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801.
Microencapsulation of neem (Azadirachta Indica A. Juss.) seed oil (NSO) was carried out by polyelectrolyte complexation of κ -carrageenan and chitosan. The microcapsules were crosslinked by using three different crosslinking agents - glutaraldehyde, genipin and tannic acid. The lowest and highest water uptake capacities were exhibited by glutaraldehyde and tannic acid crosslinked matrices, respectively. The release behavior of NSO from encapsulated crosslinked microcapsules followed the order: tannic acid > genipin > glutaraldehyde. Polyelectrolyte complex formation and its interaction with crosslinker was studied. Crosslinking improved thermal stability without affecting crystallinity. Roughness appeared on microcapsule's surface indicated interaction between microcapsules and crosslinker. 相似文献
802.
Abstract Sutures are sterile’ filaments used to close wounds and are made of either absorbable or nonabsorbable materials. The choice of suture materials for surgery is made mainly on the basis of biocompatibility and mechanical properties. The biological interaction with the tissues is considered from the point of view of the inflammatory reaction caused. An ideal suture is one that does not merely avoid negative reactions but also keeps a sterile environment and stimulates the process of healing. An absorbable suture is one which is degraded in body tissues to soluble products and disappears from the implant site, usually within 2 to 6 months. A nonabsorbable suture is resistant to biodegradation, becomes encapsulated in a fibrous sheath, and remains in the tissue as a foreign body unless it is surgically removed (e.g., skin sutures) or extruded. Sutures may be fabricated as monofilaments or multifilaments. The latter are generally braided but sometimes twisted or spun and may be coated with wax, silicone, or other polymers to decrease capillarity and improve handling properties. Hoffman [1] presented a survey on the medical applications of synthetic and natural fibrous materials made from such polymers as poly-(fluorocarbons), polyamides, polyolefins, polypeptides, and polysaccharides which are both nonbiodegradable or slowly biodegrad-ing and biodegradable fibers. Frazza [2] prepared a review on mechanical properties and sterilization of natural and synthetic absorbable and nonabsorbable suture materials. The present paper is a review on materials that have been in recent times as absorbable sutures 相似文献
803.
Vinod VT Saravanan P Sreedhar B Devi DK Sashidhar RB 《Colloids and surfaces. B, Biointerfaces》2011,83(2):351-298
An environmentally benign method for the synthesis of noble metal nanoparticles has been reported using aqueous solution of gum kondagogu (Cochlospermum gossypium). Both the synthesis, as well as stabilization of colloidal Ag, Au and Pt nanoparticles has been accomplished in an aqueous medium containing gum kondagogu. The colloidal suspensions so obtained were found to be highly stable for prolonged period, without undergoing any oxidation. SEM-EDXA, UV-vis spectroscopy, XRD, FTIR and TEM techniques were used to characterize the Ag, Au and Pt nanoparticles. FTIR analysis indicates that -OH groups present in the gum matrix were responsible for the reduction of metal cations into nanoparticles. UV-vis studies showed a distinct surface plasmon resonance at 412 and 525 nm due to the formation of Au and Ag nanoparticles, respectively, within the gum network. XRD studies indicated that the nanoparticles were crystalline in nature with face centered cubic geometry. The noble metal nanoparticles prepared in the present study appears to be homogeneous with the particle size ranging between 2 and 10 nm, as evidenced by TEM analysis. The Ag and Au nanoparticles formed were in the average size range of 5.5±2.5 nm and 7.8±2.3 nm; while Pt nanoparticles were in the size range of 2.4±0.7 nm, which were considerably smaller than Ag and Au nanoparticles. The present approach exemplifies a totally green synthesis using the plant derived natural product (gum kondagogu) for the production of noble metal nanoparticles and the process can also be extended to the synthesis of other metal oxide nanoparticles. 相似文献
804.
K. Bavya Devi Kulwant Singh N. Rajendran 《Journal of Sol-Gel Science and Technology》2011,59(3):513-520
In this study, the nanoporous zirconium titanate was prepared using sol–gel process and coated over 316L SS implants via dip-coating
technique. XRD patterns of zirconium titanate are crystalline and orthorhombic in structure. FT-IR spectra showed a broad
band between 3,500 and 3,300 cm−1, which was assigned to fundamental stretching vibrations of hydroxyl groups. The set of overlapping peaks in the range of
810–520 cm−1 are related to Zr–O and Zr–O–Ti groups. SEM-EDAX and TEM showed the surface morphology of coated zirconium titanate to be
porous and uniform. Excellent adhesion of the coating to the substrate has been achieved. The contact angle value was found
to be 12°. The coating acts as a barrier layer to the metallic implants and induces the formation of hydroxyapatite layer
on the metal surfaces. These results revealed that the nano zirconium titanate coated 316L SS exhibit higher bioactivity compared
to that of uncoated 316L SS. 相似文献
805.
T. Gomti Devi 《Journal of Raman spectroscopy : JRS》2008,39(3):427-432
The isotropic Raman component of the C = O stretching mode of ethyl acetate (EA) was analyzed using various polar and nonpolar solvents. It was found that the bandshape approaches towards Lorentzian at high dilution using the curve‐fitting method. The isotropic Raman band was also analyzed by estimating the correlation coefficient with reference to the Lorentzian lineshape using a simple method of linear‐curve fitting. The effects of dispersion and hydrodynamic forces on bandwidth were studied in details. The vibrational relaxation rate was studied using certain parameters and it was found that the microscopic based parameter can explain the complexities occurring in solute–solvent interactions. Copyright © 2007 John Wiley & Sons, Ltd. 相似文献
806.
