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11.
We report Raman scattering from the boehmite,γ-, δ- andα-phases of the alumina gel. Samples are characterized by transmission and scanning electron microscopy, X-ray diffraction
and density measurements. The main Raman line in the boehmite phase is red-shifted as well as asymmetrically broadened with
respect to that in the crystalline boehmite, signifying the nanocrystalline nature of the gel. Raman signatures are absent
in theγ- andδ-phases due to the disorder in cation vacancies. We also show that low frequency Raman scattering from the boehmite phase
resembles that from a fractal network, characterized in terms of fraction dimension
. Taking Hausdorff dimension D of the boehmite gel to be 2.5 (or 3.0), the value of
is 1.33±0.02 (or 1.44±0.02), which is close to the theoretically predicted value of 4/3. 相似文献
12.
The formation constants (logK
MAL
MA
) of the complexes of the type (UO2.A.L] (whereA = IMDA, NTA or EDTA;L = catechol, resorcinol, phloroglucinol, pyrogallol, β-resorcylic acid or protocatechuic acid) have been determined potentiometrically
at 25°C and ionic strength,I = 0·2 (mol dm−3, NaClO4) using the Irving-Rossotti approach. The formation constants of the binary complexes (logK
KMA
KM
) have been found to lie in the sequence IMDA < NTA < EDTA, whereas those for the mixed ligand complexes (logK
MAL
MA
) follow the reverse sequence, IMDA > NTA > EDTA. due to the electrostatic effect. 相似文献
13.
Anushree Purushottam Khandale Shyam Shashibhushan Bhoga 《Journal of Solid State Electrochemistry》2012,16(1):341-352
The solid solubility limit of Ce in Nd2–x
Ce
x
CuO4 ± δ
, prepared by sol–gel process, is established up to x = 0.2. The transition from negative temperature coefficient to positive temperature coefficient, within the solid solubility
region, is observed at 620 °C. The area-specific-resistance (ASR) is optimized for electrochemical cell sintered at 800 °C.
ASR enhances with increase in sintering temperature of cell. ASR value of 0.93 ohm cm2 at 700 °C, determined by electrochemical impedance spectroscopy is comparable against that by voltage versus current (V–I)
characteristics at 0.98 ohm cm2 at the same temperature. Electrochemical performance and ASR of Nd1.8Ce0.2CuO4 ± δ
is improved when prepared by sol–gel route over solid-state reaction, which is attributed to uniform size and shape of nanocrystalline
grains. 相似文献
14.
15.
Anushree Das Suma S. Thomas August A. Garofoli Kevin A. Chavez Jeanette A. Krause Cornelia Bohne Anna D. Gudmundsdottir 《Photochemistry and photobiology》2019,95(1):154-162
Laser flash photolysis of ketone 1 in argon‐saturated methanol yields triplet biradical 1BR (τ = 63 ns) that intersystem crosses to form photoenols Z‐1P (λmax = 350 nm, τ ~ 10 μs) and E‐1P (λmax = 350 nm, τ > 6 ms). The activation barrier for Z‐1P re‐forming ketone 1 through a 1,5‐H shift was determined as 7.7 ± 0.3 kcal mol?1. In contrast, for ketone 2, which has a less sterically hindered carbonyl moiety, laser flash photolysis in argon‐saturated methanol revealed the formation of biradical 2BR (λmax = 330 nm, τ ~ 303 ns) that intersystem crosses to form photoenol E‐2P (λmax = 350 nm, τ > 42 μs), but photoenol Z‐2P was not detected. However, in more viscous basic H‐bond acceptor (BHA) solvent, such as hexamethylphosphoramide, triplet 2BR intersystem crosses to form both Z‐2P (λmax = 370 nm, τ ~ 1.5 μs) and E‐2P. Thus, laser flash photolysis of ketone 2 in methanol reveals that intersystem crossing from 2BR to form Z‐2P is slower than the 1,5‐H shift of Z‐2P, whereas in viscous BHA solvents, the 1,5‐H shift becomes slower than the intersystem crossing from 2BR to Z‐2P. Density functional theory and coupled cluster calculations were performed to support the reaction mechanisms for photoenolization of ketones 1 and 2 . 相似文献
16.
Catalyst‐Free Convergent Approach for the Synthesis of Spiro[imidazo[2,1‐b][1,3]oxazine‐7,3′‐indoline
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I. R. Siddiqui Anushree Srivastava Pragati Rai Arjita Srivastava Anjali Srivastava 《Journal of heterocyclic chemistry》2015,52(5):1415-1420
Strategies to address mounting environmental concerns with current approaches include an operationally simple and highly efficient one‐pot three‐component approach for the synthesis of spiro[imidazo[2,1‐b][1,3]oxazine‐7,3′‐indoline derivatives, which has been developed via Huisgen zwitter ion intermediate. The significant advantages of this protocol are short reaction time, excellent yields, and facile formation of three new bonds in one operation from easily available starting materials. 相似文献
17.
We have devised an expedient, cleaner, and environmentally friendly approach for ‘on water’ mediated synthesis of imidazo[1,2-a]pyridine derivatives. The synthesis involves in situ formation of imines followed by addition of alkyne to give the desired products in excellent yield. 相似文献
18.
19.
Here we review our work on measurement of the Casimir force between a large aluminum coated a sphere and flat plate using
an atomic force microscope. The average statistical precision is 1% of the force measured at the closest separation. We have
also shown nontrival boundary dependence of the Casimir force. 相似文献
20.
Max Levy John R. Bertram Kristen A. Eller Anushree Chatterjee Prashant Nagpal 《Angewandte Chemie (Weinheim an der Bergstrasse, Germany)》2019,131(33):11536-11540
The emergence of multidrug‐resistant (MDR) pathogens represents one of the most urgent global public health crises. Light‐activated quantum dots (QDs) are alternative antimicrobials, with efficient transport, low cost, and therapeutic efficacy, and they can act as antibiotic potentiators, with a mechanism of action orthogonal to small‐molecule drugs. Furthermore, light‐activation enhances control over the spatiotemporal release and dose of the therapeutic superoxide radicals from QDs. However, the limited deep‐tissue penetration of visible light needed for QD activation, and concern over trace heavy metals, have prevented further translation. Herein, we report two indium phosphide (InP) QDs that operate in the near‐infrared and deep‐red light window, enabling deeper tissue penetration. These heavy‐metal‐free QDs eliminate MDR pathogenic bacteria, while remaining non‐toxic to host human cells. This work provides a pathway for advancing QD nanotherapeutics to combat MDR superbugs. 相似文献