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Visualization of the pulp chamber roof and residual dentin thickness by spectral-domain optical coherence tomography in vitro
摘要： The aim of this study was to evaluate the ability of spectral-domain optical coherence tomography (SD-OCT) to display the roof of the pulp chamber and to estimate the residual dentin thickness (RDT) of the pulp complex. The roots of 20 extracted human molars were embedded in epoxy resin, and crowns were longitudinally sectioned in the mesial-distal direction, exposing the pulp chamber. The coronal part of the crown was removed up to an RDT to the pulp chamber roof of 2 mm. Samples were imaged by SD-OCT from coronal view and by light microscopy (LM) in the sagittal plane. Using a microtome, dentin was subsequently removed in four levels from the occlusal aspect in steps of 250 μm. At each level, RDT was documented and measured by both methods. The data were compared (Spearman’s rho correlation coefficient, Wilcoxon signed-rank test). Using OCT, the roof of the pulp chamber was first displayed at a maximum RDT of 1.94 mm. The minimal RDT that could be imaged by OCT was 0.06 mm. Values from both methods were strongly correlated (r, 0.83–0.95; pi ≤ 0.05) and differed significantly for large RDTs (dentin levels 1, 2; pi < 0.05) but not for small RDTs (levels 3, 4; pi ≥ 0.226). The roof of the dental pulp chamber could be already visualized by SD-OCT with a RDT of 1.94 mm. Therefore, the method could be a useful diagnostic tool during the preparation of deep dentin cavities and might help to preserve the integrity of the pulp chamber.
关键词： Pulp protection,Residual dentin thickness,OCT,Dental pulp,Deep dentin cavities,Diagnosis
更新于2025-09-10 09:29:36
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Enhanced photocathodic protection performance of Fe2O3/TiO2 heterojunction for carbon steel under simulated solar light
摘要： Titanium dioxide nano array (TNAs) was successfully modi?ed with Fe2O3 (FTNAs) to enhance the photocathodic protection performance for carbon steel. Fe2O3 as a sensitizer captures large quantities of light photons, resulting in a strong light harvest capability of FTNAs. Meanwhile, the bandgap of FTNAs decreased to 2.26 eV, and the photo-generated current densities were 90 and 400 mA cm?2 for TNAs and FTNAs under simulated solar light illumination, respectively. The narrowed bandgap and the sensitive photoelectric response together contribute to a good photocathodic protection performance of FTNAs, which was con?rmed by the electrochemical impedance spectroscopy and electrochemical noise.
关键词： Photocathodic protection,Titanium,Electrochemistry,Carbon steel,Fe2O3
更新于2025-09-10 09:29:36
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[IEEE 2018 12th International Congress on Artificial Materials for Novel Wave Phenomena (Metamaterials) - Espoo, Finland (2018.8.27-2018.9.1)] 2018 12th International Congress on Artificial Materials for Novel Wave Phenomena (Metamaterials) - Group theoretical route to weakly and strongly protected surface states in 2D and 3D photonic crystals
摘要： Topologically protected surface states in photonic systems, with unique properties such as unidirectional propagation and light con?nement insensitive to thermal or fabrication imperfections, have attracted immense attention over the past ten years. We introduce the notion of weak protection where a topological invariant predicts the existence of surface states in the photonic bulk gap, and strong protection which instead corresponds to the number of glueing points of a surface band with the bulk edges. While strong protection is desired for many key applications such as topologically protected loss-free cavities to boost non-linear interactions, it requires optical reciprocity breaking in two dimensions. We here provide a group theoretical recipe to design weakly protected states on purely dielectric metasurfaces, and genuinely strongly protected states in fully connected 3D photonic crystals. Both design principles can be readily realized by current direct manufacturing techniques, such as electron beam lithography and direct laser writing, respectively.
关键词： topologically protected surface states,strong protection,photonic crystals,group theory,weak protection
更新于2025-09-09 09:28:46
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GaAs MMIC Low Noise Amplifier With Integrated High-Power Absorptive Receive Protection Switch
摘要： This letter reports a GaAs monolithic microwave integrated circuit (MMIC) low noise amplifier (LNA) with integrated high-power absorptive receive protection switch realized using 0.13-μm GaAs pHEMT process. On-the-chip current distributed, resonant shunt FET switch configuration is employed for higher power handling. FET stacking technique is used to reduce the effective noise figure (NF). A two-stage LNA with integrated high power switch, forming each arm in a balanced configuration is employed to realize a monolithic LNA with integrated absorptive receive protection switch. This novel MMIC provides protection up to 20-W continuous wave and 2.9-dB NF, a gain of 20 dB over 9.3–9.9 GHz.
