bluuebunny/crossref_metadata_2025 huggingface dataset:
Comparison of calibrated and uncalibrated arterial pressure–based cardiac output monitors during orthotopic liver transplantation
Authors: Krejci Vladimir , Vannucci Andrea , Abbas Alhan , Chapman William , Kangrga Ivan M.
Published: March 2010

Arterial pressure–based cardiac output monitors (APCOs) are increasingly used as alternatives to thermodilution. Validation of these evolving technologies in high-risk surgery is still ongoing. In liver transplantation, FloTrac-Vigileo (Edwards Lifesciences) has limited correlation with thermodilution, whereas LiDCO Plus (LiDCO Ltd.) has not been tested intraoperatively. Our goal was to directly compare the 2 proprietary APCO algorithms as alternatives to pulmonary artery catheter thermodilution in orthotopic liver transplantation (OLT). The cardiac index (CI) was measured simultaneously in 20 OLT patients at prospectively defined surgical landmarks with the LiDCO Plus monitor (CIL) and the FloTrac-Vigileo monitor (CIV). LiDCO Plus was calibrated according to the manufacturer's instructions. FloTrac-Vigileo did not require calibration. The reference CI was derived from pulmonary artery catheter intermittent thermodilution (CITD). CIV-CITD bias ranged from −1.38 (95% confidence interval = −2.02 to −0.75 L/minute/m2, P = 0.02) to −2.51 L/minute/m2 (95% confidence interval = −3.36 to −1.65 L/minute/m2, P < 0.001), and CIL-CITD bias ranged from −0.65 (95% confidence interval = −1.29 to −0.01 L/minute/m2, P = 0.047) to −1.48 L/minute/m2 (95% confidence interval = −2.37 to −0.60 L/minute/m2, P < 0.01). For both APCOs, bias to CITD was correlated with the systemic vascular resistance index, with a stronger dependence for FloTrac-Vigileo. The capability of the APCOs for tracking changes in CITD was assessed with a 4-quadrant plot for directional changes and with receiver operating characteristic curves for specificity and sensitivity. The performance of both APCOs was poor in detecting increases and fair in detecting decreases in CITD. In conclusion, the calibrated and uncalibrated APCOs perform differently during OLT. Although the calibrated APCO is less influenced by changes in the systemic vascular resistance, neither device can be used interchangeably with thermodilution to monitor cardiac output during liver transplantation. Liver Transpl 16:773-782, 2010. © 2010 AASLD.
Short‐term oxidation and hot corrosion resistance of a gradient CrN/Cr1−xAlxN coating
Authors: Zhu M. , Li M. S. , Xu J. J. , Zhou Y. C.
Published: March 2010

A CrN/Cr1−xAlxN coating comprised of an inner layer of CrN and an outer layer of Cr1−xAlxN with a gradient distribution of Al was deposited on two different alloys by a reactive sputtering method. Oxidation and hot‐corrosion tests of the gradient CrN/Cr1−xAlxN coating were performed at different temperatures. The phase compositions and morphologies of the as‐deposited coating and the corrosion products were investigated by using XRD and SEM/EDS. The results showed that the gradient CrN/Cr1−xAlxN coating exhibited good oxidation resistance at temperatures above 1000 °C owing to the formation of an α‐Al2O3‐rich oxide scale. The coating possessed good hot‐corrosion resistance in molten sulfate because the inner CrN layer could supply enough Cr to form a relatively protective Cr2O3 after the Al2O3‐enriched scale failed due to its dissolution in the molten sulfate.
Corrosion study of the X52 steel immersed in seawater with a corrosion inhibitor using a rotating cylinder electrode
Authors: Galvan‐Martinez R. , Orozco‐Cruz R. , Torres‐Sanchez R. , Martinez E. A.
Published: March 2010

A corrosion study of API X52 steel was carried out in natural seawater with several concentrations of a corrosion inhibitor (10, 100 and 200 ppm) using a rotating cylinder electrode (RCE) to control the hydrodynamic conditions at environment temperature, atmospheric pressure and 24 h of the exposition time. The rotation speed used was 1000 rpm (turbulent flow). The electrochemical techniques used in the corrosion studies were: linear polarisation resistance (LPR), electrochemical impedance spectroscopy (EIS) and polarisation curves (PCs). The superficial analysis was made using a scanning electron microscope (SEM). The results show a good correlation between electrochemical techniques used. In addition, under turbulent flow, the test solution with 10 ppm had the smallest corrosion rate (CR). It is important to mention that the morphology of the corrosion in all experiments was localised corrosion.
Crude unit overhead corrosion — pH profile and corrosion rate of carbon steel under controlled condensation
Authors: Cypriano D. L. N. , Ponciano J. A. C. , Jambo H. C. M.
Published: March 2010

For this paper a laboratory simulation of the crude unit overhead corrosion was conducted. The main variable that impacts the corrosion rates for pipes, heat exchangers, and drums that compound the overhead system is pH. To control this pH many companies use different kinds of neutralizers, trying to keep in an optimum range, determined for each unit, according to their own characteristics. For this study an apparatus that simulate the evaporation and subsequent condensation of a solution with hydrochloric acid and other with neutralizer, with five carbon steel coupons analyzed by metal mass‐loss was used. To compare to field practices, three kinds of neutralizer solutions were used. It was possible to observe differences between the pH profiles along condensation, which certainly influences the corrosion rate from the first condensed solution until the last one. It can be compared with the process at the atmospheric tower, from the overhead pipe, passing by the condenser until the drum that accumulates sour water at the end. In this last one the pH is usually measured, but it cannot represent what we could observe with this laboratory apparatus, that the first solution condensed is the worst for corrosion, and that there is a direct relationship between them.
Optical Characterization of Co‐Nonsolvency Effects in Thin Responsive PNIPAAm‐Based Gel Layers Exposed to Ethanol/Water Mixtures
Authors: Anac Ilke , Aulasevich Alena , Junk Matthias J. N. , Jakubowicz Piotr , Roskamp Robert F. , Menges Bernhard , Jonas Ulrich , Knoll Wolfgang
Published: March 2010

