Genetic Susceptibility to Periodontal Disease in Down Syndrome: A Case-Control Study

Severe periodontitis is prevalent in Down syndrome (DS). This study aimed to identify genetic variations associated with periodontitis in individuals with DS. The study group was distributed into DS patients with periodontitis (n = 50) and DS patients with healthy periodontium (n = 36). All samples were genotyped with the “Axiom Spanish Biobank” array, which contains 757,836 markers. An association analysis at the individual marker level using logistic regression, as well as at the gene level applying the sequence kernel association test (SKAT) was performed. The most significant genes were included in a pathway analysis using the free DAVID software. C12orf74 (rs4315121, p = 9.85 × 10⁻⁵, OR = 8.84), LOC101930064 (rs4814890, p = 9.61 × 10⁻⁵, OR = 0.13), KBTBD12 (rs1549874, p = 8.27 × 10⁻⁵, OR = 0.08), PIWIL1 (rs11060842, p = 7.82 × 10⁻⁵, OR = 9.05) and C16orf82 (rs62030877, p = 8.92 × 10⁻⁵, OR = 0.14) showed a higher probability in the individual analysis. The analysis at the gene level highlighted PIWIL, MIR9-2, LHCGR, TPR and BCR. At the signaling pathway level, PI3K-Akt, long-term depression and FoxO achieved nominal significance (p = 1.3 × 10⁻², p = 5.1 × 10⁻³, p = 1.2 × 10⁻², respectively). In summary, various metabolic pathways are involved in the pathogenesis of periodontitis in DS, including PI3K-Akt, which regulates cell proliferation and inflammatory response.     

苏通大桥钢箱梁仰角焊缝焊接工艺及疲劳性能研究

通过苏通大桥钢箱梁仰角焊缝的焊接工艺及疲劳性能研究,确定了一种钢箱梁仰角焊缝的焊接工艺方法,可为公路斜拉桥类似结构的焊接提供参考。     

从欧美日标准看我国不锈钢钢管制造业的现状及发展前景(上)

介绍了欧、美、日不锈钢钢管标准的特点。详细对比欧、美、日不锈钢钢管新标准中钢种类别、制造方法、供货状态、规格范围等有关内容。指出我国不锈钢钢管制造业应在不断扩大产量的同时,加大新钢种研发力度,完善产品规格范围,开发不锈钢钢管制造新工艺,注重产品外观质量,增加我国不锈钢钢管行业的国际竞争力。     

A (G-to-A) mutation in the initiation codon of the proteolipid protein gene causing a relatively mild form of Pelizaeus-Merzbacher disease in a Dutch family

Pelizaeus-Merzbacher disease (PMD) is an X-linked recessive disorder that is characterized by dysmyelination of the central nervous system resulting from mutations in the proteolipid protein (PLP) gene. Mutations causing either overexpression or expression of a truncated form of PLP result in oligodendrocyte cell death because of accumulation of PLP in the endoplasmic reticulum. It has therefore been hypothesized that absence of the protein should result in a less severe phenotype. However, until now, only one patient has been described with a complete deletion of the PLP gene. We report a Dutch family with a relatively mild form of PMD, in which the disease cosegregates with a (G-to-A) mutation in the initiation codon of the PLP gene. This mutation should cause the total absence of PLP and is therefore in agreement with the hypothesis that absence of PLP leads to a mild form of PMD.     

A mitochondrial tRNA(Val) gene mutation (G1642A) in a patient with mitochondrial myopathy, lactic acidosis, and stroke-like episodes

We studied a patient with the diagnosis of mitochondrial encephalomyopathy, lactic acidosis, and stroke-like episodes (MELAS) for mitochondrial DNA mutations in muscle. Established MELAS mutations were excluded. Mitochondrial DNA was further analyzed for mutations in the 22 tRNA genes by single-strand conformation polymorphism (SSCP) analysis; a tRNA(Val) mutation (G1642A) was found. The structure of the altered tRNA, the heteroplasmy, and the absence of the mutation in the mother and in 100 control subjects suggests that the tRNA(Val) mutation is associated with the MELAS syndrome.     

硫磺制酸系统余热锅炉二级过热器管失效原因分析

采用金相、EMPA、X—射线衍射和化学分析等方法对南京磷肥厂使用十个月后未经保护的12CrMoV和使用一年后经喷铝保护的12CrMov及18-8不锈钢管取样进行了分析。结果表明,二级过热器管的失效起因于管子表面的高温氧化和硫化腐蚀。 未经保护的12CrMoV管腐蚀严重,其腐蚀产物是非保护性氧化皮和铁的硫化物,而经喷铝保护的12Cr_1MoV管和18-8不锈钢管在该腐蚀条件下,由于生成能阻止O_2和S侵入金属的Al_2O_3和Cr_2O_3保护膜而表现出良好的抗腐蚀性能。 根据上述结果,提出了可能的腐蚀机制及其解决途径。     

基于案例模糊推理的土木工程造价估算方法研究

项目策划和可行性研究阶段是土木工程造价控制的重要阶段,然而传统的造价估算方法难以满足估算精度和科技进步需要。本文运用模糊数学的有关理论,介绍了一个基于案例推理(CBR)的土木工程造价估算系统的主要结构和数学模型,并结合实际案例介绍了系统应用情况。一方面,由于该系统以土木工程工料消耗为基础,故可以减小时间、历史状况等因素对价格估算的影响,也有利于应用以工程量清单为基础的国际惯例。另一方面,系统具有的对案例库的更新功能,可适应土木工程科技不断发展的要求,这些都会提高系统计算结果的准确程度和系统的实用价值。利用案例推理系统估算住宅建筑主要工料消耗的计算实例表明,基于案例推理系统是有效的,它可为土木工程造价估算决策提供了有价值的参考依据。     

胶粉/LLDPE弹性体合金的研制

系统研究了废胶粉（GRT）／线型低密度聚乙烯（LLDPE）弹性体合金（GRT／LLDPE）的配方，以及粒径，GRT含量，相容剂和硫化剂（DCP）用量对共混物力学性能的影响，结果表明，采用两阶共混法，当GRT／LLDPE共混比为：60：40，DCP用量为2份，相容剂马来酸酐三单体接枝物用量为3－5份时，所得弹性体合金力学性能最佳，弹性体合金的拉伸强度从简单共混物的5．8Mpa上升到11．1MPa，撕裂强度从39．4kN/m，上升到63．4kN/m，断裂伸长率从180％增加到260％。     

轻钢增层房屋阻尼比确定的能量法

阻尼比是反映结构耗能能力的参数,对结构的振动反应有着重要影响。目前结构设计阶段通常取阻尼比为常数,这不能真实反映建筑物的阻尼机理,与阻尼比的实测结果也有很大的差距。本文基于复阻尼理论,采用能量法推导了增层房屋任意振型阻尼比的计算公式,提出了地震反应谱的修正方法,并利用Matlab工具语言编制程序对此方法进行实现。最后,通过对一个数值算例结果的分析,验证了本文方法的可行性和实用性。     

某工程玻璃采光顶结构分析

在讨论各种玻璃采光顶支承结构的基础上,首先对由桁架和系杆组成的玻璃采光顶支承结构在各种荷载工况下的结构进行分析,具体分析结构的内力、挠度以及材料的使用效率,并讨论此类结构构件截面的选用;其次,考虑玻璃与支承结构的共同工作,对结构进行整体的分析和比较;最后利用规范公式以及考虑几何非线性的有限元分析两种方法,对带孔采光顶玻璃进行应力和挠度计算,并分析孔边距对于玻璃应力分布的影响,可为结构设计提供依据。