bluuebunny/crossref_metadata_2025 huggingface dataset:
Computer simulation of urethane formation
Authors: Shy L. Y. , Eichinger B. E.
Published: April 2007

Computer model calculations have been used to simulate the reaction of polyoxypropylene triol with hexamethylene diisocyanate. Various molecular weight distributions and degrees of polymerisation are used in the calculation. The effect of side reactions is investigated and compared with experiment. Good agreement for both cyclisation and gel points is found for bulk and concentrated solutions. The model can be used to simulate random polycondensation reactions with a reliability approaching that of experiments, and it gives crucial results that cannot be obtained in any other way.
Effects of functionality and temperature on gel points in random polymerisation
Authors: Ahmad Zahoor , Stepto Robert F. T. , Still Richard H.
Published: April 2007

First, the relationship between gel point and average functionality for an RA2+R′Bf type polymerisation has been investigated by measuring the product of extents of reaction at gelation (αc) for sebacoyl chloride (SC)/polyoxyproplyene (POP)diol/POP triol mixtures reacting at various initial dilutions in diglyme as solvent at 60°C. Intramolecular reaction always delays gelation and a generalisation of the Ahmad‐Stepto gel point expression has been used to interpret the gelation data in terms of the ring‐forming parameter λ′ab. From the variation of λ′ab with initial dilution, values of b, the effective bond length of the chain forming the smallest ring structure, have been derived. It is found that b decreases with average polyol functionality (fw). This decrease apparently compensates for the increase in λ′ab with fw, so that ring formation is less sensitive to functionality than may have been expected. It is found that the Ahmad‐Stepto expression does not predict a consistent relationship between λ′ab, fw and the gel dilution of reactive groups.

Second, the effect of temperature on the gel point has been studied by measuring αc for SC/POP triol mixtures reacting at various initial dilutions in diglyme as solvent at 27° C, 40° C and 60° C. At a given temperature, b decreases as triol molar mass increases, indicating that the POP residue of the chain forming the smallest ring structure is more flexible than the SC residue. This result is in keeping with those from previous investigations,1,2 For a given triol, αc decreases as temperature increases, indicating an increase in chain stiffness with temperature. Values of d In /dT are derived and found to be larger than those for linear chains.
In situ investigation by quasi‐elastic light scattering of an irreversible sol‐gel transition
Authors: Candau S. J. , Ankrim M. , Munch J. P. , Hild G.
Published: April 2007

We report a dynamic light scattering study of semi‐dilute solutions of polydisperse branched polymers. The autocorrelation function of the intensity of scattered light exhibits two decay modes. Experiments performed in situ on the sol phase of a system undergoing irreversible gelation show that the slow relaxation time diverges at the sol‐gel transition.
Inhomogeneity of gel and microsyneresis in porous styrene‐divinylbenzene copolymers
Authors: Galina Henryk , Kolarz Bozena N. , Wieczorek Piotr P. , Wojczynska Maria
Published: April 2007

The porosity of styrene‐divinylbenzene copolymers prepared by suspension copolymerisation of the monomers carried out in the presence of inert diluent changes due to solvent pretreatment is investigated. The changes seem to reflect the inhomogeneity of copolymer gel. Various portions of it are transferred from the rubber‐like into the glassy state at different stages of either swelling solvent exchange or the drying process. A microsyneresis, i.e. a local collapse of loosely crosslinked gel portions not followed by a shrinkage of the whole system, leads to the porosity changes.
Inhomogeneity during the bulk polymerisation of divinyl compounds: Differential scanning calorimetry experiments and percolation theory
Authors: Boots H. M. J. , Kloosterboer J. G. , Van Hei G. M. M. De , Pandey R. B.
Published: April 2007

Experiments are presented that indicate inhomogeneity in bulk divinyl polymerisation which persists far beyond the gel point and a percolation model is given by which this inhomogeneity is simulated. Isothermal differential scanning calorimetry experiments indicate trapping of radicals in regions of low mobility long before overall vitrification occurs. The results on pendant double bonds in divinyl polymerisation are similar to those obtained by Malinsky et al. for styrene/divinyl benzene copolymerisation. The percolation model used shows inhomogeneity in snapshots and provides a qualitatively correct description of the high extent of cyclisation at low conversion, in contrast to classical chemical kinetics. The model overestimates the crosslinking at high conversion.
Epoxy mechanical properties: Function of crosslink architecture
Authors: Timm Delmar C. , Ayorinde Ayodeji J. , Foral Ralph F.
Published: April 2007

A thermoset resin's molecular architecture is characterised by extent of reaction, crosslink average molecular weight and the average size of constituent macromolecules. Molecular analyses of extracts from cured resins via gel permeation chromatography yield microscopic estimates of this infrastructure. The number‐average molecular weight within the soluble oligomeric fraction correlates with crosslink average molecular weight: the extent of monomer conversion assists in developing a description of the molecular weight of constituent marcomolecules within the network structure. Macroscopic conformation couples observations by dynamic mechanical spectroscopy, compressive stress‐strain phenomena and impact resistance.
Novel precursors suitable for RIM polyurethane networks
Authors: Cawse John L. , Stanford John L. , Still Richard H.
Published: April 2007

The synthesis and development of novel, furan‐based diisocyanates (FDI) and myrcene‐based polyols (PM) with potential for polyurethane production are presented. Pure FDI compounds, similar in structure to 4,4'‐methylenediphenylene diisocyanate (MDI) were prepared unambiguously from fur‐furylamine as liquids of low volatility, stable down to 0° C. making them particularly suitable for RIM. Comparative kinetics studies with n‐butanol show the FDIs to behave as benzylic compounds with reactivities intermediate between those of aryl and alkyl diisocynates. Studies were made on segmented copolyurethanes prepared from FDI and polyol mixtures of 1,4‐butane diol (BD) and polytetrahydrofuran (Mn. 1010).

