Performance Degradation Rate Research Articles

Research on a new type of ureteral stent material Zn-2Cu-0.5Fe-xMn with controllable degradation rate

The placement of ureteral stents plays a crucial role in the treatment of ureteral strictures, therefore requiring high material performance standards. In addition, depending on the etiology of ureteral strictures, there are significant differences in the retention time of ureteral stents, thus requiring different degradation rates for the stents. Therefore, it is crucial to develop stent materials with high performance and controllable degradation rates. This study explores the potential of Zn-2Cu-0.5Fe-xMn alloy as a ureteral stent material, utilizing the antibacterial effect of copper ions, the strengthening effect of Fe element on Zn-based alloys, and the accelerated degradation effect of Mn element. The research found that with the increase in Mn content, the average grain size of the alloy and the size of (Fe, Mn)Zn13 phase gradually increased, leading to a decrease in hardness. The corrosion rate of the alloy increased with the increase in Mn content, attributed to changes in grain size and standard electrode potential differences between elements. Due to the antibacterial effects of Zn ions and Cu ions, the Zn-2Cu-0.5Fe-xMn alloy exhibits good anti-stone formation capabilities. Furthermore, the alloy also demonstrates acceptable cytotoxicity. Therefore, the Zn-2Cu-0.5Fe-xMn alloy is expected to become an important implant material in urological surgery.

Enhancing Anode Reversal Tolerance by Low-Carbon and Carbon-Free Anode Catalyst Layers for Proton Exchange Membrane Fuel Cells

Proton exchange membrane fuel cells (PEMFCs), as the main hydrogen utilization device, are considered a powerful tool for accelerating a carbon-neutral society. However, durability and cost are the two main obstacles to the commercialization of PEMFCs. Specifically, the anode reversal has been extensively studied as a severe issue that deteriorates the performance and durability of PEMFCs and leads to cell failure. Commercially, iridium oxide (IrOx) or iridium black is intensively utilized as oxygen evolution reaction catalysts to fabricate reversal tolerant anodes (RTAs) despite the slight performance loss. However, previous studies concentrated on investigating the origin or phenomena during the cell-reversal, the key factors and mechanisms affecting the anti-reversal performance, and the interaction among the anode catalyst layer components are still yet to be explored.Hence, we systematically studied the performance using three typical carbon supports with three metal contents and different metal deposition orders by experiments and model calculations. First, we synthesized Ir outside Ir/Pt/C and Pt outside Pt/It/C with uniform nanoparticle size and distribution and characterized them comprehensively. A new parameter, “relative metal coverage”, is put forward to evaluate and predict the anti-reversal ability, showing that higher relative metal coverage results in a longer reversal time and lower polarization performance degradation rate. In addition, Ir outside Ir/Pt/C shows better reversal tolerance than Pt outside Pt/It/C, which has been rarely mentioned in previous studies. Further, the experimental results show that even though the metal coverage is high, the performance degradation caused by carbon corrosion is still inevitable. On this basis, we synthesized a high specific surface area conductive oxide Ti4O7 as the anode catalyst support to eliminate the adverse effects of carbon corrosion. Previously, the initial performance of Ti4O7-supported catalyst was obstructed by the disadvantaged electrical conductivity of Ti4O7. We obtain a comparable polarization performance after optimizing the Ti4O7-supported anode catalyst layer parameters by shortening the electron transfer pathway and increasing metal coverage. Typically, the Ir@IrOx/Pt/Ti4O7-fabricated RTA with low Ir loading displays approximately ten times longer reversal time (6 hours) and two orders of magnitude lower degradation rate than a conventional carbon-supported counterpart. The degradation origin of the Ti4O7-supported anodes is also studied by postmortem characterizations, pointing to the Pt oxidation caused by the formation of TiOx thin layers on the Pt surface. These two works aim to promote the development of highly durable and reversal tolerance anode and provide a bright perspective for practical high-performance, low-degradation, and cost-friendly RTA fabrication.

