共查询到20条相似文献,搜索用时 15 毫秒
1.
Summary Penicillin G recovery is investigated in a continuous flotation column in the presence of different collectors which form a complex with penicillin. The performance of the penicillin recovery was investigated as a function of the mole ratio () of collector-to-penicillin and the aliphatic chain length of the collector. At =1 and low penicillin concentrations (e.g., 20 mg·1-1), high foam liquid concentrations (680 mg·l-1), low residue concentrations (12 mg·l-1) and high penicillin separation (56) can be attained. At =4 the separation increases to 150, and 95% of the penicillin can be recovered.Symbols Cp
penicillin concentration in feed (mg·l-1)
- CR
penicillin concentration in outlet liquid (mg·l-1)
- CS
penicillin concentration in foam liquid (mg·l-1)
- CS/CP
penicillin enrichment (-)
- CS/CR
penicillin separation (-)
- %
Pen in S penicillin yield in foam liquid (%)
-
VV}S
foam liquid volume flow (ml·min-1)
-
VV}P
feed (ml·min-1)
-
VVN
2
nitrogen flow rate (ml·s-1)
-
temperature 相似文献
2.
Summary Cell recovery by means of continuous flotation of the Hansenula polymorpha cultivation medium without additives was investigated as a function of the cultivation conditions as well as of the flotation equipment construction and flotation operational parameters. The cell enrichment and separation is improved at high liquid residence times, high aeration rates, small bubble sizes, increasing height of the aerated column, and diameter of the foam column. Increasing cell age and cultivation with nitrogen limitation reduce the cell separation.Symbols CP
cell mass concentration in medium g·l–1
- CR
cell mass concentration in residue g·l–1
- CS
cell mass concentration in foam liquid g·l–1
-
V
equilibrium foam volume cm3
- V
gas flow rate through the aerated liquid column cm3·s–1
- VF
feed rate to the flotation column ml/min
-
1
V
S/V foaminess s
-
mean liquid residence time in the column s 相似文献
3.
Bernard Bibal Gérard Goma Yves Vayssier Alain Pareilleux 《Applied microbiology and biotechnology》1988,28(4-5):340-344
Summary The effect of various culture conditions on growth kinetics of an homofermentative strain of the lactic acid bacterium Streptococcus cremoris were investigated in batch cultures, in order to facilitate the production of this organism as a starter culture for the dairy industry. An optimal pH range of 6.3–6.9 was found and a lactose concentration of 37 g·l-1 was shown to be sufficient to cover the energetic demand for biomass formation, using the recommended medium. The study of the effect of lactic acid concentration on growth kinetics revealed that the end-product was not the sole factor affecting growth. The strain was characterized for its tolerance towards lactic acid and a critical concentration of 70 g·l-1 demonstrated. With the product yield of 0.9 g·g-1 at non-lactose limiting conditions the lactic acid concentration of 33 g·l-1 could not explain the low growth rates obtained, implicating a nutritional limitation.Symbols
t
f
fermentation duration (h)
-
X
Biomass concentration (g·l-1)
-
X
m
maximum biomass concentration (g·l-1)
-
S
lactose concentration (g·l-1)
-
S
r
residual lactose concentration (g·l-1)
-
P
produced lactic acid concentration (g·l-1)
-
P
a
added lactic acid concentration (g·l-1)
-
P
c
critical lactic acid concentration (g·l-1)
-
specific growth rate (h-1)
- max
maximum specific growth rate (h-1)
-
R
x/S
biomass yield (g·g-1) calculated when =0
-
R
P/S
product yield (g·g-1) 相似文献
4.
