A Model for Through Drying of Tissue Paper at Constant Pressure Drop and High Drying Intensity

A mathematical model for through drying of paper at constant pressure drop was developed. The model is based on physical properties; hence, basis weight, pressure drop, drying air temperature, pore size distribution, initial gas fraction, and tortuosity are important input parameters to the model. The model was solved for different combinations of the variables basis weight, drying air temperature, and pressure drop corresponding to industrial conditions and the results were compared with data from bench-scale experiments. The simulations show that the drying rate curve is very sensitive to the air flow rate and that correctly modeling the correlation between pressure drop and air flow rate is the most important factor for a successful model for through drying. The model was tuned by adjusting the parameters initial gas fraction and tortuosity in order to give the best possible fit to experimental data. For a given basis weight and pressure drop, different drying air temperatures resulted in relatively constant values of the fitted parameters. This means that the model can well predict the effects of changes in drying air temperature based on a tuning of the model performed at the same basis weight and pressure drop. However, for a given basis weight, an increase in pressure drop yielded fitted parameters that were somewhat different; i.e., a lower initial gas fraction and a higher tortuosity, a change that increases the resistance to air flow. This implies that the correlation between pressure drop and air flow rate in the model does not quite capture the nonlinear relationship shown by the experiments.     

A Model for Through Drying of Tissue Paper at Constant Pressure Drop and High Drying Intensity

A mathematical model for through drying of paper at constant pressure drop was developed. The model is based on physical properties; hence, basis weight, pressure drop, drying air temperature, pore size distribution, initial gas fraction, and tortuosity are important input parameters to the model. The model was solved for different combinations of the variables basis weight, drying air temperature, and pressure drop corresponding to industrial conditions and the results were compared with data from bench-scale experiments. The simulations show that the drying rate curve is very sensitive to the air flow rate and that correctly modeling the correlation between pressure drop and air flow rate is the most important factor for a successful model for through drying. The model was tuned by adjusting the parameters initial gas fraction and tortuosity in order to give the best possible fit to experimental data. For a given basis weight and pressure drop, different drying air temperatures resulted in relatively constant values of the fitted parameters. This means that the model can well predict the effects of changes in drying air temperature based on a tuning of the model performed at the same basis weight and pressure drop. However, for a given basis weight, an increase in pressure drop yielded fitted parameters that were somewhat different; i.e., a lower initial gas fraction and a higher tortuosity, a change that increases the resistance to air flow. This implies that the correlation between pressure drop and air flow rate in the model does not quite capture the nonlinear relationship shown by the experiments.     

提高生活用纸柔软度的新技术

本文介绍了生活用纸市场的概况，提高松厚度及柔软度的先进技术，以及国内目前引进的先进卫生纸设备。     

Protease and xylanase activities and thermophilic populations as potential process monitoring tools during thermophilic aerobic digestion

Thermophilic aerobic digestion (TAD) of potato process waste slurry was carried out in a batch process in a continuously stirred tank reactor at 55 °C for a total of 156 h. The pH of the slurry was either unregulated, or regulated at 6.0, 7.0, 8.0, 9.0 and 9.5, and aeration rate was 0.5 vvm. The effect of aeration rate on the digestion process was studied at 0.1, 0.25, 0.5 and 1.0 vvm at pH 7.0 and 55 °C. The development of thermophiles (55 and 65 °C populations) and hydrolytic enzyme activities (protease and xylanase) in the process were monitored. Thermophiles developed rapidly to reach peak populations in 24h or earlier, and remained stable at all fixed pH reactions. The thermophile population was only minimally affected by the aeration rate, and they were present mostly as spores after 96h of digestion. Xylanase enzyme appeared rapidly, reached a peak in approximately 60h, and declined rapidly thereafter. Highest activities were produced in neutral reactions and higher aeration rates. Aeration rates affected protease activity profoundly. The profile of both enzymes closely reflected the development of microbial activity and the overall progress of TAD, in a medium where their substrates were not predominant and not the preferred carbon sources. The relatively simple process of measuring the activities of these enzymes is potentially a more direct measure of the progress of TAD than enumeration of the microbial populations and thus, has greater potential in process monitoring. Copyright © 2003 Society of Chemical Industry     

小型卫生纸机的发展趋势——小型模块化纸机

全球生活用纸企业正在安装幅宽2～3m的小型模块化纸机：在过去两年里,就有17台2～3m幅宽的生活用纸纸机宣布被安装运行,此外还有6台幅宽5.5m的生活用纸纸机。现在有一些新工艺技术,比如热风穿透干燥（TAD）技术,能够适合一些小型生活用纸纸机（比如一些生产高端生活用纸的小型纸机）,从而为这些小型生活用纸企业带来了许多机遇。     

Vitamin B Mitigates Thoracic Aortic Dilation in Marfan Syndrome Mice by Restoring the Canonical TGF-β Pathway

