Search

Polymer electrolytes with bicontinuous nanostructures for lithium metal batteries were prepared by UV-polymerization of hydrophobic domains in microemulsions of ionic liquids, amphiphilic ionic liquids, lithium salts and monomers.

A Cu(OAc)2-catalyzed reaction of α,β-unsaturated N-tosylhydrazones with diaryliodonium salts to give N-arylpyrazoles and an extra diaryl sulfone has been developed. This reaction took full advantage of the “waste” part of substrates to give an extra and valuable product.

Herein, a [3+2] cycloaddition of aza-oxyallylic cations with ethynylbenziodoxolones for synthesis of new λ3 -iodanes containing spirocyclic 4-oxazolidinone has been developed. This cyclic λ3 -iodanes display stability in air and excellent solubility in organic solvent. Using them as substrate, both the 4,1-benzoxazepine-2,5-diones and symmetrical 1,3-diynes derivatives were afforded in high yield under copper(I)-catalyzed conditions.

Self-powered deep-ultraviolet photodetectors have received considerable attention in recent years because of their efficiency, reliability, and various applications in civilian and military fields. Herein, a Ag/Ag

Background With the occurrence of a number of major disasters around the world, there is growing interest in chemical disaster medicine. In South Korea, there is a training program for mass casualty incidents (MCI) and backup by legal regulations by the Framework Act on the Management of Disasters and Safety. However, there is no program focusing on chemical disasters. Thus, the authors newly created a program, the Chemical-Mass Casualty Incident Response Education Module (C-MCIREM) in September 2019. This was a pilot study to verify the educational effect of the program. Method A pre/post study was conducted of a chemical MCI training program based on simulation. A total of 25 representative and qualified participants were recruited from fire departments, administrative staff of public health centers, and healthcare workers of hospitals in the Gyeonggi-do province of South Korea. They participated in a one-day training program. A knowledge test and confidence survey were provided to participants just before training, and again immediately following the training online. The authors compared improvements of pre/post-test results. In the tabletop drill exercise, quantified qualitative analyses were used to measure the educational effect on the participants. Results In the knowledge test, the mean (standard deviation) scores for all 25 participants at baseline and after training were 41.72 (15.186) and 77.96 (11.227), respectively (p

A catalyst-free, base-mediated N-sec-alkylation of amides by reaction of sulfonylindoles and α-halohydroxamates has been developed. The N-sec-alkylation of amides reaction is based on an intermolecular nucleophilic addition of vinylogous imine with N-(benzyl­oxy)meth-acrylamide/azaoxyallyl cations formed in situ and represents a simple way to give polyfunctionalized 3-indolyl methanamines in good to excellent yields.

Silicon Carbide (SiC)-based devices have been proposed to replace conventional silicon-based devices based on their physical properties and have become an active research topic. Several studies have reported a high breakdown voltage in SiC-powered devices in the implanted limited field ring structure. However, the problems of ion-implanted edge termination in field-limited rings appear to be associated with the ion implantation process, such as damage to the grid and leakage current increases due to ion implantation. In this paper, SiC Schottky Barrier Diode (SBD) Floating Metal Ring (FMR) edge-termination structures are produced regardless of whether we are using ion implantation and proceed with the breakdown voltage comparison. The experimental method for producing an SiC SBD after FMR structural design through a simulation was performed with a comparative analysis of the breakdown voltage with No-FMR and FMR. We measured the breakdown voltage of the fabricated No-FMR and FMR, and the results confirmed that FMR SiC SBD was approximately 35% higher than the breakdown voltage No-FMR. It was confirmed that the breakdown voltage increased due to the balancing effect of the electric field structure of FMR.

β-Ga2O3 Schottky barrier diodes (SBDs) were demonstrated with Ni Schottky contact deposited by the confined magnetic field-based sputtering (CMFS) method. A shallow interfacial layer was formed by the diffusion of Ni into β-Ga2O3 after post-annealing treatment, which significantly influenced the electrical performance of the CMFS-Ni/β-Ga2O3 SBDs. The CMFS method was used to vary the Schottky barrier height and the ideality factor from 0.84 to 1.33 eV and 1.20 to 1.04, respectively. The leakage current of the CMFS-SBDs was only 10% of the leakage current using E-beam Ni-based SBDs, and the thermal stability of the CMFS-SBDs also was much higher than that of the E-beam Ni SBDs. We confirmed that the effective diffusion of Ni atoms could substitute for Ga through the activation of the β-Ga2O3 with CMFS.

