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Development of a Hybrid Chitosan- and Niacinamide-Coupled ZnO Nanoparticle Composite for Sun Protection Application
摘要： Zinc oxide nanoparticles (ZnO) have long been utilized as UV-protective sunscreen components due to their high durability and lower skin irritation while maintaining capability for blocking UV rays. However, the dispersal and transparency properties of ZnO need to be enhanced in order to improve the capacity for creating effective sunscreen through control of the physiochemical properties of ZnO. In this study, chitosan or niacinamide, which are suitable functional cosmetic compounds and effective skin lightening agents, are combined with ZnO for the development of better UV-protective products. Each biocompatible coating material is individually attached on its surface after the synthesis of ZnO. The size is 70 nm using the sol-gel method. Their morphology and chemical structure are characterized by FT-IR, XRD, SEM, TEM, TGA, and zeta potential. The results indicate that approximately 50% of chitosan and 5% niacinamide were coated on the ZnO. To confirm the capacity of each surface-coated ZnO with chitosan and niacinamide as a sunscreen, we measured their transmission, reflectance, and sun protection factor (SPF) using a UV spectrophotometer and SPF. As a result, the niacinamide-coated ZnO shows remarkably lower transmission and high reflectance against UV rays than that of bare ZnO and chitosan-coated ZnO. Furthermore, niacinamide-coated ZnO exhibits great lightening effects. Consequently, these results demonstrate that niacinamide coating is highly effective for the production of sunscreen emulsions.
关键词： Zinc oxide nanoparticles,TEM,FT-IR,SEM,XRD,UV-protective sunscreen,TGA,chitosan,SPF,sol-gel method,zeta potential,niacinamide,sun protection factor
更新于2025-09-12 10:27:22
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Series arc fault detection in photovoltaic system by small‐signal impedance and noise monitoring
摘要： This paper presents a new method for the fast detection of series electrical arc (SEA) fault in a photovoltaic (PV) system, which relies on a power converter output switching waveforms as the excitation signal used to identify PV small‐signal impedance at switching frequency. In addition to the small‐signal impedance value, the proposed method extracts the high frequency noise power value caused by SEA from the PV current and uses it to indicate the presence of SEA. Both theoretical analysis and measurements performed on a commercial PV system show that SEA causes a step‐like increase in small‐signal reactance. SEA was detected in less than 10 ms during tests of the proposed algorithm. Moreover, various tests showed that there was no false tripping during transients in normal operation. Finally, the proposed algorithm was implemented and tested with a commercially available digital signal processor.
关键词： photovoltaic,protection,fault detection,grid‐tied,fire,series arc fault,impedance
更新于2025-09-12 10:27:22
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A host dTMP-bound structure of T4 phage dCMP hydroxymethylase mutant using an X-ray free electron laser
摘要： The hydroxymethylation of cytosine bases plays a vital role in the phage DNA protection system inside the host Escherichia coli. This modification is known to be catalyzed by the dCMP hydroxymethylase from bacteriophage T4 (T4dCH); structural information on the complexes with the substrate, dCMP and the co-factor, tetrahydrofolate is currently available. However, the detailed mechanism has not been understood clearly owing to a lack of structure in the complex with a reaction intermediate. We have applied the X-ray free electron laser (XFEL) technique to determine a high-resolution structure of a T4dCH D179N active site mutant. The XFEL structure was determined at room temperature and exhibited several unique features in comparison with previously determined structures. Unexpectedly, we observed a bulky electron density at the active site of the mutant that originated from the physiological host (i.e., E. coli). Mass-spectrometric analysis and a cautious interpretation of an electron density map indicated that it was a dTMP molecule. The bound dTMP mimicked the methylene intermediate from dCMP to 5′-hydroxymethy-dCMP, and a critical water molecule for the final hydroxylation was convincingly identified. Therefore, this study provides information that contributes to the understanding of hydroxymethylation.