Summary Some environmental affects on cell aggregation described in the literature are briefly summarized. By means of a biomass recirculation culture (Contact system), using the yeast Torulopsis glabrata, the aggregation behavior of cells in static and in dynamic test systems is described. Sedimentation times required to obtain 50 g · l–1 yeast dry matter in static systems were always higher than in dynamic ones.In addition to, influencing the biomass yield, the specific growth rate of the yeast also affected cell aggregation. The specific growth rate and therefore the aggregation could be regulated by the biomass recirculation rate as well as by the sedimenter volume.Abbreviations fo
Overflow flow rate (l·h–1)
- fR
Recycle flow rate (l·h–1)
- ft0t
Total flow rate through the fermenter (l·h–1)
- g
Gram
- h
Hour
- DR
Fermenter dilution rate due to recycle (h–1)
- DS
Fermeter dilution rate due to substrate (h–1)
- Dtot
Total fermenter dilution rate (h–1)
- l
Liter
-
Specific growth rate (h–1)
- PF
Fermenter productivity (g·l–1·h–1)
- PFS
Overall productivity (g·l–1·h–1)
- RpM
Rates per minute
- RS
Residual sugar content in the effluent with respect to the substrate concentration (%)
- Y
Yield of biomass with respect to sugar concentration (%)
-
Sed 50
Sedimentation time to reach a YDM of 50 g·l–1 (min)
- V
Volume (l)
- VF
Fermenter volume (l)
- VSed
Sedimenter volume (l)
- VVM
Volumes per volume and minute
- XF
YDM in the fermenter (g·l–1)
- XF
YDM in the recycle (g·l–1)
- XS
Yeast dry matter due to substrate concentration (g·l–1)
- YDM
Yeast dry matter (g·l–1) 相似文献
5.
S. N. Mukhopadhyay A. Ornelas Vale E. Camargo Rubio G. Cassarubias Arcos 《Applied microbiology and biotechnology》1978,6(1):55-66
Summary Submerged batch cultivation under controlled environmental conditions of pH 3.8, temperature 30°C, and KLa200 h–1 (above 180 mMO2
l
–1 h–1 oxygen supply rate) produced a maximum (12.0 g·l
–1) SCP (Candida utilis) yield on the deseeded nopal fruit juice medium containing C/N ratio of 7.0 (initial sugar concentration 25 g·l
–1) with a yield coefficient of 0.52 g cells/g sugar. In continuous cultivation, 19.9 g·l
–1 cell mass could be obtained at a dilution rate (D) of 0.36 h–1 under identical environmental conditions, showing a productivity of 7.2 g·l
–1·h–1. This corresponded to a gain of 9.0 in productivity in continuous culture over batch culture. Starting with steady state values of state variables, cell mass (CX–19.9 g·l
–1), limiting nutrient concentration (Cln–2.5 g·l
–1) and sugar concentration (CS–1.5 g·l
–1) at control variable conditions of pH 3.8, 30°C, and KLa 200 h–1 keeping D=0.36 h–1 as reference, transient response studies by step changes of these control variables also showed that this pH, temperature and KLa conditions are most suitable for SCP cultivation on nopal fruit juice. Kinetic equations obtained from experimental data were analysed and kinetic parameters determined graphically. Results of SCP production from nopal fruit juice are described.Nomenclature Cln
concentration of ammonium sulfate (g·l
–1)
- CS
concentration of total sugar (g·l
–1)
- CX
cell concentration (g·l
–1)
- D
dilution rate (h–1)
- Kln
Monod's constant (g·l
–1)
- m
maintenance coefficient (g ammonium sulfate cell–1 h–1)
- m(S)
maintenance coefficient (g sugar g cell–1 h–1)
- t
time, h
- Y
yield coefficient (g cells/g ammonium sulfate)
- Ym
maximum of Y
- YS
yield coefficient based on sugar consumed (g cells · g sugar–1)
- YS(m)
maximum value of YS
-
µm
maximum specific growth rate constant (h–1) 相似文献
6.
Summary Analysis of a large number of experimental data from the cultivation of Bacillus subtilis formed the basis for a kinetic model of the process explaining the effect of composition of the culture medium and of the growth rate on the rate of enzyme production. The resulting rate of formation of -amylase (EC 3.2.1.1) reflects the sum of the rate of enzyme production and the rate of its degradation as affected by the environment. The kinetic dependence confirms the previously described mechanism of regulation of enzyme biosynthesis. The mathematical model of the process served here to determine the optimal conditions for enzyme biosynthesis which were then verified in a fed-batch cultivation. The production of the enzyme in fed-batch culture was found to be twice that found in a batch cultivation.Symbols
X
biomass concentration, g·l-1
-
t
time, h
-
S
1
caseinate concentration, g·l-1
-
S
2
starch concentration, g·l-1
-
P
product concentration, U·ml-1
-
r
P
specific rate of product formation, U·g-1·h-1
-
R
P
total rate of product formation, U·l-1·h-1
-
Y
yield coefficient
-
specific growth rate, h-1 相似文献
7.