关键词： MMIC,integrated circuit,receive,current distribution,protection switch,monolithic microwave,Balanced configuration
更新于2025-09-09 09:28:46
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Preparation and protection of ZnS surface sub-wavelength structure for infrared window
摘要： Zinc sulfide (ZnS) is one of the most important far-infrared optical candidate materials. However, it is indispensable for ZnS to improve its antireflection and protection especially under harsh environments. Compared with conventional surface antireflective films, surface sub-wavelength structures (SWSs) have some unique advantages. In this paper, dewetting nickel dots as etching mask on ZnS substrates were obtained by thermal annealing of as-sputtered Ni films on the intermediate layers of as-sputtered silicon films. ZnS SWSs were then prepared by inductively coupled plasma (ICP) etching. Finally, HfO2 films were deposited on ZnS SWSs by atomic layer deposition. The influences of SWSs and ALD-derived HfO2 films on the transmittance and protection of ZnS were both investigated. The experimental results show that ZnS SWSs can increase both far-infrared transmittance and surface hydrophobicity. Meanwhile, ALD-derived HfO2 films can provide good protection. Compared with bare ZnS, HfO2-coated ZnS with double-sided SWS exhibits average transmittance of 79.2% other than initial 69.1% in 8–12 μm, better hydrophobicity with the wetting angle of 119.7°, and higher composite nano-hardness increased from 25.00 to 38.68 GPa. ALD derived HfO2 films on ZnS surface sub-wavelength structures have excellent application prospective for infrared optical windows.
关键词： Subwavelength structure,Antireflection,Infrared window,ZnS,Protection
更新于2025-09-09 09:28:46
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Infrared thermography camera protection in dairy farming management
摘要： Infrared thermography as a non-invasive contactless method of temperature distribution is ideal for various types of analyses. Thermal cameras have some protection against direct sprays of water and dust but no deposit on a camera is allowed. Educated camera operators often find themselves in situations where they have to conduct an analysis during which the equipment is exposed to unforeseen working conditions. One such occasion is dairy farming management. Analyzing dairy cows with a thermal camera exposes expensive equipment to faeces and urine. Camera protection is normally carried out by the usage of a thermal window, protective lens or special housing. One of the materials used in lens protection manufacturing is polyethylene used to make plastic bags. The paper elaborates on camera protection in order to support the usage of a plastic bag for camera protection when in unexpected circumstances. Two experiments were performed under controlled conditions and one in real conditions on a dairy farm with and without the usage of a plastic bag. The impact of the bag and its thickness on the results of thermographic analysis of a homogeneous radiation source at ambient temperature did not provide desired information due to thermal equilibrium. The setup analysis with a heat source that have the same temperature difference as a real cow in the farm has shown the influence of bag thickness as well as a different setup on the camera. The importance of a bag being well stretched over the camera lens in order to get homogeneous and minimal influence on the final measurement results was emphasized prior to the final shooting in the farm condition. In the dairy cow analysis, when the plastic bag was mounted over the camera, the temperature difference was observed. It was shown that the difference increases alongside with the increase of the observed object temperature. The plastic bag reduces the registered cow apparent temperature but similarly raises the ambient temperature.
关键词： Infrared thermography,Farm,Dairy cow,Equipment protection,Plastic bag
更新于2025-09-09 09:28:46
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A UEP Method for Imaging Low-Orbit Satellites Based on CCSDS Recommendations
摘要： Remote sensing satellites allow continuous information acquisition from large areas of the earth and have been intensively applied in a number of applications, from agriculture to defense. A major challenge in remote sensing is that satellite communication systems present bandwidth restrictions and several issues typical of time-variant channels, which justifies the need for signal coding techniques. In that sense, this letter proposes an unequal error protection method for aerospace applications using the recommendations for source and channel coding created by the Consultative Committee for Space Data System (CCSDS) as frameworks. The proposed method makes use of the CCSDS-recommended convolutional code to ensure a channel coding step as low complex as possible, which allows implementation in a wide range of embedded platforms. This letter exploits the natural data division delivered by the compressor to unequally protect the information. The proposed method, which relies on a multiobjective optimization problem, allows one to find rate arrangements that minimize the distortion of the received image for a given value of an average coding rate within a granular range. The system performance is evaluated over an additive white Gaussian noise channel model. The obtained results show that the proposed method presents several advantages over an equal error protection strategy, and paves the way for scenarios with stringent energy and bandwidth constraints.
