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1.
G. Archana K. Sabina S. Babuskin K. Radhakrishnan Mohammed A. Fayidh P. Azhagu Saravana Babu M. Sivarajan M. Sukumar 《Carbohydrate polymers》2013
In the present investigation, the polysaccharide/mucilage from waste of Abelmoscus esculentus by modification in hot extraction using two different solvents (Acetone, Methanol) were extracted, characterized and further compared with seaweed polysaccharide for their potential applications. The percentage yield, emulsifying capacity and swelling index of this mucilage were determined. The macro algae and okra waste, gave high % yield (22.2% and 8.6% respectively) and good emulsifying capacity (EC% = 52.38% and 54.76% respectively) with acetone, compared to methanol (11.3% and 0.28%; EC% = 50%) (PH = 7) while swelling index was greater with methanol than acetone extracts respectively. The infrared (I.R.) spectrum of the samples was recorded to investigate the chemical structure of mucilage. Thermal analysis of the mucilage was done with TGA (Thermal Gravimetric Analyzer) and DSC (Differential Scanning Calorimeter) which showed both okra and algal polysaccharide were thermostable hydrogels. 相似文献
2.
Effect of a small molecule on diffusion and swelling properties of selected polysaccharide gel beads
The effect of a small molecule (e.g., sodium fluorescein, SF) on the swelling properties of and diffusion from calcium polysaccharide (alginate or pectin) gel beads was investigated. The gel beads were prepared by ionotropic gelation, soaked in different concentrations of SF solution, and then dried. The swelling behavior and release of SF from the dried beads were investigated. After soaking in SF, the beads swelled to sizes that depended on the initial concentration of SF. However, the size of the dried beads was independent of the SF concentration. The swelling of the beads occurred quite rapidly and reached a maximum within 2 h. Although most beads swelled to a size which was less than their original size of wet beads, some of them swelled much more than their original wet size. Higher concentration of SF and lower concentration of sodium alginate provided a greater increase in weight. The release profile of SF from dried gel beads in water consists of a burst or a very rapid release phase during the first 60 min followed by a much slower release phase. The similarity of the relative weight increase and release profiles of SF, suggests that swelling might contribute to release of SF, particularly during the burst phase. 相似文献
3.
The swelling behavior and network parameters of guar gum/poly(acrylic acid) semi-interpenetrating polymer network hydrogels 总被引:4,自引:0,他引:4
Guar gum/poly(acrylic acid) semi-interpenetrating polymer network (IPN) hydrogels have been prepared via free radical polymerization in the presence of a crosslinker of N,N′-methylene bisacrylamide (MBA). The kinetics of swelling and the water transport mechanism were studied as a function of the composition of the hydrogels and the pH of the swelling medium. Hydrogels showed enormous swelling in aqueous medium and displayed swelling characteristics, which were highly dependent on the chemical composition of the hydrogels and pH of the medium in which hydrogels were immersed (ionic strength I = 0.15 mol/L). The semi-INP hydrogels were characterized by evaluating various network parameters such as average molecular weight between crosslinks (Mc) crosslink density (ρ) and mesh size ξ. 相似文献
4.
Liladhar B. Kumbhare Beena G. Singh G. Kedarnath K. Indira Priyadarsini 《Inorganica chimica acta》2011,374(1):69-78
A variety of platinum(II) complexes of methimazole (2-mercapto-1-methylimidazole; HImS = neutral form and ImS = thiolate form), coordinated in both thione and thiolate forms, have been isolated by reacting methimazole with [PtCl(terpy)]Cl (terpy = 2,2′:6′,2″ terpyridine), [PtCl2(bipy)] (bipy = bipyridine), [PtCl2(o-phen)] (o-phen = o-phenanthroline), [PtCl2(CH3CN)2] and [PtCl2(COD)] (COD = 1,5-cyclooctadiene). These complexes were characterized by electronic absorption, IR and NMR (1H, 13C, 195Pt) spectroscopies. Molecular structure of [Pt(bipy)(HImS)2]Cl2·3H2O (3a·3H2O) has been established by single crystal X-ray crystallography. Platinum thiolate complex, [Pt(ImS)2(HImS)2] (5), could be obtained by treatment of [Pt(HImS)4]Cl2 with sodium methoxide in methanol. The solution of 5 in organic solvents yielded bi- and tri-nuclear platinum complexes. The effect of diimine ligands on oxidation of methimazole moiety in the complexes has been studied by electrochemical oxidation and pulse radiolytic oxidation employing specific one-electron oxidant, radical. 相似文献
5.
