Quartz Halogen Research Articles

COOMET key comparison COOMET.PR-K1.a.2018 for spectral irradiance 250 nm to 2500 nmm, final report

Main textThis report describes the Key Comparison COOMET.R-K1.a.2018 for spectral irradiance in the wavelength range of 250 nm to 2500 nm, conducted by the Regional Metrology Organization "Euro-Asian Cooperation of National Metrological Institutions" (COOMET). The comparison was, in fact, a combination of three bilateral comparisons with the same link/pilot laboratory - the All-Russian Research Institute for Optical and Physical Measurements (VNIIOFI), the Russian Federation. The non-link laboratories were the Belarusian State Institute of Metrology (BelGIM), Belarus, the National Scientific Centre "Institute of Metrology" (NSC IM), Ukraine, and the National Metrology Institute of Türkiye (TÜBİTAK UME), Türkiye.The aim of the comparison was to link the BelGIM, NSC IM and TÜBİTAK UME measurement results to the CIPM key comparison CCPR-K1.a.2017, conducted by the Consultative Committee for Photometry and Radiometry (CCPR).Tungsten quartz halogen lamps of the FEL type (1000 W) were used as artefacts. Each participant used its own set of lamps. The sequence of measurements was participant - pilot - participant. The pilot measurements of the described here COOMET comparison were performed in a short time (within three months) after completing the measurements of CCPR-K1.a.2017, where VNIIOFI also was a pilot, which provided a high quality link.NSC IM performed measurements in the full spectral range, from 250 nm to 2500 nm, while BelGIM and TÜBİTAK UME managed to cover the range from 250 nm to 1100 nm only.The analysis of the comparison was performed following the approach described in the Appendix A of the Guidelines for CCPR and RMO Bilateral Key Comparisons (CCPR-G5). Differences from KCRV of BelGIM and TÜBİTAK UME, for the most of the measured wavelengths, do not exceed 2% and are within the expanded uncertainties. For NSC IM the differences from KCRV are within or comparable with the uncertainties in the IR range, from 900 nm to 2500 nm, but become larger with decreasing wavelength in the visible and UV reaching 9% at 250 nm.To reach the main text of this paper, click on Final Report. Note that this text is that which appears in Appendix B of the BIPM key comparison database https://www.bipm.org/kcdb/.The final report has been peer-reviewed and approved for publication by the CCPR, according to the provisions of the CIPM Mutual Recognition Arrangement (CIPM MRA).

CIPM key comparison CCPR-K1.a.2017 for spectral irradiance 250 nm to 2500 nm. Final report

Main textThis report describes the Key Comparison of the Consultative Committee for Photometry and Radiometry CCPR-K1.a.2017 for Spectral Irradiance in the wavelength range of 250 nm to 2500 nm. Tungsten quartz halogen lamps of the FEL type (1000 W) were used as artefacts. Each participant used its own set of lamps. The star scheme of measurements was applied with the sequence participant - pilot - participant. Twelve National Metrology Institutes participated in the comparison. Each participant's measurement data were based on a totally independent spectral irradiance scale realisation. VNIIOFI (the Russian Federation) served as a pilot. The measurements were carried out from 2017 - 2020.The analysis of the comparison was performed following the step-by-step approach described in Appendix B of the Guidelines for CCPR Key Comparison Report Preparation (CCPR-G2 Rev.4). The key comparison reference values (KCRV) were calculated independently at each wavelength as the weighted means with cut-off. The measurement data of all participants were used for the KCRV excluding just a few outliers in the wavelength range of 1700 nm to 2500 nm. The relative uncertainties of the KCRV were minimal, 0.08 %, at the wavelengths of 900 nm to 1500 nm and increasing towards the limits of the spectral range up to 0.28 % at 250 nm and 0.20 % at 2500 nm. Consistency checks were satisfied at 17 of the 28 measured wavelengths, but failed at 11 wavelengths, mostly in the infrared range. For the latter wavelengths the Mandel-Paule method was applied resulting in an additional uncertainty that varied depending on wavelength from 0.11 % to 0.89 %.In general, the measurement uncertainties submitted by the participants in this comparison were less than those submitted in the previous CCPR-K1.a comparison. This is evidenced by the values of the cut-off, which had decreased at all wavelengths by a factor of 1.2 to 3.0 depending on wavelength. However, only for seven participants the degrees of equivalence do not exceed the expanded uncertainties at almost all wavelengths. About 80 % of all results (all participants at all wavelengths) agree with the KCRV within 1 % over the whole spectral range and within 0.7 % in the visible, which is comparable with the results of the previous CCPR-K1.a comparison.To reach the main text of this paper, click on Final Report. Note that this text is that which appears in Appendix B of the BIPM key comparison database https://www.bipm.org/kcdb/.The final report has been peer-reviewed and approved for publication by the CCPR, according to the provisions of the CIPM Mutual Recognition Arrangement (CIPM MRA).

