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1.
Ballesteros I. Oliva J. M. Ballesteros M. Carrasco J. 《Applied biochemistry and biotechnology》1993,(1):201-211
Different treatments to improve the thermotolerance of fermenting yeasts for simultaneous ethanol saccharification and fermentation
process of cellulosic materials have been examined. Yeasts of the generaSaccharomyces andKluyveromyces were tested for growth and fermentation at progressively higher temperatures in the range of 42–47°C. The best results were
obtained withK. marxianus LG, which was then submitted to different treatments in order to achieve thermotolerant clones. A total of 35 new clones
were obtained that dramatically improved the SSF of 10% Solka-floc substrate at 45°C when compared to the original strain,
some with ethanol concentrations as high as 33 g/L. 相似文献
2.
Diane D. Spindler Charles E. Wyman Ali Mohagheghi Karel Grohmann 《Applied biochemistry and biotechnology》1988,17(1-3):279-293
Ten promising microbial strains were screened for glucose fermentation over the temperature range of 37–47°C, and five temperature-tolerant
yeasts (Saccharomyces cerevisiae SERI strain (D5A),S. uvarum, andCandida generaacidothermophilium, brassicae, andlusitaniae), were chosen for SSF evaluation on Sigmacell-50 cellulose with Genencor 150 L cellulase enzyme.Brettanomyces clausenii (Y-1414) was included for comparison to previous studies both by itself and in mixed culture withS. cerevisiae (D5A). Good conversion rates were achieved at temperatures as high as 43°C withC. brassicae andS. uvarum; mixed cultures of either of these yeasts with the thermotolerant cellobiose fermenting yeastC. lusitaniae achieved higher rates and yields than any of the three yeasts alone. However, the mixed culture ofB. clausenii andS. cerevisiae at 37°C achieved as high conversion rates and higher yields than any of the other yeasts tested. 相似文献
3.
S. R. Allayarov A. I. Mikhailov V. P. Mel'nikov I. M. Barkalov 《Russian Chemical Bulletin》1999,48(2):330-333
An equilibrium conformation of the perfluoroalkyl ∼CF2·CF2 radical at 77 K in matrices of polytetrafluoroethylene andn-perfluoroalkanes was studied. Upon cooling from 300 to 77 K at temperatures below 200 K, the ESR spectrum of this radical
changes, and the well-resolved hyperfine structure appears. The hyperfine splitting constants on nuclei of two nonequivalent
Fβ atoms were determined: 2.2 and 1.1 mT, respectively. TheA
∥ andA
⊥ values for the Fα atoms are 22.5 and 3.3 mT, respectively. The conformational angle between the axis of the orbital of an unpaired electron
and projection of the Cβ−Cγ bond is 5.6°.
Translated fromIzvestiya Akademii Nauk. Seriya Khimicheskaya, No. 2, pp. 331–334, February, 1999. 相似文献
4.
Enn Otsa Ludmila S. Kudrjawzewa Olaf G. Eisen 《Monatshefte für Chemie / Chemical Monthly》1980,111(1):37-42
Heats of mixing (H
E)ofn-octane with 1,2,3,4-isomers ofn-octyne,n-heptane withn-1-heptyne andn-nonane withn-1-nonyne at temperatures from 298.15 to 318.15 K were measured with aCalvet-type microcalorimeter. The results are presented in tables and correlated with theRedlich-Kister equation. 相似文献
5.
Production of cellulolytic enzymes on bagasse under solid state fermentation by coculture ofAspergillus ellipticus andAspergillus fumigatus was studied. Cocultivation ofA. ellipticus andA. fumigatus showed improved hydrolytic and Β-glucosidase activities as compared to the occasions when they were used separately. Various
pretreatment methods were used to make cellulose accessible to enzymatic attack. Best results were obtained through pretreatment
with 2% (w/v) calcium hydroxide. Maximum enzyme production was obtained after 8 d of fermentation process. 相似文献
6.
J. V. Aleman 《Colloid and polymer science》1988,266(11):975-983
Volume flow of 1,4 cis polybutadiene (1,4 cis PB) of ¯M
n
=311.900,T
g
=156 K, andT
m
=266 K, has been measured.Elastic modulus of the elastic wave, longitudinal volume viscosity, initial longitudinal volume viscosity, and retardation times are described at compression rates of ca. 1.0 to 200.0×10–5 s–1, and at temperatures of 293 K to 373 K, and pressures up to 150 MPa.Longitudinal volume viscosity decreases with increasing compression rate, and with decreasing volume deformation, the behavior being in all cases a typical non-equilibrium one. Longitudinal volume viscosity decreases with increasing temperature (except at 293 K), the volume flow activation energy being of about 18.2 KJ/mol. 相似文献
7.
