Depth-resolved water temperature measurements using Raman LiDAR.

We present the retrieval of depth-resolved temperature measurements in water using Raman LiDAR. Using a 5 m pipe of laboratory water, we recover non-homogeneous temperature profiles with a temperature accuracy ranging between 0.35°C and 0.85°C, and a position resolution of 28 cm.

Photochemical Etching of Carbonyl Groups from a Carbon Matrix: The (001) Diamond Surface.

The surface of diamond is reported to undergo nonablative photochemical etching when exposed to ultraviolet (UV) radiation which allows controlled single and partial layer removal of lattice layers. Oxygen termination of surface dangling bonds is known to be crucial for the etching process; however, the exact mechanism of carbon ejection remains unclear. We investigate the interaction of UV laser pulses with oxygen-terminated diamond surfaces using atomic-scale surface characterization combined with first-principles time-dependent density functional theory calculations. We present evidence for laser-induced desorption (LID) from carbonyl functional groups at the diamond {001} surface. The doubly bonded carbonyl group is photoexcited into a triply bonded CO-like state, including scission of the underlying C─C bonds. The carbon removal process in LID is atom by atom; therefore, this mechanism provides a novel "top-down" approach for creating nanostructures on the surface of diamond and other carbon-containing semiconductors.

Electronic structure of the organic semiconductor Alq3 (aluminum tris-8-hydroxyquinoline) from soft x-ray spectroscopies and density functional theory calculations.

The element-specific electronic structure of the organic semiconductor aluminum tris-8-hydroxyquinoline (Alq(3)) has been studied using a combination of resonant x-ray emission spectroscopy, x-ray photoelectron spectroscopy, x-ray absorption spectroscopy, and density functional theory (DFT) calculations. Resonant and nonresonant x-ray emission spectroscopy were used to measure directly the carbon, nitrogen and oxygen 2p partial densities of states in Alq(3), and good agreement was found with the results of DFT calculations. Furthermore, resonant x-ray emission at the carbon K-edge is shown to be able to measure the partial density of states associated with individual C sites. Finally, comparison of previous x-ray emission studies and the present data reveal the presence of clear photon-induced damage in the former.

Differential corneal sensitivity to ultraviolet light among inbred strains of mice. Correlation of ultraviolet B sensitivity with aldehyde dehydrogenase deficiency.

Adult male mice from four inbred albino strains (SJL/J, NZW/BL, BALB/c HeA, and SWR/J) were subjected to ultraviolet radiation (UVR) exposure (302 nm peak wavelength, intensity 398 microW/cm2) for 3.25 min and photographed 4 days postexposure to assess corneal clouding. Corneal extracts from control (unexposed) mice from each strain, were also monitored for aldehyde dehydrogenase (ALDH) and alcohol dehydrogenase (ADH) activity and soluble protein content. The SWR/J strain exhibited more extensive corneal clouding after UV exposure than did the other strains, and control SWR/J mice exhibited a low activity variant phenotype for the major ocular ALDH AHD-4, and decreased levels of soluble protein in corneal extracts. These data support earlier proposals for a major role for ALDH in assisting the cornea in protecting the eye against UVR-induced tissue damage.

Ultraviolet light-induced pathology in the eye: associated changes in ocular aldehyde dehydrogenase and alcohol dehydrogenase activities.

Adult male C57BL/6J inbred mice were subjected to ultraviolet radiation (UVR) exposure (302-nm peak wavelength; average intensity 282 microW/cm2) for 1 h and monitored for ocular aldehyde dehydrogenase (ALDH) and alcohol dehydrogenase (ADH) activity changes over a period of 25 days. Dramatic reductions in activities were observed by 4-6 days postexposure, resulting in enzyme levels of 15-16% of control animals. Major decreases in corneal enzyme levels were predominantly responsible for these changes. Ocular morphology was observed throughout using a photoslit-lamp biomicroscope, with maximum corneal clouding occurring at days 4-6. These data support earlier proposals for major roles for these corneal enzymes in assisting the cornea in protecting the eye against UVR-induced tissue damage.

Regional distribution of mammalian corneal aldehyde dehydrogenase and alcohol dehydrogenase.

The regional distribution of mouse aldehyde dehydrogenase (ALDH) and alcohol dehydrogenase activities in mouse ocular tissues was examined using spectrophotometric and agarose-isoelectric focusing techniques. The results established that these enzymes are predominantly localized in the cornea. Biochemical and histochemical analyses of the localization of these enzymes in the corneas of common domestic mammals (pigs, sheep, and cattle) and in baboons revealed species differences, with high levels being reported in corneal epithelium (pigs and baboons) and endothelium (sheep and cattle). The presence of these enzymes in the corneal epithelium is consistent with their proposed catalytic role in the detoxification of ultraviolet (UV)-induced peroxidic aldehydes, and with the proposed role for corneal ALDH in UVB absorption.

A genetic basis for corneal sensitivity to ultraviolet light among recombinant SWXJ inbred strains of mice.

PURPOSE: To examine a possible genetic basis for corneal sensitivity to UV-B light exposure. METHODS: To this end, adult male mice from the 14 SWXJ recombinant inbred albino strains (originating from SJL/J and SWR/J parental strains) were subjected to ultraviolet (UV) radiation exposure of 0.078 J/cm2 and photographed four days post-exposure, to assess corneal opacity and the possible correlation with corneal aldehyde dehydrogenase (ALDH) activity, alcohol dehydrogenase (ADH) activity and soluble protein content. RESULTS: Those recombinant strains that exhibited the SWR/J strain phenotype of having low levels of ALDH and decreased soluble protein levels also exhibited greater levels of corneal clouding after UV-exposure than the other strains, which exhibited "normal" levels of both ALDH activity and soluble protein in the cornea. CONCLUSIONS: These data support an hypothesis for a major role for ALDH in assisting the cornea to protect the eye against UV-induced tissue damage.

Purification and properties of murine corneal aldehyde dehydrogenase.

Murine corneal aldehyde dehydrogenase has been purified to homogeneity and characterized with a range of aldehyde substrates at pH 7.4. The enzyme was a dimer with a subunit molecular weight of 59 KDa. and appears to prefer aldehyde products of lipid peroxidation as substrates. The enzyme constituted approximately 5% of the total soluble protein of mouse cornea. A dual role has been proposed for corneal aldehyde dehydrogenase in providing the eye with protection against UV-B light: by oxidizing aldehydes generated through light-induced lipid peroxidation; and by the direct absorption of UV-B light by the enzyme.

When the diagnosis of deafness is wrong.

OBJECTIVE: To describe three children in whom there had been major errors in the diagnosis of hearing loss. CLINICAL FEATURES: In three children (two developmentally delayed, one not developmentally delayed) hearing thresholds obtained by behavioural testing were later proven wrong. This resulted in significant family distress and inappropriate educational approaches. INTERVENTION AND OUTCOME: Electrocochleography and brainstem audiometry were performed, demonstrating normal cochlear function. Simultaneous microinspection of the ears gave information about current or old middle ear disease and the likelihood of past conductive hearing loss. In each case hearing aids could be discarded, enabling parents and teachers to concentrate on one rather than multiple problems. CONCLUSION: Electrocochleography and brainstem audiometry should be used more frequently to check the diagnosis of hearing loss in children who are developmentally delayed, hyperactive or autistic and who do not give consistent responses to behavioural testing. It should also be considered if parents are firmly convinced that the diagnosis of deafness is wrong.