SUSTAINABLE ENERGY-EFFICIENT CONVERSION OF WASTE TEA LEAVES TO REDUCING SUGAR: OPTIMIZATION AND LIFE-CYCLE ENVIRONMENTAL IMPACT ASSESSMENT

Innovative protocols involving energy-proficient pretreatment of waste tea leaves (WTL) for preparation of cellulose and its subsequent photocatalytic hydrolysis (PH) for production of total reducing sugar (TRS) have been reported. The WTL was subjected to alkali pretreatment (60 °C, 1 h) followed by bleaching (employing peracetic acid, 65 °C, 2 h) in a quartz halogen irradiated batch reactor (QHIBR) for efficient separations of lignin and hemicellulose fractions to produce WTL derived cellulose fiber (WTLDCF; 94.5% cellulose). Consequent PH of WTLDCF in QHIBR using combination of Amberlyst-15 and nano-TiO2 catalysts was optimized (parameters: 40 min, 70 °C, 1:30 WTLDCF to water weight ratio and 5 wt. % catalyst concentration) employing Taguchi design that provided maximum 68.25% TRS yield. The QHIBR demonstrated faster hydrolysis and superior energy-efficiency over conventional reactor owing to quartz halogen irradiation. Life cycle assessment indicated an acceptable global warming potential of 2.215 kg CO2 equivalent; thus, establishing an energy-efficient environmentally sustainable WTL valorization process.

Life cycle assessment of waste printed wiring board-derived Ag photocatalyst for sustainable fermentable sugar production.

An exploratory work involving waste printed wiring board (WPWB)-derived inexpensive silver oxide (Ag2O)-grafted silica-alumina composite photocatalyst (SAA) using quartz halogen and UVA irradiations (QHUV) (wavelength: 315 nm-1000 nm) has been revealed. The efficacy of the novel SAA photocatalyst was assessed in the synthesis of fermentable sugar (FS) by photo-hydrolysis of pure crystalline cellulose (PCC) in the QHUV-assisted batch reactor (QHUVBR), and the process parameters (5% AgNO3 doping, 7.5% catalyst concentration, 20 min PH time, and 80 °C PH temperature) were optimized using Taguchi orthogonal array design. The BET analysis of the optimal SAA catalyst possessed high surface area (27.24 m2/g), high pore volume, and pore diameter (0.042 cc/g and 13.1684 nm), respectively, whereas the XRD indicated the presence of significant crystalline phases of Ag2O. EDS mapping displayed the uniform distribution of silver active sites on silica-alumina support of the optimal SAA photocatalyst. The optimized parametric conditions in QHUVBR resulted in a maximum FS yield of 77.53% which was significantly higher compared to that achieved (34.52%) in a conventionally heated batch reactor (CHBR). Besides, the energy consumption was 75% more in CHBR (600 W) in comparison with QHUVBR (150 W), making the process energy-efficient and cost-effective. The environmental sustainability could be ascertained from the life cycle assessment (LCA) study in terms of low climate change, ionizing radiation, metal depletion, human toxicity, and other potential indicator values.

