Kinetic modeling of enzymatic hydrolysis of cellulose in differently pretreated fibers from dairy manure

A kinetic model incorporating dynamic adsorption, enzymatic hydrolysis, and product inhibition was developed for enzymatic hydrolysis of differently pretreated fibers from a nitrogen-rich lignocellulosic material-dairy manure. The effects of manure proteins on the enzyme adsorption profile during hydrolysis have been discussed. Enzyme activity, instead of protein concentration, was used to describe the enzymatic hydrolysis in order to avoid the effect of manure protein on enzyme protein analysis. Dynamic enzyme adsorption was modeled based on a Langmiur-type isotherm. A first-order reaction was applied to model the hydrolysis with consideration being given for the product inhibition. The model satisfactorily predicted the behaviors of enzyme adsorption, hydrolysis, and product inhibition for all five sample manure fibers. The reaction conditions were the substrate concentrations of 10-50 g/L, enzyme loadings of 7-150 FPU/g total substrate, and the reaction temperature of 50 degrees C.     

Contribution of Dead Wood to Biomass and Carbon Stocks in the Caribbean: St. John, U.S. Virgin Islands

Dead wood is a substantial carbon stock in terrestrial forest ecosystems and hence a critical component of global carbon cycles. Given the limited amounts of dead wood biomass and carbon stock information for Caribbean forests, our objectives were to: (1) describe the relative contribution of down woody materials (DWM) to carbon stocks on the island of St. John; (2) compare these contributions among differing stand characteristics in subtropical moist and dry forests; and (3) compare down woody material carbon stocks on St. John to those observed in other tropical and temperate forests. Our results indicate that dead wood and litter comprise an average of 20 percent of total carbon stocks on St. John in both moist and dry forest life zones. Island-wide, dead wood biomass on the ground ranged from 4.55 to 28.11 Mg/ha. Coarse woody material biomass and carbon content were higher in moist forests than in dry forests. No other down woody material components differed between life zones or among vegetation categories ( P > 0.05). Live tree density was positively correlated with fine woody material and litter in the moist forest life zone ( R = 0.57 and 0.84, respectively) and snag basal area was positively correlated with total down woody material amounts ( R = 0.50) in dry forest. Our study indicates that DWM are important contributors to the total biomass and, therefore, carbon budgets in subtropical systems, and that contributions of DWM on St. John appear to be comparable to values given for similar dry forest systems.     

Can an indicator of river health be related to assessments from a catchment-scale sediment model?

The accumulation of sand and fine gravel (<5 mm diameter) on riverbeds can adversely affect benthic macroinvertebrates, which are good indicators of the ecological health of rivers. The possibility arises, therefore, that predictions of sedimentation could form a useful proxy for indicating the health of a river. The Sediment River Network Model (SedNet) constructs sediment budgets to predict the depth of bed material accumulation (BMA) in each link of a river network. This study tests whether the predicted BMA depth was associated with spatial differences in macroinvertebrate community structure, in the Upper Murrumbidgee River catchment of southeast Australia. There was a significant, albeit limited, correlation. Riffle sites with low BMA depth (0–0.01 m) had a significantly different macroinvertebrate community structure compared to sites with medium (0.01–0.3 m) or high (>0.3 m) BMA depth. At these sites, taxa sensitive to habitat were in greater abundance when BMA depth was low. Additionally, riffle sites with high predicted BMA depth had lower values for three macroinvertebrate community structure measures—AUSRIVAS observed-to-expected (OE) taxa ratio, Ephemeroptera abundance and Plecoptera abundance. There was no significant difference in macroinvertebrate community structure between sites with medium and high levels of BMA depth. Possible reasons for this result are: (1) there may have been few sites in the high and medium categories to provide sufficient statistical power to detect a significant difference; (2) spatial variation in BMA depth within SedNet river links; or (3) only a minimal amount of BMA is required to change community structure. To further define spatial variation in biological damage from BMA, data are required on the spatial scale of variations in BMA depth and damage to macroinvertebrate community structure.     

