bluuebunny/crossref_metadata_2025 huggingface dataset:
Compatibilization of SBR/NBR blends using chemically modified styrene‐co‐butadiene rubber Part 2. Effect of compatibilizer loading
Authors: Ramesan M T , Alex Rosamma
Published: January 2005

The present work focuses on the compatibization of styrene‐co‐butadiene rubber (SBR)/acrylonitrile‐co‐butadiene rubber (NBR) blends with dichlorocarbene modified styrene‐co‐butadiene rubber (DCSBR) as a function of concentration of compatibilizer and composition of the blend. FTIR studies, differential scanning calorimetry and dynamic mechanical analysis reveal molecular level miscibility in the blends in the presence of compatibilizer. The formation of interfacial bonding is assessed by analysis of swelling behaviour, cure characteristics, stress–strain data and mechanical properties. These studies show that the compatibilizing action of DCSBR becomes more prominent as the proportion of NBR in the blend increases. The resistance of the vulcanizate towards thermal and oil ageing improved with compatibilization. The change in technological properties is correlated with the crosslink density of the blends assessed from swelling and stress–strain data.

© 2001 Society of Chemical Industry
Fracture behaviour of acrylonitrile–butadiene rubber/clay nanocomposite
Authors: Nah Changwoon , Ryu Hyune Jung , Han Sang Hyub , Rhee John M , Lee Myong‐Hoon
Published: January 2005

A new fracture behaviour is described for acrylonitrile–butadiene rubber/clay nanocomposite. The nanocomposite is prepared by melt mixing the organo‐treated montmorillonite into the rubber matrix, together with a peroxide curative, and crosslinked by conventional compression moulding for typical rubbers. A considerable enhancement in stiffness is observed without serious sacrifice in ultimate strength. A totally different tear morphology of a series of regularly‐spaced tear ridges parallel to the direction of tearing was observed instead of the typical ‘cross‐hatched morphology’ of conventional rubber composites.

© 2001 Society of Chemical Industry
Aeration of fishponds by photovoltaic power
Authors: Applebaum J. , Mozes D. , Steiner A. , Segal I. , Barak M. , Reuss M. , Roth P.
Published: January 2005

Fishponds in aquaculture farms are usually located in remote areas, far from grid supply lines. Aeration of ponds for growing aquatic animals (e.g., fish) is required to prevent mortality and to intensify production, especially when feeding is practical, and in warm regions. Aeration systems with photovoltaic power supply may be the appropriate technology from an ecological and economic point of view. In addition, photovoltaic power is very suitable for remote developing regions, owing to its simplicity and low maintenance. The purpose of the present study was to demonstrate an aeration system using a paddle wheel connected to a permanent magnet DC motor, and powered by a photovoltaic power supply. The study was carried out on the coastal area in the center of Israel. The aeration system operated satisfactorily for the demonstration period of more than two years. Copyright © 2001 John Wiley & Sons, Ltd.
Impact of light‐induced recombination centres on the current–voltage characteristic of czochralski silicon solar cells
Authors: Schmidt Jan , Cuevas Andrés , Rein Stefan , Glunz Stefan W.
Published: January 2005

We have investigated the effect of the light‐induced deep‐level recombination centre specific to boron‐doped, oxygen‐contaminated Czochralski (Cz) silicon on the current–voltage characteristic of Cz silicon solar cells by means of numerical simulation and experiment. The device simulation predicts the occurrence of a shoulder in the current–voltage curve after activating the characteristic recombination centre. The physical reason for the non‐ideal diode behaviour, characterised by a local ideality factor greater unity, is the strongly injection‐level‐dependent bulk lifetime produced by the deep‐level centre. The increased ideality factor causes a degradation in fill factor with the magnitude of degradation depending on the doping concentration of the Cz silicon base. In order to verify the theoretical predictions experimentally, we have performed measurements on high‐efficiency Cz silicon solar cells. Current–voltage curves recorded before and after light degradation clearly show the theoretically predicted change in shape and the reduction in fill factor. An excellent quantitative agreement between calculation and experiment is obtained for the subtracted current–voltage curves measured after and before illumination. Copyright © 2001 John Wiley & Sons, Ltd.
Textured monocrystalline thin‐film Si cells from the porous silicon (PSI) process
Authors: Brendel Rolf , Auer Richard , Artmann Hans
Published: January 2005

We have fabricated a textured monocrystalline Si solar cell with a thickness of 15·5 μm and a confirmed efficiency of 12·2% using porous silicon (PSI) for layer transfer. The PSI process avoids photolithography and high‐temperature oxidation. The cell has a surface that is textured with randomly positioned inverted pyramids for light trapping. The device does not yet fully exploit the light‐trapping capability of this film shape, owing to a small back‐surface reflectance. Copyright © 2001 John Wiley & Sons, Ltd.
Purification and proteomic analysis of outer membrane vesicles from a clinical isolate of Leptospira interrogans serovar Copenhageni
Authors: Nally Jarlath E. , Whitelegge Julian P. , Aguilera Rodrigo , Pereira Martha M. , Blanco David R. , Lovett Michael A.
Published: January 2005

