Ca2+对悬浮培养HEK293细胞的细胞团形成、细胞生长和代谢的影响

利用HEK293细胞在悬浮培养中具有聚集成团的体外培养特性,在250ml的Bellco的搅拌培养体系中,以细胞团粒径、细胞粒径、细胞数、细胞活力、葡萄糖比消耗速率 (qglc)、乳酸比生产速率 (qlac) 和乳酸对葡萄糖得率 (Ylac/glc) 为观察指标,考察了HEK293细胞在Ca2 浓度设置为0μmol/L、250μmol/L、500μmol/L、750μmol/L和1000μmol/L的搅拌培养体系中的细胞团形成、细胞生长和代谢.实验发现:培养基中的Ca2 浓度决定着HEK293细胞在悬浮培养中能否形成细胞团并影响着细胞团的粒径分布和细胞团内细胞相互连接的紧密程度;在250～1000μmol/L的Ca2 浓度范围内,HEK293细胞团的平均粒径与培养基中的Ca2 浓度成正比;Ca2 浓度对以细胞团的形式悬浮培养的HEK293细胞的生长和代谢无明显的影响.实验结果提示,Ca2 浓度是调节HEK293细胞团粒径分布、维持悬浮细胞团中HEK293细胞正常生长和代谢的有效控制参数.     

纯钨靶在电子轰击下的失效分析

在正常工作的条件下,部分医用X射线管中的纯钨靶表面会逐渐变得粗糙,在粗糙区进一步会出现表面裂纹,但同型号的进口钨靶表面却几乎没有粗糙区和裂纹出现。采用SEM、EDS和化学成分测试等方法,对两种钨靶进行了研究和比较。结果显示,杂质元素的含量偏高和沿晶界的偏析以及不均匀的钨晶粒是造成国产钨靶表面损伤的主要原因。     

Fabrication, in vitro Degradation and Cytotoxic Assay of Different Cystalline Phases Calcium Polyphosphate

1Introduction Mostofthematerialsusedhistoricallyarecalcium phosphatessuchashydroxyapatite(HA),tricalciumphosphates(TCP),tetracalciumphosphate(TTCP),and cominationofthevariousphasesofcalciumphosphates[1].Calciumphosphatematerialshavesomeoutstandingprop ert…     

微球堆积法制备多孔磷酸钙生物材料

以壳聚糖为原料 ,用乳液凝固法合成了壳聚糖微球。利用造孔剂成孔的特点 ,在有机模具中将壳聚糖微球紧密堆积 ,形成孔隙率至少为 2 6 %的多孔结构的框架 ,再将料浆灌注到框架中 ,充满空隙。干燥后经 6 0 0°C煅烧和12 0 0°C烧结 ,将有机模具及壳聚糖微球烧去 ,获得具有大孔和贯通式微孔的多孔磷酸钙生物材料。材料孔隙率在 6 0～70 %之间 ,大孔直径为 80 μm～ 2 5 0 μm ,孔径可控且分布均匀 ,平均抗压强度为 4 .5 8MPa。     

Van Der Waals Force and Asphalt Concrete Strength and Cracking

Van der Waals force between neutral molecules is employed to characterize the interaction among molecules in asphalt cement. Several important consequences emerge from the consideration. The brittle strength of the asphalt binder is shown to be linked to the well depth of the Van der Waals potential and the mesoscopic cracks present within the asphalt binder. Moreover, the elastic modulus of asphalt binder is analytically related to the potential well depth. The strength of the asphalt concrete (AC) is estimated by considering aggregate surface characteristics and the adhesion strength between asphaltenes or resins and molecules of aggregates. These predictions can help design asphalt concrete pavement. Formulas for predicting the binder strength and the interfacial breaking strength between aggregates and binders are derived. These results are supported by reported data. Furthermore, an analytic expression for the strength of AC is given at temperature below the AC glass transition point.     

