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961.
Aybüke A. ?sbir-Turan Emine K?l?? Zafer üstünda? Haslet Ek?i Ali Osman Solak Betül Zorer 《Journal of Solid State Electrochemistry》2012,16(1):235-245
The goal of this study was to prepare novel glassy carbon electrode surfaces using two similar bis-diazonium salts, 3,8-benzo[c]cinnoline (3,8-BCC-BDAS) and 3,8-benzo[c]cinnoline 5-oxide (3,8-BCCNO-BDAS) at the glassy carbon (GC) surface. These diazonium salts were reduced electrochemically
and covalently electrografted onto the glassy carbon electrode surface to form modified electrodes. Electrochemical reduction
of 3,8-BCC-BDAS and 3,8-BCCNO-BDAS salts on the electrode surface yielded a compact and stable film. The existence of BCC
moieties on the GC surface was characterized by X-ray photoelectron spectroscopy, reflectance-adsorption infrared spectroscopy,
cyclic voltammetry, ellipsometry, and electrochemical impedance spectroscopy. The stability and working potential range of
the novel modified electrodes were also studied. The possibility of analytical application of these novel surfaces for inorganic
cations and especially selectivity to copper ions was investigated. 3,8-diaminobenzo[c]cinnoline (3,8-DABCC) and its 5-oxide derivative (3,8-DABCCNO) were synthesized from the reductive cyclization of 2,2′-dinitrobenzidine
and prepared their bisdiazonium salts via the tetrazotization reactions of the diamines with NaNO2. The structures of 3,8-DABCC and 3,8-DABCCNO and their corresponding bisdiazonium salts are confirmed by spectral analysis. 相似文献
962.
963.
Yamada M Yao I Hayasaka T Ushijima M Matsuura M Takada H Shikata N Setou M Kwon AH Ito S 《Analytical and bioanalytical chemistry》2012,402(5):1921-1930
Direct tissue analysis using matrix-assisted laser desorption/ionization (MALDI) mass spectrometry (MS) provides the means
for in situ molecular analysis of a wide variety of biomolecules. This technology—known as imaging mass spectrometry (IMS)—allows
the measurement of biomolecules in their native biological environments without the need for target-specific reagents such
as antibodies. In this study, we applied the IMS technique to formalin-fixed paraffin-embedded samples to identify a substance(s)
responsible for the intestinal obstruction caused by an unidentified foreign body. In advance of IMS analysis, some pretreatments
were applied. After the deparaffinization of sections, samples were subjected to enzyme digestion. The sections co-crystallized
with matrix were desorbed and ionized by a laser pulse with scanning. A combination of α-amylase digestion and the 2,5-dihydroxybenzoic
acid matrix gave the best mass spectrum. With the IMS Convolution software which we developed, we could automatically extract
meaningful signals from the IMS datasets. The representative peak values were m/z 1,013, 1,175, 1,337, 1,499, 1,661, 1,823, and 1,985. Thus, it was revealed that the material was polymer with a 162-Da unit
size, calculated from the even intervals. In comparison with the mass spectra of the histopathological specimen and authentic
materials, the main component coincided with amylopectin rather than amylose. Tandem MS analysis proved that the main components
were oligosaccharides. Finally, we confirmed the identification of amylopectin by staining with periodic acid-Schiff and iodine.
These results for the first time show the advantages of MALDI-IMS in combination with enzyme digestion for the direct analysis
of oligosaccharides as a major component of histopathological samples. 相似文献
964.
965.
Annia?GalanoEmail author Juan?Raúl?Alvarez-IdaboyEmail author Misaela?Francisco-Márquez Manuel?E.?Medina 《Theoretical chemistry accounts》2012,131(3):1173
The free radical scavenging activity of hydroxytyrosol (HTyr) and tyrosol (Tyr) has been studied in aqueous and lipid solutions,
using the density functional theory. Four mechanisms of reaction have been considered: single electron transfer (SET), sequential
electron proton transfer (SEPT), hydrogen transfer (HT), and radical adduct formation. It was found that while SET and SEPT
do not contribute to the overall reactivity of HTyr and Tyr toward ·OOH and ·OCH3 radicals, they can be important for their reactions with ·OH, ·OCCl3, and ·OOCCl3. The ·OOH-scavenging activity of HTyr and Tyr was found to take place exclusively by HT, and it is also predicted to be the main
mechanism for their reactions with ·OCH3. HT is proposed as the main mechanism for the scavenging activity of HTyr and Tyr when reacting with other ·OR and ·OOR radicals, provided that R is an alkyl or an alkenyl group. The major products of reaction are predicted to be the phenoxyl
radicals. In addition, Tyr was found to be less efficient than HTyr as free radical scavenger. Moreover, while HTyr is predicted
to be a good peroxyl scavenger, Tyr is predicted to be only moderately for that purpose. 相似文献
966.
Atsushi?NarumiEmail author Yudai?Kimura Seigou?Kawaguchi 《Colloid and polymer science》2012,290(4):379-384
The precipitation polymerizations of N-tert-butylacrylamide (NtBAM) in water are demonstrated; for example, the polymerization with potassium peroxodisulfate using a 15 g L−1 (118 mmol L−1) concentration of NtBAM in the feed ([NtBAM]0) was performed at 70 °C for 12 h, quantitatively producing poly(N-tert-butylacrylamide) particles with a number-average diameter (d
n) of 203 nm and a coefficient of variation (C
v) of 4.7%. The particle sizes were controlled in the d
ns range between 75 and 494 nm by changing the monomer feeds or adding an electrolyte such as NaCl. The solid contents in the
resulting aqueous latex solutions ranged from 0.1 to 1.5%, whereas it increased to 4.8% by applying a “shot-growth” technique.
