Study of Physically Transient Insulating Materials as a Potential Platform for Transient Electronics and Bioelectronics

Controlled degradation and transiency of materials is of significant importance in the design and fabrication of degradable and transient biomedical and electronic devices and platforms. Here, the synthesis of programmable biodegradable and transient insulating polymer films is reported, which have sufficient physical and chemical properties to be used as substrates for the construction of transient electronics. The composite structure can be used as a means to control the dissolution and transiency rate of the polymer composite film. Experimental and computational studies demonstrate that the addition of gelatin or sucrose to a PVA polymer matrix can be used as a means to program and either slow or enhance the transiency of the composite. The dissolution of the polymer composites are fitted with inverse exponential functions of different time constants; the lower time constants are an indication of faster transiency of the polymer composite. The addition of gelatin results in larger time constants, whereas the addition of sucrose generally results in smaller time constants.     

Antibacterial activity of ofloxacin in urine for 4 days after a single oral dose of 400 mg

Antibacterial activity of ofloxacin in urine after a single oral dose of 400 mg was evaluated in ten healthy female volunteers. Urine was collected over six periods, i.e., 0-6 h, 6-12 h, 12-24 h, 24-48 h, 48-72 h, and 72-96 h postdose. Ofloxacin levels were assayed in all samples using a microbiological method and HPLC. Urinary ofloxacin MICs were determined for five bacterial strains recovered from urine, two E. coli strains of which one was susceptible and the other resistant to nalidixic acid (Nal-A), one Klebsiella pneumoniae resistant to nalidixic acid (Nal-B), one Staphylococcus saprophyticus strain, and one Enterococcus faecalis strain; MICs were 0.06, 0.25, 1, 0.25, and 2 mg/L, respectively. Mean urinary ofloxacin levels by the microbiological method during the six collection periods were 193.3 +/- 30.3, 138.1 +/- 31, 53.2 +/- 7.3, 8.3 +/- 0.8, 1.4 +/- 0.2, and 0.6 +/- 0.1 mg/L, respectively. HPLC provided similar results: 216.7 +/- 31.6, 130.7 +/- 20.5, 56.5 +/- 7.1, 8.3 +/- 0.9, 1.5 +/- 0.3, and 0.5 +/- 0.05 mg/L, respectively. Mean urinary ofloxacin excretion over 96 h was 67.4 +/- 3.6% of the dose by the microbiological method was 72.5 +/- 2.5% of the dose by HPLC. On the first day, bacteriostatic activity of urine against enterobacteria exceeded 32 and was greater than 8192 for the nalidixic acid-susceptible E. coli strain; on the next day, overall values were equal or greater than 8 for the nalidixic acid-resistant E. coli and K. pneumoniae strains. Bacteriostatic activity was equal to or greater than 32 for the S. saprophyticus strain during the first two days and equal to 8 on the first day and 4 on the second day for the E. faecalis strain.     

Fumaric acid in apple juice: a potential indicator of microbial spoilage of apples used as raw material.

The effects of heat treatment (evaporation and excessive heating), and microbial contamination (Rhizopus stolonifer, Penicillium expansum and Lactobacillus plantarum) as sources of fumaric acid formation in apple juice concentrates were investigated. Fumaric acid formed in apple juice did not exceed 1.0 mg l(-1) during both commercial-scale evaporation and laboratory-scale excessive heat treatment, indicating that malic dehydration is not the primary source of fumaric acid formation. However, R. stolonifer and L. plantarum produced 18.23 +/- 0.82 and 5.39 +/- 0.31 mg l(-1) fumaric acid as determined in the raw juice obtained from contaminated apples after 5 days of incubation. The mean fumaric acid content of apple juice concentrates manufactured in 2000, 2001 and 2002 were determined as 4.9 +/- 1.9, 5.7 +/- 2.8 and 4.1 +/- 2.6 mg l(-1), respectively. The overall results suggest that the primary source of fumaric acid in apple juice concentrate is the use of apples decayed by certain microorganisms capable of producing fumaric acid.     

On the realization of OTA-C filters

A synthesis procedure based on the signal flow graph is given for generating second-order active filters using a minimum number of operational transconductance amplifiers and grounded capacitors. the pole quality factor and pole frequency sensitivities are studied for the proposed filters. Furthermore, the limitations on input signal amplitude are studied and a simple formula is derived for the input signal amplitude not causing clipping and slew-rate-limiting problems.     

Measurement of the vascular mass of the human radial artery by ultrasonics

OBJECTIVE: To determine the reproducibility of radial artery mass (RAM), in hypertensive patients. DESIGN AND METHODS: In 49 patients, RAM was measured using a high resolution echotracking device (Nius-02) which allows noninvasive measurement of diameter and wall thickness of the radial artery. RAM was validated in vitro by comparing weight of arterial segments to ultrasonographic measurement and determined as RAM = r (pi Re2-pi Ri2) where r is the arterial wall density (1.06 g/cm3), and Re and Ri are values of internal and external radii, respectively. Repeatability coefficient (RC2 = SDi2/n) was 1.3 mg. RESULTS: Blood pressure was (mean +/- SD) 146 +/- 19/85 +/- 15 mmHg, radial arterial diameter was 2,449 +/- 376 microns, radial wall thickness was 302 +/- 68 microns, RAM was 28 +/- 9 mg (range 13-43 mg). CONCLUSION: These results indicate that radial artery mass can be measured using a high resolution echotracking device.     

Combined surgery of the mitral valve and the abdominal aorta in a case of Takayasu's disease

The authors report the case of a 34-year-old woman, of North African origin, with mitral valve disease and abdominal aortitis. The differential diagnosis between Takayasu' disease, embolism of cardiac origin and rheumatic aortitis is discussed. Treatment of these lesions was by combined cardiac and vascular surgery in a single-stage operation.     

Highly surfaced polypyrrole nano-networks and nano-fibers

Polypyrrole (PPy) nano-networks and nano-fibers were synthesized using interfacial and template polymerization techniques, respectively. The morphology of the PPy nano-networks showed that a homogeneous, three-dimensionally grown nano-fibers were produced. Dodecyl sulfonate was used as surfactant in the interfacial polymerization. Bulk conductivity of PPy nano-networks were in a range of 10⁻¹–10⁻⁴ S/cm with a surface area of ca. 480 m²/g. Template synthesis produced one-directional alignment of conducting nano-arrays for the purpose of possible applications of these materials in charge storage devices (i.e., supercapacitors) as electrode materials. Electrochemical and spectroelectrochemical investigations showed that these materials are promising for device applications.