bluuebunny/crossref_metadata_2025 huggingface dataset:
Kinetics and mechanism of seeded dispersion polymerization
Authors: Jiang Sheng , Sudol E. David , Dimonie Victoria L. , El‐Aasser Mohamed S.
Published: May 2008

The kinetics and mechanism of seeded dispersion polymerization of methyl methacrylate (MMA) was studied by applying both micron and submicron PMMA seeds. Using a 1.7 μm PMMA seed (Np = 1 × 1012/L) and a monomer polymer ratio (M/P) of 28/1, secondary nucleation was found to occur and the number of new particles exceeded that produced in a parallel ab initio dispersion polymerization. This was explained by the paradoxical initiator concentration effect seen in dispersion polymerizations where the number of particles decreases with increasing initiator concentration. In contrast, using 194 nm (Np = 26 × 1012/L; M/P = 833/1) and 317 nm (Np = 5.6 × 1012/L; M/P = 714/1) submicron seeds, it was found that the final particle number was similar to (or less in a few cases) the initial seed number over a relatively wide range of initiator concentrations. With increasing initiator concentration, the initial reaction rate increased but the maximum reaction rate decreased slightly. This was explained by increased radical termination particularly in unstable nuclei, leading to a reduced radical entry rate. The reaction rate was found to be moderately dependent on the number of seed particles, but was independent of the seed surface area. © 2008 Wiley Periodicals, Inc. J Appl Polym Sci, 2008
Biobased polyisocyanates from plant oil triglycerides: Synthesis, polymerization, and characterization
Authors: Çaylı Gökhan , Küsefoğlu Selim
Published: May 2008

In this study, an easy and efficient synthesis of unsaturated plant oil triglycerides having isocyanate groups is reported. In the first step of the synthesis, the triglyceride was brominated at the allylic positions by a reaction with N‐bromosuccinimide, and in the second step, these brominated species were reacted with AgNCO to convert them to isocyanate‐containing triglycerides. At the end of the reaction, approximately 60–70% of the bromine was replaced by NCO groups, and the double bonds of the triglyceride were not consumed. When the amount of AgNCO was increased, the yield also increased. The final products were characterized with IR and 1H‐NMR, and polyurethanes and polyureas were obtained from these fatty isocyanates with alcohols and amines, respectively. The polymers were characterized by differential scanning calorimetry and thermogravimetric analysis. Differential scanning calorimetry curves showed that glycerin polyurethane showed a glass‐transition temperature at 19°C, castor oil polyurethane showed two glass‐transition temperatures at −43 and 36°C, and triethylene tetraamine polyurea showed a glass‐transition temperature at 31°C. Some properties of the polymers, such as the tensile strength and swelling ratios, were also determined. The swelling rate of glycerin polyurethane was higher than that of castor oil polyurethane in dichloromethane. The equilibrium swelling ratio was highest for the castor oil polyurethane. The polyurethanes synthesized in this study had a Young's modulus around 50 kPa and a tensile strength around 0.01 N/mm2 (100 kPa). The tensile strength of glycerin polyurethane was higher than that of castor oil polyurethane. © 2008 Wiley Periodicals, Inc. J Appl Polym Sci, 2008
Synthesis, characterization and SEESR spectroscopic investigations of indole/aniline copolymers
Authors: Köleli Fatih , Dündar Derya
Published: May 2008

Indole/aniline copolymers were synthesized electrochemically and the polymerization mechanism was investigated via in‐situ simultaneous electrochemical electron spin resonance (SEESR) spectroscopy. The Radical cationic intermediates of substituted indole and aniline were detected during the electrochemical oxidation. The resulting ESR‐spectra with hyperfine splitting were simulated and radicalic structures were identified. It was suggested that the polymerization occurs over positions C‐3 and C‐6 of indole molecule and over the nitrogen and para‐position of aniline. Furthermore, aniline, indole and aniline/indole copolymers were investigated depending on applied potential via electrochemical impedance spectroscopy (EIS). © 2008 Wiley Periodicals, Inc. J Appl Polym Sci, 2008
Mathematical theory of the h‐ and g‐index in case of fractional counting of authorship
Authors: Egghe Leo
Published: May 2008

This article studies the h‐index (Hirsch index) and the g‐index of authors, in case one counts authorship of the cited articles in a fractional way. There are two ways to do this: One counts the citations to these papers in a fractional way or one counts the ranks of the papers in a fractional way as credit for an author. In both cases, we define the fractional h‐ and g‐indexes, and we present inequalities (both upper and lower bounds) between these fractional h‐ and g‐indexes and their corresponding unweighted values (also involving, of course, the coauthorship distribution). Wherever applicable, examples and counterexamples are provided. In a concrete example (the publication citation list of the present author), we make explicit calculations of these fractional h‐ and g‐indexes and show that they are not very different from the unweighted ones.
Affinity‐Labeling‐Based Introduction of a Reactive Handle for Natural Protein Modification
Authors: Wakabayashi Haruto , Miyagawa Masayoshi , Koshi Yoichiro , Takaoka Yousuke , Tsukiji Shinya , Hamachi Itaru
Published: May 2008

