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1.
Temporal variations of carbon isotope composition of soil CO2 efflux (FS and δ13CFS) at different time scales should reflect both temporal variations of the climate conditions that affect canopy functioning and temporal changes in the relative contribution of autotrophic respiration to total FS. A tunable diode laser spectrophotometer (TDLS) was installed in the Hesse forest (northeast of France) early during the 2007 growing season to determine the seasonal and daily variability in δ13CFS. This method, based on the measurement of the absorption of an infrared laser emission at specific wave lengths of the 13CO2 and 12CO2, allows the continuous monitoring of the two isotopologues. The concentrations of the two isotopologues in FS were continuously monitored from June to November 2007 using chamber method and Keeling plots drawn from nocturnal accumulation of CO2 below the canopy. These TDLS measurements and isotope ratio mass spectrometer based Keeling plots gave very similar values of δ13CFS, showing the reliability of the TDLS system in this context. Results were analysed with regard to seasonal and daily changes in climatic and edaphic variables and compared with the δ13C of CO2 respired by roots, litter and soil incubated under controlled conditions. Pronounced daily as well as seasonal variations in δ13CFS were recorded (up to 1.5‰). The range of variation of δ13CFS was of the same order of magnitude at both diurnal and seasonal scales. δ13CFS observed in the field fluctuated between values of litter and of root respiration recorded during incubation, suggesting that temporal (and probably spatial) variations were associated with changes in the relative contribution of the two compartments during the day and during the season. 相似文献
2.
3.
《Inorganica chimica acta》1988,141(1):75-81
Complexes of cobalt(III) with two optically active ligands have been prepared and characterized. One of the ligands was an amino acid (S-alanine or S-isoleucine) and the other was a methyl-substituted derivative of triethylenetetramine (trien), either 2S,5R,9S-Me3trien or 2S,5S,9S-Me3trien. The amino acid complexes were prepared from the cis-α or cis-β dichloro complexes of Co(III) with the appropriate trien derivative. The crystal and molecular structure of one of these complexes, with S-alanine and 2S,5R, 9S-Me3trien, is reported.Since the cobalt(III) complex contains two chiral ligands of known absolute configuration, the overall configuration of the complex could be assigned unambiguously as the Λ isomer. Although one of the three chelate rings of the chiral tetraamine deviates from ideal symmetric skew geometry, all three methyl groups are in equatorial positions. Both secondary nitrogen atoms have S configuration, and the methyl group on the central chelate ring of the tetraamine is adjacent to the ‘flat’ rather than the ‘apical’ secondary N. The alanine anion is coordinated with its nitrogen trans to a secondary nitrogen and its oxygen trans to a primary nitrogen of the tetraamine, to give the β2 geometric isomer. Both perchlorate anions are disordered.Crystallographic data for the title complex are as follows: C12H30O11N5Cl2Co, Mr=550.23, tetragonal, P43212, Z=8, a=9.166(5), c=53.51(4) Å, V=4495.4 Å3, Dm=1.63(1), Dc=1.657 g cm−3, CuKα, λ=1.54178 Å, μ(CuKα)=90.89 cm−1, F(000)=2288, room temperature, final R=[Σ(6Fo| −|Fc|)/Σ|Fo|]=O.089 for 2620 unique, observed reflections. 相似文献
4.
Y. Naciri A. Gallais 《TAG. Theoretical and applied genetics. Theoretische und angewandte Genetik》1994,89(6):693-697
Two-factor mating designs at consecutive Sn and S(n+1) levels (S0 and S1 S1 and S2, or F2 and F3) allow estimation of all components of the variation among homozygous lines and F1 hybrids that can be derived from a given population. They also allow for the prediction of the mean of these lines and single-cross hybrids. Some tests for the presence of epistasis are possible at the levels of means and of variances. Such mating designs can be very useful for predicting the value of the best possible lines or the best possible F1 hybrids when it is difficult to produce, at an experimental level for exploratory purposes, either lines or hybrids. 相似文献
5.
