共查询到20条相似文献,搜索用时 15 毫秒
1.
Golovnya R. V. Yuryev V. P. Kalistratova E. N. Wasserman L. A. Terenina M. B. Krikunova N. I. Misharina T. A. 《Russian Chemical Bulletin》2001,50(2):300-303
Supramolecular complexes of organic odorants (n-octanol and n-octyl acetate) with polysaccharides of corn starch, its cryotextures, and waxy corn starch cryotextures were studied by differential scanning microcalorimetry. It was shown that complexes are formed with amylose-containing starch and no complexes are formed with amylopectin starch. The melting enthalpies of the complexes were determined. It was shown that complexes of the odorants with native corn starch and its cryotextures have different thermodynamic characteristics. 相似文献
2.
R. V. Golovnya M. V. Grishin A. G. Filatova B. R. Shub 《Russian Chemical Bulletin》2000,49(8):1471-1472
The microstructure of a corn starch sol was studied by scanning tunneling microscopy. The influence ofn-octyl acetate on the microstructure was found. The original starch sol contains compact anisodiametric particles 500–800
nm in size. The addition ofn-octyl acetate produces friable oval associates consisting of fine spherical particles 50–20 nm in size.
Published inIzvestiya Akademii Nauk. Seriya Khimicheskaya, No. 8, pp. 1478–1480, August, 2000. 相似文献
3.
Capillary gas chromatography was used to study noncovalent sorption ofn-butyl,n-hexyl, andn-octyl acetates from aqueous solutions by corn starch cryotextures. In the concentration range of 0.5–15.0 mmol L−1, about 38%n-butyl acetate, 70%n-hexyl acetate, and 98%n-octyl acetate are extracted from aqueous solutions. The sorption of the alkyl acetates depends on the alkyl chain length,
indicating the hydrophobic character of their interaction with the corn starch cryotexture. No competitive sorption between
acetates in the mixture was observed. Binding of alkyl acetates occurs during the cryosponge formation, due probably to the
templation at the stage of starch sol, fixation in the cryosponge, and sorption on the surface of its walls.
Translated fromIzvestiya Akademii Nauk. Seriya Khimicheskaya, No. 10, pp. 1943–1945, October, 1998. 相似文献
4.
JOSE-ANTONIO TREJO-O'REILLY JEAN-YVES CAVAILLE ALESSANDRO GANDINI 《Cellulose (London, England)》1997,4(4):305-320
The surface modification of various cellulosic materials was studied in heterogeneous conditions using different grafting
agents bearing anhydride or isocyanate reactive groups. Some of these reagents were oligomeric, others polymeric and most
were chosen so as to provide a non-polar character to the surface of the fibres in view of their possible use as reinforcing
agents in composites based on polymeric matrices. The success of these chemical modifications was assessed by Fourier-transform
Infrared Spectroscopy, scanning electron microscopy, X-ray photoelectron spectroscopy and elemental analysis. The accessibility
of the superficial OH groups varied as a function of the coupling agent in terms of both molecular size and chemical nature
and ranged between 1 and 3% of the total hydroxy groups borne by the initial cellulose sample.
This revised version was published online in August 2006 with corrections to the Cover Date. 相似文献
5.
In this research, surfaces of eight ancient metal arrowheads were investigated regarding chemical composition, homogeneity, and products of corrosion. To perform that, two nondestructive techniques were applied: Scanning electron microscopy coupled with energy dispersive spectroscopy (SEM-EDS), and X-ray powder diffractometry (XRPD). Importantly, both methods did not require sampling, cutting, nor significant cleaning of the historical artifacts, which made the measurements not only nondestructive but noninvasive too. SEM-EDS measurements provided information on the morphology and elemental composition of the surfaces of the studied objects as well as the distribution of chemical elements on the surfaces and supported crystalline phase analysis. It was revealed that the arrowheads were cast of tin bronze, but some of them contained high amounts of lead and admixtures of antimony and arsenic while copper and tin oxides and lead carbonates were found as the major corrosion products. In some cases, distribution of elements in the surface exhibited serious nonhomogeneity, probably resulting from limited solubility of the casting metals and degradation processes. Based on the obtained results, authenticity and declared provenience of the arrowheads were assessed in reference to the characteristics of similar objects described in literature. 相似文献
6.
