Effect of sol–gel MgO spin-coating on the performance of TiO2-based dye-sensitized solar cells

This paper is concerned with the improvement of dye-sensitized solar cell (DSSC) efficiency upon MgO post-treatment of the TiO₂ electrode. A simple sol–gel technique, involving magnesium acetate as precursor, ethanol as solvent and nitric acid as stabilizer, is applied to prepare a solution of suspended MgO nanoparticles. A single drop of MgO sol at 0.1 M precursor concentration was spin-coated at 3000 rpm for 30 s onto the TiO₂ electrode and sintered at 500 K for 1 h. Dye-loading using N3-dye was applied for 6 h. An increase in the average efficiency of the DSSC from 2.5% to 3.9% (over 50% enhancement) was recorded. Measurements of the dark I–V characteristics, the open circuit voltage decays, the SEM images and the dye absorbance spectra, for both uncoated and MgO-coated electrodes were examined. The improvement of the DSSC efficiency was attributed to an upward shift of the TiO₂ flat band energy and a reduction of the rate of back-transport and recombination.     

Comparison of isolation methods using commercially available kits for obtaining extracellular vesicles from cow milk

Extracellular vesicles (EV) are important for delivering biologically active substances to facilitate cell-to-cell communication. Milk-derived EV are widely known because of their potential for immune enhancement. However, procedures for isolating milk-derived EV have not been fully established. To obtain pure milk-derived EV and accurately reveal their function, such procedures must be established. The aim of the present study was to compare methods using commercially available kits for isolating milk-derived EV. Initially, we investigated procedures to remove casein, which is the major obstacle in determining milk-derived EV purity. We separated whey using centrifugation only, acetic acid precipitation, and EDTA precipitation. Then, we isolated milk-derived EV by ultracentrifugation, membrane affinity column, size exclusion chromatography (SEC), polymer-based isolation, or phosphatidylserine-affinity isolation. Using EV count per milligram of protein, which is a good indicator of purity, we determined that acetic acid precipitation was the best method for removing casein. Using nanoparticle tracking analysis, protein quantity analysis, and RNA quantity analysis, we comprehensively compared each isolation method for its purity and yield. We found that SEC-based qEV column (Izon Science) could collect purer milk-derived EV at higher quantities. Thus, a combination of acetic acid precipitation and qEV can effectively isolate high amounts of pure extracellular vesicles from bovine milk.     

Stability enhancement of garlic essential oil using new opopanax gum/gelatin nanofibres

Opopanax gum/gelatin nanofibre was produced by the electrospinning method, and the efficiency of this new technique for encapsulation of garlic essential oil was investigated. Fourier-transform infrared spectroscopy results showed the physical and weak interactions between opopanax gum and gelatin, as well as the improvement of their thermal stability in the nanofibres structure. Incorporating 10% garlic essential oil based on biopolymer weight in nanofibres was considered the best percentage. The results confirmed the presence of garlic essential oil in the nanofibres and the improvement of its thermal stability by entrapment to the nanofibre structure. The data of analysis of the stability of garlic essential oil in the forms of free and encapsulated conditions showed that its stability increased at 25 °C from 20 days to more than 60 days. It indicated the efficiency of opopanax gum/gelatin nanofibres as an applicable coating material for stability enhancement of essential oils.     

Impact of air‐handling system exhaust failure on dissemination pattern of simulant pathogen particles in a clinical biocontainment unit

Biocontainment units (BCUs) are facilities used to care for patients with highly infectious diseases. However, there is limited guidance on BCU protocols and design. This study presents the first investigation of how HVAC (heating, ventilation, air‐conditioning) operating conditions influence the dissemination of fluorescent tracer particles released in a BCU. Test conditions included normal HVAC operation and exhaust failure resulting in loss of negative pressure. A suspension of optical brightener powder and water was nebulized to produce fluorescent particles simulating droplet nuclei (0.5‐5 μm). Airborne particle number concentrations were monitored by Instantaneous Biological Analyzers and Collectors (FLIR Systems). During normal HVAC operation, fluorescent tracer particles were contained in the isolation room (average concentration = 1 × 10⁴ ± 3 × 10³/L_air). Under exhaust failure, the automated HVAC system maximizes airflow into areas adjacent to isolation rooms to attempt to maintain negative pressure differential. However, 6% of the fluorescent particles were transported through cracks around doors/door handles out of the isolation room via airflow alone and not by movement of personnel or doors. Overall, this study provides a systematic method for evaluating capabilities to contain aerosolized particles during various HVAC scenarios. Recommendations are provided to improve situation‐specific BCU safety.     