Mechanical Performance Degradation of Decaying Straight Mortise and Tenon Joints: Tusi Manor, Yunnan–Tibet Region

The straight mortise and tenon joints (SMTJs) of Tusi Manor, situated in the Yunnan–Tibet region of China, tend to undergo decay. This study aims to investigate the mechanism performance degradation of SMTJs due to decay. Five full-scale SMTJs were constructed and incubated with wood-rot fungi for 0, 6, 12, 18, and 24 weeks. Cyclic loading tests were conducted to assess the damage mechanisms and extent of mechanical property degradation at these different stages of decay, supported by ABAQUS finite element simulation software. The results revealed a progressive increase in damage with prolonged decay time. Comparison between decayed and undecayed specimens showed a maximum load-bearing performance degradation rate of 5.17%, 11.83%, 17.34%, and 23.54% after 6, 12, 18, and 24 weeks of fungal incubation, respectively. The cumulative energy efficiency degradation rates were 8.38%, 9.51%, 23.13%, and 33.31%, respectively. SMTJs mechanical performance degradation is correlated with wood mechanical property degradation as a function of the S-family. Finite element simulations further indicated a reduction in tenon strength from the outer parts towards the inner parts of the structure.

Facilitated belt for ion transport by comb-shape Poly(terphenyl piperidone) carried with macrocyclic crown ether as anchor in anion exchange membrane

To ensure efficient ion transport in anion exchange membranes (AEMs) for hydrogen production, it is essential to develop efficient ion transport pathways. Utilization of intermolecular interactions induced by embedded macrocycles is an attemptable approach. Self-aggregated channels can be constructed with this force serving as a driving force for stepped-up ion transport. Herein, we present a delicate strategy to polymerize the macro crown ether in the backbone and graft flexible alkyl long chains to prepare comb-type copolymers as AEMs. The macrocycle dynamically traps ammonium ions as an anchor which accelerates the aggregation of ionic phases. The resulting AEMs show favorable membrane-forming ability and tensile strength. As the side chain length increases, the microphase-separated morphology develops well and formed ‘belt’-like channels in the poly(terphenyl piperidone)-5-bis-quaternary ammonium (PTCP-5-bisQA) membrane, exhibiting a hydroxide conductivity of 78.1 mS/cm at 80 °C. The alkaline durability of PTCP-5-bisQA AEM is explored by nuclear magnetic hydrogen spectrum (1H NMR) investigation at 80 °C for 720 h. Furthermore, the PTCP-5-bisQA based electrolyzer reaches a current density of 330 mA/cm2 at 1.85V by 1 wt% potassium hydroxide solution circulation. A life endurance observation is carried out on this electrolyzer for a 100h operation with performance degradation rate of 40.1 mV/h.

AgCl/g-C3N4/Ti-MOFs photocatalytic composite for visible light degradation of xanthate derived from mineral processing industries

Large amounts of xanthate wastewater generated from mineral beneficiation significantly threaten the ecological environment. MOF photocatalysis is considered as a promising method for the removal of xanthate that is environmentally friendly and has high efficiency. However, the defects in MOFs limit their large-scale application due to poor visible light absorption efficiency and stability in water. In this study, a novel composite material composed of g-C3N4/AgCl/Ti-MOFs was prepared, and the catalytic degradation effect of butyl xanthate solution under different catalyst ratios and reaction conditions was investigated. The results showed that the composite could still maintain excellent catalytic performance (degradation rate of 99.5% within 90 min) under xenon light and low dosage. The characterization results showed that this excellent photocatalytic performance could be attributed to the following three points: 1) The material could absorb up to 670 nm visible light absorption capacity; 2) excellent stability was achieved (86% degradation efficiency after six cycles); and 3) the Schottky junctions formed by Ag0 and other materials in the composite increased the transfer rate of e−/h+. The possible photodegradation mechanism was proposed according to UV–vis DRS and trapping experiments.