A new chemical method to site‐specifically modify natural proteins without the need for genetic manipulation is described. Our strategy involves the affinity‐labeling‐based attachment of a unique reactive handle at the surface of the target protein, and the subsequent selective transformation of the reactive handle by a bioorthogonal reaction to introduce a variety of functional probes into the protein. To demonstrate this approach, we synthesized labeling reagents that contain: 1) a benzenesulfonamide ligand that directs specifically to bovine carbonic anhydrase II (bCA), 2) an electrophilic epoxide group for protein labeling, 3) an exchangeable hydrazone bond linking the ligand and the epoxide group, and 4) an iodophenyl or acetylene handle. By incubating the labeling reagent with bCA, the reactive handle was covalently attached at the surface of bCA through epoxide ring opening. Either after or before removing the ligand by a hydrazone/oxime‐exhange reaction, which restores the enzymatic activity, the reactive handle incorporated could be derivatized by Suzuki coupling or Huisgen cycloaddition reactions. This method is also applicable to the target‐specific multiple modification in a protein mixture. The availability of various (photo)affinity‐labeling reagents and bioorthogonal reactions should extend the flexibility of this strategy for the site‐selective incorporation of many functional molecules into proteins.
Two‐degree‐of‐freedom controller design for linear parameter‐varying systems
Authors: Xie Wei , Eisaka Toshio
Published: May 2008

A design strategy for linear parameter‐varying (LPV) systems is considered in a two‐degree‐of‐freedom (TDOF) control framework. First, a coprime factorization for LPV systems is introduced. Second, based on the coprime factorization, a TDOF control framework of linear timeinvariant systems is extended to that of LPV systems. Good tracking performance and good disturbance rejection are achieved by a feedforward controller and a feedback controller, respectively. Furthermore, each controller design problem can be formulated in terms of a linear matrix inequality related to the L2 gain performance. Finally, a simple design example is illustrated. Copyright © 2008 John Wiley and Sons Asia Pte Ltd and Chinese Automatic Control Society
Analysis and experiment on simultaneous swing‐up of a parallel cart‐type double inverted pendulum
Authors: Deng Mingcong , Inoue Akira , Henmi Tomohiro , Ueki Nobuyuki
Published: May 2008

This paper considers experimental study and analysis on simultaneous swing‐up control of a parallel cart‐type double inverted pendulum. The proposed controller includes both a swing‐up controller based on weighted energy related function and a cart travel controller designed by a pole assignment control scheme. The cart travel controller can restrict cart travel during the swing‐up. When the two pendulums are swung up, the controller will be switched to a stabilizing controller, and the controller can take the cart to the initial position. Control simulation and experiment were successfully conducted. Copyright © 2008 John Wiley and Sons Asia Pte Ltd and Chinese Automatic Control Society
Control over a packet dropping network with norm bounded uncertainties
Authors: Shi Ling , Epstein Michael , Murray Richard M.
Published: May 2008

In this paper, we consider a robust networked control problem. We consider linear unstable and uncertain discrete time plants with a network between the sensor and controller as well as between the controller and plant. We investigate the effect of data dropout in the form of packet losses and we focus on the tradeoff between packet arrival rate versus the uncertainties of the system dynamics. We show that the minimum packet arrival rate and the maximum uncertainty of the system dynamics have a positive correlation. Four distinct control schemes are explored and serve as examples to study this tradeoff. We derive sufficient condition for each scheme to ensure almost sure stability of the closed loop system. Simulation and examples are provided to assist the theory. Copyright © 2008 John Wiley and Sons Asia Pte Ltd and Chinese Automatic Control Society
Output‐feedback ℋ︁2/ℋ︁∞control of a class of networked fault tolerant control systems
Authors: Aberkane S. , Ponsart J. C. , Sauter D.
Published: May 2008

This paper deals with static output feedback control of a class of discrete‐time networked control systems (NCS) subject to random failures and random delays. The different random processes are modeled as Markovian chains, and the resulting closed‐loop system belongs to the class of discrete‐time Markovian jump linear systems (MJLS). The main contribution is to formulate conditions for multi‐performance design related to this class of stochastic hybrid systems. The specifications and objectives under consideration include stochastic stability, ℋ︁2and ℋ︁∞performances. Results are formulated as matrix inequalities. A numerical algorithm is provided and its running is illustrated on a numerical example. Copyright © 2008 John Wiley and Sons Asia Pte Ltd and Chinese Automatic Control Society
Analysis and applications of the motion message estimator for network control systems
Authors: Hsieh Chen‐Chou , Hsu Pau‐Lo
Published: May 2008

The time‐delay effect in network systems is unavoidable because of its limited transmission bandwidth. In real‐time network control systems (NCS), all messages are required to be transmitted or received to meet specifications of the deadline. Therefore, the data dropout may thus occur in NCS due to its time delay in a stochastic nature. In this paper, a motion message estimator is proposed to construct a real‐time motion NCS to significantly reduce the data‐dropout effect. Both simulation and experimental results indicate that a 3rd‐order message estimator based on the Taylor expansion can be properly implemented in NCS for industrial motion control systems. Furthermore, since the uncertainties of the NCS estimator are greatly suppressed by applying the message, experimental results indicate that its integration with the feedforward control leads to significantly improved accuracy for the NCS implemented on an industrial computerized numerical control (CNC) machine tool. Copyright © 2008 John Wiley and Sons Asia Pte Ltd and Chinese Automatic Control Society
Controller design for flow networks of switched servers with setup times: The Kumar‐Seidman case as an illustrative example
Authors: Lefeber Erjen , Rooda J. E.
Published: May 2008

