城市道路绿化带"微峡谷效应"及其对非机动车道污染物浓度的影响

研究不同绿化带结构对非机动车道污染物浓度的影响,将为城市道路绿化带格局提供依据。利用遮荫网模拟10、20、30 m隔离的道路绿化带,并模拟了3种不同结构的绿化带,分别对各类道路微气候条件(风)及SO₂、NO_x、NH₃、总悬浮颗粒物(TSP)和可吸入颗粒物(PM10)等5种主要污染物浓度进行了观测。结果表明:风速小于2 m/s时,10 m和20 m间隔的道路绿化带会产生"微峡谷效应",使绿化带间隔内风速增加。10 m间隔的绿化带较其它两种绿化带对各种污染物的净化百分率更明显,且污染物净化百分率与风速大多正相关显著。12.5 m的模拟绿化带与10 m的间隔交替的绿化带可以更有效地降低非机动车道的污染物浓度,污染物净化百分率与风速也大多正相关显著。不同结构道路绿化带会影响道路微气候条件,从而影响非机动车道污染物浓度。城市道路绿带存在合理的绿带结构,可以通过设计更合理的城市道路绿带模式有效改善城市非机动车道空气质量。     

The effects of thermoregulatory behaviour on the heat loss from shorn sheep as measured by a model ewe for micro-climate integration

A thermostatic, taxidermic model sheep was used to assess the effects of thermoregulatory behaviour of shorn sheep at night in a winter environment with mean air temperatures slightly above freezing, variable wind speeds, rain and cloud cover.Testing in a wind tunnel showed that angle of incidence to the wind had no effect on heat loss at wind speeds < 2 m s⁻¹ (7 km h⁻¹), but at wind speeds of 7 m s⁻¹ (25 km h⁻¹), heat loss was 14% greater when the model was side-on rather than tail- or head-on to the wind.In tests on pasture, standing side-on to the early morning sun reduced heat loss from the model by 33%. Three hours “lying” on the lee side of a 1-m high synthetic Sarlon windbreak on a frosty night resulted in a reduction in heat loss of 6% below that when standing or 11% below that in a standing position in the open. When the model was placed in the centre of a tight group of 16 shorn sheep, its heat loss was reduced by an average of 14%.Heat loss was also reduced if the model was moved from the open, to regions of lower wind speed adjacent to windbreaks; the effect was greater on the leeward than the windward side.The reduction one metre leeward of a grass hedge (hybrid Phalaris) was 15% compared with 12% one metre leeward of a synthetic (Sarlon) windbreak, which is consistent with the preference of shorn sheep to shelter by Phalaris rather than Sarlon windbreaks.The microclimates where heat loss from the model were lowest correspond to those sought by shorn sheep in cold weather, and the results indicate that shorn sheep have very sensitive thermosensing mechanisms and efficient thermoregulatory behaviour.     

Estimating PM2.5 Concentrations in Xi'an City Using a Generalized Additive Model with Multi-Source Monitoring Data

Particulate matter with an aerodynamic diameter <2.5 μm (PM_2.5) represents a severe environmental problem and is of negative impact on human health. Xi''an City, with a population of 6.5 million, is among the highest concentrations of PM_2.5 in China. In 2013, in total, there were 191 days in Xi’an City on which PM_2.5 concentrations were greater than 100 μg/m³. Recently, a few studies have explored the potential causes of high PM_2.5 concentration using remote sensing data such as the MODIS aerosol optical thickness (AOT) product. Linear regression is a commonly used method to find statistical relationships among PM_2.5 concentrations and other pollutants, including CO, NO₂, SO₂, and O₃, which can be indicative of emission sources. The relationships of these variables, however, are usually complicated and non-linear. Therefore, a generalized additive model (GAM) is used to estimate the statistical relationships between potential variables and PM_2.5 concentrations. This model contains linear functions of SO₂ and CO, univariate smoothing non-linear functions of NO₂, O₃, AOT and temperature, and bivariate smoothing non-linear functions of location and wind variables. The model can explain 69.50% of PM_2.5 concentrations, with R² = 0.691, which improves the result of a stepwise linear regression (R² = 0.582) by 18.73%. The two most significant variables, CO concentration and AOT, represent 20.65% and 19.54% of the deviance, respectively, while the three other gas-phase concentrations, SO₂, NO₂, and O₃ account for 10.88% of the total deviance. These results show that in Xi''an City, the traffic and other industrial emissions are the primary source of PM_2.5. Temperature, location, and wind variables also non-linearly related with PM_2.5.     

