共查询到20条相似文献,搜索用时 15 毫秒
1.
J. K. Krüger C. Grammes K. Stockem R. Zietz M. Dettenmaier 《Colloid and polymer science》1991,269(8):764-771
In order to study the anharmonic elastic behaviour of solid polymers, we introduce a Brillouin technique, including the appropriate theoretical background, to obtain the complete tensor of elastic stiffness constants of third-order. First results are reported for glassy polycarbonate.This publication is kindly dedicated to Prof. Dr. W. Pechhold on occasion of his 60th birthday. 相似文献
2.
Jinlong Cheng Matilda Fone Yigang Fu Wei Chen 《Journal of Thermal Analysis and Calorimetry》1996,47(3):673-683
Solid-state13C nuclear magnetic resonance (13C NMR) methods have been applied to study a gel-spun ultra-high molecular-mass polyethylene fiber. The mass fractions of the crystalline (orthorhombic and monoclinic), intermediate, and amorphous phases have been determined at temperatures between 296 and 413 K. The mobility of the polymer chains in the crystalline and the intermediate phases have been measured within the same temperature range, 296–413 K. Discussions on the chain conformation and the rate of motion are carried out based on the13C chemical shift and spin-lattice relaxation time, respectively.Dedicated to Professor Bernhard Wunderlich on the occasion of his 65th birthday 相似文献
3.
Ho-Hi Lee Kouji Kimura Takatomo Takai Hitoshi Senda Akio kuwae Kazuhiko Hanai 《Spectrochimica acta. Part A, Molecular and biomolecular spectroscopy》1999,55(14):2877
Polymorphs I and II of phenylpyruvic acid are obtained as mixtures of both crystal forms or relatively pure crystals, from different solvents. Polymorph I is more stable than polymorph II at room temperature. Spectral characteristics of these polymorphs are discussed on the basis of IR, Raman and solid state 13C NMR spectra. Also, the assignment of the IR features observed in the 1600–1700 cm−1 region is re-investigated by referring to the spectra of heavy-atom substituted derivatives. It is suggested that the C=O stretching band is split by the crystal field for both polymorphs. 相似文献
4.
Hiromichi Kurosu Mizuyo Kikuchi Isao Ando 《Journal of Polymer Science.Polymer Physics》1995,33(5):769-775
The solid-state 15N CP/MAS NMR spectra and 15N spin-lattice relaxation times (T1) of doped and dedoped 15N-labeled polypyrroles prepared by electrochemical polymerization, have been measured by means of high-resolution solid-state 15N NMR. The 15N signal of polypyrrole consists of four peaks decomposed by line shape analysis. The four peaks obtained have been assigned to the various structures of polypyrrole. Further, the half-width of the 15N NMR spectra of polypyrroles is discussed as related to the electrical conductivity. © 1995 John Wiley & Sons, Inc. 相似文献
5.
Isao Ando 《Macromolecular Symposia》1996,101(1):371-377
The conformational characterization of solid polypeptides has been carried out by means of high-resolution solid-state NMR. It has been demonstrated that high-resolution solid-state NMR spectroscopy is a very useful means for elucidating the structure of polypeptides and proteins in the solid state. 相似文献
6.
Fourier transform infrared (FTIR) and 13C solid state nuclear magnetic resonance (NMR) spectroscopy were used to study dextrin structural changes occurring upon hydrogel formation by vinyl acrylate (VA) grafting and subsequent free radical polymerization. The degrees of VA substitution (DS) and polymerization (DP) were quantified up to 40%VA by FTIR intensity measurements and partial least squares (PLS)/FTIR, the latter being a faster and less error-prone method. Above 40%VA, both parameters are underestimated by FTIR. A spin counting NMR experiment showed high carbon observabilities for hydrogels and improved PLS/NMR models were achieved for DS and DP determination. Alternative NMR integration methods are hindered by the broad VA peaks and need for area correction, due to their CP dynamics. NMR changes in C1 profile showed that a single helical conformation predominates at lower %VA, being replaced by disordered conformations as %VA increases. Furthermore, a correlation FTIR/NMR study indicated that ring conformations are significantly affected in hydrogels, compared to unpolymerized dextrin. 相似文献
7.