M. S. Dhillon 《Monatshefte für Chemie / Chemical Monthly》1979,110(4):847-855
Surface tensions of mixtures of bromobenzene with cyclohexane, benzene,o-, m-, andp-xylene have been determined by the capillary rise method at 293.15 and 303.15 K. The data have been used to check the various theories of surface tension of liquid mixtures. The surface heats of mixing have been computed at 293.15 K as a function of composition.
Oberflächenspannungen und Oberflächen-Mischungswärmen von Mischungen mit Brombenzol als eine Komponente, bei 293,15 und 303,15 K
Zusammenfassung Die Oberflächenspannungen von Mischungen von Brombenzol mit Cyclohexan, Benzol undo-, m- undp-Xylol wurden mit der Kapillarmethode bei 293,15 und 303,15 K bestimmt. Die Daten wurden zur Überprüfung verschiedener Theorien der Oberflächenspannung herangezogen. Die Oberflächen-Mischungswärmen wurden für 293,15 K berechnet.相似文献
8.
The suitability of acid- and enzymatically hydrolyzed birch hemicellulose as biotechnical raw material was studied usingCluconobacter oxydans, Fusarium oxysporum, andCandida utilis for production of xylonic acid, ethanol, and SCP, respectively. The fermentabilities of both hydrolyzates were rather similar
and inhibition was evident in all cases at xylose concentrations of 257–30 g/L and higher. Potential identified fermentation
inhibitors were the lignin-derived compounds sinapyl alcohol, coniferyl alcohol, vanillin, and syringaldehyde and the sugar
degradation products furfural and 5-hydroxymethyl furfural. 相似文献
9.
Clemens C. Freyhardt Michael Wiebcke Jürgen Felsche Günter Engelhardt 《Journal of inclusion phenomena and macrocyclic chemistry》1994,18(2):161-175
Single-crystal X-ray structure analyses of N(nPr)4[B5O6(OH)4][B(OH)3]2,1, and N(nBu)4 [B5O6(OH)4][B(OH)3]2,2, reveal that these materials are novel clathrates, the isotypic host structures of which are three-dimensional assemblies of hydrogen-bonded [B5O6(OH)4]– ionsand B(OH)3 molecules. The assembly of only the pentaborate anions is a distorted (i.e., along [102] elongated) fourconnected diamond-related network. The N(nPr)
4
+
and N(nBu)
4
+
ions are trapped within the complex three-dimensional channel systems of the host frameworks. Both1 and2 crystallize monoclinically with space groupP21/c andZ=4. The cell constants are:1:a=13.592(5),b=12.082(2),c=17.355(6) Å, =106.60(2)° (298K);2:a=13.874(3),b=12.585(1),c=17.588(4) Å, =107.04(1)° (238 K). The results obtained by both11B and13C MAS NMR spectroscopy are discussed. Thermogravimetric studies under a flowing inert-gas atmosphere suggest that water, stemming from polycondensation of the hydrous borate species, is released from the clathrates at ca. 443 K (1) and 398 K (2) before the decomposition of the organic cations starts at ca. 603 K (1) and 603 K (2).Author for correspondence.
Supplementary Data relating to this article are deposited with the British Library as supplementary publication No. SUP 82172 (82 pages). 相似文献
10.
M. S. Dhillon 《Monatshefte für Chemie / Chemical Monthly》1979,110(3):639-645
Excess volumes of mixtures of 1,2-dichloroethane with acetone, chloroform, carbon tetrachloride, 1,4-dioxane, and tetrahydrofuran have been measured at 293.15 K. The data have been analysed in the light of the cell model theory andFlory's theory.
Überschuß-Volumina von 1,2-Dichlorethan mit Aceton, Chloroform, Tetrachlorkohlenstoff, 1,4-Dioxan und Tetrahydrofuran bei 239,15 K
Zusammenfassung Es wurden Überschuß-Volumina von Mischungen von 1,2-Dichlorethan mit Aceton, Chloroform, Tetrachlorkohlenstoff, 1,4-Dioxan und Tetrahydrofuran bei 239,15 K gemessen. Die Daten wurden im Licht der Zellenmodell-Theorie und der Theorie nachFlory analysiert.相似文献
11.
