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排序方式: 共有2691条查询结果,搜索用时 15 毫秒
81.
82.
Lætitia H. Delmau Peter V. Bonnesen Nancy L. Engle Tamara J. Haverlock Frederick V. Sloop Jr. Bruce A. Moyer 《溶剂提取与离子交换》2013,31(2):197-217
Abstract The combined extraction of cesium and strontium from caustic wastes can be achieved by adding a crown ether and a carboxylic acid to the Caustic‐Side Solvent Extraction (CSSX) solvent. The ligand 4,4′(5′)‐di(tert‐butyl)cyclohexano‐18‐crown‐6 and one of four different carboxylic acids were combined with the components of the CSSX solvent optimized for the extraction of cesium, allowing for the simultaneous extraction of cesium and strontium from alkaline nitrate media simulating alkaline high level wastes present at the U.S. Department of Energy Savannah River Site. Extraction and stripping experiments were conducted independently and exhibited adequate results for mimicking waste simulant processing through batch contacts. The promising results of these batch tests showed that the system could reasonably be tested on actual waste. 相似文献
83.
Addition of t-butylcyclohexano-15-crown-5 (tBC-15C5) induces a synergistic effect in the extraction of Mn2+ ion with didodecylnaphthalenesulfonic acid (HDDNS). This synergism is the result of the inner-sphere complexation of the crown ether to the manganese(II) ion. The formation of this complex, first suggested by distribution studies, has been confirmed by FTIR experiments. The C-O-C stretching bands for the crown ether ligand shift to lower frequency when Mn2+ ion is extracted into a CC14 solution of HDDNS and tBC15C5. A similar C-O-C Btretching band is observed for the crystalline complex [Mn(15C5 ) (Bu3CS03)2] (where 15C5 = 15-crown-5 and Bu = n-butyl).Formation of analogous complexes is not observed for Fe3+, co2+,N2+,cu2+, or zn2+ under similar conditions. 相似文献
84.
Abdallah M. Altass H. M. El-Sayed R. Al Gorair Arej S. Jahdaly B. A. AL Sobhi M. 《Protection of Metals and Physical Chemistry of Surfaces》2021,57(4):811-819
Protection of Metals and Physical Chemistry of Surfaces - Three nonionic surfactants molecules (NS) derived from a fused pyridine characterized by IR and 1HNMR spectra were synthesized and examined... 相似文献
85.
Presents four additional articles on the general topic of Consumer Communications and Networking. The first set of articles appeared in the December 2008 issue. 相似文献
86.
Jeremy M. Rathfon Zoha M. AL‐Badri Raja Shunmugam Scott M. Berry Santosh Pabba Robert S. Keynton Robert W. Cohn Gregory N. Tew 《Advanced functional materials》2009,19(5):689-695
The chemical sensing of nerve gas agents has become an increasingly important goal due to the 1995 terrorist attack in a Tokyo subway as well as national security concerns in regard to world affairs. Chemical detection needs to be sensitive and selective while being facile, portable, and timely. In this paper, a sensing approach using a pyrene imine molecule is presented that is fluorimetric in response. The detection of a chloro‐Sarin surrogate is measured at 5 ppmv in less than 1 second and is highly selective towards halogenated organophosphates. The pyrene imine molecule is incorporated into polystyrene films as well as micrometer and sub‐micrometer fibers. Using both a direct drawing approach and electrospinning, micrometer and nanofibers can be easily manufactured. Applications for functional sensing micrometer and nanofibers are envisioned for optical devices and photonics in addition to solution and airflow sensing devices. 相似文献
87.
AL Hughes 《Canadian Metallurgical Quarterly》1999,49(2):106-114
PURPOSE: Because intraperitoneal (i.p.) therapy may provide a therapeutic advantage and because hyperthermia enhances carboplatin (CBDCA) cytotoxicity, we evaluated the feasibility, toxicity, and pharmacokinetics of CBDCA given via continuous hyperthermic peritoneal perfusion (CHPP) in patients with small-volume residual ovarian cancer. Patients and METHODS: Six patients underwent optimal cytoreductive procedures (residual disease < or =5 mm) as initial treatment of stages II and III epithelial ovarian adenocarcinoma. All patients received a 90-min CHPP at a CBDCA dose of 800-1200 mg/m2, with the perfusate being recirculated rapidly from a reservoir through a heat exchanger, resulting in i.p. temperatures of 41-43 degrees C. Plasma, perfusate, and urine samples were collected and platinum was quantified by flameless atomic absorption spectrophotometry. RESULTS: At no time did any patient's core temperature exceed 40 degrees C. Peak perfusate platinum concentrations were 8- to 15-fold higher than peak ultrafilterable plasma concentrations. The permeability-area product was extremely high and variable (14-90 ml/min), resulting in a regional advantage of 1.9-5.3. The percentage of the dose absorbed ranged widely from 27% to 77%. Dose-limiting hematologic toxicity was observed at a dose of 1200 mg/m2 and this was associated with a CBDCA AUC in plasma of 11 mg min ml(-1). CONCLUSION: CHPP with CBDCA was safely given to three patients at a dose of 800 mg/m2, and dose-limiting hematologic toxicities observed at 1200 mg/m2, correlated with the plasma CBDCA exposure established when lower doses of CBDCA are given systemically. The pharmacokinetic data are consistent with the expected effect of vigorous mixing on the exposed peritoneal surface area. Variable drug absorption and clearance make the prediction of systemic exposure highly uncertain. These findings may have important implications for novel therapies given i.p. 相似文献
88.
