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排序方式: 共有681条查询结果,搜索用时 15 毫秒
101.
We report the intercalation of dexamethasone sodium phosphate drug in Mg/Al layered double hydroxides (LDHs) through co-precipitation technique. The as-synthesized nanohybrid was characterized by XRD, FTIR and thermal analysis techniques, which reveal that the dexamethasone phosphate anions are accommodated within the brucite layers. The shifting in the stretching frequency of phosphate anion of the drug provides strong evidence that the drugs are bonded to LDHs through electrostatic force. The surface charge analysis suggested the possibility of charge manipulation in LDHs system by varying intercalated anions. In-vitro release study of as-synthesized nanohybrid particles suggests a significant reduction in release rate of dexamethasone phosphate anions from Mg/Al–Dexa LDHs and is due to confinement of drugs in the interlayer. The mechanism of drugs diffusion in nanohybrid is studied by using dissolution–diffusion kinetic model, which reveals that it is probably due to dissolution and intra-particle diffusion of anions in the physiological medium. 相似文献
102.
The flow and heat transfer characteristics in the cooling of a heated surface by impinging slot jets have been investigated numerically. Computations are done for vertically downward-directed two-dimensional slot jets impinging on a hot isothermal surface at the bottom and confined by a parallel adiabatic surface on top. Some computations are also performed where the jet is vertically upward, with an impingement plate at the top. The principal objective of this study is to investigate the associated heat transfer process in the mixed-convective regime. The computed flow patterns and isotherms for various domain aspect ratios (4–10) and for a range of jet exit Reynolds numbers (100–500) and Richardson numbers (0–10) are analyzed to understand the mixed-convection heat transfer phenomena. The local and average Nusselt numbers and skin friction coefficients at the hot surface for various conditions are presented. It is observed that for a given domain aspect ratio and Richardson number, the average Nusselt number at the hot surface increases with increasing jet exit Reynolds number. On the other hand, for a given aspect ratio and Reynolds number, the average Nusselt number does not change significantly with Richardson number, indicating that the buoyancy effects are not very significant in the overall heat transfer process for the range of jet Reynolds number considered in this study. Also, for the same problem configuration, the average Nusselt number does not change significantly when the jet is moving upward or downward. 相似文献
103.
Binary mixtures of particles of the same size but of different densities are fluidized in a 15 cm diameter column with a perforated plate distributor and two coaxial promoters. In the present work an attempt has been made to study the fluidization and the segregation characteristic of density-variant solids of the same size in terms of segregation distance. The dimensionless segregation distance has been correlated with other dimensionless groups relating to various system parameters: ratio of the density of jetsam particles to that of flotsam, initial static bed height, height of layer of particles above the bottom grid, superficial gas velocity, and average density of the mixture on the basis of the dimensional analysis approach for both un-promoted and promoted beds. Correlations have also been developed with the above system parameters by using an artificial neural network approach for different types of fluidized beds, and the findings with respect to both approaches have been compared with each other. The values of segregation distance for promoted beds have also been compared with those for the un-promoted bed in this work. 相似文献
104.
The elastic–plastic adhesive contact of rough surfaces is extended to include asymmetric distribution of asperity heights using the Weibull distribution with skewness as the key parameter to characterize asymmetry. The well-established elastic adhesion index and plasticity index are used to consider the different conditions that arise as a result of varying load and material parameters. The loading and unloading behaviour for different combinations of adhesion index, plasticity index and skewness values are obtained as functions of mean separation between the surfaces. It is seen that surfaces with negative skewness experience higher adhesion compared to surfaces with positive or zero skewness. 相似文献
105.
Ken-Tye Yong Yudhisthira Sahoo Mark T. Swihart Paul M. Schneeberger Paras N. Prasad 《Topics in Catalysis》2008,47(1-2):49-60
Seeded growth of gold nanorods (NRs) has been accomplished in a micellar medium containing mixed surfactants or a high salt
concentration. Cetyl trimethylamoniumbromide (CTAB) forms micelles upon which the growth of rod shaped gold nanoparticles
occurs. AgNO3 is introduced into the growth solution to enhance the formation of NRs. The roles of non-ionic surfactants such as Tween
and Triton, and of electrolytes such as sodium chloride and potassium chloride have been examined. As the concentration of
these additives in the growth solution is increased, the aspect ratio of the NRs increases to a critical limit, after which
it decreases again. Upon carefully controlling the content of Triton X-100 or Tween 20 in the growth solution, these non-ionic
surfactants assisted in fine-tuning the shape of gold NRs (e.g. rectangular or “dogbone”). The growth pattern of the NRs fits
into the model of a soft template formed by the mixture of CTAB and non-ionic surfactants. 相似文献
106.
The aim of this study was to investigate the antioxidant and antimicrobial activity of chitosan, EDTA, eugenol and peppermint essential oil and their effect on color and oxidative stability of chicken noodles stored at 35 ± 2 °C. Results indicated that among the four preservatives, eugenol treatment exhibited higher ABTS+ (2-2-azinobis-3ethylbenthiazoline-6-sulphonic acid) radical cation activity (89.54%), DPPH (1, 1-diphenyl-2-picrylhydrazil) (51.30%) and superoxide anion scavenging activity (66.82%). Total polyphenol content was also higher in eugenol treated samples. The samples treated with eugenol and chitosan protect against an increase lightness (L-value) and decrease in redness (a) and yellowness (b) values during storage. However, pH value was highest in noodles with chitosan treatment while TBARS (2-thiobarbituric acid reacting substances) and FFA (Free fatty acids) contents were lowest in noodles with eugenol irrespective of storage periods. Eugenol treatment also showed positive impact on microbiological quality and sensory attributes. In conclusion, eugenol has more potential as a natural preservative to increase shelf-life of chicken noodles. 相似文献
107.
