Search

Metal–organic frameworks (MOFs) have attracted extensive attention in methane (CH4) purification and storage. Specially, multinuclear cluster-based MOFs usually have prominent performance because of large cluster size and abundant open metal sites. However, compared to diverse combinations of organic linkers, one MOF with two or more multinuclear clusters is difficult to achieve. In this paper, we demonstrate a mixed multinuclear cluster strategy, which successfully led to three new heterometallic MOFs (SNNU-328–330) with the same common H3TATB [2,4,6-tris(4-carboxyphenyl)-1,3,5-triazine] tritopic linker and six types of multinuclear clusters ([YCd(COO)4(μ2-H2O)], [YCd2(COO)8], [In3(COO)6(μ3-OH)], [In3Eu2(COO)9(μ3-OH)3(μ4-O)], [Y9(COO)12(μ3-OH)14] and [Y2Cd8(COO)16(μ2-H2O)4(μ3-OH)8]). Three MOF adsorbents all show great potentials to remove the impurities (CO2and C2-hydrocarbons) in natural gas and show prominent high-pressure methane storage capacity. Among them, the ideal adsorbed solution theory separation ratios of equimolar C2H2/CH4, C2H4/CH4, C2H6/CH4, and CO2/CH4at 298 K for SNNU-328 reach to 29.7–16.0, 19.1–8.2, 33.2–10.3, and 74.3–8.5, which have surpassed many famous MOF adsorbents. Dynamic breakthrough experiments conducted at 273 and 298 K showed that SNNU-330 can separate CH4from C2H2/CH4, C2H4/CH4, C2H6/CH4, and CO2/CH4mixtures with the breakthrough interval times of about 48.2, 17.9, 37.2, and 17.1 min g–1(273 K, 1 bar, v/v= 50/50, 2 mL min–1), respectively. Remarkably, SNNU-329 exhibits extremely high methane storage performance at 298 K with the total uptake and working capacity of 192 cm3cm–3(95 bar) and 171 cm3cm–3(65 bar) due to the synergistic effects of high surface area, suitable pore sizes, and multiple open metal sites.

Heparin-mimicking polymers (HMPs) are artificially synthesized alternatives to heparin with comparable regulatory effects on protein adsorption and cell behavior. By introducing two major structural elements of HMPs (sulfonate- and glyco-containing units) to different areas of material surfaces, heterogeneous surfaces patterned with different HMPs and homogeneous surfaces patterned with the same HMPs can be obtained. In this work, heterogeneous HMP-patterned poly(dimethylsiloxane) (PDMS) surfaces with sulfonate-containing polySS (pS) and glyco-containing polyMAG (pM) distributed in circular patterns (with a diameter of 300 μm) were prepared (S–M and M–S). Specifically, pS and pM were distributed inside and outside the circles on S–M, respectively, and exchanged their distribution on M–S. Homogeneous HMP-patterned silicone surfaces (SM–SM) where sulfonate- and glyco-containing poly(SS-co-MAG) (pSM) were distributed uniformly were prepared. Vascular cells showed interestingly different behaviors between chemically homogeneous and heterogeneous surfaces. They tended to grow in the sulfonate-modified area on S–M and M–S and were distributed uniformly on SM–SM. Compared with M–S, S–M showed a better promoting effect on the growth of vascular cells. Among all the samples, SM–SM exhibited the highest proliferation density and an optimum spreading state of vascular cells, as well as the highest human umbilical vein endothelial cell (HUVEC) viability (∼99%) and relatively low human umbilical vein smooth muscle cell (HUVSMC) viability (∼72%). By heterogeneous or homogeneous patterning with different structural elements of HMPs, the modified silicone surfaces spatially guided vascular cell distribution and functions. This strategy provides a new surface engineering approach to the study of cell–HMP interactions.