Impact of novel coronavirus disease (COVID-19) lockdown on ambient air quality of Saudi Arabia

The outbreak of COVID-19 has spread globally affecting human activities but with improvement in ambient air quality. The first case of the virus in the Kingdom of Saudi Arabia was on the 2nd of March 2020. The impact of COVID-19 lockdown on the ambient air quality of the Kingdom of Saudi Arabia for the first time using data from nine cities was determined in this study. Hourly air quality data, based on concentrations of carbon monoxide (CO), particulate matter (PM₁₀), sulfur dioxide (SO₂), nitrogen dioxide (NO₂) and ozone (O₃), and meteorological conditions (atmospheric temperature, relative humidity, and wind speed) of the nine cities studied were obtained from Saudi Arabian General Authority of Meteorology and Environmental Protection (GAMEP), for the period between January 2019 to May 2020. Significant variation (p < 0.05) was recorded for the five atmospheric pollutants across the cities before and during the lockdown, with lower concentrations during the lockdown except for the concentration of O₃ in Tabuk, Al Qasim, and Haql. This can be a result of NO and O₃ reaction, causing the inability of effective O₃ depletion. The percentage changes in concentrations of CO (33.60%) and SO₂ (44.16%) were higher in Jeddah; PM₁₀ (91.12%) in Riyadh, while NO₂ (44.35%) and O₃ (18.98%) were highest in Makkah. However, even though there was a decrease in pollutants concentrations during the lockdown, the concentrations for CO, PM₁₀, SO₂, NO_2, and O₃ were still above WHO 24 h and annual mean limit levels. The COVID-19 lockdown in the Kingdom of Saudi Arabia revealed the possibility of significant atmospheric pollutant reduction by controlling traffic, activities by industries, and environmentally friendly transportation programs such as green commuting programs.     

Influence of cadmium on the distribution of the essential trace elements zinc and copper in the liver and kidneys of rats

Cd induced changes of Zn and Cd distribution in the liver and kidneys were studied in relation to Cd metallothionein (MT) synthesis. Wistar male rats were given CdCl₂ by sc injection of .8, 1.5, and 3.0 mg Cd/kg three times a week for three weeks. Cd levels of liver and kidneys increased with the increment of Cd dosage and 80–90% of Cd was found in the cytosol. The MT fractions contained 80–89% cytosolic Cd in the liver and 55–75% Cd in the kidneys. Zn concentrations in the liver increased following Cd administration, But Zn in the kidneys showed only slight increase. There was a distinct decrease of Cu concentration in the liver of the 3.0 mg group. In contrast, Cu concentrations in the kidneys increased about three times in the .8 and 1.5 mg Cd groups, but Cu in the 3.0 mg group showed only 1.5 times increase. The changes of these metal concentrations were observed mainly in the cytosol. Non-MT-Cd in the kidneys was maximum in the 1.5 mg group, but the 3.0 mg group showed significant decrease. In parallel with this decrease of Cd, Cu and Zn in the kidneys showed similar decrease. When the kidneys are injured, Zn and Cu appear to leak from this organ.     

Presence of shrubs influences the spatial pattern of soil seed banks in desert herbaceous vegetation