E-waste derived silica-alumina for eco-friendly and inexpensive Mg-Al-Ti photocatalyst towards glycerol carbonate (electrolyte) synthesis: Process optimization and LCA

Valorization ofe-waste, i.e. waste printed circuit board (WPCB) through mechano-chemical activation to obtain silica as the catalyst support and alumina as the catalyst precursor for eco-friendly synthesis of inexpensive highly proficient photocatalyst has been explored. The WPCB derived silica-supported layered double oxide photocatalyst (MATLSW) and its counterpart (MATLSC) involving commercial silica and alumina precursors were synthesized through the wet-impregnation method under energy-efficient solar simulated quartz halogen lamp (SSQHL) irradiations to improve its photocatalytic properties compared to conventional methods. The prepared MATLSWpossessed a significantly low band-gap-energy (1.58 eV) that rendered efficient photocatalysis in the green-synthesis of glycerol carbonate (GC) (an effective electrolyte). The catalytic performance of the optimal MATLSWresulted in a superior yield of GC (98.68%) compared to that rendered by MATLSCcatalyst (GC yield: 96.56%) at optimal process conditions. Detailed life cycle assessment (LCA) of the entire process (deploying Ecoinvent 3.5 database) dictated conducive environmental impacts concerning 1 kg GC synthesis alongside a scale-up study for 1 MT GC synthesis encompassing silica-alumina extraction from WPCB, MATLSW preparation, and employment of SSQHL-radiated batch reactor (SSQHLBR) (56.64% less energy consumption than conventional). The overall process deploying the novel MATLSWin conjunction with the effectual reactor demonstrated superiority over the conventional GC synthesis process through appreciable reductions of environmental impact parameters, namely GWP, FDP, and HTP by 5.78%, 3.60%, and 5.72% respectively. The developed green process for e-waste utilization can procreate an effective waste management protocol towards a cleaner world.

Properties of CrSi2 Layers Obtained by Rapid Heat Treatment of Cr Film on Silicon.

The changes in the morphology and the electrophysical properties of the Cr/n-Si (111) structure depending on the rapid thermal treatment were considered in this study. The chromium films of about 30 nm thickness were deposited via magnetron sputtering. The rapid thermal treatment was performed by the irradiation of the substrate’s back side with the incoherent light flux of the quartz halogen lamps in nitrogen medium up to 200–550 °C. The surface morphology was investigated, including the grain size, the roughness parameters and the specific surface energy using atomic force microscopy. The resistivity value of the chromium films on silicon was determined by means of the four-probe method. It was established that at the temperatures of the rapid thermal treatment up to 350 °C one can observe re-crystallization of the chromium films with preservation of the fine grain morphology of the surface, accompanied by a reduction in the grain sizes, specific surface energy and the value of specific resistivity. At the temperatures of the rapid thermal treatment from 400 to 550 °C there originates the diffusion synthesis of the chromium disilicide CrSi2 with the wave-like surface morphology, followed by an increase in the grain sizes, roughness parameters, the specific surface energy and the specific resistivity value.

Nickel silicide formation with rapid thermal treatment in the heat balance mode

The formation of nickel silicide layers on (111)-Si substrates during rapid thermal annealing in the heat balance mode was studied by the Rutherford backscattering method, X-ray diffraction, transmission electron microscopy, and electrophysical measurements. Nickel films of about 70 nm thickness were deposited by magnetron sputtering at room temperature. The rapid thermal treatment was carried out in a heat balance mode by irradiating the substrates backside with a non-coherent light flux of quartz halogen lamps in the nitrogen medium for 7 seconds up to the temperature range of 200 to 550 °C. The redistribution of nickel and silicon atoms to monosilicide NiSi composition starts already at a temperature of 300 °С and almost ends at a temperature of 400 °С. In the same temperature range, the orthorhombic NiSi phase with an average grain size of about 0.05–0.1 μm is formed. At a rapid thermal treatment temperature of 300 °C, two phases of silicides (Ni2 Si and NiSi) are formed, while a thin layer of unreacted Ni is retained on the surface. This fact can be explained by the high heating rate at the initial annealing stage, at which the temperature conditions of the NiSi phase formation occur earlier than the entire Ni layer manages to turn into the Ni2 Si phase. The layers with a simultaneous presence of three phases are characterized by a high roughness of the silicide-silicon interface. The dependence of the specific resistivity of nickel silicide layers shows an increase to the values of 26–30 μOhm · cm in the range of rapid thermal treatment temperatures of 200–250 °C and a subsequent decrease to the values of about 15 μOhm · cm at a rapid thermal treatment temperature of 400 °C. This value of specific resistivity is characteristic of the high conductivity of the NiSi phase and correlates well with the results of structure studies.