Quantitative Testing and Analysis of Non-Standard AEB Scenarios Extracted from Corner Cases

Existing testing methods for Automatic Emergency Braking (AEB) systems mostly rely on standard-based qualitative analysis of specific scenarios, with a focus on whether collisions occur. To explore scenarios beyond the standard conduct, a comprehensive testing model construction and analysis, and provide a more quantitative evaluation of AEB performance, this study extracted three typical hazardous driving scenarios from the KITTI (The Automated Driving dataset was created by the Karlsruhe Institute of Technology in Germany and the Toyota Institute of Technology in the United States) naturalistic driving dataset using kinematic data. A DME (Data Missing Estimation) scene construction method was proposed, and these scenarios were simulated and reconstructed in PRESCAN (PRESCAN is an automotive simulation software owned by Siemens, Munich, Germany). A C-AEB (Curve-Automatic Emergency Braking) testing model was developed and tested based on simulations. Finally, a BCEM (Boundary collision evaluation model) was proposed to quantitatively evaluate AEB performance. The focus of the analysis was on the identified cornering scenario A (severely failed AEB scenario). A C-AEB testing model was constructed based on the DME scene construction method for this cornering AEB failure scenario, and it was evaluated using the BCEM. The study found that the average performance degradation rate (performance degradation rate refers to the ratio of AEB performance in the current scenario compared to the standard straightaway test) of the AEB system in this cornering scenario reached 75.44%, with a maximum performance degradation rate of 89.47%. It was also discovered that the severe failure of AEB in this cornering scenario was mainly caused by sensor system perception defects and limitations of traditional AEB algorithms. This fully demonstrates the effectiveness of our testing and evaluation methodology.

Deterioration performance analysis of recycled brick concrete subjected to freezing and thawing effect

This study employed experimental and finite element modeling approaches to systematically investigate the mechanical damage mechanisms of recycled brick aggregate concrete (RAC) under freeze-thaw cycling conditions. The investigation encompassed analyses at three hierarchical levels: macroscopic, mesoscopic, and microscopic. The influence of recycled brick aggregate (RA) replacement rate and the number of freeze-thaw cycles on RAC's apparent state and mechanical performance was examined at the macroscopic level. Utilizing equipment such as electron microscopes, a comprehensive observation was conducted from mesoscopic and microscopic perspectives to elucidate the evolving patterns of the cementitious matrix, RA, and the interfacial transition zone (ITZ) within RAC during the freeze-thaw cycling process. On the one hand, more excellent internal space was inherent in RA compared to NA, enabling it to effectively accommodate the volumetric expansion resulting from water freezing. It contributed to mitigating the damage to concrete caused by freeze-thaw cycles. On the other hand, RA's rough and porous characteristics facilitated the infiltration of cement particles into its internal structure, forming a robust ITZ with RA. Concurrently, a numerical simulation of RAC's freeze-thaw cycling process was presented. This simulation generated coupled damage maps and load-deflection curves for RAC under various conditions, encompassing different levels of RA replacement rates, freeze-thaw cycle counts, and loading modes. The research results indicated that the inclusion of RA adversely affects the mechanical properties of concrete while concurrently altering the concrete's failure mode and the propagation pathways of internal cracks. Nevertheless, it was worth noting that the introduction of RA, despite diminishing the mechanical performance of concrete, effectively mitigates the rate of performance degradation during the freeze-thaw cycling process. A favorable equilibrium between freeze-thaw resistance and mechanical performance could be achieved when the replacement rate of RA for natural aggregates (NA) fell within the range of 10–30 %. By employing a finite element model to simulate the flexural performance of RAC after freeze-thaw cycles, the deviation range between the simulated and measured values fell within the range of 5.00–8.23 %. This affirmed the model's fitting solid capability and validated its effectiveness in analyzing the RAC structure's freeze-thaw-load coupled damage and lifespan prediction.

Effects of Transition Metal Elements on Ni Migration in Solid Oxide Cell Fuel Electrodes

