Elastic and thermo-elastic characterizations of thin resin films using colored picosecond acoustics and spectroscopic ellipsometry.

Colored Picosecond Acoustics (CPA) and Spectroscopic Ellipsometry (SE) are combined to measure elastic and thermoelastic properties of polymer thin-film resins deposited on 300 mm wafers. Film thickness and refractive index are measured using SE. Sound velocity and thickness are measured using CPA from the refractive index. Comparing the two thicknesses allows checking consistency between both approaches. The same combination is then applied at various temperatures from 19° to 180°C. As the sample is heated, both thickness and sound velocity change. By monitoring these contributions separately, the Temperature Coefficient on sound Velocity (TCV) and the Coefficient on Thermal Expansion are deduced. The protocol is applied to five industrial samples made of different thin-film resins currently used by microelectronic industry. Young's modulus varies from resin to resin by up to 20%. TCV is large on each resin and varies from one resin to another up to 57%.

Biaxial Piezoelectric MEMS Mirrors with Low Absorption Coating for 1550 nm Long-Range LIDAR.

This paper presents the fabrication and characterization of a biaxial MEMS (MicroElectroMechanical System) scanner based on PZT (Lead Zirconate Titanate) which incorporates a low-absorption dielectric multilayer coating, i.e., a Bragg reflector. These 2 mm square MEMS mirrors, developed on 8-inch silicon wafers using VLSI (Very Large Scale Integration) technology are intended for long-range (>100 m) LIDAR (LIght Detection And Ranging) applications using a 2 W (average power) pulsed laser at 1550 nm. For this laser power, the use of a standard metal reflector leads to damaging overheating. To solve this problem, we have developed and optimised a physical sputtering (PVD) Bragg reflector deposition process compatible with our sol-gel piezoelectric motor. Experimental absorption measurements, performed at 1550 nm and show up to 24 times lower incident power absorption than the best metallic reflective coating (Au). Furthermore, we validated that the characteristics of the PZT, as well as the performance of the Bragg mirrors in terms of optical scanning angles, were identical to those of the Au reflector. These results open up the possibility of increasing the laser power beyond 2W for LIDAR applications or other applications requiring high optical power. Finally, a packaged 2D scanner was integrated into a LIDAR system and three-dimensional point cloud images were obtained, demonstrating the scanning stability and operability of these 2D MEMS mirrors.

Revisiting the Fabry-Perot reflectivity method for mid-infrared optical index measurement: case study of InGaAs, AlInAs, and InP.

We revisit the Fabry-Perot (FP) reflectivity method to measure optical indices in the mid-infrared spectrum. This simple approach can be readily implemented using a standard Fourier transform infrared spectrometer. Measuring samples with multiple heights allows for enhanced precision of the measurement, making the FP method consistent in values and uncertainties with more advanced ellipsometric measurements. An extensive discussion about experimental errors is carried out. Results between 4 and 12 µm for AlInAs, n-doped InGaAs, and InP, which are the most standard materials for quantum cascade lasers, are given.

SU-E-T-231: Comparison of Beam Characteristics of Small Field 6 MeV Electrons as Replacement for Superficial X Ray Beam.

PURPOSE: To compare beam characteristics of superficial X-rays with 6 MeV Electrons for the purpose of replacing superficial treatments with electron fields for skin lesions. METHODS: Electron beam cutouts were made with 12mm thickness cerrobend in diameters 2-5 cm to match superficial X-ray machine cones. Central axis depth doses and profiles were generated using 0.007 cc Exradin A-16 ion chamber, in PTW water phantom at 1mm steps, at 96 and 100cm SSD for electron beams, and at 15cm SSD for superficial X-rays. From the beam data, radiation penumbra 90-10%, 90% profile width, peripheral dose and percentage depth dose were obtained for comparison. RESULTS: The 90-10% radiation penumbra was ranging 7.4-13.7 mm, 12.6-17.6 mm for 6 MeV electrons at 96 and 100cm SSD respectively, and 4.2-11.4 mm for 2-5 cm superficial X-ray cones. For 90% treatment width, a margin ranging 5-7 mm, 6-9 mm is needed around the periphery of target for 6 MeV Electrons at 96 and 100cm SSD respectively, and 2-3 mm for superficial X-ray cones. For 96cm SSD, the peripheral dose from the geometrical field edge were 3.9% at 1cm and 0.5% at 2cm. It was 2.6% at 1cm and 0.7% at 2cm for 100cm SSD. For superficial, it was 6.2%, 7.5%, 9.1% at 1cm, and 3.4%, 4.3%, 5.6% at 2cm for 100 kV, 120 kV and 150 kV respectively. The electron surface dose was below 90%. CONCLUSION: 6 MeV Electron beam shows high superiority with rapid fall off of dose beyond target with lower peripheral dose compared to superficial X-rays. However, the electrons need higher margin around the target and also need appropriate bolus thickness to increase skin dose. The dose at depth beyond 2cm makes very significant advantage using electrons compared to superficial X-rays.

Outbreak of sporotrichosis among tree nursery workers.

