bluuebunny/crossref_metadata_2025_split huggingface dataset:
Late Quaternary palaeoecological and palaeoclimatological reconstruction in the Gutaiului Mountains, northwest Romania
Authors: Feurdean Angelica , Bennike Ole 
Published: October 2004

AbstractMacrofossil, pollen, lithostratigraphy, mineral magnetic measurements (SIRM and magnetic susceptibility), loss‐on‐ignition, and AMS radiocarbon dating on sediments from two former crater lakes, situated at moderate altitudes in the Gutaiului Mountains of northwest Romania, allow reconstruction of Late Quaternary climate and environment. Shrubs and herbs with steppe and montane affinities along with stands of Betula and Pinus, colonised the surroundings of the sites prior to 14 700 cal. yr BP and the inferred climatic conditions were cold and dry. The gradual transition to open Pinus–Betula forests, slightly higher lake water temperatures, and higher lake productivity, indicate more stable environmental conditions between 14 700 and 14 100 cal. yr BP. This development was interrupted by cooler and drier climatic conditions between 14 100 and 13 800 cal. yr BP, as inferred from a reduction of open forests to patches, or stands, of Pinus, Betula, Larix, Salix and Populus. The expansion of a denser boreal forest, dominated by Picea, but including Pinus, Larix, Betula, Salix, and Ulmus started at 13 800 cal. yr BP, although the forest density seems to have been reduced between 13 400 and 13 200 cal. yr BP. Air temperature and moisture availability gradually increased, but a change towards drier conditions is seen at 13 400 cal. yr BP. A distinct decrease in temperature and humidity between 12 900 and 11 500 cal. yr BP led to a return of open vegetation, with patches of Betula, Larix, Salix, Pinus and Alnus and individuals of Picea. Macrofossils and pollen of aquatic plants indicate rising lake water temperatures and increased aquatic productivity already by ca. 11 800 cal. yr BP, 300 years earlier than documented by the terrestrial plant communities. At the onset of the Holocene, 11 500 cal. yr BP, forests dominated by Betula, Pinus and Larix expanded and were followed by dense Ulmus forests with Picea, Betula and Pinus at 11 250 cal. yr BP. Larix pollen was not found, but macrofossil evidence indicates that Larix was an important forest constituent at the onset of the Holocene. Moister conditions were followed by a dry period starting about 10 600 cal. yr BP, which was more pronounced between 8600 and 8200 cal. yr BP, as inferred from aquatic macrofossils. The maximum expansion of Tilia, Quercus, Fraxinus and Acer between 10 700 and 8600 cal. yr BP may reflect a more continental climate. A drier and/or cooler climate could have been responsible for the late expansion (10 300 cal. yr BP) and late maximum (9300 cal. yr BP) of Corylus. Increased water stress, and possibly cooler conditions around 8600 cal. yr BP, may have caused a reduction of Ulmus, Tilia, Quercus and Fraxinus. After 8200 cal. yr BP moisture increased and the forests included Picea, Tilia, Quercus and Fraxinus. Copyright © 2004 John Wiley & Sons, Ltd.
High‐resolution record of environmental changes and tephrochronological markers of the Last Glacial–Holocene transition at Lake Lautrey (Jura, France)
Authors: Vannière Boris , Bossuet Gilles , Walter‐Simonnet Anne‐Véronique , Ruffaldi Pascale , Adatte Thierry , Rossy Michel , Magny Michel 
Published: October 2004

AbstractThis paper presents the results of a multiproxy investigation including volume magnetic susceptibility (κ), mineral and pollen analyses of Late Glacial sediments from Lake Lautrey (Jura, France). Small‐scale lithological variations have been identified with high stratigraphic resolution in order to establish lithostratigraphic correlations between cores. κ measurements, combined with mineralogical analyses, provide information on past sedimentary processes. This combined approach reflects major changes in terrestrial habitats and soil processes which may relate to the climatic events characterising the Late Glacial climatic warming and cooling phases. During warm intervals, the record indicates increased lake productivity via carbonate precipitation and decreased input of detrital material. In contrast, cooler intervals show reduced lake productivity, catchment area instability and increased detrital inputs. Several short interruptions in reforestation and in soil stabilisation can be identified and linked with abrupt colder events occurring through the Bølling. A general trend of warming is recorded from the coldest part of the Younger Dryas. Three tephra layers were also detected. The mineral composition analyses show that the upper tephra layer corresponds to the Laacher See eruption (Eifel, Germany) while the lower ones may relate to the volcanic activity of the Chaîne des Puys (Massif Central, France) around 13 000 cal. yr BP. These two events, recognised for the first time outside the Massif Central region, may provide additional chronostratigraphic markers for the Late Glacial sedimentary records of the Jura mountains and northern Alps. Copyright © 2004 John Wiley & Sons, Ltd.
Novel Brush Copolymers via Controlled Radical Polymerization
Authors: Venkatesh Rajan , Yajjou Latifa , Koning Cor E , Klumperman Bert 
Published: October 2004