Xanthan-g-poly(acrylamide) was synthesized employing microwave-assisted and ceric-induced graft copolymerization, and was characterized by FT-IR, DSC, XRD and SEM studies. Matrix tablets of diclofenac sodium were formulated using graft copolymer as the matrix by direct compression technique. Release behavior of the graft copolymer was evaluated using USP type-II dissolution apparatus in 900 ml of phosphate buffer (pH 6.8), maintained at 37 °C and at 50 rpm. Microwave-assisted grafting provided graft copolymer with higher % grafting in a shorter time in comparison to the ceric-induced grafting. The % grafting was found to increase with the increase in the power of microwave and/or time of exposure. The matrix tablets were found to release the drug by zero-order kinetics, and the faster release of drug was observed from the graft copolymer matrix as compared to the xanthan gum matrix. It was observed that grafting reduces the swelling, but increases the erosion of xanthan gum. 相似文献
6.
In this study, carboxymethyl chitosan was prepared, characterized, and then photo-induced graft copolymerized with poly(ethylene glycol) under a nitrogen atmosphere in aqueous solution using 2,2-dimethoxy-2-phenyl acetophenone (DMPA) as the photo-initiator. The grafting copolymerization process was confirmed and the resulting copolymers were characterized using differential scanning calorimetry (DSC), FTIR spectroscopy, 2D-X ray diffraction, and elemental analysis. The kinetics of the grafting reactions was also studied. Under the applied experimental conditions, the optimum grafting values were obtained at: CMCs = 0.2 g, PEGA = 249 mM, DMPA = 10.4 mM at a 2 h reaction time. Some of the resulting copolymers were selected and used in the presence of methylene bisacrylamide (MBA) as a crosslinking agent to develop pH-responsive hydrogel matrices. The swelling characteristics and the in vitro release profiles of 5-fluorouracil (5-FU), as a model drug, from the hydrogels were investigated. The results revealed that the hydrogel matrices developed in this study can be customized to act as good candidates in drug delivery systems. 相似文献
7.
Ponnurengam Malliappan Sivakumar Stefania CometaMichele Alderighi Veluchamy PrabhawathiMukesh Doble Federica Chiellini 《Carbohydrate polymers》2012,87(1):353-360
An antibacterial dimethylamino-chalcone embedded multiblock copolymer (PCL-PEG) was synthesized and characterized using FT-IR, 1H NMR, SEM and SEC and the compound was characterized using FT-IR, 1H NMR, and 13C NMR. A 10% copolymer composite was prepared and casted as film to be used as a biomaterial and the copolymer films without the compound acted as control. TGA, DSC, AFM, SEM and EDAX analysis were performed for the above samples. Surface roughness (Ra) of the copolymer composite film was less when compared to the copolymer film which indicated the proper distribution of chalcone in the composite film. copolymer composite film was hydrophilic compared to copolymer film. Antibacterial adhesion studies were performed for copolymer composite polymer film and evaluated using CFU measurement and SEM analysis. Copolymer composite film shows promising antibacterial adhesion compared to the copolymer film. Hence the copolymer composite film can be used as a new biomaterial endowed with antibacterial properties. 相似文献
8.
