bluuebunny/crossref_metadata_2025 huggingface dataset:
Palynology of organic beds below Devensian glacigenic sediments at Pen‐y‐bryn, Gwynedd, North Wales
Authors: Chambers Frank M. , Addison Kenneth , Blackford Jeffrey J. , Edge Martin J.
Published: February 2007

Pollen diagrams from organic facies overlain by glacigenic sediments at Pen‐y‐bryn, North Wales (53°7′N, 4°16′W), suggest that it is the first locality in the British Isles to provide evidence for several Devensian interstadials prior to Devensian stadial glaciation(s). The evidence is not, however, unequivocal. At least two main episodes of organic sedimentation are indicated, separated by an interval of uncertain duration. One eposide records a Pinus‐Picea‐Betula forest. A second, possibly later, event, with tree pollen less than 10% of total land pollen (TLP), suggests a cool, largely unforested environment. A third episode, with tree pollen up to 25% of TLP, may be related to the latter or be of intermediate age, whereas a fourth and later episode of organic accumulation may be of reworked material. Radiocarbon dating of organic deposits and of a wood macrofossil enclosed in basal till is inconclusive, as is preliminary uranium‐series dating. The principal biogenic episodes may correlate with Oxygen Isotope Substages 5c and 5a, but as the pollen records reflect facies floras, the correlation remains tentative; it is also possible that other temperate periods are recorded. Further resolution of the chronostratigraphy is required to help clarify the problematic correlation of interstadial and stadial events in northwest Europe and to correlate more accurately the biogenic and glacigenic facies at Pen‐y‐bryn with their Pleistocene equivalents elsewhere.
Fluctuations of the South Patagonian Ice‐field during the last glaciation and the Holocene
Authors: Marden Christopher J. , Clapperton Chalmers M.
Published: February 2007

Mapping along a transect from the southeastern margin of the South Patagonian Ice‐field in Torres del Paine National Park (Chile) to the limits of fresh moraines of the last glacial cycle indentified eight glacier advances. The four younger ones have been dated by dendrochronology, tephrochronology and radiocarbon dating. Although the bases of 10 m deep bogs were sampled, close limiting radiocarbon dates were not obtained because bog formation in this rain‐shadow area appears not to have commenced until ca.12000 yr ago. The outermost Little Ice Age moraine formed during the seventeenth century and three inner ones were deposited around ad 1805, 1845 and after 1890. Densely vegetated older moraines contiguous with Little Ice Age deposits are possibly of late Holocene age. Tephra from the eruption of Reclus volcano at ca. 11 880 yr BP was incorporated by a readvance that deposited large multiple moraines 10–16 km from the modern ice‐front; the oldest basal peat found inside the moraine has been dated to ca. 9200 yr BP. These bracketing dates indicate that some eastern outlet glaciers of the ice‐field advanced at a time when some western tidewater outlet glaciers terminated inside their modern limits. This questions the view of J. H. Mercer and other that Patagonian glaciers did not readvance during the late‐glacial interval. A stadial event also occurred when the glaciers were some 18–20 km from their modern positions and is closely dated to ca. 11880 yr BP because Reclus pumice flushed down‐glacier forms thick upper beds in outwash deltas deposited in proglacial lakes.

The four older moraines pre‐date the late‐glacial eruption of Reclus but are not dated closely. Comparison of their spatial extent with well‐dated moraines in the Chilean Lakes Region suggests that they may mark advances culminating at ca. 14000 yr BP, ca. 20000 yr BP and earlier.
The intra‐Saalian interstadial floras of the Chojny Formation of Belchatów, central Poland
Authors: Krzyszkowski D. , Nita M.
Published: February 2007

The Saalian sequence of Belchatów, central Poland, is exceptionally thick and complete. Five tills, two from the older Saalian (Odranian, Drenthe) and three from the younger Saalian (Wartanian, Warthe), which are separated by the fluvial Chojny Formation, have been identified. The Saalian sequence at Bełchatów is underlain by Holsteinian and overlain by Eemian sequences, both palaeobotanically analysed. The Chojny Formation contains deposits of meandering (lower member) and braided (upper member) rivers, with occasional aeolian deposits. The lower member of the formation contains numerous organic layers. Pollen analysis indicates temperate (sub‐boreal) to cold (sub‐arctic) climatic conditions, with coniferous to mixed forests in the optimum phase of the interstadial. The interstadial floras of the Chojny Formation are interpreted as representing the intra‐Saalian Pilica Interstadial. Profiles from Belchatów are designated as the stratotype profiles of this substage. The data from Bełchatów show clearly that reforestation occurred between the major advances of the Saalian ice sheet, although only interstadial rank, not interglacial, may be inferred from the pollen data.
Late Weichselian to early Holocene litho‐ and biostratigraphy in the Devil's Hole area, central North Sea, and its relation to glacial isostasy
Authors: Ekman Sten S. R.
Published: February 2007

The 6‐m‐long British Geological Survey vibrocore 56+01/170 from the Devil's Hole area, central North Sea, comprises glaciomarine and marine sediments of Late Weichselian and Holocene age. Besides the foraminiferal, pollen and AMS 14C data presented in this study, amino acid and ostracod data exist for the core.

