A novel method of studying the collapsed cell of eucalyptus wood using X-ray CT scanning

Abstract

Collapse is the severest defect for collapse-prone species used as solid wood product materials. Previous study focused on the morphological structures by scanning electron microscopy (SEM) to observe the change of the collapsed cells during the drying processes. The multi planar reconstruction by X-ray computed tomography (CT) scanning provided a new method for cell microstructure observation. In this study, cell collapse of Eucalyptus urophylla were observed by SEM and X-ray CT scanning during the continuous and intermittent drying process. The cell shapes, cell types, cell collapsed quantities and the shrinkage curves were determined. The results demonstrated that layered scanning technique by X-ray CT scanning provided a top-down approach to investigate the structure in depth at different layers in a fast and nondestructive way. Compared with SEM observation, this approach emphasized more specific aspects and information for collapse quantitative analysis. Quantitative analysis of collapsed cells by X-ray CT scanning not only indicated the cell deformation but quantified the extent of cells collapse. The shrinkage rate was also measured by calculating the areas change in porosity at tissue level before and after drying through X-ray CT scanning. It indicates that intermittent drying process may decrease the extent of cell collapse or accelerate the recovery of collapsed cells. These results further confirm that the X-ray CT scanning provides another effective method for wood cell collapse study at the morphological level.     

Industrial Experience in Pressurized Steam Drying of Beet Pulp,Sewage Sludge and Wood Chips.

ABSTRACT

Drying in superheated steam under pressure gives possibilities for pollution free drying, energy recovery. reduced drying time and a very compact drying equipment.

Products are dried i n a pressurized cellular fluid bed by super heated steam blown through the cells. Above the fluid bed dust is separated before the steam is reheated and recirculated to the cells by a fan. The evaporated water leaves the dryer as usable steam at e.g. 3 bar g, and full energy recovery is obtained. Today 14 plants have been builtor are under construction, with capacities from 2 to 40t / h water evaporation.

This technology is suited for drying of beet pulp, residues from starch production of corn or wheat. sludge. spent grain. brown coal. wood chips and bark.

The technology shows great options for integration in steam systems in various industries, whereby drying is possible without using primary energy and pollution is avoided.     

Morphological Analyses of Polymer Electrolyte Fuel Cell Electrodes with Nano‐Scale Computed Tomography Imaging

We report a three‐dimensional (3D), pore‐scale analysis of morphological and transport properties for a polymer electrolyte fuel cell (PEFC) catalyst layer. The 3D structure of the platinum/carbon/Nafion electrode was obtained using nano‐scale resolution X‐ray computed tomography (nano‐CT). The 3D nano‐CT data was analyzed according to several morphological characteristics, with particular focus on various effective pore diameters used in modeling gas diffusion in the Knudsen transition regime, which is prevalent in PEFC catalyst layers. The pore diameter metrics include those based on chord length distributions, inscribed spheres, and surface area. Those pore diameter statistics are evaluated against computational pore‐scale diffusion simulations with local gas diffusion coefficients determined from the local pore size according to the Bosanquet formulation. According to our comparison, simulations that use local pore diameters defined by inscribed spheres provide effective diffusion coefficients that are consistent with chord‐length based estimations for an effective Knudsen length scale. By evaluating transport rates in regions of varying porosity within the nano‐CT data, we identified a Bruggeman correction scaling factor for the effective diffusivity.     

磁控溅射镀钽及其镀层性能的研究

利用直流磁控溅射法,在铝基片、玻璃基片上制备了钽膜。研究了氩气压力、阴极电流、系统本底真空度、溅射时间等工艺条件对钽膜性能及厚度的影响,并对钽膜的物理性能及电学性能进行了研究。结果表明,钽镀层的厚度主要与钽靶功率、氩气分压及溅射时间有关;当氩气压力、电流一定时,钽镀层的厚度与溅射时间近似地成正比关系：利用3A／(8min)、4A／(6min)、5A／(3min)各5片铝基片镀钽的样品制成了医用CT检测器信号接受盒,获得的X—ray电信号分别为30万、32万、34万单位,达到并超过了国际同类产品的技术指标。     

超声波/纳米铁粉协同脱氯降解四氯化碳

采用超声波／纳米铁粉协同脱氯降解四氯化碳,探讨了纳米Fe粉用量、反应液的初始pH值、CCl4初始浓度对脱氯降解效果的影响。结果表明：纳米铁粉用量为0．5g／100mL时,脱氯率最高;反应液的初始pH值为2．0时,可获得较高的脱氯率;CCl4的初始浓度越高,其脱氯率越低。     

