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Results 251 - 300 of 1418
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Ward Marty - - 2007
Homo- and heterochiral poly(mandelic acid)s (PMDAs) were synthesized under strongly acidic, mildly acidic, and nonacidic conditions. The water-soluble fractions of these polymers were evaluated with respect to their inhibitory activity against the human immunodeficiency virus (HIV-1). Polymers were prepared via a step-growth mechanism, yielding linear polyesters. The polymers were characterized ...
Deng Meng - - 2008
Previously we demonstrated the ability of ethyl glycinato substituted polyphosphazenes to neutralize the acidic degradation products and control the degradation rate of poly(lactic acid-glycolic acid) (PLAGA) by blending. In this study, blends of high strength poly[(50% ethyl alanato) (50% p-phenyl phenoxy) phosphazene] (PNEA(50)PhPh(50)) and 85:15 PLAGA were prepared using a ...
Huh Pilho - - 2007
Boronic acid-based sensors for saccharides have been developed via biocatalysis. The self-doped copolymer of poly(aniline-co-3-aminobenzeneboronic acid) [poly(aniline-co-AB)], with various mole ratios of two components, was synthesized by oxidative enzymatic polymerization using a natural biocatalyst such as horseradish peroxidase together with an anionic polyelectrolyte template (sulfonated polystyrene) under mild conditions (pH ...
Dräger Gerald - - 2007
The synthesis of a Ni-nitrilotriacetic acid (Ni-NTA) attached via a new tyrosine-based linker matrix on monolithic crosslinked poly(vinyl benzyl chloride)/poly(vinylpyrrolidinone) is described. This matrix is incorporated inside a microstructured PASSflow reactor which was used for automatic purification and immobilisation of His(6)-tagged proteins. These could be used as stable and highly ...
Jahno Vanusca Dalosto - - 2007
Polylactic acid is a polymer of great technological interest, whose excellent mechanical properties, thermal plasticity, and bioresorbability render it potentially useful for environmental applications, as a biodegradable plastic and as a biocompatible material in biomedicine. This article discusses the synthesis and characterization of poly-L-lactic acid, obtained through two synthetic routes: ...
Hove Lene Hystad - - 2007
OBJECTIVE: The aim of this study was to compare the protective effect of TiF(4), SnF(2), and NaF treatment on the development of erosion-like lesions in pellicle-covered human enamel. MATERIAL AND METHODS: Twelve human molars were each divided into 5 specimens, 4 of which were immersed in saliva for 2 h. ...
Bevilácqua Flávia M - - 2008
This study evaluated the resistance to demineralization and fluoride incorporation of enamel irradiated with Er:YAG. A total of 110 bovine teeth were selected and divided into eight groups: unlased, 37% phosphoric acid, and samples irradiated with the Er:YAG laser at several fluences (31.84 J/cm(2), 25.47 J/cm(2), 19.10 J/cm(2), 2.08 J/cm(2), ...
Sarasam Aparna R - - 2007
The preparation and characterization of porous scaffolds from chitosan-PCL blends by freeze extraction, freeze gelation and freeze drying is reported. Using freeze extraction, stable structures were obtained only from PCL, but these were not porous. No stable scaffolds were obtained using the freeze gelation process. Stable scaffolds of chitosan/PCL mixtures ...
Fang Jianmin J Center for Tropical and Emerging Global Diseases and Department of Cellular Biology, University of Georgia, Paul D. Coverdell Biomedical and Health Sciences Center, Athens, Georgia 30602, - - 2007
We report the cloning, expression, purification, and characterization of the Trypanosoma cruzi exopolyphosphatase (TcPPX). The product of this gene (TcPPX), has 383 amino acids and a molecular mass of 43.1 kDa. TcPPX differs from most exopolyphosphatases in its preference for short-chain polyphosphate (poly P). Heterologous expression of TcPPX in Escherichia ...