The accumulation of the sediment in the core began ca. 15.7 14C ka BP on an erosional surface on overconsolidated Saalian sediment. When the lower part of the core (facies 1) accumulated the core area is interpreted to have been around 40 m lower than present. This interpretation is based on two assumptions; first, that the sediment is now ca. 20 m above the global sea level at the time of deposition, and second, that the marine microfaunal content reflects a water depth of about 20 m at that time. Crustal downflexure caused by Late Weichselian glacial loading of the core area is considered as the most plausible explanation of this difference. Glacial overriding would also explain the overconsolidation of the underlying Saalian sediment, the erosional surface on the Saalian sediment and the absence of Weichselian sediment older than ca. 15.7 ka BP at the core site.

Indications of a regressional trend, with a minimum age of 12.1 ka BP, support the suggestion that the Devil's Hole area was glaciated during the Weichselian, as the fall in sea‐level at that time probably reflects local isostatic rebound.
Effects of plant species, stage of maturity and additive on the feeding value of whole‐crop cereal silage
Authors: Nadeau Elisabet
Published: February 2007

This experiment aimed to study the effects of plant species, stage of maturity, additive and their interactions on yield, chemical composition and fermentation characteristics of whole‐crop cereal silage. Barley, triticale, oats and spring wheat were harvested at the early milk stage or at the early dough stage of maturity in 2002 and 2003 with three field replicates of the plant species within each year. Proens™ (Perstorp Inc, Perstorp, Sweden), which contained 2/3 formic acid and 1/3 propionic acid, was applied at 4 L tonne−1 herbage and Lactisil 200® NB (Medipharm Inc, Kågeröd, Sweden), which contained Lactobacillus plantarum, Enterococcus faecium, Pediococcus acidilactici, Lactococcus lactis, cellulase and sodium benzoate, was applied at 200 000 colony‐forming units g−1 herbage, and both applications were compared to untreated silage. Unwilted herbage, chopped at 12 mm length, was ensiled in 4‐L laboratory silos for 90 days. Barley had more starch whereas triticale had more sugar and crude protein but less neutral detergent fibre than other species (P < 0.001). Barley and triticale had less acid detergent fibre and lignin but greater in vitro organic matter (OM) digestibility than oats and spring wheat (P < 0.0001). Averaged over maturity stages, wheat had a greater yield of digestible OM than barley and oats (P < 0.0001). Yield of digestible OM and concentration of starch increased whereas sugar concentration decreased with later maturity stage (P < 0.0001). Late harvest increased the risks for high levels of butyric acid in silage when no additives were used (P = 0.002). Additives resulted in increased lactic:acetic acid ratios but decreased protein degradation and DM losses (P < 0.0001). Acid treatment was more effective than inoculation to degrade starch and to decrease protein degradation and DM losses during ensiling (P < 0.0001). Harvest at the early milk stage of maturity resulted in more lactic acid and a lower pH than harvest at the early dough stage of maturity (P < 0.0001). When considering both maximal yield of digestible organic matter and good silage quality, triticale, wheat or barley silage harvested at the early dough stage of maturity and ensiled with acid or inoculant is suggested. Copyright © 2007 Society of Chemical Industry
Impact of sorghum processing on phytate, phenolic compounds and in vitro solubility of iron and zinc in thick porridges
Authors: Kayodé AP Polycarpe , Linnemann Anita R , Nout Martinus JR , Van Boekel Martinus AJS
Published: February 2007

This study focussed on the impact of process variables on levels of phytate and phenolic compounds, and in vitro solubility of iron (Fe) and zinc (Zn) in sorghum porridges, a major staple in semi‐arid tropics. The aim was to identify practices that enhance the mineral availability in this type of staple food. We studied the example of the West African porridge ‘dibou’ for which the processing methods involve grain cleaning, milling, sieving and cooking. Regional variations occur in the process, particularly in the cleaning which may be done wet or dry; sieving may be omitted in certain locations. Cleaning reduced the phytate content of the grain by 24–39%, while milling, sieving and cooking had no significant effect on phytate. Phenolic compounds measured as levels of reactive hydroxyl groups, remained constant after cleaning, milling and sieving, but significantly decreased by 38–65% after cooking. The Fe solubility tended to increase after cleaning but was drastically reduced due to cooking, and so was the soluble Zn. Levels of total phenolic compounds highly correlated with the Fe and Zn solubility (r2 = 0.73 and 0.82, respectively). Phenolic reaction products formed during the cooking process are presumably related with the extensive browning phenomenon observed in the dibou porridge, and with the reduction observed in Fe and Zn solubility. Copyright © 2007 Society of Chemical Industry
Physical properties of some intensively cultivated soils of Ireland amended with spent mushroom compost
Authors: Curtin J. S. , Mullen G. J.
Published: February 2007

In this paper, spent mushroom compost (SMC), a by‐product of the mushroom industry, is proposed as a suitable organic amendment for soil structure restoration. A 4‐month incubation pot trial was conducted in which fresh and composted SMC was amended at three different rates (50, 100 and 200 t ha−1) to a range of structurally degraded tillage soils (n = 10). Soil OC content and aggregate stability as determined by the three disrupting tests of the Le Bissonnais method (fast‐wetting, slow‐wetting and mechanical breakdown) were investigated. Applications of 50, 100 and 200 t ha−1 fresh SMC increased the OC content by 2·71 per cent, 2·69 per cent and 2·49 per cent respectively, while amendments of composted SMC increased the OC content by 3·28 per cent, 2·94 per cent and 2·87 per cent for each application rate, respectively. The effect of SMC on aggregate stability was generally positive and statistically significant in most soils. However, in soils 3 and 4 an application rate of 200 t ha−1 SMC decreased the aggregate stability, on average, by 15 per cent, in comparison to the control, for the fast‐wetting test. Aggregate stability was strongly controlled by the inherent OC content of the study soils; that is, the OC content prior to SMC addition. A positive correlation coefficient was also evident for the dithionite‐extractable iron, most pronounced for slow‐wetting and mechanical breakdown treatments (r = 0·844 and r = 0·817 respectively). It is clear from this research that SMC amendments have the capacity to improve soil structural stability. Copyright © 2007 John Wiley & Sons, Ltd.
Synthesis and Properties of Novel Fluorinated Poly(phenylene‐co‐imide)s
Authors: Li Wenmu , Zhang Suobo , Chen Guang , Zhang Quanyuan
Published: February 2007

