Improvement of characteristics and freeze-thaw durability of solidified loess based on microbially induced carbonate precipitation

Bulletin of Engineering Geology and the Environment - Bio-cementation is currently applied to solidify sandy soils, but only few studies use it to cement loess soil particles. In this study, the...     

铜及铜合金中铜量分析方法综述

现行标准ＧＢ５２３１－ＧＢ５２３５－８５中共有８８个合金牌号要求测定铜量，其含铜量从５３％到９９．９７％以上。本文就ＩＳＯ、ＧＢ和主要铜材生产企业分析规程中铜量测定方法，结合本人的实践经验进行综述。     

无机调整剂碳酸钠和水玻璃对磷灰石分选特性的影响研究

本文探讨了无机调整剂碳酸钠、水玻璃及其交互作用对磷灰石分选特性的影响规律。结果表明，碳酸钠在低用量时，随着用量的增大，精矿品位降低、回收率提高；当用量超过3kg／t时，精矿品位提高而回收率降低。随着水玻璃用量的增大，精矿品位提高、回收率降低。在一定范围内同时增大碳酸钠和水玻璃的用量，精矿品位和回收率均有所提高。     

粒度分布特征参数的研究

本文提出了“粒度分布特征参数”的概念,认为物料的粒度特性可以用粒度分布特征参数来精确描述;给出了粒度分布特征参数的确定方法,并且建立了相应的数学模型。     

纳米凹凸棒土改性聚氨酯纤维的热性能研究

用不同含量的纳米凹凸棒土(AT)改性聚氨酯(PU)纤维,研究了改性PU纤维热分解动力学,测定了分解活化能,讨论了AT对改性PU纤维热性能的影响。结果表明:AT的加入,提高了PU纤维的起始分解温度,改善了纤维的热稳定性;加入质量分数为1.5%的AT,改性PU纤维的起始分解温度相比纯PU纤维提高了近14℃,增强了PU硬段的热分解稳定性。     

机械振动 WSN 比例补偿跨层同步采集触发方法

针对机械振动无线传感网络同步采集中的同步触发精度低问题,提出了一种比例补偿跨层同步采集触发方法。首先,基于跨层同步架构设计超宽带机械振动无线传感器网络节点,分析采集节点实际采集时钟构成;然后,使用单一硬件定时器作为采集控制时钟,跨层获取同步信息并进行同步触发延时控制;最后,根据周期性同步信息建立节点间的时间比例模型,根据采集节点上行链路时间比例对同步触发延时进行比例补偿,减小同步采集触发误差。实验结果表明,所提方法在单跳网络中同步采集触发误差均值为20 ns,最大值为50 ns,在两跳网络中同步采集触发误差均值为37 ns,最大值为76 ns,有效提高了机械振动无线传感器网络同步采集触发精度。     

不同前体物质的添加对高山被孢霉生长及脂肪酸组分的影响

通过添加植物油及吐温作为高山被孢霉合成油脂的前体物质,分别考察了不同前体物质的添加对菌体的生物量、油脂含量、油脂产量及所得油脂中各脂肪酸组分的影响。实验结果显示:添加植物油作为前体不但可以提高菌体中油脂含量,而且会使油脂中花生四烯酸的产量得到大幅度提高,其中加入菜籽油、亚麻籽油及大豆油为前体时,花生四烯酸的产量分别达到了2 063.2、2 062.8 mg/L及2 192.9 mg/L,比对照组提高了112.72%、112.68%及126.10%;而以吐温80为前体时,虽然菌体的油脂产量有所降低,但油脂中花生四烯酸的产量比对照组提高了79.91%,达到了1 744.9 mg/L。     

制冷系统壳管式换热器的常见故障和排除方法

介绍了制冷换热器的常见故障及排除方法     

Two‐Photon Up‐Conversion Photoluminescence Realized through Spatially Extended Gap States in Quasi‐2D Perovskite Films

A new approach to generate a two‐photon up‐conversion photoluminescence (PL) by directly exciting the gap states with continuous‐wave (CW) infrared photoexcitation in solution‐processing quasi‐2D perovskite films [(PEA)₂(MA)₄Pb₅Br₁₆ with n = 5] is reported. Specifically, a visible PL peaked at 520 nm is observed with the quadratic power dependence by exciting the gap states with CW 980 nm laser excitation, indicating a two‐photon up‐conversion PL occurring in quasi‐2D perovskite films. Decreasing the gap states by reducing the n value leads to a dramatic decrease in the two‐photon up‐conversion PL signal. This confirms that the gap states are indeed responsible for generating the two‐photon up‐conversion PL in quasi‐2D perovskites. Furthermore, mechanical scratching indicates that the different‐n‐value nanoplates are essentially uniformly formed in the quasi‐2D perovskite films toward generating multi‐photon up‐conversion light emission. More importantly, the two‐photon up‐conversion PL is found to be sensitive to an external magnetic field, indicating that the gap states are essentially formed as spatially extended states ready for multi‐photon excitation. Polarization‐dependent up‐conversion PL studies reveal that the gap states experience the orbit–orbit interaction through Coulomb polarization to form spatially extended states toward developing multi‐photon up‐conversion light emission in quasi‐2D perovskites.