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1.
Understanding how photosynthetic capacity acclimatises when plants are grown in an atmosphere of rising CO2 concentrations will be vital to the development of mechanistic models of the response of plant productivity to global environmental change. A limitation to the study of acclimatisation is the small amount of material that may be destructively harvested from long-term studies of the effects of elevation of CO2 concentration. Technological developments in the measurement of gas exchange, fluorescence and absorption spectroscopy, coupled with theoretical developments in the interpretation of measured values now allow detailed analyses of limitations to photosynthesisin vivo. The use of leaf chambers with Ulbricht integrating spheres allows separation of change in the maximum efficiency of energy transduction in the assimilation of CO2 from changes in tissue absorptance. Analysis of the response of CO2 assimilation to intercellular CO2 concentration allows quantitative determination of the limitation imposed by stomata, carboxylation efficiency, and the rate of regeneration of ribulose 1:5 bisphosphate. Chlorophyll fluorescence provides a rapid method for detecting photoinhibition in heterogeneously illuminated leaves within canopies in the field. Modulated fluorescence and absorption spectroscopy allow parallel measurements of the efficiency of light utilisation in electron transport through photosystems I and IIin situ.Abbreviations A
net rate of CO2 uptke per unit leaf area (µmol m–2 s–1)
- Asat
light-saturated A
- A820
change in absorptance of PSI on removal of illumination (OD)
- c
CO2 concentration in air (µmol mol–1)
- ca
c in the bulk air; ci, c in the intercellular spaces
- ce
carboxylation efficiency (mol m–2 s–1)
- E
transpiration per unit leaf area (mol m–2 s–1)
- F
fluorescence emission of PSII (relative units)
- Fm
maximal level of F
- Fo
minimal level of F upon illumination when PSII is maximally oxidised
- Fs
the steady-state F following the m peak
- Fv
the difference between Fm and Fo
- F'm
maximal F' generated after the m peak by addition of a saturating light pulse
- F'o
the minimal level of F' after the m peak determined by re-oxidising PSII by far-red light
- g1
leaf conductance to CO2 diffusion in the gas phase (mol m–2 s–1)
- g'1
leaf conductance to water vapour diffusion in the gas phase (mol m–2 s–1)
- kc and ko
the Michaelis constants for CO2 and O2, respectively, (µmol mol–1);
- Jmax
the maximum rate of regeneration of rubP (µmol m–2 s–1)
- l
stomatal limitation to CO2 uptake (dimensionless, 0–1)
- LCP
light compensation point of photosynthesis (µmol m–2 s–1)
- oi
the intercellular O2 concentration (mmol mol–1)
- Pi
cytosol inorganic phosphate concentration
- PSI
photosystem I
- PSII
photosystem II
- Q
photon flux (µmol m–2 s–1)
- Qabs
Q absorbed by the leaf
- rubisCO
ribulose 1:5 bisphosphate carboxylase/oxygenase; rubP, ribulose 1:5 bisphosphate; s, projected surface area of a leaf (m2)
- Vc,max
is the maximum rate of carboxylation (µmol m–2 s–1)
- Wc
the rubisCO limited rate of carboxylation (µmol m–2 s1)
- Wj
the electron transport limited rate of regeneration of rubP (µmol m–2 s–1)
- Wp
the inorganic phosphate limited rate of regeneration of rubP (µmol m–2 s–1)
-
absorptance of light (dimensionless, 0–1)
- a
of standard black absorber 1, of leaf
- s
of integrating sphere walls
- , CO2
compensation point of photosynthesis (µmol mol–1)
-
the specificity factor for rubisCO carboxylation (dimensionless)
- ,
convexity of the response of A to Q (dimensionless 0–1)
-
the quantum yield of photosynthesis on an absorbed light basis (A/Qabs; dimensionless)
-
the quantum yield of photosynthesis on an incident light basis (A/Q; dimensionless)
- app
the maximum
- m
the maximum
- m,app
the photochemical efficiency of PSII (dimensionless, 0–1)
- PSII,m
the maximum 相似文献
2.
Hans Mulder Harry Schachter Jerry R. Thomas Koen M. Halkes Johannis P. Kamerling Johannes F. G. Vliegenthart 《Glycoconjugate journal》1996,13(1):107-113
Connective tissue of the freshwater pulmonateLymnaea stagnalis was shown to contain fucosyltransferase activity capable of transferring fucose from GDP-Fuc in 1–2 linkage to terminal Gal of type 3 (Gal1–3GalNAc) acceptors, and in 1–3 linkage to GlcNAc of type 2 (Gal1–4GlcNAc) acceptors. The 1–2 fucosyltransferase was active with Gal1–3GalNAc1-OCH2CH=CH2 (K
m=12 mM,V
max=1.3 mU ml–1) and Gal1–3GalNAc (K
m=20 mM,V
max=2.1 mU ml–1), whereas the 1–3 fucosyltransferase was active with Gal1–4GlcNAc (K
m=23 mM,V
max=1.1 mU ml–1). The products formed from Gal1–3GalNAc1-OCH2CH=CH2 and Gal1–4GlcNAc were purified by high performance liquid chromatography, and identified by 500 MHz1H-NMR spectroscopy and methylation analysis to be Fuc1–2Gal1–3GalNAc1-OCH2CH=CH2 and Gal1–4(Fuc1–3)GlcNAc, respectively. Competition experiments suggest that the two fucosyltransferase activities are due to two distinct enzymes.Abbreviations 2Fuc-T
1–2 fucosyltransferase
- 3Fuc-T
1–3 fucosyltransferase
- MeO-3Man
3-O-methyl-D-mannose
- MeO-3Gal
3-O-methyl-D-galactose 相似文献
3.