This work describes the wire arc additive manufacturing (WAAM) approach used to fabricate parts from wear-resistant steel. The microstructure, crystal structures, and mechanical properties of the resulting samples were thoroughly analyzed. The wear-resistant steel parts demonstrated good forming, no internal defects, good metallurgical bonding, and excellent wear resistance. The metallographic analysis confirmed that the main phase was ferrite. The microhardness of the sample along its cross section was uniform in both horizontal and vertical directions and equals to 464.7HV0.2 and 482.4 HV0.2, respectively. The average values of tensile strength, elongation ratio, and room temperature Charpy shock were equal to 945.3 MPa, 4.3%, and 5 J, respectively.

Herein, a [3+2] cycloaddition of aza-oxyallylic cations with ethynylbenziodoxolones for synthesis of new λ

Airborne microbial communities include a significant number of uncultured and poorly characterized bacteria. No effective method currently exists to evaluate the health risks of such complex bacterial populations, particularly for pneumonia.We developed a method to evaluate risks from airborne microorganisms, guided by the principle that closer evolutionary relationships reflect similar biological characteristics, and thus used 16S rDNA sequences of 10 common pneumonia-related bacterial pathogens. We calculated a risk of breath-related (We suggested applying

A three-component reaction of β,γ-unsaturated α-keto esters, proline, and dialkyl maleates has been developed. This reaction provides pyrrolizidine derivatives containing three ester groups and a styrenyl group, as well as a quaternary center, in moderate to good yields and with good to excellent diastereoselectivities.

The hard X-ray free-electron laser at the Pohang Accelerator Laboratory (PAL-XFEL) in the Republic of Korea achieved saturation of a 0.144 nm free-electron laser beam on 27 November 2016, making it the third hard X-ray free-electron laser in the world, following the demonstrations of the Linac Coherent Light Source (LCLS) and the SPring-8 Angstrom Compact Free Electron Laser (SACLA). The use of electron-beam-based alignment incorporating undulator radiation spectrum analysis has allowed reliable operation of PAL-XFEL with unprecedented temporal stability and dispersion-free orbits. In particular, a timing jitter of just 20 fs for the free-electron laser photon beam is consistently achieved due to the use of a state-of-the-art design of the electron linear accelerator and electron-beam-based alignment. The low timing jitter of the electron beam makes it possible to observe Bi(111) phonon dynamics without the need for timing-jitter correction, indicating that PAL-XFEL will be an extremely useful tool for hard X-ray time-resolved experiments. The Pohang Accelerator Laboratory X-ray Free Electron Laser (PAL-XFEL) in South Korea has now entered operation with a timing jitter of just 20 fs.

A metal-free cyclopropanation of electron-deficient olefins 3-substituted-2-cyanoacrylamides with N-tosylhydrazones has been successfully developed. This strategy provide a simple route to the synthesis of very valuable 1-cyanocyclopropanecarboxamides with a quaternary stereogenic center in good yields and with high diastereoselectivities (up to 90% yield with 19:1 dr). The reaction could be performed in one-pot fashion and in a gram-scale from aryl aldehydes.

Cryptophycin-52 (CR52), a tubulin inhibitor, exhibits promising antitumor activity in vitro (picomolar level) and in mouse xenograft models. However, the narrow therapeutic window in clinical trials limits its further development. Antibody-drug conjugate (ADC), formed by coupling cytotoxic compound (payload) to an antibody via a linker, can deliver drug to tumor locations in a targeted manner by antibody, enhancing the therapeutic effects and reducing toxic and side effects. In this study, we aim to explore the possibility of CR52-based ADC for tumor targeted therapy. Due to the lack of a coupling site in CR52, its prodrug cryptophycin-55 (CR55) containing a free hydroxyl was synthesized and conjugated to the model antibody trastuzumab (anti-HER2 antibody drug approved by FDA for breast cancer therapy) via the linkers based on Mc-NHS and Mc-Val-Cit-PAB-PNP. The average drug-to-antibody ratios (DARs) of trastuzumab-CR55 conjugates (named T-L1-CR55, T-L2-CR55, and T-L3-CR55) were 3.50, 3.29, and 3.35, respectively. These conjugates exhibited potent cytotoxicity in HER2-positive tumor cell lines with IC50 values at low nanomolar levels (0.58–1.19 nM). Further, they displayed significant antitumor activities at the doses of 10 mg/kg in established ovarian cancer (SKOV3) and gastric cancer (NCI–N87) xenograft models without overt toxicities. Finally, the drug releases were analyzed and the results indicated that T-L3-CR55 was able to effectively release CR55 and further epoxidized to CR52, which may be responsible for its best performance in antitumor activities. In conclusion, our results demonstrated that these conjugates have the potential for tumor targeted therapy, which provides insights to further research the CR55/CR52-based ADC for tumor therapy.

