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1.
R. Schindler R. Vonach B. Lendl R. Kellner 《Fresenius' Journal of Analytical Chemistry》1998,362(1):130-136
A new process control methodology for the simultaneous determination of sugars, alcohols and organic acids in wine based
on multivariate evaluation of mid-IR transmission spectra of wine samples is presented. In addition to ethanol several lower
level wine components (glucose, fructose, glycerol, citric-, tartaric-, malic-, lactic- and acetic acid) were determined.
To establish a multivariate calibration model a set of 72 calibration solutions was prepared and measured, using a novel,
fully automated sequential injection (SI) system with Fourier transform infrared (FTIR) detection. The resulting spectra were
evaluated using a partial least square (PLS) model. The developed PLS model was then applied to the analysis of real wine
samples containing 79–91 g L–1 ethanol, 5.9–8.1 g L–1 glycerol, 0.4–6.9 g L–1 glucose, 1.5–7.5 g L–1 fructose, 0.3–1.6 g L–1 citric acid, 1.0–1.7 g L–1 tartaric acid, 0.02–3.2 g L–1 malic acid, 0.4–2.8 g L–1 lactic acid and 0.15–0.60 g L–1 acetic acid, yielding results which were in good agreement with those obtained by an external reference method (HPLC-IR).
The short analysis time (less than 3 min) together with high reproducibility makes the newly developed method applicable to
process control and screening purposes (average of the standard deviations calculated from four repetitive measurements of
six different real samples: ethanol: 0.55 g L–1, glycerol: 0.037 g L–1, glucose: 0.056 g L–1, fructose: 0.036 g L–1, citric acid: 0.020 g L–1, tartaric acid: 0.010 g L–1, malic acid: 0.052 g L–1, lactic acid: 0.012 g L–1 and acetic acid: 0.026 g L–1).
Received: 21 January 1998 / Revised: 5 March 1998 / Accepted: 6 March 1998 相似文献
2.
Summary The simultaneous quantitation of acids and sugars as their trimethyl silyl (TMS) derivatives has been extended in order to
identify and quantitate the simple acid and sugar constituents in the hydrolyzates of various immunostimulant, water-soluble
polysaccharides obtained from various Basidiomycetes, such as Armillariella mellea, Auricularia auricula-judae, Coriolus versicolor,
Flammulina velutipes, Fomes fomentarius, Ganoderma applanatum, Ganoderma lucidum, Pleurotus ostreatus, Schizophyllum commune,
Trametes hirsuta. Optimum hydrolysis conditions, performed with 2 M trifluoroacetic acid (TFAA) for five hrs, proved the presence
of several sugars and acids with maximum recovery. (i) the total sugar/sugar alcohol content of polysaccharides varied between
20- and 65% and consisted of arabitol (0.01–10.2%), arabinose (0.09–1.3%), ribose (0.2–1.8%), fucose (0.3–1.2%), mannitol
(0.01–5.3%), sorbitol (0.01–0.05%), galactiol (0.04%), fructose (0.08–0.8%), galactose (0.9–29%), glucose (10–53%), uronic
acids (0.14–3.7%), sucrose (0.03–2%), trehalose (0.2–1%), cellobiose (0.01–0.6%), maltose (0.2–1.9%), other disaccharides
(0.2–8%). (ii) The total of acids varied from 1.5 to 30% including o-phosphoric (1.3–19%), malic (0.08–4.7%), citric (0.08–4.7%),
isocitric; (3%) and C16−C18 fatty acids (1–6%). 相似文献
3.
Zou Hantao Yi Changhai Wang Luoxin Liu Hongtao Xu Weilin 《Journal of Thermal Analysis and Calorimetry》2009,97(3):929-935
Thermogravimetric (TG), differential thermal analysis (DTA) and thermal degradation kinetics, FTIR and X-ray diffraction (XRD)
analysis of synthesized glycine–montmorillonite (Gly–MMT) and montmorillonite bound dipeptide (Gly–Gly–MMT) along with pure
Na–MMT samples have been performed. TG analysis at the temperature range 25–250 °C showed a mass loss for pure Na–MMT, Gly–MMT
and Gly–Gly–MMT of about 8.0%, 4.0% and 2.0%, respectively. DTA curves show the endothermic reaction at 136, 211 and 678 °C
in pure Na–MMT whereas Gly–MMT shows the exothermic reaction at 322 and 404 °C and that of Gly–Gly–MMT at 371 °C. The activation
energies of the first order thermal degradation reaction were found to be 1.64 and 9.78 kJ mol−1 for Gly–MMT and Gly–Gly–MMT, respectively. FTIR analyses indicate that the intercalated compounds decomposed at the temperature
more than 250 °C in Gly–MMT and at 250 °C in Gly–Gly–MMT. 相似文献
4.