M. L. F. Giuseppin 《Applied microbiology and biotechnology》1984,20(3):161-165
Summary The influence of the concentration of oxygen on lipase production by the fungus Rhizopus delemar was studied in different fermenters. The effect of oxygen limitation ( 47 mol/l) on lipase production by R. delemar is large as could be demonstrated in pellet and filamentous cultures. A model is proposed to describe the extent of oxygen limitation in pellet cultures. Model estimates indicate that oxygen is the limiting substrate in shake flask cultures and that an optimal inoculum size for oxygen-dependent processes can occur.Low oxygen concentrations greatly negatively affect the metabolism of R. delemar, which could be shown by cultivation in continuous cultures in filamentous growth form (Doptimal=0.086 h-1). Continuous cultivations of R. delemar at constant, low-oxygen concentrations are a useful tool to scale down fermentation processes in cases where a transient or local oxygen limitation occurs.Symbols and Abbreviations CO
Oxygen concentration in the gas phase at time = 0 (kg·m-3)
- CO
2i
Oxygen concentration at the pellet liquid interface (kg·m-3)
- CO
2i
Oxygen concentration in the bulk (kg·m-3)
-
D
Dilution rate (h-1)
- IDO
2
Diffusion coefficient for oxygen (m2·s-1)
-
dw
Dry weight of biomass (kg)
-
f
Conversion factor (rs
O
2 to oxygen consumption rate per m3) (-)
-
k
Radial growth rate (m·s-1)
-
K
Constant
-
kla
Volumetric mass transfer coefficient (s-1)
-
klA
Oxygen transfer rate (m-3·s-1)
-
kl
Mass transfer coefficient (m·s-1)
-
K
O
2
Affinity constant for oxygen (mol·m-3)
-
K
w
Cotton plug resistance (m-3·s-1)
-
M
Henry coefficient (-)
-
NV
Number of pellets per volume (m-3)
-
R
Radius (m)
-
RO
Radius of oxygen-deficient core (m)
-
RQ
Respiration quotient (mol CO2/mol O2)
-
rs
O
2
Specific oxygen consumption rate per dry weight biomass (kg O2·s-1[kg dw]-1)
-
rX
Biomass production rate (kg·m-3·s-1)
-
SG
Soytone glucose medium (for shake flask experiments)
-
SG
4
Soytone glucose medium (for tower fermenter and continuous culture experiments)
-
V
Volume of medium (m-3)
-
X
Biomass (dry weight) concentration (kg·m-3)
-
XR
o
Biomass concentration within RO for a given X (kg·m-3)
-
Y
O
2
Biomass yield calculated on oxygen (kg dw/kg O2)
-
Thiele modulus
-
Efficiency factor =1-(RO/R)3 (-)
-
Growth rate (m-1·s-1·kg1/3)
-
Dry weight per volume of pellet (kg·m-3) 相似文献
8.
Bimetallic copper(II) and zinc(II) complexes of acyclic Schiff base ligands derived from amino acids
Abdessamad Arbaoui Noelia M. Sanchez-Ballester David L. Hughes 《Inorganica chimica acta》2011,365(1):96-102
The acyclic Schiff-base ligands (2-(OH)-5-(R3)C6H2-1,3-(HCNC(R1)(R2)CO2H), derived from the dialdehyde 2-hydroxy-5-R-1,3-benzenedicarboxaldehyde (R = Me or t-Bu) and two equivalents of the amino acids glycine, 2,2-diphenylglycine or phenylalanine, have been reacted with the metal acetates M(OAc)2 (M = Cu, Zn) in the presence of triethylamine, affording the complexes [HNEt3][M2(CH3CO2)2(2-(O)-5-(t-Bu)C6H2-1,3-(HCNC(R1)(R2)CO2)2] (M = Cu, R1 = R2 = C6H5, R3 = Me (1); M = Zn, R1 = R2 = H, R3 = t-Bu (2); M = Zn, R1 = R2 = C6H5, R3 = t-Bu (3); M = Zn, R1 = H, R2 = CH2C6H5, R3 = t-Bu (4)) in good yields. The crystal structures of 1·MeCN, 2·, 3·2MeOH, and 4·3MeOH have been determined. 相似文献
9.
