Additive Manufacturing of Polymer-Based Lubrication

The fast growth of 3D printing technology gives designers many ways to make structures that are hard to see. 3D printing lets you customize complex structures in any way you want and make rapid prototypes of materials. It enables you to simulate things more effectively. So far, experiments with polymer-based lubrication have been done on atomically smooth surfaces, under dynamic conditions, and on the nano- or micro-scale. Polymer-based lubrication in 3D printing has been studied in depth, which has made it possible to make significant, multifunctional 3D structures with microscale accuracy. It is a crucial way to approach lubrication and has sparked much scientific interest. A thorough literature review is done to keep track of the latest advances in 3D printing for structural polymer-based lubrication simulation. The design and lubrication performance quality of bio-inspired, different-sized simulation structures is given much attention. The material requirements, skills, and representative applications of various 3D printing technologies are summarized. The efficient directions for future research in designing and making 3D-printed lubrication structures are also pointed out.     

Strong and Ultra-Tough Supramolecular Hydrogel Enabled by Strain-Induced Microphase Separation

Architected hydrogels are widely used in biomedicine, soft robots, and flexible electronics while still possess big challenges in strong toughness, and shape modeling. Here, inspired with the universal hydrogen bonding interactions in biological systems, a strain-induced microphase separation path toward achieving the printable, tough supramolecular polymer hydrogels by hydrogen bond engineering is developed. Specifically, it subtly designs and fabricates the poly (N-acryloylsemicarbazide-co-acrylic acid) hydrogels with high hydrogen bond energy by phase conversion induced hydrogen bond reconstruction. The resultant hydrogels exhibited the unique strain-induced microphase separation behavior, resulting in the excellent strong toughness with, for example, an ultimate stress of 9.1 ± 0.3 MPa, strain levels of 1020 ± 126%, toughness of 33.7 ± 6.6 MJ m⁻³, and fracture energy of 171.1 ± 34.3 kJ m⁻². More importantly, the hydrogen bond engineered supramolecular hydrogels possess dynamic shape memory character, i.e shape fixing at low temperature while recovery after heating. As the proof of concept, the tailored hydrogel stents are readily manufactured by 3D printing, which showed good biocompatibility, load-bearing and drug elution, being beneficial for the biomedical applications. It is believed that the present 3D printing of the architected dynamic hydrogels with ultrahigh toughness can broaden their applications.     

Triply Hiding Optical Information via Excitation-Dependent Allochroic Photoluminescence Based on Cellulose Derivates

Optical encryption technologies are widely used in information security, whereas the technology with one single optical secret key can be easily cracked. Here, a triple encryption is reported, which hides patterned information in excitation-dependent allochroic materials with long afterglow, enhancing the security level. The allochroic materials are based on a uniaxial co-assembly structure of cellulose nanocrystals (CNCs) and silica. The assembled CNCs present blue emission with quantum yield of 19.8% under 367 nm UV radiation. The blue emission is maintained in the inverse structure when CNCs are calcinated and converted to carbon dots (CDs). The inverse uniaxial-assembly structure improves the CD emission by 6.7 times. The assembly structure can even improve the phosphorescence of CDs, leading to excellent excitation-dependent allochroic properties. Specifically, the materials maintain a cyan long afterglow luminescence at 480 nm after removing 365 nm UV light, whose lifetime is 0.492 s. Changing the excitation wavelength to 254 nm, a UV emission at 343 nm can be obtained, alongside a blue long afterglow luminescence of 420 nm, whose lifetime is 1.574 s. Combining with blue afterglow materials, optical encryption labels are prepared, which hide different patterned information in three scenarios: natural light, UV light, and afterglow luminescence.     