AbstractSummary: A combination of reversible addition‐fragmentation chain transfer (RAFT) polymerization and atom transfer radical polymerization (ATRP) techniques were applied for the synthesis of novel polymer brushes by using the “grafting from” approach or a combination of “grafting through” and “grafting from” methods. The procedure included the following steps: (1) Synthesis of 2‐(2‐bromoisobutyryloxy)ethyl methacrylate (BIEM), (2a) RAFT homopolymerization of BIEM to obtain PBIEM as the polymer backbone. (2b) RAFT copolymerization of BIEM and PEO macromonomer (PEOMA, $\overline M _{\rm w}$ = 450 g · mol−1, $\overline {DP} _{{\rm PEO}}$ = 9) to obtain a more hydrophilic polymer backbone. Well‐controlled copolymers containing almost 25 mol‐% of PEOMA were obtained, and (3) ATRP homopolymerization of methyl acrylate (MA) and copolymerization of MA with 1‐octene using both PBIEM homopolymer and poly(BIEM‐co‐PEOMA) as polyinitiators resulted in brushes with densely grafted homopolymer and copolymer side chains, respectively. Well‐controlled copolymer side chains containing 15 mol‐% of 1‐octene were obtained. Relatively narrow molar mass distributions (MMD) were obtained for the ATRP experiments. The formation of the side chains was monitored using size exclusion chromatography (SEC) and NMR spectroscopy. The copolymer composition in the side chain was confirmed using 1H NMR spectroscopy. Contact angle measurements indicated that for the brush polymers, containing 1‐octene in the side chain, there was a decrease in the surface energy, as compared with the brush polymers containing only the homopolymer of MA in the side chain.Tapping‐mode SFM images for the poly(BIEM)‐graft‐poly(MA‐co‐octene) brush polymer, dip coated from dilute THF solution on mica.magnified imageTapping‐mode SFM images for the poly(BIEM)‐graft‐poly(MA‐co‐octene) brush polymer, dip coated from dilute THF solution on mica.
Amphotropic Ionomers by Attachment of Secondary Amines to a Reactive Ester Polymer
Authors: Mruk Ralf , Prehl Sabine , Zentel Rudolf 
Published: October 2004

AbstractSummary: We report on the synthesis of polyacrylamides that were prepared by the reaction of a reactive ester polymer with a mesogen‐containing secondary amine and N‐methylpiperazine. As the polymers do not form hydrogen bonds near the amide groups, their mobility is significantly higher than that of poly(N‐monoalkylacrylamides). The initially nonionic polymer shows no liquid‐crystalline behavior in bulk and in mixture with ethylene glycol. This is due to the low polarity difference between the different side chains. The polarity difference can be increased by protonation or quarternization of the tertiary amino groups, and liquid‐crystalline behavior is observed. The self‐assembly multilayer build‐up of the polymer with quarternized amino groups, and an anionic polyelectrolyte proceeds regularly.
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Nylon 6‐Polyesteramide Block Copolymers (NBC) and NBC/Phenolic Resin Composites, 1
Authors: Estrada‐Monje Anayansi , Navarro‐Rodríguez Dámaso 
Published: October 2004

AbstractSummary: A series of NBC/phenolic resin composites, containing 0, 1, 3, 5 or 7 wt.‐% of a powdered phenolic resin of different particle diameter, was prepared by the reaction injection molding (RIM) process. It was determined by SEM analysis that there exists a strong interaction between particles and matrix and that such interaction occurs through hydrogen‐type bonds as determined by FTIR analysis. According to the results it is thought that the glass transition temperature of the NBC/phenolic resin composites depends on two competing factors: the rigidity promoted by the hard solid filler and the flexibility imparted by the nylon 6 amorphous phase, whose proportion becomes more important with increasing amounts of phenolic resin particles. The elastic and flexural moduli of the NBC were improved by the addition of phenolic resin confirming the reinforcing effect of this filler. On the contrary, the impact strength diminishes with increasing amounts of phenolic resin, although this property is strongly dependent on the particle diameter.SEM micrograph of the nylon 6‐polyesteramide block copolymer (80/20).magnified imageSEM micrograph of the nylon 6‐polyesteramide block copolymer (80/20).
A Study on the Friction and Wear Behavior of PTFE Filled with Acid Treated Nano‐Attapulgite
Authors: Lai Shi‐Quan , Li Tong‐Sheng , Liu Xu‐Jun , Lv Ren‐Guo 
Published: October 2004

