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Results 201 - 250 of 1409
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Niu Xufeng - - 2008
To design novel bioinspired polymeric material, poly(D,L-lactic acid) (DL-PLA) was on the base and modified in the bulk. Firstly, maleic anhydride (MA) groups were introduced to the side chain of DL-PLA by the way of melting free radical copolymerization using benzoyl peroxide as an initiator. Then, to neutralize the acid ...
Lambert Jean-François - - 2008
The present paper offers a review of recent (post-1980) work on amino acid adsorption and thermal reactivity on oxide and sulfide minerals. This review is performed in the general frame of evaluating Bernal's hypothesis of prebiotic polymerization in the adsorbed state, but written from a surface scientist's point of view. ...
Kuryatnyk T - - 2008
Phosphogypsum (calcium sulfate) is a naturally occurring part of the process of creating phosphoric acid (H(3)PO(4)), an essential component of many modern fertilizers. For every tonne of phosphoric acid made, from the reaction of phosphate rock with acid, commonly sulfuric acid, about 3t of phosphogypsum are created. There are three ...
Cheng Lei - - 2008
OBJECTIVE: To investigate the effect of chemical compounds of Galla chinensis and their combined effects with fluoride on remineralization of artificial early enamel caries. METHOD: Bovine enamel blocks with in vitro produced initial lesion were used. The lesions were subjected to a pH-cycling regime for 12 days. Each daily cycle ...
Ogliari Fabrício Aulo - - 2008
OBJECTIVES: The aim of this study was to synthesize an acidic monomer using an alternative synthetic pathway and to evaluate the influence of the acidic monomer concentration on the microtensile bond strength to dentin. METHODS: The intermediary 5-hydroxypentyl methacrylate (HPMA) was synthesized through methacrylic acid esterification with 1,5-pentanediol, catalyzed by ...
Preechaworapun Anchana - - 2008
An alternative method of a protein immunosensor has been developed at boron-doped diamond (BDD) electrode material. In order to construct the base of the immunosensor, o-aminobenzoic acid (o-ABA) was electropolymerized at an electrode by cyclic voltammetry. The poly-o-ABA-modified BDD was characterized by scanning electron microscopy (SEM) and X-ray photoelectron spectroscopy ...
Liu Guoguang - - 2008
The feasibility of a previously established method based on ozonolysis and hydrogenation reactions for the production of 9-hydroxynonanoic acid from oleic acid has been demonstrated. Metal catalyzed lactonization conditions have been used to convert 9-hydroxynonanoic acid into 1,11-dioxacycloicosane-2,12-dione, which is a potential monomer in the synthesis of polylactones. The structure ...
de Medeiros Carmen L S G - - 2008
The aim of this study was to measure the demineralization capacity of 37% phosphoric acid on bovine enamel at different time-points after bleaching with 30% carbamide peroxide. Five, 4 x 4-mm sections were obtained from the enamel of 10 bovine incisors. After applying 30% carbamide peroxide (Vivastyle) for 90 min, ...
Hoyer Herbert - - 2008
Microparticles were formulated by incorporation of the model protein horseradish peroxidase in (thiolated) chitosan and (thiolated) poly(acrylic acid) via co-precipitation. Dried protein/polymer complexes were ground with an air jet mill and resulting particles were evaluated regarding size distribution, shape, zeta potential, drug load, protein activity, release pattern, swelling behaviour and ...
Faragher Robert J - - 2008
For the introduction of additional analysis protocols of tethered molecules, a method is presented to prepare functionalized, deuterated oligo(ethylene glycols) from ethylene glycol-d4. Partial oligomerization of ethylene glycol-d4 and conversion to ditosylates is accompanied by coupling reactions to prepare doubly benzyl protected oligo(ethylene glycols) with two to five repeating units. ...
