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81.
Todd W. Hudnall 《Journal of fluorine chemistry》2010,131(11):1182-1186
4-Chloro-4-phenyl-1,3,5,7,8-pentamethyl-3a,4a-diaza-4-bora-s-indacene (2) has been synthesized, structurally characterized and converted into the corresponding hydroxide derivative 4-hydroxo-4-phenyl-1,3,5,7,8-pentamethyl-3a,4a-diaza-4-bora-s-indacene (3). This boron hydroxide derivative reacts with fluoride anions under acidic conditions to afford the corresponding fluoride derivative 4-fluoro-4-phenyl-1,3,5,7,8-pentamethyl-3a,4a-diaza-4-bora-s-indacene (4). This simple reaction may become useful for the incorporation of [18F]-fluoride and may serve for the preparation of radiolabeled BODIPY derivatives. 相似文献
82.
Three-dimensionally ordered macroporous (3DOM) monoclinic InVO4 and its supported chromia (yCrOx/3DOM InVO4, y denotes as the weight percentage of Cr2O3, y = 5, 10, 15, and 20 wt%) photocatalysts were fabricated using the ascorbic acid-assisted polymethyl methacrylate-templating and incipient wetness impregnation methods, respectively. Physicochemical properties of the materials were characterized by means of a number of analytical techniques. Photocatalytic activities of the samples were evaluated for the degradation of rhodamine B (RhB) in the presence of H2O2 under visible-light illumination. Compared to 3DOM InVO4 and 15CrOx/bulk InVO4, yCrOx/3DOM InVO4 showed much better visible-light-driven photocatalytic performance for RhB degradation, with the 15CrOx/3DOM InVO4 sample performing the best. It is concluded that the CrOx loading, higher surface area and surface oxygen vacancy density and lower bandgap energy as well as the better quality of 3DOM structure were responsible for the good photocatalytic performance of 15CrOx/3DOM InVO4 for the degradation of RhB. 相似文献
83.
84.
Juan J. Ferreiro Jose G. de la Campa Angel E. Lozano Javier de Abajo 《Journal of polymer science. Part A, Polymer chemistry》2005,43(21):5300-5311
A set of novel aromatic polyamides containing pyridine pendent groups was prepared from aromatic diamines and new monomers that are 5‐substituted derivatives of isophthalic acid bearing nicotinamide, isonicotinamide, or picolinamide groups. The polymers were obtained in high yield and high molecular weight by the phosphorylation method of polycondensation. They were characterized by spectroscopic and chromatographic methods and several of their properties were investigated. All of the polymers were soluble in polar aprotic solvents and gave films of good mechanical properties. Glass transition temperatures were higher than that of the reference polymer, poly(m‐phenyleneisophthalamide) (IP‐MPD), while the thermal resistance, defined by the initial decomposition temperature observed by thermogravimetry, was in the range 370–420 °C, lower by 30–70 °C than that of IP‐MPD. The presence of a pendent pyridine group and an additional amide side group per repeat unit made the polymers essentially amorphous and greatly improved their abilities to absorb water in comparison with nonsubstituted polyamides. Water uptake values up to 15% were observed at 65% relative humidity. © 2005 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 43: 5300–5311, 2005 相似文献
85.
本文合成了四种新配合物:二氯化双苯甲醛缩氮基硫脲合铜(Ⅱ)(Cu~Ⅱ(Betsc—H)_2Cl_2),三氯化水杨醛缩氨基硫脲合铁(Ⅲ)(Fe~Ⅲ(Satsc—H_2)Cl_3,二氯化双对二甲氨基苯甲醛缩氨基硫脲合钴(Ⅱ)(Co~Ⅱ(Dmabtsc—H)_2Cl_2·H_2O)及双对硝基苯甲醛缩氨基硫脲合钴(Ⅱ)醋酸盐(Co~Ⅱ(Nitsc—H)(Nitsc)(Ac))。用元素分析和IR测定了化合物的组成,并进行了吸放O_2和CO的试验。 相似文献
86.
87.
