导向喷动流化床生物质快速裂解制液体燃料

在冷模试验得到的优化的结构参数基础上，建立了一套生物质最大处理量为5kg／h的导向管喷动流化床生物质裂解反应器。反应在常压和440～520℃进行，以木屑为生物质原料，二氧化碳和氮气为喷动气或流化气，沙子为流化介质。结果表明该喷动流化床反应器可用于生物质的快速裂解。在400～480℃，液体产率随温度增加而上升，高于480℃时，二次反应的加剧又导致液体产品产率下降。固体和气体的产率则随温度的升高而减少。喷动气和流化气流量的增加均强化了反应器内的传热，并使生物质初始裂解产物的停留时间减少，二次反应进行程度减弱。在适当的裂解条件下液体产率可达73．2％，此时气体和焦的产率分别为12．8％和14．0％。所得液体产品为单一相液体，含水约30％，可用于燃烧。与流化床相比，喷动流化床作为生物质快速裂解反应器可明显提高液体产率。     

一株曲霉果糖转移酶的发酵条件及转果糖基活性

对一株曲霉果糖转移酶菌株的产酶培养条件进行了研究。确定了最佳培养基组成：初始蔗糖质量浓度15～18g／dL，氮源为酵母膏，K2HPO4对果糖转移酶的产生具有明显的促进作用，添加0．2g／dLCMC能够使果糖转移酶活力提高到原来的1．3倍，在pH5．5，30℃条件下，果糖转移酶最高酶活力为30．42U／mL。HPLC分析结果表明，转糖基产物为总质量的55．8％。     

Biomass fuel exposure and asthma symptoms among rural school children in Nigeria

Background: Approximately 70% of rural Nigerian households rely on biomass fuels for cooking. The International Study of Asthma and Allergies in Childhood (ISAAC) estimates the prevalence of current wheeze among children in Nigeria to have risen from 10.7% in 1999 to approximately 20% in 2014. Objective: To examine the effects of biomass smoke exposure on asthma symptom prevalence in rural children in Nigeria. Methods: We conducted a cross-sectional survey in rural communities in Nigeria. Asthma symptoms were defined according to ISAAC definitions. Biomass smoke exposure was determined by the types of fuel used for cooking. Logistic regression was used to explore associations between biomass smoke and asthma symptoms. Results: The study population comprised 1,690 school children, of which 865 lived in households cooking with biomass and 825 lived in households not using biomass. Asthma symptoms were reported in 481 (28.5%) children. Biomass fuel was associated with increased odds of asthma symptoms. Adjusted odds ratios (aORs) were 1.38 (95% CI: 1.05–1.80) for nocturnal cough, 1.26 (95% CI: 1.00–1.61) for current wheeze, and 1.33 (95% CI: 1.05–1.69) for report of any asthma-related symptoms. Sex modified the associations between asthma symptoms with biomass fuel: aORs were stronger and significant for males (nocturnal cough = 1.85, 95% CI: 1.24–2.76; current wheeze = 1.48, 95% CI: 1.03–2.13; report of any asthma-related symptoms = 1.60, 95% CI: 1.12–2.28), but weaker and non-significant for females.Conclusion: The risk of asthma symptoms related to biomass smoke exposure appears to differ by sex.     

Long‐Term Exposure to Biomass Fuel and Its Relation to Systolic and Diastolic Biventricular Performance in Addition to Obstructive and Restrictive Lung Diseases