Surface‐attached, photo‐crosslinked gel films of a N‐isopropylacrylamide copolymer were investigated in ethanol/water mixtures using a combination of surface plasmon resonance/optical waveguide spectroscopy with reversed WKB analysis. The solvent quality of the pure good solvents drops in their mixture and this co‐nonsolvency effect shifts the transition temperature (Tc) in the µm‐thin gel films from 32.8 °C in pure water to 29.7 °C with only 0.25 vol.‐% ethanol. Between 20 and 70% ethanol and >10 °C (the practical temperature limit) the layers existed only in the collapsed state. A reentrant Tc of 40.2 °C was found at 70% ethanol while at higher ethanol volume fraction no Tc could be recorded.

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Brush‐Like Amphoteric Poly[isobutylene‐alt‐(maleic acid)‐graft‐oligoethyleneamine)]/DNA Complexes for Efficient Gene Transfection
Authors: Khan Majad , Beniah Goliath , Wiradharma Nikken , Guo XinDong , Yang Yi Yan
Published: March 2010

Synthetic gene delivery vectors, especially cationic polymers have attracted enormous attention in recent decades because of their ease of manufacture, targettability, and scaling up. However, certain issues such as high cytotoxicity and low transfection efficiency problems have hampered the advance of nonviral gene delivery. In this study, we designed and synthesized brush‐like amphoteric poly[isobutylene‐alt‐(maleic acid)‐graft‐oligoethyleneamine] capable of mediating highly efficient gene transfection. The polymers are composed of multiple pendant oligoethyleneimine molecules with alternating carboxylic acid moiety grafted onto poly[isobutylene‐alt‐(maleic anhydride)]. The polymer formed from pentaethylenehexamine {i.e., poly[isobutylene‐alt‐(maleic acid)‐graft‐pentaethylenehexamine)]} was able to condense DNA efficiently into nanoparticles of size around 200 nm with positive zeta potential of about 28–30 mV despite its amphoteric nature. Luciferase expression level and percentage of GFP expressing cells induced by this polymer was higher than those mediated with polyethyleneimine (branched, $\overline M _{\rm w} $ 25 kDa) by at least one order of magnitude at their optimal N/P ratios on HEK293, HepG2, and 4T1 cells. In vitro cytotoxicity testing revealed that the polymer/DNA complexes were less cytotoxic than those of PEI, and the viability of the cells after being incubated with the polymer/DNA complexes at the optimal N/P ratios was higher than 85%. This polymer can be a promising gene delivery carrier for gene therapy.

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Interconversion of Planar Networks and Vesicles Triggered by Temperature
Authors: Lee Eunji , Kim Jung‐Keun , Lee Myongsoo
Published: March 2010

Dumbbell‐shaped amphiphiles based on an elongated rod segment can self‐assemble into planar networks with in‐plane hexagonally ordered pores in aqueous solution. On increasing temperature, the 2D networks change into hollow capsules passing through the closed sheets as an intermediate structure due to a LCST behavior of the oligoether dendritic exterior. The primary driving force for this interesting feature seems to originate from a consequence of the energy balance between hydrophobic interactions of anisotropic rod segments and alkyl chains, and repulsive interactions between dissimilar blocks. This dynamic structural variation triggered by external stimuli in a self‐assembling system can provide a useful strategy to create smart supramolecular materials and biomimetic systems.

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Valuation of health states in the US study to establish disability weights: lessons from the literature
Authors: Rehm Jürgen , Frick Ulrich
Published: March 2010

The metric of disability‐adjusted life years (DALYs) has become the global standard of measuring burden of disease. DALYs are comprised of years of life lost due to premature mortality and years of healthy life lost due to living with disability. In order to calculate the second part of the DALY equation, disease specific disability weights have to be established, i.e. measures for the decline of health associated with these disease states, which vary between zero for perfect health and one for death. Although these disability weights are key for estimating DALYs, there have not been many comprehensive studies with empirical determinations of them. This article describes a systematic review on the state of the art with respect to empirically determining disability weights. Based on this review, a multi‐method approach is outlined, which has also been implemented in a US study to measure burden of disease. This approach involves the use of psychometric methodology as well as economic trade‐off methods for determining the value of health states. It is conceptualized as a disaggregated approach, where the disability weight of any health state can be calculated if the attributes of this health state are known. The US study received the collaboration of experts from more than 20 institutes of the National Institutes of Health and of the Centers for Disease Control and Prevention. First results will be available by the end of this year. Copyright © 2010 John Wiley & Sons, Ltd.
The validity of the German version of the Health of the Nation Outcome Scales (HoNOS‐D): a clinician‐rating for the differential assessment of the severity of mental disorders
Authors: Andreas Sylke , Harfst Timo , Rabung Sven , Mestel Robert , Schauenburg Henning , Hausberg Maria , Kawski Stephan , Koch Uwe , Schulz Holger
Published: March 2010

