bluuebunny/crossref_metadata_2025_split huggingface dataset:
Zinc Glutarate Catalyzed Synthesis and Biodegradability of Poly(carbonate‐co‐ester)s from CO2, Propylene Oxide, and ϵ‐Caprolactone
Authors: Hwang Yongtaek , Kim Heesoo , Ree Moonhor 
Published: May 2005

AbstractA zinc glutarate (ZnGA) catalyst was prepared from the reaction of zinc oxide and glutaric acid in dry toluene. ZnGA was found to exhibit a catalytic activity for the copolymerization of carbon dioxide (CO2) and propylene oxide (PO) and the homopolymerization of PO but to reveal no catalytic activity for the homopolymerization of ϵ‐caprolactone (CL). The ZnGA‐catalyzed polymerization was extended for the terpolymerization of CO2 with PO and CL, producing poly(propylene carbonate‐co‐ϵ‐caprolactone)s (PPCCLs) with a reasonably high molecular weight in high yields. In the terpolymerization, PO and CL were used as both co‐monomers and reaction media, after the reaction completed, the excess co‐monomers were easily recovered and reused in the next terpolymerization batch. For the synthesized polymers, enzymatic and biological degradability were investigated.
Synthesis and Characterization of New Biodegradable Polymers for Biomodeling and Biomedical Applications
Authors: Sung Yong Kiel , Song Dae Kyung 
Published: May 2005

AbstractBiodegradable poly(1,2‐propanediol succinate) and poly(1,3‐propanediol succinate) were synthesized using 1,2‐propanediol and 1,3‐propanediol with succinic anhydride, respectively. The synthesized polymers were identified by NMR spectrometry and FT‐IR spectrophotometry. The weight average molecular weights were 8,900 in poly(1,2‐propanediol succinate) and 8,600 in poly(1,3‐propanediol succinate), respectively. The biodegradation behavior of polymers in microorganisms was studied by using a modified ASTM method. These polyesters were degraded to lower molecular weight compounds depending on hydrophobicity and hydrophilicity. The quantitative determination of carbon dioxide, generated during the treatment with the activated sludge, showed that poly(1,3‐propanediol succinate) was biodegraded faster than poly(1,2‐propanediol succinate). The biodegradation ability of the polymers by Aspergillus niger was monitored to check the molecular weights using GPC and to check the crystallinity change of the polymers using DSC. Based upon the visual observation of the biodegraded polymers, the crystalline structure of poly(1,2‐propanediol succinate) apparently retained its crystallinity longer than the similar structure in poly(1,3‐propanediol succinate).
Locust Bean Gum Hydrogels Formed by Freezing and Thawing
Authors: Hatakeyama Tatsuko , Naoi Sunao , IIjima M. , Hatakeyama Hyoe 
Published: May 2005

AbstractLocust bean gum (LBG) hydrogels were prepared by freezing and thawing. It was found that the junction zone of LBG hydrogels is tightly formed by repeating freezing and thawing. During this process, LBG molecules not connected with the junction zone are excluded from the gel portion and the remaining molecules gradually form densely packed hydrogels. Molecular conformation in the sol state affects the rate of the junction formation. Obtained LBG hydrogels are thermally stable and no gel‐sol transition was observed in temperatures from 40 to 100 °C by the observation of differential scanning calorimetry (DSC). Non‐freezing water content calculated from the DSC melting peak of water in the gel indicates that the junction zone became dense with increasing freezing and thawing.
Influence of Heat Treatment on Biological Properties of Chitosan toward Vascular Cells in vitro
Authors: Lim Sae‐Hwan , Park Ki‐Sook , Park Hyun‐Sook , Gin Yong‐Jae , Noh In‐Sup , Park Chan‐Woong , Son Young‐Sook , Kim Chun‐Ho 
Published: May 2005

