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38 result(s) for "揮發性有機化合物"
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揮發性有機化合物暴露與失智症風險之相關性:回溯性世代研究
目標:本研究探討不同揮發性有機化合物(volatile organic compounds, VOCs)(包括苯、甲苯、乙苯、間/對-二甲苯)暴露和失智症發生的相關性。方法:本研究以臺灣人體生物資料庫中60歲以上的參與者作為研究對象,並使用土地利用迴歸模型評估揮發性有機化合物、空氣污染物、道路交通噪音及溫度的年平均暴露。我們基於自填問卷的醫師診斷結果及簡易心智量表(Mini-Mental State Examination, MMSE)低於24分來判斷受試者是否為失智症個案,總共參與人數為4,917人。我們使用Cox proportion hazards regression探討揮發性有機化合物與失智症發生的相關性,估計風險比及95%信賴區間,並調整道路交通噪音、空氣污染物(細懸浮微粒[particulate matter with an aerodynamic equivalent diameter ≤ 2.5μm, PM_(2.5)]及二氧化氮[nitrogen dioxide, NO_2])與年平均高溫,計算校正風險。結果:研究對象的苯、甲苯、乙苯、間/對-二甲苯暴露平均分別為3.91±4.31 μg/m^3、2.50±0.35 μg/m^3、2.04±1.20 μg/m^3及10.27±5.78 μg/m^3,其平均人年數為3.43±0.91年,失智症發生率為1.06%。調整空氣污染物、道路交通噪音及年均高溫後,甲苯對失智症發生的風險為0.67(95%CI: 0.51-0.90),且在不同年齡分組(≦65歲/>65歲)有顯著的修飾效應(P_(interaction)=0.023)。結論:甲苯在共同暴露中與失智症的發生風險有顯著保護相關,且不同年齡分組顯示存在修飾效應。
A highly durable catalyst based on CoxMn3-xO4 nanosheets for low-temperature formaldehyde oxidation
Cost-effective catalysts for the oxidation of volatile organic compounds (VOCs) are critical to energy conversion applications and environmental protection. The main bottleneck of this process is the development of an efficient, stable, and cost-effective catalyst that can oxidize HCHO at low temperature. Here, an advanced material consisting of manganese cobalt oxide nanosheet arrays uniformly covered on a carbon textile is successfully fabricated by a simple anodic electrodeposition method combined with post annealing treatment, and can be directly applied as a high-performance catalytic material for HCHO elimination. Benefiting from the increased surface oxygen species and improved redox properties, the as-prepared manganese cobalt oxide nanosheets showed substantially higher catalytic activity for HCHO oxidation. The catalyst completely converted HCHO to CO2 at temperatures as low as 100 ℃, and exhibited excellent catalytic stability. Such impressive results are rarely achieved by non-precious metal-based catalysts at such low temperatures.
Coordination polymers: Challenges and future scenarios for capture and degradation of volatile organic compounds
Over the past few decades, coordination polymers/metal organic frameworks (CPs/MOFs) have drawn a great deal of attention for diverse applications due to their advantages of intrinsically ttLnable chemical structure, flexible architecture, high pore volume, high surface area, multifunctional properties, etc. To date, numerous CPs/MOFs have been developed and employed for the treatment and control of gaseous pollutants, such as volatile organic compounds (VOCs), through capture, sorptive removal, and catalytic degradation. Nevertheless, there are also some key drawbacks and challenges for the practical application of these systems (e.g., poor selectivity, high energy (and fiscal) cost, high synthesis cost, low capacity, and difficulties in regeneration and recycling). In this review, recent developments in CPs/MOFs research are described with their associated mechanisms for capture, sorptive removal, and catalytic degradation of VOCs. To this end, we discuss the key variables and challenges for afforded abatement of VOCs through CPs/MOFs technologies. Hopefully, this review will help the scientific community set future directions for the advancement of CPs/MOFs techniques for the effective management of diverse environmental issues.
