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1.
Centaurea calcitrapa suspension cultures were grown either in Erlenmeyer flasks or in a mechanically stirred bioreactor. Its rheological behaviour,
when fitted to the Oswald–de Waele model (power law), showed pseudoplastic characteristics in both cases. The flow behaviour
index (n) decreased over the course of a growth cycle and the consistency index (K) increased, reached a value of 1.81 N sn m−2 run on 2 l bioreactor. Bioreactor cultivation of C. calcitrapa cells at different agitation rates (30, 60, 100 and 250 rpm), highlighted the influence of shear forces on cell viability
loss (90–34%) and phenol accumulation (74–140 μg l−1), due to increased stirring speeds. Analysis of these results suggests that this cell line is shear-sensitive. An empirical
exponential correlation was defined between apparent viscosity and biomass concentration, under the studied conditions, giving
the possibility to estimate the prevailing broth regime and to optimize bioreactor design.
Revisions requested 10 October 2005; Revisions received 19 December 2005 相似文献
2.
Influence of microbial concentration on the rheology of non-Newtonian fermentation broths 总被引:2,自引:0,他引:2
The objective of this study was to quantify the effect of fungal biomass concentration on the rheology of non-Newtonian fermentation
systems. Batch fermentations of Penicillium chrysogenum were carried out with glucose as the sole carbon source. The flow behavior of the system was characterized at various fermentation
times and was adequately described by the power-law model. The apparent viscosity of the fermentation broth was significantly
affected by biomass concentrations in the fermenter. Fermentation broths containing 17.71 g/l biomass as dry weight were characterized
by an apparent viscosity of 0.25 Pa s at a shear rate of 50 s−1. Microbial concentration also affected the power-law flow-behavior index and the consistency index. The value of the consistency
index ranged from 0.002 Pa s
n
at a biomass concentration of 0.1 g/l to 6.14 Pa s
n
at a biomass concentration of 17.71 g/l. The flow-behavior index decreased from an initial value of 1 to a final value of
0.17. Simple empirical correlations have been proposed to quantify the dependence of the power-law parameters on fungal biomass
concentration. Experimental data obtained in this study were accurately described by these correlations. The general applicability
of these relationships was tested, using previously published rheological data on Aspergillus awamori and Aspergillus niger fermentation broths, and good agreement was seen between experimental data and the predictions from the empirical correlations.
Received: 24 March 1998 / Received revision: 10 September 1998 / Accepted: 16 October 1998 相似文献
3.
The steady-state viscosity (η*) of the liquid two-phase disperse system water-casein-sodium alginate of varying composition, with a disperse particle diameter of about 30 μm, has been investigated in the shear rate range
. The flow curves obtained are similar in shape. They are invariant in composition and can be fitted to the flow curve equation
where η*0 is the Newtonian viscosity obtained from data at low shear stresses and k is an empirical parameter. Both η*0 and k depend on the composition of the two-phase system.The experimental dependence of the viscosity on the composition follows a logarithmic additivity law at high shear stresses, but at low shear stresses the observed viscosities are lower than would be predicted by this law. The experimental dependence of the ratio
(the mean activation volume) on the composition is also not in agreement with the additivity law. These special features of the steady-state flow of the investigated disperse system are explained by the presence of a low-concentration interphase layer having a lower viscosity and less pronounced non-Newtonian behaviour than the disperse and continuous phases. This interphase layer exists in other two-phase systems which consist of a solvent and two incompatible polymers. For this reason, the rheological behaviour of the system investigated may be expected to be common for two-phase systems of this type, particularly protein-polysaccharide mixtures in water. 相似文献
4.
《Electromagnetic biology and medicine》2013,32(3):260-264
ABSTRACTThe aim of the study is to test the influence of in vivo magnetostimulation on the rheological properties of blood in neurological patients. Blood circulation in the body depends both on the mechanical properties of the circulatory system and on the physical and physicochemical properties of blood. The main factors influencing the rheological properties of blood are as follows: hematocrit, plasma viscosity, whole-blood viscosity, red cells aggregability, deformability, and the ability of red cells to orient in the flow. The blood samples were collected from neurological patients with pain. Blood samples were collected twice from each patient, that is, before the magnetostimulation and immediately after the therapy. For each blood sample, the hematocrit value was measured using the standard method. Plasma viscosity and whole-blood viscosity were measured by means of a rotary-oscillating rheometer Contraves LS40. Magnetic field was generated by the instrument Viofor JPS® and the magnetostimulation treatments were performed using M1P2 and M1P3 programs. The analysis of the results included estimation of the hematocrit value (Hct), plasma viscosity (ηp), whole-blood viscosity and rheological parameters of Quemada’s model: k0, k∞, γ′c. Plasma viscosity values were obtained from the shear rate dependence of shear stress using the linear regression method. The results obtained in the study suggest that the blood rheological properties change in accord with applied magnetostimulation program. 相似文献
5.
