Measurement and correlation of solvent extraction equilibria. The extraction of copper by kelex 100

Statistical modeling procedures are used to correlate experimental data for the extraction of copper from acid sulfate solutions by Kelex 100 in xylene. The data are fit with a standard error of 9 pct over a wide range of conditions by use of a thermodynamic reaction equilibrium constant and expressions for activity coefficient ratios in each phase. Comparison of the results of this study with other published data indicates the marked effect that diluent composition can have on metal distribution equilibria. Formerly a Graduate Student.     

The extraction of noble metals by macrocyclic compounds: II. The extraction by crown compounds

Our review on the extraction of noble metals by macrocyclic compounds, i.e., by crown ethers containing donor atoms O, S, and N, continues. The literary data for the period from 1984 to 2008 are summarized. It is noted that no systematic investigations have been carried out until now. On the whole, the information is incomplete. The solution compositions are far from technological ones, and the chemical state of extracted ions in aqueous solutions is not taken into account. It is emphasized that there is only desultory information on the reextraction in the literature. The problem of selectivity for noble metal extraction by crown compounds is discussed.     

Clustering, seriation, and subset extraction of confusion data.

The study of confusion data is a well established practice in psychology. Although many types of analytical approaches for confusion data are available, among the most common methods are the extraction of 1 or more subsets of stimuli, the partitioning of the complete stimulus set into distinct groups, and the ordering of the stimulus set. Although standard commercial software packages can sometimes facilitate these types of analyses, they are not guaranteed to produce optimal solutions. The authors present a MATLAB *.m file for preprocessing confusion matrices, which includes fitting of the similarity-choice model. Two additional MATLAB programs are available for optimally clustering stimuli on the basis of confusion data. The authors also developed programs for optimally ordering stimuli and extracting subsets of stimuli using information from confusion matrices. Together, these programs provide several pragmatic alternatives for the applied researcher when analyzing confusion data. Although the programs are described within the context of confusion data, they are also amenable to other types of proximity data. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Solvent extraction of noble metals by formazans. II: The effect of ortho-substituents of formazans on their extraction and stripping behaviour

Eight systematically substituted 1,5-diphenyl formazans, dissolved separately in toluene, chloroform and dichloromethane, were investigated as liquid-liquid extractants. The size of the phenyl ring substituents in the ortho position (halogen and alkyl groups) as well as the nature of the substituent on the central carbon atom affect the stability and acidity of the formazans. Their tendency to form different isomers influences the coordination chemistry of the ligands and thus their extraction behaviour. Distribution ratios determined for platinum group metals, gold and numerous base metals reveal the selective extractability of Pd (II) from dilute hydrochloric acid. The ortho-iodo formazan is the most effective ligand due to its enhanced formazion of a 1:1 Pd (II) complex, whereas all other formazans co-ordinate as 1:2-chelates. Consequently, in the stripping step with an acidified solution of thiourea, the rate of ligand substitution is also comparatively faster in the case of the 1:1-chelate. An effective separation of Pd (II) from an excess of Pt (IV) can be achieved by the iodo formazan.     

Coupled process of reaction and solvent extraction: I. The reaction between CO2 and SrCl2 coupled with solvent extraction of HCl

In order to ensure the continual reaction between CO₂ and SrCl₂ to produce SrCO₃, it is necessary to neutralize produced HCl or to remove it to another phase. Coupling the reaction with solvent extraction is a way to lower the acidity of the aqueous solution and to allow the reaction to proceed continually. Based on this coupled process, a new flow sheet for producing strontium carbonate from celestite is proposed. The factors influencing equilibrium of the coupled process of strontium carbonate production with solvent extraction have been studied.     

