宁夏高校新生乙型肝炎知识和正向态度的调查

目的：调查宁夏地区大学生新生有关乙型肝炎防治知识的认知情况，为开展健康教育提供基线资料。方法：采取分层整群抽样方法，对宁夏1000名大学新生进行问卷调查。结果：对乙型肝炎一般知识、传播途径的正确回答率宁夏医学院新生高于宁夏大学和宁夏农学院新生，传播途径得分女生高于男生；正向态度得分宁夏大学新生高于其它2校，汉民高于回民；乙肝的一般知识、传播途径及正向态度得分城市学生均高于农村，差异均有显著性。结论：大学生对乙肝的防治知识有一定了解，但不全面，不系统，不均衡，开展健康教育非常重要。     

Estenia瓷树脂复合体制作冠桥的强度测试

目的:探讨Estenia瓷树脂复合体的强度,并与其他几种树脂材料进行比较,为临床选择冠桥树脂材料提供参考。方法:采用Estenia瓷树脂复合体体外模拟下颌第一磨牙单冠和第一磨牙缺失3个单位固定桥的形态,测试单冠的抗压强度和固定桥的抗弯强度,并与Artglass、Solidex、Targis3种树脂材料在相同实验方法下测试得到的结果作比较。结果:Estenia瓷树脂单冠的折裂最大载荷均值为600.20N,Estenia瓷树脂桥的折裂最大载荷均值为302.53N。结论:Estenia瓷树脂复合体的强度高于Artglass﹑Solidex和Targis树脂复合体。     

The influence of support conditions in the loading fixture on failure mechanisms in the push-out test: a finite element study

The usefulness of the push-out test as an indicator of interface strength was evaluated using finite element models of intact and partially failed cylindrical push-out specimens loaded against a rigid annular support. The irregular stress distributions that were found in intact specimens depended more on interface conditions at the loading fixture than on a 35% increase in interface area. The maximum stress at the interface was a tensile stress. Critical energy release rates for interface failure were calculated for flawed specimens in which flaw size was either 10 or 100 microns, and for boundary conditions at the loading fixture that were either fixed or slipping in the radial direction. The critical energy release rates depended heavily on the support boundary conditions. Thus, the results of parametric push-out tests can be reasonably compared only for specimens that are very similar in geometry and that are loaded in very carefully controlled fixtures.     

中国西部城市和农村开展面粉营养素强化的可行性分析

目的通过对甘肃农产区居民的饮食习惯、营养知识和态度的调查,从需方的角度对开展面粉营养素强化的可行性进行探讨。方法采用定性和定量调查相结合的方法,对4个地区的城市和农村的男性和女性分别进行现状和原因的调查分析。结果被调查地区多数城市(92.7%)和农村(60.7%)家庭日常饮食以面食为主,94.7%的城市家庭购买面粉,而在农村地区,多数家庭自己种植或购买小麦。城市居民较农村对营养和维生素有更多的了解和关注。农村男性对面粉营养素强化持怀疑态度,女性更加关注孩子的营养,认为目前的饮食单一,孩子可能营养不足。结论与农村地区相比,城市地区的社会经济条件和知识基础较利于开展面粉强化工作。     

Ex vivo estimation of thoracolumbar vertebral body compressive strength: The relative contributions of bone densitometry and vertebral morphometry

The estimation of vertebral fracture risk in individuals with suspected osteopenia is commonly based on measurements of lumbar spine bone density. The efficacy of vertebral size and deformity, as assessed by vertebral morphometry, in the prediction of fractures has been less studied. In an ex vivo investigation the regional relationships between vertebral size, vertebral deformity, bone density and compressive strength throughout the thoracolumbar spine were examined. In 16 vertebral columns (T1–L5) the bone mineral content (BMC) and bone mineral density (BMD) of each segment were measured using lateral projection dual-energy X-ray absorptiometry, and the vertebral cancellous density (VCD) and mid-vertebral cross-sectional area (CSA) measured using quantitative computed tomography. Vertebral body heights were determined from mid-sagittal CT scans, and vertical height ratios calculated for each segment. The failure load and failure stress of the isolated vertebral bodies were determined using a material testing device. Separate analyses were performed for the upper (T1–4), middle (T5–8) and lower (T9–12) thoracic, and lumbar (L1–5) segments. In all regions, failure load was strongly correlated with BMD (r=0.82–0.86), moderately correlated with VCD (r=0.60–0.71) and vertebral height (r=0.22–0.49), and poorly correlated with the height ratios (r=0.04–0.33). Failure stress was best predicted by BMD (r=0.73–0.78) and VCD (r=0.70–0.78) but was poorly correlated with all morphometric variables (r=0.01–0.33). The segmental correlations between BMD and VCD ranged fromr=0.49 tor=0.79. For all regions, BMD and VCD were included in the stepwise regression models for predicting failure load and failure stress. Either the mid-vertebral height or CSA were included in all the failure load models, while mid-vertebral height was included in only one of the failure stress models. The results suggest that vertebral deformity and size (as assessed by vertebral morphometry) make only a minor contribution to the prediction of vertebral strength additional to that provided by bone densitometry alone. The consistent regional relationships between variables appear to support the practice of global fracture risk assessment based on lumbar spine densitometry.     