Background: Previous studies have demonstrated an increased risk for cardiovascular events and pulmonary disease in patients with biomass fuel exposure (BFE). However, biventricular heart function has yet to be investigated in these patients. Left ventricular (LV) myocardial performance index (LVMPI), which is an index of global ventricular function, incorporates ejection, isovolumic relaxation, and contraction times. In this study, pulmonary function and biventricular heart function were investigated in nonsmoking female patients with BFE. Methods: Our study population consisted of 46 female patients with BFE (group 1) and 31 control subjects (group 2). Pulmonary function tests and transthoracic echocardiographic examination were performed. Right ventricular myocardial performance index (RVMPI) and LVMPI were obtained by tissue Doppler imaging echocardiography (TDI). Results: BFE caused obstructive and restrictive spirometric impairments. RVMPI was higher in group 1 (0.55 ± 0.07) than group 2 (0.46 ± 0.06) (P = 0.042) and LVMPI was higher in group 1 (0.54 ± 0.08) than group 2 (0.47 ± 0.05) (P = 0.032). Also, pulmonary artery systolic pressure was higher in group 1 than group 2 (P = 0.02). Conclusions: BFE causes both obstructive and/or restrictive lung disease and systolic and diastolic biventricular dysfunction. Nonetheless, long‐term studies are needed to understand on BFE‐related ventricular dysfunctions and to document subsequent cardiovascular events. (Echocardiography 2011;28:52‐61)     

Rapid dark aging of biomass burning as an overlooked source of oxidized organic aerosol

Oxidized organic aerosol (OOA) is a major component of ambient particulate matter, substantially impacting climate, human health, and ecosystems. OOA is readily produced in the presence of sunlight, and requires days of photooxidation to reach the levels observed in the atmosphere. High concentrations of OOA are thus expected in the summer; however, our current mechanistic understanding fails to explain elevated OOA during wintertime periods of low photochemical activity that coincide with periods of intense biomass burning. As a result, atmospheric models underpredict OOA concentrations by a factor of 3 to 5. Here we show that fresh emissions from biomass burning exposed to NO₂ and O₃ (precursors to the NO₃ radical) rapidly form OOA in the laboratory over a few hours and without any sunlight. The extent of oxidation is sensitive to relative humidity. The resulting OOA chemical composition is consistent with the observed OOA in field studies in major urban areas. Additionally, this dark chemical processing leads to significant enhancements in secondary nitrate aerosol, of which 50 to 60% is estimated to be organic. Simulations that include this understanding of dark chemical processing show that over 70% of organic aerosol from biomass burning is substantially influenced by dark oxidation. This rapid and extensive dark oxidation elevates the importance of nocturnal chemistry and biomass burning as a global source of OOA.

Highly oxidized organic aerosol (OOA) is a dominant component of particulate matter air pollution globally (1–3); however, sources of OOA remain uncertain, limiting the ability of models to accurately represent OOA and thus predict the associated climate, ecosystem, and health implications (4, 5). The current conceptual model of OOA formation suggests that anthropogenic OOA predominantly originates from the oxidation of volatile (VOCs), intermediate volatility (IVOCs), and semivolatile (SVOCs) organic compounds by the OH radical, resulting in lower-volatility products that condense to the particle phase (6). As the OH radical is formed through photolysis and has a very short atmospheric lifetime [less than a second (7)], this oxidation mechanism only occurs in the presence of sunlight. Further, the time scale for OOA formation through oxidation with OH in models is on the order of a few days (8). While this understanding is sufficient in explaining OOA concentrations in summer or periods with high solar radiation, atmospheric models fail to reproduce the observed concentration of OOA in the ambient atmosphere during winter and low-light conditions (9, 10). Fountoukis et al. (9) found simulated OOA concentrations significantly underestimated in wintertime Paris. Tsimpidi et al. (10) also reported an underprediction of simulated OOA globally in winter, suggesting missing sources of both primary OA (POA) and secondary formation pathways. This underproduction suggests a possible overlooked conversion pathway of organic vapors or particles to OOA that is not accounted for in current chemical transport and climate models.As stricter controls on fossil fuel combustion are implemented, residential biomass burning (BB) as a source of heating or cooking is becoming an increasingly important source of OA in urban environments (1, 11, 12). Further, increasing rates of wildfires from climate change are increasing the frequency of smoke-impacted days in urban areas (12–14). BB emissions include high concentrations of POA, SVOCs, IVOCs, and VOCs (15, 16), thus making BB a key source of OOA. Previous research has focused on quantifying the concentration of OOA formed through photochemical oxidation reactions (i.e., OH) with BB emissions (17, 18). However, oxidation of BB emissions in low or no sunlight is less well understood and is not included in chemical transport models. As opposed to OH, the NO₃ radical is formed through reactions with NO₂ and O₃ and is rapidly lost in the presence of sunlight (19). Thus, the NO₃ radical is only available in significant concentrations at night or other low-light conditions (20, 21). Previous research has established that biogenic VOCs may undergo oxidation at night when mixed with anthropogenic emissions containing NO₂ and O₃ (19, 22–27). There have been only a few studies that consider that nighttime oxidation of residential wood combustion may proceed through similar pathways (28–31); however, the magnitude and relevance to observed OOA in the ambient atmosphere has not yet been established. By combining laboratory experiments and ambient observations to inform a chemical transport model, we present strong evidence that nighttime oxidation of BB plumes (proceeding through reactions with O₃ and the NO₃ radical) is an important source of OOA.     