Question: Do shrubs influence the spatial pattern of soil seed banks in herbaceous vegetation and are these effects influenced by wind direction, sampling position (windward vs leeward sides of the shrub) and distance from the shrub? Location: Horqin desert in eastern Inner Mongolia, China. Methods: A pioneer shrub, Artemisia halodendron, occurring in a mobile sandy habitat was used as a case study. Species composition and abundance of the seed bank and established herbaceous vegetation around six target shrubs were sampled along transects aligned to the four main wind directions and at 0.5, 1, 2, 3, 4.5 and 6 m from the shrub base on both windward and leeward sides of a transect. Results: The presence of shrubs significantly modified the spatial pattern of seed deposition, but effects varied with wind direction, sampling position and distance from the shrub. More seeds were deposited on the leeward side than on the windward sides in all four transects, especially on transects with the most prevailing wind directions. Shrubs also caused a marked variation in seed deposition across sampling locations; this effect was more pronounced on the leeward side of transects with the most prevailing wind directions, suggesting the mean range of the shrub's influence is within ca. 2 m. Conclusions: The study shows clear evidence of shrubs as a source of spatial heterogeneity in seed availability in the herbaceous layer. Shrub presence effects were strongly influenced by complex interactions between wind direction, sampling position, and distance from the shrub.     

AEROBIOLOGY AND POLLEN CAPTURE OF ORCHARD-GROWN PISTACIA VERA (ANACARDIACEAE)

The phenology of pollen release and pollen capture by Pistacia vera was studied in the field and laboratory respectively. Inflorescences of Pistacia vera were examined in a wind tunnel to determine whether the behavior of airborne conspecific pollen around receptive flowers differed as a result of changes in the shape and size of the inflorescence. In addition, the behavior of unclumped (single) and clumped pollen grains was studied to determine differences in the probability of their capture. Wind speeds within a commercial orchard during pollen shedding averaged 0.9–2.2 m/sec and atmospheric pollen concentrations were highest between 0900–1100 hr MST. Each of three stages in inflorescence development (defined on the basis of the number of exserted stigmas) was examined under identical ambient airflow conditions with equal concentrations of airborne pollen (1,000 grains/m³). The general pattern of pollen grain motion involves direct inertial collision by windward surfaces and by sedimentation of pollen onto leeward surfaces; clumped pollen rarely sedimented onto leeward surfaces. Small changes in ambient wind speed (0.5 m/sec to 1.0 m/sec) produced significant changes in the pattern of pollen motion around inflorescences and altered the number of pollen grains captured by leeward surfaces. Thus, wind pollination in P. vera is affected both by windspeed and by the shape or size of flower clusters. Differences in the behavior of clumped and unclumped pollen result from their inertial properties and responsiveness to local changes in the direction and speed of airflow. Unclumped pollen has a higher probability of being captured by leeward surfaces. The apparent insensitivity of pollen motion to differences in inflorescence size may ensure equitable pollination during the acropetal development of flowers.     

科尔沁沙地人工杨树林生态服务效能评价

采用定位观测法,系统评价了杨树(Populus simonii)林的防风、抗蚀和滞尘等生态服务效能及其间接价值,同时定量探讨了风速减弱系数与实测林地叶面积指数的关系。结果表明,在研究区主害风(西北风)天气下,林地迎风区6H(H为平均树高)、3H、林地中央、林地背风区林缘、6和8H处2m高度的日平均风速与对照点(流动沙丘)相比均有不同程度减弱,风速减弱系数在18．3％～66．2％之间。林地背风区6H处0．25、0．5、1和2 m 4个高度的月平均风速减弱系数与林地叶面积指数呈显著非线性相关,其间存在良好的三次曲线关系(P<0．0001,R²=0．43～0．94,n=80)。在主害风天气下,林地各观测点的地表日风蚀量与对照点相比大幅度降低,平均降幅85．2％～99．9％。在观测期内,林地中央的日平均降尘量为13.2 kg·hm^-2,而林地迎风区6H处的日平均降尘量为9．9 kg·hm^-2,林地的日滞尘能力约为3．3kg·hm^-2。       

The Association between Ambient Air Pollution and Daily Mortality in Beijing after the 2008 Olympics: A Time Series Study