Degradation of tiamulin by a packed bed dielectric barrier plasma combined with TiO2 catalyst

Recently, a plasma catalyst was employed to efficiently degrade antibiotic residues in the environment. In this study, the plasma generated in a packed bed dielectric barrier reactor combined with TiO2 catalyst is used to degrade the antibiotic tiamulin (TIA) loaded on the surface of simulated soil particles. The effects of applied voltage, composition of the working gas, gas flow rate and presence or absence of catalyst on the degradation effect were studied. It was found that plasma and catalyst can produce a synergistic effect under optimal conditions (applied voltage 25 kV, oxygen ratio 1%, gas flow rate 0.6 l min−1, treatment time 5 min). The degradation efficiency of the plasma combined with catalyst can reach 78.6%, which is 18.4% higher than that of plasma without catalyst. When the applied voltage is 30 kV, the gas flow rate is 1 l min−1, the oxygen ratio is 1% and the plasma combined with TiO2 catalyst treats the sample for 5 min the degradation efficiency of TIA reached 97%. It can be concluded that a higher applied voltage and longer processing times not only lead to more degradation but also result in a lower energy efficiency. Decreasing the oxygen ratio and gas flow rate could improve the degradation efficiency. The relative distribution and identity of the major TIA degradation product generated was determined by high-performance liquid chromatography–mass spectrometry analysis. The mechanism of TIA removal by plasma and TiO2 catalyst was analyzed, and the possible degradation path is discussed.     

高烈度区某天燃气工程指挥部隔震加固设计与施工

针对新疆某天燃气工程指挥部的抗震问题,对其采用隔震技术进行加固,并采用"抱柱托梁加垫"和"夹墙梁"的方法进行施工,确保其上部结构安全。采用国际通用的三维空间有限元软件ETABS对其进行建模分析,并用时程分析方法对其进行隔震加固设计分析。在此基础上,分析了其减震效果,并介绍了本工程采用的施工工艺及相应的关键技术。结果表明:该工程隔震加固效果比较显著,能较好地满足现行规范和使用功能的要求,故对其进行隔震加固设计与施工是可行的。     

红枣片冷冻—红外组合干燥特性

目的:优化红枣片干燥工艺，改善产品品质。方法:以红枣片为研究对象，研究转换含水率、红外温度和切片厚度与干燥时间和干燥速率的相关关系，计算红枣片在FD-IRD中水分有效扩散系数随转换含水率、红外温度和切片厚度的变化规律，并根据试验数据计算红枣片FD-IRD的干燥活化能。结果:转换含水率越低，红外干燥时间越短，但过低的转换含水率，会使冷冻干燥时间大幅延长；适当提高红外干燥温度有利于提高水分有效扩散系数；红枣片越薄干燥速率越大，减小切片厚度能够提高水分有效扩散系数，利于缩短干燥时间；前后两段均为降速干燥过程，通过费克第二定律求解得到不同干燥条件下的冷冻干燥和红外干燥的水分有效扩散系数分别为3.39×10^-9～9.47×10^-9,3.34×10^-9～2.01×10^-8 m²/s;通过阿尼乌斯公式计算出红外干燥阶段干燥活化能为59.03 kJ/mol。结论:在转换含水率30%,红外温度60℃,切片厚度6 mm的条件下，冷冻—红外组合干燥技术所用干燥时间短、效率高。     

大学生创新创业感知价值、满意度与行为意向的关系研究

根据高校学生创新创业教育满意度调查问卷数据，构建高校创新创业教育满意度模型。结果表明：学生满意度与文化体系、教育体系、实践体系呈正相关关系；学生行为意向与文化体系、教育体系具有正相关关系；学生满意度对行为意向的正向影响显著。     

CoNi bimetallic alloy cocatalyst-modified TiO2 nanoflowers with enhanced photocatalytic hydrogen evolution

In terms of improving photocatalytic hydrogen production performance, inexpensive and earth-rich cocatalysts have become promising alternatives to precious metals. Herein, a novel CoNi–TiO₂ photocatalyst composed of TiO₂ nanoflowers and CoNi alloy was prepared by hydrothermal and chemical reduction methods. Various characterizations and test results have confirmed that the further improvement of the photocatalytic performance of the CoNi–TiO₂ photocatalyst is mainly due to the fact that the bimetallic CoNi alloy can accelerate charge transfer and inhibit the recombination of photo-induced carriers. The hydrogen production rate of the prepared CoNi–TiO₂ is about 24 times higher than that of the pristine TiO₂, and its hydrogen production rate value can reach 6580.9 μmol g^?1 h^?1, and showing comparable photocatalytic performance to 0.5 wt% Pt–TiO₂. In addition, combined with the characterization results, a probable mechanism for enhanced photocatalytic performance was proposed. This study provides favorable enlightenment for the design of a series of highly efficient non-precious metal TiO₂-based photocatalysts.