Hydroxyfunctional polymyrcenes were prepared from myrcene in n‐butanol at 100° C using hydrogen peroxide as initiator. The liquid rubbers formed (Mn, 2000‐4000; with fn, 2.3‐1.3 respectively) were shown by n.m.r. to comprise mainly substituted 1,4‐butadiene units and are similar to the commercially available polybutadienes (PB). Copolyurethane elastomers were prepared from polyol blends of PM and 1,4‐butane diol reacting with MDI.

Both series of FDI‐and PM‐based copolyurethanes were shown by d.s.c. d.m.a. and tensile measurements to possess properties comparable to analogous materials formed from, respectively, MDI‐ and PB‐based systems. In addition to their suitability for RIM, the results show the feasibility of deriving polyurethane feedstocks from naturally‐occurring, non‐oil based sources.
The influence of processing on biopolymeric structures
Authors: Richmond Peter , Smith Andrew C.
Published: April 2007

Maize grits and maize starch were extruded under a number of conditions using a twin screw extruder. Under equilibrium operation the extruder was dead stopped and the barrel contents removed. Samples from the raw input to the extrudate were examined using scanning electron microscopy, water solubility and aqueous dispersion rheology. The extrusion process results in deformation of the starch granular structure and the production of a new texture corresponding to a marked increase in solubility. Raw maize dispersions are characterised by low viscosity and dilatancy, whereas their heat treatment results in a viscous, shear thinning response. Extrusion results in a tendency to Newtonian behaviour in the limit of high shear and low moistures. This behaviour has been attributed to the reduced swelling functionality of the starch as a function of extrusion which causes a breakdown of the starch granules.
The microstructure of polypropylene welds as a guide to processing history
Authors: Oliveira M. J. , Hemsley D. A.
Published: April 2007

The well known occurrence of different crystalline forms in polypropylene and their easy recognition in the polarising microscope has provided a method of analysing the behaviour of this material during the production of hot plate welds. The different thermal behaviour of the α‐ and the β‐forms of crystalline polypropylene allows estimation of the thermal history of the polymer in the region of the weld. In particular it is possible to estimate the amount of material actually melted by contact with the hot plate. The effect of the original crystalline microstructure of the components being welded on the microstructure of the recrystallised material forming the weld bond has also been explored. It is possible to characterise the general crystalline texture in the weld bead in terms of the shear and thermal history of the material. The influence of pre‐ and post‐welding annealing of the polypropylene has been investigated and a difficulty is encountered in explaining an apparent ‘memory’ of β‐form crystallisation which conflicts with established x‐ray diffraction results.
The characterisation of polycarbonate‐containing graft copolymers and the kinetics of graft polymerisation
Authors: Eastmond G. C. , Harvey L. W.
Published: April 2007

This paper examines several procedures for selective degradation of the preformed polymer component (polycarbonate) of certain types of graft copolymers. A procedure based on a two‐phase alkaline hydrolysis of the polycarbonate is identified as the preferred technique because it provides a clean system for the quantitative recovery and subsequent characterisation of the grafts. The application of the technique to a series of polycarbonate/polystyrene graft copolymers is reported. The kinetics of free‐radical graft polymerisation of styrene and the molecular weight distributions of the polystyrene grafts are compared with those for styrene homopolymerisation performed at the same rates of initiation. This comparison allows several differences between the kinetics of graft and homopolymerisation to be identified, both prior to and after gelation. These factors are interpreted in terms of modifications to the rate coefficient for bimolecular termination of the propagating grafts. Two (possibly three) factors are identified which influence the polymerisation kinetics prior to gelation; their influences are contrary and their relative importances depend on the rate of initiation. After gelation an additional effect, termed the network effect, comes into force and dominates both the rates of graft polymerisation and the molecular weight distributions of the grafts.
Topochemical polymerisation of a diacetylene: Studies of lattice parameters and thermal expansion coefficients
Authors: Bloor David , Day Richard J. , Ando David J. , Motevalli Majid
Published: April 2007

The solid‐state polymerisation of the disubstituted diacetylene, 2,4‐hexadiynylene bis(p‐toluene sulphonate). has been studied by x‐ray diffraction in the temperature range 223 to 295 K. The variation in lattice parameters is shown to be similar to that reported in previous less extensive studies. This data is used to determine the behaviour of the thermal expansion coefficients as a function of polymer content. The relevance of these results to the question of polymer chain lengths at low conversion is discussed.
Statistical evaluation of methylol‐free melamine‐formaldehyde oligomer distributions: Empirical formulae from elemental analysis
Authors: Gebregiorgis T. , Gordon M.
Published: April 2007

