Impact of xylan structure and lignin–xylan association on methane production from C5-sugars

Xylan biopolymers are the dominant hemicelluloses present in agricultural plant materials which have potential use in various biotechnological processes including methane production. Hence, the effect of lignin content and the structural features of xylan on anaerobic digestion were studied by using synthetic assemblies consisting of xylans and lignin models (dehydrogenation polymers). The ramification by arabinose and uronic acid was shown to be a key factor in low methane potential (BMP) from xylans and xylan–lignin assemblies. Indeed, BMP increased when xylose content was increased, and decreased when arabinose and uronic acid contents were increased. Lignin content and molecular weight were found to be the most influential parameters on the anaerobic digestion rate. Digestion rate decreased when the lignin content and molecular mass increased.     

利用测井信息计算页岩有机质丰度 ——以川南长宁地区龙马溪组为例

充足的有机质是油气生成的物质基础,有机质丰度决定了烃源岩的生烃潜力,因此获取页岩有机质丰度对指导页岩气的勘探开发具有重要作用。在选取川南长宁地区龙马溪组下段泥、页岩作为研究对象的同时,利用总有机碳含量作为有机质丰度评价指标,对泥、页岩样品化验得出的有机碳含量和对应深度的测井数据进行拟合,得出总有机碳含量的计算公式,并依据不同测井响应参数的选取,总结出 3 种测井计算方法,相应地回归出 3 个计算公式,在研究区对计算结果进行验证和误差分析。结果表明：Δ lg R-密度法和密度-铀多元回归法得出的有机碳含量与样品实测的有机碳含量符合程度较高;单井纵向上表现出龙马溪组有机碳含量在下段底部附近较高,具有由底部向上逐渐降低的趋势;密度-铀多元回归公式计算的误差最小,表现出较强的适用性,可在长宁地区推广应用。     

A NEW METHOD FOR PREDICTION OF PRODUCTIVITY OF FRACTURED HORIZONTAL WELLS BASED ON NON-STEADY FLOW

Hydraulic fracturing technologies of horizontal well are important ways to develop oil-gas field with low permeability. Productivity forecast of fractured horizontal wells is a difficult problem of hydraulic fracturing technologies. Basing on non-steady flow of fractures fluid during production, applying potential function principles, superposition principle and mathematical method for solving, coupling of seepage flow in the formation and pipe flow in the well bore, a new model on multi-fracture interference productivity forecast of fractured horizontal well is established in this article. The results indicate the coincidence rate between this model and practice is high. The pressure loss in the horizontal well bore has definite influence on the production status of fractured horizontal wells. The productions of different fractures in horizontal well bore are unequal, the productions of outer fractures are higher than middle fractures; the pressure in the well bore shows an uneven distribution, the pressure declines gradually from finger tip to heel end. Asymmetry of fractures may make productivity of fractured horizontal wells decline. The conclusions are instructive in designing fractured horizontal well for low permeability reservoir.     

Reforming catalysts for hydrogen generation in fuel cell applications

The objective of this review paper is to present a summary of the specific contributions in the field of fuel processing, particularly, outlines various developments involving catalytic reforming of a range of fuels for the development of an efficient fuel-processing unit for syngas production in fuel cell applications. Two major topics are discussed (i) the basic reactions involved in each of the processes and (ii) various catalyst systems that have been tested. A final short section offers some new possible routes for future research.     

Disconnected Policymakers

The halt of restructuring is not merely due to “bumps in the road” on the way to the idealized marketplace. A renewed commitment to universal service at reasonable rates is needed.     

双咪唑啉在CO2/O2环境中的缓蚀行为及其与巯基乙醇的复配性能

目的 探究双咪唑啉(PMA)在CO2/O2环境中对碳钢的缓蚀作用及其与2-巯基乙醇(MAT)复配时的缓蚀性能和机理。方法 采用红外光谱对合成的PMA进行表征，运用失重法、电化学测试技术(阻抗谱和极化曲线)和表面形貌分析等手段评价PMA的缓蚀性能，同时探究PMA与MAT复配后的协同缓蚀作用。通过量子化学计算和分子动力学模拟，分析PMA与MAT分子的吸附活性位点和吸附能力。结果 失重实验结果表明，CO2/O2环境中添加100 mg/L PMA时，缓蚀率可达66.47%。随MAT浓度的增加，缓蚀效率逐渐提高，当MAT的质量浓度为40 mg/L时，缓蚀率达到最高值(70.38%)。电化学测试结果表明，PMA和MAT复配后，碳钢的腐蚀电位随缓蚀剂浓度的升高而升高，阳极反应受到明显抑制。扫描电镜观察到加入复配缓蚀剂后，碳钢表面光滑，腐蚀深度减小。理论计算结果表明，PMA的活性位点在咪唑啉环上，而MAT的活性位点在硫原子上，二者复配后自由体积分数减小，因此缓蚀效率提高。结论 由于PMA在碳钢表面有较强的吸附能力，因此在CO2/O2环境下的缓蚀效果较好，PMA与MAT表现出较好的协同作用，二者复配后，能够更有效地抑制碳钢在CO2/O2环境中的腐蚀。缓蚀机理为PMA在碳钢表面形成一层保护膜，MAT的加入使保护膜更加致密。     

Environmental risks of shale gas development in China

Shale gas development in China can generate great potential economic benefits, but also poses serious environmental risks. In this paper, we offer a macro assessment of the environmental risks of shale gas development in China. We use the US experience to identify the nature of shale gas development activities and the types of potential burdens these activities may create. We then review the baseline environmental conditions and the effectiveness of environmental regulations in China and discuss the implications of these China-specific factors for risk assessment. We recommend China to conduct a strategic environmental assessment and to consider sector-specific environmental regulations.