Preservation of Aloe vera and soybean flour fortified Granny Smith apple through optimised quartz–halogen radiated vacuum drying: kinetics and quality evaluation

Granny Smith (GS) apple has low protein content and poor antimicrobial properties; hence it has been blended with Aloe vera (AV; high ascorbic acid, antimicrobial and antioxidant properties) and soybean flour (SF; rich in phenols, flavonoids, ascorbic acid, total antioxidant and protein) in different proportions to obtain fortified GS, i.e. GSAVSF. Moreover, GS being a perishable fruit, its moisture content should be reduced to enhance shelf life. Accordingly, this GSAVSF was osmotically pre-dehydrated and finally dried through energy-efficient quartz-halogen radiation (QHR) assisted vacuum-drying (QHRVD) to produce dried GSAVSF i.e. (DGSAVSF) under optimized conditions. The optimally dehydrated DGSAVSF product resulted in minimum moisture (4.85% w/w) and maximum protein (6.24 g kg-1 ) content. The application of osmotic dehydration and QHRVD afforded acceptable colour of DGSAVSF compared to GSAVSF (ΔEI * = 10.07 ± 0.21). A parametric drying model was formulated that corroborated well with Fick's equation. QHRVD rendered high moisture diffusivity (1.49 × 10-8 m2 s-1 ) and low activation energy (27.64 kJ mol-1 K-1 ). Appreciable quality improvements with respect to fresh GS concerning ascorbic acid (176.05%), total phenolic (579.07%), total flavonoid (333.33%) contents and 2,2'-diphenyl-1-picrylhydrazyl radical scavenging activity (446.71%) could be achieved. The product demonstrated satisfactory shelf life (1 × 104 CFU g-1 : aerobic mesophilic; 1 × 104 CFU g-1 : mould and yeast) and high rehydration ratio (4.25 ± 0.1). The enrichment of GS with AV and SF along with optimal drying protocols could provide a quality fortified DGSAVSF through an energy-proficient sustainable process. The highly nutritious product with suitable colour, microbial stability and rehydration ratio also satisfied a 9-point hedonic scale, thus confirming consumer acceptability. © 2020 Society of Chemical Industry.

Structure and morphology of CrSi<sub>2</sub> layers formed by rapid thermal treatment

The formation of chromium disilicide layers on n-type single crystal silicon substrates (111) during rapid thermal annealing in heat balance mode by the methods of Rutherford backscattering, X-ray diffraction and transmission electron microscopy of cross sections was investigated. Chromium films of about 30 nm thickness were deposited by magnetron sputtering of a chromium target with argon ions onto silicon substrates at room temperature. The rapid thermal treatment was carried out in a temperature range of 200 to 550 °C in a heat balance mode by irradiating the substrates backside with a non-coherent light flux of quartz halogen lamps in a nitrogen ambient for 7 s. It was established that hexagonal phase of chromium disilicide formation with grain size of 150–300 nm occurs in a threshold manner when the temperature of rapid thermal treatment exceeds 400 °C. At the same time, there are strong changes in the films surface morphology and surface roughness, and a silicide-silicon interface occur. In this case the wavy film surface morphology practically repeats silicide-silicon interface morphology (the surface exactly replicates the interface). The mechanism of CrSi2/Si interface structure roughness formation based on consideration of Kirkendall effect and deformation-stimulated diffusion of vacancies is proposed and discussed. The research results of the structure and morphology of CrSi2 layers on silicon are well-correlated with the results of the Schottky barrier electrophysical measurements. The results obtained can be used in microelectronics for forming rectifying contacts and interconnects metallization for integrated circuits, as well as for thermoelectric and optoelectronic applications.

Quartz halogen radiated fast and energy‐efficient convective vacuum drying of green tea fortified Himsagar mango: Optimization, kinetics, and quality assessment

