Did ice-age bovids spread tuberculosis?

Pathognomonic metacarpal undermining is a skeletal pathology that has been associated with Mycobacterium tuberculosis in bovids. Postcranial artiodactyl, perissodactyl, and carnivore skeletons were examined in major university and museum collections of North America and Europe for evidence of this and other pathology potentially attributable to tuberculosis. Among nonproboscidean mammals from pre-Holocene North America, bone lesions indicative of tuberculosis were restricted to immigrant bovids from Eurasia. No bone lesions compatible with diagnosis of tuberculosis were found in large samples of other pre-Holocene (164 Oligocene, 397 Miocene, and 1,041 Plio–Pleistocene) North American mammals, including 114 antilocaprids. Given the unchanged frequency of bovid tubercular disease during the Pleistocene, it appears that most did not die from the disease but actually reached an accommodation with it (as did the mastodon) (Rothschild and Laub 2006). Thus, they were sufficiently long-lived to assure greater spread of the disease. The relationships of the proboscidean examples need further study, but present evidence suggests a Holarctic spread of tuberculosis during the Pleistocene, with bovids acting as vectors. While the role of other animals in the transmission of tuberculosis could be considered, the unique accommodation achieved by bovids and mastodons makes them the likely “culprits” in its spread.     

掺硅碳羟基磷灰石的制备及其对Pb2+的吸附性能

以废弃蛋壳、硅酸钠为原料,采用水热法制备掺硅碳羟基磷灰石(Ca10(PO4)6-x-y(SiO4)x(CO3)y(OH)2-x-y,Si-CHAP),研究其对溶液中Pb2+子的吸附性能.采用BET比表面积、红外光谱、X光衍射、扫描电镜等分析手段对样品进行表征,实验考察了pH值、反应时间以及温度等对Si-CHAP吸附Pb2+的影响.结果表明,Si-CHAP是一种具有较大比表面积的介孔材料,其比表面积为323.25m2/g.Pb2+初始浓度为300mg/L并加入2g/L的吸附剂,室温下反应时间90min后,Si-CHAP对溶液中铅离子去除率和吸附容量分别为99.39%和149.09mg/g. Langmuir等温吸附方程能较好描述铅离子在Si-CHAP上的吸附平衡,准二级动力学方程式描述铅离子在Si-CHAP上吸附的最佳吸附动力学模型,热力学参数表明Si-CHAP吸附铅离子是自发、吸热和熵值增加过程.     

Non-equilibrium phenomena in carbon dioxide expansion

Release of liquid and supercritical carbon dioxide is a fundamental research topic in CCS. Traditional approach is largely based on HEM and, in general, assumes equilibrium from the outlet to the Mach disc. Experimental results have shown that this approach is not always effective in describing the expansion phenomenon; therefore a significant lack of knowledge exists about CO₂ properties at the under-expanded jet zone boundary, which is a main focus in process safety. Here, solid formation, vapour quality, sonic velocity and final temperature are generally calculated according to equilibrium saturation condition, and this is generally incorrect. This article deals with non-equilibrium thermodynamics of liquid and supercritical CO₂ expansion, illustrating relaxation dynamics through the HRM models, and discussing the very specific singularities of CO₂ phase transitions, vapour to liquid and liquid to solid, that result away from the equilibrium condition, due to the rapid phase changes and to the specific properties of CO₂ multi phase thermodynamics, including nucleation and particle growth. Statistical rate theory has been applied with the aim at identifying the phase transition energy barrier, resulting in a significant entropy increase. A case study based on HEM conservation equations integrated with the statistical rate approach has been presented, which covers the gap of the equilibrium hypothesis. The objective of the article is to provide a more accurate method to predict the properties of carbon dioxide following an expansion.     

A dynamic programming implemented resource competition game theoretic model

Resource competition is commonly occurred in animal populations and studied intensively by researchers. Previous studies have applied game theoretic model by finding Nash equilibrium to investigate this phenomenon. However computation of the Nash equilibrium requires an understanding of the payoff matrix that allocates the rewards received by players when they adopt each of the strategies in the game. In our study we present a dynamic programming implemented framework to compute 2 × 2 intraspecific finite resource allocation game's payoff matrix explicitly. We assume that two distinct types of individuals, aggressive and non-aggressive, are in the population. Then we divide the entire animal development period into three different stages: initialization, quasilinear growth and termination. Each stage for each type of players is specified with their own development coefficient, which determines how resource consumption could convert into strength as reward. Each player has equal and finite resource at the beginning of their development and fights against other players in the population to maximize its own potential reward. Based on these assumptions it is reasonable to use backward induction dynamic programming to compute payoff matrix. We present numerical examples for three different types of aggressive individuals and compute the payoff matrices correspondingly. Then we use the derived payoff matrices to determine the Nash equilibrium and Evolutionary Stable Strategy. Our research provide a framework for future quantitative studies on animal resource competition problems and could be expanded to n-players interspecific stochastic asymmetric resource allocation problem by changing some settings of dynamic programming formulation.     

