兰州重离子加速器深层治癌束流线真空系统

重离子深层治癌束流线从兰州重离子加速器冷却储存环(HIRFL-CSR)主环引出,利用能量为100MeV/u～430MeV/u的碳离子束,开展治疗体内各种癌症的深层治癌研究.该束流线真空系统包括极高真空段、超高真空段和大气段,采用不同的真空获得方案和工艺路线,分别在极高真空段和超高真空段获得了8×10-10Pa和1×10-6Pa的真空度,并顺利实现了束流线的真空过渡,保证了HIRFL-CSR主环极高真空系统的安全运行;研制了适用于高频率扫描磁铁内放置的真空管道,消除了涡流对束流的影响;对隔离真空和大气的大尺寸膜窗材料进行了调研,选择高强度塑料膜(Hostaphan)和加强纤维膜(Kevlar)联合使用,既能让束流通过,又不会产生危害人体的中子,并能够有足够的强度抵御大气压力.该束流线真空系统的建成为重离子深层治癌的研究提供了良好的真空条件.     

波导真空侧射频击穿导致陶瓷窗破裂

出示真空侧波导内部打火导致陶瓷窗破裂的一些证据 ,支持关于陶瓷窗破裂是由于真空波导内靠近陶瓷窗附近(或在其上 )强射频击穿引起的观点 ,最后简要分析之。     

波导阀门放气理论计算和改进措施

本文介绍了波导阀门放气量和波导阀附近真空系统的真空度的关系.波导阀门放气量对速调管陶瓷窗附近的真空度有极大的影响.在计算和实验研究的基础上,我们对波导阀门的放气量进行了理论计算,按照BEPCII对速调管陶瓷窗真空度的要求改进了真空系统.     

PVDF螺旋卷式膜组件制备及真空膜蒸馏性能研究

真空膜蒸馏工艺作为一种具有良好应用前景的膜蒸馏操作方式得到了广泛的研究.当前常用于真空膜蒸馏研究的膜组件包括平板式、管式和中空纤维式.尝试制备了一种用于真空膜蒸馏的螺旋卷式膜组件,通过试验对自制组件的性能进行了研究,证实了卷式膜组件真空膜蒸馏操作的可行性.在真空度为-0.092 MPa,温度为67.7℃的操作条件下,得到了10.43 kg/(m2·h)的通量.通过试验比较了所制备卷式膜的通量与膜材料本底通量的差别,并对所存在的问题进行了分析.     

氧传感膜的制备及稳定性研究

将聚丙烯微孔过滤膜浸渍到不同比例荧光指示剂(四(五氟苯基)卟啉铂(PtTFPP)和聚合物基质(乙基纤维素)的混合溶液中,制备了一系列氧传感膜。采用扫描电子显微镜、激光共聚焦荧光显微镜和荧光光谱仪表征了氧传感膜的形貌和光学性质,并得到最佳配比的氧传感膜。连续监测14d后,氧传感膜的真空相位降低了7.69%,使用特定的发光二极管(LED)光照老化装置对氧传感膜进行连续光照老化实验。结果表明,老化10h后氧传感膜的真空相位下降速率降低。测试了老化10h后氧传感膜的稳定性,发现紫外光和绿光老化的氧传感膜真空相位下降幅度分别为1.35%和2.40%,明显小于未老化的氧传感膜。光老化法可以提高氧传感膜的稳定性,在实际应用中具有广阔的前景。     

加速器束流钛窗钎焊

本文论述了以束流钛窗代替老式结构束流窗的特点，使得耐热性能好、强度大，并 采用焊接结构密封，结构简单，真空性能也好，抗辐照、抗老化、寿命长等。文中系统 地论述焊接设备、钛窗钎焊结构，钎料选择、钎焊工艺等．     

自动导引小车系统运输能力的设计研究

为了解决自动导引小车系统(AGVS)中由于两辆以上自动导引小车竞争同一资源(通道或缓冲区)所引起的碰撞导致的运输能力设计问题,提出了一种基于贪心算法的时间窗技术方法。仿真实验表明,该方法完全可以解决这一问题,同时可以使系统的运输能力最大化。     

