Gypsum Plate Research Articles

EFFECT OF IMMERSION TYPE III GYPSUM IN SODIUM HYPOCHLORITE AND POVIDONE-IODINE SOLUTIONS ON THE NUMBER OF CANDIDA ALBICANS COLONIES

Introduction: Cross-infection is the transfer of microorganisms that can occur from individual to individual or to object. Candida albicans is one of the infectious pathogens that can cause cross-infection in dentistry. One example is the manufacture of working models of gypsum material, which can cause cross-infection from patients to dentists or technicians, so it is necessary to control infection by means of disinfection of type III gypsum material work models. Objective: To determine the effectiveness of soaking type III Gypsum in a 0.5% Sodium hypochlorite and 2% Povidone Iodine solution against the growth of Candida albicans. Methods: A laboratory experiment with a total of 21 samples, consisting of 7 samples for each group. The sample is made of a type III gypsum plate measuring 2 x 1 x 0.5 cm. The sample consisted of 3 groups: treatment 1, treatment 2, and treatment 3. The study used the diffusion method. Gypsum plate type III was contaminated with Candida albicans and then immersed in a solution of sterile distilled water (C), 0.5% sodium hypochlorite (P1), and 2% povidone-iodine (P2). The soaking results were planted in SDA media, incubated for 2x24 hours, and then counted using a colony counter. The data were analyzed using Kruskal- Wallis and Mann-Whitney post hoc analyses. Results: In the Kruskal- Wallis analysis of significance (p), between each group, there was a significant difference (p<0.05). The Mann-Whitney post hoc analysis test showed a correlation between group K and P1 and P2 (p<0.05). Conclusion: 0.5% Sodium Hypochlorite and 2% Povidone Iodine solutions are effective as disinfectants using the immersion method in Type III Gypsum against the growth of Candida albicans.

Ultrasound flow phantom for transcranial Doppler: An assessment of angular mismatch effect on blood velocity measurement in comparison to optical particle image velocimetry

Detecting abnormal blood flow is possible through transcranial Doppler (TCD) ultrasound by measuring blood velocity in cerebral arteries. Velocity measurements are at the highest precision when the direction of blood flow coincides with the ultrasound beam. However, because TCD is typically performed blindly (i.e., without a B-mode), a 0° interrogation angle is usually assumed. This leads to a common issue of angular mismatch. This study quantitatively shows the angular mismatch effects on the measured velocities using a TCD ultrasound flow phantom compared with the velocities measured by optical particle image velocimetry (PIV) as control. Resulting errors with and without ultrasound machine angular correction were also considered. An ultrasound phantom developed by combining polyvinyl alcohol hydrogel (PVA-H), quartz glass as a scatterer, and a gypsum plate as a skull bone was utilized to approximate the middle cerebral artery TCD measurement from the temporal window. The PVA-H and quartz glass compositions were controlled to achieve transparency and enable PIV velocity measurement. Then, TCD velocity measurement was conducted on several interrogation and mismatch angles. Comparison results revealed that without an ultrasound machine angle correction, all measurements yielded underestimation with 73.9% at the highest in the 80° interrogation window at the 130 mL/min flow. On the other hand, with the correction, the errors in almost all angles were comparatively lower; however, at 80° at the 124 mL/min flow, a maximum overestimation rate of 113.7% was found, showing a larger error magnitude. Therefore, we find that angular mismatch, especially in larger angles, leads to inaccurate velocity measurements in TCD. Our results suggest that despite angle correction, velocity errors may still occur when the interrogation angle changes.

Optical signals of uniaxial and biaxial cholesteric lyotropic phases

Lyotropic cholesteric liquid crystalline phases were prepared by doping the ternary mixture of potassium laurate (KL)/decanol (DeOH)/ deuterium oxide (D2O) with brucine sulphate, in two different concentrations. Using the variation of the average color in a heating cycle, with and without the insertion of compensator a gypsum plate (1 λ), in the light path, the optical signal of the cholesteric phases ChD-(ChC+) was confirmed as being negative(positive). When the biaxial cholesteric phase (ChB) is between two uniaxial phases (ChD-ChB-ChD) or (ChD-ChB-ChC), the sign of the ChB phase depends on the uniaxial phase in its vicinity. In the case (ChD--ChB--ChD-), the phase ChB has a negative optical signal (ChB-) across the domain. However, if the ChB phase is between uniaxial cholesteric phases of opposite optical signals, it cannot have just one signal, but must have a change at some point in the biaxial domain showing (ChD--ChB--ChB+-ChC+) phase sequence.