The Health of the Nation Outcome Scales (HoNOS) is an internationally‐established clinician‐rating instrument for the differential assessment of the severity of patients with mental disorders. The aim of this study was to examine the validity of the German version of the HoNOS (HoNOS‐D). Evaluation of validity, including factor validity, convergent and discriminant validity and sensitivity to change, was conducted on a large, virtually representative, clinical sample of patients with mental disorders in inpatient psychotherapy (Study 1, N = 3169). Additional assessment of criterion‐based validity was completed using another clinical sample of patients with mental disorders (Study 2, N = 55). Although factor validity of the HoNOS‐D and its total score could not be confirmed as expected, the majority of single items of the HoNOS‐D proved to be valid in terms of convergent validity, criterion‐based validity and sensitivity to change. Hence, single items, rather than the total score of the HoNOS‐D, can be recommended for obtaining a picture of the impairment of patients with mental disorders in the clinical setting. Copyright © 2010 John Wiley & Sons, Ltd.
Nitroxide‐Mediated Bulk and Miniemulsion Polymerization in a Continuous Tubular Reactor: Synthesis of Homo‐, Di‐ and Triblock Copolymers
Authors: Enright Thomas E. , Cunningham Michael F. , Keoshkerian Barkev
Published: March 2010

In previous work, a modified nitroxide‐mediated miniemulsion polymerization was demonstrated in a continuous tubular reactor to prepare a latex of polystyrene homopolymer dispersed in water. There, the initial reaction step (low conversion bulk polymerization to prepare the macroinitiator) was done in a batch reactor while the miniemulsion polymerization step was done in a continuous tubular reactor. The present paper describes an extension of that work in which all the reaction steps have been achieved in the continuous tubular reactor. Chain extension of the polystyrene latex to give polystyrene‐block‐poly(butyl acrylate) diblock and polystyrene‐block‐poly(butyl acrylate)‐block‐polystyrene triblock copolymers is also described.

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Hyperbranched Polyethylenes and Functionalized Polymers by Chain Walking Polymerization with Pd‐Diimine Catalysis
Authors: Ye Zhibin , Li Shiyun
Published: March 2010

Chain walking polymerization (CWP) with Pd‐diimine catalysis represents a novel concept for the synthesis of hyperbranched polyethylenes (HBPEs) and functionalized polymers from ethylene stocks. This article summarizes recent developments in this research area. The properties of HBPEs have recently been studied and their application as lubricant viscosity additives, polymer processing aids, and polymers for the functionalization and solubilization of carbon nanotubes in organic solvents have been explored, with some outstanding features having been discovered. Using the CWP strategy, we have also synthesized a range of functionalized HBPEs covalently tethered with a variety of functional groups, including POSS nanoparticles, ATRP‐initiating sites, methacryloyl and acryloyl double bonds, and backbone‐incorporated functionalized ring units.

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The transshipment fund mechanism: Coordinating the decentralized multilocation transshipment problem
Authors: Hanany Eran , Tzur Michal , Levran Alon
Published: March 2010

The multilocation replenishment and transshipment problem is concerned with several retailers facing random demand for the same item at distinct markets, that may use transshipments to eliminate excess inventory/shortages after demand realization. When the system is decentralized so that each retailer operates to maximize their own profit, there are incentive problems that prevent coordination. These problems arise even with two retailers who may pay each other for transshipped units. We propose a new mechanism based on a transshipment fund, which is the first to coordinate the system, in a fully noncooperative setting, for all instances of two retailers as well as all instances of any number of retailers. Moreover, our mechanism strongly coordinates the system, i.e., achieves coordination as the unique equilibrium. The computation and information requirements of this mechanism are realistic and relatively modest. We also present necessary and sufficient conditions for coordination and prove they are always satisfied with our mechanism. Numerical examples illustrate some of the properties underlying this mechanism for two retailers. © 2010 Wiley Periodicals, Inc. Naval Research Logistics, 2010
Strategies to recruit and retain college smokers in cessation trials
Authors: Davidson M. Meghan , Cronk Nikole J. , Harris Kari Jo , Harrar Solomon , Catley Delwyn , Good Glenn E.
Published: March 2010

Techniques to recruit and retain college fraternity and sorority members who reported past 30‐day smoking into a cessation trial are described. Recruitment efforts included relationship‐building, raffles, and screening survey administration during existing meetings. Surveys were administered to 76% (n = 3,276) of members in 30 chapters, 79% of eligible members agreed to participate, and 76% of those completed assessments and were enrolled in the trial (n = 452). The retention rate was 73%. Retention efforts included cash incentives, flexible scheduling, multiple reminders, chapter incentives, and use of chapter members as study personnel. Retention was not related to demographic, behavioral, or group characteristics. The strategies of partnership, convenience, and flexibility appear effective and may prove useful to investigators recruiting similar samples. © 2010 Wiley Periodicals, Inc. Res Nurs Health 33:144–155, 2010
Streit mit dem Gravitationsphysiker Nummer Eins
Authors: Loos Andreas
Published: March 2010

Das Schicksal meint es nicht immer gut mit Wissenschaftlern. Und wenn das Lebenswerk, an dem einer vier Jahrzehnte lang gearbeitet hat, erst nach dem Ableben erscheint, ist dies ganz besonders bitter. Doch hat sich der fleißige Forscher noch andere Verdienste erworben. So war er der erste Direktor des bedeutendsten englischen Observatoriums und Königlicher Astronom.
Sojamilch, der Superemulgator
Authors: Vilgis Thomas
Published: March 2010

Sämige Schokoladecremes sind immer ein gern gesehenes Element in einem Menü. Die klassische Küche vermengt die Schokolade mit Eigelb, das Lecithin als Emulgator beisteuert, und der sorgt für Cremigkeit. Auch Sojamilch liefert Lecithin in großer Menge, hat aber darüber hinaus noch reichlich Sojaproteine im Gepäck. Im Doppelpack bieten die Moleküle die besten Voraussetzungen für eine neue Klasse von cremigen Emulsionen.
Jahrhunderte altes Rätsel des Iapetus gelöst
Authors: Denk Tilmann
Published: March 2010