The effect of hydration andpH on the thermal stability of proteinase K was studied in the temperature range 310–450 K by differential scanning calorimetry. The dependences of the denaturation temperatureT
d, the specific enthalpy of denaturation H
d and the maximum of excess apparent specific heat capacityC
ex
max
upon the degree of hydrationh and thepH of the buffers used are presented. The relation betweenT
d andh is of the Flory-Garrett's type. By means of Ooi's model, the two components of the denaturation enthalpy arising from hydration and conformational change, respectively, were estimated. The fact that the specific denaturation enthalpy of proteinase K is very low may be attributed to its very low enthalpy of conformational change per heavy atom.Dedicated to Prof. Menachem Steinberg on the occasion of his 65th birthdayThis major project was supported by the National Natural Science Foundation of China. 相似文献
12.
Mohandas Devaki V. Whelan Douglas R. Panchal Chandra J. 《Applied biochemistry and biotechnology》1995,(1):307-318
Mutants resistant to comparatively high levels of acetic acid were isolated from the xylose-fermenting yeastsCandida shehatae andPichia stipitis by adapting these cultures to increasing concentrations of acetic acid grown in shake-flask cultures. These mutants were
tested for their ability to ferment xylose in presence of high acetic acid concentrations, in acid hydrolysates of wood, and
in hardwood spent sulfite liquor, and compared with their wild-type counterparts and between themselves. TheP. stipitis mutant exhibited faster fermentation times, better tolerance to acid hydrolysates, and tolerance to lower pH. 相似文献
13.
Keller Fcred A. Bates Delicia Ruiz Ray Nguyen Quang 《Applied biochemistry and biotechnology》1998,(1):137-148
Several strains and genera of yeast, includingSaccharomyces cerevisiae D5A,Pachysolen tannophilus, S. cerevisiae K-l,Brettanomyces custersii, Candida shehatae, andCandida acidothermophilum, are screened for growth on dilute acid-pretreated softwood prehydrolysate. Selected softwood species found in forest underbrush
of the western United States, which contain predominantly hexosan hemicellulose, were studied. This phase of the work emphasized
debarked Douglas fir. The two best initial isolates were gradually selected for improved growth by adaptation to increasing
prehydrolysate concentrations in batch culture, with due consideration of nutrient requirements. Microaerophilic conditions
were evaluated to encourage tolerance of pretreatment hydrolysate, as well as ethanol product. Adaptation and simultaneous
saccharification and fermentation (SSF) results are used to illustrate improved performance with an adapted strain, compared
to the wild type. 相似文献
14.
Soil application of cement kiln exhausts (electrostatic precipitator dust) at both lower and higher concentrations did not
inhibit growth, nodule formation, and productivity inCajanus cajan, vigna radiata, andVigna mungo. In fact, growth was promoted, possibly because of the dust containing most of the elements, such as N, Ca, Fe, Mg, Mn, K,
Zn, P, S, and Cu, which are needed for plant growth and root nodulation. Foliar application of the dust did not affect chlorophylls
and carotenoids. The rate of photosynthesis as measured by CO2 uptake and stomatal diffusive resistance of all legumes were
not affected. There was a biomagnification of Mg and K in leaves and seeds. Addition of the ESP dust did not affect either
the soil or nodule rhizobial population. It is evident that the dust did not act as a phytotoxicant but as an elixir of plant
life. 相似文献
15.
W. Swiatkowski 《Journal of Thermal Analysis and Calorimetry》1996,47(6):1735-1741
The rate of transformation of the chains in amorphous sulphur was examined by calorimetry at 298 K. The amorphous samples were remelted at the temperatureT
f in the range from 458 to 573 K. Increase ofT
f decreased the transformation rate. The results satisfy the equationX=1-exp[-(kt)z] (X=transformation degree,t=time, andk andz=constants). A one-stage transformation was observed for samples remelted atT
f473 K. ForT
f 523 K, transformation in two stages was observed.The effects ofT
f on the kinetics of nucleation and the growth of the nuclei are discussed. 相似文献
16.
N. Raman V. Muthuraj S. Ravichandran A. Kulandaisamy 《Journal of Chemical Sciences》2003,115(3):161-167
Neutral tetradentate N2O2 type complexes of Cu(II), Ni(II), Co(II) and Zn(II) have been synthesised using the Schiff base formed by the condensation
of acetylacetone andp-anisidine. Microanalysis, molar conductance, magnetic susceptibility, IR, UV-Vis,1 H NMR, CV and EPR studies have been carried out to determine the structure of the complexes. From the data, it is found that
all the complexes possess square-planar geometry. The EPR spectrum of the copper complex in DMSO at 300 K and 77 K was recorded
and its salient features are reported. All the title complexes were screened for antimicrobial activity by the well diffusion
technique using DMSO as solvent. The minimum inhibitory concentration (MIC) values were calculated at 37°C for a period of
24 h. It has been found that all the complexes are antimicrobially active and show higher activity than the free ligand. 相似文献
17.