The covalently modified ureido-conjugated chitosan/TPP multifunctional nanoparticles have been developed as targeted nanomedicine delivery system for eradication of Helicobacter pylori. H. pylori can specifically express the urea transport protein on its membrane to transport urea into cytoplasm for urease to produce ammonia, which protects the bacterium in the acid milieu of stomach. The clinical applicability of topical antimicrobial agent is needed to eradicate H. pylori in the infected fundal area. In this study, we designed and synthesized two ureido-conjugated chitosan derivatives UCCs-1 and UCCs-2 for preparation of multifunctional nanoparticles. The process was optimized in order to prepare UCCs/TPP nanoparticles for encapsulation of amoxicillin. The results showed that the amoxicillin-UCCs/TPP nanoparticles exhibited favorable pH-sensitive characteristics, which could procrastinate the release of amoxicillin at gastric acids and enable the drug to deliver and target to H. pylori at its survival region effectively. Compared with unmodified amoxicillin-chitosan/TPP nanoparticles, a more specific and effective H. pylori growth inhibition was observed for amoxicillin-UCCs/TPP nanoparticles. Drug uptake analysis tested by flow cytometry and confocal laser scanning microscopy verified that the uptake of FITC-UCCs-2/TPP nanoparticles was associated with urea transport protein on the membrane of H. pylori and reduced with the addition of urea as competitive transport substrate. These findings suggest that the multifunctional amoxicillin-loaded nanoparticles have great potential for effective therapy of H. pylori infection. They may also serve as pharmacologically effective nanocarriers for oral targeted delivery of other therapeutic drugs to treat H. pylori.

The Pohang Accelerator Laboratory X-ray Free Electron Laser project, a new worldwide-user facility to deliver ultrashort, laser-like x-ray photon pulses, will begin user operation in 2017 after one year of commissioning. Initially, it will provide two beamlines for hard and soft x-rays, respectively, and two experimental end-stations for the hard x-ray beamline will be constructed by the end of 2015. This article introduces one of the two hard x-ray end-stations, which is for hard x-ray pump-probe experiments, and primarily outlines the overall design of this end-station and its critical components. The content of this article will provide useful guidelines for the planning of experiments conducted at the new facility.

A new metal-free, ring-expansion reaction of six-membered N-sulfonylimines with unstable diazomethanes, generated in situ from the N-tosylhydrazones, has been developed. This reaction delivers valuable seven-membered enesulfonamides by a Tiffeneau-Demjanov rearrangement and intramolecular proton transfer tautomerization process. Moreover, this ring-expansion reaction can be carried out in a one-pot fashion and scaled up to the gram scale by using aryl aldehydes, without the need to isolate the N-tosylhydrazone.

Bidding and contract systems are used for public construction projects to select contractors following fair competition principles and to execute national budgets effectively. Many challenges have arisen due to a lack of transparency and fairness and because bidding practices have been luck-based. Few comprehensive or comparative analyses have been conducted on the performance and limitations of bidding and contract systems, and empirical analyses designed to improve policies on and the practice of such systems are lacking. This study empirically analyzed current bidding and contract systems to seek ways of improving them. The study proposes several alternatives to resolve the problems with and irrationalities of the current system: 1) improving bidding and selection systems by changing them from a luck-based price competition into a technical merit- and value-based competition; 2) improving the assessment criteria to meet the current market level of bid and winning prices; 3) adjusting contractual responsibilities and sharing structures to meet the current trend; and 4) strengthening the competitiveness and expanding the social responsibility-based procurement systems of construction companies.

Construction cost index (CCI) has been published for last 10 years, it`s contributed to update the historical cost data, analysis cost fluctuation and evaluate the market price for construction works with direct or indirect manner. CCI is a secondary or processed statistics using the basic statistics of input output table (IO table) and producer price index (PPI) from the Bank of Korea (BOK). So once the basic statistics change, it is required to modify the calculating model of CCI. Recently the BOK changed some fundamental principles and the base year (from 2005 to 2010), that can be used in IO table and PPI. This research analyzed the recent revision of basic statistics and their impacts on CCI, and improved the previous CCI model in response to it. Also the validity of new CCI was verified by analyzing the items and weights utilized in CCI and comparing the related index.