CREIGHTON M. LITTON MICHAEL G. RYAN† DENNIS H. KNIGHT PETER D. STAHL‡ 《Global Change Biology》2003,9(5):680-696
The effects of fire on soil‐surface carbon dioxide (CO2) efflux, FS, and microbial biomass carbon, Cmic, were studied in a wildland setting by examining 13‐year‐old postfire stands of lodgepole pine differing in tree density (< 500 to > 500 000 trees ha?1) in Yellowstone National Park (YNP). In addition, young stands were compared to mature lodgepole pine stands (~110‐year‐old) in order to estimate ecosystem recovery 13 years after a stand replacing fire. Growing season FS increased with tree density in young stands (1.0 µmol CO2 m?2 s?1 in low‐density stands, 1.8 µmol CO2 m?2 s?1 in moderate‐density stands and 2.1 µmol CO2 m?2 s?1 in high‐density stands) and with stand age (2.7 µmol CO2 m?2 s?1 in mature stands). Microbial biomass carbon in young stands did not differ with tree density and ranged from 0.2 to 0.5 mg C g?1 dry soil over the growing season; Cmic was significantly greater in mature stands (0.5–0.8 mg C g?1 dry soil). Soil‐surface CO2 efflux in young stands was correlated with biotic variables (above‐ground, below‐ground and microbial biomass), but not with abiotic variables (litter and mineral soil C and N content, bulk density and soil texture). Microbial biomass carbon was correlated with below‐ground plant biomass and not with soil carbon and nitrogen, indicating that plant activity controls not only root respiration, but Cmic pools and overall FS rates as well. These findings support recent studies that have demonstrated the prevailing importance of plants in controlling rates of FS and suggest that decomposition of older, recalcitrant soil C pools in this ecosystem is relatively unimportant 13 years after a stand replacing fire. Our results also indicate that realistic predictions and modeling of terrestrial C cycling must account for the variability in tree density and stand age that exists across the landscape as a result of natural disturbances. 相似文献
6.
Fuad Iraqi Steven J. Clapcott Praveen Kumari Chris S. Haley Stephen J. Kemp Alan J. Teale 《Mammalian genome》2000,11(8):645-648
We have previously reported the results of genome-wide searches in two murine F2 populations for QTLs that influence survival following Trypanosoma congolense infection. Three loci, Tir1, Tir2, and Tir3, were identified and mapped to mouse Chromosomes (Chrs) 17, 5, and 1 respectively, with confidence intervals (CIs) in the
range 10–40 cM. The size of these CIs is to a large degree the consequence of limited numbers of recombination events in small
chromosomal regions in F2 populations. A number of population designs have been proposed to increase recombination levels in crosses, one of which
is the advanced intercross line (AIL). Here we report fine mapping of Tir1, Tir2, and Tir3 in G6 populations of two independent murine AILs created by crossing the C57BL/6J strain with the A/J and BALB/cJ strains,
respectively. Data were analyzed by two methods that gave equally informative and similar results. The three QTLs were confirmed
in the A/J × C57BL/6J AIL and in the combined data set, but Tir2 was apparently lost from the BALB/cJ × C57BL/6J AIL. The reduction in CIs for the Tir loci ranged from 2.5 to more than ten-fold in G6 populations by comparison with CIs obtained previously in the equivalent
F2 generations. Mapping in the AILs also resolved the Tir3 locus into three trypanosomiasis resistance QTLs, revealing a degree of complexity not evident in extensive studies at the
F2 level.
Received: 16 December 1999 / Accepted: 24 March 2000 相似文献
7.
菌渣化肥配施对稻田土壤微生物量碳氮和可溶性碳氮的影响 总被引:12,自引:0,他引:12
菌渣作为一种养分丰富的有机物料还田,可减少化肥施用,同时保持土壤肥力;而土壤微生物量碳、氮和可溶性碳、氮是土壤活性碳氮库的重要组成部分,其含量和比例变化对土壤肥力均具有重要作用。因此,探讨不同比例菌渣化肥配施对土壤微生物量碳、氮及可溶性碳、氮的影响,评价菌渣在优化土壤肥力方面的生态作用具有重要意义。本研究在水稻田间定位试验条件下,设置3个化肥水平(C) 0%、50%、100%,菌渣相对用量(F) 0%、50%、100%,共9个处理,分析了各处理土壤微生物量碳(MBC)、氮(MBN)和可溶性碳(DOC)、氮(DON)的变化特征,及其占土壤有机碳(SOC)和全氮(TN)的比例与相关关系。结果表明:菌渣化肥配施后,微生物量碳和可溶性碳、氮均在C100F50最高,微生物量氮在C50F100最高,与不施肥处理相比,分别显著增加了49.40%、43.65%、83.52%、207.19%;MBC/SOC和DOC/SOC均随着菌渣化肥配施量的增加而减少,MBN/TN和DON/TN均在C100F50最高。相关分析表明,MBC、DOC与SOC,MBN与TN均呈极显著正相关,DON和TN呈显著正相关。总体来讲,菌渣化肥配施能够显著提高土壤微生物量碳、氮和可溶性碳、氮含量,但不是随着用量的增加一直呈增加趋势,高量菌渣或者化肥下会有降低趋势;菌渣化肥配施降低了土壤微生物量和可溶性碳氮比,因此适宜的菌渣化肥配施是提高土壤有机碳周转速度、微生物活性及其氮素供应能力和有效性的最佳选择。 相似文献
8.