Shigang Sun Shuangjin Hong Shengpei Chen Guoqiang Lu Hongping Dai Xiaoyin Xiao 《中国科学B辑(英文版)》1999,42(3):261-267
In situ scanning FTIR microscopy was built up for the first time in the present work, which consists of an FTIR apparatus, an IR
microscope, an X-Y mapping stage, and the specially designed electrochemical IR cell and computer software. It has been demonstrated
that this new space-resolvdin situ IR technique can be used to study vibration properties of micro-area, and to perform IR imaging of electrode surface. The
chemical image obtained using this technique for CO adsorption on Pt electrode illustrated, at a space-resolution of 10-2 cm, the inhomogeneity and the distribu-tion of reactivity of micro-area of electrode surface.
Project supported by the National Natural Science Foundation of China (Grant No. 29525307). 相似文献
7.
Y. Laligant 《Journal of solid state chemistry》2001,160(2):401
The crystal structures of two telluromolybdates CdTeMoO6 and CoTeMoO6 have been solved ab initio. CdTeMoO6 crystallizes in a tetragonal cell (space group No. 113, P
21m, Z=2) with a=5.2840(1) Å, c=9.0595(2) Å whereas CoTeMoO6 crystallizes in orthorhombic space group P21212 (No. 18) with two formula units in the unit cell of dimensions a=5.2545(1) Å, b=5.0653(1) Å, and c=8.8589(2) Å. The X-ray powder diffraction pattern data were refined by the Rietveld profile technique and led respectively to RBragg=0.07 for CdTeMoO6 and RBragg=0.07 for CoTeMoO6. The crystal structure of CdTeMoO6 is built up from corner-sharing distorted CdO4 tetrahedra which build a layer in the a,b plane, while in CoTeMoO6 cobalt atoms exhibited an octahedral distorted surrounding. Both compounds are simultaneously cation- and anion-deficient 1.1.2 superstructures of fluorite in which the electron lone pairs of tellurium are stereo-chemically active. High-resolution electron microscopy images of CdTeMoO6 showed well-ordered crystals fragments, but in some crystals defects have also been detected. 相似文献
8.
Martin Andresen Leena-Sisko Johansson Bjørn Steinar Tanem Per Stenius 《Cellulose (London, England)》2006,13(6):665-677
Microfibrillated cellulose (MFC) obtained by disintegration of bleached softwood sulphite pulp in a homogenizer, was hydrophobically modified by surface silylation with chlorodimethyl isopropylsilane (CDMIPS). The silylated MFC was characterized by Fourier transform infrared spectroscopy (FT-IR), atomic force microscopy (AFM), transmission electron spectroscopy (TEM), X-ray photoelectron spectroscopy (XPS) and white light interferometry (WLI). The degree of surface substitution (DSS) was determined using Si concentrations from XPS survey scans, as well as deconvoluted peaks in high-resolution C1s XPS spectra. The DSS values obtained by the two methods were found to be in good agreement. MFC with DSS between 0.6 and 1 could be dispersed in a non-flocculating manner into non-polar solvents, TEM observations showing that the material had kept its initial morphological integrity. However, when CDMIPS in excess of 5 mol CDMIPS/glucose unit in the MFC was used, partial solubilization of the MFC occurred, resulting in a drop in the observed DSS and a loss of the microfibrillar character of the material. The wetting properties of films cast from suspension of the silylated MFC were also investigated. The contact angles of water on the films increased with increasing DSS of the MFC, approaching the contact angles observed on super hydrophobic surfaces for the MFC with the highest degree of substitution. This is believed to originate from a combination of low surface energy and surface microstructure in the films. 相似文献
9.
