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1.
Richard Vytlacil 《Monatshefte für Chemie / Chemical Monthly》1980,111(5):1075-1086
In the ternary system silver chloride-lithium chloride-sodium chloride the kinetics of the galvanic deposition of silver on graphite electrodes was investigated as well as its dissolution without current in the molten salt saturated with chlorine gas.In addition the emf-values were measured in the temperature range between 923 K and 1,173 K by means of, the formation cell graphite/Ag(s)/AgCl(l)–LiCl(l)–NaCl(l)/Cl2 graphite From these data the partial molar free excessGibbs energies were calculated. Using the equation for a multicomponent system as suggested byRedlich-Kister
1
G
AgCl
E
values were obtained by a non-linear fitting process, where the fit was performed for all investigated temperatures and over the entire concentration range in the ternary system. With the parameters obtained the partial and integral excess valuesG
i
E
,G
E
,H
i
E
,H
E
,S
i
E
andS
E
were calculated. 相似文献
2.
I. Capek 《Central European Journal of Chemistry》2003,1(3):291-304
The kinetics of free-radical copolymerization and terpolymerization of acrylamide (AAm), N, N′-methylenebis(acrylamide) (MBA) and methacrylic acid (MA) in the inverse water/monomer/cyclohexane/Tween 85 miniemulsion was
investigated. Polymerizable sterically-stable miniemulsions were formulated in cyclohexane as a continuous medium. Polymerizations
are very fast and reach the final conversion within several minutes. The dependence of the polymerization rate vs. conversion
is described by a curve with two nonstationary rate intervals. The maximum rate of polymerization slightly increases with
increasing concentration of crosslinking monomer (MBA) and strongly decreases by the addition of MA. The rate of polymerization
is inversely proportional to the 0.9
th
and 1.8
th
power of the particle concentration without and with MA, respectively. The number of polymer particles is inversely proportional
to the 0.18
th
and 0.13
th
power of MBA concentration. The kinetic and colloidal parameters of the miniemulsion polymerization are discussed in terms
of microemulsion polymerization model. 相似文献
3.
In the theoretical model it is assumed that a graphite disk electrode is covered by a thin film of solution of decamethylferrocene
(dmfc) and some electrolyte CX in nitrobenzene and immersed in an aqueous solution of the electrolyte MX. Oxidation of dmfc is accompanied by the transfer of anion X
− from water into nitrobenzene since it is also assumed that cations dmfc
+ and C
+ are insoluble in water and cation M
+ is insoluble in nitrobenzene. Kinetic parameters of the electrode reaction can be determined if the total potential difference
across the nitrobenzene/water interface is maintained constant by adding the electrolytes CX and MX in concentrations which are much higher than the initial concentration of dmfc in nitrobenzene. 相似文献
4.
5.
Maria Cyfert Barbara Latko Maria Wronska 《Monatshefte für Chemie / Chemical Monthly》1980,111(3):619-626
The influence of NaClO4, NaCl and Na2SO4 on the oxidation of Fe(phen)
3
2+
by Ce(IV) was investigated by means of the stopped-flow method. At the concentrations range of NaClO4 and NaCl 0.1–1.0M the rate constant values decrease from 1.03·105 to 0.56·105M–1s–1 and from 1.08·105 to 0.81·105M–1s–1 respectively.In varying concentrations of Na2SO4 solutions (0.05–0.35M) the rate constant values decrease from 1.05·105M–1s–1 to 0.45·105M–1s–1.Taking into account the negative salt effect the mechanism of the reaction progress is proposed. 相似文献
6.