用酸蚀法提高纯钛与光固化冠桥树脂粘结强度的研究

目的：研究用酸蚀法提高钛与光固化复合树脂剪切粘结强度的可行性，并观察表面粗糙度与剪切粘结强度之间的关系。方法：采用不同浓度的酸蚀剂对钛铸件表面进行酸蚀，并与artglass光固化复合树脂进行粘结，以单纯喷砂组为对照，比较剪切粘结强度的差异。对酸蚀后及剪切试验后的金属表面进行扫描电镜观察，并测定其表面粗糙度。结果：用酸蚀法可以显著提高钛与复合树脂的粘结强度，HF浓度为4％时粘结强度最高。表面粗糙度随酸蚀剂的浓度增高而下降。结论：纯钛铸件用酸蚀法处理后可以获得较高的粘结强度，HF酸浓度以4％为宜。表面粗糙度对粘结强度不起决定性作用。     

Differential titin isoform expression in human skeletal muscle

Mammalian skeletal muscle expresses at least two isoforms of the cytoskeletal protein titin (connectin; MW ≈ 3000 kDa). These isoforms are associated with different passive force curves, and thus may affect physical performance. To study the distribution of titin and its possible influence on performance in humans, muscle biopsies were obtained from 15 males (X ± SE; age = 25.4 ± 2.9 years, height = 177.7 ± 1.8 cm, weight = 76.5 ± 2.2 kg). Two biopsies were obtained on separate occasions from both the right and left vastus lateralis, and one biopsy each from the lateral head of the right gastrocnemius and the right soleus, with all biopsies handled identically. Fibre type analyses were performed via mATPase histochemistry. Expression of titin and myosin heavy chain isoforms were determined by SDS-PAGE. Titin bands in the resulting gels were highly repeatable and were verified by migration patterns, as well as Western blot analysis. Two groups of subjects were identified: group 1 (n=10) expressed only one titin isoform (titin-1) in all biopsies, and group 2 (n=5) expressed two titin isoforms (titin-1 and titin-2) in all biopsies. No significant differences (P> 0.05) between groups were observed for percentage fibre types, percentage fibre type areas, fibre type cross-sectional areas, and percentage myosin heavy chain expression when comparing individual muscles, sampling times or bilateral comparisons. This is the first report of differential titin isoform expression in healthy, mature human skeletal muscle, but it is not clear why this occurs or what influence this may have on performance.     

The application of percolation theory to the compaction of pharmaceutical powders

Based on the concepts of percolation theory the compaction process is interpreted as a site-bond percolation phenomenon. The combination of the Heckel equation with an equation derived earlier yields a simple relationship between the tensile strength σ_t, or the deformation hardness P and the relative density. This mathematical model is identical with the fundamental law of percolation theory i.e., X = s(p − p_c)^q with X= system property equivalent to tensile strength or deformation hardness, S = scaling factor, p = site occupation or bond formation probability corresponding to the relative density p,p_c = percolation threshold and critical exponent q = 1 according to percolation on a Bethe lattice. In the case of the tensile strength σ_t and the deformation hardness p, two percolation thresholds p_c(1) and p_c(2) corresponding to p_c(1) and p_c(2) could be identified. The relative density p_c(1) which is close to the relative poured or relative tapped density can be interpreted as a bond percolation threshold. The particles are bonded by weak interparticulate forces and form only loose compacts as used for filling of capsules. The relative density p_c(2) is the relative density where the first stable pharmaceutical compact is achieved which can no longer be disintegrated mechanically into its primary particles. It is of special interest that the above equation is also valid for the elastic modulus with the only percolation threshold p_c(1) = p_c(1).     

潍坊市出境劳务人员艾滋病防治知识需求分析

目的为了解外出劳务人员对艾滋病知识的需求和接受程度。方法对外出劳务人员艾滋病防治知识知晓率进行抽样调查。结果艾滋病防治知识平均知晓率为60.75%。讨论调查对象对艾滋病知识及检测有很大的需求,对艾滋病防治知识和无偿献血基本知识相当缺乏,有待于继续加强宣传教育工作。     

等离子接枝处理的CF/PAA复合材料层间剪切强度及其形貌研究

采用等离子技术对碳纤维(CF)进行接枝芳基乙炔(PAA)处理，研究了影响CF／PAA复合材料层间剪切强度(ILSS)的因素。结果表明，经等离子接枝PAA处理后，复合材料的ILSS有了很大提高。SEM显示经接枝处理后CF和PAA树脂之间的界面结合紧密，改善了复合材料的界面结合性能。