Study on petrographic characteristics of devolatilization char/coke related to coal rank and coal maceral

Char/coke is the medium product of coal gasification, combustion, and metallurgy, whose morphological and optical characteristics are determined by coal rank and pyrolysis conditions. Twelve coals varying in coal rank from lignite to anthracite, collected in China, were used to study morphological and optical characteristics of char/coke upon different pyrolysis conditions systematically, specifically the char/coke structure and texture influenced by coal rank and coal maceral. Coke and char are distinguished by their caking ability. The morphology of the chars derived from low rank coals and high rank coals are closely related to coal maceral composition, whereas the morphology of cokes derived from high volatile bituminous A, medium, and low volatile bituminous is closely related to coal rank. In lignite, subbituminous, high volatile bituminous C, semianthracite, and anthracite, macerals are infusible during the heating process, but cavities generated in the low rank coals are related to the shapes of the liptinite macerals in the raw coals. Morphological changes of chars derived from high rank coals are difficultly to identify microscopically using an oil-immersion objective with a 1-lambda gypsum plate. in addition, the random reflectance (Rr) range of the chars becomes narrower as pyrolysis temperature increases. Overall, the Rr range of cokes is much larger than that of the chars, which is a result of the optical anisotropy of the caking coals. Although the Rr of vitrinite/huminite in the low and high ranks is distinct, the Rr of their chars is always similar when the pyrolysis conditions are the same. The Rr of char/coke is closely related to both coal rank and the final pyrolysis temperature. Longer residence time of the char/coke at the same pyrolysis temperature did not show a relevant difference in the reflectance of char/coke.

Yellowing of laser-cleaned artworks: Formation of residual hydrocarbon compounds after Nd:YAG laser cleaning of gypsum plates covered by lamp black

Abstract The removal of black crusts decaying the surface of artworks is an important concern for the conservation of cultural heritage. Nd:YAG laser cleaning of encrusted stones and plasters at 1064 nm is widely recognized as an effective restoration technique, but induces a noticeable yellowing of the treated surface. Several researches carried out on the effects of laser cleaning have been focused on the induced yellowing and how to visually mitigate this phenomenon. To this end, UV-B radiations were successfully used to lessen the laser-induced yellowing due to the removal of lamp black particles on gypsum. The mechanism at play for both the formation of the compounds yellowing the surface and their disappearance upon UV-B exposure remains, however, poorly understood. Within the frame of this research, we apply surface-sensitive characterization techniques to analyze the yellowed surface produced after Nd:YAG Q-Switched laser cleaning of lamp black deposit on a gypsum plate, and the same surface after UV-B exposure. A combination of X-ray photoelectron spectroscopy and Fourier-transformed infrared spectroscopy has been used to identify the residual carbon compounds responsible for the yellow coloration of the substrate. A nanoscale structural description of the ejected particles collected during the laser cleaning was finally performed with transmission electron microscopy. We found that the yellowing is due to partially oxidized hydrocarbons compounds deposited at the surface of the gypsum substrate. We propose that they form by reactions between carbon species emitted by the vaporization of the carbon particles, with hydrogen and oxygen produced by the dissociation of water molecules coming together from dehydration of the gypsum surface and from the water sprayed by the operator during cleaning.

Studying the evolution of both thermal and kinetic boundary layers in the vicinity of a vertical conductive gypsum plate under dynamic time-depending conditions at the building scale

In this paper, a vertical gypsum plate with thermal capacity placed in an open cavity under dynamic temperature decrease is numerically investigated in order to assess the evolution of the thermal and kinetic structure of the boundary layer and the convective heat transfer coefficient h over time. The particularity of this work resides in the fact that the system was made to simulate the case of a plate with thermal capacity under nocturnal conditions where the temperature is constantly decreasing. Thus, a two-dimensional CFD model is developed under the Ansys Fluent 14.5 environment and is validated using experimental data obtained for a plasterboard studied under dynamic temperature changes. This study contributes to give precise results about temperature, flux, convective heat transfer coefficient and velocity in the vicinity of a vertical wall with a thermal conductivity at the building scale. All the phenomena that occur in the vicinity of the heat capacitive vertical plate (gypsum) are analyzed and explicitly discussed. The main results of this study show that after simulating 1h real time we observe that turbulent flow begins to appear at the top level of the plate and after this moment the three flows (laminar, transitional and turbulent) coexist. Finally, mean convective heat transfer coefficient depends on the thermal storage capacity of the adjacent material. The average value of convective heat transfer coefficient increases over time by obtaining for a plasterboard (Cp=1100J/kgK) value of 1.8W/m2K and for a phase change material in a solid state (Cp=4350J/kgK) value of 2.4W/m2K at steady state.