Comparison of Photosynthetic Traits Between Two Typical Shrubs: Legume and Non-Legume in Hunshandak Sandland 总被引:6,自引:0,他引:6
In Huanshandak Sandland, China, net photosynthetic rate (P
N), transpiration rate (E), stomatal conductance (g
s), intercellular CO2 concentration (C
i), water use efficiency (WUE), photochemical efficiency of photosystem 2 (Fv/Fm), and leaf nitrogen content were compared for Hedysarum fruticosum var. mongolicum (H.f.m.), a nitrogen fixing shrub, and Salix gordejevii (S.g.), a nitrogen non-fixing shrub. P
N, E, and g
s of the two shrubs were similar in trends, i.e. two peaks were observed in diurnal courses. However, except C
i, other parameters of H.f.m. were higher during the measured days than those of S.g. The midday depression of P
N was mainly due to decrease in stomata conductance and to reduction of Fv/Fm at midday. The higher P
N of H.f.m. was consistent with the higher leaf N content and there was a positive relation between them. In addition, several C4 traits were found in H.f.m., i.e. high saturation irradiance and WUE, low dark respiration rate, and C
i, which partly resulted in higher P
N. This seems to indicate that the C3 plant H.f.m. may have C4 photosynthesis pathway or C4 enzymes. 相似文献
9.
Harry M. Zacharis 《Chemistry and physics of lipids》1977,18(2):221-231
The melting behavior of a variety of saturated long chain compounds is shown to be related to hydrocarbon chain length by the equation TN = C0 + T∞N where T is the absolute melting temperature, and N is the number of long chain carbon atoms. The constants C0 and T∞ are determined graphically or analytically from TN vs. N data. The linear relationship, derived from fundamental thermodynamic principles, is empirically satisfied. For each homologous series considered, coefficients of the equation provide a rational means for correlation and comparison with other polymorphs and indicate the relative importance of chain length, chain parity (even or odd), and headgroup polarity to melting behavior. 相似文献
10.
《Biochimica et Biophysica Acta (BBA)/Molecular Cell Research》1986,886(1):76-87
The presence of three distinct populations of folate binding sites on the surface of Dictyostelium discoideum cells has been reported recently. The A sites (consisting of two subtypes) recognize folic acid, 2-deaminofolic acid and methotrexate with equal affinity and appear to be linked to cAMP synthesis. B and C sites (the latter is composed of two interconvertable subtypes; rapidly equilibrating, CF, and more slowly equilibrating, CS) preferentially bind N10-methylfolic acid and folic acid and may both be involved in the chemotactic response (De Wit, R.J.W. and Van Haastert, P.J.M. (1985) Biochim. Biophys. Acta 814, 199–213; De Wit, R.J.W., Bulgakov, R., Pinas, J.E. and Konijn, T.M. (1985) Biochim. Biophys. Acta 814, 214–226). The present study gives two lines of evidence that the B and C sites are interconvertable. (i) Occupancy of the B-sites by N10-methylfolic acid proceeds at a rate identical to that of the association of this ligand to CS at all concentrations tested. This suggests that association to CS and formation of occupied B sites share a common pathway. (ii) After preincubation with ligand, removal of free ligand results in the reappearance of unoccupied CF sites with kinetics identical to the disappearance of occupied B sites. Furthermore, the existence of a third type of C site, which is formed out of CS and may be converted to B, is proposed. This is based on competition studies using folate analogs with a different affinity for CS and B. 相似文献
11.