The severe pulmonary form of leptospirosis (SPFL) is an especially serious and rapid disease process characterized by alveolar hemorrhage and acute respiratory failure. The outer membrane of Leptospira facilitates direct interactions with the environs and likely contains important constituents involved during infection, transmission, survival, and adaptation to environmental conditions, including putative vaccinogen and diagnostic candidates. Outer membrane vesicles (OMVs) were purified by incubation in low‐pH citrate buffer, treatment in a French press, and centrifugation over a continuous sucrose gradient. OMVs characterized by two‐dimensional gel electrophoresis (2‐DE) contained the previously described outer membrane proteins OmpL1, Qlp42, LipL32, LipL41, LipL36 and Loa22. In addition, unknown, hypothetical and putative outer membrane proteins were identified. High‐performance liquid chromatography (HPLC) coupled with mass spectrometry and fraction collection (LC‐MS+) measured the intact mass profile of the major outer membrane protein, LipL32, and the putative lipoprotein Qlp42. In contrast to a predicted molecularmass of 27 653.5 Da for LipL32 after cleavage of its signal peptide, intact mass proteomics measured the mass as ranging from 28 468 to 28 583 Da, consistent with lipidation of LipL32. In contrast to a predicted molecular mass of 39.8 kDa for Qlp42, the actual mass was measured as 24 811 and 26 461 Da consistent with a 30 kDa doublet observed on sodium dodecyl sulfate‐polyacrylamide gel electrophoresis (SDS‐PAGE) gels and processing of the N‐terminus of the mature protein. These studies indicate that purified OMVs are highly compatible with proteomics technologies including 2‐DE and intact mass proteomics using LC‐MS+ that facilitates definition of actual molecular masses of intact outer membrane proteins, and heterogeneity associated with them.∁
A proteomic approach to characterize protein shedding
Authors: Ahram Mamoun , Adkins Joshua N. , Auberry Deanna L. , Wunschel David S. , Springer David L.
Published: January 2005

Shedding (i.e. proteolysis of ectodomains of membrane proteins) plays an important pathophysiological role. In order to study the feasibility of identifying shed proteins, we analyzed serum‐free media of human mammary epithelial cells by mass spectrometry following induction of shedding by the phorbol ester, 4β‐phorbol 12‐myristate 13‐acetate (PMA). Different means of sample preparation, including biotinylation of cell surface proteins, isolation of glycosylated proteins, and preparation of crude protein fractions, were carried out to develop the optimal method of sample processing. The collected proteins were digested with trypsin and analyzed by reversed‐phase capillary liquid chromatography interfaced to an ion‐trap mass spectrometer. The resulting peptide spectra were interpreted using the program SEQUEST. Analyzing the sample containing the crude protein mixture without chemical modification or separation resulted in the greatest number of identifications, including putatively shed proteins. Overall, 45 membrane‐associated proteins were identified including 22 that contain at least one transmembrane domain and 23 that indirectly associate with the extracellular surface of the plasma membrane. Of the 22 transmembrane proteins, 18 were identified by extracellular peptides providing strong evidence they originate from regulated proteolysis or shedding processes. We combined results from the different experiments and used a peptide count method to estimate changes in protein abundance. Using this approach, we identified two proteins, syndecan‐4 and hepatoma‐derived growth factor, whose abundances increased in media of cells treated with PMA. We also detected proteins whose abundances decreased after PMA treatment such as 78 kDa glucose‐regulated protein and lactate dehydrogenase A. Further analysis using immunoblotting validated the abundance changes for syndecan‐4 and 78 kDa glucose‐regulated protein as a result of PMA treatment. These results demonstrate that tandem mass spectrometry can be used to identify shed proteins and to estimate changes in protein abundance.
PROTEOMICS Enters its 5th Year of Publication
Authors: Dunn Michael J.
Published: January 2005

No abstracts.
1,4‐Naphthoquinonediazide‐2‐carboxylic acid: a diazo compound with a long‐lived triplet excited state
Authors: Bucher Götz , Wandel Holger , Sander Wolfram
Published: January 2005

Laser flash photolysis (308 nm) of 1,4‐naphthoquinonediazide‐2‐carboxylic acid 1 in 2‐methyltetrahydrofuran (MTHF) leads to the detection of a long‐lived (5.3 μs) triplet excited state, whose triplet energy, obtained by measuring the phosphorescence spectrum of 1 in an Ar‐ matrix at 10 K, is ca 55 kcal mol−1 (1 kcal­= 4.184 KJ). The first triplet excited state of 1 is quenched efficiently by 1,3‐dienes and molecular oxygen. By calculating the spin density distribution it can be shown that 31 is not a typical naphthalene triplet, as it bears significant spin density at the diazo moiety. Copyright © 2001 John Wiley & Sons, Ltd.
The Grunwald–Winstein relationship in the solvolysis of crowded tertiary alkyl chlorides. Hindered hydration and hydrophobic effect
Authors: Takeuchi Ken'ichi , Takasuka Masaaki , Shiba Eiji , Tokunaga Hironobu , Endo Tadasuke , Ushino Takuhiro , Tokunaga Kazuhiko , Okazaki Takao , Kinoshita Tomomi , Ohga Yasushi
Published: January 2005

Various highly crowded tertiary alkyl chlorides having a neopentyl or a (1‐adamantyl)methyl substituent on the reaction center were subjected to solvolysis rate studies, and the Grunwald–Winstein (GW) type relationship with respect to the YCl scale was examined. Analyses of the plots showed that these bulky substituents efficiently preclude the nucleophilic solvent participation from the rear side and that the data points for non‐aqueous protic solvents give linear GW type plots. On the other hand, increased crowding causes considerable downward dispersions of the data points in aqueous mixtures of ethanol, acetone and 1‐propanol. The magnitude of the downward dispersion increases in this order, giving a curvature with a downward bulge in the GW type relationship. Aqueous mixtures of the smallest alcohol, methanol, on the other hand, give only slight downward dispersions of the data points, which constitute a linear GW type plot. These results can be explained in terms of two causes. First, structural crowding makes the transition state of ionization less susceptible to the Brønsted base‐type hydration to the β‐hydrogens than 1‐chloroadamantane as the standard of the YCl scale. Second, with highly hydrophobic substrates the first solvation shell in aqueous ethanol is expected to become more ethanol rich than the bulk phase, causing less easy ionization of the substrate. The rate data can be semiquantitatively analyzed by using Hansch's hydrophobicity parameters. The present anomalies found in solvolysis reactions are regarded as a kinetic version of Wepster's observations of the solvent effects on the magnitude of Hammett σ constants of bulky alkyl groups. Copyright © 2001 John Wiley & Sons, Ltd.
Solvent effect on the volume of activation and volume of the Diels–Alder reaction
Authors: Kiselev Vladimir D. , Konovalov Alexandr I. , Asano Tsutomu , Kashaeva Elena A. , Iskhakova Gulnara G. , Shihab Mahdi S. , Medvedeva Margarita D.
Published: January 2005