Oxygen and shear stress are the key factors for enhanced glucan production with Schizophyllum commune. During batch cultivation control of
or
(specific oxygen uptake rate) was achieved by variation of the impeller speed. Biomass was modelled by using the carbon and oxygen balance derived from exhaust data. At mycel growth a
of 0.042 h–1 presents just the border before oxygen limitation arises and is simultaneously the optimum operation condition for maximum glucan formation. Related to an overall cultivation time of 72 h a maximum of both productivity (4.3 kg m–3 d–1) and yield (13 kg m–3) were obtained.List of Symbols
C kg m–3
concentration
-
k
L
a
h
–1
volume related oxygen transfer coefficient
-
K
s
mol m–3
substrate saturation constant
-
N rpm
impeller speed
-
%
oxygen partial pressure of the liquid phase
-
kg m–3h–1
oxygen uptake rate
-
h–1
specific oxygen uptake rate, kg O2 (kg biomass h)–1
-
t h
time
-
yield coefficient (biomass formed/oxygen consumed)
Greek Symbols
h–1
specific growth rate
Indices
O
2
oxygen
-
X
biomass
-
L
liquid phase
- *
gas/liquid interface
-
S
substrate (glucose)
Dedicated to the 65th birthday of Professor Fritz Wagner.This work was kindly supported in parts by B. Braun Biotech International. The authors are grateful to Prof. Dr. Fritz Wagner for scientific support and appreciate the technical assistance of Detlev Rasch 相似文献
4.
Summary By applying photographic, electrical conductivity, and electrooptical methods, the transverse variation of bubble size and velocity, the local gas hold up, and the local specific gas/liquid interfacial area were estimated in a bench scale bubble-column bioreactor containing model cultivation media. The liquid velocity profile, the transverse turbulence intensity variations, and the turbulence energy dissipation scale were also measured by a hot film turbulence probe and constant temperature anemometer technique.A significant relationship was found between the two-phase flow fluid dynamical state and the transverse variation of the various properties.Symbols M
mass
- L
length
- T
time
- a
gas/liquid interfacial area L2
-
specific gas/liquid interfacial area with regard to the bubbling layer volume L–1
- D
transverse coordinate (measured from the wall of the column) L
- d
bubble diameter L
- d
mean bubble diameter L
- de
dynamic equilibrium (maximum stable) bubble diameter L
- dp
primary bubble diameter L
- ds
Sauter bubble diameter L
- E
specific energy dissipation rate with regard to the volume of the liquid ML–1T–3
- EVL
energy dissipation rate ML2T–3
-
, since =1 g/cm3, E has the same numerical value as E. Therefore, the symbol E is used everywhere in the present paper for E for simplicity and called energy dissipation rate (S.s–2=Stokes.s–2) L2T–3
- EG or
local relative gas holdup
- f (r)
cross correlation function
- g
acceleration of gravity LT–2
- h
longitudinal distance from the aerator L
-
relative turbulence intensity
- NO
number of u and crossings T–1
- nB
bubble frequency T–1
- r
distance between two points 1 and 2 of the cross correlation function L
- t
time
- u
instantaneous liquid velocity LT–1
-
mean liquid velocity LT–1
-
mean square fluctuation velocity L2T–2
-
turbulence intensity LT–1
- wSG
superficial gas velocity LT–1
- wSL
superficial liquid velocity LT–1
-
or EG
local relative gas holdup LT–1
-
energy dissipation scale L
-
kinematic liquid viscosity L2T–1
-
liquid density M L–3
-
surface tension M T–2
-
dynamic turbulence pressure M L–1T–2
Indices p
primary (at the aerator)
- e
equilibrium (far from the aerator) 相似文献
5.
