A comparative investigation of ultrafine particle number and mass emissions from a fleet of on-road diesel and CNG buses

Particle number, particle mass, and CO2 concentrations were measured on the curb of a busy urban busway used entirely by a mix of diesel and CNG operated buses. With the passage of each bus, the ratio of particle number concentration and particle mass concentration to CO2 concentration in the diluted exhaust plume were used as measures of the particle number and mass emission factors, respectively. With all buses accelerating pastthe monitoring point, the results showed that the median particle mass emission from CNG buses was less than 9% of that from diesel buses. However, the median particle number emission from CNG buses was 6 times higher than the diesel buses, and the particles from the CNG buses were mainly in the nanoparticle size range. Using a thermodenuder to remove the volatile material from the sampled emissions showed that the majority of particles from the CNG buses, but not from the diesel buses, were volatile. Approximately, 82% of the particles from the CNG buses and 38% from the diesel buses were removed by heating the emissions to 300 degrees C.     

Quantification of particle number emission factors for motor vehicles from on-road measurements

The database on particle number emission factors has been very limited to date despite the increasing interest in the effects of human exposure to particles in the submicrometer range. There are also major questions on the comparability of emission factors derived through dynamometer versus on-road studies. Thus, the aims of this study were (1) to quantify vehicle number emission factors in the submicrometer (and also supermicrometer) range for stop-start and free-flowing traffic at about 100 km h(-1) driving conditions through extensive road measurements and (2) to compare the emission factors from the road measurements with those obtained previously from dynamometer studies conducted in Brisbane. For submicrometer particles the average emission factors for Tora Street were estimated at (1.89 +/- 3.40) x 10(13) particles km(-1) (mean +/- standard error; n = 386) for petrol and (7.17 +/- 2.80) x 10(14) particles km(-1) (diesel; n = 196) and for supermicrometer particles at 2.59 x 10(9) particles km(-1) and 1.53 x 10(12) particles km(-1), respectively. The average number emission factors for submicrometer particles estimated for Ipswich Road (stop-start traffic mode) were (2.18 +/- 0.57) x 10(13) particles km(-1) (petrol) and (2.04 +/- 0.24) x 10(14) particles km(-1) (diesel). One implication of the conclusion that emission factors of heavy duty diesel vehicles are over 1 order of magnitude higher than emission factors of petrol-fueled passenger cars is that future control and management strategies should in particular target heavy duty vehicles, as even a moderate decrease in emissions of these vehicles would have a significant impact on lowering atmospheric concentrations of particles. The finding that particle number emissions per vehicle-km are significantly larger for higher speed vehicle operation has an important implication on urban traffic planning and optimization of vehicle speed to lower their impact on airborne pollution. Additionally, statistical analysis showed that neither the measuring method (dynamometer or on-road), nor data origin (Brisbane or elsewhere in the world), is associated with a statistically significant difference between the average values of emission factors for diesel, petrol, and vehicle fleet mix. However, statistical analyses of the effect of fuel showed that the mean values of emission factors for petrol and diesel are different at a 5% significance level.     

Variability of particle number emissions from diesel and hybrid diesel-electric buses in real driving conditions

A linear mixed model was developed to quantify the variability of particle number emissions from transit buses tested in real-world driving conditions. Two conventional diesel buses and two hybrid diesel-electric buses were tested throughout 2004 under different aftertreatments, fuels, drivers, and bus routes. The mixed model controlled the confounding influence of factors inherent to on-board testing. Statistical tests showed that particle number emissions varied significantly according to the after treatment, bus route, driver, bus type, and daily temperature, with only minor variability attributable to differences between fuel types. The daily setup and operation of the sampling equipment (electrical low pressure impactor) and mini-dilution system contributed to 30-84% of the total random variability of particle measurements among tests with diesel oxidation catalysts. By controlling for the sampling day variability, the model better defined the differences in particle emissions among bus routes. In contrast, the low particle number emissions measured with diesel particle filters (decreased by over 99%) did not vary according to operating conditions or bus type but did vary substantially with ambient temperature.     