AbstractSummary: A solid lubricant composite material was prepared by compression molding PTFE and acid treated nano‐attapulgite. The friction and wear tests were performed on a block‐on‐ring wear tester. Scanning electron microscopy (SEM), energy‐dispersive X‐ray spectrometer (EDS) and DSC were utilized to investigate material microstructures and examine modes of failure. Experimental results showed that there was no significant change in coefficient of friction, but the wear rate of the PTFE composite was orders of magnitude less than that of pure PTFE. Acid treated nano‐attapulgite was superior to untreated nano‐attapulgite in enhancing the wear resistance of PTFE. Moreover, the wear resistance of the composite increased monotonically with increasing treated attapulgite concentration. Investigation of transfer film and analysis of debris for PTFE and its composite showed that acid treated nano‐attapulgite filled to PTFE could facilitate formation of transfer film on the steel ring surface and inhibit breakage of PTFE molecular chain. The PTFE composite with higher heat absorption capacity exhibited improved wear resistance. Furthermore, the steel ring counterface abrasion was not found.Effect of load on the wear rate of PTFE and its composites.magnified imageEffect of load on the wear rate of PTFE and its composites.
Enzymatic Synthesis of Chitin‐ and Chitosan‐graft‐Aliphatic Polyesters
Authors: Fujioka Masayori , Okada Hideyuki , Kusaka Yukihiko , Nishiyama Satoko , Noguchi Hiromichi , Ishii Shigeru , Yoshida Yasuhiko 
Published: October 2004

AbstractSummary: The title polymers, in which both the stem and the graft are biodegradable, have been synthesized for the first time in a one‐pot, lipase‐catalyzed, graft‐polymerization reaction (in bulk, at 70 °C) of β‐butyrolactone (β‐BL) and ε‐caprolactone (ε‐CL) onto chitin and chitosan. The reactivity order of the lactones was found to be ε‐CL > β‐BL ≫ γ‐BL (no reaction). All the graft polymers prepared are insoluble in common organic solvents.Synthesis of chitin‐ or chitosan‐graft‐aliphatic polyesters.imageSynthesis of chitin‐ or chitosan‐graft‐aliphatic polyesters.
Free functional rectus femoris muscle transfer for restoration of extension of the foot after lower leg compartment syndrome
Authors: Wechselberger Gottfried , Pichler Maximilian , Pülzl Petra , Schoeller Thomas 
Published: October 2004

AbstractIn severely injured lower extremities with loss of the anterior compartment, the free functional rectus femoris musculocutaneous flap was used to restore extension of the foot and in soft‐tissue reconstruction. From June 2000–July 2002, 3 patients were treated with this technique. Mean follow‐up of the 3 patients was 27 months. Electromyography and the Stanmore system (recording pain, need for orthosis, ability to wear normal shoes, activity level, muscle power, active extension of the foot, and foot posture) were used to assess results of functional rectus femoris transfer. One patient had an excellent result, one patient had a good result, and one patient had a poor result, as assessed by the Stanmore system. Free functional rectus femoris transfer can obtain excellent results in treating foot‐drop and soft‐tissue defects due to lower leg compartment syndrome and loss of all muscles of the anterior compartment. © 2004 Wiley‐Liss, Inc. Microsurgery 24:437–441, 2004.
High‐performance liquid chromatography–coordination ion spray–mass spectrometry (HPLC‐CIS/MS): a new tool for the analysis of non‐polar compound classes in plant extracts using the example of Piper methysticum forst
Authors: Gaub M. , von Brocke A. , Roos G. , Kovar K.‐A. 
Published: October 2004

AbstractAn efﬁcient method to characterise complex plant extracts is described using the example of Piper methysticum Forst. (kava; Piperaceae). The method is based on the on‐line coupling of high‐performance liquid chromatography to a new detection technique: coordination ion spray–mass spectrometry (CIS/MS). CIS/MS is a universal, novel ionisation technique improving selectivity as well as sensitivity. Charged complexes were formed through addition of central complexing ions such as sodium, silver and cobalt. The advantages of CIS/MS detection compared with the electrospray ionisation detection are discussed. The experimental set‐up and the application of this simple and robust technique is described to show the its various ﬁelds of application in the analysis of plant extracts. Copyright © 2004 John Wiley & Sons, Ltd.
Determination of isopropylmethylphenols in black seed oil by differential pulse voltammetry
Authors: Michelitsch Astrid , Rittmannsberger Anna , Hüfner Antje , Rückert Ulla , Likussar Werner 
Published: October 2004