Amide–induced monodispersed Pt(100) nanoparticles loaded on graphene surface for enhanced photocatalytic hydrogen evolution

Using free and sustainable solar energy to produce hydrogen is the most promising strategy to resolve the environmental pollution and global energy crisis. The properties of sensitized matrix and co–catalyst, including the dispersibility, lattice structure and electrical performance, are usually two the decisive factors for photocatalytic hydrogen evolution. This paper reports a facile synthetic process of surface–clean monodisperse Pt(100) nanocubes supported on graphene surface using amide functional groups as induction sites. The prepared catalyst (AG/Pt(100)) not only incorporate plentiful amide functional groups that act as the dispersant and stabilizer into surface and edge of graphene, but also significantly dislodge the oxygen–containing functional groups, which hold strong promise for improving conductivity, carrier concentration and mobility of sensitized matrix. Simultaneously, the monodisperse Pt(100) nanocubes supported on graphene surface exposure more active sites. These results provide the necessary conditions for efficient catalysts. Without any pre–treatment, it exhibits high H₂ generation activity (553.7 μmol for 2 h) and apparent quantum efficiency (AQE) (33.9% at 430 nm) under visible light irradiation when Eosin Y is used as photosensitizer. These superior production H₂ activities can attribute to enhance the dispersion and conductivity of sensitized matrix, construct special geometry of Pt(100) nanocubes and prolong the lifetime of photogenerated electron.     

1 000 MW高效宽负荷率的超超临界锅炉开发

根据反平衡法对电站锅炉各项效率损失进行分析，潜力较大的是排烟损失和未完全燃烧损失，主要影响因素有过量空气系数、排烟温度、燃烧效率；1 000 MW高效宽负荷率超超临界煤粉锅炉的开发采用低过量空气系数设计理念，在炉膛选型、受热面布置、燃烧系统设计、降低锅炉漏风等方面采取措施。与传统设计相比，50% THA负荷下锅炉效率提升了0.96%。     

A new high-pressure clearance seal with flexible laddered piston assembly in oil-free miniature compressor for potential hydrogen applications and investigation on its dynamic sealing efficiency

In this paper, a new flexible laddered piston assembly of clearance seal without any soft seal part was proposed for a long life time run of high-pressure stage in oil-free miniature compressor for potential hydrogen applications. In this assembly, the functions of radial load bearing and gas sealing were undertaken independently by large and small piston. The dynamic sealing performance evaluation was carried out by comprehensively considering the real-time variation of gas properties and piston motion with thermodynamic process in the compression chamber. Simulation study shows that the introduced clearance gap has a great influence on the expansion, compression and discharge process. Leakage through the clearance would lead to the in-cylinder pressure drop during the discharge process and bring about oscillation and earlier closure of the discharge valve. Sealing clearance exert more significant influence on the sealing efficiency in the high-pressure stage compared to sealing length and shaft speed.     

An energy matching method for battery electric vehicle and hydrogen fuel cell vehicle based on source energy consumption rate

The smart cities development requires reducing energy consumption and using as much renewable energy as possible, so the widespread use of new energy vehicles is a very important measure. In this work, for the energy system configuration and energy efficiency balance of new energy vehicles, we propose an energy matching method to study its energy efficiency from the view point for energy life cycle. Nowadays, new energy vehicles mainly include battery electric vehicles (BEV) and hydrogen fuel cell vehicles (HFCEV). Firstly, we proposed the Source to Range (STR) model. Then, based on STR model, we used energy efficiency analysis chart to visually represent the conversion, delivery and consumption of the vehicle energy life cycle. Furthermore, we proposed a Source Energy Consumption Rate (SECR), which is used to evaluate the vehicles energy efficiency. Finally, based on STR model, we obtained the dividing line of the same SECR for new energy vehicles and equivalent fuel vehicles, which provides constraints on the vehicle energy system design. The results show that STR model can provide an effective tool for energy matching and energy efficiency analysis of new energy vehicles, and has a reference for product development of new energy vehicles.     

减震隔声降噪地垫的研发

介绍我国分户楼板隔声及其隔声研究现状,详细阐述多层复合结构的减震隔声降噪地垫的结构、性能和安装,减震隔声降噪地垫与木地板配合使用,将其铺装于扫平层的140 mm厚现浇钢筋混凝土楼板之上,经江苏省建工建材检测中心检测,撞击声隔声为61 dB,能很好地满足住宅分户楼板撞击声隔声L'nT,W≤65 dB的要求。