Commercial chelating solvent extraction reagents. III. Oximes: Spectra,structure and properties

Structures of the proprietary aliphatic and aromatic oxime extractants, marketed by General Mills, Inc., under the name LIX reagents, have been investigated by spectroscopic methods. The syn and anti isomers of the aromatic oximes are readily distinguishable by their u.v. spectra. Infrared studies indicate that intramolecular hydrogen bonding is predominant in the syn isomers, whereas intermolecular bonding predominates in the anti isomers. Evidence from n.m.r. spectra substantiates these conclusions.Proton-ligand stability constants of the isomers of the aromatic oximes, together with that of the aliphatic oxime LIX 63 are reported. In all cases, the syn isomers are found to be significantly stronger acids than the anti isomers. LIX 63 is a substantially weaker acid than any of the aromatic LIX reagents.An earlier reported structure of LIX 63 has been substantiated from mass spectral data and from elemental analysis of the pure reagent.     

Extracapsular cataract extraction in diabetic eyes. The role of YAG laser capsulotomy

Cataract surgery may exacerbate preexisting diabetic retinopathy. Especially diabetics with active retinal neovascularisation are at high risk of rubeosis iridis after intracapsular cataract extraction. Thirty-five eyes previously treated with panretinal photocoagulation underwent extracapsular cataract extraction with posterior chamber lens implantation. Twenty-eight eyes with retinal neovascularisation required further Argon laser PRP after surgery. Fourteen eyes required YAG-laser capsulotomy. From the group of eyes without YAG-laser capsulotomy none developed neovascular glaucoma. From the YAG laser capsulotomy group six eyes developed rubeosis iridis and neovascular glaucoma. Our results indicate that eyes in which PRP has been performed, have an excellent prognosis after ECCE with posterior chamber lens implantation only if YAG Laser posterior capsulotomy is not performed.     

Extraction of cadmium from phosphoric acid solutions with amines. Part III. A thermodynamic extraction model

A thermodynamic model for cadmium extraction from phosphoric-hydrochloric acid mixtures has been developed. The model enables calculations of cadmium extraction as well as coextraction of phosphoric and hydrochloric acids to be made. In the aqueous phase Bromley's model for the activity coefficients is adopted. In the organic phase simple expressions for the non-ideal behaviour of phosphoric acid are used. The model is capable of calculating cadmium extraction from 0.02 M up to 6.7 M H₃PO₄ and chloride concentrations between 0.005 and 0.10 M HCl. For high amine concentrations the prediction for cadmium extraction is too high, indicating that high concentrations of phosphoric acid in the organic phase affect the activity coefficient for the extracted cadmium complex significantly. The thermodynamic constant for the extraction equilibrium has been determined as log K₁₁ = 10.23.     

Breech extraction of the second twin. 56 cases and review of the literature

It has been well known that the survivors of retinoblastoma are prone to have osteosarcoma. But the secondary tumor usually occurs in bilateral, hereditary type of retinoblastoma. We report one case of osteosarcoma in a survivor of unilateral, sporadic retinoblastoma. A fourteen year old male presented with a painfully swollen distal forearm of 2 month duration. He had enucleated his left eye 10 years ago due to retinoblastoma with no other adjuvant therapy. We managed him with our conventional protocol and identified deletion of Rb gene from his pathological specimen by using the PCR-RFLP method. This result is unusual for unilateral nonhereditable retinoblastoma and may suggest gene level change even in sporadic cases. And Rb gene study may be helpful for unilateral, sporadic retinoblastoma patient in detecting the possibility of late osteosarcoma.     

Combined cataract-glaucoma operations. Extracapsular extraction and trabeculectomy versus phacoemulsification and trabeculectomy

This retrospective study was conducted to evaluate the results of Combined Surgery of Cataract and Glaucoma (triple procedure). The procedure of combined surgery were trabeculectomy and extracapsular extraction (14 eyes) versus trabeculectomy and phacoemulsification (15 eyes). The follow-up of both groups was at least 9 months and up to 16 months (mean: 12 months). The mean decrease of IOP was 12.4 mmHg and 8.9 mm Hg in the first and second group respectively. Instillation of Beta-blockers twelve months after surgery were more frequent in the first group (64.3%) than in the second (26.7%). Finally, the IOP values one year after surgery were equivalent in both groups (less than 19 mmHg in 93% of cases). The mean features to emphasize the delay of recuperation of the best corrected visual acuity: one month for phacotrabeculectomy, and three months for extracapsular with trabeculectomy. The frequency of complications was low in both groups. We observed more hyphemas but less secondary cataracts in the phacotrabeculectomy group. Phacotrabeculectomy could become a reference procedure for combined glaucoma and cataract surgery.     

