Novel measurement system for respiratory aerosols and droplets in indoor environments

The SARS-CoV-2 pandemic has created a great demand for a better understanding of the spread of viruses in indoor environments. A novel measurement system consisting of one portable aerosol-emitting mannequin (emitter) and a number of portable aerosol-absorbing mannequins (recipients) was developed that can measure the spread of aerosols and droplets that potentially contain infectious viruses. The emission of the virus from a human is simulated by using tracer particles solved in water. The recipients inhale the aerosols and droplets and quantify the level of solved tracer particles in their artificial lungs simultaneously over time. The mobile system can be arranged in a large variety of spreading scenarios in indoor environments and allows for quantification of the infection probability due to airborne virus spreading. This study shows the accuracy of the new measurement system and its ability to compare aerosol reduction measures such as regular ventilation or the use of a room air purifier.     

A practical Equivalent Electrical Circuit model for Proton Exchange Membrane Fuel Cell (PEMFC) systems

An alternative Equivalent Electrical Circuit for Proton Exchange Membrane Fuel Cells is modelled in this study. Both I–V characteristics and H₂ consumptions corresponding to generated power under load and no-load conditions are investigated. For this purpose, H₂ consumptions and I–V characteristics of three different sized PEMFCs are tested. There is a very good harmony between the model results and measured values (relative error %0.7, %6.4 and %2.5 for FC-A, FC-B and FC-C respectively). In the proposed model current passes only on parallel resistance and not on serial resistance at no-load condition. Thus, a FC with higher parallel resistance should be preferred. Another key output of this study is that based on the proposed model, performance comparison of FCs can be performed with the parameters defined in this work. Proposals made in this study can easily be used for performance analysis of FCs under for both steady state and transient analysis.     

Flexible poly(styrene-ethylene-butadiene-styrene) hybrid nanofibers for bioengineering and water filtration applications

Among the thermoplastic elastomers that play important roles in the polymer industry due to their superior properties, styrene-based species and polyurethane block copolymers are of great interest. Poly(styrene-ethylene-butadiene-styrene) (SEBS) as a triblock copolymer seems to have the potential to meet many demands in different applications due to various industrial requirements where durability, biocompatibility, breaking elongation, and interfacial adhesion are important. In this study, the SEBS triblock copolymer was functionalized with natural (Satureja hortensis, SH) and synthetic (nanopowder, TiO₂) agents to obtain composite nanofibers by electrospinning and electrospraying methods for use in biomedical and water filtration applications. The results were compared with thermoplastic polyurethane (TPU) composite nanofibers, which are commonly used in these fields. Here, functionalized SEBS nanofibers exhibited antibacterial effect while at the same time improving cell viability. In addition, because of successful water filtration by using the SEBS composite nanofibers, the material may have a good potential to be used comparably to TPU for the application.     

Partitioning of predominant lipophilic bioactives (squalene, α-tocopherol and β-sitosterol) during olive oil processing

The partitioning of predominant lipophilic olive bioactives (squalene, β-sitosterol and α-tocopherol) in olive oil processing was studied for the first time using common integrated olive milling plant. 7% of the oil and 5% of the squalene present in the olives was lost in the last pomace. β-sitosterol and α-tocopherol, which are mainly concentrated in the seed of the olive fruit, was recovered in virgin olive oil to a lesser extent (66%, 67%) while 10% were lost in last pomace. Thus, the loss of β-sitosterol and α-tocopherol was higher than that of squalene and oil, due to nonrecovered bound forms. 19% of the α-tocopherol and 21% of the β-sitosterol loss was unaccounted for, which can be attributed to degradation of α-tocopherol and incomplete recovery of sterols from the olive and pomace matrices. This study provides a basis for process development studies.     

Optimal design of elastic beams with segmentwise constant height in the case of dynamic loading

A shape optimization method for elastic beams with segmentwise constant height is proposed. The ends of the beam are simply supported, clamped or free. Two problems are discussed; (i) a beam is loaded by lateral pressure, (ii) a beam is struck by an attached mass. External loads and volume of the beam are prescribed and the deflection in a given cross-section is to be minimized. For solving this problem, the deflections are expanded into a Fourier series by eigenfunctions. Numerical results are given for two-, three- and four-stepped beams.     