Experimental realization of multi, zero, dual order and achromatic gypsum wave plate in a wavelength range 400–1000 nm

In a wide wavelength range (400–1000nm), the birefringence channeled spectra produced from interference of polarized white light is used to extract the birefringence Δn of gypsum crystal. In the same spectral range, the dispersion of gypsum birefringence is extracted and fitted to Cauchy dispersion function with relative error in finding Δn of an order 2×10−4. The calculated retardation introduced by gypsum crystal confirms that gypsum plate of thickness ≈2mm can act as a multiple order half and quarter wave plate for most of Ar+, Kr and He–Ne laser lines. Zero order full, half and quarter wave plate are experimentally realized at 675nm, 633nm and 633nm, respectively. In addition, a dual wavelength quarter wave plate working at 550nm and 930nm is also experimentally obtained. Finally, in the same spectral range quarter and half achromatic wave plate are practically realized by combining gypsum with MgF2 crystal.

INVESTIGATION AND SIMULATION OF TEMPERATURE CHANGES AND THERMAL DEFORMATIONS OF MULTILAYERED STRUCTURE WITH GYPSUM PLATE

This work presents numerical investigations of the thermal behaviour of fire resistant multilayered structure consisting of two steel sheets, gypsum plate and stone wool layer. Simulation was performed using SolidWorks ® Simulation software. The numerical simulation results were compared with experimental data obtained from the fire resistance test. The simulation results were found to be in good agreement with experimental results. It is shown that thermal behaviour of such multilayered structures can be investigated numerically, thus avoiding costly and time-consuming laboratory experiments. DOI: http://dx.doi.org/10.5755/j01.mech.18.3.1878

On Prediction of the Drying Rate in Superheated Steam Drying Process

The aim of the study was to determine how the drying rate in the falling drying rate period can be predicted in superheated steam drying. The study presents drying kinetics (determined experimentally) in the range of steam temperatures from 120°C to 200°C, with the superheated steam velocity from 0.18 to 0.40 m/s and under atmospheric pressure of a gypsum plate. In the study the drying rate based on the convective heat-transfer coefficient and steam-solid temperature difference was determined. It was proven that in order to predict drying rate in the falling rate period the surface temperature must be known.

Feasibility of Raman microspectroscopic identification of biomarkers through gypsum crystals

The miniaturized Raman spectrometer is considered to be a candidate instrument for the Pasteur payload (the ExoMars mission scheduled for 2018). This mission will, for the first time, combine mobility and access to subsurface locations where organic molecules might be well preserved. Evaporitic crystals are among the potential protected habitats that have been postulated. Various concentrations of biomarkers (beta-carotene, glycine and phthalic acid) dispersed in a gypsum matrix were analyzed through transparent mineral (gypsum) plates of different thicknesses. By doing so, conditions were simulated in which biomarkers were trapped within evaporitic crystals. Using a long-working distance objective, all studied concentrations of biomarkers mixed in gypsum powder were detected. The characteristic Raman bands were easily observable for a 10% mixture of all chosen biomarkers not only through a 3.3 mm plate and but even through a 5.2 mm plate. It was possible to detect key Raman bands of 1% phthalic acid/gypsum mixture and 1% beta-carotene/gypsum mixture even through a 5.2 mm gypsum plate. The 1% beta-carotene/gypsum mixture was still clearly distinguishable through an 8.5 mm gypsum crystal due to the known resonance Raman effect of the molecule.

Spectral variation of the birefringence, group birefringence and retardance of a gypsum plate measured using the interference of polarized light

Polarized white light interferometry is used to characterize the wavelength dependence of the birefringence, group birefringence and retardance of a gypsum crystal. Two different calculation schemes are used to extract values of the birefringence across the whole visible spectrum. In the spectral range 435 nm–642 nm, the variation of the gypsum birefringence is fitted to the two terms Cauchy formula and to a fourth order dispersion function. The gypsum birefringence is found to be inversely proportional with wavelength. The experimental method used gives a relative error in finding the gypsum birefringence of an order of 6×10 −4. The wavelength dependence of gypsum group birefringence is also calculated with a relative error of order 5×10 −4. In the same spectral range, the retardance changes by 28 π and the gypsum plate introduced halfwave retardance 15 times.

