UV Windows Research Articles

High-performance peptide and disulfide mapping by direct injection of intact proteins using on-line coupled UV-liquid chromatography microdroplet mass spectrometry (UVLC-MMS)

Microdroplet mass spectrometry (MMS), achieving ultra-fast enzyme digestion in the ionization source, holds great promises for innovating protein analysis. Here, in-depth protein characterization is demonstrated by direct injection of intact protein mixtures via on-line coupling MMS with capillary C4 liquid chromatography (LC) containing UV windows (UVLC-MMS) through an enzyme introduction tee. We showed complete sets of peptides of individual proteins (hemoglobin, bovine serum albumin, and ribonuclease A) in a mixture could be obtained in one injection. Such full (100%) sequence coverage, however, could not be achieved by conventional nanoLC-MS method using bottom-up approach with single enzyme. Moreover, direct injection of a chaperone α-crystalline (α-Cry) complex yielded identification of post-translational modifications including novel sites and semi-quantitative characterization including 3:1 stoichiometry ratio of αA- and αB-Cry sub-units and ∼1.4 phosphorylation/subunit on S45 (novel site) and S122 (main site) of αA-Cry, ∼0.7 phosphorylation/subunit on S19 (main site) and S45 of αB-Cry, as well as 100% acetylation on both N-termini of each subunits by matching the mass and retention time of the intact and its digested peptides. Furthermore, trifluoroacetic acid was able to be used in the mobile phase with UVLC-MMS to improve the separation of differentially reduced intact species and detectability of the droplet-digested products. This allowed us to completely map four disulfide linkages of ribonuclease A based on collision-induced dissociation of disulfide clusters, some of which would otherwise not be detected, preventing scrambling or shuffling errors arising from lengthy bulk solution digestion by the bottom-up approach. Integration of UVLC and MMS greatly improves droplet digestion efficiency and MS detection, enabling highly efficient workflow for in-depth and accurate protein characterization.

NaCa5BO3(SiO4)2 with Interesting Isolated [BO3] and [SiO4] Units in Alkali- and Alkaline-Earth-Metal Borosilicates.

A new borosilicate, NaCa5BO3(SiO4)2, has been synthesized by a high-temperature solution method, which crystallizes in the centrosymmetric monoclinic space group P21/ c (No. 14), having a tangled three-dimensional (3D) network including isolated [BO3] triangles, isolated [SiO4] tetrahedra, and [CaO n] ( n = 7-9) and [NaO7] polyhedra. According to our surveys, it is the first compound containing both isolated [BO3] triangles and isolated [SiO4] tetrahedra in alkali- and alkaline-earth-metal borosilicates, which enriches the structure chemistry of borosilicates. The UV-vis-NIR diffuse reflectance spectrum shows that NaCa5BO3(SiO4)2 exhibits a wide transparent region which covers the near-IR, visible, and UV windows and displays a short UV cutoff edge at about 240 nm. Additionally, the thermal behavior (TG and DSC) and IR spectrum were also analyzed. For a deeper understanding of the relationships between the structure and properties, an analysis of theoretical calculations by density functional theory was also performed.

Void lattice formation in electron irradiated CaF2: Statistical analysis of experimental data and cellular automata simulations

Calcium fluoride (CaF2) is an important optical material widely used in both microlithography and deep UV windows. It is known that under certain conditions electron beam irradiation can create therein a superlattice consisting of vacancy clusters (called a void lattice). The goal of this paper is twofold. Firstly, to perform a quantitative analysis of experimental TEM images demonstrating void lattice formation, we developed two distinct image filters. As a result, we can easily calculate vacancy concentration, vacancy cluster distribution function as well as average distances between defect clusters. The results for two suggested filters are similar and demonstrate that experimental void cluster growth is accompanied by a slight increase of the void lattice constant. Secondly, we proposed a microscopic model that allows us to reproduce a macroscopic void ordering, in agreement with experimental data, and to resolve existing theoretical and experimental contradictions. Our computer simulations demonstrate that macroscopic void lattice self-organization can occur only in a narrow parameter range. Moreover, we studied the kinetics of a void lattice ordering, starting from an initial disordered stage, in a good agreement with the TEM experimental data.

Calcium Fluoride Crystals

AbstractThe performance of microchips continues to double about every 18 months. The incredible progress that is being made in lithography and many other areas of technology owes a lot to calcium fluoride crystals. Low solubility and wide transmission make calcium fluoride extremely useful for a variety of different applications, including microlithography, mirror substrates for UV laser systems, windows, lenses and prisms for UV and IR applications.