The problem of measuring quantitatively and reliably the proportions of methylene‐ and ether bridges in melamine‐formaldehyde resins has resisted chemical and spectroscopic approaches. Such measurements are specially required for refining statistical models of the overall crosslinking reaction. Pregel samples contain oligomer mixtures which can be freed from pendent methylols by treatment with ammonia. They obey the empirical formula (C3N6H6)1(CH2)R(H2O)z, where R and z can be found by optimising over measurements of %C, %N and %H. The accepted structures lead to prediction of z = −0.5R if only ether bridges are present or z= −R if only methylene bridges are present. In principle, intermediate values of −0.5R>z>‐R could allow the proportions of the two kinds of bridges to be determined. However, over a wide range of ratios R of formaldehyde to melamine, results are found to obey z = −0.2R, indicating retention of free water in the samples. Prolonged vacuum drying at room temperature may overcome the problem.
Copolymer melt rheograms from melt flow index
Authors: Shenoy A. V. , Saini D. R.
Published: April 2007

Available literature data on the variation of melt viscosity with shear rate are shown to coalesce together to give unique curves for each copolymer type, independent of temperature and copolymer grade, based on a normalising technique using the Melt Flow Index. The unified curves obtained are useful for estimating the flow curves of the copolymers at the temperature of interest if the Melt Flow Index of the copolymer at the specific temperature is known. Coalesced curves are presented for a number of commonly known copolymers such as acrylonitrile‐butadiene‐styrene, styrene‐butadiene‐styrene. vinyl chloride‐vinyl acetate, ethylene‐vinyl‐acetate, polyester elastomer and an olefinic‐tyype thermoplastic elastomer.
Analysis of a homologous series of non‐reducing oligosaccharides from Arnica montana L. Roots
Authors: White Charles A. , Kennedy John F. , Lombard Anna , Rossetti Valeria
Published: April 2007

The oligosaccharide component compositions of a series of non‐reducing oligosaccharides extracted from the roots of Arnica montana L. has been determined by gel permeation chromatography (g.p.c.). The range of oligosaccharides present was found to extend beyond the octasaccharide previously reported. with 16% to 19% of the oligosaccharides having a degree of polymerisation of between 11 and 19 and almost 3% having a degree of polymerisation greater than 20. The chromatographic behaviour of this series of oligosaccharides is compared with that observed for series of D‐gluco‐oligosaccharides.
Ultrasonic study of molecular association of poly(vinyl chloride) solution in tetrahydrofuran
Authors: Hassun Subhi K. , Al‐Madfai Suham H. F. , Al‐Jarrah Mustafa M. F.
Published: April 2007

Ultrasonic absorption, velocity, adiabatic compressibility, relaxation time and relaxation amplitude measurements are reported on poly(vinyl chloride) (PVC) solution in tetrahydrofuran (THF) using pulsed ultrasonic apparatus operating at 2 MHz and 313 K. Results show a linear increase of velocity. density, viscosity, absorption coefficient, relaxation time and relaxation amplitude values with the increase of PVC concentration in THF. In contrast the compressibility decreases with increasing PVC concentration. This suggests interaction between PVC and THF molecules.
Investigations on the cyanogen bromide activation of xanthan gum
Authors: Kennedy John F. , Hussain Meriam Adam
Published: April 2007

The CNBr activation procedure has been investigated as a means of synthesising derivatives of xanthan gum. Both the titration and buffer methods of the procedure were compared. While the degrees of activation obtained from both methods were pH‐dependent, the buffer method gave a slightly greater concentration of active groups. Imidocarbonates constituted the major reactive species in the activated polysaccharide. This indicated that the mechanism of activation and hence, coupling with amino‐ligands, of CNBr‐activated xanthan was similar to that postulated for Sephadex and other polyglucose polysac‐charides. However, the degree of activation of xanthan gum was considerably reduced in comparison to values obtained with Sephadex activated in a similar manner. It was concluded that this was due to the complex structure and conformation of xanthan gum in solution which was also thought to be responsible for the ability of the unreacted polysaccharide to interact non‐covalently with small amino‐ligands. The activated xanthan gum exhibited a reduced viscosity in solution compared to that of the native polysaccharide.
A preliminary study of blends of bisphenol a polycarbonate and poly(ethylene terephthalate)
Authors: Chen Xin‐Yue , Birley Arthur W.
Published: April 2007

The microstructure of blends of bisphenol A polycarbonate (PC), and poly(ethylene terepthalate) (PETP) has been studied by solvent extraction, infrared spectrophotometry, differential scanning calorimetry and dynamic mechanical thermal analysis. The blends appear to contain two amorphous phases over the whole composition range. The tensile behaviour and the Charpy impact strength of some of the blends have been determined, before and after heat treatment at 125°C for 18 hours. Improved performance of the blends, compared with that of the homopolymers PC and PETP, has been demonstrated.
Curing of epoxy resin of 1,1'‐bis(4‐hydroxy phenyl) cyclohexane with phthalic anhydride. A differential scanning calorimetric investigation
Authors: Shah Praful P. , Parsania Pursottam H. , Patel Shanti R.
Published: April 2007

Curing reactions of epoxy resin of 1,1'‐bis(4‐hydroxy phenyl) cyclohexane with phthalic anhydride have been investigated by differential scanning calorimetry. The overall kinetics of curing have been found to follow a simple Arrhenius‐type rate‐temperature dependence, with an average overall activation energy of 75.4 ± 8.0 kJ mol−1 and natural log of Arrhenius frequency factor of about 18 min−1 up to at least 90% conversion. The curing reaction is found to follow overall first‐order kinetics.
Electron irradiation of polymerisable langmuir‐blodgett multilayers as model resists for electron‐beam lithography
Authors: Boothroyd Brian , Delaney Paul A. , Hann Richard A. , Johnstone Robert A. W. , Ledwith Anthony
Published: April 2007