I. I. Gnatyuk N. V. Platonova G. A. Puchkovskaya E. N. Kotelnikova S. K. Filatov J. Baran M. Drozd 《Journal of Structural Chemistry》2007,48(4):654-665
Thermal deformations and polymorphic transformations of two long-chain evennumbered normal paraffins C26H54 and C28H58 were studied by thermal X-ray diffraction (temperature step is tenths of a degree), infrared spectroscopy (temperature step is 1–5°), and differential scanning calorimetry (temperature step is 2° in a sample heating melt cooling mode. The samples are characterized by high homologous purity (99.0%) and belong to so-called “boundary” n-paraffins. The starting C26H54 n-paraffin sample is a triclinic modification at room temperature (Tc cryst). When quickly cooled, the melt crystallizes as the triclinic Tc cryst and monoclinic monolayer 1M cryst forms (two-phase mixture Tc cryst + 1M cryst). The starting C28H58 n-paraffin sample is a double-layer monoclinic modification 2M cryst at room temperature. Crystallization from hexane or slow cooling of a melt leads to a monolayer monoclinic form 1M cryst. Thermal deformations and temperature ranges of existence of the crystalline forms (Tc cryst, 1M cryst, and 2M cryst), low-temperature rotator crystalline orthorhombic form (Or rot.1), and high-temperature rotator crystalline hexagonal (H rot.2) phases of these n-paraffins were evaluated from changes in their diffraction patterns and unit cell parameters. The molecular structure and the conformational composition of these n-paraffins in different states were found from their IR spectra. Differential scanning calorimetry (DSC) was used to determine the phase transition temperature. Thermal X-ray diffraction, IR, and DSC data agree well with one another. 相似文献
10.
L. N. Mazalov S. V. Trubina I. M. Oglezneva N. A. Kryuchkova O. V. Tarasenko V. L. Varand T. E. Kokina S. V. Larionov 《Journal of Structural Chemistry》2005,46(3):542-545
X-ray photoelectron and voltammetry studies of the charged state of the metal atom in nickel(II) chelate complexes with ligands
containing CS
2
−
and PS
2
−
groups and in heteroligand complexes on their basis were carried out. It is shown that the degree of formal oxidation of
the nickel atom in the complexes corresponds to Ni(II). In the case of heteroligand complexes, addition of nitrogen heterocycles
causes an increase in the electron density on the atoms of the coordination center. Theoretical data obtained in ab initio quantum chemical model calculations correlate with the experimental results.
Original Russian Text Copyright ? 2005 by L. N. Mazalov, S. V. Trubina, I. M. Oglezneva, N. A. Kryuchkova, O. V. Tarasenko,
V. L. Varand, T. E. Kokina, and S. V. Larionov
__________
Translated from Zhurnal Strukturnoi Khimii, Vol. 46, No. 3, pp. 554–557, May–June, 2005. 相似文献
11.
Hydrothermal synthesis and characterization of nanocrystalline ZrO2 and surface modification with 2-acetoacetoxyethyl methacrylate 总被引:1,自引:0,他引:1
Funda Sayılkan Meltem Asiltürk Esin Burunkaya Ertuğrul Arpaç 《Journal of Sol-Gel Science and Technology》2009,51(2):182-189
For the utilization as inorganic/organic hybrid nanomaterials for optical purposes, nanocrytalline tetragonal ZrO2 was synthesized by hydrothermal method using zirconium(IV)-n-propoxide as precursor material. Surface of the ZrO2 particles was then modified with 2-acetoacetoxyethyl methacrylate used as a copolymer for coatings. X-ray diffraction analysis
revealed that both ZrO2 and modified ZrO2 are in tetragonal crystalline phase. As proved by transmission electron microscope and particle size analysis, average particle
sizes of ZrO2 and modified ZrO2 were found as 6.22 and 14.7 nm, respectively. ZrO2 powder was easily dispersed either in water or n-hexane. Ultraviolet diffuse reflectance spectrophotometer analysis for ZrO2 and surface modified ZrO2 showed that maximum absorption peaks are at 215 and 225 nm, respectively. 相似文献
12.
Recent developments in quantitative surface analysis by Auger (AES) and x-ray photoelectron (XPS) spectroscopies are reviewed and problems relating to a more accurate quantitative interpretation of AES/XPS experimental data are discussed. Special attention is paid to consideration of elementary physical processes involved and influence of multiple scattering effects on signal line intensities. In particular, the major features of core-shell ionization by electron impact, Auger transitions and photoionization are considered qualitatively and rigorous approaches used to calculate the respective transition probabilities are analysed. It is shown that, in amorphous and polycrystalline targets, incoherent scattering of primary and signal Auger and photoelectrons can be described by solving analytically a kinetic equation with appropriate boundary conditions. The analytical results for the angular and energy distribution, the mean escape depth, and the escape probability as a function of depth of origin of signal electrons as well as that for the backscattering factor in AES are in good agreement with the corresponding Mote Carlo simulation data. Methods for inelastic background subtraction, surface composition determination and depth-profile reconstructions by angle-resolved AES/XPS are discussed. Examples of novel techniques based on x-ray induced photoemission are considered. 相似文献
13.
