bluuebunny/crossref_metadata_2025_split huggingface dataset:
Click chemistry in materials synthesis. II. Acid‐swellable crosslinked polymers made by copper‐catalyzed azide–alkyne cycloaddition
Authors: Li Chunmei , Finn M. G. 
Published: August 2006

AbstractA highly crosslinked hyperbranched polymer that rapidly swells and shrinks in a halogenated solvent in response to the addition of an acid or base has been prepared by Cu(I) catalysis of the reaction between a diazide and an amine‐containing trialkyne. The triazole linkages in the polymer are highly stable and may also play a role in the swelling behavior. The swelling–deswelling process is reversible. © 2006 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 44: 5513–5518, 2006
Synthesis and comparative solution properties of single‐, twin‐, and triple‐tailed associating ionic polymers based on diallylammonium salts
Authors: Ali Sk. Asrof , Umar Yunusa , Abu‐Sharkh B. F. , Al‐Muallem Hasan A. 
Published: August 2006

AbstractThe cycloterpolymerizations of single‐, twin‐, and triple‐tailed hydrophobes with hydrophilic monomer N,N‐diallyl‐N‐carboethoxymethylammonium chloride and sulfur dioxide afforded a series of cationic polyelectrolytes (CPEs) in excellent yields. These CPEs, upon the acidic hydrolysis of the pendent ester groups, gave the corresponding pH‐responsive cationic acid salts, which, upon a treatment with sodium hydroxide, were converted to polybetaines (PBs), anionic polyelectrolytes (APEs), and PB/APE polymers containing various proportions of zwitterionic (PB) and anionic fractions (APE) in the polymer chain. At a shear rate of 0.36 s−1 at 30 °C, salt‐free water solutions of the CPEs (2 g/dL) containing 8, 4, and 2.67 mol % of the single‐, twin‐, and triple‐tailed hydrophobes (all having 8 mol % octyloxy tails) had apparent viscosity values of 70, 2800, and 396,000 cps, respectively. The PB/APE polymer with a ratio of 33:67 for the zwitterionic and anionic fractions in the polymer chain gave the highest viscosity value. The superior viscosity behavior of the polymers containing the triple‐tailed hydrophobe was attributed to the blocky nature of the comonomer. © 2006 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 44: 5480–5494, 2006
Infrared thermography analysis of the thermally latent polymerization of 3‐ethyl‐3‐phenoxymethyloxetane
Authors: Nagasawa Tomomi , Ochiai Bungo , Endo Takeshi 
Published: August 2006

AbstractInfrared thermography was employed to analyze multiple batches of the thermally latent polymerization of 3‐ethyl‐3‐phenoxymethyloxetane at once. The temperature changes in the polymerization depended on the polymerization rates. That is, a fast polymerization was exothermic, increasing the temporal temperature of the polymerization by approximately 130 °C within a few minutes. Infrared thermography, which can analyze multiple samples instantaneously, proved effective as a screening method for thermally latent curing systems. Exothermicity in the crosslinking polymerization of 1,4‐bis(3‐ethyloxetanylmethoxy)benzene was also analyzed by infrared thermography. © 2006 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 44: 5519–5524, 2006
Ultrasound in polymer chemistry: Revival of an established technique
Authors: Paulusse Jos M. J. , Sijbesma Rint P. 
Published: August 2006

AbstractThe history of ultrasound in polymer chemistry goes back a long way. Initially, its uses were limited to being an alternative method of initiating radical polymerizations through the decomposition of solvents to form radicals or through the breakage of polymers leading to macroradicals. Recently, the raw power of ultrasound has been focused through the use of weak linkages in polymer chains, which enables the production of well‐defined macroradicals and coordinatively unsaturated metal complexes. © 2006 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 44: 5445–5453, 2006
What elderly cancer patients want to know? Differences among elderly and young patients
Authors: Giacalone Annalisa , Blandino Michela , Talamini Renato , Bortolus Roberto , Spazzapan Simon , Valentini Mariagrazia , Tirelli Umberto 
Published: August 2006