Claudia Mureşanu Lucian Copolovici Florina Pogącean 《Central European Journal of Chemistry》2005,3(4):592-604
The inhibitory effect of para-nitrophenol on the catalytic reaction of catalase was investigated. Michaelis-Menten kinetic parameters were determined from
Lineweaver-Burk plots obtained in the absence or in the presence of the inhibitor. The inhibitor pattern, revealed by the
Lineweaver-Burk plots, suggested a fully mixed inhibition mechanism. Spectrophotometric monitoring of the indicator reaction:
in conjunction with initial rate measurements was employed for the kinetic determination of the inhibitor. Calibration plots
of initial rate vs. para-nitrophenol concentration were linear in the concentration range 0.9·10−5–2.5·10−5 mol/L and the detection limit was 3·10−6 mol/L (417 μg/L) para-nitrophenol. Interferences from other phenolic compounds like orto-cresole, meta-and orto-nitrophenol were observed. 相似文献
7.
五味子中木脂素类成分的高效液相色谱-电喷雾质谱研究 总被引:3,自引:0,他引:3
采用液相色谱-电喷雾质谱联用(HPLC-ESI-MSn)技术, 对北五味子与南五味子中木脂素类成分进行了系统研究. 通过HPLC-ESI-MS技术, 获得了相应化合物的保留时间、紫外光谱和分子量等信息, 利用电喷雾多级串联质谱技术(ESI-MSn), 获得了相应化合物的结构信息. 研究结果表明, 北五味子与南五味子的主要木脂素成分除5个共有成分外其它成分差异较大, 并且其共有成分含量差别较大. 在此基础上, 建立了简便、快速的北五味子与南五味子药材分析鉴定的新方法. 相似文献
8.
Karin Popa Alexandru Cecal Doina Humelnicu Ioan Caraus Camelia L. Draghici 《Central European Journal of Chemistry》2004,2(3):434-445
This study concerns the removal of the 137Cs+ and 60Co2+ β+γ-radioactive ions in Azolla caroliniana Willd. water fern. The living fern and two different types of biosorbent prepared from Azolla caroliniana were tested to remove the above-mentioned radioactive ions from dilute solutions, in the absence and in the presence of the
ionic competition. Effective 137Cs+ and 60Co2+ ions removal from low radioactive wastewaters was demonstrated. The time dependent K
d
(t) values were calculated from the absorption data. These results indicate that removal process achieved equilibrium in about
120 min and that it involves two steps: rapid and slow absorption; the active process (metabolic bioaccumulation on the living
fern) was responsible for above one half of the total removal process. A thin layer radiochromatography study leads to the
conclusion that the biochemical components in which 137Cs+ and 60Co2+ place themselves are of a polysaccharide and lipoid fractions. 相似文献
9.
Alfred Vendl 《Monatshefte für Chemie / Chemical Monthly》1979,110(1):103-108
The crystal structure of NbMoN1–x
has been determined from X-ray powder patterns. It is isotypic with the formerly described1,2 complex nitrides NbCrN and Ta1–x
Cr1+x
N. The tetragonal unit cell contains 6 atoms and belongs to the space groupP4/nmm-D
4h
7. The lattice parameters are:a=3,095 Å,c=7,799 Å. The structure is characterized by relatively close packed double layers of Nb-atoms and Mo-atoms parallel to the base plane. The nitrogen atoms are within the octahedral interstitial sites. 相似文献
10.
Axel-Rüdiger Schulze Hanskarl Müller-Buschbaum 《Monatshefte für Chemie / Chemical Monthly》1981,112(2):149-156
The hitherto unknown compound Ca3Ga4O9 was prepared and investigated by X-ray single crystal methods. Ca3Ga4O9 has orthorhombic symmetry:a=1435.8;b=1682.5;c=532.1 pm; space group C
2v
11
–Cmm2,Z=6. The tetrahedra network (circles of 4 and 5 GaO4-tetrahedra) and the surrounding of Ca2+ are described and discussed with respect to other oxogallates. 相似文献
11.
Enn Otsa L. S. Kudrjawzewa O. G. Eisen E. M. Piotrowskaja 《Monatshefte für Chemie / Chemical Monthly》1980,111(3):607-617
The vapour-liquid equilibrium data obtained from isobarict-x-measurements have been used for calculation of the group UNIFAC parameters and excess free enthalpyG
E
of binary mixturesn-alkanes with isomericn-alkynes. The UNIFAC model gives satisfactory predictions for the systems studied. The temperature dependence ofG
E
was estimated on the basis of the heats of mixing measured earlier. The influence of the position of triple bond in the molecules ofn-alkynes on the excess thermodynamic functions is considered. 相似文献
12.
