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Increased UV absorption properties of natural hydroxyapatite-based sunscreen through laser ablation modification in liquid
摘要： Sunfilters based on hydroxyapatite (HAp) and iron-containing compounds (Fe2O3 and calcium iron phosphates) are of increasing interest, as they show UV absorption without generating health endanger free radicals (usually observed when other inorganic sunscreens are used). In this paper, laser ablation of solids in liquids has been applied to improve the UV absorption properties of a HAp based Fe-containing sunscreen powder derived from cod fish bones. Two different laser wavelengths were explored (532 and 1064 nm, green and infrared respectively); an improved experimental device was used, to allow a fine control of the volume of the irradiated particles. Results show an increased UV absorbance for the laser-treated powders in comparison with the untreated ones; this can be explained considering the smaller particle size and increased surface area; the higher iron concentration in the powders may also be determinant. Enhanced absorption was also observed in the near-infrared range, making the powders even more suitable for sunscreen applications. The green laser was more effective than the infrared one. Overall, laser ablation showed to be a powerful technique to control the size of the sunscreen particles and tailor their optical properties.
关键词： hydroxyapatite,Liquid laser ablation,UV protection,sunscreen
更新于2025-11-14 15:25:21
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Encapsulated Cadmium Sulfide in Silicon Dioxide Porous Shells for Enhanced Photocatalytic Sustainability and Commendable Protection of Organic Carriers
摘要： The purpose of this study is to provide a solution to two troublesome problems on photocorrosion of cadmium sulfide (CdS) and photocatalysis damage to organic carrier. An encapsulation system of CdS in silicon dioxide (SiO2) porous shell can be constructed by following strategies: polypyrrole (PPy) layer is deposited on the surface of CdS nanoparticles via chemical redox polymerization; then the resulting PPy@CdS is covered by metasilicic acid (H2SiO3) with polyethylene glycol by sol–gel process, which originates from hydrolysis of tetraethyl orthosilicate; after removing PPy interlayers by calcination, CdS@void@SiO2 yolk–porous-shell nanospheres (YSNs) are fabricated. As expected, YSN nanoarchitecture is verified by transmission electron microscopy (TEM) and Brunauer–Emmett–Teller (BET) analysis. The tailored void can be tuned by the sacrificed layers of PPy. CdS@void@SiO2 YSNs exhibit excellent photostability with a considerably low level of Cd2+ concentration at <30 ppm, which is dropped down 18 times less than ≈520 ppm of CdS. CdS@void@SiO2 YSNs show good dye removal efficiency up to 99.5%, and commendable hydrogen evolution of 126.8 μmol g?1 h?1. More interestingly, the transparent and porous SiO2 shell in the YSNs has an impressive shielding to organic carrier. Our versatile YSNs have great potential to translate CdS photocatalyst to industrial-scale application because of its stability and nondestructivity.
关键词： cadmium sulfide,photocorrosion,carrier protection,sustainable photocatalysis,yolk–porous-shell
更新于2025-11-14 15:18:02
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Projection X-ray Imaging
摘要： Recent advances in digital detector technology for medical radiography and fluoroscopy have resulted in improved workflow efficiency, operational flexibility, image quality, and diagnostic accuracy. This is attributed to the implementation of portable flat-panel x-ray detector devices able to provide real-time readout, processing, and display of medical images. As a result, digital radiography flat-panel detectors are rapidly replacing computed radiography passive detectors for projection imaging exams and image intensifier detectors for dynamic fluoroscopy exams. Advanced exam capabilities now include digital tomosynthesis and dual-energy radiography; the former is based on rapid acquisition of multiple angle-dependent image projections to synthesize tomographic slabs at selectable depths within the patient, and the latter is based on rapid back-to-back acquisition of the same anatomy at low and high x-ray energies to generate separate soft tissue and bone images. In both situations, superimposition of anatomy is reduced or eliminated, with the possibility of enhanced diagnostic confidence. Increased x-ray absorption efficiency and lower electronic noise of digital radiography detectors compared to computed radiography detectors enable equal image quality at lower patient dose; however, because of a disconnect between image appearance and radiation dose, lower patient dose is not always achieved. Education, training, and implementation of standards such as the International Electrotechnical Commission 62494-1 Digital Radiography Exposure Index are needed to ensure image quality at the lowest appropriate radiation dose. The National Council on Radiation Protection and Measurements can contribute to radiation responsibility in medical imaging by providing guidance on use of digital radiography, including recommendations for acquisition protocols and exposure index standards, for development of radiographic exam diagnostic reference levels, and for oversight of retake and reject analysis.