A new class of high‐performance materials, fluorinated poly(phenylene‐co‐imide)s, were prepared by Ni(0)‐catalytic coupling of 2,5‐dichlorobenzophenone with fluorinated dichlorophthalimide. The synthesized copolymers have high molecular weights ($\overline M _{\rm w}$ = 5.74 × 104–17.3 × 104 g · mol−1), and a combination of desirable properties such as high solubility in common organic solvent, film‐forming ability, and excellent mechanical properties. The glass transition temperature (Tgs) of the copolymers was readily tuned to be between 219 and 354 °C via systematic variation of the ratio of the two comonomers. The tough polymer films, obtained by casting from solution, had tensile strength, elongation at break, and tensile modulus values in the range of 66.7–266 MPa, 2.7–13.5%, and 3.13–4.09 GPa, respectively. The oxygen permeability coefficients ($P_{{\rm O}_{\rm 2} }$) and permeability selectivity of oxygen to nitrogen ($P_{{\rm O}_{\rm 2} } /P_{{\rm N}_{\rm 2} }$) of these copolymer membranes were in the range of 0.78–3.01 barrer [1 barrer = 10−10 cm3 (STP) cm/(cm2 · s · cmHg)] and 5.09–6.25, respectively. Consequently, these materials have shown promise as engineering plastics and gas‐separation membrane materials.

magnified image
Synthesis, Characterization, and Properties Evaluation of Poly[(N‐isopropylacrylamide)‐co‐ester]s
Authors: Ren Liqun , Agarwal Seema
Published: February 2007

Copolymerization behavior of cyclic ketene acetal like 5,6‐benzo‐2‐methylene‐1,3‐dioxepane (BMDO) with N‐isopropylacrylamide (NIPAAm) is studied by free radical polymerization. Structural characterization is done using 1D and 2D NMR techniques. Under optimized reaction conditions, quantitative ring‐opening of BMDO took place during the copolymerizations leading to the formation of poly(NIPAAm‐co‐ester)s. The reactivity ratios for the copolymerization of BMDO and NIPAAm were determined using Kelen–Tüdõs method and found to be rBMDO = 0.11 and rNIPAAm = 7.31. Copolymers with low mol‐% of BMDO were found to be soluble in water and also showed hydrolytic degradability. Different degradable copolymers could be generated with varied glass transition temperatures and lower critical solution temperatures (LCSTs).

magnified image
Study of Novel PU‐Type Polymeric Photoinitiators Comprising of Side‐Chain Benzophenone and Coinitiator Amine: Effect of Macromolecular Structure on Photopolymerization
Authors: Wei Jun , Wang Hongyu , Jiang Xuesong , Yin Jie
Published: February 2007

Three PU‐type polymeric photoinitiators containing side‐chain benzophenone and coinitiator amine, PUSBA‐h, PUSBA‐t and PUSBA‐i, were synthesized via polycondensation of 3,5‐diamino‐4′‐thiophenylbenzophenone, different diisocyanates and N‐methyldiethanolamine. FT‐IR, 1H NMR and GPC analyses confirm the structures of all polymers. The UV‐vis spectra of polymeric photoinitiators are similar and all exhibit the maximal absorption near 320 nm. ESR spectra show PUSBA‐h and PUSBA‐t can efficiently generate free radicals. The photopolymerization of trimethylolpropane triacrylate and the PU prepolymer, initiated by these polymeric photoinitiators, was studied by photo‐DSC. The results indicate that the macromolecular structure has an important effect on photopolymerization, and different photoinitiators exhibit different behavior towards different monomers: PUSBA‐t is the most efficient for TMPTA and PUSBA‐h is the most efficient for PU prepolymer. The final conversion for the photopolymerization of PU prepolymer initiated by PUSBA‐h is greater than 97%.

magnified image
Predisposing factors of restless legs syndrome in pregnancy
Authors: Tunç Tuğba , Karadağ Yeşim Sücüllü , Doğulu Funda , İnan Levent E.
Published: February 2007

The occurrence of restless legs syndrome in pregnancy is well known. However, the mechanism of this association is unclear. In this study, we aimed to identify the factors that predispose women to have restless legs syndrome during pregnancy. A total of 146 pregnant women were included in the study. Patients were asked questions regarding demographic characteristics, complications of pregnancy, medical therapy (vitamin and iron intake), sleep disorders, muscle cramps, and excessive daytime sleepiness. Electroneurography, routine blood biochemistry tests, complete blood count, and thyroid function tests were performed and vitamin B12, folic acid, serum iron, iron‐binding capacity, ferritin, iron saturation, prolactin, estradiol, and progesterone were measured. Of the participants, 38 were diagnosed as having restless legs syndrome. In women with restless legs syndrome, additional medical problems, night cramps, and excessive daytime sleepiness were more frequent. In women without restless legs syndrome, serum hemoglobin levels were significantly higher and the use of supplemental iron or vitamins was greater. Among the women with restless legs syndrome, progesterone levels were slightly higher but this difference was not statistically significant. In summary, in this study, lower hemoglobin levels and supplementation deficits of iron and vitamins were found be the risk factors for restless legs syndrome in pregnancy. © 2007 Movement Disorder Society
Continuous locked suture technique for arterial anastomosis in rat small bowel transplantation
Authors: Wang Jian , Ma Hao , Zhang Haiyun , Lu Bin , Wang Jinhua , Wang Zhenlong , Li Yousheng , Li Jieshou
Published: February 2007

