Mesoporous silica with short-range MFI structure

A new type of mesoporous silica has been prepared which showed 780 m²/g of BET surface area and 0.6 ml/g of primary mesopores narrowly distributed around 4.2 nm. More importantly however, is that it showed short-range zeolite crystallinity as demonstrated by FTIR and XRD analysis, and hydrophobicity as demonstrated by water and n-hexane adsorption.

This material was synthesized via a dual-template, three-step hydrothermal–flocculation–steaming synthesis procedure developed by us recently. Briefly, MFI nanoprecursors (NPs) were first prepared by a low-temperature hydrothermal step using TPAOH as template for zeolite structure, and then flocculated using a surfactant that served as the template for the mesopores. The collected NPs are mesoporous silica exhibiting short-range MFI domains when directly calcined. However, the steaming step promoted the crystallization of the NPs and created uniform mesopores. It was found that almost every detail in these procedures affected the properties of the final product. The most important variables, however, were identified as the duration the flocculants were kept in contact with the liquid phase, and the humidity under which the steaming was conducted. By properly adjusting the procedures, the said mesoporous silica, as well as nanocrystals having high external surface area, could be produced at will.     

PVA基活性碳纤维的研制

探索了由民用大丝束聚乙烯醇纤维(PVAF)试制活性碳纤维(ACF)的可能性,以开辟新的原料路线,降低产品成本。PVAF首先用脱水剂处理,脱水剂浓度为10%(质量),然后在200—300℃进行热处理,处理后的纤维再经预氧化和碳化活化转化为ACF,ACF的收率为37.7%,比表面积为1050m~2/g。此外,还探索了用O_3处理PVAF。用差热、热失重和红外等手段对产物进行了表征,推论了相应的反应机理。结果表明:经适当处理的PVAF可制得具有较好吸附性能的ACF。     

宁波市蛇蟠岛应急水源地建设与环境效应

在评价宁波市蛇蟠岛淡水资源量的基础上,估算其应急供水规模。通过构建地下水数值模型,预测在应急开采条件下地下水位恢复能力,并对应急开采产生的地下水降落漏斗、地面沉降和咸水入侵等环境效应进行了评价。结果表明,蛇蟠岛地下淡水具有应急水源地建设可行性,为该地区进一步勘查应急水源地提供了依据。     

流域一体化下的生态文明先行示范区建设探索

以抚仙湖流域为研究区域,通过系统收集分析流域多年水量水质监测数据,诊断流域保护与发展面临的主要矛盾,并基于流域一体化管理思想,提出了流域保护与发展的可能路径:1创新抚仙湖流域生态文明示范区行政管理体制,从发展思路确立抚仙湖流域实施"严格环境保护、创新生态发展"的转型战略,真正树立和实现"大景区"环境保护和"大旅游"产业发展的生态文明建设理念;2在全面实现生态发展战略的前提下,建议将流域实施分区管控,调减农业用地面积,积极发展现代观光农业和旅游业;3通过生态搬迁,优化城乡布局,实施抚仙湖流域全域"大旅游景区"战略,实现生态资源-资产-资本的良性转化。     

管材超声波分层缺陷检测中盲区的构成探析

管材超声波分层检测作为控制产品质量的关键步骤,必须引起相关从业人员的重视,特别是要重点分析分层缺陷检测中盲区的构成原因和分布特征。只有这样,才能切实保证检测结果的准确性,更好地控制管材质量。通过对超声波分层缺陷检测的重要性进行阐释,分析了其中盲区的构成和分布等问题。     

Preparation and characterization of trilobal activated carbon fibers

The objective of this research was to evaluate the effectiveness of several different methods for controlling the pore size and pore size distribution in activated carbon fibers. Variables studied included fiber shape, activation time, and the addition of small amounts of silver nitrate. Pure isotropic pitch and the same isotropic pitch containing 1 wt.% silver were melt spun to form fibers with round and trilobal cross sections. These fibers were then stabilized, carbonized, and activated in carbon dioxide. Field emission scanning electron microscopy (FE SEM), electron dispersive spectra (EDS), and wavelength dispersive spectra (WDS) were used to monitor the size and distribution of the silver particles in the fibers before and after activation. Each of these analyses showed that the distribution of silver particles was extremely uniform before and after activation. The fibers were also weighed before and after activation to determine the percent burn-off. The BET specific surface areas of the activated fibers were determined from N₂ adsorption isotherms measured at −196 °C. The results showed that round and trilobal fibers with equivalent cross-sectional areas yielded similar burn-off values and specific surface areas after activation. Also, activation rates were found to be independent of CO₂ flow rate. The porosity of the activated fibers depended on the total time of activation and the cross-sectional area of fibers. The N₂ adsorption measurements showed that the activated fibers had extremely high specific surface areas (greater than 3000 m²/g) and high degrees of meso- and macro-porosity. FE SEM was also used to investigate surface texture and size of pore openings on the surfaces of the activated fibers. The photos showed that silver particles generated surface macro- and mesopores, in agreement with the inferences from N₂ adsorption measurements.     

Preparation and characterization of antibacterial silver-dispersed activated carbon aerogels

Silver-dispersed carbon aerogels (CAs) were obtained by direct immersion of organic aerogels prepared by ambient pressure drying technique in AgNO₃ aqueous solution and then carbonization. The effect of preparation conditions such as the resorcinol/catalyst ratio, the feed AgNO₃ concentration, the ratio of aerogel mass/solution volume, immersion time and carbonization temperature on the bulk density and silver content as well as the BET surface area of the dispersed CAs was studied. The dispersion and structure of silver nanoparticles in obtained materials were investigated by means of scanning electron microscopy, transmission electron microscopy and X-ray diffraction. The Ag-dispersed CAs prepared exhibit strong and long-term antibacterial activity.     

无线传感网中基于成对节点探测不确定性的目标容错跟踪方法

针对无线传感器网络(Wireless Sensor Networks,WSN)中的节点在真实环境中的不可靠感知现象及其对目标跟踪精度的影响,首先分析计算了成对传感器节点感知存在的不确定区域及其边界,在此基础上,提出了一种基于成对节点探测不确定性的目标容错跟踪方法(Tracking with Pairwise Uncertainty of RSSI,TPU-RSSI),即通过匹配分组感知采样得到的感知向量(sampling vector)和跟踪区域划分面(face)的特征向量(signature vector)来进行移动目标容错跟踪。该方法在保持跟踪方法灵活性的基础上,能够减小由环境因素带来的跟踪误差。为了降低计算复杂度,提出了一种基于邻居面连接的启发式匹配算法。大量的仿真实验结果均表明,所提方法相比同类的其他方法具有更强的灵活性和更高的定位精度。     

沉淀法白炭黑化学指标与胶料物理性能的关系

分析了沉淀法白炭黑BET，CTAB，Ssears比表面，DBP吸油值，平均粒径与粒径分布对胶料物理性能的影响。得出结论：满足轮胎综合力学性能的沉淀法白炭黑应为低BET比表面积，低BET与CTAB比，高BET与Ssears比，适中的DBP吸油值，中值粒径小且易崩解的产品。     

多壁纳米碳管的超声短切处理

采用超声方法对多壁纳米碳管进行短切处理，比较系统地考察了超声时间对纳米碳管的长度、孔结构和形貌的影响。结果表明，超声粉碎可以有效地短切多壁纳米碳管，随超声时间的延长，纳米碳管的长度显著减小。在超声处理120min后，纳米碳管被短切到平均长度为400nm。超声短切后的纳米碳管比表面积和孔容均显著增加。进一步延长超声时间，其比表面积和孔容反而下降。