Chambliss CK Haverlock TI Bonnesen PV Engle NL Moyer BA 《Environmental science & technology》2002,36(8):1861-1867
Recovery and recycle of caustic reagents in industrial processes offer potential means of pollution prevention, as investigated herein for particular needs related to the cleanup of alkaline nuclear waste. Specifically, the recovery of hydroxide from alkaline media by liquid-liquid extraction can be effected utilizing weak hydroxy acids, as demonstrated for NaOH utilizing a series of lipophilic fluorinated alcohols and alkylated phenols dissolved in 1-octanol. Extraction efficiency follows the expected order of acidity of the hydroxy acids, the phenols being the most efficient extractants among the compounds tested. After extraction, NaOH is effectively recoverable from the organic phase upon contact with water. The weakest hydroxy acids are the most efficiently stripped, NaOH recovery being nearly quantitative in a single contact. In competitive extraction experiments, good selectivity for hydroxide recovery over other anions such as nitrate and chloride was demonstrated. Since the order of extraction favors larger anions, the exceptional preference for hydroxide implies that the extraction occurs by deprotonation of the hydroxy acids in a cation-exchange process. Stripping therefore occurs by hydrolysis to regenerate the neutral hydroxy acid, liberating NaOH to the aqueous phase. Since hydroxide equivalents rather than actual hydroxide ions are transferred to the solvent, the process is termed "pseudohydroxide extraction." Hydroxide recovery from a simulant of alkaline nuclear tank waste (Hanford DSSF simulant) was also demonstrated in repeated extraction and stripping cycles. 相似文献
89.
Comments on "Psychotherapy, classism, and the poor: Conspicuous by their absence" by Laura Smith (see record 2005-11834-002). This article might have improved Smith's argument that prejudice and oppression (classism) are significant obstacles preventing the poor from receiving psychological services if she had presented evidence to substantiate her claim that "psychology has fallen short in its services" (p. 687) to the poor in the first place. In fact, there is reason to believe that psychotherapists are meeting the mental health needs of the poor in some areas of the country. In Maine, the poor are eligible for Medicaid, which allows for mental health benefits that are more generous in some cases than those provided by private insurance. In addition, the poor in southern Maine may take advantage of programs that pay for mental health services in ways that the middle class cannot. Many psychologists in Maine do provide mental health services to the poor. This is not to say that barriers do not exist or that the mental health needs of the poor are being met. However, I think it is fair to challenge the premise of Smith's (2005) article that the poor either are not being served or are being disproportionately served compared with the nonpoor. (PsycINFO Database Record (c) 2010 APA, all rights reserved) 相似文献
90.
Kavallieratos K Danby A Van Berkel GJ Kelly MA Sachleben RA Moyer BA Bowman-James K 《Analytical chemistry》2000,72(21):5258-5264
A systematic study of a dual-host system exhibiting pairwise anion/cation separations has been performed for CsNO3 extraction. Tripodal triamides 1-4 and 9 derived from condensation of hexanoic (for 1), octanoic (for 2), decanoic (for 3), lauric (for 4), and p-tert-butylbenzoic (for 9) acid with tris(2-aminoethyl)amine (tren) were used together with tetrabenzo-24-crown-8, a well-known Cs+ cation receptor. By using 5 mM crown ether in the organic phase and 10 mM CsNO3 with 0.1 mM HNO3 in the aqueous phase, tripods 1, 2, and 9 enhance CsNO3 extraction by factors of 2.4, 1.7, and 4.4, respectively (for 50 mM amide concentration), while the corresponding monoamide controls 5-8 derived from n-propylamine (5, 6) or N,N'-dimethylethylenediamine (7, 8) and hexanoic (5, 7) or octanoic (6, 8) acid derivatives gave no significant enhancement under the same conditions. This behavior may be ascribed to nitrate complexation by the triamides, which lowers the overall thermodynamic barrier for the salt transfer to the organic phase. The nitrate binding was confirmed by 1H NMR titration of receptor solutions, using tetrabutylammonium nitrate. Association constants for the formation of the anion-nitrate complexes were found to vary between 33 and 52 M-1 for the more soluble triamides. The synergistic effects for CsNO3 extraction are in reasonable agreement with the values predicted theoretically from the measured association constants. Electrospray ionization mass spectrometry confirmed the predominant formation of 1:1 tripod-nitrate complexes. Monoamide controls gave no evidence of anion complexation. 相似文献