Volumes of activation, ΔV≠, and reaction, ΔV, partial molar volumes, $\bar{V}$, and enthalpies of solution, ­ΔsolH, were determined for tetracyanoethylene, cyclopentadiene, 1,3‐butadiene, trans, trans‐1,4‐diphenyl‐1,3‐butadiene and their Diels–Alder adducts at 25 °C in some solvents of π‐ and n‐donor type. The values of the activation and reaction volumes were exceptionally small in the former type of solvents. Large solvent effects on ΔsolHTCNE (up to 26 kJ mol−1), $\bar{V}$TCNE, ΔV and ΔV≠ (up to 11 cm3mol−1) were observed in aromatic solvents and these values are linearly correlated with each other. Poor correlations were found for n‐donor solvents, but a linear dependence between ΔV and δr−nH (enthalpy of reaction) was obtained for all solvents. Copyright © 2001 John Wiley & Sons, Ltd.
A quantum‐chemical study of PBX: intermolecular interactions of TATB with CH2F2 and with linear fluorine‐containing polymers
Authors: Xiao He‐Ming , Li Jin‐Shan , Dong Hai‐Shan
Published: January 2005

The calculations of density functional theory at the B3LYP/3‐21G* level have been employed to optimize the 1,3,5‐triamino‐2,4,6‐trinitrobenzene (TATB)CH2F2 complex. The complex binding energy is corrected for the basis set superposition error. In addition, the interactions of TATB with (CUVCXY)
n (U, V, X, Y = H. U = F; V, X, Y = H. U, V = F; X, Y = H. U, V, X = F; Y = H. U, V, X, Y = F. U, V, X = F; Y = Cl) have been studied with the MO‐PM3 method, and the complex binding energy with approximation of electron correlation correction by the dispersion energy has been given. The results computed indicate that the greatest corrected binding energy of TATB and CH2F2 is −4.62 kJ mol−1 at the B3LYP/6‐311G*//B3LYP/3‐21G* level. The interactions of ­(CF2CH2)
n with TATB and of (CF2CFH)
n with TATB are stronger than those of (CUVCXY)
n (U, V, X, Y = H. U = F; V, X, Y = H. U, V, X, Y = F. U, V, X = F; Y = Cl) with TATB (n = 5). Copyright © 2001 John Wiley & Sons, Ltd.
Linear free energy relationship analysis of the solubility of solids in supercritical CO2
Authors: Saunders Robert A. , Platts J. A.
Published: January 2005

Linear free energy relationship (LFER) methods were used to construct a model for the solubility of a species in supercritical CO2. The final model was based on 64 molecules and 782 data points, employing a modified version of the Abraham LFER equation incorporating π1, the dipolarity/polarizability of the CO2 at a given density. This allowed us to model data ranging from 308 to 435 K and 74.3 to 410 bar, with an accuracy of ±0.65 log mole fraction units. The model shows that solubility in supercritical CO2 is favoured by the presence of π and n electron pairs and hydrogen‐bond basicity. Solute size and hydrogen‐bond acidity are less important, whereas polarity/polarizability is statistically insignificant. Copyright © 2001 John Wiley & Sons, Ltd.
Bisimide–Lactamimide ring contraction in six‐membered bisimides: a theoretical study
Authors: Ponce Patricia , Fomina Lioudmila , Fomine Serguei
Published: January 2005

The bisimide–lactamimide ring contraction reaction of six‐membered bisimides has been modeled at the B3PW91/6‐31 + G(d,p)//HF/3‐21G level of theory using the isodensity polarized continuum model to take into account the solvent effect. Basically, the results of molecular modeling support the validity of the proposed mechanism. However, the calculations suggest that the final reaction step involves the direct oxidation of dianions by molecular oxygen, instead of oxidation of the hydroaromatic intermediate as proposed previously. The reactivity difference between N‐alkyl and N‐phenyl bisimides in the ring contraction reaction has been explained. Copyright © 2001 John Wiley & Sons, Ltd.
Correlation analysis of reactivity in the oxidation of substituted benzaldehydes by pyridinium hydrobromide perbromide
Authors: Aneja Meenakshi , Kothari Seema , Banerji Kalyan K.
Published: January 2005

The oxidation of benzaldehyde and 35 monosubstituted benzaldehydes by pyridinium hydrobromide perbromide (PHPB) in aqueous acetic acid leads to the formation of the corresponding benzoic acids. The reaction is first order with respect to each of the benzaldehydes and PHPB. Addition of pyridinium bromide has no effect on the rate of oxidation. The oxidation of [2H]benzaldehyde (PhCDO) indicated the presence of a substantial kinetic isotope effect. The effect of solvent composition indicated that the reaction rate increases with increase in the polarity of the solvent. The rates of oxidation of meta‐ and para‐substituted benzaldehydes were correlated in terms of Charton's triparametric LDR equation whereas those of ortho‐substituted benzaldehydes were correlated with a tetraparametric LDRS equation. The oxidations of para‐ and ortho‐substituted benzaldehydes are more susceptible to the delocalization effect while the oxidation of meta‐substituted compounds displays a greater dependence on the field effect. The positive value of η suggests the presence of an electron‐deficient reaction centre in the rate‐determining step. The reaction is subjected to steric hindrance by the ortho substituents. Copyright © 2001 John Wiley & Sons, Ltd.
Application of correlation analysis to solvolytic reactions of tertiary haloalkanes and Menschutkin reactions
Authors: Gonçalves Raquel M. C. , Albuquerque Lídia M. P. C.
Published: January 2005