AbstractThe effects of heat treatment of chitosan film on the proliferation of vascular cells were examined in vitro. Chitosan film was heat treated at 110 °C in vacuo for 1∼3 days. Heat treatment slightly improved the hydrophilicity of chitosan, although the cross‐linking of chitosan took place after heat treatment. Chitosan films were cytocompatible toward smooth muscle cells (SMCs) and human dermal microvascular endothelial cells (HDMECs) before and after heat treatment of chitosan. In particular, the heat treated chitosan supported the proliferation of both vascular cell types for one day. The growth of HDMECs was greater than that of SMCs on heat treated chitosan film for one day. Heat treated chitosan has intrinsic biological activity which could contribute to a retardation of SMC growth relative to HDMECs.
Thermosensitive Chitosans as Novel Injectable Biomaterials
Authors: Chung Ho Jin , Bae Jin Woo , Park Hyung Dal , Lee Jin Woo , Park Ki Dong 
Published: May 2005

AbstractTwo kinds of water soluble thermosensitive chitosan copolymers were prepared by graft polymerization of N‐isopropylacrylamide (NIPAAm) onto chitosan using cerium ammonium nitrate (CAN) as an initiator (chitosan‐g‐NIPAAm) and by coupling monocarboxy Pluronic® with chitosan using 1‐ethyl‐3‐(3‐dimethylaminopropyl)‐carbodiimide (EDC) and N‐hydroxysuccin‐imide (NHS) as coupling agents (chitosan‐Pluronic®). The physicochemical properties of the resulting copolymers were characterized and they formed thermally reversible hydrogel, which exhibits a lower critical solution temperature (LCST) at 34°C in aqueous solutions. The human mesenchymal stem cells (hMSCs) were cultured in the chiotsan‐g‐NIPAAm in vitro. Chondrogenic differentiation was induced in the chitosan‐g‐NIPAAm gel. Therefore, chondrogenic differentiated cells from MSCs with a thermo‐sensitive chitosan‐g‐NIPAAm could be used as an injectable cell‐polymer complex. In summary, chitosan‐g‐NIPAAm and chitosan‐Pluronic® attest to their usefulness as injectable materials because of their thermally reversible property and relatively good biocompatibility.
Novel Carbon Nanotube/Poly(L‐lactic acid) Nanocomposites; Their Modulus, Thermal Stability, and Electrical Conductivity
Authors: Moon Sung‐Il , Jin Fengzhe , Lee Cheol‐jin , Tsutsumi Sadami , Hyon Suong‐Hyu 
Published: May 2005

AbstractThe interest in poly(L‐lactic acid)(PLLA) has been increasing in recent years because this polymer is made from renewable resources and its properties are benign to the environment. Carbon nanotubes(CNTs) have shown exceptional stiffness and strength and remarkable thermal and electrical properties, which make them ideal candidates for the development of multifunctional material systems. In this study, mechanical and thermal properties as well as the electrical conductivity of CNTs/PLLA nanocomposites were investigated. Our study of the mechanical properties of these nanocomposites indicates that the tensile strength and ultimate elongation decreased, but Young's modulus slightly increased from 1 GPa to 2.5 GPa. Embedding the CNTs into the polymer matrix improves the thermal stability of the polymer. The thermogravimetric analysis (TGA) results of PLLA and the 3 wt% CNTs/PLLA nanocomposites in air show initial weight loss at the same temperature as PLLA, but the decomposition temperature for the nanocomposite is approximately 10°C higher than that of PLLA. Similar results were found for the other CNTs/PLLA composites (5, 10 wt%). In addition, electrical conductivity and electromagnetic wave shielding effect was also investigated.
Rheological, Thermal, and Morphological Characteristics of Plasticized Cellulose Acetate Composite with Natural Fibers
Authors: Choi Joon Soon , Lim Sung Taek , Choi Hyoung Jin , Hong Soon Man , Mohanty Amar K. , Drzal Lawrence T. , Misra Manjusri , Wibowo Arief C. 
Published: May 2005

AbstractPlasticized cellulose acetates processed with biofibers like industrial hemp and henequen were investigated with respect to their thermal, morphological and rheological characteristics. Discernable fibril morphologies in the biocomposites were observed via a SEM investigation. Such morphological characteristics were further analyzed with the results of TGA and rheometry. Furthermore, the obtained rheological properties were also interpreted in conjunction with the formation and destruction of internal structure in biocomposites.
Biodegradable Composites of Poly(lactic acid) with Cellulose Fibers Polymerized by Aluminum Triflate
Authors: Funabashi Masahiro , Kunioka Masao 
Published: May 2005

