Electrocatalytic Reduction of CO2 to Ethylene by Molecular Cu‐Complex Immobilized on Graphitized Mesoporous Carbon

The electrochemical reduction of carbon dioxide (CO₂) to hydrocarbons is a challenging task because of the issues in controlling the efficiency and selectivity of the products. Among the various transition metals, copper has attracted attention as it yields more reduced and C2 products even while using mononuclear copper center as catalysts. In addition, it is found that reversible formation of copper nanoparticle acts as the real catalytically active site for the conversion of CO₂ to reduced products. Here, it is demonstrated that the dinuclear molecular copper complex immobilized over graphitized mesoporous carbon can act as catalysts for the conversion of CO₂ to hydrocarbons (methane and ethylene) up to 60%. Interestingly, high selectivity toward C2 product (40% faradaic efficiency) is achieved by a molecular complex based hybrid material from CO₂ in 0.1 m KCl. In addition, the role of local pH, porous structure, and carbon support in limiting the mass transport to achieve the highly reduced products is demonstrated. Although the spectroscopic analysis of the catalysts exhibits molecular nature of the complex after 2 h bulk electrolysis, morphological study reveals that the newly generated copper cluster is the real active site during the catalytic reactions.     

Template Engineering of CuBi2O4 Single‐Crystal Thin Film Photocathodes

To develop strategies for efficient photo‐electrochemical water‐splitting, it is important to understand the fundamental properties of oxide photoelectrodes by synthesizing and investigating their single‐crystal thin films. However, it is challenging to synthesize high‐quality single‐crystal thin films from copper‐based oxide photoelectrodes due to the occurrence of significant defects such as copper or oxygen vacancies and grains. Here, the CuBi₂O₄ (CBO) single‐crystal thin film photocathode is achieved using a NiO template layer grown on single‐crystal SrTiO₃ (STO) (001) substrate via pulsed laser deposition. The NiO template layer plays a role as a buffer layer of large lattice mismatch between CBO and STO (001) substrate through domain‐matching epitaxy, and forms a type‐II band alignment with CBO, which prohibits the transfer of photogenerated electrons toward bottom electrode. The photocurrent densities of the CBO single‐crystal thin film photocathode demonstrate ?0.4 and ?0.7 mA cm^?2 at even 0 V_RHE with no severe dark current under illumination in a 0.1 m potassium phosphate buffer solution without and with H₂O₂ as an electron scavenger, respectively. The successful synthesis of high‐quality CBO single‐crystal thin film would be a cornerstone for the in‐depth understanding of the fundamental properties of CBO toward efficient photo‐electrochemical water‐splitting.     

Imidazolium-Functionalized Diacetylene Amphiphiles: Strike a Lighter and Wear Polaroid Glasses to Decipher the Secret Code

The development of smart inks that change color and transparency in response to external stimuli is very important for various fields, from modern art to safety and anticounterfeiting technology. A uniaxially oriented diacetylene thin film on a macroscopic area is obtained by coating, self-assembling and topochemical photopolymerizing of imidazolium-functionalized diacetylenes (M-DA and T-DA) and 4,6-decadiyne ink (70 wt%:20 wt%:10 wt%) exhibiting a lyotropic smectic A liquid-crystalline phase at room temperature. The color and transparency of letters and symbols written with the DA-based secret inks change reversibly from blue to red as well as from colorless transparent to black opaque depending on the temperature and polarization axis. A secret code written with thermoresponsive and polarization-dependent secret inks consisting of imidazolium-functionalized diacetylenes is successfully deciphered by wearing polaroid glasses and holding a burning torch.     

Hepatoprotective Potency of Chrysophanol 8-O-Glucoside from Rheum palmatum L. against Hepatic Fibrosis via Regulation of the STAT3 Signaling Pathway

Rhubarb is a well-known herb worldwide and includes approximately 60 species of the Rheum genus. One of the representative plants is Rheum palmatum, which is prescribed as official rhubarb due to its pharmacological potential in the Korean and Chinese pharmacopoeia. In our bioactive screening, we found out that the EtOH extract of R. palmatum inhibited hepatic stellate cell (HSC) activation by transforming growth factor β1 (TGF-β1). Chemical investigation of the EtOH extract led to the isolation of chrysophanol 8-O-glucoside, which was determined by structural analysis using NMR spectroscopic techniques and electrospray ionization mass spectrometry (ESIMS). To elucidate the effects of chrysophanol 8-O-glucoside on HSC activation, activated LX-2 cells were treated for 48 h with chrysophanol 8-O-glucoside, and α-SMA and collagen, HSC activation markers, were measured by comparative quantitative real-time PCR (qPCR) and western blotting analysis. Chrysophanol 8-O-glucoside significantly inhibited the protein and mRNA expression of α-SMA and collagen compared with that in TGF-β1-treated LX-2 cells. Next, the expression of phosphorylated SMAD2 (p-SMAD2) and p-STAT3 was measured and the translocation of p-STAT3 to the nucleus was analyzed by western blotting analysis. The expression of p-SMAD2 and p-STAT3 showed that chrysophanol 8-O-glucoside strongly downregulated STAT3 phosphorylation by inhibiting the nuclear translocation of p-STAT3, which is an important mechanism in HSC activation. Moreover, chrysophanol 8-O-glucoside suppressed the expression of p-p38, not that of p-JNK or p-Erk, which can activate STAT3 phosphorylation and inhibit MMP2 expression, the downstream target of STAT3 signaling. These findings provided experimental evidence concerning the hepatoprotective effects of chrysophanol 8-O-glucoside against liver damage and revealed the molecular basis underlying its anti-fibrotic effects through the blocking of HSC activation.     