Janette Wallis 《American journal of primatology》1992,28(2):101-113
Behavioral observations were made on thirteen female and seven male adult group-living chimpanzees (Pan troglodytes). The behavioral data were analyzed as a function of the day of the females' menstrual cycles to explore the possible interrelationship between genital swelling and sociosexual behavior of female chimpanzees. Copulatory behavior was confined almost entirely to the period of genital swelling and the occurrence of male-to-female genital inspection (both female- and male-initiated) was negatively correlated with the days from swelling onset, i.e., as the presumed day of ovulation approached, genital inspection decreased, while copulatory behavior increased. In addition, more females groomed their male cagemates during the luteal phase than in the follicular phase of their cycles, whereas male-to-female grooming was positively correlated with the progress of the cycle, with peaks during the time of swelling onset and menstruation. The profile of sociosexual behavior observed throughout the menstrual cycle suggested that, although chimpanzees exhibit an extended period of sexual receptivity and genital swelling, the presumed fertile period is not concealed. The role of genital swelling in chimpanzees is discussed in relation to the possible hormonal effect on female sexuality and the evolution of chimpanzee mating strategies. © 1992 Wiley-Liss, Inc. 相似文献
9.
Bao JS Sun M Corke H 《TAG. Theoretical and applied genetics. Theoretische und angewandte Genetik》2002,104(2-3):408-413
Starch comprises about 90% of milled rice, so that the eating and cooking quality of rice is mainly affected by the starch
properties. In the present paper, we analyzed the genetical behavior of gelatinization temperature tested by differential
scanning calorimetry (DSC), gel texture, and the swelling volume (SV) of indica rice with an incomplete cross of 4×8 parents. A genetic model which can dissect the effects of triploid seed, the cytoplasm,
and the maternal plant on the endosperm traits was used. The results indicated that peak temperature (Tp), conclusion temperature (Tc) and enthalpy (ΔH) were controlled by three types of genetic effects: seed direct (endosperm) effects, cytoplasmic effects
and maternal effects. No cytoplasmic effects for the onset temperature (To), hardness and SV, and no maternal effects for cohesiveness were found. The additive variances (V
A
+V
Am
) were larger than the dominance variances (V
D
+V
Dm
) for all the traits except for Tc, which suggested that selection could be applied for the starch properties in early generations. The total narrow-sense heritability
for each parameter was over 60%, indicating that selection advances were predictable in the early generations for these traits.
Received: 17 February 2001 / Accepted: 17 May 2001 相似文献
10.
Graft copolymer of k-carrageenan and N,N-dimethylacrylamide has been synthesized by free radical polymerization using peroxymonosulphate/glycolic acid redox pair in an inert atmosphere. The grafting parameters i.e. grafting ratio, add on and efficiency decrease with increase in concentration of k-carrageenan from 0.6 to 1.4 g dm−3 and hydrogen ion from 3 × 10−3 to 7 × 10−3 mol dm−3, but these grafting parameters increase with increase in concentration of N,N-dimethylacrylamide from 16 × 10−2 to 32 × 10−2 mol dm−3, and peroxymonosulphate from 0.8 × 10−2 to 2.4 × 10−2 mol dm−3. The metal ion sorption, swelling behaviour and flocculation properties have been studied. The intrinsic viscosity of pure and grafted samples has been measured by using Ubbelohde capillary viscometer. Flocculation capability of k-carrageenan and k-carrageenan-g-N,N-dimethylacrylamide for both coking and non-coking coals has been studied for the treatment of coal mine waste water. The graft copolymer has been characterized by Infrared (IR) spectroscopy and thermogravimetric analysis. 相似文献
11.
Virginie Dulong Georgeta MocanuLuc Picton Didier Le Cerf 《Carbohydrate polymers》2012,87(2):1522-1531
The synthesis of thermosensitive copolymers based on pullulan and polyether amine was performed in water using a water-soluble carbodiimide and N-hydroxysuccinimide as activators. Jeffamine® M2005 was chosen as a polyether to impart thermosensitive character to the copolymer. Pullulan was modified into carboxymethylpullulan, to bring carboxylate groups to the polysaccharide so as to further the grafting reaction. The copolymers were characterized by FT-IR, 1H NMR spectroscopy and molecular weights measurements (by SEC coupled with MALS/DRI/Viscometer lines). The thermosensitive behaviour of CMP-g-M2005 copolymers was studied by fluorescence spectroscopy of pyrene, by rheometry and microDSC measurements. The sol-gel transition temperature was found dependent on the solvent, the grafting degree of M2005 and the concentration of the copolymer. For example it was 35 °C in water, 28 °C in acid buffer (0.1 M, pH 5.4) and 26 °C in saline phosphate buffer (0.15 M, pH 7.4) for a grafting degree of 0.20 at a concentration of 5 wt%. 相似文献
12.