A modified Rotating Biological Contactor (RBC) was used for the treatability studies of synthetic tapioca wastewaters. The RBC used was a four stage laboratory model and the discs were modified by attaching porous nechlon sheets to enhance biofilm area. Synthetic tapioca wastewaters were prepared with influent concentrations from 927 to 3600 mg/l of COD. Three hydraulic loads were used in the range of 0.03 to 0.09 m3·m–2·d–1 and the organic loads used were in the range of 28 to 306 g COD· m–2·d–1. The percentage COD removal were in the range from 97.4 to 68. RBC was operated at a rotating speed of 18 rpm which was found to be the optimal rotating speed. Biokinetic coefficients based on Kornegay and Hudson models were obtained using linear analysis. Also, a mathematical model was proposed using regression analysis.List of Symbols
A m2
total surface area of discs
-
d m
active depth of microbial film onany rotating disc
-
K
s mg ·l–1
saturation constant
-
P mg·m–2·–1
area capacity
-
Q l·d–1
hydraulic flow rate
-
q m3·m–2·d–1
hydraulic loading rate
-
S
0 mg·l–1
influent substrate concentration
-
S
e mg·l–1
effluent substrate concentration
-
w rpm
rotational speed
-
V m3
volume of the reactor
-
X
f mg·l–1
active biomass per unit volume ofattached growth
-
X
s mg·l–1
active biomass per unit volume ofsuspended growth
-
X mg·l–1
active biomass per unit volume
-
Y
s
yield coefficient for attachedgrowth
-
Y
A
yield coefficient for suspendedgrowth
-
Y
yield coefficient, mass of biomass/mass of substrate removed
Greek Symbols
hr
mean hydraulic detention time
- (max)A d–1
maximum specific growth rate forattached growth
- (max)s d–1
maximum specific growth rate forsuspended growth
- max d–1
maximum specific growth rate
- d–1
specific growth rate
- v mg·l–1·hr–1
maximum volumetric substrateutilization rate coefficient 相似文献
10.
A series of mononuclear organotin(IV) complexes of the types, R3SnL {R = C4H9 (1), C6H11 (2), CH3 (3) and C6H5 (4)}, R2SnClL {R = C4H9 (5), C2H5 (7) and CH3 (9)} and R2SnL2 {R = C4H9 (6), C2H5 (8) and CH3 (10)}, have been synthesized, where L = 4-(4-methoxyphenyl)piperazine-1-carbodithioate. The ligand-salt and the complexes have been characterized by Raman, FT-IR and multinuclear NMR (1H, 13C and 119Sn) spectroscopy and elemental microanalysis (CHNS). The spectroscopic data substantiate coordination of the ligands to the organotin moieties. The structures of complexes 4 and 6 have been determined by single-crystal X-ray diffraction and illustrate the asymmetric bidentate bonding of the ligand. The packing diagrams indicate O···H and π···H intermolecular interactions in complex 4 and intermolecular S2C···H interactions in complex 6, resulting in layer structures for both complexes. A subsequent antimicrobial study indicates that the compounds are active biologically and may well be the basis for a new class of fungicides. 相似文献
11.
Roland H. Müller Oleg V. Sysoev Wolfgang Babel 《Applied microbiology and biotechnology》1986,25(3):238-244
Summary Investigations were made into the improvement of growth yield (Y) of Pichia pinus MH 4 growing continuously on methanol by feeding formate so as to create an increasing concentration gradient (transient state). Under particular formate supply conditions, Y could be increased from 0.37 g·g-1 on methanol alone to 0.55 and 0.47 g·g-1 in the presence of formate at dilution rates (D) of 0.045 and 0.075 h-1, respectively. These differences could be explained as being due to a limiting formate consumption rate of 50–60 nmol·min-1·g-1 dry wt., coupled to a net-energy generation independent of D. Any further formate oxidation proceeded without energy gain. Deviations from optimum conditions of biomass increase are discussed in terms of different formate oxidizing systems and uncoupling properties of formate itself. These results are compared to and confirmed by steady-state considerations.Abbreviations a
steepness of the formate gradient (g·l-1·h-1)
- a
acceleration of change of formate concentration in the fermenter (g·l-1·h-2)
- D
dilution rate (h-1)
- Ft
formate
- S1 and S2
initial and final formate concentration of the gradient (g·l-1)
- Y
growth yield in g·g-1 methanol 相似文献
12.