We have adopted a modified combustion route, namely, a mixed fuel process (MFP) to prepare a novel series of nano-crystalline
single- and multiple-doped ceria compositions with controlled powder characteristics, large surface area, finer particle size,
high sinterability, and high oxide ion conductivity at intermediate temperatures (500–700 °C). Using the mixed fuel process,
we have prepared nano-particles of single- and multiple-doped ceria powders with dopants such as Ca, Gd, and Sm and a suitable
combination of the same. In the pursuit for identifying new oxide-ion-conducting materials in this family of oxides, we have
pursued the idea of co-doping effect on the single doped compositions with proper introduction of a second dopant. Effect
of these dopants on the thermal decomposition and physico–chemical characteristics of the precursor and the powders prepared
thereby were studied in detail. Finally, the effects of multiple co-doping on the microstructural and electrical properties
were compared to understand the origin of the effect of dopant characteristics on the oxide ion conductivity of Ce1−x
M
x
O2 solid solutions. Our experimental results established unequivocally that co-doping is very effective in identifying new materials
with remarkably high ionic conductivity with substantial reduction in the cost for technological applications. Among the studied
compositions, the maximum conductivity with minimum activation energy was observed for the triply co-doped CCGS composition
(; E
a = 0.56 eV), which is much higher compared to the conductivity exhibited by most of the reported co-doped ceria compositions.
In conclusion, an effective way to improve the oxide ion conductivity of ceria-based oxides by proper choice of dopants and
co-doping is achieved. 相似文献
807.
Indu Saxena Vijay Kumar Rikkam Devi 《Russian Journal of Physical Chemistry B, Focus on Physics》2018,12(1):17-27
Ultrasonic technique, transport properties and related acoustical parameters of 1,4-dioxane and N,N-dimethyl formamide were prepared of different % compositions at variable temperatures using tetra alkyl ammonium iodide salts (R4NI) of 0.14 M, to investigate inter-ionic interactions, molecular interactions, molecular rearrangement, molecular association etc. The densities were measured by using magnetic float densitometer. Transport properties provide a deep and meaningful insight of various interactions taking place between the binary liquid mixtures with salts. We have observed the influence of small as well as large alkyl chain length (R4N+), and extract the information with respect to various kinds of intermolecular interactions such as dipole-dipole, dipole-induced dipole, solute-solvent, dispersive type and H-bonding interaction between the components. Such observations in the presence of specific molecular interactions of binary solutions and structural effects were analyzed on the basis of measured and derived thermo-dynamical parameters. 相似文献
808.
Manju Bala Satish Kumar Rekha Devi Avni Khatkar V. B. Taxak Priti Boora S. P. Khatkar 《Journal of fluorescence》2018,28(3):775-784
A series of five new terbium(III) ion complexes with 4,4-difluoro-1-phenylbutane-1,3-dione (HDPBD) and anciliary ligands was synthesized. The composition and properties of complexes were analyzed by elemental analysis, IR, NMR, powder X-ray diffaraction, TG-DTG and photoluminescence spectroscopy. These complexes exhibited ligand sensitized green emission at 546 nm associated with 5D4?→?7F5 transitions of terbium ion in the emission spectra. The photoluminescence study manifested that the organic ligands act as antenna and facilitate the absorbed energy to emitting levels of Tb(III) ion efficiently. The enhanced luminescence intensity and decay time of ternary C2-C5 complexes observed due to synergistic effect of anciliary ligands. The CIE color coordinates of complexes came under the green region of chromaticity diagram. The mechanistic investigation of intramolecular energy transfer in the complexes was discussed in detail. These terbium(III) complexes can be thrivingly used as one of the green component in light emitting material and in display devices. 相似文献
809.
Sumit Ranjan Sahu D. Parimala Devi V. V. N. Phanikumar T. Ramesh N. Rajalakshmi G. Praveena R. Prakash Bijoy Das R. Gopalan 《Ionics》2018,24(11):3413-3421
Demand of low-cost carbonaceous anode materials for lithium-ion batteries has led to the development of anode materials from different bio-sources. In this regard, tamarind seed (skin) was used as a precursor to prepare disordered carbon as an anode material for lithium-ion batteries. The carbon was prepared through simple hydrothermal method and was characterized by X-ray diffraction (XRD), Raman spectroscopy, Brunauer–Emmett–Teller (BET) measurements, field emission scanning electron microscopy (FE-SEM), and transmission electron microscopy (TEM) techniques. It exhibited amorphous carbon particles arranged in a fiber-like morphology with high surface area of 508 m2 g?1. The binder content was optimized for the carbon to achieve high and stable capacity. Electrochemical performance of the as-prepared carbon with optimized binder content showed a stable reversible specific capacity of 224 mAhg?1 after 300 cycles at 1 C-rate. The stable cycling performance of carbon at high current rate is explained by electrochemical impedance spectroscopy (EIS) and FE-SEM data of cycled electrodes. The low cost and stable specific capacity make the carbon as potential anode material for lithium-ion battery. 相似文献
810.