Determining the frequency of asbestos use in automotive brakes from a fleet of on-road California vehicles

Asbestos is a known human carcinogen, and recent regulation in California limits asbestiform fibers in brakes to trace levels beginning in 2014, although there is no corresponding federal requirement. In order to gauge the current prevalence of asbestos use in automotive brake applications, the California Air Resources Board tested brake linings from 137 light- and medium-duty vehicles and 54 heavy-duty vehicles. Only about 3% of the light- and medium-duty vehicle brake linings contained chrysotile asbestos. All of those brake linings were drum-type shoes, which are generally being phased out. No asbestos was found in low mileage vehicles presumed to have their original stock linings from the vehicle manufacturer. Additionally, no asbestos was found in the heavy-duty vehicle brake shoe linings sampled. Given the small percentage of vehicle brake linings with asbestos observed, it appears that the prior federal ban that was subsequently overturned, in combination with a threat of litigation, has reduced asbestos use in brake linings. However, our study was limited in scope and without a national ban, the current and future prevalence of asbestos in brakes is uncertain, suggesting the need for continued monitoring of materials released as toxic air contaminants in normal braking operations.     

Uncertainty in particle number modal analysis during transient operation of compressed natural gas, diesel, and trap-equipped diesel transit buses

The relationships between transient vehicle operation and ultrafine particle emissions are not well-known, especially for low-emission alternative bus technologies such as compressed natural gas (CNG) and diesel buses equipped with particulate filters/traps (TRAP). In this study, real-time particle number concentrations measured on a nominal 5 s average basis using an electrical low pressure impactor (ELPI) for these two bus technologies are compared to that of a baseline catalyst-equipped diesel bus operated on ultralow sulfur fuel (BASE) using dynamometer testing. Particle emissions were consistently 2 orders of magnitude lower for the CNG and TRAP compared to BASE on all driving cycles. Time-resolved total particle numbers were examined in terms of sampling factors identified as affecting the ability of ELPI to quantify the particulate matter number emissions for low-emitting vehicles such as CNG and TRAP as a function of vehicle driving mode. Key factors were instrument sensitivity and dilution ratio, alignment of particle and vehicle operating data, sampling train background particles, and cycle-to-cycle variability due to vehicle, engine, after-treatment, or driver behavior. In-cycle variability on the central business district (CBD) cycle was highest for the TRAP configuration, but this could not be attributed to the ELPI sensitivity issues observed for TRAP-IDLE measurements. Elevated TRAP emissions coincided with low exhaust temperature, suggesting on-road real-world particulate filter performance can be evaluated by monitoring exhaust temperature. Nonunique particle emission maps indicate that measures other than vehicle speed and acceleration are necessary to model disaggregated real-time particle emissions. Further testing on a wide variety of test cycles is needed to evaluate the relative importance of the time history of vehicle operation and the hysteresis of the sampling train/dilution tunnel on ultrafine particle emissions. Future studies should monitor particle emissions with high-resolution real-time instruments and account for the operating regime of the vehicle using time-series analysis to develop predictive number emissions models.     

Effects of diesel particle filter retrofits and accelerated fleet turnover on drayage truck emissions at the Port of Oakland

Heavy-duty diesel drayage trucks have a disproportionate impact on the air quality of communities surrounding major freight-handling facilities. In an attempt to mitigate this impact, the state of California has mandated new emission control requirements for drayage trucks accessing ports and rail yards in the state beginning in 2010. This control rule prompted an accelerated diesel particle filter (DPF) retrofit and truck replacement program at the Port of Oakland. The impact of this program was evaluated by measuring emission factor distributions for diesel trucks operating at the Port of Oakland prior to and following the implementation of the emission control rule. Emission factors for black carbon (BC) and oxides of nitrogen (NO(x)) were quantified in terms of grams of pollutant emitted per kilogram of fuel burned using a carbon balance method. Concentrations of these species along with carbon dioxide were measured in the exhaust plumes of individual diesel trucks as they drove by en route to the Port. A comparison of emissions measured before and after the implementation of the truck retrofit/replacement rule shows a 54 ± 11% reduction in the fleet-average BC emission factor, accompanied by a shift to a more highly skewed emission factor distribution. Although only particulate matter mass reductions were required in the first year of the program, a significant reduction in the fleet-average NO(x) emission factor (41 ± 5%) was observed, most likely due to the replacement of older trucks with new ones.     