Continuous locked suture technique in arterial anastomosis was used in a rat heterotopic small bowel transplantation model. Blood loss, time consumption and success rate of the technique, as well as long‐term blood flow and histological changes of arterial anastomosis and intestinal graft were compared with the traditional simple continuous suture technique. The results showed that the time consumption was similar between the two techniques while the continuous locked suture technique had a higher success rate (P = 0.016) and was more secure than the simple continuous suture technique. Moreover, it provided a higher long‐term blood flow. Under light microscopy and electron scanning microscopy, the anastomosis of continuous locked suture technique showed significantly less stenosis than those of simple continuous suture technique. No difference was found between the two techniques considering the graft intestinal histological changes. In conclusion, the continuous locked suture technique was a more superior technique than simple continuous suture technique in arterial end‐to‐side anastomosis considering long‐term hemodynamics. © 2007 Wiley‐Liss, Inc. Microsurgery, 2007.
Enthalpy relaxation in bisphenol‐A polycarbonate/poly(methyl methacrylate) blends
Authors: Penco Maurizio , Sartore Luciana , Sciucca Stefania Della
Published: February 2007

Bisphenol‐A polycarbonate (PC)/poly(methyl methacrylate) (PMMA) blends (PC/PMMA) were prepared by melt mixing with and without a trans‐esterification catalyst (tetrabutylammoniun tetraphenylborate), which is able to promote inter‐exchange reactions between PC and PMMA. Evidences of the ester–ester exchange reaction taking place were pointed out via Fourier Transform Infra‐Red and size exclusion chromatography analyses. A series of enthalpy relaxation measurements were carried out for the pure polymers and for blends thereof. The data were analyzed on the basis of the Tool–Narayanaswamy–Moynihan/Kohlraush–Williams–Watts model. This model characterizes the structural relaxation in the glass transition region by means of four parameters: the apparent activation energy (Δh*), the nonlinearity (x), the nonexponentiality (β), and the pre‐exponential factor (τ0). The apparent activation energy can be determined from the cooling rate dependence of the fictive temperature (Tf) measured using DSC. Δh* values of homogeneous blend and of the starting polymers were determined in this way, while an estimation of x, β and τ0 was proposed. Comparisons were made between a single glass transition temperature PC/PMMA blend and homopolymers data. The experimental values of Δh* suggest that the degree of cooperativity decreases on going from the starting polymers to the blend. POLYM. ENG. SCI., 47:218–224, 2007. © 2007 Society of Plastics Engineers.
Linear polymers with sulfur in the main chain. IV. Synthesis of thermotropic liquid‐crystalline polythioesters based on 4,4′‐biphenyldithiol with excellent adhesive properties
Authors: Hirano Hiroshi , Kadota Joji , Agari Yasuyuki , Harada Toshihiko , Tanaka Mitsuaki , Hasegawa Kiichi
Published: February 2007

A series of sulfur‐containing linear polythioesters were synthesized from 4,4′‐biphenyldithiol (BPT) and bifunctionally aliphatic acyl dichlorides (ACs) by means of polycondensation. Polycondensations of BPT with azelaoyl chloride or sebacoyl chloride chosen as a model reaction system were investigated in several solvents by solution polycondensation, to find an optimal solvent to achieve high molecular weight and quantitative yield. Thus, all the polythioesters from BPT and AC (methylene number of 3–10) were synthesized in chloroform and their structures were confirmed by 1H‐NMR and Fourier transform infrared spectrophotometer. They were also evaluated by thermogravimetry and differential scanning calorimeter (DSC). Almost all of the BPT, polythioesters exhibited two distinct exothermic and endothermic peaks on first cooling and second heating in their DSC curves, respectively. Polarized microscope (PLM) observation clarified that the higher transition temperatures were isotropic temperatures (Tis). The odd–even effect between Ti and the methylene number was observed in these BPT polythioesters. Furthermore, almost all of the polythioesters showed thermotropic liquid‐crystalline behavior, as evidenced by a PLM observation. To know the effect of introduction of sulfur on adhesive properties of the polythioester/copper junction, a single lap shear test was carried out in comparison with corresponding 4,4′‐biphenyldiol (BPH) polyesters derived from BPH and ACs. It was clarified that the BPT polythioesters have greatly higher adhesive strengths in comparison with the BPH polyesters. POLYM. ENG. SCI., 47:262–269, 2007. © 2007 Society of Plastics Engineers.
Effect of molecular structure on extrudate swell behavior for different thermoplastic melts in an electro‐magnetized die
Authors: Sombatsompop N. , Uawongsuwan P. , Chaochanchaikul K.
Published: February 2007