AbstractThe nutritional attributes of Himsagar mango (HM; Mangifera indica L.) were enriched through fortification with green tea (GT; Camellia sinensis) extract followed by an energy‐proficient rapid drying technique. The HM fortified by GT (HMGT) was dehydrated employing vacuum‐drying under quartz halogen radiation (QHRVD) and the optimal process parameters were determined corresponding to a minimal moisture content of the final dehydrated HMGT deploying Taguchi orthogonal design. Additionally, an efficient periodic convective‐drying protocol was coupled with QHRVD (PQHRVD) to further escalate the dehydration of HMGT through cyclic injection of CO2 to stimulate forced diffusion, thus facilitating drying time reduction by approximately 50% compared to QHRVD. Faster drying rate and superior energy‐efficiency could be achieved in PQHRVD owing to higher effective moisture diffusivity (4.71 × 10−10 m2 s−1) and lower activation energy (2.13 kJ mol−1) in comparison with QHRVD (2.03 × 10−10 m2 s−1; 3.65 kJ mol−1). Thus, the periodic CO2 convection exhibited a remarkable reduction in processing time and energy consumption and produced a functionally enriched HM with significantly higher antioxidant properties, phenolics, ascorbic acid, and flavonoid contents.Practical applicationsHimsagar mango (HM), a tropical high‐demand fruit has been fortified with green tea (GT) (Camellia sinensis) extract for quality improvement. The amalgamated Himsagar mango was subsequently vacuum‐dried to improve the product shelf‐life and to augment the nutritional attributes. The energy‐efficient quartz halogen radiated vacuum‐drying (VD) technique was optimized to render a superior quality foodstuff. The VD operation was further intensified through periodic convection by CO2 to make the operation more beneficial. The cyclic CO2 convection resulted in significant augmentation in drying rate and rendered a lucrative foodstuff. The nutritionally enriched “HM fortified by GT” (HMGT) product displayed improved nutritional attributes (higher antioxidant properties, phenolics, ascorbic acid, and flavonoid contents) and enhanced shelf life for potential application in preparation of candy, cake, sweet, or dietary supplements. Therefore, the energy‐proficient and rapid drying method providing the functionally improved HMGT product can lay a prospective foundation for bakery and related food industries.

Electron-microscope investigations of the Pt-Si system during its rapid thermal treatment

The paper is dedicated to investigation of the influence of rapid thermal treatment on the microstructure of platinum silicide. The Pt films 43.7 nm thick were applied on the substrates of the monocrystal silicon by means of the magnetronic sputtering of platinum with the purity of 99.95 % on the МРС 603 set-up with the cryogenic pumping to the pressure not worse than 5*10-5 Pa. As an operating medium, argon was used with the purity of 99.933 %. Rapid thermal treatment of samples was performed in the thermal balance conditions by irradiating the non-working side of the wafer with the incoherent light flow in the nitrogen atmosphere during 7 s at the temperatures of 200-550 °C. The irradiation source in the set-up was represented by the quartz halogen incandescent lamps. The comparative analysis was done through the traditional long thermal treatment of the platinum films at a temperature of 550 о С for 30 min in the nitrogen atmosphere. Investigations of the platinum silicide microstructure were performed by means of the transmission electron microscopy which demonstrated that the increase in the RTT temperature initiates first the annealing of defects on the inter-grain boundaries, which is evident from the more distinct contrast from the grains, and then one can observe their growth reflecting the forming of the new phase (silicide one). Such progress of changes of the platinum silicide microstructure and of the size of the grains with the increase in treatment temperature is determined by the heat of its forming. As the Pt2Si phase forming heat is minimum and constitutes 10.4-16.8 Kkal/atom of metal, and for PtSi - 15.7-25.5 Kkal/atom of metal, then the forming of a stable PtSi structure requires a higher temperature. The authors carried out calculations of the activation energy of the diffusion synthesis of platinum silicide during rapid thermal treatment. The calculations show that it is 0.37 eV smaller, than during the long thermal treatment. This means that in this case this process is subject to acceleration related to the rupture of the silicon-silicon bonds and electron excitation in silicon under the influence of the photon flow.