We present a selection of our studies concerning solvent, substrate and temperature effects in solvolytic and Menschutkin reactions, by means of multiparametric equations and, more recently, by the use of factor analysis. Important steps in this development are recapitulated: (i) the application of correlation relationships relating rate constants to the properties of the solvents and of the solvents, substrates and temperature, simultaneously; (ii) the dissection of solvent effects into contributions from the initial state and the transition state; (iii) the split of intermolecular forces through the application of linear solvation energy relationships to the enthalpies of solution; and (iv) recent developments including the use of target factor analysis. The parametric descriptions reveal the dominant interaction mechanisms. Copyright © 2001 John Wiley & Sons, Ltd.
Predominance of 2‐arylhydrazones of 1,3‐diphenylpropane‐1,2,3‐trione over its proton‐transfer products
Authors: Gawinecki Ryszard , Kolehmainen Erkki , Janota Henryk , Kauppinen Reijo , Nissinen Maija , Ośmiałowski Borys
Published: January 2005

2‐Phenylhydrazones of 1,3‐diphenyl‐1,2,3‐trione are the dominant tautomeric form detected in chloroform solution by 15N NMR chemical shifts. The substituent in the phenylhydrazone moiety does not affect this tautomeric preference. The substituent effect is transmitted effectively only to the hydrazone nitrogen and hydrogen atoms. Ab initio calculations show that the ketohydrazone tautomer is really very much favoured over its proton‐transfer products in chloroform solution. The same tautomer was also detected in the crystal state by X‐ray crystallography. Copyright © 2001 John Wiley & Sons, Ltd.
Optimization of micellar catalysis of nucleophilic substitution reactions in buffered solutions of cetyltrimethylammonium halide surfactants, part 2: buffers in the pH range 7–8
Authors: Ouarti Nadia , Blagoeva Iva B. , Seoud Omar A. El , Ruasse Marie‐Françoise
Published: January 2005

Binding of the phosphate, tris‐(hydroxymethyl)‐methylamine, aminomethylpropanediol, and glycinemethylester buffers by cetyltrimethylammonium chloride (CTACl) in aqueous solutions has been probed by investigating: (1) the dependence of the buffer pH (starting pH 7.9) on [CTACl], and (2) the micellar effect on the kinetics of dephosphorylation of p‐nitrophenyldiphenylphosphate (PNDPP) by the anion of isonitrosoacetylacetone (INAA) in CTACl solutions in the presence of the same buffers. The pH–[CTACl] profiles showed a marked dependence on the buffer employed and the coion, Y−, of its acidic component, $\hbox{RNH}_{3}^{+}\hbox{Y}^{-}$. The sizeable pH decrease observed with phosphate buffer (0.43 pH units for [Buffer] = 10−2 M at [CTACl] = 2 × 10−2 M) indicates that both buffer components, namely $\hbox{H}_{2}\hbox{PO}_{4}^{-}$ and $\hbox{HPO}_{4}^{2-}$, exchange with the surfactant counterion, Cl−. This ion exchange occurs at the expense of the nucleophile (anion of INAA)–Cl− counterpart. Indeed, the micellar acceleration of the phosphate‐buffered reaction is the smallest, kmax/kw = 410 (kmax and kw are the maximum pseudo first‐order rate constants in buffered micellar solutions and bulk water, respectively). Although CTACl micelles do not seem to incorporate the neutral component of amino buffers, the pH–[CTACl] profiles were found to depend on the nature in Y− (F−, Cl− or AcO−). The micellar accelerations (kmax/kw ≈ 600), however, were not strongly altered by a change in the buffer coion, except where Y− = F−. In the interfacial region, the partially desolvated fluoride ion behaves as a nucleophile, competing with INAA anion for the dephosphorylation of PNDPP. The rate–[surfactant] profiles were interpreted in terms of the pseudophase ion‐exchange model, as applied to a reaction scheme involving competitive exchanges of the oximate and Y− for the surfactant counterion. The second‐order rate constant of the micelle‐mediated reaction, smaller (ca one‐third) than that in bulk aqueous solution, is discussed in terms of the properties (ionic strength and microscopic polarity) of interfacial water. Copyright © 2001 John Wiley & Sons, Ltd.
The mode of transmission of electrical effects: evidence from infrared stretching frequencies
Authors: Charton Marvin , Charton Barbara I.
Published: January 2005

The transmission of the universal electrical effect in infrared stretching frequencies is well fit by the modified field effect model with m ≈ −1.5 ± 0.2. The considerable variation in rm/p, the ratio of transmission of the electrical effect through meta‐substituted benzene derivatives to that through para‐substituted benzene derivatives and rc/t, the ratio of the transmission of the electrical effect through the s‐cis conformer to that through the s‐trans conformer and the failure of these ratios to show a Gaussian distribution provides further evidence against the existence of the inductive effect. The values of rm/p obtained show that, in the general case, the Hammett equation is inferior to either di‐ or tri‐parametric equations, as it assumes the equality of ρm and ρp. This is also true of the Yukawa–Tsuno equation. It has been shown that the inductive effect does not fit the experimental data on the transmission of electrical effects in a range of chemical reactions and in infrared stretching frequencies. Recent quantum chemical calculations support the field effect as the mode of electrical effect transmission. The inductive effect model of electrical effect transmission should be abandoned. Copyright © 2001 John Wiley & Sons, Ltd.
Microstructure determination of methyl methacrylate and n‐butyl acrylate copolymers synthesized by atom transfer radical polymerization with two‐dimensional NMR spectroscopy
Authors: Brar A. S. , Kaur Sukhdeep
Published: January 2005