Decolourization of anaerobically digested and polyaluminium chloride treated distillery spentwash was studied in a fungal
stirred tank aerobic reactor without dilution of wastewater. Aspergillus niger isolate IITB-V8 was used as the fungal inoculum. The main objectives of the study were to optimize the stirrer speed for
achieving maximum decolourization and to determine the kinetic parameters. A mathematical model was developed to describe
the batch culture kinetics. Volumetric oxygen transfer coefficient (k
L
a) was obtained using dynamic method. The maximum specific growth rate and growth yield of fungus were determined using Logistic
equation and using Luedeking–Piret equation. 150 rpm was found to be optimum stirrer speed for overall decolourization of
87%. At the optimum stirrer speed, volumetric oxygen transfer coefficient (k
L
a) was 0.4957 min−1 and the maximum specific growth rate of fungus was 0.224 h−1. The values of yield coefficient (Y
x/s) and maintenance coefficient (m
s) were found to be 0.48 g cells (g substrate)−1 and 0.015 g substrate (g cells)−1 h−1. 相似文献
6.
E. Savin J. Siegelova B. Fisher P. Bonnin 《European journal of applied physiology and occupational physiology》1997,76(3):289-293
The intra- and extracerebral Doppler artery blood velocity responses to a 10-mmHg abrupt blood pressure (BP) decrease in ten
healthy men were studied. This decrease was obtained using two cuffs placed over both thighs. First, cuffs were inflated to
pressures greater than the arterial BP for 5 min. Next, they were deflated to 60 mmHg in order to prevent venous return from
the legs. We obtained a decrease in mean arterial BP of from 101 (10) to 90 (10) mmHg [mean (SD), P < 0.01] without modifications in the heart rate [HR, 88 (14) beats min−1]. Middle cerebral artery mean blood velocity (MCAmv) decreased immediately from 50 (10) to 42 (12) cm s−1 (P < 0.05). Simultaneously, temporal superficial artery mean blood velocity (TSAmv) decreased from 11 (3) to 7 (2) cm s−1 (P < 0.05) and common carotid artery blood flow (CCAbf ) decreased from 305 (23) to 233 (33) ml min−1 (P < 0.05). After 5 s, MCAmv and CCAbf returned to baseline values, whereas TSAmv [8 (2) cm s−1], mean arterial BP [86 (10) mmHg] remained low and HR increased [92 (12) beats min−1]. TSAmv, BP and HR returned to baseline values in 1 min. These data confirm that cerebral blood flow (CBF) is very rapidly
regulated but that blood flow in extracranial territories is not and that it follows the arterial BP changes.
Accepted: 8 April 1997 相似文献
7.
The steady state non-Newtonian viscosity of whole human blood has been widely studied as a function of the shear rate; and used to characterize the blood in various pathological disorders. In our previous studies, we demonstrated that blood is a thixotropic fluid. Its time-dependency and shear rate dependency of rheological behavior can be represented by an equation developed by Huang. Parameters of the equation can be used for the characterization of an individual's blood. They provide information, such as the kinetic rate constant of breakdown of RBC rouleaux to individual erythrocytes and the relative amount of rouleau formation in the dynamic equilibrium between rouleaux and individual erythrocytes. In this communication, the thixotropic parameters from blood samples of fifteen apparently healthy human subjects were investigated. When compared to the use of apparent viscosity values for the correlation with a pathological disorder, thixotropic parameters are preferable. The mean values of thixotropic parameters obtained from apparently healthy human subjects provide a base for comparison with the same parameters as obtained from blood samples of patients with certain pathological disorders involving the circulation. 相似文献
8.