In recent decades, ambient air pollution has been an important public health issue in Beijing, but little is known about air pollution and health effects after the 2008 Beijing Olympics. We conduct a time-series analysis to evaluate associations between daily mortality (nonaccidental, cardiovascular and respiratory mortality) and the major air pollutants (carbon monoxide, nitrogen dioxide and particulate matter less than 10 µm in aerodynamic diameter) in Beijing during the two years (2009∼2010) after the 2008 Beijing Olympics. We used generalized additive model to analyze relationship between daily mortality and air pollution. In single air pollutant model with two-day moving average concentrations of the air pollutants, increase in their interquartile range (IQR) associated with percent increase in nonaccidental mortality, 2.55 percent [95% confidence interval (CI): 1.99, 3.11] for CO, 2.54 percent (95% CI: 2.00, 3.08) for NO₂ and 1.80 percent (95% CI: 1.21, 2.40) for PM₁₀, respectively; increases in the IQR of air pollutant concentrations associated with percent increase in cardiovascular mortality, 2.88 percent (95% CI: 2.10,3.65) for CO, 2.63 percent (95% CI: 1.87, 3.39) for NO₂ and 1.72 percent (95% CI: 0.88, 2.55) for PM₁₀, respectively; and increase in IQR of air pollutant concentrations associated with respiratory mortality, 2.39 percent (95% CI: 0.68, 4.09) for CO, 1.79 percent (95% CI: 0.11, 3.47) for NO₂ and 2.07 percent (95% CI: 0.21, 3.92) for PM₁₀, respectively. We used the principal component analysis to avoid collinearity of varied air pollutants. In addition, the association stratified by sex and age was also examined. Ambient air pollution remained a significant contributor to nonaccidental and cardiopulmonary mortalities in Beijing during 2009∼2010.     

Energetic costs of the winter arboreal microclimate: The gray squirrel in a tree

Heated taxidermic mounts of the gray squirrel were used to analyze the thermal environment of a small arboreal endotherm. Changes in the standard operative temperature (T _es) calculated from the temperatures of heated and unheated mounts agreed well with the power consumption (M–E) of mounts on the ground and on the wind-ward side of a 48-cm diameter tree trunk. As wind speed (u) rose and sky solar radiation (Q _r) decreased, the windward side of the tree trunk became an increasingly more stressful thermal environment than the leeward side of the trunk or the ground, producingM–E differences of more than 30%. Although theM–E of a ground mount and a limb mount 4 m in the air are dependent onQ _ras well asu, the ratio of the two value ofM–E is independent ofQ _r, poorly predicted byu and well predicted byu ^1/2.     

Future wood productivity of Pinus radiata in New Zealand under expected climatic changes

The physiologically based growth model CenW was used to simulate wood‐productivity responses of Pinus radiata forests to climate change in New Zealand. The model was tested under current climatic conditions against a comprehensive set of observations from growth plots located throughout the country. Climate change simulations were based on monthly climate change fields of 12 GCMs forced by the SRES B1, A1B and A2 emission scenarios for 2040 and 2090. Simulations used either constant or increasing CO₂ concentrations corresponding to the different emission scenarios. With constant CO₂, there were only slight growth responses to climate change across the country as a whole. More specifically, there were slight growth reductions in the warmer north but gains in the cooler south, especially at higher altitudes. For sites where P. radiata is currently grown, and across the full suite of GCMs and emission scenarios, changes in wood productivity averaged +3% for both 2040 and 2090. When increasing CO₂ concentration was also included, responses of wood productivity were generally positive, with average increases of 19% by 2040 and 37% by 2090. These responses varied regionally, ranging from relatively minor changes in the north of the country to very significant increases in the south, where the beneficial effect of increasing CO₂ combined with the beneficial effect of increasing temperatures. These relatively large responses to CO₂ depend on maintenance of the current adequate fertility levels in most commercial plantations. Productivity enhancements came at the expense of some soil‐carbon losses. Average losses for the country were simulated to average 3.5% under constant CO₂ and 1.5% with increasing CO₂ concentration. Again, there were regional differences, with larger losses for regions with lesser growth enhancements, and lesser reductions in regions where greater productivity enhancements could partly balance the effect of faster decomposition activity.     