The polymerization in water under a somewhat unique condition is described, which was started from a heterogeneous system
due to the presence of significantly large amounts of monomers ([NtBAM]0 = 50 g L−1). This also provided monodisperse latexes with the d
n of 370 nm in 96% yield, in which the solid content reached 4.9%. 相似文献
967.
Guang-Yan?Sun Hai-Bin?Li Yun?Geng Zhong-Min?SuEmail author 《Theoretical chemistry accounts》2012,131(3):1099
To maximize the efficiency of heterojunction organic photovoltaics (HJOPVs), it is imperative to increase not only the open-circuit
voltage (V
OC) but also the short-circuit current (I
SC). Therefore, it is desirable to find an organic acceptor material that possesses a higher lowest unoccupied molecular orbital
(LUMO) level for higher V
OC and can absorb photons in the solar spectrum efficiently for larger I
SC. In this paper, in comparison with the typical donor poly(3-hexylthiophene) (P3HT) and acceptor [6,6]-phenyl-C61-butyric acid ester ([60]PCBM), the geometries, electronic structures, absorption spectra, and transport properties of a series
of organic compounds containing 9,9′-bifluorenylidene (9,9′BF) were systematically investigated using density functional and the semiclassical Marcus charge transfer theory calculation
to evaluate their potential severing as acceptor. Our results indicate that the absorption spectra of 99′BF derivatives have better overlap with the solar spectrum than those of [60]PCBM, and higher LUMOs result in a significant
enhancement of V
OC when they are used in HJOPVs with P3HT as donor materials. On the other hand, these compounds own higher electron carrier
mobilities comparing with [60]PCBM. The study also demonstrates that the H-shaped compounds based on the 99′BF backbone possess good photophysical and charge transport properties, can be promising organic semiconductor for heterojunction
photovoltaics. 相似文献
968.
Alain?DelgadoEmail author Stefano?Corni Guido?Goldoni 《Theoretical chemistry accounts》2012,131(2):1115
We report on ab-initio calculations of the electronic structure and optical absorption response of the black dye sensitizer
in gas phase. We show that, despite the large size of this molecule, the second-order multiconfiguration quasi-degenerate
perturbation theory (MC-QDPT) can be used to calculate vertical excitation energies, oscillator strengths and optical absorption
spectra. The zeroth-order reference states entering perturbation calculations are complete active space (CAS) configuration
interaction (CI) wave functions computed for 12 active electrons distributed in 12 active orbitals. We found that the CI approach
is not enough for taking into account the strong dynamical correlation effects in this system. In fact, the excitation energies
of the CAS-CI target states are strongly renormalized by the MC-QDPT calculations. In the calculated absorption spectra, the
analysis of the perturbed wavefunctions revealed that the stronger absorption bands correspond to metal-to-ligand and ligand-to-ligand
charge transfer processes. Comparison with independent time-dependent extension (TDDFT) calculations performed with different
functionals shows that corrections to the long-range behavior of the functional is pivotal to achieve agreement with the MC-QDPT
results. 相似文献
969.
Vikas?D.?GhuleEmail author Dharavath?Srinivas S.?Radhakrishnan Pandurang?M.?Jadhav Surya?P.?Tewari 《Structural chemistry》2012,23(3):749-754
Density functional theory has been used to investigate geometries, heats of formation (HOFs), C-NO2 bond dissociation energies (BDEs), and relative energetic properties of nitro derivatives of azole substituted furan. HOFs for a series of molecules were calculated by using density functional theory (DFT) and Møller–Plesset (MP2) methods. The density is predicted using crystal packing calculations; all the designed compounds show density above 1.71 g/cm3. The calculated detonation velocities and detonation pressures indicate that the nitro group is very helpful for enhancing the detonation performance for the designed compounds. Thermal stabilities have been evaluated from the bond dissociation energies. Charge on the nitro group was used to assess the impact sensitivity in this study. According to the results of the calculations, tri- and tetra-nitro substituted derivatives reveal high performance with better thermal stability. 相似文献
970.
Lauren?B.?Brown Ann?M.?AndersonEmail author Mary?K.?Carroll 《Journal of Sol-Gel Science and Technology》2012,62(3):404-413
Titania (TiO2) and titania–silica (TiSi) aerogels are suitable for photocatalytic oxidation of volatile organic compounds for pollution mitigation; however, methods for fabricating these aerogels can be complex. In this work we describe the use of a rapid supercritical extraction (RSCE) technique to prepare TiO2 and TiSi aerogels in as little as 8 h. The RSCE technique uses a metal mold and a four-step hydraulic hot press procedure to bring the solvents in the sol–gel pores to a supercritical state and control the supercritical fluid release process. Resulting TiO2 aerogels were powdery with BET surface areas of 130–180 m2/g, pore volumes ~0.5 cm3/g and skeletal densities of 3.6 g/mL. Monolithic TiSi aerogels were made using two different methods. An impregnation process, in which titania precursor was added to a silica sol–gel, took 4–8 days to complete with a 7-h RSCE and resulted in translucent aerogels with high surface area (560–650 m2/g) and pore volume (2.0–2.6 cm3/g), bulk densities ranging from 0.1 to 0.4 g/mL and skeletal densities of 2.3 g/mL. A co-precursor method for preparing TiSi aerogels took 8 h to complete. The precursor chemical mixture was poured directly into the mold and processed in a 7-h RSCE process. The resulting aerogels were opaque, with high surface areas (510–580 m2/g), low bulk density (0.03 g/mL), skeletal densities of 2 g/mL and pore volumes of 2.6–3.5 cm3/g. Preliminary solar simulator studies show that TiO2 and TiSi aerogels are capable of photocatalytic degradation of methylene blue in aqueous solution. 相似文献