The extrudate swell ratio of five different thermoplastic melts flowing in a constant shear rate rheometer having a capillary die with and without application of magnetic field was studied. The effects of the magnetic flux direction and density, die temperature, and wall shear rate on the extrudate swell and flow properties were investigated. The experimental results suggested that an increasing wall shear rate increased the swelling ratio for the polystyrene (PS), LLDPE, and PVC melts, but the opposite effect was observed for the ABS and PC melts. The extrudate swell ratio for the PS, ABS, PC, and LLDPE melts decreased with increasing die temperature, the effect being reversed for the PVC melt. Thermoplastic melts having high benzene content in the side‐chain and exhibiting anisotropic character were apparently affected by the magnetic field, the extrudate swell ratio increasing with magnetic flux density. The effect of the magnetic field on the extrudate swell ratio decreased in the order of PS → ABS → PC. The extrudate swell ratio for the co‐parallel magnetic field system was slightly higher than that for the counter‐parallel magnetic field system at a high magnetic flux density. POLYM. ENG. SCI., 47:270–280, 2007. © 2007 Society of Plastics Engineers.
Flexural properties of surface reinforced wood/plastic deck board
Authors: Jiang Long , Wolcott Michael P. , Zhang Jinwen , Englund Karl
Published: February 2007

Decking and railing is the largest and fastest growing market for wood–plastic composites (WPCs). Despite WPC's advantages in comparison to lumber, its modulus and creep resistance need to be further improved for demanding structural applications. In this study, WPC deck boards were reinforced by the composite sheets made of commingled glass and polypropylene fiber. Various reinforcement arrangements were carried out to identify the optimal one. Scanning electron microscopy revealed good bonding at the reinforcement/WPC interface. All reinforced samples exhibited considerably increased modulus of rupture, modulus of elasticity, and strain at break. The creep resistance of the reinforced WPC boards was also greatly improved. Creep strain was simulated with Findley's model. Master curves of creep compliance were generated by time–temperature–stress superposition principle. The Prony series was found to be the analytical expression of the master curves with acceptable accuracy. With improved mechanical properties, the reinforced WPC board can be used in more demanding applications. POLYM. ENG. SCI., 47:281–288, 2007. © 2007 Society of Plastics Engineers.
Preform shape and operating condition optimization for the stretch blow molding process
Authors: Thibault F. , Malo A. , Lanctot B. , Diraddo R.
Published: February 2007

In this work, a new design approach was developed to automatically and consecutively predict optimal preform geometry and optimal operating conditions for the stretch blow molding process. The numerical approach combines a constrained gradient‐based optimization algorithm that iterates automatically over predictive finite element software. The strategy allows for targeting a specified container thickness distribution by manipulating consecutively the preform geometry (thickness and shape) and the operating parameters subject to process and design constraints. For the preform shape optimization, the preform geometry is mathematically parameterized for simplified treatment and the corresponding sensitivities are evaluated using a finite difference technique. A finite difference technique is also employed for the operating condition optimization. The constrained optimization algorithms are solved via the use of the sequential quadratic programming method that updates the design variables accordingly. Predicted optimization results obtained on an industrial case are presented and discussed to assess the validity when compared to experimental results and the robustness of the proposed approach. POLYM. ENG. SCI., 47:289–301, 2007. © 2007 Society of Plastics Engineers.
Polybutadiene rubber/organoclay nanocomposites: Effect of organoclay with various modifier concentrations on the vulcanization behavior and mechanical properties
Authors: Kim Min‐Su , Kim Gue‐Hyun , Chowdhury Subhendu Ray
Published: February 2007

It has been reported that the cure time t90, scorch time t2, and their difference (t90−t2) of Polybutadiene rubber (BR)/organoclay nanocomposites were much reduced over those of BR. This effect can be attributed to the ammonium groups in the organoclay. The possible formation of a Zn complex in which sulfur and ammonium modifier participate may facilitate the formation of crosslinks. If this assumption is true, it is expected that the organoclay with higher ammonium modifier concentration will give larger torque difference and faster vulcanization rate to the BR/organoclay nanocomposites. The effect of organoclay with different modifier concentration on the vulcanization behavior and mechanical properties of BR/organoclay hybrid was investigated in this study. As expected, the order of the torque difference was BR/Cloisite 15A > BR/Cloisite 10A > BR/Cloisite 20A > BR/Cloisite 25A > BR/Cloisite 30B > BR/Cloisite Na+, and the order of vulcanization rate also showed similar trends. The organoclay with higher modifier concentration gave larger torque difference and faster vulcanization rate to the BR/organoclay nanocomposites. POLYM. ENG. SCI., 47:308–313, 2007. © 2007 Society of Plastics Engineers.
Mechanical properties of methacylic acid/acrylonitrile copolymer foam
Authors: Tie‐Min Liu , Guang‐Cheng Zhang , Ting Chen , Xue‐Tao Shi , Cui Zhang
Published: February 2007

To gain a foam plastic with excellent mechanical properties, tensile mechanical properties of methacylic acid/acrylonitrile (MAA/AN) copolymer and the corresponding foam microstructure were studied, and furthermore effects of the density, heat treatment, and crosslinking agent on foam mechanical properties were also discussed in this paper. The results reveal that the tensile strength and modulus of the copolymer after heat treatment are 64 MPa and 4.2 GPa respectively, when compared with 58 MPa and 3.8 GPa before heat treatment respectively. Foam mechanical properties are enhanced with the rise of the density, and the values tested accords with the theoretical values of pentagonal dodecahedron mechanical model basically. Foam mechanical properties are enhanced via heat treatment, and the same result can be observed after using the crosslinking agent (acrylamide) too. All these results indicate that MAA/AN copolymer foam possesses excellent mechanical properties, such as its tensile, 10% compressive and shear strength are 1.3, 0.8, and 0.8 MPa respectively when the foam density is 52 kg/m3. POLYM. ENG. SCI., 47:314–322, 2007. © 2007 Society of Plastics Engineers.
Poly(butylene terephthalate)/poly(ε‐caprolactone) blends: Miscibility and thermal and mechanical properties
Authors: Di Lorenzo Maria Laura , Pietra Paola La , Errico Maria Emanuela , Righetti Maria Cristina , Angiuli Marco
Published: February 2007