Single particle characterization of ultrafine and accumulation mode particles from heavy duty diesel vehicles using aerosol time-of-flight mass spectrometry

The aerodynamic size and chemical composition of individual ultrafine and accumulation mode particle emissions (Da = 50-300 nm) were characterized to determine mass spectral signatures for heavy duty diesel vehicle (HDDV) emissions that can be used for atmospheric source apportionment. As part of this study, six in-use HDDVs were operated on a chassis dynamometer using the heavy heavy-duty diesel truck (HHDDT) five-cycle driving schedule under different simulated weight loads. The exhaust emissions were passed through a dilution/residence system to simulate atmospheric dilution conditions, after which an ultrafine aerosol time-of-flight mass spectrometer (UF-ATOFMS) was used to sample and characterize the HDDV exhaust particles in real-time. This represents the first study where refractory species including elemental carbon and metals are characterized directly in HDDV emissions using on-line mass spectrometry. The top three particle classes observed with the UF-ATOFMS comprise 91% of the total particles sampled and show signatures indicative of a combination of elemental carbon (EC) and engine lubricating oil. In addition to the vehicle make/year, the effects of driving cycle and simulated weight load on exhaust particle size and composition were investigated.     

保健食品中人参皂苷类成分的快速检测及应用

目的建立保健食品中人参皂苷类成分的提取、检测方法,并对检测方法进行方法学考察。方法以标示含人参成分保健食品为研究对象,样品经溶剂提取,固相萃取小柱净化,超高效液相-串联二极管阵列检测器检测保健食品中人参皂苷类成分。使用建立的方法对市售17批保健食品(标示成分为总皂苷)中的人参皂苷类成分进行含量测定,并与产品总皂苷标示量和传统检测方法的测定结果进行对比,评判含人参成分保健食品品质。结果建立的方法能够快速、准确、灵敏地检测7种皂苷成分。17批标示含人参成分的保健食品所测人参皂苷类成分总量均低于采用《规范》方法所测得的总皂苷含量和产品总皂苷标示含量。结论本研究建立的方法可以客观反映含人参成分保健食品的品质。     

Oxalic extraction of high methoxyl pectin and its application as a stabiliser

The objective of this work was to extract high methoxyl (HM) pectin with oxalic acid, characterise its physicochemical properties and evaluate its dispersion stability in acidified milk drink (AMD). HPSEC–MALLS analysis revealed that the obtained HM pectin was high in molecular weight (522.4 kDa). The ζ-potential of the obtained HM pectin in aqueous solution at pH 4.0 was −31.5 mV. The AFM images proved that the obtained HM pectin contained several long linear molecules. The apparent diameter of AMD stabilised by the obtained HM pectin was 636 nm at the concentration of 3.0‰. The stability analysis of AMD and the microscopic observation with confocal laser scanning microscopy (CLSM) proved that the obtained HM pectin was a prominent stabiliser in AMD.     

