3D-printed poly(vinylidene fluoride)/carbon nanotube composites as a tunable, low-cost chemical vapour sensing platform.

We report the production of flexible, highly-conductive poly(vinylidene fluoride) (PVDF) and multi-walled carbon nanotube (MWCNT) composites as filament feedstock for 3D printing. This account further describes, for the first time, fused deposition modelling (FDM) derived 3D-printed objects with chemiresistive properties in response to volatile organic compounds. The typically prohibitive thermal expansion and die swell characteristics of PVDF were minimized by the presence of MWCNTs in the composites enabling straightforward processing and printing. The nanotubes form a dispersed network as characterized by helium ion microscopy, contributing to excellent conductivity (∼3 × 10-2 S cm-1). The printed composites contain little residual metal particulate relative to parts from commercial PLA-nanocomposite material visualized by micro-X-ray computed tomography (µ-CT) and corroborated with thermogravimetric analysis. Printed sensing strips, with MWCNT loadings up to 15% mass, function as reversible vapour sensors with the strongest responses arising with organic compounds capable of readily intercalating and subsequently swelling the PVDF matrix (acetone and ethyl acetate). A direct correlation between MWCNT concentration and resistance change was also observed, with larger responses (up to 161% after 3 minutes) being generated with decreased MWCNT loadings. These findings highlight the utility of FDM printing in generating low-cost sensors that respond strongly and reproducibly to target vapours. Furthermore, the sensors can be easily printed in different geometries, expanding their utility to wearable form factors. The proposed formulation strategy may be tailored to sense diverse sets of vapour classes through structural modification of the polymer backbone and/or functionalization of the nanotubes within the composite.

Blood recipient notification for hepatitis C in Prince Edward Island.

BACKGROUND: Two of the major risk factors for hepatitis C are injection drug use and receipt of blood or blood products. Many patients are unaware that they have received transfusions. In 1998 Prince Edward Island conducted a province-wide look-back notification program to notify patients who had received transfusions in PEI between Jan. 1, 1984, and June 1, 1990. The authors present the results of the notification program. METHODS: A registry for recipients of blood and blood products was created from the province's Red Cross blood bank records. The registry data were linked with Vital Statistics data to determine death status and with Health Registration data to determine residence status of recipients (in PEI or moved out of province). All identified recipients with a current PEI mailing address were sent a letter recommending hepatitis C virus (HCV) testing. Laboratory records were checked to determine HCV test results. RESULTS: The registry contained data for 6086 recipients of blood or blood products during the look-back period; 51.1% (3109/6086) had died by the time of notification. Of the remainder, 18.4% (549/2977) were not directly notified because they had moved out of province, had refused delivery of the notification letter or had died recently, or because identifying information was missing from the blood bank records. Of the recipients who were notified 80.4% (1953/2428) underwent testing, and 2.2% (43/1953) were found to be HCV positive. Most of these (58.1% [25/43]) had undergone testing before notification. The HCV positivity rate differed significantly between recipients tested before notification and those tested after notification (9.9% v. 1.1%, p < 0.001). HCV-positive recipients were more likely than other notified recipients to have had multiple transfusions (39.5% v. 9.5%, p < 0.001). INTERPRETATION: Before notification 4.1% of PEI recipients had undergone HCV testing. After notification 91.2% of PEI recipients were identified as tested, dead or moved out of province. The notification program resulted in the identification of the majority of PEI's transfusion-related cases of hepatitis C.

U.S. Army dietitians deploy in support of Cobra Gold: a humanitarian mission.

Dietitians are multifunctional and play an important role in humanitarian missions as educators, planners, and consultants. Three dietitians deployed to Thailand in support of the 16th Annual Joint and Combined Exercise, Cobra Gold 1997. The goal of the Medical Civic Assistance Program (MEDCAP) was to promote long-term public health improvements in rural Thai villages. The dietitians counseled 140 patients and taught an additional 5,300 individuals during nutrition classes. The primary nutrition-related clinical diagnoses included malnutrition, anemia, diabetes, hypertension, goiter, and poor appetite. The dietitian who deployed as the medical planner and MEDCAP executive officer facilitated coordination and planning for all phases of the MEDCAP operation. The teams were made up of U.S. and Thai military forces and Thai civilian medical personnel. The mission requirements were established with the Royal Thai Supreme Command, Thai governors, Ministry of Public Health officers, military and medical officers, and veterinarians of the three provinces.

