A Degeneration Gradient of Poplar Trees Contributes to the Taxonomic,Functional, and Resistome Diversity of Bacterial Communities in Rhizosphere Soils

Bacterial communities associated with roots influence the health and nutrition of the host plant. However, the microbiome discrepancy are not well understood under different healthy conditions. Here, we tested the hypothesis that rhizosphere soil microbial diversity and function varies along a degeneration gradient of poplar, with a focus on plant growth promoting bacteria (PGPB) and antibiotic resistance genes. Comprehensive metagenomic analysis including taxonomic investigation, functional detection, and ARG (antibiotics resistance genes) annotation revealed that available potassium (AK) was correlated with microbial diversity and function. We proposed several microbes, Bradyrhizobium, Sphingomonas, Mesorhizobium, Nocardioides, Variovorax, Gemmatimonadetes, Rhizobacter, Pedosphaera, Candidatus Solibacter, Acidobacterium, and Phenylobacterium, as candidates to reflect the soil fertility and the plant health. The highest abundance of multidrug resistance genes and the four mainly microbial resistance mechanisms (antibiotic efflux, antibiotic target protection, antibiotic target alteration, and antibiotic target replacement) in healthy poplar rhizosphere, corroborated the relationship between soil fertility and microbial activity. This result suggested that healthy rhizosphere soil harbored microbes with a higher capacity and had more complex microbial interaction network to promote plant growing and reduce intracellular levels of antibiotics. Our findings suggested a correlation between the plant degeneration gradient and bacterial communities, and provided insight into the role of high-turnover microbial communities as well as potential PGPB as real-time indicators of forestry soil quality, and demonstrated the inner interaction contributed by the bacterial communities.     

稳流仓进料调节装置和出料稳流装置的设计与应用

稳流仓广泛应用于水泥生产行业,仓内布料情况直接关系到辊压机运行的稳定性,直接影响系统的台时产量、工序电耗等经济指标。为了使稳流仓内物料均匀分布,生产现场通常采用打散板、打散格等方式,但由于仓位变化、结皮等因素导致物料离析,最终影响辊压机运行。     

Predicting the dynamic behavior of asphalt concrete using three-dimensional discrete element method

A user-defined three-dimensional(3D)discrete element model was presented to predict the dynamic modulus and phase angle of asphalt concrete(AC).The 3D discrete element method(DEM)model of AC was constructed employing a user-defined computer program developed using the "Fish" language in PFC3D.Important microstructural features of AC were modeled,including aggregate gradation,air voids and mastic.The irregular shape of aggregate particle was modeled using a clump of spheres.The developed model was validated through comparing with experimental measurements and then used to simulate the cyclic uniaxial compression test,based on which the dynamic modulus and phase angle were calculated from the output stress-strain relationship.The effects of air void content,aggregate stiffness and volumetric fraction on AC modulus were further investigated.The experimental results show that the 3D DEM model is able to accurately predict both dynamic modulus and phase angle of AC across a range of temperature and loading frequencies.The user-defined 3D model also demonstrated significant improvement over the general existing two-dimensional models.     

锈蚀钢筋混凝土梁的力学性能研究

对24根直径不同的钢筋和8根钢筋混凝土梁进行电化学加速腐蚀模拟后,研究了24根受损钢筋的伸长率、屈服强度和极限强度的变化规律,以及8根不同腐蚀程度钢筋混凝土梁的应力-应变、荷载-挠度曲线和强度的变化规律.结果表明:伸长率的降低是导致锈蚀梁失去安全性能的主要因素;梁的极限承载能力和延性首先呈上升趋势,然后成反比例下降,最后出现陡降,形成不统一的单体,最终发生脆性破坏.     

D152树脂对镝的吸附及机制

对D152树脂吸附镝(Ⅲ)的过程及镝在D152树脂上的吸附行为进行了研究。研究了介质pH、温度、吸附时间、树脂量等因素对吸附过程的影响。实验结果表明:D152树脂对镝(Ⅲ)的吸附在pH=5.93的HAc-NaAc的缓冲溶液中为最佳。25℃时静态饱和吸附量为314.6mg.g-1(干树脂)。用1.0 mol.L-1的HCl溶液作为解吸剂,解吸率为96.2%;D152树脂对镝(Ⅲ)的表观吸附活化能Ea=18.28 kJ.mol-1,表观吸附速率常数k298=2.54×10-5s-1,k308=2.93×10-5s-1,k318=4.05×10-5s-1,测得热力学参数分别为ΔH=18.19 kJ.mol-1,ΔG=-0.88 kJ.mol-1,ΔS=63.99 J.mol-1.K-1,等温吸附服从Freundlich经验式。并用化学和红外光谱的方法探求树脂对镝(Ⅲ)的吸附机制。     

一种卫星双向时频传递设备时延差的标定方法

利用卫星双向时间频率传递方法可以实现精度优于1 ns的远程时间同步。卫星双向设备时延差是影响双向比对结果的一项主要误差。目前,国际上通用的方法是利用一套可移动的双向校准设备实现对两套卫星双向设备时延差的校准。该方法存在设备成本高、占用通信卫星资源且对天气条件要求较高等问题。随着i GMAS站和其他监测站点的建设,越来越多站点的接收机监测数据资源可用。提出一种利用各站点监测数据实现对卫星双向设备时延差的校准方法。当卫星双向比对两地同时具有监测数据可用时,可以通过事后数据处理的方式校准两地卫星双向设备的时延差。校准的主要思路是利用精密星历、钟差和电离层产品,从每颗星的伪距测量值中扣除传播路径中的各项延迟,得到本地与导航系统时间的时差。通过对所有可见星的时差结果进行加权、滤波,并扣除接收机间的相对时延,得到比对两地的全视站间钟差。最后,通过与同时段的卫星双向结果进行比较,得到两地卫星双向设备的时延差,校准精度优于1 ns。虽然该方法无法实现亚纳秒量级的校准,但是可以较为简单地标定出两地卫星双向设备的时延差,可以满足纳秒级的时间同步应用需求。     