关键词： hydroxymethylation,XFEL,dCMP hydroxymethylase,X-ray free electron laser,T4dCH,hydroxylation,cytosine bases,phage DNA protection,dTMP,Escherichia coli,bacteriophage T4,methylene intermediate
更新于2025-09-12 10:27:22
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The acute impact of local cooling versus local heating on human skin microcirculation using laser Doppler flowmetry and tissue spectrophotometry
摘要： Knowledge of thermally induced skin injury has increased, but its pathophysiology remains unclear. Although it is assumed that local cooling may protect tissue, little is known about the impact of local heating on human skin. This study aimed to evaluate acute skin perfusion dynamics following thermal stimuli in healthy human volunteers. In 54 subjects, a TSA-II-NeuroSensory Analyzer was used to induce local hypothermia (15°C and 5°C) and local hyperthermia (40°C and 45°C) at the palmar forearm of healthy volunteers. Changes in tissue microcirculation were assessed using an O2C device before and after each temperature change. Blood flow and velocity values showed a continuous decrease with decreasing skin temperature, whereas haemoglobin oxygen saturation (SO2) showed a continuous increase in superficial (2 mm) and deep layers (8 mm). With increasing skin temperature, flow, SO2 and velocity increased in the superficial and deep layers. The relative amount of haemoglobin (rHB) did not show a continuous alteration. Local cooling may protect damaged tissue due to increased SO2 (lower oxygen consumption). However, reduced blood flow and velocity in response to local cooling limit nutrient requirements and the transport of metabolites. Despite higher oxygen consumption of tissue at higher temperatures, both blood flow and SO2 increase. Thus, we hypothesize that not only hypothermia but also hyperthermia may provide tissue protection.
关键词： Hypothermia,Tissue protection,Microcirculation
更新于2025-09-12 10:27:22
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Coupling Waveguide-Based Micro-Sensors and Spectral Multivariate Analysis to Improve Spray Deposit Characterization in Agriculture
摘要： The leaf coverage surface is a key measurement of the spraying process to maximize spray efficiency. To determine leaf coverage surface, the development of optical micro-sensors that, coupled with a multivariate spectral analysis, will be able to measure the volume of the droplets deposited on their surface is proposed. Rib optical waveguides based on Ge-Se-Te chalcogenide films were manufactured and their light transmission was studied as a response to the deposition of demineralized water droplets on their surface. The measurements were performed using a dedicated spectrophotometric bench to record the transmission spectra at the output of the waveguides, before (reference) and after drop deposition, in the wavelength range between 1200 and 2000 nm. The presence of a hollow at 1450 nm in the relative transmission spectra has been recorded. This corresponds to the first overtone of the O–H stretching vibration in water. This result tends to show that the optical intensity decrease observed after droplet deposition is partly due to absorption by water of the light energy carried by the guided mode evanescent field. The probe based on Ge-Se-Te rib optical waveguides is thus sensitive throughout the whole range of volumes studied, i.e., from 0.1 to 2.5 μL. Principal Component Analysis and Partial Least Square as multivariate techniques then allowed the analysis of the statistics of the measurements and the predictive character of the transmission spectra. It confirmed the sensitivity of the measurement system to the water absorption, and the predictive model allowed the prediction of droplet volumes on an independent set of measurements, with a correlation of 66.5% and a precision of 0.39 μL.
关键词： principal component analysis (PCA),partial least squares (PLS),precision agriculture,droplet characterization,infrared spectroscopy,optical micro-sensors,crop protection
更新于2025-09-12 10:27:22
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[IEEE 2019 International Conference on Robots & Intelligent System (ICRIS) - Haikou, China (2019.6.15-2019.6.16)] 2019 International Conference on Robots & Intelligent System (ICRIS) - Research on Security Threats and Protection Strategies of Optical Fiber Communication
摘要： Natural factors, human factors and technical factors have many security threats to optical fiber communication with the improvement of informatization. The security threat of optical fiber communication is analyzed. The integration of military and civilian, the combination of field and fixed, the improvement of the equipment performance, and the establishment of standardized guarantee mechanism and operational procedures need to be strengthened is proposed to improve the protection capability of the optical fiber communication network.