继电反馈辨识方法的改进及应用

分析和研究了常规PID算法不适应用于大时滞过程控制的一些主要因素，有针对性地提出了基于改进型继电反馈辨识方法的PID／PI自整定控制策略，并将其应用于典型的大时滞大惯性对象——纸机的水分定量控制系统中，系统运行结果证明控制效果良好。     

Rapid analysis of glufosinate by improving the bulletin method and its application to soybean and corn

A rapid analytical method for residues of the herbicide glufosinate [DL-homoalanin-4-yl (methyl)phosphinic acid] and its metabolite (MPPA: 3-methylphosphinicopropionic acid) in soybeans and corns was developed by improving the bulletin method. Fifty mL of solution extracted with water (corresponding to 2 g of the sample) was loaded on a column packed with 5 mL of anion exchange resin, and then the trapped glufosinate and MPPA were eluted with 40 mL of 50% acetic acid. After the derivatization of glufosinate and MPPA with trimethyl orthoacetate, the derivatives were purified and separated on a silica gel cartridge column. The determination of the derivatives was performed with a GC-FPD. The detection limits for glufosinate and MPPA were 0.01 microgram/g and 0.005 microgram/g, respectively. The recoveries of glufosinate from soybeans and corns were 86.3-92.0%, and those of MPPA were 86.5-95.2%.     

产琥珀酸菌的快速筛选及鉴定

琥珀酸是重要的化工原料,广泛应用于食品、医药等领域。采用简单、高效的筛选方法,从牛瘤胃内容物分离获得1株有潜力的琥珀酸生产菌。通过生理生化分析和16SrDNA同源性比对,鉴定为琥珀酸放线杆菌(Actinobacillus succinogenes)。     

一株产高活性多酚氧化酶菌株筛选鉴定及其酶学性质

采用变色圈法从土壤样品中分离筛选产多酚氧化酶的菌株,对其进行形态学观察、分子生物学鉴定,并对其所产多酚氧化酶的酶学性质进行研究。结果表明,筛选得到1株产多酚氧化酶活性较高的菌株,命名为ZL-2,其被鉴定为竹黄菌属（Shiraia sp.）。菌株ZL-2发酵8 d产多酚氧化酶酶活最高,达到521 U/mL。菌株ZL-2产多酚氧化酶最适底物为邻苯二酚,其最适pH值为6、最适温度为30 ℃;酶活在温度20～40 ℃及pH 3～6范围内稳定。金属离子Cu2+、Mg2+、Mn2+、Fe3+、Zn2+对多酚氧化酶都有激活作用,其中Cu2+激活作用最强;Ca2+、Al3+对酶活有一定抑制作用;L-抗坏血酸和亚硫酸氢钠对该酶抑制作用较强。     

一株芽孢杆菌的分离鉴定及其在发酵酱渣研究中的应用

从酱渣中筛选分离出一株芽孢菌株,通过生理生化实验以及16SrDNA鉴定其为地衣芽孢杆菌,将该菌种应用于发酵酱渣研究,表明用液态发酵方式较好,当酱渣与玉米淀粉比例为1∶1时,获得的活菌数较多。对添加辅料元素进行正交实验优化结果表明,当培养基中MgSO₄为3g/L,MnSO₄为2g/L,CaCO₃为3g/L时,培养基中的活菌数最多,为6.55×10⁹cfu/mL。     

一株塔宾曲霉的分离鉴定及其在地沟油鉴别中的应用

为了研究微生物在地沟油鉴别领域的应用,采用地沟油精炼技术对地沟油进行精炼,并从地沟油中分离获得8株真菌,其中发现菌株DGY03能够在地沟油培养基上快速生长繁殖,对其进行形态学观察以及采用分子生物学等方法进行鉴定。同时进一步探讨了菌株DGY03应用于地沟油鉴别领域的可行性,观察并比较其在地沟油和四种食用油培养基上的菌落生长速度、菌落长势以及培养基颜色变化等特征。结果表明,该菌株的菌落形态和显微结构与曲霉属基本相同,其ITS序列与Aspergillus tubingensis的同源性达100%,确定该菌株为塔宾曲霉(Genbank登录号:MF186869)。菌株DGY03在地沟油培养基上的菌落生长速度和菌落长势明显优于其它四种食用油培养基,其在地沟油培养基上的菌落生长速度为0.64 cm/d,而在大豆油、菜籽油、玉米油、花生油培养基上的菌落生长速度分别为0.21、0.28、0.24、0.29 cm/d。由此初步推断,利用菌株DGY03作为指示菌鉴别地沟油是可行的。     