In this paper we consider the control of a reentrant manufacturing system with setup times, as introduced by Kumar and Seidman. In most literature on control of a network of servers with setup times, first a policy is introduced and then the resulting network behavior is analyzed. In manufacturing systems the network typically is fixed and givena priori. Furthermore, optimal steady state behavior is desired. Therefore, this paper follows a different approach. First optimal steady state network behavior is determined, then a feedback controller is presented which makes the network converge towards this desired steady state behavior. The resulting controller is a non‐distributed controller: each server needs global state information. For a manufacturing system this is not a problem, since global information typically is available. Finally it is shown that a distributed controller (each server needs only local state information) can also be used to achieve the same result. Copyright © 2008 John Wiley and Sons Asia Pte Ltd and Chinese Automatic Control Society
Fault tolerant control of feedback linearizable systems with stuck actuators
Authors: Wang Min , Zhou Donghua
Published: May 2008

Fault tolerant control of feedback linearizable systems with stuck actuators is studied in this paper. Once stuck, the faulty actuators cannot respond to the control inputs and have fixed constant outputs. The fault considered here is severe in the sense that the faulty system is no longer feedback linearizable. By constructing a nonlinear transformation and extending Chen's disturbance observer to a multi‐dimensional case, a generalized disturbance observer is developed for estimating the unknown constant outputs of the faulty actuators. Then, through integrating the generalized disturbance observer with a controller constructed by the famous cascade design method, a fault tolerant controller is obtained. It is proven that the fault tolerant controller ensures not only boundedness of the state of the faulty system but also satisfactory output performance. Finally, computer simulations are done using an inverted pendulum model to verify the effectiveness of the proposed method. Copyright © 2008 John Wiley and Sons Asia Pte Ltd and Chinese Automatic Control Society
Optimal genetic and adaptive fuzzy washout filter design in the motion‐cueing simulator
Authors: Hwang Thong‐Shing , Kuo Ming‐Sung , Hsieh Sheng‐Ping
Published: May 2008

This paper has improved the simulation fidelity of a motion‐cueing simulator within a limited working space by using the optimal genetic algorithm and an adaptive fuzzy algorithm in the washout filter design, especially, in solving the real‐time parameter auto‐tuning problem. The optimal parameters of the washout filter have been searched out globally by the genetic algorithm. The fuzzy inference methodology is adopted to solve the real‐time auto‐tuning problem of the motion‐cueing parameters in the coordinate adaptive washout filter design according to the varying frequency of the dynamic input signal and the attitude of the upper platform within a limited working space.

The simulation results have demonstrated that the sensing error values of otolith and semicircular canal have been suppressed below one threshold unit and the displacement has been controlled within the working space of the simulator. Copyright © 2008 John Wiley and Sons Asia Pte Ltd and Chinese Automatic Control Society
NTD prevalences in central California before and after folic acid fortification
Authors: Chen Brian H. , Carmichael Suzan L. , Selvin Steve , Abrams Barbara , Shaw Gary M.
Published: May 2008

BACKGROUND: In many regions, NTD prevalences were already declining prior to folic acid fortification. This study examined whether the declining prefortification (1989–1996) NTD prevalences continued into the postfortification period (1998–2003) in selected California counties. METHODS: This population‐based study used vital statistics data and birth defects registry data that were actively ascertained from medical records. The study population included all live births and stillbirths delivered in central California counties from 1989 to 2003. Cases included deliveries with NTDs during the same time period. RESULTS: For all NTDs combined, the slopes indicated that NTD prevalence was decreasing by 7.5 (slope: −7.5; 95% CI: −12.4, −2.5) cases per 100,000 deliveries per year before fortification, whereas NTD prevalence was no longer decreasing after fortification. Comparison of the difference in the two slopes indicated that the postfortification slope exceeded the prefortification slope by 12.6 (95% CI: 2.6, 22.6) cases per 100,000 deliveries per year. CONCLUSIONS: Annual NTD prevalences in central California did not continue to decrease after implementation of folic acid fortification. Birth Defects Research (Part A) 2008. © 2008 Wiley‐Liss, Inc.
Evaluation of preterm births and birth defects in liveborn infants of US military women who received smallpox vaccine
Authors: Ryan Margaret A. K. , Gumbs Gia R. , Conlin Ava Marie S. , Sevick Carter J. , Jacobson Isabel G. , Snell Katherine J. , Spooner Christina N. , Smith Tyler C. ,   for the Department of Defense Birth and Infant Health Registry Team
Published: May 2008

BACKGROUND: Women serving in the US military have some unique occupational exposures, including exposure to vaccinations that are rarely required in civilian professions. When vaccinations are inadvertently given during pregnancy, such exposures raise special concerns. These analyses address health outcomes, particularly preterm births and birth defects, among infants who appear to have been exposed to maternal smallpox vaccination in pregnancy. METHODS: This retrospective cohort study included 31,420 infants born to active‐duty military women during 2003–2004. We used Department of Defense databases to define maternal vaccination and infant health outcomes. Multivariable regression models were developed to describe associations between maternal smallpox vaccination and preterm births and birth defects in liveborn infants. RESULTS: There were 7,735 infants identified as born to women ever vaccinated against smallpox, and 672 infants born to women vaccinated in the first trimester of pregnancy. In multivariable modeling, maternal smallpox vaccination in pregnancy was not associated with preterm or extreme preterm delivery. Maternal smallpox vaccination in the first trimester of pregnancy was not significantly associated with overall birth defects (OR 1.40; 95% CI: 0.94, 2.07), or any of seven specific defects individually modeled. CONCLUSIONS: Results may be reassuring that smallpox vaccine, when inadvertently administered to pregnant women, is not associated with preterm delivery or birth defects in liveborn infants. Birth Defects Research (Part A) 2008. © 2008 Wiley‐Liss, Inc.
Living related liver transplantation in children
Authors: Heaton N , Faraj W , Melendez H Vilca , Jassem W , Muiesan P , Mieli-Vergani G , Dhawan A , Rela M
Published: May 2008

Background

Living related liver transplantation (LRLT) has become established for treating children with end-stage liver disease. The aim of this study was to review a single-centre experience of left lateral segment liver transplants from living donors in children.

