bluuebunny/crossref_metadata_2025_split huggingface dataset:
Numerical simulation on freezing phase change heat transfer in cryosurgery with two cryoprobes
Authors: Zhao Fang , Chen Zhenqian , Shi Mingheng 
Published: January 2011

AbstractA mathematical model for phase change heat transfer in biological tissue (including tumor and normal tissue) embedded with two cryoprobes was established. In this model, the vascular architecture was described as a tree‐like branched fractal network, and the effective thermal conductivity and flow rate of blood were presented based on this fractal structure. Occurrence of three regions including frozen, phase‐changing, and unfrozen regions in biological tissue during the freezing process was also considered. The numerical studies on temperature distribution and ice crystal growth process in biological tissue embedded with two cryoprobes were performed. The results showed that the growth rate of ice crystal is more rapid in the initial freezing stage and becomes slower later. So it is unreasonable to prolong freezing time merely without other assisting measures for enlarging the freezing region in the late freezing stage. Furthermore, the placement distance of the two cryoprobes plays a significant role in the growth of ice crystal in the initial freezing stage, and the influence of different distances between two probes on ice crystal growth becomes less profound with an increasing of freezing time. © 2011 Wiley Periodicals, Inc. Heat Trans Asian Res; Published online in Wiley Online Library (wileyonlinelibrary.com). DOI 10.1002/htj.20332
Curbing domestic violence: instantiating C–K theory with formal concept analysis and emergent self‐organizing maps
Authors: Poelmans Jonas , Elzinga Paul , Viaene Stijn , Dedene Guido 
Published: January 2011

AbstractWe propose a human‐centred process for knowledge discovery from unstructured text that makes use of formal concept analysis and emergent self‐organizing maps. The knowledge discovery process is conceptualized and interpreted as successive iterations through the concept–knowledge (C–K) theory design square. To illustrate its effectiveness, we report on a real‐life case study of using the process at the Amsterdam–Amstelland police in the Netherlands aimed at distilling concepts to identify domestic violence from the unstructured text in actual police reports. The case study allows us to show how the process was not only able to uncover the nature of a phenomenon such as domestic violence, but also enabled analysts to identify many types of anomaly in the practice of policing. We will illustrate how the insights obtained from this exercise resulted in major improvements in the management of domestic violence cases. Copyright © 2010 John Wiley & Sons, Ltd.
Polysorbate cationic synthetic vesicle for gene delivery
Authors: Huang Yongzhuo , Rao Yuefeng , Chen Jinliang , Yang Victor C. , Liang Wenquan 
Published: January 2011

AbstractSynthetic nonionic surfactant vesicles (niosomes) are a colloidal system with closed bilayer structures, displaying distinct advantages in stability and cost compared with liposomes. In this article, polysorbate cationic niosomes (PCNs) were developed as gene carriers. The PCNs comprised nonionic surfactants (i.e., polysorbates) and a cationic cholesterol, and were synthesized using a film hydration method. The niosomes thus prepared possessed a regular morphology, and a particle size of 100 ∼ 200 nm, and a zeta potential of +30 ∼ 45 mV. The PCNs showed great physical stability over the course of 4 weeks at room temperature. The binding capacity of PCNs toward oligodeoxynucleotides (ODN) was assessed by a gel retardation approach, which demonstrated that the ionic complexes were formed when ± charge ratio reached to 4 or greater. Gene transfer study showed that the PCNs exhibited a high efficiency in mediating cellular uptake and transferred DNA expression. Based on these findings, PCNs may offer the potential to function as an effective gene delivery system. © 2011 Wiley Periodicals, Inc. J Biomed Mater Res Part A:, 2011.
The significance of repetitive hair‐pulling behaviors in eating disorders
Authors: Zucker Nancy , Von Holle Ann , Thornton Laura M. , Strober Michael , Plotnicov Kathy , Klump Kelly L. , Brandt Harry , Crawford Steve , Crow Scott , Fichter Manfred M. , Halmi Katherine A. , Johnson Craig , Kaplan Allan S. , Keel Pamela , LaVia Maria , Mitchell James E. , Rotondo Alessandro , Woodside D. Blake , Berrettini Wade H. , Kaye Walter H. , Bulik Cynthia M. 
Published: January 2011

