Fibrous porous ceramics with devisable phenolic resin reinforcing layer

Fibrous porous ceramics with devisable phenolic resin reinforcing layer were fabricated using low cost atmospheric impregnation technology at room temperature. In combination with additional sealing method, phenolic resin reinforcing layer with controllable thickness could be obtained on the surface of fibrous porous ceramics. Typical gradient profile was observed along the thickness direction of impregnation. The effects of the phenolic resin reinforcing layer on mechanical properties and thermal insulation properties were studied. The results revealed that compressive strength increased from 1.70?MPa to 2.61?MPa, tensile strength increased from 0.78?MPa to 0.91?MPa, and flexural strength increased from 9.55?MPa to 10.89?MPa with the phenolic resin layer increasing from 0?mm to 9?mm. Simultaneously, room-temperature thermal conductivity increased from 0.051?W/(m·K) to 0.055?W/(m·K). In addition, the impact resistance of the surface of the material was obviously improved. The contact angel of the surface of the material exceeded 125°, which effectively improved the environmental adaptability.     

Porous polyurethane film fabricated via the breath figure approach for sustained drug release

The breath figure (BF) method is an effective process for fabricating porous polymeric films. In this study, we fabricated porous polymer films from thermoplastic polyurethane (PU) through static BF with CHCl₃ as a solvent under 55–80% relative humidity. The porous PU films were prepared within various pore structures and sizes, which were adjustable, depending on the fabrication conditions. The humidity and exposure time were examined as variable parameters affecting the surface morphology, wettability, and cytotoxicity. Atorvastatin calcium, a hyperlipidemic agent, was loaded into the porous films during the casting process, and the drug-loading and drug-releasing behaviors of the porous PU membranes were evaluated. Approximately 60–80% of the drug was released in 14 days. The films exhibited sustained drug-release performances because of the hydrophobicity and nonbiodegradable nature of PU for perivascular drug administration. © 2019 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2019 , 136, 47658.     

Deposition of heterojunction of ZnO on hydrogenated TiO2 nanotube arrays by atomic layer deposition for enhanced photoelectrochemical water splitting

The heterojunction of ZnO was deposited on hydrogenated TiO₂ nanotube arrays (H–TiO₂) by atomic layer deposition (ALD) with various cycles. The ZnO was uniformly wrapped with the H–TiO₂ samples and the thickness could be accurately controlled by the cycle numbers of ALD. The higher growth rate ~2.7 Å/cycle was obtained due to the surface amorphous layer, compared with the air-treated samples (A-TiO₂), ~2.3 Å/cycle. When the cycle numbers increased to 200, nanowire arrays appeared. Interestingly, the absorption in the visible light region improved more significantly when ALD ZnO was employed for the H–TiO₂ rather than the A-TiO₂ samples. The H–TiO₂ samples with 42 nm of ALD ZnO exhibited enhanced photoelectrochemical water splitting performances, compared with the A-TiO₂ with 42 nm of ALD ZnO. This was related to the higher degree of the electronic band bending and improved photo-response in the UV and visible light region, resulting from the oxygen vacancies.     

Systematic optimization of low bandgap polymer/[6,6]-phenyl C70 butyric acid methyl ester blend photodiode via structural engineering

Synthetic approaches for optimizing polymer-based organic photodiodes (OPDs) by systematically analyzing the effects of the hole-blocking layer, the electron-blocking layer, and the thickness and morphology of the active layer with respect to the dark current and detectivity have been reported. PBDTT-DPP with a repeating alkylthienylbenzodithiophene (BDTT) and diketopyrrolopyrrole (DPP) units is used as a p-type polymer for achieving both broadband absorption and a high absorption coefficient in conjunction with n-type [6,6]-phenyl C₇₀ butyric acid methyl ester (PC₇₀BM) for constructing photoactive layers. Through systematic investigations of various interfacial layers, we found that the thickness of the active layer and the energy level of the hole/electron blocking layer were critical for minimizing the dark current of OPDs. By changing the deposition method of the PBDTT-DPP/PC₇₀BM blend and using post treatment, we discovered that the morphology of the active layer was directly related to the photocurrent of OPDs. Furthermore, we conducted a comparative study between a bulk heterojunction and a planar heterojunction (PHJ) to demonstrate the effectiveness of the PHJ for suppressing the dark current. Consequently, we realized a high detectivity of 5.3 × 10¹² Jones with an optimized device architecture and morphology. This work shows the importance of a synthetic approach for optimizing OPDs that requires both a high photocurrent and a low dark current in the reverse saturation regime.     