北草蜥卵孵化过程中物质和能量的动态

研究北草蜥卵在温、湿度分别为 3 0℃、 -12kPa的条件下 ,孵化过程中物质和能量的动用以及胚胎生长。孵化过程中 ,每隔 5天称量卵重。孵化第 10天起 ,每隔 5天解剖来自不同窝的卵 15枚 ,并分离成胚胎、卵壳和卵黄三组分。孵出幼体称重后冰冻处死 ,之后解剖分离成躯干、剩余卵黄和脂肪体。所有材料 65℃烘至恒重 ,用索氏脂肪提取器测定脂肪含量 ,氧弹热量计测定能值 ,马福炉测定灰分含量。本研究北草蜥卵的孵化期为 2 8 1天。卵孵化时从基质中吸水导致重量增加。卵孵化 0 -10天、 11-2 0天、 2 1-2 5天、 2 6-2 8天 ,胚胎分别利用新生卵能量的 12 %、 3 5%、 3 7%和 15%。 0 -10天 ,胚胎生长较缓慢 ;10天后生长迅速。卵孵化过程中 ,干物质、非极性脂肪和能量的转化率分别为 69 7%、 3 7 0 %和 53 1%。初生幼体的能量组分为 :躯干95 2 % ,脂肪 2 4% ,剩余卵黄 2 4%。本研究结果显示 :北草蜥从新生卵到孵出幼体的物质和能量转化率较低 ;胚胎发育所需要的无机物来自卵黄和卵壳     

人工雌核发育鲢的遗传多样性及异源遗传物质整入的RAPD分析

运用RAPD技术对连续二代人工雌核发育鲢的遗传多样性及异源遗传物质的整入进行了分析 ,结果表明 :一代雌核发育鲢 ,个体间遗传相似度为 0 94 5— 0 995 6 ,多样性指数为 0 175 ;二代雌核发育鲢 ,个体间遗传相似度为0 96 15— 1 0 0 ,平均为 0 985 2 ,多样性指数为 0 0 6 2。研究揭示经过连续二代人工雌核发育后 ,其遗传多样性明显减少 ,种质进一步纯化。通过对雌核发育鲢二代、亲本鲢和雄鲤的RAPD扩增比较 ,发现雌核发育鲢含有少数与父本相同的特异DNA扩增带 ,而亲本鲢没有 ,在基因水平上表明雌核发育鲢整入了雄鲤的遗传物质     

Modeling process and material alternatives in life cycle assessments

Background, Aims and Scope  Although LCA is frequently used in product comparison, many practitioners are interested in identifying and assessing improvements within a life cycle. Thus, the goals of this work are to provide guidelines for scenario formulation for process and material alternatives within a life cycle inventory and to evaluate the usefulness of decision tree and matrix computational structures in the assessment of material and process alternatives. We assume that if the analysis goal is to guide the selection among alternatives towards reduced life cycle environmental impacts, then the analysis should estimate the inventory results in a manner that: (1) reveals the optimal set of processes with respect to minimization of each impact of interest, and (2) minimizes and organizes computational and data collection needs. Methods  A sample industrial system is used to reveal the complexities of scenario formulation for process and material alternatives in an LCI. The system includes 4 processes, each executable in 2 different ways, as well as 1 process able to use 2 different materials interchangeably. We formulate and evaluate scenarios for this system using three different methods and find advantages and disadvantages with each. First, the single branch decision tree method stays true to the typical construction of decision trees such that each branch of the tree represents a single scenario. Next, the process flow decision tree method strays from the typical construction of decision trees by following the process flow of the product system, such that multiple branches are needed to represent a single scenario. In the final method, disaggregating the demand vector, each scenario is represented by separate vectors which are combined into a matrix to allow the simultaneous solution of the inventory problem for all scenarios. Results  For both decision tree and matrix methods, scenario formulation, data collection, and scenario analysis are facilitated in two ways. First, process alternatives that cannot actually be chosen should be modeled as sub-inventories (or as a complete LCI within an LCI). Second, material alternatives (e.g., a choice between structural materials) must be maintained within the analysis to avoid the creation of artificial multi-functional processes. Further, in the same manner that decision trees can be used to estimate ‘expected value’ (the sum of the probability of each scenario multiplied by its ‘value’), we find that expected inventory and impact results can be defined for both decision tree and matrix methods. Discussion  For scenario formulation, naming scenarios in a way that differentiate them from other scenarios is complex and important in the continuing development of LCI data for use in databases or LCA software. In the formulation and assessment of scenarios, decision tree methods offer some level of visual appeal and the potential for using commercially available software/ traditional decision tree solution constructs for estimating expected values (for relatively small or highly aggregated product systems). However, solving decision tree systems requires the use of sequential process scaling which is difficult to formalize with mathematical notation. In contrast, preparation of a demand matrix does not require use of the sequential method to solve the inventory problem but requires careful scenario tracking efforts. Conclusions  Here, we recognize that improvements can be made within a product system. This recognition supports the greater use of LCA in supply chain formation and product research, development, and design. We further conclude that although both decision tree and matrix methods are formulated herein to reveal optimal life cycle scenarios, the use of demand matrices is preferred in the preparation of a formal mathematical construct. Further, for both methods, data collection and assessment are facilitated by the use of sub-inventories (or as a complete LCI within an LCI) for process alternatives and the full consideration of material alternatives to avoid the creation of artificial multi-functional processes. Recommendations and Perspectives  The methods described here are used in the assessment of forest management alternatives and are being further developed to form national commodity models considering technology alternatives, national production mixes and imports, and point-to-point transportation models. ESS-Submission Editor: Thomas Gloria, PhD (t.gloria@fivewinds.com)     