Salman M. Saadeh Nizam M. El‐Ashgar Issa M. El‐Nahhal Mohamed M. Chehimi Jocelyne Maquet Florence Babonneau 《应用有机金属化学》2005,19(6):759-767
A porous, solid insoluble polysiloxane‐immobilized ligand system bearing pyrogallol active sites of the general formula P? (CH2)3? NH(CH2)3OC6H3(OH)2 (where P represents [Si? O]n siloxane network) has been prepared by the reaction of 3‐aminopropylpolysiloxane with 1,3‐dibromopropane followed by the reaction with pyrogallol. 13C CP‐MAS NMR and X‐ray photoelectron spectroscopy confirmed that the pyrogallol is chemically bonded to the siloxane backbone. Thermal analysis showed that the ligand system is stable under nitrogen at relatively high temperature. The polysiloxane–pyrogallol ligand system exhibits high potential for the uptake of the metal ions (Fe3+, Co2+, Ni2+ and Cu2+). Complexation of the pyrogallol ligand system for the metal ions at the optimum conditions was found to be in the order Fe3+ > Cu2+ > Ni2+ > Co2+. Copyright © 2005 John Wiley & Sons, Ltd. 相似文献
88.
本文研究了激光染料Coumarin-480,Oxazine-720,Oxazine-725在聚乙二醇介质中的荧光光谱。结果表明荧光光强度随着聚乙二醇浓度的不断增大而增强,荧光发射的最大峰位有较明显的红移,表明染料分子与聚乙二醇分子间形成了分子缔合物,缔合物愈稳定,荧光强度增强愈大,红移愈大。 相似文献
89.
A one-dimensional approximate analytical model, which preserves the main features of soil-crop-atmospheric hydrodynamics,
has been suggested for plant roots of low soil-root conductivity ratio (SRCR). The proposed approach involves physically based
concepts, such as mass balance equation, Darcy’s law, and related water uptake and plant transpiration functions. Two main
assumptions have been made to derive the analytical solution: (1) gravitational flow is adopted and (2) the uniform soil moisture
distribution within the root water activity zone is supposed. The mass balance equation in its integral form is solved by
the method of characteristics. This leads to the two functional equations for soil pressure head and root potential, which
can be solved simultaneously by using common software. The model has been further verified against the numerical one. The
model represents a reasonable compromise between the complicated mechanism of unsaturated water flow with root water uptake
(RWU) and still insufficient knowledge of the soil-plant-atmospheric continuum. It is able to account for temporal fluctuations
in root activity zone and provides a relatively simple algorithm for investigation of RWU-mechanism. Besides the theoretical
and applicative importance, this flow model yields water and velocity distributions within soil profile, and, thereby, constitutes
a preliminary step toward solution of contaminant transport problems in vadose zone.
Deceased 相似文献
90.
Nitrogen uptake of nickel free austenitic stainless steel powder during heat treatment—an XPS study 下载免费PDF全文
Anna Weddeling Kathrin Lefor Eduard Hryha Stephan Huth Lars Nyborg Sebastian Weber Werner Theisen 《Surface and interface analysis : SIA》2015,47(3):413-422
In austenitic stainless steel nitrogen stabilizes the austenitic phase, improves the mechanical properties and increases the corrosion resistance. Nitrogen alloying enables to produce austenitic steels without the element nickel which is high priced and classified as allergy inducing. A novel production route is nitrogen alloying of CrMn‐prealloyed steel powder via the gas phase. This is beneficial as the nitrogen content can be adjusted above the amount that is reached during conventional casting. A problem which has to be overcome is the oxide layer present on the powder surface which impedes both the sintering process and the uptake of nitrogen. This study focuses on whether heat treatment under pure nitrogen is an appropriate procedure to enable sintering and nitrogen uptake by reduction of surface oxides. X‐ray photoelectron spectroscopy (XPS) in combination with scanning electron microscopy (SEM) and energy dispersive X‐ray spectrometry (EDS) are used to investigate the surface of powdered FeMn19Cr17C0.4N heat treated under nitrogen atmosphere. The analyses showed reduction of iron oxides already at 500 °C leading to oxide‐free metallic surface zones. Mn and Cr oxides are reduced at higher temperatures. Distinct nitrogen uptake was registered, and successful subsequent sintering was reached. Copyright © 2014 John Wiley & Sons, Ltd. 相似文献