Novel transparent and flexible nanocomposite film prepared from chrysotile nanofibres

In the present study, chrysotile nanofibres, obtained from physicochemical dispersion of natural chrysotile, were used to prepare nanofibre sheets by vacuum filtration. As-prepared sheets were then impregnated by UV-curable resin and cured by ultraviolet light to fabricate the flexible and transparent nanocomposite films. Observed from SEM, the transparent films showed a smooth surface and a typical sandwich structure in cross section, viz. nanofibre sheet filled with resin was sandwiched by two layers of resin. XRD patterns indicated the amorphous nature of cured resin and characteristic crystallographic structure of chrysotile in nanocomposite films. Though the nanofibre sheets were white in colour, and nanofibre contents in nanocomposites were as much as 43.4 wt%, the nanocomposite films displayed an excellent optical transparency with about 85% light transmittance in the visible light range. Tensile tests showed that the addition of nanofibres resulted in a great improvement in mechanical strength of the nanocomposite films; with the increase of nanofibre contents, the modulus and tensile strength of nanocomposite films increased gradually.     

20G低碳钢的高温环烷酸腐蚀行为

使用高温高流速环烷酸腐蚀模拟装置对20G低碳钢在不同温度和冲刷角下的环烷酸腐蚀行为进行了研究,结果表明:温度和冲刷角对20G低碳钢的环烷酸腐蚀行为有显著影响;冲刷角对腐蚀速率的影响与温度及流速有关,腐蚀速率在280～320℃达到峰值,超过320℃腐蚀速率随温度升高呈下降趋势。20G钢的腐蚀形貌分析表明:在环烷酸腐蚀时20G钢中的珠光体优先发生溶解,在珠光体腐蚀后再由晶界向晶内腐蚀铁素体。     

数字电视NIT表的研究及在DVB-C中的应用

通过对网络信息表(NIT)段、描述子的语法进行研究,分析了其主要功能,并结合工程实践,叙述了NIT在有线数字电视的应用.     

栀子食用人群栀子苷暴露评估

目的 了解我国居民栀子食用情况,评估我国栀子食用人群栀子苷暴露水平及健康风险。方法 通过文献检索和专项监测收集我国栀子中栀子苷含量数据,结合2019—2022年我国食药物质消费量调查数据,采用简单分布方法和概率评估方法获得我国不同人群通过食用栀子的栀子苷暴露水平及健康风险。结果 我国9省栀子食用率为10.32%,每日食用量均值为0.36 g,高消费人群每日栀子食用量为1.48 g。简单分布评估显示,9省栀子食用人群的栀子苷每日平均暴露量为0.29 mg/kg·BW,高消费人群（P95）栀子苷暴露量为1.28 mg/kg·BW,9省栀子食用人群中有17.20%的居民通过食用栀子的栀子苷暴露量超过其每日可耐受摄入量（TDI,0.386 mg/kg·BW）。河南省食用人群每日平均暴露量最高,为0.54 mg/kg·BW。概率评估结果显示,我国14.70%的栀子食用人群栀子苷暴露量超过TDI,具有潜在健康风险。结论 我国栀子食用人群的栀子苷暴露风险总体较低,但部分高消费人群（P95）存在健康风险。     

红茶发酵影响因素及品质调控技术研究进展

红茶是我国主要的消费茶类之一,其加工步骤为萎凋、揉捻、发酵和干燥,其中发酵是红茶品质特征形成的关键环节。关于红茶发酵过程中影响因素及品质调控技术,已有文献表明,多酚类物质含量及组成比例、酶种类及其活性、温度、湿度、pH,以及发酵过程中微生物等内部及环境因素均会影响红茶品质特征化合物的形成,从而影响其品质。目前常用的品质调控技术主要包括新发酵技术、冷冻萎凋技术、外源酶技术以及光质。未来研究重点将是优化红茶适制品种培育、环境因子间的交互作用机制、微生物对红茶发酵品质的影响机制和加工设备智能化等方面,因此本文通过对红茶发酵影响因素及品质调控技术的研究进展进行综述,以期为提升红茶的滋味品质和推进红茶新研究进展提供借鉴与参考。     

