bluuebunny/crossref_metadata_2025 huggingface dataset:
Surface modification of polycarbonate by radio‐frequency plasma and optimization of the process variables with response surface methodology
Authors: Gomathi N. , Eswaraiah C. , Neogi Sudarsan
Published: June 2009

This study deals with the radio‐frequency plasma treatment of polycarbonate surfaces with argon. The wettability of polycarbonate was examined by static contact angle measurements with polar solvents (deionized water and formamide) and a nonpolar solvent (diiodomethane). The surface free energy of the polycarbonate obtained from the measured contact angle demonstrated that exposure to argon plasma resulted in an increased surface energy and polarity compared to the untreated polycarbonate. Attenuated total reflection/Fourier transform infrared spectroscopy indicated that argon plasma treatment resulted in surface chemistry changes by hydrogen abstraction from the phenyl ring and methyl group and chain scission at the ether and carbonyl sites. These led to the formation of hydroxyl groups and double bonds. With scanning electron microscopy and atomic force microscopy analysis, changes in the surface morphology and roughness before and after plasma treatment were observed. We followed an experimental matrix with the identified process variables affecting the wettability of the polymer, and optimized the experiments with the response surface methodology of a central composite design. A quadratic model was developed to represent the surface energy in terms of process variables. Optimized process conditions were derived from the predicted model and were confirmed by the experimental data at the predicted optimum conditions. The prediction accuracy of the model was found to be very high. © 2009 Wiley Periodicals, Inc. J Appl Polym Sci, 2009
Synthesis and metal ion adsorption properties of poly(4‐sodium styrene sulfonate‐co‐acrylic acid)
Authors: Rivas Bernabé L. , Muñoz Carla
Published: June 2009

The water‐insoluble resin poly(sodium 4‐styrene sulfonate‐co‐acrylic acid) was synthesized through a solution radical polymerization with ammonium persulfate as an initiator and N,N′‐methylene‐bis‐acrylamide as a crosslinking reagent (CR) at different amounts (2, 4, 6, and 8 mol %). The polymerization yield ranged from 75 to 91%. The metal ion retention properties were studied by batch and column equilibrium procedures for: Cd(II), Cr(III), Zn(II), Al(III), Pb(II), and Hg(II). These properties were investigated under competitive and noncompetitive conditions. The effect of pH, particle size, time, temperature, and initial metal ion concentration on metal ion adsorption was investigated. The resins showed a high retention ability for Hg(II) ions over 85% at pH 2 and for Cd(II), Cr(III), Zn(II), and Pb(II) over 96% at pH 5. The maximum adsorption performance for Pb(II) was achieved as 148.5 mg/g at an optimum pH. © 2009 Wiley Periodicals, Inc. J Appl Polym Sci, 2009
Effect of carboxymethyl cellulose concentration on rheological behavior of milk and aqueous systems. A creep and recovery study
Authors: Bayarri S. , Dolz M. , Hernández M. J.
Published: June 2009

Carboxymethyl cellulose (CMC) is an anionic polysaccharide used mainly as stabilizer and thickener agent. The purpose of this study was to investigate the effect of CMC concentration on viscoelasticity of dairy and aqueous model systems through the analysis of creep and recovery tests. The viscoelastic properties of different concentrations of CMC (0.75, 1.00, 1.25, and 1.50% w/w) in two milk systems (skimmed milk and whole milk) were compared with those of the same concentration of biopolymer in aqueous solution. Creep curves were fitted to a six parameter mechanical model (Burger + Kelvin‐Voigt), whereas an empirical equation was used for recovery. The creep and recovery properties of samples were clearly affected by both the type of dispersing media and the CMC concentration. The whole‐milk system was more elastic than both the biopolymer (CMC) aqueous solution and the skimmed‐milk sample, indicating that in whole‐milk samples some new interactions could take place between macromolecules. © 2009 Wiley Periodicals, Inc. J Appl Polym Sci, 2009
Interaction of microcrystalline chitosan (MCCh) with Mo(VI) in aqueous solution
Authors: Kufelnicki Aleksander , Lichawska Marta E. , Bodek Kazimiera H.
Published: June 2009

The molybdenum(VI) complex formation equilibria of microcrystalline chitosan (MCCh) with three different degrees of deacetylation (DD = 0.750, 0.812, and 0.948) were studied by pH‐potentiometric and UV‐spectrophotometric methods. The hydrolysis constants of Mo(VI) were evaluated under exactly the same conditions as during the experiments in presence of chitosan. It has been shown that the complexation model depends on DD. Besides the formation of a ligand to metal 2 : 1 MoO2B22+ complex (“bridge model”) with A = MoO42−, B = MCCh, H = proton, the 1 : 1 MoO3B species (“pendant model”) has been confirmed as well for the two lower values of DD and moderate excess of ligand. At the highest DD, the results indicate only the occurrence of 2 : 1 species. When taking into account the number of protons in reaction as the third index, the corresponding average overall stability constants log βabh of MoO3B and MoO2B22+ reach log β112 = 13.8 and log β124 = 27.9, respectively. © 2009 Wiley Periodicals, Inc. J Appl Polym Sci, 2009
Thermal stability eminence of PMMA prepared in presence of photosynthesized ruthenium carbonyl Schiff base as a catalyst
Authors: Youssef Teraze A. , Mekewi Mohamed A.
Published: June 2009

