Determination of ruthenium and iridium in anode coatings by atomic-absorption spectroscopy.

A method is described for the determination of ruthenium and iridium coated on an electrode surface. The coating is chemically removed from the electrode by fusion with alkali, and the resulting solution prepared for analysis. Interelement interferences are eliminated by using a titanium-potassium matrix solution as a releasing agent. Recovery and precision data are given for ruthenium and iridium. The AAS determination of ruthenium compares favourably with a standard colorimetric method.

Determination of acid-soluble and total rhodium on alumina-supported catalysts.

Characterization of alumina-supported catalysts required determination of rhodium by atomic-absorption spectroscopy (AAS). Catalysts were loaded with 0.1-2.0% rhodium chloride and calcined at 400 degrees . Rhodium remaining as the chloride was regarded as the soluble form, while that converted into the oxide or bonded to the alumina was regarded as the bonded form. By selective dissolution procedures, soluble rhodium was leached from the substrate and determined by AAS. Total rhodium was determined after the catalyst had been fused with sodium peroxide. Bonded rhodium can be determined by difference or by analysing leached residue. Optimization of AAS conditions, use of spectroscopic buffer solution and elimination of interelement interferences are discussed.

Determination of ruthenium and tin on electrochemical anodes by energy-dispersive X-ray fluorescence.

"Dimensionally Stable Anodes" (DSA)(R) have gained wide acceptance in electrochemical production of chlorine and caustic soda. The DSAs are usually composed of electrocatalytic layers of precious and non-precious metal oxides produced by thermal decomposition of salts on a valve-metal substrate (e.g., titanium). They have long lifetimes (some years) in commercial service, and accelerated aging is used in testing them. In these tests the cell potential is stable for most of the anode life. Failure of an anode is characterized by a rapid increase in potential to beyond the point of practical operation of the cell. Non-destructive X-ray techniques have been utilized to investigate the mechanism involved. It has been established that the precious metal content has been reduced by 50-60% when the anodes fail. Although present DSA coatings are more than adequate for commercial applications, there is continuing interest in improving them. The materials for DSA formulation include the precious metals iridium, ruthenium and rhodium, the non-precious metals tin, antimony and manganese, and the valve metals titanium and tantalum.

Mild head injury is not always mild; implications for damage litigation.

The traditional view that mild head injury involves an essentially reversible physiological process is examined and is found to be largely invalid. It is concluded that long-term impairment following mild head injury is fairly common and that the degree of impairment can be assessed clinically. Such an assessment involves a combination of objective electrophysiological and psychometric investigations as well as professional interpretation. With the use of this approach the possibility of malingering can be ruled out in most cases and significant impairment, when it exists, can be demonstrated beyond reasonable doubt.

Comparisons among neo-Lurian assessment measures of brain-injured adults.

The performances of 49 brain-injured community college students (41% women; M age = 34.0 yr., SD = 13.6) on two neo-Lurian assessment batteries were investigated. Pearson correlations among the 11 clinical subtests of the Luria-Nebraska Neuropsychological Battery, Form I and 10 Planning, Attention, Simultaneous Processing, and Successive Processing (PASS) experimental tasks are reported. While the correlations were largely weak to moderate, a few interpretable trends in these relationships emerged. Over-all, the irregular and diffuse pattern of significant correlations may, in part, reflect the heterogeneity of the Luria-Nebraska battery's subscales. Implications for the cognitive assessment and remediation of patients with brain injuries are briefly discussed.

Proposals to modify the taxation of Social Security benefits: options and distributional effects.

This article presents simulation estimates of the income-distributional effects in 1994 of several proposals to modify the taxation of Social Security benefits under the Federal personal income tax. Under the benefit-taxation provisions that have been in effect since 1984, up to 50 percent of benefits are included in taxable income for taxpayers with incomes above certain thresholds. In 1994 about 20 percent of beneficiary families will pay a larger income tax as a result of these provisions. Because of the benefit taxation thresholds, the affected families are concentrated in the upper half of the income distribution: about 70 percent of these families have incomes that put them in the top 30 percent of families by income. If the current taxation thresholds were kept and the percentage of benefits includable in taxable income were raised above 50 percent, the tax effect would remain concentrated on the upper income families. If, on the other hand, the percentage includable were kept at 50 percent while the taxation thresholds were lowered or eliminated, more beneficiary families with incomes in the middle deciles would become affected. The lowest income beneficiary families, however, would remain unaffected, because their benefits would be protected from income taxation by exemptions and the standard deduction. The simulations indicate that only a very few families in the bottom 20 percent of families by income would be affected even if the benefit taxation thresholds were eliminated entirely.

Efficacy of an educationally-based cognitive retraining programme for traumatically head-injured as measured by LNNB pre- and post-test scores.

Traumatic head-injuries have been described as a national 'silent epidemic' (Wall Street Journal) and within the medical rehabilitation field it is becoming increasingly recognized that the care and service needs for this population significantly surpass the typical scope of acute rehabilitation services. From the literature, it is suggested that long-term recovery is contingent upon the person remaining within a structured, therapeutic environment. Cognitive retraining is one such area of therapeutic service. The major goal of an educational retraining programme for traumatically head-injured students is to maximize each individual's potential for independent functioning, which is promoted through improvement in cognitive functioning, social and emotional adjustments and transitional living experiences. The pre- and post-tests results for this were analyzed collectively utilizing standard T-test comparison procedures for groups with correlated means (SPSS 1983). The results of each student were then analysed individually utilizing the procedure described for subjects measured with the LNNB by Knight and Godfrey (1983).

