bluuebunny/crossref_metadata_2025 huggingface dataset:
Corrosion studies of polyaniline/coconut oil poly(esteramide urethane) coatings
Authors: Ahmad Sharif , Ashraf S. M. , Riaz Ufana
Published: June 2005

Advancements in the area of conducting polymers have been towards their application as effective corrosion protective coatings to replace the use of heavy metals as additives in the coatings industries, which are now considered to be an environmental as well as health hazard. With the aim to utilize a sustainable resource based polymer for the development of an anti‐corrosive conducting coating material, coconut oil based conducting blend coatings of polyaniline and poly(esteramide urethane) were prepared by loading different ratios (2, 4 and 8 wt%) of polyaniline in poly(esteramide urethane). Then their physico‐chemical, thermal, morphological, conductivity and anti‐corrosive coating characteristics were investigated. The effect of a 2 year environmental aging process on the coated samples was analyzed by thermal methods as well as by corrosion studies. Results showed that the corrosion protective performance of the blend coatings was far superior than that of plane poly(esteramide urethane). These coatings showed enhanced corrosion protection in acid as well as alkaline environments upto 360 and 192 hr respectively. Conductivity of the blends was found to be in the range 2.5 × 10−5–5.7 × 10−4 S/cm−1. An increase in the thermal stability of the blend coatings and a decrease in their conductivity was noticed in the aged samples which was attributed to the crosslinking effect. The corrosion protective performance of the coatings remained almost unaffected even after 2 years of aging. Copyright © 2005 John Wiley & Sons, Ltd.
Novel high performance RTM bismaleimide resin with low cure temperature for advanced composites
Authors: Gu Aijuan
Published: June 2005

A novel performance matrix, coded as LCRTM, with low cure and post‐cure temperature (≤ 200°C) for fabricating advanced polymer composites via resin transfer molding (RTM), was successfully developed, made up of 4,4′‐bismaleimidodiphenylmethane (BDM) and N‐allyl diaminodiphenylether (ADDE). Investigations show that the stoichiometry of BDM and ADDE has great effect on the processing and performance parameters of the resultant resins. In the case of the optimum formulation (the mole ratio of BDM and ADDE is 1:0.55), the injection temperature range is between 70–82°C, and the pot life at 80°C is 300 min, moreover, the cured resin has desirable thermal and mechanical properties after being cured at 200°C for 6 hr, reflecting a great potential as high performance matrices for fabricating advanced composites via the RTM technique. Copyright © 2005 John Wiley & Sons, Ltd.
Poly(L‐histidine) with several aminoethyl groups for a new pH‐sensitive DNA carrier
Authors: Asayama Shoichiro , Sekine Takashi , Hamaya Ai , Kawakami Hiroyoshi , Nagaoka Shoji
Published: June 2005

In this study, poly(L‐histidine) with several aminoethyl groups, i.e. aminated poly(L‐histidine), is reported to be able to make complexes with DNA and to transfect cells in vitro in the presence of serum. The present study was performed to determine whether the pH of the medium had an influence on the complex formation with DNA, on the cell membrane fusion activity and on the transfection efficiency. Agarose gel retardation assays proved that the polyion complex formation of the aminated poly(L‐histidine) with DNA was affected by pH of the medium, owing to the basicity (protonation–deprotonation) of the imidazole groups with a pKa value around 6.0. Hemolysis assay showed that the resulting DNA complex enhanced membrane disruptive ability at endosomal pH. The aminated poly(L‐histidine) gene carrier demonstrated significant transfection efficacy which was decreased by the inclusion of chloroquine as an endosomolytic agent. These results suggest that the aminated poly(L‐histidine) promises to be a new pH‐sensitive DNA carrier for endosomal escape. Copyright © 2005 John Wiley & Sons, Ltd.
Self‐ and hetero‐association of sterically hindered tertiary alcohols
Authors: Lomas John S.
Published: June 2005

Self‐association constants for 2,2,4,4‐tetramethyl‐3‐alkylpentan‐3‐ols are so small as to be negligible in comparison with hetero‐association constants for the same alcohols with a moderately strong base. Equilibrium constants were determined by the NMR titration method for the hydrogen bonding association of this and two other series of sterically hindered alcohols with pyridine, in benzene as solvent. Steric effects are small even when the 3‐alkyl substituent is very bulky. The acidity of the OH hydrogen in 2,2,4,4‐tetramethyl‐3‐phenylpentan‐3‐ols increases slightly with the electron‐withdrawing ability of the para substituent (Hammett reaction constant, 0.3). The syn rotamer of a 2‐methyl derivative, where the methyl and OH groups are close, has a lower association constant than the anti rotamer. In the case of 2,2,4,4‐tetramethyl‐3‐(2‐thienyl)pentan‐3‐ols a second approach, based on the variation of the syn/anti ratio with the pyridine concentration, gives results concordant with those of the NMR method. The association constants predict accurately syn/anti ratios and syn OH proton chemical shifts in neat pyridine. The unusually large temperature coefficients of OH proton shifts in pyridine are due in part to the variation of the association constant. Copyright © 2005 John Wiley & Sons, Ltd.
Controlled/living polymerization of methacrylamide in aqueous media via the RAFT process
Authors: Vasilieva Yulia A. , Scales Charles W. , Thomas David B. , Ezell Ryan G. , Lowe Andrew B. , Ayres Neil , McCormick Charles L.
Published: June 2005

