bluuebunny/crossref_metadata_2025_split huggingface dataset:
An investigation about solid equal channel angular extrusion on polypropylene/organic montmorillonite composite
Authors: Li Hong , Huang Xun , Huang Chengya , Zhao Yaoming 
Published: August 2011

AbstractThe solid equal channel angular extrusion (ECAE) process on polypropylene (PP)/organic montmorillonite (OMMT) was carried out. Scanning electron microscopy, polarized optical microscopy, transmission electron microscopy, and X‐ray diffraction were used to observe and characterize the samples structures. Experimental results show that both PP spherulites and OMMT particles were significantly deformed and orientated toward the shearing direction, and OMMT agglomeration particles were broken into needle‐like primary particles, some even exfoliated into nanosilicate layers after twice ECAE processes due to the immense solid shear force. This solid process approach introduces a new way to prepare PP/OMMT nanocomposites. The mechanism of exfoliation between PP and OMMT was also discussed. © 2011 Wiley Periodicals, Inc. J Appl Polym Sci, 2012
Mathematical modeling for the pultrusion of polymethyl methacrylate based composites
Authors: Chen Chin‐Hsing 
Published: August 2011

AbstractThe thermokinetic behavior of polymethyl methacrylate (PMMA)‐based composites during the pultrusion of glass fiber reinforced composites was investigated using a mathematical model accounting for the heat transfer and heat generation during the reaction. The equations of continuity and energy balance, coupled with a kinetic expression for the reaction system were solved using a finite difference method to calculate the temperature profiles in the thickness direction in a rectangular pultrusion die. A kinetic model,
$ {dP\over dt} = -\eta A_{o}{\rm exp}\left(-{E_{p}\over {\rm RT}}\right)$
$(2[I]_{o}- [Z]_{o})P^m \left(1- {P\over P_{f}} \right)^n(1-{\rm exp}(-k_{d}(t-t_{z})))$, was proposed to describe the reaction behavior of a PMMA resin. Kinetic parameters for the model were found from isothermal differential scanning calorimetry (DSC) scans using a multiple regression technique. The kinetic parameters ηAo = 1.459 × 109 min−1, Ep = 10.62 kcal/mol, m = 1.095, and n = 0.893 were obtained. The predictions of the model will be compared with experimental results. It can be found that the theoretical predicted values of temperature profiles along the pultrusion die length were in good agreement with experimental data, which implies that the mathematical model was suitable for the pultrusion processes. © 2011 Wiley Periodicals, Inc. J Appl Polym Sci, 2012
Information behavior and decision making in time‐constrained practice: A dual‐processing perspective
Authors: Allen David 
Published: August 2011

AbstractThis article reviews results from a research project designed to understand the mediating influence of information technology on information behavior. During the analysis of the data, five modes of information behavior were uncovered. These provide us with a reconceptualization of core information‐seeking and search activities, as well as a fruitful opening to redevelop, augment, or complement existing models of information behavior. The findings resonate with emerging theories of decision making and judgement and illustrate the need for information behavior researchers to undertake research in differing contexts. The work illuminates an issue of current concern for public policy: police use of information in decision making.
Semiparametric estimation in copula models for bivariate sequential survival times
Authors: Lawless Jerald F. , Yilmaz Yildiz E. 
Published: August 2011

AbstractSequentially observed survival times are of interest in many studies but there are difficulties in analyzing such data using nonparametric or semiparametric methods. First, when the duration of followup is limited and the times for a given individual are not independent, induced dependent censoring arises for the second and subsequent survival times. Non‐identifiability of the marginal survival distributions for second and later times is another issue, since they are observable only if preceding survival times for an individual are uncensored. In addition, in some studies a significant proportion of individuals may never have the first event. Fully parametric models can deal with these features, but robustness is a concern. We introduce a new approach to address these issues. We model the joint distribution of the successive survival times by using copula functions, and provide semiparametric estimation procedures in which copula parameters are estimated without parametric assumptions on the marginal distributions. This provides more robust estimates and checks on the fit of parametric models. The methodology is applied to a motivating example involving relapse and survival following colon cancer treatment.
A two‐part mixed‐effects pattern‐mixture model to handle zero‐inflation and incompleteness in a longitudinal setting
Authors: Maruotti Antonello 
Published: August 2011