Solid oxide cells (SOCs), both solid oxide fuel cell (SOFC) and solid oxide electrolysis cell (SOEC), have emerged and attracted more and more attentions due to its high energy conversion efficiency and fuel flexibility. However, degradation of fuel electrodes after long-term operation remains as one of the main challenges for their commercial application. Two major types of microstructure evolution, nickel (Ni) migration and Ni coarsening in Ni - yttria-stabilized zirconia (Ni-YSZ) fuel electrodes have been widely reported, which have strong impacts on both cell performance and durability. Therefore, materials-driven research has focused on developing more robust fuel electrodes with good electrocatalytic ability. Utilization of Ni alloys has immersed as a promising concept to enhance the performance and robustness of conventional Ni/YSZ. In the present study, Ni-M (M = Fe, Cu) bimetallic fuel electrodes are applied to investigate the effects of transition metal elements on the morphological evolutions under SOFC and SOEC operations. Ni-Fe, Ni-Cu and pure Ni patterned fuel electrodes are sputtered on YSZ pellets. The electrochemical performance of these Ni-M bimetallic fuel electrodes decreases compared with pure Ni fuel electrode, while the performance degradation rate of Ni-Fe fuel electrodes is smaller than others. Besides, the spreading of Ni film on YSZ surface is observed for all samples under anodic polarization and such Ni migration is suppressed by Fe doping, whereas enhanced by Cu doping. On the other hand, the adhesion is weakened at the electrode / electrolyte interface for Ni-Cu and pure Ni fuel electrodes under cathodic polarization, while good adhesion at the interface is maintained for Ni-Fe, which correlates with the smaller performance degradation rate.

Performance evaluation of TiN/Ti coatings on the aluminum alloy bipolar plates for PEM fuel cells

In this study, different coatings were applied to the bipolar plates (BPs) of proton-exchange membrane fuel cells (PEMFCs). The studied BPs materials include graphite, uncoated Al6061, Al6061 coated with single TiN (0.5 μm) layer, and different composite TiN/Ti layers. Experimental results show that the BP with TiN coating has a higher corrosion potential than those with TiN/Ti coatings, which implies TiN/Ti may have shorter operating life than TiN. The Al6061 with TiN (0.5 μm) has the lowest water contact angle among all the materials. As the Ti proportion on TiN increases, the water contact angle becomes greater, leading to better water removal ability and better fuel cell performance stability. The PEMFC performance with the Al6061 BPs coated with TiN/Ti (0.5μm/0.125 μm) is slightly better than that only coated with TiN. The appropriate thickness of Ti coating improves the PEMFC performance. The BPs made of uncoated Al6061 show the worst performance. After 480-h testing, the cell with uncoated Al6061 BPs has a significant performance degradation due to the increase of the ohmic resistance. The performance degradation rates with TiN/Ti and TiN coated BPs are slightly different, but both coatings significantly improve of the PEMFC life with Al6061 BPs.

Development, physicochemical characterization and in vitro evaluation of chitosan-fish gelatin-glycerol hydrogel membranes for wound treatment applications.

Chitosan and fish gelatin, two natural polymers, coupled with glycerol, were used to develop hydrogel membranes. The membrane properties of the prepared membranes, have been improved after heat treatment, leading to materials with ameliorated mechanical performance and lower degradation rate. Attenuated total reflectance-Fourier transform infrared spectroscopy (ATR-FTIR) and x-ray diffraction (XRD) tests were conducted to study the interactions between the biopolymers and the plasticizer. Biopolymers and plasticizer interact via secondary interactions with all plasticized materials being amorphous. Scanning electron microscopy (SEM) was used to evaluate the morphology of the materials and showed that increase in fish gelatin concentration leads to rougher surface morphologies. Dynamic mechanical analysis (DMA) measurements and tensile testing, indicated that increase in fish gelatin concentration leads to improved mechanical performance and in particular in terms of maximum strain at break as well as stress at break. Water absorption and degradation rates were found to be fully dependent on fish gelatin concentration as expected. Antimicrobial testing via the measurement of an inhibition zone, as well as ,endothelial cell attachment and proliferation results (in vitro endothelial cell colonization tests) indicate that the hydrogel membranes show promising potential for use in wound healing/care applications (protection against bacteria, providing a moist environment, etc.).

