Conoscopic interferometry of surface-acoustic-wave substrate crystals.

Conoscopic interferometry is applied for determining the crystal orientation of lithium niobate and other commonly employed substrate wafers for integrated-optic and surface-acoustic-wave devices. The method is particularly applicable for detecting the orientation of the optic axes of the strongly birefringent niobate but is less sensitive for lithium tantalate or quartz. Conoscopic interference is a low-cost and easy-to-use method that is especially suitable for laboratory usage.

Binary-phase zone-plate arrays based on hybrid solgel glass.

An organically modified silane zirconate-based solgel material is used for the fabrication of binary-phase zone-plate arrays. The synthesized hybrid solgel material has a negative tone under UV exposure and can be patterned by a UV-lithography process. The transmittance of the material is nearly 100%, and the refractive index is 1.52. Two different diffractive lens arrays with focal lengths of 5 and 42 cm have been fabricated. The average roughness of the zone surface is less than 20 nm. The diffraction efficiencies of the lens arrays are measured as a function of modulation depth and exposure dose. A diffraction efficiency of 30% is achieved.

Birefringence control for ion-exchanged channel glass waveguides.

We show that at 1.55-mum wavelength the waveguide birefringence of ion-exchanged channel waveguides in glass can be broadly tuned by a potassium and silver double-ion exchange. Two different potassium and silver double-ion-exchange processes are used to make surface waveguides with negligible waveguide birefringence. This process is crucially important in the manufacture of devices for dense wavelength-division multiplexing systems. The dependence of the waveguide birefringence on the channel width is also reported.

Effects of cis- and trans-urocanic acids on the secretion of interleukin-1 beta and tumour necrosis factor-alpha by human peripheral blood monocytes.

In order to investigate the mechanism of urocanic acid (UCA)-mediated immune modulation, we studied the effect of cis- and trans-UCA on interleukin-1 beta and tumour necrosis factor-alpha production by human peripheral blood monocytes, using immunospecific ELISA techniques. Trans-UCA augmented the interleukin-1 beta production and inhibited tumour necrosis factor-alpha production in a dose-dependent manner, whereas cis-UCA had no effect on the secretion of these cytokines by phorbol myristate acetate or lipopolysaccharide-stimulated monocytes. This is a novel example of trans-UCA mediating a biological effect, a finding earlier reported for cyclic adenosine monophosphate up-regulation in human fibroblasts by Palaszynski and coworkers and for human natural killer cell inhibition by ourselves. Our data suggest an important role for trans-UCA as an immunomodulator in the skin.

Effect of psoriasis heliotherapy on epidermal urocanic acid isomer concentrations.

A noninvasive Finn Chamber sampling method and HPLC analysis were used to determine epidermal urocanic acid (UCA) concentrations of psoriasis patients during 4 weeks of heliotherapy on the Spanish Canary Islands and a follow-up period of 8 weeks. During heliotherapy the epidermal cis-UCA concentration increased from a mean initial value of 0.2 nmol/cm2 to a mean final value of 2.9 nmol/cm2. The total UCA concentration decreased during the first week of heliotherapy from an initial value of 5.5 nmol/cm2 to a nadir of 2.0 nmol/cm2. Thereafter, a steady increase was recorded in the total UCA level, with a maximum of 10.2 nmol/cm2 in week 2 of the post-treatment follow-up period. Suberythemal sun exposures caused near-maximal UCA isomerization, and during heliotherapy the cis isomer constituted 63.7-74.3% of the total UCA concentration. Clinical response of psoriasis to heliotherapy, however, seemed to be independent of UCA isomer levels.

A non-invasive chamber sampling technique for HPLC analysis of human epidermal urocanic acid isomers.

A new, non-invasive chamber sampling technique for HPLC analysis of human epidermal urocanic acid isomers is described. Easily processed samples are obtained in a rapid and non-invasive manner, without discomfort to the patient. HPLC data from chamber samples are reproducible, and recorded urocanic acid isomer levels are comparable to those measured in samples taken with tape stripping technique.

NMR spectroscopy of naturally occurring phloroglucinol derivatives.

Carbon-13 NMR spectra of eight 2-acyl- and -6-methyl-substituted filicinic acid (4,4-dimethyl-1,3,5-cyclohexantrione) derivatives were recorded in hexadeuterioacetone and in deuteriochloroform and the signals assigned on basis of chemical shifts and J (CH) coupling considerations. The data prove that the prevailing tautomeric structure of these derivatives is the monoketonic one with the carbonyl function in position 3 and hydroxyl groups in positions 1 and 5, the former being hydrogen bonded to the acyl side chain carbonyl. The 2-acyl-6,6-dimethyl compounds have the diketonic structure and a hydrogen-bonded hydroxyl group in position 3. The skeletal structure of 2-butyryl-4-hydroxy-4,6-dimethyl-1,3,5-cyclohexantrione is identical with that of humulone. This compound and its homologues also exist in the monoketonic tautomeric form, where C-3 carries the carbonyl function. In the solvents used the 6-methyl-2,3-dihydropyrane-2,4-dione exists predominantly as a single tautomer having two ring double bonds; the remaining carbonyl group is a part of an alpha, beta-unsaturated lactone grouping.