AbstractTwo‐part regression models are frequently used to analyze longitudinal count data with excess zeros, where the same set of subjects is repeatedly observed over time. In this context, several sources of heterogeneity may arise at individual level that affect the observed process. Further, longitudinal studies often suffer from missing values: individuals dropout of the study before its completion, and thus present incomplete data records. In this paper, we propose a finite mixture of hurdle models to face the heterogeneity problem, which is handled by introducing random effects with a discrete distribution; a pattern‐mixture approach is specified to deal with non‐ignorable missing values. This approach helps us to consider overdispersed counts, while allowing for association between the two parts of the model, and for non‐ignorable dropouts. The effectiveness of the proposal is tested through a simulation study. Finally, an application to real data on skin cancer is provided.
Evaluation of the antioxidant activity of tetracycline antibiotics in vitro
Authors: Kładna Aleksandra , Michalska Teresa , Berczyński Paweł , Kruk Irena , Aboul‐Enein Hassan Y. 
Published: August 2011

ABSTRACTTetracyclines are the second most common antibiotic family in medicine usage. These antibiotics exhibit antioxidant potential; however, the exact mechanism remains unclear. The antiradical activity of the seven tetracyclines (TCs; tetracycline, chlortetracycline, oxytetracycline, doxocycline, methacycline, demeclocycline, minocycline) was determined using the free radical 2,2‐diphenyl‐1‐picrylhydrazyl (DPPH•) and hydroxyl radicals (HO•) generated in a Fenton reaction. Electron spin resonance (ESR), ESR spin‐trapping, chemiluminescence and spectrophotometry techniques were applied. It was found that the TCs showed high DPPH antiradical activity in the range 26–96% at 2.5 mmol/L concentration. The second‐order rate constants for the reaction between HO• and TCs were calculated, in the range (3.6–9.6) × 109 L/mol/s. The tetracycline compounds also exhibited a strong decrease in light emission (range 61–85% at concentration of 1 mmol/L). This study also showed that TCs promote the generation of singlet oxygen in the presence of and Fe(II)/Fe(III) ions. Our findings suggest direct scavenging activity of the examined tetracyclines towards free radicals, and may be relevant to therapeutic strategy. Copyright © 2011 John Wiley & Sons, Ltd.
Enzyme precipitate coatings of glucose oxidase onto carbon paper for biofuel cell applications
Authors: Fischback Mike , Kwon Ki Young , Lee Inseon , Shin Su Jeong , Park Hyun Gyu , Kim Byoung Chan , Kwon Yongchai , Jung Hee‐Tae , Kim Jungbae , Ha Su 
Published: August 2011

AbstractEnzymatic biofuel cells (BFC) have a great potential as a small power source, but their practical applications are being hampered by short lifetime and low power density. This study describes the direct immobilization of glucose oxidase (GOx) onto the carbon paper in the form of highly stable and active enzyme precipitation coatings (EPCs), which can improve the lifetime and power density of BFCs. EPCs were fabricated directly onto the carbon paper via a three‐step process: covalent attachment (CA), enzyme precipitation, and chemical crosslinking. GOx‐immobilized carbon papers via the CA and EPC approaches were used as an enzyme anode and their electrochemical activities were tested under the BFC‐operating mode. The BFCs with CA and EPC enzyme anodes produced the maximum power densities of 50 and 250 µW/cm2, respectively. The BFC with the EPC enzyme anode showed a stable current density output of >700 µA/cm2 at 0.18 V under continuous operation for over 45 h. When a maple syrup was used as a fuel under ambient conditions, it also produced a stable current density of >10 µA/cm2 at 0.18 V for over 25 h. It is anticipated that the direct immobilization of EPC on hierarchical‐structured electrodes with a large surface area would further improve the power density of BFCs that can make their applications more feasible. Biotechnol. Bioeng. 2012; 109:318–324. © 2011 Wiley Periodicals, Inc.
Randomized clinical trial of fibrin sealant versus titanium tacks for mesh fixation in laparoscopic umbilical hernia repair
Authors: Eriksen J R , Bisgaard T , Assaadzadeh S , Nannestad Jorgensen L , Rosenberg J 
Published: August 2011

Abstract

Background
The use of tacks for mesh fixation may induce pain after surgery for ventral hernia. The aim of this study was to compare postoperative pain after laparoscopic ventral hernia repair (LVHR) with conventional mesh fixation using titanium tacks versus fibrin sealant (FS).

Methods
This randomized clinical trial included patients with an umbilical hernia defect ranging from 1·5 to 5 cm at three Danish hernia centres. Participants were assigned randomly to FS or titanium tack fixation. The primary outcome was acute pain, defined as the mean pain score on days 0–2 after surgery, measured on a 0–100-mm visual analogue scale (VAS).