Research on thermal stress fracture performance of low-temperature asphalt concrete in castel high altitude area

The temperature in the southwest Castel highland area is relatively low, and the asphalt concrete on the road surface is in a low-temperature state all year round. Strong ultraviolet radiation will interfere with the material and cause it to fracture and damage. This paper uses a low-temperature bending test and thermal stress constrained specimen test (TSRST) to test the low-temperature performance of asphalt mixtures with different gradation and asphalt types under different ultraviolet (UV) aging conditions. Existing studies are mainly based on asphalt aging, which cannot take into account the interactions between the binder and aggregate phases during aging. This paper analyzes the correlation between test indexes after UV aging and asphalt mixture parameters, as well as the impact of UV on asphalt mixtures, and the mechanical strength prediction model was established. The results indicate that when the aging time is less than 2 months, the low-temperature performance degradation rate of the asphalt mixture first accelerates and then gradually slows down. The degree of influence of ultraviolet radiation on different graded asphalt mixtures is in descending order: stone asphalt concrete, AC 16 asphalt concrete, and AC-13 asphalt concrete. The relationship between fracture thermal stress and asphalt mixture parameters is strong. It is suggested that the appropriate equivalent outdoor aging time is 2 months in the low-temperature performance test of asphalt mixture after UV aging. At the point when there is no UV test condition, the worth acquired by the test is prescribed to consider the UV aging attenuation coefficient, and the matrix asphalt can allude to 0.84; modified asphalt has a value of 0.9. This article is of great significance for guiding the research on thermal stress fracture of low-temperature asphalt concrete in Castel high-altitude areas.

Engineered metal coverage of anode catalyst layer enhancing cell reversal tolerance for proton exchange membrane fuel cells

Anode cell reversal, which is caused by fuel starvation, poses a great threat to the durability of proton exchange membrane fuel cells. Commercially, iridium oxide or iridium is applied to boost oxygen evolution reaction, which alleviates carbon corrosion and protects the catalyst layer structure. However, the key factors that affect the anti-reversal ability and the interaction between Pt, Ir, and carbon support are still unclear. Hence, we systematically studied the performance using three typical carbon supports with three metal contents and different metal deposition orders by experiments and model calculations. A new parameter, “relative metal coverage”, is put forward to evaluate and predict the anti-reversal ability, showing higher relative metal coverage results in a longer reversal time and lower polarization performance degradation rate. Typically, only a 15.5% polarization performance loss after 1700 mins reversal time when the relative metal coverage of high metal content Ir/Pt/Super P anode is one. The results suggest that increasing relative metal coverage is a practical approach to improve reversal tolerance and provide new insights into the reversal tolerant anodes design.

Effects of Transition Metal Elements on Ni Migration in Solid Oxide Cell Fuel Electrodes

In the present study, Ni-M (M = Fe, Cu) bimetallic fuel electrodes are applied to investigate the effects of transition metal elements on nickel (Ni) migration and Ni coarsening under SOFC and SOEC operations. Ni-Fe, Ni-Cu and pure Ni patterned fuel electrodes are sputtered on YSZ pellets. The electrochemical performance of these Ni-M bimetallic fuel electrodes are lower than pure Ni fuel electrode, while the degradation rate of Ni-Fe fuel electrodes is smaller than the others. The spreading of Ni film on YSZ surface is observed for all samples under anodic polarization, and such Ni migration is suppressed by Fe doping, whereas it was enhanced by Cu doping. The adhesion between the electrode/electrolyte interface is weakened for Ni-Cu and pure Ni fuel electrodes under cathodic polarization, while good adhesion at the interface is maintained for Ni-Fe, which correlates with the smaller performance degradation rate.

Understanding the bond performance between BFRP bars and alkali-activated seawater coral aggregate concrete under marine environments

To improve the bond durability of fiber-reinforced polymer (FRP) bars with coral aggregate concrete (CAC), this study employed alkali-activated materials (AAMs) as an alternative to ordinary Portland cement for preparing alkali-activated slag CAC (AACAC) and investigated their bond behavior with FRP bars under seawater corrosion environments. The influences of various exposure times (0, 6, 9, and 12 months) and seawater environments (seawater immersion and drying-wetting cycles) on bond performance were considered. Scanning electron microscopy (SEM) and X-ray diffraction (XRD) were adopted to characterize the microstructural changes and mineralogical characteristics at the cross-section of BFRP bars and at paste matrix-aggregates interfaces of the concrete after seawater environment exposure. The tested results manifested that with the increase in exposure age, the bond strength for AACAC and CAC specimens gradually degraded, but their slope at the ascending stage of bond-stress curves (i.e., bond stiffness) tended to be enhanced. Compared with CAC specimens, AACAC specimens achieved a slightly lower rate of performance degradation. After being suffered from seawater conditions for 12 months, the compressive strength and bond strength of CAC specimens decreased by approximately 6.5% and 2.3%, respectively, while those of AACAC specimens only degraded by 2.5% and 1.5%, respectively.