Walter Borzani 《Biotechnology letters》1995,17(12):1295-1298
Summary The following equations represent the influence of the ethanol concentration (E) on the specific growth rate of the yeast cells () and on the specific production rate of ethanol () during the reactor filling phase in fed-batch fermentation of sugar-cane blackstrap molasses: =
0 - k · E and v = v
0
· K/(K +E)
Nomenclature E
ethanol concentration in the aqueous phase of the fermenting medium (g.L–1)
- Em
value of E when = 0 or = 0 (g.L–1)
- F
medium feeding rate (L.h–1)
- k
empirical constant (L.g–1.h–1)
- K
empirical constant (g.L–1)
- Mas
mass of TRS added to the, reactor (g)
- Mcs
mass of consumed TRS (g)
- Me
mass of ethanol in the aqueous phase of the fermenting medium (g)
- Ms
mass of TRS in the aqueous phase of the fermenting medium (g)
- Mx
mass of yeast cells (dry matter) in the fermenting medium (g)
- r
correlation coefficient
- S
TRS concentration in the aqueous phase of the fermenting medium (g.L–1)
- Sm
TRS concentration of the feeding medium (g.L–1)
- t
time (h)
- T
temperature (° C)
- TRS
total reducing sugars calculated as glucose
- V
volume of the fermenting medium (L)
- V0
volume of the inoculum (L)
- X
yeast cells concentration (dry matter) in the fermenting medium (g.L–1)
-
filling-up time (h)
-
specific growth rate of the yeast cells (h–1)
- 0
value of when E=0
-
specific production rate of ethanol (h–1)
- 0
value of when E=0
-
density of the yeast cells (g.L–1)
-
dry matter content of the yeast cells 相似文献
6.
Gopaul Kotturi Campbell W. Robinson William E. Inniss 《Applied microbiology and biotechnology》1991,34(4):539-543
Summary Cell growth and phenol degradation kinetics were studied at 10°C for a psychrotrophic bacterium, Pseudomonas putida Q5. The batch studies were conducted for initial phenol concentrations, So, ranging from 14 to 1000 mg/1. The experimental data for 14<=So<=200 mg/1 were fitted by non-linear regression to the integrated Haldane substrate inhibition growth rate model. The values of the kinetic parameters were found to be: m=0.119 h–1, K
S=5.27 mg/1 and K
I=377 mg/1. The yield factor of dry biomass from substrate consumed was Y=0.55. Compared to mesophilic pseudomonads previously studied, the psychrotrophic strain grows on and degrades phenol at rates that are ca. 65–80% lower. However, use of the psychrotrophic microorganism may still be economically advantageous for waste-water treatment processes installed in cold climatic regions, and in cases where influent waste-water temperatures exhibit seasonal variation in the range 10–30°C.Nomenclature
K
S
saturation constant (mg/l)
-
K
I
substrate inhibition constant (mg/l)
-
specific growth rate (h–1)
- m
maximum specific growth rate without substrate inhibition (h–1)
- max
maximum achievable specific growth rate with substrate inhibition (h–1)
- S
substrate (phenol) concentration (mg/l)
- So
initial substrate concentration (mg/l)
- Smax
substrate concentration corresponding to max (mg/l)
-
t
time (h)
- X
cell concentration, dry basis (mg DW/l)
- Xf
final cell concentration, dry basis (mg DW/l)
- Xo
initial cell concentration, dry basis (mg DW/l)
- Y
yield factor (mg DW cell produced/mg substrate consumed) 相似文献
7.
A. K. McConnell E. S. G. Semple C. T. M. Davies 《European journal of applied physiology and occupational physiology》1993,66(4):332-337
The present investigation examined the relationship between CO2 sensitivity [at rest (S
R) and during exercise (S
E)] and the ventilatory response to exercise in ten elderly (61–79 years) and ten younger (17–26 years) subjects. The gradient of the relationship between minute ventilation and CO2 production (
E/
CO2) of the elderly subjects was greater than that of the younger subjects [mean (SEM); 32.8 (1.6) vs 27.3 (0.4); P<0.01]. At rest, S
R was lower for the elderly than for the younger group [10.77 (1.72) vs 16.95 (2.13) 1 · min–1 · kPa–1; 1.44 (0.23) vs 2.26 (0.28) 1 · min–1 · mmHg–1; P<0.05], but S
E was not significantly different between the two groups [17.85 (2.49) vs 19.17 (1.62) l · min–1 · kPa–1; 2.38 (0.33) vs 2.56 (0.21) 1 · min–1 · mmHg–1]. There were significant correlations between both S
R and S
E, and
E/
CO2 (P<0.05; P<0.001) for the younger group, bot none for the elderly. The absence of a correlation for the elderly supports the suggestion that
E/
CO2 is not an appropriate index of the ventilatory response to exercise for elderly humans. 相似文献
8.
Analysis of gas exchange in seedlings of Acer saccharum: integration of field and laboratory studies
In the field, photosynthesis of Acer saccharum seedlings was rarely light saturated, even though light saturation occurs at about 100 mol quanta m-2 s-1 photosynthetic photon flux density (PPFD). PPFD during more than 75% of the daylight period was 50 mol m-2 s-1 or less. At these low PPFD's there is a marked interaction of PPFD with the initial slope (CE) of the CO2 response. At PPFD-saturation CE was 0.018 mol m-2 s-1/(l/l). The apparent quantum efficiency (incident PPFD) at saturating CO2 was 0.05–0.08 mol/mol.