High-energy ultrasonic controlling Al-KBF4-K2ZrF6reaction system was used to prepare ZrB2/AA6016 nanoparticle-reinforced aluminum matrix composites (PRAMC). Microstructural observations revealed that acoustic fluidic cavitation promoted the collapse and dispersion of nano-clusters. The plateau of the hardening curve indicates that ultrasonic treatment can improve the plasticity and toughness of the composite. Under 250 °C-70MPa, the apparent stress exponents of the matrix alloy, 3wt% ZrB2/AA6016 and 3wt% ultrasonic-assisted ZrB2/AA6016 composites are 7.34, 9.37, 12.62, respectively. The apparent activation energies are 165.20kJ/mol, 178.83kJ/mol and 215.33kJ/mol, respectively. According to the linear correlation coefficient, the true stress index of the composite material is determined to be 5, which indicates that the creep mechanism of the composite material is the dislocation climbing mechanism. Creep fracture analysis showed that the nano-ZrB2particles can effectively hinder the propagation of cracks, and ultrasonic treatment can effectively alleviate the stress concentration defects caused by nano-clusters.

Simple, fast, and sensitive detection of trace water in organic solvents is an urgent requirement for chemical industries. Herein, combining the unusual excited-state intramolecular proton transfer (ESIPT) mechanism with the effective strategy of pore space partition, for the first time, we construct a powerful fluorescent metal–organic framework (SNNU-301) probe with excellent water stability. The SNNU-301 probe shows a remarkable performance for turn-on ESIPT-based fluorescence response to water in nine common organic solvents, exhibiting wide linear ranges, low limit of detection values, and ultrafast response, especially in dimethyl sulfoxide (0–5.2%; 0.011%, v/v; 110 s). The typical ESIPT-sensitive linker 2,5-dihydroxyterephthalate (DHBDC) imparts it with discriminative detection properties via enol–keto tautomerism, and light-responsive triangular tri(pyridin-4-yl)-amine (TPA) realizes pore space partition. The theoretical calculation gives an in-depth explanation about the proton transfer mechanism. Comparative experiments and GCMC simulation provide evidence that the synergy of the ESIPT process and TPA of the framework further boosts its performance effectively. Definitely, this work not only offers a promising candidate with fast detection speed, high sensitivity, excellent universality, and visual observation for the determination of water in organic solvents but also provides valuable guidance for the design of high-performance fluorescent probes.

We report a new sensing mechanism based on an indium-dihydroxyterephthalic acid metal–organic framework (MOF, SNNU-153), in which the spatially fitted analyte-MOF hydrogen-bond (H-bond) formation provides selective recognition while the analyte-H-bond assisted excited-state intramolecular proton transfer (ESIPT) and the resulting ratiometric emission act as a superior signal transducer with ultrafast response. The synergy of ESIPT signal transduction and confined MOF pore enables the SNNU-153 sensor selectively sensing hydrazine even among nitrogen-containing hydride analogs such as NH3, NH2OH, and (Me)2NNH2. The key of H-bond and associated ESIPT was further counter evidenced by an indium-2,5-dimethoxyterephthalic acid MOF (SNNU-152), where the hydroxyl protons were removed by methylation, showing near inertness to N2H4. The new molecular recognition concept thus makes SNNU-153 a powerful N2H4sensor, which should be far-reaching to other sensing elements.

Surface endothelialization is a promising way to improve the hemocompatibility of biomaterials. However, current surface endothelialization strategies have limitations. For example, various surface functions are not well balanced, leading to undesirable results, especially when multiple functional components are introduced. In this work, a multifunctional surface was constructed by balancing the functions of antifouling, nitric oxide (NO) release and endothelial cell promotion via layer-by-layer (LBL) self-assembly. Poly(sodium p-styrenesulfonate-co-oligo(ethylene glycol) methacrylate) (negatively charged) and polyethyleneimine (positively charged) were deposited on silicon substrates to construct multilayers by LBL self-assembly. Then, organic selenium, which has a NO-releasing function, and the cell-adhesive peptide Gly-Arg-Glu-Asp-Val-Tyr, which selectively promotes endothelial cells, were introduced on the assembled multilayers. Poly(oligo(ethylene glycol) methacrylate) is a hydrophilic component for antifouling properties, and poly(sodium p-styrenesulfonate) is a heparin analog that provides negative charges. By modulating the contents of poly(oligo(ethylene glycol) methacrylate) and poly(sodium p-styrenesulfonate) in the copolymers, the NO release rates catalyzed by the modified surfaces were regulated. Moreover, the behaviors of endothelial cells and smooth muscle cells on modified surfaces were well controlled. The optimized surface strongly promoted endothelial cells and inhibited smooth muscle cells to achieve endothelialization effectively.

