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81.
Mi-Hyun Lee Bhari Mallanna Nagaraja Prakash Natarajan Ngoc Thanh Truong Kwan Young Lee Sungho Yoon Kwang-Deog Jung 《Research on Chemical Intermediates》2016,42(1):123-140
PtSn/θ-Al2O3 catalysts with different amounts of K (0.14, 0.22, 0.49, 0.72, and 0.96 wt%) are prepared to investigate the K effects on the PtSn catalyst in propane dehydrogenation (PDH). KPtSn catalyst with 0.xx wt% K, 0.5 wt% Pt and 0.75 wt% Sn is designated as xx-KPtSn. PDH was performed at 873 K and a gas hourly space velocity (GHSV) of 53,000 mL/gcat h. The temperature-programmed desorption (NH3-TPD), temperature-programmed reduction (TPR) and CO chemisorption of the KPtSn catalysts with K added revealed the potassium addition blocked the acid sites, promoted the reduction of Sn oxide and decreased the Pt dispersion. The formations of cracking products and higher hydrocarbons on acid sites were suppressed by the K effect of blocking the acid sites. In contrast, K addition at more than 0.72 wt% rather increased cracking products and the amount of coke, resulting in the severe deactivation of catalysts. The high cracking products on the KPtSn catalysts with the high amount of K should not be related to the acid sites, because the acid sites were monotonously decreased with an increase in the amount of K. Instead, the potassium affected the characteristics of PtSn. The interaction between Pt and Sn could be weakened by enriching the reduced Sn, because the K component promoted the reduction of Sn oxide in the TPR experiments. Therefore, the 14-KPtSn catalyst with the low amount of K exhibits the highest stability and selectivity among the prepared KPtSn catalysts due to the compromise of the advantageous (blocking the acid sites) and bad (weakening the interaction between Pt and Sn) effects of the K addition in PDH. 相似文献
82.
A highly sensitive nanomechanical cantilever sensor assay based on an electrical measurement has been developed for detecting activated cyclic adenosine monophosphate (cyclic AMP)-dependent protein kinase (PKA). Employing a peptide derived from the heat-stable protein kinase inhibitor (PKI), a magnetic bead system was first selected as a vehicle to immobilize the PKI-(5-24) peptide for capturing PKA catalytic subunit and the activity assay was applied for indirectly assessing the binding. Synergistic interactions of adenosine triphosphate (ATP) and the peptide inhibitor with the kinase were then investigated by a solution phase capillary electrophoretic assay, and by surface plasmon resonance technology which involved immobilization of the peptide inhibitor. After systemically evaluated by a homogeneous direct binding assay, the ATP-dependent recognition of the catalytic subunit of PKA by PKI-(5-24) was successfully transferred on to the nanomechanical cantilevers at protein concentrations of 6.6 pM-66 nM, exhibiting much higher sensitivity and wider dynamic range than the conventional activity assay. Thus, direct assessment of activated kinases using the cantilever sensor system functionalized with specific peptide inhibitors holds great promise in analytical applications and clinical medicine. 相似文献
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86.
Won Seok Seo Youn Jaung Cho Sung Cheol Yoon Joon T. Park Younbong Park 《Journal of organometallic chemistry》2001,640(1-2):79-84
Reaction of ansa-cyclopentadienyl pyrrolyl ligand (C5H5)CH2(2-C4H3NH) (2) with Ti(NMe2)4 affords bis(dimethylamido)titanium complex [(η5-C5H4)CH2(2-C4H3N)]Ti(NMe2)2 (3) via amine elimination. A cyclopentadiene ligand with two pendant pyrrolyl arms, a mixture of 1,3- and 1,4-{CH2(2-C4H3NH)}2C5H4 (4), undergoes an analogous reaction with Ti(NMe2)4 to give [1,3-{CH2(2-C4H3N)}2(η5-C5H3)]Ti(NMe2) (5). Molecular structures of 3 and 5 have been determined by single crystal X-ray diffraction studies. 相似文献
87.
Hee-Man Yang Chan Woo Park Kune Woo Lee Byung-Sik Lee Ilgook Kim In-Ho Yoon 《Journal of Radioanalytical and Nuclear Chemistry》2018,316(3):955-962
A polyvinyl alcohol (PVA)-borate hydrogel-based strippable surface decontaminant containing an ammonium salt and Prussian blue (PB) was developed for the removal of 137Cs from various surfaces. This surface decontaminant can be easily prepared by the simple mixing of commercially available materials, such as PVA, borax, NH4Cl and PB, in water, and the decontaminant can be peeled off surfaces due to its high elastic property after surface decontamination. The hydrogel displayed an effective removal performance for Cs from painted cement, aluminum, stainless steel, and cement surfaces and a potential for reusability. Therefore, the PB/PVA-borate hydrogel has good potential as a new surface decontaminant. 相似文献
88.
Dr. Xingshu Li Nahyun Kwon Tian Guo Prof. Zhuang Liu Prof. Juyoung Yoon 《Angewandte Chemie (International ed. in English)》2018,57(36):11522-11531
Despite its clinical promise, photodynamic therapy (PDT) suffers from a key drawback associated with its oxygen‐dependent nature, which limits its effective use against hypoxic tumors. Moreover, both PDT‐mediated oxygen consumption and microvascular damage further increase tumor hypoxia and, thus, impede therapeutic outcomes. In recent years, numerous investigations have focused on strategies for overcoming this drawback of PDT. These efforts, which are summarized in this review, have produced many innovative methods to avoid the limits of PDT associated with hypoxia. 相似文献
89.
Kie Yong Cho Hyun-Ji Kim Xuan Huy Do Jin Young Seo Jae-Woo Choi Sang-Hyup Lee Ho Gyu Yoon Seung Sang Hwang Kyung-Youl Baek 《Research on Chemical Intermediates》2018,44(8):4663-4684
Two series of water-soluble metalloporphyrin-cored amphiphilic star block copolymers were synthesized by controlled radical polymerizations such as atom transfer radical polymerization (ATRP) and reversible addition fragmentation chain transfer (RAFT), which gave eight amphiphilic block copolymer arm chains consisting of poly(n-butyl acrylate-b-poly(ethylene glycol) methyl ether methacylate) (PnBA-b-PEGMEMA, Mn,GPC = 78,000, Mw/Mn = 1.2, 70 wt% of PPEGMEMA) and poly(styrene-b-2-dimethylamino ethyl acrylate) (PS-b-PDMAEA, Mn,GPC = 83,000, Mw/Mn = 1.2, 67 wt% of PDMAEA), yielding porphyrin(Pd)-(PnBA-b-PPEGMEMA)8 and porphyrin(Pd)-(PS-b-PDMAEA)8, respectively. Obtained metalloporphyrin polymer photocatalysts were homogeneously solubilized in water to apply to the removal of chlorophenols in water, and was distinguished from conventional water-insoluble small molecular metalloporphyrin photocatalysts. Notably, we found that the water-soluble star block copolymers with hydrophobic–hydrophilic core–shell structures more effectively decomposed the chlorophenol, 2,4,6-trichlorophenol (2,4,6-TCP), in water under visible light irradiation (k = 1.39 h?1, t1/2 = 0.5 h) in comparison to the corresponding water-soluble star homopolymer, because the hydrophobic core near the metalloporphyrin effectively captured and decomposed the hydrophobic chlorophenols in water. 相似文献
90.
[reaction: see text]. We have demonstrated that a dicobalt octacarbonyl catalyzed double [2 + 2 + 1] carbonylative cycloaddition reaction of triyne can be carried out to yield a novel 5.5.5.6 tetracyclic di-enone system. 相似文献