Self-aligning planarization and passivation for integration applications in III-V semiconductor devices

This work reports an easy planarization and passivation approach for the integration of III-V semiconductor devices. Vertically etched III-V semiconductor devices typically require sidewall passivation to suppress leakage currents and planarization of the passivation material for metal interconnection and device integration. It is, however, challenging to planarize all devices at once. This technique offers wafer-scale passivation and planarization that is automatically leveled to the device top in the 1-3-/spl mu/m vicinity surrounding each device. In this method, a dielectric hard mask is used to define the device area. An undercut structure is intentionally created below the hard mask, which is retained during the subsequent polymer spinning and anisotropic polymer etch back. The spin-on polymer that fills in the undercut seals the sidewalls for all the devices across the wafer. After the polymer etch back, the dielectric mask is removed leaving the polymer surrounding each device level with its device top to atomic scale flatness. This integration method is robust and is insensitive to spin-on polymer thickness, polymer etch nonuniformity, and device height difference. It prevents the polymer under the hard mask from etch-induced damage and creates a polymer-free device surface for metallization upon removal of the dielectric mask. We applied this integration technique in fabricating an InP-based photonic switch that consists of a mesa photodiode and a quantum-well waveguide modulator using benzocyclobutene (BCB) polymer. We demonstrated functional integrated photonic switches with high process yield of >90%, high breakdown voltage of >25 V, and low ohmic contact resistance of /spl sim/10 /spl Omega/. To the best of our knowledge, such an integration of a surface-normal photodiode and a lumped electroabsorption modulator with the use of BCB is the first to be implemented on a single substrate.     

工业项目的海绵城市建设标准与技术要点

工业用地是城市建设用地的主要类型之一,是海绵城市建设的重要区域。通过梳理工业项目硬化面积高、径流污染程度高等特征,针对性提出其海绵城市建设的实施路径、建设标准和技术应用等实施建议。工业项目的海绵城市设计应遵循因地制宜的原则,应合理布局绿地并建设海绵设施,通过精细化的标高设计进行径流组织设计;对于降雨径流污染严重的三类工业项目,其海绵措施应以雨水调蓄池(应急事故池)为主,严禁设置具有渗透功能的源头控制设施。对于三类工业项目,海绵城市所提出的年径流总量控制率的目标与事故池的环保要求基本一致,建议相关部门在制定(修订)的应急事故池设计标准时,其中的径流污染控制体积可与对应区域年径流总量控制率标准协同一致。     

沂沭河底泥中污染物空间分布特征及评价

测定沂沭河底泥的有机质(OM)、总氮(TN)、总磷(TP)及有效磷含量,分析了污染物之间的相关性,评价了沂沭河底泥的污染状况。结果表明:沂沭河流域表层沉积物中TN、TP分布特性相似,沂河中OM含量远低于沭河,OM、TN、TP分布的空间差异较大。有效磷含量约占TP含量的17.7%,表明农田及人类活动对流域水环境造成了一定程度的污染。C/N、N/P及OM与氮、磷含量的回归分析表明,碳、氮具有同源性,底质中OM及氮主要源于生物沉降,而磷主要源于外部输入。经评价,沂沭河底质沉积物环境质量整体较好,污染程度属于清洁水平。     

Video multipath transmission mechanism with load balancing in the FiWi network

Aiming at the differentiated needs of users and the problem of video service interruption caused by the local overload of the converged network,a load-balanced video transmission mechanism is proposed.First,the split multipath routing protocol is improved to obtain the path selection model according to the front-end structural characteristics of the optical fiber wireless access network;second,we calculate the path differential delay and the video transmission delay on wireless side,and set their threshold as the quality of the experience constraint.Finally,while considering the quality of user experience,a particle swarm optimization algorithm with a multi-stage penalty function is used for video distribution.Simulation results show that the proposed mechanism is better than the throughput-aware load-sensing algorithms,enhances delay-control load distribution algorithms and delay-energy-quality aware multipath algorithms,and that it can effectively balance the network load and alleviate network congestion while avoiding user loss.