in molten L‐lactide resulted in an uncontrolled polymerization only when the feed mole ratio of L‐lactide to pentaerythritol was 13. At feed ratios of 40 and greater, a pseudoliving polymerization was observed. As part of this study, in situ FT‐Raman spectroscopy was demonstrated to be a suitable method to monitor the kinetics of the ring‐opening polymerization of lactide. The advantages of using this technique rather than FTIR‐ATR and 1H NMR for monitoring L‐lactide consumption during polymerization are discussed. © 2009 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 47: 4736–4748, 2009
Controlled synthesis of poly(dimethylsiloxane) homopolymers using high‐vacuum anionic polymerization techniques
Authors: Ninago Mario D. , Satti Angel J. , Ressia Jorge A. , Ciolino Andrés E. , Villar Marcelo A. , Vallés Enrique M. 
Published: August 2009

AbstractThe controlled synthesis of poly(dimethylsiloxane) homopolymers (PDMS) using hexamethyl(cyclotrisiloxane) monomer (D3), a mixture of ciclohexane/tetrahydrofuran 50/50 v/v and sec‐Bu–Li+ as initiator was studied using different experimental conditions, and whole‐sealed glass reactors according to standards procedures in high‐vacuum anionic polymerization. It was observed that polydispersity indexes (PD) and conversions strongly depend on temperature and reaction times. For PDMS homopolymers with molar masses below 100,000 g/mol, high conversion (>90%) and PD < 1.1 can be achieved at long reaction times (24 h) and mild temperature conditions (below or up to 30 °C). On the other hand, to synthesize PDMS homopolymers with molar masses higher than 100,000 g/mol and PD < 1.1 it is necessary to increase the temperature up to 50 °C and decrease the reaction time (8 h). However, under these reaction conditions, it was observed that the conversion decreases (about 65–70% conversion is achieved). Apparently, the competition between propagation and secondary reactions (redistribution, backbiting, and reshuffling) depends on the molar masses desired. According to the results obtained in this study—which were compared with others found in the scientific literature—propagation is favored when Mn < 100,000 g/mol, whereas secondary reactions seem to become important for higher molar masses. Nevertheless, model PDMS homopolymers with high molar masses can still be obtained increasing the reaction temperature and shortening the total reaction time. It seems that the combined effect of these two facts favors propagation against secondary reactions, and provides model PDMS homopolymers with molar masses quite close to the expected ones. © 2009 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 47: 4774–4783, 2009
Synthesis of imidazole‐containing conjugated polymers bearing phenol unit as side group and excited state intramolecular proton transfer‐mediated fluorescence
Authors: Takagi Koji , Sugihara Kenta , Isomura Takato 
Published: August 2009

AbstractDibromobenzimidazole and dibromoimidazole bearing hydroxyl group‐protected phenol unit (1 and 2) were prepared and they showed an intramolecular hydrogen bonding between ether oxygen and amino proton of imidazole. The palladium‐catalyzed Suzuki coupling polymerization of 1 and 2 with benzene bis(boronic acid) derivatives gave soluble polymers (3 and 4), where the molecular weights were limited probably due to the coordination ability of imidazole to palladium metal. The phenol hydroxyl groups were subsequently deprotected using BBr3 to obtain 3′ and 4′. From the 1H NMR spectra, the complete conversion to the hydroxyl group and the formation of another type of intramolecular hydrogen bonding between hydroxyl proton and imine nitrogen were confirmed. In the UV and PL spectra of 3′ and 4′, the excited state intramolecular proton transfer (ESIPT) occurred to shift the emission spectra toward lower energy region compared to 3 and 4. Especially, the PL spectrum of 3′ demonstrated large stokes shift (145 nm) in THF solution. The ESIPT‐mediated fluorescence was influenced by the addition of methanol and trifluoroacetic acid, which inhibited the formation of intramolecular hydrogen bonding. © 2009 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 47: 4822–4829, 2009
Plastic bronchitis as an unusual cause of mucus plugging in cystic fibrosis
Authors: Mateos‐Corral Dimas , Cutz Ernest , Solomon Melinda , Ratjen Felix 
Published: August 2009

AbstractCystic fibrosis patients are known to produce abundant, purulent sputum consisting mainly of DNA and cellular debris. We present a case of a CF patient with recurrent airway obstruction caused by a rare condition known as plastic bronchitis (PB). PB is characterized by the formation of casts of the airways that cause obstruction. Multiple etiologies have been proposed, but to our knowledge, no CF patient has been reported in any PB classification. Histological analysis and in‐vitro testing of the cast were important factors in choosing the adequate therapy in this patient. Pediatr Pulmonol. 2009; 44:939–940. © 2009 Wiley‐Liss, Inc.
Encouraging physical activity in pediatric asthma: A case–control study of the wonders of walking (WOW) program
Authors: Walders‐Abramson Natalie , Wamboldt Frederick S. , Curran‐Everett Douglas , Zhang Lening 
Published: August 2009