Material properties of manatee rib bone

Watercraft-related mortality of the Florida manatee Trichechus manatus latirostris accounts for 24% of all deaths from 1974 to 2006. Of these, the proportion of deaths due to impact accounts for 66% of all watercraft fatalities. To establish safe boat speeds for manatee protection, an estimate of the material properties of their bone is needed to quantify the biomechanical effects of boat strikes on manatees. Manatee ribs are unique in that they are pachyostotic. Machined specimens from ribs were tested in three point flexure. Strength, modulus, work of fracture and fracture toughness were determined for three size classes, by sex. The mean flexural strength ranged from 62 to 160 MPa, elastic modulus from 4 to 18 GPa and work of fracture from 3 to 6 MJ m⁻³. Fractographic analysis was used to calculate toughness, which averaged 1.4–2.9 MPa m^1/2. The results show that manatee bone material is less strong and tough than other mammalian bone. Although the bone increases in static strength as the animals grow, it is not able to absorb more energy. In fact, the ability to absorb impact energy appears to decline with increasing size in animals over 265 cm body length. This decline is due in part to the bone's high density and mineral content. There was little change in mineral content with size, suggesting that material properties are likely correlated with bone quantity. There were no differences in mechanical variables between the sexes. The pachyostotic nature of the bone, which makes the manatee well adapted to its environment, also leaves it highly susceptible to fatal injuries from boats.     

Demand for biomass to meet renewable energy targets in the United States: implications for land use

Renewable energy policies in the electricity and transportation sectors in the United States are expected to create demand for biomass and food crops (corn) that could divert land from food crop production. We develop a dynamic, open‐economy, price‐endogenous multi‐market model of the US agricultural, electricity and transportation sectors to endogenously determine the quantity and mix of bioenergy likely to be required to meet the state Renewable Portfolio Standards (RPSs) and the federal Renewable Fuel Standard (RFS) if implemented independently or jointly (RFS & RPS) over the 2007–2030 period and their implications for the extent and spatial pattern of diversion of land from other uses for biomass feedstock production. We find that the demand for biomass ranges from 100 million metric tons (MMT) under the RPS alone to 310 MMT under the RFS & RPS; 70% of the biomass in the latter case can be met by crop and forest residues, while the rest can be met by devoting 3% of cropland to energy crop production with 80% of this being marginal land. Our findings show significant potential to meet current renewable energy goals by expanding high‐yielding energy crop production on marginal land and using residues without conflicting with food crop production.     

The biological standard of living in pre-modern Korea: Determinants of height of militia recruits during the Chosŏn dynasty

This paper extends the research on the biological standard of living in the Korean peninsula back to pre-modern times. Drawing on militia rosters of the Chosŏn Dynasty from the sixteenth to eighteenth centuries, we tentatively conclude that the final height of Korean men during this period was 166 cm and thus slightly above that of modern North Korean men (165 cm). On the other hand, the average height of modern South Korean men is 172 cm, 6 cm more than what we tentatively estimate for pre-modern Korean men. Regression analysis of the height of pre-modern Korean men finds that un-free Koreans (“slaves”) were significantly shorter by about 0.6–0.7 cm than commoners, whereas the average height of recruits suffering from smallpox did not differ significantly from that of other recruits. Moreover, regional, as opposed to birth-dummy, variables account, and to a significant degree, for most of the differences in height. Whether or not this is a result of socioeconomic differences across provinces or a result of other regionally-varying factors remains an open question.     

黄芩汤药效物质基础及其治疗胃肠道疾病研究进展

黄芩汤是《伤寒论》中治疗下痢的经典方剂,由黄芩、芍药、甘草(炙)和大枣四味中药煎煮而成,用于治疗痢疾、腹泻等胃肠道疾病已有近1800年,中药治疗胃肠道疾病相较于西药更安全。本文结合国内外相关文献,对近几年来黄芩汤药效物质基础研究进行概括总结,并对其治疗溃疡性结肠炎和减轻化疗药物胃肠道毒性机制的最新研究进行了综述,结合胃肠道疾病的发病机制以及黄芩汤减毒机制的研究方法对现有研究过程中存在的不足进行了评述,并对中药疗效研究展开设想,提出以组学作为研究手段,配合中药复方整体作用模式的组分-疗效研究思路,以期为黄芩汤治疗胃肠道疾病的研究提供参考。