Tuberculin skin testing in a hospital and two chronic care facilities in Prince Edward Island.

OBJECTIVE: To determine the prevalence of initial and booster positive responses to tuberculin skin testing among staff of an acute care hospital, and among staff and residents of two chronic care facilities on Prince Edward Island (PEI). PATIENTS AND METHODS: Two hundred and eighty-six staff from the hospital and the facilities, and 164 residents from the facilities were given tuberculin testing using 5 tuberculin units (TU) of purified protein derivative (PPD) of tuberculin. A two-step booster test was performed on 125 of 173 staff (73%) aged 35 years or older who initially tested negative, and on 138 of 141 residents (97.9%) at the chronic care homes. RESULTS: The overall rate of initial tuberculin positivity among staff at the facilities was 15.7%. Among residents, the rate of positivity was 14.0%. Histories given by institutional staff of having previously received Bacille bilié de Calmette-Guérin vaccine (BCG) were associated with tuberculosis (TB) test reactivity, but not with mean reaction size. Staff with a history of BCG who tested positive did not differ in age from those testing negative. Institutional staff whose work involved patient contact were more likely to have a positive test than those whose work did not involve such contact. Booster positivity among those older than 35 years of age ranged from 2.0 to 5.2%. CONCLUSIONS: These results suggest that, for health care institutions in PEI, tuberculin testing should be performed on all new or current hospital staff at risk of TB exposure, all new or current staff of chronic care facilities, and all new or current residents of chronic care facilities unless contraindicated. Booster testing should also be performed on all institutional staff and residents 35 years of age or older if their initial tuberculin test is negative.

Hepatitis B prenatal screening survey, Nova Scotia, 1990-1991.

We conducted a study in which 5,754 pregnant women who delivered at the Grace Maternity Hospital in Halifax were screened for HBsAg. There were five who were found to be seropositive for the first time (a screening yield for seropositivity of 8.7/10,000). Overall six were seropositive for a prevalence rate of 10.4/10,000. These rates are above the 6.0/10,000 level at which routine prenatal screening is considered to be cost-effective. Screening based upon risk factors would have identified only two of the five women who were found for the first time to be HBsAg seropositive. Based upon the results of this study, we recommend that routine screening for HBsAg be performed on all prenatal women in Nova Scotia.

Obesity and its relation to cardiovascular disease risk factors in Canadian adults. Canadian Heart Health Surveys Research Group.

OBJECTIVE: To describe the distribution of weight and abdominal obesity among Canadian adults and to determine the association of obesity with other risk factors for cardiovascular disease. DESIGN: Population-based cross-sectional surveys. Survey nurses administered a standard questionnaire and recorded two blood pressure measurements during a home visit. At a subsequent visit to a survey clinic two further blood pressure readings were made, anthropometric measurements recorded and a blood specimen taken for plasma lipid determination. SETTING: Nine Canadian provinces, from 1986 to 1990. PARTICIPANTS: A probability sample of 26,293 men and women aged 18 to 74 years was selected from the health insurance registration files of each province. Anthropometry was performed on 17,858 subjects. OUTCOME MEASURES: Body mass index (BMI), ratio of waist to hip circumference (WHR), mean plasma lipid levels, prevalence of high blood pressure (diastolic greater than or equal to 90 mm Hg or patient on treatment) and self-reported diabetes mellitus. MAIN RESULTS: The prevalence of obesity (BMI greater than or equal to 27) increased with age and was greater in men (35%) than in women (27%). Abdominal obesity was likewise higher in men and increased with both age and BMI. The prevalence of high blood pressure was greater in those with higher BMI, especially in those with a high WHR. Although total plasma cholesterol levels increased only modestly with BMI, levels of low density lipoprotein (LDL) cholesterol and triglycerides and the ratio of total cholesterol to high density lipoprotein (HDL) cholesterol increased steadily, while HDL-cholesterol decreased consistently with increasing BMI. High total cholesterol levels (greater than or equal to 5.2 mmol/L) were more prevalent among people with high BMI, especially those with a high WHR. The prevalence of diabetes increased with BMI among those 35 years or older, especially those with abdominal obesity. About half of men and two-thirds of women who were obese were trying to lose weight. CONCLUSION: Obesity remains common among Canadian adults. There is a need for broad-based programs that facilitate healthy eating and activity patterns for all age groups. Health professionals should incorporate measurement of BMI and WHR into their routine examinations of patients to enhance their evaluation of health risk.