AbstractThe aims of our study were: (1) to evaluate the information needs of Italian elderly cancer patients (age ⩾65 years), (2) to compare them with those of young patients (age 18–40 years). Between June 2004 and February 2005 we asked 122 elderly (mean age 72 years) and 52 young (mean age 33 years) cancer patients naïve for treatment to fill in two self‐administered questionnaires exploring their needs for information and their psychological distress. The needs for information of elderly patients differed significantly from those of the young patients (p<0.0001); on contrast, both groups showed a similar psychological distress and the same reasons for seeking further information. Our results demonstrate that, more frequently than expected, Italian elderly cancer patients do not want complete information on their disease. Assessing to what extent elderly patients require information is essential for giving them tailored information. Copyright © 2006 John Wiley & Sons, Ltd.
Biologically Multifunctional Surfaces Using Plasma Polymerization Methods
Authors: Chu Liqiang , Knoll Wolfgang , Förch Renate 
Published: August 2006

AbstractSummary: We report on the development of a multilayer system, which allows for specific DNA binding reactions to occur at the surface, but at the same time shows antifouling properties, thus minimizing the nonspecific adsorption of proteins (BSA). The synthesis involves the combination of plasma polymerization and streptavidin‐biotin assembly. DNA sensing is achieved using SPFS. Antifouling properties are tailored by controlling the film thickness, together with the effects of the swelling in buffer solution and by the specific surface chemical design. Preliminary hybridization experiments show promising results.The immobilization of biotin‐streptavidin within an antifouling pp‐EO2 plasma polymer.magnified imageThe immobilization of biotin‐streptavidin within an antifouling pp‐EO2 plasma polymer.
Synthesis and Characterization of 1‐Azido‐2‐Nitro‐2‐Azapropane and 1‐Nitrotetrazolato‐2‐Nitro‐2‐Azapropane
Authors: Boese Roland , Klapötke Thomas M. , Mayer Peter , Verma Vikas 
Published: August 2006

Abstract1‐Azido‐2‐nitro‐2‐azapropane (1) was synthesized in high yield from 1‐chloro‐2‐nitro‐2‐azapropane and sodium azide. 1‐Nitrotetrazolato‐2‐nitro‐2‐azapropane (2) was synthesized in high yield from 1‐chloro‐2‐nitro‐2‐azapropane and silver nitrotetrazolate. The highly energetic new compounds (1 and 2) were characterized using vibrational (IR and Raman) and multinuclear NMR spectroscopy (1H, 13C, 14N), elemental analysis and low‐temperature single crystal X‐ray diffraction. 1‐Azido‐2‐nitro‐2‐azapropane (1) represents a covalently bound liquid energetic material which contains both a nitramine unit and an azide group in the molecule. 1‐Nitrotetrazolato‐2‐nitro‐2‐azapropane (2) is a covalently bound room‐temperature stable solid which contains a nitramine group and a nitrotetrazolate ring unit in the molecule. Compounds 1 and 2 are hydrolytically stable at ambient conditions. The impact sensitivity of compound 1 is very high (<1 J) whereas compound 2 is less sensitive (<6 J).
Computational Study on Potassium Picrate Crystal
Authors: Ju Xue‐Hai , Lu Ya‐Lin , Ma Xiu‐Fang , Xiao He‐Ming 
Published: August 2006

AbstractDFT calculation at the B3LYP level was performed on crystalline potassium picrate. The frontier bands are slightly fluctuant. The energy gap between the highest occupied crystal orbital (HOCO) and the lowest unoccupied crystal orbital (LUCO) is 0.121 a.u. (3.29 eV). The carbon atoms that are connected with the nitro groups make up the narrow lower energy bands, with small contributions from nitro oxygen and phenol oxygen. The higher energy bands consist of orbitals from the nitro groups and carbon atom. The potassium bears almost 1 a.u. positive charge. The potassium forms ionic bonding with the phenol oxygen and the nitro oxygen at the same time. The crystal lattice energy is predicted to be −574.40 kJ/mol at the B3LYP level determined with the effective core pseudopotential HAYWSC‐31G basis set for potassium and 6‐31G** basis set for other atoms.
A Contribution to the Analysis of Corner Turning Rib Problems
Authors: Vágenknecht Jiří , Adamík Vladislav 
Published: August 2006

AbstractThe detonation process was studied theoretically and experimentally for circularly curved charges with both square and circular cross sections. Velocities of the front of the detonation wave along the inner and outer edge were monitored. For comparison with numerical simulations, the results of experiments from Lawrence Livermore National Laboratory (LLNL), USA and Department of Theory and Technology of Explosives (DTTX), Czech Republic were used. The ribs were simulated with LS‐DYNA code utilizing beta burn model for the explosives. The results of the numerical simulations were in a very good agreement with the experimental data.
The quantum Monte Carlo method
Authors: Towler M. D. 
Published: August 2006

