Polished Quartz Plate Research Articles

Drying Drop Technology as a Possible Tool for Detection Leukemia and Tuberculosis in Cattle

Usual response of organism to viral or bacterial invasion represents antibodies production, qualitative and quantitative changes in composition of biological fluids. These changes influence conformation and surface characteristics of macromolecules (proteins), which become apparent in sessile drying drops, when they form aggregates due to salting-out effect and sediment. The bottom adsorption layers change their adhesive and viscoelastic properties in time depending on fluid composition and structure. The aim of this study was verification the idea of using this phenomenon in rapid vet diagnostics. Milk, blood and serum samples of 183 cows were tested using Drop Drying Technology (DDT). A drop of tested fluid dried on a polished quartz plate, oscillated with constant frequency—60 kHz. Mechanical properties of the drop changed during drying, influenced the electrical conductivity of the quartz plate. This signal was converted to the Acoustical- Mechanical Impedance (AMI) and displayed as a curve in coordinates AMI vs. Time. Shape of the AMI curve reflected this dynamics, and was used as a target for quantitative comparison between control and infected animals. Frequency analysis of the estimated parameters of the curves was performed using features of the Excel program. Powerful method of artificial neural network processing of the experimental data was also tested in this work as a possible tool for future development. Significant differences between control, Bovine leucosis virus positive (BLV+) and Bovine tuberculin positive (BTub+) cattle groups were obtained using all biological fluids—blood, serum and milk. We fixed also a season shift of the data, but distinction between groups still remained. In serum and milk some features of the AMI curves were more stable, and retained diagnostic properties when combined winter and spring databases. Further development of DDT is proposed.

Diamond Films for Implantable Electrodes

Diamond is a promising material for implantable electrodes due to its unique properties. The aim of this work is to investigate the growth of boron-doped nanocrystalline diamond (B-NCD) films by plasma-enhanced microwave chemical vapor deposition at various temperatures, and to propose optimal diamond growth conditions for implantable electrodes. We have investigated the temperature dependence (450 °C–820 °C) of boron incorporation, surface morphology and growth rate on a polished quartz plate. Surface morphology and thickness were examined by atomic force microscopy (AFM).The quality of the films in terms of diamond and non-diamond phase of carbon was investigated by Raman spectroscopy. AFM imaging showed that the size of the grains was determined mainly by the thickness of the films, and varied from an average size of 40 nm in the lowest temperature sample to an average size of 150 nm in the sample prepared at the highest temperature. The surface roughness of the measured samples varied between 10 (495 °C) and 25 nm (800 °C). The growth rate of the sample increased with temperature. We found that the level of boron doping was strongly dependent on temperature during deposition. An optimal B-NCD sample was prepared at 595 °C.

Changes in Optical Absorptions in Natural Quartz Irradiated by γ-Rays and Its Isochronal Annealing

The clear natural Brazilian quartz used in this experiment had a weak optical absorption at the A1-band (1.85–2.0 eV) before γ-ray irradiation. By irradiating the sample, a strong A2-band absorption (2.65–2.75 eV) was produced, while the A1-band absorption increased only very slightly, although both the A1- and A2-bands are related to an aluminum impurity. The thermal activation process of the A2-band absorption was investigated by isochronal annealing to evaluate the activation energy. When possible losses were taken into consideration, an activation energy E=0.32 eV was obtained, where the losses are light transmission losses originating from multiple scattering, absorption by surface damage, and scattering in random directions by the surface roughness of a specularly polished quartz plate. When an ideal state was assumed, in which the transmission losses did not exist, an activation energy E=0.28 eV was obtained. From these results, the activation energy for this color center is evaluated to be 0.3±0.2 eV.

Double-Plate Sample Carrier for a Simple Total Reflection X-Ray Fluorescence Analyser

A simple total reflection x-ray fluorescence (TXRF) analyser was constructed using an original double-plate sample carrier. The carrier consists of two glass microscope slides, one 25 mm longer than the other, which function simultaneously as both the collimator and the sample holder. Total reflection conditions are achieved in the space between the two plates, completely eliminating the need for precise sample positioning. Because the instrument consists of simple mechanical parts, it can be made in most laboratories using traditional XRF components (x-ray generator and energy-dispersive x-ray spectrometer) which are readily available. Despite the simplicity of the design, the instrument has essentially all of the capabilities of conventional TXRF machines: multi-element analysis (Cl to U), low limits of detection (pg) and a requirement for only very small volumes (μl) of sample. The detection limits which can be achieved using 50 μl samples depend on the quality of the plate surface. For example, using glass microscope slides for plates, the absolute detection limit for first series transition metals (Sc to Zn), Pb and Sr are of the order of 200 pg; this is adequate for a wide range of geological and environmental samples. The detection limits could be further improved by either (1) placing the sample carrier and detector head in a vacuum chamber, (2) by using monoenergetic excitation, because of the high efficiency of the double-plate collimator, or (3) by using highly polished quartz plates instead of glass for the sample carrier.