新型斜拉链密封的应用

在水泥生产过程中,熟料输送机输送的是高温熟料,熟料输送机使用的输送带侧挡皮耐高温性差,在出现红料时容易燃烧,一方面会造成消防安全事故,另一方面侧挡皮燃烧后失去挡皮原有作用,斜拉链地坑冒灰造成环境污染,在设备工作过程中,如果在下料口处重新安装挡皮,会存在危险,所以只有等到设备停机时才能补充更换挡皮,在等待时,输送机缺失挡皮处持续漏料,不但造成熟料的损失,而且侧挡漏料处需要工作人员每班进行清理,劳动强度加大。因此有必要改进斜拉链机密封结构。     

渝东南地区阳春沟构造带五峰组—龙马溪组页岩构造裂缝特征及形成期次解析

渝东南地区阳春沟构造带是页岩气勘探有利区,构造裂缝发育特征和期次研究有助于评价该地区页岩气储层物性和保存条件。以渝东南地区阳春沟构造带五峰组—龙马溪组页岩构造裂缝为研究对象,通过岩心观察、成像测井解释、包裹体测温、磷灰石裂变径迹测年和区域构造运动演化等手段,对页岩构造裂缝发育的特征及形成期次进行研究,进而分析构造裂缝形成与页岩气成藏过程的匹配关系。研究结果表明,阳春沟地区五峰组—龙马溪组页岩中的构造裂缝非常发育,被方解石充填,多处呈现不同期次裂缝交错切割形成复杂缝网,并可见揉皱、微断层等现象。这些裂缝形成于3期构造运动：第一期为北北西向、北西西向和北东向裂缝,以方解石和黄铁矿全充填为主,形成于燕山运动中期,磷灰石裂变径迹测年为82~95 Ma,包裹体测温为190~210 ℃;第二期为北北东向、北东东向平面剪切缝和北西向剖面剪切缝,以方解石充填—半充填为主,形成于燕山运动晚期,磷灰石裂变径迹测年为68~78 Ma,包裹体测温为165~185 ℃;第三期为北北东向、北东东向平面剪切缝和北西向剖面剪切缝,并对前期裂缝进行改造,裂缝以方解石充填为主,形成于燕山末期—喜马拉雅期,磷灰石裂变径迹测年为30~62 Ma,包裹体测温为135~155 ℃。第一期构造裂缝形成于页岩最大埋深—开始抬升期,有利于改善页岩储层物性。第二期和第三期构造裂缝形成于页岩气藏调整期,该期的抬升运动会增加页岩气的逸散量,破坏页岩气的保存条件。抬升时期开始的越早,页岩气藏经历的调整破坏时期越长,单井含气量和测试产量就越低。     

Heterostructured TiO2 Nanorod@Nanobowl Arrays for Efficient Photoelectrochemical Water Splitting

Heterostructured TiO₂ nanorod@nanobowl (NR@NB) arrays consisting of rutile TiO₂ nanorods grown on the inner surface of arrayed anatase TiO₂ nanobowls are designed and fabricated as a new type of photoanodes for photoelectrochemical (PEC) water splitting. The unique heterostructures with a hierarchical architecture are readily fabricated by interfacial nanosphere lithography followed by hydrothermal growth. Owing to the two‐dimensionally arrayed structure of anatase nanobowls and the nearly radial alignment of rutile nanorods, the TiO₂ NR@NB arrays provide multiple scattering centers and hence exhibit an enhanced light harvesting ability. Meanwhile, the large surface area of the NR@NB arrays enhances the contact with the electrolyte while the nanorods offer direct pathways for fast electron transfer. Moreover, the rutile/anatase phase junction in the NR@NB heterostructure improves charge separation because of the facilitated electron transfer. Accordingly, the PEC measurements of the TiO₂ NR@NB arrays on the fluoride‐doped tin oxide (FTO) substrate show significantly enhanced photocatalytic properties for water splitting. Under AM1.5G solar light irradiation, the unmodified TiO₂ NR@NB array photoelectrode yields a photocurrent density of 1.24 mA cm^–2 at 1.23 V with respect to the reversible hydrogen electrode, which is almost two times higher than that of the TiO₂ nanorods grown directly on the FTO substrate.     

Thermodynamic Evaluation of the Co-Al-C System by Coupling Ab Initio Calculations and CALPHAD Approach

The ternary Co-Al-C system was thermodynamically assessed using the CALPHAD method based on the critical review of all experimental information in the system. The κ-carbide was described with a three-sublattice model (Al,Co)₃(Al,Co)₁(C,Va)₁. To support the assessment, the enthalpies of formation of all end-members of the κ-carbide were studied by ab initio calculations. The solubility ranges of the carbon in the κ-carbide, the αCo and the AlCo (B2) phases were well reproduced. The equilibria involving the liquid phase were reasonably described using the present set of thermodynamic parameters.