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21.
Elias Salomão Helou Sandra A. Santos Lucas E. A. Simões 《Journal of Optimization Theory and Applications》2017,175(1):137-157
The gradient sampling method is a recently developed tool for solving unconstrained nonsmooth optimization problems. Using just first-order information about the objective function, it generalizes the steepest descent method, one of the most classical methods for minimizing a smooth function. This study aims at determining under which circumstances one can expect the same local convergence result of the Cauchy method for the gradient sampling algorithm under the assumption that the problem is stated by a finite max-function around the optimal point. Additionally, at the end, we show how to practically accomplish the required hypotheses during the execution of the algorithm. 相似文献
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Eliana F. C. Simões João M. M. Leitão Joaquim C. G. Esteves da Silva 《Journal of fluorescence》2014,24(2):639-648
The quantification of nitric oxide (NO) based on the quenching of the fluorescence of a nanocomposites sensor constituted by cadmium/selenium quantum dots (CdSe) stabilized by chitosan (CS) and mercaptosuccinic acid (MSA) is assessed. The optimization of the response of the CS-CdSe-MSA nanocomposites to NO was done by multivariate response surface experimental design methodologies. The highest fluorescence quenching was obtained at pH 5.5 and at room temperature. The NO quantification capability of CS-CdSe-MSA was evaluated using standard solutions and a NO donor reagent. A large linear working range from 5 to 200 μM and a limit of detection of 1.86 μM were obtained. Better quantification results were obtained using the NO donor reagent. Besides NO, the response of the fluorescence of CS-CdSe-MSA to the main reactive oxygen and nitrogen species and similar NO compounds was also assessed. 相似文献
24.
Hyun Ook Seo Dae Han Kim Kwang-Dae Kim Eun Ji Park Chae Won Sim Young Dok Kim 《Adsorption》2013,19(6):1181-1187
Adsorption and desorption of toluene on bare and TiO2-coated silica with a mean pore size of 15 nm under dry and humid conditions were studied using toluene breakthrough curves and temperature programmed desorption (TPD) of toluene and CO2. Two TiO2/silica samples (either partially or fully covered with TiO2) were prepared with 50 and 200 cycles of TiO2 atomic layer deposition (ALD), respectively. The capacity of silica to adsorb toluene improved significantly with TiO2-thin film coating under dry conditions. However, toluene desorption from the surface due to displacement by water was more pronounced for TiO2-coated samples than bare samples under humid conditions. In TPD experiments, silica with a thinner TiO2 film (50-ALD cycled) had the highest reactivity for toluene oxidation to CO2 both in the absence and presence of water. Toluene adsorption and oxidation reactivity of silica can be controlled by modifying the silica surface with small amount of TiO2 using ALD. 相似文献
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Cristina García‐Simón Marc Garcia‐Borràs Dr. Laura Gómez Dr. Isaac Garcia‐Bosch Dr. Sílvia Osuna Prof. Marcel Swart Dr. Josep M. Luis Prof. Concepció Rovira Prof. Manuel Almeida Dr. Inhar Imaz Prof. Daniel Maspoch Dr. Miquel Costas Dr. Xavi Ribas 《Chemistry (Weinheim an der Bergstrasse, Germany)》2013,19(4):1445-1456
The metal‐directed supramolecular synthetic approach has paved the way for the development of functional nanosized molecules. In this work, we report the preparation of the new nanocapsule 3? (CF3SO3)8 with a A4B2 tetragonal prismatic geometry, where A corresponds to the dipalladium hexaazamacrocyclic complex Pd‐1 , and B corresponds to the tetraanionic form of palladium 5,10,15,20‐tetrakis(4‐carboxyphenyl)porphyrin ( 2 ). The large void space of the inner cavity and the supramolecular affinity for guest molecules towards porphyrin‐based hosts converts this nanoscale molecular 3D structure into a good candidate for host–guest chemistry. The interaction between this nanocage and different guest molecules has been studied by means of NMR, UV/Vis, ESI‐MS, and DOSY experiments, from which highly selective molecular recognition has been found for anionic, planar‐shaped π guests with association constants (Ka) higher than 109 M ?1, in front of non‐interacting aromatic neutral or cationic substrates. DFT theoretical calculations provided insights to further understand this strong interaction. Nanocage 3? (CF3SO3)8 can not only strongly host one single molecule of M(dithiolene)2 complexes (M=Au, Pt, Pd, and Ni), but also can finely tune their optical and redox properties. The very simple synthesis of both the supramolecular cage and the building blocks represents a step forward for the development of polyfunctional supramolecular nanovessels, which offer multiple applications as sensors or nanoreactors. 相似文献
26.