Sunlight irradiation reaction of Ru3(CO)12 with a Schiff base, bis (acetyl acetone) ethylene diimine, acacenH2, in benzene results in the formation of an octahedral complex [Ru(CO)2(acacen)] with a tetradentate ligand. The complex was structurally confirmed using elemental analysis, infrared, mass spectrometry, 1HNMR, UV–vis absorption spectra, and magnetic measurements. [Ru(CO)2(acacen)] complex compound was then used as a catalyst for the polymerization of methyl methacrylate (MMA) in the presence of sodium bisulfite as a cocatalyst. FT‐IR, gel permeation chromatography (GPC) was used as a tool for structure confirmation and molecular weights of the poly methyl methacrylate (PMMA). The stability of the catalyzed polymer against thermal degradation was investigated using thermal gravimetric analysis (TGA) and differential thermal analysis (DTA) to assess its distinctive thermal stability. Higher thermal stability of PMMA samples prepared in presence of [Ru(CO)2(acacen)] compared with blank PMMA were clearly observed. A reaction mechanism was suggested based on the coordination of the complex compound with the polymeric chains. © 2009 Wiley Periodicals, Inc. J Appl Polym Sci, 2009
Thermal degradation and flammability of P/Si polysilsesquioxane epoxy nanocomposites
Authors: Chiu Yie‐Chan , Ma Chen‐Chi M. , Liu Fang‐Yi , Chou I‐Chen , Chiang Chin‐Long , Yang Jeng‐Cheng
Published: June 2009

A thermal stable epoxy nanocomposite prepared from the 4,4′‐diglycidylether bisphenol A (DGEBA) and the P/Si ladder‐like polysilsesquioxane (PSSQ). The activation energies of thermal degradation were calculated by Kissinger's and Ozawa's methods. The higher ladder‐like PSSQ content not only increase the oligomer content but also generate the steric hindrance. Which steric hindrance influence the epoxy/amine curing reaction of the modified epoxy system was more than the pristine DGEBA epoxy system. The P‐Si synergistic effect on the thermal stability of the nanocomposites was discussed. © 2009 Wiley Periodicals, Inc. J Appl Polym Sci, 2009
Conductive plastics with hybrid materials
Authors: Immonen Kirsi , Nättinen Kalle , Sarlin Juha , Hartikainen Juha
Published: June 2009

Hybrid materials of conducting polyaniline (PANi) and multiwalled carbon nanotubes (CNTs) were synthesized using an in situ polymerization method. The resulting CNTs with a thin layer of PANi coating were further compounded with polypropylene to produce electrically conductive composite material. The PANi coating was found to enhance the CNT dispersion in PP. An amphiphilic component was also used as a surfactant to further enhance the dispersion. With these methods and materials, a conductivity of 26 S cm−1 was obtained. The conductivity of the hybrid material far exceeded that of the separately compounded mixture and of that prepared of lower aspect ratio conductive materials: carbon nanofibers and carbon black. The level of conductivity qualifies the material for use in applications requiring electromagnetic interference shielding. By adjusting the PANi loading, the conductivity can be tuned down to obtain materials suitable for electrostatic discharge applications. © 2009 Wiley Periodicals, Inc. J Appl Polym Sci, 2009
Structure‐rheology responses of polylactide/calcium carbonate composites
Authors: Gu Shu‐Ying , Zou Cun‐Yang , Zhou Kai , Ren Jie
Published: June 2009

Polylactide (PLA) and calcium carbonate (CaCO3) were melt blended using a twin‐screw extruder. The morphology of PLA/CaCO3 composites was observed by scanning electronic microscopy. The linear and nonlinear shear rheological behaviors of PLA/CaCO3 melts were investigated by an advanced rheology expended system. The results show that the CaCO3 particles are evenly dispersed in the PLA matrix. The incorporation of low CaCO3 content (<20%) causes the reduction of the storage moduli, loss moduli, and dynamic viscosities whereas high CaCO3 content (>30%) leads to the increase of the storage moduli, loss moduli, and dynamic viscosities. The composites with high CaCO3 content show pseudo‐solid‐like behaviors at low frequency. High CaCO3 content also results in a significant increase of flow activation energy and a dramatic decrease of flow index n, which is in consistent with the more serious shear‐thinning tendency of high‐filled PLA composites melts. The particular rheological responses might be attributed to the formation and destruction of the percolating network. © 2009 Wiley Periodicals, Inc. J Appl Polym Sci, 2009
Additive effect of poly(ethylene oxide) on polypropylene/fibrous cellulose composite: Effects of additive amount of poly(ethylene oxide) on Young's modulus and morphology
Authors: Miyazaki Kensuke , Nakatani Hisayuki
Published: June 2009

In this work, the additive effects of the poly(ethylene oxide) (PEO) on the Young's moduli of two kinds of polypropylene (PP)/fibrous cellulose (FC) composite were studied using the Kerner–Nielsen equation. In the case of the PP/maleated PP (MAPP)/FC + PEO composite, all the values of the moduli with the various PEO contents were in good agreement with the theoretical values obtained from the Kerner–Nielsen equation. Whereas the moduli of the PEO/FC + PP/MAPP composite followed the Kerner–Nielsen equation about 6 vol % of the PEO content and then unexpectedly deviated. In the scanning electron microscopy (SEM) observation, the PP/MAPP/FC + PEO composite was found to have a sea‐island morphology corresponding to the PP/MAPP/FC matrix and the PEO phase. This morphology had been unchanged against the increase of the PEO content. Whereas in the case of the PEO/FC + PP/MAPP composite, the SEM micrographs showed that that the interface between the FC and the PP became worse with the increase of the PEO content, indicating that the formation of the PP/MAPP/FC matrix was blocked by the excess PEO. The deviation of the Young's moduli from the Kerner–Nielsen equation was due to the blocking of the PEO. It was found that the adequate combination of the PEO and the MAPP was able to supply the increase of the toughness of the PP/FC composite by investigating the dependence of the PEO/FC + PP/MAPP composite on the MAPP content. © 2009 Wiley Periodicals, Inc. J Appl Polym Sci, 2009
Thiol containing sulfonamide based polymeric sorbent for mercury extraction
Authors: Yavuz Erdem , Barim Gamze , Senkal Bahire Filiz
Published: June 2009