Fan Z Robbins MD Staub JE 《TAG. Theoretical and applied genetics. Theoretische und angewandte Genetik》2006,112(5):843-855
Cucumber (Cucumis sativus L.; 2n=2x=14) has a narrow genetic base, and commercial yield of US processing cucumber has plateaued in the last 15 years. Yield may
be increased by altering plant architecture to produce unique early flowering (days to flower, DTF), female (gynoecious, GYN),
highly branched (multiple lateral branching, MLB), long-fruited (length:diameter ratio, L:D) cultivars with diverse plant
statures. The genetic map position of QTL conditioning these quantitatively inherited yield component traits is known, and
linked molecular markers may have utility in marker-assisted selection (MAS) programs to increase selection efficiency, and
effectiveness. Therefore, a base population (C0), created by intermating four unique but complementary lines, was subjected to three cycles (C1–C3) of phenotypic (PHE) mass selection for DTF, GYN, MLB, and L:D. In tandem, two cycles of marker-assisted backcrossing for
these traits began with selected C2 progeny (C2S) to produce families (F1[i.e., C2S × C2S], and BC1 [i.e., F1 × C2S]) for line extraction, and for comparative analysis of gain from selection by PHE selection, and MAS. Frequencies of marker
loci were used to monitor selection-dependent changes during PHE selection, and MAS. Similar gain from selection was detected
as a result of PHE selection, and MAS for MLB (~0.3 branches/cycle), and L:D (~0.1 unit increase/cycle) with concomitant changes
in frequency at linked marker loci. Although genetic gain was not realized for GYN during PHE selection, the percentage of
female flowers of plants subjected to MAS was increased (5.6–9.8% per cycle) depending upon the BC1 population examined. Selection-dependent changes in frequency were also detected at marker loci linked to female sex expression
during MAS. MAS operated to fix favorable alleles that were not exploited by PHE selection in this population, indicating
that MAS could be applied for altering plant architecture in cucumber to improve its yield potential.
The cost of publishing this paper was defrayed in part by the payment of page charges. Under postal regulations, this paper
therefore must be hereby, marked advertisement solely to indicate this fact. Mention of a trade name, proprietary product,
or specific equipment does not constitute a guarantee or warranty by the USDA and does not imply its approval to the exclusion
of other products that may be suitable. 相似文献
12.
D. R. Flaschenriem P. D. Ascher 《TAG. Theoretical and applied genetics. Theoretische und angewandte Genetik》1979,55(1):23-28
Summary A cross between a 0% pseudo-self-compatible (PSC) plant (S3.3) and a 100% PSC plant (S1.1) yielded an F1 population which, when selfed, produced a high mean seed set which was not significantly different than that produced when the F1 was backcross pollinated by the 100% PSC parent. Backcross pollinating the F1 with the 0% PSC parent yielded no seed. No S3.3 plants were recovered in the F2 populations, indicating that pollen tubes containing the S3 allele were inhibited during pollen tube growth of the selfed F1 plants. Apparently stylar-conditioned PSC does not remove all discriminatory power from these petunia styles. Crossing the F1 (S1.3) with an self-incompatible (SI) plant (S2.2) produced plants which were used for computation of a standard linkage test. An approximate map distance of 28 units was found between the S specificity locus and the major gene(s) which influenced its expression. Other generalized PSC modifying genes apparantly were not linked with the S locus.Scientific Journal Series Paper Number 10,606 of the Minnesota Agricultural Experiment Station 相似文献
13.
Roberto L. Salomón Kathy Steppe Jean M. Ourcival Selwyn Villers Jesús Rodríguez-Calcerrada Roderick Schapman Jean M. Limousin 《Plant, cell & environment》2020,43(6):1528-1544
Stem water storage capacity and hydraulic capacitance (CS) play a crucial role in tree survival under drought-stress. To investigate whether CS adjusts to increasing water deficit, variation in stem water content (StWC) was monitored in vivo for 2 years and related to periodical measurements of tree water potential in Mediterranean Quercus ilex trees subjected either to permanent throughfall exclusion (TE) or to control conditions. Seasonal reductions in StWC were larger in TE trees relative to control ones, resulting in greater seasonal CS (154 and 80 kg m−3 MPa−1, respectively), but only during the first phase of the desorption curve, when predawn water potential was above −1.1 MPa. Below this point, CS decreased substantially and did not differ between treatments (<20 kg m−3 MPa−1). The allometric relationship between tree diameter and sapwood area, measured via electrical resistivity tomography, was not affected by TE. Our results suggest that (a) CS response to water deficit in the drought-tolerant Q. ilex might be more important to optimize carbon gain during well-hydrated periods than to prevent drought-induced embolism formation during severe drought stress, and (b) enhanced CS during early summer does not result from proportional increases in sapwood volume, but mostly from increased elastic water. 相似文献
14.