Juozas Kulys Kastis Krikstopaitis Arturas Ziemys 《Journal of biological inorganic chemistry》2000,5(3):333-340
N -substituted phenothiazines (PTs) and phenoxazines (POs) catalyzed by fungal Coprinus cinereus peroxidase and Polyporus pinsitus laccase were investigated at pH 4–10. In the case of peroxidase, an apparent bimolecular rate constant (expressed as k
cat/K
m) varied from 1 ×107 M−1 s−1to 2.6×108 M−1 s−1 at pH 7.0. The constants for PO oxidation were higher in comparison to PT. pH dependence revealed two or three ionizable
groups with pK
a values of 4.9–5.7 and 7.7–9.7 that significantly affected the activity of peroxidase. Single-turnover experiments showed
that the limiting step of PT oxidation was reduction of compound II and second-order rate constants were obtained which were
consistent with the constants at steady-state conditions. Laccase-catalyzed PT and PO oxidation rates were lower; apparent
bimolecular rate constants varied from 1.8×105 M−1 s−1 to 2.0×107 M−1 s−1 at pH 5.3. PO constants were higher in comparison to PT, as was the case with peroxidase. The dependence of the apparent
bimolecular constants of compound II or copper type 1 reduction, in the case of peroxidase or laccase, respectively, was analyzed
in the framework of the Marcus outer-sphere electron-transfer theory. Peroxidase-catalyzed reactions with PT, as well as PO,
fitted the same hyperbolic dependence with a maximal oxidation rate of 1.6×108 M−1 s−1 and a reorganization energy of 0.30 eV. The respective parameters for laccase were 5.0×107 M−1 s−1 and 0.29 eV.
Received: 20 September 1999 / Accepted: 24 February 2000 相似文献
9.
Bioreactor cultivations were carried out with Schizophyllum commune and Xanthomonas campestris. Influence of process parameters and downstream processing on molecular data (molecular weight, intrinsic and shear viscosity) of the secreted exopolysaccharide are shown. Glucan formation of S. commune was enhanced by oxygen limitation. Depending on the type of agitator used, a maximum glucan formation rate of 0.12 kg/(m3 · h) was reached. During cultivation molecular weight and intrinsic viscosity went through a broad maximum with maximum data of 1.3 107 g/mol and 15,400 cm3/g, respectively. After substrate consumption glucan degrading enzymes (glucananses) were released by S. commune. For washing out low molecular substances and concentrating cellfree glucan solutions cross-flow filtration technique with hollow fiber cartridges (molecular cut-off 100,000) were used. After this procedure the shear and intrinsic viscosity were decreased. In contrast to Xanthan, shear viscosity of glucan solutions was not affected by a change in pH from 2 to 12. The intrinsic viscosity of aqueous Xanthan and glucan solutions was opposingly altered by adding salt.List of Symbols
A
number of capillaries
-
C
*g/(dm3 · h)
formation rate
-
D
–1
shear rate
-
k Pa/sn
consistency index
-
n
flow behaviour index
-
MW g/mol
molecular weight
-
R m
radius
-
t h
time
-
V dm3
volume
-
Y
yield coefficient
-
mPas
shear viscosity
- [] cm3/g
intrinsic viscosity
-
Pa
shear stress
Indices
PS
polysaccharide
-
X
cell mass
-
S
substrate
-
m
maximum
Dedicated to Prof. Dr. Fritz Wagner on his 60th birthday 相似文献
10.
Barrera-Cortés J Manilla-Pérez E Poggi-Varaldo HM 《Bioprocess and biosystems engineering》2006,29(5-6):391-398
The objective of this work was to determine (1) the effect of rotational speed (N) and lifters on the oxygen transfer coefficient (k
L) of a mineral solution and (2) the effect of solids concentration of a slurry soil-mineral solution on k
L, at a fixed value N (0.25 s−1); in both cases the treatment was carried out in an aerated rotating drum reactor (RDR) operated at atmospheric pressure. First, the k
L for the mineral solution was in the range 6.38 × 10−4–7.69 × 10−4 m s−1, which was of the same order of magnitude as those calculated for closed rotating drums supplied with air flow. In general, k
L of RDR implemented with lifters was superior or equal to that of RDR without lifters. For RDR implemented with lifters, k
L increased with N in the range 6.65 × 10−4–10.51 × 10−4 m s−1, whereas k
L of RDR without lifters first increased with N up to N = 0.102 s−1, and decreased beyond this point. Second, regarding soil slurry experiments, an abrupt fall of k
L (ca. 50%) at low values of the solid concentration (C
v) and an asymptotic pattern at high C
v were observed at N = 0.25 s−1. These results suggest that mass transfer phenomena were commanded by the slurry properties and a semi-empirical equation of the form Sh = f(Re, Sc) seems to corroborate this finding. 相似文献
11.