AbstractBiodegradable polymer composites consisting of poly(lactic acid) (PLA) and cellulose fibers (CF) were prepared by our newly developed method. L‐Lactic acid (LA) was reacted by ring‐opening polymerization with aluminum triflate as a catalyst, glycerol as an initiator and CF as a filler, in simple plastic tubes at 100 °C for 6 hours. By this method, CF could be mixed with the polymer matrix easily and homogeneously. The molecular weight and molecular weight distribution of the PLA matrix were determined by gel permeation chromatography (GPC). The Mn of the composite samples decreased from 6200 to 2800 with increasing CF content. The molecular weight distribution of composites was around 2.5 regardless of the CF content. Biodegradation of samples was determined by measuring the results from the Microbial Oxidative Degradation Analyzer (MODA) and the weight loss in compost. Biodegradation of composite samples of PLA with CF increases with increasing CF content as measured by the MODA. Apparent density of composite samples was calculated by using the weight and sizes of column shape specimens. The density of the composite samples was a bit lower than that of PLA pure samples without CF. Mechanical properties such as the elastic modulus and strength were investigated by compression tests using column shape specimens. For the sample with filter paper as CF, the strength of composite samples increases with increasing CF content.
Soil and Microbial Degradation Study of Poly(ϵ‐caprolactone) – Poly(vinyl butyral) Blends
Authors: Rohindra David , Sharma Praneel , Khurma Jagjit 
Published: May 2005

AbstractBiodegradation of blends of poly(ϵ‐caprolactone) [PCL] with poly(vinyl butyral) [PVB] was studied in the soil and by bacterial strains of Bacillus subtilis and Escherichia Coli isolated from the soil. Miscibility of the blends was also analyzed using FT‐IR and optical microscopy at room temperature. Biodegradation of the blends was followed by weight loss, visual observations and scanning electron microscopy [SEM]. Blends with low polyester concentration, i.e., 30 wt% PCL and less, were clear and transparent and no spherulite formation was observed. Above 30 wt% PCL spherulites appeared, the size of which increased with increasing PCL concentration. Infra‐red studies of the blends with less than 30 wt% PCL showed that only the amorphous phase of PCL was present. Above 30 wt% PCL indicated the presence of both crystalline and blended PCL. The second derivative of the carbonyl peak of PCL also supported the presence of two phases in blends with more than 30 wt% PCL and only one peak for blends with 30 wt% or less PCL. Weight loss was observed in all the blends. PCL rich blends showed more degradation, which was faster in the natural environment than in the laboratory. Physical appearance and microscopic examination showed the films deteriorated in soil. Blends in the Bacillus subtilis strain showed more degradation as compared to the E. Coli. strain.
Synthesis of Starch‐g‐Poly(glycidyl methacrylate) and Its Blending with Poly(ϵ‐caprolactone) and Nylon 610
Authors: Kim Gwan Young , Park Eun Soo , Kim Kwangsok , Chin In‐Joo , Yoon Jin San 
Published: May 2005

AbstractDifferent amounts of glycidyl methacrylate (GMA) were grafted onto corn starch dispersed in water or dimethyl sulfoxide (DMSO) to yield starch‐graft‐poly(glycidyl methacrylate) (ST‐g‐PGMA). ST‐g‐PGMAW, obtained by grafting PGMA onto corn starch that was dispersed in water, showed a higher PGMA grafting content and a lower content of the homopolymerized PGMA than ST‐g‐PGMAD, which was prepared in DMSO. The modified starches were blended with poly(ϵ‐caprolactone) (PCL) and nylon 610, respectively, and the tensile properties of the blends were measured by UTM. Mechanical properties of the biodegradable ST‐g‐PGMA/PCL blends were dependent on the PGMAD content grafted on starch. Without dramatic loss of the tensile properties of PCL, ST‐g‐PGMAW was melt blended with PCL. Meanwhile, an increase in the tensile modulus was observed in the ST‐g‐PGMAW/nylon 610 blend. When nylon 610 was reacted with ST‐g‐PGMAW in DMSO in the presence of triethylamine, the tensile modulus and strength were much higher than those of the pure nylon 610, and phase‐separated domains of starch were not observed microscopically.
Curing and Glass Transition of Epoxy Resins from Ester‐Carboxylic Acid Derivatives of Mono‐ and Disaccharides, and Alcoholysis Lignin
Authors: Hirose Shigeo , Hatakeyama Tatsuko , Hatakeyama Hyoe 
Published: May 2005