EFFECT OF RAPID THERMAL TREATMENT CONDITIONS ON ELECTROPHYSICAL PROPERTIES OF CROMIUM THIN FILMS ON SILICON

Present paper is devoted the determination of the effect of the temperature of the process of rapid thermal treatment of chromium films on n-type conductivity silicon on their resistivity and contact properties of the interface. Chromium films of about 30 nm thickness were deposited by magnetron sputtering onto the surface of silicon substrates having a resistivity of 0.58 to 0.53 ohms×cm. The rapid thermal treatment was carried out in a heat balance mode by irradiating the back side of the substrates with non-coherent light flux in nitrogen ambient for 7 seconds. Quartz halogen incandescent lamps were used as the heating source. The temperature of the rapid thermal process ranged from 200 to 550 °C. The thickness of the chromium films was determined by raster electron microscopy. The surface resistance of the samples was measured by a four- probe method. The Schottky barrier height and the ideality factor were determined from I-V plots. It is shown that at the temperature of the rapid thermal process 400 °C a layer of chromium disilicide is formed, causing a sharp increase in the resistivity of chromium films to 1.2 mOhm×cm and the height of the Schottky barrier to 0.6 V. When the temperature of the rapid thermal process is further increased to 550 °C, the resistivity increases monotonically to 4.0 mOhm×cm due to the increase in the width of the interstitial boundaries increasing the scattering of charge carriers in the CrSi2 layers. It has also been shown that rapid thermal treatment of the Cr/Si structure at a temperature of 450–500 °C enables to obtain rectifying contacts with a barrier height of 0.615 V and an ideality factor of 1.1. The results obtained can be used in the technology of integrated electronics products containing Schottky contacts as well as thin film resistors.

A new method for opening quartz halogen light bulbs in vehicle accident investigations

After a car accident, it is an important forensic task to evaluate the status of the vehicle's lighting at the time of impact. In some cases, the bulb has to be opened up to allow proper examination of the high and low beam filaments. Quartz halogen pressurized bulbs are both rigid and brittle and their internal pressure makes them likelier to explode. This study aimed to develop a more elegant method of breaking halogen bulbs open that would minimize the danger of explosion and the risk of damaging the filaments in the process. As part of the study, several opening methods were tried on multiple pressurized quartz halogen bulbs, such as cutting a groove with a hacksaw or a rotary tool, using a propane torch on the bulb to cut or warm it and then cooling it rapidly. Repeated testing by several examiners has shown that the new method developed in this study is the safest and easiest compared with other established methods.

Evaluation of selected electric infrared emitters for tomato peeling

The performance of selected electric infrared (IR) emitters with different emissive powers was investigated examining tomato heating rate, peeling performance and final product quality. Four types of electric emitters, including ceramic full trough element (CFTE), pillared quartz element (PQE), quartz tungsten medium (QTM), and quartz halogen medium (QHM), were selected based on their ability to produce high emissive power with appropriate range of wavelengths. The electric emitters were tested to heat the tomato cultivar Hz 6410 for peeling, using a prototype IR heating system under similar conditions. The electric emitters attained high surface temperatures (602–825 °C) and emissive powers (27–37 kW m−2). High emissive powers of these electric emitters increased the heating rate of tomato, resulting in a high peeling performance and product quality in significant short times (≤25 s). Among all the studied emitters, PQE with the highest surface temperature (825 °C) and emissive power (37 kW m−2) took 10 s to heat the tomatoes to the degree that they had excellent peeling easiness while meeting the USDA peelability standard. However, tomatoes experienced undesirable skin burns when the heating time was too long at high emissive powers. The study provided valuable information about the suitability of different electric emitter with the IR wavelength spectrum (2.6–3.3 μm) for tomato peeling application.

High temperature modal analysis of a non-uniformly heated rectangular plate: Experiments and simulations

Structures in demanding environments where high-temperatures and high-frequency vibratory loads are combined often experience fatigue which shortens their lifecycle. A limited amount of experimental data is available on the mechanical behaviour of plates under such thermo-acoustic loading. In this work, on Hastelloy-X plates, non-contact techniques were used to simultaneously acquire full-field temperature and out-of-plane displacement data for a thin plate. The plate was heated using halogen quartz lamps arranged in two different configurations and mechanically loaded using a commercially-available shaker. The centre of the plate was mounted to the shaker through a stinger with a bolted connection. The structure's resonant frequencies were determined using experimental modal analysis when mechanically loading the plate using a randomly varying signal from 0 to 800 Hz. Modal shapes were studied by exciting the plate to its first eleven resonant frequencies and acquiring displacement data using a PL-DIC (Pulse Laser Digital Image Correlation) method. Infra-red imaging was used to acquire temperature maps across the specimen. A finite element model was developed to include temperature-dependent material properties in the prediction of the plate's resonant frequencies and mode shapes. For the first time, experimental results showed the resonant response of the plate to strongly depend on the temperature distribution across the structure, correlating well with past predictive work in the literature. This was supported by the results from the finite element model, which were validated against experimental data and found to yield reliable predictions.