and PPFD-saturated CO2 exchange was 6–8 mol m-2 s-1. The ratio of internal CO2 concentration to external (C
i
/C
a
) was 0.7 to 0.8 except during sunflecks when it decreased to 0.5. The decrease in C
i
/C
a
during sunflecks was the result of the slow response of stomates to increased PPFD compared to the response of net photosynthesis. An empirical model, which included the above parameters was used to simulate the measured CO2 exchange rate for portions of two days. Parameter values for the model were determined in experiments separate from the daily time courses being sumulated. Analysis of the field data, partly through the use of simulations, indicate that the elimination of sunflecks would reduce net carbon gain by 5–10%.List of symbols
A
measured photosynthetic rate under any set of conditions (mol m-2 s-1)
-
A
m
(atm)
measured photosynthetic rate at saturating PPFD, 350 l/l CO2 and 21% (v/v) O2 (mol m-2 s-1)
-
C
constant in equation of Smith (1937, 1938)
-
C
a
CO2 concentration in the air (l/l)
-
C
i
CO2 concentration in the intercellular air space (l/l)
-
C
i
/*
C
i
corrected for CO2 compensation point, i.e., C
i
-I
*, (l/l)
- CE
initial slope of the CO2 response of photosynthesis (mol m-2 s-1/(l/l))
- CEM
CE at PPFD saturation
-
E
transpiration rate (mmol m-2 s-1)
-
F
predicted photosynthetic rate (mol m-2 s-1)
-
G
leaf conductance to H2O (mol m-2 s-1)
-
I
photosynthetic photon flux density (mol m-2 s-1)
-
N
number of data points
-
P
m
predicted photosynthetic rate at saturating CO2 and given PPFD (mol m-2 s-1)
-
P
ml
predicted photosynthetic rate at saturating CO2 and PPFD (mol m-2 s-1)
-
R
d
residual respiratory rate (mol m-2 s-1)
-
T
a
air temperature (°C)
-
T
l
leaf temperature (°C)
-
V
reaction velocity in equation of Smith (1937, 1938)
-
V
max
saturated reaction velocity in equation of Smith (1937, 1938)
- VPA
vapor pressure of water in the air (mbar/bar)
- VPD
vapor pressure difference between leaf and air (mbar/bar)
-
X
substrate concentration in equation of Smith (1937, 1938)
-
initial slope of the PPFD response of photosynthesis at saturating CO2 (mol CO2/mol quanta)
- (atm)
initial slope of the PPFD response of photosynthesis at 340 l/l CO2 and 21% (v/v) O2 (mol CO2/mol quanta)
-
I
*
CO2 compensation point after correction for residual respiration (l/l)
-
PPFD compensation point (mol m-2 s-1) 相似文献
9.
J. -P. Ewert H. -A. Häeter 《Journal of comparative physiology. A, Neuroethology, sensory, neural, and behavioral physiology》1969,64(2):135-153
Zusammenfassung Durch simultane visuelle Bewegungsreize, die von mehreren Beutetieren (z.B. Mehlkäferlarven) ausgehen, wird der Beutefang der Erdkröte (Bufo bufo L.) gehemmt. An diese Verhaltensheobaehtung anknüpfend, wurde die Abhängigkeit dieses inhibitorischen Umfeldeffektes von verschiedenen visuellen Reizparametern im Attrappen versuch quantitativ gemessen: Im frontalen Gesichtsfeld der Kröte rotierte vor dunklem Hintergrund eine weiße, rechteckige, 2,5 × 20° große Beuteattrappe (Zentralattrappe, z) mit dem Rechteckzentrum im Drehpunkt. Zusätzlich konnten mehrere Kreisscheiben von 5 bzw. 10° (Peripherattrappen, p) um die Zentralattrappe bewegt werden.Die Beutefangaktivität R
z [Beutefangreaktionen x min–1] auf die allein gebotene Zentralattrappe war bei einer Sehwinkelgeschwindigkeit v
s der distalen Attrappenkanten 10v
s30 [grad x see–1] maximal und sank für kleinere oder größere Winkelgeschwindigkeiten wieder ab.
Eine mit v
s=25 [grad x sec–1] allein bewegte Peripherattrappe löste maximale Beutefangaktivität R
p aus. Mit zunehmender Anzahl n
p simultan bewegter Peripherattrappen sank die Beutefangaktivität ab.Mehrere, um den gleichen Drehpunkt bewegte Peripherattrappen, deren Abstand untereinander
=10° betrug, blieben von der Kröte unbeantwortet. Sie bildeten ein inhibitorisches Umfeld und hemmten dadurch die Reaktion auf die gleichzeitig bewegte Zentralattrappe z. — Die im Simultanreizungsversuch gemessene Beutefangaktivität R
zp war abhängig vom Abstand
[grad] zwischen Zentralattrappe und Peripherattrappen (
: Kürzester Abstand zwischen z und p): Für
=10° war R
zp0 und stieg für
>10° an. — Kontrollversuche, die jeweils auf die Simultanreizung mit z allein folgten (R
z), ließen eine
-abhängige Nachhemmung erkennen. — Die hemmende Wirkung auf die Beantwortung von z war auch von der Sehwinkelgeschwindigkeit v
s der Peripherattrappen abhängig; sie war bei derjenigen Sehwinkelgeschwindigkeit (v
s=25 [grad × sec–1]) maximal, mit der die Zentralattrappe, allein geboten, maximale Beutefangaktivität auslöste; für v
sg25 [grad × sec–1] nahm die Hemmung wieder ab.Die Versuchsergebnisse lassen auf inhibitorische Verknüpfungen innerhalb des zentralen visuellen Systems schließen. Es wird vermutet, daß die Reiz-Verhaltens-reaktionsbeziehungen in den visuellen Simultanreizungsversuchen durch eine Art zentrale laterale Inhibition bestimmt werden.