DoublePlate Sample Carrier for a Simple Total Reflection XRay Fluorescence Analyser

A simple total reflection x-ray fluorescence (TXRF) analyser was constructed using an original double-plate sample carrier. The carrier consists of two glass microscope slides, one 25 mm longer than the other, which function simultaneously as both the collimator and the sample holder. Total reflection conditions are achieved in the space between the two plates, completely eliminating the need for precise sample positioning. Because the instrument consists of simple mechanical parts, it can be made in most laboratories using traditional XRF components (x-ray generator and energy-dispersive x-ray spectrometer) which are readily available. Despite the simplicity of the design, the instrument has essentially all of the capabilities of conventional TXRF machines: multi-element analysis (Cl to U), low limits of detection (pg) and a requirement for only very small volumes (μl) of sample. The detection limits which can be achieved using 50 μl samples depend on the quality of the plate surface. For example, using glass microscope slides for plates, the absolute detection limit for first series transition metals (Sc to Zn), Pb and Sr are of the order of 200 pg; this is adequate for a wide range of geological and environmental samples. The detection limits could be further improved by either (1) placing the sample carrier and detector head in a vacuum chamber, (2) by using monoenergetic excitation, because of the high efficiency of the double-plate collimator, or (3) by using highly polished quartz plates instead of glass for the sample carrier.

Vapor Phase Reactions of Organoaminosilanes with Quartz

A technique for modifying the natural water-wetting behavior of polished quartz plates is discussed. The method involves chemical bonding of an organoaminosilane in the vapor phase to hydroxyl groups at the quartz surface. The dynamic Wilhelmy plate apparatus provided rapid and convenient evaluation of the silylation reactions. Three different silylation temperatures were investigated for both monofunctional hexamethyldisilazane (HMDS) and bifunctional bis(dimethylamino)dimethylsilane (BDMADMS). With both types of silane, only experiments at the highest temperature, 275°C, resulted in new siloxane bonds at the surface and, hence, strongly oil-wetting behavior. The persistence of the modified surfaces upon immersion of the plates in water varied considerably with the type of silane used. The surface of the HMDS-treated plates started to degrade within 24 h after soaking the plates in water. Plates treated with BDMADMS remained oil wetting in both directions of the wetting cycle for up to 13 weeks of soaking in water and at least 9 additional weeks when soaked in other liquids.

Influence of initial surface damage on the final texture of chemically etched quartz plates

Various AT-cut quartz plates, mechanically lapped or polished prior to etching are etched at a constant temperature. The variations in the dissolution rate with the time of etching are found to depend on the surface damage in the initial stages of the chemical attack, but with prolonged etching all the dissolution rates tend to a common limiting value. Lapped and polished quartz plates exhibit opposite changes in roughness parameters with the depth of etch for short etching times. Subsequent dissolution leads, whatever the original surface preparation of the quartz plate, to equilibrium values of the roughness parameters characterized by the direction of the profilometry traces. Scanning electron micrographs are in agreement with these observations and reveal that pits of the same shape develop on polished and lapped quartz plates. Thus the initial surface damage has no influence on the final surface texture of deeply etched quartz plates which is determined primarily by the crystal orientation.

The optical determination of a surface layer on polished quartz plates

The optical determination of a surface layer on polished quartz plates

Design and Performance of Ultraprecise 2.5-mc Quartz Crystal Units

A 2.5-mc crystal unit has been developed for use in a new, extremely stable frequency standard oscillator. A well-balanced design was achieved by using a 30-mm-diameter, plano-convex, polished quartz plate, coated with gold and operated on its fifth overtone. The quartz plate is mounted on its quiescent edge in an evacuated bulb, and achieves a Q of five to six million, representative of the Q of the quartz itself. The temperature coefficient, current coefficient, frequency adjustment tolerance and frequency aging of the crystal unit are all consistent with a frequency stability in the order of one part in 1010. It was necessary to develop polishing methods that would not disturb the crystal structure of the quartz plate and new methods of orienting the crystollographic axes to achieve better temperature coefficient control. New methods of mounting the quartz plate were found that avoid strain and reduce the effects of shock and vibration. The new crystal unit makes possible oscillators characterized by excellent frequency stability, small and uniform aging and straightforward design. For periods up to one month, the frequency stability of such standards compares favorably with that of atomic frequency standards.

UV-Absorptionsküvette für extrem dünne Schichten mit genau messbarem Plattenabstand bis unterhalb 1μ

A very thin ring produced by evaporating aluminium in high vacuum on one of the two very exactly plane polished quartz plates forming the absorption cell is used as distance ring. The plate rotates in the vacuum during evaporation to obtain regular distribution of the metal. Plate distances down to 0.34μ were obtained. Small distances of this size can be measured with high precision by measuring interference fringes appearing in the spectrum due to the reflexions by the inner cell walls. The possible errors both experimental and technical are discussed and quantitative relations are given.

Infrared radiations from small particles

It has been shown that crystals whose particle-size is small in comparison with the wave-length absorb but do not reflect within the region of selective absorption. It is suggested that within this region a powder ought to reveal an emission maximum. This suggestion is put to experimental test which shows that powder-films of quartz, barium sulphate and potassium carbonate show pronounced emission maxima. The behavior of quartz-powder is shown to be quite the inverse of that of a polished quartz plate.