Parallel spectroscopic ellipsometry for ultra-fast thin film characterization.

Spectroscopic ellipsometer (SE) is an essential optical metrology tool commonly used to characterize thin films and monitor fabrication processes. However, it relies on mechanical rotation of a polarizer or a photo-elastic phase modulator which are limited in speed and prone to errors when handling dynamic processes. The constant trend of micro-electronics dimensions shrinkage and increase of the wafer area necessitates faster and more accurate tools. A fast SE design based on parallel snapshot detection of three signals at different polarizations is proposed and demonstrated. Not relying on mechanical rotation nor serial phase modulation, it is more accurate and can reach acquisition rates of hundreds of measurements per second.

In vivo study on biotransformation of pentacyclic analogs of progesterone: Identification of their metabolites by HPLC-MS method.

Progesterone derivatives containing the D' additional cyclohexane ring in the 16α,17α-positions of steroid core (pregna-D'-pentaranes) exhibited high in vitro and in vivo selective progestogenic activity. The assessment of their biotransformation in the body, and the identification of possible metabolites are integral parts of a potential drug studies. Here we describe the results of in vivo metabolic transformation of 6α-methyl-16α,17α-cyclohexanopregn-4-ene-3,20-dione 1 and its 6-demethylated analog 2 and identification of their metabolites in rat urine. We synthesized and fully characterized (1D and 2D NMR, HRMS) 11 possible metabolites as the standards. Then we developed the LC-MS/MS assay including sample preparation and chromatography conditions for identification of the detected metabolites of 1 and 2. The 5α- and 5ß-3,20-diketo-, 3ß-hydroxy-20-keto-5α-, 3-keto-20(S)-hydroxy-5α-, 3ß,20(S)-dihydroxy-5α-metabolites of compounds 1 and 2 were found in rat urine samples. The starting steroids 1 and 2, as well as both 3ß,20(R)-dihydroxy metabolites were not detected in the examined biological urine samples. Thus, we demonstrate for the first time that exogenous progestines - pregna-D'-pentaranes - and endogenous progesterone follow similar metabolic pathways. Therefore, despite the presence of an additional ring D' and the methyl group in position 6, the main enzymatic transformations are similar to those of the natural hormone.

Assessment of intraocular pressure sensing using an implanted reflective flexible membrane.

Glaucoma is a neurodegenerative condition that is the leading cause of irreversible blindness worldwide. Elevated intraocular pressure (IOP) is the main cause for the development of the disease. The symptoms of this form, such as deterioration of vision and scotomas (loss of visual fields), appear in the latter stages of the disease. Therefore, an IOP monitoring device is needed for better, simpler, and faster diagnosis, and to enable a fast treatment response. We present a theoretical assessment as well as preliminary experimental results of a simple approach for easy, optical, IOP self-monitoring. It is based on a polydimethylsiloxane membrane coated with a reflective layer and a Hartmann­Shack wavefront sensor. Nearly linear correlation is found between membrane deformation and Zernike coefficients representing defocus primary spherical aberration, with high sensitivity and negligible dependence on the measurement distance. The proposed device is expected to provide an accurate IOP measurement resolution of less than ± 0.2 ?? mm ? Hg with a pressure dependence on working distances < 0.7 ?? mm ? Hg / cm for a thick membrane; the corresponding values for a thin membrane are ± 0.45 ?? mm ? Hg and < 0.6 ?? mm ? Hg / cm , respectively, at typical IOP values­up to 40 mm Hg.

Non-specialist ultrasound measuring of access flow: new technology.

A new ultrasound instrument has been developed, using vector Doppler and embedded machine intelligence, to enable measurement of access flow rates by non-specialists. Ultrasound measurement of access flow can be performed with the patient off the dialysis machine, avoiding the hemodynamic changes that may affect indicator-dilution methods. A research version of the instrument was tested on flow phantoms simulating graft flow, and showed accuracy better than 5%. A non-specialist measured flow in the access grafts of 7 consenting dialysis patients; the instrument showed flows commensurate with indicator-dilution-measured flows, but with less variability. Measurements were made in less than 5 min per patient. The cost per measurement is calculated to be significantly less than that of present methods of measuring flow. The new instrument may become a useful tool for monitoring flow in accesses to extend their life.