bluuebunny/crossref_metadata_2025 huggingface dataset:
Late Quaternary palaeoecological and palaeoclimatological reconstruction in the Gutaiului Mountains, northwest Romania
Authors: Feurdean Angelica , Bennike Ole
Published: October 2004

Macrofossil, 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

This 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

Summary: 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.

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Tapping‐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

Summary: 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

Summary: 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).

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SEM 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

Summary: 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.

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Effect 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

Summary: 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.

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Synthesis 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

In 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

An 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

A 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

The 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

A 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

New 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

A 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

Based 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

To 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
Dendrimers as scaffolds for multifunctional reversible addition–fragmentation chain transfer agents: Syntheses and polymerization
Authors: Hao Xiaojuan , Nilsson Camilla , Jesberger Martin , Stenzel Martina H. , Malmström Eva , Davis Thomas P. , Östmark Emma , Barner‐Kowollik Christopher
Published: October 2004

The synthesis and characterization of novel first‐ and second‐generation true dendritic reversible addition–fragmentation chain transfer (RAFT) agents carrying 6 or 12 pendant 3‐benzylsulfanylthiocarbonylsulfanylpropionic acid RAFT end groups with Z‐group architecture based on 1,1,1‐hydroxyphenyl ethane and trimethylolpropane cores are described in detail. The multifunctional dendritic RAFT agents have been used to prepare star polymers of poly(butyl acrylate) (PBA) and polystyrene (PS) of narrow polydispersities (1.4 < polydispersity index < 1.1 for PBA and 1.5 < polydispersity index < 1.3 for PS) via bulk free‐radical polymerization at 60 °C. The novel dendrimer‐based multifunctional RAFT agents effect an efficient living polymerization process, as evidenced by the linear evolution of the number‐average molecular weight (Mn) with the monomer–polymer conversion, yielding star polymers with molecular weights of up to Mn = 160,000 g mol−1 for PBA (based on a linear PBA calibration) and up to Mn = 70,000 g mol−1 for PS (based on a linear PS calibration). A structural change in the chemical nature of the dendritic core (i.e., 1,1,1‐hydroxyphenyl ethane vs trimethylolpropane) has no influence on the observed molecular weight distributions. The star‐shaped structure of the generated polymers has been confirmed through the cleavage of the pendant arms off the core of the star‐shaped polymeric materials. © 2004 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 42: 5877–5890, 2004
Fracture mechanism of liquid‐crystalline epoxy resin systems with different phase structures
Authors: Harada Miyuki , Aoyama Kentaro , Ochi Mitsukazu
Published: October 2004

A liquid‐crystalline epoxy resin was cured at two different temperatures. The phases of the cured systems clearly showed isotropic and nematic polydomain structures, which depended on the curing temperature. The fracture toughness of the systems was measured, and the fracture mechanism was investigated with polarized IR measurements. The nematic polydomain structure system showed considerably higher fracture toughness than the isotropic structure. Moreover, both systems exhibited a reorientation of the network chains near the fracture surface during the fracture process, and the region of the network reorientation in the nematic polydomain structure system was larger than that in the isotropic structure system. © 2004 Wiley Periodicals, Inc. J Polym Sci Part B: Polym Phys 42: 4044–4052, 2004
Preparation of benzoylchitosans and their chiroptical properties in dilute solutions
Authors: Wu Yusong , Seo Toshihiro , Maeda Shiro , Sasaki Takashi , Irie Satoshi , Sakurai Kensuke
Published: October 2004

Two benzoyl substituted chitosan derivatives, 3,6‐O‐dibenzoylchitosan (DBC) and 2‐N‐3,6‐O‐tribenzoylchitosan (TBC), were prepared, and their optical activities in organic solvent were investigated by circular dichroism (CD). For TBC, two splitting bands (a negative one at 288 nm and a positive one at 274 nm) corresponding to the 1Lb transition of the benzoyl group were observed in chloroform and dichloromethane, while only a negative CD band was recorded in N, N‐dimethylformamide (DMF). These results indicated that the transition moments of benzoyl groups were orderly arranged along the helical polymer chain when TBC was dissolved in a solvent with low polarity, but the same ordered structure did not appear in a polar solvent of DMF. For DBC, only negative CD signals corresponding to the 1Lb transition of the benzoyl group were observed, regardless of the solvent property, which indicated that the chromophores were not arranged in an ordered fashion with appropriate geometry to interact with one another to induce bi‐signate CD signals. Adding methanol or DMF to the solution of TBC/chloroform resulted in a progressive decrease of the intensity of the positive split band at 274 nm. The intensity of the positive band was weakened upon heating a solution of TBC/chloroform from 20 to 60 °C. The results suggested that the ordered arrangement of the chromophores in the TBC system was dependent on solvent and sensitive to temperature. © 2004 Wiley Periodicals, Inc. J Polym Sci Part B: Polym Phys 42: 4107–4115, 2004
Weakly bound triatomic 4He23He and 3He24He molecules
Authors: Gou Bingcong , Wang Fei
Published: October 2004