Xiao Yan - - 2007
A simple and rapid bulk-modification method based on adding an amphiphilic copolymer during the fabrication process was employed to modify PDMS microchips. Poly(lactic acid)-poly(ethylene glycol) (PLA-PEG) was used as the additive substance. Compared to the native PDMS microchips, both the contact angle and the EOF of the bulk-modified PDMS microchips ...
Tombul Mustafa - - 2007
In the title compound, poly[(mu3-boric acid)-mu4-maleato-dipotassium], [K2(C(4)H(2)O(4)){B(OH)3}]n, there are two independent K+ cations, one bonded to seven O atoms (three from boric acid and four from maleate), and the other eight-coordinate via three boric acid and four maleate O atoms and a weak eta(1)-type coordination to the C=C bond of ...
Yu Hui - - 2008
A biodegradable Copolymer of poly(lactic acid-co-lysine)(PLA-PLL) was synthesized by a modified method and novel Arginine-Glycine-Aspartic (RGD) peptides were chemical conjugated to the primary epsilon-amine groups of lysine components in four steps: I to prepare the monomer of 3-(Nepsilon-benzoxycarbonyl-L-lysine)-6-L-methyl-2,5-morpholinedione; II to prepare diblock copolymer poly(lactic acid-co-(Z)-L-lysine) (PLA-PLL(Z)) by ring-opening polymerization of ...
Kaneshiro Todd L - - 2007
Macromolecules with defined nanosizes--nanoglobules--were synthesized and characterized as novel drug carriers with precise molecular architectures. Poly-L-lysine dendrimers with a cubic octa(3-aminopropyl)silsesquioxane (OAS) core, (L-lysine 8-OAS, (L-lysine) 16-(L-lysine) 8-OAS, (L-lysine) 32-(L-lysine) 16-(L-lysine) 8-OAS, and (L-lysine) 64-(L-lysine) 32-(L-lysine) 16-(L-lysine) 8-OAS, were divergently synthesized by solution phase peptide chemistry in good yield and ...
Miyaki Kyo - - 2007
A novel polydimethylsiloxane (PDMS) surface modification method for microchip electrophoresis has been developed to make a stable and sufficient electroosmotic flow (EOF). Poly(l-glutamic acid) (PGA) which had ionizable carboxyl groups at a high pH-range was immobilized on the surface of microchannel fabricated with PDMS. The surface modification involved surface oxidation ...
Liu Bin - - 2008
This study deals with the fabrication of a peripheral nerve scaffold prepared with poly (lactic acid-co-glycolic acid) [PLGA] and acellularized pigskin collagen micro particles and the investigation of its sustained release property in vitro. We took bovine serum albumin [BSA] as model drug to investigate the sustained-release property of the ...
Fan Yanru - - 2007
The interaction of hydrophobically modified copolymers of acrylamide and acrylic acid, designated as PAM-C12-AA (X%) (X% indicates the percentage of acrylic acid unit and X = 5, 10, 20), with dimyristoylphosphatidylcholine (DMPC) vesicles has been studied. Complementary techniques including isothermal titration microcalorimetry (ITC), differential scanning calorimetry (DSC), turbidity measurement, calcein ...
Romberg Birgit - - 2007
Long-circulating liposomes, such as PEG-liposomes, are frequently studied for drug delivery and diagnostic purposes. In our group, poly(amino acid) (PAA)-based coatings for long-circulating liposomes have been developed. These coatings provide liposomes with similar circulation times as compared to PEG-liposomes, but have the advantage of being enzymatically degradable. For PEG-liposomes it ...
Zou Tao - - 2007
Novel cholic acid functionalized star oligo/poly(DL-lactide)s with different molecular weights were synthesized through the ring-opening polymerization of DL-lactide initiated by cholic acid. Compared with poly(DL-lactide), these star oligo/poly(DL-lactide)s show faster hydrolytic degradation rates, and the degradation mechanism changes from bulk erosion to surface erosion with decreasing molecular weight. Based on ...
Piskin Erhan - - 2007
Biomaterials are widely used in diverse applications as substances, materials or important elements of biomedical devices. Biodegradable polymers, both natural and synthetic, have been utilized in applications in which they act as temporary substitutes. Poly(alpha-hydroxy acids), especially lactic acids and glycolic acid and their copolymers with epsilon-caprolactone, are the most ...