AbstractWe studied the relation between intrusive and repetitive hair pulling, the defining feature of trichotillomania, and compulsive and impulsive features in 1,453 individuals with anorexia nervosa and bulimia nervosa. We conducted a series of regression models examining the relative influence of compulsive features associated with obsessive‐compulsive disorder, compulsive features associated with eating disorders, trait features related to harm avoidance, perfectionism, and novelty seeking, and self harm. A final model with a reduced sample (n = 928) examined the additional contribution of impulsive attributes. One of 20 individuals endorsed hair pulling. Evidence of a positive association with endorsement of compulsive behavior of the obsessive‐compulsive spectrum emerged. Hair pulling may be more consonant with ritualistic compulsions than impulsive urges in those with eating disorders. © 2011; Wiley Periodicals, Inc. J Clin Psychol 00:1–13, 2011.
Sorbent coatings for solid‐phase microextraction based on mixtures of polymeric ionic liquids
Authors: Graham Christa M. , Meng Yunjing , Ho Tien , Anderson Jared L. 
Published: January 2011

AbstractFour polymeric ionic liquids based on two different cations, poly(1‐vinyl‐3‐hexylimidazolium) and poly(1‐vinyl‐3‐hexadecylimidazolium), combined with two different anions, bis[(trifluoromethyl)sulfonyl]imide (NTf) and chloride (Cl−), were combined in various weight percentages and used as sorbent coatings for solid‐phase microextraction gas chromatography (SPME‐GC). The selectivity of the fiber coatings for 12 test analytes was examined. The extraction efficiency of n‐alcohols increased with an increase in the weight percentage of chloride ion in the sorbent coating. The ability to tune the interactions between the coating material and the analytes was exploited and resulted in distinct changes in the limits of detection for hydrogen‐bonding analytes with varying chloride ion content in the sorbent coating.
Preparation of novel polydimethylsiloxane solid‐phase microextraction film and its application in liquid sample pretreatment
Authors: Wei Fang , Zhang Fang‐Fang , Liao Hui , Dong Xu‐Yan , Li Yan‐Hua , Chen Hong 
Published: January 2011

AbstractIn this paper, an extraction approach based on the use of a novel polydimethylsiloxane (PDMS) film as the extraction medium was described. Two kinds of PDMS films with smooth surface and frosted surface were prepared and were practically evaluated for extraction. A model analytical problem, the determination of organochlorine pesticides in water samples, was selected for practical evaluation of the film extraction procedure by direct extraction and solvent desorption, followed by gas chromatography (GC) analysis with electron capture detection (ECD). The main variables affecting the extraction process such as the extraction time, the extraction temperature, the elution conditions, etc. were studied. The method was characterized on the basis of its linearity, precision, and limits of detection. The novel approach was sensitive and precise enough for the detection of the target analytes in the low nanogram per liter range using 5 mL of sample. In fact, limits of detection ranging from 0.77 to 10.25 ng/L were obtained. Compared with the solid‐phase microextraction (SPME) fiber, the robust extraction film has a large extraction capacity, low cost of preparation. Besides, owing to the simplicity of the extraction procedures, in‐site sample preparation for environmental monitor may be realized.
Prediction of pesticides chromatographic lipophilicity from the computational molecular descriptors
Authors: Casoni Dorina , Petre Jana , David Victor , Sârbu Costel 
Published: January 2011

AbstractQuantitative structure–property relationship models were developed for the prediction of pesticides and some PAH compounds lipophilicity based on a wide set of computational molecular descriptors and a set of experimental chromatographic data. The chromatographic lipophilicity of pesticides has been evaluated by high‐performance liquid chromatography (HPLC) using different chemically bonded (C18, C8, CN and Phenyl HPLC columns) stationary phases and two different organic modifiers (methanol and acetonitrile, respectively) in the mobile phase composition. Through a systematic study, by using the classic multivariate analysis, several quantitative structure–property/lipophilicity multi‐dimensional models were established. Multiple linear regression and genetic algorithm for the variable subset selection were used. The internal and external statistical evaluation procedures revealed some appropriate models for the chromatographic lipophilicity prediction of pesticides. Moreover, the statistical parameters of regression and those obtained by applying t‐test for the intercept (a0) and for the slope (a1) in order to evaluate relationship between experimental and predicted octanol–water partition coefficients in case of the test set compounds, revealed two statistically valid models that can be successfully used in lipophilicity prediction of pesticides.
Qualitative and quantitative determination of nine main active constituents in Pulsatilla cernua by high‐performance liquid chromatography coupled to electrospray ionization tandem mass spectrometry
Authors: Xu Huijun , Shi Xiaowei , Ji Xiang , Du Yingfeng , Zhu Hong , Zhang Lantong 
Published: January 2011