Amphiphilic molecules containing a polymerisable oxiran (epoxide) group have been assembled into Langmuir‐Blodgett multilayers. Lines were drawn on the multilayers by exposure to an electron beam and subsequent development by rinsing in toluene. Line widths and heights were examined for various doses of electrons of energies 10, 5 and 2 kV. Generally, for the higher energies and shorter exposures, narrow well defined lines were obtained of height similar to the thickness of the original multilayers. Conversely, at lower energies and exposure times, troughs rather than lines were observed following incomplete development. The implications of these results are compared with theoretical predictions of bbnd forming and bond scission processes during electron irradiation of organic molecules.
Deposition mechanisms in langmuir‐blodgett films
Authors: Peterson I. R. , Russell G. J.
Published: April 2007

As part of a study of the possible application of polymerisable Langmuir‐Blodgett (LB) films as ultra‐fine‐line e‐beam resists, an investigation of the variation of film structure of 22‐tricosenoic acid with differing deposition conditions has been made. Unexpected effects with significant implications for deposition speed and resist sensitivity have been observed, and the new techniques for film characterisation developed during the investigation have resulted in a revised model of deposition explaining the observed independence of the disorder causing optical scattering and the macroscopic features observed by polarised microscopy.
Langmuir‐blodgett films from preformed polymers
Authors: Hodge Philip , Khoshdel Ezzatollah , Tredgold Richard H. , Vickers Anthony J. , Winter Christopher S.
Published: April 2007

Recent work on Langmuir films and Langmuir‐Blodgett films prepared from derivatives of styrene‐maleic anhydride and octadec‐1‐ene‐maleic anhydride copolymers is reviewed.
Fundamentals of Hydrogels and Gelation
Authors: Ross‐Murphy Simon B. , McEvoy Henry
Published: April 2007

A discussion of the properties of that class of materials known as ‘hydrogels’ must make particular reference to (i) a working definition of what is meant by a ‘gel’, (ii) the manner in which this relates to the underlying macromolecular structure, and (iii) how these properties are affected by the presence of water within the macromolecular network. The first point is answered by providing an operational definition of a gel, which depends on the mechanical response of the material to oscillatory shear. This type of behaviour is shown to be quantitatively related to the degree of connectivity of the network. The chemical aspects of the problem address the relationship between this and the degree of reaction achieved by those chemical or physical features responsible for crosslinking. Finally, the swelling properties of such materials are discussed, and how these are complicated by the non‐ideal thermodynamic properties of the solvent water.
The Role of Permeability and Related Properties in the Design of Synthetic Hydrogels for Biomedical Applications
Authors: Tighe Brian J.
Published: April 2007

Synthetic hydrogels are a versatile range of materials which are of value in several biomedical applications, particularly those where permeability is important. Because the equilibrium water content of the gel governs permeability processes and has a marked influence on other important properties, the permeability requirements of a material often influence other aspects of its behaviour. The design of hydrogels for contact lenses demands an understanding of these interrelationships and thus provides a valuable basis for extending hydrogel design to other applications.
Molecular Interactions in Polysaccharide Gelation
Authors: Morris Edwin R.
Published: April 2007

The gel structures formed by naturally occurring polysaccharides, either in vivo (in, for example, plant tissue) or in vitro after extraction and purification, are normally crosslinked by extended intermolecular ‘junction zones’ of conformationally ordered chains. Formation and disruption of these ordered structures under biologically and industrially relevant conditions of extensive hydration may be monitored and characterised by a variety of physical techniques, in conjunction with x‐ray analysis at atomic resolution in the condensed phase by fibre diffraction. Interconnecting regions of residual disorder, necessary for solubilisation of the gel network, may be introduced by structural irregularities or block character in the primary sequence.
Synthetic Hydrogels as Substrata for Cell Adhesion Studies
Authors: Lyndon Michael J.
Published: April 2007

Synthetic polymer hydrogels have many proven and potential biomedical applications as wound coverings, drug delivery systems, surgical prostheses, contact lenses and in extracorporeal circuitry. Their success in long‐term contact with biological fluids and cellular tissue depends upon their interfacial properties in such environments, and in turn, upon their physical and chemical nature. One approach to defining requirements for interfacial events at polymer surfaces in vivo is to investigate cell adhesion behaviour on these materials in culture, and to correlate this behaviour with polymer structure and theories of in vivo biocompatibility. At the same time, polymer hydrogels provide the opportunity to extend existing cell culture systems for the study of environmental cues for cell behaviour under normal and pathological circumstances.
The Diffusion of Compact Macromolecules Within Hydrogels
Authors: Sellen D. B.
Published: April 2007

Studies of the diffusion of globular proteins and dextran fractions within polysaccharide and poly‐acryamide gels by laser light scattering are described. Gels of stiff polysaccharide chains scatter light which exhibits little spectral broadening, since apart from a small amount of structural relaxation they are almost stationary at a molecular level. Well defined diffusion coefficient of compact macromolecules within these gels can be measured. However, gels of relatively flexible polymers such as polyacrylamide are highly mobile at a molecular level, and scatter light which is spectrally broadened by the diffusion of fluctuations in acrylamide concentration. In this case there is a complex interaction between the two diffusion coefficients, with the diffusing compact macromolecules dominating at low gel concentrations, and the diffusing gel fluctuations dominating at high gel concentrations where they tend to control the movement of the compact macromolecules.
Controlled Release from Crosslinked Poloxamer Hydrogels
Authors: Law T. K. , Whateley T. L. , Florence A. T.
Published: April 2007