Intracoronal stress transfer through enamel following RBC photopolymerisation: A synchrotron X-ray study

ObjectivesTo measure the spatial distribution of crystallographic strain in tooth enamel induced by the photo-polymerisation of a dimethacrylate resin based composite cavity restoration. MethodsSix sound first premolar teeth, allocated into two groups (n=3), were prepared with mesio-occlusal distal cavities. The enamel was machined at the point of maximum convexity on the outer tooth to create a vertical fin of thickness 100μm and 0.5mm depth to allow for synchrotron X-ray diffraction measurements. 2D diffraction patterns were used to determine crystallite orientation and quantify changes in the hydroxyapatite crystal lattice parameters, before and after photo-polymerisation of a composite material placed in the cavity, to calculate strain in the respective axis. The composite was photo-polymerised with either relatively high (1200mWcm−2, group 1) or low (480mWcm−2, group 2) irradiances using LED or quartz halogen light sources, respectively. A paired t-test was used to determine significant differences in strain between irradiance protocols at ɑ=0.001. ResultsPhoto-polymerisation of the composite in the adjacent cavity induced significant changes in both the crystallographic c and a axes of the enamel measurement area. However the magnitude of strain was low with ∼0.1% difference before and after composite photo-polymerisation. Strain in enamel was not uniformly distributed and varied spatially as a function of crystallite orientation. Increased alignment of crystallites perpendicular to the cavity wall was associated with higher c axis strain. Additionally, strain was significantly greater in the c (p<0.001) and a axis (p<0.001) when using a high irradiance photo-polymerisation protocol. SignificanceAlthough cuspal deflection is routinely measured to indirectly assess the ‘global’ effect of composite shrinkage on the tooth-restoration complex, here we show that absolute strains generated in enamel are low, indicating strain relief mechanisms may be operative. The use of low irradiance protocols for photo-polymerisation resulted in reduced strain.

Image processing based quantitative damage evaluation in composites with long pulse thermography

Pulsed thermography is a contactless and rapid non-destructive evaluation (NDE) technique that is widely used for the inspection of fibre reinforced plastic composites. However, pulsed thermography uses expensive and specialist equipment such high-energy flash lamps to generate heat into the sample, so that alternative thermal stimulation sources are needed. Long pulse thermography was recently developed as a cost-effective solution to enhance the defect detectability in composites by generating step-pulse heat into the test sample with inexpensive quartz halogen lamps and measuring the thermal response during the material cooling down. This paper provides a quantitative comparison of long pulse thermography with traditional pulsed thermography and step heating thermography in carbon fibre and glass fibre composites with flat-bottomed holes located at various depths. The three thermographic methods are processed with advanced thermal image algorithms such as absolute thermal contrast, thermographic signal reconstruction, phase Fourier analysis and principal component analysis in order to reduce thermal image artefacts. Experimental tests have shown that principal component analysis applied to long pulse thermography provides accurate imaging results over traditional pulsed thermography and step heating thermography. Hence, this inspection technique can be considered as an efficient and cost-effective thermographic method for low thermal conductivity and low thermal response rate materials.

Heating and dehydration of grain and cereals at a combined energy supply

The paper dwells on the development of experimental dependencies of heating and dehydration of grain and cereals when varying the irradiance, ambient temperature in the heat treatment zone and the initial moisture content of product, and the development of the mathematical models for heating and dehydration of some grains and cereals. The grain was heated on the laboratory equipment with quartz halogen linear infrared emitters. The irradiance on the working surface in the treatment zone was determined by calculation using a specially developed program. The ambient temperature was determined by a thermocouple thermometer placed in a ceramic tube. The grain temperature was estimated as average by weight by a thermocouple thermometer after its transfer into a thermally insulated container. The following dependencies have been obtained: 1 - Temperature dependence of the heating time for different heating modes and initial moisture content. 2 - Dependence of moisture content on the heating time under different conditions and initial moisture content. 3 - Dependence of moisture content on a temperature under different conditions and constant initial humidity. The models of the heat-moisture exchange and dehydration processes have been created, and the model parameters K0 and KT of the temperature dependence of some grains have been identified, as well as their dependence on moisture content and treatment modes has been evaluated. It has been established that this model describes adequately the process of dehydration to an extent limited by the upper temperature value of grain not much more than 100 ºÐ¡. Within not limited to the upper temperature value of grain not much more than 100 ºÐ¡. From the presented graphs and earlier obtained results for barley and millet, it can be assumed that the model describes adequately experimental data on the small-sized (3 - 5 mm) objects.