A new polymeric resin with thiol pendant functions has been prepared for the extraction of mercuric ions. The thiol containing sulfonamide based resin with 3.5 mmol/g total nitrogen content is able to selectively sorb mercury from aqueous solutions. The mercury sorption capacity of the resin is around 1.70 mmol/g under non‐buffered conditions. Experiments performed in identical conditions with several metal ions revealed that Cd(II), Pb(II), Zn(II), Fe(III), and Fe (II) ions also were extractable in quantities (1.0–1.65 mmol/g). The sorbed mercury can be eluted by repeated treatment with 4M HNO3 without hydrolysis of the amide groups. © 2009 Wiley Periodicals, Inc. J Appl Polym Sci, 2009
Trabecular Microarchitecture of Hominoid Thoracic Vertebrae
Authors: Cotter Meghan M. , Simpson Scott W. , Latimer Bruce M. , Hernandez Christopher J.
Published: June 2009

Spontaneous vertebral fractures are a common occurrence in modern humans, yet these fractures are not documented in other hominoids. Differences in vertebral bone strength between humans and apes associated with trabecular bone microarchitecture may contribute to differences in fracture incidence. We used microcomputed tomography to examine trabecular bone microarchitecture in the T8 vertebra of extant young adult hominoids. Scaled volumes of interest from the anterior vertebral body were analyzed at a resolution of 46 μm, and bone volume fraction, trabecular thickness, trabecular number, trabecular separation, structure model index, and degree of anisotropy were compared among species. As body mass increased, so did trabecular thickness, but bone volume fraction, structure model index, and degree of anisotropy were independent of body mass. Bone volume fraction was not significantly different between the species. Degree of anisotropy was not significantly different among the species, suggesting similarity of loading patterns in the T8 vertebra due to similar anatomical and postural relationships within each species' spine. Degree of anisotropy was negatively correlated with bone volume fraction (r2 = 0.85, P < 0.05) in humans, whereas the apes demonstrated no such relationship. This suggested that less dense human trabecular bone was more preferentially aligned to habitual loading. Furthermore, we theorize that trabeculae in ape thoracic vertebrae would not be expected to become preferentially aligned if bone volume fraction was decreased. The differing relationship between bone volume fraction and degree of anisotropy in humans and apes may cause less dense human bone to be more fragile than less dense ape bone. Anat Rec, 2009. © 2009 Wiley‐Liss, Inc.
New and improved: The role of text augmentation and the application of response interpretation standards (coding schemes) in a final iteration of birth defects warnings development
Authors: Mayhorn Christopher B. , Goldsworthy Richard C.
Published: June 2009

BACKGROUND:

Several birth defects warning symbols identified as most successful in an earlier study (Mayhorn and Goldsworthy, 2007) were further modified and then evaluated within a nationally distributed field trial (n = 2773). The purpose for the current research was to determine whether symbol warning components could be improved further, whether the addition of text enhanced comprehension uniformly across symbols, and whether results varied by the application of different interpretation standards (coding schemes).

METHOD:

A total of 11 warning labels were examined: four new symbols plus the existing baseline symbol, each in versions with and without text, plus a text‐only condition. Participant interpretation accuracy and preferences were assessed during face‐to‐face interview sessions.

RESULTS:

For symbol‐only conditions, several candidate symbols outperformed the existing symbol, one substantially so. The effect of adding text to symbols varied significantly by symbol. Symbol plus text and text‐only conditions performed equivalently, generally exceeded symbol‐only conditions, and often surpassed the American National Standards Institute benchmark of 85% accurate interpretation.

CONCLUSIONS:

The research effort has identified a teratogen symbol and warning that outperforms the one currently in use. The effort has also identified important pragmatic and conceptual issues that should inform future work to improve medication labeling and other hazard communication. Birth Defects Research (Part A), 2009. © 2009 Wiley‐Liss, Inc.
The influence of pulsed magnetic fields (PMFs) on nonsynaptic potentials recorded from the central and peripheral nervous systems in vitro
Authors: Ahmed Zaghloul , Wieraszko Andrzej
Published: June 2009

The influence of pulsed magnetic fields (PMFs) on nonsynaptic potentials recorded from the central and peripheral nervous system in vitro has been investigated. The population spikes (PSs) recorded from hippocampal slices during antidromic stimulation and compound action potentials (CAPs) recorded from the segments of the sciatic nerve were used as indicators of neuronal activity. The potentials recorded from both preparations were significantly and permanently enhanced following PMF (0.16 Hz, 15 mT) exposure. The increase in the antidromic PS occurred even in the presence of potassium channel blocker tetraethylammonium (TEA) and was accompanied by multiple spiking. Among all frequencies of PMF tested (0.5, 0.16, 0.07, 0.03, 0.0 Hz), the frequency of 0.5 Hz was the most effective in enhancement of potential amplitude. The influence of PMF on the amplitude of two CAPs evoked by the pair of electrical stimuli applied in rapid succession has also been evaluated. In control conditions the potential triggered by the second stimuli was slightly smaller expressing the phenomenon of short‐term depression (STD). Although PMF exposure amplified the amplitude of both potentials, the increase in the size of the first potential was significantly greater increasing further the magnitude of STD. The blocking of potassium channels reversed STD into facilitation. One of the possible mechanisms involved in PMF action could be the modification of the axonal threshold, which was significantly reduced following exposure to PMF. Bioelectromagnetics 30:621–630, 2009. © 2009 Wiley‐Liss, Inc.
Hypersensitivity to RF fields emitted from CDMA cellular phones: A provocation study
Authors: Nam Ki Chang , Lee Ju Hyung , Noh Hyung Wook , Cha Eun Jong , Kim Nam Hyun , Kim Deok Won
Published: June 2009

