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Simple, Rapid, and Sensitive Determination of Thiols by Liquid Chromatography with Fluorescence Detection
摘要： Thiol compounds are important for protecting cells from oxidative stress. One common method of quantifying thiols is liquid chromatographic separation with fluorescence detection of their derivatives. The pH and the concentration of tris (2-carboxyethyl) phosphine hydrochloride in the reaction medium were shown to have significant effects on the fluorescence intensity of five thiol compounds: cysteine, glutathione, and three phytochelatins. The optimal pH range for derivatization, as indicated by the maximum fluorescence intensities, was 7.75–8.0 for all of the evaluated thiols. The thiol derivative fluorescence increased and then decreased with the tris (2-carboxyethyl) phosphine hydrochloride concentration. In particular, the fluorescence intensities of all of the derivatives decreased by 96.5–99.9% when tris (2-carboxyethyl) phosphine hydrochloride levels were increased from 0.1 to 1 mmol L?1. We attributed these changes to preferential interactions between tris (2-carboxyethyl) phosphine hydrochloride and the thiol-specific fluorophore, monobromobimane. We describe herein a method, based on our optimized solution pH and tris (2-carboxyethyl) phosphine hydrochloride concentration, that is rapid (12 min) and boasts excellent recovery (91.3–102%), sensitivity (limit of detections, 17.8–75.2 pmol L?1) and precision (relative standard deviation values ≤1.03%) for the quantification of these thiol compounds in microalgal samples.
关键词： tris (2-carboxyethyl) phosphine hydrochloride,High-performance liquid chromatography (HPLC),thiol compounds,monobromobimane
更新于2025-09-23 15:22:29
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Solar air collector performance in transient operation under radiative regimes with different levels of stability
摘要： The first objective of this paper is to prove that for the same amount of incident solar irradiation, the amount of useful heat provided by a solar air collector is different during time intervals with stable and unstable radiative regimes, respectively. A simple one-node model is used to analyze the performance of two solar air collectors with similar surface area. One collector has a porous absorber while the other collector has an aluminum U-corrugated absorber. Quantifying the performance of solar collectors during transient operation is more involved than during steady-state operation. Specific instantaneous indicators and variability factors are defined, which show how large is, in average, the relative deviation between the instantaneous and global values of the efficiency and coefficient of performance, respectively. The second objective is to estimate variability factors for different levels of radiative regime stability. Three conclusions are stated. First, when a solar collector performs better on long term than another collector, this is true for all radiative regimes. Second, the instantaneous performance indicators depend on the radiative regime, operation duration and design parameters. Third, the variability factors are smaller (in absolute value) in case of the stable radiative regime than for the unstable radiative regimes. Experimental data confirm that the usual global indicators may be used with reasonable accuracy in case of stable radiative regimes but they should be complemented with variability factors during unstable radiative regimes.
关键词： Transient operation,Solar air collector,Performance indicators
更新于2025-09-23 15:21:21
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Experimental Study on the Cogeneration Performance of Roll-bond-PVT Heat Pump System with Single Stage Compression During Summer
摘要： Photovoltaic thermal (PVT) heat pump technology refers to the integration of photovoltaic and solar heat pump, representing the deep exploitation and utilization of solar energy. In this paper, roll-bond-PVT heat pump (RB-PVTHP) system with single stage compression is proposed and investigated experimentally. The roll-bond-PVT (RB-PVT) unit is introduced in detail which is combined with the photovoltaic module and single-sided roll-bond evaporation heat exchanger laminating together. The designed experimental system consists of 4 pieces of RB-PVT units, 1HP heat pump unit and 150L heat storage tank, which is also equipped with various monitoring sensors to explore the system operating characteristics. Then the performance evaluation method of the unit and system is proposed. The experimental investigation on the cogeneration performance of the system in northern China during summer is carried out simultaneously, in terms of the thermal efficiency, electrical efficiency, thermal-based overall efficiency of the unit and heating COP of the system. The operating characteristics monitoring results show that the system works in a long-term stable condition during the daytime with considerable cogeneration performance. The detailed performance parameters have been given in this paper. This study demonstrates that the RB-PVTHP system has the large-scale practically feasible application value in northern China.
