Separation of95Zr and95Nb from each other and from other fission products by adsorption and desorption on silica gel using hydrochloric acid solutions

The silica gel adsorption behaviour of zirconium, niobium, ruthenium and cerium in hydrochloric acid has been investigated by batch and column techniques. A satisfactory radiochemical separation of zirconium and niobium from each other and from other fission products has been achieved by a two column technique. The recommended procedure consists of sorption of all the nuclides on a primary silica gel column. Fifteen per cent of⁹⁵Nb, all of the zirconium and all of the other fission products are eluted first by washing with 5.5 M HCl. A second elution with concentrated hydrochloric acid then recovers the⁹⁵Nb (free from other products). The solution from the first elution after evaporation to 1 ml is then passed through another silica gel column and successively washed with 0.5M HCl, 5.5M HCl and concentrated HCl to obtain three fractions—other fission products—⁹⁵Zr free from other products—⁹⁵Nb free from other products, respectively.     

Separation of amphotericin B components by combined thin-layer and high-performance liquid chromatography

Amphotericin B has been separated into five components by the use of thin-layer chromatography (TLC) with only methanol as the developing solvent. Each TLC component was then subjected to high-performance liquid chromatography. Besides the two major components found in other studies, amphotericin B was also found to contain five other significant heptaenes, one tetraene, two fluorescent polyenes (pentaene and heptaene), and at least five other significant components which had appreciable absorbance at approximately 305 nm. In addition, amphotericin B was found to exhibit as in a previous study by other workers, only a trace amount of fluorescence.     

A novel approach towards chemoselective reduction of nitro to amine

Chemo selective reduction of a wide range of aromatic nitro compound has been performed by using inexpensive Zn powder and CuSO₄ system in water medium at room temperature. This system has high tolerance to other highly reducible groups present in nitro substance along with high conversation and selectivity. This chemo-selective reduction also provides a facile root for the synthesis of other industrially important fine chemicals or biologically important compounds where other highly reducible groups are present in close proximity to the targeted nitro groups.     

迭代目标转换因子分析光度法同时测定钇和其它稀土合量

以三氯偶氮胂为显色剂，根据钇(Y^3 )与其它稀土组分的显色络合物吸收光谱差别较大的特点，提出应用迭代目标转换因子分析光度法同时测定钇和其它烯土合量的计算光度分析法，通过对不同组成的人工模拟样品和龙南稀土氧化物标准样中的钇和其它稀土合量的测定，取得了满意的结果。     

Phthalones and their structural analogs (review)

This review is devoted to research on the synthesis, reactivities, practical application, and structural problems of compounds of the phthalone series, primarily pyrophthalones and quinophthalones. The properties and peculiarities of the structures of the indicated compounds are compared with structural analogs that contain other heterocyclic substituents and other β-dicarbonyl systems and also with other betainelike derivatives of β-dicarbonyl compounds. Problems in the development of the chemistry of phthalones are discussed.     

Determination of hexavalent chromium and accompanying anions in one run using isocratic ion chromatography with column switching

A method for the simultaneous determination of hexavalent chromium and other inorganic anions like chloride, nitrate and sulfate in aqueous solutions was developed using isocratic ion chromatography with suppressed conductometric detection and column switching. Owing to the large differences in distribution coefficient between chromate and the other species, the chromate is separated from the other anions in a first short column, whereas the other anions are led to a longer second column via a column-switching valve, and separated there. Using standard anion separation conditions the length of the columns and the switching procedure were optimized. The time of analysis for eight anions is less than 12 min and the method can be easily automated. Detection limit and precision are not effected by the switching procedure.     

Activation analysis of rare earths : Part II. Determination of lutetium in gadolinite

Two precise and accurate methods for the determination of lutetium in the presence of other rare earths and after separation from a mineral, gadolinite, are described. Both methods require separation of lutetium and ytterbium from the other rare earths. A complete separation of Lu and Yb is necessary when integral counting is used. The other method differentiates between the two elements by γ -spectrometry.     

Recent studies at Durham on direct fluorination

Developments in direct fluorination are described, which changed our perception of the viability of this methodology for selective introduction of carbon–fluorine bonds. Use of acids as solvent media is a valuable technique for electrophilic fluorination, especially with aromatic systems. Fluorinations of 1,3-dicarbonyl compounds proceed well and techniques for promoting reactivity in other carbonyl derivatives are described. ‘In-situ’ formation of other reagents, e.g. by reaction of fluorine with other halogens and with water, provides convenient methodology for halogenation and oxidation.     

Replacing targeted compassion with multidimensional compassion: an essential paradigm shift to achieve sustainability

We are in the midst of a national, arguably global, debate about hunting and other means of controlling populations of deer and other animals that have greatly exceeded the carrying capacity of local and regional habitat. At one extreme are those who feel that, since humans have eliminated the large, natural predators, we are obligated to keep game species in balance with their environment. At the other extreme are those who value the lives of individual wild creatures and seek to prevent their destruction. Keeping in balance with nature is the essence of sustainability. This would permit the largest number of humans to occupy the planet over a long period of time. Properly managed sustainability should concomitantly make the planet more habitable for other species. The position taken in this discussion is that targeted compassion is inappropriate for sustainable use of the planet because it will not leave a habitable world for future generations.     

Comparison of the NCI open database with seven large chemical structural databases.

