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A spectroscopic method for quick evaluation of tint strength and tint tone of titania (rutile) pigment and factors affecting them
摘要： Titanium dioxide (TiO2) manufacturing industries measure optical properties such as brightness, colour, tint strength, tint tone, gloss, scatter coefficient, and others to ensure the quality of the product. Product characterization and process control generally focus on the optical properties, which determine its quality. In this work, titania rutile pigment with varying tint strength and tint tone is analyzed and a correlation is established between particle size and the optical properties such as tint strength and tint tone. It is observed that optical properties of titania pigment depends on the particle size as well as particle size distribution. A relatively faster evaluation of tint strength and tint tone can be made using the reflectance and particle size measurements. Analytical samples were prepared by ultrasonic dispersion of pigment in water containing calgon as dispersing agent. To verify the accuracy of the method, pigment tint strength and tint tone obtained from this study are compared with those resulting from traditional analysis. The results showed that the new method is viable.
关键词： optical properties,tint strength,reflectance,titania pigment,tint tone
更新于2025-09-23 15:23:52
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Topology and polarity of dislocation cores dictate the mechanical strength of monolayer MoS2
摘要： In contrast to homoelemental graphene showing common dislocation dipole with pentagon-heptagon (5|7) core, heteroelemental MoS2 is observed to contain diverse dislocation cores that tune the chemical and physical properties. Yet, how the inevitable dislocation cores in MoS2 affect the mechanical behaviours remains virtually unexplored. Herein, we report direct atomistic simulations of mechanical characteristics of isolated dislocation-embedded MoS2 monolayers under tensile load. All isolated dislocation cores in MoS2 monolayer rise polar stress-concentration, while those with larger Burgers vector are less energetically-favorable configurations but show local wrinkling behaviour. It is revealed that the intrinsic tensile strength of MoS2 is dictated by topology and polarity of dislocation cores. There is a strong inverse correlation between the maximum residual stresses induced by the dislocation cores and the strength of MoS2 monolayers. Mechanical failure initiates from the bond at dislocation polygon on which side there is a missing atomic chain. Armchair-oriented 4|8 dislocation exhibits sole brittle failure, however, dual brittle/ductile fractures occur in zigzag-oriented dislocations; Mo-S-Mo angle-oriented crack is brittle, while the S-Mo-S angle-oriented crack becomes ductile. Our findings shed sights on mechanical design of heteroelemental 2D materials via dislocation engineering for practical application.
关键词： Mechanical strength,Fracture characteristics,Monolayer MoS2,Molecular dynamics simulations,Dislocation cores
更新于2025-09-23 15:23:52
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The mechanical and photocatalytic properties of modified gypsum materials
摘要： Co-modi?ed TiO2 photocatalysts (TiO2-N,C) were added to commercial gypsum to obtain self-cleaning building material. The gypsum/TiO2 composite were also studied towards their mechanical properties. The highest photocatalytic activity was obtained for gypsum samples containing TiO2/N,C photocatalyst treated at 100–300 °C, attributed to high anatase phase participation, relatively high nitrogen and carbon content and high BET surface area (ca. 170–270 m2/g). In this case (300 °C) the model pollutant (azo dye) degradation rate was 85% and 70% after 15 h of UV and vis irradiation, respectively. Higher compressive strength values was observed for gypsum sample loaded with photocatalysts treated at higher temperatures (600–800 °C), attributed to rutile phase presence and large crystallite size. The grinding operation during gypsum/TiO2 composite preparation can contribute towards the increase of compressive strength (even 40%) by reduction of gypsum particle size whereas photocatalyst particles act as the e?ective ?llers of void spaces in gypsum material.
关键词： Modi?ed gypsum,Photocatalysis,TiO-N,C,Compressive strength
更新于2025-09-23 15:23:52
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[IEEE 2018 Seventh Balkan Conference on Lighting (BalkanLight) - Varna (2018.9.20-2018.9.22)] 2018 Seventh Balkan Conference on Lighting (BalkanLight) - Investigation of Reliability of Diversity Systems Through Stress-Strength Model Analysis
摘要： Paper concerns a problem of reliability indexes calculation of two channel homogeneous and diversity system. Using SSM it is easy to determine the probability of Common Cause Failures (CCF) and other parameters of investigated redundant systems. Here is used a complex approach with Multi-Factor Stress-Strength Model (MFSSM). The obtained analytical formulas are verificated via simulation.