Performance Evaluation and Degradation Mechanism for Proton Exchange Membrane Fuel Cell with Dual Exhaust Gas Recirculation

Fuel gas utilization and water management are particularly challenging integrated engineering problems in hydrogen–oxygen proton exchange membrane fuel cell (H2/O2 PEMFC) systems. Herein, a standardized process is adopted to evaluate the performance and investigate the degradation mechanisms of a PEMFC with dual exhaust gas recirculation. The purpose of incorporating recirculation subsystems in the fuel cell is to achieve a high fuel gas utilization rate and realize effective water management inside the stack, which consists of 3D‐printed ejectors and a customized recirculation pump. Evaluation of the electrochemical performance degradation and morphological characterization of the fuel cells under different operating strategies are performed after 50 h durability experiments. At a current density of 400 mA cm−2, the performance degradation rates of the stack decrease from 16.50% to 7.49% and 0.71% in the ejector and recirculation pump operation strategies, respectively. The results show that using exhaust gas recirculation devices (ejector/pump) in the fuel cell stack can help in effectively mitigating water flooding and chemical degradation of the membrane electrode assembly. The findings of the study provide a perspective on the exhaust gas recirculation behavior and contribute to the engineering application of H2/O2 PEMFCs.

Concurrent Static and Dynamic State Monitoring Using a Global-Local Model for the Fluid Loop in Space Stations

The fluid loop is the core of thermal control system in the space station. Owing to the complex and changeable operating conditions and long time in orbit, the fault rate and performance degradation rate increase. Therefore, it is of practical significance to timely and accurately monitor the operating state of the fluid loop. This article proposed a combined strategy of canonical variate analysis and slow feature analysis to concurrently monitor the static deviation and process dynamics for the operating state. First, multiple sensors are used to measure the data in all condition of the space station, and typical faults are simulated by fault seeding to obtain fault data. Following that, the serially correlated canonical subspaces for each normal operating condition are modeled, and they are further explored to extract slow features to establish the multiple local static monitoring models. Besides, a global model is built using differential slow features in all condition to detect the dynamic anomalies by monitoring the temporal variations. To illustrate the feasibility and efficacy, the proposed monitoring strategy is applied to monitor the test data consisting of normal samples and fault samples.

Constructing outstanding 1D/2D Co3O4/NiMnO3 heterostructure to promote the PEC efficiency for water pollution remediation

The structural design and morphology control of materials is a very attractive topic because the structure and morphology of materials usually play a key role for their performance and application. In this work, we report a facile two-step hydrothermal process for construction of the binary composite oxide system (i.e., 1D/2D Co3O4/NiMnO3 core-shell heterostructure) based on Ostwald ripening effect. Interestingly, Co3O4 nanowire will expand only when it is fully covered with NiMnO3 nanosheets to form a core-shell structure in sequential hydrothermal process. In binary composite oxide system, the formation of continuous and uniform interface between core (Co3O4) and shell (NiMnO3) based on Ostwald ripening effect is the key factor in the heterogeneous nucleation process, which can be proved by the homogeneous diffusion of Co element in the Ti/Co3O4-NiMnO3 sample. As a result, the optimized Ti/Co3O4-NiMnO3-1.5 exhibited superior PEC performance (degradation rates are ∼ 91.2% for 120 min and 80.5% after 5 cycles) for degrading reactive brilliant blue KN-R solution, which can be attributed to the construction of the hollow Co3O4/NiMnO3 core-shell heterostructure. Furthermore, the identification experiments of active species showed that the h+ and •O2- radicals are the dominant reactive species, indicating the induced charge transfer is based on the type II semiconductor heterostructure.

A biopolymer functionalized two-dimensional WS2@TiO2 nanocomposite for in vitro biomedical and photocatalytic applications: facile synthesis and characterization.