The polymerization of methacrylamide (MAM) was performed in aqueous media via reversible addition fragmentation chain transfer (RAFT) polymerization with the dithiobenzoate chain‐transfer agent (CTA) 4‐cyanopentanoic acid dithiobenzoate (CTP) and 4,4′‐azobis(4‐cyanopentanoic acid) (V‐501) as initiator. The polymerization in unbuffered water at 70 °C with a CTP/V‐501 ratio of 1.5 was controlled for the first 3 h, after which the molecular weight distribution broadened and a substantial deviation of the experimental from the theoretical molecular weight occurred, presumably because of a loss of CTA functionality at longer polymerization times. Conducting the polymerization in an acidic buffer afforded a well‐defined homopolymer (Mn = 23,800 g/mol, Mw/Mn = 1.08). To demonstrate the controlled/living nature of the system, a block copolymer of MAM and acrylamide was successfully prepared (Mn = 33,800 g/mol, Mw/Mn = 1.25) from a polymethacrylamide macro‐CTA. © 2005 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 43: 3141–3152, 2005
Synthesis and characterization of novel fluoride‐releasing monomers. II. Dimethacrylates containing bis(aminodiacetic acid) and their ternary zirconium fluoride complexes
Authors: Xu Xiaoming , Ding Xingzhe , Ling Long , Burgess John O.
Published: June 2005

Novel dimethacrylate monomers containing bis(aminodiacetic acid) chelating ligands with or without additional hydroxyl groups were synthesized, starting from 2,2‐bis(4‐hydroxy‐3‐methylphenyl)propane. The structures of the monomers were characterized by electrospray mass spectrometry (ESMS), 1H NMR, and 13C NMR. The structures and relative stability of fluoride‐releasing monomers containing one or more ternary zirconium fluoride complex moieties were studied by ESMS. The most stable ternary zirconium fluoride complex was in the form of [LZrF]−, where H4L is the monomer containing bis(aminodiacetic acid) without additional hydroxyl groups. The synthesized monomer was photopolymerized with camphorquinone and 1‐phenyl‐1,2‐propane‐dione as initiators and N,N‐dimethylaminoethyl methacrylate as the accelerator. The fluoride release, fluoride recharge, compressive strength, and flexure strength were tested on the experimental dental composite containing 13.7 wt % synthesized monomer and three commercial flowable dental composites. The results showed that the experimental composite has significantly higher fluoride release and recharge capabilities than the commercial flowable composites. The compressive strength was comparable to that of the commercial materials. The water sorption and solubility met the requirement of the ISO Specification 4049. © 2005 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 43: 3153–3166, 2005
Synthesis and characterization of poly(ethylene glycol) polymers functionalized by terminal tributyltin carboxylate moieties
Authors: Angiolini Luigi , Caretti Daniele , Mazzocchetti Laura , Salatelli Elisabetta , Willem Rudolph , Biesemans Monique
Published: June 2005

Novel polymeric derivatives of various average molecular weights bearing tributyltin carboxylate moieties as terminal groups have been prepared by esterification with bis(tributyltin) oxide of the corresponding poly(ethylene glycol)s functionalized with dimethylenecarboxylic end groups. Low‐molecular‐weight compounds have also been synthesized, with the aim of investigating the influence of the polymeric chain on tin properties. As investigated by Sn NMR and Fourier transform infrared, the metal center appears to be completely tetracoordinated in chloroform solution at room temperature, whereas at low temperature, the tin atom undergoes a fast exchange between intramolecular pentacoordination with the ethereal oxygen atoms and the unassociated form. In the solid state, even at room temperature, all the polymeric products exhibit both tetracoordination and pentacoordination at tin, the latter achieved by interaction with both ethereal and carbonyl oxygens. The thermal behavior of the series of compounds indicates the presence of crystalline domains in the material, which can be ascribed either to intermolecular interactions at tin, giving rise to organometal aggregates, or to the formation of an ordered phase induced by the presence of the macromolecular chain, depending on the more or less elevated relative concentration of the organotin moieties in the sample. These findings are also confirmed by the X‐ray diffractions patterns of the investigated products. © 2005 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 43: 3091–3104, 2005
Development of an efficient route to hyperbranched poly(arylene ether sulfone)s
Authors: Himmelberg Patrick , Fossum Eric
Published: June 2005

A two‐step route to an AB2 monomer that underwent polymerization via nucleophilic aromatic substitution to afford hyperbranched poly(arylene ether sulfone)s (HB PAES) was developed. The synthesis of 3,5‐difluoro‐4′‐hydroxydiphenyl sulfone (4) was accomplished by the reaction of 3,5‐difluorophenylmagnesium bromide with 4‐methoxyphenylsulfonyl chloride, followed by deprotection of the phenol group with HBr in acetic acid. The polymerization of 4 in the presence of 3,4,5‐trifluorophenylsulfonyl benzene or tris(3,4,5‐trifluorophenyl)phosphine oxide as a core molecule afforded HB PAES with number‐average molecular weights ranging from 3400 to 8400 Da and polydispersity index values ranging from 1.5 to 4.8. The presence of cyclic oligomeric species, formed by an intramolecular cyclization process, was a contributing factor to the relatively low molecular weights. The degree of branching (DB) of the HB PAES samples was estimated by a comparison of the 19F NMR spectra of the polymer samples with those of a series of model compounds, and DB values ranging from 0.51 to 0.70 were determined. The glass‐transition temperatures for the HB PAES samples were in the range of 205–222 °C, as determined by differential scanning calorimetry. © 2005 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 43:3178–3187, 2005
High resolution electron microscopy of ordered polymers and organic molecular crystals: Recent developments and future possibilities
Authors: Martin David C. , Chen Jihua , Yang Junyan , Drummy Lawrence F. , Kübel Christian
Published: June 2005

