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1.
Satya Prakash 《Pramana》1989,33(1):109-131
This article summarizes the recent radiochemical investigations on mass, charge kinetic energy and fragment angular distributions
in low energy fission of actinides. 相似文献
2.
3.
Solution properties of a drug and its partitioning into lipid bilayers were studied for drug extraction using several different techniques, such as surface tension, zeta potential, ultra filtration and UV-Vis spectroscopy. From the surface tension study it was found that the presence of salt makes the drug molecules more surface-active. Zeta potential revealed the adsorption of the drug into the liposome bilayers to be governed mostly by electrostatic forces. The drug retention volume was expressed as a capacity factor, K, and that was normalized with respect to the amount of the immobilized phospholipids. The K-values for the positively charged drug on the liposomes decreased in the presence of phosphate buffer due to the presence of the oppositely charged ions. The above methods can thus be used to understand the mechanism of drug-membrane interaction and quantification of drug absorption into liposomes. 相似文献
4.
Summary Reactions of titanium(IV) isopropoxide with ethyl 1-hydroxycyclohexylacetate, ethyl 2-hydroxy-2-arylpropionate, ethyl 2-hydroxy-2-arylbutyrate and ethyl 2-hydroxy-2-arylhydrocinnamate have been studied in dry benzene in different molar ratios under strictly anhydrous conditions. The Ti(OPr-i)4-nLn type compounds, where L = hydroxy ester and n = 1 to 4, have been isolated and characterised by elemental analysis, molecular weight, i.r. and n.m.r. spectral studies. These products may be distilled unchanged under reduced pressure.Reprints of this are not available. 相似文献
5.
Somasundaran P Ananthapadmanabhan KP Deo P 《Journal of colloid and interface science》2005,290(2):357-363
Interactions of surfactants with solid substrates are important in the controlling of processes such as flotation, coating, flocculation and sedimentation. These interactions usually lead to adsorption on solids, but can also result in an exclusion of the reagents with dire consequences. In this work electrostatic exclusion of negatively charged dodecylbenzene sulfonate micelles from quartz/water, Bio-Sil/water and alumina/water interfaces has been investigated as a function of pH and ionic strength. Measurable negative adsorption of these surfactants from similarly charged solid/liquid interface was observed in the micellar region. In the case of porous samples with large surface area, comparison of pore size with the micelle size is necessary to avoid any erroneous conclusions regarding the role of electrostatic exclusion in a given system. A theoretical model for the electrostatic exclusion of micelles is developed and used to calculate the adsorption of negatively charged dodecylbenzene sulfonate on negatively charged quartz (pH 7), silica (Bio-Sil A, pH 3) and alumina (pH 11) in the micellar concentration region. The micellar exclusion values calculated using the model are in excellent agreement with the experimental results. 相似文献
6.
Deo P Deo N Somasundaran P Jockusch S Turro NJ 《The journal of physical chemistry. B》2005,109(44):20714-20718
Structural changes of pyrene-labeled and unlabeled poly(maleic acid/octyl vinyl ether) (PMAOVE) and poly(maleic acid/methyl vinyl ether) (PMAMVE) with changes in pH have been investigated in this study. The changes in the photophysical properties of pyrene are interpreted to investigate uncoiling or swelling of the polymeric chains with pH. The vibrational fine structure of the pyrene fluorescence (I(3)/I(1)) and the ratio between excimer and monomer fluorescence (I(e)/I(m)) of both pyrene-labeled and unlabeled PMAMVE and PMAOVE suggest that, at pH 4, the polymers are in the coiled form and PMAOVE forms hydrophobic nanodomains. An increase in pH ionizes a number of COOH groups on both PMAMVE and PMAOVE, which leads to the stretching or swelling of the polymers. 相似文献
7.
8.
A. Ramaswami G. K. Gubbi R. J. Singh Satya Prakash 《Journal of Radioanalytical and Nuclear Chemistry》1988,125(1):85-89
Cumulative yields of short-lived/barium isotopes139, 141, 142Ba have been determined in the spontaneous fission of252Cf, using fast radiochemical separation and gamma-ray spectrometry.142Ba yield is reported for the first time. The measured cumulative yields are converted to chain yields, assuming normal charge distribution systematics for comparision with the literature data. 相似文献
9.