Eight large chemical databases have been analyzed and compared to each other. Central to this comparison is the open National Cancer Institute (NCI) database, consisting of approximately 250 000 structures. The other databases analyzed are the Available Chemicals Directory ("ACD," from MDL, release 1.99, 3D-version); the ChemACX ("ACX," from CamSoft, Version 4.5); the Maybridge Catalog and the Asinex database (both as distributed by CamSoft as part of ChemInfo 4.5); the Sigma-Aldrich Catalog (CD-ROM, 1999 Version); the World Drug Index ("WDI," Derwent, version 1999.03); and the organic part of the Cambridge Crystallographic Database ("CSD," from Cambridge Crystallographic Data Center, 1999 Version 5.18). The database properties analyzed are internal duplication rates; compounds unique to each database; cumulative occurrence of compounds in an increasing number of databases; overlap of identical compounds between two databases; similarity overlap; diversity; and others. The crystallographic database CSD and the WDI show somewhat less overlap with the other databases than those with each other. In particular the collections of commercial compounds and compilations of vendor catalogs have a substantial degree of overlap among each other. Still, no database is completely a subset of any other, and each appears to have its own niche and thus "raison d'être". The NCI database has by far the highest number of compounds that are unique to it. Approximately 200 000 of the NCI structures were not found in any of the other analyzed databases.     

NAA as viewed from the perspective of international atomic energy agency intercomparison tests

Results of several IAEA intercomparison runs organized over the last 8 years are analyzed from the point of view of contribution and performance of NAA as compared to other techniques. It is shown that NAA is the method of good accuracy and precision providing on average greater share of results than any other single analytical technique. The prominent position of NAA among other methods used in trace analyses seems to be firmly established and there are no signs that there might be any change of the trend in the nearest future.     

Indexing scheme and similarity measures for macromolecular sequences

Nucleotide composition and distribution along a DNA sequence is known to play a vital role in the determination of gene functions. Protein coding regions, regulatory sequences, and other functional regions are determined generally by homology studies with comparable genes from other species or specific experimental verification. With the rapid and explosive increase in sequence information, new computational techniques for rapid determination of such information and comparative studies of different genes are becoming necessary which ideally should encompass not only DNA sequences but other macromolecular sequences as well.     

Improved recovery of hexachlorobenzene in adipose tissue with a modified micro multiresidue procedure.

Using the described methodology the recovery of hexachlorobenzene from adipose tissue was significantly increased over that normally obtained with other multiresidue procedures. The recovery of other commonly encountered chlorinated hydrocarbon pesticides was not affected nor was the "background" from adipose tissue intolerable. Although extensive work has not been done, it is likely that improved recovery of hexachlorobenzene could be expected from other tissues.     

Carboxy-substituted Phthalocyanine Metal Complexes

Metal complexes of carboxy-substituted phthalocyanines differing in the number of carboxy groups and their positions and those having carboxy groups together with other substituents were synthesized, and their spectral and some other properties were studied.     

5-epi-Canadensene and other novel metabolites of Taxus canadensis

The Canadian yew distinguishes itself from other yews by the nature of its taxane metabolites. We are now reporting a new canadensene taxane whose stereochemistry is rigorously established. The three-dimensional structures of canadensene, 5-epi-canadensene and three other related bicyclic taxanes isolated from other yews were calculated using distance constraints derived from NMR data. The stereochemistry of the substituents, the polar acetate groups and the double bonds determine the 3D models. In addition, three new taxanes were also characterized and some biosynthetic speculations are presented.     

化学发光法在药物分析中的应用

化学发光法因具有设备简单、灵敏度高等特点而被广泛采用。文中对近年涉及药物、药物在人体中的代谢产物及生命相关物质的化学发光分析进行了评述,引用文献87篇。     

Ion-exchange chromatography of glycolatocomplexes of rare earths

Summary The ion-exchange behavior of glycolatocomplexes of the rare earths (Sc, Y and lanthanides) with 1-octanesulfonate as the hydrophobic ion has been investigated in aqueous glycolate media. The system is capable of separating adjacent light intra rare earths, La-Ce-Pr-Nd-Y-Sm, and heavy rare earths, Ho-Er-Tm-Yb-Lu-Sc, from each other with good resolution by gradient elution at room temperature. Intermediate rare earths, Dy-Tb-Gd-Eu-Sm, are difficult to separate from each other. The position of Y in the eluate is different from that found with most other eluent systems used for rare earth separations, being between Nd and Sm.     

Polyphosphate content and fine structure of acidocalcisomes of Plasmodium falciparum.

Although acidocalcisomes have been well characterized morphologically in other apicomplexan parasites, no such characterization has been done in Plasmodium spp. Here, we report that Plasmodium falciparum merozoites possess electron-dense organelles rich in phosphorus and calcium, as detected by X-ray microanalysis of intact cells, which are similar to the acidocalcisomes of other apicomplexans, but of more irregular form. In agreement with these results malaria parasites possess large amounts of short- and long-chain polyphosphate (polyP), which are associated with acidocalcisomes in other organisms. PolyP levels were highest in the trophozoite stage of the parasite. Treatment of isolated trophozoites with chloroquine resulted in a significant hydrolysis of polyP. Taken together, these results provide evidence that acidocalcisomes from Plasmodium falciparum do not differ significantly from acidocalcisomes of other apicomplexan parasites.     

Scanning transitiometry and its applications

Scanning transitiometry combines three state variables (P,V,T) with a heat effect measured in strictly defined thermodynamic conditions. By slowly scanning one of the state variables when the other one is kept constant, the transitiometer permits to determine simultaneously two thermodynamic derivatives, always one is thermal and the other one mechanical. This study presents a number of applications of scanning transitiometry in various fields (dense liquids, supercritical systems, polymers, food systems) and presents results, often impossible to obtain with other known techniques.     

Deoxygenation of allylic carbinolamides and related alcohols by acidic sodium cyanoborohydride: Scope and limitations

Acidic sodium cyanoborohydride reduces allylic and other substituted carbinolamides to the corresponding deoxygenated compounds, whereas other similar alcohols are unreactive or undergo alternative transformations.