The influence of irradiation on the microhardness and photoluminescence of SiO2

The microhardness and photoluminescence spectra excited with 337-nm laser radiation in commercial SiO2 glasses (UV windows, substrates with BaTiO3 film coatings) exposed to 60Co gamma radiation and a mixed neutron flux from the reactor are investigated. It is revealed that initial samples contain nanocrystalline phases. An increase in the microhardness and the intensity of the excitonic UV luminescence due to 60Co gamma irradiation and the quenching of the photoluminescence associated with the nonbridging oxygen centers result from healing of Si-O dangling bonds and microcracks in the surface layer at the nanocrystal-glass matrix and substrate-coating interfaces. It is demonstrated that reactor irradiation leads to the phase transformation of SiO2 cristobalite into tridymite and BaO into BO2, as well as to the decomposition of BaTiO3 and BaCO3. This brings about a decrease in the microhardness and photoluminescence quenching.

Time-resolved luminescence from feldspars: New insight into fading

Time-resolved infrared optically stimulated luminescence (IR-OSL) signals of K- and Na-feldspar samples extracted from sediments were measured in UV, blue and red detection windows, using a fast photon counter and pulsed IR stimulation ( λ = 875 nm ) . We observe that the relative contribution of long lifetime ( ∼ 20 μ s ) components in K-feldspars is greater than that in Na-feldspars at each detection wavelength. From any one feldspar sample, red and blue IR-OSL signals have a greater contribution of long lifetime components than UV IR-OSL. We found this long lifetime component was significantly more stable than shorter lifetime components, by comparing natural/regenerated and prompt/delayed time-resolved IR-OSL. We also compared both pulsed and continuous wave (CW) equivalent dose ( D e ) values from four feldspar samples. For pulsed IR-OSL, the signal was collected between 10 and 100 μ s after the diodes were switched off, to avoid all contributions from short lifetime components. In all cases, the pulsed D e values were larger than the CW D e values, regardless of the type of the feldspar and the detection wavelength; the pulsed D e values were also all consistent with those calculated from the quartz D e . It is possible that the long lifetime component from feldspars do not show anomalous fading.

Development of cooled UV, visible and IR windows for quasicontinuous operation of the W7-X stellarator

The stellarator W7-X will be capable of running 30 min discharges. The expected continuous radiation power loads on plasma-facing optical components of 50 kW/m2 will be predominantly deposited in the form of short wavelength radiation (<60 nm) within the first millimeter of any window material. At such high heat loads actively water cooled windows are essential. The finite element-code ANSYS was used to calculate temperature and stress distributions across the windows for different window materials (CaF2, MgF2, quartz, ZnSe, sapphire), diameters, and thicknesses to explore any window design limitations resulting from the material properties of the different window substrates. First tests of a prototype water cooled window (coated with water-based colloidal graphite for effective IR absorption) in a specially designed vacuum test chamber equipped with a large surface vacuum compatible high power IR heater are being reported on. The temporal evolution of the temperature at different locations on the air side of the window and its surrounding structure is being monitored by several PT100 resistive thermometers while the spatial heat distribution across the cooled windows on their air and vacuum side is being measured with two IR cameras operating at 4 and 10 μm.

Some Results of the Coordinated Observations of the Red Dwarf Flare Star EV Lac in 1986-1994

In 1986-94 a series of coordinated monitorings for the flare star EV Lac has been performed. The observations were aimed to collect homogeneous data on the star both in its active and quiet states, to study its flares and starspots. These photometric patrols were accompanied by monitorings of EV Lac of different other kinds: polarimetric, spectral, radio, UV and high energy studies. In total, these monitorings covered a range from decametre radio wavelengths through IR, optical and UV windows up to very high energy γ-rays. The list of participants of these studies is very large. Up to date the results of 1986, 1987, 1990 and 1991 are published (Gershberg et al. 1991a,b, 1993, Alekseev et al. 1994), the data of 1989 are submitted (Berdyugin et al. 1995), the data of 1992 (Abdul-Aziz et al. 1995) will be submitted in the near future. In 1993, photometric observations were accompanied by monitoring observations of EUVE and IUE, in 1994, VHE γ-ray observations were included. The publication of data collected in 1993 and 1994 is in preparation. In this communication I shall concentrate on several new findings related to the EV Lac flares only.

Ultraviolet windows in commercial sunglasses

The optical transmission of a random selection of nonprescription sunglasses was measured from 0.3-microm to 0.85-microm wavelength. Several models were found with uv windows that may increase the probability of cataract formation on the eye lens. More than half of the twenty-five models tested had ir windows that may cause eye discomfort with prolonged usage. In the tested glasses, there appears to be no correlation between lens color or cost and the amount of shielding given to the eyes from the radiation not contributing to the visual response.