Butler Mark J - - 2007
A poly(butyl methacrylate-co-methacrylic acid) (BMA-MAA) scaffold was fabricated by an in situ polymerization solvent casting/particulate leaching technique. It displayed high porosity (85-90%), pore interconnectivity, and a pore size range of 100-650 microm. Compression testing of the scaffolds demonstrated a dependence of the compressive stiffness on several fabrication variables including the ...
Verdelis Kostas K The Hospital for Special Surgery, 535 E. 70th Street, New York, NY 10021, - - 2007
Phosphorylation of the organic matrix proteins of dentin is important for the initiation of mineralization, but its relevance in later mineralization stages is controversial. The objective of this study was to analyze changes in the total matrix phosphate content during dentin development and to identify their origin. Amino acid and ...
Yamamoto Tatsuhiro - - 2007
Partially benzyl-esterified poly(ethylene glycol)-b-poly(aspartic acid) (PEG-P(Asp(Bzl))) having different hydrophobic inner-core structure were synthesized and analyzed. We obtained two types of the block copolymers for formation of polymeric micelle drug carriers; one had an amide-bond ratio of 1:3 (alpha/beta) in the poly(aspartic acid) residues through alkaline hydrolysis, and the other one ...
Kumar S Ashok - - 2008
Here, we described a new method for electrochemically selective detection of dopamine (DA). In this report, for the first time, electrochemical polymerization of 4-amino-1-1'-azobenzene-3,4'-disulfonic acid (acid yellow 9 dye (AY)) was carried out onto the surface of glassy carbon (GC) electrode and indium tin oxide coated electrode (ITO) from acidic ...
Wiegand A - - 2007
OBJECTIVE: The study aimed to analyse the effects of different brushing loads on abrasion of acid-softened and sound enamel surfaces. DESIGN: Sound and acid-softened surfaces of each 10 human enamel samples were submitted to brushing abrasion in an automatic brushing machine at 1.5 N (A), 2.5 N (B), 3.5 N ...
Grisorio Roberto - - 2007
A practical synthesis for 9,10-bis(alkoxyphenyl)-2,7-diiodophenanthrenes is described. 9,10-Bis(4-hexyloxyphenyl)-2,7-diiodophenanthrene was selectively obtained by a one-pot reaction of 10,10-bis-(4-hexyloxy-phenyl)-2,7-diiodo-10H-phenanthren-9-one with 1 equiv of triethylsilane in trifluoroacetic acid. The target molecular architecture was demonstrated to be a useful precursor for obtaining the corresponding poly(phenanthrene) and poly(phenanthrylene-vinylene).
Zhou Wen You - - 2008
This study focuses on the use of bio-nanocomposite microspheres, consisting of carbonated hydroxyapatite (CHAp) nanospheres within a poly(L: -lactide) (PLLA) matrix, to produce tissue engineering (TE) scaffolds using a modified selective laser sintering (SLS) machine. PLLA microspheres and PLLA/CHAp nanocomposite microspheres were prepared by emulsion techniques. The resultant microspheres had ...
Portilla-Arias Jose A - - 2007
The hydrolytic degradability and erythromycin release from stoichiometric ionic complexes of biotechnological poly(beta,L-malic acid)s and poly(gamma,D-glutamic acid)s with alkyltrimethylammonium surfactants were investigated. The influence of pH, temperature and antibiotic load on hydrolysis rate was examined. It was found that poly(malic acid) complexes degraded by a surface erosion mechanism at a ...
Paris S - - 2007
Infiltration of non-cavitated caries lesions with light-curing resins could lead to an arrest of lesion progression. The aim of this study was to evaluate the penetration of a conventional adhesive into natural enamel caries after pre-treatment with two different etching gels in vitro. Extracted human molars and premolars showing proximal ...