AbstractMono‐ and disaccharides (SAC) such as glucose (Glc), fructose (Frc) and sucrose (Suc), and also alcoholysis lignin (AL) were dissolved in ethylene glycol and each of the obtained mixtures was reacted with succinic anhydride to form a mixture of ester‐carboxylic acid derivatives such as SAC‐polyacid, SACPA, and AL‐polyacid, ALPA. Ethylene glycol‐polyacid (EGPA) was also prepared from ethylene glycol. Each of the obtained mixtures of ester carboxylic acid derivatives was reacted with ethylene glycol diglycidyl ether in the presence of a catalytic amount of dimethylbenzylamine to form ester‐epoxy resins. The molar ratios of epoxy groups to carboxylic acid groups ([EPOXY]/[ACID] ratios, mol mol−1) was maintained at 1.0. The contents of SACPA and ALPA in the mixtures of SACPA/EGPA, and ALPA/EGPA, respectively, were also varied from 0 to 100 %. The curing reaction of SucPA and ALPA was studied by differential scanning calorimetry (DSC). Activation energy of the curing reaction for the SucPA system was 80.5 kJ/mol. Thermal properties of epoxy resins were studied by DSC. Glass transition temperatures (Tg) decreased with increasing numbers of repeating units in ester chains between cross‐linking points, suggesting that ester chain lengths between cross‐linking points mainly affect the mobility of ester chains in epoxy resin networks.
Biodegradation of Plastics in Compost Prepared at Different Composting Conditions
Authors: Joo Sang Bum , Kim Mal Nam , Im Seung Soon , Yoon Jin San 
Published: May 2005

AbstractMaximum temperature during the thermophilic phase and moisture content were controlled in the course of composting to examine the effects of these composting conditions on the quality of the compost used for the evaluation of the biodegradability of plastics. The moisture content during composting was controlled at 65%, while keeping the maximum temperature below 46°C, 58°C and 70°C, respectively. In turn, the maximum temperature was controlled to be below 58°C, while maintaining the moisture content at 45%, 55% and 65% respectively. The number of microbial cells was examined in the five compost samples thus prepared. Biodegradation of cellulose, polycaprolactone and poly(butylene succinate‐co‐butylene adipate) was conducted in the five compost samples, and the consistency and reproducibility of the test results were explored.
Accelerated Microbial Degradation of Poly(L‐lactide)
Authors: Tokiwa Yutaka , Jarerat Amnat 
Published: May 2005

AbstractAcceleration of the biodegradation of poly(L‐lactide) (PLA) was studied. We found that the degradation rate of high molecular weight (1.3×105) PLA film was greatly increased by the addition of gelatin into the culture medium of the microorganisms. 100 mg of PLA film was almost completely degraded by the fungus, Tritirachium album (eukaryotic microorganisms), and by an actinomycete, Saccharothrix waywayandensis (prokaryotic microorganisms). In addition to gelatin, various insoluble proteins, peptides and amino acids also accelerate the biodegradation of PLA. Silk fibroin was the best inducer for the production of PLA‐degrading enzymes of an actinomycete, Amycolatopsis orientalis.
Rechnerische Behandlung der Verlagerung von Eigenspannungen in einem Stabmodell durch Überbelastung. Ein Beitrag zum mechanischen Schweißeigenspannungsbbau
Authors: Schimmöller H. 
Published: May 2005