Miscibility and thermal and mechanical properties of poly(butylene terephthalate) (PBT) blends with poly(ε‐caprolactone) (PCL) were analyzed as a function of the molecular mass of PCL. It was found that the components are miscible when oligomeric PCL is blended with PBT, probably due to favorable interactions between OH end groups of poly(ε‐caprolactone) and ester groups of PBT. In the blends containing high molar mass PCL, the concentration of hydroxyl end groups is lower, allowing only partial miscibility of the components. The resulting materials display good mechanical properties, with enhanced performance at rupture compared to plain PBT. POLYM. ENG. SCI., 47:323–329, 2007. © 2007 Society of Plastics Engineers.
‘Bricks and mortar’ nanoparticle self‐assembly using polymers
Authors: Arumugam Palaniappan , Xu Hao , Srivastava Sudhanshu , Rotello Vincent M
Published: February 2007

Developments in self‐assembly methods allow access to hierarchical materials featuring a wide range of functionality and applications. Polymer‐based self‐assembly of nanoparticles opens up new avenues for the fabrication of highly structured nanocomposites that can serve as bridges between ‘bottom‐up’ and ‘top‐down’ methods. Of various interactions leading to self‐assembly of nanocomposites, hydrogen bonding and electrostatic interactions are commonly utilized. In this review, we illustrate the design and subsequent property tuning of various self‐assembled nanocomposite materials that were developed based on these interactions. Copyright © 2007 Society of Chemical Industry
Synthesis and characterization of new nanocomposites based on epoxy resins and organophilic clays
Authors: Gârea Sorina‐Alexandra , Iovu Horia , Stoleriu Stefania , Voicu Georgeta
Published: February 2007

Epoxy–clay nanocomposites were synthesized using different types of modified montmorillonite, either with a classic quaternary ammonium salt or with protonated adducts synthesized by reacting resorcinol diglycidyl ether with monoamines (benzylamine or cyclohexylamine). The chemical structure was investigated using Fourier transform infrared and 1H NMR spectrometry. The nanocomposite structures were confirmed using X‐ray diffraction analysis and transmission electron microscopy. The influence of the montmorillonite modifier on the glass transition temperature of the cured composites was studied using dynamic mechanical analysis. Copyright © 2007 Society of Chemical Industry
Is the intrinsic disorder of proteins the cause of the scale‐free architecture of protein–protein interaction networks?
Authors: Schnell Santiago , Fortunato Santo , Roy Sourav
Published: February 2007

In protein–protein interaction (PPI) networks certain topological properties appear to be recurrent: network maps are considered scale‐free. It is possible that this topology is reflected in the protein structure. In this paper, we investigate the role of protein disorder in the network topology. We find that the disorder of a protein (or of its neighbors) is independent of its number of PPIs. This result suggests that protein disorder does not play a role in the scale‐free architecture of protein networks.
Proteomic analysis of the oxidative stress response inCandida albicans
Authors: Kusch Harald , Engelmann Susanne , Albrecht Dirk , Morschhäuser Joachim , Hecker Michael
Published: February 2007

An efficient oxidative stress response (OSR) is important for the facultative pathogenic yeastCandida albicansto survive within the human host. We used a large scale 2‐D protein gel electrophoresis approach to analyze the stress response mechanisms ofC. albicansafter treatment with hydrogen peroxide and the thiol oxidizing agent, diamide. Quantitation ofin vivoprotein synthesis after pulse labeling of the proteins with radioactiveL‐[35S]‐methionine resulted in characteristic proteome signatures for hydrogen peroxide and diamide with significant overlap of 21 up‐regulated proteins for both stressors. Among the induced proteins were enzymes with known antioxidant functions like catalase or thioredoxin reductase and a set of oxidoreductases. 2‐D gel analysis of mutants in theCAP1gene revealed that the synthesis of 12 proteins is controlled by the oxidative stress regulator Cap1p. Stressing its importance for theC. albicansOSR, all 12 proteins were also induced after oxidative challenge by hydrogen peroxide or diamide.
Kinetics of hexene‐1 polymerization using [(N,N′‐diisopropylbenzene)‐2,3‐(1,8‐napthyl)‐1,4‐diazabutadiene] dibromonickel/methylaluminoxane catalyst system
Authors: Subramanyam Ummadisetty , Sivaram Swaminathan
Published: February 2007

