Physical characteristics of AFEX-pretreated and densified switchgrass,prairie cord grass,and corn stover

The goal of the study was to evaluate and compare the physical properties of control, pretreated and densified corn stover, switchgrass, and prairie cord grass samples. Ammonia Fiber Expansion (AFEX) pretreated switchgrass, corn stover, and prairie cord grass samples were densified by using the comPAKco device developed by Federal Machine Company of Fargo, ND. The densified biomass were referred as “PAKs” in this study. All feedstocks were ground into three different grind size of 2, 4 and 8 mm prior to AFEX pretreatment and the impact of grinding on pellet properties was studied. The results showed that the physical properties of AFEX-PAKed material were not influenced by the initial grind size of the feedstocks. The bulk density of the AFEX-PAKed biomass increased by 1.2–6 fold as compared to untreated and AFEX-pretreated materials. The durability of the AFEX-PAKed materials were between 78.25 and 95.2%, indicating that the AFEX-PAKed biomass can be transported easily. To understand the effect of storage on the physical properties of these materials, samples were stored in the ambient condition (20 ± 2 °C and 70 ± 5% relative humidity) for six months. After storage, thermal properties of the biomass did not change but glass transition temperature decreased. The water absorption index and water solubility index of AFEX-treated and AFEX-PAKed biomass showed mixed trends after storage. Moisture content decreased and durability increased upon storage.     

Study of metal assisted anisotropic chemical etching of silicon for high aspect ratio in crystalline silicon solar cells

Textured surface is commonly used to enhance the efficiency of silicon solar cells by reducing the overall reflectance and improving the light scattering. In this study, a comparison between isotropic and anisotropic etching methods was investigated. The deep funnel shaped structures with high aspect ratio are proposed for better light trapping with low reflectance in crystalline silicon solar cells. The anisotropic metal assisted chemical etching (MACE) was used to form the funnel shaped structures with various aspect ratios. The funnel shaped structures showed an average reflectance of 14.75% while it was 15.77% for the pillar shaped structures. The average reflectance was further reduced to 9.49% using deep funnel shaped structures with an aspect ratio of 1:1.18. The deep funnel shaped structures with high aspect ratios can be employed for high performance of crystalline silicon solar cells.     

Fatigue life improvement of 12Cr1МoV steel by irradiation with Zr+ ion beam

Cyclic tension and bend tests were performed on heat-resistant 12Cr1MoV steel specimens in as-supplied condition as well as after Zr⁺ ion beam surface irradiation. Distinct differences in strain induced relief, as well in cracking pattern of modified surface layer were observed by optical microscopy and interference profilometry. Changes in subsurface layer are characterized by means of nano- and microindentation and fractography of fracture surfaces (with the help of scanning electron microscopy). It is shown that the main influence on mechanical properties is mostly induced by thermal treatment during irradiation rather than formation of a 2 μm thick layer doped with Zr. The differences in deformation behavior may be explained by physical mesomechanics concepts.     

Preparation and properties of nano-sized SnO2 powder

1　INTRODUCTIONSnO2isoneofthemainmaterialsusedingassensor.Becauseofthehumidityandgassensingfunction,itattractsmoreandmoreattentions.Butthepresentproblemishowtoimprovethestabilityandsensibilityofgassensor.Researchershavetakenmanymeasurestoresolvethisproble…     

超细Fe3O4粒子表面包覆酞菁钴性质研究

本文研究了合成载氧体的金属有机化学液相淀积法制造工艺，所得产物经ＴＥＭ、ＸＰＳ、Ｍｏｓｓ－ｂａｕｅｒ谱和Ｂ－Ｈ仪等手段，研究了它的结构和磁性能。实验表明，酞青钴以薄层形式包覆在Ｆｅ＿３Ｏ＿４的表面，封闭了Ｆｅ＿３Ｏ＿４的表面孔洞，稳定了Ｆｅ＿３Ｏ＿４的物相，增强了磁性能。     

孤岛油田西区聚合物驱开发研究

孤岛油田西区注聚区1997年3月投入注聚后，高渗层得到有效封堵，吸水剖面得到明显改善。注聚期间，通过实施注聚区外围水井降水或停注、油井放大生产压差和调整注聚井注入速度等开发措施，扩大了聚合物波及体积，聚合物驱取得了明显效果。     

FW调剖技术及应用

应用FW调剖技术有针对性地对 119口非钻停井区注水井采取了 4种精细调剖方案 ,对比了化学浅调剖应用前后注水井层间矛盾的缓解 ,纵向上吸水剖面的改善 ,注水量和吸水指数的变化及渗流能力的变化。结果表明 ,注水井化学浅调剖后 ,井区的连通油井明显受效 ,获得较高的增油量 ,水驱的开发效果得到改善。化学浅调剖可以有效地封堵高渗透层 ,扩大低渗透层注入水的波及体积 ,减缓注水井层间矛盾 ,实现了对注水井吸水剖面的有效调整 ,这对深化注水结构调整、挖掘各类油层潜力、提高储量动用程度有显著的效果。     

Optical switching properties of RCo2-type alloy thin films by electrochemical hydrogenation

The switchable optical properties of Pd-protected RCo₂-type Ho_0.6Mm_0.4Co₂ alloy thin films have been investigated in a KOH electrolyte. The reversible optical switching has been carried out simultaneously by measuring transmitted light through the thin film during electrochemical charging–discharging of hydrogen. The dependence of switching speed and cyclic durability of the film on the charging and discharging current density as well as concentration of KOH electrolyte has been studied. In addition, cyclic voltammetric measurements have been performed to examine the hydride formation and decomposition reactions.     

服装低密度聚乙烯热熔胶化学粉碎的研究

服装粘合衬布的生产需要低密度聚乙烯热熔胶的微细粉末,介绍了对该热熔胶的化学粉碎技术所进行的实验研究,表明采用适当的助剂种类和用量以及适宜的工艺过程,通过化学粉碎可以得到合格的粉末产品。     

化学事故危害评估

根据化学事故危害的主要影响因素对化学事故进行危害评估,考查了危害纵深、人员杀伤率、危害地域估算、爆炸燃烧事故危害等内容。