A Study of Energy Consumption and Exhaust Emissions from Beijing's Civil Vehicles from Years 2008 to 2020

The number of Beijing's civil vehicles is growing rapidly due to the great support of the automobile industry and the Chinese government and the increasing average per capita income of China's people. Exhaust emissions from vehicles have already become the main source of Beijing's air pollution. Based on the Long-range Energy Alternatives Planning System (LEAP), this article predicts the energy consumption and exhaust emissions from Beijing's civil vehicles. Also, we estimated the reduction potentials of China's new fuel consumption standards and exhaust pollutants standards that will be implemented from 2008 to 2020. Two scenarios were developed: “Business as Usual” (BAU) and “New Standard” (NS). In the BAU scenario, the Chinese government would do nothing to improve the fuel consumption standards and exhaust pollutants standards in the future. In the NS scenario, the Chinese government would implement more strict fuel consumption standards and exhaust pollutants standards for Beijing's civil vehicles. By comparing the results of the two scenarios for year 2020, the energy consumption will experience a reduction of 7.8%, and the exhaust pollutants CO, HC, NO_X, PM, and the emissions of CO₂ would decrease by 43.3%, 36.4%, 60.3%, 81.2%, and 7.8%, respectively.     

Utilization of traces of carbon monoxide by aerobic oligotrophic microorganisms in ocean,lake and soil

Carbon monoxide at trace concentrations (1 nM) was utilized in ocean water, lake water and soil. By boiling or by poisoning the water with HgCl₂, NaCN or NaN₃ must read CO consumption was switched off; this demonstrated that CO utilization was due to metabolic processes. Since CO consumption activity was removed by filtration through 0.2 m filters, but not by filtration through 3.0 m filters, CO consumption was most probably due to single bacterial cells. CO consumption followed Michaelis-Menten kinetics withK _m -values of 7–9 nM CO. Enrichment experiments were carried out by gassing lake water and soil suspensions with ambient pressurized air containing 0.5–1.0 ppmv CO. After a total supply of approximately 2 ml CO, utilization of CO became detectable. Then, the CO consumption rates of the suspensions increased steadily with incubation time indicating the growth of a specific CO-utilizing microbial population. No CO consumption activity was detectable in control suspensions, which were gassed with CO-free air. The high affinity of soil and water for CO as well as the increase of CO consumption activity upon incubation under ambient atmospheric CO is indicative for the oligotrophic nature of a specific CO-utilizing microflora.     

模拟长期大风对木本猪毛菜表观特征的影响

风是一个重要的生态因子,对植物地上部分的生长和构型有重要影响。植物表观特征对植物获取光能、抵抗外界机械压力有着重要作用。木本猪毛菜(Salsola arbuscula Pall.)是新疆达坂城大风区植被的共建种,也是该区植被恢复潜在的先锋植物。为了研究木本猪毛菜在长期大风环境中形成的独特适应机制,以盆栽实验为手段,设置3个风速(小风:3 m/s,中风:7 m/s,大风:12 m/s),持续吹风105d,定量分析长期大风作用下木本猪毛菜地上部分的生长和空间构型的变化。结果表明:(1)风胁迫减小了木本猪毛菜的株高,增大了其顺风向的基径;大风减小了木本猪毛菜的叶片长度,中风和小风对其叶片长度没有影响;大风和中风增加了木本猪毛菜的叶片数,小风对叶片数没有影响。(2)木本猪毛菜植冠的空间构型在迎风面和背风面出现明显的不对称性;风胁迫减小了木本猪毛菜的主茎弯曲角度、叶倾角;大风和小风减小了木本猪毛菜的冠幅,中风没有影响;大风和中风减小了木本猪毛菜的枝倾角,小风没有影响;木本猪毛菜在大风和中风作用下出现了二级分枝,在小风作用下没有出现二级分枝。木本猪毛菜主要通过减小自身的扩大生长,增加空间构型的不对称性,减小枝与叶的受力面积等方式来降低风的阻力,以适应长期大风。     

Characterization of an urban-rural CO<Subscript>2</Subscript>/temperature gradient and associated changes in initial plant productivity during secondary succession