AbstractQuantum Monte Carlo is an important and complementary alternative to density functional theory when performing computational electronic structure calculations in which high accuracy is required. The method has many attractive features for probing the electronic structure of real atoms, molecules and solids. In particular, it is a genuine many‐body theory with a natural and explicit description of electron correlation which gives consistent, highly‐accurate results while at the same time exhibiting favourable (cubic or better) scaling of computational cost with system size. This article is intended to provide a brief and hopefully accessible review of some relevant aspects of quantum Monte Carlo together with an outline of our implementation of it in the Cambridge computer code ‘CASINO’ [1, 2]. (© 2006 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)
Core‐level shifts in complex metallic systems from first principle
Authors: Olovsson Weine , Göransson Christian , Marten Tobias , Abrikosov Igor A. 
Published: August 2006

AbstractWe show that core‐level binding energy shifts (CLS) can be reliably calculated within density functional theory. The scheme includes both the initial (electron energy eigenvalue) as well as final state (relaxation due to core‐hole screening) effects in the same framework. The results include CLS as a function of composition in substitutional random bulk and surface alloys. Sensitivity of the CLS to the local chemical environment in the bulk and at the surface is demonstrated. A possibility to use the CLS for structural determination is discussed. Finally, an extension of the model is made for Auger kinetic energy shift calculations. (© 2006 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)
Criteria for the occurrence of negative resonant magnetoresistance in magnetic tunnel junctions
Authors: Ţolea Mugurel , Aldea Alexandru , Ţolea Felicia 
Published: August 2006

AbstractThe dependence of the driven‐current through a tunnel junction on the relative orientation of the magnetization in the electrodes deviates from the Julliere formula when the current is resonant through impurity levels. For asymmetric coupling of the impurities to the electrodes, the magnetoresistance can even be negative on the resonance. Such inversion in sign is due to the fact that not only the density of states in the electrodes is important (for both orientations of spins), but also the density of states at the impurity position, which has a specific behavior. We find the exact conditions under which the negative magnetoresistance occurs, as function of both polarization and coupling asymmetry. The resonant magnetoresistance may have single or double‐dip aspect, depending on the mentioned parameters. (© 2006 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)
Open system dynamics approach to polyatomic molecules: Excitons in chromophore complexes
Authors: May Volkhard 
Published: August 2006

AbstractAn introduction to the dissipative quantum dynamics description of molecular system is presented based on the definition of a reduced density operator $\hat{\rho}$(t) for the system under consideration. Methods are reviewed that have been used to calculate $\hat{\rho}$(t) with emphasis on an approximate equation of motion known as the quantum master equation. The inclusion of external ultrafast fields is particularly accounted for, and a brief description of femtosecond laser pulse control experiments is given. Different applications are mentioned, concentrating on the description of Frenkel‐exciton dynamics in biological chromophore complexes (photosynthetic antennae). Finally, recent achievements guiding exciton transfer by tailored femtosecond laser pulses are considered. © 2006 Wiley Periodicals, Inc. Int J Quantum Chem, 2006
Determination of Nε‐(carboxymethyl)lysine in exhaled breath condensate using isotope dilution liquid chromatography/electrospray ionization tandem mass spectrometry
Authors: Gonzalez‐Reche Luis M. , Kucharczyk Anna , Musiol Anita K. , Kraus Thomas 
Published: August 2006

AbstractIn order to identify new biomarkers for pulmonary diseases in exhaled breath condensate (EBC) it was the aim of this study to develop an analytical method for the identification and quantification of Nε‐(carboxymethyl)lysine (CML) in EBC. As detection by liquid chromatography with positive electrospray ionization tandem mass spectrometry (LC/ESI‐MS/MS) offers the advantage of structurally related detection with the necessary specificity required for the identification of a substance, it was the method chosen for the determination of the non‐volatile compound. Specific mass transitions and comparison of retention times with standards under given conditions were used for the unequivocal identification of CML in EBC of healthy subjects. Synthesis of isotopically labelled CML was performed and used as an internal standard for an accurate determination. It was possible to identify the advanced glycation end‐product CML in 8 out of 10 healthy subjects. The concentration range determined in the quantifiable examined samples ranged between 35 and 110 pg/mL. EBC samples from 11 patients with different diseases such as diabetes and chronic obstructive pulmonary disease were also measured. In one patient with pneumonia a concentration of 1509 pg CML/mL EBC could be detected. This is the first time that CML has been identified and determined in EBC. The developed LC/ESI‐MS/MS method could be used to address the utility of CML as a biomarker in pulmonary diseases. Copyright © 2006 John Wiley & Sons, Ltd.
Quantitative determination of major active components in Ginkgo biloba dietary supplements by liquid chromatography/mass spectrometry
Authors: Ding Shujing , Dudley Ed , Plummer Sue , Tang Jiandong , Newton Russell P. , Brenton A. Gareth 
Published: August 2006

