P2O5与CaF2制备PF5工艺研究

以P2O5与CaF2为原料,采用加热的方法制备PF5气体,并研究了反应温度、反应时间及P2O5和CaF2质量比对PF5产率的影响。结果表明,制备PF5的最佳条件：反应温度控制在280-300℃,反应时间5h,PF5和CaF2质量比为2．5：1。     

奥氏体化时间对22MnB5热压成形钢组织和性能的影响

目前就奥氏体化时间对热成形钢组织结构和力学性能的研究较少。采用万能材料试验机和金相显微镜研究了900℃下奥氏体化时间对22Mn B5热压成形钢组织结构和力学性能的影响,得出了22Mn B5热压成形钢的性能随奥氏体化时间的变化规律。结果表明:22Mn B5钢在900℃下奥氏体化5 min,得到的热成形钢具有板条状马氏体,且马氏体的硬度最高,试样的强度较高,塑性较好。     

Al-5Ti-1B对A357合金晶粒细化作用的研究

采用Al-5Ti-1B中间合金作为细化剂细化A357合金,考察细化剂加入量、保温温度及熔体在不同温度下保温时间对晶粒尺寸的影响,研究了Al-5Ti-1B中间合金对A357合金晶粒细化效果.研究表明:Al-5Ti-1B可明显减小A357合金的晶粒尺寸,并且在较长的时间内保持良好的细化效果;熔体长时间静置后易出现(钛)偏析,底部Ti含量比顶部要高,致使铸件整体细化效果大大降低;定期对熔体进行搅拌可有效消除偏析.     

Dissolution of Some Lithium Dosage Forms and Correlation with Enslin Number

The biopharmaceutic parameters of six conventional and one sustained release lithium carbonate commercial products were determined. From the dissolution data mean residence time, dissolution rate constants, and percent dissolved at 5 and 10 minutes were obtained. The ENSLIN numbers were compared with mean residence time and percent dissolved at 5 and 10 minutes. A good correlation was obtained between ENSLIN number and mean residence time for the conventional preparations.     

两步晶化法制备MCM-48/ZSM-5复合分子筛

利用两步晶化法制备了高水热稳定性的MCM48/ZSM-5介微孔复合分子筛.通过SEM、TEM、XRD、IR和N₂吸附脱附进行表征,结果显示,该材料的结构不同于简单的机械混合,而是具有微孔孔壁和三维立方介孔孔道的复合材料,其孔道尺寸为2.6nm左右.该复合分子筛在沸水中处理6h后,介孔结构仍保留完好.通过考察晶化时间对复合分子筛的影响,证明了介孔和微孔的组装是一个竞争的过程,复合分子筛中介孔与微孔结构的比例随晶化时间的变化而变化,且具有介孔孔道和微孔孔壁的复合分子筛150℃的最优晶化时间为8h.     

Dissolution of Some Lithium Dosage Forms and Correlation with Enslin Number

Abstract

The biopharmaceutic parameters of six conventional and one sustained release lithium carbonate commercial products were determined. From the dissolution data mean residence time, dissolution rate constants, and percent dissolved at 5 and 10 minutes were obtained. The ENSLIN numbers were compared with mean residence time and percent dissolved at 5 and 10 minutes. A good correlation was obtained between ENSLIN number and mean residence time for the conventional preparations.     

Pseudo first-order adsorption kinetics of N719 dye on TiO2 surface

We have investigated the adsorption kinetics of Ru-based N719 dye on TiO(2) surface in dye-sensitized solar cell using 0.5 mM and 5 mM dye solutions. The amount of adsorbed dye on TiO(2) surface of ca. 5 μm-thick film was measured as a function of immersion (adsorption) time. The amount of adsorbed dye increases with increasing the adsorption time and keeps constant after saturation. Completion of dye adsorption is found to be more than 5 times faster in 5 mM than in 0.5 mM. Since the change of dye concentration is negligible compared to that of number of TiO(2) adsorption site, reaction order and rate constant can be estimated from a pseudo reaction. Among the zeroth-, first-, and second-order simulation, the observed data follow first order reaction for both 0.5 mM and 5 mM cases. The rate constant is estimated to be 0.504 min(-1) for 5 mM and 0.094 min(-1) for 0.5 mM, which indicates that completion of dye adsorption is about 5 times shorter in 5 mM than in 0.5 mM. This is consistent with the observed adsorption time difference. Except for the difference in adsorption kinetics, best cell efficiency is similar regardless of dye solution concentration.     

