Genipin cross-linked chitosan hydrogel for the controlled release of tetracycline with controlled release property,lower cytotoxicity,and long-term bioactivity

To realize the controlled release property, lower cytotoxicity, and long-term bioactivity of tetracycline, the chitosan hydrogel had been prepared using genipin as the cross-linker and the tetracycline was in situ encapsulated. The formation process and strength of hydrogel were studied by rheological analysis, and the microtopography was observed by scanning electron microscope. It was found that the amount of genipin could modulate the physical property of the hydrogel. For in vitro release and antibacterial assays, the hydrogel could controllably release tetracycline and keep its bioactivity for a long time. The tetracycline-loaded chitosan hydrogel showed good antibacterial effect even under alkaline environment, which displayed better stability compared with free tetracycline. Moreover, the tetracycline-loaded chitosan hydrogel exhibited lower cytotoxicity than did tetracycline alone, suggesting that this tetracycline-loaded chitosan hydrogel could be a more useful dosage form than separate doses of tetracycline. The novel aspects of this study include the cytotoxicity study and the in vitro and in vivo assays, which might be useful for other researchers in this field.

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Graphical abstract To realize the controlled release property, lower cytotoxicity, and long-term bioactivity of tetracycline, genipin cross-linked chitosan hydrogel was used as the carrier of tetracycline. The hydrogel could controllably release tetracycline with bioactivity. The hydrogel showed good antibacterial effect even under alkaline environment. The hydrogel exhibited lower cytotoxicity than did tetracycline alone.

     

熔盐电解法制备单一Sm2Fe17合金相的机理研究

选择在LiF-CaF₂-SmF₃熔盐体系中,采用熔盐电解法在1160℃下通过恒电流在Fe阴极表面获得了不同厚度(17.22～40.34μm)的Sm₂Fe₁₇合金层,同时通过循环伏安法与方波伏安法研究了Sm³⁺在W与Fe阴极上的电化学行为。结果表明,Sm³⁺无法单独沉积于W电极上,Sm³⁺在铁阴极上的还原为Sm⁰分为2步,首先在-0.33V(vs.Cr/Cr₂O₃)发生Sm³⁺还原为Sm²⁺的可溶-可溶型反应,然后当电极电势超过-0.78V(vs.Cr/Cr₂O₃)时Sm²⁺开始在阴极界面处上发生欠电势还原,在Fe电极表面生成Sm₂Fe₁₇合金,这是由于在Sm₂Fe₁₇合金中降...     

A graph deep learning method for short‐term traffic forecasting on large road networks

Short‐term traffic flow prediction on a large‐scale road network is challenging due to the complex spatial–temporal dependencies, the directed network topology, and the high computational cost. To address the challenges, this article develops a graph deep learning framework to predict large‐scale network traffic flow with high accuracy and efficiency. Specifically, we model the dynamics of the traffic flow on a road network as an irreducible and aperiodic Markov chain on a directed graph. Based on the representation, a novel spatial–temporal graph inception residual network (STGI‐ResNet) is developed for network‐based traffic prediction. This model integrates multiple spatial–temporal graph convolution (STGC) operators, residual learning, and the inception structure. The proposed STGC operators can adaptively extract spatial–temporal features from multiple traffic periodicities while preserving the topology information of the road network. The proposed STGI‐ResNet inherits the advantages of residual learning and inception structure to improve prediction accuracy, accelerate the model training process, and reduce difficult parameter tuning efforts. The computational complexity is linearly related to the number of road links, which enables citywide short‐term traffic prediction. Experiments using a car‐hailing traffic data set at 10‐, 30‐, and 60‐min intervals for a large road network in a Chinese city shows that the proposed model outperformed various state‐of‐the‐art baselines for short‐term network traffic flow prediction.     

Seismic performance of corrugated steel plate concrete composite shear walls

In this paper, composite shear walls with different encased steel plates (flat, horizontal corrugated, and vertical corrugated) were tested and simulated by Abaqus to investigate the seismic behavior of corrugated steel plate concrete composite shear walls (SPCSWs). The failure characteristics, deformation and energy dissipation capacity, and stiffness and bearing capacity of the structures under low‐frequency cyclic load were analyzed, and indexes of the seismic performance were obtained. The formulas of the shear‐bearing capacity of steel plate concrete composite shear walls are suggested, and the shear‐sharing ratio of each member is obtained. According to the obtained results, corrugated steel plates can bond with concrete well, and the bearing capacity of the vertical corrugated SPCSW are higher than that of the horizontal corrugated SPCSW. Compared with flat SPCSW, corrugated SPCSW has higher initial stiffness and lateral stiffness, better ductility and energy dissipation ability, and the degradation of bearing capacity and stiffness is slower. The shear‐sharing ratio of a steel plate is larger than that of reinforced concrete in the flat SPCSW and the vertical corrugated SPCSW, the shear force shared by steel plate and reinforced concrete in horizontal corrugated SPCSW is basically the same.     