Singh A Dilnawaz F Mewar S Sharma U Jagannathan NR Sahoo SK 《ACS applied materials & interfaces》2011,3(3):842-856
Exercising complementary roles of polymer-coated magnetic nanoparticles for precise drug delivery and image contrast agents has attracted significant attention in biomedical applications. The objective of this study was to prepare and characterize magnetic nanoparticles embedded in polylactide-co-glycolide matrixes (PLGA-MNPs) as a dual drug delivery and imaging system capable of encapsulating both hydrophilic and hydrophobic drugs. PLGA-MNPs were capable of encapsulating both hydrophobic and hydrophilic drugs in a 2:1 ratio. Biocompatibility, cellular uptake, cytotoxicity, membrane potential, and apoptosis were carried out in two different cancer cell lines (MCF-7 and PANC-1). The molecular basis of induction of apoptosis was validated by Western blotting analysis. For targeted delivery of drugs, targeting ligand such as Herceptin was used, and such a conjugated system demonstrated enhanced cellular uptake and an augmented synergistic effect in an in vitro system when compared with native drugs. Magnetic resonance imaging was carried out both in vitro and in vivo to assess the efficacy of PLGA-MNPs as contrast agents. PLGA-MNPs showed a better contrast effect than commercial contrast agents due to higher T(2) relaxivity with a blood circulation half-life ~ 47 min in the rat model. Thus, our results demonstrated the dual usable purpose of formulated PLGA-MNPs toward either, in therapeutics by delivering different hydrophobic or hydrophilic drugs individually or in combination and imaging for cancer therapeutics in the near future. 相似文献
108.
Bao H Pan Y Ping Y Sahoo NG Wu T Li L Li J Gan LH 《Small (Weinheim an der Bergstrasse, Germany)》2011,7(11):1569-1578
The covalent functionalization of graphene oxide (GO) with chitosan (CS) is successfully accomplished via a facile amidation process. The CS-grafted GO (GO-CS) sheets consist of about 64 wt.% CS, which imparts them with a good aqueous solubility and biocompatibility. Additionally, the physicochemical properties of GO-CS are studied. As a novel nanocarrier, GO-CS is applied to load a water-insoluble anticancer drug, camptothecin (CPT), via π-π stacking and hydrophobic interactions. It is demonstrated that GO-CS possesses a superior loading capacity for CPT, and the GO-CS-CPT complexes show remarkably high cytotoxicity in HepG2 and HeLa cell lines compared to the pure drug. At the same time, GO-CS is also able to condense plasmid DNA into stable, nanosized complexes, and the resulting GO-CS/pDNA nanoparticles exhibit reasonable transfection efficiency in HeLa cells at certain nitrogen/phosphate ratios. Therefore, the GO-CS nanocarrier is able to load and deliver both anticancer drugs and genes. 相似文献
109.
Kühl T Sahoo N Nikolajski M Schlott B Heinemann SH Imhof D 《Chembiochem : a European journal of chemical biology》2011,12(18):2846-2855
Studies of the binding of heme/hemin to proteins or peptides have recently intensified as it became evident that heme serves not only as a prosthetic group, but also as a regulator and effector molecule interacting with transmembrane and cytoplasmic proteins. The iron‐ion‐containing heme group can associate with these proteins in different ways, with the amino acids Cys, His, and Tyr allowing individual modes of binding. Strong coordinate‐covalent binding, such as in cytochrome c, is known, and reversible attachment is also discussed. Ligands for both types of binding have been reported independently, though sometimes with different affinities for similar sequences. We applied a combinatorial approach using the library (X)4(C/H/Y)(X)4 to characterize peptide ligands with considerable hemin binding capacities. Some of the library‐selected peptides were comparable in terms of hemin association independently of whether or not a cysteine residue was present in the sequence. Indeed, a preference for His‐based (≈39 %) and Tyr‐based (≈40 %) sequences over Cys‐based ones (≈21 %) was detected. The binding affinities for the library‐selected peptides, as determined by UV/Vis spectroscopy, were in the nanomolar range. Moreover, selected representatives efficiently competed for hemin binding with the human BK channel hSlo1, which is known to be regulated by heme through binding to its heme‐binding domain. 相似文献
110.
Polypyrrole (PPy) composites were prepared with both unmodified and amine‐modified multiwalled carbon nanotubes (MWCNTs) in the presence and absence of barium titanate (BaTiO3) by in situ oxidative polymerization. A uniform coating of PPy on the MWCNTs and BaTiO3 surfaces was confirmed by field emission scanning electron microscopy and high‐resolution transmission electron microscopy images. The structure of the pure and amine‐modified MWCNTs were identified by Fourier transform infrared spectroscopy. The incorporation of BaTiO3 enhanced the thermal stability and capacitance properties of the composites. The maximum specific capacitance and energy density values found for the PPy/amine‐modified MWCNT/BaTiO3 composites were 155.5 F/g and 21.6 W h/kg, respectively, at a scan rate of 10 mV/s. The maximum power density was found to be 385.7 W/kg for the same composite at a scan rate of 200 mV/s. Furthermore, the impedance spectra of the composites showed moderate capacitive behavior. © 2012 Wiley Periodicals, Inc. J. Appl. Polym. Sci., 2013 相似文献