To examine the impact of climate change on vegetative productivity, we exposed fallow agricultural soil to an in situ temperature and CO₂ gradient between urban, suburban and rural areas in 2002. Along the gradient, average daytime CO₂ concentration increased by 21% and maximum (daytime) and minimum (nighttime) daily temperatures increased by 1.6 and 3.3°C, respectively in an urban relative to a rural location. Consistent location differences in soil temperature were also ascertained. No other consistent differences in meteorological variables (e.g. wind speed, humidity, PAR, tropospheric ozone) as a function of urbanization were documented. The urban-induced environmental changes that were observed were consistent with most short-term (~50 year) global change scenarios regarding CO₂ concentration and air temperature. Productivity, determined as final above-ground biomass, and maximum plant height were positively affected by daytime and soil temperatures as well as enhanced [CO₂], increasing 60 and 115% for the suburban and urban sites, respectively, relative to the rural site. While long-term data are needed, these initial results suggest that urban environments may act as a reasonable surrogate for investigating future climatic change in vegetative communities.     

Study on the Traffic Air Pollution inside and outside a Road Tunnel in Shanghai,China

To investigate the vehicle induced air pollution situations both inside and outside the tunnel, the field measurement of the pollutants concentrations and its diurnal variations was performed inside and outside the Xiangyin tunnel in Shanghai from 13:00 on April 24th to 13:00 on April 25th, 2013. The highest hourly average concentrations of pollutants were quantified that CO, NO, NO₂ and NO_X inside the tunnel were 13.223 mg/m³, 1.829 mg/m³, 0.291 mg/m³ and 3.029 mg/m³, respectively, while the lowest ones were 3.086 mg/m³, 0.344 mg/m³, 0.080 mg/m³ and 0.619 mg/m³. Moreover, the concentrations of pollutants were higher during the daytime, and lower at night, which is relevant to the traffic conditions inside the tunnel. Pollutants concentrations inside the tunnel were much higher than those outside the tunnel. Then in a case of slow wind, the effect of wind is much smaller than the impact of pollution sources. Additionally, the PM_2.5 concentrations climbed to the peak sharply (468.45 µg/m³) during the morning rush hours. The concentrations of organic carbon (OC) and elemental carbon (EC) in PM_2.5 inside the tunnel were 37.09–99.06 µg/m³ and 22.69–137.99 µg/m³, respectively. Besides, the OC/EC ratio ranged from 0.72 to 2.19 with an average value of 1.34. Compared with the results of other tunnel experiments in Guangzhou and Shenzhen, China, it could be inferred that the proportion of HDVs through the Xiangyin tunnel is relatively lower.     

Analysis of the emission of SO2, NOx,and suspended particles from the thermal power plants Kostolac (Serbia)

The environmental situation related to the thermal power basin of Kostolac for the most part represents the result of the influence of the thermal power plants (TPPs) of Kostolac A, Kostolac B, and the open-pit lignite mine. The quality of air is monitored by continuously measuring concentrations of the overall precipitation matters and gases such as CO₂, SO₂, NO_x, CO, and O₃. Values significantly exceeding the legal limits have been found for pollutants in the surroundings of the TPPs Kostolac A and B and in the direction of dominant winds. The paper analyzes the impact of different scenarios of emission of harmful matters from the blocks of TPPs Kostolac A and B on the quality of air in this part of Serbia. The Gaussian model has been used to evaluate dispersion of gas substances and suspended particulates as well as parameters related to the surroundings. Calculations have been made relating to ground-level concentrations of sulfur dioxide, nitrogen oxide, and suspended particles at varying distances from the emission source.     

基于CFD模拟的不同地形格局风场规律及其风感规划对策

近地表地形的风场受坡度坡向、地表形态和空间格局等地形要素的控制,从而影响人的"风感"体验,是人居环境的选址与布局需要考虑的重要因素。通过建立地形3D模型、划分网格、设定模拟工况,运用Fluent 14.0软件对不同山体地形坡度、形态和格局的风场进行CFD （Computational Fluid Dynamics）模拟。结果发现：（1）坡度在0.3以下对地形风场影响较小;当坡度大于0.5时,随坡度增大背风坡风影区逐渐增大,挡风效果更加明显;坡度大于0.7以后,随着风影区加大,回流涡旋更加明显。（2）风场受到周边地形形体的影响,尤其是迎风面和背风面截面变化率。迎风面截面变化率越大,风速变化越快;背风面截面变化越大,背风面的出现风影区和回流涡旋的几率越大。迎风面出现凹形迎风口会形成气体滞留区,而背风面凹形口后部会增加风影区和回流涡旋出现的几率。（3）不同地形格局对单个地形的风场具有强化和减弱效果。"三面环山"的相对封闭的地形格局有利于形成稳定的风场,并提高风感舒适度。在人居环境的风感营造和优化中,需要避开风感敏感区域,即风速激增区、回流涡旋区、无固定风向的强烈湍流区、气流不流通的静风区和气流死循环涡旋区等风感敏感区,并利用植被或者人工构筑物来消除敏感区或削弱这一影响。并根据不同的气候类型和城市特点进行选址、地形改造或者进行内部地形格局调整和优化,以提高风感舒适度。选择开放型地形格局和低坡度、平行风向的流线型地形能够加强通风,而塑造封闭性地形格局和垂直风向的陡坡地形能够减小风速。     