S. F. Malysheva N. K. Gusarova N. A. Belogorlova A. M. Nalibayeva S. V. Yasko N. A. Chernysheva S. I. Verkhoturova G. K. Bishimbayeva B. A. Trofimov 《Russian Journal of General Chemistry》2020,90(2):229-234
Bis(polyfluoroalkyl) chlorophosphites and polyfluoroalkyl dichlorophosphites react easily with secondary amines (from –40 to –22°C, 1–3 h, CH2Cl2) in the presence or absence of triethylamine to form the corresponding bis(polyfluoroalkyl) diorganylamidophosphites or bis(diorganylamido) polyfluoroalkyl phosphites in the yield of up to 74%. Bis(polyfluoroalkyl) diorganylamidophosphites were also synthesized from diorganylamidodichlorophosphites and polyfluoroalkanols (–25 to –22°C, 2 h, Et3N–CH2Cl2) with a yield of 56–60%. 相似文献
5.
V. Shanthi K. Ramanathan Rao Sethumadhavan 《Applied biochemistry and biotechnology》2010,160(5):1473-1483
C–H….π interactions are known to be important contributors to protein stability. In this study, we have analyzed the influence
of C–H….π interactions in single chain “all-alpha” proteins. In the data set, a total of 181 C–H….π interactions were observed.
The most prominent representatives are the interactions between aromatic C–H donor groups and aromatic π acceptors. Eighty-one
percent of the C–H….π interactions between side chain to side chain and remaining19% of the C–H….π interactions were observed
between side-chain to side-chain five-member aromatic ring. The donor atom contribution to C–H….π interactions was mainly
from Phe, Tyr, and Trp residues. The acceptor atom contribution to C–H….π interactions was mainly from Phe, Tyr, Trp, and
His. The highest percentage of C–H….π interactions were observed form Phe residue. The secondary structure preference analysis
of all C–H….π interacting residues showed that Phe, Tyr, Trp, and His preferred to be in helix. Long-range C–H….π interactions
are the predominant type of interactions in single chain all-alpha proteins data set. All the C–H….π interactions forming
residues in the data set preferred to be in the buried region. Seventy-three percent of the donor residues and 65% of the
acceptor residues are highly conserved. 相似文献
6.
A. Ebrahimi S. M. Habibi Khorassani H. Delarami H. Esmaeeli 《Journal of computer-aided molecular design》2010,24(5):409-416
The substituent effects on the geometrical parameters and the individual hydrogen bond (HB) energies of base pairs such as
X–adenine–thymine (X–A–T), X–thymine–adenine (X–T–A), X–guanine–cytosine (X–G–C), and X–cytosine–guanine (X–C–G) have been studied by the quantum mechanical calculations at the B3LYP and MP2 levels with the 6–311++G(d,p) basis set. The
electron withdrawing (EW) substituents (F and NO2) increase the total binding energy (ΔE) of X–G–C derivatives and the electron donating (ED) substituent (CH3) decreases it when they are introduced in the 8 and 9 positions of G. The effects of substituents are reversed when they are located in the 1, 5, and 6 positions of C, with exception of CH3 in the 1 position and F in the 5 position, which in both cases the ΔE value decreases negligibly small. With minor exceptions (X=8–CH3, 8–F, and 9–NO2), both ED and EW substituents increase slightly the ΔE values of X–A–T derivatives. The individual HB energies (∆E
HBs) have been estimated using electron densities that calculated at the hydrogen bond critical points (HBCPs) by the atoms
in molecules (AIM) method. Most of changes of individual HBs are in consistent with the ED/EW nature of substituents and the
role of atoms entered H-bonding. The remarkable change is observed for NO2 substituted derivative in each case. 相似文献
7.
The poly(glycidyl methacrylate) adsorbents P(GMA–EDMA) and P(GMA–DVB) were synthesized by the radical suspension–polymerization
method and farther coupled by oligo-β-cyclodextrin (CDP) to obtain P(GMA–EDMA)–CDP and P(GMA–DVB)–CDP. The synthesized polymeric
media were characterized by Fourier transform infrared (FTIR) spectrometer, scanning electron microscopy, and BET surface
area. The adsorption of puerarin from aqueous solution onto the four media, i.e., P(GMA–EDMA), P(GMA–DVB), P(GMA–EDMA)–CDP,
and P(GMA–DVB)–CDP, was studied. An enhanced adsorption of puerarin apparently presented on grafted media. The interaction
between the polymeric media and the puerarin was researched by FTIR. The result shows that the adsorption efficiency on P(GMA–DVB)–CDP
driven by multiple weak interactions is much higher than that on P(GMA–EDMA) driven by hydrogen bonding interaction only and
on P(GMA–DVB) or P(GMA–EDMA)–CDP driven by two interactions. 相似文献
8.
