Human DDX17 Unwinds Rift Valley Fever Virus Non-Coding RNAs

Rift Valley fever virus (RVFV) is a mosquito-transmitted virus from the Bunyaviridae family that causes high rates of mortality and morbidity in humans and ruminant animals. Previous studies indicated that DEAD-box helicase 17 (DDX17) restricts RVFV replication by recognizing two primary non-coding RNAs in the S-segment of the genome: the intergenic region (IGR) and 5′ non-coding region (NCR). However, we lack molecular insights into the direct binding of DDX17 with RVFV non-coding RNAs and information on the unwinding of both non-coding RNAs by DDX17. Therefore, we performed an extensive biophysical analysis of the DDX17 helicase domain (DDX17_135–555) and RVFV non-coding RNAs, IGR and 5’ NCR. The homogeneity studies using analytical ultracentrifugation indicated that DDX17_135–555, IGR, and 5’ NCR are pure. Next, we performed small-angle X-ray scattering (SAXS) experiments, which suggested that DDX17 and both RNAs are homogenous as well. SAXS analysis also demonstrated that DDX17 is globular to an extent, whereas the RNAs adopt an extended conformation in solution. Subsequently, microscale thermophoresis (MST) experiments were performed to investigate the direct binding of DDX17 to the non-coding RNAs. The MST experiments demonstrated that DDX17 binds with the IGR and 5’ NCR with a dissociation constant of 5.77 ± 0.15 µM and 9.85 ± 0.11 µM, respectively. As DDX17_135–555 is an RNA helicase, we next determined if it could unwind IGR and NCR. We developed a helicase assay using MST and fluorescently-labeled oligos, which suggested DDX17_135–555 can unwind both RNAs. Overall, our study provides direct evidence of DDX17_135–555 interacting with and unwinding RVFV non-coding regions.     

响应面法优化超压肠杆菌利用黄水生产微生物絮凝剂

以黄水为培养基，利用单因素及响应面试验研究黄水的稀释度、外加碳氮源、无机盐、接种量、pH值等因素对超压肠杆菌（Enterobacter nimipressuralis）产微生物絮凝剂的影响。结果表明，最佳黄水培养基组成为：初始pH值7.0，接种量6%，黄水体积分数17%，葡萄糖添加量7.5 g/L、尿素添加量1.5 g/L、KCl添加量3.0 g/L。在此优化条件下，絮凝剂的絮凝率可达到84.35%。     

四川干热河谷地区公路生态植被恢复与重建模式探讨

分析了四川干热河谷地区公路周边自然植被条件与海拔高度的关系,以国道318线二郎山至康定公路为例,对干热河谷地区公路生态恢复与重建的模式进行了研究,根据道路所处海拔高度的差异把全路段分为二郎山、泸定大渡河、康定瓦斯沟三段,根据各段气候和植被特点确定恢复模式,经过2年的生长观察,证明各恢复模式都取得很好的效果,乔灌木的平均成活率达到85%,草坪地被覆盖率平均达到93%;最后,总结了干热河谷道路生态恢复与重建的特殊技术。     

中国牛形古村落--安徽黟县宏村

安徽省黟县东北部的宏村，融自然景观和人文景观为一体，恰似山水长卷，被誉为“中国画里的乡村”。其将整个村子构建成“牛”型结构布局的理水艺术，更是被誉为当今世界历史文化遗产的一大奇迹。2000年11月30日被联合国教科文组织世界遗产委员会列入世界文化遗产名录。     

Hand gesture recognition using valley circle feature and Hu’s moments technique for robot movement control

Hand gesture recognition is a simpler and more natural way of human computer interaction. The goal of this paper is to detect the continuous gestures and use them to convey information for the robot movement control. So the hand gesture recognition requires fast and extremely robust. In this paper, three strategies were used to realize the hand gesture recognition: (1) the valley circle (VC) was created for the first stage of 6 fingertip numbers classification; (2) the hybrid feature vector of Hu’s moments, convexity and compactness (HCC) were constructed for the second stage of gesture recognition of the remainder unknown gesture classes; (3) a new template matching recognition (NTMR) algorithm was proposed to realize 10 gesture classes recognition. To test the hand gesture recognition method, the robot movement control system was built. It is experimental proved that the NTMR algorithm is effective and corrective for the hand gesture recognition. It increased the recognition accuracy by 4% and decreased the recognition duration by 112 ms compared with Hu’s moment method. It had good performances of the real-time hand gesture acquisition and information conveyance, and it had the invariant properties when the gesture was rotated and shifted and scaled.     