Copolymers of methyl methacrylate (MMA) and n‐butyl acrylate (n‐BA) were synthesized under atom transfer radical polymerization (ATRP) conditions. The molar infeed ratio was varied to obtain copolymers with different compositions. Methyl 2‐bromo propionate was used as the initiator with CuBr/Cu(0)/N,N,N′,N″,N″‐pentamethyldiethylenetriamine as the catalyst at 60 °C. Molecular weight distribution was determined by gel permeation chromatography (GPC). Copolymer compositions (FM) were calculated from 1H NMR spectra. Reactivity ratios calculated with the Mao–Huglin terminal model at a high conversion were found to be rM = 2.17 and rB = 0.47. The polymerization mechanism was studied with the α‐methyl region of MMA. The backbone methylene and carbonyl carbons of both MMA and n‐BA units were found to be compositionally as well as configurationally sensitive. Complete spectral assignments were performed with the help of heteronuclear single quantum coherence (HSQC) spectroscopy along with total correlated spectroscopy (TOCSY). Further, the assignments of the carbonyl region were made with the help of heteronuclear multiple quantum coherence (HMBC) spectroscopy. © 2005 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 43: 1100–1118, 2005
Preparation of densely grafted poly(aniline‐2‐sulfonic acid‐co‐aniline)s as novel water‐soluble conducting copolymers
Authors: Hua Fengjun , Ruckenstein Eli
Published: January 2005

Various densely grafted polymers containing poly(aniline‐2‐sulfonic acid‐co‐aniline)s as side chains and polystyrene as the backbone were prepared. A styryl‐substituted aniline macromonomer, 4‐(4‐vinylbenzoxyl)(N‐tert‐butoxycarbonyl)phenylamine (4‐VBPA‐tBOC), was first prepared by the reaction of 4‐aminophenol with the amino‐protecting moiety di‐tert‐butoxyldicarbonate, and this was followed by substitution with 4‐vinylbenzyl chloride. 4‐VBPA‐tBOC thus obtained was homopolymerized with azobisisobutyronitrile as an initiator, and this was followed by deprotection with trifluoroacetic acid to generate poly[4‐(4‐vinylbenzoxyl)phenylamine] (PVBPA) with pendent amine moieties. Second, the copolymerization of aniline‐2‐sulfonic acid and aniline was carried out in the presence of PVBPA to generate densely grafted poly(aniline‐2‐sulfonic acid‐co‐aniline). Through the variation of the molar feed ratio of aniline‐2‐sulfonic acid to aniline, various densely grafted copolymers were generated with different aniline‐2‐sulfonic acid/aniline composition ratios along the side chains. The copolymers prepared with molar feed ratios greater than 1/2 were water‐soluble and had conductivities comparable to those of the linear copolymers. Furthermore, these copolymers could self‐dope in water through intermolecular or intramolecular interactions between the sulfonic acid moieties and imine nitrogens, and this generated large aggregates. © 2005 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 43: 1090–1099, 2005
Impact fracture toughness of polyamide‐6/montmorillonite nanocomposites toughened with a maleated styrene/ethylene butylene/styrene elastomer
Authors: Tjong S. C. , Bao S. P.
Published: January 2005

Polyamide‐6 (PA6)/montmorillonite (MMT) nanocomposites toughened with maleated styrene/ethylene butylene/styrene (SEBS‐g‐MA) were prepared via melt compounding. Before melt intercalation, MMT was treated with an organic surfactant agent. Tensile and impact tests revealed that the PA6/4% MMT nanocomposite fractured in a brittle mode. The effects of SEBS‐g‐MA addition on the static tensile and impact properties of PA6/4% MMT were investigated. The results showed that the SEBS‐g‐MA addition improved the tensile ductility and impact strength of the PA6/4% MMT nanocomposite at the expenses of its tensile strength and stiffness. Accordingly, elastomer toughening represents an attractive route to novel characteristics for brittle clay‐reinforced polymer nanocomposites. The essential work of fracture (EWF) approach under impact drop‐weight conditions was used to evaluate the impact fracture toughness of nanocomposites toughened with an elastomer. Impact EWF measurements indicated that the SEBS‐g‐MA addition increased the fracture toughness of the PA6/4% MMT nanocomposite. © 2005 Wiley Periodicals, Inc. J Polym Sci Part B: Polym Phys 43: 585–595, 2005
Enhanced rockfall activity during the Little Ice Age: further lichenometric evidence from a Norwegian talus
Authors: McCarroll Danny , Shakesby Richard A. , Matthews John A.
Published: January 2005

A recent study of lichen sizes on a talus in western Norway suggested that rockfall frequency was enhanced considerably during the cold conditions of the Little Ice Age. That conclusion is tested here using another talus in western Norway, in an area where lichen (genus Rhizocarpon) growth rates are higher. That part of the talus retaining a late Holocene record yields a lichen size–frequency distribution quite different to that reported in the previous study. However, when the appropriate lichenometric dating curve is used within a model that simulates the influence of late Holocene rockfall activity on lichen size–frequency distributions, a similar temporal pattern of rockfall supply is obtained. The results suggest that, at this site, rockfall frequency during the eighteenth century, the coldest phase of the Little Ice Age, may have been up to seven times higher than the normal late Holocene rate. Copyright © 2001 John Wiley & Sons, Ltd.