Methods

Fifty left lateral segment LRLT procedures have been performed since 1993. There were 17 girls and 33 boys, of median age 1·5 years (range 0·5 to 13 years), with a median weight of 10 (range 0·7–44) kg. Donors included 23 mothers, 26 fathers and one uncle, with a median age of 33 (range 19–46) years.

Results

At a median follow-up of 86 months, there was no donor mortality and low morbidity. Patient and graft survival rates were 98, 96 and 96 per cent, and 98, 96 and 93 per cent at 1, 3 and 5 years respectively. Three children had a second transplant at a median of 9 years after the first. The incidence of hepatic artery thrombosis, portal vein thrombosis and biliary complications was 6, 4 and 14 per cent respectively.

Conclusion

Living related liver transplantation has good long-term results in children.
Quality of life after liver resection for hepatobiliary malignancies
Authors: Dasgupta D , Smith A B , Hamilton-Burke W , Prasad K R , Toogood G J , Velikova G , Lodge J P A
Published: May 2008

Background

Few prospective longitudinal studies have used a validated quality of life (QOL) instrument in patients undergoing liver resection for hepatobiliary malignancy.

Methods

Patients undergoing liver resection for hepatobiliary tumours in a 1-year period were enrolled. The cancer-specific European Organization for Research and Treatment of Cancer core questionnaire (EORTC QLQ-C30) was completed before operation, and at 6, 12 and 36–48 months after surgery. QOL over time was analysed in relation to several clinical factors.

Results

A total of 103 patients were enrolled. Patient compliance was at least 75 per cent at all stages. Most functional scales and the global QOL scale showed a non-significant trend towards deterioration at 6 months and a return to preoperative level at 12 months. Physical functioning and dyspnoea deteriorated significantly at 6 months (P = 0·020 and P = 0·004 respectively) and did not recover by 12 months (P = 0·002 and P < 0·001 respectively). Pain and fatigue showed clinically significant deterioration over 12 months, which was not statistically significant. Survivors without recurrence at 36–48 months showed better QOL than those with recurrent disease.

Conclusion

Major liver resection is associated with acceptable QOL outcomes, and QOL continues to improve in the long term in those without recurrence.
Ileal pouch–anal anastomosis and liver transplantation for ulcerative colitis complicated by primary sclerosing cholangitis
Authors: Mathis K L , Dozois E J , Larson D W , Cima R R , Sarmiento J M , Wolff B G , Heimbach J K , Pemberton J H
Published: May 2008

Background

The aim was to evaluate outcomes in patients with ulcerative colitis complicated by primary sclerosing cholangitis (PSC) who required ileal pouch–anal anastomosis (IPAA) and orthotopic liver transplantation (OLT).

Methods

A retrospective analysis was performed of 32 patients undergoing both IPAA and OLT between 1980 and 2006. Data were collected regarding demographics, indication for surgery, postoperative complications, and outcome of IPAA and OLT.

Results

Thirty-day mortality after either procedure was nil. The median preoperative Model for End-stage Liver Disease (MELD) score for the group with initial IPAA was 8 (range 6–20) and the postoperative score was 11 (range 6–19). At 1 and 10 years, 32 and 26 of the 32 liver grafts had survived, and 31 and 30 of the 32 pouches, respectively. Fourteen patients require daily medical therapy for chronic pouchitis. At a median follow-up of 3·6 (range 0·2–16·2) years after the second of two procedures, responding patients reported a median of 5·5 stools per day and 2 stools per night.

Conclusion

IPAA and OLT are feasible and safe in patients requiring both procedures for ulcerative colitis and PSC. Functional outcomes are stable over time, despite an increased risk of chronic pouchitis.
High‐Strength Cellulose/Poly(ethylene glycol) Gels
Authors: Liang Songmiao , Wu Junjie , Tian Huafeng , Zhang Lina , Xu Jian
Published: May 2008

Cellulose gel membranes have been prepared by a pre‐gelation method employing cellulose solutions in aqueous NaOH–thiourea obtained at low temperature. The cellulose gels were then swollen by low‐molecular‐weight polyethylene glycol (PEG; MW<1000 g mol−1), and the morphology, structure and mechanical properties of the cellulose/PEG gels were studied by various techniques. The gels exhibit high mechanical performance, and the tensile strength of the gel membranes increases sharply with an increase in the molecular weight of PEG from 200 to 800 g mol−1. Moreover, their elongation at break remains stable at 100 %. PEG800 efficiently improves the optical transmittance of the gel membranes at ambient temperature, which is about five times greater than that of a normal cellulose hydrogel membrane. A strong hydrogen‐bonding interaction occurs between PEG and cellulose leading to a homogeneous structure, high mechanical strength and good transparency of the gel membranes.
A long‐term flow cytometry assay to analyze the role of specific genes of Drosophila melanogaster S2 cells in surviving genotoxic stress
Authors: Yi Xia , Lemstra Willy , Vos Michel J. , Shang Yongfeng , Kampinga Harm H. , Su Tin Tin , Sibon Ody C. M.
Published: May 2008