Summary Copper has been determined gravimetrically as its bis-salicylaldehyde-ethylenediamine complex of the composition C16H14O2N2 · Cu, dried at 100–120° C. The complex is completely precipitated in theph range of 10.5–13.5, adjusted with ammonia or caustic alkali. It is stable in presence of excess ammonia, 0.1 N alkali, ammonium salts and complexing agents as tartrate, citrate, sodium-thiosulphate, fluoride, thiourea, triethanolamine and EDTA. In presence of tartrate and ammonia the ions of alkali metals, alkaline earths, Ag+, Tl+, Tl3+, Pb2+, Cd2+, Co2+, Mn2+, Pd2+, Al3+, Cr3+, La3+, Ce3+, Au3+, Pt4+, Ti4+, Zr4+, Th4+, UO2
2+ and anions as VO3
–, MoO4
2–, WO4
2–, CrO4
2–, PO4
3–, AsO4
3– do not interfere. Ni2+ and Hg2+ are masked by tartrate, EDTA and ammonia; As3+, Sb3+ and Sn2+ are separated using fluoride as the complexing agent; at an alkalinity of 0.1 N caustic alkali in presence of tartrate As3+, Sb3+, Sn2+, Bi3+, Zn2+ and Fe3+ are separated. Fe3+ can also be separated using triethanolamine as the masking agent at aph of about 13.0. Copper can be separated from almost all the ions, thus affording a highly selective method for the determination of copper.
Part I: Singh, B. R., and S. Kumar: Z. analyt. Chem. 185, 211 (1962). 相似文献
Zusammenfassung Es wird eine gravimetrische Methode zur Bestimmung von Kupfer beschrieben, die auf der Bildung des Bis-salicylaldehyd-äthylendiaminkomplexes beruht. Dieser hat die Zusammensetzung C16H14O2N2 · Cu. Die Fällung wird imph-Bereich 10,5–13,5 (mit Ammoniak oder Alkalilauge eingestellt) vorgenommen und der Niederschlag bei 100°–120° C getrocknet. Der Komplex ist beständig in Gegenwart von überschüssigem Ammoniak, 0,1 n Alkali, Ammoniumsalzen sowie Tartrat, Citrat, Natriumthiosulfat, Fluorid, Thioharnstoff, Triäthanolamin und ÄDTA. In Gegenwart von Tartrat und Ammoniak stören nicht: Alkalien, Erdalkalien, Ag+, Tl+, Tl3+, Pb2+, Cd2+, Co2+, Mn2+, Pd2+, Al3+, Cr3+, La3+, Ce3+, Au3+, Pt4+, Ti4+, Zr4+, Th4+, UO2 2+ sowie VO3 –, MoO4 2–, WO4 2–, CrO4 2–, PO4 3– und AsO4 3+. Ni2+ und Hg2+ können mit Tartrat, ÄDTA und Ammoniak maskiert werden, As3+, Sb3+ und Sn2+ mit Fluorid. In 0,1 n ätzalkalischer Lösung in Gegenwart von Tartrat können As3+, Sb3+, Sn2+, Bi3+, Zn2+ und Fe3+ abgetrennt werden. Fe3+ kann ebenfalls mit Triäthanolamin beiph 13,0 maskiert werden. Das beschriebene Verfahren erlaubt somit eine Abtrennung des Kupfers von fast allen anderen Ionen.
Part I: Singh, B. R., and S. Kumar: Z. analyt. Chem. 185, 211 (1962). 相似文献
10.
Scientific evidence in the prevention and treatment of various disorders is accumulating regarding probiotics. The health
benefits supported by adequate clinical data include increased resistance to infectious disease, decreased duration of diarrhea,
management of inflammatory bowel disease, reduction of serum cholesterol, prevention of allergy, modulation of cytokine gene
expression, and suppression of carcinogen production. Recent ventures in metabolic engineering and heterologous protein expression
have enhanced the enzymatic and immunomodulatory effects of probiotics and, with time, may allow more active intervention
among critical care patients. In addition, a number of approaches are currently being explored, including the physical and
chemical protection of cells, to increase probiotic viability and its health benefits. Traditional immobilization of probiotics
in gel matrices, most notably calcium alginate and κ-carrageenan, has frequently been employed, with noted improvements in
viability during freezing and storage. Conflicting reports exist, however, on the protection offered by immobilization from
harsh physiologic environments. An alternative approach, microencapsulation in “artificial cells,” builds on immobilization
technologies by combining enhanced mechanical stability of the capsule membrane with improved mass transport, increased cell
loading, and greater control of parameters. This review summarizes the current clinical status of probiotics, examines the
promises and challenges of current immobilization technologies, and presents the concept of artificial cells for effective
delivery of therapeutic bacterial cells. 相似文献