STUDY ON THE ELEMENTAL CHLORINE FREE BLEACHING OF BAMBOO KRAFT PULP

1INTRODUCTIONChina is a country using the most variety of non-wood fiber raw material and is the largest country producing non-wood fiber pulp and paper in the world[1]. Bamboo is one kind of the main non-wood species for papermaking in China. Although the structure of raw materials for papermaking has being adjusted through increasing the proportion of wood pulp and by effectively utilizing waste paper source, non-wood species will still remain an important fiber resource[1,2].At present…     

基于解释结构模型的智慧城市建筑信息模型运维管理应用影响因素分析

现今智慧城市大力推广的情景下,相比传统的建造和运维手段,建筑信息模型（BIM）技术更适合作为建筑项目全过程智慧化管理的重要基础,解决项目管理建设中容易出现的管理不当、信息紊乱、难以发挥信息资源合理利用等问题。本文通过相关文献研究和查询相关报告,提取出10个影响因素,基于此采用解释结构模型技术（Interpretative Structural Modeling,ISM）搭建智慧城市背景下BIM运维管理应用影响因素的结构模型,根据结构模型对影响因素进行解释和分析,得出各影响因素之间的联系。该研究对BIM应用提供了理论依据,支持多方BIM相关人员针对不同使用情况来做出及时和明智的决策。     

我国专利保险的困境与对策

专利保险作为知识产权与金融资源结合的产物,具有提升企业知识产权保护与运用能力,降低与化解企业创新风险的重要功能。但专利保险产品在我国的推广实践表明,受限于企业维权能力、知识产权保护意识以及保险产品设计等方面原因。企业对于专利保险的认可程度仍较为有限,引发了专利保险的进一步推广与普及的困境。针对上述原因提出具有针对性的工作方案,是推动专利保险充分发挥其功能的关键。     

铀矿排风井周边地表大气氡致辐射效应的数值模拟

为了指导铀矿排风井周边地表环境的辐射防护设计,基于放射性气态流出物大气扩散的高斯烟羽模型,建立了铀矿排风井周边地表年均氡浓度以及公众个人年有效剂量的数学计算模型,研究了排风井气态流出物初始氡浓度、排风风量和源强对排风井周边地表1 km范围内年均氡浓度以及公众个人年有效剂量分布的影响.结果表明,在其他参数不变的情况下,年均氡浓度和公众个人年有效剂量的最大值随气态流出物初始氡浓度的增加而增大,随排风风量的增加而减小;最大值离井口的距离和氡致辐射的影响范围随初始氡浓度的增加而增大,随排风风量的增加而减小;相同源强下,最大值随气态流出物的初始氡浓度增加而增大,随排风风量的增大而减小;最大值离井口的距离随排风风量的增加而增大.最后,根据所得结论提出铀矿排风井周边的辐射防护建议.     

小型城市景观水体水环境的整治对策——以某高校校园河流为例

以某高校校园河流为例,首先通过布设监测站位评价水环境质量现状,估算水环境容量,然后对前期修复措施的治理效果进行评估,并为后期河流综合治理方案的制定提供建议.调查结果表明:该校园河流Z4区段水体叶绿素浓度高于其他区段,存在暴发藻类水华的风险;对照景观娱乐用水区水质标准,26个站位中总氮浓度超标率为19%,总磷浓度超标率为88%,氮、磷是影响该校园河流水环境质量的关键因素;该校园河流总氮和总磷水环境容量较低,分别为12.38 kg/d和1.05 kg/d.基于前期整治经验,后期应重点针对H2、Z4等区段,集成生态型堤岸构建、水生植被重建和人工湿地处理等水生态修复技术,并通过引调水工程、海绵校园建设和环保意识提升来开展河流综合治理,以确保该校园河流水质达到IV类标准.     

Cpf1 和 Cas9核酸酶靶向EGFR-L858R突变的研究

表皮生长因子受体(EGFR)单核苷酸突变(2573TG,L858R)占所有EGFR突变的90%.使突变的EGFR失活对有此突变的病人非常有利.这里,应用双荧光报告分析的方法分析规律成簇间隔短回文重复(CRISPR)系统中Cpf1和Cas9在靶向EGFR-L858R突变的编辑效率.在EGFR-L858R突变位点的附近,有两个Cpf1前间区序列邻近基序(PAMs)——TTTN.并且,2573TG突变形成了一个Cas9的PAM——NGG.因此本文通过构建两条AsCpf1的gRNAs(gRNA1和gRNA2)和一条SpCas9的gRNA(gRNA3)在体外通过双荧光蛋白分析系统去评估SpCas9和AsCpf1特异性靶向等位基因的能力.结果证实了AsCpf1和SpCas9都能够特异性的编辑突变的EGFR(2573TG).     

