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Gel System (gel + system)
Selected AbstractsThree Phase Microemulsion/Sol,Gel System for Aqueous C,C Coupling of Hydrophobic SubstratesEUROPEAN JOURNAL OF ORGANIC CHEMISTRY, Issue 14 2008Dmitry Tsvelikhovsky Abstract Heck, Stille, Suzuki and three-component coupling reactions with hydrophobic substrates have been carried out in water. The substrates are initially transformed by a general procedure into a microemulsion, which consists of nearly 90,% water with the aid of sodium dodecyl sulfate and either PrOH or BuOH. The surfactant carries the molecules of the substrates to Pd(OAc)2 entrapped within a hydrophobicitized silica sol,gel matrix where the coupling between the substrates is assumed to take place. The products are then returned by the surfactant into the microemulsion from which it can be released. The immobilized palladium catalyst is leach proof and recyclable. It can be used in various coupling processes at least six times without loss of activity. Experiments with D2O have revealed that the water does not take part in the coupling process, but it has an effect on the pore size of the sol,gel matrix, which hosts the palladium catalyst. (© Wiley-VCH Verlag GmbH & Co. KGaA, 69451 Weinheim, Germany, 2008) [source] Detection of muscarinic receptor subtypes in human urinary bladder mucosa: Age and gender-dependent modifications,,§NEUROUROLOGY AND URODYNAMICS, Issue 5 2008Nicola Arrighi Abstract Aims Muscarinic receptor subtypes expressed in the human urinary bladder mucosa were characterized, investigating whether there were gender-dependent differences and if aging could induce changes in their expression. Methods The study was carried out on 34 subjects, 22 men and 12 women, divided in four groups, based on gender and age. Gene expression was evaluated by quantitative RT-PCR. The Western blot was performed using the 4,12% NuPAGE Bis,Tris Gel System. Results The molecular expression of each subtype of the M1 receptor family was observed and it was not influenced either by gender or age. M2 receptor family transcripts revealed that both M2 and M4 were detected and that the M2 transcripts were modified by both gender and age. Indeed, M2 mRNA was lower in old rather than adult men (P,<,0.05), but higher in rather old than adult women (P,<,0.05). Further, adult men expressed more M2 mRNA than adult women (P,<,0.05), while the opposite was detected in old age (P,<,0.05). The Western blot followed by quantification confirmed that the mRNAs were translated into proteins, and that the M2 subtype showed similar modifications found at molecular level. Discussion The selective modification of M2 receptors observed at the urinary bladder mucosa levels indicates that this anatomical structure could play an active role in the pathophysiology of micturition and supports evidence suggesting an effect of antimuscarinic drugs at this level. Whether these results may influence the age-dependent development of micturition disorders remains to be determined. Neurourol. Urodynam. 27:421,428, 2008. © 2007 Wiley-Liss, Inc. [source] A Facile Reduction Procedure for N,N,-Bis[5-substituted salicylidene]m/p-phenylenediamines with Sodium Borohydride,Silica Gel System.CHEMINFORM, Issue 32 2004V. Sridharan No abstract is available for this article. [source] Oxygen-Generating Gel Systems Induced by Visible LightADVANCED FUNCTIONAL MATERIALS, Issue 5 2010Kosuke Okeyoshi Abstract Toward complete artificial photosynthesis systems to generate hydrogen and oxygen using visible light and water, oxygen-generating gel systems are designed and fabricated using the electrostatic interactions of ionic functional groups and steric effects of a polymer network. By using a graft polymer chain with Ru(bpy)32+ units as sensitizers to closely arrange RuO2 nanoparticles as catalyst, the functional groups transmit multiple electrons cooperatively to generate oxygen. In this paper, a novel strategy is shown to design a hierarchical network structure using colloidal nanoparticles and macromonomers. Such a soft material to oxidize water inside a hydrogel is useful as a solar-energy converting system. [source] Transverse imaging and simulation of dsDNA electrophoresis in microfabricated glass channelsELECTROPHORESIS, Issue 23 2008Ramsey I. Zeitoun