Jeffrey B. Olsen Chris Habicht Joel Reynolds James E. Seeb 《Environmental Biology of Fishes》2004,69(1-4):261-273
Mutation rate can vary widely among microsatellite loci. This variation may cause discordant single-locus and multi-locus estimates of FST, the commonly used measure of population divergence. We use 16 microsatellite and five allozyme loci from 14 sockeye salmon populations to address two questions about the affect of mutation rate on estimates of FST: (1) does mutation rate influence FST estimates from all microsatellites to a similar degree relative to allozymes?; (2) does the influence of mutation rate on FST estimates from microsatellites vary with geographic scale in spatially structured populations? For question one we find that discordant estimates of FST among microsatellites as well as between the two marker classes are correlated with mean within-population heterozygosity (HS) and thus are likely due to differences in mutation rate. Highly polymorphic microsatellites (HS > 0.84) provide significantly lower estimates of FST than moderately polymorphic microsatellites and allozymes (HS < 0.60). Estimates of FST from binned allele frequency data and RST provide more accurate measures of population divergence for highly polymorphic but not for moderately polymorphic microsatellites. We conclude it is more important to pool loci of like HS rather than marker class when estimating FST. For question two we find the FST values for moderately and highly polymorphic loci, while significantly different, are positively correlated for geographically proximate but not geographically distant population pairs. These results are consistent with expectations from the equilibrium approximation of Wright's infinite island model and confirm that the influence of mutation on estimates of FST can vary in spatially structured populations presumably because the rate of migration varies inversely with geographic scale. 相似文献
15.
Siffeen Zehra Mohammad Shavez Khan Iqbal Ahmad 《Journal of biomolecular structure & dynamics》2019,37(7):1863-1879
New tailored Cu(II) & Zn(II) metal-based antitumor drug entities were synthesized from substituted benzothiazole o?vanillin Schiff base ligands. The complexes were thoroughly characterized by elemental analysis, spectroscopic studies {IR, 1H & 13C NMR, ESI?MS, EPR} and magnetic susceptibility measurements. The structure activity relationship (SAR) studies of benzothiazole Cu(II) & Zn(II) complexes having molecular formulas [C30H22CuN5O7S2], [C30H20Cl2CuN5O7S2], [C30H20CuF2N5O7S2], [C30H22N4O4S2Zn], [C30H20Cl2N4O4S2Zn], and [C30H20F2N5O7S2Zn], with CT?DNA were performed by employing absorption, emission titrations, and hydrodynamic measurements. The DNA binding affinity was quantified by K b and K sv values which gave higher binding propensity for chloro-substituted Cu(II) [C30H20Cl2CuN5O7S2] complex, suggestive of groove binding mode with subtle partial intercalation. Molecular properties and drug likeness profile were assessed for the ligands and all the Lipinski’s rules were found to be obeyed. The antimicrobial potential of ligands and their Cu(II) & Zn(II) complexes were screened against some notably important pathogens viz., E. coli, S. aureus, P. aeruginosa, B. subtilis, and C. albicans. The cytotoxicity of the complexes [C30H20Cl2CuN5O7S2], [C30H20CuF2N5O7S2], [C30H20Cl2N4O4S2Zn], and [C30H20F2N5O7S2Zn] were evaluated against five human cancer cell lines viz., MCF?7 (breast), MIA?PA?CA?2 (pancreatic), HeLa (cervix) and Hep?G2 (Hepatoma) and A498 (Kidney) by SRB assay which revealed that chloro-substituted [C30H20Cl2CuN5O7S2] complex, exhibited pronounced specific cytotoxicity with GI50 value of 4.8 μg/ml against HeLa cell line. Molecular docking studies were also performed to explore the binding modes and orientation of the complexes in the DNA helix. 相似文献
16.