Bioconversion of synthesis gas to hydrogen using a light-dependent photosynthetic bacterium,Rhodospirillum rubrum

Biological hydrogen production from synthesis gas was carried out in batch culture. The phototrophic anaerobic bacterium, Rhodospirillum rubrum was used to oxidize CO and water to CO₂ and hydrogen. The bacteria were grown under anaerobic conditions in liquid medium; also acetate was used as carbon source in presence of synthesis gas. Biological hydrogen production was catalysed by R. rubrum via the water–gas shift reaction. A light-dependent cell growth modelled with a desired rate of hydrogen production and CO uptake was determined. The effect of light intensity on microbial cell growth was also studied at 500, 1,000 and 1,500 m.cd. A complete conversion of CO to hydrogen and maximum light efficiency were obtained with an acetate concentration of 1 g/l and light intensity of 500 m.cd. Utilization of the carbon monoxide from the gas phase was often considered as a mass transfer limited process, which needed to diffuse through the gas–liquid interface and then further diffuse into liquid medium prior to reaction. The results from this study showed that maximum cell propagation and hydrogen production were achieved with a limited light intensity of 1,000 m.cd. It was also found that high-light intensity may interfere with cell metabolism. In low-light intensity and substrate concentration, no inhibition was observed, however at extreme conditions, non-competitive inhibition was identified. The adverse effect of high-light intensity was shown at 5,000 m.cd, where the CO conversion drastically dropped to as low as 21%. Maximum CO conversion of 98% and maximum yield of 86% with an acetate concentration of 1.5 g/l and a light intensity of 1,000 m.cd were achieved.     

Robust Thin Films‐Based Triboelectric Nanogenerator Arrays for Harvesting Bidirectional Wind Energy

Wind‐driven triboelectric nanogenerators (TENGs) play an important role in harvesting energy from ambient environments. Compared to single‐side‐fixed triboelectric nanogenerator (STENG) arrays for harvesting single‐pathway wind energy, double‐side‐fixed triboelectric nanogenerator (DTENG) arrays are developed to harvest bidirectional wind energy. Electrical performances of the STENG and DTENG can be improved due to sticky, abrasive, and electrical properties of the Ti buffer layers among Al, polytetrafluoroethylene (PTFE), and polyimide (Kapton), configuring in triboelectric PTFE/Ti/Al and Al/Ti/Kapton/Ti/Al thin films. Short‐circuit current (I _SC), open‐circuit voltage (V _OC), and frequencies of the STENG and DTENG increase with increasing wind velocity ranging from 9.2 to 18.4 m s²¹, revealing that the moderate I _SC, V _OC, frequencies, and output powers of the STENG and DTENG reach 67 μA, 57 μA, 334 V, 296 V, 173 Hz, 162 Hz, 5.5 mW and 3.4 mW with a matched load of 4 MΩ at airflow rate of 15.9 m s²¹, respectively. Compared with counterparts of the single‐pathway‐harvested STENG arrays, the I _SC, durability, and stability of the bidirectional‐harvested DTENG can be dramatically improved by a 4 3 1 array connected in parallel because of the improved device configuration, stickiness, and abrasion by adhering Ti buffer layers. The durable DTENG arrays present a step toward practical applications in harvesting bidirectional wind energy for self‐powered systems and wireless sensors.