The bound rotational excited states of weakly bound 4He23He and 3He24He molecules have been searched for. Including pair interaction between helium atoms, we solved the Schrödinger equation for the triatomic systems with hyperspherical coordinates in the adiabatic approximation. The resulting potential curves are mostly repulsive for nonzero angular momenta. We conclude that no bound rotational excited states exist in both 4He23He and 3He24He molecules. The stability of the systems depends sensitively on the quantum symmetry and the masses of the particles. © 2004 Wiley Periodicals, Inc. Int J Quantum Chem, 2005
Theoretical study of structure and stability of fullerene derivative: C50O
Authors: Xu Xiufang , Xing Yumei , Yang Xia , Wang Guichang , Cai Zunsheng , Shang Zhenfeng , Pan Yinming , Zhao Xuezhuang
Published: October 2004

A total of eight possible isomers of C50O, an oxide of fullerene C50 (D5h), have been investigated by B3LYP/3‐21G calculations. The isomer, which has an annulene‐like structure with oxygen bridging across a [5,6] type CC bond at the site between the pole and the equatorial belt, is found being the ground state of C50O. Four isomers are relatively more stable and the energy differences between them are not large. This result indicates that more than one C50O isomer will coexist once C50O is synthesized. The relative stabilities of the C50O isomers may be determined mainly by the strain release and by the formation of the cyclic phenylene substructure at the equatorial belt of the cage. The calculated nucleus independent chemical shifts (NICS) of the C50O isomers will be useful because from them one can expect outstanding NMR properties that can lead to their identification and characterization. © 2004 Wiley Periodicals, Inc. Int J Quantum Chem, 2005
A gauge‐origin independent expression for the Verdet constant within the time‐dependent density functional theory
Authors: Banerjee Arup , Autschbach Jochen , Ziegler Tom
Published: October 2004

The analytical expression for the Verdet constant of magneto‐optical rotation is presented within the time‐dependent density functional theory formalism. Use has been made of gauge, including atomic orbitals, to circumvent the problem of gauge dependence often associated with the calculation of magnetic properties. © 2004 Wiley Periodicals, Inc. Int J Quantum Chem, 2005
Avoiding asymptotic divergence of the potential from orbital‐ and energy‐dependent exchange‐correlation functionals
Authors: Niquet Y. M. , Fuchs M. , Gonze X.
Published: October 2004

We investigate the asymptotic behavior of the exchange‐correlation potentials deriving from orbital‐ and energy‐dependent (OED) functionals potentially able to describe van der Waals interactions. We take some simple functionals based on the adiabatic connection fluctuation‐dissipation (ACFD) theorem as examples. Although the potentials deriving from arbitrary OED functionals can be expected to diverge asymptotically, we find that these ACFD potentials are in fact well behaved. They indeed depend on Kohn–Sham orbitals and energies only through the Kohn–Sham Green function, allowing for complete analytical treatment. However, the dependence on the empty Kohn–Sham orbitals and energies must be treated with care. We discuss some precautions to be taken for practical calculation of these potentials. Last, we introduce approximate potentials, which are much simpler to compute than the exact ones, but are still quite accurate. © 2004 Wiley Periodicals, Inc. Int J Quantum Chem, 2005
Effect of neonatal isolation on the noradrenergic transduction system in the rat hippocampal slice
Authors: Kusaka Kouji , Morinobu Shigeru , Kawano Ki‐Ichiro , Yamawaki Shigeto
Published: October 2004