Measurements of particle number and mass concentrations and size distributions in a tunnel environment

Particulate matter emissions were measured in two bores of the Caldecott Tunnel in Northern California during August and September 2004. One bore (Bore 1) is open to both heavy- and light-duty vehicles while heavy-duty vehicles are prohibited from entering the second bore (Bore 2). Particulate matter number and mass size distributions, chemical composition, and gaseous copollutants were recorded for four consecutive days near the entrance and exit of each bore. Size-resolved emission factors were determined for particle number, particle mass, elemental carbon, organic carbon (OC), sulfate, nitrate, and selected elements. The size distributions in both the bores showed a single large mode at roughly 15-20 nm in mobility diameter, with occasional smaller modes around 100 nm. The PM10 mass emission factor for heavy-duty vehicles was 14.5 times higher than that of light-duty vehicles. The particles derived from diesel are more abundant in elemental carbon, 70.9% of PM10 emissions, as compared to the light-duty vehicles. Conversely, a greater percentage of OC was found in light-duty emissions than heavy-duty emissions. In comparison to previous studies at the Caldecott Tunnel, less particle mass but more particle numbers are emitted by vehicles than was the case 7 years ago.     

HNSS01的分离鉴定以及用于酱油酿造的初步研究

摘要：HNSS01是从阳江豆豉中分离得到的1株枯草芽孢杆菌,用其作为发酵菌种,以大豆为原料,结合高盐稀态发酵工艺的某些特点进行酿制酱油的实验研究。结果表明：加入2倍体积的水进行发酵得到的头油氨基态氮含量为0．991g／100mL的酱油,头油总酸含量为1．425g／100mL,还原糖含量为2．283mg／mL,可溶性固形物为39．394．g／100mL,全氮含量为1．045g／100mL。色泽呈棕黄色,具有酱油的浓郁香气．     

蜡样芽孢杆菌(Bacillus cereus)筛选鉴定及在雪茄烟叶发酵中的应用研究

采用酪蛋白水解实验和蛋白酶活力测定对烟草表面微生物进行分离筛选,对所筛选菌株进行形态学观察、理化试验及16SrRNA基因测序的鉴定。将筛选所得菌株x-2添加到雪茄烟叶表面进行人工发酵,对发酵后烟叶进行常规氮化合物测定和感官质量评吸,结果表明:筛选所得菌株x-2在45℃时其产酸、中、碱性蛋白酶最高酶活力分别为91.63 U/mL、163.34 U/mL、43.82 U/mL,经过鉴定为蜡样芽孢杆菌(Bacillus cereus)。在雪茄烟叶堆积发酵过程中添加x-2可明显降低烟叶含氮化合物含量,发酵结束时烟叶总氮降低21.64%、蛋白质降低13.53%、总植物碱降低36.38%,挥发碱降低24.05%;感官评吸结果显示烟叶劲头、刺激性改善最为明显,同时杂气减轻、香气增加。     

Structural coloration and its application to textiles: a review

Abstract

Structural coloration, where the microscopic structure of surfaces affects the behavior of light, has attracted growing attention across numerous application areas, especially textile engineering and dyeing. In this review, fundamental mechanisms, means of fabrication and recent progress regarding the structural coloration of textile fibers and fabrics is summarized, examining how it represents an alternate method to traditional chemical dyeing. The opportunities and challenges of applying structural coloration to textiles are discussed and effective strategies for the design and preparation of such textiles are assessed. It is concluded that there is a need for further work on the use of structural coloration with flexible textiles and the range of textiles to which it might be applied. It is also concluded that structural coloration is unlikely to completely replace traditional dyeing and that the scope for industrial application of the approach requires significant further research.