The chain conformation of a heteropolysaccharide Erwinia gum (EG) consisting of Glc, Gal, Fuc, and GlcA in aqueous solution was investigated by using viscometry and static and dynamic light scattering. The Huggins constants k′ ranging from 0.31 to 0.35, and the larger second virial coefficient A2 of the order of 10−4 and even 10−3 mol g−2 cm3 for EG fractions having different molecular weights in 0.03 M NaCl aqueous solution at 25 °C, suggested that 0.03 M NaCl aqueous solution is a good solvent for EG polysaccharide. Smidsrød’s ‘B-value’ characterizing chain stiffness was estimated to be 0.028-0.045 for EG fractions indicating that the backbone of EG polysaccharide is semi-stiff having similar stiffness to the semi-stiff Alginate and CMC. The hydrodynamic factor ρ (1.69-1.89), Flory-Fox factor Φ, and the product of ρΦ/NA (0.16-0.22) also confirmed the semi-stiffness of EG polysaccharide chains. Compared with general flexible polymers, the first remarkable shear-thinning and then Newtonian flowing behaviors in steady shear tests for EG polysaccharides were ascribed to the alignment of extended semi-stiff chains on shearing. The dynamic oscillatory shear experiments indicated that addition of certain amount of NaCl effectively prohibited its gelation in pure water even at high concentration and low temperature for long time, suggesting that 0.03 M NaCl aqueous solution of EG has good stability and ability of antigelation, and thus is a promising additive in food field. 相似文献
13.
The aim of this paper is to investigate the structures and properties of epoxidized linseed and Pongamia glabra oils (LOE/POE), their derived products—epoxy-polyols (HLOE/HPOE), epoxy-polyurethanes (EU = LOPU/POPU) and EU coatings. Changes in epoxy equivalent, iodine value, hydroxyl value and percent saturation of oil backbone in due course of epoxidation and hydroxylation reactions, were plotted as a function of time. Spectral (IR, 1H NMR and 13C NMR), physico-chemical and thermal (TGA and DSC) analyses of aforementioned resins were performed by standard methods. Physico-mechanical and chemical resistance tests reveal that coatings of LOPUs perform better than those of POPUs. It was found that properties of oil epoxy-polyurethane coatings are mainly governed by: (i) fatty acid composition and nature of starting oils, (ii) extent of epoxidation, (iii) number and location of hydroxyls and residual double bonds in the final product and (iv) the presence of long dangling chains. PO, HLOE and LOPUs exhibit good antibacterial activity against Escherichia coli at very small MIC. These EU systems can be safely employed unto 220 °C. 相似文献
14.
The aim of functional tissue engineering is to repair and replace tissues that have a biomechanical function, i.e., connective orthopaedic tissues. To do this, it is necessary to have accurate benchmarks for the elastic, permeability, and swelling (i.e., biphasic-swelling) properties of native tissues. However, in the case of the intervertebral disc, the biphasic-swelling properties of individual tissues reported in the literature exhibit great variation and even span several orders of magnitude. This variation is probably caused by differences in the testing protocols and the constitutive models used to analyze the data. Therefore, the objective of this study was to measure the human lumbar disc annulus fibrosus (AF), nucleus pulposus (NP), and cartilaginous endplates (CEP) biphasic-swelling properties using a consistent experimental protocol and analyses. The testing protocol was composed of a swelling period followed by multiple confined compression ramps. To analyze the confined compression data, the tissues were modeled using a biphasic-swelling model, which augments the standard biphasic model through the addition of a deformation-dependent osmotic pressure term. This model allows considering the swelling deformations and the contribution of osmotic pressure in the analysis of the experimental data. The swelling stretch was not different between the disc regions (AF: 1.28±0.16; NP: 1.73±0.74; CEP: 1.29±0.26), with a total average of 1.42. The aggregate modulus (Ha) of the extra-fibrillar matrix was higher in the CEP (390 kPa) compared to the NP (100 kPa) or AF (30 kPa). The permeability was very different across tissue regions, with the AF permeability (64 E−16 m4/N s) higher than the NP and CEP (~5.5 E−16 m4/N s). Additionally, a normalized time-constant (3000 s) for the stress relaxation was similar for all the disc tissues. The properties measured in this study are important as benchmarks for tissue engineering and for modeling the disc's mechanical behavior and transport. 相似文献
15.
