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.

The relation of total body potassium to height, weight, and age in normal adults.

Total body potassium was measured in 103 healthy adults using a shadow-shield whole-body monitor of high sensitivity. The range of height was 147 to 192 cm, of weight 43 to 92 kg, and of age 18 to 77 years. The values obtained for total body potassium were correlated with height, with weight, and with height and weight. Age was then included as an additional variable. The standard deviation from regression was smaller when total body potassium was correlated with height than with weight and was further reduced, to about 9%, in a multiple regression using height and age. The advantages of this relationship over indices involving weight are discussed. The smallest standard deviation from regression, 7.5%, was obtained when total body potassium was correlated with height, weight, and age. The usefulness of this relationship is discussed with comment on its limitations.A regression equation was derived between lean body mass (derived from height and weight) and total body potassium with a standard deviation from regression of 5.5% in males and 7.3% in females.

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.

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.

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.

The ion-binding characteristics of reconstituted collagen.

The ion-binding capacity of highly purified reconstituted calf-skin collagen, and the effects of these ions on the precipitation and solubility of the collagen, were studied with a variety of salt solutions at ionic strength 0.16 and pH7.4. Only a small percentage of the total theoretically available anionic and cationic groups was available for ion-binding. In view of this, it appears that most of the ionizable groups of collagen are involved in intramolecular or intermolecular linkages, or both. Nevertheless, marked differences in the binding of the various ions by collagen were observed. Bivalent cations were bound in extremely small but remarkably similar quantities. In contrast, sodium was bound both in much higher and more variable quantities. Of the anions, pyrophosphate and sulphate were bound in the largest quantities, followed by phosphate, fluoride and chloride, in that order. Despite the minimal uptake by collagen of bivalent cations, they prevented the aggregation of tropocollagen into fibrils, and disaggregated fibrillar collagen. In the presence of multivalent anions, tropocollagen aggregated readily and its fibrillar stability was maintained. On the basis of the imbalance in the binding of ion pairs by the sodium pyrophosphate- and sodium phosphate-treated collagens, it was apparent that a reduced number of side-chain carboxyl groups were dissociated in the presence of these salts.

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.