With the number of cellular phone users rapidly increasing, there is a considerable amount of public concern regarding the effects that electromagnetic fields (EMFs) from cellular phones have on health. People with self‐attributed electromagnetic hypersensitivity (EHS) complain of subjective symptoms such as headaches, insomnia, and memory loss, and attribute these symptoms to radio frequency (RF) radiation from cellular phones and/or base stations. However, EHS is difficult to diagnose because it relies on a person's subjective judgment. Various provocation studies have been conducted on EHS caused by Global System for Mobile Communications (GSM) phones in which heart rate and blood pressure or subjective symptoms were investigated. However, there have been few sham‐controlled provocation studies on EHS with Code Division Multiple Access (CDMA) phones where physiological parameters, subjective symptoms, and perception of RF radiation for EHS and non‐EHS groups were simultaneously investigated. In this study, two volunteer groups of 18 self‐reported EHS and 19 non‐EHS persons were tested for both sham and real RF exposure from CDMA cellular phones with a 300 mW maximum exposure that lasted half an hour. We investigated not only the physiological parameters such as heart rate, respiration rate, and heart rate variability (HRV), but also various subjective symptoms and the perception of EMF. In conclusion, RF exposure did not have any effects on physiological parameters or subjective symptoms in either group. As for EMF perception, there was no evidence that the EHS group better perceived EMF than the non‐EHS group. Bioelectromagnetics 30:641–650, 2009. © 2009 Wiley‐Liss, Inc.
Polycomb group proteins: remembering how to catch chromatin during replication
Authors: Kumar Ram Parikshan
Published: June 2009

Polycomb group (PcG) proteins maintain the expression state of PcG‐responsive genes during development of multicellular organisms. Recent observations suggest that “the H3K27me3 modification” acts to maintain Polycomb repressive complex (PRC) 2, the enzyme that creates this modification, on replicating chromatin. This could in turn promote propagation of H3K27me3 on newly replicated daughter chromatin, and promote recruitment of PRC1. Other work suggests that PRC1‐class complexes can be maintained on replicating chromatin, at least in vitro, independently of H3K27me3. Thus, histone modifications and PcG proteins themselves may both be maintained through replication.
Error propagation from prime variables into specific rates and metabolic fluxes for mammalian cells in perfusion culture
Authors: Goudar Chetan T. , Biener Richard , Konstantinov Konstantin B. , Piret James M.
Published: June 2009

Error propagation from prime variables into specific rates and metabolic fluxes was quantified for high‐concentration CHO cell perfusion cultivation. Prime variable errors were first determined from repeated measurements and ranged from 4.8 to 12.2%. Errors in nutrient uptake and metabolite/product formation rates for 5–15% error in prime variables ranged from 8–22%. The specific growth rate, however, was characterized by higher uncertainty as 15% errors in the bioreactor and harvest cell concentration resulted in 37.8% error. Metabolic fluxes were estimated for 12 experimental conditions, each of 10 day duration, during 120‐day perfusion cultivation and were used to determine error propagation from specific rates into metabolic fluxes. Errors of the greater metabolic fluxes (those related to glycolysis, lactate production, TCA cycle and oxidative phosphorylation) were similar in magnitude to those of the related greater specific rates (glucose, lactate, oxygen and CO2 rates) and were insensitive to errors of the lesser specific rates (amino acid catabolism and biosynthesis rates). Errors of the lesser metabolic fluxes (those related to amino acid metabolism), however, were extremely sensitive to errors of the greater specific rates to the extent that they were no longer representative of cellular metabolism and were much less affected by errors in the lesser specific rates. We show that the relationship between specific rate and metabolic flux error could be accurately described by normalized sensitivity coefficients, which were readily calculated once metabolic fluxes were estimated. Their ease of calculation, along with their ability to accurately describe the specific rate‐metabolic flux error relationship, makes them a necessary component of metabolic flux analysis. © 2009 American Institute of Chemical Engineers Biotechnol. Prog., 2009
Synergistic coordination of polyethylene glycol with ClpB/DnaKJE bichaperone for refolding of heat‐denatured malate dehydrogenase
Authors: Nian Rui , Kim Duck Sang , Tan Lihan , Kim Chan‐Wha , Choe Woo‐Seok
Published: June 2009

The use of polyethylene glycol (PEG) as a refolding additive to a refolding cocktail comprising the molecular bichaperone ClpB and DnaKJE significantly enhances chaperone‐mediated refolding of heat‐denatured malate dehydrogenase (MDH). The critical factor to affect the refolding yield is the time point of introducing PEG to the refolding cocktail. The refolding efficiency reached approximately 90% only when PEG was added at the beginning of refolding reaction. The synergistic coordination of an inexpensive refolding additive PEG with the ClpB/DnaKJE bichaperone system may provide an economical route to further enhance the efficacy of ClpB/DnaKJE refolding cocktail approach, facilitating its implementation in large‐scale refolding processes. © 2009 American Institute of Chemical Engineers Biotechnol. Prog., 2009
Emergent percutaneous coronary intervention for resuscitated victims of out‐of‐hospital cardiac arrest
Authors: Kern Karl B. , Rahman Ossama
Published: June 2009