W. -M. Weber B. Dannenmaier W. Clauss 《Journal of comparative physiology. B, Biochemical, systemic, and environmental physiology》1993,163(2):153-159
The dorsal skin of the leech Hirudo medicinalis was used for electrophysiological measurements performed in Ussing chambers. The leech skin is a tight epithelium (transepithelial resistance = 10.5±0.5 k· cm-2) with an initial short-circuit current of 29.0±2.9 A·cm-2. Removal of Na+ from the apical bath medium reduced short-circuit current about 55%. Ouabain (50mol·l-1) added to the basolateral solution, depressed the short-circuit current completely. The Na+ current saturated at a concentration of 90 mmol Na+·l-1 in the apical solution (K
M=11.2±1.8 mmol·l-1). Amiloride (100 mol·l-1) on the apical side inhibited ca. 40% of the Na+ current and indicated the presence of Na+ channels. The dependence of Na+ current on the amiloride concentration followed Michaclis-Menten kinetics (K
i=2.9±0.4 mol·l-1). The amiloride analogue benzamil had a higher affinity to the Na+ channel (K
i=0.7±0.2 mol·l-1). Thus, Na+ channels in leech integument are less sensitive to amiloride than channels known from vertebrate epithelia. With 20 mmol Na+·l-1 in the mucosal solution the tissue showed an optimum amiloride-inhibitable current, and the amiloride-sensitive current under this condition was 86.8±2.3% of total short-circuit current. Higher Na+ concentrations lead to a decrease in amiloride-blockade short-circuit current. Sitmulation of the tissue with cyclic adenosine monophosphate (100 mol·l-1) and isobutylmethylxanthine (1 mmol·l-1) nearly doubled short-circuit current and increased amiloride-sensitive Na+ currents by 50%. By current fluctuation analysis we estimated single Na+ channel current (2.7±0.9 pA) and Na+ channel density (3.6±0.6 channels·m-2) under control conditions. After cyclic adenosine monophosphate stimulation Na+ channel density increased to 5.4±1.1 channels·m-2, whereas single Na+ channel current showed no significant change (1.9±0.2 pA). These data present a detailed investigation of an invertebrate epithelial Na+ channel, and show the similarities and differences to vertebrate Na+ channels. Whereas the channel properties are different from the classical vertebrate Na+ channel, the regulation by cyclic adenosine monophosphate seems similar. Stimulation of Na+ uptake by cyclic adenosine monophosphate is mediated by an increasing number of Na+ channels.Abbreviations
slope of the background noise component
- ADH
antidiuretic hormone
- cAMP
cyclic adenosine monophosphate
-
f
frequency
-
f
c
coner frequency of the Lorentzian noise component
- Hepes
N-hydroxyethylpiperazine-N-ethanesulphonic acid
- BMX
isobutyl-methylxanthine
-
i
Na
single Na+ channel current
-
I
Na
max, maximal inhibitable Na+ current
-
I
SC
short circuit current
-
K
i
half maximal blocker concentration
-
K
M
Michaelis constandard error of the mean
-
S
(f)
power density of the Lorentzian noise component
-
S
0
plateau value of the Lorentzian noise component
- TMA
tetramethylammonium
- Trizma
TRIS-hydroxymethyl-amino-methane
-
V
max
maximal reaction velocity
-
V
T
transepithelial potential
-
K
half maximal blocker concentration 相似文献
13.
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
14.