Chemically modified derivatives of the copolymeric poloxamer surfactants have been polymerised to form crosslinked, swelling hydrogels. Mixtures of derivatives of poloxamers 188 and 181 form gels which show increased swelling with increased content of the more hydrophilic poloxamer 188. The rate of release of benzoic and p‐hydroxybenzoic acids also increases with increasing content of poloxamer 188. Release rate data have been analysed in terms of the swelling controlled release model for these hydrogels.
Effect of Processing Conditions on Styrene‐Butadiene‐Styrene‐Thermoplastic Rubber
Authors: Canevarolo Sebastio V. , Birley Arthur W. , Hemsley Derek A.
Published: April 2007

The effects of shear rate, extrusion temperature and heat treatment on a lamellar triblock copolymer of styrene‐butadiene‐styrene were studied using extrudates from a capillary rheometer. The rheological behaviour is mainly non‐Newtonian in the region studied and the flow curves can be time‐temperature reduced. The quality of the domain structure PS phase was measured mechanically in terms of the stress at yield and optically by birefringence. Some of the factors considered during the analysis of the results are: rearrangement of the imperfect original domain structure taking place in the barrel, before extrusion, for temperatures higher than 145°C; partial destruction of this pre‐developed structure during extrusion; orientation of the chains during extrusion and under some conditions, the development of sharkskin on the surface of the extrudate. The heat treatment induces the copolymer to undergo three processes: internal stress relaxation (∼135°C); rearrangement of the imperfect domain structure (145°CT240°C); and crosslinking in the rubbery phase (T200°C).
Proteomic analysis of rice plasma membrane reveals proteins involved in early defense response to bacterial blight
Authors: Chen Fang , Yuan Yuexing , Li Qun , He Zuhua
Published: April 2007

Plant plasma membrane (PM) proteins play important roles in signal transduction during defense response to an attacking pathogen. By using an improved method of PM protein preparation and PM‐bound green fluorescent protein fusion protein as a visible marker, we conducted PM proteomic analysis of the rice suspension cells expressing the disease resistance gene Xa21, to identify PM components involved in the early defense response to bacterial blight (Xanthomonas oryzae pv. oryzae). A total of 20 regulated protein spots were observed on 2‐D gels of PM fractions at 12 and 24 h after pathogen inoculation, of which some were differentially regulated between the incompatible and compatible interactions mediated by Xa21, with good correlation between biological repeats. Eleven protein spots with predicted functions in plant defense were identified by MS/MS, including nine putative PM‐associated proteins H+‐ATPase, protein phosphatase, hypersensitive‐induced response protein (OsHIR1), prohibitin (OsPHB2), zinc finger and C2 domain protein, universal stress protein (USP), and heat shock protein. OsHIR1 was modified by the microbal challenge, leading to two differentially accumulated protein spots. Transcript analysis showed that most of the genes were also regulated at transcriptional levels. Our study would provide a starting point for functionality of PM proteins in the rice defense.
Proteomic analysis of up‐regulated proteins in human promonocyte cells expressing severe acute respiratory syndrome coronavirus 3C‐like protease
Authors: Lai Chien‐Chen , Jou Ming‐Jia , Huang Shiuan‐Yi , Li Shih‐Wein , Wan Lei , Tsai Fuu‐Jen , Lin Cheng‐Wen
Published: April 2007

The pathogenesis of severe acute respiratory syndrome coronavirus (SARS CoV) is an important issue for treatment and prevention of SARS. Previously, SARS CoV 3C‐like protease (3CLpro) has been demonstrated to induce apoptosis via the activation of caspase‐3 and caspase‐9 (Lin, C. W., Lin, K. H., Hsieh, T. H., Shiu, S. Y. et al., FEMS Immunol. Med. Microbiol. 2006, 46, 375–380). In this study, proteome analysis of the human promonocyte HL‐CZ cells expressing SARS CoV 3CLpro was performed using 2‐DE and nanoscale capillary LC/ESI quadrupole‐TOF MS. Functional classification of identified up‐regulated proteins indicated that protein metabolism and modification, particularly in the ubiquitin proteasome pathway, was the main biological process occurring in SARS CoV 3CLpro‐expressing cells. Thirty‐six percent of identified up‐regulated proteins were located in the mitochondria, including apoptosis‐inducing factor, ATP synthase beta chain and cytochrome c oxidase. Interestingly, heat shock cognate 71‐kDa protein (HSP70), which antagonizes apoptosis‐inducing factor was shown to down‐regulate and had a 5.29‐fold decrease. In addition, confocal image analysis has shown release of mitochondrial apoptogenic apoptosis‐inducing factor and cytochrome c into the cytosol. Our results revealed that SARS CoV 3CLpro could be considered to induce mitochondrial‐mediated apoptosis. The study provides system‐level insights into the interaction of SARS CoV 3CLpro with host cells, which will be helpful in elucidating the molecular basis of SARS CoV pathogenesis.
Differential proteomic analysis of the endoplasmic reticulum from developing and germinating seeds of castor (Ricinus communis) identifies seed protein precursors as significant components of the endoplasmic reticulum
Authors: Maltman Daniel J. , Gadd Stephen M. , Simon William J. , Slabas Antoni R.
Published: April 2007