A new resonance light-scattering (RLS) assay of proteins such as bovine serum albumin (BSA) and human serum albumin (HSA) is presented. In the medium of phosphoric acid (pH=2.6), the weak RLS of sodium dodecyl benzene sulfonate (SDBS) or sodium lauryl sulfate (SLS) can be greatly enhanced by proteins, owing to interaction between the protein and the anionic surfactant and formation of an associate. The RLS intensity of the SDBS–protein system is stronger than that of the SLS–protein system under same experimental conditions. It is considered that the synergistic resonance caused by the absorption of both protein and SDBS could produce strong RLS, while absorption of protein only in the SLS system could cause relatively weak RLS. The enhanced intensity of RLS is proportional to the concentration of the protein. If SDBS is used as the probe the linear range is 7.5×10–9–1.5×10–5 g mL–1 for BSA and 1.0×10–8–1.0×10–5 g mL–1 for HSA. The detection limits are 1.8 and 2.8 ng mL–1, respectively. When SLS is used as the probe the linear range is 2.0×10–8–1.0×10–5 g mL–1 and 2.5×10–8–1.0×10–5 g mL–1 for BSA and HSA, respectively, and the detection limits are 12.8 and 21.6 ng mL–1, respectively. The biological mimics samples are synthetic concoctions of BSA and HSA with some interferents. In these samples, the concentration of interferents is higher than the concentration normally existing in organisms. The samples were determined satisfactorily. 相似文献
9.
Fruits ofPeucedanum oreoselinum (L.) Moench, were collected at three sites in 1995–1998 and contained 1.5–5.0% essential oil. Analyses were performed using
GLC and GC-MS. The main component of the essential oil is limonene (44.1–82.4%). The majority of examined samples contained
more limonene than has been reported in the literature. Only in sunny locations do plants synthesize significant quantities
of γ-terpinene (12.2–17.5%) and β-pinene (8.5–14.5%). Small quantities of α-pinene are present in all studied samples of essential
oil (4.0–8.3%). Monoterpenes comprise 97.1–98.6% of the essential oil. The remainder consists of sesquiterpenes.
Institute of Chemistry, ul. Goshtauto, 9, Vilnius, Lithuania. Translated from Khimiya Prirodnykh Soedinenii, No. 6, pp. 743–745,
November–December, 1999. 相似文献
10.
Cai Jin-Hua Ye Yuan-Jian Huang Jin-Wang Yu Han-Cheng Ji Liang-Nian 《Journal of Sol-Gel Science and Technology》2012,62(3):432-440
Three types of silica gel supported titanium dioxide particles immobilizing Zn(II) carboxylphenyl porphyrins appending p-CH3, p-H and p-Cl phenyl substituents (designated as ZnMP–TiO2–SiO2, ZnPP–TiO2–SiO2 and ZnCP–TiO2–SiO2, respectively) have been synthesized and characterized using SEM, XRD, IR, AFS, DRS, UV–Vis, XPS and TG. The photodegradation
of α-terpinene in aqueous suspension was used to determine the photocatalytic activity of TiO2–SiO2 samples which had been impregnated with Zn(II) porphyrins, as sensitizers. The experimental results confirmed that the photocatalytic
activitys of these composites are much higher than those of the nonmodified TiO2–SiO2 under visible light irradiation and follow the order of ZnMP–TiO2–SiO2 > ZnPP–TiO2–SiO2 > ZnCP–TiO2–SiO2. 相似文献
11.
Liviu V. Costea Vasile N. Bercean Valentin Badea Klaus Gerdes Ulrich Jordis 《Monatshefte für Chemie / Chemical Monthly》2006,8(2):737-744
1H-3-Methyl-4-ethoxycarbonyl-5-(benzylidenehydrazino)pyrazoles are key intermediates in obtaining various heterocyclic systems
including pyrazolotriazoles. We present the voltammetric behavior of these compounds in nonaqueous media, with the following
para substituents grafted on the benzene ring: –N(CH3)2, –OH, –OCH3, –F, –Cl, –CF3, –NO2, as well as of the novel compounds with –Br, –I, and –SCH3 in the para position, in order to elucidate the influence of the various substituents on the mechanism of anodic oxidation. 相似文献
12.