Design and synthesis of porous non-noble metal oxides for catalytic removal of VOCs
The design and synthesis of highly active non-noble metal oxide catalysts, such as transition- and rare-earth-metal oxides, have attracted significant attention because of their high efficiency and low cost and the resultant potential applications for the degradation of volatile organic compounds(VOCs). The structure-activity relationships have been well-studied and used to facilitate design of the structure and composition of highly active catalysts. Recently, non-noble metal oxides with porous structures have been used as catalysts for deep oxidation of VOCs, such as aromatic hydrocarbons, aliphatic compounds, aldehydes, and alcohols, with comparable activities to their noble metal counterparts. This review summarizes the growing literature regarding the use of porous metal oxides for the catalytic removal of VOCs, with emphasis on design of the composition and structure and typical synthetic technologies.
Characterization and Source Apportionment of Volatile Organic Compounds in Urban and Suburban Tianjin, China
Tianjin is the third largest megacity and the fastest growth area in China,and consequently faces the problems of surface ozone and haze episodes.This study measures and characterizes volatile organic compounds (VOCs),which are ozone precursors,to identify their possible sources and evaluate their contribution to ozone formation in urban and suburban Tianjin,China during the HaChi (Haze in China) summer campaign in 2009.A total of 107 species of ambient VOCs were detected,and the average concentrations of VOCs at urban and suburban sites were 92 and 174 ppbv,respectively.Of those,51 species of VOCs were extracted to analyze the possible VOC sources using positive matrix factorization.The identified sources of VOCs were significantly related to vehicular activities,which specifically contributed 60% to urban and 42% to suburban VOCs loadings in Tianjin.Industrial emission was the second most prominent source of ambient VOCs in both urban and suburban areas,although the contribution of industry in the suburban area (36%) was much higher than that at the urban area (16%).We conclude that controlling vehicle emissions should be a top priority for VOC reduction,and that fast industrialization and urbanization causes air pollution to be more complex due to the combined emission of VOCs from industry and daily life,especially in suburban areas.
Air quality control in the ART laboratory is a major determinant of IVF success
Arecently published article described how a fertility center in the UnitedStates implemented air quality control to newly designed in vitro fertilization (IVF) laboratory.1 A highly-efficient air filtration was achieved by installing a centered system supplying filtered air to the IVF laboratory and related critical areas, combining air particulate and volatile organic compound (VOC) filtration. As a consequence, live birth rates were increased by improvements in air quality. This article highlights the key aspects of air contamination in the IVF context. The topic is important not only to IVF specialists but also to Andrologists due to the great number of male infertility patients referred to assisted reproductive technology (ART) treatments. The evidence is growing that laboratory air quality is paramount importance for improved IVF outcome.
Role of ammonia in forming secondary aerosols from gasoline vehicle exhaust
Ammonia(NH3) plays vital roles in new particle formation and atmospheric chemistry. Although previous studies have revealed that it also influences the formation of secondary organic aerosols(SOA) from ozonolysis of biogenic and anthropogenic volatile organic compounds(VOCs), the influence of NH3 on particle formation from complex mixtures such as vehicle exhausts is still poorly understood. Here we directly introduced gasoline vehicles exhausts(GVE) into a smog chamber with NH3 absorbed by denuders to examine the role of NH3 in particle formation from GVE. We found that removing NH3 from GVE would greatly suppress the formation and growth of particles. Adding NH3 into the reactor after 3 h photo-oxidation of GVE, the particle number concentration and mass concentrations jumped explosively to much higher levels, indicating that the numbers and mass of particles might be enhanced when aged vehicle exhausts are transported to rural areas and mixed with NH3-rich plumes. We also found that the presence of NH3 had no significant influence on SOA formation from GVE. Very similar oxygen to carbon(O:C) and hydrogen to carbon(H:C) ratios resolved by aerosol mass spectrometer with and without NH3 indicated that the presence of NH3 also had no impact on the average carbon oxidation state of SOA from GVE.