Long‐term survival rates even after successful resuscitation from out‐of‐hospital cardiac arrest are dismal. Most of those initially resuscitated expired during their hospitalization. Recent reports have suggested that a more aggressive approach to postresuscitation care is the key to better outcome. Waiting for the evidence of neurological recovery before acting can result in missed opportunity to improve such recovery. Immediate induction of mild therapeutic hypothermia for all resuscitated victims who remain comatose offers the best hope for neurological recovery. Numerous reports suggest that early coronary angiography and PCI also improve outcome among those resuscitated from cardiac arrest whose postresuscitation ECG show evidence of ST elevation myocardial infarctions. Most promising is combining these two postresuscitation therapies, namely immediate induction of hypothermia and early coronary angiography and PCI. Combining these therapies has resulted in long‐term survival rates of 70% with more than 80% of all such survivors neurologically functional. Even those without ST elevation on their postresuscitation ECG can greatly benefit from timely induction of hypothermia and early angiography/PCI. © 2009 Wiley‐Liss, Inc.
Transhepatic closure of patent foramen ovale
Authors: Jolly Neeraj , Dhar Gaurav , Amin Zahid
Published: June 2009

Transhepatic right heart catheterization is an uncommon procedure for adult interventional cardiologists. We report its successful use for closure of a patent foramen ovale in an elderly patient without femoral vein access. Also described is a novel method of using a vascular plug to achieve hemostasis of the hepatic venous access site. © 2009 Wiley‐Liss, Inc.
Framework Breathing in the Vapour‐Phase Adsorption and Separation of Xylene Isomers with the Metal–Organic Framework MIL‐53
Authors: Finsy Vincent , Kirschhock Christine E. A. , Vedts Gill , Maes Michael , Alaerts Luc , De Vos Dirk E. , Baron Gino V. , Denayer Joeri F. M.
Published: June 2009

Vapour‐phase adsorption and separation of the C8 alkyl aromatic compounds p‐xylene, m‐xylene, o‐xylene, and ethylbenzene has been studied on the metal–organic framework MIL‐53. Adsorption and desorption isotherms of the pure components at 110 °C were determined using the gravimetric technique. The adsorption isotherms show two well‐defined steps and hysteresis, corresponding to the opening or breathing of the framework, as induced by the presence of the adsorbing molecules. In the first isotherm plateau, an adsorption capacity of about 18 wt % is observed. After the breathing phenomenon, the adsorption capacity increases to about 40 wt %. Breakthrough separation experiments with equimolar o‐xylene/ethylbenzene mixtures were performed at 110 °C with varying hydrocarbon pressures. The separation mechanism is related to the state of the pore structure, as dictated by framework breathing. At low pressure, below the “pore‐opening” pressure, MIL‐53 shows no preference for any isomer. At pressures high enough to induce pore opening, separation of the C8 alkyl aromatic isomers becomes possible and separation factors as high as 6.5 are observed. The separation at a high degree of pore filling in the open form is a result of differences in the packing modes of the C8 alkyl aromatic components in the pores of MIL‐53.
Synthesis of Amphiphilic [60]Fullerene [3:3]Hexakisadducts with Four Spherically Defined Addend Zones
Authors: Beuerle Florian , Hirsch Andreas
Published: June 2009

New [3:3]hexakisadducts 3, 6, and 7 have been synthesized by a stepwise addition of two tripodal malonate tethers to pristine [60]fullerene. For the first time, [3:3]hexakisadducts of two sets of asymmetrically substituted malonate addends could be prepared as single in/out isomers by following this synthetic protocol. Thereby, four spherically defined addend zones I–IV were created with various similar degrees of latitude on the fullerene sphere. Four amphiphilic [3:3]hexakisadducts 12, 14, 18, and 19 were prepared with different relative arrangements of both the hydrophilic and lipophilic moieties in the addend zones I/II and III/IV, respectively.
Selective Triplet‐State Formation during Charge Recombination in a Fullerene/Bodipy Molecular Dyad (Bodipy=Borondipyrromethene)
Authors: Ziessel Raymond , Allen Ben D. , Rewinska Dorota B. , Harriman Anthony
Published: June 2009

A conformationally restricted molecular dyad has been synthesized and subjected to detailed photophysical examination. The dyad comprises a borondipyrromethene (Bodipy) dye covalently linked to a buckminsterfullerene C60 residue, and is equipped with hexadecyne units at the boron centre in order to assist solubility. The linkage consists of a diphenyltolane, attached at the meso position of the Bodipy core and through an N‐methylpyrrolidine ring at the C60 surface. Triplet states localised on the two terminals are essentially isoenergetic. Cyclic voltammetry indicates that light‐induced electron transfer from Bodipy to C60 is thermodynamically favourable and could compete with intramolecular energy transfer in the same direction. The driving force for light‐induced electron abstraction from Bodipy by the singlet excited state of C60 depends critically on the solvent polarity. Thus, in non‐polar solvents, light‐induced electron transfer is thermodynamically uphill, but fast excitation energy transfer occurs from Bodipy to C60 and is followed by intersystem crossing and subsequent equilibration of the two triplet excited states. Moving to a polar solvent switches on light‐induced electron transfer. Now, in benzonitrile, the charge‐transfer state (CTS) is positioned slightly below the triplet levels, such that charge recombination restores the ground state. However, in CH2Cl2 or methyltetrahydrofuran, the CTS is slightly higher in energy than the triplet levels, and decays, in part, to form the triplet state localized on the C60 residue. This step is highly specific and does not result in direct formation of the triplet excited state localized on the Bodipy unit. Subsequent equilibration of the two triplets takes place on a relatively slow timescale.
New Blue‐Light‐Emitting Ultralong [Cd(L)(TeO3)] (L=polyamine) Organic–Inorganic Hybrid Nanofibre Bundles: Their Thermal Stability and Acidic Sensitivity
Authors: Yao Hong‐Bin , Li Xiao‐Bo , Yu Shu‐Hong
Published: June 2009