星敏感器曝光时间的优化

星敏感器曝光时间是影响星敏感器星点定位精度的因素之一.建立星敏感器星点像移模型和CCD噪声影响模型,分析了星点质心定位精度与曝光时间的关系,并以CCD47-20为例,对星敏感器的曝光时间进行了优化.结果表明:对于6.5等星,当星点光斑像移速度为4.67 pixels/s时,采用5×5窗口的亚像元质心算法,亚像元质心算法精度随曝光时间的延长而降低,CCD噪声对星点质心定位精度的影响随曝光时间的增加而减小;星敏感器的最佳曝光时间为200 ms,此时的星点质心定位精度优于1/50 pixel.     

Effect of deposition time on morphology,corrosion resistance and mechanical properties of Ti-containing conversion coatings on zinc

Ti-containing conversion coatings were obtained on zinc electroplated steel. The influence of deposition time on the coatings morphology, chemical composition, corrosion resistance and mechanical properties were studied. Their chemical composition strongly depends on deposition time. As the time increases from 5 s to 300 s, the Ti content decreases and the Si content increases. For the deposition time of 5 s the Si:Ti atomic ratio in the conversion coating is 0.32 and after 300 s it increases to 9.1, which is accompanied by reduction in corrosion resistance. As deposition time increases, the microhardness of the coatings and their wear resistance deteriorate. Corrosion test results show that the coatings can be applied to protect zinc against corrosion.     

几种非复合薄膜安全性能的评价

研究了塑料包装材料对长时间存放的液体食品中不挥发物的迁移规律。采用食品包装常用的5 种塑料薄膜,在常规试验条件下,研究了不同模拟浸泡液中的不挥发物总量与浸泡时间的线性关系,延长浸泡时间至120 d 以及在极限试验条件下的不挥发物迁移量。在3 种浸泡液中的不挥发物总量均随着浸泡时间的增加而增大,在乙酸浸泡液(4%)中的迁移总量最多,最大值为28. 5 mg/ L,在乙醇浸泡液(65%)中的迁移总量最少,最大值为20. 5 mg/ L,A 薄膜在长达120 d 的模拟浸泡液中,不挥发物总量达到了55. 5 mg/ L,极限使用条件下,在正己烷浸泡液中的迁移总量最多,最大值为95. 5 mg/ L。在3 种浸泡液中5 种薄膜均存在迁移行为,危害程度有待评估。     

强化研磨微纳加工参数对轴承套圈滚道表面硬度的影响

目的 探明不同加工参数对加工表面平均硬度的影响规律。方法 用强化研磨微纳加工技术对6012深沟球轴承内圈滚道表面进行强化处理,通过设置不同的喷射压力、加工时间、喷射角度及钢珠配比获得加工试样。采用洛氏硬度计分别检测加工前后套圈滚道表面硬度,并分析其随各参数变化的规律。结果 加工时间为5 min,喷射角度为45°,喷射压力为0.4～0.6 MPa时,表面硬度随喷射压力的增大而增大,0.6 MPa后维持在HRC61.60附近;喷射压力为0.6 MPa,喷射角度为45°,加工时间为1～5 min时,表面硬度及其增量随时间增加而增大,其后在HRC61.50附近徘徊;喷射压力为0.6MPa,加工时间为5min,喷射角度为35°～55°时,试样表面硬度及其增量先减小后增大,喷射角度达50°后,表面硬度达最大值HRC63.45;钢珠配比则对试样表面硬度影响不大,加工所得试样在HRC61.67～HRC61.80之间。结论 试样表面硬度及其增量随喷射压力、加工时间及喷射角度的增加而增加,且受加工时间影响最大。当加工时间为5 min,喷射压力为0.6 MPa,喷射角度为50°时,可获得较高的平均表面硬度。     