关键词： x rays,radiation dose,fluoroscopy,National Council on Radiation Protection and Measurements
更新于2025-09-23 15:23:52
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Ambient dose during intraoral radiography with current techniques: Part 1 conversion factor for scattered radiation using a rectangular collimator
摘要： The aim of this study was to establish a conversion factor for assessing the scattered radiation produced during intraoral radiography with a rectangular collimator in areas where the remnant beam is not present. The dose level in the remnant beam will be addressed in another study. A radiological phantom (Rando) in the upright position was exposed to radiation delivered by a Planmeca Intra X-ray unit over 9 exposure geometries (right side of a full mouth series). For each geometry, the scattered radiation dose was measured at 5 locations in the horizontal plane and 4 locations in the vertical plane in front of the patient. The measurements were corrected for background and leakage radiation. An inventory of the distributions of the different geometries with respect to their share of the total workload was created in order to assign the correct weightings of the total ambient scattered radiation for the different geometries. The weightings were used to construct a scattered radiation pattern for a representative mix of exposures. The maximum value found in this pattern was used to arrive at a safe conversion factor. The scattered ambient radiation dose was evenly distributed over the horizontal plane. The scattered ambient radiation dose ranged from 20 to 65% lower in the vertical plane. The conversion factor established for scattered ambient radiation was 0.05 μSv per mAs at 1 meter. This factor is 3-fold lower than the conversion factors reported previously.
关键词： radiation protection,dental radiography,radiation monitoring,Dental Equipment
更新于2025-09-23 15:23:52
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Ambient dose during intra-oral radiography with current techniques: Part 2 quantifying the remnant beam - an <i>in vivo</i> study
摘要： Objectives: (1) To find a safe reference transmission factor for the remnant beam to be used when assessing the remnant beam during intra-oral radiography. (2) To identify factors such as exposure type, side (left or right), gender and age that might significantly affect transmission. Methods: Measurements were performed in the remnant beam during 323 intra-oral exposures of 43 patients. The exposure parameters were 60 kV and 7 mA. These measurements were compared with values in the same setting, but without a patient present to arrive at a transmission value. Differences between types of exposure [bitewing (BW), incisor and canine (IC) periapical, premolar and molar (PM) periapical], exposure side (left or right), gender and age were statistically analysed. The reference value was based on the exposure yielding the highest transmission value, to which a safety margin of two standard deviations (SDs) was added, and then rounding up. Results: The respective mean transmission values (SD) for BW, IC and PM exposures were as follows: 1.78% (1.15%), 0.639% (0.63%) and 2.60% (0.98%). The differences between PM and IC and between BW and IC were significant (p > 0.01). The differences between exposure side, gender and age were not significant. The reference transmission value, which was calculated from the highest mean transmission percentage for PM (2.60%) plus twice the SD (0.98%) and rounding up, was 5%. Conclusions: A transmission factor of 5% could be used to assess the remnant beam during intra-oral radiography. Anterior exposures led to significantly lower transmission values than posterior exposures.
关键词： radiation protection,dental radiography,dental equipment,radiation monitoring
更新于2025-09-23 15:23:52
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Photoactive and hydrophobic nano-ZnO/poly(alkyl siloxane) coating for the protection of sandstone
摘要： Poly(alkyl siloxane) containing photoactive nano-ZnO (0.5 wt%) has been studied as a protective coating of glauconitic sandstone. Effect on visual appearance, hydrophobicity, porosity, water absorption/evaporation, and self-cleaning ability of the sandstone was measured. The results were evaluated in comparison with uncoated and poly(alkyl siloxane)-coated sandstone. Static contact angle of water reached 89° ± 3° and 128° ± 2° for poly(alkyl siloxane) and nano-ZnO/poly(alkyl siloxane) coating, respectively. Poly(alkyl siloxane) and nano-ZnO/poly(alkyl siloxane) coatings led to increased reduction in water absorption (>50%) for ≥18 h and ≥8 h, respectively, compared to the uncoated sandstone. The shorter time is compensated by self-cleaning ability: photodegradation of methylene blue on the nano-ZnO/poly(alkyl siloxane) coating after 5 h of UV irradiation was observed. This coating is a promising candidate for practical use in sandstone monuments protection.
关键词： Sandstone,ZnO,Photoactivity,Protection,Poly(alkyl siloxane),Hydrophobicity
更新于2025-09-23 15:23:52
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On the efficient optimization of unicast, anycast and multicast flows in survivable elastic optical networks
摘要： The paper investigates efficient allocation of three types of flows (unicast, anycast, multicast) in elastic optical network with dedicated path protection. We model the problem as an integer linear programming and propose efficient solution methods: greedy randomized algorithm (GRA) and column generation (CG)-based approach implemented in two versions, which differ in the method used to find a final problem solution for the selected columns. Then, we evaluate in detail methods efficiency with respect to four reference algorithms. What is more, for CG-based methods we use five different algorithms to find initial sets of columns and, by these means, evaluate how the quality of these methods influences the efficiency of CG-based approaches. The simulation results show that the proposed GRA significantly outperforms reference greedy methods and finds very good solutions (the average gap to optimal result was not higher than 13.4%). The CG-based methods allow to further improve results and obtain solutions very close to optimal ones (for the best CG-based version, the highest average gap to optimal result was 2.1%). Moreover, the results show that the traffic pattern influences the algorithms performance. The methods perform the best for scenarios with high amount of multicast volume while high anycast volume brings the most difficult problem instances. Eventually, the study reveals that the efficiency of CG-based methods depends strongly on the quality of initial columns as well as on the method used to find final solution for the selected columns.