AbstractA differential pulse voltammetric method is presented for the determination of isopropylmethylphenols (carvacrol and/or thymol) in phytotherapeutic black seed oils. The voltammetric behaviours of these phenols were examined in various buffer systems over the pH range 3.5–10.0. In Sörensen buffered methanol solution (3:7; v:v; pH 8.5), the differential pulse voltammograms exhibited reproducible peaks at Ep + 0.49 V vs. silver–silver chloride–potassium chloride 3 m for both carvacrol and thymol. Under these conditions, a plot of peak height against concentration of the isopropylmethylphenols was found to be linear over the range 0.25–2.5 µg/mL (r = 0.999). The detection limit was 0.04 µg/mL. The described voltammetric method was tested on two black seed oils available on the Austrian market. Copyright © 2004 John Wiley & Sons, Ltd.
Quantitative analysis of ginkgolic acids from Ginkgo leaves and products using 1H‐NMR
Authors: Choi Young Hae , Choi Hyung‐Kyoon , Peltenburg‐Looman A. M. G. , Lefeber Alfons W. M. , Verpoorte Robert 
Published: October 2004

AbstractThe determination of ginkgolic acids in Ginkgo products is one of the principal components of quality control. However, a number of ginkgolic acids with different side chains may be present and this makes their analysis by conventional chromatographic methods more complex. In this study, 1H‐NMR spectrometry was applied to the analysis of the total content of ginkgolic acids in leaves of Ginkgo biloba and in six types of commercial Ginkgo products in the absence of chromatographic puriﬁcation. For this analysis, protons H‐3, H‐4, and H‐5, which are well separated in the range δ (ppm) 6.5–7.5 in the 1H‐NMR spectrum, were utilised. For further conﬁrmation, the correlations of H‐3, H‐4 and H‐5 were examined by 1H–1H COSY spectra in all extracts. The quantity of the compounds was calculated from the relative ratio of the integral of each peak to the integral of the peaks of a known amount (100 µg) of anthracene used as an internal standard. The quantitative results obtained by 1H‐NMR analysis were compared with those obtained by GC, which showed that the 1H‐NMR method allows a simple quantiﬁcation of total ginkgolic acids in Ginkgo extracts without any pre‐puriﬁcation steps. Copyright © 2004 John Wiley & Sons, Ltd.
Synthesis and characterization of gold‐based mesoscopic additives for polymers
Authors: Carotenuto G , Nicolais L 
Published: October 2004

AbstractA method for the controlled synthesis of alkanethiol‐derivatized gold clusters to be used as fillers for polymeric nanocomposites has been developed. Gold clusters embedded in poly(N‐vinyl pyrrolidone) (PVP) were obtained by reduction of AuCl4− with ethylene glycol in the presence of PVP as a stabilizer. The gold/PVP system was separated from the reactive mixture by flocculation with acetone, and this material was treated with a dodecanethiol/ethanol solution to produce thiol‐derivatized gold clusters. Then, the clusters were dispersed in polystyrene/chloroform solutions and highly transparent purple‐colored nanocomposite films were obtained by solution casting. This preparative scheme allows one to obtain high‐purity nanocomposites, with complete control over the filler percentage and size. Copyright © 2004 Society of Chemical Industry
Synthesis and characterization of new aromatic poly(amide–imide)s based on 4‐aryl‐2,6‐bis(4‐trimellitimidophenyl) pyridines
Authors: Behniafar Hossein , Banihashemi Ahmad 
Published: October 2004

AbstractNew diimide–dicarboxylic acids, ie 4‐phenyl‐2,6‐bis(4‐trimellitimidophenyl)pyridine and 4‐p‐biphenyl‐2,6‐bis‐(4‐trimellitimidophenyl)pyridine, were synthesized by the condensation reaction of 4‐phenyl‐2,6‐bis(4‐aminophenyl)pyridine and 4‐p‐biphenyl‐2,6‐bis(4‐aminophenyl)pyridine with trimellitic anhydride in glacial acetic acid or dimethylformamide. The monomers were fully characterized by FT‐IR and NMR spectroscopies, and elemental analyses. A series of novel poly(amide–imide)s with inherent viscosities of 0.68–0.87 dl g−1 was prepared from the two diimide–diacids with various aromatic diamines by direct polycondensation. The poly(amide–imide)s were characterized by FT‐IR and NMR spectroscopies. The λmax data for the resulting poly(amide–imide)s were in the range of 260–292 nm. These polymers exhibited good solubilities in polar aprotic solvents. The 10 % weight loss temperatures are above 485 °C under a nitrogen atmosphere. Copyright © 2004 Society of Chemical Industry
Synthesis and characterization of a novel hyperbranched polyether
Authors: Borah J , Karak N 
Published: October 2004