Drosophila S2 cells are easy to manipulate and culture and are a versatile model system for high‐throughput screens such as genome‐wide siRNA screens to find genes involved in stress or therapy resistance or for screening through large compound libraries to identify cytotoxins. Clonogenic assays are considered the gold‐standard to investigate the cytotoxicity of specific treatments or to compare the sensitivity of various cell types for a specific treatment. However, this assay cannot be used for Drosophila S2 cells as they are virtually unable to grow in distinct colonies. We designed a novel fluorescence‐based flow cytometry assay to study long‐term proliferation of S2 cells under various conditions and in the presence of specific gene products or after downregulation of specific gene products. Here we validate this assay and we used this novel method to investigate the role of checkpoint genes grapes/Dchk1 and DmChk2 in cell survival responses. Our data demonstrate that Grapes/Dchk1 but not DmChk2 is required to survive hydroxyurea. Our assay will be of use to investigate the long‐term effects of various treatments in S2 cells and to evaluate the role of specific proteins therein. © 2008 International Society for Advancement of Cytometry
Enhanced FRET contrast in lifetime imaging
Authors: Spriet Corentin , Trinel Dave , Riquet Franck , Vandenbunder Bernard , Usson Yves , Heliot Laurent
Published: May 2008

In combination with two photon excitation, FLIM is currently one of the best techniques to quantitatively study the subcellular localization of protein–protein interactions in living cells. An appropriate analysis procedure is crucial to obtain reliable results. TCSPC is an accurate method to measure FLIM. It is however an indirect process that requires photon decay curve fitting, using an exponential decay equation. Although choosing the number of exponential terms is essential, it is labor‐intensive and time consuming. Therefore, a mono‐model is usually applied to a whole image. Here we propose an algorithm, named Liχ, allowing pixel by pixel analysis based on the Δχ2 value. Liχ was validated using simulated photon decay curves with known lifetimes and proportions. It showed a high robustness for decay curves with more than 103 photons. When applied to lifetime images acquired from living cells, it resulted in a more realistic representation of the interaction maps. We developed an easy‐to‐use procedure for multi‐model FLIM analysis, which enables optimized FRET quantification for all interaction texture studies, and is especially suitable to avoid the classical misinterpretation of heterogeneous samples. © 2008 International Society for Advancement of Cytometry
On the error probability of quasi‐orthogonal space–time block codes
Authors: Yang Jae‐Dong , Jin Xianglan , No Jong‐Seon , Shin Dong‐Joon
Published: May 2008

In this paper, we derive the exact pairwise error probabilities (PEPs) of various quasi‐orthogonal space–time block codes (QO‐STBCs) using the moment generating function. By classifying the exact PEPs of QO‐STBCs into three types, we derive the closed‐form expression for each type of PEP. Based on these closed‐form expressions, we obtain the union bounds on the symbol error probability and bit error probability for QPSK modulation. Through simulation, it is shown that these union bounds are quite tight. Copyright © 2008 John Wiley & Sons, Ltd.
Reactivity of Phosphane–Imidazolium Salts Towards [Ir(COD)Cl]2: Preparation of New Hydridoiridium(III) Complexes Bearing Abnormal Carbenes
Authors: Wolf Joffrey , Labande Agnès , Daran Jean‐Claude , Poli Rinaldo
Published: May 2008

The unusual reactivity of chelating phosphane–imidazolium salts MesImEtPPh2+Br–, DIPP‐ImEtPPh2+Br–, and MesImEtPPh2+BF4– towards the low‐oxidation‐state iridium complex [Ir(COD)(μ‐Cl)]2 was studied. In the absence of a base, the C–H insertion at the C5 position of the imidazolium ring was the only reaction that occurred, with no normal NHC observed, leading to hydridoiridium(III) complexes. This reactivity was independent of the nature of the imidazolium counteranion and of the substitution pattern of the aryl group. (© Wiley‐VCH Verlag GmbH & Co. KGaA, 69451 Weinheim, Germany, 2008)
Quenching the Hysteresis in Single Crystals of a 1D Chain Iron(II) Spin Crossover Complex
Authors: Weber Birgit , Kaps Eike S. , Desplanches Cédric , Létard Jean‐François
Published: May 2008

The unusual grinding effects observed in the 1D spin crossover polymer [FeL(bipy)]n (1), with L being a tetradentate N2O22– coordinating Schiff base type ligand {(3,3′)‐[1,2‐phenylenebis(iminomethylidyne)]bis(2,4‐pentanedionato)(2–)‐N,N′,O2,O2′} and bipy = 4,4′‐bipyridine, are investigated using magnetic measurements, X‐ray powder diffraction and optical reflectivity studies. The observed behaviour can be explained when solvent effects are taken into account. (© Wiley‐VCH Verlag GmbH & Co. KGaA, 69451 Weinheim, Germany, 2008)
Cobalt‐Induced Synthesis of 6‐(Pyridin‐2‐yl)purines by Microwave‐Enhanced [2+2+2] Cyclotrimerization
Authors: Turek Pavel , Hocek Michal , Pohl Radek , Klepetářová Blanka , Kotora Martin
Published: May 2008

A novel, efficient, and atom‐economic methodology for the preparation of a large series of diversely substituted (pyridin‐2‐yl)purines has been developed. Thus, microwave‐enhanced [2+2+2] cyclotrimerization of 6‐(diynyl)purines with nitriles in the presence of a stoichiometric or catalytic amount of [CpCo(CO)2] afforded the corresponding products in good yields. The reactions carried out with various alkyl, aryl, and heteroaryl cyanides poceeded with exclusive regioselectivity, affording 6‐(pyridin‐2‐yl)purines. In an analogous manner, [2+2+2] cyclotrimerizations of 1,8‐bis(purinyl)‐1,7‐octadiynes with nitriles were conducted, yielding 1,4‐bis(purin‐6‐yl)‐5,6,7,8‐tetrahydroisoquinolines. (© Wiley‐VCH Verlag GmbH & Co. KGaA, 69451 Weinheim, Germany, 2008)
Determination of amino acids by capillary electrophoresis‐electrospray ionization‐mass spectrometry: An evaluation of different protein hydrolysis procedures
Authors: Simionato Ana V. Colnaghi , Moraes Edgar Perin , Carrilho Emanuel , Tavares Marina Franco Maggi , Kenndler Ernst
Published: May 2008