Palma Marcia B. Pinto Annette L. Gombert Andreas K. Seitz Karina H. Kivatinitz Silvia C. Castilho Leda R. Freire Denise M. G. 《Applied biochemistry and biotechnology》2000,84(1-9):1137-1145
Lipase, protease, and amylase production by Penicillium restrictum in solid-state fermentation was investigated. The basal medium was an industrial waste of babassu oil (Orbignya oleifera) production. It was enriched with peptone, oliveoil, and Tween-80. The supplementation positively influenced both enzyme
production and fungal growth. Media enriched with Tween-80 provided the highest protease activity (8.6 U/g), whereas those
enriched with peptone and olive oil led to the highest lipase (27.8 U/g) and amylase (31.8 U/g) activities, respectively. 相似文献
8.
Thermally induced oxidative trimerization of benzimidazole by copper(II) chloride in the solid state
Rahul Bhattacharya Sibdas Ray Jayanta Ray Ashutosh Ghosh 《Central European Journal of Chemistry》2003,1(4):427-440
Benzimidazolium trichlorocuprate(II) undergoes a redox reaction in the solid state at elevated temperature (∼240°C) to produce
the cyclic trimer of benzimidazole and cuprous chloride. The trimer has been characterized by IR, NMR, and Mass spectroscopy.
It has also been synthesized in lower yield by heating the mixtures of CuCl2 and benzimidazole in different ratios or heating other compounds of CuCl2 and benzimidazole. The absorption, emission, and excitation spectra of the trimer in two different solvents (TFA and DMSO)
and a comparison of these results with those of benzimidazole are presented here. 相似文献
9.
Hossein Reza Darabi Marjan Azimzadeh Arani Mohsen Tafazzoli Mina Ghiasi 《Monatshefte für Chemie / Chemical Monthly》2008,139(10):1185-1189
The existence of a short C–H ⋯ π (alkyl–alkyne) interaction in the structure of a strained and relatively rigid tolanophane
is expected to hinder the rotation about the C–C sp3 single bond. Variable-temperature NMR experiments (performed in three solvents, CDCl3, THF-d8, and acetone-d6) and ab initio density functional calculations were carried out to investigate its dynamic nature. An energy barrier of 48.6 kJ/mol is determined
at coalescence (210 K) with acetone-d6 which is in good agreement with calculation result (54 kJ/mol).
Correspondence: Hossein Reza Darabi, Chemistry and Chemical Engineering Research Center of Iran, Pajoohesh Blvd., km 17, Karaj
Hwy, 14968-13151 Tehran, Iran. 相似文献
10.
E. A. V. Ebsworth E. K. Macdonald D. W. H. Rankin 《Monatshefte für Chemie / Chemical Monthly》1980,111(1):221-233
Difluoro(germylthio)phosphine, PF2(SGeH3), has been prepared by the reaction of S(PF2)2 with GeH3Cl, and has been characterised by i.r.,Raman, n.m.r. and mass spectroscopy. Cleavage reactions with Cl2 and HBr, donor reactions of the phosphorus atom and exchange reactions with platinum complexes have been studied. The molecular structure of PF2(SGeH3) in the gas phase has been determined by electron diffraction. Principal parameters (r
a) are:r(Ge–S) 225.6(4)pm;r(P–S) 211.5(8)pm;r(P–F) 159.0(9)pm; <(GeSP) 99.0(6)° <(SPF) 99.9(4)° <(FPF) 97.0(10)°. The conformation adopted is such that there are short non-bonded F...H contacts, with the PF2 group twisted 18° from the position in which the FPF angle bisector eclipses the Ge–S bond.