Die Riesenplaneten in unserem Sonnensystem besitzen zahlreiche Monde. Fast alle bestehen im Wesentlichen aus Wassereis, und viele weisen hoch interessante, teilweise überraschende Eigenschaften auf. Die am längsten bekannte Eigentümlichkeit ist die globale Helligkeitsdichotomie des Saturnmondes Iapetus: Während eine Hemisphäre weiß erscheint, ist die andere sehr dunkel (Abbildung 1). Die Ursache dieses Phänomens konnten wir jetzt erklären.
Lehrer in die Forschung
Authors: Rosenzweig Stephan
Published: March 2010

Das Leibniz‐Institut für Festkörper‐ und Werkstoffforschung Dresden (IFW) bietet jährlich einem Lehrer die Möglichkeit zu einem Forschungspraktikum. Diese Fortbildungsmaßnahme verlangt von allen Beteiligten eine große Bereitschaft zur Veränderung, bringt aber für beide Seiten viele Vorteile.
Synthesis and properties of bifunctional oligoethers. I. Chiral oligomers from propylene oxide
Authors: Jun C. L. , Leborgne A. , Spassky N.
Published: March 2010

Racemic or chiral bifunctional oligoethers of the type H—(O—CH(CH3)—CH2—)n—Cl, n = 4‐10, have been prepared by reacting racemic or optically active propylene oxide with teiraphenyl porphyrin (TPPH2)—AlEt2Cl initiator sysfem. The synthesized products were characterized by IR, elemental analysis, VPO, GPC, and 1H and 13CNMR techniques. The oligomers purified by fractional distillation exhibit narrow MW distributions (M̄w/M̄n ≈ 1.03). Chiroptical properties of the oligomers and their derivatives were examined and compared with those of high molecular weight polyfpropylene oxide). Different possibilities of applicadons of these oligomers are presently under study.
Polvnucleotide analogs with PEI or PEI/polyethyloxazoline backbones
Authors: Ludwick A. G. , Robinson K. S. , McCloud J.
Published: March 2010

The synthesis and characterization of uracil‐ and thy mine‐containing polynucleotide analogs with a linear polyethylenimine backbone is described. Hypochromicity is observed for these analogs in DMSO and in DMSO/H2O solutions and found lo increase as the percent water increases. The influence of water on the 240‐ to 280‐nm absorptions of the analogs and their monomer models is correlated with the mobiliiy of the nucleic‐acid‐base‐con tain ing pendant to the polymeric backbone. An impure 5‐fluorouracil analog has been prepared, and its increased solubility in water relative to the corresponding uracil analog has been noted. A thy mine‐containing analog with a PEI/PEOXZ backbone has been synthesized. The analog consists of water‐soluble and insoluble forms characterized by NMR.
Polyetherimides. II. High‐temperature solution polymerization
Authors: Takekoshi T. , Kochanowski J. E. , Manello J. S. , Webber M. J.
Published: March 2010

The polymerization and characterization of the ether‐containing aromatic polyimides of the following general structure are presented.

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The polymerization was conducted in one step in homogeneous solution of m‐cresol at high temperatures. Typical polyeterimides (PEI) were noncrystalline and showed excellent thermal stability. Among 46 polymers synthesized, only two were crystalline. PEI had glass transition temperatures from 178° to 277°C and exhibited excellent processibility. Many PEI were also soluble in dipolar aprotic solvents and chlorinated hydrocarbons.
Aromatic polyamides. XIII. effect of the halogen position on the thermal and flammability behavior of halogenated poly (1,3‐phenylene‐isophthalamide)
Authors: Whang W. T. , Kapuscinska M. , Pearce E. M.
Published: March 2010

Various halogen substituted poly (1,3‐phenylene‐isophthalamide)s have been prepared. Their glass transition temperature Tg (DSC), thermal decomposition courses (TGA), and flame resistance (oxygen index) are discussed.

The polyamides substituted with halogen in the meta position to NH group showed higher Tg and better thermal stability than those substituted with the same halogen in the ortho position. All halogenated polyamides studied had fairly good flame resistance characteristics: high oxygen indices and high char yields. Halogenated aromatic polyamides with nitrogen ortho to halogen showed the flammability characteristic: limiting oxygen index = 38 + 61 × (weight loss at initial plateau temperature).
Optically active poly(diphenyl‐2‐pyridylmethyl methacrylate): Asymmetric synthesis, stability of helix, and chiral recognition ability
Authors: Okamoto Yoshio , Mohri Haruhiko , Motoshiishikura  , Hatada Koichi , Yuki Heimei
Published: March 2010