关键词： satellite communication,joint source–channel coding,unequal error protection (UEP),Image coding
更新于2025-09-09 09:28:46
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Stone/Coating Interaction and Durability of Si-Based Photocatalytic Nanocomposites Applied to Porous Lithotypes
摘要： The use of hybrid nanocoatings for the protection of natural stones has received increasing attention over the last years. However, the interaction of these materials with stones and, in particular, its modification resulting from the blending of nanoparticles and matrices, are yet little explored. In this work, the interaction of two nanocomposite coatings (based on alkylalkoxysilane matrices and TiO2 nanoparticles in water and 2-propanol) with two different porous stones is examined in detail by comparing their absorption behaviour and protection performance with those of the respective TiO2-free matrices. It is shown that the protective effectiveness of both matrices is not negatively affected by the presence of TiO2, as the desired water barrier effect is retained, while a significant photocatalytic activity is achieved. The addition of titania leads to a partial aggregation of the water-based matrix and accordingly reduces the product penetration into stones. On the positive side, a chemical interaction between titania and this matrix is observed, probably resulting in a greater stability of nanoparticles inside the protective coating. Moreover, although an effect of TiO2 on the chemical stability of matrices is observed upon UV light exposure, the protective performance of coatings is substantially maintained after ageing, while the interaction between matrices and nanoparticles results in a good retention of the latter upon in-lab simulated rain wash-out.
关键词： UV ageing,stone protection,water-repellency,photo-oxidative degradation,durability,artificial rain,photocatalysis,TiO2 nanoparticles,alkylalkoxysilane
更新于2025-09-09 09:28:46
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Regioisomeric synthesis of chlorin-e6 dimethyl esters and their optical properties
摘要： Chlorin-e6 dimethyl esters possessing a single carboxy group at the 13-, 151-, or 172-position were prepared by chemically modifying chlorophyll-a. These three synthetic regioisomers were fully characterized by their mass, NMR, and visible absorption spectra. Their molecular structures were unambiguously identified by the specific 1H–13C correlation at the 13-, 15-, and/or 17-substituents in their respective HMBC spectra. Methyl esterification of 13/151-COOH and hydrolysis of 13/151-COOMe affected small shifts of the Qy absorption and fluorescence emission maxima in a diluted CH2Cl2 solution, while no substitution effect of 172-COOH/Me was observed.
关键词： fluorescence emission,ester protection,Qy absorption,retro-Dieckmann condensation,chlorophyll-a derivative
更新于2025-09-09 09:28:46
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Evaluation of radiation protection conditions in intraoral radiology
摘要： Introduction: The dental radiology represents about 20% of human exposure to radiation in radio diagnostic. Although the doses practiced in intraoral dentistry are considered low, they should not be ignored due to the volume of the performed procedures. This study presents the radiation protection conditions for intraoral radiology in Curitiba - PR. Methods: Data was collected through a quantitative field research of a descriptive nature during the period between September of 2013 and December of 2014. The survey sample consisted of 97 dentists and 130 intraoral equipments. The data related to the equipments was collected using structured questions and quality control evaluations. The evaluations of the entrance skin dose, the size of the radiation field and the total filtration were performed with dosimetry kits provided and evaluated by IRD/CNEN. The exposure time and voltage were measured using noninvasive detectors. The occupational dose was verified by thermoluminescent dosimeters. The existence of personal protection equipment, the type of image processing and knowledge of dentists about radiation protection were verified through the application of a questionnaire. Results: Among the survey’s results, it is important to emphasize that 90% of the evaluated equipments do not meet all the requirements of the Brazilian radiation protection standards. Conclusion: The lack of knowledge about radiation protection, the poor operating conditions of the equipments, and the image processing through visual method are mainly responsible for the unnecessary exposure of patients to ionizing radiation.
关键词： Radiation protection,Intraoral radiology,Quality control in radiology
更新于2025-09-09 09:28:46