Reductions in NO2 burden over north equatorial Africa from decline in biomass burning in spite of growing fossil fuel use, 2005 to 2017

Socioeconomic development in low- and middle-income countries has been accompanied by increased emissions of air pollutants, such as nitrogen oxides [NO_x: nitrogen dioxide (NO₂) + nitric oxide (NO)], which affect human health. In sub-Saharan Africa, fossil fuel combustion has nearly doubled since 2000. At the same time, landscape biomass burning—another important NO_x source—has declined in north equatorial Africa, attributed to changes in climate and anthropogenic fire management. Here, we use satellite observations of tropospheric NO₂ vertical column densities (VCDs) and burned area to identify NO₂ trends and drivers over Africa. Across the northern ecosystems where biomass burning occurs—home to hundreds of millions of people—mean annual tropospheric NO₂ VCDs decreased by 4.5% from 2005 through 2017 during the dry season of November through February. Reductions in burned area explained the majority of variation in NO₂ VCDs, though changes in fossil fuel emissions also explained some variation. Over Africa’s biomass burning regions, raising mean GDP density (USD⋅km⁻²) above its lowest levels is associated with lower NO₂ VCDs during the dry season, suggesting that economic development mitigates net NO₂ emissions during these highly polluted months. In contrast to the traditional notion that socioeconomic development increases air pollutant concentrations in low- and middle-income nations, our results suggest that countries in Africa’s northern biomass-burning region are following a different pathway during the fire season, resulting in potential air quality benefits. However, these benefits may be lost with increasing fossil fuel use and are absent during the rainy season.