Numerous studies suggest that early adverse experiences induce neurochemical, morphological, and functional changes in the hippocampus in adolescence and adulthood. The aim of this study was to identify the influence of neonatal isolation (NI) on noradrenaline (NA)‐mediated intracellular calcium ([Ca2+]i) mobilization. To measure [Ca2+]i, we used the Ca2+‐sensitive dye fura‐2 and analysis by fluorescence microscopy. First, we examined the contributions of adrenergic receptor subtypes to the NA‐stimulated increase in [Ca2+]i in the granule cell layers of the dentate gyrus (DG) and in the pyramidal cell layers of the CA3 in the hippocampus. Second, we found that the NA‐stimulated [Ca2+]i increment was significantly decreased in response to NI in these hippocampal regions. In addition, we examined the influence of environmental enrichment (EE) after weaning on the decrease in the NA‐stimulated [Ca2+]i increment induced by NI. The administration of EE reversed the influence of NI on the NA‐stimulated [Ca2+]i increment in the CA3 pyramidal cell layer but not in the DG granular cell layer in the hippocampus. These findings suggest that NI and EE after weaning may modulate hippocampal function by altering adrenergic receptor‐mediated signal transduction during adolescence. Synapse 54:223–232, 2004. © 2004 Wiley‐Liss, Inc.
Mycosporine‐glutaminol‐glucoside, a UV‐absorbing compound of two Rhodotorula yeast species
Authors: Sommaruga Ruben , Libkind Diego , van Broock Maria , Whitehead Kenia
Published: October 2004

High‐performance liquid chromatography (HPLC), alone or in combination with mass spectrometry (MS), was used to screen the basidiomycetous yeasts Rhodotorula minuta and R. slooffiae isolated from lakes for the presence of UV‐absorbing compounds. Mycosporine‐glutaminol‐glucoside (maximum absorption, 310 nm), a UV‐photoprotective mycosporine known in terrestrial fungi, was the major UV‐absorbing compound found in these species. This is the first identification of a mycosporine in yeasts. The presence of this compound seems to be a promising chemotaxonomical marker for yeast systematics. Copyright © 2004 John Wiley & Sons, Ltd.
Limitations of codon adaptation index and other coding DNA‐based features for prediction of protein expression in Saccharomyces cerevisiae
Authors: Friberg Markus , von Rohr Peter , Gonnet Gaston
Published: October 2004

The relationship between codon usage and protein/mRNA expression in S. cerevisiae has been extensively studied. Recently, protein expression data for the whole yeast genome was published. We investigate which properties of coding DNA sequences can be used to predict expression levels. The new algorithm by Carbone et al. for computing dominating codon bias in a genome is evaluated. It is concluded that it works at least as well as existing methods, and eliminates the need to arbitrarily choose a set of highly expressed genes. Also, the hypothesis that information on codon pair frequencies can be used to predict expression is investigated. Our conclusion is that codon pairs do not contribute more information than do single codon frequencies. Overall correlation between predicted and actual expression data using properties of coding DNA sequences is around 0.65. Hence, while being a useful source of information, the expression levels predicted by these methods should only be used as a rule of thumb. Copyright © 2004 John Wiley & Sons, Ltd.
Mating‐induced mating‐type cassette conversion in Saccharomyces cerevisiae
Authors: Nishida Yuri , Katoh Hiroyuki , Andoh Masahiko , Ono Bun‐ichiro
Published: October 2004

We have previously reported that the HMRa‐bearing restriction fragment of a ρ° sir4‐11 strain (HMLα‐MATα‐HMRa), which acts as an α‐mater because of being ρ°, changes its electrophoretic mobility when the strain mates with a certain group of a‐mating strains (HMLα‐MATa‐HMRa). In this study, we found that the sir4‐11 strain being ρ° was not essential for this phenomenon and also that the altered form of the fragment contained HMRα in place of HMRa. Furthermore, we observed conversion of HMLa to HMLα in the cross in which a sir4‐11 HMLa‐MATα‐HMRα strain was mated with a representative of the above‐mentioned a‐mating strain. In addition, when this a‐mating strain was mated with a SIR+ HMLα‐MATa‐HMRα strain, the resultant diploid was found to be HMLα/HMLα MATa/MATαHMRa/HMRα, indicating that conversion of MATa to MATα had taken place in the course of mating. From all these observations, we conclude that there is a group of S. cerevisiae strains that carries factor(s) that induces conversion of a mating‐type cassette of the mating partner to α mating‐type cassette and that this mating type cassette conversion takes place in all three mating type loci, HML, MAT and HMR, if the loci are in the non‐silenced condition. Copyright © 2004 John Wiley & Sons, Ltd.
Surgical training in a statutory health insurance system: Belgian experience
Authors: Hubens A. , Van Hee R.
Published: October 2004