The endoplasmic reticulum is a major compartment of storage protein and lipid biosynthesis. Maximal synthesis of these storage compounds occurs during seed development with breakdown occurring during germination. In this study, we have isolated four independent preparations of ER from both developing and germinating seeds of castor bean (Ricinus communis) and used 2‐D DIGE, and a combination of PMF and MS/MS sequencing, to quantify and identify differences in protein complement at both stages. Ninety protein spots in the developing seeds are up‐regulated and 19 individual proteins were identified, the majority of these are intermediates of seed storage synthesis and protein folding. The detection of these transitory storage proteins in the ER is discussed in terms of protein trafficking and processing. In germinating seed ER 15 spots are elevated, 5 of which were identified, amongst them was malate synthetase which is a component of the glyoxysome which is believed to originate from the ER. Notably no proteins involved in complex lipid biosynthesis were identified in the urea soluble ER fraction indicating that they are probably all integral membrane proteins.
Down‐regulation of pigment epithelium‐derived factor in uveitic lesion associates with focal vascular endothelial growth factor expression and breakdown of the blood‐retinal barrier
Authors: Deeg Cornelia A. , Altmann Frank , Hauck Stefanie M. , Schoeffmann Stephanie , Amann Barbara , Stangassinger Manfred , Ueffing Marius
Published: April 2007

Spontaneous equine recurrent uveitis (ERU) is an incurable autoimmune disease affecting the eye. Identifying biological markers or pathways associated with this disease may allow the understanding of its pathogenesis at a molecular level. The vitreous is the body fluid closest to the disease‐affected tissue and possibly also an effector of pathological processes relevant for ERU. Surgical removal of vitreous leads to cessation of relapses in spontaneous uveitis of both man and horse, therefore vitreous composites are likely to contribute to disease progression. Uveitic vitreous is likely to contain potential biomarkers in relatively undiluted quantities. With the goal to identify these markers, we systematically compared vitreous from healthy and disease‐affected eyes by proteomic profiling. Nine differentially expressed proteins were identified, that are functionally related to immune response, inflammation, and maintenance of the blood‐retinal barrier. One of these, pigment epithelium‐derived factor, a protein involved in maintaining a proper blood‐retina barrier as well as protecting from neoangiogenesis was additionally found to be down‐regulated within uveitic retinal lesions whereas, conversely, vascular endothelial growth factor was found to be up‐regulated at these sites. Together, these changes point to as of yet undiscovered biological pathways involved in the pathogenesis of this autoimmune disease.
A proteomic‐based approach for the characterization of some major structural proteins involved in host–parasite relationships from the silkworm parasite Nosema bombycis (Microsporidia)
Authors: Wang Jian‐Yang , Chambon Christophe , Lu Chang‐De , Huang Ke‐Wei , Vivarès Christian P. , Texier Catherine
Published: April 2007

Nosema bombycis is the causative agent of the silkworm Bombyx mori pebrine disease which inflicts severe worldwide economical losses in sericulture. Little is known about host–parasite interactions at the molecular level for this spore‐forming obligate intracellular parasite which belongs to the fungi‐related Microsporidia phylum. Major microsporidian structural proteins from the spore wall (SW) and the polar tube (PT) are known to be involved in host invasion. We developed a proteomic‐based approach to identify few N. bombycis proteins belonging to these cell structures. Protein extraction protocols were optimized and four N. bombycis spore protein extracts were compared by SDS‐PAGE and 2‐DE to establish complementary proteomic profiles. Three proteins were shown to be located at the parasite SW. Moreover, 17 polyclonal antibodies were raised against major N. bombycis proteins from all extracts, and three spots were shown to correspond to polar tube proteins (PTPs) by immunofluorescent assay and transmission electron microscopy immunocytochemistry on cryosections. Specific patterns for each PTP were obtained by MALDI‐TOF‐MS and MS/MS. Peptide sequence tags were deduced by de novo sequencing using Peaks Online and DeNovoX, then evaluated by MASCOT and SEQUEST searches. Identification parameters were higher than false‐positive hits, strengthening our strategy that could be enlarged to a nongenomic context.
Enhancement of proteolysis through the silica‐gel‐derived microfluidic reactor
Authors: Liu Yun , Qu Haiyun , Xue Yan , Wu Zhonglin , Yang Pengyuan , Liu Baohong
Published: April 2007

An on‐chip enzymatic reactor providing rapid protein digestion is presented. Trypsin‐embedding stationary phase within the microchannel has been prepared by the sol‐gel method. Such a microfluidic reactor has been used for low‐level protein digestion at 16 fmol per analysis. The analytical potential of the microreactor combined with the strong cation exchange and RPLC ESI‐MS/MS for the identification of real samples from the cytoplasma of the human liver tissue has been demonstrated.
C‐Terminal antibodies (CTAbs): A simple and broadly applicable approach for the rapid generation of protein‐specific antibodies with predefined specificity
Authors: Edwards Robert J. , Wrigley Amanda , Bai Zhonghu , Bateman Michaela , Russell Hugh , Murray Stephen , Lu Huafeng , Taylor Graham W. , Boobis Alan R. , Sriskandan Shiranee
Published: April 2007