Une étude récente de la taille des lichens sur un talus de l'ouest de la Norvège suggérait que la fréquence des chutes de roches a été beaucoup plus élevée que maintenant pendant le ‘petit âge glaciaire.’ Cette conclusion est testée ici sur un autre talus de la même région où la vitesse de croissance des lichens est plus élevée. La partie du talus qui contient l' information portant sur la fin de l'Holocène montre une distribution de la taille des lichens tout à fait différente de celle mentionnée dans l'étude antérieure. Toutefois quand la courbe de datation lichenométrique est utilisée dans le cadre d'un modèle qui simule l'influence de l'activité des chutes de blocs holocènes sur la distribution des lichens, les auteurs obtiennent une figure de l'alimentation par chute de blocs comparable à celle de l'étude précédente. Le résultat suggère qu'en cet endroit la fréquence des chutes de blocs pendant le 18e siècle, qui a été la phase la plus froide du ‘petit âge glaciaire’ pourrait avoir été jusqu'à sept fois plus grande que la vitesse normale de la fin Holocène. Copyright © 2001 John Wiley & Sons, Ltd.
Reducing value chain vulnerability to terrorist attacks
Authors: Downes A.M. (Tony)
Published: January 2005

Like most U.S. chemical companies, you probably know where your security‐sensitive inventories are located within your sites and have assured yourself that you have taken reasonable precautions to reduce the risk of their being used in a terrorist attack. What about when you ship them? How secure are the various parts of your value chain—offsite storage and transportation of your products, raw materials, intermediates, and wastes, and processing of ordering and invoicing transactions? Value chain security focuses on tampering and misuse of materials handled outside the plant boundaries.

At FMC, we took a three‐stage approach to identifying and dealing with potential security issues posed by materials in transit. Stage 1 was a quick review to determine which of our products, intermediates, or raw materials might be potentially useful to terrorists. In Stage 2 we looked for specific security‐emergency scenarios that might involve those chemicals, estimated the risk of those scenarios, and made recommendations to reduce the vulnerability to terrorist attack. In Stage 3 we are implementing the plans we developed.

FMC's approach has successfully focused our efforts and used familiar techniques to break down complex Value Chains into manageable sections and then to identify the possible scenarios and (relative) risks at each section. We were able to do this with minimal travel costs.

This paper describes the general organization of FMC's value chain security efforts and our analysis technique, and discusses lessons (including a few surprises) that we have learned from the analyses. © 2005 American Institute of Chemical Engineers Process Saf Prog, 2005
Herbicide‐resistant crops and weed resistance to herbicides
Authors: Owen Micheal DK , Zelaya Ian A
Published: January 2005

The adoption of genetically modified (GM) crops has increased dramatically during the last 3 years, and currently over 52 million hectares of GM crops are planted world‐wide. Approximately 41 million hectares of GM crops planted are herbicide‐resistant crops, which includes an estimated 33.3 million hectares of herbicide‐resistant soybean. Herbicide‐resistant maize, canola, cotton and soybean accounted for 77% of the GM crop hectares in 2001. However, sugarbeet, wheat, and as many as 14 other crops have transgenic herbicide‐resistant cultivars that may be commercially available in the near future. There are many risks associated with the production of GM and herbicide‐resistant crops, including problems with grain contamination, segregation and introgression of herbicide‐resistant traits, marketplace acceptance and an increased reliance on herbicides for weed control. The latter issue is represented in the occurrence of weed population shifts, the evolution of herbicide‐resistant weed populations and herbicide‐resistant crops becoming volunteer weeds. Another issue is the ecological impact that simple weed management programs based on herbicide‐resistant crops have on weed communities. Asiatic dayflower (Commelina cumminus L) common lambsquarters (Chenopodium album L) and wild buckwheat (Polygonum convolvulus L) are reported to be increasing in prominence in some agroecosystems due to the simple and significant selection pressure brought to bear by herbicide‐resistant crops and the concomitant use of the herbicide. Finally, evolution of herbicide‐resistant weed populations attributable to the herbicide‐resistant crop/herbicide program has been observed. Examples of herbicide‐resistant weeds include populations of horseweed (Conyza canadensis (L) Cronq) resistant to N‐(phosphonomethyl)glycine (glyphosate). An important question is whether or not these problems represent significant economic issues for future agriculture. Copyright © 2005 Society of Chemical Industry
Molecular evolution of herbicide resistance to phytoene desaturase inhibitors in Hydrilla verticillata and its potential use to generate herbicide‐resistant crops
Authors: Arias Renée S , Netherland Michael D , Scheffler Brian E , Puri Atul , Dayan Franck E
Published: January 2005

Hydrilla [Hydrilla verticillata (Lf) Royle] is one of the most serious invasive aquatic weed problems in the USA. This plant possesses numerous mechanisms of vegetative reproduction that enable it to spread very rapidly. Management of this weed has been achieved by the systemic treatment of water bodies with the herbicide fluridone. At least three dioecious fluridone‐resistant biotypes of hydrilla with two‐ to fivefold higher resistance to the herbicide than the wild‐type have been identified. Resistance is the result of one of three independent somatic mutations at the arginine 304 codon of the gene encoding phytoene desaturase, the molecular target site of fluridone. The specific activities of the three purified phytoene desaturase variants are similar to the wild‐type enzyme. The appearance of these herbicide‐resistant biotypes may jeopardize the ability to control the spread of this non‐indigenous species to other water bodies in the southern USA. The objective of this paper is to provide general information about the biology and physiology of this aquatic weed in relation to its recent development of resistance to the herbicide fluridone, and to discuss how this discovery might lead to a new generation of herbicide‐resistant crops. Copyright © 2005 Society of Chemical Industry
High‐Tc cuprate superconductivity in a nutshell
Authors: Won Hyekyung , Haas Stephan , Parker David , Maki Kazumi
Published: January 2005

The cover picture shows the quasiparticle spectra of the vortex states of the high‐Tc nodal superconductor PrOs4Sb12: the p+h‐wave of the A‐phase (left) and that of the B‐phase (right).