Difluor(germylthio)phosphin. Darstellung, Eigenschaften und Molekülstruktur in der Gasphase
Zusammenfassung PF2(SGeH3) wurde über die Reaktion von S(PF2)2 mit GeH3Cl dargestellt und mittels IR,Raman, NMR and MS charakterisiert. Es wurden Spaltungs-reaktionen mit Cl2 und HBr, Donor-Reaktionen des Phosphor und Austausch-reaktionen mit Platinkomplexen untersucht. Die Molekülstruktur von PF2(SGeH3) in der Gasphase wurde mittels Elektronendiffraktion bestimmt. Die Hauptparameter (r a) sind:r(Ge–S) 225,6(4)pm;r(P–S) 211,5(8)pm;r(P–F) 159,0(9)pm; <(GeSP) 99,0(6)° <(SPF) 99,9(4)° <(FPF) 97,0(10)°.相似文献
11.
Structural information of natural organic matter (NOM) at the molecular level is very essential in understanding their nature and reactivity. Nuclear magnetic resonance (NMR) is an excellent tool for estimating the gross chemical composition of the very complex humic matter (HM). A well-known fact is that the solid state 13C NMR spectral analysis is very parameter-sensitive especially in the study of the heterogenous HM (e.g. baseline corrections, different pulse techniques and spinning rates of the rotor vs. different disruptive sidebands in the spectra). This being the case, it has been emphasized the importance of qualitative and quantitative analyses for generating as real spectra as possible by means of different pulse and polarization techniques, sampling spinning rates as well as certain correction factors. In the present study a practical accuracy for quantitative determination of NOM type material by solid state 13C NMR spectroscopy was assessed using a known HM sample. Different magnetic-field strengths, sampling spinning rates, single and ramped amplitude cross polarization techniques and TOSS pulse sequence were applied for obtaining a more reliable insight into the disruptive effect of the chemical shift anisotropy (CSA), especially the most disturbing first order spinning side bands (SSB). The results demonstrated that the SSB problem is not so significant as sometimes stated, at least in the context of HM samples and in the light of the overall reproducibility and uncertainty connected with the sample itself. 相似文献
12.
13.
The solid state13C NMR spectra of four13CO enriched carbonyl clusters having a tri-iron metallic core have been analyzed to provide structural and dynamic information. In Fe3(CO)12 (1), the high temperature spectra suggest the occurrence of large amplitude motions of the CO groups around their position at the vertexes of the coordination polyhedron in addition to the motion involving the Fe3-triangle previously detected in the VT-13C MAS spectra.13C and31P NMR data of Fe3(CO)11PPh3 (2) indicates the presence of one molecule in the asymmetric unit in apparent disagreement with the previously reported X-ray data. Furthermore, we show that structural information can be obtained from the chemical shift tensor components readily available from the analysis of the spinning sideband manifold. 相似文献
14.
Ong LG Abd-Aziz S Noraini S Karim MI Hassan MA 《Applied biochemistry and biotechnology》2004,118(1-3):73-79
The oil palm sector is one of the major plantation industries in Malaysia. Palm kernel cake is a byproduct of extracted palm
kernel oil. Mostly palm kernel cake is wasted or is mixed with other nutrients and used as animal feed, especially for ruminant
animals. Recently, palm kernel cake has been identified as an important ingredient for the formulation of animal feed, and
it is also exported especially to Europe, South Korea, and Japan. It can barely be consumed by nonruminant (monogastric) animals
owing to the high percentages of hemicellulose and cellulose contents. Palm kernel cake must undergo suitable pretreatment
in order to decrease the percentage of hemicellulose and cellulose. One of the methods employed in this study is fermentation
with microorganisms, particularly fungi, to partially degrade the hemicellulose and cellulose content. This work focused on
the production of enzymes by Aspergillus niger and profiling using palm kernel cake as carbon source. 相似文献
15.