To address the adverse reactions caused by the implantation of blood-contacting materials, researchers have developed different strategies, of which mimicking multiple key features of endothelial cells is the most effective. However, simultaneously immobilizing multiple chemical components on a single material surface and maintaining the effects of individual components are challenging. In this work, endothelium-mimicking silicone surfaces were developed by incorporating the antifouling polymer poly(oligo(ethylene glycol) methacrylate), the glycosaminoglycan analog poly(sodium 4-vinyl-benzenesulfonate) and a nitric oxide catalyst (selenocystamine dihydrochloride). Through the rational regulation of multiple chemical components, the surfaces harmoniously resisted nonspecific protein adsorption, platelet adhesion and activation and smooth muscle cell hyperproliferation while promoting endothelial cell proliferation and migration. The coculture experiment with HUVECs and HUVSMCs showed that the optimum selectivity of HUVECs/HUVSMCs was ∼1.7. This work contributes insight into the control of antifouling properties and endothelial selectivity, providing a new avenue for the development of blood-contacting materials.

This study investigated methane hydrate inhibition by a new polyvinyl lactam-based kinetic hydrate inhibitor (KHI) by determining the maximum subcooling temperature, induction time, and growth rate using a high-pressure sapphire reactor. The studied KHI, namely, the random copolymer of N-vinylcaprolactam and 1-vinylimidazole (PVCap-co-VIM), was synthesized by free radical solution polymerization with the objective of producing copolymers with higher cloud points than the poly(N-vinylcaprolactam) (PVCap) homopolymer. These data were compared with those of laboratory-made PVCap and commercial poly(N-vinylpyrrolidone) (PVPK90) under various cooling rates (1.0, 2.0, and 5.0 K/h) and mass concentrations (0.5, 1.0, and 2.0 wt %). The experimental results showed that the cooling rate had little effect on the maximum subcooling temperature of the KHIs. PVCap-co-VIM was capable of delaying the nucleation of hydrate crystals for a longer time than PVPK90 and successfully suppressed hydrate growth in the early stage of hydrate formation. PVCap performed better than PVCap-co-VIM under the same conditions, but PVCap-co-VIM exhibited a significantly higher cloud point temperature (TCl> 70 °C) than PVCap (TCl= 37.9 °C), which was beneficial for field applications. Furthermore, the measured powder X-ray diffraction and Raman spectral data showed that the formed hydrate structures were the same (structure I) for all the studied KHI-containing systems, despite some differences in the characteristic peak intensities as a result of different inhibitory activities. Cryo-scanning electron microscopy images illustrated that the morphology of the formed CH4hydrate crystals varied significantly by KHIs, which could be helpful for safe pipeline fluid transportation.

The incorporation of heterometallic atoms into the structure of titanium–oxygen nanomaterials is one of the known and effective strategies to develop new high-performance photovoltaic active materials. In this study, we have synthesized three benzoic acid-stabilized heterometallic titanium oxo clusters with the different transition metals Co, Cu, and Cd, formulated as [Ti4Co2(μ2-O)2(μ3-O)2(C6H5COO)12(CH3CN)2]·2CH3CN (1), [Ti5Cu4(μ3-O)6(C6H5COO)16] (2), and [Ti12Cd5(μ2-O)(μ3-O)15(μ4-O)2(C6H5COO)22(C6H5COOH)(CH3CN)]·CH3CN·C6H5COOH (3), and then we characterized their structures. UV–vis spectroscopy analysis revealed an enhanced UV–vis-light absorption of those heterometallic clusters. The density functional theory calculations indicated that charge transfer occurs from the p orbital of O atoms to the d orbital of Ti atoms in the TiO core (O → Ti) as well as from the metal to the core in 1and 2. We also measured the photocurrent response and photocatalytic H2evolution, which shows enhancement in the photocurrent intensity and good H2evolution ability because of the cooperative effect of heterometal doping in titanium oxo clusters.