关键词： Single-sided roll-bond evaporator,PVT,Cogeneration performance evaluation,Roll-bond-PVT heat pump
更新于2025-09-23 15:21:21
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A Novel Multi-objective Dynamic Programming Optimization Method: Performance Management of a Solar Thermal Power Plant as a Case Study
摘要： Due to the intermittent nature of solar irradiance, solar power plants are usually equipped with energy storage systems. Suitable charge and discharge management of the storage systems can considerably help increase the reliability and profitability of the solar systems. In this regard, various optimization approaches, with their own strengths and limitations, have been employed by literature. Dynamic Programming (DP) is one of the fittest approaches for the wide range of engineering problems which exhibit the properties of overlapping sub-problems. DP is a simple, gradient-free, efficient, and deterministic optimization method that guarantees the optimal solution. However, this method has not been developed for multi-objective problems. This study develops a multi-objective DP method and employs it for the performance management of a solar power plant equipped with thermal energy storage system. “Daily electricity generation” and “daily revenue obtained from selling electricity” are considered to be the objective functions. The superiority of the developed method is shown through a comparison with one of the most commonly used multi-objective optimization approaches, NSGA-II. This comparison indicates that the multi-objective DP attains 3.0%- 7.5% greater values of electricity generation and 3.1%-12.6% higher values of revenue than NSGA-II, for the different levels of solar radiation.
关键词： Thermal Energy Storage System,Optimal Performance,Solar Thermal Power Plant,Multi-objective Dynamic Programming method
更新于2025-09-23 15:21:21
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Facile synthesis of SiO2@TiO2 hybrid NPs with improved photocatalytic performance
摘要： SiO2@TiO2 hybrid nanoparticles (NPs) were successfully prepared via a simple solvothermal approach using tetrabutyl titanate (Ti(OBu)4) as a titanium source. The morphology and crystal structure of the sample were characterised by scanning electron microscope, transmission electron microscope, and X-ray diffraction. The photocatalytic properties of SiO2@TiO2 hybrid NPs were also investigated in detail. The results showed that the layers of TiO2 NPs have been successfully coated onto the uniform silica sphere and transformed into anatase after calcination at 500°C. In addition, the photocatalytic activity of the as-obtained product was higher than that of the commercial P25-TiO2. The method for producing hybrid NPs has potential applications in building various types of hybrid NPs.
关键词： SiO2@TiO2 hybrid nanoparticles,photocatalytic performance,solvothermal approach,anatase titanium dioxide
更新于2025-09-23 15:21:21
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AIP Conference Proceedings [Author(s) SolarPACES 2017: International Conference on Concentrating Solar Power and Chemical Energy Systems - Santiago, Chile (26–29 September 2017)] - Experimental evaluation of volumetric solar absorbers – Ceramic foam vs. an innovative rotary disc absorber concept
摘要： This paper presents the experimental evaluation of two volumetric solar absorber concepts. It compares the thermal performance of conventional foam absorbers with that of an innovative rotary disc absorber design. The moving absorber showed advantages regarding air temperature stability at the outlet and better operability compared to the foam absorber. Unfortunately, it is shown that the innovative rotary disc design in its present form is not competitive, neither in terms of thermal performance, nor regarding mechanical reliability and robustness. The future task is therefore to optimize the mechanical design regarding thermal fatigue, in order to obtain a robust and durable rotary absorber that can be thoroughly evaluated experimentally.
关键词： volumetric solar absorbers,ceramic foam,thermal performance,rotary disc absorber,mechanical reliability
更新于2025-09-23 15:21:21
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[IEEE IGARSS 2018 - 2018 IEEE International Geoscience and Remote Sensing Symposium - Valencia, Spain (2018.7.22-2018.7.27)] IGARSS 2018 - 2018 IEEE International Geoscience and Remote Sensing Symposium - Automated Analysis of Remotely Sensed Images Using the Unicore Workflow Management System
摘要： The progress of remote sensing technologies leads to increased supply of high-resolution image data. However, solutions for processing large volumes of data are lagging behind: desktop computers cannot cope anymore with the requirements of macro-scale remote sensing applications; therefore, parallel methods running in High-Performance Computing (HPC) environments are essential. Managing an HPC processing pipeline is non-trivial for a scientist, especially when the computing environment is heterogeneous and the set of tasks has complex dependencies. This paper proposes an end-to-end scientific workflow approach based on the UNICORE workflow management system for automating the full chain of Support Vector Machine (SVM)-based classification of remotely sensed images. The high-level nature of UNICORE workflows allows to deal with heterogeneity of HPC computing environments and offers powerful workflow operations such as needed for parameter sweeps. As a result, the remote sensing workflow of SVM-based classification becomes re-usable across different computing environments, thus increasing usability and reducing efforts for a scientist.