Reusable and durable electrostatic air filter based on hybrid metallized microfibers decorated with metal-organic-framework nanocrystals

As global air pollution becomes increasingly severe,various types of fibrous filters have been devel-oped to improve air filter performance.However,fibrous filters have limitations such as high packing density that generally causes high-pressure drop and ultimately deterioration in the filtration effi-ciency.High-pressure particulate matter precipitators are limited in terms of scope for commercialization because they require high voltage supplies and ozone generators.In this study,we develop fibrous fil-ters with enhanced durability and improved performance using metallized microfibers decorated with metal-organic-framework(MOF)nanocrystals.Not only does the efficiency of the developed filters remain at or above 97％for 0.50-1.5 μm PMs but the durability also significantly increases.In addi-tion,using the water purification ability of the MOF,we explore the dye degradation effect of the hybrid microfibers by immersing them into Rhodamine B aqueous solution.In such an experiment the Rho-damine B aqueous solution is completely purified by the presence of the hybrid microfibers under the UV irradiation.     

Predictively encoded graph convolutional network for noise-robust skeleton-based action recognition

Applied Intelligence - In skeleton-based action recognition, graph convolutional networks (GCNs), which model human body skeletons using graphical components such as nodes and connections, have...     

真空缓冷铸渣机冷却炉渣选铜的研究

介绍了真空缓冷炉渣的工艺矿物学特性。试验研究结果表明，该炉渣属于中等可碎性偏难，硬度系数在８￣１６之间，在磨矿细度为－０．０１６ｍｍ占８９％时，粗、扫选抛尾粗精矿再磨再选，以Ｚ－２００、ＳＮ－９和丁胺为混合捕收剂，最终得到铜精矿产率为４．５９％，精矿含铜２３．４８％，含金５．８ｇ／ｔ，铜回收率为８３．７０％；尾矿含铜０．２２％，含金０．１８ｇ／ｔ。     

Modeling, rate-limiting step investigation, and enhancement of the direct bio-regeneration of perchlorate laden anion-exchange resin

Anion-exchange with high perchlorate affinity resins is one of the most promising technologies for removing low levels of perchlorate. However, the traditional brine desorption technique is difficult and costly for regeneration of this type of resin. Previously, a direct bio-regeneration method by contacting the spent high perchlorate affinity resin with the perchlorate-reducing bacteria was proved feasible. This research is a further study of that method. Firstly, a direct bio-regeneration process model, based on the physicochemical and biological fundamentals, was developed and calibrated with experimental data. Thereafter, the rate-limiting step in regeneration of the high perchlorate affinity resin was investigated. Methods to enhance the regeneration efficiency were developed. The results indicated that the calibrated model well described the regeneration process. It thus might provide useful insights into the regeneration system. The results also demonstrated that the perchlorate desorption from the loaded resin could be the rate-limiting step. Addition of proper amount of counter anions such as chloride and sulfate improved the regeneration efficiency because these anions could promote both the extent and rate of perchlorate desorption from the loaded resin. These findings aided us in achieving good and efficient regeneration of high perchlorate affinity resins like the A-530E and SR-7 resins. The findings also suggested that the application of bacteria that could efficiently reduce perchlorate in highly saline solution would make the method more promising for the regeneration of high perchlorate affinity resins.     

Membrane performance enhancer evaluations on pilot- and full-scale membrane bioreactors

Recently developed polymeric membrane performance enhancer product, MPE50, was tested in various pilot‐ and full‐scale membrane bioreactors (MBRs). The Initial MPE50 dosage was determined by visual jar tests and by using various bench‐top filtration tests. Different amounts of MPE50 were dosed, and the particle size and supernatant clarity of the mixed liquor were monitored visually. Bench‐top filtration tests were also conducted. A 50% higher MPE50 dosage is recommended to be added to the pilot/full‐scale bioreactors because, based on experience, some of the soluble microbial products in the mixed liquor do not completely react with polymer during the relatively short bench‐test mixing time interval. With the addition of 400 mg/L MPE50 to a pilot MBR, the design flow was increased twofold without any significant transmembrane pressure (TMP) increase for 1 day. The control TMP surged within a few hours without MPE50. Long‐term field trials in a full‐scale plant also showed a substantial flux increase. In addition to flux enhancement, MPE50 helped to remove foam from the bioreactors and improved plant aesthetics, safety and general operating performance.     

Cyclic behavior of prefabricated circular composite columns with low steel ratio

Improved economy and speed of construction can be achieved through the use of prefabricated structural members. As a step toward the advancement of prefabricated substructures, a precast composite column for seismic regions is proposed in this paper. Concrete-encased composite columns with core structural steel can be utilized for a fast construction method using steel connections. Six concrete-encased composite specimens with low steel ratio were fabricated. Quasi-static tests were conducted to investigate the cyclic response of the prefabricated composite columns. For composite columns with bolt connections, the cyclic behavior in terms of ultimate load and post-cracking behavior was enhanced significantly as the transverse reinforcement ratio increases. Higher prestressing gave greater flexural strength to the composite columns with prestressing and better energy absorption capacity, while displacement ductility of the prestressed composite column was decreased as the prestressing increased.