A new type of blue‐light‐emitting ultralong [Cd(L)(TeO3)] (L=ethylenediamine, diethylenetriamine) nanofibre bundle has been synthesised under reflux in a mixed solvent media. Inorganic Cd(TeO3) layers are assumed to exist in the structures and are connected by the organic amine molecules through the coordination between nitrogen atoms and cadmium ions. The composition and formulae of these hybrid materials, based on the proposed structures, have been identified through element analysis (EA), thermal gravity analysis (TGA) and energy dispersive spectra (EDS). The thermal stabilities and optical properties of these nanofibre bundles have been investigated. Thermal decomposition of [Cd(en)(TeO3)] (en=ethylenediamine) and [Cd(DETA)(TeO3)] (DETA=diethylenetriamine) at 450 °C allowed the formation of a mixture of CdTe and Cd(TeO3) phases, and a pure CdTe phase, respectively. In addition, this new kind of hybrid bundle, which demonstrates blue emission, was found to be sensitive to acids, and the emission intensity is strongly dependent on the acidity of the solutions, implying that these hybrid nanofibre bundles could be potentially applied as acid sensors.
Synthesis and Structure–Activity Correlation Studies of Secondary‐ and Tertiary‐Amine‐Based Glutathione Peroxidase Mimics
Authors: Bhabak Krishna P. , Mugesh Govindasamy
Published: June 2009

In this study, a series of secondary‐ and tertiary‐amino‐substituted diaryl diselenides were synthesized and studied for their glutathione peroxidase (GPx) like antioxidant activities with H2O2, cumene hydroperoxide, or tBuOOH as substrates and with PhSH or glutathione (GSH) as thiol cosubstrates. This study reveals that replacement of the tert‐amino groups in benzylamine‐based diselenides by sec‐amino moieties drastically enhances the catalytic activities in both the aromatic thiol (PhSH) and GSH assay systems. Particularly, the N‐propyl‐ and N‐isopropylamino‐substituted diselenides are 8–18 times more active than the corresponding N,N‐dipropyl‐ and N,N‐diisopropylamine‐based compounds in all three peroxide systems when GSH is used as the thiol cosubstrate. Although the catalytic mechanism of sec‐amino‐substituted diselenides is similar to that of the tert‐amine‐based compounds, differences in the stability and reactivity of some of the key intermediates account for the differences in the GPx‐like activities. It is observed that the sec‐amino groups are better than the tert‐amino moieties for generating the catalytically active selenols. This is due to the absence of any significant thiol‐exchange reactions in the selenenyl sulfides derived from sec‐amine‐based diselenides. Furthermore, the seleninic acids (RSeO2H) derived from the sec‐amine‐based compounds are more stable toward further reactions with peroxides than their tert‐amine‐based analogues.
Structural Adaptability of Zinc Binding Sites: Different Structures in Partially, Fully, and Heavy‐Metal Loaded States
Authors: Heinz Uwe , Hemmingsen Lars , Kiefer Martin , Adolph Hans‐Werner
Published: June 2009

The present study demonstrates that both the nature (ZnII, CdII or HgII) and supply of metal ions determine whether zinc fingers fold into the well‐known, fully loaded structures or alternatively populate a variety of structural states under substoichiometric conditions. Metal‐bridged species are observed by perturbed angular correlation (PAC), EXAFS, UV spectroscopy, and stopped‐flow kinetics. Transitions between structural states as adaptive reactions to changed metal‐ion supply might represent intelligent system changes in zinc homeostasis, trafficking and signalling, and reflect features of heavy‐metal toxicity at the molecular level. Because the zinc fingers exist in structural states that are different from the metal‐free and fully loaded species, the prevailing view on metal‐mediated molecular regulation in terms of “on and off control” might be oversimplified.
N‐Heteroacenes
Authors: Bunz Uwe H. F.
Published: June 2009

The synthesis and the property evaluation of several large N‐heteroacenes are discussed. Issues of stability and aromaticity are compared and investigated and a historical perspective of the field is given. Some of the larger heterocyclic materials that are evaluated in this concept article have been around for more than one hundred years, yet their chemistry and properties are not well known/understood.
Chiral separation of phospine‐containing α‐amino acid derivatives using two complementary cellulosic stationary phases in supercritical fluid chromatography
Authors: West Caroline , Bouet Alexis , Gillaizeau Isabelle , Coudert Gerard , Lafosse Michel , Lesellier Eric
Published: June 2009

Enantiomeric separations of six amino‐acid derivatives have been studied using packed‐column supercritical fluid chromatography with two polysaccharide‐based enantioselective stationary phases: cellulose tris(3,5‐dimethylphenylcarbamate) and cellulose tris(3‐chloro‐4‐methylphenylcarbamate) (Lux Cellulose‐1 and ‐2). The effect of analyte structure on retention and separation was studied. Varied mobile phase compositions were investigated: alcohol modifier percentage was increased from 3 to 40% but smaller amounts were most effective in separating these compounds. Besides, ethanol was preferred to methanol or isopropanol as it proved to be a good compromise to achieve sufficient resolution in a reasonable analysis time. Moreover, a carbon dioxide‐ethanol mixture allows performing analyses in safe and green conditions. The effect of temperature at constant mobile phase composition was explored between 10 and 40°C. In most cases, increasing the temperature improved the chiral separation, up to an optimum temperature. The results are discussed in line with the structure variation of the racemic derivatives analyzed and the two columns are compared. The two columns were shown to provide complementary selectivities for the investigated solutes: whereas Lux 1 provided separation for five of the six racemates, Lux 2 could resolve the last racemic mixture. Finally, optimized conditions of separation are defined. Chirality, 2010. © 2009 Wiley‐Liss, Inc.
Bayesian robust transformation and variable selection: A unified approach
Authors: Gottardo Raphael , Raftery Adrian
Published: June 2009