AbstractDer Mechanismus der Überbelastung, hervorgerufen durch die überlagerung von Last‐ und Eigenspannungen, wird für ein eindimensionales Zugstabmodell mit elastisch‐idealplastischem Stoff‐verhalten mathematisch formuliert. Die Rechnung ergibt ein Gleichungssystem, das in Abhängigkeit von dem vorhandenen Eigenspannungszustand, der Fließgrenze und der Belastung die elastisch‐plastische überlagerung von Last‐ und Eigenspannungen vollständig beschreibt. Die durch örtliches Fließen veränderten ursprünglichen Eigenspannungen ergeben sich durch elastische Entlasten. Das allgemein gültige Gleichungssystem wird für symmetrische Eigenspannungsverteilungen spezialisiert. Zur Ergänzung der theoretischen Darstellung wird ein einfaches Beispiel ausführlich durchgerechnet.
Das Explosivschweißen — eine wesentliche Ergänzung zu den bestehenden Fügeverfahren
Authors: Prümmer R. 
Published: May 2005

AbstractDie Grundlagen des Explosivschweißens werden geschildert. Insbesondere wird auf die Bedeutung der Schweißparameter eingegangen. Eine einfache neue Methode zu deren Ermittlung wird beschrieben. Typische Schweißverbindungen mit und ohne Reaktionen in der Verbindungsschicht werden beispielhaft diskutiert. Ebenfalls werden typische Anwendungsfälle aufgezeigt.
C60 as a stationary phase for microcolumn liquid chromatographic separation of polycyclic aromatic hydrocarbons
Authors: Jinno Kiyokatsu , Yamamoto Kunihiko , Fetzer John C. , Biggs Wilton R. 
Published: May 2005

AbstractBuckminsterfullerene C60 was evaluated as a stationary phase for the microcolumn liquid chromatographic separation of polycyclic aromatic hydrocarbons. Material prepared from a soot extract was packed into a fused‐silica capillary, 13‐mm times; 0.53‐mm i. d. The chromatographic characteristics were examined. The results indicate that C60 can work as a liquid chromatographic stationary phase, offering a unique shape selectivity for polycyclic aromatic hydrocarbons compared with octadecylsilica and dicoronylene stationary phase.
High‐resolution separation and detection of DNA adducts of benzo[a]pyrene
Authors: Harvey Scott D. , Bean Roger M. , Udseth Harold R. 
Published: May 2005

AbstractAnalysis of DNA adducts as indicators of human exposure to environmental levels of carcinogenic compounds represents an extreme challenge for trace analyses to chemists. At environmental exposure levels of benzo[a]pyrene, one can expect less than one adduct per 107 base pairs, or roughly 30 femtomoles of adduct per mg DNA. Microcolumn separation techniques are ideally suited for the trace analysis of DNA adducts due to the high separation efficiency, enhanced mass flow sensitivity, and ease of interfacing with highly specific and sensitive mass spectrometric detectors. This study describes the analysis of benzo[a]pyrene‐adducted deoxyguanosine‐5′‐monophosphate with micellar electrokinetic capillary chromatographic separation followed by fluorescence detection. Alternatively, adducts can be cleaved from the DNA by treatment with acid, resulting in the formation of highly fluorescent benzo[a]pyrene tetrahydrotetrols. Analysis of the tetrahydrotetrols by either capillary zone electrophoresis or microcolumn HPLC with fluorescence detection is described. Detection limits for the benzo[a]pyrene tetrahydrotetrols with either of the aforementioned separation techniques were approximately 3 femtomoles.
Carbon‐13 NMR spectra of isomeric 2‐arylimidazopyridines
Authors: Tretyakov A. V. , Rudaya L. I. , El'tsov A. V. , Larin M. F. , Lopyrev V. A. 
Published: May 2005

AbstractThe 13C NMR spectra of some 2‐arylimidazo‐[4,5‐c]‐ and ‐[4,5‐b]‐pyridines and their protonated forms have been studied. The nitrogen atom of the pyridine ring has been shown to be the most basic nitrogen in these compounds.
NMR studies of phosphonate carbanions: Influence of substituents on 1J(PC) and 1J(CH) and some INDO calculations
Authors: Webb G. A. , Simonnin M.‐P. , Seyden‐Penne J. , Bottin‐Strzalko T. 
Published: May 2005