关键词： Security Protection,Optical Fiber Communication,Security Threat
更新于2025-09-11 14:15:04
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[IEEE 2019 IEEE International Conference on Electron Devices and Solid-State Circuits (EDSSC) - Xi'an, China (2019.6.12-2019.6.14)] 2019 IEEE International Conference on Electron Devices and Solid-State Circuits (EDSSC) - On-Chip Excessive Heating Protection Scheme for Uncooled Micro-Bolometer Imagers
摘要： Joule heating effect of micro-bolometer sensors heats the elements rapidly during readout, and longtime heating might cause permanent damage of the detector. To solve this problem, we proposed a self-protection scheme based on an analog row select length of time detection circuitry. The protection circuit is effective for various sequential errors and improves the robustness of the whole detector. By implementing a cascaded OR-gate logic with trimmed edge delay, the row-level selection circuit layout is more regular with reduced area. To verify the proposed scheme, a 640×512 array format uncooled infrared detector with 17μm pixel pitch is designed and fabricated in 0.18μm CMOS process. Power consumption of the circuits is below 50μW and the measured protection threshold of row period is around 360μs.
关键词： self-protection,joule heating,micro-bolometer,uncooled infrared detector
更新于2025-09-11 14:15:04
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Radiation exposure during direct versus indirect image acquisition during fluoroscopy-controlled internal fixation of a hip fracture: Results of a randomized controlled trial
摘要： Background: Intra-operative image acquisition can be obtained indirectly (via verbal request to a technician) or directly (executed at the tableside, by a surgeon stepping on a foot pedal). Direct image acquisition could reduce the exposure time and thus the risk of radiation damage. The aim of this randomized controlled trial was to compare direct surgeon-controlled fluoroscopy with indirect technician-operated fluoroscopy during internal fixation of a hip fracture. Methods: From March 5, 2014 to August 19, 2015, 100 patients who had sustained a hip fracture that required internal fixation were enrolled. Patients were randomized between direct surgeon-controlled image acquisition using a foot pedal (n = 52) and indirect image acquisition by a radiology technician (n = 48). The primary outcome measure was the radiation exposure time; secondary outcome measures were the associated effective radiation dose and the dose area product. (DAP) Results: A total of 96 patients (with a median age of 84 years) were enrolled in this study. Eighty-nine (93%) patients had a pertrochanteric fracture. No statistically significant differences between direct image acquisition and indirect image acquisition were found for overall radiation time, total radiation dose or DAP for the total population. When adjusted for potential confounders, a difference in overall radiation time of 18.50 s (95% CI 2.19; 34.81, p = 0.027) was found in favour of indirect image acquisition. Conclusion: This study showed statistically significantly lower radiation duration using indirect fluoroscopy for the total population and the pertrochanteric fracture subgroup when adjusted for several confounders. No significant effect on radiation dose and DAP was found.
关键词： Radiation dosage,Radiation protection,Hip fractures,Fluoroscopy,Femoral fractures
更新于2025-09-11 14:15:04
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Nanocomposite material that protects against laser attack
摘要： An international group of researchers has produced a new biologically based optical-nanocomposite material that helps protect against strong light. The material, which consists of biologically generated elemental tellurium nanocrystals as well as a polymer, could protect electronic devices from attack by high-intensity bursts of light, such as emitted by common lasers aimed at aircraft, drones, surveillance cameras and other equipment, and could also find applications in improving the capacity of high-speed optical networking.
关键词： Nanocomposite material,tellurium nanocrystals,laser attack protection,high-speed optical networking,biologically generated
更新于2025-09-11 14:15:04
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AIP Conference Proceedings [AIP Publishing ADVANCES IN BASIC SCIENCE (ICABS 2019) - Bahal, India (7–9 February 2019)] ADVANCES IN BASIC SCIENCE (ICABS 2019) - Profit analysis of a uni-directional and non revertible 1+1 protection switching scheme in optical communication process
摘要： The present paper examines availability and profit analysis of a system comprising four optical lines out of which two are operative (working paths) and the other two are hot-standby (protection paths). Each working line has its own hot standby. On the failure of the working path, signal is received from its own protection path and the failed unit is gone under repair immediately by a repairman. If a working path and its corresponding protection path both get failed then system is said to be failed. The system is analyzed by making use of regenerative point technique. Various measures of system effectiveness as well as expression for finding the profit have been obtained.
关键词： 1+1 Protection Scheme,availability,reliability,profit analysis
更新于2025-09-11 14:15:04