Abstract We have observed the non-uniform distribution of DNA molecules during PAGE in a microfabricated system. Confocal laser scanning microscopy was used to visualize fluorescently labeled DNA during electrophoretic migration. The distribution of double-stranded DNA larger than 100,bp is observed to transition from a center-biased motion on the transverse plane 1,cm downstream from injection to an edge-biased motion 2,cm downstream. Although this distribution increased with increasing dsDNA size in a cross-linked gel, no similar distribution was found with the same dsDNA molecules in a linear polyacrylamide solution (6%). Simulations of DNA distribution in gels suggest that DNA distribution non-uniformities may be caused by biased electrophoretic migration resulting from motion in an inhomogeneous gel system. [source] Vertical agarose gel electrophoresis and electroblotting of high-molecular-weight proteinsELECTROPHORESIS, Issue 11 2003Chad M. Warren Abstract The electrophoretic separation of high-molecular-weight proteins (>,500 kDa) using polyacrylamide is difficult because gels with a large enough pore size for adequate protein mobility are mechanically unstable. A 1% vertical sodium dodecyl sulfate (SDS)-agarose gel electrophoresis (VAGE) system has been developed that allows titin (a protein with the largest known SDS subunit size of 3000,4000 kDa) to migrate over 10 cm in a ,13 cm resolving gel. Such migration gives clear and reproducible separation of titin isoforms. Proteins ranging in size from myosin heavy chain (,,220 kDa) up to titin can be resolved on this gel system. Electroblotting of these very large proteins was nearly 100% efficient. This VAGE system has revealed two titin size variants in rabbit psoas muscle, two N2BA bands in rabbit cardiac muscle, and species differences between titins from rat and rabbit muscle. Agarose electrophoresis should be the method of choice for separation and blotting of proteins with very large subunit sizes. [source] In Situ Synthesis, Characterization of SiPMo-X, and Different Catalytic Properties of SiPMo-X and SiPW-XEUROPEAN JOURNAL OF INORGANIC CHEMISTRY, Issue 15 2006Chunfeng Shi Abstract SBA-15 frameworks with encapsulated Keggin type heteropolyacids (HPAs) were synthesized in situ under strongly acidic conditions (pH,<,0). During the hydrolysis of tetraethyl orthosilicate (TEOS), a P- and a Mo source were added into the initial sol,gel system to form Keggin type HPAs. The texture of the final products was studied by the N2 adsorption,desorption isotherms and transmission electron microscopy (TEM), and their structure was systematically characterized by X-ray diffraction (XRD), UV/Vis diffuse reflectance- (DRS), infrared- (IR), and 31P magic angle spinning nuclear magnetic resonance (MAS NMR) spectroscopy. Characterization results suggest that the samples show very ordered hexagonal mesostructure, and the HPAs that are incorporated into the framework of meso-silica are insoluble during catalysis. Results of catalytic tests indicate that the materials demonstrated catalytic activity comparable with or even surpassing those of the bulk HPAs in catalytic tests implementing chemical reactions of bulky molecules (1,3,5-triisopropylbenzene cracking, esterification of benzoic acid with tert -butyl alcohol, and 2,3,6-trimethylphenol hydroxylation with H2O2). Additionally, some other properties, such as easy separation and stability when recycled, ensure their potential applications in the chemical industries. Here, we report not only the in situ synthesis and characterization of SiPMo-X, but also the difference in the catalytic properties of SiPMo-X and SiPW-X. (© Wiley-VCH Verlag GmbH & Co. KGaA, 69451 Weinheim, Germany, 2006) [source] Immunoisolation of two synaptic vesicle pools from synaptosomes: a proteomics analysisJOURNAL OF NEUROCHEMISTRY, Issue 6 2005Marco Morciano Abstract The nerve terminal proteome governs neurotransmitter release as well as the structural and functional dynamics of the presynaptic compartment. In order to further define specific presynaptic subproteomes we used subcellular fractionation and a monoclonal antibody against the synaptic vesicle protein SV2 for immunoaffinity purification of two major synaptosome-derived synaptic vesicle-containing fractions: one sedimenting