超支化聚硅氧烷改性聚偏氟乙烯微孔膜的制备及膜蒸馏性能

采用γ-甲基丙烯酰氧基丙基三甲氧基硅烷(A-174)水解缩合反应合成超支化聚硅氧烷(HPSi O),并用其改性聚偏氟乙烯(PVDF)制备疏水HPSiO-PVDF微孔膜。通过红外光谱、核磁共振、水接触角、孔隙率、孔径分布、力学强度等表征方法研究了所制膜的结构和性能,以及微孔膜膜蒸馏性能。结果表明,HPSiO的加入降低了膜孔径,提高了微孔膜的孔隙率、疏水性能、力学性能及真空膜蒸馏性能。     

厌氧膜生物反应器在食品废水处理中的应用研究

分别采用小试规模(50 L/d)外置错流管式厌氧膜生物反应器和中试规模(20 t/d)浸没式厌氧旋转膜生物反应器进行了食品厂废水的处理实验研究.结果表明,加入超滤膜单元提高了厌氧系统的总有机物去除率及甲烷产量,使系统出水水质更加稳定;外置错流式超滤膜随运行时间的延长通量明显下降,而旋转式超滤膜可通过膜片旋转速度提高和保持膜通量;浸没式旋转膜组件的运行能耗较外置管式膜组件至少降低30%;但不同形式的厌氧膜生物反应器对氨氮和总磷去除能力有限,需进一步处理.     

PVDF中空纤维膜组件特性参数对淡化浓盐水VMD性能的影响

研究聚偏氟乙烯中空纤维膜组件性能参数(高径比、装填封率)对淡化浓盐水真空膜蒸馏(VMD)性能的影响,获得适用于淡化浓盐水VMD过程膜组件制备的优化参数.小试实验研究了膜组件高径比为分别为25∶2、15∶1、35∶2、20∶1、45∶2及装填封率分别为1%、5%、10%条件下的淡化浓盐水真空膜蒸馏性能.在真空膜蒸馏中试试验中,研究膜组件高径比分别为10∶3、70∶9、10∶1,装填封率分别为7.11%、9.48%、14.22%条件下的膜蒸馏性能.结果表明,在同等条件下高径比或装填封率越小时,膜蒸馏的渗透通量越大.淡化浓盐水VMD过程产品水脱盐率均在99.9%以上.     

An analytical approach to determination of bending modulus of a multi-layered graphene sheet

In this paper, the bending modulus of a multi-layered graphene sheet is investigated using a geometrically based analytical approach. For this purpose, a bending potential energy is derived, based on the van der Waals interactions of atoms belonging to the two neighboring sheets of a double-layered graphene sheet. The inter-atomic spacing between the adjacent layers is determined along the line of action of the applied bending moments. The bending potential of the double-layered sheet is calculated by summing up the potentials at discrete hexagons over the length and width of the sheet. A multi-layered graphene sheet is considered as consisting of many stacking double-layers. It is observed that the bending modulus of a multi-layered graphene sheet does not depend on the length of the sheet and is a property for the multi-layered sheet.     

Nanoscale vibration analysis of embedded multi-layered graphene sheets under various boundary conditions

The present article deals with the vibrational analysis of multi-layered graphene sheets with different boundary conditions amongst sheets. An elastic multiple-plate model is utilized in which the nested plates are coupled with each other through the van der Waals interlayer force. The interaction of van der Waals forces between adjacent and non-adjacent layers and the reaction from the surrounding media are included in the Reissner–Mindlin-type field equations on which the theoretical formulation is based. The set of coupled equations of motion for the multi-layered graphene sheets is then solved by the generalized differential quadrature method. The numerical analysis presented herein provides the possibility of considering various combinations of layerwise boundary conditions in a multi-layered graphene sheet. Based on exact solution, explicit formulas for the frequencies of a double-layered graphene sheet with all edges simply supported are also obtained. The results of the present numerical solution are shown to be in excellent agreement with those of exact solution for simply supported graphene sheets.     