The authors consider the problem of simultaneous transformation and variable selection for linear regression. They propose a fully Bayesian solution to the problem, which allows averaging over all models considered including transformations of the response and predictors. The authors use the Box‐Cox family of transformations to transform the response and each predictor. To deal with the change of scale induced by the transformations, the authors propose to focus on new quantities rather than the estimated regression coefficients. These quantities, referred to as generalized regression coefficients, have a similar interpretation to the usual regression coefficients on the original scale of the data, but do not depend on the transformations. This allows probabilistic statements about the size of the effect associated with each variable, on the original scale of the data. In addition to variable and transformation selection, there is also uncertainty involved in the identification of outliers in regression. Thus, the authors also propose a more robust model to account for such outliers based on at‐distribution with unknown degrees of freedom. Parameter estimation is carried out using an efficient Markov chain Monte Carlo algorithm, which permits moves around the space of all possible models. Using three real data sets and a simulated study, the authors show that there is considerable uncertainty about variable selection, choice of transformation, and outlier identification, and that there is advantage in dealing with all three simultaneously. The Canadian Journal of Statistics 37: 361–380; 2009 © 2009 Statistical Society of Canada
Pathway sensitivity analysis for detecting pro‐proliferation activities of oncogenes and tumor suppressors of epidermal growth factor receptor‐extracellular signal‐regulated protein kinase pathway at altered protein levels
Authors: Li Hu , Ung Choong Yong , Ma Xiao Hua , Liu Xiang Hui , Li Bao Wen , Low Boon Chuan , Chen Yu Zong
Published: June 2009

BACKGROUND:

Mathematic models and sensitivity analyses of biologic pathways have been used for exploring the dynamics and for detecting the key components of signaling pathways.

METHODS:

The authors previously developed a mathematic model of the epidermal growth factor receptor‐extracellular signal‐regulated protein kinase (EGFR‐ERK) pathway using ordinary differential equations from existing EGFR‐ERK pathway models. By using prolonged ERK activation as an indicator that may lead to cell proliferation under certain circumstances, in the current study, a pathway sensitivity analysis was performed to test its capability of detecting pro‐proliferative activities through altered protein levels to examine the effects on ERK activation.

RESULTS:

The analysis revealed that 12 of 20 oncoproteins and 4 of 5 tumor suppressors were detected, consistent with reported experimental works. Because pathway dynamics depend on many factors, some of which were not included in the current models, failure to detect all known oncogenes and tumor suppressors can be because of the failure to include relevant crosstalk to other pathway components.

CONCLUSIONS:

Overall, the current results indicated that pathway sensitivity analysis is a useful approach for detecting and distinguishing pro‐proliferation activities of oncoproteins and suppressed proliferative activities of tumor suppressors at altered protein levels at least in the EGFR‐ERK model. Cancer 2009. © 2009 American Cancer Society.
Yes‐associated protein is an independent prognostic marker in hepatocellular carcinoma
Authors: Xu Michelle Z. , Yao Tzy‐Jyun , Lee Nikki P. Y. , Ng Irene O. L. , Chan Yuk‐Tat , Zender Lars , Lowe Scott W. , Poon Ronnie T. P. , Luk John M.
Published: June 2009

BACKGROUND:

Yes‐associated protein (YAP), a downstream target of the Hippo signaling pathway, was recently linked to hepatocarcinogenesis in a mouse hepatocellular carcinoma (HCC) model. The objective of the current study was to investigate the clinical significance of YAP in HCC and its prognostic values in predicting survival and tumor recurrence.

METHODS:

The authors collected 177 pairs of tumor and adjacent nontumor tissue from HCC patients with definitive clinicopathologic and follow‐up data. YAP expression was determined by immunohistochemistry, Western blot analysis, and quantitative polymerase chain reaction. Association of YAP with each clinicopathologic feature was analyzed by Pearson chi‐square test, and HCC‐specific disease‐free survival and overall survival by Kaplan‐Meier curves and log‐rank test. Multivariate Cox regression analyses of YAP in HCC were also performed.

RESULTS:

YAP was expressed in the majority of HCC cases (approximately 62%) and mainly accumulated in the tumor nucleus. Overexpression of YAP in HCC was significantly associated with poorer tumor differentiation (Edmonson grade; P = .021) and high serum α‐fetoprotein (AFP) level (P < .001). Kaplan‐Meier and Cox regression data indicated that YAP was an independent predictor for HCC‐specific disease‐free survival (hazards ratio [HR], 1.653; 95% confidence interval [95% CI], 1.081‐2.528 [P = .02]) and overall survival (HR, 2.148; 95% CI, 1.255‐3.677 [P = .005]).