Liviu V. Costea Vasile N. Bercean Valentin Badea Klaus Gerdes Ulrich Jordis 《Monatshefte für Chemie / Chemical Monthly》2006,137(6):737-744
Summary. 1H-3-Methyl-4-ethoxycarbonyl-5-(benzylidenehydrazino)pyrazoles are key intermediates in obtaining various heterocyclic systems
including pyrazolotriazoles. We present the voltammetric behavior of these compounds in nonaqueous media, with the following
para substituents grafted on the benzene ring: –N(CH3)2, –OH, –OCH3, –F, –Cl, –CF3, –NO2, as well as of the novel compounds with –Br, –I, and –SCH3 in the para position, in order to elucidate the influence of the various substituents on the mechanism of anodic oxidation. 相似文献
13.
Valdek Mikli 《Mikrochimica acta》2006,155(1-2):205-208
The study covers a problem frequently encountered in the quantification of the results of wavelength-dispersive spectrometry
(WDS) for the composition analysis of thin films. The characteristics of a Parallel Beam Spectrometer and traditional WDS
systems were examined and olivine mineral – (Mg, Fe)2SiO4 (O – 44.03 wt%, Mg – 31.1 wt%, Si – 19.56 wt%, Fe – 5.06 wt%, Ni – 0.16 wt%, Mn – 0.09 wt%) was used as a reference material.
Low accelerating voltage at 7 kV and beam current 400 nA were applied. Both methods yielded 30–35% of Mn. This is attributed
to the overlapping of the MnLα first-order and the MgKα second-order lines. Studies of the influences of the second- and the
third-order lines show that the second-order lines from Kα and Lα X-ray counts affected significantly the obtained WDS spectra
when the influence of Mα counts was insignificant. Furthermore, the third-order lines did not have a marked effect on the
analysis results. 相似文献
14.
15.
Jerzy Jurczyk Rafał Sitko Beata Zawisza Franciszek Buhl Ewa Malicka 《Mikrochimica acta》1999,132(1):41-47
A simple and quick method of durable samples preparation by the thin layer method through direct digesting of the analysed
material on the substrate has been presented. Four- and three-component mono- and polycrystals have been analysed. Standards
have been used in calibration containing: Cr, Co, Ni, Cu, Zn, Ga, Se, Sb, Yb. To improve the correlation between the concentration
and the fluorescent radiation models of mathematical corrections have additionally been used: multiple linear regression,
Lucas-Tooth-Pyne model (L. T. P.) and de Jongh model (d. J.).
Statistical parameters: detection limits for 0.5 mg samples: Cr–0.041%, Co–0.034%, Ni–0.042%, Cu–0.053%, Zn–0.054%, Ga–0.057%,
Se–0.057%, Sb–0.113%, Yb–0.077%. Correlation coefficients: simple regression 0.9946–0.9997, multiple regression 0.9974–1.0000,
L. T. P. 0.9993–1.0000, d. J. 0.9995–1.0000.
Received August, 1, 1998. Revision March 25, 1999. 相似文献
16.
R. M. Dorizzi Michele Schinella Antonella Pupillo Luca Endrizzi 《Accreditation and quality assurance》2000,5(9):367-370
The estimation of reference limits represents quite a taxing task for laboratories which frequently adopt the limits suggested
by manufacturers or those reported in the literature. This practice does not meet the requirements of accreditation programs
(i.e. Essential Criteria, Clinical Pathology Accreditation) that require laboratories to produce or check all their reference
intervals. We collected 15 244 hematological results from females aged 0–99 years obtained by the Rovereto Hospital Laboratory
and calculated the reference intervals, or to be more precise the health-related intervals, using an indirect method (based
on all the inpatient and outpatient results). All the measurements were carried out using an automatic Coulter STK S analyzer,
and the results were transferred to Verona by e-mail. The results for hemoglobin were: <1 year (n=154)=90–171 g/l; 2–8 years
(n=619)=104–136 g/l; 9–14 years (n=322)=118–143 g/l; 15–44 years (n=6329)=106–144 g/l; 45–75 years (n=4893)=107–148 g/l; 75–99 years
(n=2927)=90–153 g/l. The results appear different from the results currently used by Rovereto Hospital (120–160 g/l) but comparable
to those reported in the literature with the exception of the subjects under 1 year and over 75 years, probably due to the
excess of "diseased" subjects in these classes. The indirect method allows even small laboratories to produce or check their
reference intervals for all age groups, increasing the clinical effectiveness of laboratory results and satisfying the accreditation
standards.
Received: 15 April 2000 · Accepted: 20 April 2000 相似文献
17.