山地河谷型村落的更新与活化 ——以浙江德清东沈村为例

江南地区山地纵横、水网密布， 地貌丰富多样，村落呈现出不同的类型及特 征，山地河谷村落数量众多。但现阶段乡建 同质化严重，不同类型村落的适宜性政策被 忽略。本文以浙江德清东沈村为例，分析山 地河谷村落特征，以地形地貌为出发点，从 山、水、村落三方面，提出基于山水特质的村 落更新与活化策略，促进乡村经济、社会、文 化的永续发展。     

世博轴单层异形钢结构网壳节点制作工艺的研究

世博轴共有6个大小不一的阳光谷,高度约为41.5m,最大底部直径约20m,最大顶部直径约90m,结构为由三角形网格组成的单层网架体系.阳光谷节点由多杆箱形构件直接交汇而成,其中部分采用实心铸钢节点,节点总数10348个,呈空间三维异形形态,几乎无一相同.着重介绍阳光谷钢结构异形复杂节点制作工艺技术的研究开发,可供今后同...     

引汉济渭工程秦岭隧洞围岩稳定性有限元分析

对引汉济渭工程秦岭引水隧洞开挖的初期支护施工过程围岩结构的塑性变形分布规律进行分析研究,结合计算结果,为初期支护过程围岩的稳定性提供分析依据,以便对现场施工提供合理化建议。采用非线性弹塑性有限元法,依据地下结构设计理论及岩石的Drucker-Prager屈服准则,考虑围岩和初期支护衬砌结构的整体性,对秦岭引水隧洞的Ⅲ、Ⅳ类围岩开挖和初期支护结构的施工过程进行了模拟,计算了开挖施工过程三种不同工况下围岩顶拱及侧向的塑性变形。结果表明:秦岭隧洞初期支护施工过程的三种工况下围岩结构的塑性变形主要集中在顶拱120°范围内及两侧边墙,隧洞围岩结构整体处于安全状态。     

三河口水利枢纽厂房边坡爆破大块率问题分析及其爆破参数优化

引汉济渭工程三河口水利枢纽厂房边坡爆破开挖施工中,出现了边坡预裂爆破半孔率不高、爆破后大块岩石较多以及根底或者马道超爆等问题,后续开挖运输过程中需要二次破碎,不但增加了施工成本,也影响施工进度、影响边坡外观效果。为了彻底解决上述问题,深入分析现场爆破作业操作流程,分析对比方案和实施过程中的问题,通过试验确定岩石强度等影响爆破效果的要素,根据实测数据进行爆破设计方案优化。结果表明:通过现场跟踪记录各工序,找出了现场存在的导致大块率过高的主要因素和原因,逐一分析解决,并通过逐次爆破后效果分析进行爆破设计优化。优化后的爆破方案基本解决了爆破后大块岩石较多的问题。这表明:结合生产开展爆破试验,能够获得安全、高效、经济的钻孔与爆破参数。     

河谷气候影响下的生态城市形态浅析 ——以重庆市奉节县整体城市设计为例

古往今来,气候特征对人类历史上 各种文明的产生和发展发挥着不同程度的作 用。虽然现代文明已经发展到可以抵御部分 气候带来的灾害,但是在目前所倡导的城市双 修、节能减排、绿色宜居,建设低碳生态城市 大背景下,通过城市的空间形态充分利用自然 气候带来的益处,减少不良气候带来的危害, 从而达到生态宜居,成为了城市建设的最终目 的。山地城市地形地貌复杂、生态环境敏感、 气候多变,在山地气候研究中又以河谷气候变 化最为复杂,河谷城市形态受气候及其它因素 影响与平原城市相比也有很大的不同。因此 本文选取具有典型河谷特征地形的奉节县为 例,研究通过城市形态利用较为复杂的局地 气候,最终达到建设生态城镇的目的。