G. M. Pavlov 《European biophysics journal : EBJ》1997,25(5-6):385-397
The relationship between the sedimentation coefficient s0 and its concentration coefficient ks obtained in experiments on velocity sedimentation for polysaccharides is discussed. The values of s0, ks and an independently determined molecular weight reported by different authors for different polysaccharides are considered.
It was established that the scaling relation. ks∼ s0
v
unambiguously relates to the scaling relation s0∼ Mb. The values of the sedimentation parameter β
s introduced on the basis of Svedberg's equation for s0 and on the basis of the expression ks = B 〈h2〉3/2M–1 are discussed and the generalized Wales-van Holde-Rowe equation MKS = (NA/β
S)3/2[s]3/2 kS
1/2 is used for evaluation of the molecular weights of polysaccharides. The adequacy of this evaluation is illustrated by taking
as an example the determination of the unit length weight of an extra-rigid polysaccharide chain and of the equilibrium rigidity
of rigid-chain, semi-rigid-chain and flexible-chain polysaccharides. The pair of experimental values s0 and kS obtained in a single series of experiments give the same information as may be obtained from the other pairs of hydrodynamic
values such as [η] and s0 or [η] and D0, where [η] is the intrinsic viscosity and D0 is the translational diffusion coefficient.
Accepted: 11 December 1996 相似文献
12.
The apparent viscosity of non-Newtonian fermentation media is examined. The present state of this subject is discussed. The energy dissipation rate concept is used for a new evaluation of the apparent viscosity in bioreactors, i.e. stirred tank and bubble column bioreactors. The proposed definition of the apparent viscosity is compared with the definitions available in the literature.List of Symbols
A
d
m
2
downcomer cross-sectional area
-
A
r
m
2
riser cross-sectional area
-
a m–1
specific surface area
-
C
constant in eq. (13)
-
D m
column diameter
-
D
I
m
impeller diameter
-
g m s–2
gravitational acceleration
-
h J m–2 s–1 K–1
heat transfer coefficient
-
K Pa s
n
consistency index in a power-law model
-
k
constant in eq. (3)
-
k
L
m s
–1
liquid-phase mass transfer coefficient
-
N s–1
impeller speed
-
n
flow index in a power-law model
-
P W
power input
-
Re
Reynolds number ND
I
/2
/(/)
-
U
sg
m s
–1
superficial gas velocity
- (U
sg
)
r
m s–1
superficial gas velocity based on riser
-
V-m3
liquid volume
-
v
0 m s–1
friction velocity
Greek Symbols
s–1
shear rate
-
c s–1
characteristic shear rate
-
W kg–1
energy dissipation rate per unit mass
-
W kg–1
characteristic energy dissipation rate per unit mass
-
Pa s
viscosity
-
app
Pa s
apparent viscosity
-
kg m–3
density
- Pa
shear stress 相似文献
13.
The knowledge of rheological behaviour of juices and fruit derivatives is very useful both in the prediction of their stability
and in process design, and it depends on the type of juice and on the raw material with which they are produced. Most of the
equations that have been used to quantify flow behaviour describe the evolution of shear stress with the change of shear rate.
Nevertheless, the essential variable in equipment design is viscosity. In this way, a mathematical model to easily describe
the evolution of apparent viscosity of these non-Newtonian fluids with the shear rate would be very useful. In this work,
a mathematical expression has been developed, fitted to experimental data and compared with the Herschel–Bulkley one. The
obtained parameters with concentrated orange juice followed these trends: equilibrium apparent viscosity (η
∞) scarcely changed with temperature. Static apparent viscosity (η
0) decreased with increasing temperature, contrary to what happened with the flow behaviour constant k. 相似文献
14.