Results
Forty patients were included, of whom 38 were available for intention-to-treat analysis after 1 month. Patients in the FS group reported less pain than those in the tack group on days 0–2, both at rest (median 19 versus 47 mm; P = 0·025) and during activity (38 versus 60 mm; P = 0·014). The absolute difference in pain score between groups was 19 (95 per cent confidence interval 3 to 34) and 20 (4 to 35) mm at rest and during activity respectively. Patients in the FS group resumed normal daily activity earlier (after median 7 versus 18 days; P = 0·027) and reported significantly less discomfort. No recurrences were observed.

Conclusion
Mesh fixation with FS in LVHR was associated with less acute postoperative pain, discomfort and a shorter convalescence than tack fixation. Long-term follow-up is needed to show whether the effect of FS fixation persists in terms of chronic pain and recurrence. Registration number: NCT00842842 (http://www.clinicaltrials.gov).
Pathogenesis of postoperative adhesion formation
Authors: Hellebrekers B W J , Kooistra T 
Published: August 2011

Abstract

Background
Current views on the pathogenesis of adhesion formation are based on the ‘classical concept of adhesion formation’, namely that a reduction in peritoneal fibrinolytic activity following peritoneal trauma is of key importance in adhesion development.

Methods
A non-systematic literature search (1960–2010) was performed in PubMed to identify all original articles on the pathogenesis of adhesion formation. Information was sought on the role of the fibrinolytic, coagulatory and inflammatory systems in the disease process.

Results
One unifying concept emerged when assessing 50 years of studies in animals and humans on the pathogenesis of adhesion formation. Peritoneal damage inflicted by surgical trauma or other insults evokes an inflammatory response, thereby promoting procoagulatory and antifibrinolytic reactions, and a subsequent significant increase in fibrin formation. Importantly, peritoneal inflammatory status seems a crucial factor in determining the duration and extent of the imbalance between fibrin formation and fibrin dissolution, and therefore in the persistence of fibrin deposits, determining whether or not adhesions develop.

Conclusion
Suppression of inflammation, manipulation of coagulation as well as direct augmentation of fibrinolytic activity may be promising antiadhesion treatment strategies.
A strategy for extending the applicability of a validated plasma calibration curve to quantitative measurements in multiple tissue homogenate samples: a case study from a rat tissue distribution study of JI‐101, a triple kinase inhibitor
Authors: Gurav Sandip Dhondiram , Jeniffer Sherine , Punde Ravindra , Gilibili Ravindranath Reddy , Giri Sanjeev , Srinivas Nuggehally R , Mullangi Ramesh 
Published: August 2011

ABSTRACTA general practice in bioanalysis is that, whatever the biological matrix the analyte is being quantified in, the validation is performed in the same matrix as per regulatory guidelines. In this paper, we are presenting the applicability of a validated LC‐MS/MS method in rat plasma for JI‐101, to estimate the concentrations of JI‐101 in various tissues that were harvested in a rat tissue distribution study. A simple protein precipitation technique was used to extract JI‐101 and internal standard from the tissue homogenates. The recovery of JI‐101 in all the matrices was found to be >70%. Chromatographic separation was achieved using a binary gradient using mobile phase A (acetonitrile) and B (0.2% formic acid in water) at a flow rate of 0.30 mL/min on a Prodigy ODS column with a total run time of 4.0 min. The MS/MS ion transitions monitored were 466.1 → 265 for JI‐101 and 180.1 → 110.1 for internal standard. The linearity range was 5.02–4017 ng/mL. The JI‐101 levels were quantifiable in the various tissue samples harvested in this study. Therefore, the use of a previously validated JI‐101 assay in plasma circumvented the tedious process of method development/validation in various tissue matrices. Copyright © 2011 John Wiley & Sons, Ltd.
Validated high‐performance liquid chromatographic enantioseparation of selenomethionine using isothiocyanate based chiral derivatizing reagents
Authors: Bhushan Ravi , Dubey Rituraj 
Published: August 2011

ABSTRACTA high‐performance liquid chromatographic (HPLC) method for enantioseparation of selenomethionine (SeMet) was developed using two isothiocyanate‐based chiral derivatizing reagents [(R)‐methyl benzyl isothiocyanate (MBIC) and (S)‐1‐(1‐naphthyl) ethyl isothiocyanate (NEIC)] and UV detection. Diastereomers of selenomethionine were synthesized either via stirring (using MBIC) or by microwave irradiation (using NEIC). Derivatization conditions were optimized and the synthesized diastereomers were successfully resolved using triethyl ammonium phosphate buffer and acetonitrile on a reversed‐phase column. The method was validated for accuracy, precision and limit of detection. The mechanism of separation is also discussed. Copyright © 2011 John Wiley & Sons, Ltd.
Development and validation of a HPAE‐PAD method for the quantification of CGP69669A, a sialyl Lewisx mimetic, in skin permeation studies
Authors: Gratieri Taís , Wagner Beatrice , Kalaria Dhaval , Ernst Beat , Kalia Yogeshvar N. 
Published: August 2011

