A Tactile Sensor for Biomedical Applications Based on IPMCs

In this paper, a first prototype of a multifunctional tactile sensor using ionic polymer metal composites (IPMCs) is proposed, designed, and tested. Two IPMC strips are used, one as an actuator and one as a sensor, both positioned in a cantilever configuration; working together they enable the system to detect the presence of a material in contact with it and to measure its stiffness. These sensing capabilities can be exploited in various biomedical applications, such as catheterism, laparoscopy and the surgical resection of tumors. Moreover, the simple structure of the proposed tactile sensor can easily be extended to devices in which a sensing tip for exploration of the surrounding environment is required. Compared with other similar tools, the one proposed works with a very low-power supply (the order of magnitude being a few volts), it needs very simple electronics, it is very lightweight and has a low cost.     

Colchicine in chronic hepatitis B: a pilot study

INTRODUCTION: The authors report the case of an internal rotation of the lower limb, lately ascribed to a posterior placement of the acetabular component during total hip arthroplasty. MATERIAL AND METHOD: A 58 years old female had an irreducible internal rotation of the right hip 3 years after total hip arthroplasty for arthritis. When the hip was extended, the lower limb showed an irreducible internal rotation of 45 degrees. In flexion of the hip this rotation disappeared. AP radiograms showed femur and femoral stem in internal rotation, a healed fracture of the acetabulum, and the acetabular component seemed to be in correct position. On CT scan the acetabular component was 4 cm posterior to the anatomic location, although there was no abnormal anteversion of the stem and acetabular component. Revision, with relocation of the acetabular component, corrected lower limb rotation. DISCUSSION: Posterior position of the acetabular component has not been described as a cause of lower limb malrotation. Normally the strength of the external hip rotators muscles is three times as important as of the internal rotators. The transverse acetabular fracture led to backwards placement of the acetabular component and yelded in an automatic internal rotation of the femur, because the trochanter kept an anatomical position in the horizontal plane. The posteriorised rotation center of the hip had changed the balance of the different rotator muscles, some of them, originally external rotators, becoming internal rotators.     

Nutrient transfers by leaching in a no-tillage system through soil treated with repeated pig slurry applications

Repeated pig slurry applications cause accumulation and leaching of soil nutrients and, subsequently, groundwater contamination. The purpose of this study was to evaluate ammonium (NH₄ ⁺–N), nitrate (NO₃ ^?–N), phosphorus (P) and potassium (K) leaching in a sandy soil with a 5-year history of repeated pig slurry applications. The study was carried out in the experimental field of the Universidade Federal de Santa Maria (UFSM) (Federal University of Santa Maria), Santa Maria, Rio Grande do Sul, in the South of Brazil, from 2002 to 2007, in no-tillage system in a Typic Hapludalf soil. Slurry was applied at doses of 0, 20, 40 and 80 m³ ha^?1, which over the 5 years amounted to the addition of 594, 1,188 and 2,376 kg N ha^?1; 508, 1,016 and 2,032 kg P ha^?1 and 216, 432 and 864 kg K ha^?1, respectively. Leachate solutions were collected throughout the period, prepared and then subjected to analysis of NH₄ ⁺–N, NO₃ ^?–N, P and K available in the solution. Repeated applications of pig slurry in a no-tillage system in sandy soil led to the transfer of elements through the leachate solution according to the sequence: nitrate > potassium > ammonium > phosphorus. The transfers of these elements were positively related to the increased volume of leachate solution over the years in addition to the nutrient amounts added by the pig slurry applied over the 60-month period.     

Dipyridamole stress echocardiography for risk stratification in hypertensive patients with chest pain

BACKGROUND: The noninvasive prognostic assessment of coronary artery disease (CAD) in hypertensive patients represents an unresolved task to date. In this study, we investigated the value of dipyridamole stress echocardiography in risk stratification of hypertensive patients with chest pain and unknown CAD. METHODS AND RESULTS: Dipyridamole stress echocardiography was performed in 257 hypertensives (110 men; age, 63+/-9 years) complaining of chest pain and without a history of CAD. No major complications occurred. Four tests were interrupted prematurely because of side effects, with 98. 4% feasibility of test. A positive echocardiographic response was found in 72 patients (27 during the low-dose [0.56 mg/kg]). During the follow-up (32+/-18 months), 27 cardiac events occurred: 3 deaths, 8 infarctions, and 16 cases of unstable angina. Moreover, 27 patients underwent coronary revascularization. At multivariate analysis, the positive echocardiographic result (OR, 5.5; 95% CI, 1.4 to 16.6) was the only predictor of hard cardiac events (death, infarction). Considering spontaneous cardiac events (death, infarction, and unstable angina) as end points, the positive echocardiographic result (OR, 4.2; 95% CI, 1.8 to 9.6) and family history of CAD (OR, 4.2; 95% CI, 1.5 to 6. 9) were independently associated with prognosis. The 3-year survival rates for the negative and the positive populations were, respectively, 97% and 87% (P=0.0019) considering hard cardiac events and 96% and 74% (P=0.0000) considering spontaneous cardiac events. CONCLUSIONS: Dipyridamole stress echocardiography is safe, highly feasible, and effective in risk stratification of hypertensives with chest pain and unknown CAD. At present, it represents an attractive option for prognostic assessment of this clinically defined population.     

PEM fuel cell testing by electrochemical impedance spectroscopy

Nowadays, proton exchange membrane fuel cells (PEMFC) are candidate as middle term power sources for automotive, stationary generation and portable power applications. In order to introduce these devices into the market an improvement in their performances seems necessary, as well as the development of an effective control system able to find their optimal operating conditions. This paper deals with electrochemical impedance spectroscopy (EIS) using an effective tool, where a cost-effective measurement hardware has been developed creating a software to analyze the results. Both single fuel cells and stacks have been tested in various operating conditions. This experimental approach allows to highlight variations of model parameters and to perform a further analysis of the processes occurring in a fuel cell through electrical circuit models. A special attention is given to the experimental results, in order to address fuel cell malfunctions using the EIS approach as an effective diagnostic method.