S. J. Warren E. Keshavarz-Moore P. Ayazi Shamlou M. D. Lilly C. R. Thomas K. Dixon 《Bioprocess and biosystems engineering》1995,13(1):45-48
Fermentation experiments were performed to obtain time-dependent data on broth rheology for three filamentous microorganisms, Streptomyces rimosus, Actinomadura roseorufa and Saccharopolyspora erythraea, cultivated under standard conditions in a mechanically stirred bioreactor. Rheological data were successfully analysed using Mitschka's technique and flow curves of the cultures described by the power law model in the range of shear rate between 5 and 100 s–1. Consistency coefficients of the cultures were found to vary continuously with fermentation time while flow behaviour index fell sharply within the first few hours of cultivation and then remained practically unchanged till the end of fermentation. The pH of the biomass was found to have a strong influence on both consistency coefficient and flow behaviour index.List of Symbols
k
n
Mitschka shear rate constant
-
K
consistency coefficient (Pa s
n
)
-
n
flow behaviour index (–)
-
N
spindle speed (rps)
-
T
torque on spindle (Nm)
-
gg
A
average shear rate (s–1) 相似文献
15.
Purple Loosestrife is rapidly displacing native vegetation in North American wetlands. Associated changes in wetland plant
communities are well understood. Effects of Loosestrife invasion on nutrient cycling and decomposition rates in affected wetlands
are unknown, though potentially of significance to wetland function. We used litter bag methods to quantify decomposition
rates and phosphorus concentrations of purple Loosestrife (Lythrum salicaria) and native cattails (Typha spp.) in fourteen Minnesota wetlands. A 170-day study that began in autumn modeled decomposition of Loosestrife leaves. Loosestrife
stems andTypha shoots that had overwintered and fragmented were measured in a 280- day study that began in spring. In general, Loosestrife
leaves decomposed most rapidly of the three;Typha shoots decomposed faster than Loosestrife stems. Significant decay coefficients (k-values) were determined by F-testing single
exponential model regressions of different vegetation types in the fourteen wetlands. Significant decay coefficients were:k = 2.5 × 10−3 and 4.32 × 10−3 for all Loosestrife leaves (170 d);k = 7.2 × 10−4 and 1.11 × 10−3 for overwintered Loosestrife stems (280-d) andk = 7.9 × 10−4, 1.42 × 10−3 and 2.24 × 10−3 for overwinteredTypha shoots (280-d). Phosphorus concentrations of plant tissue showed an initial leaching followed by stabilization or increase
probably associated with microbial growth. Loosestrife leaves had twice the phosphorus concentration of Loosestrife stems
andTypha shoots. Our results indicate that conversion of wetland vegetation from cattails to Loosestrife may result in significant
change in wetland function by altering timing of litter input and downstream phosphorus loads. Conversion of a riverine, flow-
through wetland fromTypha to Loosestrife may effectively accelerate eutrophication of downstream water bodies. Impacts of Loosestrife invasion must
be considered when wetlands are managed for wildlife or for improvement of downstream water quality. 相似文献
16.
Bead-bead collisions have been characterized using the velocity of the smallest turbulent eddies to calculate a turbulent collision severity (defined as the energy of collisions times their frequency), but a shear-based collision mechanism with a different dependence on the system variables is also applicable. This shearbased mechanism and the ratio of smallest eddy size to microcarrier diameter can explain the beneficial effects of both smaller diameter microcarriers and higher viscosity of the medium on the growth rate of bovine embryonic kidney cells. Death rates of these cells have also been measured at several levels of agitation. The decrease in apparent growth rate from increasing agitation is caused both by a higher rate of cell death as well as a lower intrinsic growth rate.List of Symbols
B
unspecified biological variable
-
d cm
bead diameter
-
d
i
cm
impeller diameter
-
e
error in estimate of power number
-
F
n
, F
s
(g·cm)/s2
normal and shear forces on a cell
- Fr
Froude number
-
g 980cm/s2
acceleration of gravity
-
k k–1
first order death rate constant
-
m g
mass of a bead
-
n s–1
impeller rotational rate
-
n
b
number of impeller blades
-
N
p
impeller power number
-
R
i
cm
impeller leading edge radius
-
TCS (g·cm2)/s3
turbulent collision severity
-
V cm3
reactor volume
-
v
br
cm/s rms
relative velocity between beads
-
v
e
cm/s
velocity in smallest eddies
-
X number of cells/cm3
cell population
Greek Symbols
volume fraction microcarriers
-
s–1
shear rate
-
cm2/s3
turbulent power dissipation rate
-
cm
size of smallest eddies
-
g/(cm·s)
dynamic viscosity
-
h–1
apparent growth rate of cells
-
0 h–1
intrinsic growth rate of cells in absence of death
-
v cm2/s
kinematic viscosity
-
b
g/cm3
bead density
-
f
g/cm3
fluid density
-
g/(cm·s2)
shear stress 相似文献
17.