Physically cross-linked novel block copolymer hydrogels with tunable hydrophilic properties for biomedical applications were synthesized by controlled radical polymerization of polyurethane macroiniferter and (2,2-dimethyl-1,3-dioxolane) methyl methacrylate. The block copolymers were converted to hydrogels by the selective hydrolysis of poly[(2,2-dimethyl-1,3-dioxolane) methyl methacrylate] block to poly(glycerol methacrylate). The block copolymerization has been monitored by monomer conversion and molecular weight increase as a function of time. It was observed that the polymerization proceeded with a characteristic living behavior where both monomer conversion and molecular weight increased linearly, with increasing reaction time. The resulting hydrogels were investigated for their equilibrium water content (EWC), dynamic water contact angles, swelling kinetics, thermodynamic interaction parameters, plasma protein adsorption, and platelet adhesion. Similar to our previous mechanically responsive hydrogels (Mequanint, K.; Sheardown, H. J. Biomater. Sci. Polym. Ed. 2005, 10, 1303-1318), the present results indicated that block copolymer hydrogels have excellent hydrophilicity and swelling behavior with improved modulus of elasticity. The equilibrium swelling was affected by the hydrolysis time, block length of poly(glycerol methacrylate), temperature, and the presence of soluble salts. Fibrinogen adsorption and platelet adhesion were significantly lower for the hydrogels than for the control polyurethane, whereas albumin adsorption increased for the hydrogels in proportion to the contents of poly(glycerol methacrylate). These hydrogels have potential in a number of biomedical applications such as drug delivery and scaffolds for tissue engineering. 相似文献
16.
The purpose of this study is to develop novel colon-specific drug delivery systems with pH-sensitive swelling and drug release properties. Methacrylic-type polymeric prodrugs with different content levels of 5-amino salicylic acid (5-ASA) were synthesized by free radical copolymerization of metacrylic acid (MAA), polyethylene glycol monomethacrylate (PEGMA), and a methacrylic derivative of 5-ASA (methacryloyloxyethyl 5-amino salicylate [MOES]). The copolymers were characterized, and the drug content of the copolymers was determined. The effect of copolymer composition on the swelling behavior and hydrolytic degradation was studied in simulated gastric fluid (SGF, pH 1.2) and simulated intestinal fluid (SIF, pH 7.2). The swelling and hydrolytic behavior of the copolymers was dependent on the content of MAA groups and caused a decrease in gel swelling in SGF or an increase in gel swelling in SIF. Drug release studies showed that increasing content of MAA in the copolymer enhances the hydrolysis in SIF but has no effect in SGF. The results suggest that hydrogen-bonded complexes are formed between MAA and PEG pendant groups and that these pH-sensitive systems could be useful for preparation of a controlled-release formulation of 5-ASA. 相似文献
17.
