Point-of-care testing (POCT), as a portable and user-friendly technology, can obtain accurate test results immediately at the sampling point. Nowadays, microfluidic paper-based analysis devices (μPads) have attracted the eye of the public and accelerated the development of POCT. A variety of detection methods are combined with μPads to realize precise, rapid and sensitive POCT. This article mainly introduced the development of electrochemistry and optical detection methods on μPads for POCT and their applications on disease analysis, environmental monitoring and food control in the past 5 years. Finally, the challenges and future development prospects of μPads for POCT were discussed.

The development of highly efficient electrocatalysts for the oxygen evolution reaction (OER) plays a crucial role in many regenerative electrochemical energy-conversion systems. Herein, we report a novel double core−shell-structured CNH@PDA@NiMOF (CNH−D−NiMOF) composite based on the support of carbon nanohorns (CNHs) and the direction of polydopamine (PDA) on the synthesis of metal−organic frameworks (MOFs). It is found that this unique structure improves the electrocatalytic performance and stability of the composites. Furthermore, a controlled partial pyrolysis strategy was proposed to construct the Ni-based nanoparticleembedded N-doped CNHs. The partial pyrolysis method preserves the framework structure of MOFs for effective substrate diffusion while producing highly active nanoparticles. This leads to the result that the Ni-based nanoparticle-embedded Ndoped CNHs possess higher stability and significantly improved electrocatalytic properties. Among these derivatives, the sample prepared at a pyrolysis temperature of 400 °C (named as CNH−D−NiMOF-400) outperforms most of the reported unprecious-metal catalysts. At current densities of 20 and 100 mA•cm −2 , the overpotentials of CNH−D−NiMOF-400 are 270 and 340 mV for the OER on a carbon fiber paper (CFP), respectively. The outstanding electrocatalytic properties above suggest that this composite is an excellent candidate for the substitution of noble metal-based catalysts for OER.

As most of the known systems are flashtype, long-lasting chemiluminescence (CL) emissions are extremely needed for the application of cold light sources, accurate CL quantitative analysis, and biological mapping. In this work, the flashtype system of luminol was altered to a long lasting CL system just because of the paper substrate. The Cu­(II)-based organic complex was loaded on the paper surface, which can trigger luminol-H2O2 to produce a long lasting CL emission for over 30 min. By using 1,10-phenanthroline-2,9-dicarboxylic acid (PDA) as the ligand, a hexacoordinated Cu­(II)-based organic complex was synthesized by the simple freeze-drying method. It is interesting that the complex morphology can be controlled by adding different amounts of water in the synthesizing procedure. The complex with a certain size can be definitely trapped in the pores of the cellulose. Then, slow diffusion, which can be attributed to the long lasting CL emission, was produced. With the high catalytic activity of the complex, reactive oxygen species from H2O2 was generated and was responsible for the high CL intensity. By using the paper substrate, the flash-type luminol system can be easily transferred to the long-duration CL system without any extra reagent. This long-lasting emission system was used for hydrogen sulfide detection by the CL imaging method. This paper-based sensor has great potential for CL imaging in the clinical field in the future.

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The cold-formed steel (CFS) double-lipped equal-leg angle is widely used in modular container houses and cold-formed steel buildings. To study the buckling behavior and bearing capacity design method of the cold-formed steel (CFS) double-lipped equal-leg angle under axial compression, 24 CFS double-lipped equal-leg angles with different sections and slenderness ratios the axial compression were conducted. The test results showed that the distortional buckling occurs for specimens with a small width-to-thickness ratio and small slenderness ratio. The buckling interactive with distortional and global flexural buckling was observed for the specimens with small width-to-thickness ratios and large slenderness ratios. The specimens with large width-to-thickness ratios and small slenderness ratios showed interactive buckling with local and distortion buckling. The specimens with large width-to-thickness ratios and large slenderness ratio developed interactive buckling with local, distortional, and global flexural buckling. The finite element model established by ABAQUS software was used to simulate and analyze the test. The buckling modes and the load-carrying capacities analyzed by the finite element model agreed with the test results, which showed that the developed finite element model was feasible to analyze the buckling and bearing capacity of the CFS double-lipped equal-leg angles. The experimental results were compared with those calculated by the direct strength method in the North American standard and the effective width method in the Chinese standard. The comparisons indicated that the calculated results are very conservative with maximum value 36% and 51% for direct strength method and effective width method, respectively. The coefficient of variation was 0.276 and 0.397, respectively. Finally, the modified direct strength method and the modified effective width method were proposed based on the experimental results. The comparison on the ultimate strength between test results and calculated results by using the modified method showed a good agreement. The modified method can be as a proposed desigh method for the ultimate strength of the CFS double-lipped equal-leg angles under axial compression.

The relationship between the stability coefficient φ and slenderness λ ¯ for axial compression perforated members was studied using finite element software ABAQUS in this paper. The overall buckling of members with unperforated, circular and multi-circular holes was described. The influence on the members of hole position, hole size, hole spacing and plate size was analysis. According to the main parameters affecting the overall buckling of the perforated members, results show that φ will decrease with the increase of hole size. for multi-circular holes members, the smaller the hole spacing is, the more likely φ will be affected. When the hole spacing is wide enough, φ will become stable.

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