Temperature dependence of viscosity and relation with the surface tension of ionic liquids 总被引:1,自引:0,他引:1
Viscosities of ionic liquids were correlated with two linear relations. The first one presents the temperature dependence of imidazolium-, pyridinium-, pyrrolidinium-, quaternary ammonium-, and nicotinium-based ionic liquids with high accuracy. The second one is a linear relation between logarithm of surface tension and fluidity involving the characteristic exponent ?, and fits the ionic liquids uniquely with ? = 0.30. Our previously measured surface tension data of ionic liquids and literature's were used in this study. The dependence of surface tension–fluidity relation of the imidazolium-based ionic liquids on the anion type is likely disappeared as alkyl chain length increases. 相似文献
14.
V. V. Lesnyak V. K. Yatsimirskii O. Yu. Boldyreva T. D. Kinder 《Theoretical and Experimental Chemistry》2008,44(3):189-194
The catalytic activity in the oxidation of hydrogen (in the gaseous state in the presence of excess oxygen) has been studied
for samples of Pt(Pd)/Ta2O5−x, formed by reduction with hydrogen. The samples obtained had greater activity than the traditional catalysts Pt(Pd)/Al2O3. According to X-ray diffraction analysis and electron microscopic studies, Ta2O5−x becomes amorphous with the formation of more reduced non-stoichiometric oxygen-deficient tantalum oxides with a surface layer
of catalyst.
__________
Translated from Teoreticheskaya i éksperimental’naya Khimiya, Vol. 44, No. 3, pp. 180–185, May–June, 2008. 相似文献
15.
Jin-Hai Niu Ai-Min Zhu Chuan Shi Hong-Yu Fan Xiao-Mei Chen Xue-Feng Yang 《Research on Chemical Intermediates》2007,33(6):549-566
A pretreatment-transient reaction product analysis method was applied to study the reactions and average composition of the
possible surface intermediate species in selective catalytic reduction with ethylene of NO
x
over Co-ZSM-5. The reactions of the surface species, formed by the pretreatment of Co-ZSM-5 in a NO/C2H4/O2 mixture at 275°C, with the NO/O2 flow produced much more N2 than that with the individual NO or O2 flow. The similarity of N2/CO
x
/H2O product distribution generated from the above surface species-NO/O2 reactions and that from the normal NO/C2H4/O2 flow reactions implies that the surface species NC
a
O
b
H
c
formed in the three-component pretreatment process is very likely the primary intermediate surface species generated during
the real flow reactions. The in situ FT-IR (DRIFT) spectroscopy measurements of the surface species support the above conclusion. 相似文献
16.
M. Yu. Smirnov A. V. Kalinkin V. I. Bukhtiyarov 《Journal of Structural Chemistry》2007,48(6):1053-1060
The reactions of the platinum and rhodium model catalysts applied to aluminum oxide with NOx (10 Torr NO + 10 Torr O2) were studied by X-ray photoelectron spectroscopy. The reaction conducted at room temperature formed on the surface of the oxide support the NO 3,s ? nitrate ions characterized by the N1s line at 407.4 eV and O1s line at 533.1 eV and the NO 2,s ? nitrite ions characterized by the N1s line with a binding energy of 404.7 eV. At the same time, the Pt4f and Rh3d lines of the supported platinum particles are shifted toward higher binding energies by 0.5–1.0 eV and 0.7–1.2 eV, respectively. It is assumed that the binding energies increase due to changes in the chemical state of the platinum metal in which oxygen is dissolved. The reaction of NOx with Pt/Al2O3 at 200°C forms platinum oxide defined by the Pt4f 7/2 line with a binding energy of 72.3 eV. 相似文献
17.