Jasaswini Tripathy Dinesh Kumar Mishra Mithilesh Yadav Kunj Behari 《Carbohydrate polymers》2010,79(1):40-46
An unreported graft copolymer of N,N-dimethylacrylamide (DMA) with chitosan has been synthesized under nitrogen atmosphere using peroxymonosulphate/mandelic acid redox pair. The effect of reaction conditions on grafting parameters i.e. grafting ratio, efficiency, conversion, add on and homopolymer has been studied. Experimental results show that maximum grafting has been obtained at 1.0 g dm−3 concentration of chitosan, 30 × 10−2 mol dm−3 concentration of N,N-dimethylacrylamide and 7.0 × 10−3 mol dm−3 concentration of hydrogen ion. It has also been observed that grafting ratio, add on, conversion and efficiency increase upto 3.2 × 10−3 mol dm−3 of mandelic acid, 12.0 × 10−3 mol dm−3 of potassium peroxymonosulphate, 150 min of time and 40 °C of temperature. Grafted polymer has been characterized by FTIR spectroscopy and thermogravimetric analysis. Water swelling capacity of chitosan-g-N,N-dimethylacrylamide has been determined. It has been observed that the graft copolymer is thermally more stable than parent backbone. 相似文献
18.
S. Jarrett Howell 《Inorganica chimica acta》2005,358(13):3711-3723
A series of new thiophene amides containing a pyridine ring has been synthesized and characterized. Single crystal X-ray structures have been determined for four of the new substances which show two distinct patterns of hydrogen-bonding. The crystal structure of the copper (II) complex of one of the ligands shows that the bonding is O,N in a square planar geometry with perchlorate ions in the axial positions. The new compounds do not undergo electropolymerization due to primary oxidation of the amide function but tuning of the amide group by introduction of an electron-withdrawing group on the pyridine ring allows electropolymerization to occur. 相似文献
19.
Carboxymethylated cyclosophoraoses (CM-Cys) were synthesized by chemical modification of a family of neutral cyclosophoraoses isolated from Rhizobium leguminosarum biovar trifolii. Structural analyses of the CM-Cys were carried out using NMR and FTIR spectroscopies, and the molecular weight distributions were confirmed with MALDI-TOF mass spectrometry. Based on structural characterization, native cyclosophoraoses were successfully substituted with carboxymethyl groups at the OH-4 and OH-6 of the glucose residues with degrees of substitution (DS) ranging from 0.012 to 0.290. CM-Cys was also used as a host for the inclusion complexation with hydrobenzoin (HB) and N-acetyltryptophan (N-AcTrp) as guest molecules. NMR spectroscopic analyses of the complexes showed that the CM-Cys induced chemical shifts of some protons of the guest molecules upon the complexation. Phase solubility studies of the guest molecules by CM-Cys were performed using HPLC, and the results were compared with those of native cyclosophoraoses. The solubility of HB and N-AcTrp was enhanced by the CM-Cys about 5.1- and 299-fold, respectively. 相似文献
20.
Microbial solubilization of coal has been considered as a promising technology to convert raw coal into valuable products. In the present study, initially a total of 50 different aerobic bacterial and fungal isolates have been isolated from soil, coal and water samples of Dulmial Coal Mines, Chakwal, Pakistan, but on the basis of solubilization potential, only four isolates were selected for further study. The intensity of biosolubilization was measured by determining the weight loss of the coal pieces, which was observed to be about 25.93% by Pseudomonas sp. AY2, 36.36% by Bacillus sp. AY3 and 50% by Trichoderma sp. AY6, while Phanerochaete sp. AY5 showed maximum coal solubilization potential i.e. 66.67% in 30 days. UV/Vis spectrum revealed an increase in the pattern of absorbance of all treated samples compared to control referring to solubilization. Fourier transform infrared spectroscopy indicated alterations in the structure of treated coal in comparison to control coal suggesting breakdown in the complex structure of coal. The major absorbance bands in infrared spectroscopy for solubilization product were attributed to carbonyl (1,600 cm?1), hydroxyl (3,450 cm?1), cyclane (2,925 cm?1), ether linkage (1,000–1,300 cm?1), carboxyl (3,300–2,500 cm?1) and side chains of aromatic ring (1,000–500 cm?1). The presence of microorganisms and surface erosion of coal residues compared to control samples were observed by scanning electron microscopy, which suggested that isolated microorganisms were able to survive in coal for a longer period of time. Therefore, the present study concluded that microorganisms isolated from coal mines have excellent potential for coal solubilization which is considered as a crucial step in coal methanogenesis allowing them to be used successfully for in situ methane production to meet future energy demands. 相似文献