High Resolution Electron Microscopy (HREM) has made it possible to directly image the detailed organization of a variety of polymers and organic molecular crystals. For organic materials it is imperative to use low dose techniques that minimize the structural reorganizations that inevitably occur during electron beam irradiation. This article reviews recent developments in low dose HREM from our own laboratory and elsewhere. The developments in closely related microstructural characterization techniques are also reviewed. In the future, the ability to correct the spherical aberration of the objective lens, the use of low voltages to increase contrast, and the use of time‐resolved techniques are expected to open new avenues for the ultrastructural investigations of organic materials. New sample preparation techniques, such as the ability to make thin samples by focused ion beam (FIBs), to cut samples with an oscillating diamond knife, and to more conveniently prepare cryogenically solidified specimens, are also expected to be of increasing importance. © 2005 Wiley Periodicals, Inc. J Polym Sci Part B: Polym Phys 43: 1749–1778, 2005
Free volume and water vapor transport properties of temperature‐sensitive polyurethanes
Authors: Ding X. M. , Hu J. L. , Tao X. M. , Wang Z. F. , Wang B.
Published: June 2005

Segmented polyurethanes (PU) with crystalline soft segments were prepared with different crystalline polyols as soft segments. Morphology and microstructure of the PUs were investigated using Differential Scanning Calorimetry (DSC), Wide‐angle X‐ray Diffraction (WAXD), and Positron Annihilation Lifetime Spectra (PALS). Water vapor transport properties of the PU membranes were measured in the temperature range of crystal melting of their soft segments. Dependence of free volume of the PUs on temperature and the relationship between the free volume and water vapor permeability of the PU membranes were investigated. The results show that the mean free volume size and fractional free volume increase more rapidly in the temperature range of crystal melting than in other temperature intervals. In the specified temperature range, water vapor permeability of the polyester based PU membranes increases significantly, caused by the steep increase in free volume, due to crystal melting of the soft segments. Water vapor permeability of the polyester based PUs exhibits approximately direct correlation with the fractional free volume within the temperature range of crystal melting. © 2005 Wiley Periodicals, Inc. J Polym Sci Part B: Polym Phys 43: 1865–1872, 2005
Unique rheological behavior of rubber based nanocomposites
Authors: Sadhu Susmita , Bhowmick Anil K.
Published: June 2005

Montmorillonite clay (N) based nanocomposites were prepared using three different grades of acrylonitrile butadiene rubber (NBR) (19%, 34%, and 50% acrylonitrile contents), styrene butadiene rubber (SBR), and polybutadiene rubber (BR). Rheological study was carried out on these nanocomposites at three different temperatures (110 °C, 120 °C, and 130 °C) over a range of shear rates for comparison. The results showed that the shear viscosity decreased with increasing shear rate and incorporation of the unmodified (N) and the modified (OC) fillers up to a certain loading, when the results were compared with the gum rubber. This effect became more prominent with increasing polarity of the rubber. The die swell, on the other hand, decreased with loading of N and OC. With increasing filler volume fraction, the die swell further decreased. Decrease of viscosity with concomitant decrease of die swell is unique in such systems. Consecutive runs of the same sample over different shear rates increased the viscosity. The results were explained with the help of X‐Ray Diffraction (XRD) data and Transmission Electron Microscopy (TEM).© 2005 Wiley Periodicals, Inc. J Polym Sci Part B: Polym Phys 43: 1854–1864, 2005
Direct Si oxidation with fluorine incorporation using an argon excimer VUV source
Authors: Yu J. J. , Boyd I. W.
Published: June 2005

Direct Si oxidation using an Ar excimer VUV source without substrate heating has led to the rapid growth of oxide layers, with a film thickness of 8 nm being obtained for only 10 min VUV irradiation. With fluorine incorporation, the film thickness was further increased to 21 nm. The 1073 cm–1 absorption band in the infrared spectra for the Si–O stretching vibration was shifted to a higher wavenumber up to 1096 cm–1 while its full width at half maximum (FWHM) was reduced from 64 to 54 cm–1. The resulting SiOF films were OH‐free. The rapid Si oxidation could be caused by the highly reactive O (1S) generated by VUV photons, the availability of more Si dangling bonds produced from the replacement of Si in the Si–Si bond by F, and more VUV‐induced O3 formation at low substrate temperatures. Fluorine incorporated into the Si–O network was directly provided by the VUV dissociated PTFE materials in the reaction chamber. The F contents in the SiOF films could be controlled by varying the VUV source parameters such as the excimer gas pressure. (© 2005 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)
Transport in high mobility amorphous wide band gap indium zinc oxide films
Authors: Martins R. , Barquinha P. , Pimentel A. , Pereira L. , Fortunato E.
Published: June 2005

This paper discusses the electron transport in the n‐type amorphous indium–zinc–oxygen system produced at room temperature by rf magnetron sputtering, under different oxygen partial pressures. The data show that the transport is not band tail limited, as it happens in conventional disordered semiconductors, but highly dependent on its ionicity, which explains the very high mobilities (≥60 cm2 V–1 s–1) achieved. The room temperature dependence of the Hall mobility on the carrier concentration presents a reverse behaviour than the one observed in conventional crystalline/polycrystalline semi‐conductors, explained mainly by the presence of charged structural defects in excess of 4 × 1010 cm–2 that scatter the electrons that pass through them. (© 2005 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)
Recurrence relations for matrix elements of few‐body correlated wave functions
Authors: Harris Frank E.
Published: June 2005