Sofia Zaichick Vladimir Zaichick 《Journal of Radioanalytical and Nuclear Chemistry》2011,288(1):197-202
The effect of age on chemical element contents in intact prostate of 64 apparently healthy 13–60 years old men was investigated
by neutron activation analysis with high resolution spectrometry of short-lived radionuclides. Mean values (M ± SΕΜ) for content
(mg/kg, dry weight basis) of chemical elements were: Br–31.6 ± 3.2, Ca–2150 ± 160, Cl–12670 ± 675, K–12010 ± 400, Mg–1150 ± 75,
Mn–1.56 ± 0.09, and Na–10520 ± 340, respectively. A tendency of age-related increase in Ca content and decrease in Mn content
was observed. 相似文献
18.
Bin Zhu Qingbiao Wang Esben F. Roge Peng Nan Zhijun Liu Yang Zhong 《Chemistry of Natural Compounds》2006,42(4):422-425
Hydrodistilled leaf oils of Pistacia chinensis Bunge from five locations in China were analyzed using GC/MS. A total of 58
compounds was identified in the oils, and a relatively high variation in their contents was found. The major compounds include
β-phellandrene (0.54–53.86%), α-pinene (4.74–54.44%), β-pinene (0.49–42.90%), caryophyllene (5.64–20.01%), cis-ocimene (tr−43.93%), eudesmadiene (0–15.06%), and camphene (tr−20.57%). Cluster analysis classified the leaf oils into two
chemotypes: one rich in α-pinene and β-pinene, and the other rich in β-phellandrene.
Published in Khimiya Prirodnykh Soedinenii, No. 4, pp. 341–343, July–August, 2006. 相似文献
19.
Xian-Ming Zhang Yu-Feng Hu Xiao-Ming Peng Wen-Jia Yue 《Journal of solution chemistry》2009,38(10):1295-1306
Conductivities were measured for the ternary systems NaNO3–KNO3–H2O, NaCl–BaCl2–H2O, NaCl–LaCl3–H2O, and their binary subsystems NaNO3–H2O, KNO3–H2O, NaCl–H2O, BaCl2–H2O, and LaCl3–H2O at (293.15, 298.15 and 303.15) K. The results were used to verify the generalized Young’s rule and the semi-ideal solution
theory. Comparison of the results shows that the average relative differences between the predicted and measured conductivities
are ≤4.2×10−3 for NaNO3–KNO3–H2O, ≤4.6×10−3 for NaCl–BaCl2–H2O, and ≤8.9×10−3 for NaCl–LaCl3–H2O, indicating that the generalized Young’s rule and the semi-ideal solution theory can provide good predictions for the conductivity
of mixed electrolyte solutions in terms of the data from their binary subsystems. 相似文献
20.
The conformational composition of gaseous MTMNB and the molecular structures of the rotational forms have been studied by
electron diffraction at 130∘C aided by results from ab initio and density functional theory calculations. The conformational potential energy surface
has been investigated by using the B3LYP/6-31G(d,p) method. As a result, six minimum-energy conformers have been identified.
Geometries of all conformers were optimized using MP2/6-31G(d,p), B3LYP/6-31G(d,p), and B3LYP/cc-pVTZ methods. These calculations
resulted in accurate geometries, relative energies, and harmonic vibrational frequencies for all conformers. The B3LYP/cc-pVTZ
energies were then used to calculate the Boltzmann distribution of conformers. The best fit of the electron diffraction data
to calculated values was obtained for the six conformer model, in agreement with the theoretical predictions. Average parameter
values (ra in angstroms, angle α in degrees, and estimated total errors given in parentheses) weighted for the mixture of six conformers
are r(C–C) = 1.507(5), r(C–C)ring, av = 1.397(3), r(C–S)av = 1.814(4), r(C–N) = 1.495(4), r(N–O)av = 1.223(3), ∠(C–C–C)ring = 116.0–122.5, ∠ C6–C4–C7 = 118.2(4), ∠ C–C–S = 113.6(6), ∠ C–S–C = 98.5(12), ∠ N–C–C4 = 121.9(3), ∠(O–N–C)av = 116.8(3), ∠ O–N–O = 127.0(4). Torsional angles could not be refined. Theoretical B3LYP/cc-pVTZ torsional angles for the
rotation about C–N bond, φC−N, were found to be 30.5–36.5∘ for different conformers. As to internal rotation about C–C and C–S bonds, values of φC−C = 68–118∘ and φC−S = 66–71∘ were obtained for the three most stable conformers with gauche orientation with respect to these bonds.
Some conclusions of this work were presented in a short communication in Russ. J. Phys. Chem. 2005, 79, 1701. 相似文献