一种由NIM5铯喷泉基准驾驭实现的独立时标TA（NIM）

原子时标TA（NIM）是一个独立时标,其频率由NIM5铯喷泉基准驾驭。产生时标的主钟是一台主动型氢原子钟,铯喷泉基准定期对其测量和校准。时标算法通过预估氢钟将来的频率,补偿过去预估频率与校准频率之差,并评估无校准数据期间的氢钟频率,最终尽可能实现TA（NIM）的频率与NIM5铯喷泉基准保持一致。2007年8月,TA（NIM）开始试运行,2008年6月正式运行。1年多来的数据分析表明,TA(NIM)运行连续可靠,与TAI间的时间稳定度(5天)达到1.2 ns,相对频差为2.0×10^-15。     

制备工艺对锌铝氧化物(ZAO)粉末红外发射率的影响

采用液相共沉淀法制备了ZAO掺杂半导体粉末材料,系统研究了制备工艺对ZAO粉末红外发射率的影响.借助于TG-DTA、XRD、SEM对材料的热处理温度,晶体结构及表面形貌进行了考察,利用IR-2双波段发射率测量仪对ZAO粉末材料的红外发射率进行了测试.研究结果表明:当反应物终点pH值为8.5、反应时间为2.5h、煅烧温度为800℃,煅烧时间为2h、Al2O3的掺杂量为3%时所得的ZAO粉末的红外发射率最低;ZAO掺杂半导体粉末的晶体结构为ZnO的铅锌矿结构;粒子形状近似为椭圆形,平均粒径为5～10μm;在中红外(3～5μm)和远红外(8～14μm)波段均具有较低的红外发射率.     

1 200 MPa级HSLA钢的SH-CCT曲线及其热影响区组织与性能

为在工程应用中对焊接工艺的合理选取与制定提供理论和试验依据,采用焊接热模拟技术研究了800~500℃冷却时间(t8/5)对1 200 MPa级低合金高强钢焊接热影响区粗晶区(CGHAZ)显微组织和性能的影响.结果表明:t8/5为6~20 s时,该钢热影响区的粗晶区组织为板条马氏体,硬度为477~456 HV5;随着冷却时间的延长,组织中开始出现板条贝氏体,在t8/5为60 s时硬度下降到380 HV5;当t8/5为60~600 s时,粗晶区组织为板条贝氏体和粒状贝氏体,硬度为380~300 HV5;t8/5600 s时粗晶区组织主要为粒状贝氏体,硬度为300~315 HV5.试验钢碳当量为0.626%,冷裂纹敏感系数为0.335%,说明其淬硬倾向较大,焊接热影响区容易产生裂纹.     

Determination of optimal exposure time for imaging of blood flow changes with laser speckle contrast imaging

Laser speckle contrast imaging is becoming an established method for full-field imaging of cerebral blood flow dynamics in animal models. The sensitivity and noise in the measurement of blood flow changes depend on the camera exposure time. The relation among sensitivity, noise, and camera exposure time was investigated experimentally by imaging the speckle contrast changes in the brain after electrical forepaw stimulation in rats. The sensitivity to relative changes in speckle contrast was found to increase at longer exposure times and to reach a plateau for exposure times greater than approximately 2 ms. However, the speckle contrast noise also increases with exposure time and thus the contrast-to-noise ratio was found to peak at an exposure time of approximately 5 ms. Our results suggests that approximately 5 ms is an optimal exposure time for imaging of stimulus-induced changes in cerebral blood flow in rodents.     