This article considers the matrix elements arising from the use of wave functions containing exponentials in all the interparticle distances. Special cases (with some vanishing parameters) correspond to the use of the Hylleraas basis. For the three‐body (sometimes called two‐electron) correlated wave function, we present new recurrence relations that complement the formula of Sack, Roothaan, and Kolos. One of these is a sum rule that could also be used for downward recursion; the other is suitable for recursion in the usual (upward) recursive process. Formulas connecting matrix elements in the four‐body (three‐electron) problem are also derived; their use confirms the recurrence relations recently published by Pachucki, Puchalski, and Remiddi for the Hylleraas basis and provides a new sum rule for matrix elements in the general correlated exponential basis. © 2005 Wiley Periodicals, Inc. Int J Quantum Chem, 2005
Ordering the complements of trees by the number of maximum matchings
Authors: Yan Weigen , Yeh Yeong‐Nan , Zhang Fuji
Published: June 2005

A “perfect matching” of a graph G with n vertices is a set of ⌊n/2⌋ independent edges of G. In the present study, we succeeded in determining the trees whose complements have the extremal number of “perfect matchings” for two different group of trees. Some further problems are also posed. © 2005 Wiley Periodicals, Inc. Int J Quantum Chem, 2005
Geometry and stability of fullerene cages: C24 to C70
Authors: Chang Y. F. , Zhang J. P. , Sun H. , Hong B. , An Z. , Wang R. S.
Published: June 2005

The electronic structures and geometries of all even carbon fullerenes were investigated theoretically using density functional theory (DFT) at the B3LYP/6‐31G* level. Based on geometries, energies, and aromaticities, the potential relationship between geometry factors and stability has been investigated systematically. The extra stability of C60 has been confirmed by the shorter average bond length, smaller angle strain, widest energy gap, larger binding energy, and dissociation energy. Furthermore, C32 and C50 are predicted to have higher aromaticity due to larger negative nucleus independent chemical shift (NICS) values, whereas C60 displays a weak aromaticity. © 2005 Wiley Periodicals, Inc. Int J Quantum Chem, 2005
Density functional theory study of the interaction between 3‐nitro‐1,2,4‐triazole‐5‐one and ammonia
Authors: Fang Guo‐Yong , Xu Li‐Na , Hu Xin‐Gen , Li Xin‐Hua
Published: June 2005

Two fully optimized geometries of 3‐nitro‐1,2,4‐triazol‐5‐one (NTO)–NH3 complexes have been obtained with the density function theory (DFT) method at the B3LYP/6‐311++G** level. The intermolecular interaction energy is calculated with zero point energy (ZPE) correction and basis set superposition error (BSSE) correction. The greatest corrected intermolecular interaction of the NTO–NH3 complexes is −37.58 kJ/mol. Electrons in complex systems transfer from NH3 to NTO. The strong hydrogen bonds contribute to the interaction energies dominantly. Natural bond orbital (NBO) analysis is performed to reveal the origin of the interaction. Based on vibrational analysis, the changes of thermodynamic properties from the monomer to complexes with the temperature ranging from 200 K to 800 K have been obtained using the statistical thermodynamic method. It is found that two NTO–NH3 complexes can be produced spontaneously from NTO and NH3 at normal temperature. © 2005 Wiley Periodicals, Inc. Int J Quantum Chem, 2005
High turbulence liquid chromatography online extraction and tandem mass spectrometry for the simultaneous determination of suberoylanilide hydroxamic acid and its two metabolites in human serum
Authors: Du Lihong , Musson Donald G. , Wang Amy Qiu
Published: June 2005

A reliable and sensitive method incorporating high turbulence liquid chromatography (HTLC) online extraction with tandem mass spectrometry (MS/MS), for simultaneous determination of suberoylanilide hydroxamic acid (SAHA) and its two metabolites, SAHA‐glucuronide (M1) and 4‐anilino‐4‐oxobutanoic acid (M2), in human serum, has been developed to support clinical studies. The HTLC technology significantly reduces the time required for sample clean‐up since sample extraction and analysis are performed online. Clinical samples, internal standards (IS) and buffer are transferred into 96‐well plates using a robotic liquid handling system. A 20 µL aliquot of prepared sample is directly injected into the HTLC/LC‐MS/MS system where the matrix is rapidly washed away to waste and the analytes are retained on the narrow‐bore extraction column (0.5 × 50 mm), using an aqueous mobile phase at 1.5 mL/min. Analytes are then eluted from the extraction column and transferred to the analytical column using a gradient mobile phase prior to detection by MS/MS. Interference with determination of SAHA from in‐source dissociation of M1 is eliminated by the chromatographic separation. The resolution of SAHA and M1 did not change for more than 1500 serum sample injections by applying an acid wash (15% acetic acid) on the extraction column. The linear calibration ranges for SAHA, M1, and M2 are 2–500, 5–2000, and 10–2000 ng/mL, respectively. Assay intraday validation was conducted using five calibration curves prepared in five lots of human control serum. The precision expressed as relative standard deviation (RSD) is less than 6.8% and accuracy is 94.6–102.9% of nominal values for all three analytes. Assay specificity, freeze/thaw stability, storage stability, and matrix effects were also assessed. Copyright © 2005 John Wiley & Sons, Ltd.
Fragmentations of isomeric sulfated monosaccharides using electrospray ion trap mass spectrometry
Authors: Minamisawa Toshikazu , Hirabayashi Jun
Published: June 2005