The Muqarnas Plate Found at Takht-i Sulayman: A New Interpretation

In 1968 the German excavation team at Takht-i Sulay man, Iran, found a 50 cm gypsum plate amid the palace ruins. This thirteenth-century plate was spon taneously recognized to be a muqarnas design. Ulrich Harb published the details of the plate and also sug gested an interpretation of its design;1 Mohammad Yaghan has more recently published other readings.2 In this paper we propose yet a different interpretation, which is more in accordance with surviving buildings of the period and the description of muqarnas by the famous mathematician al-Kashi (ca. 1430).

Full waveform inversion of a 3-D source inside an artificial rock

A full waveform inversion of the kinematics of a 3-D source inside an artificial rock plate is presented. The source is provided by a piezoelectric disc embedded inside a gypsum plate, excited by an arbitrary electrical signal. Elastic waves emitted from the source propagated through the plate and were recorded by an array of wide-band high-fidelity microseismic displacement sensors. These microseismic data are then inverted by deconvolving the recorded signals with the theoretical Green's functions to obtain the kinematics of the source modeled by force couples. The force time functions thus inverted are justified qualitatively by the known mechanical behavior and compared quantitatively to simplified electro-acoustic equations. For the first time, the combined use of a wide-band high-fidelity sensor, Green's functions incorporating Q damping, effective point source theory, and linear deconvolution yield physically justified time functions of the source kinematics.

CONVECTION HEAT TRANSEER COEFFICIENTS AT CONVECTIVE DRYING OF POROUS MATERIALS*

ABSTRACT Our measurements proved that the convective heat transfer coefficient (h) has a larger value hwet at the constant drying rate period and after that it falls down to a minimum one: hdry in the equilibrium dried state (see Fig.1). Our measurements showed also that the heat of vaporisation in the last phase of the falling drying rate period is far greater than it was in the constant drying rate period (see Fig.10). Our first measurements were made on a gypsum plate. Afterwards we carried out measurement research with fine glass powder and cement-perlite plate and determined hwet and hdry heat transfer coefficients as function of Reynolds number. All of these measurements confirmed our establishment that hwet is far greater than hdry .

THE CYST‐THECA RELATIONSHIP IN CALCIODINELLUM OPEROSUM EMEND. (PERIDINIALES, DINOPHYCEAE) AND A NEW APPROACH FOR THE STUDY OF CALCAREOUS CYSTS

ABSTRACT The paratabulate calcareous cyst of Calciodinellum operosum Deflandre was recorded in a sediment trap sample collected in the Bay of Naples (Tyrrhenian Sea, Italy). The germination of this resting stage produced a phototrophic vegetative cell that had the typical plate pattern of a Scrippsiella species. The cyst morphotypes, observed in a clonal culture of this species, ranged from cysts with well‐developed paratabulation to cysts in which the paratabulation was barely visible, to cysts covered by irregularly shaped crystals. The analysis of thin sections of the calcareous cysts using the polarized light microscope equipped with crossed nicols and a gypsum plate showed that the optical orientation of the calcite crystals was tangential in all the morphotypes examined. We suggest that the crystallographic method we describe might provide insights for calcareous cyst taxonomy and phylogeny.

Gypsum plate enhancement of cataclastic fabric in thin section

Individual fine particles in cataclastic zones (gouge) are often extremely difficult to distinguish in thin section in either plane- or cross-polarized light. It is equally difficult, using these techniques, to determine the relationship of fine fragments in gouge zones to one another or to their parent material. Cathodoluminescence can greatly improve such observations, but it too has limitations and requires special equipment. This paper discusses how using a gypsum plate, which causes light retardation, can enhance the interference colors of fine particles in gouge such that they are more clearly distinguishable. In addition, if cataclastic deformation within the gouge is not extreme, flow paths and origins for fine particles can be observed by using the gypsum plate, thus providing an easily available, inexpensive tool for the structural petrologist studying finely comminuted material.