Current perceptions of rehabilitation professionals towards mild traumatic brain injury.

There has been long-standing controversy in the medical literature and increasing interest within the rehabilitation field in mild traumatic brain injury and postconcussion syndrome. The Head Injury Interdisciplinary Special Interest Group of the American Congress of Rehabilitation Medicine conducted an opinion survey to analyze the perceptions of rehabilitation professionals towards patient's with these problems. The survey initially compared response patterns of rehabilitation personnel to two earlier identical surveys made with a group of neurosurgeons and a group of neuropsychologists. As a group, rehabilitation professionals tend to have perceptions of mild traumatic brain injury that are similar to those of neuropsychologists. The survey also included a group of questions developed to analyze specific issues among rehabilitation professionals related to symptomatology, persistence, and treatment. The most salient findings concluded that rehabilitation providers: (1) want a grading system associated with the term to designate injury severity, symptom severity, and level of functional impairment; (2) most frequently use neuropsychologists in assessment and treatment of these patients; (3) report cognitive deficits as the most common symptom, followed by irritability and somatic complaints; (4) when medications are used, most frequently use antidepressants; (5) typically follow these patients anywhere from six to 18 months postinjury; and (6) report that most patients make a complete functional recovery, though there is a substantial proportion (about 25%) who do not. Implications drawn from the survey include that there is a need to better define the term and its associated features and that there is a substantial group of patients who remain at least partially functionally disabled and present a major challenge to the rehabilitation community.

Computerized measurement of cognitive impairment and associated neuropsychiatric dimensions.

This study aimed to cross-validate the capacity of a computer software program to detect and measure, using a measurement method applied to the content and form analysis of 5-minute speech samples, cognitive impairment and associated comorbid neuropsychiatric psychobiological dimensions in drug-abusing patients. At the University of California-Irvine (UCI) Neuropsychiatric Center, 28 drug-abusing inpatients using illegal drugs were clinically evaluated. Their scores for cognitive impairment derived by the computerized content analysis method were compared with scores derived from selected tests from the Halstead-Reitan Neuropsychological Test Battery, the computerized Automated Neuropsychological Assessment Metric Battery (ANAM), the Alzheimer's Disease Assessment Scale-Cognitive Portion, the Stroop Color and Word Test, the Symbol Digit Modalities Test, and the Controlled Oral Word Association Test. The statistical significance (P value) of the correlations of scores from these different measures with scores obtained from the computerized content analysis measures was less than .05 to .001. The comparative "hit rate," detecting cognitive impairment above the norms for each measure administered to these drug-abusing patients, for the computerized content analysis measures and some of the ANAM neuropsychological measures was 75% to 89%, and for the other neuropsychological measures, 25% to 64%. In conclusion, the computerized content analysis methodology applied to 5-minute verbal samples is a valid, rapid, easily administered measurement instrument for assessing the magnitude of cognitive impairment and comorbid neuropsychiatric dimensions.

Evidence-based cognitive rehabilitation: recommendations for clinical practice.

OBJECTIVE: To establish evidence-based recommendations for the clinical practice of cognitive rehabilitation, derived from a methodical review of the scientific literature concerning the effectiveness of cognitive rehabilitation for persons with traumatic brain injury (TBI) or stroke. DATA SOURCES: A MEDLINE literature search using combinations of these key words as search terms: attention, awareness, cognition, communication, executive, language, memory, perception, problem solving, reasoning, rehabilitation, remediation, and training. Reference lists from identified articles also were reviewed; a total bibliography of 655 published articles was compiled. STUDY SELECTION: Studies were initially reviewed according to the following exclusion criteria: nonintervention studies; theoretical, descriptive, or review papers; papers without adequate specification of interventions; subjects other than persons with TBI or stroke; pediatric subjects; pharmacologic interventions; and non-English language papers. After screening, 232 articles were eligible for inclusion. After detailed review, 61 of these were excluded as single case reports without data, subjects other than TBI and stroke, and nontreatment studies. This screening yielded 171 articles to be evaluated. DATA EXTRACTION: Articles were assigned to 1 of 7 categories according to their primary area of intervention: attention, visual perception and constructional abilities, language and communication, memory, problem solving and executive functioning, multi-modal interventions, and comprehensive-holistic cognitive rehabilitation. All articles were independently reviewed by at least 2 committee members and abstracted according to specified criteria. The 171 studies that passed initial review were classified according to the strength of their methods. Class I studies were defined as prospective, randomized controlled trials. Class II studies were defined as prospective cohort studies, retrospective case-control studies, or clinical series with well-designed controls. Class III studies were defined as clinical series without concurrent controls, or studies with appropriate single-subject methodology. DATA SYNTHESIS: Of the 171 studies evaluated, 29 were rated as Class I, 35 as Class II, and 107 as Class III. The overall evidence within each predefined area of intervention was then synthesized and recommendations were derived based on consideration of the relative strengths of the evidence. The resulting practice parameters were organized into 3 types of recommendations: Practice Standards, Practice Guidelines, and Practice Options. CONCLUSIONS: Overall, support exists for the effectiveness of several forms of cognitive rehabilitation for persons with stroke and TBI. Specific recommendations can be made for remediation of language and perception after left and right hemisphere stroke, respectively, and for the remediation of attention, memory, functional communication, and executive functioning after TBI. These recommendations may help to establish parameters of effective treatment, which should be of assistance to practicing clinicians.