Non-destructive prediction of ‘Marsh’ grapefruit susceptibility to postharvest rind pitting disorder using reflectance Vis/NIR spectroscopy

Abstract Postharvest RP is a progressive rind physiological disorder affecting citrus fruit during postharvest storage, reducing external quality of the fruit. The disorder develops 3–5 weeks after harvest, making it difficult to detect during grading and sorting in commercial packing lines. The Vis/NIR spectroscopy and associated chemometric analytical methods were explored for non-destructive prediction of ‘Marsh’ grapefruit (Citrus x paradisi MacFad) susceptibility to rind pitting. Reflectance Vis/NIR spectral data was acquired from fruit, just after harvest, using a laboratory bench-top monochromator NIR System equipped with a quartz halogen lamp and lead sulfide detector. Reference measurements for calibrating and validating PLS models included visual scores of RP and rind physico-chemical variables related to the disorder. The spectral data was correlated to RP scores and rind physico-chemical properties after eight weeks in cold storage and a week in shelf life. Good prediction of RP was obtained (R2p = 0.78; RPD = 2.03; RMSEP = 1.41). Prediction models for rind physicochemical properties successfully developed and validated included rind total antioxidant capacity (R2p = 0.95), β carotene (R2p = 0.99), total carotenoids (R2p = 0.92), chlorophyll a (R2p = 0.89), chlorophyll b (R2p = 0.93), dry matter (R2p = 0.88), sucrose (R2p = 0.91), glucose (R2p = 0.93) and fructose (R2p = 0.94). Principal component analysis successfully segregated fruit based on canopy position and susceptibility to rind pitting disorder. The ability of Vis/NIR spectroscopy coupled with chemometric analysis to cluster fruit based on canopy position is recommended as a secondary approach to discriminate fruit with high susceptibility to RP since RP occurrence was high on fruit from outside canopy.

Pressure dependence of refractive index of Ge near the absorption edge

Pressure-dependent refractive index of semiconductor germanium (Ge) near the absorption edge has not been well studied theoretically and experimentally to date. In this paper, we present a pressure-dependent refractive index of Ge film near its absorption threshold (about 1550 nm), deduced from the reflectivity of high crystalline Ge film coated on a fiber end. The thin Ge layer is deposited on one end of an optical fiber by using an E-beam evaporation machine equipped with a substrate heater of a quartz halogen lamp. In order to obtain high crystalline film, the quartz halogen lamp heater provides a constant substrate temperature of 450 ℃ during film deposition. After the film forming, the sample is transferred into a muffle furnace with a nitrogen atmosphere and annealed at 600 ℃ for 20 h to guarantee the formation of higher crystalline film. The process of light propagating through the optical fiber and reflecting from the Ge thin-film involves multi-beam interference. An abnormal dispersion is observed in the refractive index spectra of the polycrystalline Ge near the absorption edge. A comparison shows that the refractive index spectrum of the amorphous Ge is normal dispersion. Unlike previously reported results that the pressure-dependent refractive index had a negative value, in our experiment it is observed to be a positive value near the absorption edge. To better understand this phenomenon, we use a critical point model including the pressure effect to successfully fit the experimental data. We obtain an abnormal dispersion range of 1505-1585 nm and a range of negative value of pressure-dependent refractive index of 1500-1580 nm from the critical point model. In this paper, we adopt the method of high crystalline Ge film coated on a fiber end. This method has the advantages of small volume, high precision and strong stability, which can be used to measure the optical properties of many thin film materials under the different conditions (temperature, electric field or magnetic field, etc.). In this work, we obtain the refractive index of the Ge film and its pressure dependence near the C-band of the optical fiber communication, and these results are conducive to optimized design of the Ge-based optical systems near the C-band of the optical fiber communication.