激光水下PPM通信中的脉宽稳定技术研究

云层使PPM光脉冲产生时间扩展。全信号检测带来困难。给出平均多路经时间扩展的计算式。并提出了克服困难的一种方法：将电脉冲非线性展宽，以减小云层厚度对脉宽度的影响。模拟实验表明，当输入脉冲宽度变化范围20ns-5μs时，输出脉冲宽度变化为1-5μs。     

高能球磨Gd5Si1.8Ge1.8Si0.4合金的磁性能及相组成

采用电弧熔炼的方法制备了具有一级磁晶相变Gd5Si1.8Ge1.8Si0.4母合金,然后在不同时间条件下对其进行高能球磨,并研究球磨时间对该磁热合金的磁性能及相组成的影响.粉末XRD结果显示球磨没有改变Gd5Si2Ge2相,但拓宽了相应的布拉格衍射峰,这表明球磨后的合金的晶粒尺寸较小.另外,球磨后的合金中形成了一些非晶相.随着晶粒尺寸和磁畴的减小,与母合金相比,希望其滞后现象减小.     

The synthesis of nano-sized ZSM-5 zeolite by dry gel conversion method and investigating the effects of experimental parameters by Taguchi experimental design

In this study ZSM-5 Nano particles with high crystallinity were synthesized using a dry gel conversion technique. An L9 orthogonal array of the Taguchi method was applied to investigate the effect of synthesis parameters, such as crystallization time, gel drying temperature, molar composition of template (TPAOH) and water content in the crystallization stage on crystallinity and particle size of the ZSM-5 catalyst. The products were characterized by X-ray diffraction (XRD) and scanning electron microscopy (SEM). Beside short crystallization time, the particle sizes were considerably smaller in comparison with those prepared using the hydrothermal method. The results showed that the particle size and crystallinity increased with increasing water content and crystallization time. The effects of gel drying temperature and molar composition of template were found to be more complex, however. Comparing to hydrothermal method, ZSM-5 samples synthesized with the dry gel conversion exhibited higher selectivity to gasoline than other hydrocarbons.     

Synthesis of mesoporous ZSM-5 from rice husk ash with ultrasound assisted alkali-treatment method used in catalytic cracking of light naphtha

A series of mesoporous ZSM-5 zeolite was synthesized with ultrasonic assisted alkali-treatment technique and their catalytic activity was investigated in catalytic cracking of light naphtha. ZSM-5 zeolite was synthesized from rice husk ash without using any organic template. Effect of alkali-treatment conditions on physicochemical properties of synthesized zeolite was investigated with XRD, FESEM, TEM, N2 adsorption-desorption isotherm, NH3-TPD and TGA technique. It was found that ultrasound energy facilitates the creation of hierarchical structure of ZSM-5 during alkali-treatment. According to XRD analysis, zeolite structure was preserved after 20 min ultrasonic assisted alkaline treatment. However, prolonged dessilication time led to the destruction of MFI zeolite structure. The synthesized ZSM-5 represented highly ordered hexagonal-shape morphology. With increasing alkali-treatment time, the plough land roughness appeared on the surface of zeolite. Comparison of the textural properties samples revealed that the mesopore surface area of alkali-treated samples increased considerably with the increase of ultrasonic assisted alkali-treatment time. Results from catalytic activity tests showed that ultrasound energy has great influence on the activity of ZSM-5. The sample had the highest activity after alkali-treated for 20 min in presence of ultrasound energy which was due to their appropriate hierarchical structure.     

低温对时效态TC4合金拉伸性能的影响

在77－300K温度范围内对不同时6效状态TC4合金进行拉伸试验，研究了低温对时效态合金拉伸性能的影响。时效温度取813天，时效时间分别为0．5h、7h、60h。试验结果表明：在室温下，时效0．5h合金与退火态合金相比强度明显提高，延伸率略有降低；时效时间大于0．5h，随时效时间的延长，合金的强度与延伸率均下降。随试验温度的降低，3种时效态合金的强度都单调增加，延伸率先是下降，但在77K时又略有升高，TEM观察表明，随着试验温度的降低，拉伸断口附近位错分布不均匀性增大。