Noscoc
flagelliforme is a terrestrial macroscopic cyanobacterium with high economic value. Free-living cells that were separated from a natural
colony of N. flagelliforme were cultivated in a 20-L photobioreactor for 16 days at five agitation rates with impeller tip speeds at 0.3, 0., 0.8, 1.0,
and 1.5 m·s−1. With different impeller tip speeds there were significant differences in the cell growth and polysaccharide production,
and different types of cell colonies appeared because of different shear forces caused by agitation. At harvest time, cell
concentrations with tip speeds of 0.8 and 1.0 m·s−1 were clearly higher than those with the other three tip speeds, but dry cell weights with the tip speeds of 0.3, 0.5, 0.8,
and 1.0 m·s−1 were almost the same. The highest RPS (polysaccharide that released into liquid medium) production was obtained with the
tip speeds of 0.8 and 1.0 m·s−1, while the highest EPS (polysaccharide that formed capsule or slime layer) production was obtained with the tip speed of
0.5 m·s−1. The tip speed of 1.5 m·s−1 was harmful for both cell growth and polysaccharide production, indicating that an appropriate shear force was needed in
the liquid suspension culture of N. flagelliforme. 相似文献
18.
F. Vendruscolo L. O. Pitol B. A. M. Carciofi D. E. Moritz J. B. Laurindo W. Schmidell J. L. Ninow 《Journal of Biorheology》2010,24(1):29-35
The objectives of this work were the construction and adaptation of a vane system in a rotational rheometer; calibration of
vane system using a mineral oil, and determination of rheological properties of the broth fermentation of Monascus ruber CCT 3802 at high cell density. Batch fermentation was carried out with glucose as the sole carbon source in a Bioflo III
bioreactor. The consistency index (K) and flow behavior index (n) of the broth fermentation of M. ruber were characterized at different biomass concentrations and were adequately described by a power law model. The K and n values were significantly affected by biomass concentrations. K values ranged from 0.375 to 11.002 Pa s
n
when evaluated at biomass concentrations from 25.67 to 63.20 g L−1. The pseudoplastic behavior was confirmed by values of n that ranged between 0.157 and 0.254. Simple empirical correlations have been proposed to quantify the dependence of the power
law terms on fungal biomass concentration. 相似文献
19.
Tank-treading (TT) motion is established in optically trapped, live red blood cells (RBCs) held in shear flow and is systematically investigated under varying shear rates, temperature (affecting membrane viscosity), osmolarity (resulting in changes in RBC shape and cytoplasmic viscosity), and viscosity of the suspending medium. TT frequency is measured as a function of membrane and cytoplasmic viscosity, the former being four times more effective in altering TT frequency. TT frequency increases as membrane viscosity decreases, by as much as 10% over temperature changes of only 4°C at a shear rate of ∼43 s−1. A threshold shear rate (1.5 ± 0.3 s−1) is observed below which the TT frequency drops to zero. TT motion is also observed in shape-engineered (spherical) RBCs and those with cholesterol-depleted membranes. The TT threshold is less evident in both cases but the TT frequency increases in the latter cells. Our findings indicate that TT motion is pervasive even in folded and deformed erythrocytes, conditions that occur when such erythrocytes flow through narrow capillaries. 相似文献
20.
2-Vinylfuran derivatives were found to inhibit algal and yeast growth.
Experiments with a respiratory type ofSaccharomyces cerevisiae DT XII, its respiration-deficient mutant DT XII A, andCandida albicans showed that all 2-vinylfurans are inhibitors of key processes of energy metabolism (especially glycolysis). The properties
determining the inhibitory activity are chemical reactivity and lipophilicity. The reactivity of the studied derivatives was
characterized by second-order rate constantsk (L. mol−1.s−1) for reaction with mercaptoacetic acid (as a model thiol), and the lipophilicity by calculated Σπi. An equation correlating the structure and the activity of 2-vinylfurans was derived.
The significance of reactions of 2-vinylfurans with thiols or other nucleophilic groups of cell components is stressed. The
reaction centre of 2-vinylfurans in these reactions is the electrophilic exocyclic double bond. The presence of a nitro group
in position 5 of the furan ring is not indispensable for biological activity of 2-vinylfurans. 相似文献