Recent advances in proteomic techniques have resulted in an ever‐increasing need to produce antibodies. Here, to address this problem, a technically simple approach of targeting the extreme C‐termini of proteins with antibodies (CTAbs) was investigated in proteins secreted by the human pathogen Streptococcus pyogenes. Target proteins were identified by a conventional proteomic approach and CTAbs produced against synthetic five amino acid peptides representing the C‐terminus of each target protein. In every case where protein secretion was demonstrated (n = 20), CTAbs were successfully produced and bound specifically to the target protein (100% success rate). The apparent specificity was consistent with the structural heterogeneity of the C‐termini of S. pyogenes proteins. The global specificity of CTAb binding was defined using a combinatorial library of synthetic peptides representing structural variants of the original synthetic immunogen. This is a systematic and comprehensive approach for the development of antibodies with defined specificity that can be used in a range of applications.
A widespread picture of the Streptococcus thermophilus proteome by cell lysate fractionation and gel‐based/gel‐free approaches
Authors: Salzano Anna Maria , Arena Simona , Renzone Giovanni , D'Ambrosio Chiara , Rullo Rosario , Bruschi Maurizio , Ledda Luigi , Maglione Giuseppe , Candiano Giovanni , Ferrara Lino , Scaloni Andrea
Published: April 2007

Among the group of lactic acid bacteria, Streptococcus thermophilus has found a wide application in industrial processes used for the manufacture of dairy products. Taking advantage of different proteome extraction and subfractionation protocols, bacterial cytosolic and membrane proteins were isolated and resolved by independent gel‐free and gel‐based separation procedures. Whole cytosolic fraction and its acid, basic and low molecular mass protein components were separated by different resolutive 2‐DE and tricine 1‐DE gels and identified by MALDI‐TOF PMF and/or μLC‐ESI‐IT‐MS/MS. Membrane proteins were resolved by 2‐DE and SDS‐PAGE gels and similarly identified by PMF and TMS analysis. In parallel, whole extract was trypsinized and resulting peptides were identified by shotgun 2‐D LC‐ESI‐IT‐MS/MS analysis. Using this combined approach, expression products corresponding to 458 different genes were identified, which cover almost a third of the predicted vegetative proteome. Relative protein concentration and hydrophobicity affected protein detection. Broad recognition was obtained for enzymes involved in carbohydrate, fatty acid, amino acid and nucleotide metabolism, replication, transcription, translation, cell wall synthesis, as well as for proteins affecting bacterial functions important for industrial applications, i.e. milk sugar import and exopolysaccharide biosynthesis. By providing detailed reference electrophoretic/chromatographic maps to be used in future comparative proteomic investigations on bacteria grown under various experimental conditions or on different bacterial strains, our results will favour dedicated studies on S. thermophilus metabolism and its regulation or on detection of biomarkers for selection of optimal strains for industrial applications.
Evaluation of various DFT protocols for computing 1H and 13C chemical shifts to distinguish stereoisomers: diastereomeric 2‐, 3‐, and 4‐methylcyclohexanols as a test set
Authors: Wiitala Keith W. , Al‐Rashid Ziyad F. , Dvornikovs Vadims , Hoye Thomas R. , Cramer Christopher J.
Published: April 2007

1H and 13C NMR chemical shifts were measured for a set of six isomers—the cis and trans 2‐, 3‐, and 4‐methylcyclohexanols. 1H and 13C NMR chemical shifts were computed at the B3LYP, WP04, WC04, and PBE1 density functional levels for the same compounds, taking into account the Boltzmann distribution among conformational isomers (chair–chair forms and hydroxyl rotamers). The experimental versus computed chemical shift values for proton and carbon were compared and evaluated (using linear correlation (r2), total absolute error (|Δδ|T), and mean unsigned error (MUE) criteria) with respect to the relative ability of each method to distinguish between cis and trans stereoisomers for each of the three constitutional isomers. For 13C shift data, results from the B3LYP and PBE1 density functionals were not sufficiently accurate to distinguish all three pairs of stereoisomers, while results using the WC04 functional did do so. For 1H shift data, each of the WP04, B3LYP, and PBE1 methods was sufficiently accurate to make the proper stereochemical distinction for each of the three pairs. Applying a linear correction to the computed data improved both the absolute accuracy and the degree of discrimination for most of the methods. The nature of the cavity definition used for continuum solvation had little effect. Overall, use of proton chemical shift data was more discriminating than use of carbon data. Copyright © 2007 John Wiley & Sons, Ltd.
Synthesis of oligomeric urethane dimethacrylates with carboxylic groups and their testing in dental composites
Authors: Buruiana Emil C. , Buruiana Tinca , Melinte Violeta , Zamfir Mirela , Colceriu Aurora , Moldovan Marioara
Published: April 2007