Mit Unterstützung der Deutschen Forschungsgemeinschaft (Ew 7/4+5). 相似文献
Inhibitory effect of simultaneously moved prey dummies on the prey catching behaviour of the common toad (Bufo bufo L.)
Summary The prey catching behaviour of the toad (Bufo bufo L.) is generally inhibited by simultaneously visual moving stimuli caused by a group of prey animals (mealworms). According to this behavioural observation the dependence of this inhibitory effect on several visual parameters were quantitatively measured in dummy experiments: in the frontal visual field of the toad a white rectangular prey dummy of 2,5×20° (central dummy, z) was rotating in a centre against dark background. In addition several disks of 5 or 10° diameter (peripheral dummies, p) could simultaneously rotate around the central dummy (Figs. 1 and 7).The prey catching activity R z [catching reactions x min–1] released by rotation of only the central dummy z increased with increasing angular velocity v s of the stimulus distal edges, reaching a maximum for 10vs30 [degrees x sec–1] and decreasing for v s>30 [degrees x sec–1] (Fig. 5).A single peripheral dummy p, moved at v s=25 [degrees x sec–1], released maximal catching activity R p. The activity R p decreased with the increasing number n p of simultaneously offered dummies (Fig. 6).The prey catching behaviour of the toad was inhibited, when several peripheral dummies p were moved around the centre with a distance =10° from each other. They caused an inhibitory field and they also inhibited the response to a simultaneously moved central dummy z. The prey catching activity, measured in experiments in which z and p rotated simultaneously, depends on the distance [degrees] between z and p ( being the shortest distance between z and p). For =10°, R zp was zero; R zp increased for >10° (Figs. 9 and 10). — Control experiments carried out with z allone — after having applied the simultaneous stimulation — showed a - dependent after-inhibition (Fig. 9). — The inhibitory effect on the response to z also depended on the angular velocity v s of p; the inhibition was at a maximum for v s25 [degrees x sec–1], and it decreased for v s25 [degrees x sec–1] (Fig. 11).The experimental results suggest inhibitory interactions within the central visual system. It is supposed that the relation between stimulus and behavioural reaction in simultaneous stimulating experiments results from some kind of central nervous lateral inhibition.
Mit Unterstützung der Deutschen Forschungsgemeinschaft (Ew 7/4+5). 相似文献
10.
B. Šantek P. Horvat S. Novak B. Mayr A. Moser V. Marić 《Bioprocess and biosystems engineering》1996,14(4):195-204
The construction of the horizontal rotating tubular bioreactor (HRTB) represents a combination of a thin-layer bioreactor and a biodisc reactor. The bioreactor was made of a plastic tube whose interior was divided by the O-ring shaped partition walls. For the investigation of mixing properties in HRTB the temperature step method was applied. The temperature change in the bioreactor as a response to a temperature step in the inlet flow was monitored by six Pt-100 sensors (t
90 response time 0.08 s and resolution 0.002 °C) which were connected with an interface unit and personal computer. Mixing properties of the bioreactor were modeled using the modified tank in series concept which divided the bioreactor into ideally mixed compartments. A mathematical mixing model with simple flow was developed according to the physical model of the compartments network and corresponding heat balances. Numerical integration of an established set of differential equations was done by the Runge-Kutt-Fehlberg method. The final mathematical model with simple flow contained four adjustable parameters (N1,Ni, F
cr
andF
p
) and five fixed parameters.List of Symbols
A
u
m2
inner surface of bioreactor's wall
-
A
ui
m2
i-th part of inner surface of bioreactor's wall
-
A
v
m2
outlet surface of bioreactor's wall
-
A
vi
m2
i-th part of outlet surface of bioreactor's wall
-
C
p
kJ kg–1 K–1
heat capacity of liquid
-
C
pr
kJ kg–1 K–1
heat capacity of bioreactor's wall
-
D h–1
dilution rate
-
E °C °C–1 h–1
error of mathematical model
-
F
cr
dm3s–1
circulation flow in the model
-
F
p
dm3 s–1
back flow in the model
-
F
t
dm3s–1
inlet flow in the bioreactor
-
I °C
intensity of temperature step, the difference in temperature between the temperature of the inlet liquid flow and the temperature of liquid in the bioreactor before the temperature step
-
K1 Wm–2K–1
heat transfer coefficient between the liquid and bioreactor's wall
-
K2 Wm–2K–1
heat transfer coefficient between the bioreactor's wall and air
-
m
s kg
mass of bioreactor's wall
-
L m
length of bioreactor
-
L
k
m
wetted perimeter of bioreactor
-
n min–1
rotational speed of bioreactor
-
n
s
number of temperature sensors
-
N1
number of cascades
-
Ni
number of compartments inside the cascade
-
Nu
Nusselt number
-
Pr
Prandtl number
-
r
u
m
inner diameter of bioreactor
-
r
v
m
outside diameter of bioreactor
-
Re
Reynolds number
-
s(t)
step function
-
t s
time
-
T °C
temperature
-
T
c
°C
calculated temperature
-
T
m
°C
measured temperature
-
T
N1,Ni
°C
temperature of liquid in a defined compartment inside cascade
-
T
N1,S
°C
temperature of defined part of bioreactor's wall
-
T
S
°C
temperature of bioreactor's wall
-
T
v
°C
temperature of liquid in bioreactor
-
T
z
°C
temperature of surrounding air
-
V
t
dm3
volume of liquid in the bioreactor
Greek Symbols
kJm–1s–1 K–1
thermal conductivity of liquid in the bioreactor
-
kgm–3
density of liquid in the bioreactor
-
m2s–1
kinematic viscosity of liquid in the bioreactor
Matrix Coefficient
B
-
C
-
D
-
E
B+C+D
-
G1
-
G2
-
G3
-
A
ui
-
A
vi
-
Q
1
-
Q
2
-
Q
3
相似文献
11.