Bassiouny Mohamed A - - 2007
Evidence-based case reports and epidemiologic surveys have indicated an association between dental erosion and high consumption of acidulated carbonated beverages (ACBs). This study sought to monitor the effect of exposure to ACBs on the topography and geometrical profile of disassociated human dentition. Two representatives of ACBs, caramelized (ACCB) and non-caramelized ...
Kobayashi Shinzo - - 2007
An optically active helical poly(phenylacetylene) was synthesized by the copolymerization of phenylacetylenes bearing optically active hydroxy or ester groups obtained by the kinetic resolution of a racemic phenylacetylene with lipase; the helix-sense was inverted from one helix to another by the further chemical modification of the hydroxy groups with achiral ...
Wang Hua-Jie - - 2007
In our previous study, a three-dimensional zein porous scaffold with a compressive Young's modulus of up to 86.6+/-19.9 MPa and a compressive strength of up to 11.8+/-1.7 MPa was prepared, and was suitable for culture of mesenchymal stem cells (MSCs) in vitro. In this study, we examined its tissue compatibility ...
Griffin R C - - 2008
Estimation of age-at-death for skeletonised forensic remains is one of the most significant problems in forensic anthropology. The majority of existing morphological and histological techniques are highly inaccurate, and show a bias towards underestimating the age of older individuals. One technique which has been successful in forensic age estimation is ...
Fukushima Kazuki - - 2007
Stereoblock poly(lactic acid) (sb-PLA) is incorporated into a 1:1 polymer blend system of poly(L-lactic acid) (PLLA) and poly(D-lactic acid) (PDLA) that has a high molecular weight to study its addition effect on the stereocomplex (sc) formation of PLLA and PDLA. The ternary polymer blend films are first prepared by casting ...
Rizvi Syed Asad Ali - - 2007
In this work, six amino acid derived (L-leucinol, L-leucine, L-isoleucinol, L-isoleucine, L-valinol, and L-valine) polymeric chiral surfactants with carboxylate and sulfate head groups that were recently synthesized in our laboratory [30, 33, 35] are compared for the simultaneous enantioseparation of several groups of structurally similar analytes under neutral and basic ...
Silva Johanna A - - 2007
Poly-beta-hydroxyalkanoate (PHA) is a biodegradable polymer accumulated in intracellular granules by different bacterial species. Its physical and chemical properties are similar to those of petroleum-derived plastics. Material generated by the acid hydrolysis of wood was evaluated for use in the bacterial synthesis of PHA. Acid-hydrolyzed sawdust was prepared and adjusted ...
Majekodunmi A O - - 2007
Polymer modified calcium phosphate cements made with cement powders of varying tetracalcium phosphate [TTCP] content were prepared using two different molecular weight fractions of poly(acrylic acid) at four different concentrations. The ratio of the precursors (TTCP:DCPA) in the cement powder was found to influence the initial setting which decreased with ...
Yan Liuming - - 2007
Molecular simulation studies of the microstructure and of the proton transport properties of phosphoric acid solvated Nafion membrane are carried out. The ab initio calculations show that the phosphoric acid is a good solvent to promote the proton ionization of the sulfonic acid group, and only two phosphoric acid molecules ...
Zilberman Meital - - 2008
Poly(DL-lactic-co-glycolic acid) microspheres are prepared using a double-emulsion technique and are loaded with the model enzyme horseradish peroxidase (HRP). These microspheres can be used alone or as coatings for bioresorbable fibers that may be used as scaffolds for tissue regeneration applications. The present study focuses on the effect of the ...
Bae Younsoo - - 2007
Cancer treatment efficacy and safety of the environmentally sensitive polymeric micelle drug carriers were significantly increased by optimizing the number of ligands on their surface. These micelles were designed to target the cancerous tumors through the interaction between folate and its receptors that overexpress on the cancer cell membrane while ...
Kulshrestha Ankur S - - 2007
Lipase-catalyzed terpolymerizations were performed with the monomers trimethylolpropane (B3), 1,8-octanediol (B2), and adipic acid (A2). Polymerizations were performed in bulk, at 70 degrees C, for 42 h, using immobilized lipase B from Candida antartica (Novozyme-435) as a catalyst. To determine the substitution pattern of trimethylolpropane (TMP) in copolymers, model compounds ...