Socioeconomic development and population growth in low- and middle-income countries have been widely associated with increased environmental degradation, including rapid increases in emissions of air pollutants (1–3). In contrast, in countries with a high per capita gross domestic product (GDP), various socioeconomic, institutional, and regulatory factors often cause economic growth to be accompanied by reductions of some pollutant emissions, though these emissions may simply be outsourced to lower income countries (4). The relationship between income level and environmental pressure—known as the Environmental Kuznets Curve—has often been conceptualized as an inverted U-shaped curve, but a wide array of functional relationships is possible (3). For emissions of air pollutants, the relationship has generally been described as an inverted U-shaped curve, though carbon dioxide generally does not follow such a curve (3, 5). Some researchers argue that low- and middle-income countries can mitigate or shorten the period of rapid emissions growth that tends to accompany socioeconomic development for at least some pollutants (4). Africa, and sub-Saharan Africa in particular, is characterized by countries with low but growing per capita GDP and rapid population growth, which have been linked to increases in emissions of carbon dioxide and particulate matter (6). As these countries continue their trajectories of economic development, emissions of air pollutants from fossil fuel and biofuel combustion are expected to experience explosive growth (7).Nitrogen dioxide (NO₂) is a reactive gas and air pollutant with a lifetime in the atmosphere on the order of hours (8). In the atmosphere, NO₂ interconverts rapidly with nitric oxide (NO), and the two species are collectively referred to as NO_x. NO₂ itself is toxic, is regulated by the US Environmental Protection Agency, and has been associated with premature mortality and asthma [though its direct effects on health are not clear (9) and it may instead function as a proxy for other pollutants, such as ozone and aerosols that have direct health and mortality impacts (10)]. NO_x is also a key precursor to the formation of tropospheric ozone (O₃), which is damaging to both crop productivity and human health; anthropogenic O₃ contributes to roughly half a million premature deaths annually, of which nearly 20,000 are in Africa (11). In addition, NO_x is involved in reactions with atmospheric ammonia (NH₃) to form nitrate aerosols, which contribute to particulate matter pollution (12) as well as in reactions with volatile organic compounds (VOCs), which form organic nitrates (13). Because of the short lifetime of NO₂, and because it can function as an indicator for other pollutants, it can serve as an indicator of overall changes in air quality.NO and NO₂ are emitted from a variety of natural and anthropogenic sources. Fossil fuel combustion and anthropogenic alterations to soils through fertilization or livestock management are the primary sources of NO_x in many parts of the world. In sub-Saharan Africa (excluding South Africa), fossil fuel combustion and fertilizer use has been considerably lower than elsewhere, and natural soils and biomass burning have historically been more important sources (14). This is true even in Nigeria (15), which experiences substantial emissions of VOCs from the oil and gas industry (16). NO_x emissions from Lagos have been shown to be either lower than (15) or comparable to other megacities (17), and NO₂ concentrations are generally low during the rainy season, but air quality can become heavily degraded during the biomass burning season (15, 18). However, fossil fuel combustion in the region nearly doubled between 2000 and 2016 (19) and associated emissions of NO_x are projected to increase sixfold by 2030 in the absence of regulation, as compared to 2005 levels (7).This increase in fossil fuel combustion is occurring against the backdrop of Africa’s unique, fire-prone savanna ecosystems, home to 70% of the global area burned each year (20). Biomass burning in Africa is estimated to be responsible for NO_x emissions of roughly 4 Tg N⋅yr⁻¹, equivalent to about half of all NO_x emissions for the continent (21), and one third to half of NO_x emissions from biomass burning globally (21–23). The majority of biomass burning in Africa occurs in northern and southern bands of savanna, savanna-forest mosaic, and woodland ecoregions, with a seasonality that follows the migration of the intertropical convergence zone.The early part of the 21st century has been accompanied by a global decline in burned area, with some of the largest declines occurring in Africa’s northern fire band (24). Some of the burned area decline in the northern fire band can be attributed to changes in precipitation that, in turn, affect the quantity and moisture content of available fuels (24–26). However, active anthropogenic suppression of fire has also played an important role (24, 25). Burning is thought to be used as a management strategy—among other uses, humans ignite fires to mineralize nutrients, improve grazing, and reduce fuel loads and the potential for large, uncontrolled fires (27). Increased population density and the introduction of agricultural land into African savanna landscapes—reflecting socioeconomic transitions from traditional nomadic pastoralist lifestyles (28)—have been associated with a sharp decrease in burned area as people either reduce ignition or suppress fires to protect villages and farms, with a reduction in the amount of pasture area to be maintained (25).Unfortunately, sub-Saharan Africa remains a severely understudied region—for example, agricultural soil NO fluxes have only been measured directly for two sites (29, 30), and surface air quality monitoring is extremely limited compared to other parts of the world (31). Remote sensing products provide an important tool for filling some of these data gaps. The short NO₂ lifetime in the planetary boundary layer makes it possible to use satellite observations to directly evaluate emissions sources, especially in regions with high temperatures, which tend to shorten the NO₂ lifetime, and in relatively polluted regions, where total column densities and surface emissions are highly correlated (ref. 8 and references therein). Although recent remote sensing work has evaluated long-term trends in NO₂ concentrations around the world, recent trends in the biomass burning region of northern Africa have not been explicitly evaluated, and the relative impacts of socioeconomic development—the possibility of reduced NO_x emissions because of anthropogenic fire suppression and of increasing NO_x emissions from growing fossil fuel use—remain unknown. In general, studies on global trends in NO₂ tend not to focus on Africa, likely because the regions with the highest NO₂ concentrations are in China, Europe, and the United States (e.g., refs. 1, 21). Some earlier studies observed a decline in NO₂ VCDs over north equatorial Africa (32, 33), but others did not (34). These and other large-scale studies (e.g., refs. 8, 34, 35) did not identify mechanisms for the observed NO₂ dynamics, but rather focused on understanding anthropogenic influences on trends in other regions.Indoor air pollution from biomass combustion for fuel is an important health concern (36). We do not focus on this source. Biofuel combustion is responsible for emissions of 0.6 Tg NO annually across all of Africa (37), which is less than 10% of the magnitude of landscape biomass burning emissions estimated by the Global Fire Emissions Database version 4s [GFED4s (38)] and represents a much smaller proportion of NO_x emissions from landscape biomass burning regions during the dry season.Here, we use observations of NO₂ by the Ozone Monitoring Instrument [OMI (39)] and burned area from the Moderate Resolution Imaging Spectroradiometer [MODIS (40)] to demonstrate that the recent decline in burned area in the productive savannas of north equatorial Africa—home to over 275 million people—is associated with large declines in tropospheric NO₂ VCDs during the biomass burning season from 2005 through 2017, though positive trends explained in part by increasing fossil fuel combustion were observed in other seasons, especially over Nigeria.     