关键词： High-Performance Computing (HPC),Remote Sensing,Scientific Workflows,UNICORE,Support Vector Machine (SVM)
更新于2025-09-23 15:21:21
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Diagnosis of Knee Meniscal Injuries by Using Three-dimensional MRI: A Systematic Review and Meta-Analysis of Diagnostic Performance
摘要： To investigate the diagnostic performance of three-dimensional (3D) MRI for depicting meniscal injuries of the knee by using surgery as the standard of reference. A literature search was performed to identify original studies published between 1985 and 2017. Summary receiver operating characteristic curve and sensitivity analyses were performed to compare the diagnostic performance of 3D versus two-dimensional (2D) MRI for the assessment of knee meniscal injuries and to evaluate the impact of relevant covariates on the diagnostic performance for assessment of knee meniscal injuries. Of identified records, 31 studies (1743 3D knee MRI examinations) were included (23 studies also reported the results of 2D MRI). All studies before 2008 used gradient-echo (GRE) sequences, whereas all studies after 2011 used fast spin-echo (FSE) sequences. By comparing FSE and GRE sequences with 2D MRI, pooled estimate of sensitivity (90.0%; P = .2 and 90.1%; P = .2 vs 88.5%) and pooled estimate of specificity (91%; P = .3 and 89.8% vs 90.1%; P = .7) were comparable. The 3D FSE sequences demonstrated similar diagnostic performance as 3D GRE sequences, except for slightly improved sensitivity for depicting lateral meniscal injuries (FSE, 84.6%; GRE, 75%; P = .01). The specificity of 3D sequences improved when multiplanar reformatting was performed (P = .02). Both three-dimensional (3D) fast spin-echo (FSE) and 3D gradient-echo (GRE) sequences had similar diagnostic performance as two-dimensional sequences, with slight superior sensitivity of 3D FSE sequences compared with 3D GRE sequences for depicting lateral meniscal injuries of the knee.
关键词： knee,diagnostic performance,meniscal injuries,MRI,3D
更新于2025-09-23 15:21:21
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Outdoor performance of perovskite solar technology: Silicon comparison and competitive advantages at different irradiances
摘要： Perovskite solar cells have shown an impressive performance evolution during the last years. This technology has been mostly tested under laboratory conditions using small area devices. In this work, the outdoor photovoltaic performance of perovskite solar cells was evaluated under real tropical weather conditions. Specifically, two perovskite modules with active area of 17 and 50 cm2 were fabricated, encapsulated and tested. Taking a commercial silicon panel as reference, both technologies were evaluated for 500 h correlating the in-situ I-V measurements with atmospheric variables measured every minute during the light hours. To obtain the performance and the average outdoor efficiency of devices, we proposed a new adapted methodology based on the standard IEC 61853-1, showing the photovoltaic parameters performance through maps, to graphically visualize their behavior in a broad range of atmospheric conditions. Additionally, we demonstrated that the power delivery and short circuit current of both technologies correlate linearly with the atmospheric variables. Moreover, the open circuit voltage of perovskite technology exhibited a nonlinear behavior and an improved performance with temperature at high irradiance regimes. This work presents reliable information concerning perovskite solar technology performance under real outdoor operation conditions, being this crucial to identify competitive advantages of this technology and the aspects to be improved.
关键词： Temperature,power delivery,Outdoor performance,Irradiance,Perovskite solar cells,Minimodules
更新于2025-09-23 15:21:21
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Validity assessment of quantitative light-induced fluorescence-digital (QLF-D) for the dental plaque scoring system: a cross-sectional study
摘要： Background: The aim of this study was to analyze the correlation between the dental plaque indices measured using quantitative light-induced fluorescence-digital (QLF-D) and conventional clinical indices that assess gingival status. Methods: From among the patients who visited Ewha Womans University Mokdong Hospital, 33 adults in their 20s who had relatively even teeth were selected for full-mouth QLF-D imaging. The images were used to analyze the QLF-D score and the QLF-D ΔR score. As clinical indices, the gingival index (GI), bleeding on probing (BOP), probing pocket depth (PPD), and patient hygiene performance (PHP) index were measured. The correlations between the QLF-D score and QLF-D ΔR score and each clinical index were analyzed. Analyses were performed comparing the indices of maxillary and mandibular teeth, the teeth on right and left sides of the mouth, anterior and posterior teeth, and buccal and lingual surfaces of each tooth. Pearson’s correlation analysis was conducted (p < 0.05). Results: The mean full-mouth QLF-D score was highly correlated with the GI, BOP, PPD, PHP index (p < 0.01). The mean full-mouth QLF-D score showed the highest correlation with GI (r = 0.749) and the lowest correlation with PPD (r = 0.683). The correlations between the QLF-D score were higher in the mandible than in the maxilla and in the anterior teeth than in the posterior teeth, while no significant differences were seen between the buccal and lingual surfaces of tooth. Conclusions: This study concluded that the correlations between the plaque indices measured for each tooth surface area using QLF-D and the clinical indices assessed were significantly high, and it allowed objective determination of the gingival status. Therefore, the plaque index measured using QLF-D may be used as an alternative to supplement the shortcomings of conventional clinical indices for educating patients about plaque control and continued patient oral care.
关键词： Gingival index,Bleeding on probing,Quantitative light-induced fluorescence-digital,Probing pocket depth,Dental plaque,Patient hygiene performance index
更新于2025-09-23 15:21:21