Electrochromic devices (ECDs) have exhibited promising applications in the fields of energy-saving intelligent buildings and next-generation displays because of their simple structure, low power consumption, and multicolor displays. W18O49/polyaniline (PANI) hybrid films are prepared and assembled to ECDs. Compared with pure PANI and W18O49films, the hybrid film exhibits superior electrochemical and electrochromic performance, including high optical modulation (70.2%), large areal capacity (79.6 mF/cm2), and good capacitance retention. The excellent electrochemical and electrochromic performance is ascribed to the formation of the donor (PANI)-acceptor (W18O49) pair, the porous structure in the nanowires, and the large surface area, which enhance electron delocalization of the W18O49/PANI, improve the ion diffusion rate, and increase the charge storage sites. Furthermore, benefitting from the outstanding optical, electrical, and multifunctional properties, the W18O49/PANI hybrid film-based ECD platform is expected to play an important role in electrochromism and energy storage.

The binary cluster [Co@Sn9]4–(1) was extracted directly from ethylenediamine (en) solutions of an intermetallic precursor with nominal composition “K5Co3Sn9”, and its reactions with various organometallic reagents were explored. Reaction with Ni(PPh3)2(CO)2gives [Co@Sn9Ni(CO)]3–(2), a Co-centered closo-Sn9Ni bicapped square antiprism. Analogous reactions with Ni(COD)2, Pt(PPh3)4, and Au(PPh3)Ph led to the isolation of [Co@Sn9Ni(C2H4)]3–(3), [Co@Sn9Pt(PPh3)]3–(4), and [Co@Sn9AuPh]3–(5), respectively. 3is structurally similar to 2but significantly distorted from a closo-cluster with one open square face. The coordination of [CoSn9]3–by PtPPh3(4) or AuPh (5) induces a structural transformation in the CoSn9core, from a monocapped square antiprism (C4v) to a tricapped trigonal prismatic structure (pseudo-C3v), with the transition metal fragment capping a triangular face. The four trimetallic anions presented here represent a new family of ternary functionalized Zintl clusters incorporating a d9transition metal center. All clusters were characterized by single-crystal X-ray diffraction and electrospray ionization mass spectrometry (ESI-MS).

Fault location is an effective way to ensure quickly power recovery after a failure in power distribution system. Bad operation environment of FTU, damaged elements or lost information usually cause variations in fault information for correlation analysis in fault location of power distribution system. A data mining (DM) correlation analysis model based on rough sets (RS) theory and immune algorithm (IA) is proposed in this paper. Firstly, using RS theory to extract domain knowledge, a set of the given variant fault pattern is converted into a decision table in RS. Secondly, an attribute reduction of the decision table is made by using the IA theory, and the intrinsic correlation rules between input vector (condition attribute) and output vector (decision attribute) are mined. Then, the data mining method is used to deal with the distortion of FTU real-time input information. According to the current limit information sequence of section switches, line fault states in each section are judged to realize the fault location in power distribution network. Finally, the feasibility and effectiveness of the fault location model of distribution network based on RS-IA data mining model is verified by simulation.