The results of kinetic and equilibrium experiments with the set of reaction of proton abstraction from 4-nitrophenyl[bis(ethylsulphonyl)]methane
in acetonitrile are reported. Two strong organic bases are used: 1,5,7-triazabicyclo[4.4.0]dec-5-ene (TBD) and 7-methyl-1,5,7-triazabicyclo[4.4.0]dec-5-ene
(MTBD).
The rates of proton transfer reaction have been measured by T-jump method in the presence of perchlorate of the appropriate
base as a common cation BH+ and supporting electrolyte-tetrabutylammonium perchlorate (TBAP) in the temperature range between 20–40°C are: k
H
=1.32×107−2.00×107 and 2.82×107−4.84×107 dm 3mol−1s−1 for MTBD and TBD respectively. The enthalpies of activation ΔH
MTBD
≠
=13.5 and ΔH
TBD
≠
=18.1 kJmol−1. The entropies of activation are negative: ΔS
MTBD
≠
=−62.3 and ΔS
TBD
≠
=−40.3 Jmol−1K−1.
The change of the absorbance of the anion of 4-nitrophenyl[bis9ethylsulphonyl)]methane at the temperature 25°C in the presence
of common cation BH+ gives the equilibrium constants K=705 and 906 M−1 for MTBD and TBD respectively.
Kinetic and equilibrium results are discussed. The possible mechanism of proton transfer reaction between 4-nitrophenyl[bis(ethylsulphonyl)]methane
and cyclic organic bases: MTBD and TBD in acetonitrile is proposed. 相似文献
13.
Potentially bi- and tetra-dentateSchiff bases derived from salicylaldehyde react with hydrated uranyl salts to give complexes: UO2H2
LX
2, UO2H2
LX
2 and UO2(HL)2
X
2 [H2
L=N,N-propane-1,3-diylbis(salicylideneimine), H2
L=N,N-ethylenebis(salicylideneimine) and HL=N-phenylsalicylideneimine;X
–=Cl–, Br–, I–, NO3
–, ClO4
–, and NCS–]. Because of marked spectral similrities with the structurally known Ca(H2
L) (NO3)2, theSchiff bases are coordinated through the negatively charged phenolic oxygen atoms and not the nitrogen atoms of the azomethine groups which carry the protons transferred from phenolic groups on coordination. Halide, nitrate, perchlorate and thiocyanate groups are covalently bonded to the uranyl ion, resulting a 6-coordinated uranium ion in the halo and thiocyanato complexes and 8-coordinated in nitrato and perchlorato complexes.
Komplexe von Dioxouranyl(VI) mit zwitterionischen Formen von zwei- und vierzähnigen Schiff-Basen
Zusammenfassung Von Salizylaldehyd abgeleitete zwei- und vierzähnigeSchiff-Basen reagieren mit hydratisierten Uranylsalzen zu Komplexen folgenden Typs: UO2H2 LX 2, UO2H2 LX 2 und UO2(HL)2 X 2 [H2 L=N,N-Propan-1,3-diylbis(salicylidenimin), H2 L=N,N-Ethylen-bis(salicylidenimin) und HL=N-Phenylsalicylidenimin;X –=Cl–, Br–, I–, NO3 –, ClO4 – und NCS–]. Auf Grund eindeutiger spektraler Ähnlichkeiten mit dem bekannten Ca(H2 L) (NO3)2 wird auf Koordination über die negativ geladenen phenolischen Sauerstoffatome (und nicht über die Azomethin-Stickstoffe) geschlossen. Die AnionenX – sind kovalent an das Uranyl-Ion gebunden; damit ergibt sich ein hexakoordiniertes Uranyl-Ion für die Halogen- und Thiocyanat-Komplexe und Oktakoordination für die Nitrat- und Perchlorat-Komplexe.相似文献
14.