Michailof Chrysa - - 2008
Using caffeic acid and p-hydroxybenzoic acid as templates, two molecularly imprinted polymers (MIPs) were prepared that were used for isolation of polyphenols from olive mill waste water samples (OMWWs) without previous pre-treatment. For the preparation of the caffeic acid MIPs 4-vinylpyridine, allylurea, allylaniline and methacrylic acid were tested as functional ...
Dziak Katherine L - - 2008
Charged amino acids such as arginine, lysine, glutamic acid, and aspartic acid are abundant in noncollagenous proteins that regulate mineralization. Synthetic peptide forms of these amino acids have been shown to affect crystal growth in precipitation of mineral crystals in solution. However, little is known about the effects of these ...
Magalhães Ana Carolina - - 2008
The objective of this study was to assess the salivary residual effect of fluoride dentifrice on human enamel subjected to an erosive challenge. This crossover in situ study was performed in two phases (A and B), involving ten volunteers. In each phase, they wore acrylic palatal appliances, each containing 3 ...
Asselin Marie-Eve - - 2008
PURPOSE: The purpose of this in vitro study was to investigate and compare the microleakage-occurring after the placement of a light-curing sealant-to unground permanent enamel which had been previously conditioned using 3 different application protocols. METHODS: Sixty-three molars were randomly distributed in 3 different groups according to the application protocol ...
Lepri Taísa Penazzo - - 2008
BACKGROUND: Salivary contamination is one of the factors that can disturb the sealing process and interfere in the longevity of pit and fissure sealants. Erbium : yttrium-aluminum-garnet (Er : YAG) laser could influence the bond strength of enamel and increase the acid resistance. PURPOSE: To evaluate the influence of Er ...
Ray Debajyoti - - 2008
Intravenous administration of 5-fluorouracil (5-FU) for colon cancer therapy produces severe systemic side-effects due to its cytotoxic effect on normal cells. The main objective of the present study was to develop novel oral site-specific delivery of 5-FU to the colon with less drug being released in the stomach or small ...
Aguilar-Mendoza Jose A - - 2008
OBJECTIVE: To compare the effect of self-etching primers and phosphoric acid on the wettability and roughness of smear layer-covered and smear layer-free dentin. MATERIALS AND METHOD: Three self-etching primers (Clearfil SE Bond, AdheSE, and Xeno III) and 10% (w/w) phosphoric acid (H(3)PO(4)) solution were evaluated. The substrates were midcoronal dentin ...
Sasaki Luis H - - 2008
Er:YAG laser has been studied as a potential tool for restorative dentistry due to its ability to selectively remove oral hard tissue with minimal or no thermal damage to the surrounding tissues. The purpose of this study was to evaluate in vitro the tensile bond strength (TBS) of an adhesive/composite ...
Thi Tran Hang - - 2008
Poly(4-hydroxycinnamic acid) (P4HCA), poly(3-hydroxycinnamic acid) (P3HCA), poly(3-methoxy-4-hydroxycinnamic acid) (PMHCA) and poly(3,4-dihydroxycinnamic acid) (PDHCA) were synthesized by the thermal poly-condensation of the corresponding monomers, which are lignin precursors, coumaric acid derivatives consisting of cinnamoyl groups and different position and number of OH groups. The solubility of the homo-polymers in organic solvents ...
Pulat Mehlika - - 2008
Polyacrylamide (PAAm), polyacrylic acid (PAA), poly(acrylamide-co-itaconic acid) (PAAmIA) and poly(acrylic acid-co-itaconic acid) (PAAIA) hydrogels were prepared via free-radical polymerization using ethylene glycol dimethacrylate (EGDMA) as cross-linker. The variations of swelling percentages with time and pH were determined for these hydrogels at 37 degrees C. PAAmIA was found as the most ...
Li Yan - - 2008
Novel functionalized poly(p-phenylene ethynylene)s (PPEs) bearing facially amphiphilic cholic and deoxycholic acid units are synthesized by a Pd-catalyzed Sonogashira cross-coupling reaction. Some interesting properties, particularly their optical and self-assembly characteristics, are unraveled. The PPEs that carry bile acid substituents exhibit remarkable solvatochromism in a wide range of solvent systems, and ...