In this work, a CE equipment, online hyphenated to an IT MS analyzer by a linear sheath liquid interface promoting ESI, was used to develop a method for quantitative determination of amino acids. Under appropriate conditions (BGE composition, 0.8% HCOOH, 20% CH3OH; sheath liquid composition, 0.8% HCOOH, 60% methanol; VESI, +4.50 kV), analytical curves of all amino acids from 3 to 80 mg/L were recorded presenting acceptable linearity (r >0.99). LODs in the range of 16–172 μmol/L were obtained. BSA, a model protein, was submitted to different hydrolysis procedures (classical acid and basic, and catalyzed by the H+ form of a cation exchanger resin) and its amino acid profiles determined. In general, the resin‐mediated hydrolysis yields were overall similar or better than those obtained by classical acid or basic hydrolysis. The resulting experimental‐to‐theoretical BSA concentration ratios served as correction factors for the quantitation of amino acids in Brazil nut resin generated hydrolysates.
Application of capillary electrophoresis‐mass spectrometry for determining organic food contaminants and residues
Authors: Font Guillermina , Ruiz Maria José , Fernández Monica , Picó Yolanda
Published: May 2008

Food contamination continues to be a serious problem around the world. Surveillance of chemical contaminants in foods is important not only for public health but also because of the negative economic impact of contamination. From the analytical perspective, analysis of contaminants in food is an extremely challenging area. There is a wide variety of questions, ranging from the quantification of extremely low levels of individual components to the detailed assessment and evaluation of the analytical technique possibilities. This review considers the applications of CE coupled to MS detection (CE‐MS) for the analysis of organic contaminants in food. Analytical information on sample concentration techniques, as well as on the CE separation conditions and recoveries obtained from water and food are provided. Different sections include several fields of application, such as pesticides, drug residues, or toxic formed during food processing in different matrices. A number of tables report a comprehensive listing of CE‐MS applications. As a result, this work presents an update overview on the principal application of CE‐MS together with a discussion of their main advantages and drawbacks, and an outline of future trends on analysis of organic contaminants.
Sample complexity reduction for two‐dimensional electrophoresis using solution isoelectric focusing prefractionation
Authors: Richardson Matthew R. , Liu Sean , Ringham Heather N. , Chan Victor , Witzmann Frank A.
Published: May 2008

Despite its excellent resolving power, 2‐DE is of limited use when analyzing cellular proteomes, especially in differential expression studies. Frequently, fewer than 2000 protein spots are detected on a single 2‐D gel (a fraction of the total proteome) regardless of the gel platform, sample, or detection method used. This is due to the vast number of proteins expressed and their equally vast dynamic range. To exploit 2‐DE unique ability as both an analytical and a preparative tool, the significant sample prefractionation is necessary. We have used solution isoelectric focusing (sIEF) via the ZOOM® IEF Fractionator (Invitrogen) to generate sample fractions from complex bacterial lysates, followed by parallel 2‐DE, using narrow‐range IPG strips that bracket the sIEF fractions. The net result of this process is a significant enrichment of the bacterial proteome resolved on multiple 2‐D gels. After prefractionation, we detected 5525 spots, an approximate 3.5‐fold increase over the 1577 spots detected in an unfractionated gel. We concluded that sIEF is an effective means of prefractionation to increase depth of field and improve the analysis of low‐abundance proteins.
Lectin‐based electrophoretic analysis of the expression of the 35 kDa inter‐α‐trypsin inhibitor heavy chain H4 fragment in sera of patients with five different malignancies
Authors: Mohamed Emida , Abdul‐Rahman Puteri Shafinaz , Doustjalali Saeid Reza , Chen Yeng , Lim Boon‐Kiong , Omar Siti Zawiah , Bustam Anita Zarina , Singh Vivek Ajit , Mohd‐Taib Nur Aishah , Yip Cheng‐Har , Hashim Onn Haji
Published: May 2008

A 35 kDa glycoprotein whose abundance was previously demonstrated to be enhanced in sera of patients with endometrial adenocarcinoma (n = 12), was isolated from pooled sera of three of the cancer patients using champedak galactose‐binding lectin affinity chromatography in the present study. Subjecting it to 2‐DE and MS/MS, the glycoprotein was identified as the O‐glycosylated fragment of inter‐α‐trypsin inhibitor heavy chain H4 (ITIH4). When compared to control sera (n = 17), expression of the 35 kDa ITIH4 cleavage fragment was demonstrated to be significantly enhanced in sera of patients with breast carcinoma (n = 10), epithelial ovarian carcinoma (n = 10), and germ cell ovarian carcinoma (n = 10) but not in patients with nasopharyngeal carcinoma (n = 13) and osteosarcoma (n = 7). The lectin‐based electrophoretic bioanalytical method adopted in the present study may be used to assess the physiological relevance of ITIH4 fragmentation and its correlation with different malignancies, their stages and progression.
Noncovalent interactions in human plasma proteins analyzed by the comparison of nondenaturing and denaturing micro‐2‐D gel electrophoresis patterns after polypeptide assignment using matrix‐assisted laser desorption/ionization‐mass spectrometry and peptide mass fingerprinting
Authors: Manabe Takashi , Jin Ya
Published: May 2008