Direct Forming of All-Polypropylene Composites Products from Fabrics made of Co-Extruded Tapes

Many technologies presented in literature for the forming of self-reinforced or all-polymer composites are based on manufacturing processes involving thermoforming of pre-consolidated sheets. This paper describes novel direct forming routes to manufacture simple geometries of self-reinforced, all-polypropylene (all-PP) composites, by moulding fabrics of woven co-extruded polypropylene tapes directly into composite products, without the need for pre-consolidated sheet. High strength co-extruded PP tapes have potential processing advantages over mono-extruded fibres or tapes as they allow for a larger temperature processing window for consolidation. This enlarged temperature processing window makes direct forming routes feasible, without the need for an intermediate pre-consolidated sheet product. Thermoforming studies show that direct forming is an interesting alternative to stamping of pre-consolidated sheets, as it eliminates an expensive belt-pressing step which is normally needed for the manufacturing of semi-finished sheets products. Moreover, results from forming studies shows that only half the energy was required to directly form a simple dome geometry from a stack of fabrics compared to stamping the same shape from a pre-consolidated sheet.     

铝合金-聚合物复合层板弯曲回弹理论分析

针对铝合金-聚合物复合层板弯曲回弹问题,分析了复合层板弯曲过程表面层铝板及中心层聚合物的变形特征,建立了复合层板平面应变纯弯曲回弹理论分析模型.采用建立的模型预测了复合层板纯弯曲过程回弹角变化,并与实验结果进行了对比,分析了聚合物层厚度及铝合金板材力学性能对回弹的影响规律.结果表明:随着中心聚合物层厚度的增加,复合层板回弹角降低;随着表面层铝板强度的降低,复合层板回弹角减小.理论预测结果与实验结果一致,说明了本文推导的理论模型的可靠性.     

Vibration characteristics of embedded multi-layered graphene sheets with different boundary conditions via nonlocal elasticity

A nonlocal elastic plate model accounting for the small scale effects is developed to investigate the vibrational behavior of multi-layered graphene sheets under various boundary conditions. Based upon the constitutive equations of nonlocal elasticity, derived are the Reissner–Mindlin-type field equations which include the interaction of van der Waals forces between adjacent and non-adjacent layers and the reaction from the surrounding media. The set of coupled governing equations of motion for the multi-layered graphene sheets are then numerically solved by the generalized differential quadrature method. The present analysis provides the possibility of considering different combinations of layerwise boundary conditions in a multi-layered graphene sheet. Based on exact solution, explicit expressions for the nonlocal frequencies of a double-layered graphene sheet with all edges simply supported are also obtained. The results from the present numerical solution, where possible, are indicated to be in excellent agreement with the existing data from the literature.     

Preparation of zeolite sheet using a papermaking technique Part II The strength of zeolite sheet and its hygroscopic characteristics

Zeolite has been widely applied to practical processes in various industrial fields as a desiccant, an adsorbent, a molecular sieve, an ion exchanger, a catalyst and so on. It has generally been used in the form of beads or pellets. However, these methods of utilization have some disadvantages such as powdering of the zeolite when particles rub against each other and remarkable pressure losses in reaction towers with increasing gas flow velocities. Zeolite sheets consisting of 10% cotton linters pulp, about 30% ceramic fiber and 60% zeolite were easily prepared using a papermaking technique intending to produce their honeycomb structure. The sheets were ignited at 700°C to remove linters pulp, but they were fragile and brittle. To improve the zeolite sheet strength, alumina sol was used as a binder. Although a very high retention of alumina was achieved by the internal addition method with polymer retention aids, the improvement of sheet strength was not satisfactory. In this case, the added alumina seemed to be located mainly on the outermost surface of the sheet because the retention of alumina occurred through the filtration. On the other hand, soaking of zeolite sheets in the alumina sol increased the sheet strength remarkably. These results suggested that the alumina was distributed in the whole sheet and formed a tight network structure between particles. These procedures are expected to lead to useful zeolite products, which have a potential for new practical uses.     

FRACTURE TYPES AND THICKNESS DISTRIBUTION IN SUPERPLASTIC SHEETS FORMED WITH PLASTIC INJECTION MOLDING

This paper investigated the fracture types and thickness ratio distribution in superplastic Zn-22% Al sheets formed during a hybrid process combining superplastic forming with plastic injection molding. Three types of sheet fractures (edge crack, central crack, and combined crack) were observed. The effects of using this approach on sheet molding and fracture window for various parameters, including melt temperature, injection pressure, and mold temperature, were investigated. They are presented and discussed as they relate to molding area and various fracture types. Central cracks occurred when superplastic sheets were formed by injection molding at higher melt temperature, whereas edge cracks occurred at higher injection pressure. When melt flow was parallel to the sheet rolling direction, areas of edge crack were enlarged. The sheet thickness ratio distribution was obtained for various injection parameters and rib depths. Observation of sheet thickness distribution for variation parameters, and the tendency for fracture can be generalized.     