关键词： diversity,common cause failures,stress-strength model,dependability
更新于2025-09-23 15:23:52
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Air-kerma strength determination of a new directional <sup>103</sup> Pd source
摘要： Purpose: A new directional 103Pd planar source array called a CivaSheet? has been developed by CivaTech Oncology, Inc., for potential use in low-dose-rate (LDR) brachytherapy treatments. The array consists of multiple individual polymer capsules called CivaDots, containing 103Pd and a gold shield that attenuates the radiation on one side, thus defining a hot and cold side. This novel source requires new methods to establish a source strength metric. The presence of gold material in such close proximity to the active 103Pd region causes the source spectrum to be significantly different than the energy spectra of seeds normally used in LDR brachytherapy treatments. In this investigation, the authors perform air-kerma strength (SK) measurements, develop new correction factors for these measurements based on an experimentally verified energy spectrum, and test the robustness of transferring SK to a well-type ionization chamber. Methods: SK measurements were performed with the variable-aperture free-air chamber (VAFAC) at the University of Wisconsin Medical Radiation Research Center. Subsequent measurements were then performed in a well-type ionization chamber. To realize the quantity SK from a directional source with gold material present, new methods and correction factors were considered. Updated correction factors were calculated using the MCNP6 Monte Carlo code in order to determine SK with the presence of gold fluorescent energy lines. In addition to SK measurements, a low-energy high-purity germanium (HPGe) detector was used to experimentally verify the calculated spectrum, a sodium iodide (NaI) scintillating counter was used to verify the azimuthal and polar anisotropy, and a well-type ionization chamber was used to test the feasibility of disseminating SK values for a directional source within a cylindrically symmetric measurement volume. Results: The UW VAFAC was successfully used to measure the SK of four CivaDots with reproducibilities within 0.3%. Monte Carlo methods were used to calculate the UW VAFAC correction factors and the calculated spectrum emitted from a CivaDot was experimentally verified with HPGe detector measurements. The well-type ionization chamber showed minimal variation in response (<1.5%) as a function of source positioning angle, indicating that an American Association of Physicists in Medicine (AAPM) Accredited Dosimetry Calibration Laboratory calibrated well chamber would be a suitable device to transfer an SK-based calibration to a clinical user. SK per well-chamber ionization current ratios were consistent among the four dots measured. Additionally, the measurements and predictions of anisotropy show uniform emission within the solid angle of the VAFAC, which demonstrates the robustness of the SK measurement approach. Conclusions: This characterization of a new 103Pd directional brachytherapy source helps to establish calibration methods that could ultimately be used in the well-established AAPM Task Group 43 formalism. Monte Carlo methods accurately predict the changes in the energy spectrum caused by the fluorescent x-rays produced in the gold shield.
关键词： TG43,directional sources,dosimetry,air-kerma strength,brachytherapy
更新于2025-09-23 15:22:29
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Examination of dielectric strength of thin Parylene C films under various conditions
摘要： The breakdown voltage of the biocompatible polymer Parylene C was determined after storage in 60°C saline solution and treatment by autoclave. It occurred that both, storage at 60°C in saline solution and autoclaving, lead to distinct decrease of dielectric strength by approximately 50%.
关键词： Parylene C,dielectric strength,insulation,encapsulation,implant
更新于2025-09-23 15:22:29
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Spin-orbit interaction of Tm3+ - ground level and crystal field strength
摘要： The ground level 3H6 of Tm3+ ions in a number of crystals has been examined through the matrix elements of spin – orbit interaction. The latter have been determined comparable with the separation between 3H6 and the first excited level 3F4. The normalized ratios of spin – orbit interactions relative to the free ion value of Tm IV as a function of the scalar crystal field parameter Nv have been found to vary analogous to the nephelauxetic effect. The relationships between maximum splitting of 3H6, spin-orbit coupling constant, crystal-field parameters and the Nv have been also studied for the presented 42 stoichiometric or doped crystals containing Tm3+. The compounds include halogenides, organic complexes, oxides, oxohalides, and semiconductors.