Previously, we reported the analysis of human plasma proteins by 2‐DE under nondenaturing conditions (Type‐I 2‐DE) followed by the assignment of stained spots using MALDI‐MS and PMF [1]. Here, we employ 2‐DE conditions modified only in the second‐dimensional separation; SDS was added in the gradient slab gel aiming to dissociate noncovalently bound proteins/polypeptides (Type‐II 2‐DE). Totally 169 CBB‐stained spots on a micro‐2‐DE gel were numbered and subjected to polypeptide assignment using MALDI‐MS‐PMF. One hundred sixty spots out of the 169 provided significant match (p <0.05) with polypeptides in databases. Comparisons of the results of polypeptide assignment on the two 2‐DE patterns indicated that 10 polypeptides in 20 stained spots on the Type‐I 2‐DE pattern [1] shifted toward low‐molecular‐weight positions on the Type‐II 2‐DE pattern, demonstrating the presence of noncovalent interactions. Seventeen polypeptides in 38 stained spots were only assigned on the Type‐II 2‐DE gel, which could mostly be accounted for by the disruption of noncovalent protein–protein interactions in the presence of SDS, i.e., protein/polypeptide complexes which might form smear bands on the Type‐I 2‐DE gel dissociate to form clear spots on the Type‐II 2‐DE gel. The method employed here, comparisons of nondenaturing and denaturing 2‐DE maps with polypeptide assignment by MALDI‐MS‐PMF, would enable the simultaneous detection of multiple noncovalent interactions in complex protein/polypeptide systems.
Microscale characterization of the binding specificity and affinity of a monoclonal antisulfotyrosyl IgG antibody
Authors: Lassen Klaus S. , Bradbury Andrew R. M. , Rehfeld Jens F. , Heegaard Niels H. H.
Published: May 2008

Sulfation is a potentially important post‐translational modification of proteins and has been demonstrated in a number of polypeptides, notably in gastrointestinal hormones. In contrast to phosphorylation, however, the investigation of sulfation patterns in tissues and on purified proteins has been complicated by the absence of specific immunoreagents (antibodies) for this modification as well as the chemical lability of the sulfate group. Here, we investigate the properties of a novel mAb against sulfated tyrosyl groups (anti‐Tyr(SO3H) antibody) using CE and a panel of sulfated and nonsulfated peptides and proteins. The data show that the anti‐Tyr(SO3H) antibody is completely specific for compounds containing sulfated tyrosyls. Affinity electrophoresis experiments allowed us to estimate dissociation constants for sulfated hirudin fragment (56–65), gastrin‐17, and cholecystokinin octapeptide (CCK8) in the 1–3 μM range. The affinity of the antibody toward complement 4 protein that contains three sulfotyrosines was analyzed by surface plasmon resonance technology and modeled according to a bivalent‐binding model which yielded a Kd1 of 20.1 μM for the monovalent complex. The same binding was studied by CE and found to be in the micromolar scale albeit with some uncertainty due to complex separation patterns. The work illustrates the amount of information on antibody–antigen interactions that may be obtained with microelectrophoretic methods consuming minute quantities of material. Furthermore the specificity of this antibody could be confirmed in one operation using an array of sulfated and nonsulfated compounds.
Proteomics of marine bacteria
Authors: Schweder Thomas , Markert Stephanie , Hecker Michael
Published: May 2008

Little is known about the life of marine microorganisms under their particular environmental conditions. Genome sequencing combined with the techniques of functional genomics, especially proteome analyses, now open up revolutionary insights into the adaptation strategies marine organisms have evolved in response to the challenges of their habitat. This report summarizes the first approaches and state‐of‐the‐art in the field of proteome analysis of marine bacteria. This includes, amongst others, proteomics on culturable, free‐living marine bacteria and on uncultivable bacteria living in symbiosis with higher organisms. Finally, new approaches to determine the metaproteome of uncultured microbial consortia from marine habitats are discussed.
Preparative isolation of protein complexes and other bioparticles by elution from polyacrylamide gels
Authors: Seelert Holger , Krause Frank
Published: May 2008

Due to its unmatched resolution, gel electrophoresis is an indispensable tool for the analysis of diverse biomolecules. By adaptation of the electrophoretic conditions, even fragile protein complexes as parts of intracellular networks migrate through the gel matrix under sustainment of their integrity. If the thickness of such native gels is significantly increased compared to the analytical version, also high sample loads can be processed. However, the cage‐like network obstructs an in‐depth analysis for deciphering structure and function of protein complexes and other species. Consequently, the biomolecules have to be removed from the gel matrix into solution. Several approaches summarized in this review tackle this problem. While passive elution relies on diffusion processes, electroelution employs an electric field to force biomolecules out of the gel. An alternative procedure requires a special electrophoresis setup, the continuous elution device. In this apparatus, molecules migrate in the electric field until they leave the gel and were collected in a buffer stream. Successful isolation of diverse protein complexes like photosystems, ATP‐dependent enzymes or active respiratory supercomplexes and some other bioparticles demonstrates the versatility of preparative electrophoresis. After liberating particles out of the gel cage, numerous applications are feasible. They include elucidation of the individual components up to high resolution structures of protein complexes. Therefore, preparative electrophoresis can complement standard purification methods and is in some cases superior to them.
Analysis of histones, histone variants, and their post‐translationally modified forms
Authors: Lindner Herbert H.
Published: May 2008