Organic dyes and microorganisms in industrial wastewater have harmed both the environment and human health. In this present study, the in vitro biological and photocatalytic properties of a synthesized biogenic chitosan functionalized WS2@TiO2 hybrid nanocomposite (NC) are investigated. The chitosan-functionalized WS2@TiO2 hybrid nanocomposite (NC) was synthesized hydrothermally. Its microstructure and compositional properties were studied. The antibacterial activity against Staphylococcus aureus, and Bacillus subtilis (Gram-positive) and Klebsiella pneumoniae, and Escherichia coli (Gram-negative) was evaluated. The NC exhibits the highest antibacterial activity against K. pneumoniae at bacterial inhibition zones of 27 mm. It also showed remarkable anticancer effects in MCF-7 cells (cell inhibition of 74% at 100 μg mL-1). The biocompatibility of the composite was tested against the Vero (kidney epithelial) cell line. The results suggest that the NC had no obvious cytotoxicity. Also, the NC showed good photocatalytic performance (degradation rate of 89.43% at 150 min; K = 0.0175 min-1). The results suggest that chitosan functionalized WS2@TiO2 NCs are a potential candidate for biological and environmental applications.

Long-term examinations up to 20 years of performance ratio and degradation rate of different-type photovoltaic modules at central part of Japan

Performance ratio and degradation rate of various-type silicon-based photovoltaic modules, which are multi-crystalline silicon, amorphous silicon, amorphous silicon/multi-crystalline silicon tandem, and amorphous silicon/amorphous silicon germanium/amorphous silicon germanium three-stack, were investigated after long exposure period up to about 20 years from 2000 to 2020 at outdoor site in Shiga-prefecture, Japan. Moreover, meteorological elements such as ambient temperature, and solar irradiance at outdoor location were investigated for approximately 20 years. Outdoor spectral distribution was observed in a year. It is disclosed that monthly performance ratio of multi-crystalline silicon module is inversely proportional to ambient temperature, whereas that of the amorphous silicon and tandem modules is positively proportional to ambient temperature. Degradation rate of the amorphous silicon module is the highest (3.776 %/year), and that of the tandem module is the second highest (1.338 %/year) of all silicon-based silicon modules after light exposure in the first period of the installation of the modules (≤10 years), implying performance ratio of amorphous silicon and tandem modules are more decreased than other type (multi-crystalline silicon and three-stack) modules. With longer years of the installation up to 20 years, degradation rate of each type of the modules is further decreased, suggesting that silicon-based modules become more stable after longer light exposure time.

Analysis of Heat Source System Degradation Due to Aging and Evaluation of Its Effect on Energy Consumption

The performance of air conditioning systems deteriorate due to the natural aging and wear caused by operating the devices. This is termed “aging degradation,” and it results from a lack of appropriate maintenance which accelerates the degree of performance degradation. The performance degradation of an air conditioning system can cause problems such as increased energy consumption, deteriorated indoor heating environment, and shortened lifespan of air conditioning equipment. To prevent such problems, it is important to establish a long-term maintenance plan to recover degraded performance, such as predicting an appropriate maintenance time by identifying the real-time performance degradation rate based on a system’s operation data. In this study, the performance degradation rate, according to the operating time, was estimated using long-term operation data for devices constituting a heat source system, and the effect of performance degradation of the heat source system’s operation and energy consumption was reviewed using a simulation. The performance degradation rate of the target device was estimated by analyzing the variation trend of the calibration coefficient, which was calculated when the initial performance prediction model was calibrated through operating data. Using this approach, it was confirmed that the annual performance degradation rate was 1.0–1.4% for the heat source equipment, 0.4–1.2% for the cooling towers, and 0.8–1.3% for the pumps. In addition, a heat source system energy simulation calculated the 15-year performance degradation of the heat source equipment to be 34–52% and 7–19% for both the cooling towers and pumps. Due to the equipment performance deterioration, the number of operating heat source equipment and cooling tower fans, and the pump flow rate gradually increased every year, thus accelerating the performance deterioration even further. As a result, energy consumption in the 15th year increased by approximately 41% compared with the initial energy consumption.