关键词： Network optimization,Multicast traffic,Anycast traffic,Column generation technique,Elastic optical networks,Dedicated path protection
更新于2025-09-23 15:23:52
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Readjustment of abdominal computed tomography protocols in a university hospital: impact on radiation dose
摘要： Objective: To assess the reduction of estimated radiation dose in abdominal computed tomography following the implementation of new scan protocols on the basis of clinical suspicion and of adjusted images acquisition parameters. Materials and Methods: Retrospective and prospective review of reports on radiation dose from abdominal CT scans performed three months before (group A – 551 studies) and three months after (group B – 788 studies) implementation of new scan protocols proposed as a function of clinical indications. Also, the images acquisition parameters were adjusted to reduce the radiation dose at each scan phase. The groups were compared for mean number of acquisition phases, mean CTDIvol per phase, mean DLP per phase, and mean DLP per scan. Results: A significant reduction was observed for group B as regards all the analyzed aspects, as follows: 33.9%, 25.0%, 27.0% and 52.5%, respectively for number of acquisition phases, CTDIvol per phase, DLP per phase and DLP per scan (p < 0.001). Conclusion: The rational use of abdominal computed tomography scan phases based on the clinical suspicion in conjunction with the adjusted images acquisition parameters allows for a 50% reduction in the radiation dose from abdominal computed tomography scans.
关键词： Contrast media,Radiation dose,Radiation protection,Computed tomography,Abdomen
更新于2025-09-23 15:23:52
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A dsDNA-lighted fluorophore for monitoring protein-ligand interaction through binding-mediated DNA protection
摘要： Because of their important roles in cellular functions, life activities, drug screening, and disease treatment, the development of efficient methods for monitoring protein-ligand interaction is essential. In this study, inspired by our previous studies on DNA conformation-selective fluorescent indicators, we developed a new sensing platform for monitoring protein-ligand interaction and detecting protein activity based on binding-mediated DNA protection and the dsDNA-lighted fluorophore, ethyl-4-[3,6-bis(1-methyl-4-vinylpyridium iodine)-9H-carbazol-9-yl)] butanoate (EBCB). The ligand was purposefully linked to the 3?-terminal of a hairpin DNA probe to selectively bind with the target protein and protect the DNA from cleavage by exonuclease III. By virtue of EBCB’s outstanding capacity to discriminate DNA conformation, the protein-ligand interaction could be effectively monitored through a fluorescence change in EBCB. A high fluorescence signal was detected when the hairpin DNA was protected in the presence of the target protein, whereas a much lower signal was observed in the presence of nontarget proteins. Our results demonstrated that the proposed strategy had high potential, such as high selectivity and relatively high sensitivity, for monitoring protein-ligand interaction and detecting protein activity. We believe these results will pave the way for applying dsDNA-lighted fluorophore EBCB as an effective signal transducer for DNA conformation transformation-mediated biochemical sensing.
关键词： DNA protection,protein-ligand interaction,dsDNA-lighted fluorophore,fluorescence detection
更新于2025-09-23 15:23:52
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[IEEE 2018 IEEE 7th Data Driven Control and Learning Systems Conference (DDCLS) - Enshi (2018.5.25-2018.5.27)] 2018 IEEE 7th Data Driven Control and Learning Systems Conference (DDCLS) - Quantum Noise Protection via Weak Measurement for Quantum Mixed States
摘要： Due to the interaction with the environment, a quantum state is often affected by the different types of noises which becomes to one of the biggest problems for practical quantum computation. We study the possibility of protecting the mixed state of a quantum system that goes through noise by weak measurements and control operations. The aim is to find the optimal measurement strength and control operations and make the input and output states as close as possible. We show that our scheme can effectively protect arbitrary mixed states against typical types of noise sources: amplitude damping, phase damping and amplitude-phase damping. The optimal measurement and control operators are deduced in different bases of the Bloch sphere to find the best control scheme for each type of noise. The effectiveness of our control scheme is demonstrated by simulation results.
关键词： quantum system control,Open quantum system,optimal noise protection,weak measurement
更新于2025-09-23 15:23:52