Health care delivery in Belgium is based on a compulsory insurance system, installed and controlled by the government since 1945 for employees; in 1963 the system was expanded to include self‐employed citizens. Mutual benefit organizations act as insurance carriers for all patients, whether cared for in the office or hospital. The cost of statefinanced medical care has grown to such an extent during the last few decades that cost‐sharing in ambulatory practice is being extended to in‐clinic services. The free choice of practitioners as well as free access to medical and specialist education have always been keystones of the Belgian medical care system. A well regulated scheme of surgical training combined with strict rules imposed on instructors, hospitals, and trainees guarantee high quality and state‐controlled surgical education. Developments in the Belgian political landscape may considerably affect health care delivery and surgical education. A constant rise in the number of medical practitioners and the sociopolitical discrepancies between the Flemish and French speaking parts of the federalized kingdom have paralleled burgeoning medical health care costs and have induced rationalization and possibly federalization of health care dilivery as well as ongoing debates concerning the limitation of medical and surgical practitioners.
Health care delivery systems: Effects on surgical education in Italy
Authors: Stipa Sergio , Ziparo Vincenzo , Castorina Silvia
Published: October 2004

Since 1989 a national health system (NHS) has been in effect in Italy based on the constitutional principle that health care is a right of all citizens. Until 1992 the NHS had a secondary role in medical education, as the 33 medical schools for postgraduate training are under the control of the Ministry of University. The European Community legislation allowing free movement of M.D.s and specialists between member countries has resulted in standardization of teaching programs and formative curricula in the European Community. Therefore beginning in 1992, every 3 years the Ministry of Health and University establishes the number of specialists that can meet the needs of the NHS and allocates funds to each school for the salary obligations. The actual number of paid residents for surgical specialities is 941 per year (192 for general surgery). Until recently surgical training in Italy was mainly theoretic, as no legislation guaranteed that physicians in training would perform surgery. New legislation, increased exchanges with European hospitals, and improved and loyal cooperation between universities and the NHS will certainly improve the situation in coming years.
Health care delivery system. Effects on surgical education: The Mexican panorama
Authors: Cervantes Jorge , Cervantes Arturo
Published: October 2004

Health care delivery in Mexico is divided in three groups: a social sector that covers approximately 53% of the population and is financed by the labor force, the state and the employer; a public, or open, sector that covers 33% of the population and is financed by federal and state funds; and a private sector that covers about 5% of the population and has two categories, the not‐for‐profit hospitals and the profit‐oriented institutions. Most medical practitioners can work in any of the three groups or in several. Nine percent of Mexico's population, because of extreme ignorance, poverty, or isolation, have no or limited access to medical care. Mexico has 58 medical schools, which graduate about 7800 new physicians annually, awarding them the title Medico cirujano (Physician Surgeon). There are more than 160,000 physicians in Mexico, 20,000 of whom are unemployed. Each year, approximately 12,000 physicians compete for the 4306 places in the official residency training programs for all specialties. Of those taking the examination, 2000 try to get one of the 625 slots available for training in general surgery. Most of the surgical training programs in Mexico have a 3‐year duration. The Mexican Academy of Surgery, the Mexican Society of General Surgery, and the Mexican Board of Surgery, as well as private individuals and organizations, are working to improve the quality of medical education and trying to establish a 5‐year training program in surgery. The rapid movement toward modernization that is sweeping the country must include the improvement of surgical education as well.
Health care provision and surgical education in South Africa
Authors: Thomson Sandie R. , Baker Lynne W.
Published: October 2004

Apartheid policies have led to inequalities in the delivery of health care and the training of surgeons in South Africa. The nation's population of 33 million is comprised of 73.6% Blacks, 14.8% Whites, 8.8% Coloureds, and 2.7% Asians. Only 17% of the population are covered by medical insurance (78% of Whites, 28% of Asians, 26% of Coloureds, 4% of Blacks) that funds the private sector which accounts for 46% of the nation's total health care expenditure of 9.2156 million rand. The remainder receive care from curative state hospital based services, which consume 77% of the public expenditure on health. Preventive and promotive health services account for 23%. only 3.2% of South Africa's gross national product is spent on health care provision for 80% of the population‐well short of the World Health Organization's recommendation of 5.8%. This figure translates into a per capita expenditure of 138, 340, 356, and 597 rands for Blacks, Coloureds, Asians, and Whites, respectively. Eight medical schools produce just over 900 graduates per year, 80% of whom are white. The medium of instruction is English at five (Cape Town, Witwatersrand, Natal, MEDUNSA, and Transkei) and Afrikaans at three (Pretoria, Stellenbosch, and Bloemfontein). Natal and MEDUNSA are creations of apartheid and have graduated almost all the Black South African doctors, of whom only 15 are practicing surgeons. Many universities are cognizant that dramatic change is needed to redress such imbalances, and admission policies are changing. Schools are addressing the implications of admitting many more Black African students from less privileged educational backgrounds into their medical faculties. Only then will more nonwhite graduates emerge with excellent, well monitored specialist training in surgery, which until now has been the domain of mainly white doctors.
Swedish health care delivery system and its effects on surgical education
Authors: Bengmark Stig , Jeppson Bengt
Published: October 2004

