Postweld electrotransport treatment

Hydrogen damage susceptibility of high-strength steel weldments and in other advanced materials, such as intermetallics, is a problem that restricts their application in many structural uses. A high-temperature (~500 °C) postweld treatment is often applied to remove the diffusible hydrogen and make the material more resistant to hydrogen damage. An electrotransport technique, using a direct current, can be applied at room temperature to move hydrogen from the underbead region, which is crack susceptible. The method has been used to electrorefine many metals and alloys containing both interstitial and substitu-tional solutes. This paper reviews the electrotransport theory and applies it to estimate the time of electrotransport treatment for lowering the hydrogen content from the underbead region by 50%. Thus, this theoretical work forms the basis for developing a new practice and provides sample calculations. Under a combined influence of the diffusional and electrotransport at room temperature using an electric field of 0.10 V/cm, ~30 min is required to remove 50% of the hydrogen from a starting concentration of 5 ppm. Theoretically, the treatment will also generate a heat of 0.95 kcal/s, which may not cause an excessive temperature increase in the workpiece. The electrotransport technique thus has the potential for a low-cost, low-temperature practice for mitigating hydrogen damage susceptibility.     

Improving certified nurse aide retention. A long-term care management challenge

In the long-term care industry, the turnover rate among nurse aides is extremely high. This adversely affects resident satisfaction, resident care, morale, and finances. It presents a challenge to long-term care administration. Refusing to accept high turnover as an impossible situation allows changes to be made. The authors describe how the staff at one intermediate care facility identified its problems, assessed the causes, and implemented corrective action.     

The use of computed tomography in stereotaxic operations in dyskinesia patients

The pool of free purine derivatives and activities of the key enzymes of purine metabolism (adenosine deaminase, purine nucleoside phosphorylase, and 5'-nucleotidase) in lymphocytes, erythrocytes, and epidermis homogenates were measured in 20 normal subjects and 15 patients with psoriasis by high-performance liquid chromatography. The levels of AMP, GMP, and IMP purine monophosphates are decreased in the epidermis and red cells of psoriasis patients, whereas the final products of hypoxanthine, xanthine, and uric acid metabolism are accumulating, and the activities of ADA and PNP are increased double in the skin, all this indicating purine derivatives catabolism.     

Screening asymptomatic patients for colorectal lesions

The genetic structure of temperature preference of D. immigrans was analyzed by a 4 x 4 diallel cross. Preference for low temperature was dominant to that for high temperature. Partition of the variance showed that most of the variance was additive; the variance caused by dominance was small but significant, and non-additive, non-dominance variance was not significant. Heritability of the temperature preference was 0.81. There may be a few genes involved in variation for temperature preference.     

Effect of topical anesthetic use on initial patient satisfaction and overall success with rigid gas permeable contact lenses

BACKGROUND: Rigid gas permeable (RGP) contact lenses have numerous benefits; however, RGP lens use is not increasing in the United States. An important factor for this trend has been initial comfort. Studies have demonstrated that how RGPs are presented to patients, in addition to lens design, can play an important role in the initial comfort process. Another important factor could be the use of a topical anesthetic during the fitting and dispensing visits. The purpose of this study was to use a multicenter format to determine if topical anesthetic use increased the likelihood of patient satisfaction and success. METHODS: A total of 80 subjects, with no previous rigid lens wear experience, was entered into this 1-month study, including 20 subjects from each of 4 institutions. Subjects were randomly divided into the following two groups: (A) anesthetic or (B) placebo, with the former group receiving one drop of a topical anesthetic before lens insertion at both the diagnostic fitting and dispensing visits, whereas the latter group received a placebo. Subjects completed a questionnaire on their perception of rigid lens wear both immediately before fitting and at the 1-month visit. After diagnostic fitting with rigid lenses, subjects completed an adaptation questionnaire after 15 min, 1 week, 2 weeks, and 1 month of lens wear. RESULTS: Seventy of the 80 subjects completed the study and, of the 10 subjects who discontinued, 8 were in the placebo group. In all categories evaluated, the anesthetic group experienced a more optimum adaptation experience at each visit vs. the placebo group. Specifically, overall comfort was rated significantly higher at both dispensing and 2 weeks. In addition, the anesthetic group exhibited significantly greater overall satisfaction with rigid lens wear at 2 and 4 weeks. Also, the anesthetic group perceived their adaptation, sensitivity, and adaptation time to be significantly better at the 1-month visit. There was no significant difference in corneal staining between these two groups at each visit, with the exception of a greater amount of staining in the central quadrant for the placebo group at the 1-month visit. CONCLUSIONS: The use of a topical anesthetic at the fitting and dispensing visits for first-time wearers of RGP lenses resulted in significantly fewer dropouts, improved initial comfort, an enhanced perception of the adaptation process, and greater overall satisfaction after 1 month of lens wear as compared to the use of a nonanesthetizing placebo at those visits. This result, in combination with both presenting RGP lenses in a nonthreatening manner and optimizing the lens design and fitting relationship, should result in a positive adaptation process and successful wear of RGP contact lenses.     

A thermodynamic criterion to predict wettability at metal- alumina interfaces

Metals are known to wet ceramics by chemical bond formation. Existing theories, using reaction thermodynamics, can predict the relative wetting trends in wetting systems but fail to distinguish between the wetting and non wetting systems. Wetting is considered as a surface phenomenon, and the spontaneity of wetting is controlled by ΔG_W, a thermodynamic term defined here as the Gibbs free energy of wetting. A model that treats wetting as a reaction between the surface phase of the ceramic and the molten metal is presented to calculate ΔG_W. The model is used to predict wetting tendencies of various molten metals on α-alumina surfaces. The predictions are compared with previously published results, as well as with the experimental results of this study. Experimental wettability parameters were measured using a capillary rise apparatus. Measurements were made for various metals wetting an aluminum-oxide surface. Based on this model, a thermodynamic wetting map that delineates wetting and non wetting regimes is drawn. A map of this nature can be used advantageously in ceramic joining and metal-matrix composites applications.     

Actin mutations in dilated cardiomyopathy, a heritable form of heart failure

To test the hypothesis that actin dysfunction leads to heart failure, patients with hereditary idiopathic dilated cardiomyopathy (IDC) were examined for mutations in the cardiac actin gene (ACTC). Missense mutations in ACTC that cosegregate with IDC were identified in two unrelated families. Both mutations affect universally conserved amino acids in domains of actin that attach to Z bands and intercalated discs. Coupled with previous data showing that dystrophin mutations also cause dilated cardiomyopathy, these results raise the possibility that defective transmission of force in cardiac myocytes is a mechanism underlying heart failure.