Chronic Obstructive Pulmonary Disease and its Non-Smoking Risk Factors in India

The rising prevalence of the chronic obstructive pulmonary disease (COPD) is generally attributed to smoking, since the role of other risk factors among non-smokers are not well established especially in low and middle income countries like India. This is also reflected by the limited literature available on non-smoking related COPD risk factors like indoor and outdoor air pollution. The present review is an attempt to assess the influence of non-smoking risk factors on COPD and its measures in Indian subcontinent. The most noteworthy factors among non-smokers appear to be the use of biomass fuel for cooking and heating purposes. We observed that the studies undertaken to evaluate the role of such risk factors are inconclusive due to weak methodologies and small sample sizes, may be due to limited financial resources. The present review suggests the need of a nationally representative study to estimate the effect of each of the potential modifiable risk factor (other than smoking) for framing impactful public health policies to prevent and manage COPD at community and population level in India.     

Ethnopharmacological Studies of Tribulus Terrestris (Linn). in Relation to Its Aphrodisiac Properties

Synergism and antagonism impact of different plant metabolites present in crude fruit extract of Tribulus terrestris ‘the herbal Viagra’ have been studied. Variability in plant composition, biomass and metabolites concentration in different modules was significantly contributed by spatial factor. However the edhaphic parameters also changes with both spatial and temporal factors significantly. Fruit is the officinal part and the fruit production significantly related with soil nitrogen (P<0.01), whereas the soil nitrogen and pH also influenced the alkaloid content in fruit (P<0.05). The linear relation between fruit protein and fruit alkaloid (P<0.01) also observed and the relationship in between different soil parameters were established. Bioassay work confirmed its aphrodisiac properties, and site III is suggested for maximum biomass and high concentration of different metabolites.     

Converting diameter measurements of Pinus radiata taken at different breast heights

Two compatible conversion factors for converting diameter measurements taken at different breast heights were derived for Pinus radiata using taper data from more than 3000 trees. The two breast heights used for conversion were 1.3 and 1.4 m above ground, as defined in Australia and New Zealand, two major radiata-growing countries in the world. The conversion factors were estimated through three alternative statistical methods including simple least squares regression, seemingly unrelated regression and errors-in-variables models. The three sets of estimates were almost identical and had similar conversion accuracy, although the second method was slightly better. The conversion factors were more accurate than overbark taper equations used for the same purpose. The factor was 0.9916 for converting diameter measured at 1.3 to that at 1.4 m above ground, and the inverse of this value, 1.0084, was for the vice versa. When calculating tree and stand volume and biomass using equations with diameter at a different breast height as a predictor to that of the input data, the bias, either over or under estimation, could be between 1.67% and 2.00% without conversion. These conversion factors will facilitate the sharing of data among radiata growing countries with different definitions of breast height, but more importantly it will help correct the bias in stand volume and biomass estimation caused by the seemingly negligible difference in breast height when software for forest resource management and decision support developed in one country is applied in another. Such bias when accumulated over a large management area may not be financially insignificant for an astute forest management agency.