Nanocarbon-induced rapid transformation of polymer surfaces into superhydrophobic surfaces

We present a facile method for fabricating superhydrophobic polymer surfaces by solubility modulation and nanocarbon (NC)-induced crystallization of polycarbonate (PC). The method consists of dipping polymer sheets in a solvent in which the polymer is partially soluble and then inducing solution crystallization by dipping the sheet in a poor solvent for several seconds. A solvent mixture of methyl ethyl ketone and isopropyl alcohol (IPA) was optimized to shorten the crystallization time in a poor solvent. Single-walled carbon nanotubes, multiwalled carbon nanotubes (MWNTs), and graphene sheets were used to nucleate PC crystallization. In particular, monolayer graphene sheets were prepared by reducing graphene oxide with hydrazine. Crystalline micro- and nanostructures rapidly formed upon dipping of the PC sheets in the solution containing NCs, followed by immersion in IPA. The structures depended on the dimensions of the NCs. Especially, in the MWNT solution, dipping for 10 s was sufficient to create a superhydrophobic surface. Crystallization of PC and the incorporation of NCs during crystallization were characterized by Raman spectroscopy.     

Thermoforming woodfibre–polypropylene composite sheets

Thermoforming of woodfibre–polypropylene composite sheets made without any modification of the fibres or the polymer is the focus of this paper, the emphasis being on their formability and the associated issues. Both the degree to which a material conforms to the desired part geometry after deformation and the extent to which a sheet material may be deformed before unacceptable defects occur are considered. Four thermoforming processes such as V-bending, die-match forming, air pressure forming and deep drawing have been utilised to examine both single-curvature and double-curvature deformation conditions. The technique of Grid Strain Analysis (GSA) has been applied to quantify differences in strain distributions during sheet deformation. The effects of thermoforming process parameters and sheet composition on sheet formability are also discussed. Notably, this study considers composite sheets reinforced with wood fibres rather than woodflour, enabling the study of fibre layup and fibre interlocking effects. While the tensile strengths of the composite sheets increase marginally the stiffnesses increase significantly compared to those of unreinforced polypropylene. The key deformation mechanism for layered woodfibre–polypropylene composite sheets is inter-ply shear while intra-ply shear dominates the deformation of homogeneous sheets. Forming temperature and blank size have the most pronounced effects on the formability of these composite sheets.     

Transfer of fibroblast sheets cultured on thermoresponsive dishes with membranes

In cell or tissue engineering, it is essential to develop a support for cell-to-cell adhesion, which leads to the generation of cell sheets connected by extracellular matrix. Such supports must be hydrophobic and should result in a detachable cell sheet. A thermoresponsive support that enables the cultured cell sheet to detach using only a change in temperature could be an interesting alternative in regenerative medicine. The aim of this study was to evaluate plates covered with thermoresponsive polymers as supports for the formation of fibroblast sheets and to develop a damage-free procedure for cell sheet transfer with the use of membranes as transfer tools. Human skin fibroblasts were seeded on supports coated with a thermoresponsive polymer: commercial UpCell? dishes (NUNC?) coated with thermoresponsive poly(N-isopropylacrylamide) (PNIPAM) and dishes coated with thermoresponsive poly(tri(ethylene glycol) monoethyl ether methacrylate) (P(TEGMA-EE)). Confluent fibroblast sheets were effectively cultured and harvested from both commercial PNIPAM-coated dishes and laboratory P(TEGMA-EE)-coated dishes. To transfer a detached cell sheet, two membranes, Immobilon-P^® and SUPRATHEL^®, were examined. The use of SUPRATHEL for relocating the cell sheets opens a new possibility for the clinical treatment of wounds. This study established the background for implementing thermoresponsive supports for transplanting in vitro cultured fibroblasts.