Three layer control structure is proposed for optimal control of continuous fermentation processes. The start-up optimization problems are solved as a first step for optimization layer building. A steady state optimization problem is solved by a decomposition method using prediction principle. A discrete minimum time optimal control problem with state delay is formulated and a decomposition method, based on an augmented Lagrange's function is proposed to solve it. The problem is decomposed in time domain by a new coordinating vector. The obtained algorithms are used for minimum time optimal control calculation of Baker's Yeast fermentation process.List of Symbols
x(t) g/l
biomass concentration
-
s(t) g/l
limiting substrate concentration
-
x
0 g/l
inlet biomass concentration
-
s
0(t) g/l
inlet substrate concentration
-
D(t) h–1
dilution rate
- (t) h–1
specific growth rate
-
Y g/g
yield coefficient
-
(t) h–1
specific limiting substrate consumption rate
-
k
D
h–1
disappearing constant
-
w
1, w
2
known constant or piece-wise disturbances
-
m
h–1
maximum specific growth rate
-
k
s
g/l
Michaelis-Menten's parameter
-
h
time delay
-
x
0, s
0 g/l
initial concentrations
-
¯x, ¯s, ¯D
optimal steady state value
-
V
min
, V
max
, v=x,s,d,t
bounds of variables
-
t h
sampling period
-
K
number of steps in the optimization horison
-
Js, J
d
performance indexes
-
L
s
Lagrange's function
-
L
d
Lagrange's functional
-
0
weighting coefficient for the amount of the limiting substrate throwing out of the fermentor
-
1, 2
dual variables of Lagrange's function
-
steps in steady state coordination procedure
-
errors values for steady state coordination process
-
v
, v=x, s
conjugate variables of Lagrange's functional
-
v
, v=x,s
penalty coefficients of augmented Lagrange's functional
-
v
, v=x, s
interconnections of the time
-
e
v
, v=x,s, D,
x
,
s
gradients of Lagrange's functional
-
j, l
indexes of calculation procedures
-
values of errors in calculations
The researches was supported by National Scientific Research Foundation under grants No NITN428/94 and No NITN440/94 相似文献
12.
Summary The photographic and electrical conductivity methods to measure the structure of two phase flow, especially bubble size, bubble frequency, local gas hold-up and, for the latter, the bubble velocity are described.Symbols
specific interfacial area
- a
gas/liquid interfacial area
- B
constant in Eq. (4)
- d
diameter of the bubbles
- d
mean diameter of the bubbles
- dS
Sauter diameter
- EG
relative gas hold up
- I
current
- kL
mass transfer coefficient across the gas/liquid interface
- kL
local kL
-
LT–1
-
LT–1
-
1
longitudinal distance between the start and stop sensors
-
1B
pierced length of the bubble
- t
time
-
t1
length of the square-wave signal at the start sensor
-
t2
length of the square-wave signal at the stop sensor
-
t12
time delay between start and stop signals
- V
volume of the bubbling layer
- VL
volume of the bubble free layer
- VB
bubble volume
- vB
bubble velocity 相似文献
13.