Cryptosporidium Log-inactivation with Ozone Using Effluent CT10, Geometric Mean CT10, Extended Integrated CT10 and Extended CSTR Calculations

The draft Long-Term 2 Enhanced Surface Water Treatment Rule (LT2ESWTR) contains Cryptosporidium log-inactivation CT tables (ozone-in-water concentration [residual], “C” times contact time, T). Depending on water temperature, Cryptosporidium CT values that are listed are 15 to 25 times greater than CT values for equivalent Giardia log-inactivation credit. The elevated operating dose required for Cryptosporidium log-inactivation credit has the potential to increase disinfection by-product (DBP) formation (e.g., bromate). Calculating CT value accurately will minimize ozone dose, which will decrease operating cost and lower DBP formation, and at the same time maintain disinfection protection through implementation of scientifically based safety factors. Various methods are available for calculating CT value. The method chosen depends largely on the available information concerning ozone residual characteristics and hydrodynamic features of the ozone contactor, plus local regulatory requirements. Four methods are discussed in this paper. Each method can be used to calculate Giardia, virus, and Cryptosporidium log-inactivation credit.     

结节或包块型不典型肺结核CT影像特征及意义

目的：总结分析采用C T诊断结节或包块型不典型肺结核的影像资料表现。方法：在2013年2月到2015年2月期间,选取我院病理确诊的50例肺癌患者作为对照组,同时选取50例结节或包块型不典型肺结核患者作为观察组,对这两组患者采用CT诊断的影像表现进行分析。结果：观察组和对照组在CT影像中的分叶征、毛刺征、支气管充气征、空泡征、血管集束征、胸膜凹陷征以及增强扫描方面存在着明显差异（P＜0.05）,具有统计学意义。结论：对于结节或包块型不典型肺结核患者采用CT诊断过程中应注意与肺癌的区别,多种影像资料表现的综合分析有助于提高不典型肺结核的诊断率。     

再生骨料特征参数对混凝土强度的影响

再生骨料(RCA)对混凝土的性能影响极大,了解RCA对混凝土性能的影响,对提高RCA的利用效率,降低建筑行业碳排放并响应国家“双碳”政策至关重要。本文借助CT扫描技术获取了四组不同RCA替代率下掺锂渣再生混凝土的骨料特征图像,运用数字图像处理方法获得了RCA的形状系数(SF)、棱角度(AN)、棱角与表面纹理(AT)指数及三维球体度(SP),分析了它们的分布规律及特点,并通过灰色关联分析方法建立了骨料特征参数与抗压强度的联系。结果表明:RCA具有较高的不规则性,由于骨料残留的砂浆量不同,其表面呈现粗糙且多棱角的特点;四个骨料特征参数均表现出较高的灰色关联度,其中SP关联性最大,达到0.942;在合理的骨料混合比例下,试验样品可以满足C30混凝土强度的要求,且在30%(质量分数)RCA替代率下力学性能最优。     

Application of Cr3C2/C composite powders synthesized via molten-salt method in low-carbon MgO–C refractories

High-performance and low-carbon MgO–C refractories are important refractories for smelting ultra-low carbon steel and clean steel. Based on this, Cr₃C₂/C composite powders were synthesized by the molten-salt method, and used as an additive to prepare low-carbon MgO–C refractories under nitrogen atmosphere. The phase, morphology and oxidation kinetics of Cr₃C₂/C composite powders were studied. In addition, the effect of Cr₃C₂/C composite powders on the morphology, mechanical properties, thermal shock resistance, and corrosion resistance of MgO–C refractories was investigated. The results indicated that the Cr₃C₂/C composite powders exhibited superior oxidation resistance than flake graphite. Moreover, the Cr₃C₂/C composite powders were introduced into the MgO–C refractories. Compared with the sample without Cr₃C₂/C composite powders, the introduction of 1 wt% Cr₃C₂/C composite powders significantly improved the thermomechanical properties and corrosion resistance of the material, its CMOR, CCS before and CCS after thermal shock were 9.06 MPa, 50.40 MPa and 32.60 MPa, respectively, and the corrosion index was significantly reduced from 44.6% to 26.5%.     

薄壁锥端注浆微型钢管桩抗拔承载特性的现场试验

解决新时期电网"绿色建设"的需求,研发并应用新型环保型杆塔基础是电网建设中的首要任务之一.本文提出一种改进的薄壁锥端注浆微型钢管桩,通过现场试验,研究该类钢管桩的抗拔承载特性.以双楼—交河220 kV线路工程为背景,设计出 ?159和?203 mm两种桩径、5和8 m两种埋深、注浆与不注浆两种条件,共18根钢管桩,开展...