Electrospray ionization combined with ion trap mass spectrometry (ESI‐ITMS) is a powerful tool for structural analysis of complex carbohydrates. Although its application to sulfated glycans has been limited so far, it should provide critical information, such as sulfate positions, on their structures. In this work, MSn spectra of nine monosulfated monosaccharides, consisting of five hexoses and four N‐acetylhexosamines, were measured in negative ion mode to find basic fragmentation rules for sulfated sugars. Two pairs of positional isomers with respect to sulfation, i.e., Gal4S and Gal6S, and GalNAc4S and GalNAc6S, showed characteristic fragmentation patterns in MS3, and could be discriminated from one another by the appearance of particular diagnostic fragment ions that characterize individual isomers. It was also demonstrated that, even if a mixture of these positional isomers was analyzed, the proportion of each species could be estimated through analysis of the abundance ratios of the diagnostic ions. However, 3‐O‐sulfated saccharides (Glc3S and GlcNAc3S) gave a single abundant diagnostic ion in MS2 corresponding to the hydrogensulfate ion, [OSO3H]−, and this characteristic clearly differentiated them from their positional isomers. In contrast, 6‐O‐sulfated diastereomers consisting of two groups, Glc6S, Man6S, Gal6S, and GlcNAc6S, GalNAc6S, could not be discriminated by the types of fragment ions; however, the abundance ratios of particular fragment ions differed significantly between Glc(NAc)6S and Gal(NAc)6S. Since ESI‐ITMS yielded large quantities of useful information on structures of monosulfated hexoses and N‐acetylhexosamines in an extremely simple and reproducible manner, establishment of a comprehensive strategy based on ESI‐ITMSn appears to be a promising technique for structural elucidation of sulfated complex carbohydrates. Copyright © 2005 John Wiley & Sons, Ltd.
Analysis of the composition of immunoconjugates using size‐exclusion chromatography coupled to mass spectrometry
Authors: Lazar Alexandru C. , Wang Lintao , Blättler Walter A. , Amphlett Godfrey , Lambert John M. , Zhang Wei
Published: June 2005

Recombinant monoclonal antibody drug products play an increasingly important role in the treatment of various diseases. Antibodies are large, multi‐chain proteins and antibody preparations often contain several molecular variants, which renders them heterogeneous. The heterogeneity is further increased in immunoconjugates prepared by covalently linking several drug molecules per antibody molecule. As part of the product characterization, the molecular weights of the antibodies or their drug conjugates need to be measured. Electrospray ionization mass spectrometry (ESI‐MS) is well suited for the analysis of recombinant antibodies and immunoconjugates. Sample preparation is an important element of ESI‐MS analysis, in particular samples need to be freed of interfering charged species, such as salts and buffer components. In this paper, Amicon centrifugal filters, reversed‐phase high‐performance liquid chromatography (HPLC), and size‐exclusion HPLC were evaluated for sample desalting. Size‐exclusion HPLC, using aqueous acetonitrile as the mobile phase, directly coupled to ESI‐MS provided the best performance and was optimized for the study of immunoconjugates. The results showed that antibodies carrying covalently linked maytansinoid molecules generated charge envelope profiles that differ from those of the non‐conjugated antibody. For the determination of the distribution of the various conjugate species in an immunoconjugate sample prepared by randomly linking in the average 3.6 drug molecules per antibody molecule, the experimental conditions needed to be carefully selected to allow acquisition of the whole spectrum containing the charge envelopes of all species. Copyright © 2005 John Wiley & Sons, Ltd.
Can radical cations of the constituents of nucleic acids be formed in the gas phase using ternary transition metal complexes?
Authors: Wee Sheena , O'Hair Richard A. J. , McFadyen W. David
Published: June 2005

Electrospray ionization (ESI) tandem mass spectrometry (MS/MS) of ternary transition metal complexes of [M(L3)(N)]2+ (where M = copper(II) or platinum(II); L3 = diethylenetriamine (dien) or 2,2′:6′,2″‐terpyridine (tpy); N = the nucleobases: adenine, guanine, thymine and cytosine; the nucleosides: 2′deoxyadenosine, 2′deoxyguanosine, 2′deoxythymine, 2′deoxycytidine; the nucleotides: 2′deoxyadenosine 5′‐monophosphate, 2′deoxyguanosine 5′‐monophosphate, 2′deoxythymine 5′‐monophosphate, 2′deoxycytidine 5′‐monophosphate) was examined as a means of forming radical cations of the constituents of nucleic acids in the gas phase. In general, sufficient quantities of the ternary complexes [M(L3)(N)]2+ could be formed for MS/MS studies by subjecting methanolic solutions of mixtures of a metal salt [M(L3)X2] (where M = Cu(II) or Pt(II); L3 = dien or tpy; X = Cl or NO3) and N to ESI. The only exceptions were thymine and its derivatives, which failed to form sufficient abundances of [M(L3)(N)]2+ ions when: (a) M = Pt(II) and L3 = dien or tpy; (b) M = Cu(II) and L3 = dien. In some instances higher oligomeric complexes were formed; e.g., [Pt(tpy)(dG)n]2+ (n = 1–13). Each of the ternary complexes [M(L3)(N)]2+ was mass‐selected and then subjected to collision‐induced dissociation (CID) in a quadrupole ion trap. The types of fragmentation reactions observed for these complexes depend on the nature of all three components (metal, auxiliary ligand and nucleic acid constituent) and can be classified into: (i) a redox reaction which results in the formation of the radical cation of the nucleic acid constituent, N+.; (ii) loss of the nucleic acid constituent in its protonated form; and (iii) fragmentation of the nucleic acid constituent. Only the copper complexes yielded radical cations of the nucleic acid constituent, with [Cu(tpy)(N)]2+ being the preferred complex due to suppression, in this case, of the loss of the nucleobase in its protonated form. The yields of the radical cations of the nucleobases from the copper complexes follow the order of their ionization potentials (IPs): G (lowest IP) > A > C > T (highest IP). Sufficient yields of the radical cations of each of the nucleobases allowed their CID reactions (in MS3 experiments) to be compared to their even‐electron counterparts. Copyright © 2005 John Wiley & Sons, Ltd.
Analysis of bufadienolides in the Chinese drug ChanSu by high‐performance liquid chromatography with atmospheric pressure chemical ionization tandem mass spectrometry
Authors: Ye Min , Guo De‐an
Published: June 2005