Investigations on free radical copolymerization of 1-vinyl naphthalene (1-VNph, monomerM
2) with styrene (St), methyl methacrylate (MMA) and acrylonitrile (AN) (monomersm
1) in bulk at 60°C with AIBN as initiator are presented. Relative reactivity ratios were calculated by the Kelen-Tüdös method yielding:r
st=0.70 ±0.23 andr
1–VNph=2.02 ±0.40 for system St/1-VNph;r
MMA=0.32 ±0.10 andr
1–VNph=0.57 ±0.07 for system MMA/1-VNph andr
AN=0.11 ±0.03 andr
1–VNph=0.45 ±0.09 for system AN/1-VNph.Q, e values for 1-VNph according to Alfrey, Price scheme were calculated toQ
1–VNph=1.02,e
1–VNph=–0.62. 相似文献
18.
S. P. Gabuda S. G. Kozlova 《Journal of inclusion phenomena and macrocyclic chemistry》1995,22(1):1-13
The zeolite water arrangement in laumontite Ca3.85Na0.23K0.06Al7.96Si16.03O48·nH2O (n=16–18) and leonhardite (n=12–14.4) has been studied from1H and27Al-NMR data at temperatures of 200–390 K. Close agreement is found between NMR data obtained for samplesn=12 andn=18 and previous X-ray and neutron diffraction data. The H2O arrangement in the powder sample withn=14.4 and in a laumontite single crystal is represented by a combination of the H2O arrangements in samples withn=12 andn=18 with increased orientational H2O disordering. Concentration-type phase transitions are found in the single crystal and then=16 andn=18 samples at 226 and 230 K, and orientational-type phase transitions are found in the sample withn=14.4 at 230 K, and in the sample withn=18 at 293 K. The smooth transformations into an orientationally disordered glassy state arrangement of H2O in the zeolite channels is found in smaples withn=14.4, 16, and 18 at 300–330 and 305–315 K. 相似文献
19.
M. Elantkowska A. Bernard J. Dembczyński J. Ruczkowski 《Zeitschrift für Physik D Atoms, Molecules and Clusters》1993,27(2):103-109
The hyperfine structure (hfs) and the isotope shift (IS) of transitions between metastable levels of the configuration 4f
7 5d 6s and levels of the configuration 4f
6 5d 6s
2 of151Eu and153Eu were studied by means of the high resolution laser-atomic-beam technique. New data for the hfs in151Eu and153Eu were obtained as well as new and more accurate for the IS between151Eu and153Eu. The measured hfs constantsA andB of the 4f
6 5d 6s
2 configuration allow to perform a parametric analysis using the Sandars and Beck theory. The value of the Sternheimer correction is also disscused. 相似文献
20.
Ali Jabalameli Andrzej Nowek Richard H. Sullivan Jerzy Leszczyński 《Structural chemistry》1997,8(4):245-256
Ab initio studies (LCAO-MO method) on conformers of three seleno derivatives of the biuret molecules diselenobiuret [I], selenobiuret [II], and selenothiobiuret [III] were carried out at the Hartree-Fock (HF) and MP2 levels. The molecular geometries of these species were fully optimized at the HF level and characterized by analysis of the harmonic vibrational frequencies using a split-valence triple-zeta basis set augmented by a set ofd polarization functions on heavy atoms andp polarization functions on hydrogen atoms [TZP(d, p)]. The total energies of the HF-optimized structures were calculated at the MP2 (frozen core) level using a larger TZP (2df, 2pd) basis set. The potential energy searches revealed a total of 11 minimum-energy conformers (assigned astrans-trans, trans-cis, cis-trans, andcis-cis) and seven transition-state species for the title molecules. The two predicted conformers for diselenobiuret (Ia=trans-trans andIc=cis-cis) are characterized byC
2 and the third byC
s symmetry. For selenothiobiuret two forms (IIIa=trans-trans andIIId=cis-cis) possessC
1 and two (IIIb=trans-cis andIIIc=cis-trans) possessC
s symmetries, respectively. For selenobiuret, four formsIIa=trans-trans (C1),IIb=trans-cis (C
s),IIc=cis-trans (C
1), andIId=cis-cis (C1), were obtained as a result of gradient optimization. Comparison of the relative energies for the considered species indicated that thecis-trans forms are the most stable conformations for all three systems at both the HF and MP2 levels of theory. 相似文献