AbstractA hyperbranched polyether has been synthesized by a single‐step nucleophilic displacement polymerization technique between cyanuric chloride and the sodium salt of bisphenol‐A. The effects of various reaction parameters on the yield, and molecular weight, as measured by the intrinsic viscosity of the polymer, have been studied. The synthesized polymer has been characterized by FT‐IR, UV and 1H NMR spectroscopies, elemental analysis, solubility and viscosity measurements. The polymer is soluble in highly polar solvents such as N,N‐dimethylacetamide, N,N‐dimethylformamide and dimethyl sulfoxide, partially soluble in dilute aqueous NaOH solution, methanol, ethanol, chloroform, etc., but insoluble in water and non‐polar hydrocarbon solvents. The solubility parameter of the hyperbranched polymer has also been measured experimentally. Copyright © 2004 Society of Chemical Industry
Synthesis and evaluation of biodegradable segmented multiblock poly(ether ester) copolymers for biomaterial applications
Authors: Wang Lian‐cai , Chen Jin‐wu , Liu Hou‐li , Chen Zhu‐qiong , Zhang Yong , Wang Chang‐yong , Feng Zeng‐guo 
Published: October 2004

AbstractBased on 1,4‐succinic acid, 1,4‐butanediol, poly(ethylene glycol)s and dimethyl terephthalate, biodegradable segmented multiblock copolymers of poly[(butylene terephthalate)‐co‐poly(butylene succinate)‐block‐poly(ethylene glycol)] (PTSG) were synthesized with different poly(butylene succinate) (PBS) molar fractions and varying the poly(ethylene glycol) (PEG) segment length, and were evaluated as biomedical materials. The copolymer extracts showed no in vitro cytotoxicity. However, sterilization of the copolymers by gamma irradiation had some limited effect on the cytotoxicity and mechanical properties. A copolymer consisting of PEG‐1000 and 20 mol% PBS, assigned as 1000PBS20 after SO2 gas plasma treatment, sustained the adhesion and growth of dog vascular smooth muscle cells. The in vivo biocompatibility of this sample was also measured subcutaneously in rats for 4 weeks. The assessments indicated that these poly(ether ester) copolymers are good candidates for anti‐adhesion barrier and drug controlled‐release applications. Copyright © 2004 Society of Chemical Industry
Luminescent copoly(aryl ether)s with new electron‐transporting bis(3‐(trifluoromethyl)phenyl)‐1,3,4‐oxadiazole or bis(3‐(trifluoromethyl)phenyl)‐4‐(4‐hexyloxyphenyl)‐4H‐1,2,4‐triazole segments
Authors: Chen Shinn‐Horng , Chen Yun 
Published: October 2004

AbstractTo investigate the effect of trifluoromethyl groups in enhancing electron affinity of aromatic oxadiazole and triazole chromophores, we prepared four new copoly(aryl ether)s (P1–P4) consisting of bis(3‐(trifluoromethyl) phenyl)‐1,3,4‐oxadiazole (ETO) or bis(3‐(trifluoromethyl)phenyl)‐4‐(4‐hexyloxyphenyl)‐4H‐1,2,4‐triazole (ETT) segments and hole‐transporting segments [2,5‐distyrylbenzene (HTB) or bis(styryl)fluorine (HTF)]. Molecular spectra (absorption and photoluminescence) and cyclic voltammetry were used to investigate their optical and electrochemical properties. The emissions of P1–P4 are dominated by the hole‐transporting fluorophores with longer emissive wavelengths around 442–453 nm via efficient excitation energy transfer. The highest occupied molecular orbital (HOMO) and lowest unoccupied molecular orbital (LUMO) energy levels of P1–P4, estimated from electrochemical data, are −5.15, −5.18, −5.30, −5.27, −3.39, −3.49, −3.36, and −3.48 eV, respectively. The LUMO levels of ETO and ETT segments are significantly reduced to −3.39∼−3.36 eV and −3.48∼−3.49 eV, respectively, as compared with −2.45 eV of P5 containing a 2,5‐diphenyl‐1,3,4‐oxadiazole segment. Moreover, electron and hole affinity can be enhanced simultaneously by introducing isolated hole‐ and electron‐transporting segments in the backbone. © 2004 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 42: 5900–5910, 2004