ABSTRACTA simple, rapid, precise and specific isocratic HPAE‐PAD method for quantification of CGP69669A was developed and validated. CGP69669A is a glycomimetic of sialyl Lewisx and an antagonist of E‐selectin with potential application in the treatment of inflammatory skin disease. Quantification was performed using a Dionex CarboPacTM PA‐200 anion‐exchange column (3 × 250 mm) with 100 mm NaOH solution as mobile phase, a flow rate of 0.50 mL/min and an injection volume of 10 μL. A quadruple potential waveform was used to detect the carbohydrate (+0.1 V from 0.00 to 0.40 s, −2.0 V from 0.41 to 0.42 s, +0.6 V at 0.43 s and −0.1 V from 0.44 to 0.50 s with current integrated between 0.20 and 0.40 s for detection) and rafinose was employed as an internal standard. The optimized conditions enabled rapid elution of CGP69669A (at 3.0 min) without interference from solvent peaks or substances present in the skin. The method showed good intra‐ and inter‐day precision and accuracy and the response was linear from 1.0 to 25 µg/mL. This is the first validated direct method for the quantification of CGP69669A. It will now be employed in studies investigating the topical and transdermal delivery of CGP69669A in vitro and in vivo and it should also be of use for other applications of this molecule. Copyright © 2011 John Wiley & Sons, Ltd.
Proteomic understanding of intracellular responses of recombinant chinese hamster ovary cells adapted to grow in serum‐free suspension culture
Authors: Baik Jong Youn , Ha Tae Kwang , Kim Young Hwan , Lee Gyun Min 
Published: August 2011

AbstractTo understand the intracellular responses in recombinant Chinese hamster ovary (rCHO) cells adapted to grow in serum‐free suspension culture, a proteomic approach was employed. After rCHO cells producing erythropoietin were adapted to grow in suspension culture with the two different serum‐free media (SFM4CHO™ and SF‐L1), proteome analyses were carried out using 2‐D PAGE and based on spot intensities, 58 high‐intensity protein spots were selected. Of the 58 protein spots, which represented 34 different kinds of proteins, 55 were identified by MALDI‐TOF‐MS, and MS/MS. Compared with the results in serum‐containing medium, six proteins, four de novo synthesis of nucleotides‐related proteins (dihydrolipoamide S‐acetyltransferase, transaldolase, inosine‐5′‐monophosphate dehydrogenase 2, and lymphoid‐restricted membrane protein) and two molecular chaperones (heat shock protein 70 kDa and 60 kDa [HSC70, HSP60]) were significantly increased in SFM4CHO™. From the results of proteomic analysis, HSP60 and HSC70, which were increased in both SFM, were selected as candidate proteins for engineering and rCHO cell lines overexpressing these genes were constructed. Cells overexpressing HSP60 and/or HSC70 showed 10–15% enhanced cell concentration during serum‐free adaptation and 15–33% reduction in adaptation time. Taken together, identification of differentially expressed proteins in rCHO cells by a proteomic study can provide insights into understanding the intracellular events and clues to find candidate genes for cell engineering for improved performance of rCHO cells during adaptation to serum‐free suspension culture. © 2011 American Institute of Chemical Engineers Biotechnol. Prog., 2011
Enzyme activity evaluation of organic solvent‐treated phenylalanine ammonia lyase
Authors: Quinn Andrew J. , Pickup Margaret J. , D'Cunha Godwin B. 
Published: August 2011