关键词： Thulium (3+),Crystal field strength,Spin-orbit interaction,Ground level
更新于2025-09-23 15:22:29
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Hybrid TDOA/RSS based localization for visible light systems
摘要： In a visible light positioning (VLP) system, a receiver can estimate its location based on signals transmitted by light emitting diodes (LEDs). In this manuscript, we investigate a quasi-synchronous VLP system, in which the LED transmitters are synchronous among themselves but are not synchronized with the receiver. In quasi-synchronous VLP systems, position estimation can be performed by utilizing time difference of arrival (TDOA) information together with channel attenuation information, leading to a hybrid localization system. To specify accuracy limits for quasi-synchronous VLP systems, the Cramér–Rao lower bound (CRLB) on position estimation is derived in a generic three-dimensional scenario. Then, a direct positioning approach is adopted to obtain the maximum likelihood (ML) position estimator based directly on received signals from LED transmitters. In addition, a two-step position estimator is proposed, where TDOA and received signal strength (RSS) estimates are obtained in the first step and the position estimation is performed, based on the TDOA and RSS estimates, in the second step. The performance of the two-step positioning technique is shown to converge to that of direct positioning at high signal-to-noise ratios based on asymptotic properties of ML estimation. Finally, CRLBs and performance of the proposed positioning techniques are investigated through simulations.
关键词： Received signal strength (RSS),Estimation,Visible light,Localization,Time difference of arrival (TDOA)
更新于2025-09-23 15:22:29
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Efficacy of phototherapy with different conventional surface treatments on adhesive quality of lithium disilicate ceramics
摘要： Aim: The aim of the present study was to evaluate shear bond strength (SBS) of LDC and resin composite in combination with phototherapy and different ceramic surface treatments. Materials and Method: Forty Lithium Disilicate Glass Ceramic (LDC) disks measuring (4x4x9mm) were fabricated. The specimens were randomly divided into four groups (n=10 each) according to the surface treatment. Group 1 HF+ Silane (Control); Group 2 HF+ Ultrasonic bath + Silane; Group 3 SECP (Self etch ceramic primer) and Group 4 phototherapy (Er, Cr: YSGG) + Silane. On each ceramic disk a resin build-up was done. For SBS the specimens were subjected to increasing load with a transversal velocity of 1ml/min on a universal testing machine on a ceramic resin interface. Failure mode was evaluated using digital microscope. The failure modes were divided into adhesive, cohesive and admixed interface. Data through bond strength testing was tabulated using statistical program for social science (SPSS). Means and standard deviations were compared using analysis of variance and Tukey's post hoc test (p<0.05) Results: The maximum and minimum bond strength was observed in group 2 [19.58(1.011)] and group 1 [17.14(1.122)] respectively. The bond strength among experimental group 1 [17.14 (1.122)] and group 4 [17.48(1.145)] were found to be comparable. Specimens in Group 2 displayed significantly higher bond strength among all experimental groups. Commonly adhesive failure mode was observed in the present study, with an incidence of 60%, 100% and 70% in groups 1,2 and 3 correspondingly Conclusion: Phototherapy using laser at frequency 30Hz and 4.5 W can be used as a surface conditioner for LDC alternate to HF acid. Conditioning of LDC using Self-etch ceramic primer showed better SBS outcomes as compared to phototherapy (Er, Cr: YSGG laser).
关键词： bond strength,microleakage,Phototherapy,lithium disilicate ceramics
更新于2025-09-23 15:22:29
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Strain Monitoring on PHC Pipe Piles Based on Fiber Bragg Grating Sensors
摘要： Fiber Bragg grating (FBG) sensors emerged as a relatively new strain-sensing technology for civil engineering applications. This study presents a field test to assess the feasibility of FBG sensors in monitoring the strain profile of prestressed high-strength concrete (PHC) pipe piles during installation. Two open-ended PHC pipe piles were instrumented with FBG sensors and then driven into the ground using a hydraulic jacking machine. To measure the strain profile along the test piles, nine FBG sensors were arranged in a single optical fiber and then mounted on one pile at the opposite side to monitor the strain at different levels as a function of wavelength shift. The procedure for installing the FBG sensors along the PHC pipe piles is introduced first. Next, the distribution of the axial forces and average side shear stresses that were evaluated from the strain measurements of the FBG sensors are discussed. The field test results indicate that the FBG sensor system was suitable for monitoring the strain state of PHC pipe piles during installation. The axial forces and side shear stresses along the test piles were influenced significantly by the penetration depth and the local soil resistance.
关键词： Fiber Bragg grating (FBG) technology,Jacking method,Strain monitoring,Prestressed high-strength concrete (PHC) pipe pile
更新于2025-09-23 15:22:29