Dipheny‐2‐pyridylmethyl methacrylate (D2PyMA) was anionically polymerized with several organolithium complexes of chiral ligands such as (‐)‐sparteine (Sp), (S,S)‐( + )‐ and (R,R)‐(‐)‐2,3‐dimethoxy‐1,4‐bis(dimethylamino)butane [(+)‐ and (‐ )‐DDB], (S)‐(‐)‐1 ‐ methyl‐2‐(piperi‐dinomethyl)pyrrolidine (MPP), (S,S)‐( + )‐3,4‐dimethoxy‐N‐(2‐(dimethylamino)ethyl)pyrrolidine (DDEP), and (S,S)‐(+ )‐N‐benzyl‐3,4‐dimethoxypyrrolidine (BDP) in toluene at low temperature. Sp complexes gave a polymer of low optical activity. DDB was a better chiral ligand, and its complex, particularly the complex with N,N'‐diphenylethylenediamine monolithium amide (DPEDA‐Li), was effective in preparing a polymer of high optical rotation. A THF‐soluble portion of the polymer obtained with (‐)‐DDB‐DPEDA‐Li showed [α]25/365 about ‐ 1400°, which was comparable to that of poly(triphenylmethyl methacrylate) (PTrMA) with pure one‐handed helical structure. However, in the polymerization with DDB‐DPEDA‐Li, optical rotation of the polymer depended greatly on polymerization conditions, such as monomer and initiator concentrations, reaction temperature, and polar additives. Fractionation by THF and/or gel permeation chromatography of the obtained polymers revealed that poly(diphenyl‐2‐pyridylmethyl methacrylate) (PD2PyMA) consisted of a mixture of (+)‐ and (‐)‐ polymers which probably were not enantiomeric to each other. DDEP‐DPEDA‐Li and DDEP‐fluorenyllithium complexes were also efficient chiral initiators that gave polymer of the same or higher optical rotation in comparison with DDB complexes. The optical rotation of PD2PyMA in CHCl3‐2,2,2‐trifluoroethanol (90:10) slowly changed with time. Optically active PD2PyMA coated on macroporous silica gel resolved racemic compounds as a chiral stationary phase for high‐performance liquid chromatography (HPLC).
A polymeric triarylmethane dye as a sensitizer for photoconductivity
Authors: Mitra Smarajit
Published: March 2010

A polymeric analogue of crystal violet in which the triarylmethane moiety is pendent from a polyester backbone has been examined as a sensitizer for photoconductivity in poly‐N‐vinyicarbazole. In both positive and negative surface charging modes, the dark decay rates increase linearly with sensitizer concentration, but are lower than those for monomeric crystal violet sensitization. The photodecay rates, in both modes, show optimal concentration dependence and are higher than those for monomeric crystal violet.
Synthesis and characterization of main‐chain polyaminimides
Authors: Salamone J. C. , Richard R. E. , Watterson A. C.
Published: March 2010

Three novel main‐chain polyarninimides were prepared containing rigid and/or flexible groups within the backbone. The polymer precursors were initially synthesized from bis‐dimethylhydrazides and dihalides at room temperature through the Menschulkin reaction, which yielded hydrazinium ionenes. In a similar fashion, low molecular weight model compounds were also prepared in order to confirm the structures of the ionene polymers. It was found that the ionenes were totally, or at least partially, converted o the aminimide form in the presence of water alone, while the model cationic compounds required a strong base before conversion to their corresponding aminimides. These new polymers were characterized by (heir infrared and NMK spectra, as well as dilute solution viscosity. Preliminary solution properties indicate that the hydrazinium form of the polymers behave as poly electrolytes, whereas the aminimide form behaves as a neutral polymer.
NMR study of 9‐anthranylmethyl hexafluorophosphate. Polymerization of styrene monomers
Authors: Toncheva V. D. , Velichkova R. S. , Panayotov I. M. , Markova L. P.
Published: March 2010

The primary carbenium salt 9‐anihranylmethyl hexafluorophosphate is characterized by 1H‐ and 13C‐NMR spectroscopy. The results show that in the temperature range −60°‐15°C the initiator exists as a classical carbenium ion and a protonated anthracenium ion. At higher temperatures the reactions of self‐alkylation and disproportionation proceed, giving bianthracenes, hydroanthracenes, and other dimer forms.

The polymerization of α‐methylstyrene and p‐methoxystyrene, initiated by 9‐anthranylmethyl hexafluorophosphate, is investigated. The mechanism of initiation, the stereochemical configuration, and the end groups of the polymer chains are determined.
Exploratory ring‐opening polymerization. XIIL ring‐opening polymerization of 2‐vinyl cyclic sulfones
Authors: Cho Iwhan , Kim Sang‐Keun , Lee Myong‐Hoon
Published: March 2010

2‐Vinyllhiolane‐1,1‐dioxide (Ia) and 2‐vinylthiane‐1,1‐dioxide(Ib) have been prepared and polymerized with free radical initiators to obtain poly(sulfonyl‐hex‐2‐enylene) (IIa) and poly(sulfonyl‐hept‐2‐enyIene‐co‐2‐vinylthiane‐1,1‐dioxide) (IIb), respectively, via a ring‐opening mechanism. Structures of the polymers are supported by infrared and 1H‐NMR spectroscopy. Poly(sulfonyl‐hex‐2‐enylene) was insoluble in ordinary organic solvents, but soluble in concentrated sulfuric acid or trifluoroacetic acid, and was white amorphous powder, softening at 168°C. Degradation occurred at 294°C under N2. Ia copolymerized with certain vinyl monomers, such as ethyl acrylate, but its copolymerization behavior was different from those of normal vinyl monomers.
On predicting free radical polymerizability of allyl monomers. MINDO/3 and 13C NMR results
Authors: Vaidya Rajeev A. , Mathias Lon J.
Published: March 2010