Basic decoding components in reading: Two dissociable feature extraction processes.

Two views of the feature-extraction process underlying visual word recognition are contrasted. One asserts that features that span individual letters (configurational features) are functional. The other asserts instead that preliminary letter identification alone subserves word recognition. Configurational feature theory predicts that since case alternation eliminates configurational features, words should be more disrupted than nonwords because words have more configurational features than nonwords. The alternative theory predicts that since only preliminary letter identification underlies both word and nonword recognition, any effect of case alternation should be at least as disruptive to nonwords as to words. Two experiments, with 66 undergraduates, varied the utility of configurational features by case alternation and demonstrated that lexical decision provides data consistent with configurational feature theory, but naming latency provides data consistent with preliminary letter identification. Additional findings suggest that configurational features subserve only a familiarity discrimination process that can be recruited for some tasks but is eschewed for others. Tasks that require that a word be uniquely specified rely on preliminary letter identification; case alternation effects in these latter tasks may reflect delays in the mapping of abstract information back on to the original sensory pattern (perceptual integration). (French abstract) (25 ref) (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Solvent extraction of uranium from dilute solutions using a gas-bubble mixed extraction column

A modified solvent extraction process for recovering uranium from very dilute solutions, such as mine waters or copper dump liquors, has been developed and tested on a laboratory scale. The system utilizes a column in which the aqueous feed flows downward through a liquid organic extractant. A countercurrent flow of gas is used to achieve mixing and enhance mass transfer. Acid sulfate solutions at pH 1.5 containing either 0.010 or 0.015 g/1 U₃O₈ comprised the feed. The extractant used was Alamine® 336 dissolved in fuel oil. Critical parameters of the system, such as length to diameter ratio of the organic phase, volume ratio of aqueous to organic in the column, and flow rates of aqueous feed and gas are examined.     

Blood fractionation based on the extraction of the buffy-coat layer. Analysis of our results

T-cell growth is controlled to a large degree by extracellular signals that bind to specific receptors on the surface of cells. A number of these receptors have intrinsic protein tyrosine kinase (PTK) activity. Their action on second messenger generation, and thus on cell proliferation, has been indirectly demonstrated by the decrease in [3H]-thymidine (TdR) uptake that follows co-stimulation of T-cells with mitogens and PTK inhibitors such as genistein (GEN). In this paper we report that the [3H]-TdR uptake assay is not a valid and reliable tool for investigating the proliferative activity of certain T-cell lines. In fact, a concomitant assessment of both [3H]-TdR uptake and cell cycle progression demonstrated that GEN is able to block G2/M progression of Jurkat T-lymphocytes even at doses (5 micrograms/ml) that do not influence [3H]-TdR uptake. Pretreatment with sodium o-vanadate (100 nM) could not reverse the GEN-related cell cycle perturbation, but was able to restore optimal [3H]-TdR uptake. Finally, GEN treatment was able to induce concentration-dependent apoptotic cell death of Jurkat T-cells. The control of cell activation, proliferation and programmed cell death is undoubtedly influenced by receptor-associated PTKs. The final effect on cell survival is almost entirely dependent on the activation state of the cell. The [3H]-TdR uptake assay seems to be inadequate for a correct interpretation of the expected results.     

TRACX: A recognition-based connectionist framework for sequence segmentation and chunk extraction.