A simple and effective procedure for the enantioselective synthesis of (R)- and (S)-moprolol was described. The key step was the asymmetric synthesis of enantiopure (R)- and (S)-guaifenesin, which were synthesized from enantioenriched (R)-3-chloro-l,2-propanediol and (S)-epichlorohydrin via kinetics of hydrolysis resolution of racemic epichlorohydrin by chiral Salen-Co^Ⅲ complex. The e.e. values of both the optical compounds were above 98%, and the chemical structures of the target compounds were confirmed by ^1H NMR, ^13C NMR, IR, and MS. 相似文献
15.
Molar excess volumes, V
ijk
E, and speeds of sound, U
ijk
, of o-toluidine (i) + benzene (j) + cyclohexane or n-hexane or n-heptane (k) ternary mixtures have been measured as a function of composition at 308.15 K. The observed speed of sound data have been
utilized to determine the excess isentropic compressibilities, (K
S
E)
ijk
, of the ternary (i+j+k) mixtures. The Moelywn-Huggins concept (Huggins in Polymer 12: 389–399, 1971) of connectivity between the surfaces of the binary mixture constituents has been extended to ternary mixtures (using the
concept of a connectivity parameter of third degree of molecules, 3
ξ, which in turn depends on its topology) to obtain an expression that describes well the measured V
ijk
E and (K
S
E)
ijk
data. The observed data have also been analyzed in terms of Flory’s theory. 相似文献
16.
Capacity of Bacillus thuringiensis S-layer protein displaying polyhistidine peptides on the cell surface 总被引:4,自引:0,他引:4
S-layer protein of Bacillus thuringiensis strain CTC was used as the carrier protein to display polyhistidine (poly[6His]) peptides on the cell surface. Poly(6His)
n
was fused with S-layer protein at two different sites, inserting just downstream of the S-layer protein homologous domain
(slh) and replacing the non-slh region of S-layer protein, respectively. The two series chimeric proteins were both expressed by crystal negative B. thuringiensis strain 4Q7 and strain 171, respectively, as shown by sodium dodecyl sulfate polyacrylamide gel electrophoresis. The recombinant
B. thuringiensis cells gained Ni2+- and Cd2+-binding ability and had a capacity to display up to nine copies of poly(6His). The Cd2+ adsorption quantity of the recombinant strain with the strongest adsorption ability was twice that of the host strain. 相似文献
17.
Paul Peringer 《Monatshefte für Chemie / Chemical Monthly》1980,111(6):1245-1252
The mixed mercury complexes (2XC6H4)2N3HgY (X=CH3, F, Cl, Br, I;Y=SC2H5, SC6H5, SeC6H5) have been prepared. Both the Hg–S and Hg–Se bonds and, in contrast to other mixed triazenato-mercury compounds, the triazenato-mercury bonds have been shown to be kinetically labile on the NMR time scale by means of77Se and199Hg NMR spectroscopy. Evidence has been obtained for the presence of (2XC6H4)2N3HgY together with HgY
2 and [(2XC6H4)2N3]2Hg in solution. 相似文献
18.
The reaction of trimethylsilylcarbonamides with halogeno-diorganyl-boranes resp. trihalogenoboranes or organodihalogenoboranes gives monomeric resp. dimeric amidoboranes (borylcarbonamides) and derivatives of 4,8-diaza-1,5-dibora-2,6,9-trioxabicyclo[3.3.1]nonadienes. By reaction of the free acylamides with halogenoboranes in most cases the imide halides could be isolated as the only products. By reaction of the hydrochloride of bis(dimethylamino)-hydroxyborane withn-butyl-lithium followed by addition of the imide halides, the corresponding imidoylamines were formed.1H,11B, and19F-nmr spectra, mass spectra and characteristic ir group frequencies are reported.
15. Mitt.:W. Maringgele undA. Meller, Z. anorg. allg. Chem., im Druck. 相似文献
19.