G. E. Walsberg B. O. Wolf 《Journal of comparative physiology. B, Biochemical, systemic, and environmental physiology》1995,165(4):306-314
We quantified metabolic power consumption as a function of wind speed in the presence and absence of simulated solar radiation in rock squirrels, Spermophilus variegatus, a diurnal rodent inhabiting arid regions of Mexico and the western United States. In the absence of solar radiation, metabolic rate increased 2.2-fold as wind speed increased from 0.25 to 4.0 m·s-1. Whole-body thermal resistance declined 56% as wind speed increased over this range, indicating that body insulation in this species is much more sensitive to wind disruption than in other mammals. In the presence of 950 W·m-2 simulated solar radiation, metabolic rate increased 2.3-fold as wind speed was elevated from 0.25 to 4.0 m·s-1. Solar heat gain, calculated as the reduction in metabolic heat production associated with the addition of solar radiation, increased with wind speed from 1.26 mW·g-1 at 0.25 m·s-1 to 2.92 mW·g-1 at 4.0 m·s-1. This increase is opposite to theoretical expectations. Both the unexpected increase in solar heat gain at elevated wind speeds and the large-scale reduction of coat insulation suggests that assumptions often used in heat-transfer analyses of animals can produce important errors.Abbreviations
absorptivity of coat to solar radiation
-
kinematic viscosity of air (mm2·s-1)
-
reflectivity of coat to solar radiation
-
a
r
B
expected at zero wind speed (s·m-1)
-
A
P
projected surface area of animal on plane perpendicular to solar beam (cm2)
-
A
SKIN
skin surface area (cm2)
-
b
Coefficient describing change in r
B with change in square-root of wind speed (s1.5·m1.5)
-
d
hair diameter (m)
- d
characteristic dimension of animal (m)
-
D
H
thermal diffusivity of air (m2·s-1)
-
E
evaporative heat loss (W·m-2)
-
I
probability per unit coat depth that photon will strike hair
-
k
constant equalling 1200 J·m-3·°C-1
-
l
C
coat depth m)
-
l
H
hair length (m)
-
M
metabolic rate (W·m-2)
-
n
density of hairs of skin (m-2)
-
Q
A
solar heat gain to animal (W·m-2)
-
Q
I
solar irradiance intercepted by animal (W·m-2)
-
RQ
respiratory quotient
-
r
A
thermal resistance of boundary layer (s·m-1)
-
r
B
whole-body thermal resistance (s·m-1)
-
r
E
thermal resistance between animal surface and environment s·m-1)
-
r
R
radiative resistance (s·m-1)
-
r
S
sum of r
B and r
E at 0.25 m·s-1 (s·m-1)
-
r
T
tissue thermal resistance s·m-1)
-
T
AIR
air temperature (°C)
-
T
B
body temperature (°C)
-
T
E
operative temperature of environment (°C)
-
T
ES
standard operative temperature of environment (°C)
-
u
wind speed (m·s-1) 相似文献
15.
Summary The larvae of Megachile pacifica, the leafcutter bee, develop within a cell constructed of pieces of leaf by the adult female which also provides a plug of nectar and pollen, the sole source of nutrient for the larvae. In this study, eggs (1 per cell) hatched in 2–3 days and larvae were fully grown after a further 9 days at 28° C.The mean larval dry weight (dw) when fully grown (P
L
) was 18.89 mg. Larvae ate 45.99 mg (dw) (C) of their food leaving 0.90 mg (dw) unconsumed. The faeces (FU) weighed an average of 5.62 mg (dw) and their cocoon weighed 2.68 mg (dw) (P
E
). The components of their energy budget (C=(P
L
+P
E
)+R+FU) were C=1079.4 J, P
L
=569.1 J, P
E
=62.25 J, R (metabolic energy measured with a Gilson respirometer)=218.3 J and FU=134.4 J. R calculated by difference was 313.6 J.Full grown larvae contained 1.17 mg of nitrogen (N). They egested 0.19 mg N and incorporated 0.16 mg N in the cocoons. They ingested 1.51 mg N (measured) — the calculated consumption of nitrogen (by difference) was 1.52 mg.The ecological efficiencies showed that these larvae are among the most efficient invertebrate converters of energy and nitrogen yet recorded. The assimilation efficiencies (A·C
-1
) were 87.5% (energy), 87.2% (N), the net ecological efficiencies (P·A
-1
) were 66.8% (energy) and 100% (N) and the gross ecological efficiencies (P·C
-1
) were 58.5% (energy) and 87.6% (N). the production to respiration ratio (x100) was 201.5% using calculated R. 相似文献
16.