为了更好地理解土壤碳氮对枯落物输入变化的响应,通过枯落物添加与去除实验(DIRT)对滇中高原云南松林枯落物输入变化对土壤碳氮储量及其分布格局的影响进行了研究。2018年3月至2019年2月分别设置6种枯落物输处理,分别为对照(CO)、去除枯落物(NL)、双倍枯落物(DL)、去除根系(NR)、无输入(NI)以及去除有机层与A层(O/A-Less),研究了不同处理条件下土壤剖面上碳氮储量的分布规律。研究结果表明:(1)不同处理全碳储量为134.49-170.92 t/hm2,全碳储量在不同处理间表现为:SC(NL)=170.92 t/hm2 > SC(CO)=168.10 t/hm2 > SC(NR)=153.26 t/hm2 > SC(NI)=147.20 t/hm2 > SC(O/A-Less)=143.54 t/hm2 > SC(DL)=134.49 t/hm2,不同处理0-20 cm土层全碳储量占0-60 cm土层全碳储量的40.86%-53.56%;不同处理全氮储量表现为:SN(CO)=11.83 t/hm2 > SN(NL)=9.70 t/hm2 > SN(DL)=8.70 t/hm2 > SN(NR)=8.35 t/hm2 > SN(O/A-Less)=8.21 t/hm2 > SN(NI)=8.09 t/hm2。不同处理0-20 cm土层的全氮储量占0-60 cm土层全氮储量的39.28%-46.04%。云南松林地枯落物添加去除实验发现去除枯落物短期内可以增加土壤碳储量,其他处理均在一定程度上减少了土壤碳氮储量。(2)地上枯落物输入对表层(0-20 cm)土壤碳氮影响显著,根系输入对深层(20-40 cm)土壤碳氮影响显著;(3)土壤C、N存在耦合关系,不同处理土壤全碳含量与全氮含量极显著正相关,并且土壤全碳含量与土壤各化学计量比均呈极显著正相关关系;土壤容重与土壤碳氮含量具有极显著负相关关系。 相似文献
17.
The thermal dissipation technique is widely used to estimate transpiration of individual trees and forest stands, but there
are conflicting reports regarding its accuracy. We compared the rate of water uptake by stems of six tree species in potometers
with sap flow (F
S) estimates derived from thermal dissipation sensors to evaluate the accuracy of the technique. To include the full range
of xylem anatomies (i.e., diffuse-porous, ring-porous, and tracheid), we used saplings of sweetgum (Liquidambar styraciflua), eastern cottonwood (Populus deltoides), white oak (Quercus alba), American elm (Ulmus americana), shortleaf pine (Pinus echinata), and loblolly pine (Pinus taeda). In almost all instances, estimated F
S deviated substantially from actual F
S, with the discrepancy in cumulative F
S ranging from 9 to 55%. The thermal dissipation technique generally underestimated F
S. There were a number of potential causes of these errors, including species characteristics and probe construction and installation.
Species with the same xylem anatomy generally did not show similar relationships between estimated and actual F
S, and the largest errors were in species with diffuse-porous (Populus deltoides, 34%) and tracheid (Pinus taeda, 55%) xylem anatomies, rather than ring-porous species Quercus alba (9%) and Ulmus americana (15%) as we had predicted. New species-specific α and β parameter values only modestly improved the accuracy of F
S estimates. However, the relationship between the estimated and actual F
S was linear in all cases and a simple calibration based on the slope of this relationship reduced the error to 1–4% in five
of the species, and to 8% in Liquidambar styraciflua. Our calibration approach compensated simultaneously for variation in species characteristics and sensor construction and
use. We conclude that species-specific calibrations can substantially increase the accuracy of the thermal dissipation technique. 相似文献
18.