Arafat Ahmed - - 2007
Covalently attached organic monolayers on etched silicon nitride (SixN4; x >/= 3) surfaces were prepared by reaction of SixN4-coated wafers with neat or solutions of 1-alkenes and 1-alkynes in refluxing mesitylene. The surface modification was monitored by measurement of the static water contact angle, XPS, IRRAS, AFM, and ToF-SIMS, and ...
Hooper S - - 2007
OBJECTIVES: The consumption of acidic soft drinks continues to rise as do concerns regarding effects of frequent intake. The aim of the study was to determine the effect of acidic soft drinks containing food approved polymers, on dental enamel. METHODS: The study design was a single blind, randomised, five-treatment crossover ...
Tokiwa Yutaka - - 2007
The escalating problems regarding the treatment of plastic waste materials have led to development of biodegradable plastics. At present, a number of aliphatic polyesters; such as poly[(R)-3-hydroxybutyrate] (PHB), poly(l-lactide), polycaplolactone, poly(ethylene succinate) and poly(butylene succinate) have been developed. Among these aliphatic polyesters, PHB is one of the most attractive since ...
Seol Yeonee - - 2007
We have found strong supporting evidence for the helical structures of single-stranded nucleic acids by stretching individual molecules of polyadenylic acid [poly(A)] and polycytidylic acid [poly(C)]. Analyzing the force versus extension data using a two-state elastic model in which random-coil domains alternate with rigid helical domains allows one to extract ...
Lau Kenneth K S - - 2007
Initiated chemical vapor deposition (iCVD) is presented as an all-dry synthesis and coating method for applying methacrylic acid copolymers as pH-responsive controlled release layers. iCVD combines the strengths of liquid-phase chemical synthesis with a precision solvent-free chemical vapor deposition environment. Copolymers of methacrylic acid and ethyl acrylate were confirmed by ...
Chu Dafeng - - 2007
Huperzine A loaded poly(D,L-lactic-co-glycolic acid) (PLGA) microspheres were prepared by an oil/water (o/w) solvent evaporation technique. With a decrease of the ratio of o/w from 1 : 100 to 1 : 50, the encapsulation efficiency was reduced about 4%. Increasing the PVA concentration from 0.5 to 2% reduced the percentage ...
Ulukapi Hasmet - - 2007
Conservative techniques for treatment of discolored human enamel include in-office bleaching with heat-activated 35% hydrogen peroxide, Nightguard vital bleaching with 10% carbamide peroxide, and enamel microabrasion with 18% hydrochloric acid. OBJECTIVES: In this study, these bleaching techniques were performed on 30 extracted teeth to evaluate their effects on microhardness of ...
Fu Hui-Li - - 2007
Novel cholic acid functionalized branched oligo/poly(epsilon-caprolactone)s were synthesized through the ring-opening polymerization of epsilon-caprolactone initiated by cholic acid with hydroxyl groups. The molecular weight of the branched polymers can be adjusted by controlling the feed ratio of the initiator cholic acid to the monomer epsilon-caprolactone. Comparing with linear homopolymer poly(epsilon-caprolactone) ...
Guo Wen-Xun - - 2007
The drug release profiles of poly(dimer acid-dodecanedioic acid) P(DA-DDDA) copolymer containing 5% adriamycin hydrochloride (ADM) in vitro were evaluated. The biocompatibility of P(DA-DDDA) under mice skin was also evaluated, macroscopic observation and microscopic analysis demonstrated that the copolymer is biocompatible and well tolerated in vivo. Antitumor efficacy of P(DA-DDDA) copolymers ...
Cava D - - 2007
Inverse gas chromatography (IGC) has been used to characterise the surface properties of polycaprolactone (PCL) and poly(lactic acid) (PLA). The dispersive component of the surface free energy (gamma(S)(D)) was found to be very small for both of them--values close to 30 mJ/m(2) in the case of the PLA and ca. ...
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