Assessing the antifouling properties of cold-spray metal embedment using loading density gradients of metal particles.

Particles of copper, bronze and zinc were embedded into a polymer using cold-spray technology to produce loading density gradients of metal particles. The gradients were used to identify the species with the highest tolerance to the release of copper and zinc ions. The gradients also established the minimum effective release rates (MERRs) of copper and zinc ions needed to prevent the recruitment of fouling under field conditions. Watersipora sp. and Simplaria pseudomilitaris had the highest tolerances to the release of metal ions. Copper and bronze gradient tubes were similar in their MERRs of copper ions against Watersipora sp. (0.058 g m(-2) h(-1) and 0.054 g m(-2) h(-1), respectively) and against S. pseudomilitaris (0.030 g m(-2) h(-1) and 0.025 g m(-2) h(-1), respectively). Zinc was not an effective antifoulant, with failure within two weeks. In conclusion, cold-spray gradients were effective in determining MERRs and these outcomes provide the basis for the development of cold-spray surfaces with pre-determined life-spans using controlled MERRs.

Polyurethane seismic streamer skins: an application of cold spray metal embedment.

Cold spray metal embedment is an innovative antifouling (AF) technology that delivers metal particles with AF properties into many thermoplastic polymers. AF efficacy was quantified for low (22.1 ± 4.8 g m(-2)) and high (101.1 ± 10.8 g m(-2)) densities of copper particles embedded into polyurethane (PU) seismic streamer skins, which are used in geophysical exploration. Failure of each Cu-embedded treatment was defined as settlement of hard foulers. Low-density streamers failed after 42 days while high-density streamers failed after 210 days. Most importantly, the high-density streamers were completely free of hard foulers including the barnacle Amphibalanus reticulatus during this time period. In conclusion, cold-spray metal embedment is an effective AF technology for PU seismic streamer skins, under intense fouling conditions. Higher copper particle densities enhance AF longevity and the effect of density provides a tool to extend efficacy and enhance AF performance for specific polymers.

Cold spray metal embedment: an innovative antifouling technology.

The study demonstrates that embedment of copper particles into thermoplastic polymers (polymers) using cold spray technology is an effective deterrent against fouling organisms. Two polymers, high-density polyethylene (HDPE) and nylon were metallised with copper powder using cold spray technology. After 250 days in the field, Cu-embedded HDPE and copper plate controls were completely free of hard foulers compared to Cu-embedded nylon and polymer controls which were heavily fouled with both soft and hard fouling. Antifouling (AF) success is related to the interaction between the properties of the polymers (elastic modulus and hardness) and the cold spray process which affect particle embedment depth, and subsequently, the release of copper ions as determined by analytical techniques. Embedding metal using cold spray equipment is shown to be an effective AF technology for polymers, in particular those that are difficult to treat with standard AF coatings, with efficacy being a function of the interaction between the cold spray metal and the polymer recipient.

Pulsed high intensity focused ultrasound mediated nanoparticle delivery: mechanisms and efficacy in murine muscle.

High intensity focused ultrasound (HIFU) is generally thought to interact with biological tissues in two ways: hyperthermia (heat) and acoustic cavitation. Pulsed mode HIFU has recently been demonstrated to increase the efficacy of a variety of drug therapies. Generally, it is presumed that the treatment acts to temporarily increase the permeability of the tissue to the therapeutic agent, however, the precise mechanism remains in dispute. In this article, we present evidence precluding hyperthermia as a principal mechanism for enhancing delivery, using a quantitative analysis of systemically administered fluorescent nanoparticles delivered to muscle in the calves of mice. Comparisons were carried out on the degree of enhancement between an equivalent heat treatment, delivered without ultrasound, and that of the pulsed-HIFU itself. In the murine calf muscle, Pulsed-HIFU treatment resulted in a significant increase in distribution of 200 nm particles (p < 0.016, n = 6), while the equivalent thermal dose showed no significant increase. Additional studies using this tissue/agent model also demonstrated that the pulsed HIFU enhancing effects persist for more than 24 h, which is longer than that of hyperthermia and acoustic cavitation, and offers the possibility of a novel third mechanism for mediating delivery.

Delivering care to the streets.