Abstract13C and 31P NMR data are reported for a series of phosphonate carbanions. In comparison with related uncharged molecules, the values of 1J(PC) are rather large. This is discussed with the help of some INDO‐SCPT spin‐spin coupling calculations, which reveal that while the positive contact term makes the dominant contribution to these couplings, the negative orbital term also plays an important role. The signs of 1J(PC) and 1J(CH) are predicted to be positive in all cases. Support for the proposal of a planar anionic carbon atom is forthcoming from the INDO‐SCPT calculations.
Carbon‐13 NMR of tertiary fluorosteroids as a stereochemical probe
Authors: Rozen Shlomo , Ben‐Shushan Giora 
Published: May 2005

AbstractThe 13C NMR spectra of tertiary fluorinated steroids possessing no functional groups in the vicinity of the fluorine have been measured. All α‐ and β‐carbons are deshielded by the fluorine atom. The γ‐carbons, however, are divided into two groups. The carbons gauche to the fluorine atom are all shielded by 1–8 ppm, whereas the γ‐carbons anti to the halogen are all deshielded by 2–5 ppm. Apart from the α‐Carbons, which have coupling constants of 170–180 Hz, all β‐Carbons are also coupled to the fluorine with a 2J(CF) value of approximately 20 Hz. The γ‐carbons gauche to the fluorine have a very small coupling constant (usually 0‐3 Hz), while the anti γ‐carbons are split by the fluorine by 6–8 Hz. Both chemical shifts and coupling constants can be used for the Stereochemical evaluation of fluorosteroids.
Investigation of the 31P NMR chemical shift dependence of phosphoryl compounds on the inductive and resonance effects of substituents
Authors: Rezvukhin A. I. , Dolenko G. N. , Krupoder S. A. 
Published: May 2005

AbstractLinear dual‐parameter equations relating the 31P NMR chemical shifts in a series of phosphoryl compounds XYZP = O (X, Y, Z = various organic substituents or halogens) with the sums of inductive (σI) and resonance (σ) constants of the substituents have been obtained. The direction of the influence of the inductive and resonance components of the electron demand of substituents, and their relative contributions to the δ31P values, have been evaluated. The nature of the resonance contribution is discussed on the basis of the dependence between δ31P values and the charge characteristics of the phosphorus atom (x‐ray P Kα shifts).
17O NMR Spectra of 1‐adamantylphosphoryl derivatives
Authors: Duddeck Helmut , Hanna Atef G. 
Published: May 2005

AbstractThe 17O chemical shifts and one‐bond phosphorus‐oxygen coupling constants of a series of 1‐adamantylphosphoryl derivatives are reported and discussed. It was found that a significant 2p electron transfer towards the phosphoryl oxygen in the phosphonic esters is clearly reflected by the 17O NMR parameters.
Proton NMR study of methyl‐ and fluoro‐substituted 6‐ and 7‐ethoxy‐1‐methoxytricyclo[3.3.0.02,8]oct‐3‐enes
Authors: Jans A. W. H. , Van Arkel B. , Osselton E. M. , Cornelisse J. 
Published: May 2005

Abstract1H NMR data (300 and 500 MHz) are reported for methyl‐ and fluoro‐substituted 6‐ and 7‐ethoxy‐1‐methoxytricyclo[3.3.0.02,8]oct‐3‐enes, products of the meta photocycloaddition of methyl‐ and fluoro‐anisoles to ethyl vinyl ether. COSY 45 (300 and 500 MHz) and COSY 90 (300 MHz) experiments were performed for the determination of the structures of these products.
Carbon‐13 NMR studies of primary amines and their corresponding 2,4,6‐trimethyl‐pyridinium salts
Authors: Balaban Alexandru T. , Dinculescu Antonie , Elguero José , Faure Robert 
Published: May 2005

AbstractThe 13C NMR chemical shifts of 37 N‐substituted 2,4,6‐trimethylpyridinium (TMP) salts with alkyl, aralkyl, aryl and heteroaryl N‐substituents are reported and discussed in comparison with those of the corresponding primary amines RNH2.