Response Surface Methodology Analysis of Energy Harvesting System over Pathway Tiles.

This paper presents an experimental analysis of the optimization of PZT-based tiles for energy harvesting. The hardware (actual experiment), PZT-based tiles, were developed using 6 × 6 piezoelectric (PZT-lead zirconate titanate) sensors of 40 mm in diameter on a hard cardboard sheet (300 × 300 mm2). Our experimental analysis of the designed tiles obtained an optimized power of 3.626 mW (85 kg or 0.83 kN using 36 sensors) for one footstep and 0.9 mW for 30 footsteps at high tapping frequency. Theoretical analysis was conducted with software (Design-Expert) using the response surface methodology (RSM) for optimized PZT tiles, obtaining a power of 6784.155 mW at 150 kg or 1.47 kN weight using 34 sensors. This software helped to formulate the mathematical equation for the most suitable PZT tile model for power optimization. It used the quadratic model to provide adjusted and predicted R2 values of 0.9916 and 0.9650, respectively. The values were less than 0.2 apart, which indicates a high correlation between the actual and predicted values. The outcome of the various experiments can help with the selection of input factors for optimized power during pavement design.

Controlled release of antimicrobial Cephalexin drug from silica microparticles.

Release of antimicrobial drugs in a controlled fashion for extended duration of time has been investigated for long. Such controlled-drug-releasing materials show promising applications in medicinal bandages. Along with antimicrobial agents, one could also incorporate other therapeutic drugs, to make such bandages more versatile. In this context, silica micro particles were synthesized using direct reduction method, in which the synthesis was done in the presence of Cephalexin. Cephalexin was chosen as an antimicrobial candidate. The morphological characterization shows formation of monodispersed, silica microparticles of ~200nm in size. The FTIR spectroscopy shows weak interaction of the drug molecule at its hydroxide (OH) site with oxygen ions on the silica surface. Upon conjugation, the UV-vis spectroscopy shows persistence of the Cephalexin signature, especially its R group, confirming its antimicrobial activity even after conjugation. Loading studies reveal 12% Cephalexin loading on silica. The antimicrobial studies were done on three micro-organisms, namely, Staphylococcus aureus, Bacillus subtilis and Escherichia coli. Using zone-of-inhibition studies, it was found that E. coli, did not respond to the delivery of Cephalexin either directly or via microparticles. However, for both S. aureus and B. subtilis, the particles showed controlled release of Cephalexin for the duration of 48h and continued maintenance and even increase in the zone of inhibition. This work demonstrates an effective protocol to prepare antimicrobial patches for controlled drug delivery.

Sleep-disordered breathing and hypertension among African Americans.

This study investigated differences in sleep-disordered breathing (SDB) between hypertensives without a family history of hypertension and hypertensives with a family history. Furthermore, it examined whether these two groups differed in the severity of SDB. Patients were African Americans (n=162, mean age=51.19+/-13.77 years; mean body mass index (BMI)=37.85+/-9.51 kg/m2, male=57%), who were referred to the clinic because of a sleep complaint. Sleep was recorded in the laboratory using standard physiological parameters; all parameters were analysed by a trained scorer. Altogether, 91% of the patients received an SDB diagnosis. Of these patients, 25% were hypertensives without a family history, 20% were hypertensives with a family history, and 55% were normotensives. We found a significant difference between these patient groups regarding the severity of SDB (F14,158=1.823, P<0.05), but no significant group difference was observed in the rate of SDB. Increasing weight was accompanied by increasing severity of SDB. The finding that hypertensive patients with or without a positive family history showed worse oxygenation and respiratory characteristics than did normotensives is consistent with previous research. Of note, hypertensives reporting a family history were characterized by a greater number of oxygen desaturations and apnoea hypopnoea index than those typified only by a current diagnosis of hypertension. Hypertensives with a family history are likely to show a profile of greater blood pressure, higher BMI, and more severe SDB, which by all accounts are more common among African Americans.

Reduction in vancomycin-resistant Enterococcus and Clostridium difficile infections following change to tympanic thermometers.

OBJECTIVE: To contain a nosocomial outbreak of vancomycin-resistant Enterococcus (VRE). DESIGN: Intervention study, with comparison of incidence rates before and after intervention to assess whether changes in incidence followed the intervention and were greater than expected based on trends observed before the intervention. SETTING: A 343-bed acute-care hospital serving a predominantly elderly population referred from nursing homes, as well as patients admitted from the community. METHODS: Interventions strategies were tested on three high-risk nursing stations. These included enhanced environmental sanitation; intensive staff retraining in Universal Precautions, body substance isolation, and proper use of gloves; and the use of tympanic thermometers to avoid possible rectal or oral VRE transmission during temperature taking. RESULTS: Nosocomial VRE infections were reduced by 48% 9 months after switching to tympanic thermometers; incidence of Clostridium difficile infections also was reduced. As a result, tympanic thermometers were introduced facilitywide; additional observation for 20 months showed a risk reduction of 60% for VRE and 40% for C difficile. CONCLUSION: Cross-transmission of VRE and C difficile during temperature taking may result in bowel colonization, placing the patient at increased risk for infection. This risk may be reduced by the use of tympanic thermometers.

Genetics of epidermal ridges: a study in subjects with refractive errors.

The dermatoglyphic characteristics of subjects with refractive errors when compared with control group revealed significant differences in both qualitative and quantitative parameters. The loops were increased in male myopics; the whorls were increased in male hypermetropics and astigmatics and the arches were decreased in all types of refractive errors in males. However, the whorls were decreased in female hypermetropics only. The mean total ridge count was significantly higher in male astigmatics only. As regards pattern intensity (fingers) no significant difference in the mean value was observed in either sex with any type of refractive errors when compared with those of controls.

Serum zinc in corneal ulcer--a preliminary report.

In recent times zinc is emerging as a nutrient of clinical importance and had been found to be low in serum in various disease conditions. In the current study 11 control cases and 22 corneal ulcer cases were taken. Their serum zinc level was measured by atomic absorption spectrophotometer. Serum zinc level in recalcitrant corneal ulcer cases was found to be below normal.

Positive airway pressure in patients receiving intermittent mandatory ventilation at zero rate. The role in weaning in chronic obstructive pulmonary disease.

Over a 20-month period, we treated 180 mechanically ventilated patients in our respiratory intensive care unit. Among these patients, we observed an interesting previously unreported phenomenon in 20 patients with severe chronic obstructive disease. During the weaning from mechanical ventilators of these 20 patients, there was a marked clinical deterioration when the mode of ventilation was changed from intermittent mandatory ventilation (IMV) at zero rate to that of a T-tube setup. To explain this previously unreported observation, we studied and compared nine different intubated patients for possible differences in airway pressure between IMV set up at zero rate and a T tube. We observed that peak airway pressures were greater on IMV at zero rate compared to the peak airway pressures on the T piece in all nine patients. At the end of expiration, seven out of the nine patients had higher airway pressures on IMV at zero rate compared to the T tube. These differences in the peak airway pressures and end-expiratory pressures were statistically significant in both groups. In spite of the obvious limitation of extrapolating the experimental results obtained in one group of patients to explain the clinical observations made in another group of patients, we believe that the higher airway pressures on the IMV system (even without any mechanical ventilation) prevent early collapse of the airways, and this may be of significant importance in successfully weaning patients with COPD.