Carboxyl urethane dimethacrylate oligomers with poly(ethylene oxide) sequences in the structure were synthesized and examined in photopolymerizable resins that could better adhere to various kinds of materials, including tooth substrates. Aspects of the morphogenesis of dental composites formed through a photochemically initiated radical copolymerization of the carboxylic derivatives, in addition to other partners encountered frequently in such materials, were studied comparatively with the corresponding urethane dimethacrylate monomer. The effect of a small quantity of a carboxylic macromer (ca. 10%) on the formation of a network with a non‐carboxyl urethane dimethacrylate oligomer (90%) as a potential substitute for diglycidyl methacrylate of bisphenol A and a filler (1/1 70% Aerosil/glass) was visualized by fluorescence spectroscopy with a pyrene methanol probe. The results showed the following: (1) the degree of conversion in the formulations into which carboxyl urethane dimethacrylate was incorporated decreased with increasing poly(ethylene oxide) chain length, (2) the formation of excimers was inhibited in the derived composites, and (3) an important quenching of the monomer fluorescence emission with the UV–vis irradiation time was observed in the formulation containing a filler (Aerosil+Zr/Sr glass). Preliminary testing of the resin composites suggested that all urethane oligomers containing carboxylic acid could lead to dental materials with reduced polymerization shrinkage and good mechanical properties. © 2006 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 45: 1956–1967, 2007
New thermosets obtained by the cationic copolymerization of diglycidyl ether of bisphenol A with γ‐caprolactone with an improvement in the shrinkage. I. Study of the chemical processes and physical characteristics
Authors: González Servando , Fernández‐Francos Xavier , Salla Josep Maria , Serra Angels , Mantecón Ana , Ramis Xavier
Published: April 2007

Diglycidyl ether of bisphenol A was cured with different proportions of γ‐caprolactone with ytterbium triflate as an initiator. The curing was studied by means of differential scanning calorimetry and Fourier transform infrared in the attenuated total reflection mode. The latter was used to monitor the competitive reactive processes and to quantify the conversions of the epoxide, lactone, and intermediate spiroorthoester groups. A partial depolymerization process from the cured material to free γ‐caprolactone was also identified. The formation of a stable carbocation and the coordinative capability of ytterbium triflate were the reasons for this unexpected process. The thermal and dynamic mechanical properties of the cured materials were determined with differential scanning calorimetry, thermogravimetric analysis, and dynamic mechanical thermal analysis. An increase in the proportion of γ‐caprolactone resulted in an increased curing rate, a decrease in the shrinkage after gelation, and a significant decrease in the glass transition temperature. The introduction of ester linkages into the three‐dimensional structure led to more thermally degradable thermosets. © 2006 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 45: 1968–1979, 2007
Synthesis of a novel bis‐spiroorthoester containing 9,10‐dihydro‐9‐oxa‐10‐phosphaphenantrene‐10‐oxide as a substituent: Homopolymerization and copolymerization with diglycidyl ether of bisphenol A
Authors: Canadell J. , Mantecón A. , Cádiz V.
Published: April 2007

A new bis‐spiroorthoester‐containing monomer, bis[(1,4,6‐trioxaspiro‐[4.4]‐nonan‐2‐yl)‐methyl] 2‐[10‐(9,10‐dihydro‐9‐oxa‐10‐phosphaphenantrene‐10‐oxide‐10‐yl)] maleate (SOE‐DOPOMA), was synthesized with good yields by an esterification reaction with a hydroxylated spiroorthoester (2‐hydroxymethyl‐1,4,6‐trioxaspiro‐[4.4]‐nonane) and a phosphorus‐containing diacid {2‐[10‐(9,10‐dihydro‐9‐oxa‐10‐phosphaphenantrene‐10‐ oxide‐10‐yl)] maleic acid}, both of which were previously synthesized. SOE‐DOPOMA was characterized with 1H, 13C, and 31P NMR spectroscopy. This new spiroorthoester was crosslinked with ytterbium triflate as a cationic initiator. A mixture of SOE‐DOPOMA and diglycidyl ether of bisphenol A was also crosslinked under the same conditions. The curing was studied with differential scanning calorimetry and monitored with Fourier transform infrared spectroscopy. The materials were characterized with differential scanning calorimetry, thermogravimetric analysis, and thermodynamomechanical analysis. The shrinkage effect on cationic crosslinking was assessed with gas pycnometry, and the flame‐retardant properties were determined with limiting oxygen index measurements. © 2006 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 45: 1980–1992, 2007.
Specific swelling behaviors of alkali‐metal poly(styrene sulfonate) gels in aqueous solvent mixtures
Authors: Fukunaga Yoko , Hayashi Mariko , Satoh Mitsuru
Published: April 2007

Counterion‐ and solvent‐specific swelling behaviors were investigated for alkali‐metal poly(styrene sulfonate) (PSSM) gels having different degrees of sulfonation in aqueous organic solvent mixtures [water plus methanol, ethanol, 2‐propyl alcohol, t‐butyl alcohol, dimethyl sulfoxide (DMSO), acetone, acetonitrile, tetrahydrofuran, or dioxane]. With an increasing organic solvent concentration, most gel systems, except for DMSO, showed a volume phase transition. The transition abruptly occurred without significant deswelling in the lower solvent concentration region. Such swelling behavior contrasted with that of other common charged gel systems, including alkali‐metal polyacrylate (PAAM) gels, which showed gel collapse after gradual deswelling with an increasing organic solvent concentration. The dielectric constant at the critical transition point (Dcr) for most mixed solvent systems decreased in the order of PSSK ≥ PSSCs ≥ PSSNa > PSSLi; that is, larger counterion systems were favorable for the transition. The counterion specificity also contrasted with our previous results for PAAM gels: PAANa > PAAK > PAALi ∼ PAACs. On the other hand, the solvent specificity for the PSSM gels was similar to that for the PAAM gels; the higher the dielectric constant was of the organic solvent, the higher the Dcr value was at which the transition occurred. These specificities were examined on the basis of the solvation properties of the counterions and polymer charged groups and the solvent properties such as the Gutmann–Mayer donor number and acceptor number. © 2007 Wiley Periodicals, Inc. J Polym Sci Part B: Polym Phys 45: 1166–1175, 2007