Espinosa Roberto - - 2008
The goal of this in vitro study was to identify the topographical features of the enamel surface deproteinized and etched with phosphoric acid (H3PO4) compared to phosphoric acid alone. Ten extracted lower first and second permanent molars were polished with pumice and water, and then divided into 4 equal buccal ...
Matsumoto Fukashi - - 2008
Novel [6,6]-phenyl-C61-butyric acid methyl ester (PCBM) analogues containing benzo[b]thiophene (3a, 3b) and thieno[3,2-b]thiophene (3c, 3d) were synthesized and characterized. The morphology of the thin films prepared from the mixtures of these methanofullerenes with regioregular poly(3-hexylthiophene) (P3HT) was investigated by AFM measurement and UV-Vis absorption spectroscopy. A solubility test of these ...
Natarajan Anupama - - 2008
Biodegradable scaffolds such as poly(lactic acid) (PLA), poly(lactic-co-glycolic acid) (PLGA) or poly(glycolic acid) (PGA) are commonly used materials in tissue engineering. The chemical composition of these scaffolds changes during degradation which provides a differential environment for the seeded cells. In this study we have developed a simple and relatively high-throughput ...
Lee Yuhan - - 2008
Pluronic mimicking poly(ethylene oxide)-poly(propylene oxide)-poly(ethylene oxide) (PEO-PPO-PEO) triblock copolymer having multiple hydroxyl groups in the PPO middle segment (core-functionalized Pluronic: CF-PLU) was synthesized for conjugation of doxorubicin (DOX). DOX was conjugated on the multiple hydroxyl groups of CF-PLU via an acid-labile hydrazone linkage (CF-PLU-DOX). In aqueous solution, CF-PLU-DOX copolymers self-assembled ...
Lin Song - - 2008
Intelligent gene delivery systems based on physiologically triggered reversible shielding technology have evinced enormous interest due to their potential in vivo applications. In the present work, an acid-labile block copolymer consisting of poly(ethylene glycol) and poly(2-(dimethylamino)ethyl methacrylate) segments connected through a cyclic ortho ester linkage (PEG- a-PDMAEMA) was synthesized by ...
Krasko Michal Y - - 2007
Pasty biodegradable polymers that can be mixed with drugs at room temperature and injected to tissue as neat composition are advantageous as they allow simple preparation and delivery of drugs, particularly for heat sensitive drugs. A series of biodegradable pasty poly (ester-anhydride)s were prepared from alkanedicarboxylic acids and ricinoleic acid ...
Davies R - - 2008
OBJECTIVE: To assess the erosive potential of a number of commercially available sour sweets in the laboratory. METHODS: The erosive potential was assessed by measuring the pH, neutralisable acidity and ability to erode permanent and deciduous enamel. These parameters were compared to those of an orange juice positive control. RESULTS: ...
Dayem Raad Niama - - 2009
This study proposes a new application for the neodymium:yttrium-aluminum-garnet (Nd:YAG) laser in conservative dentistry, which is represented by the removal of collagen network from acid-etched dentin. Thirty extracted human upper premolars were selected to be given standardized buccal and lingual class V cavities. The teeth were randomly divided into three ...
Davis Rachael E - - 2007
BACKGROUND: Calcium in acidic beverages can decrease a person's risk of experiencing dental erosion. The authors compared the pHs and titratable acidities of commercially available calcium-fortified and unfortified 100 percent juices, and enamel and root surface lesion depths after they were exposed to different juices. METHODS: The authors measured the ...
Rathke Andreas - - 2007
The aim of this in vitro study was to determine the diffusion of 2-hydroxyethyl methacrylate (HEMA) released from different bonding systems (BS) through dentin. Occlusal cavities with a remaining dentin thickness (RDT) of 0.5 mm (n=90) and 0.25 mm (n=80), respectively, were prepared in dentin discs of non-carious human molars. ...