St. Francis Hospital's management team has collaborated with other community organizations to respond to the very real needs of the homeless and indigent in Wilmington, DE. St. Francis Hospital has developed two innovative programs: St. Clare Medical Outreach and Tiny Steps. Recognizing that the poor and indigent find transportation, clinic schedules, and intimidating paperwork to be major barriers to healthcare, St. Francis Hospital and its partner in this collaborative ministry, Ministry of Caring, sought a creative approach that would bring healthcare to Wilmington's needy in a nonthreatening way, while also offering continuity of care. St. Clare Medical Outreach van staff began administering much-needed healthcare services on April 27, 1992. For years, St. Francis Hospital has supported a pediatric clinic at West End Neighborhood House, an organization offering a variety of family-related services to the indigent. In September 1992 the hospital collaborated with other community organizations to offer a more comprehensive, holistic healthcare service to those in need. This joint-venture of St. Francis Hospital and 11 other community organizations is designed to lower the infant mortality rate by identifying high-risk pregnancies early on and managing complications during pregnancy and after birth.

Skeletal manifestations of primary oxalosis.

We describe the clinical, radiographic and histological features of skeletal involvement in four patients with end-stage renal failure due to primary oxalosis. The clinical features were unrelenting bone pain, and in two patients multiple fractures. Radiographic features were, in chronological order: (1) radiodense metaphyses and other red marrow bone; (2) cortical defects in metaphyses; (3) spontaneous fracture-separations of epiphyses of long limb bones which healed poorly. The fractures occurred through crystal deposits, and fracture displacement was associated with extrusion of crystalline material from bone. On histological examination crystals were found to replace metaphyseal bone. Pericrystalline giant cell granulomata replaced bone marrow. Erosion surfaces near granulomas were increased. Subperiosteal and intra-osseous tophi of calcium oxalate were seen. Calcium oxalate appears to precipitate with greater facility than does physiological mineral. Bone showed the features of mixed uraemic osteodystrophy in all four patients. We conclude that: (1) the fractures occurred through heavy crystal deposits; (2) ununited fractures and intra-osseous and subperiosteal tophi contributed to the pain; (3) spontaneous fractures are of poor prognostic significance. We recommend that unstable fractures be internally fixed.

Cuts to the quick. How to soften the blow of layoffs.

No one relishes a layoff, but with the volatile changes in healthcare, financial imperatives may force many administrators into the unpleasant task of laying off trusted employees. When faced with the possibility of closing a hospital's doors, personnel reductions may be the only reasonable alternative. The actual process of laying off employees can be traumatic. At a time so highly charged with emotion, it is best to have a procedure to follow. Layoffs should affect employees in every pay grade and not single out any one group. Also, managers should take employees outside their department to give them the bad news. The plan should also include a list of those to be let go, criteria for the order of layoffs, and a list of teams to meet with affected employees. In addition, managers should ascertain the total cash entitlement for each employee to be let go and arrange for a complete paycheck on the last day, prepare to discuss other pay options that are available, gather all documents pertaining to the employee, and give the employee all the information in writing.

Meningococcaemia complicated by myocarditis. A report of 2 cases.

Two cases of myocarditis complicating meningococcal septicaemia are presented. Neisseria meningitidis infection with bacteraemia is a common entity but the important complication of myocarditis has not often been described. The autopsy findings in 1 of the 2 patients described further illustrates the significance of myocarditis. The pathology, clinical presentation and management of this complication are briefly discussed.

Acute promyelocytic leukaemia associated with acute myocardial infarction. A case report.

In a case of acute promyelocytic leukaemia presenting with an acute myocardial infarction a fibrin-platelet thrombus was demonstrated postmortem in the anterior descending branch of the left coronary artery. The possible pathogenesis of thrombus formation in the face of disseminated intravascular coagulation and thrombocytopenia is discussed.

The relationship between uric acid and potassium in normal subjects.