The hydrothermal reaction of uranyl ions with (5-methyl-1,3-phenylene)diphosphonic acid (H4MPDP) in the presence of additives such as nitric acid, N-bearing species, and heterometal ions yielded five new uranyl organic hybrids: (H3O)[(UO2)5(H2O)4(H3DPB)2(H2DPB)(HDPB)]·2H2O (1), (Hphen)(phen)[(UO2)3(H2DPB)(HDPB)] (2), (H2dipy)[(UO2)3(MPDP)2] (3), Zn(bipy)(UO2)(MPDP) (4), and Co(bipy)(UO2)(MPDP)·H2O (5) (H5DPB = 3,5-diphosphonobenzoic acid; phen = 1,10-phenanthroline; dipy = 4,4′-bipyridine; bipy = 2,2′-bipyridine). Single-crystal X-ray diffraction (XRD) demonstrates that 1and 2are 3D frameworks constructed of uranyl centers and carboxyphosphonate DPB ligands; the latter were formed via the in situ oxidation of H4MPDP. In the homometallic uranyl diphosphonate 3, less common UO6square bipyramids connected by MPDP ligands were incorporated to form the 2D assembly. A further introduction of heterometal ions produced two heterobimetallic uranyl phosphonates 4and 5. Both of them show layered structures, formed by UO6square bipyramids linked by MPDP ligands with heterometal-centered polyhedra decorated on the sides of the layers. It is found that the pH and heterometal ions have significant effects on the structures of the complexes. In addition to the syntheses and XRD characterization, the spectroscopic properties of these uranyl complexes were also addressed. To complement the experimental results, density functional theory calculations were carried out on several model complexes that feature a homo- or heterobimetallic molecular skeleton. Geometrical/electronic structures, IR spectra, and electronic absorptions were discussed.

Despite continuous technological improvements in sample preparation, mass-spectrometry-based proteomics for trace samples faces the challenges of sensitivity, quantification accuracy, and reproducibility. Herein, we explored the applicability of turboDDA (a method that uses data-dependent acquisition without dynamic exclusion) for quantitative proteomics of trace samples. After systematic optimization of acquisition parameters, we compared the performance of turboDDA with that of data-dependent acquisition with dynamic exclusion (DEDDA). By benchmarking the analysis of trace unlabeled human cell digests, turboDDA showed substantially better sensitivity in comparison with DEDDA, whether for unfractionated or high pH fractionated samples. Furthermore, through designing an iTRAQ-labeled three-proteome model (i.e., tryptic digest of protein lysates from yeast, human, and E. coli) to document the interference effect, we evaluated the quantification interference, accuracy, reproducibility of iTRAQ labeled trace samples, and the impact of PIF (precursor intensity fraction) cutoff for different approaches (turboDDA and DEDDA). The results showed that improved quantification accuracy and reproducibility could be achieved by turboDDA, while a more stringent PIF cutoff resulted in more accurate quantification but less peptide identification for both approaches. Finally, the turboDDA strategy was applied to the differential analysis of limited amounts of human lung cancer cell samples, showing great promise in trace proteomics sample analysis.

The selective separation of C2H2from C2H2/CO2and C2H2/C2H4is crucial but remains incredibly challenging due to their extremely similar physical characteristics and nearly equivalent molecular kinetic diameters. Here, four novel pillared-layer-like metal–organic frameworks (MOFs) with quadrilateral channels, SNNU-283–286, which consist of a unique two-dimensional wave layer and carboxylic acid ligands as columns, are successfully synthesized via a facile solvothermal process. Interestingly, with the decrease of the bent angle between two −COOH groups in ligands, the distortion of the quadrilateral channel increases, and the two-dimensional wave layer becomes more curving. The optimized SNNU-285 with appropriate structural distortion exhibits remarkably high C2H2adsorption capacity (124.6 cm3g–1), superior selectivity (20.2), and enhanced breakthrough interval times (21.6 min g–1at 273 K) for C2H2/CO2due to the exposed open metal site and the polar furan ring. This work offers novel pillared-layer-like MOFs with quadrilateral channels for efficient C2H2adsorption and purification.