The qualitative analysis of bufadienolides in the Chinese drug ChanSu was performed using high‐performance liquid chromatography with atmospheric pressure chemical ionization tandem mass spectrometry (APCI‐MS/MS). Bufadienolides are the major bioactive constituents of ChanSu, which is used to treat heart failure and cancer in traditional Chinese medicine. The APCI‐MS fragmentation behavior of bufadienolides was studied. For bufadienolides with only hydroxyl substituents, the fragmentation was characterized by successive eliminations of H2O and CO molecules, and the profile of MS/MS product ions was correlated with the number of hydroxyl groups. If a C‐16 acetoxyl group was present, the fragmentation of [M+H]+ ions was triggered by initial loss of 60 Da (HOAc). The elimination of CO was significant for bufadienolides with a 19‐formyl group, and the 19‐hydroxyl group could be characterized by the loss of 30 Da (HCHO). These fragmentation rules were applied to the identification of bufadienolides in a methanolic extract of ChanSu, which was separated on a C18 column with gradient elution. A total of 35 bufadienolides were identified, including four new constituents. The method established here facilitated the convenient and rapid quality control of ChanSu crude drug and its pharmaceutical preparations. Copyright © 2005 John Wiley & Sons, Ltd.
Analysis of organochlorines in harbor seal (Phoca vitulina) tissue samples from Alaska using gas chromatography/ion trap mass spectrometry by an isotopic dilution technique
Authors: Wang Dongli , Atkinson Shannon , Hoover‐Miller Anne , Li Qing X.
Published: June 2005

A gas chromatography/ion trap mass spectrometry (GC/ITMS) method was developed for the determination of organochlorine pesticides (OCPs), polychlorinated biphenyls (PCBs) and polychlorinated naphthalenes (PCNs) in harbor seal (Phoca vitulina) tissues. Tissue samples were homogenized, lyophilized and fortified with 13C‐PCBs 28, 123, 169 and 170, and then extracted with an accelerated solvent extractor with a mixture of hexane and methylene chloride (1:1, v/v). After lipid removal using a 40% H2SO4‐modified silica gel column, all organochlorines were collected in one fraction and further fractionated with an activated carbon/silica gel (1:20) column into a first fraction containing OCPs, non‐coplanar PCBs and 13C‐PCBs 28, 123 and 170, and a second containing PCNs, coplanar PCBs and 13C‐PCB 169. Prior to GC/MS/MS analysis, 13C‐PCB 169 was added into the first fraction as an injection standard and 13C‐PCB 170 into the second fraction to calibrate the recoveries of the fortified internal standards. This method can effectively eliminate matrix interferences, and has high selectivity and sensitivity. Recoveries averaged 45–86% for OCPs with relative standard deviations (RSDs) of 2–14%, 52–137% for PCBs with RSDs of 3–29% and 36–152% for PCNs with RSDs of 7–29% from lard and chicken heart samples, which were used as alternative matrices to harbor seal samples in recovery studies. The limits of detection for OCPs, PCBs and PCNs were 0.7–1.9, 1.5–8.9 and 0.5–10 pg/g dry weight, respectively. This method can be used to analyze OCPs, PCBs and PCNs in harbor seal blubber, liver and kidney samples. Copyright © 2005 John Wiley & Sons, Ltd.
Study of metal complexes of a tripodal hydroxypyridinone ligand by electrospray tandem mass spectrometry
Authors: Budimir Natali , Fournier Françoise , Bailly Théodorine , Burgada Ramon , Tabet Jean‐Claude
Published: June 2005

The tripodal ligand N,N,N‐tris[(1,hydroxy‐2‐pyridinon‐6‐yl)amide]propylamine was synthesized. It is composed of an anchor (nitrogen atom), a functional group (hydroxamate), and also a spacer of variable length defined by the number of methylene groups linking the anchor and the functional group. The characterization of this ligand in the presence of several divalent metal cations (FeII, MnII, CoII and CuII), performed by electrospray ionization mass spectrometry (ESI‐MS and ESI‐MS/MS), allowed elucidation of oxidation states and also of different fragmentation patterns. The importance of the spacer length was studied in the case of the iron binary complex by comparing this ligand with another with a shorter spacer. In this way the stabilizing conditions, in which hydrogen bonds are implicated, were clarified. Copyright © 2005 John Wiley & Sons, Ltd.
New conditions for matrix‐assisted laser desorption/ionization mass spectrometry of native bacterial R‐type lipopolysaccharides
Authors: Sturiale Luisa , Garozzo Domenico , Silipo Alba , Lanzetta Rosa , Parrilli Michelangelo , Molinaro Antonio
Published: June 2005

A new sample preparation method for matrix‐assisted laser desorption/ionization (MALDI) analysis of native rough‐type lipopolysaccharides (R‐type LPSs) is presented. In our MALDI mass spectra, besides the [MH]− ions, abundant ions originating from the cleavage between the 3‐deoxy‐D‐manno‐oct‐2‐ulosonic acid (Kdo) unit and the lipid A moiety are always present, giving important pieces of information about the structure of the molecules analyzed. Remarkably, in most cases, the comparison of the MALDI mass spectra of the intact R‐type LPS with the O‐deacylated one allowed us to obtain the structure of the lipid A moiety. Copyright © 2005 John Wiley & Sons, Ltd.
Mono‐ and diiodocyclophosphamide as possible internal standards for cyclophosphamide quantification: characterization by ion trap multi‐stage mass spectrometry and effects of iodine‐chlorine substitution on the fragmentation pattern
Authors: Castiglia L. , Miraglia N. , Pieri M. , Genovese G. , Simonelli A. , Basilicata P. , Sannolo N. , Acampora A.
Published: June 2005