Yue Zhang Natsumi Watanabe Yuuko Miyawaki Yutaka Mune Kenta Fujii Yasuhiro Umebayashi Shin-ichi Ishiguro 《Journal of solution chemistry》2005,34(12):1429-1443
Aprotic N,N-dimethylpropionamide (DMPA) and N,N,N′,N′-tetramethylurea (TMU) are both strong donor solvents and coordinate to metal ions through the carbonyl oxygen atom. These
solvents show a different conformational aspect in the bulk phase, i.e., DMPA exists as either a planar cis or a nonplanar staggered conformer, while TMU exists in a single planar cis conformer. It has been established that the manganese(II) ion is solvated by five molecules in both solvents. Interestingly,
although the planar cis conformer of DMPA is more favorable than the nonplanar staggered one in the bulk phase, the reverse is the case in the coordination
sphere of the metal ion, i.e., a conformational change occurs upon solvation. To reveal the thermodynamic aspect of this conformational change, the complexation
of Mn(II) with bromide ions in DMPA and TMU has been studied by titration calorimetry at 298 K. It was found that the Mn(II)
ion forms mono-, di- and tri-bromo complexes in both solvents, and their formation constants, enthalpies and entropies were
obtained. The Δ H∘1 value for MnBr+ strongly depends on the solvent, i.e., it is positive (19.4 kJ-mol−1) in DMPA and negative (−8.7 kJ-mol−1) in TMU, whereas the Δ H^∘2 and Δ H∘3 values for the stepwise formation of MnBr2 and MnBr3− are both small and negative. The enthalpy of transfer ΔtH∘ from DMPA to TMU, which is evaluated on the basis of the extrathermodynamic TATB assumption, is 25.5 kJ-mol−1 for Mn2+ and −3.6 kJ-mol−1 for MnBr+. These values indicate that the difference between the formation enthalpy of MnBr+ in the two solvents, Δ H^∘1 (DMPA) – Δ H∘1 (TMU), is mainly ascribed to the value of ΔtH∘(Mn2+). It is found that the metal ion is also five-coordinated in the monobromo complex, MnBr(DMPA)4+ . The enthalpy for the conformational change of DMPA from its planar cis to the nonplanar staggered form is evaluated to be −11 and −5.5 kJ-mol−1 for Mn(DMPA)52 + and MnBr(DMPA)4+, respectively. Note that these values are significantly smaller than the corresponding value (5.0 kJ-mol−1) in the bulk phase. We thus conclude that, although steric hindrance among solvent molecules is reduced by replacing one
DMPA of Mn(DMPA)52 + with the relatively small bromide ion, DMPA molecules are still sterically hindered in the MnBr(DMPA)4+ complex. 相似文献
20.
George Bajszár Jon Croonenberghs Irina L. Karnushina Sun Y. Lee James R. Mattoon 《Applied biochemistry and biotechnology》1994,44(2):187-204
A new allelic variant of theSTA2 gene ofS. diastaticus, designated asSTA2
K, was cloned and characterized (1; accompanying paper). An application-oriented analysis of the promoter region ofSTA2
K is described, with an emphasis on its peculiar structural feature: A 1.1-kb natural deletion located 189 nucleotides upstream
of the translation start codon.
The strength of theSTA2
K promoter was found comparable to that of known strong constitutive yeast promoters(ADH1, GAPDH). Regulated glucoamylase expression was demonstrated by chimeric promoters, which were constructed by placing theSTA2
K promoter under the control of either thePH05 orCYC1 upstream regulatory sequences. On high-copy-number vectors, induction of the UASpho5-STA2K chimeric promoter by phosphate depletion resulted in a destructive overexpression of the secreted glucoamylase, which completely
halted cell growth, and promoted cell decay. In contrast, UAScyc1 was shown to mediate a fine-tuned regulation both by glucose
concentration and, indirectly, by starch, the substrate for the glucoamylase to produce glucose. 相似文献