Electrical safety is a common goal of electricity customers and power companies. In order to meet the needs of different users for electricity safety, ensure the legitimate rights and interests of the State Grid Corporation and users, promote the service level of State Grid Corporation and improve the life quality of the users, an effective measures is the user electricity safety inspections. Firstly, it introduces the development of cloud computing technology and the advantages of the user electricity safety monitoring system based on cloud computing technology. Secondly, from three aspects of the system structure, function and cloud system, the user electrical safety monitoring system based on cloud computing technology has been elaborated. Lastly, it discusses the development of the lateral user electricity safety monitoring, and provides the reference for the application of user electricity safety inspections.

Porous structure of the super absorbent polymer (SAP) was synthesized through inverse suspension method by adding acrylic acid (AA) and acrylic amide (AM) as monomer, N,N'-Methylene-bis-acrylamide (MBA) as cross-linking agent, the mixed solution of methanol and ethanol as pore-foaming agent. The factors that influenced the bibulous performance of the super absorbent polymer were studied including the dosage of cross-linking agent, the dosage of pore-foaming agent, monomer ratio, revolving speed. The Internal structure and surface morphology of SAP was characterized by scanning electron microscopy (SEM). It indicated that when the monomer ratio was m(AM):m(AA)=1:2; the weight rate of cross-linking agent and pore-foaming agent were 0.06%(compared with the quality of the monomer) and 9%, the product attained the best water absorbency of 2909 g/g in distilled water, the saline absorbency was 124.5 g/g; the water absorption rate was 10. Meanwhile, SEM showed that the structure of the copolymer was full of holes.

Based on virtual prototyping technology (VPT) and software engineering principles, and combining with the characteristics of steam jet pump, a virtual prototyping development platform of steam jet pump, consisting of five functional models, including general scheme design, virtual physical prototype design, virtual performance prototype design, assemble process analysis and VR model design and evaluation, was present in this paper. The architecture and functional model of the virtual steam jet pump prototyping development platform (VSJPDP) were proposed in the article. The ideas corresponding to several key technological problems for implementing the VSJPDP were also described. At last, the platform’s feasibility, effectiveness and advancement were verified by the development process of the virtual single-stage steam jet pump.

Based on analyzing the shortcomings of the current product development mode and methods of the automatic transmission, and on the principle of virtual prototype technology(VPT) and the thought of business process re-engineering (BPR), a concurrent development flow model suitable for virtual automatic transmission prototype(VATP) was established. The function model and the architecture of the platform for developing the VATP were also described in detail. Finally, the ideas for solving some key technological problems faced during implementing the platform were discussed in this paper.

This paper discusses the application of the boundary contour method for resolving plate bending problems. The exploitation of the integrand divergence free property of the plate bending boundary integral equation based on the Kirchhoff hypothesis and a very useful application of Stokes' Theorem are presented to convert surface integrals on boundary elements to the computation of bending potential functions on the discretized boundary points, even for curved surface elements of arbitrary shape. Singularity and treatment of the discontinued corner point are not needed at all. The evaluation of the physics variant at internal points is also shown in this article. Numerical results are presented for some plate bending problems and compared against analytical and previous solutions.

Magnesium alloys and magnesium matrix composites by means of its excellent performance have wide application prospect in electronics, automotive, biotechnology, aerospace field, and welding technology has become a key of restricting its application. This paper describes the welding characteristics of magnesium, the obvious advantages in the application and the domestic and foreign research advance technology of plasma arc welding of magnesium, and summarizes the existing problems and development trends of plasma arc welding technology of magnesium.

TianQin is a proposed space-borne gravitational-wave detection mission using circular high Earth orbits. The geocentric concept has raised questions about the disturbing effect of the nearby gravity field of the Earth-Moon system on the highly sensitive intersatellite ranging measurements. Here we examine the issue through high-precision numerical orbit simulations with detailed gravity-field models. By evaluating range accelerations between distant free-falling test masses, the study shows that the majority of the Earth-Moon's gravity disturbances are not in TianQin's detection frequency band above 10-4 Hz, and hence present no showstoppers to the mission. [ABSTRACT FROM AUTHOR]