Summary A constant temperature hot film anemometer has been used to evaluate mean liquid flow velocity, bubble frequency, turbulence scale and intensity, and the rate of energy dissipation by liquid phase bubble flow.Symbols M
mass
- L
lenght
- T
time
- a
gas/liquid interfacial area L2
- a=a/VL
specific gas/liquid interfacial area with regard to the volume of the liquid L–1
- d
bubble diameter L
- d
mean bubble diameter L
- de
dynamic equilibrium (maximum stable) bubble size L
- dp
primary bubble diameter L
- ds
Sauter bubble diameter L
- E
specific energy dissipation rate with regard to the volume of the liquid ML–1T–3
- E VL
energy dissipation rate ML2T–3
- E=E/
since =1 g cm–3, E has the same numerical value as E. Therefore, the symbol E is used everywhere in the present paper for E and called energy dissipation rate (S. s–2=Stokes. s–2) L2T–3
- EG or G
local relative gas hold up L2T–3
- f()
autocorrelation function [Eq. (10)] L2T–3
- f(r)
cross correlation function [Eq. (11)] L2T–3
- g
acceleration of gravity LT–2
- k
constant LT–2
- kL
mass transfer coefficient LT–1
- kLa
volumetric mass transfer coefficient with regard to the volume of the liquid T–1
- N0
number of crossings of u and T–1
- nB
bubble frequency T–1
- r
distance between two points 1 and 2 of the cross correlation function L
- t
time T
- u
momentaneous liquid velocity LT–1
-
mean liquid velocity LT–1
-
mean square fluctuation velocity L2T–2
-
intensity of turbulence LT–1
- x
position coordinate L
- V
volume of the bubbling layer in the column L3
- VL
volume of the bubble free layer in the column L3
- V
electrical voltage (in Fig. 2) L3
- v
velocity scale [Eq. (6)] LT–1
- Wecrit
critical Weber number [Eq. (4)] LT–1
- wSG
superficial gas velocity LT–1
- wSL
superficial liquid velocity LT–1
- G or EG
local relative gas hold up LT–1
-
smallest scale [Eq. (6)] L
-
time delay in the autocorrelation function [Eq. (10)] T
-
energy dissipation scale [E. (15)] L
- f:
Taylor's vorticity scale [E. (14)] L
-
kinematic viscosity of the liquid L2T–1
-
density of the liquid ML–3
-
surface tension MT–2
-
dynamic pressure of the turbulence [Eq. (8)] ML–1T–2
- p
primary (at the aerator)
- e
equilibrium (far from the aerator) 相似文献
14.
Thomas H. Dietz S. Y. Graves 《Journal of comparative physiology. B, Biochemical, systemic, and environmental physiology》1981,143(2):185-190
Summary Isolated gills of the freshwater mussel,Ligumia subrostrata, accumulate Na from a pondwater bathing medium. The rate of Na transport by the isolated gill is 13.2±1.1 mol (g dry gill·10 min)–1 which equals or exceeds the estimated Na transport rate of intact animals. Sodium influx is saturable with aV
max of 13.6±1.2 mol (g dry gill·10 min)–1 and an affinity (K
s) of 0.17 mM Na/l. The isolated gills survive prolonged exposure to pondwater with a constant
of 890 l O2 (g dry gill·h)–1 over a 4 h period. Sodium transport in the isolated gills is stimulated 80% above control values by 10–4 M serotonin, 60% by 0.5 mM cAMP and 60% by 12.5 g/ml nystatin. Sodium influx is inhibited by 0.5 mM amiloride and 1 mM lithium. 相似文献
15.
Enhancement of protein precipitate strength and density by low-frequency conditioning 总被引:1,自引:0,他引:1
Dr. N. J. Titchener-Hooker Dr. R. V. McIntosh 《Bioprocess and biosystems engineering》1992,8(1-2):91-97
The use of a continuous, low-frequency conditioning process to alter the structure of protein precipitate aggregates is examined. An increase in the density of aggregates is correlated with the levels of fluid acceleration and hence hydrodynamic stress to which the aggregates are exposed during conditioning. A combination of low-frequency conditioning followed by shear break-up (as in the feed zone to a high-speed disk-stack centrifuge) is shown to result in a precipitate suspension of increased particle size at the fine end of the distribution, and having a greater sedimentation velocity. The resistance of large aggregates to shear disruption is increased by low-frequency conditioning.List of Symbols
CR
conditioning ratio
-
CRS
conditioning ratio after shearing
-
d m
amplitude of displacement
-
D m
particle size
-
D
c m
critical size for centrifuge recovery
-
f s–1
frequency of vibration
-
G s–1
mean velocity gradient
-
Q m3/s
volumetric throughput
-
SR
shear ratio
-
t s
ageing time
Greek Symbols
s–1
mass-average shear rate
-
K
sedimentation shape factor
-
a kg/m3
aggregate density
-
f kg/m3
fluid density
-
s kg/m3
solids density
- kg/m3
aggregate-suspension density difference
-
Ns/m2
kinematic viscosity
-
amplitude of pulse ratio (ref. 23, 9)
-
s
mean residence time
-
s
solids volume fraction 相似文献
16.