The serum uric acid concentration in normal healthy subjects has been studied in relation to sex, height, weight, lean body mass measured from total body potassium and predicted from the Hume-Weyers formula (1971), total body potassium, plasma potassium and urea, and packed cell volume. The strongest correlation was found with sex, but height, weight, total body potassium, lean body mass (measured and predicted) also correlated significantly with serum uric acid concentration. However, when the sex variable was removed, the other factors lost their significant correlation. Finally, total red blood cell and plasma volumes were predicted (Hume and Goldberg, 1964) and from these an estimate of total plasma uric acid, total plasma potassium, and total red blood cell potassium obtained. Measured total body potassium was found to correlate well with total plasma potassium and total red blood cell potassium independent of sex. Total plasma uric acid correlated well with measured total body potassium when both sexes were considered and when separated into male and female groups the males retained a significant correlation as did the female group.

The relation between potassium in body fluids and total body potassium in healthy and diabetic subjects.

1. The concentration of potassium in the erythrocytes and the plasma of forty-one normal subjects and twenty-five diabetic patients was measured and the results were used to calculate the total amount of potassium in the erythrocyte mass and the total amount of potassium in the plasma. The total body potassium was measured in a whole-body monitor. 2. In normal subjects a close correlation was found between total erythrocyte potassium and total body potassium and also between total plasma potassium and total body potassium. 3. The regression relation between total body potassium and total erythrocyte potassium in normal subjects was used to predict the total body potassium in diabetic patients. There was reasonable agreement between the measured and predicted total body potassium but there was poor agreement between the measured total body potassium and that predicted from the patient's height and age or height and age or height, weight and age.

Total body potassium in children, with particular reference to coeliac disease.

1. Total body potassium was measured, by wholebody counting, in children with coeliac disease and in children not having this disease, matched as closely as possible with respect to sex, height, weight and age. 2. The measured total body potassium in children with coeliac disease was not significantly different from that in the matched children. 3. The problems associated with such measurements, particularly those of interpretation, are considered.

Whole body potassium in patients with ureterosigmoid anastomoses.

Total body potassium was measured by whole body counting in 11 patients with uretero-sigmoid anastomoses who had undergone cystectomy 4 months to 13 years previously. The measured total body potassium was not significantly different in any of the patients from the "normal" value for the individual patients, predicted from height and age. It was only significantly different from that predicted from height, age and weight in 1 patient. In the series as a whole, the measured values of whole body potassium were not significantly different from the "normal" values estimated by either relationship. From measurements of skinfold thickness, the lean body mass of each patient was estimated. The mean potassium content, 62-0 mEg/kg LBM in the male patients was within the normal range. The absence of potassium depletion may derive from the successful abolition of hyperchloraemic acidosis by long-term alkali therapy.

The distribution and retention of cadmium 115m in the rat following injection into the prostate.

The gonadal effects produced by injection of cadmium in the rats are well known. The effects of direct injection into the prostate are less well understood. The present experiments indicated the retention of cadmium by the various lobes of the rat prostate following direct injection of radioactive cadmium into the organ. The cells of the prostate are capable of retaining cadmium in measurable amounts up to at least 6 weeks following the injection. The subcellular fractions were measured with respect to cadmium activity and these are indicated. In addition measurements were made in organs which are known to be affected by cadmium, that is, kidney and the testicle. The affinity of the kidney for cadmium is confirmed. The areas of the prostate gland with a high zinc content appear to retain less cadmium than areas of the gland which are known to have a low zinc content. This suggests a possible zinc protective mechanism.

Total body potassium in long-term frusemide therapy: is potassium supplementation necessary?

Measurements of total body potassium (T.B.K.) were made by whole-body counting in four groups of patients receiving oral frusemide for one year. Patients in group 1 had essential hypertension and normal renal function and received 40 mg frusemide daily without potassium supplements. Patients in group 2 were similar but received oral potassium supplements for the first four months of treatment. Patients in group 3 had hypertension associated with renal disease and received 120 mg frusemide daily without potassium supplements. Patients in group 4 also had hypertension and renal impairment and in addition to 120 mg frusemide daily they received oral potassium supplements for four months. No evidence of depletion of T.B.K. was found in any of the groups after continuous treatment with frusemide for one year. It is questioned whether potassium supplementation in long term diuretic therapy with frusemide is necessary unless there is evidence of pre-existing potassium depletion or of some other factor such as cardiac failure, cirrhosis of the liver, or the nephrotic syndrome.