CONCLUSIONS:

YAP is an independent prognostic marker for overall survival and disease‐free survival times of HCC patients and clinicopathologically associated with tumor differentiation and serum AFP level. It is a potential therapeutic target for this aggressive malignancy. Cancer 2009. © 2009 American Cancer Society.
Cancer treatment adherence among low‐income women with breast or gynecologic cancer
Authors: Ell Kathleen , Vourlekis Betsy , Xie Bin , Nedjat‐Haiem Frances R. , Lee Pey‐Jiuan , Muderspach Laila , Russell Christy , Palinkas Lawrence A.
Published: June 2009

BACKGROUND:

The authors implemented a controlled, randomized trial that compared 2 interventions: the provision of written resource navigation information (enhanced usual care [EUC]) versus written information plus patient navigation (TPN) aimed at improving adjuvant treatment adherence and follow‐up among 487 low‐income, predominantly Hispanic women with breast cancer or gynecologic cancer.

METHODS:

Women were randomized to receive either TPN or EUC; and chemotherapy, radiation therapy, hormone therapy, and follow‐up were assessed over 12 months. Patients with breast cancer were analyzed separately from patients with gynecologic cancer.

RESULTS:

Overall adherence rates ranged from 87% to 94%, and there were no significant differences between the TPN group and the EUC group. Among women with breast cancer, 90% of the EUC group and 88% of the TPN group completed chemotherapy (14% of the EUC group and 26% of the TPN group delayed the completion of chemotherapy), 2% of the EUC group and 4% of the TPN group failed to complete chemotherapy, and 8% of the EUC group and 7% of the TPN group refused chemotherapy. Radiation treatment adherence was similar between the groups: Ninety percent of patients completed radiation (40% of the EUC group and 42% of the TPN group delayed the completion of radiation); in both groups, 2% failed to complete radiation, and 8% refused radiation. Among gynecologic patients, 87% of the EUC group and 94% of the TPN group completed chemotherapy (41% of the EUC group and 31% of the TPN group completed it with delays), 7% of the EUC group and 6% of the TPN group failed to complete chemotherapy, 6% of the EUC refused chemotherapy, 87% of the EUC group and 84% of the TPN group completed radiation (51% of the EUC group and 42% of the TPN with delays), 5% of the EUC group and 8% of the TPN group failed to complete radiation, and 8% of the EUC group and 5% of the TPN group refused radiation.

CONCLUSIONS:

Treatment adherence across randomized groups was notably higher than reported in previous studies, suggesting that active telephone patient navigation or written resource informational materials may facilitate adherence among low‐income, predominantly Hispanic women. Adherence also may have be facilitated by federal‐state breast and cervical cancer treatment funding. Cancer 2009. © 2009 American Cancer Society.
Interinstitutional consultation in fine‐needle aspiration cytopathology
Authors: Bomeisl Philip E. , Alam Shadia , Wakely Paul E.
Published: June 2009

BACKGROUND:

The importance of interinstitutional consultation (IC) has been documented across a variety of surgical pathology organ systems. However, to the authors' knowledge, few studies exist regarding this practice within cytopathology and specifically within fine‐needle aspiration cytology (FNAC).

METHODS:

All FNAC cases between September 2002 and January 2007 were reviewed. Original diagnoses and second opinion diagnoses (SODs) were categorized as either no diagnostic disagreement, or minor diagnostic disagreement, or major diagnostic disagreement, and the latter was defined as either a 2‐step deviation on a scale of “unsatisfactory, benign, atypical, suspicious, and malignant” or a change in treatment and/or prognosis. Outcome was determined by a review of the electronic medical record.

RESULTS:

Among 742 FNAC cases from outside laboratories, there were minor disagreements in 132 cases (17.8%) and major disagreements in 69 cases (9.3%) compared with the SODs from the authors' laboratory. Follow‐up was available for 60 of 69 major discrepancies. The SOD was supported on follow‐up in 65% of major discrepancies, and the initial diagnosis was supported better in 33% of major discrepancies. In 55% of cases in which the original institution diagnosis was supported better, either no case slides were received for examination or the slides contained material that was considered nondiagnostic by the authors. An SOD prompted a change in clinical management in 32 of 742 patients (4.3%). Aspirates that were most prone to change in management or therapy were from the thyroid (13 cases), neck (soft tissue and lymph nodes; 9 cases), salivary gland (2 cases), and liver (2 cases). Of 60 major diagnostic disagreements, board‐certified cytopathologists rendered an SOD in 44 cases, and 75% of the diagnoses were supported better by follow‐up, whereas pathologists who were not board certified in cytopathology had only 38% of SODs supported.

CONCLUSIONS:

Of 742 FNAC cases, 9.3% had major diagnostic disagreements; and, in 4.3%, patient management and therapy were altered. These results were similar to studies in surgical pathology emphasizing the importance of IC in FNAC. The authors concluded that FNAC IC benefits patient care. Cancer (Cancer Cytopathol) 2009. © 2009 American Cancer Society.
Acid‐Catalyzed Conversion of Sugars and Furfurals in an Ionic‐Liquid Phase
Authors: Sievers Carsten , Musin Ildar , Marzialetti Teresita , Valenzuela Olarte Mariefel B. , Agrawal Pradeep K. , Jones Christopher W.
Published: June 2009

The reactivity of monosaccharides, furfural, and 5‐hydroxymethyl‐2‐furfural (HMF) in the presence of a Brønsted acid (added as H2SO4) in the ionic liquid 1‐butyl‐3‐methylimidazolium chloride (BMImCl) is investigated at 120 °C. Fructose is converted much faster than mannose, glucose, and xylose and yields HMF with high selectivity, even in the absence of acid. Conversion of mannose, glucose, and xylose involves more complex reaction networks. Only small amounts of furfural and HMF are converted in the absence of other reactants but both compounds are consumed when monosaccharides and their degradation products are present. Acid‐catalyzed degradation reactions also lead to the formation of solid residues (humins).