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[en] This article is devoted to economic aspects of aluminium production. Therefore, the perspectives of development of aluminium production, the base components of aluminium cost and economic security of enterprise are considered in this chapter.
[en] A continuous process for digesting a uraniferous ore by oxidation with a recycling aqueous liquor containing alkaline carbonates and bicarbonates in solution as well as uranium in a concentration close to its solubility limit at digestion temperature, and of recuperation of the precipitated uranium within the solid phase remaining after digestion. The digestion is carried out by spraying oxygen into the hot reactional medium in order not only to permit oxidation of the uranium and its solubilization but also to ensure that the sulphides of impurities and organic substances present in the ore are oxidized
[fr]Il s'agit d'un procede continu d'attaque oxydante d'un minerai uranifere par une liqueur aqueuse de recyclage contenant en solution des carbonate et bicarbonate alcalins ainsi que de l'uranium a une concentration proche de la limite de sa solubilite a la temperature d'attaque, et de recuperation de l'uranium precipite au sein de la phase solide restant apres l'attaque. L'attaque est realise par barbotage d'oxygene dans le milieu reactionnel chaud afin de permettre l'oxydation de l'uranium et sa solubilisation, mais aussi assurer l'oxydation des sulfures d'impuretes et des matieres organiques presentes dans le minerai
[en] The series of experiments to investigate the kinetics of isotopic exchange of tritium with sodium bicarbonate (NaHCO_3) using a column of anion exchange resin and membrane filter were conducted. On the basis of the data method of determining the organically bound tritium was developed. (authors)
[en] A new spectrophotometric method has been developed for the determination of the potent antibiotic (CF) by derivatization with 4-dimethylaminobenzaldehyde (DAB). The derivative indicated molar absorptivity of 5.3 * 10/sup 3/ L mol/sup -1/ at lemda max 397 nm and obeyed the Beers law within 20-100 micro gmL/sup -1/. The color reaction was highly stable and did not show any change in absorbance up to 24h. The mehtod was successfully applied for the determination of CF from various pharmaceutical preparations available in local market. The amounts of CF found in various pharmaceutical preparations were within 237.4-990 mg ampoule/sup -1/ with standard deviation(SD)+-0.0003-0.44 (N=3) respectively. (author)
[en] This study characterized the removal of strontium from an aqueous solution via co-precipitation followed by microfiltration (CPMF) on a lab-scale. Sodium carbonate was used as the precipitating agent. Ferric chloride was added to a settler at a dosage of 20 mg/L to improve strontium removal, and it was added to a membrane separator at a dosage of 10 mg/L to reduce membrane fouling. The concentration of strontium in the raw water used in this study was about 5 mg/L. In two intermittent tests, where dosages of sodium carbonate were 2000 mg/L and 1000 mg/L, the mean decontamination factors (DFs) were 237 and 158 and the mean concentration factors (CFs) were 288 and 462, respectively. Although the mean DF value was lower when the sodium carbonate dosage was 1000 mg/L instead of 2000 mg/L, the rate at which the specific flux (SF) of the membrane declined decreased as the amount of the effluent treated increased. The problem of strontium release at the beginning of the operation was controlled by a continuous test in which the dosage of sodium carbonate still was 1000 mg/L and the other parameters were the same as in the other tests. The results showed that the mean DF and CF were 157 and 480, respectively. (author)
[en] Highlights: • Soft blasting of polytetrafluoroethylene leads to slippery superhydrophobic surfaces. • A micro-scale random texture is generated through polymer fibers tearing. • The method is portable, cost-effective, and requires a process time as low as five seconds. In this paper, we propose a new method for fabricating superhydrophobic surfaces. We use polytetrafluoroethylene (PTFE) as representative fluorinated polymer, and show that a few seconds blasting treatment of this material, with sodium bicarbonate (NaHCO3) grit, can lead to superhydrophobicity with optimum sliding performances. Such a wetting behavior is correlated to the multi-scale random roughness of the surface, generated by abrasion and tearing of polymer fibers during the blasting process. This method, compared to other techniques generating superhydrophobic surfaces, turns out simpler, much more cost-effective, and directly suitable for large-scale applications.
[en] A flow injection electrochemiluminescence (FI-ECL) analysis method for the determination of sibutramine in the presence of luminol was studied under conventional cyclic voltammetry in alkaline Na2CO3-NaHCO3 buffer solution (pH 8.0-12.0). This method is based on the enhanced ECL of luminol-sibutramine. Meanwhile, in order to overcome the drawbacks of conventional cells, a FI cell was designed, which is reusable and has a great improvement in sensitivity and selectivity for ECL analysis. Under the optimal experimental conditions, the enhanced ECL intensity was linearly related to the concentration of sibutramine in the range 1.0x10-8-1.0x10-6 g mL-1 with a detection limit of 2.48x10-9 g mL-1 and a correlation coefficient (R) of 0.9995. The relative standard deviation (RSD) for 1.0x10-7 g mL-1 samples was 2.1% (n=11). The possible mechanism discussed. The proposed FI-ECL method has been successfully applied to the determination of sibutramine in diet pill samples. - Highlights: → An electrochemiluminescence (ECL) system was studied to determine sibutramine. → A flow injection cell was made to overcome the drawbacks of the conventional ones. → The system was based on the enhanced ECL of luminol-sibutramine. → The system can be satisfactorily applied to determine sibutramine in diet pills.
[en] Powder X-ray patterns were used to study the crystalline structure of isomorphous compounds LiNpO2CO3 (1) and NaNpO2CO3 (2). The crystals are of rhombic structure with unit cell parameters a=4.870 A, b=10.146 A, c=4.280 A and a=4.856 A, b=10.680 A, c=4.368 A respectively. The structure consists of [NpO2CO3] layers isostructural to the [UO2CO3] layers in the mineral rutherfordine UO2CO3. The alkali cations are studied between the anionic layers
[en] This paper describes a spectrophotometric method for the determination of silicon in alumina grit used for sand blasting of surface of zircaloy tubes including the inner surface. The spectrophotometric method involves fusion of the alumina grit with a mixture of sodium carbonate and borax, dissolution of the fused melt, addition of necessary reagents and measurement of absorbance of the solution at 815 nm. The molar extinction coefficients obtained for silico-molybdenum blue complex in the absence and presence of matrix respectively are 1.7309 x 104 and 1.6278 x 104 L mol-1 cm-1.The RSD achieved in this method is 1.1% (n=10) at 1% silica in alumina grit. (author)