AbstractA reversed‐phase high‐performance liquid chromatography/electrospray ionisation mass spectrometry (RP‐HPLC/ESI‐MS) method was developed and validated for the simultaneous determination of ten major active components in Ginkgo biloba extract (bilobalide, ginkgolides A, B, C, quercetin, kaempferol, isorhamnetin, rutin hydrate, quercetin‐3‐β‐D‐glucoside and quercitrin hydrate) which have not been previously reported to be quantified in a single analysis. The ten components exhibit baseline separation in 50 min by C18 chromatography using a water/1:1 (v/v) methanol/acetonitrile gradient. Quantitation was performed using negative ESI‐MS in selected ion monitoring (SIM) mode. Good reproducibility and recovery were obtained by this method. The sensitivity of both UV and different mass spectrometry modes (full scan, selected ion monitoring (SIM), and selected reaction monitoring (SRM)) were compared and both quantitation with and without internal standard were evaluated. The analysis of Ginkgo biloba commercial products showed remarkable variations in the rutin and quercetin content as well as the terpene lactone contents although all the products satisfy the conventional quality control method. Copyright © 2006 John Wiley & Sons, Ltd.
Moving from fast to ballistic gradient in liquid chromatography/tandem mass spectrometry pharmaceutical bioanalysis: matrix effect and chromatographic evaluations
Authors: De Nardi Claudio , Bonelli Fabio 
Published: August 2006

AbstractThe paper describes the steps taken by the authors to move from a fast to a ballistic gradient in routine liquid chromatography/tandem mass spectrometry (LC/MS/MS) analysis of plasma samples from pharmacokinetic (PK) profiling of new chemical entities. The reduction of column dimensions from 50 × 4.6 mm to 30 × 2.1 mm followed by optimization of chromatographic separation led to a decrease in the typical runtime from 5 (fast) to 2 min (ballistic) using an API4000 tandem mass spectrometer in Turbo Ionspray mode for detection. Three analytical standards representing typical molecular structures from our sample repository were used to spike plasma from four different species (rat, dog, human and mouse). Two different approaches were used to evaluate matrix effect: post‐column infusion and comparison of the peak areas of neat standards and standards spiked after extraction into different pools of plasma; the influence of PEG400 as a typical dosing vehicle was also considered. Two different protein precipitation procedures were taken into account for sample extraction prior to injection. Peak shape, width and height, selectivity and sensitivity of the method were taken into account for chromatographic evaluation. The ballistic method was successfully cross‐validated with the conventional fast gradient chromatographic assay. Copyright © 2006 John Wiley & Sons, Ltd.
Analysis of amino acid 13C abundance from human and faunal bone collagen using liquid chromatography/isotope ratio mass spectrometry
Authors: McCullagh James S. O. , Juchelka Dieter , Hedges Robert E. M. 
Published: August 2006

AbstractThe scope of compound‐specific stable isotope analysis has recently been increased with the development of the LC IsoLink which interfaces high‐performance liquid chromatography (HPLC) and isotope ratio mass spectrometry (IRMS) to provide online LC/IRMS. This enables isotopic measurement of non‐volatile compounds previously not amenable to compound‐specific analysis or requiring substantial modification for gas chromatography/combustion/isotope ratio mass spectrometry (GC/C/IRMS), which results in reduced precision. Amino acids are an example of such compounds.We present a new chromatographic method for the HPLC separation of underivatized amino acids using an acidic, aqueous mobile phase in conjunction with a mixed‐mode stationary phase that can be interfaced with the LC IsoLink for compound‐specific δ13C analysis. The method utilizes a reversed‐phase Primesep‐A column with embedded, ionizable, functional groups providing the capability for ion‐exchange and hydrophobic interactions. Baseline separation of 15 amino acids and their carbon isotope values are reported with an average standard deviation of 0.18‰ (n = 6). In addition δ13C values of 18 amino acids are determined from modern protein and archaeological bone collagen hydrolysates, demonstrating the potential of this method for compound‐specific applications in a number of fields including metabolic, ecological and palaeodietary studies. Copyright © 2006 John Wiley & Sons, Ltd.
Rapid determination of three anticoagulant rodenticides in whole blood by liquid chromatography coupled with electrospray ionization mass spectrometry
Authors: Jin Mi‐cong , Chen Xiao‐hong 
Published: August 2006