The kinetics of CNProto- and CNDeutero-hemin binding to apohemoglobin A2 was investigated in a stopped-flow device in 0.05 M potassium phosphate buffer, pH 7, at 10°C. The overall kinetic profile exhibited multiple phases: Phases I–IV corresponding with heme insertion (8.5–13 × 107 M–1 s–1), local structural rearrangement (0.21–0.23 s–1), global structural event (0.071–0.098 s–1), and formation of the Fe–His bond (0.009–0.012 s–1), respectively. Kinetic differences observed between apohemoglobin A2 and apohemoglobin A (previously studied) prompted an analysis of the structures of and chains through molecular modeling. This revealed a structural repositioning of the residues not only at, but also distant from the site of the amino acid substitutions, specifically those involved in the heme contact and subunit interface. A significant global change was observed in the structure of the exon-coded 3 region and provided additional evidence for the designation of this as the subunit assembly domain. 相似文献
17.
Summary Three yeasts of the genus Candida (Candida intermedia, candida lipolytica and Candida tropicalis) were cultivated batchwise on three different carbon sources: glucose, acetate, and hexadecane. Growth curves, oxygen uptake rates, CO2 evolution rates and the amount of oxygen required for biomass production were determined. The data were compared and discussed from the point of maximum specific growth rate, maximum oxygen uptake rate, carbon conversion into CO2 and biomass, consumption of oxygen and available energy for cell synthesis. The results indicated a relationship between m
m, Ys, YO, and for different carbon sources. YO and were in the same order of magnitude for acetate (0.58 and 0.38 respectively) and hexadecane (0.45 and 0.40 respectively). These values were remarkably lower than those for glucose (1.26 and 0.54 respectively).Symbols av e–
Available electrons per mol of substrate (dimensionless)
- Eav
Energy available per mol of substrate (dimensionless)
- Cd
Dissimilated carbon (%)
-
m
Maximum specific rate of oxygen uptake (mMO2 h–1 g–1)
- RQ
CO2 evolved per O2 consumed
- mol. wt.
Molecular weight
- YATP
Biomass mass yield based on mol of ATP generated (g)
-
Biomass mass yield based on available energy (g)
- YM
Biomass mass yield based on mol of organic substrate (g)
- YO
Biomass mass yield based on oxygen consumed (gg–1)
- 1/YO
Oxygen consumed for one gram of biomass produced (gg–1)
- Ys
Biomass mass yield based on organic substrate (dimensionless)
- b
Reductance degree of biomass (equiv. available electrons/g atom carbon)
- s
Reductance degree of organic substrate (equiv. available electrons/g atom carbon)
-
Fraction of energy in organic substrate which is converted to biomass
- b
Weight fraction carbon in biomass (dimensionless)
- s
Weight fraction carbon in organic substrate (dimensionless)
- m
Maximum specific growth rate (h–1) 相似文献
18.
K. Shimizu 《Biochemical genetics》1987,25(3-4):197-203
DNA polymorphism patterns linked to the A-globin gene were analyzed in healthy Japanese using four different restriction endonucleases. The chromosomes with the A-globin gene were mapped through an evaluation of the presence of seven different restriction sites (HincII 5 to ; HindIII in G and A; HincII in, and 3 to, 1; AvaII in ; Bam-HI 3 to ). Among 36 chromosomes analyzed, 20 chromosomes had a haplotype of [+–––––+]. Among 55 individuals examined, 7 possessed a homozygous haplotye of [+–––––+]. All Japanese with the AT-globin gene had a subhaplotype of [–++–+] 5 to the -globin gene. Their major haplotypes were [–++–+–+] and [–++–++–]. It was expected that the presence of the AT-globin gene in Japanese may be deduced from subhaplotypes 5 to the -globin gene. 相似文献
19.
The Effects of Hypoxia on Three Sympatric Shark Species: Physiological and Behavioral Responses 总被引:1,自引:0,他引:1
Behavioral and physiological responses to hypoxia were examined in three sympatric species of sharks: bonnethead shark Sphyrna tiburo, blacknose shark, Carcharhinus acronotus, and Florida smoothhound shark, Mustelus norrisi, using closed system respirometry. Sharks were exposed to normoxic and three levels of hypoxic conditions. Under normoxic conditions (5.5–6.4mg l–1), shark routine swimming speed averaged 25.5 and 31.0cm s–1 for obligate ram-ventilating S. tiburo and C. acronotus respectively, and 25.0cm s–1 for buccal-ventilating M. norrisi. Routine oxygen consumption averaged about 234.6 mg O2kg–1h–1 for S. tiburo, 437.2mg O2kg–1h–1 for C. acronotus, and 161.4mg O2 kg–1 h–1 for M. norrisi. For ram-ventilating sharks, mouth gape averaged 1.0cm whereas M. norrisi gillbeats averaged 56.0 beats min–1. Swimming speeds, mouth gape, and oxygen consumption rate of S. tiburo and C. acronotus increased to a maximum of 37–39cm s–1, 2.5–3.0cm and 496 and 599mg O2 kg–1 h–1 under hypoxic conditions (2.5–3.4mg l–1), respectively. M. norrisi decreased swimming speeds to 16cm s–1 and oxygen consumption rate remained similar. Results support the hypothesis that obligate ram-ventilating sharks respond to hypoxia by increasing swimming speed and mouth gape while buccal-ventilating smoothhound sharks reduce activity. 相似文献