多孔陶瓷负载钯催化剂及污水处理研究

本研究以廉价的高岭土、滑石粉、氧化铝为主要原料,水泥为固化剂,疏水型活性碳粉为泡沫稳定剂,采用直接起泡法制备了高开气孔率的多孔陶瓷,采用浸渍和反应法负载氢氧化高钯催化剂.利用次甲基蓝模拟污水,并作为钯基催化剂催化次氯酸钠分解的标识物.研究了催化剂负载量、温度、次氯酸钠用量对催化剂降解次甲基蓝的影响.结果显示,多孔陶瓷负载的钯催化剂能有效催化次氯酸钠分解,极大地提高了次甲基蓝氧化褪色的速率,随温度升高,最终褪色所需时间急剧减少.在温度为40℃,催化剂量为0.4g,NaClO量为5mL,pH值为7.88的条件下,50mL浓度为10mg/L的次甲基蓝仅需要58min就能褪至无色.     

新型氯离子活化过氧单硫酸盐的非自由基系统去除水中扑热息痛的研究

提出了基于过氧单硫酸盐(PMS)的非自由基氧化法降解水中典型药物污染:利用常见的氯离子(Cl-)活化PMS降解水中典型药物扑热息痛,并同传统次氯酸钠氧化降解扑热息痛系统进行比对.对比研究了两系统中氧化剂投量、底物浓度和pH值对扑热息痛去除的影响.实验结果表明PMS/Cl-系统对扑热息痛的去除符合典型零级反应动力学模型,而NaClO系统对扑热息痛的去除符合拟一级动力学模型.当扑热息痛初始浓度为10mg/L时,0.4mM PMS和50mM Cl-在120min内对其去除率最大可达76.7%.结果表明在PMS/Cl-和NaClO系统中,提高氧化剂浓度、降低底物浓度、降低系统pH值均利于目标物的去除.PMS/Cl-和NaClO系统均以HClO为主要活性因子降解污染物,但是PMS/Cl-系统中活性因子的产生更为缓慢,今后可考虑在基于PMS的高级氧化系统中投加氯离子以实现消除残余氧化剂并保证系统的持续消毒能力.     

An M/M/1 Queueing-Inventory System with Geometric Batch Demands and Lost Sales

This paper studies an M/M/1 queueing-inventory system with batch demands. Customers arrive in the system according to a compound Poisson process, where the size of the batch demands for each arrival is a random variable that follows a geometric distribution. The inventory is replenished according to the standard (s,S) policy. The replenishment time follows an exponential distribution. Two models are considered. In the first model, if the on-hand inventory is less than the size of the batch demands of an arrived customer, the customer takes away all the items in the inventory, and a part of the customer’s batch demands is lost. In the second model, if the on-hand inventory is less than the size of the batch demands of an arrived customer, the customer leaves without taking any item from the inventory, and all of the customer’s batch demands are lost. For these two models, the authors derive the stationary conditions of the system. Then, the authors derive the stationary distributions of the product-form of the joint queue length and the on-hand inventory process. Besides this, the authors obtain some important performance measures and the average cost functions by using these stationary distributions. The results are illustrated by numerical examples.     

Effects of Zn content on the microstructure and the mechanical and corrosion properties of as-cast low-alloyed Mg–Zn–Ca alloys

The effects of Zn content on the microstructure and the mechanical and corrosion properties of as-cast low-alloyed Mg–xZn–0.2Ca alloys (x=0.6wt%, 2.0wt%, 2.5wt%, hereafter denoted as 0.6Zn, 2.0Zn, and 2.5Zn alloys, respectively) are investigated. The results show that the Zn content not only influences grain refinement but also induces different phase precipitation behaviors. The as-cast microstructure of the 0.6Zn alloy is composed of α-Mg, Mg₂Ca, and Ca₂Mg₆Zn₃ phases, whereas 2.0Zn and 2.5Zn alloys only contain α-Mg and Ca₂Mg₆Zn₃ phases, as revealed by X-ray diffraction (XRD) and transmission electron microscopy (TEM) analyses. Moreover, with increasing Zn content, both the ultimate tensile strength (UTS) and the elongation to fracture first increase and then decrease. Among the three investigated alloys, the largest UTS (178 MPa) and the highest elongation to fracture (6.5%) are obtained for the 2.0Zn alloy. In addition, the corrosion rate increases with increasing Zn content. This paper provides an updated investigation of the alloy composition–microstructure–property relationships of different Zn-containing Mg–Zn–Ca alloys.