AbstractA rapid, sensitive and selective method for the simultaneous determination of bromadiolone, flocoumafen and brodifacoum in whole blood using warfarin as internal standard (IS) by high‐performance liquid chromatography coupled with electrospray ionization mass spectrometry (HPLC/ESI‐MS) has been developed and validated. The target compounds were extracted from the whole blood with ethyl acetate and separated on an XDB C18 column (150 mm × 2.1 mm i.d. × 5 µm) by using a mobile phase consisting of 0.2% acetic acid/methanol (12/88, v/v) at a constant flow rate of 0.50 mL/min. The analytes were detected using negative ESI‐MS in the selected ion monitoring (SIM) mode. The molecular ions [MH]− of m/z 527, 541,523 and 307 were selected for the quantification for bromadiolone, flocoumafen, brodifacoum and the IS, respectively. The calibration curves were linear (r2 > 0.995) in the concentration range of 0.50–100.00 ng/mL. The method showed a satisfactory sensitivity (0.05–0.5 ng/mL using 200 µL blood), precision (RSD < 11.9%), accuracy (recovery: 82.0–96.1%) and selectivity. This method was successfully applied to the determination of the analytes for the diagnoses of poisoned human beings and animals. Copyright © 2006 John Wiley & Sons, Ltd.
Intact cell matrix‐assisted laser desorption/ionization mass spectrometry as a tool to screen drugs in vivo for regulation of protein expression
Authors: Kulkarni Mahesh J. , Vinod V. P. , Umasankar P. K. , Patole Milind S. , Rao Mala 
Published: August 2006

AbstractHere we demonstrate for the first time the application of intact cell matrix‐assisted laser desorption/ionization mass spectrometry (ICM‐MS) to study the regulation of protein expression. This technique can be extended to screen the drugs that inhibit protein synthesis in various diseases. We have used Escherichia coli cells expressing a recombinant glutathione‐S‐transferase (GST) gene under an arabinose‐inducible promoter as a model system. Using ICM‐MS analysis, we have detected a 28 kDa peak corresponding to the production of recombinant GST under the arabinose‐induced condition. Furthermore, recombinant GST protein was purified by a single‐step affinity purification using a glutathione Sepharose 4B affinity column from arabinose‐induced E. coli cells. The purified GST protein was found to be a 28 kDa protein by MALDI analysis suggesting the arabinose‐induced protein is indeed GST. The regulation of protein expression was studied using glucose as an alternative metabolite. The glucose‐mediated regulation of the ara‐operon was followed using the ICM‐MS technique. All the results obtained from ICM‐MS data were validated using sodium dodecyl sulfate polyacrylamide gel electrophoresis (SDS‐PAGE) analysis. The present technique can be extended for in vivo screening of drugs and it holds tremendous potential to discover novel drugs against specific protein expressions in different diseases. Copyright © 2006 John Wiley & Sons, Ltd.
Use of the local Knox statistic for the prospective monitoring of disease occurrences in space and time
Authors: Brooke Marshall J. , Spitzner Dan J. , Woodall William H. 
Published: August 2006

AbstractThe detection of clusters of events occurring close together both temporally and spatially is important in finding outbreaks of disease within a geographic region. The Knox statistic is often used in epidemiology to test for space–time clustering retrospectively. For quicker detection of epidemics, prospective methods should be used in which observed events in space and time are assessed as they are recorded. The cumulative sum (CUSUM) surveillance method for monitoring the local Knox statistic tests for space–time clustering each time there is an incoming observation. We consider the design of this control chart by determining the in‐control average run length (ARL) performance of the CUSUM chart for different space and time closeness thresholds as well as for different control limit values. We also explain the effect of population density and region shape on the in‐control ARL and discuss other distributional issues that should be considered when implementing this method. Copyright © 2006 John Wiley & Sons, Ltd.