Kinetics of hexene‐1 polymerization was investigated using [(N,N′‐diisopropylbenzene)2,3‐(1,8‐napthly)‐1,4‐diazabutadiene]dibromonickel/methylaluminoxane catalyst. Experiments were performed at varying catalyst and monomer concentrations in the temperature range of −10 to 35 °C. First order time‐conversion plot shows a downward curvature at temperatures of 20 °C and 35 °C indicating the presence of finite termination reactions. A nonlinear plot of degree of polymerization (Pn) with respect to conversion indicates occurrence of transfer reactions and slow initiation. The experimental molar masses are higher than predicted, which implies that a fraction of catalyst species could not be activated or is deactivated at the early stages of the reactions. The efficiency of the catalyst (Cateff) varies from 0.77 to 0.89. The observed polydispersity of the poly(hexene‐1) s is in the range of 1.18–1.48. The reaction order was found to be 1.11 with respect to catalyst. The Arrhenius plot obtained using the overall propagation rate constant, kp, at five different temperatures (−10, 0, 10, 20, and 35 °C) was found to be linear with an activation energy, Ea = 4.3 kcal/mol. Based on the results presented it is concluded that the polymerization of hexene‐1 under the above‐mentioned conditions shows significant deviation from ideal “living” behavior. © 2006 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 45: 1093–1100, 2007
Dynamical behavior of the vascular endothelial growth factor: Biological implications
Authors: Horta Bruno A. C. , Cirino José J. V. , de Alencastro Ricardo B.
Published: February 2007

The vascular endothelial growth factor (VEGF) seems to be the most important regulator of physiological and pathological angiogenesis, being, for this reason, a favorite target for therapies against angiogenesis‐related diseases. VEGF is a homodimer in which the monomers are formed by β‐strands interconnected on the poles by three loops. A recent work showed that an intimate relationship between loops‐1 and ‐3 is required for high affinity binding to the receptors (Kiba et al., J Biol Chem 2003;278:13453–13461). In this work, we report the results of a 10‐ns molecular dynamics simulation of VEGF. We analyzed the dynamical behavior of the protein (using a dynamical cross‐correlation map) and found that it is governed by a high degree of correlation between the motions of the loops. We also performed a principal component analysis and found an overall motion in which the opposite poles are projected against each other, just like the movement of the wings of a butterfly. From the biological point of view, it is likely that this motion would facilitate receptor binding since VEGF must enter a restricted cavity formed by the two subunits of the receptor. Proteins 2007. © 2007 Wiley‐Liss, Inc.
Predicting disulfide connectivity patterns
Authors: Lu Chih‐Hao , Chen Yu‐Ching , Yu Chin‐Sheng , Hwang Jenn‐Kang
Published: February 2007

Disulfide bonds play an important role in stabilizing protein structure and regulating protein function. Therefore, the ability to infer disulfide connectivity from protein sequences will be valuable in structural modeling and functional analysis. However, to predict disulfide connectivity directly from sequences presents a challenge to computational biologists due to the nonlocal nature of disulfide bonds, i.e., the close spatial proximity of the cysteine pair that forms the disulfide bond does not necessarily imply the short sequence separation of the cysteine residues. Recently, Chen and Hwang (Proteins 2005;61:507–512) treated this problem as a multiple class classification by defining each distinct disulfide pattern as a class. They used multiple support vector machines based on a variety of sequence features to predict the disulfide patterns. Their results compare favorably with those in the literature for a benchmark dataset sharing less than 30% sequence identity. However, since the number of disulfide patterns grows rapidly when the number of disulfide bonds increases, their method performs unsatisfactorily for the cases of large number of disulfide bonds. In this work, we propose a novel method to represent disulfide connectivity in terms of cysteine pairs, instead of disulfide patterns. Since the number of bonding states of the cysteine pairs is independent of that of disulfide bonds, the problem of class explosion is avoided. The bonding states of the cysteine pairs are predicted using the support vector machines together with the genetic algorithm optimization for feature selection. The complete disulfide patterns are then determined from the connectivity matrices that are constructed from the predicted bonding states of the cysteine pairs. Our approach outperforms the current approaches in the literature. Proteins 2007. © 2007 Wiley‐Liss, Inc.
Wind structure over the sea
Authors: Westwater F. L.
Published: February 2007

A comparison between theory and observation is made for he problem of veer of wind with height over the sea. Observations made in H.M.ships, notably aircraft carriers, which may be assumed to be at least as accurate as shore based observations are included. Frequency diagrams for the angle of veer show peculiar features which are absent from land observations. It is suggested that the motion of the sea surface mobility is discussed. for this, and the general effect of surface mobility is discussed.

In view of the uniformity of the surface and the absence of marked thermal effects, one would expect good agreement between theory and observation in the case of wind structure in the friction layer over the sea. unfortunately the agreement is, if anything, less good than over the land, and the sea observations show certain interesting features which are absent in the case of land observations.

It has been the practice in the past to attribute much of the disparity between theory and observation over the sea to observational difficulties. The difficulty of making pilot balloon observations “from a moving steamer” is mentioned by Rossby, and others seek refuge in the fact that wind directions at the surface are only measured to the nearest compass point. The probable validity of these objections in the past is not denied, but the recent rapid development of the Naval meteorological Service, and the growing volume of sea observations of a high standard of accuracy collected by trained observers calls for a review of the situation. Surface winds in H.M. ships are no longer measured n points, but in degrees, allowance for the relative motion of the ship being made automatically. An occasion when great accuracy in measurement of wind direction is possible is when aircraft are being flown off or on to the deck of a carrier. Furthermore pilot balloon observations are not, in general, more difficult to carry out on board than on shore. Ships of the size of aircraft carriers do not move a great deal in winds of less than force six, and the instruments available for following the balloon are superior to those used on shore, although they cannot be described here for obvious reasons. It may be taken as certain that observations taken on one of the larger carriers are at least as accurate as any taken ashore provided the wind is of force five or less. In the discussion below, observations from carriers will be given, as well be given, as well as those from merchant ships.
The ozone content of surface air and its relation to some meteorological conditions
Authors: Glückauf E.
Published: February 2007

The variations of the ozone content of surface air during depressions have been investigated. Three definite conditions were found to occur, apparently without exception.