AbstractA novel qualitative and quantitative method using high‐performance liquid chromatography coupled to electrospray ionization tandem mass spectrometry (HPLC‐ESI‐MS/MS) was developed for simultaneous determination of the nine major active constituents in Pulsatilla cernua (Thunb.) Bercht. et Opiz., namely anemoside A3 (1), anemoside B4 (2), 23‐hydroxybetulinic acid (3), cirenshenoside S (4), pulsatilloside B (5), pulsatilloside C (6), oleanolic acid (7), ajugasterone C (8) and β‐ecdysterone (9), respectively. A Sapphire C18 column (250 mm×4.6 mm, 5 μm) and gradient elution were used during the analysis. The identification and quantification of the analytes were achieved on a hybrid quadrupole linear ion trap mass spectrometer. Multiple‐reaction monitoring (MRM) scanning was employed for quantification with switching electrospray ion source polarity between positive and negative modes in a single run. All calibration curves showed good linearity (r2>0.9948) within the test ranges. The intra and interday variations for nine analytes were less than 3.95 and 3.78%, respectively. The developed method was successfully applied to determine the investigated compounds in 15 batches of natural and cultured samples of P. cernua. The results indicated that the method was simple, rapid, specific and reliable, which is helpful to comprehensive evaluation of quality of P. cernua.
Retention prediction in reversed‐phase liquid chromatography systems with methanol/water mobile phases containing different alkanols as additives
Authors: Pappa‐Louisi Adriani , Agrafiotou Panagiota , Fasoula Stella 
Published: January 2011

AbstractIn an effort to gain enhancement of selectivity in reversed‐phase liquid chromatography, retention was tuned in this study by introducing short and medium straight‐chained‐length alkanol additives (methanol (MeOH), ethanol, 1‐propanol, 1‐butanol, 1‐pentanol, 1‐hexanol or 1‐heptanol) at low concentrations in mobile phases containing MeOH as the main organic solvent. A six‐parameter retention model considering simultaneously the contents of the main organic modifier and of the alcohol additive as well as of the number of alkyl chain of additive was developed by a direct combination of equations expressing separately a linear dependence of the retention upon each of these factors. The effectiveness of the above model was tested in the retention prediction of a mixture of six alkylbenzenes under isocratic conditions with mobile phases containing as an additive any member of the homologues series of alkanols (with 1–7 carbon atoms) at different low concentrations in a wide range of MeOH–water mixtures. The prediction was excellent in all cases even when the alkanol additives used in experiments for the fitting procedure are different than those used in chromatographic runs done for testing the prediction ability of the proposed model.
Preparative separation of quaternary ammonium alkaloids from Corydalis yanhusuo W. T. Wang by pH‐zone‐refining counter‐current chromatography
Authors: Yu Qing , Tong Shengqiang , Yan Jizhong , Hong Chaoqun , Zhai Wenfeng , Li Yaqin 
Published: January 2011

AbstractThe optimal extraction condition for extracting quaternary ammonium alkaloid dehydrocorydaline from Corydalis yanhusuo W. T. Wang was investigated using orthogonal experimental design. pH‐zone‐refining counter‐current chromatography (CCC) with normal phase elution was successfully applied to preparative separation of alkaloids from the crude extract of Corydalis yanhusuo. The separation was performed with a biphasic solvent system composed of chloroform (CHCl3)–methanol (MeOH)–water (2:1:1, v/v), in which the lower organic phase containing 10 mM of triethylamine was used as the mobile phase, while the upper aqueous phase containing 10 mM of hydrochloric acid was used as the stationary phase. The separation mechanism of quaternary ammonium alkaloids using pH‐zone‐refining CCC was discussed in comparison with standard high‐speed CCC. In the present study, the separation of 1.200 g of crude sample yielded 129 mg of dehydrocorydaline and 12 mg of palmatine at a high purity of 94 and 92%, respectively. Recovery for dehydrocorydaline and palmatine was 85 and 86%, respectively.
Revisiting MacCannell's site sacralization theory as an analytical tool: Historic prophetstown as a case study
Authors: Forristal Linda Joyce , Marsh Dawn Gay , Lehto Xinran Y. 
Published: January 2011