Bakry Ahmed Samir - - 2007
PURPOSE: The aim of this study was to evaluate the effect of Er:YAG laser ablation on the microstructure of the dentin/adhesive interface after acid-base challenge in vitro. MATERIALS AND METHODS: Thirty-two extracted third molars were used. One pair of disk-shaped specimens was obtained from the midcoronal dentin of each tooth. ...
Chunmuang Siriwan - - 2007
This study aimed to determine the anti-erosive effects of xylitol, fluoride and a xylitol/fluoride combination used as an additive in an acidic drink or as mouthrinse after enamel was exposed to an acidic drink, in vitro. Human third molars were divided into 7 groups (A-G). Samples from groups A to ...
Zhang Guodong - - 2008
There is much interest in the development of a nanoscale drug delivery system with MRI visibility to optimize the delivery efficiency and therapeutic efficacy under image guidance. Here we report on the successful fabrication of nanoscale micelles based on biodegradable poly( L-glutamic acid)- b-polylactide (PG- b-PLA) block copolymer with paramagnetic ...
Müller Werner E G - - 2008
Bioencapsulation is an intriguing way to immobilize biological materials, including cells, in silica, metal-oxides or hybrid sol-gel polymers. Until now only the sol-gel precursor technology was utilized to immobilize bacteria or yeast cells in silica. With the discovery of silicatein, an enzyme from demosponges that catalyzes the formation of poly(silicate), ...
Mizuhashi H - - 2008
The purpose of this study was to investigate how the characteristics of a poly-l-lactic acid mini-plate changed with dynamic loading in an environment with hydrolytic degradation. A mandible osteosynthesis model was prepared with specimen poly-l-lactic acid mini-plates to simulate sagittal splitting ramus osteotomy. The model was then subjected to dynamic ...
Wagstaff Jane L - - 2008
We report the successful application of selective excitation sculptured TOCSY NMR (SXS-TOCSY) to identify individual solution components from a heterogeneous system using selectively acquired (1)H NMR spin system patterns. SXS-TOCSY application is illustrated by detection of the simultaneous presence of poly-beta-(1,6)-N-acetylglucosamine (PNAG) and poly(glycerol phosphate) teichoic acid (TA) carbohydrate polymer ...
Williams Alicia A - - 2008
Novel fluorescent chiral molecular micelles (FCMMs) were synthesized, characterized, and employed as chiral selectors for enantiomeric recognition of non-fluorescent chiral molecules using steady state fluorescence spectroscopy. The sensitivity of the fluorescence technique allowed for investigation of low concentrations of chiral selector (3.0 x 10(-5) M) and analyte (5.0 x 10(-6) ...
García-Zubiri Iñigo X - - 2007
The complexation of beta-carboline-3-carboxylic acid N-methylamide (betaCMAM) with the sodium salts of the nucleotides polyadenylic (Poly A), polycytidylic (Poly C), polyguanylic (Poly G), polythymidylic (Poly T) and polyuridylic (Poly U) acids, and with double stranded (dsDNA) and single stranded deoxyribonucleic acids (ssDNA) was studied at pH 4, 6 and 9. ...
Lee Sang-Jin - - 2007
The present research describes synthesis of highly sinterable, nano-sized hydroxyapatite (HAp) powders using a wet chemical route with recycled eggshell and phosphoric acid as calcium and phosphorous sources. The raw eggshell was easily turned to CaO by the calcining process, and phosphoric acid was mixed with the calcined eggshell by ...
Jaklenec Ana - - 2008
Biodegradable scaffolds play an important role in tissue engineering by providing physical and biochemical support for both differentiated and progenitor cells. Here, we describe a novel method for incorporating proteins in 3D biodegradable scaffolds by utilizing protein-loaded microspheres as the building blocks for scaffold formation. Poly(l,d-lactic-co-glycolic acid) (PLGA) microspheres containing ...
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 - - 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 ...
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