Roth M 《Journal of chromatography. A》2009,1216(10):1861-1880
Applications and prospects of two-phase, tuneable solvent systems composed of ionic liquids (ILs) and supercritical fluids with an emphasis on supercritical carbon dioxide (scCO(2)) are reviewed. The IL-scCO(2) biphasic systems have increasingly been used in diverse fields of chemistry and technology, and some examples of these applications are mentioned here. Rational design of such applications can obviously benefit from pertinent data on phase equilibria including the partition coefficients of the prospective products and reactants between the two phases. Therefore, a reliable technique to measure the limiting partition coefficients would be of value. Here, the pros and cons of supercritical fluid chromatography in this respect are discussed. An overview of methods for predictive thermodynamic modelling of binary (IL-scCO(2)) and ternary (solute-IL-scCO(2)) systems is also included. 相似文献
18.
The imine of polybenzimidazole (PBI) is chemically oxidized by hydrogen peroxide (H2O2) in the presence of acetic acid (AcOH). Fourier transform infrared (FT-IR) and X-ray photoelectron spectroscopies (XPS) showed that when the AcOH concentration remained constant, the degree of oxidation increased with increasing H2O2 levels. Moreover, the imine also exhibited electrochemical redox behavior. Based on these properties, a PBI-modified Au (PBI/Au) electrode was developed as an enzyme-free H2O2 sensor. At an applied potential of −0.5 V vs. Ag/AgCl, the current response of the PBI/Au electrode was linear with H2O2 concentration over a range from 0.075 to 1.5 mM, with a sensitivity of 55.0 μA mM−1 cm−2. The probe had excellent stability, with <5% variation from its initial response current after storage at 50 °C for 10 days. Potentially interfering species such as ascorbic or uric acid had no effect on sensitivity. Sensitivity improved dramatically when multiwalled carbon nanotubes (MWCNT) were incorporated in the probe. Under optimal conditions, the detection of H2O2 using a MWCNT-PBI/Au electrode was linear from 1.56 μM to 2.5 mM, with a sensitivity of 928.6 μA mM−1 cm−2. Analysis of H2O2 concentrations in urine samples using a MWCNT-PBI/Au electrode produced accurate real-time results comparable to those of traditional HPLC methods. 相似文献
19.
Iva Rezi? 《Trends in analytical chemistry : TRAC》2011,30(7):1159
Textile materials with engineered nanoparticles (ENPs) have excellent properties as they are antibacterial, antimicrobial, water resistant and protective. The textile industry has recognized the importance and the advantages of ENPs, so they comprise one of the fastest developing branches of processing.The most important sources of ENPs released to the environment from textiles are textile-industry wastewaters and waters from large hospital or hotel laundries. In addition, waste textile materials coated with ENPs present a threat to the environment, if such materials are not properly handled and disposed of after use.Currently, the toxicity and the potential harm of ENPs widely applied on textiles are not thoroughly investigated and/or eliminated. Consequently, there is an urgent need to define the most appropriate analytical methods for monitoring ENPs on textiles.This review presents the most important techniques for monitoring ENPs on textile materials and in textile-wastewater samples, from the perspective of protecting the environment and human health. 相似文献
20.
Graphene field-effect transistors (GFET) have emerged as powerful detection platforms enabled by the advent of chemical vapor deposition (CVD) production of the unique atomically thin 2D material on a large scale. DNA aptamers, short target-specific oligonucleotides, are excellent sensor moieties for GFETs due to their strong affinity to graphene, relatively short chain-length, selectivity, and a high degree of analyte variability. However, the interaction between DNA and graphene is not fully understood, leading to questions about the structure of surface-bound DNA, including the morphology of DNA nanostructures and the nature of the electronic response seen from analyte binding. This review critically evaluates recent insights into the nature of the DNA graphene interaction and its affect on sensor viability for DNA, small molecules, and proteins with respect to previously established sensing methods. We first discuss the sorption of DNA to graphene to introduce the interactions and forces acting in DNA based GFET devices and how these forces can potentially affect the performance of increasingly popular DNA aptamers and even future DNA nanostructures as sensor substrates. Next, we discuss the novel use of GFETs to detect DNA and the underlying electronic phenomena that are typically used as benchmarks for characterizing the analyte response of these devices. Finally, we address the use of DNA aptamers to increase the selectivity of GFET sensors for small molecules and proteins and compare them with other, state of the art, detection methods. 相似文献