Thoracic aortic aneurysm (TAA) formation is a multifactorial process that results in diverse clinical manifestations and drug responses. Identifying the critical factors and their functions in Marfan syndrome (MFS) pathogenesis is important for exploring personalized medicine for MFS. Methylenetetrahydrofolate reductase (MTHFR), methionine synthase (MTR), and methionine synthase reductase (MTRR) polymorphisms have been correlated with TAA severity in MFS patients. However, the detailed relationship between the folate-methionine cycle and MFS pathogenesis remains unclear. Fbn1^C1039G/+ mice were reported to be a disease model of MFS. To study the role of the folate-methionine cycle in MFS, Fbn1^C1039G/+ mice were treated orally with methionine or vitamin B mixture (VITB), including vitamins B6, B9, and B12, for 20 weeks. VITB reduced the heart rate and circumference of the ascending aorta in Fbn1^C1039G/+ mice. Our data showed that the Mtr and Smad4 genes were suppressed in Fbn1^C1039G/+ mice, while VITB treatment restored the expression of these genes to normal levels. Additionally, VITB restored canonical transforming-growth factor β (TGF-β) signaling and promoted Loxl1-mediated collagen maturation in aortic media. This study provides a potential method to attenuate the pathogenesis of MFS that may have a synergistic effect with drug treatments for MFS patients.     

Nondestructive analysis of structural defects in wide bandgap II-VI heterostructures

X-ray scattering measurements of wide bandgap II-VI heterostructures show that stacking faults (which nucleate defects that are responsible for optical degradation of light emitting diodes and lasers) introduce significant levels of diffuse scattering near Bragg reflections of both the epitaxial layers and the GaAs substrate. We employed triple axis x-ray diffraction techniques to investigate stackingfault diffuse scattering and used cathodoluminescence and transmission electron microscopy to independently measure the stacking fault density. For comparison, double axis scans from the same samples were largely incapable of detecting the presence of these defects. Measurements taken at different azimuthal positions exhibit different levels of diffuse scattering and the diffuse scattering intensity is related to the stacking fault intensity in each <110> direction, which suggests that this technique can provide a non-destructive assessment of defects present in these systems. For some samples, the ZnSe buffer layer exhibited a tilt with respect to the substrate along a <110> direction; this tilt was greater than the tilt which would be attributed to growing a strained layer on the slightly miscut substrates which were used here.     

Regulation Network of Colorectal-Cancer-Specific Enhancers in the Progression of Colorectal Cancer

Enhancers regulate multiple genes via higher-order chromatin structures, and they further affect cancer progression. Epigenetic changes in cancer cells activate several cancer-specific enhancers that are silenced in normal cells. These cancer-specific enhancers are potential therapeutic targets of cancer. However, the functions and regulation networks of colorectal-cancer-specific enhancers are still unknown. In this study, we profile colorectal-cancer-specific enhancers and reveal their regulation network through the analysis of HiChIP data that were derived from a colorectal cancer cell line and Hi-C and RNA-seq data that were derived from tissue samples by in silico analysis and in vitro experiments. Enhancer–promoter loops in colorectal cancer cells containing colorectal-cancer-specific enhancers are involved in more than 50% of the topological associated domains (TADs) changed in colorectal cancer cells compared to normal colon cells. In addition, colorectal-cancer-specific enhancers interact with 152 genes that are significantly and highly expressed in colorectal cancer cells. These colorectal-cancer-specific enhancer target genes include ITGB4, RECQL4, MSLN, and GDF15. We propose that the regulation network of colorectal-cancer-specific enhancers plays an important role in the progression of colorectal cancer.     

基于数据链的空战目标运动参数的转换

为了解决多机协同空战中数据链延时对空战态势判断带来的影响,本文应用了一种极坐标系下的卡尔曼滤波算法,对数据链的传输延时误差进行补偿,并在此基础上进行目标运动参数的转换,计算工程技术人员感兴趣但机载测量设备无法测量的目标信息,比如目标进入角。仿真结果表明,该算法对数据链延时的补偿误差较小,并能对数据链提供的目标数据进行比较精确的处理。     

纯氧曝气用于污泥高温好氧消化的研究

采用纯氧曝气高温好氧消化技术(TAD)处理污水厂污泥,并与传统空气曝气进行了对比,系统考察了纯氧曝气高温好氧消化反应器的运行性能.研究发现,通过合理调节纯氧曝气量来控制反应器内的溶解氧浓度,可以实现污泥的高温好氧消化,7 d后对VSS的去除率可达40%以上,达到了我国城镇污水处理厂污泥的排放标准.纯氧曝气用于污泥高温好氧消化的氧气利用效率明显高于空气(<25%),最高可达80%.在达到同等污泥稳定化效率的情况下,纯氧曝气量远小于空气曝气量,由于尾气排放造成的能量损失较少,有利于反应器的保温.纯氧曝气速率过高会导致反应器内溶解氧的积累,而在高温条件下过高的溶解氧浓度(>15 mg/L)会对微生物产生一定的毒害作用.