For many years, histones were considered passive structural components of eukaryotic chromatin. Meanwhile it has been proven that histones also participate in gene regulation and repression via post‐translational modification. The multitude of these post‐translational modifications and the existence of numerous histone variants require particular separation strategies for their analysis, a prerequisite for studying biological processes. The most widely utilized techniques for the separation of histones, namely PAGE, HPCE, RP‐HPLC, and hydrophilic Interaction LC, are reviewed here. Problems inherent to the analysis of histones owing to their unique physical and chemical properties along with advantages and shortcomings of particular methods are discussed.
Enhanced dechlorination of trichloroethylene by membrane‐supported Pd‐coated iron nanoparticles
Authors: Wu Linfeng , Ritchie Stephen M.C.
Published: May 2008

In this study, cellulose acetate (CA) supported iron and Pd/Fe nanoparticles were used for dechlorination of trichloroethylene (TCE) from water. Solution and microemulsion methods were used to synthesize the iron nanoparticles. Pd/Fe bimetallic particles were prepared by postcoating Pd on the prepared iron nanoparticles. These materials were then dispersed in CA solution, which was used to prepare the membrane‐supported nanoparticles. TEM imaging confirmed that the iron and Pd/Fe bimetallic nanoparticles were ∼10 nm in diameter. The results of dechlorination studies showed that the surface composition of the Pd/Fe bimetallic nanoparticles (microemulsion method) significantly affected the observed reduction rate constant. In addition, the rate constant was a nonlinear function of metal loading and initial TCE concentration. A comparative study for the Pd/Fe (Pd 1.9 wt %) nanoparticles from solution and microemulsion methods showed that the nanoparticles formed by the latter method gave superior performance for the dechlorination of TCE. © 2008 American Institute of Chemical Engineers Environ Prog, 2008
Tetraglyme coatings reduce fibrinogen and von Willebrand factor adsorption and platelet adhesion under both static and flow conditions
Authors: Zhang Min , Horbett Thomas A.
Published: May 2008

Previous studies have showed that radio‐frequency plasma deposited tetraglyme coatings greatly reduced fibrinogen adsorption (ΓFg) from highly diluted plasmas (0.1 and 1%) and subsequent platelet adhesion under static conditions. In this study, the protein resistant properties of tetraglyme were re‐examined with high‐concentration plasma, and subsequent platelet adhesion was measured under both static and flow conditions. The resistance of tetraglyme to vWf adsorption (ΓvWf) and the role of vWf in platelet adhesion under flow were also investigated. ΓFg and ΓvWf were measured with 125I radiolabeled proteins. Flow studies were done at shear rates of 50 or 500 s−1 by passing a platelet/red cell suspension through a GlycoTech flow chamber. When adsorbed from a series of increasing plasma concentrations, the adsorption of both proteins to tetraglyme increased steadily, and did not show a peak at intermediate dilutions, i.e., there was no Vroman effect. When plasma concentration was less than 10%, the tetraglyme surface was highly nonfouling, exhibiting ultralow ΓFg (less than 5 ng/cm2) and extremely low platelet adhesion under both static and flow conditions. However, when the adsorption was done from 100% plasma, ΓFg was much higher (∼85 ng/cm2), indicating that tetraglyme surface may not be sufficiently protein‐resistant in the physiological environment. To correlate platelet adhesion under flow with ΓFg and ΓvWf, a series of tetraglyme surfaces varying in ether content and protein adsorption was created by varying deposition power. On these surfaces, platelet adhesion at low shear rate depended only on the amount of ΓFg, but under high shear, both ΓFg and ΓvWf affected platelet adhesion. In particular, it was found that ΓvWf must be reduced to less than 0.4 ng/cm2 to achieve ultra low platelet adhesion under high shear. © 2008 Wiley Periodicals, Inc. J Biomed Mater Res, 2009
TiO2 nanotubes on Ti: Influence of nanoscale morphology on bone cell–materials interaction
Authors: Das Kakoli , Bose Susmita , Bandyopadhyay Amit
Published: May 2008

Ti being bioinert shows poor bone cell adhesion with an intervening fibrous capsule. Ti could be made bioactive by several methods including growing in situ TiO2 layer on Ti‐surface. TiO2 nanotubes were grown on Ti surface via anodization process and the bone cell–material interactions were evaluated. Human osteoblast cell attachment and growth behavior were studied using an osteoprecursor cell line for 3, 7, and 11 days. An abundant amount of extracellular matrix (ECM) between the neighboring cells was noticed on anodized nanotube surface with filopodia extensions coming out from cells to grasp the nanoporous surface of the nanotube for anchorage. To better understand and compare cell–materials interactions, anodized nanoporous sample surfaces were etched with different patterns. Preferential cell attachment was noticed on nanotube surface compare to almost no cells in etched Ti surface. Cell adhesion with vinculin adhesive protein showed higher intensity, positive contacts on nanoporous surface and thin focal contacts on the Ti‐control. Immunochemistry study with alkaline phosphatase showed enhanced osteoblastic phenotype expressions in nanoporous surface. Osteoblast proliferation was significantly higher on anodized nanotube surface. Surface properties changed with the emergence of nanoscale morphology. Higher nanometer scale roughness, low contact angle and high surface energy in nanoporous surface enhanced the osteoblast‐material interactions. Mineralization study was done under simulated body fluid (SBF) with ion concentration nearly equal to human blood plasma to understand biomimetic apatite deposition behavior. Although apatite layer formation was noticed on nanotube surface, but it was nonuniform even after 21 days in SBF. © 2008 Wiley Periodicals, Inc. J Biomed Mater Res, 2009