由不可逆过程热力学线性关系推导的传质方程

本文用不可逆过程势力学线性关系式，推导出了在不同盐平均浓度下的一系列线性关系式，这些关系式与采用不同高聚物膜，不同盐浓度所做的反渗透实验结果符合得很好。     

Modelling Thiocyanate Adsorption onto Surfactant-Modified Coir Pith, an Agricultural Solid ‘Waste’

Thiocyanate (SCN⁻) is used in many industrial processes and is found in industrial wastewaters. Adsorptive removal of thiocyanate by surfactant-modified coir pith, an unwanted byproduct of coir fibre industry was studied. Cationic surfactant, hexadecyltrimethylammonium bromide was used as modifier. Optimum pH for maximum adsorption of SCN⁻ was found to be 2.0. Langmuir, Freundlich and Dubinin Radushkevich (D-R) isotherms were used to model the adsorption equilibrium data and the system followed all the three isotherms and the adsorption capacity of the adsorbent was found to be 8.6 mg g⁻¹. Kinetic studies show that the adsorption obeyed second order. Desorption studies showed that upto 90% recovery of SCN⁻ from the spent adsorbent was feasible. Effect of foreign anions on the adsorption of SCN⁻ was also examined.     

Thermodynamic Controls on Quality of Water From Underground Coal Mines in Colorado1

ABSTRACT: Water samples collected from 14 underground coal mines in Colorado were analyzed for major dissolved constituents. The data indicate the water quality of 13 of the samples has developed by the interaction of calcite saturated ground water with sodium rich marine shales. Those samples that displayed evidence of being most completely reacted were composed almost entirely of sodium and bicarbonate ions and had a calcium to sodium activity ratio of 0.16, similar to that of seawater. The one sample that was not saturated with respect to calcite was saturated with respect to gypsum. The dissolved solids concentration attainable by dissolution of gypsum is much less than that attainable by the calcite marine shale equilibration, or approximately 2,500 milligrams per liter. By considering the maximum predicted concentrations of dissolved solids in relation to promulgated water quality criteria, it is possible to predict the hazards of reuse of this mine drainage. The primary problems would be damage or destruction of crops if the drainage water was used for irrigation. In addition, some samples contained concentrations of chloride and sulfate in excess of recommended standards for public water supplies.     

改性颗粒活性炭对水中溴酸根的吸附特性研究

采用阳离子表面活性剂氯化十六烷基吡啶(CPC)改性颗粒活性炭以提高活性炭对溴酸根的吸附能力.通过小试研究了改性颗粒活性炭(GAC-CPC)对溴酸根的吸附特性,考察了BrO-3初始浓度、pH、共存阴离子等因素对吸附过程的影响.结果表明,CPC改性能显著提高GAC对BrO-3的吸附能力,吸附量随着初始浓度升高而增大;在碱性条件下GAC-CPC对BrO-3的吸附量减小;共存阴离子与BrO-3在GAC-CPC上存在竞争吸附,其影响顺序为:NO-3SO2-4PO3-4CO2-3.用准一级、准二级和颗粒内扩散动力学模型拟合GAC-CPC吸附BrO-3的动力学过程,结果表明,准二级动力学能更好的描述吸附过程,且孔扩散可能是改性GAC吸附BrO-3初始阶段的主要速率控制因素.用Langmuir和Freundlich等温吸附模型拟合不同温度下BrO-3的吸附平衡过程,结果表明,Langmuir等温吸附模型能很好的描述吸附平衡过程,GAC-CPC吸附BrO-3的过程是自发且放热的,温度升高不利于吸附.     

生物炭对西北黄土吸附壬基酚的影响

以壬基酚(nonylphenol,NP)为目标污染物,采用批量实验法研究其在添加不同温度制备的小麦秸秆生物炭的黄土中的吸附动力学、吸附热力学,以及粒径、pH等影响因素.结果表明,不添加生物炭黄土吸附NP的快反应时间为10 h,而加入生物炭后,黄土对NP吸附的快反应时间缩短,为6 h;且快反应阶段添加生物炭黄土明显比不添加生物炭黄土对NP的吸附量多,但碳化温度不同的生物炭在此阶段吸附量差别较小.黄土和添加生物炭黄土对NP的吸附平衡时间均为16 h且符合准二级动力学模型.无论是否添加生物炭,NP在黄土上的热力学吸附过程都较好地符合Freundlich等温吸附模型,符合L-型吸附等温模式;随着系统温度的升高,黄土和添加生物炭的黄土对NP的饱和吸附量都呈增大趋势;NP的吸附自由能ΔGθ0,焓变ΔHθ0,熵变ΔSθ0,表明此吸附是一个自发吸热且混乱程度增大的吸附过程.在同一温度下,随着生物炭碳化温度的升高,NP在添加生物炭黄土中的吸附量逐渐增大.添加生物炭黄土的粒径越小,对NP的吸附量越大.pH值为4~7时,添加生物炭黄土吸附量随pH值的增大而增加;pH为7~10时,吸附量又随pH值增大而减小;表明添加生物炭黄土在中性范围内对NP的吸附效果最好,酸性和碱性都不利于NP的吸附.     

阴离子表面活性剂改性水滑石吸附硝基苯的特性研究

以阴离子表面活性剂十二烷基硫酸钠(sodium dodecyl sulfate,SDS)为改性剂,采用共沉淀法在不同表面活性剂浓度,0.5～2.0理论阴离子交换容量(theoretical anion exchange capacity,TAEC)条件下制备了有机水滑石LDH-DS,并用XRD、FT-IR表征了样品的结构特征.结果表明十二烷基硫酸根成功插层进入LDH层间,d003底面间距由0.80 nm增大至3.98 nm.同时研究了LDH-DS对硝基苯的吸附性能,表明有机水滑石对硝基苯的等温吸附曲线符合线型方程(R2>0.99),吸附过程主要为分配作用.随着样品中SDS负载量的增加,LDH-DS对硝基苯的吸附系数Kd相应增强,但有机碳标化的吸附系数Koc值基本保持恒定.吸附热力学实验显示吸附过程为吸热反应,熵增大是吸附过程的驱动力.