Suk-Ku Kang Hyun-Sung Cho Hyeong-Su Sim Beon-Kyu Kim 《Journal of carbohydrate chemistry》2013,32(6):807-812
Abstract In connection with our projects on the synthesis of biologically active 5-hydroxyalkan-4-olides which have a chiral 2.3-diol unit,1 we have carried out the synthesis of (4R,5S)-(?)- and (4R,5S)-(+)-L-factors (1).2 the proposed autoregulators from Streptomyees griseus, and muricatacin (2),3 a biologically active constituent from the seeds of Annona muricata L. via 2.3-dihydroxy aldehydes derived from D-glucose. Hex-3-enofuranose4 was prepared by the elimination of thetriflate derived from D-glucose. 相似文献
27.
Sim Woojeong Lee Booyeong Kim Dong Ju Lee Jeong A Kim Jaewon Chung Jintai 《Nonlinear dynamics》2022,108(2):987-1004
Nonlinear Dynamics - This study analyzes the vibro-impact behavior of two adjacent cantilever beams subjected to vibration generated by applying harmonic excitation to their rigid base. For the... 相似文献
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Svitlana V. Shishkina Igor V. Ukrainets Olga V. Vashchenko Natali I. Voloshchuk Pavlo S. Bondarenko Lidiya A. Petrushova Galina Sim 《Acta Crystallographica. Section C, Structural Chemistry》2020,76(1):69-74
The title benzothiazine‐3‐carboxamide, C17H16N2O4S, crystallized in two enantiomorphic crystal forms with the space groups P32 and P31 despite the absence of a classic stereogenic atom. The molecular structures are mirror images of each other. Only one sulfonyl O atom takes part in intramolecular hydrogen bonding as a proton acceptor and this atom is different in the two enantiomorphic structures. As a result, the S atom becomes a pseudo‐stereogenic centre. This fact is worth taking into account due to the different biological activities of the enantiomorphic forms. One form possesses a high analgesic activity, while the other form revealed a high anti‐inflammatory activity. 相似文献
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Howard Yi Fan Sim Jaslyn Ru Ting Chen Charlynn Sher Lin Koh Dr. Hiang Kwee Lee Dr. Xuemei Han Gia Chuong Phan-Quang Jing Yi Pang Dr. Chee Leng Lay Dr. Srikanth Pedireddy Dr. In Yee Phang Prof. Edwin Kok Lee Yeow Prof. Xing Yi Ling 《Angewandte Chemie (Weinheim an der Bergstrasse, Germany)》2020,132(39):17145-17151
The electrochemical nitrogen reduction reaction (NRR) offers a sustainable solution towards ammonia production but suffers poor reaction performance owing to preferential catalyst–H formation and the consequential hydrogen evolution reaction (HER). Now, the Pt/Au electrocatalyst d-band structure is electronically modified using zeolitic imidazole framework (ZIF) to achieve a Faradaic efficiency (FE) of >44 % with high ammonia yield rate of >161 μg mgcat−1 h−1 under ambient conditions. The strategy lowers electrocatalyst d-band position to weaken H adsorption and concurrently creates electron-deficient sites to kinetically drive NRR by promoting catalyst–N2 interaction. The ZIF coating on the electrocatalyst doubles as a hydrophobic layer to suppress HER, further improving FE by >44-fold compared to without ZIF (ca. 1 %). The Pt/Au-NZIF interaction is key to enable strong N2 adsorption over H atom. 相似文献