In spring 1994, an outbreak of sporotrichosis occurred at a tree nursery in Florida; 9 (14%) of 65 workers involved in production of sphagnum moss topiaries developed lymphocutaneous sporotrichosis. A cohort study of all 65 employees was conducted to identify risk factors for sporotrichosis, and an environmental investigation was done. The risk of sporotrichosis increased significantly with the duration of working with sphagnum moss (P < .05), in particular with filling topiaries (P < .05), and with having less gardening experience (P < .05). Wearing gloves was protective (P < .005). Sporothrix schenckii was cultured from patients and sphagnum moss used in topiary production. Use of restriction fragment length polymorphism revealed an identical pattern for patient isolates that was different from the patterns of environmental isolates. Physicians should be aware of sporotrichosis in patients with ulcerative skin lesions who have a history of occupational or recreational exposure to sphagnum moss.

Death due to asthma at workplace in a diphenylmethane diisocyanate-sensitized subject.

Total cases of fatal asthma in the occupational setting reported in the literature are reviewed and the case of a 39-year-old foundry worker who died at work is described. A diagnosis of occupational asthma induced by diphenylmethane diisocyanate (MDI) had been assessed 5 years in advance through a 0.005-ppm exposure inhalation challenge. Postmortem microscopic examination of the lung showed epithelial desquamation, eosinophilic/neutrophilic infiltration of the mucosa, dilatation of bronchial vessels, edema, hypertrophy and disarray of smooth muscle. Fatal asthma attack in a MDI-sensitized individual, to our knowledge, has not been previously described.

Molecular epidemiology of group B streptococcal infections: use of restriction endonuclease analysis of chromosomal DNA and DNA restriction fragment length polymorphisms of ribosomal RNA genes (ribotyping).

Epidemiologic investigation of group B streptococcal (GBS) infections has been limited by the lack of a discriminatory typing system. Therefore, the use of restriction endonuclease analysis of chromosomal DNA (REAC) and DNA restriction fragment length polymorphisms of rRNA genes (ribotyping) to subtype molecularly GBS isolates associated with human invasive disease was investigated. Chromosomal DNA of selected GBS isolates was initially digested with 24 different restriction enzymes. HhaI gave the best discrimination of hybridization banding patterns (ribotypes) and was used with all study isolates. Ribotyping and REAC differentiated among isolates of the same and different serotypes. Nine ribotype patterns were noted among the 76 isolates studied, including 4 among serotype Ia/c and 4 additional ribotypes among serotype III isolates. Epidemiologically related isolates (e.g., mother-infant or twin-twin pairs) had identical REAC and ribotype patterns. Epidemiologically unrelated isolates with the same ribotype usually had different REAC patterns, suggesting that REAC may be a more sensitive technique for strain differentiation. REAC and ribotyping were reproducible and proved to be successful molecular epidemiologic methods for subtyping GBS.

Use of plasmid analysis and determination of aminoglycoside-modifying enzymes to characterize isolates from an outbreak of methicillin-resistant Staphylococcus aureus.

We compared disk susceptibility, plasmid analysis, aminoglycoside resistance patterns, and DNA hybridization for their usefulness in characterizing isolates from a hospital outbreak of methicillin-resistant Staphylococcus aureus. Fifteen isolates were susceptible (group 1) and 28 were resistant (group 2) to gentamicin. A total of 15 of 15 (100%) group 1 and 22 of 28 (79%) group 2 isolates carried a 21.5-megadalton plasmid. All group 2 isolates and none of the group 1 isolates possessed a 33-megadalton plasmid. Aminoglycoside resistance pattern determinations revealed the presence of the ANT(4')-I enzyme (aminoglycoside 4' adenyltransferase) in all group 1 isolates but was unable to demonstrate presence of this enzyme in group 2 organisms. The APH(2") + AAC(6')-II enzyme (aminoglycoside 2" phosphotransferase plus 6' acetyltransferase) was found in all of the group 2 isolates but in none of the group 1 isolates. Use of DNA hybridization revealed the presence of the ANT(4')-I enzyme in both groups (group 1, 14 of 15; group 2, 26 of 28). In this hospital outbreak, we found good correlation between disk susceptibility, plasmid profile, aminoglycoside resistance patterns, and DNA hybridization results. It was difficult to predict the presence of the ANT(4')-I enzyme in the presence of the bifunctional [APH(2") + AAC(6')-II] enzyme by the aminoglycoside resistance pattern method because of overlap of the substrate profile.

Clinical efficacy and levels of ciprofloxacin in tissue in patients with soft tissue infection.

The clinical efficacy of ciprofloxacin was evaluated with 21 patients with soft tissue infection due mainly to gram-negative aerobic bacteria. Clinical cure was noted in 16 patients (76%), and clinical improvement was noted in the remaining 5 patients (24%). In addition, levels of ciprofloxacin were measured in the sera and tissues of 11 patients. Mean concentrations in tissue averaged 1.75 times the levels in serum. Ciprofloxacin should provide serum and soft tissue concentrations above the MICs for most gram-negative aerobic bacteria.

Encephalitis caused by Coxiella burnetii.

Acute infection with Coxiella burnetii usually results in a self-limited illness, but it can occasionally cause chronic endocarditis or hepatitis. Headache is a common presenting symptom of acute infection with this agent, but specific neurological abnormalities are rare. We report the case of a patient with acute Q fever that caused frank encephalitis. We also review the literature on central nervous system disease attributable to C. burnetii.