Sweden, with a small, decentralized population, has a similarly decentralized network of hospitals that comprise the national health care system, which is nonetheless highly regulated by the national government. Medical education and graduate training in surgery are likewise regulated. Reforms implemented in 1992 made a 21‐month general rotating internship mandatory for all medical graduates, after which they enter specialty training. That training, which lasts a minimum of 5 years, is done under the tutelage of a Board‐certified practitioner in the field. During the trainee and program contract for the amount of time spent in clinical and didactic experiences, the trainee is personally responsible for ensuring that much of his or her individual programs is accomplished. Rising health care costs have spurred increased rationalization of resources and are expected to constrict training opportunities for future surgeons.
Health care delivery systems: Effects on surgical education
Authors: Taylor I.
Published: October 2004

In the United Kingdom recent changes in government health policy and a reduction in junior doctors' hours are likely to have an effect on surgical training. These changes are occurring at a time when there is increasing specialization in surgical care, which necessitates careful organization of surgical training programs. This paper reviews the interaction of these factors in influencing our attitudes toward surgical training.
Changing surgical education strategies in an environment of changing health care delivery systems
Authors: Dunnington Gary L. , DaRosa Debra A.
Published: October 2004

Emerging changes in health care delivery will have a significant impact on the structure of surgical education in academic departments of surgery. Based on some assumptions as to the probable nature of the final product of this reform, this article encourages a proactive stance by surgical educators to anticipate changes and move toward restructuring in areas of curricular content, the teaching process, performance evaluation strategies, and faculty infrastructure of the academic department. Curriculum changes must bridge the gap between public health and medicine and continue the aggressive trend toward teaching in the outpatient setting. Surgical educators must adapt to evolving computer and instructional technology that will make multimedia presentations, distance education, teleconferencing, hypermedia, and virtual reality commonplace in the teaching setting. Increased emphasis on accountability and accreditation will require stringent criteria in performance and program evaluation methodology. The academic infrastructure will need to adapt to the changing goal of training more general surgeons and fewer specialists and yet maintain the fundamental responsibility of an academic surgeon for mentoring the medical student and surgical resident.
U.S. health care reform: Will it change postgraduate surgical education?
Authors: Pories Walter J. , Smout Jay C. , Morris Alva , Lewkow Victoria E.
Published: October 2004

The principal goals of the pending health care reform initiatives in the United States are improving access to health care and controlling its costs. There are multiple proposals designed to reach these goals. Regardless of the final result, health care reform is likely to have significant implications for postgraduate surgical education. The teaching environment is already rapidly changing. Present environmental influences include the explosion of surgical knowledge, demographic changes, expansion of regulatory requirements from within the health care delivery system and within surgery as a discipline, societal and cultural changes, and economic pressures. Current and pending concerns prompt several questions: What should we teach? Where do we teach? How long should it take? Who are our learners? How do we evaluate our educational programs? Who should pay? A number of predictable changes affecting surgical education are proposed. New, more complex technologies will result in increased surgical specialization. Demands on surgical education will require that it be shorter, more relevant, more efficient, more effective, and more accountable. Surgical manpower requirements must be more clearly defined. Better and more relevant measures of clinical outcomes will be developed. Use of improved informational technology to manage clinical activity will expand. Solutions to the problem of foreign medical graduates will be clarified. The issue of who pays for surgical education will require resolution with some new and creative results. A proposal for shorter and more effective surgical residency is advocated.
HIV infection and surgeons
Authors: Lin Eric Y. , Brunicardi F. Charles
Published: October 2004

The human immunodeficiency virus (HIV) causes acquired immunodeficiency syndrome, which remains uniformly fatal in affected individuals. A common route of HIV transmission is via inoculation of contaminated blood, which may occur during surgical procedures. Surgeons may estimate their risk of HIV infection over a 30‐year surgical career based on HIV prevalence among surgical patients, percutaneous injury rate per operation, and seroconversion rate. Surgeons can reduce their risk by various means, but the most pragmatic is by reducing the rate of percutaneous injury through optimal surgical technique and proper precautions.