Hospital personnel involved in antineoplastic drug preparation and administration to patients are exposed to large amounts of these drugs. Labour legislation indicates the necessity of planning monitoring strategies aimed at prevention and/or reduction of drug exposure. Monitoring strategies consist of quantitative determinations of indicators, present in environmental and biological matrices. Among the antineoplastic drugs widely used, cyclophosphamide (CP) has been identified as a suitable indicator of potential exposure to mixtures of antineoplastic drugs. Many literature methods for quantitative analysis of CP involve either liquid (LC) or gas chromatography (GC) with mass spectrometry (MS), both of which require use of a suitable internal standard. The present work focuses on the synthesis of mono‐ and diiodocyclophosphamide (CPI and CPI2) to be used as internal standard. These compounds were analyzed by GC/EI‐MS/MS and LC/ESI‐MSn using ion trap mass spectrometry. The product ion mass spectra are interpreted in terms of proposed structures of fragment ions. Iodine‐chlorine substitution resulted in a weakening of the carbon–halogen bond with a noteworthy influence on the ion fragmentation processes. The proposed suitability of CPI and CPI2 as internal standards was based on similarities to CP as regards ionization and fragmentation processes. The results obtained suggest that CPI could be used as internal standard for CP quantification by LC/ESI‐MS/MS, and CPI2 for GC/EI‐MS/MS analyses. Copyright © 2005 John Wiley & Sons, Ltd.
Characterisation via electrospray ionisation multistage mass spectrometry of three related series of nitrido technetium complexes containing phosphinothiolate and dithiocarbamate ligands
Authors: Tubaro Michela , Traldi Pietro , Bolzati Cristina , Tisato Francesco , Refosco Fiorenzo , Benini Elisa , Cavazza‐Ceccato Mario
Published: June 2005

Nine nitrido technetium compounds comprising bis‐substituted Tc(N)(PS)2 (1–4) (PS = bidentate phosphinothiolate ligands) and Tc(N)(dtc)2 (5, 6) derivatives (dtc = bidentate dithiocarbamate), and mixed‐ligand Tc(N)(PS)(dtc) (7–9) species, were subjected to electrospray ionisation mass spectrometry and MSn experiments. Bis‐substituted phosphinothiolato complexes 1–4 lead to the straightforward formation of dinuclear species reasonably originating from proton bound dimers. These dinuclear species do not show, under collisionally induced fragmentation processes, the formation of monomeric units but cleavages related to the ligand framework, thereby proving the high stability of the [TcH+Tc] bond. Bis‐dithiocarbamate compounds 5 and 6 show, instead, abundant [M+H]+, [M+Na]+ and [2M+Na]+ ions, and their collisionally induced fragmentations are highly favoured with cleavages related to the CN and CS bonds. During these processes, the coordination of a water molecule to [MH–L]+ product ions is observed, as proved by the collisionally induced H2O loss detected for this species. Mixed‐ligand compounds 7 and 8 show the protonated molecules and Na+‐cationised ions with fragmentation processes related to the dithiocarbamate moiety. This behaviour indicates that coordination of ether‐ and ester‐substituted dithiocarbamates to the [Tc  N] group is weaker than that of phosphinothiolates. Conversely, diethyldithiocarbamate inserted in mixed complex 9 enhances both CN and TcS bonds, and fragmentation processes suggest that metal‐phosphinothiolate and metal‐dithiocarbamate show comparable strength. Copyright © 2005 John Wiley & Sons, Ltd.
Negative‐ion electrospray ionization mass spectrometry of N‐benzyloxycarbonyl‐protected 1‐substituted and cyclic taurines
Authors: Xu Jiaxi , Ma Yuan , Xu Shu , Zhao Yufen
Published: June 2005

The negative‐ion mass spectrometric behavior of N‐benzyloxycarbonyl‐protected 1‐substituted and cyclic taurines has been investigated under electrospray ionization conditions. Their fragmentation pathways are proposed and supported by collisionally activated dissociation product‐ion spectrometry. The deprotonated substituted taurines preferentially eliminate a molecule of benzyl alcohol to yield isocyanato‐sulfonate ions, which further generate alkene‐2‐sulfonate ions by loss of isocyanic acid. The isocyanato‐sulfonate ions of 1‐substituted taurines could further generate aziridine‐2‐sulfonate ion via ring rearrangements by loss of CO plus benzyne and carbene moieties, respectively, while the isocyanato‐sulfonate ions of cyclic taurines could further give rise to cycloalkene anion radicals. An obvious substituent effect on the fragmentations of the title compounds was observed. Copyright © 2005 John Wiley & Sons, Ltd.
13C‐Isotope ratio mass spectrometry as a potential tool for the forensic analysis of white architectural paint: a preliminary study
Authors: Reidy L. J. , Meier‐Augenstein W. , Kalin R. M.
Published: June 2005

Paints have a dual role in society, to protect materials from environmental agents such as ultraviolet light, moisture and oxygen, and to make painted materials look more attractive. Variability in paint samples is often due to binder and pigment type within the sample. The most common resin used in decorative paints is drying oil alkyd resin, which incorporates soybean oil and vinyl acrylic based latexes. Traditional analytical methods used by forensic scientists may be able to say whether two paint samples are indistinguishable but cannot conclusively say that they both originate from the same source. To find out if isotopic composition can provide an added dimension of information, 28 different white architectural paints were analysed for 13C abundance using isotope ratio mass spectrometry. In addition, variations in application, drying time and thickness were also investigated to assess the discriminatory power of 13C data from white paints with an unknown history. Preliminary results indicate that this method could aid screening of paint samples. Copyright © 2005 John Wiley & Sons, Ltd.
The host environment drives HIV‐1 fitness
Authors: van Opijnen Tim , Berkhout Ben
Published: June 2005