AbstractThe direct one‐step synthesis of L‐phenylalanine methyl ester in an organic‐aqueous biphasic system using phenylalanine ammonia lyase (E.C.4.3.1.5, PAL) containing Rhodotorula glutinis yeast whole cells was reported earlier. We report here further optimization of this biotransformation using isolated PAL, when the lyophilized enzyme is treated with different water miscible and water immiscible organic solvents. Use of isolated PAL enzyme is advantageous in overcoming diffusion barriers encountered when using PAL containing R. glutinis whole cells, and resulted in increased product yield due to better interaction of enzyme with the substrate. Among the water miscible solvents, ethanol treated and methanol treated enzymes supported maximum PAL forward and reverse activities; respectively. In the water immiscible solvents category, heptane‐treated enzyme exhibited maximal activity for both PAL forward and reverse reactions. PAL activity obtained with enzyme specimens treated with methanol, ethanol, and heptane varied in the range of 91–99% of that observed in aqueous buffer medium for the forward reaction; and 89–95% for the reverse reaction. n‐butanol, acetone, and benzene were found to have a inhibitory effect on PAL enzyme, in that, it resulted in only 31–33% activity of that obtained with aqueous solution. Raman spectroscopy was used to monitor amide I and II bands which are sensitive to changes in the secondary structure of proteins. No changes in structure could be detected from the analyses of AI and AII bands of PAL spectra. This data obtained for PAL, a tetramer, could be significant in predicting how solvent interactions affect the structure and function of multimeric proteins and enzymes in nonaqueous media. © 2011 American Institute of Chemical Engineers Biotechnol. Prog., 2011
Dynamic Multicomponent Hemiaminal Assembly
Authors: You Lei , Long S. Reid , Lynch Vincent M. , Anslyn Eric V. 
Published: August 2011

AbstractA simple approach to generating in situ metal‐templated tris‐(2‐picolyl)amine‐like multicomponent assemblies with potential applications in molecular recognition and sensing is reported. The assembly is based on the reversible covalent association between di‐(2‐picolyl)amine and aldehydes. Zinc ion is best for inducing assembly among the metal salts investigated, whereas 2‐picolinaldehyde is the best among the heterocyclic aldehydes studied. Although an equilibrium constant of 6.6×103 M−1 was measured for the assembly formed by 2‐picolinaldehdye, di‐(2‐picolyl)amine, and zinc triflate, the equilibrium constants for other systems are in the 102 M−1 range. X‐ray structural analysis revealed that zinc adopts trigonal‐bipyramidal geometry within the assembled ligand. The diversity and equilibrium of the assemblies are readily altered by simply changing concentrations, varying components, or adding counteranions.
SrP3N5O: A Highly Condensed Layer Phosphate Structure Solved from a Nanocrystal by Automated Electron Diffraction Tomography
Authors: Sedlmaier Stefan J. , Mugnaioli Enrico , Oeckler Oliver , Kolb Ute , Schnick Wolfgang 
Published: August 2011

AbstractThe oxonitridophosphate SrP3N5O has been synthesized by heating a multicomponent reactant mixture that consisted of phosphoryl triamide OP(NH2)3, thiophosphoryl triamide SP(NH2)3, SrS, and NH4Cl enclosed in evacuated and sealed silica‐glass ampoules up to 750 °C. The compound was obtained as nanocrystalline powder with needle‐shaped crystallites. The crystal structure was solved ab initio on the basis of electron diffraction data by means of automated electron diffraction tomography (ADT) and verified by Rietveld refinement with X‐ray powder diffraction data. SrP3N5O crystallizes in the orthorhombic space group Pnma (no. 62) with unit‐cell data of a=18.331(2), b=8.086(1), c=13.851(1) Å and Z=16. The compound is a highly condensed layer phosphate with a degree of condensation κ=1/2. The corrugated layers ${{{\hfill 2\atop \hfill \infty }}}${(P3N5O)2−} consist of linked, triangular columns built up from P(O,N)4 tetrahedra with 3‐rings and triply binding nitrogen atoms. The Sr2+ ions are located between the layers and exhibit six‐, eight‐, and ninefold coordination. FTIR and solid‐state NMR spectra of SrP3N5O are discussed as well.
Preparation of Mononuclear, Homodinuclear, and Heterotrinuclear Complexes by Salicylaldiminato‐Functionalized Imidazolium Salt: Approach to Multifunctional Catalysts
Authors: Zhong Rui , Wang Ya‐Nong , Guo Xu‐Qing , Chen Zhen‐Xia , Hou Xiu‐Feng 
Published: August 2011

AbstractA salicylaldiminato imidazolium salt that bears both a Schiff base and imidazolium salt moiety was used to synthesize heterometallic compounds that could serve as multifunctional catalysts in certain reactions. The successful preparation of seven mononuclear compounds with a variety of transition metals (Pd, Ir, Ru, Zn, Ni) illustrated the high versatility of this class of ligands, which is crucial for the design of catalysts. Synthesis of homodinuclear compounds and heterotrinuclear compounds provided practical methods to connect multiple metal fragments through these ligands. The heterotrinuclear complex (Ni/Ir) was employed as a catalyst in the reaction of dehalogenation/transfer hydrogenation of halo‐acetophenones. The preliminary catalytic study showed that this heterometallic species is more active than a combination of the corresponding monometallic species.