A drop in the ozone content is found up to 300 miles in advance of warm fronts, with high values of ozone after their passage.

An occluded front of the warm front type behaved in exactly the same way as a front with a warm sector.

A drop in the ozone content is found after the passage of backbent occlusions, persisting until the front has moved on up to 200 miles, after which the ozone returns to its normal concentration.

This seems to indicate that the observed change under these conditions in the ozone content is due to the increased stability of air not at the surface but at the upper warm front inversion. This would prevent the ozone (constantly destroyed near the ground) from being restored by turbulent interchange with air from greater heights.
Structural analysis of O‐glycopeptides employing negative‐ and positive‐ion multi‐stage mass spectra obtained by collision‐induced and electron‐capture dissociations in linear ion trap time‐of‐flight mass spectrometry
Authors: Deguchi Kisaburo , Ito Hiroki , Baba Takashi , Hirabayashi Atsumu , Nakagawa Hiroaki , Fumoto Masataka , Hinou Hiroshi , Nishimura Shin‐Ichiro
Published: February 2007

Structural analyses of various glycans attached to proteins and peptides are highly desirable for elucidating their biological roles. An approach based on mass spectrometry (MS) combining both collision‐induced dissociation (CID) and electron‐capture dissociation (ECD) in the positive‐ and negative‐ion modes has been proposed as a simple and direct method of assigning an O‐glycan without releasing it from the peptide and of determining the amino acid sequence of the peptide and glycosylation site. The instrument used is an electrospray ionization (ESI) linear ion trap (LIT) time‐of‐flight (TOF) mass spectrometer with tandem LITs for CID by He gas and ECD. The proposed approach was tested with two synthetic O‐glycopeptides binding a sialyl Lewis x (sLex) oligosaccharide and a 3′‐sialyl N‐acetyllactosamine (3′‐SLN) on a serine (S) residue. In the negative‐ion mode, the CID MS2 spectra of O‐glycopeptides showed a relatively abundant glycoside‐bond cleavage between the core N‐acetylglucosamine (GlcNAc) and serine (S) that yields deprotonated C3‐type fragment ions of O‐glycan and deprotonated Z0‐type peptide ions. The structure of the sLex (3′‐SLN) oligosaccharide was simply assigned by comparing the CID MS3 spectrum derived from the C3‐type fragment ion with the CID MS2 spectra of the sLex and sLea (3′‐ and 6′‐SLN) standards (i.e., negative‐ion MSn spectral matching). The amino acid sequence of the peptide including the glycosylation site was determined from the ECD MS2 spectrum in the positive‐ion mode. Copyright © 2007 John Wiley & Sons, Ltd.
Concurrent quantification of light and heavy sulphur volatiles in wine by headspace solid‐phase microextraction coupled with gas chromatography/mass spectrometry
Authors: Fedrizzi Bruno , Magno Franco , Moser Sergio , Nicolini Giorgio , Versini Giuseppe
Published: February 2007

A new method based on headspace solid‐phase microextraction coupled with gas chromatography/mass spectrometry (HS‐SPME‐GC/MS) to analyse 13 light and heavy volatile sulphur compounds in the same run was established. For the successful application of the procedure, various adsorption process parameters were optimised. In particular the nature of the adsorptive phase, the temperature, the ionic strength of the sample solutions and the equilibration time were considered. The best extraction conditions, in terms of the maximum signal obtainable for each compound, were obtained with a carboxen‐polydimethylsiloxane‐divinylbenzene (CAR‐PDMS‐DVB) 2 cm long coating fibre. The choice of suitable internal standards and the matrix effect were studied and the proposed method was validated by determining linearity, precision and accuracy, evaluating the critical, detection and quantification limits. This method is fast, sensitive and precise and easy to transfer to wine quality control. Finally, the proposed method was applied to the determination of the aforementioned sulphur compounds in 32 red and white wines. Copyright © 2007 John Wiley & Sons, Ltd.
Evaluation of sample fractionation using micro‐scale liquid‐phase isoelectric focusing on mass spectrometric identification and quantitation of proteins in a SILAC experiment
Authors: Thorsell Annika , Portelius Erik , Blennow Kaj , Westman‐Brinkmalm Ann
Published: February 2007

Mass spectrometric methods based on stable isotopes have shown great promise for identification and quantitation of complex mixtures. Stable isotope labelling by amino acids in cell culture (SILAC) is a straightforward and accurate procedure for quantitation of proteins from cell lines, that are cultured in media containing the natural amino acid or its isotopically labelled analogue, giving rise to either ‘light’ or ‘heavy’ proteins. The two cell populations are pooled and treated as a single sample, which allows the use of various protein purification methods without introducing errors into the quantitative analysis. The quantitation of the proteins is based on the intensities of the light and heavy peptides. The increased number of peptides in a quantitative experiment arising from peptide pairs implies that prefractionation is critical prior to liquid chromatography/mass spectrometric (LC/MS) analysis to minimise signal suppression effects and errors in measurements of the intensity ratios. In this study, the effect of a prefractionation step on identification and quantitation of proteins in a SILAC experiment was evaluated. We show that micro‐scale liquid‐phase isoelectric focusing in the Micro Rotofor separates proteins into well‐defined fractions and reduces the sample complexity. Furthermore, the fractionation enhanced the number of identified proteins and improved their quantitation. Copyright © 2007 John Wiley & Sons, Ltd.