Relationship between lattice mismatch and ionic conduction of grain boundary in YSZ

The grain boundary plays an important role in the electrical behaviors of solid oxide electrolytes for solid state fuel cells. To reveal the relationship between the structure and the ionic conductivity of grain boundary,the conductive properties of {1 1 1} and {1 1 0} twist grain boundaries in 8 mol% yttria-stabilized zirconia have been examined. These boundaries have a series of Σ values defined by the coincident site lattice model. It has been found that the activation energy of {1 1 1} twist grain boundary increases and then decreases with the Σ value,while that of the {1 1 0} boundary shows an opposite trend. It is suggested that the properties can reflect the balance of the effects of lattice mismatch on the diffusion ability of oxygen vacancies and the segregation of oxygen vacancies and Y3 tions. Therefore,the properties in polycrystalline electrolyte can be adjusted by controlling the grain boundary structures.     

DNA损伤修复蛋白在胆囊病变组织中的表达及其临床意义

目的 研究胆囊腺癌、癌旁组织、腺瘤性息肉和慢性胆囊炎组织中DNA损伤修复蛋白hMSH2和hMLH1表达及其临床意义.方法 选取胆囊腺癌108例、癌旁组织46例、腺瘤性息肉15例和慢性胆囊炎35例手术切除标本常规作石蜡包埋切片,采用EnVisionTM免疫组化法检测hMSH2和hMLH1.结果 hMSH2和hMLH1表达阳性率,胆囊腺癌分别为50.0%和49.1%、评分分别为2.2±1.9和2.2±1.8,均明显低于癌旁组织（阳性率分别为84.8%和87.0%;评分分别为3.9±1.3和4.2±1.2）、腺瘤性息肉（阳性率分别为80.0%和86.7%;评分分别为3.7±1.3和4.0±1.1）及慢性胆囊炎组织（阳性率分别为88.6%和88.6%;评分分别为4.1±1.1和3.9±1.1）（P＜0.05）;不同类型良性病变中2种DNA损伤修复蛋白表达阳性率及其评分均无明显差异（P＞0.05）.hMSH2和hMLH1表达阴性的良性病变胆囊上皮均呈中至重度不典型增生的病理形态学表现.腺瘤癌变或高分化腺癌、肿块最大径＜2 cm,无淋巴结转移及未侵犯周围组织的病例hMSH2和hMLH1表达阳性率及其评分均明显地高于低分化腺癌、肿块最大径≥2 cm、淋巴结转移及侵犯周围组织病例（P＜0.05）;2种DNA损伤修复蛋白表达与患者性别、年龄及有无胆囊结石均无明显关系（P＞0.05）.结论 DNA损伤修复蛋白表达水平均为反映胆囊腺癌发生、进展、临床生物学行为及预后的重要标记物,检测其表达水平对指导预防和早期发现、临床化疗胆囊癌可能有一定临床意义.     

一种电流舵DAC电流源失配补偿算法与实现

对高速高精度电流舵模数转换器(DAC)的非理想因素影响进行消除已经成为研究热点。提出了一种基于"方向随机"和"特定代码随机"的电流源单元动态随机选取算法,并采用SMIC0.13μm CMOS工艺实现,具有较优的功耗、面积和速度指标。最终对算法建立Verilog-A电路级模型并应用在14位200 MHz电流舵DAC上,仿真表明SFDR达到90 dB以上。     

一个具有四翼的混沌吸引子的混沌系统的分析与同步控制

在提出一个具有四翼混沌吸引子和每个方程含有一个三次非线性交叉乘积项的新复杂四维连续自治系统基础上,依据Lyapunov稳定性定理,采用非线性反馈控制,通过构造合适的响应系统,实现了新系统的错位同步控制．数值仿真结果表明,该非线性反馈控制器所要求的控制律简单易于实现,且收敛速度快．     

Some features of base pair mismatch repair and its role in the formation of genetic recombinants

For the formation of recombinants involving closely linked markers, two distinct processes play a role. The recombinational interaction between homologous DNA molecules results in the presence of heteroduplex DNA joining the parental components of the recombinant. The presence of markers distinguishing the parents in the region of heteroduplex DNA can result in base pair mismatches. The post recombination repair of such mismatches can contribute to the separation of closely linked markers. The processes responsible for such repair also play roles in mutation avoidance. The specificities, functions and contribution to the formation of recombinants for closely linked markers of the processes inEscherichia coli are described.