The present issue of physica status solidi (b) contains invited and contributed papers from the 28th International Conference of Theoretical Physics – Electron Correlations in Nano‐ and Macrosystems (ICTP2004) which was held from 2–7 September 2004 in Ustroń, Poland.
Cytotoxic activity of Justicia spicigera is inhibited by bcl‐2 proto‐oncogene and induces apoptosis in a cell cycle dependent fashion
Authors: Cáceres‐Cortés J. R. , Cantú‐Garza F. A. , Mendoza‐Mata M. T. , Chavez‐González M. A. , Ramos‐Mandujano G. , Zambrano‐Ramírez I. R.
Published: January 2005

Identification of organic compounds from plants is of clinical significance because of the effect that they might have in patients with haematopoietic disorders. We studied the effect of the plant extract Justicia spicigera (Acanthaceae) in different haematopoietic cells: human leukaemic cell lines, umbilical cord blood cells, and mouse bone marrow cells.

By examining colony formation and performing the MTT (3‐(4,5‐dimethylthiazol‐2‐yl)‐2,5‐diphenyl tetrazolium bromide) assay it was shown that the plant extract of Justicia spicigera contains cytotoxic factors for leukaemic cells and has no proliferative activity on normal haematopoietic progenitor cells. Our results show that this plant extract induces apoptosis in the human leukaemia cell line TF‐1, but not in the bcl‐2 transfectant cell line TB‐1. Similar results were obtained using a haemopoietic cell line 32D and 32DBcl2. The cultures of umbilical cord blood cells and mouse bone marrow that contain granulocyte‐macrophage colony‐stimulating factor (GM‐CSF) do not proliferate or become terminally differentiated in the presence of the infusion of Justicia spicigera. GM‐CSF that acts by abrogating programmed cell death is not sufficient to inhibit the apoptotic stimulus in TF‐1 and 32D cells. Moreover mouse fibroblasts (3T3) and two cervical carcinoma cell lines CALO and INBL, undergo apoptosis in the presence of different concentrations of an infusion from the plant. Our data show that there is a strong correlation between the cytotoxic effect and cell proliferation. Together, these results indicate that the plant infusion of Justicia spicigera does not contain any haematopoietic activity, induces apoptosis inhibited by bcl‐2 and is linked to cell proliferation. Copyright © 2001 John Wiley & Sons, Ltd.
Electronic structure of laser dye DCM and its derivatives
Authors: Khohlova S. S. , Lebedev N. G. , Bondarev S. L. , Knyukshto V. N. , Turban A. A. , Mikhailova V. A. , Ivanov A. I.
Published: January 2005

The electron energetic characteristics of laser dye molecules 4‐dicyanomethylene‐2‐methyl‐6‐p‐dimethylamino‐styryl‐4H‐pyran (DCM), (E)‐2‐{2‐[2‐(4‐dimethylaminophenyl)ethynyl]‐6‐threefluoromethyl‐4H‐4‐pyranylidene}‐malonitrile (DCMF3), (E)‐2‐{2‐[2‐(4‐dimethylaminophenyl)ethynyl]‐6‐n‐heptafluoropropyl‐4H‐4‐pyranylidene}‐malonitrile (DCMF7), (E)‐2‐{2‐[2‐(5‐piperidine‐2‐thienyl)ethynyl]‐6‐threefluoromethyl‐4H‐4‐pyranylidene}‐malonitrile (PTFDN) were investigated thoroughly using semiempirical methods ZINDO/1 and ZINDO/S. The geometry optimization was carried out by the method of conjugated gradients. On the basis of the electronic structure and optimum geometry of the molecules, the spectra of electronic transitions to the excited states, the dipole moments, and oscillator strengths of the transitions were calculated by the method of configuration interaction. Typical features of the electronic absorption spectra of these molecules were calculated and compared with the experimental data. The influence of the solvent on the optical absorption spectra was explored. © 2005 Wiley Periodicals, Inc. Int J Quantum Chem, 2005
Development of an analytical system for the simultaneous determination of anabolic macrocyclic lactones in aquatic environmental samples
Authors: Laganá Aldo , Fago Giovanna , Marino Alessandra , Santarelli Daniela
Published: January 2005

An analytical procedure that enables routine analysis for trace determination of six anabolic macrocyclic lactones (zearalenone, α‐ and β‐zearalenol, zearalanone, zeranol, and taleranol) in sewage treatment plant (STP) samples has been developed. The method uses solid‐phase extraction, followed by high‐performance liquid chromatography with on‐line tandem mass spectrometry using atmospheric pressure chemical ionization (LC/APCI‐MS/MS). The extraction of these compounds from filtered water samples was performed off‐line with C18 solid‐phase cartridges. The detection was achieved by isocratic reversed‐phase high‐performance liquid chromatography coupled with an heated nebulizer (HN) APCI interface operating in negative ion mode. Mean recovery of the analytes in STP effluent samples generally exceeded 81%. This method was used to determine the occurrence of target analytes in the aquatic environment. In the selected STP effluent samples, zearalenone and α‐zearalenol were detected in the ng/L range. Copyright © 2001 John Wiley & Sons, Ltd.
The potential of inductively coupled plasma mass spectrometry detection for high‐performance liquid chromatography combined with accurate mass measurement of organic pharmaceutical compounds
Authors: Axelsson B‐O. , Jörnten‐Karlsson M. , Michelsen P. , Abou‐Shakra F.
Published: January 2005