Enhancing light-extraction efficiency of OLEDs with high- and low-refractive-index organic–inorganic hybrid materials

High- and low-refractive-index hybrid materials were prepared by an in situ acid-free sol–gel process for internal and external light-extraction layers in organic light-emitting diodes (OLEDs). A random copolymer of methyl methacrylate (MMA) and 3-(trimethoxysilyl) propyl methacrylate (MSMA), poly(MMA-co-MSMA), which was capped with trialkoxysilane in MSMA units, was used as a precursor. The precursor was further reacted with titanium(IV) isopropoxide (TTIP) and tetraethyl orthosilicate (TEOS) to synthesize the high- and low-refractive-index hybrid materials, respectively, in which TiO₂ and SiO₂ nanoparticles were well dispersed, respectively, in the polymer matrix. After the reactions with TTIP and TEOS, the refractive index increased to 1.81 and decreased to 1.44 from 1.50 of the precursor, respectively. The luminance, power, and current efficiency of the OLED with an external light-extraction layer were enhanced by 21.3, 28.6, and 29.1%, respectively, those of the OLED with an internal light-extraction layer were increased by 62.4, 76.9, and 59.2%, respectively, and those of the device with combined ELEL and ILEL were enhanced by 62.7, 77.2, and 59.3%, respectively, when compared to values for the reference OLED without an internal or external light-extraction layer. These results indicate that high- and low-refractive-index materials are desirable for enhancement in light-extraction efficiency, and they can provide practical solutions for various applications such as OLED displays and lighting.     

褥垫层和刚性基础在CFG桩复合地基中的应用

针对褥垫层和刚性基础在CFG桩复合地基中的应用进行了研究,通过分析褥垫层和刚性基础对复合地基受力的影响,揭示褥垫层和足够刚度基础的作用,为CFG桩的合理设计及在工程实践中的应用提供了一定指导。     

环氧自流平2mm厚地坪施工方案

结合环氧自流平地面性能特点及环氧自流平地坪设计概况,对基土、基层、结合层、面层施工工艺进行了介绍,并提出相关施工质量保证措施及成品保护等措施,从而保证了施工质量,对该施工工艺具有积极的推广作用。     

Kinetic mobility and connectivity in nanopore networks

Experimental results for methane and carbon dioxide diffusion in coal, as reported in the literature, often lead to diffusion rates of CO₂ appearing to be much greater than that of CH₄. The interpretation sometimes offered that the diffusion coefficient for CO₂ is 1–2 orders of magnitude higher than that of CH₄, violates fundamental principles. Nevertheless, the experimental observations require explanation. In this article, we: (a) Develop simplified models for the fast estimation of transport coefficients. These are compared with comprehensive grand canonical Monte Carlo (GCMC) and molecular dynamic (MD) simulations, collectively defined as molecular simulations (MS), which provide theoretical adsorption isotherms and various transport coefficients based on multicenter potential energy equations. The simplified models are shown to have acceptable accuracies. (b) Use the simplified models to compare diffusivities of CO₂ and CH₄ in carbon nanopores. For all cases examined, the diffusivity of CH₄ is always larger than that of CO₂. (c) Offer two explanations for the apparently contradictory experimental observations (that CO₂ sometimes appears to diffuse much faster than the CH₄ molecule, even though CH₄ is lighter and has smaller adsorption affinity): (i) CH₄ mobility could be significantly reduced by directional forces resulting from irregular pore geometries; and (ii) if pores contain throats with sizes close to the CH₄ molecular diameter, the energy barrier that the methane molecules must overcome to proceed through is much larger than that required for CO₂. (d) Demonstrate that both mobility and connectivity issues can be addressed using kinetic theory in association with percolation analysis. Furthermore, this method of understanding pore networks provides a number of important quantitative measures including percolation threshold, size of largest cluster, shortest path and tortuosity. Separating different transport mechanisms, as we propose here, provides improved insights into the complex transport phenomena that occur in carbonaceous porous media. In many cases, diffusivities reported in the literature with mixed mechanisms are better named “apparent transport coefficients,” because they lump in other unrelated phenomena, violating the fundamental basis of, or mathematical assumptions imposed on, the definition of diffusion. © 2011 American Institute of Chemical Engineers AIChE J, 2012     

结合沉积成藏规律实现葡萄花疑难层测井解释

测井综合评价中,常以电阻率测量值的高低来反映岩层的含油饱和程度,以孔隙度测井值来反映岩层的储集能力。由于沉积成藏条件复杂,部分岩层测井评价存在困难,具体归纳为"低阻油层"、"高阻水层"两种情况。弱水动力的低能量沉积环境、辅以较高的地层水矿化度形成"低阻油层";而油气运移"路过"的部分岩层,孔隙内残余原油氧化后致使流体导电能力降低,形成"高阻水层"。以卫星油田葡萄花油层为例,在沉积微相、油气运移成藏规律基础上,分析总结复杂油水分布特征,将电阻率、孔隙度、断层、岩层到葡顶的距离、砂体展布情况等诸要素联系起来,建立综合识别方法,有效提高了这两类疑难储层的测井评价精度。     

电火花强化工艺制造金刚石镀层实验研究

为实现金刚石工具的快速制造和在线快速修复,探索了一种简单快速的金刚石表面强化工艺方法的可行性。以金刚石颗粒和钴颗粒为主要成分,采用压制工艺制作电极,并用该电极在基体材料304不锈钢板上进行电火花强化实验,探究电极的压制压力、金刚石含量、加工电流和加工时间等参数对实验效果的影响规律。用镀钛金刚石电极加工5 min,可得到表面上金刚石颗粒的表面积分数为13.5%、厚度为400μm的强化层,且该强化层具有很好的磨削性能。