Two new methods of predicting free radical polymerizability of allyl monomers have been developed. MINDO/3 calculations of eigenvalues for the C—H bond a to the atlyl substituent allow comparison of relative bond strengths. Monomers known to undergo degradative chain transfer display more positive eigenvalues correlating with weaker α‐C—H bonds. Polymerizable monomers have more negative eigenvalues and stronger α‐C—H bonds. The latter possess strongly polarized or protonated substituents not capable of resonance stabilization of a chain‐terminating allyl radical. The inductive effect of such substituents on the 13C NMR peaks of the vinyl carbons is the basis for the empirical spectroscopic method. Allyl compounds display β‐carbon peaks farther downfield than the γ‐carbon peaks. Polymerizable monomers generally have β peaks shifted upfield and γ peaks shifted downfield from those of poor monomers. This effect brings the two peaks closer together in the spectrum. Thus, the smaller the Δδ value (δβ − δγ), the more likely the monomer is to polymerize well. Monomers with intermediate eigenvalues or Δδ values may polymerize with difficulty or only under special conditions. Combined use of the theoretical and empirical techniques can allow prediction of inherent polymerizability and can facilitate evaluation of reaction media most favorable to polymer formation.
Conformational analysis of poly(tetrahydrofurandiyls)
Authors: Moore J. A. , Wille Roice , Miller Kenneth J.
Published: March 2010

The stereoisomeric configurations of poly(2,5‐tetraliydrofurandiyl), 1, and poly(2,3‐tetrahydrofurandiyl), 2, have been investigated by conformational analysis. Similar results were obtained for 1 and 2, Threodiisotactic (tit) and erythrodisyndiotactic (est) configurations could form low energy helical conformations, whereas erythrodiisotactic (eit) and threodisyndiotactic (tst) configurations generally formed low energy linear conformations. Helical conformations of I placed oxygen atoms at the interior of the helices, but helical conformations of 2 placed oxygen atoms more toward the periphery. The results of ion‐binding experiments are interpreted in terms of the results of conformational analysis. Ion‐binding experiments are consistent with the suggestion that configurations that can form low energy, helical conformations with oxygen atoms at the interior of the helices could bind cations efficiently. Configurations that can form only low energy linear conformations, or that form helices with oxygen atoms toward the periphery of the helices, should be inefficient in binding cations.
Effects of bulky substituents on oxygen permeation behaviors of polystyrene‐based polymers
Authors: Kawakami Y. , Kamiya H. , Yamashita Y.
Published: March 2010

Polymers of β‐cyclodextrinyl substituted styrene and 4′‐oligodimethylsiloxanyl‐4‐vinyldiphenyl were synthesized. Their oxygen perm selectivity was studied from the viewpoint of investigating the effects of the introduction of bulky p‐substituents to polystyrene on their permeation behaviors. The bulky substituents were quite effective in enhancing the permeability; however, the selectivity in permeation decreased with the increase in permeability.
A Comparative Mass‐Spectrometric Study of Plasma‐ and Vacuum Ultraviolet Ablation of Selected Polymers
Authors: Nelea Valentin , Vasilets Victor N. , Skurat Vladimir E. , Truica‐Marasescu Florina , Wertheimer Michael R.
Published: March 2010

Energetic photons (UV, VUV radiation and soft X rays), and particles (ions, electrons, metastable excited atoms) from inert gas plasmas possess sufficient energy to induce multiple bond scission reactions in the macromolecular chains of most polymers. As a result, volatile products of varying molecular weights escape from the polymers' surfaces; they can be captured and identified by mass spectrometry (MS). We report an MS‐based study of five commercial polymers, polyethylene (PE), polypropylene (PP), polystyrene (PS), poly(ethylene terephthalate) (PET) and polyamide that were exposed to inert gas (He, Ar) plasmas and to near‐monochromatic (λ = 121.6 nm) VUV irradiation. For the cases of PE and PP, quantitative analyses of the most abundant reaction products (H2, C1–C7 alkanes) are compared among the various polymer/excitation‐source cases, and with regard to literature data for γ irradiation.

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Bridging the gap: A GFP‐based strategy for overexpression and purification of membrane proteins with intra and extracellular C‐termini
Authors: Hsieh Jennifer M. , Besserer Gabriel Mercado , Madej M. Gregor , Bui Ha‐Quyen , Kwon Seunghyug , Abramson Jeff
Published: March 2010

Low expression and instability during isolation are major obstacles preventing adequate structure‐function characterization of membrane proteins (MPs). To increase the likelihood of generating large quantities of protein, C‐terminally fused green fluorescent protein (GFP) is commonly used as a reporter for monitoring expression and evaluating purification. This technique has mainly been restricted to MPs with intracellular C‐termini (Cin) due to GFP's inability to fluoresce in the Escherichia coli periplasm. With the aid of Glycophorin A, a single transmembrane spanning protein, we developed a method to convert MPs with extracellular C‐termini (Cout) to Cin ones providing a conduit for implementing GFP reporting. We tested this method on eleven MPs with predicted Cout topology resulting in high level expression. For nine of the eleven MPs, a stable, monodisperse protein‐detergent complex was identified using an extended fluorescence‐detection size exclusion chromatography procedure that monitors protein stability over time, a critical parameter affecting the success of structure‐function studies. Five MPs were successfully cleaved from the GFP tag by site‐specific proteolysis and purified to homogeneity. To address the challenge of inefficient proteolysis, we explored expression and purification conditions in the absence of the fusion tag. Contrary to previous studies, optimal expression conditions established with the fusion were not directly transferable for overexpression in the absence of the GFP tag. These studies establish a broadly applicable method for GFP screening of MPs with Cout topology, yielding sufficient protein suitable for structure‐function studies and are superior to expression and purification in the absence GFP fusion tagging.
Structures of the OmpF porin crystallized in the presence of foscholine‐12
Authors: Kefala Georgia , Ahn Chihoon , Krupa Martin , Esquivies Luis , Maslennikov Innokentiy , Kwiatkowski Witek , Choe Senyon
Published: March 2010