Viral fitness is defined by the ability of an individual genotype to produce infectious progeny in a specific environment. For HIV the environment is never constant but rather fluctuates in time and space. For instance, environmental factors that determine viral fitness during transmission from host to host are different to the pressures from either cytotoxic T‐lymphocytes (CTLs) or antiviral drugs. Consequently, viral fitness is highly dependent on the environment and the accurate determination of this value therefore depends strongly on the chosen environmental setting. This review describes how the host environment imposes selective pressures on the virus that shape its genotype and fitness. The most important environments that the virus encounters throughout its life cycle and during natural infection are discussed. In order of appearance, CTLs are discussed, followed by neutralising antibodies and antiretroviral drug treatment. It then goes on to describe receptor molecules that mediate viral entry and intracellular restriction factors, which represent selective pressures that are present directly from the start of a natural infection. It concludes by discussing the complexity of viral fitness and how an accurate measure of viral fitness eventually may, for example, contribute to the improvement of antiretroviral therapy or help in the formulation of an optimal vaccination strategy. Copyright © 2005 John Wiley & Sons, Ltd.
Time course of localization for a repeatedly flashing stimulus presented at perisaccadic timing
Authors: Watanabe Junji , Maeda Taro , Tachi Susumu
Published: June 2005

When a light spot is flashed repeatedly during saccade, a dotted line called a phantom array (PA) is perceived. When light spots are placed on a vertical line and the flashing pattern is changed quickly during saccade, the flashing pattern is expanded to a spatial pattern by the effect of eye movement, and a two‐dimensional image is perceived. The authors have proposed a visual information presentation method based on this phenomenon. A crucial issue in information presentation by this method is the time relation between the perceived PA and the eye movement. Consequently, this study examines the time relation between the perception and the eye movement. The time course of perceived position for repeatedly flashing stimulus is investigated by presenting light spots in the vertical position. It is found that the locus of the perceived light spot starts to curve at the start of saccade in the direction opposite to the saccade, and returns to the vertical direction when the saccade ends. It differs from the locus of the light spot which is expected in accordance with cancellation theory. © 2005 Wiley Periodicals, Inc. Syst Comp Jpn, 36(9): 77–86, 2005; Published online in Wiley InterScience (www.interscience.wiley.com). DOI 10.1002/scj.10690
Chip size and performance evaluations of shared cache for on‐chip multiprocessor
Authors: Sasaki Takahiro , Inoue Tomohiro , Omori Nobuhiko , Hironaka Tetsuo , Mattausch Hans J. , Koide Tetsushi
Published: June 2005

Recent semiconductor technology has made on‐chip multiprocessors with several CPUs and cache memories on a single chip a realistic possibility. Generally, conventional multiprocessor systems with shared memory offer a simple programming model, but need a cache coherency mechanism that may become a system bottleneck. Furthermore, the same data may be cached on two or more caches, which prevents effective cache utilization. The multiport cache is one solution, but when using the conventional multiport memory architecture, the chip size of the multiport cache will increase in proportion to the square of the number of ports. On the other hand, with our proposed hierarchical multiport memory architecture, multiport memory can be implemented with a smaller chip size than by the conventional methods. This paper proposes the shared cache with a hierarchical multiport memory architecture that does not need a coherency mechanism. This paper also presents the results of performance evaluations and chip size estimations. © 2005 Wiley Periodicals, Inc. Syst Comp Jpn, 36(9): 1–13, 2005; Published online in Wiley InterScience (www.interscience.wiley.com). DOI 10.1002/scj.20244
The factorial structure of the GHQ‐12
Authors: Vanheule Stijn , Bogaerts Stefan
Published: June 2005

This paper studies the factorial structure of the 12‐item version of the General Health Questionnaire (GHQ‐12), Dutch translation, in a large Belgian sample (n = 9442) that is representative of the general population. Data was collected from the 2001 Belgian Health Interview Survey. In total, 11 factor‐structure models are tested by means of confirmatory factor analysis. Two models, a two‐factorial model without cross‐loadings and a three‐factorial model with cross‐loadings, prove to have acceptable model‐fit. Given parsimony and the uni‐dimensionality of the subscales, the authors prefer the two‐factorial model over the three‐factorial one. In a next step, it is examined whether a general, second‐order factor can be seen underlying both the two‐ and three‐factorial models. This, however, was only true for the three‐factorial model. Based on correlations with other scales (the revised Symptom Checklist 90, SCL‐90‐R; the MOS Social Support Survey, MOS‐SSS) and a variable on social contacts, the authors suggest that the ‘social dysfunction’ subscale be renamed ‘dysfunction’. Copyright © 2005 John Wiley & Sons, Ltd.
The development of social justice attitudes and actions: An overview of current understandings
Authors: Broido Ellen M. , Reason Robert D.
Published: June 2005

This chapter reviews the current theoretical understanding of the development of social justice attitudes and related concepts.
Encouraging the development of social justice attitudes and actions in heterosexual student
Authors: Evans Nancy J. , Broido Ellen M.
Published: June 2005

The authors discuss strategies for the development of heterosexual allies and actions that allies can take to support this social identity group.
Encouraging the development of disability allies
Authors: Evans Nancy J. , Assadi Jennifer L. , Herriott Todd K.
Published: June 2005

The authors advocate for a constructionist interpretation of disability, grounded in a social justice perspective, by discussing disability paradigms, factors that influence attitudes and attitude change regarding disability, and disability ally development and behaviors.