AbstractHistoric Prophetstown in Battle Ground, Indiana is intrinsically connected to a pivotal event in Native American and United States military history. While it appears to have all the necessary elements to become a successful tourism attraction, it consistently teeters on the verge of insolvency. Applying sociologist Dean MacCannell's (1976) five‐stage site sacralization theory as an analytical lens to investigate the site revealed that it has never successfully moved beyond MacCannell's first stage (i.e. naming), which may be a key factor contributing to low visitation and poor economic performance. This suggests that MacCannell's theory can offer unique insights into site development. Copyright © 2010 John Wiley & Sons, Ltd.
Polymerisation of Norbornene Catalysed by Highly Active Tetradentate Chelated α‐Diimine Nickel Complexes
Authors: Li Lidong , Gomes Pedro T. , Lemos M. Amélia N. D. A. , Lemos Francisco , Fan Zhiqiang 
Published: January 2011

AbstractA series of three recently synthesised tetradentate chelated α‐diimine nickel complexes of the type [NiBr2(Ar‐BIAN)] (where Ar = 2‐(1‐R‐1H‐1,2,3‐triazol‐4‐yl)phenyl; R = benzyl 1, 1‐phenylethyl 2, phenyl 3) are used as precatalysts for the polymerisation of norbornene. When activated with MAO, 1–3 are highly active catalysts for the production of high molecular weight polynorbornene (e.g., 1.39 × 107 g PNB mol Ni−1 · h−1). The catalytic activity and polymer molecular weight increase markedly with the initial concentration of norbornene, but both parameters decrease with the reaction time. The characterisation of the polynorbornenes by NMR, GPC/SEC, X‐ray diffraction, and DSC/TGA leads to the assignment of a structure typical of a polynorbornene originated by a coordination vinyl addition mechanism.
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Use of Reactive and Functional Hydrophobes (Hydrophobins) in the Miniemulsion Polymerization of Styrene and Methyl Methacrylate
Authors: Agarwal Seema , Grabe Norman 
Published: January 2011

AbstractThe successful use of multitasking polycaprolactone‐based hydrophobins for miniemulsion polymerization of model monomers like styrene and methyl methacrylate is demonstrated. These hydrophobins were synthesized in two steps – the synthesis of polyester diol (i.e., polycaprolactone diol) followed by polycondensation with an equimolar amount of azobis(cyanopentanoic acid dichloride). The hydrophobin, besides acting as a hydrophobe and initiator for the miniemulsion polymerization, also provided functionality; in this case degradability to the miniemulsion. An optimum ratio of hydrophobin to monomer was required for making stable dispersions of a small size (average diameter around 100 nm) with relatively high solid content (around 22%). magnified image
Association of a Cylindrical Polyelectrolyte Brush with Tetravalent Counterions
Authors: Ruthard Christian , Maskos Michael , Yildiz Hakan , Gröhn Franziska 
Published: January 2011

AbstractCylindrical poly(styrene sulfonate) brushes were combined with a tetravalent double‐DABCO based counterion. With increasing addition of counterion, hydrodynamic radius and radius of gyration decrease and AFM reveals a conformation change from wormlike to curled structures. Rg/Rh changes from 1.3 to 0.9. Above charge stoichiometry, brushes become interconnected into finite size assemblies, which are stable in aqueous solution for charge ratios (ratio of the molar concentration of charged counterion groups to the molar concentration of charged monomer units of the polymer brush) 1 < l < 1.2. They are compact and consist of the brushes in curled (bent) conformation, which is in difference to network‐like aggregates from cylindrical poly(styrene sulfonate) brushes with tetravalent porphyrin counterions (Gröhn et al. Macromolecules 2009) and to a wormlike—bent conformation—helix transition found for another brush counterion system (Müller et al. Soft Matter 2009).
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Tailored Polymer Microstructures Prepared by Atom Transfer Radical Copolymerization of Styrene and N‐substituted Maleimides
Authors: Lutz Jean‐François , Schmidt Bernhard V. K .J. , Pfeifer Sebastian 
Published: January 2011