at lower and one sedimenting at higher sucrose density. The less dense fraction contains free synaptic vesicles, the denser fraction synaptic vesicles as well as components of the presynaptic membrane compartment. These immunoisolated fractions were analyzed using the cationic benzyldimethyl- n -hexadecylammonium chloride (BAC) polyacrylamide gel system in the first and sodium dodecyl sulfate,polyacrylamide gel electrophoresis in the second dimension. Protein spots were subjected to analysis by matrix-assisted laser desorption ionization time of flight mass spectrometry (MALDI TOF MS). We identified 72 proteins in the free vesicle fraction and 81 proteins in the plasma membrane-containing denser fraction. Synaptic vesicles contain a considerably larger number of protein constituents than previously anticipated. The plasma membrane-containing fraction contains synaptic vesicle proteins, components of the presynaptic fusion and retrieval machinery and numerous other proteins potentially involved in regulating the functional and structural dynamics of the nerve terminal. [source] Textural properties of legume protein isolate and polysaccharide gelsJOURNAL OF THE SCIENCE OF FOOD AND AGRICULTURE, Issue 12 2006Eleousa A Makri Abstract The influence of legume proteins from lupin, pea and fababean on the formation of gels prepared by heat treatment in the absence or presence of xanthan gum, locust bean gum and NaCl was investigated. The resulting fracture and texture properties of gels not only are associated with the heating process used to form the gel but also depend on the conformational aspects of xanthan,locust bean gum in admixture with legume proteins, which after 10 days of aging reinforce the system. The fracture and textural properties are explained in terms of the effect of the protein,polysaccharide molecular structure and physicochemical conditions applied in the gel system during the gel preparation and measurements. Copyright © 2006 Society of Chemical Industry [source] Spatiotemporal control of vascular endothelial growth factor delivery from injectable hydrogels enhances angiogenesisJOURNAL OF THROMBOSIS AND HAEMOSTASIS, Issue 3 2007E. A. SILVA Summary. Therapeutic angiogenesis with vascular endothelial growth factor (VEGF) delivery may provide a new approach for the treatment of ischemic diseases, but current strategies to deliver VEGF rely on either bolus delivery or systemic administration, resulting in limited clinical utility, because of the short half-life of VEGF in vivo and its resultant low and transient levels at sites of ischemia. We hypothesize that an injectable hydrogel system can be utilized to provide temporal control and appropriate spatial biodistribution of VEGF in ischemic hindlimbs. A sustained local delivery of relatively low amounts of bioactive VEGF (3 ,g) with this system led to physiologic levels of bioactive VEGF in ischemic murine (ApoE,/,) hindlimbs for 15 days after injection of the gel, as contrasted with complete VEGF deprivation after 72 h with bolus injection. The gel delivery system resulted in significantly greater angiogenesis in these limbs as compared to bolus (266 vs. 161 blood vessels mm,2). Laser Doppler perfusion imaging showed return of tissue perfusion to normal levels by day 28 with the gel system, whereas normal levels of perfusion were never achieved with saline delivery of VEGF or in control mice. The system described in this article could represent an attractive new generation of therapeutic delivery vehicle for treatment of cardiovascular diseases, as it combines long-term in vivo therapeutic benefit (localized bioactive VEGF for 1,2 weeks) with minimally invasive delivery. [source] Preparation and Charactrization of Fibrous Crystals of Boron-containing MTW-type ZeoliteCHINESE JOURNAL OF CHEMISTRY, Issue 2 2004Mao-Ying Song Abstract Fibrous crystals of boron-containing MTW-type zeolite have been hydrothermally synthesized in B2O3 -SiO2 -HF-H2O gel system at 170 °C in 20 to 28 d by using 1, 4-diazabicyclo[2.2, 2]octane (DABCO) and methylamine as the co-template, and characterized with XRD, SEM, TEM, HRTEM and SAED. The results of characterizations show that B atoms are incorporated into the zeolite framework as tetrahedron of B(OSi)4. The fibrous single crystals of 5,50 ,m in length and 100,500 