以碳酸氢铵为沉淀剂制备纳米钇铝石榴石粉体

以碳酸氢铵为沉淀剂,硝酸盐为原料,采用沉淀法,通过仔细控制沉淀过程的工艺参数,得到了煅烧后可直接生成纯相YAG的前驱体沉淀物,前驱体经过900℃煅烧即可获得纳米YAG粉体.BET,TEM和XRD的测试结果表明纳米YAG粉体的晶粒尺寸为67～175nm,晶粒形态为球形,分散性良好.粉体达到完全致密化的最低烧结温度为1450℃.所获得的粉体经过1700℃真空烧结3h,烧结体具有一定的透明度.研究表明,这种纳米YAG粉体所具有的良好烧结活性与粉体的纳米晶粒尺寸,球形晶粒形态及极佳的分散性有关.     

电解法研制氧化亚铜

对电解法生产氧化亚铜进行试验研究，提出了电解法生产氧化亚铜的工艺方法，确定了最佳工艺条件。试验产品质量达化工行业标准。     

Modification of High Performances of Polymer Cement Concrete

1　ＩｎｔｒｏｄｕｃｔｉｏｎＴｈｅｈｉｇｈｍｅｃｈａｎｉｃａｌｐｒｏｐｅｒｔｉｅｓ ,ｇｏｏｄｄｕｒａｂｉｌｉｔｙａｎｄａｐｐｒｏｐｒｉａｔｅｗｏｒｋａｂｉｌｉｔｙａｒｅｎｅｃｅｓｓａｒｙｆｏｒｈｉｇｈｐｅｒｆｏｒｍａｎｃｅｃｏｎｃｒｅｔｅｔｏｓａｔｉｓｆｙｔｈｅｃｏｎｓｔｒｕｃｔｉｏｎｒｅｑｕｉｒｅｍｅｎｔｏｆｌａｒｇｅ ｓｃａｌｅｃｏｎｃｒｅｔｅｅｎｇｉｎｅｅｒｉｎｇ .Ａｃｃｏｒｄｉｎｇｔｏｄｉｆｆｅｒｅｎｔａｐｐｌｉｃａ ｔｉｏｎｓａｎｄｐｕｒｐｏｓｅｓ ,ｉｎｏｒｄｅｒｔｏｉｍｐｒｏｖｅｔｈｅ…     

The hydration characteristics and expansion machanism of expansive cement at low<Emphasis Type="Italic">W/B</Emphasis> ratio

The hydration characteristics and expansion impetus of three kinds of cement paste under free-and confined-curing conditions were investigated, which were respectively mixed with three different kinds of expansive agent at low W/B ratio. The results show that the hydration products of pure cement paste and paste mixed with expansive agent are same, but the amount of hydration products, un-hydrated C₃S and C₂S are obviously different at the same hydration age. At 3 d age, the amount of CH in pure cement paste is less than that of paste mixed with expansive agent, but it is reverse when at 28 d age. The amount of AFt at 3d and 28d age in pure cement paste is less than those of paste mixed with expansive agent. Regardless of under free- or confined-curing condition, the amount of ettringite produced varies little since 3d age. The joint effect of the tumefaction of gel-ettringite due to water absorption and the expansive pressure on the pore caused by the crystalloid ettringite is the cause of the volume expansion of cement paste, and the former effect is much greater than the latter. LU Lin-nu : Born in 1972 Funded by 973 High-tech Project of China (No. 2001CB610704-2) and the Natural Science Foundation of Hubei Province(No. 2002AB075)     

MODBUS通信协议在现场水泥成分X荧光分析仪中的应用

首先对MODBUS通信协议进行了简单介绍，然后讨论了采用MODBUS通信协议的水泥成分X荧光分析仪是如何实现与水泥生产自动化总控制系统之间的数据传输的，由此达到控制水泥配料系统自动配料的目的。并给出了Visual C^ 下实现通讯的方法。