Odour reducing microbial-mineral additive for poultry manure treatment
Poultry production systems are associated with emissions of odorous volatile organic compounds (VOCs), ammonia (NH3), hydrogen sulfide (HES), greenhouse gases, and particulate matter. Development of mitigation technologies for these emissions is important. Previous laboratory-scale research on microbial-mineral treatment has shown to be effective for mitigation of NH3, H2S and amines emissions from poultry manure. The aim of this research was to assess the effectiveness of surface application of a microbial-mineral treatment for other important odorants, i.e., phenolics and sulfur-containing VOCs. Microbial-mineral litter additive consisting of 20% (w/w) of bacteria powder (six strains ofheterotrophic bacteria) and 80% of mineral carrier (perlite-bentonite) was used at a dose of 500 g·m^-2 (per -31 kg of manure). Samples of air were collected m two series, 4 and 7 days after application of additives. An odor profile of the poultry manure was determined using simultaneous chemical and sensory analysis. Reduction levels of VOCs determined on Day 4 was between 31% and 83% for mineral adsorbent treatment and in the range of 9% and 96% for microbial-mineral additive, depending on the analyzed compound. Reduction levels on Day 7 were considerably lower than on Day 4, suggesting that the odorous VOCs treatment efficacy is relatively short. There was no significant difference between treatments consisting of microbial-mineral additive and mineral carrier alone.
Enhanced open-circuit voltage in methoxyl substituted benzodithiophene-based polymer solar cells
The open-circuit voltage(V_(oc))is one of the important parameters that influence the power conversion efficiency(PCE)of polymer solar cells.Its value is mainly determined by the energy level offset between the highest occupied molecular orbital(HOMO)of the donor and the lowest unoccupied molecular orbital(LUMO)of the acceptor.Therefore,decreasing the HOMO value of the polymer could lead to a high Voc and thus increasing the cell efficiency.Here we report a facile way to lower the polymer HOMO energy level by using methoxyl substituted-benzodithiophene(BDT)unit.The polymer with the methoxyl functionl group(POBDT(S)-T1)exhibited a HOMO value of-5.65 eV,which is deeper than that(-5.52 eV)of polymer without methoxyl unit(PBDT(S)-T1).As a result,POBDT(S)-T1-based solar cells show a high V(oc of 0.98 V and PCE of 9.2%.In contrast,PBDT(S)-T1-based devices show a relatively lower Voc of 0.89 V and a moderate PCE of 7.4%.The results suggest that the involvement of methoxyl group into conjugated copolymers can efficiencly lower their HOMO energy levels.
Trends of chemical speciation profiles of anthropogenic volatile organic compounds emissions in China, 2005-2020
This study estimates the detailed chemical profiles of China’s anthropogenic volatile organic compounds (VOCs) emissions for the period of 2005–2020. The chemical profiles of VOCs for seven activity sectors are calculated, based on which the Photochemical Ozone Creation Potential (POCP) of VOCs for these sectors is evaluated. At the national level, the VOCs species emitted in 2005 include alkanes, alkenes and alkynes, aromatic compounds, alcohols, ketones, aldehydes, esters, ethers and halocarbons, accounting for 26.4 wt.%, 29.2 wt.%, 21.3 wt.%, 4.7 wt.%, 5.4 wt.%, 1.7 wt.%, 2.1 wt.%, 0.7 wt. % and 2.2 wt.% of total emissions, respectively. And during 2005-2020, their mass proportions would respectively grow or decrease by − 6.9%, − 32.7%, 7.3%, 65.3%, 34.7%, − 48.6%, 108.5%, 100.5%, and 55.4%. This change would bring about a 13% reduction of POCP for national VOCs emissions in the future. Thus, although the national VOCs emissions are expected to increase by 33% over the whole period, its ozone formation potential is estimated to rise only by 14%. Large discrepancies are found in VOCs speciation emissions among provinces. Compared to western provinces, the eastern provinces with a more developed economy would emit unsaturated hydrocarbons and benzene with lower mix ratios, and aromatic compounds except benzene, oxidized hydrocarbons and halocarbons with higher mix ratios. Such differences lead to lower POCP of VOCs emitted in eastern provinces, and higher POCP of VOCs emitted in western provinces. However, due to the large VOCs emissions from Chinese eastern region, the ozone formation potential of VOCs emission in eastern provinces would be much higher than those in western provinces by about 156%–235%.