The endogenous Escherichia coli porin OmpF was crystallized as an accidental by‐product of our efforts to express, purify, and crystallize the E. coli integral membrane protein KdpD in the presence of foscholine‐12 (FC12). FC12 is widely used in membrane protein studies, but no crystal structure of a protein that was both purified and crystallized with this detergent has been reported in the Protein Data Bank. Crystallization screening for KdpD yielded two different crystals of contaminating protein OmpF. Here, we report two OmpF structures, the first membrane protein crystal structures for which extraction, purification, and crystallization were done exclusively with FC12. The first structure was refined in space group P21 with cell parameters a = 136.7 Å, b = 210.5 Å, c = 137 Å, and β = 100.5°, and the resolution of 3.8 Å. The second structure was solved at the resolution of 4.4 Å and was refined in the P321 space group, with unit cell parameters a = 215.5 Å, b = 215.5 Å, c = 137.5 Å, and γ = 120°. Both crystal forms show novel crystal packing, in which the building block is a tetrahedral arrangement of four trimers. Additionally, we discuss the use of FC12 for membrane protein crystallization and structure determination, as well as the problem of the OmpF contamination for membrane proteins overexpressed in E. coli.
Steric and thermodynamic limits of design for the incorporation of large unnatural amino acids in aminoacyl‐tRNA synthetase enzymes
Authors: Armen Roger S. , Schiller Stefan M. , Brooks Charles L.
Published: March 2010

Orthogonal aminoacyl‐tRNA synthetase/tRNA pairs from archaea have been evolved to facilitate site specific in vivo incorporation of unnatural amino acids into proteins in Escherichia coli. Using this approach, unnatural amino acids have been successfully incorporated with high translational efficiency and fidelity. In this study, CHARMM‐based molecular docking and free energy calculations were used to evaluate rational design of specific protein–ligand interactions for aminoacyl‐tRNA synthetases. A series of novel unnatural amino acid ligands were docked into the p‐benzoyl‐L‐phenylalanine tRNA synthetase, which revealed that the binding pocket of the enzyme does not provide sufficient space for significantly larger ligands. Specific binding site residues were mutated to alanine to create additional space to accommodate larger target ligands, and then mutations were introduced to improve binding free energy. This approach was used to redesign binding sites for several different target ligands, which were then tested against the standard 20 amino acids to verify target specificity. Only the synthetase designed to bind Man‐α‐O‐Tyr was predicted to be sufficiently selective for the target ligand and also thermodynamically stable. Our study suggests that extensive redesign of the tRNA synthatase binding pocket for large bulky ligands may be quite thermodynamically unfavorable. Proteins 2010. © 2010 Wiley‐Liss, Inc.
Novel method for the synthesis of urea backbone cyclic peptides using new Alloc‐protected glycine building units
Authors: Hurevich Mattan , Tal‐Gan Yftah , Klein Shoshana , Barda Yaniv , Levitzki Alexander , Gilon Chaim
Published: March 2010

Cyclization of bioactive peptides, utilizing functional groups serving as natural pharmacophors, is often accompanied with loss of activity. The backbone cyclization approach was developed to overcome this limitation and enhance pharmacological properties. Backbone cyclic peptides are prepared by the incorporation of special building units, capable of forming amide, disulfide and coordinative bonds. Urea bridge is often used for the preparation of cyclic peptides by connecting two amine functionalized side chains. Here we present urea backbone cyclization as an additional method for the preparation of backbone cyclic peptide libraries. A straightforward method for the synthesis of crystalline Fmoc‐Nα [ω‐amino(Alloc)‐alkyl] glycine building units is presented. A set of urea backbone cyclic Glycogen Synthase Kinase 3 analogs was prepared and assessed for protein kinase B inhibition as anticancer leads. Copyright © 2010 European Peptide Society and John Wiley & Sons, Ltd.
Unveiling the defect levels in SnS thin films for photovoltaic applications using photoluminescence technique
Authors: Sajeesh T. H. , Poornima N. , Kartha C. Sudha , Vijayakumar K. P.
Published: March 2010

Exploiting the potential of the material for the photovoltaic applications requires an extensive defect level analysis, mandatory. Photoluminescence (PL) technique was employed to probe the defect levels in p‐SnS thin films deposited using chemical spray pyrolysis (CSP) technique. Three PL emissions were recorded at 1.09, 0.76, and 0.75 eV. Systematic investigations performed, focusing the 1.09 eV emission, revealed that the shoulder at 1.093 eV gets completely quenched beyond 110 K. From this study, we could identify a bound exciton associated to a shallow donor level whose activation energy was calculated to be 20 meV from Arrhenius plot. By studying the variation of PL intensity with excitation power, we could zero‐in that the emission at 1.09 eV was a donor–acceptor pair (DAP) transition. Knowing the band gap to be 1.33 eV, we could identify a deep acceptor at 0.22 eV above valence band. The band structure deduced from the present analysis is depicted in the abstract figure.