AbstractIn the present Feature Article, a kinetic strategy for controlling the microstructure of synthetic polymer chains prepared via a radical chain‐growth polymerization process is presented. This approach was recently developed in our laboratory and relies on the controlled kinetic addition of ultrareactive N‐substituted maleimides during the atom transfer radical polymerization of styrene. This method is experimentally straightforward and can be applied to a broad library of functional N‐substituted maleimides. Thus, this platform allows synthesis of unprecedented polymer materials such as 1D macromolecular arrays. The basic kinetic requirements, the experimental conditions, and the synthetic scope of this approach are discussed in details herein.
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Functionalization of Hydrogels Based on N‐Isopropyl‐acrylamide and Cationic Surfactant Monomers upon Electrostatic Self‐Assembly
Authors: Friedrich Tatjana , Trinker Anna , Tieke Bernd 
Published: January 2011

AbstractSummary: Positively charged copolymer hydrogels based on N‐isopropyl‐acrylamide (NiPAAm) and a cationic surfactant monomer (surfmer) were functionalized upon electrostatic self‐assembly of functional organic or inorganic complex counterions in the gel. As cationic surfmers 11‐acryloylundecyltrimethylammonium bromide (AUTMAB) or 11‐methacryloyl‐undecyltrimethylammonium bromide (MUTMAB) were used. The hydrogels were prepared from a micellar aqueous solution of the surfmer and NiPAAm either upon 60Co‐gamma irradiation, or upon chemical cross‐linking using methylenebisacrylamide as cross‐linker and 1,4‐diaminobutane as accelerator. Electrostatic self‐assembly was facilitated utilizing the thermoresponsive swelling and shrinking of the hydrogel. Several examples of gel functionalization are described such as in‐situ preparation of Prussian Blue and Pd0 nanoparticles, and induction of fluorescent properties. The catalytic activity of the palladium‐containing gel was studied by investigating the reduction of 4‐nitrophenol (4‐NP) with sodium borohydride as a model reaction. Fluorescent gels can be prepared upon exchange of bromide against 1‐pyrenesulfonate ions in the gel.
3D Stereolithography by Using Two‐Photon Photopolymerization
Authors: Kim Ran Hee , Lee Kwang‐Sup 
Published: January 2011

AbstractSummary: This article describes the development and evolution of two‐photon lithography of 3‐dimensional (3D) polymeric structures through two‐photon photopolymerization (TPP) and the materials used to facilitate the same. The first part elaborates on the advantages of TPP over conventional lithographic techniques used in the fabrication of 3D microelectromechanical systems (MEMS). The second part introduces the preparation of highly efficient organic two‐photon absorbing materials based on the centro‐symmetric π‐conjugated system and their performance as sensitizers in two‐photon polymerization.
Small‐Molecule Diffusion in Semicrystalline Polymers as Revealed by Experimental and Simulation Studies
Authors: Nilsson Fritjof , Hedenqvist Mikael S. , Gedde Ulf W. 
Published: January 2011

AbstractSummary: Diffusion of n‐hexane in poly(ethylene‐co‐1‐hexene)s with 15–75 wt.% crystallinity was studied by desorption experiments analyzing data using the Fickian equations with a concentration dependent diffusivity. The effect of the impenetrable crystalline phase on the penetrant diffusivity (D) is described by D = Da/(τβ), where Da is the diffusivity of the amorphous polymer, τ is the geometrical impedance factor and β is a factor describing the constraining effect of the crystals on the non‐crystalline phase. For a polymer with 75 wt.% crystallinity, τβ varied markedly with penetrant concentration (v1a) in the penetrable phase: 1000 (v1a = 0) and 10 (v1a = 0.15). This penetrant‐uptake had no effect on the gross crystal morphology, i.e. β must be strongly dependent on v1a. Samples saturated in n‐hexane exhibited a penetrant‐induced loosening of the interfacial structure, as revealed by an increase in crystal density that require an increased mobility in the interfacial component and by a decrease in the intensity of the asymmetric X‐ray scattering associated with the interfacial component. The geometrical impedance factor has been modelled by mimicking spherulite growth and τ was obtained as the ratio of the diffusivities of the fully amorphous and semicrystalline systems. The maximum τ obtained from these simulations is ca. ten, which suggests that β in the systems with v1a = 0.15 takes values close to unity. The simulations showed that the geometrical impedance factor is insensitive to the ratio of the crystal width and the crystal thickness. A free path length scaling parameter characteristic of the amorphous phase correlated with τ.