The application of multilayer digital image processing techniques to the description of soil thin sections

A multilayer approach to the image analysis of soil thin sections is presented. Sixteen images from the same microscope field were digitized from photomicrographs obtained with different light polarizations combined with different colour filters. The light sources were plain transmitted light (PTL), between crossed polars(BXP), circularly polarized light (CPL) and CPL with gypsum plate. ERDAS: a digital imaging processing (DIP) system normally applied to remote sensing was used. This, together with the hardware, allowed the creation of multilayer images on which supervised and unsupervised classification procedures were applied to distinguish and quantify features such as quartz, clay coatings, matrix and pores. A combination of PTL and CPL images gave the best multilayer image. Inaccuracies in the classification procedures were corrected manually to produce a reference image which was compared with the images created by the classifications. The unsupervised classification had many limitations, however the supervised classification was very successful in differentiating the features.

破砕帯付近に作孔した先進ボーリングの応力解放に関する模型実験

Stress relief method is widely used in coal mines in many countries to prevent the gas outburst and rock burst. It is one of the effective methods to relieve the stress by boring in coal seams.The author made a model experiment to investigate the effect of the boring bored near fractured zone at the heading face on the stress relief. A three-dimensional model experimental apparatus of about 1: 80 geometrical scale was used. As the model rock mass, the gypsum plate was used and as the model coal seam, an artificial seam made from the mixture of water, gypsum and diatomite was used. The scale factor of the stress and strength was 1: 40.The effect of the stress relief was measured by varying the location of fractured zone, the thickness of fractured zone and the strength of model coal seam. The effect of the stress relief was evaluated by the degree of stress relief defined by the author. The characteristics of the stress distribution near the fractured zone and the relationship between the degree of the stress relief and the above experimental parameters were reported.

炭鉱のガス突出防止のためのスリットを用いた応力解放に関する模型実験

Stress relief method is widely used in coal mines in many countries to prevent the gas outburst and rock burst. It is one of the effective methods of relieving the stress to cut the slits in coal seams.The author made a model experiment to investigate the effect of the slitting at the heading face on the stress relief. A three-dimensional model experimental apparatus of about 1: 80 geometrical scale was used. The dependence of slit thickness, number of slits and the strength of model coal seam on the effect of the stress relief was measured. As the model rock mass, the gypsum plate was used and as the model coal seam, an artificial seam made from the mixture of water, gypsum and diatomite was used. The scale factor of the stress and strength was 1: 40.The effect of the stress relief was evaluated by the degree of stress relief defined by the author. A slitting standard for effective stress relief, such as to cut the several parallel slits and to cut the slits near roof or floor, was proposed.

Measurements of diffusive sublayer thicknesses in the ocean by alabaster dissolution, and their implications for the measurements of benthic fluxes

Fluxes of reactive chemical species across the sediment‐water interface can profoundly influence the dominant biogeochemical cycles in the worlds ocean. However, reliable in‐situ measurements of benthic fluxes of many reactive species cannot be carried out without adjustment of stirring rates inside benthic flux chambers to match boundary layer conditions prevailing outside. A simple method to compare flow levels consists of measurements of gypsum dissolution rates inside benthic chambers and on the seafloor. The measurement of the diffusion‐controlled dissolution rate of gypsum allows the estimation of the diffusive sublayer thickness and the time‐averaged bottom stress on the seafloor. This method had previously been intercalibrated with the stress sensor method in flumes and inside benthic chambers. We describe here free‐vehicle deployments of alabaster plates on the bottom of the ocean which gave results consistent with hydrodynamic theory. Errors in the calculated diffusive sublayer thicknesses were estimated to be about 10–15% for typical deployment conditions in the ocean. Current velocities 5 m off the bottom, which were measured concurrently during two deployments, allowed for comparisons with hydrodynamic predictions of diffusive sublayer thicknesses. The values obtained this way agreed within 15%. The measured mass transfer velocity was found to correlate with the plate dimension L, to the power of ⅓. This confirms the theoretical procedure for extrapolating to infinite plate size when calculating the sublayer impedance of solute fluxes from sediments (where L is large). Typical values of diffusive sublayer thicknesses, corrected to infinite plate size, were 1200 μm for current velocities, U100, of 2 cm s−1, and 500 μm at 8 cm s−1. Furthermore, values of friction velocities calculated from alabaster dissolution were compared with those using stress sensors. Gypsum plate values of u* were 0 and 30% lower than skin friction values of u*, at u* values of 0.6 and 0.2 cm s−1, respectively, possibly as a result of bottom roughness effects. A case is made for the importance of considering boundary layer dynamical conditions when benthic fluxes are to be measured correctly. When rates of oxygen uptake, carbonate dissolution, and nutrient species uptake or release in regions near the sediment‐water interface are fast compared with diffusion rates across the diffusive sublayer, overall rates can become mass transport controlled.