nm in width inter-grow along the c -axis of the zeolite, and the one dimension 12 oxygen ring channels are perpendicular to the fibber axis. [source] Oxygen-Generating Gel Systems Induced by Visible LightADVANCED FUNCTIONAL MATERIALS, Issue 5 2010Kosuke Okeyoshi Abstract Toward complete artificial photosynthesis systems to generate hydrogen and oxygen using visible light and water, oxygen-generating gel systems are designed and fabricated using the electrostatic interactions of ionic functional groups and steric effects of a polymer network. By using a graft polymer chain with Ru(bpy)32+ units as sensitizers to closely arrange RuO2 nanoparticles as catalyst, the functional groups transmit multiple electrons cooperatively to generate oxygen. In this paper, a novel strategy is shown to design a hierarchical network structure using colloidal nanoparticles and macromonomers. Such a soft material to oxidize water inside a hydrogel is useful as a solar-energy converting system. [source] Enhancing therapeutic loading and delaying transport via molecular imprinting and living/controlled polymerizationAICHE JOURNAL, Issue 1 2010Asa D. Vaughan Abstract This work demonstrates for the first time molecular imprinting using a "living/controlled" polymerization (LCP) strategy to enhance template loading/affinity and delay release in weakly crosslinked gels. Two gel systems were studied: poly(DEAEM- co -HEMA- co -PEG200DMA) gels imprinted for diclofenac sodium and poly(MAA- co -EGDMA) gels imprinted for ethyl adenine-9-acetate. Experimental evidence confirms that template diffusion coefficients within imprinted gels can be heavily influenced by template binding affinity. Recognition studies revealed significant increases in template loading/affinity with large increases in loading for LCP, and dynamic template release studies showed that imprinting via LCP extends the template release profile by twofold over that of imprinting via conventional free-radical polymerization techniques and fourfold over the control network (less Fickian and toward zero-order release with a profile coefficient of 0.70). Analysis of reaction kinetics indicated that LCP with reversible termination events increases the chemically controlled chain propagation mechanism, and that binding sites are formed during this phase of the polymerization. © 2009 American Institute of Chemical Engineers AIChE J, 2010 [source] Stability of 5-aminolevulinic acid in novel non-aqueous gel and patch-type systems intended for topical applicationJOURNAL OF PHARMACEUTICAL SCIENCES, Issue 8 2005Paul A. McCarron Abstract Aminolevulinic acid (ALA) stability within topical formulations intended for photodynamic therapy (PDT) is poor due to dimerisation to pyrazine-2,5-dipropionic acid (PY). Most strategies to improve stability use low pH vehicles, which can cause cutaneous irritancy. To overcome this problem, a novel approach is investigated that uses a non-aqueous vehicle to retard proton-induced charge separation across the 4-carbonyl group on ALA and lessen nucleophilic attack that leads to condensation dimerisation. Bioadhesive anhydrous vehicles based on methylvinylether-maleic anhydride copolymer patches and poly(ethyleneglycol) or glycerol thickened poly(acrylic acid) gels were formulated. ALA stability fell below pharmaceutically acceptable levels after 6 months, with bioadhesive patches stored at 5°C demonstrating the best stability by maintaining 86.2% of their original loading. Glycerol-based gels maintained 40.2% in similar conditions. However, ALA loss did not correspond to expected increases in PY, indicating the presence of another degradative process that prevented dimerisation. Nuclear magnetic resonance (NMR) analysis was inconclusive in respect of the mechanism observed in the patch system, but showed clearly that an esterification reaction involving ALA and both glycerol and poly(ethyleneglycol) was occurring. This was especially marked in the glycerol gels, where only 2.21% of the total expected PY was detected after 204 days at 5°C. Non-specific esterase hydrolysis demonstrated that ALA was recoverable from the gel systems, further supporting esterified binding within the gel matrices. It is conceivable that skin esterases could duplicate this finding upon topical application of the gel and