电力电缆隧道结构病害及检测评估方法探讨

电力电缆隧道是目前常见的城市地下空间利用形态之一,但是该类隧道的结构病害检测技术体系和规范尚不完善,影响了该类隧道的病害评定及相应处治。电力电缆隧道的病害类型主要包括隧道渗漏水、隧道衬砌裂损、衬砌结构腐蚀这三大类型,其中影响较大的为隧道渗漏水。在电力电缆隧道的检测工作中,需要结合电力隧道的工作环境条件、功能特点,明确检测的目的和需求,有针对性地调查和收集相关的信息和资料以制定检测方案。检测的内容可以划分为外观检查、结构安全性检查、结构耐久性检查这三大类内容,以便选取适宜的仪器和方法开展电力隧道检测工作。论文提出了确定电力隧道结构区段的分项评定标准及综合技术状况评定方法,并建议依据检测评定结果对电力隧道采取对应的养护措施。     

微量Y(0.2 wt.%)对铸造Mg-Sn合金热变形行为影响

采用MTS-CMT5105电子万能试验机,在温度为250~400℃、初始应变速率为10_-4~10_-1s_-1,最大变形量为40%的条件下,对铸态Mg-2.5Sn(wt.%)和Mg-2.5Sn-0.2Y(wt.%)合金进行压缩变形。结合真应力-应变曲线、峰值应力、显微组织、本构方程、DMM加工图,研究了微量Y(0.2 wt.%)对铸造Mg-Sn合金热变形行为的影响。结果表明：微量Y的添加,在较低应变速率时,会使Mg-Sn合金热压缩峰值应力增加30%以上;但在较高应变速率时,却对其影响不大。会改变合金塑性变形机制的控制方式,即由扩散控制变为位错的滑移和攀移。会抑制动态再结晶。会降低功率耗散系数,扩大加工失稳区。     

应变路径变化对纯镍组织和织构的影响

采用背散射电子衍射（EBSD）和X射线衍射（XRD）技术对比分析了两种应变方式（单向轧制和交叉轧制）对大变形量（厚度方向压下量90%）纯镍形变组织和织构以及随后热处理过程中组织和织构演变的影响。结果表明：单向与交叉轧制纯镍的形变微观组织均以层片状组织为主,但前者储存能高于后者;单向轧制纯镍的宏观织构是典型的铜型冷轧织构,而交叉轧制纯镍的主要织构组分是黄铜和旋转型黄铜织构,且前者的织构强度明显高于后者。对两种方式形变样品在不同温度下进行退火处理,发现单向轧制样品中形成了以立方织构为主的再结晶织构,且随着退火温度的升高,立方织构的强度逐渐增强;而交叉轧制样品则形成了弱的再结晶纤维织构,其强度远小于单向轧制样品的再结晶织构强度。另外,单向轧制样品在高温800°C保温处理后,出现了少量异常长大晶粒,这是由于取向相近的立方取向晶粒聚集形成团簇,使得微观取向分布不均匀造成的;而交叉轧制方式可以抑制热处理过程中的晶粒异常长大。     

稀土CeCl3对耐热钢Ni2Al3/Ni复合涂层抗氧化性的影响

本文采用电镀镍、低温包埋渗铝在P92铁素体耐热钢表面制备不同稀土Ce含量的Ni-Al化合物复合涂层,并对复合涂层进行650 ℃×132 h的抗氧化实验。利用OM、SEM、EDS、XRD,分析涂层氧化前后的截面微观形貌,化学元素分布及物相变化规律。结果表明：涂层的氧化动力学曲线均符合抛物线规律。不含Ce的复合涂层平均氧化速率为0.4412×10-6 g/cm2/s,渗铝剂中加入2%CeCl3的涂层抗氧化性明显增强,平均氧化速率为0.2957×10-6 g/cm2/s,而加入过量CeCl3（4%、6%）则会在氧化过程中产生更多的孔洞,恶化了涂层的高温抗氧化性能,氧化速率相对加入2 % CeCl3的涂层有所升高。另外涂层中加入Ce元素增加了氧化膜的粘附性,对Al元素的向内扩散具有抑制作用。     

基于聚苯胺的光固化防腐蚀涂层

利用十二烷基苯磺酸 (DBSA) 对本征态的聚苯胺 (PANI) 进行掺杂,将不同含量的掺杂后的聚苯胺分别加入到光固化树脂聚氨酯丙烯酸酯 (6071) 中,制备了一种低VOC排放的光固化聚苯胺防腐蚀涂层。通过实时红外以及漆膜性能的测试选择了合适的光引发剂,通过电化学阻抗谱、盐雾实验以及极化曲线对涂层的防腐蚀性能进行了测试。结果表明,加入0.4%DBSA-PANI的光固化涂层具有最佳的防腐蚀性能。     

基于三轴实验的软破岩石破坏准则的研究

随着开采深度的进一步增加，软破岩工程变得越来越突出。本文在分析软破岩石特点的基础上，提出了依据软破岩石三轴试验，而建立其破坏准则，为对软破岩的进一步深入研究提供了条件，同时为岩石强度的研究开辟了一条实用途径。