Individuals of all ages extract structure from the sequences of patterns they encounter in their environment, an ability that is at the very heart of cognition. Exactly what underlies this ability has been the subject of much debate over the years. A novel mechanism, implicit chunk recognition (ICR), is proposed for sequence segmentation and chunk extraction. The mechanism relies on the recognition of previously encountered subsequences (chunks) in the input rather than on the prediction of upcoming items in the input sequence. A connectionist autoassociator model of ICR, truncated recursive autoassociative chunk extractor (TRACX), is presented in which chunks are extracted by means of truncated recursion. The performance and robustness of the model is demonstrated in a series of 9 simulations of empirical data, covering a wide range of phenomena from the infant statistical learning and adult implicit learning literatures, as well as 2 simulations demonstrating the model's ability to generalize to new input and to develop internal representations whose structure reflects that of the items in the input sequence. TRACX outperforms PARSER (Perruchet & Vintner, 1998) and the simple recurrent network (SRN, Cleeremans & McClelland, 1991) in matching human sequence segmentation on existing data. A new study is presented exploring 8-month-olds' use of backward transitional probabilities to segment auditory sequences. (PsycINFO Database Record (c) 2011 APA, all rights reserved)     

Mandibular fractures following third molar extraction. A retrospective clinical and radiological study

Health care workers (HCW) are at risk of occupationally acquiring Mycobacterium tuberculosis (TB) infection. The Centers for Disease Control and Prevention has published guidelines for health care facilities to protect HCW. One of the recommended elements is TB infection surveillance among HCW using purified protein derivative (PPD) skin testing and analysis of the data by occupational group and work location to determine areas of increased risk of infection. At the military medical center (MMC) we studied, occupational groups with statistically significant (p < 0.05) above-average PPD conversion risk (> 1.1%/year) included respiratory therapists (15.6%/year), nursing technicians (2.3%/year), and military personnel (1.6%/year). Maintenance and engineering workers (2.6%/year), food service workers (2.5%/year), laboratory workers (2.0%/year), custodial workers (1.8%/year), and practical nurses (1.7%/year) had above-average, but not statistically significant, risk. The fourth floor of the MMC had 39% (21/54) of the converters. The surveillance program also uncovered 235 individuals who had not completed adequate prophylactic therapy, and a case of active TB in a laboratory worker.     

溶剂萃取法从含钒浸出液中提钒的研究进展

提钒原料、浸出工艺及浸出条件等将决定浸出液中钒的存在形态及净化方法.溶剂萃取法可有效净化回收浸出液中的钒，具有处理量大、选择性高、可回收利用、产品纯度高等优点，在钒冶金中得到越来越广泛的应用.笔者针对不同提钒原料所得到的含钒浸出液，综述了各类萃取剂以一定萃取机制从中萃取钒的研究现状.讨论了萃取过程中溶液pH值、协萃剂、萃取时间、杂质元素及萃取预处理等因素对钒萃取分离的影响，并介绍了溶剂萃取法从含钒浸出液中提钒新技术，提出了钒溶剂萃取技术的未来发展方向.      

Combined cataract extraction and thermal sclerostomy versus combined cataract extraction and trabeculectomy

We performed either a combined cataract extraction and trabeculectomy or a combined cataract extraction and thermal sclerostomy on 43 eyes. All eyes had chronic open angle glaucoma or chronic angle closure glaucoma, or a combination of the two. In our cataract/trabeculectomy group, 74% had improvement in visual acuity, 91% had normalized intraocular pressure without anti-glaucoma medications, 31% had transient postoperative hyphemas. In our cataract/thermal sclerostomy group, 61% had improvement in visual acuity, 61% had normalization of intraocular pressures without antiglaucoma medications, 17% had transient postoperative hyphemas. We could not correlate any of the complications of surgery with poor intraocular pressure results in either groups. The mechanism for the higher success rate with a combined cataract extraction and trabeculectomy as compared with a combined cataract extraction and thermal sclerostomy was not obvious after analyzing these patients.