AbstractObjectivesThe complex overlap between asthma and obesity may be explained in part by activity avoidance in asthma. We compared responses to a walking intervention between matched groups of children with and without asthma. We expected youth with asthma to have lower baseline and post‐intervention activity levels. Psychosocial, demographic, and physiologic correlates of activity were also examined.Design/ParticipantsWe compared baseline and post‐intervention activity levels among 59 children aged 10–16 with well‐controlled asthma and 59 healthy matched controls. Participants completed spirometry, physical examination, anthropometric measurement, and psychosocial questionnaires.Intervention/Outcome MeasureParticipants wore blinded calibrated pedometers for a baseline typical activity week, returning to complete the Wonders of Walking (WOW) intervention, followed by a week of post‐intervention pedometer monitoring.ResultsContrary to expectation, no differences between cases (median steps = 6,348/day) and controls (median steps = 6,825/day) in baseline activity were found. Response to the WOW intervention was comparable, with both groups demonstrating an increase of approximately 1,485 steps per day (equivalent to more than 5 additional miles walked during the post‐intervention week). Health beliefs did not correlate to activity at baseline or intervention response. No significant associations between activity and asthma control, FEV1, or duration of diagnosis were found. Intervention response was comparable across racial/ethnic groups, children versus adolescents, and between normal weight and overweight youth.ConclusionsContrary to expectation, we found similar rates of objectively measured physical activity among youth with well‐controlled asthma and controls. Importantly, we documented statistically significant increases in physical activity across both groups following a brief, pedometer‐based intervention. The intervention was successful even among typically sedentary groups, and represents an effective, safe, and inexpensive walking program. Pediatr Pulmonol. 2009; 44:909–916. © 2009 Wiley‐Liss, Inc.
Microwave Properties of TATB Particles from Measurements of the Effective Permittivity of TATB Powders
Authors: Glover Brian B. , Perry W. Lee 
Published: August 2009

AbstractComplex permittivity is the constitutive property required to fully define the absorption, reflection, and transmission of microwave frequency electromagnetic energy for a non‐magnetic material. We report the complex permittivity of 1,3,5‐triamino‐2,4,6‐trinitrobenzene (TATB) powder from 1 to 18 GHz. The average complex permittivity of individual TATB particles was estimated from measurements of the complex permittivity of the powder at two different densities. TATB was found to have low permittivity, low dielectric loss with nearly constant valued permittivity between 1 and 18 GHz. These data are used to calculate the complex permittivity of a composite composed of TATB and Kel‐F 800.
RNA polymerase II flexibility during translocation from normal mode analysis
Authors: Feig Michael , Burton Zachary F. 
Published: August 2009

AbstractThe structural dynamics in eukaryotic RNA polymerase II (RNAPII) is described from computational normal mode analysis based on a series of crystal structures of pre‐ and post‐translocated states with open and closed trigger loops. Conserved modes are identified that involve translocation of the nucleic acid complex coupled to motions of the enzyme, in particular in the clamp and jaw domains of RNAPII. A combination of these modes is hypothesized to be involved during active transcription. The NMA modes indicate furthermore that downstream DNA translocation may occur separately from DNA:RNA hybrid translocation. A comparison of the modes between different states of RNAPII suggests that productive translocation requires an open trigger loop and is inhibited by the presence of an NTP in the active site. This conclusion is also supported by a comparison of the overall flexibility in terms of root mean square fluctuations. Proteins 2010. © 2009 Wiley‐Liss, Inc.
Evaluation of template‐based models in CASP8 with standard measures
Authors: Cozzetto Domenico , Kryshtafovych Andriy , Fidelis Krzysztof , Moult John , Rost Burkhard , Tramontano Anna 
Published: August 2009

AbstractThe strategy for evaluating template‐based models submitted to CASP has continuously evolved from CASP1 to CASP5, leading to a standard procedure that has been used in all subsequent editions. The established approach includes methods for calculating the quality of each individual model, for assigning scores based on the distribution of the results for each target and for computing the statistical significance of the differences in scores between prediction methods. These data are made available to the assessor of the template‐based modeling category, who uses them as a starting point for further evaluations and analyses. This article describes the detailed workflow of the procedure, provides justifications for a number of choices that are customarily made for CASP data evaluation, and reports the results of the analysis of template‐based predictions at CASP8. Proteins 2009. © 2009 Wiley‐Liss, Inc.
CASP8 results in context of previous experiments
Authors: Kryshtafovych Andriy , Fidelis Krzysztof , Moult John 
Published: August 2009

AbstractThe quality of structure models submitted to CASP8 is analyzed in the context of previous CASPs. To compare models from the latest experiment with their predecessors, we use the approaches consistent with the previous articles in this series. Using the basic evaluation measures accepted in CASP, there were no noticeable advances in the quality of the methods in any of the target difficulty categories. At the same time, there were three positive developments: (1) for set of the best models on each target, CASP8 registered the highest number of cases from all CASPs where alignment accuracy exceeded the maximum possible from the best template; (2) modeling accuracy of regions not present in the best template has improved; and (3) the loss in modeling quality from selection of nonoptimal models as the best ones submitted on the target has decreased. Proteins 2009. © 2009 Wiley‐Liss, Inc.