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Structural details of Ge‐rich and silver‐doped chalcogenide glasses for nanoionic nonvolatile memory
Authors: Mitkova Maria , Sakaguchi Yoshifumi , Tenne Dmitri , Bhagat Shekhar Kumar , Alford Terry L.
Published: March 2010

We are reporting our results of Raman and X‐ray diffraction (XRD) studies on amorphous Ge46S54 thin films and the films after silver photodiffusion. Based on the Raman scattering studies, a structural model for amorphous Ge46S54 is suggested including the formation of single Ge–S chains with a vibrational mode at 410 cm−1. The result of XRD measurement indicates that there exists a medium‐range order with about 6 Å´ even at such Ge‐rich composition. After the introduction of silver, the medium‐range order is lost and there was a change in the diffraction curve indicative of the change in the local atomic order. The experimental results are explained in terms of our structural model, in connection with the application for fast switching memory devices.
Ferromagnetic and ferroelectric quantum phase transitions
Authors: Rowley Stephen , Smith Robert , Dean Mark , Spalek Leszek , Sutherland Michael , Saxena Montu , Alireza Patricia , Ko Chris , Liu Cheng , Pugh Emma , Sebastian Suchitra , Lonzarich Gilbert
Published: March 2010

The applicability of mean field models of ferroelectric and ferromagnetic quantum critical points is examined for a selection of d‐electron systems. Crucially, we find that the tendency of the effective interaction between critical fluctuation modes to become attractive and anomalous as the ordering temperatures tend to absolute zero results in particularly complex and striking phenomena. The multiplicity of quantum critical fields at the border of metallic ferromagnetism, in particular, is discussed here.
Optical properties of TiO2 thin films prepared by chemical spray pyrolysis from aqueous solutions
Authors: Ayouchi R. , Casteleiro C. , Schwarz R. , Barrado J. R. , Martín F.
Published: March 2010

Titanium dioxide (TiO2) is known to have three different kinds of polymorphous crystalline forms: rutile, anatase, and brookite. The rutile phase is always formed at higher temperatures, while the anatase phase is formed at lower temperatures and transformed into rutile phase above 800 ºC. Various deposition techniques have been developed for depositing TiO2 thin films, including evaporation, sputtering, chemical vapour deposition and thermal oxidation of titanium. Among them, the Chemical Spray Pyrolysis (CSP) technique has many advantages, such as good conformal coverage, the possibility of epitaxial growth and the application to large area deposition. Also, this method is low cost and it is easy to control the deposition growth parameters. In the present work, TiO2 thin films have been deposited on p‐Si (001) and fused silica substrates by Chemical Spray Pyrolysis (CSP) method from aqueous solution containing titanium (IV) isopropoxide (Ti[OCH(CH3)2]4. As‐deposited thin films show anatase polycrystalline structure, and rutile phase formed for films annealed at 750ºC. SEM images have confirmed a smooth and crack‐free surface with low surface roughness. X‐ray photoelectron spectroscopy (XPS) combined with 4 keV Ar+ depth profiling has shown that crystallized films correspond to TiO2. Residual carbon coming from the organic precursor solution is only detected at the surface of the film. Thin films deposited on fused silica were highly transparent (more than 85%), with an indirect optical band gap of 3,43 and 3,33 eV for as‐deposited and annealed films, respectively, and refractive indexes in the range between 2.01–2.29. Spectroscopic Ellipsometry (SE) also has been used to extract optical parameters. SE data fitted to triple‐layer physical model revealed the same tendency to increase refractive index in annealed films. (© 2010 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)
Educative mentoring: Promoting reform‐based science teaching through mentoring relationships
Authors: Bradbury Leslie Upson
Published: March 2010

Educative mentoring is an idea developed by Feiman‐Nemser [Feiman‐Nemser, S. (1998). Teachers as teacher educators.European Journal of Teacher Education, 21(1), 63–74; (2001). Helping novices learn to teach: Lessons from an exemplary support teacher.Journal of Teacher Education, 52(1), 17–30] to reflect current conceptions of mentoring that emphasize novices learning from their practice with the assistance of a mentor teacher. Educative mentoring seeks to meet the immediate needs of novice teachers while also focusing on long‐term goals for professional development. This paper discusses the meaning of educative mentoring, describes key behaviors of educative mentors, outlines important components for the professional development of mentors, and proposes areas for further research with a specific emphasis on the needs of beginning science teachers. © 2010 Wiley Periodicals, Inc.Sci Ed94:1049–1071, 2010
The Exploratory Behavior Scale: Assessing young visitors' hands‐on behavior in science museums
Authors: Van Schijndel Tessa J. P. , Franse Rooske K. , Raijmakers Maartje E. J.
Published: March 2010

In this paper, we introduce the Exploratory Behavior Scale (EBS), a quantitative measure of young children's interactivity. More specifically, the EBS is developed from the psychological literature on exploration and play and measures the extent to which preschoolers explore their physical environment. A practical application of the EBS in a science museum is given. The described study was directed at optimizing parent guidance to improve preschoolers' exploration of exhibits in science center NEMO. In Experiment 1, we investigated which adult coaching style resulted in the highest level of exploratory behavior at two exhibits. In Experiment 2, we investigated whether informing parents about an effective way of coaching influenced preschoolers' exploratory behavior at two exhibits. The results of the study demonstrate the added value of the EBS in visitor behavior research: compared to existing global measures of visitor interactivity; the EBS adds information about the quality of the hands‐on behavior. Compared to existing detailed measures of visitor interactivity, the EBS has the advantage of being applicable in different museum settings and enabling comparisons between exhibits or exhibitions. In addition, the EBS allows for quantification of unanticipated behavior. © 2010 Wiley Periodicals, Inc. Sci Ed 94:794–809, 2010
Tunable Water Channels with Carbon Nanoscrolls
Authors: Shi Xinghua , Cheng Yuan , Pugno Nicola M. , Gao Huajian
Published: March 2010

Molecular dynamics simulations and theoretical analyses are performed to show that the flow rate of water through the core of carbon nanoscrolls (CNSs) can be adjusted over a broad range through the effective surface energy, which in turn can be tuned by an applied DC or AC electric field. The results suggest that the CNSs hold great promise for applications such as tunable water and ion channels, nanofluidic devices, and nanofilters, as well as tunable gene‐ and drug‐delivery systems.