一种新型的无人机牧草分割网络—LMS-DeeplabV3+

目前草原环境复杂、牧草分散且与背景颜色差异小,无法实现高效精准的分割,因此本文提出了一种新型的轻量化多尺度DeeplabV3+网络(lightweight and multi-scale DeeplabV3+network, LMS-DeeplabV3+)。该网络以DeeplabV3+为基础网络,首先选用轻量级的MobilenetV2作为骨干网络用于初步特征提取,并为了适应牧草分割任务做了网络配置上的调整;其次在加强特征提取模块和解码模块中均使用深度可分离卷积代替普通卷积以轻量化网络;此外利用密集空洞空间金字塔池化(dense atrous spatial pyramid pooling, DASPP)模块捕获更大的感受野,加强各特征之间的交互;又引入卷积注意力机制(convolutional block attention module, CBAM)重分配权重加强特征提取。实验证明,提出的新网络与原始网络相比平均交并比(mean intersection over union,mIOU)提升了8.06个百分点、平均像素精度(mean pixel accuracy,mPA)提升了6.7...     

基于单片机的远程监测控制装置设计

基于广泛使用的PSTN网络,综合使用线路信号检测芯片判断线路状态、DTMF收发芯片接收发送DTMF信号进行命令交互,采用单片机集中控制,制作的远程监控装置,具有广泛的应用价值.     

SOM人工神经网络与阻抗谱方法结合研究涂层的失效过程

    分析了干湿循环条件下有机涂层的电化学阻抗谱特征后选取了阻抗变化率参数作为一维自组织特征映射(self-organizing feature map,SOM)神经网络的训练样本,每个样本对输出层神经元都会产生一定的激发水平,根据该神经网络的特性,输出神经元激发水平的变化趋势便可以反映涂层的降解过程.结合涂层阻抗谱的变化特征,可以把干湿循环条件下涂层的失效过程分为三个阶段,即介质渗入涂层过程,介质到达金属表面诱发金属腐蚀过程和腐蚀扩展涂层剥离过程.     

ATR Contributes More Than ATM in Intra-S-Phase Checkpoint Activation after IR,and DNA-PKcs Facilitates Recovery: Evidence for Modular Integration of ATM/ATR/DNA-PKcs Functions

The intra-S-phase checkpoint was among the first reported cell cycle checkpoints in mammalian cells. It transiently slows down the rate of DNA replication after DNA damage to facilitate repair and thus prevents genomic instability. The ionizing radiation (IR)-induced intra-S-phase checkpoint in mammalian cells is thought to be mainly dependent upon the kinase activity of ATM. Defects in the intra-S-phase checkpoint result in radio-resistant DNA synthesis (RDS), which promotes genomic instability. ATM belongs to the PI3K kinase family along with ATR and DNA-PKcs. ATR has been shown to be the key kinase for intra-S-phase checkpoint signaling in yeast and has also been implicated in this checkpoint in higher eukaryotes. Recently, contributions of DNA-PKcs to IR-induced G₂-checkpoint could also be established. Whether and how ATR and DNA-PKcs are involved in the IR-induced intra-S-phase checkpoint in mammalian cells is incompletely characterized. Here, we investigated the contributions of ATM, ATR, and DNA-PKcs to intra-S-phase checkpoint activation after exposure to IR of human and hamster cells. The results suggest that the activities of both ATM and ATR are essential for efficient intra-S-phase checkpoint activation. Indeed, in a wild-type genetic background, ATR inhibition generates stronger checkpoint defects than ATM inhibition. Similar to G2 checkpoint, DNA-PKcs contributes to the recovery from the intra-S-phase checkpoint. DNA-PKcs–deficient cells show persistent, mainly ATR-dependent intra-S-phase checkpoints. A correlation between the degree of DSB end resection and the strength of the intra-S-phase checkpoint is observed, which again compares well to the G2 checkpoint response. We conclude that the organization of the intra-S-phase checkpoint has a similar mechanistic organization to that of the G₂ checkpoint in cells irradiated in the G₂ phase.     

图像扫描波动性定量标准及分形扫描矩阵的快速生成

在图像扫描技术中，首要的问题是如何尽量减小生成数据的波动性。本文在深入研究各种扫描技术的基础上，定义了一种描述扫描产生数据波动性的度量指标，基于图像存在局部连续性，证明了Hilbert分形曲线扫描优于其他传统扫描，表明在生成数据的最佳连续特性，并通过实验 分析了图像扫描方式对DCT变换编码效果的影响。最后，给出了一个构造Hilbert扫描矩阵的快速算法。