N. E. Burlinson J. A. Ripmeester 《Journal of inclusion phenomena and macrocyclic chemistry》1984,1(4):403-409
Solid inclusion compounds of cyclotriveratrylene (CTV) with benzene, toluene, acetone, tetrahydrofuran, acetic acid and chloroform, as well as two hydrated forms, were prepared and characterized by solid state13C NMR. The inclusion process for CTV appears to be quite selective, and in some instance depends critically on the presence or absence of water. A number of different structural types are indicated by the solid state13C NMR splitting paterns. For the guests listed above,1H NMR in solution indicated a guest to host ratio close to 0.5, except for chloroform, for which the ratio is closer to 2. 相似文献
16.
João Paulo Bender Marcio Antônio Mazutti Débora de Oliveira Marco Di Luccio Helen Treichel 《Applied biochemistry and biotechnology》2006,132(1-3):951-958
Inulinase is an enzyme relevant to fructose production by enzymatic hydrolysis of inulin. This enzyme is also applied in the
production of fructo-oligosaccharides that may be used as a new food functional ingredient. Commercial inulinase is currently
obtained using inulin as substrate, which is a relatively expensive raw material. In Brazil, the production of this enzyme
using residues of sugarcane and corn industry (sugarcane bagasse, molasses, and corn steep liquor) is economically attractive,
owing to the high amount and low cost of such residues. In this context, the aim of this work was the assessment of inulinase
production by solid state fermentation using by Kluyveromyces marxianus NRRL Y-7571. The solid medium consisted of sugar cane bagasse supplemented with molasses and corn steep liquor. The production
of inulinase was carried out using experimental design technique. The effect of temperature, moisture, and supplements content
were investigated. The enzymatic activity reached a maximum of 445 units of inulinase per gram of dry substrate. 相似文献
17.
Kimihiro Kubo Isao Ando Toru Shiibashi Takeshi Yamanobe Tadashi Komoto 《Journal of Polymer Science.Polymer Physics》1991,29(1):57-66
High-resolution 13Carbon nuclear magnetic resonance (NMR) spectra of Nylons 4, 6, and 66 in the solid state were measured over a wide range of temperature. From the results, it was found that resonance lines of crystalline and noncrystalline components were separable and their chemical shifts were determined. The 13C chemical shift behavior is closely related to their conformation. The origin of the conformational effects on the chemical shifts is discussed. 相似文献
18.
N. E. Burlinson J. A. Ripmeester 《Journal of inclusion phenomena and macrocyclic chemistry》1985,3(1):95-98
The cycloveratrylene tetramer was found to form well-defined solvates with chloroform and methylene chloride which were characterized by their solid state13CNMR spectra. Elemental analysis indicates the presence of two molecules of included solvent for every host molecule. Several distinct forms of the solvent-free tetramer were identified as well. 相似文献
19.
A group of para-substituted bis(acetoxy)iodoarenes has been studied by 17O and 13C NMR. Only one signal for all the oxygens of the acetoxy groups has been observed. Both 17O and 13C chemical shifts of this group show a strong invariance with para substitution. The absence of covalent I-O bonds and an ion pair structure is proposed for the title compounds. 相似文献
20.
Valentine P. Ananikov 《Central European Journal of Chemistry》2004,2(1):196-213
A convenient methodology was developed for a very accurate calculation of 13C NMR chemical shifts of the title compounds. GIAO calculations with density functional methods (B3LYP, B3PW91, PBE1PBE) and
6-311+G(2d,p) basis set predict experimental chemical shifts of 3-ethynylcyclopropene (1), 1-ethynylcyclopropane (2) and 1,1-diethynylcyclopropane (3) with high accuracy of 1–2 ppm. The present article describes in detail the effect of geometry choice, density functional
method, basis set and effect of solvent on the accuracy of GIAO calculations of 13C NMR chemical shifts. In addition, the particular dependencies of 13C chemical shifts on the geometry of cyclopropane ring were investigated. 相似文献