An investigation was performed into the operation of an integrated system for continuous production and product recovery of solvents (acetone-butanol-ethanol) from the ABE fermentation process. Cells of Clostridium acetobutylicum were immobilized by adsorption onto bonechar, and used in a fluidized bed reactor for continuous solvent production from whey permeate. The reactor effluent was stripped of the solvents using nitrogen gas, and was recycled to the reactor. This relieved product inhibition and allowed further sugar utilization. At a dilution rate of 1.37 h–1 a reactor productivity of 5.1 kg/(m3 · h) was achieved. The solvents in the stripping gas were condensed to give a solution of 53.7 kg/m3. This system has the advantages of relieving product inhibition, and providing a more concentrated solution for recovery by distillation. Residual sugar and non-volatile reaction intermediates are not removed by gas stripping and this contributes to high solvent yields.List of Symbols
C kg/m3
Lactose concentration in reactor effluent
-
C
b kg/m3
Lactose concentration in bleed stream
-
C
c kg/m3
Lactose concentration in whey permeate feed
-
C
i kg/m3
Lactose concentration at reactor inlet
-
C
p kg/m3
Lactose concentration in condensed solvent stream (=0)
-
C
r kg/m3
Lactose concentration in recycle line (C
b=C
r)
-
C kg/h
Amount of lactose utilized during certain time period
-
D h1
Dilution rate of reactor, F
i/D=F/D
-
F dm3/h, m3/h
F
i = Rate of feed flow to the reactor
-
F
b
dm
3/h, m3/h
Rate of bleed
-
F
c dm3/h, m3/h
Rate of feed of whey permeate solution
-
F
p dm3/h, m3/h
Rate of concentrated product removal
-
F
r dm3/h, m3/h
Rate of recycle of stripped effluent to the reactor
-
P
l %
Percent lactose utilization
-
R
l kg/(m3 · h)
Overall lactose utilization rate
-
R
p kg/(m3 · h)
Overall reactor (solvent) productivity
-
R
sl kg/h
Rate of solvent loss
- S kg/m3
Solvent concentration in reactor effluent
-
S
b kg/m3
Solvent concentration in bleed
-
S
c kg/m3
0; Solvent concentration in concentrated whey permeate solution
-
S
i kg/m3
Solvent concentration at inlet of reactor
-
S
p kg/m3
Solvent concentration in concentrated product stream
-
S
r kg/m3
Solvent concentration in stripped effluent, S
r=Sb
- S kg/h
Amount of solvent produced from C amount of lactose in a particular time
- ds/dt kg/(m3 · h)
Rate of accumulation of solvents in the stripper
-
t h
Time
-
V dm3, m3
Total reactor volume
-
V
1 dm3, m3
Liquid volume in stripper
-
Y
P/S
Solvent yield 相似文献
19.
J DiSalvo M J Jiang J R Vandenheede W Merlevede 《Biochemical and biophysical research communications》1982,108(2):534-540
An ATPMg-dependent phosphorylase phosphatase was identified in vascular smooth muscle from bovine aorta. The smooth muscle enzyme, like the corresponding enzyme from striated muscle, exists as an inactive phosphatase (FC-enzyme) which can be activated by a protein, FA, in the presence of ATP and Mg2+. Moreover, smooth muscle FC is activatable by skeletal muscle FA and skeletal muscle FC can be activated by smooth muscle FA. The mode of activation of aortic FC by aortic FA is similar to that reported for the skeletal muscle proteins. In accord with earlier findings obtained with the skeletal muscle system, the activity of the aortic phosphatase is inhibited by a specific heat-stable modulator protein (previously called phosphatase inhibitor-2). Thus, the fundamental properties of arterial ATPMg-dependent phosphatase appear to be identical to those of its skeletal muscle counterpart which purportedly represents the major phosphorylase phosphatase in that tissue. Since glycogen phosphorylase is activated when vascular smooth muscle contracts, ATPMg-dependent protein phosphatase may participate in coordinating arterial metabolism and contractility. 相似文献
20.
Chlorophyll a fluorescence characteristics were investigated in 12 species and 2 hybrids from the genus Flaveria exhibiting C3, C3–C4 intermediate, or C4 photosynthesis, and in the C4 species Zea mays. At room temperature, the variable fluorescence divided by the maximum fluorescence (FV/FM) of dark-adapted leaves decreased from C3 to C4 plants. This trend was qualitatively paralleled by an increase of the 735 nm peak relative to the 685 nm peak (F735/F685) of fluorescence emission spectra measured at low temperature (77 K). The variations were analysed using a quantitative model that takes into account higher PS I fluorescence in C4 plants than in C3 plants. The model predicts a linear correlation between 1/(FV/FM) and F735/F685, and was experimentally confirmed. From linear regression analysis, the FV/FM of PS II was calculated to be 0.88. By comparing the FV/FM of PS II with the FV/FM from leaves, the PS I contribution to total F0 fluorescence at wavelengths greater than 700 nm was determined to be about 30% and 50% in C3 and C4 plants, respectively. The corresponding values for the FM fluorescence were 6% and 12%. It is concluded that the effects of PS I fluorescence are significant and should be taken into account when analysing fluorescence data. 相似文献