Quantification of unknown components in pharmaceutical, metabolic and environmental samples is an important but difficult task. Most commonly used detectors (like UV, RI or MS) require standards of each analyte for accurate quantification. Even if the chemical structure or elemental composition is known, the response from these detectors is difficult to predict with any accuracy. In inductively coupled plasma mass spectrometry (ICP‐MS) compounds are atomised and ionised irrespective of the chemical structure(s) incorporating the element of interest. Liquid chromatography coupled with inductively coupled plasma mass spectrometry (LC/ICP‐MS) has been shown to provide a generic detection for structurally non‐correlated compounds with common elements like phosphorus and iodine. Detection of selected elements gives a better quantification of tested ‘unknowns’ than UV and organic mass spectrometric detection. It was shown that the ultrasonic nebuliser did not introduce any measurable dead volume and preserves the separation efficiency of the system. ICP‐MS can be used in combination with many different mobile phases ranging from 0–100% organic modifier. The dynamic range was found to exceed 2.5 orders of magnitude. The application of LC/ICP‐MS to pharmaceutical drugs and formulations has shown that impurities can be quantified below the 0.1 mol‐% level. Copyright © 2001 John Wiley & Sons, Ltd.
Electrospray tandem mass spectrometry of lexitropsins
Authors: Domingues M. Rosário M. , Domingues Pedro , Gajewski Mariusz , Czuchajowski Leszek , Ferrer‐Correia A. J.
Published: January 2005

Several compounds, representative of the class of lexitropsins, were analyzed by electrospray tandem mass spectrometry. The study of the fragmentations of the protonated molecular species ([M + H]+) and of selected fragment ions allowed proposals for the main fragmentation pathways of compounds of this type. The interpretation of the fragmentation pathways of these compounds was complicated because of intramolecular hydrogen migration. In order to better understand the fragmentation pathways, the MS/MS/MS spectra of several compounds, and the MS/MS and MS/MS/MS spectra of the deuterated compounds, were obtained. Accurate mass measurements helped elucidate the structures of smaller fragment ions. Low‐energy collision‐induced decomposition (CID) tandem mass spectrometry of lexitropsins with electrospray ionization has proven to be a good method for the structural characterization and identification of this class of compounds. Main fragmentation pathways occur by cleavage of the peptide bond followed by the elimination of the substituted pyrrole ring, and their elucidation will facilitate structural characterization of new lexitropsins. Copyright © 2001 John Wiley & Sons, Ltd.
RNA–RNA noncovalent interactions investigated by microspray ionization mass spectrometry
Authors: Hoyne Paula Rodrigues , Benson Linda M. , Veenstra Timothy D. , Maher L. James , Naylor Stephen
Published: January 2005

Electrospray ionization mass spectrometry is playing an increasing role in the study of noncovalent interactions involving biomolecules. RNA–RNA complexes are important in many areas of biology, including RNA catalysis, RNA splicing, ribosome function, and gene regulation. Here, microelectrospray mass spectrometry (µESI‐MS) is used to study noncovalent base‐pairing interactions between RNA oligonucleotides, an area not previously explored by this technique. Using a set of complementary RNA oligonucleotides, we demonstrate the formation of the expected double‐helical RNA complexes composed of three distinct oligonucleotides. The ability to study specific RNA noncovalent interactions by µESI‐MS has the potential to provide a unique method by which to analyze and assign precise molecular masses to RNA–RNA complexes. Copyright © 2001 John Wiley & Sons, Ltd.
Direct coupling of a nano‐high‐performance liquid chromatography column to an ion trap designed for a gas chromatography/mass spectrometry system
Authors: Moneti Gloriano , Pieraccini Giuseppe , Bartolucci Gianluca , Guida Gianni , Seraglia Roberta , Traldi Pietro
Published: January 2005

The possibility of direct liquid injection inside an ion trap, designed for a commercial gas chromatography/mass spectrometry (GC/MS) system, has been tested by continuous solution flow and by loop injection. Instrumental parameters such as solution flows and sample concentration, and temperatures of transfer line, ion trap and ion trap housing, have been optimised. Different configurations of the interface capillary have been also considered, and the best results have been obtained by the injection of the solution coaxially with a helium flow. The experimental arrangement leads to the detection of good quality electron (EI) and chemical (CI) ionisation spectra of low to medium polarity compounds, at µM levels. The direct coupling of a nano‐HPLC column with the modified transfer line led on one hand to EI spectra which were successfully employed for library searches, and on the other to CI data directly comparable to results achieved by a commercial HPLC/MS system operating under ESI conditions. Copyright © 2001 John Wiley & Sons, Ltd.
Laser ablation of Co/Ge mixtures: a new type of endohedral structure, a semiconductor cage trapping a metal atom
Authors: Zhang Xia , Li Guoliang , Gao Zhen
Published: January 2005

In experiments on Co/Ge binary clusters by laser vaporization, a remarkably strong signal in the mass spectrum was presented, which was assigned to the cluster anion consisting of ten germanium atoms and one cobalt atom, [CoGe10]−. For this cluster anion we suggest an endohedral structure – a Ge10 cage trapping a Co atom in its interior. Reactions between cobalt clusters and germanium clusters using a laser double ablation reactor also confirmed the endohedral structure. According to the electronic and geometrical shell closures, a bicapped tetragonal antiprism structure was predicted for this endohedral [CoGe10]− cluster anion. Copyright © 2001 John Wiley & Sons, Ltd.