convert these derivatives back to ALA in situ, provided skin penetration is not affected adversely. © 2005 Wiley-Liss, Inc. and the American Pharmacists Association J Pharm Sci 94:1756,1771, 2005 [source] SENSORY CHARACTERIZATION OF TEXTURE AND FLAVOR OF HIGH VISCOSITY GELS MADE WITH DIFFERENT THICKENERS,JOURNAL OF TEXTURE STUDIES, Issue 4 2000NIINA KÄLVIÄINEN ABSTRACT Four thickeners (pectin, gelatin, starch and gelatin + starch) and two aroma concentrations (1.4 and 0.7 mL aroma / 1 kg candy base) were used for manufacturing high viscosity gel systems, i.e. strawberry candies. The salient texture and flavor attributes of the samples were identified and evaluated by a trained descriptive panel. The thickeners strongly affected texture and flavor attributes of the samples, while the two aroma concentrations did not differentiate between samples. Each thickener used produced its own characteristic texture. The gels with weak and fragile texture had stronger flavor intensities and tart flavor than the gels with strong and cohesive texture. Because of the strong interaction between texture and flavor, the results have major implications for the production of high viscosity gels such as candies. [source] Novel Gelling Systems of , -, , - and , -Carrageenans and their Composite Gels with Cellulose Using Ionic LiquidMACROMOLECULAR BIOSCIENCE, Issue 4 2009Kamalesh Prasad Abstract Gels of three types of carrageenans (, -, , - and , -), as well as their composite gels with cellulose, were prepared using an ionic liquid, 1-butyl-3-methylimidazolium chloride (BMIMCl), by a heating-cooling process. , -Carrageenan gave the formation of hard gel while the other two carrageenans gave the formation of softer gels with BMIMCl. The gels were characterized by X-ray diffraction (XRD), thermal analysis (TGA and DSC), scanning electron microscope (SEM) and compressive testing. The results indicated that, among the three types of carrageenans, , - and , -carrageenans gave better miscible gels with BMIMCl, followed by , -carrageenan. On the other hand, , -carrageenan gave a better miscible composite gel with cellulose and BMIMCl, followed by , - and , -carrageenans. The stress-strain curves indicated that the mechanical properties of the above gel systems on the compressive mode were much better than those of the hydrogels of , - and , -carrageenans as well as the cellulose gel with BMIMCl. [source] Self-Assembly of Two-Component Gels: Stoichiometric Control and Component SelectionCHEMISTRY - A EUROPEAN JOURNAL, Issue 2 2009Andrew Abstract Two-component systems capable of self-assembling into soft gel-phase materials are of considerable interest due to their tunability and versatility. This paper investigates two-component gels based on a combination of a L -lysine-based dendron and a rigid diamine spacer (1,4-diaminobenzene or 1,4-diaminocyclohexane). The networked gelator was investigated using thermal measurements, circular dichroism, NMR spectroscopy and small angle neutron scattering (SANS) giving insight into the macroscopic properties, nanostructure and molecular-scale organisation. Surprisingly, all of these techniques confirmed that irrespective of the molar ratio of the components employed, the "solid-like" gel network always consisted of a 1:1 mixture of dendron/diamine. Additionally, the gel network was able to tolerate a significant excess of diamine in the "liquid-like" phase before being disrupted. In the light of this observation, we investigated the ability of the gel network structure to evolve from mixtures of different aromatic diamines present in excess. We found that these two-component gels assembled in a component-selective manner, with the dendron preferentially recognising 1,4 - diaminobenzene (>70,%), when similar competitor diamines (1,2- and 1,3-diaminobenzene) are present. Furthermore, NMR relaxation measurements demonstrated that the gel based on 1,4-diaminobenzene was better able to form a selective ternary complex with pyrene than the gel based on 1,4-diaminocyclohexane, indicative of controlled and selective ,,, interactions within a three-component assembly. As such, the results in this paper demonstrate how component selection processes in two-component gel systems can control hierarchical self-assembly. [source] | ||||||||||||||||||||||||||||