A. M. Beal 《Journal of comparative physiology. B, Biochemical, systemic, and environmental physiology》1995,164(8):629-635
Saliva was collected from the mandibular glands of anaesthetized common wombats (Vombatus ursinus) to ascertain maximal flow rates, salivary compostion and possible adaptations, particularly PO4
3- secretion, to assist digestion. After temporary catheterization of the main duct through its oral opening, salivary secretion was evoked at flow rates ranging from 0.02±0.002 (±SEM) ml·min-1 (0.7±0.07 l·min-1·kg body weight-1) to 0.4±0.05 ml·min-1(14±1.9 l·min-1·kg body weight-1) by ipsilateral intracarotid infusion of acetylcholine. The [Na+] (15±5.1 to 58±8.6 mmol·l-1) and [HCO3
-] (35±1.9 to 60±1.9 mmol·l-1) were positively correlated with salivary flow rate. The [K+] (58±5.2 to 30±2.4 mmol·l-1), [Ca2+] (10.4±1.67 to 4.1±0.44 mmol·l-1), [Mg2+] (0.94±0.137 to 0.17±0.032 mmol·l-1), [Cl-] (71±9.2 to 45±6.0 mmol·l-1), [urea] (9.3±0.79 to 5.1±0.54 mmol·l-1), H+ activity (29±1.6 to 17±1.6 nEq·l-1) and amylase activity (251±57.4 to 92±23.3 kat·l-1) were negatively correlated with flow. Both concentration and osmolality fell with increasing flow at the lower end of the flow range but osmolality always increased again by maximal flow whereas the relation between protein and flow was not consistent at the higher levels of flow and stimulation. Salivary [PO4
3+] was not correlated with flow and at 3–14% of the plasma concentration was extremely low. Thus, in contrast to its nearest relative, the koala (Phascolarctos cinereus), the wombat secretes little PO4
3+ presumably because it does not need high levels of PO4
3+ in its saliva to facilitate microbial digestion of plant fibre.Abbreviations bw
body weight
- ww
wet weight 相似文献
17.
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
18.
Gwon-Soo Kim Si-Hyung Park Yung-Jin Chang Yoong-Ho Lim Soo-Un Kim 《Biotechnology letters》2002,24(19):1553-1556
(+)-Isopiperitenone (100 mg l–1) was converted into (4S,6R)-6-hydroxy- and (4S,8R)-8,9-epoxyisopiperitenone, aside from the already known (+)-7-hydroxyisopiperitenone, by suspension cell culture of Mentha piperita. As (–)-isopiperitenone was hydroxylated similarly, this implies that the hydroxylating enzyme(s) have a broad substrate stereospecificity in regards to the stereochemistry at C4. (–)-(4R)-Carvone was reduced by the Mentha cells both at carbonyl and C1-C6 double bond to give (1R,2S,4R)-neodihydrocarveol and (1R,2R,4R)-dihydrocarveol with the former being the major product. (+)-(4S)-Carvone had a similar reduction pattern, producing (1S,2R,4S)-neodihydrocarveol and (1S,4S)-dihydrocarvone. Formation of these compounds indicates that the peppermint cell culture cannot only hydroxylate the allylic position but also reduce the ,-unsaturated carbonyl system. 相似文献
19.
Maria D. Koskolou Donald C. McKenzie 《European journal of applied physiology and occupational physiology》1994,68(1):80-86
In order to determine the level of hypoxemia which is sufficient to impair maximal performance, seven well-trained male cyclists [maximum oxygen consumption (VO2max)51·min–1 or 60 ml·kg–1·min–1] performed a 5-min performance cycle test to exhaustion at maximal intensity as controlled by the subject, under three experimental conditions: normoxemia [percentage of arterial oxyhemoglobin saturation (%S
a O2)>94%], and artificially induced mild (%S
aO2=90±1%) and moderate (%S
aO2=87±1%) hypoxemia. Performance, evaluated as the total work output (Worktot) performed in the 5-min cycle test, progressively decreased with decreasing %S
aO2 [mean (SE) Worktot=107.40 (4.5) kJ, 104.07 (5.6) kJ, and 102.52 (4.7) kJ, under normoxemia, mild, and moderate hypoxemia, respectively]. However, only performance in the moderate hypoxemia condition was significantly different than in normoxemia (P=0.02). Mean oxygen consumption and heart rate were similar in the three conditions (P=0.18 andP=0.95, respectively). End-tidal partial pressure of CO2 was significantly lower (P=0.005) during moderate hypoxemia compared with normoxemia, and ventilatory equivalent of CO2 was significantly higher (P=0.005) in both hypoxemic conditions when compared with normoxemia. It is concluded that maximal performance capacity is significantly impaired in highly trained cyclists working under an %S
aO2 level of 87% but not under a milder desaturation level of 90%. 相似文献
20.
Summary The growth parameters ofPenicillium cyclopium have been evaluated in a continuous culture system for the production of fungal protein from whey. Dilution rates varied from 0.05 to 0.20 h–1 under constant conditions of temperature (28°C) and pH (3.5). The saturation coefficients in the Monod equation were 0.74 g l–1 for lactose and 0.14 mg l–1 for oxygen, respectively. For a wide range of dilution rates, the yield was 0.68 g g–1 biomass per lactose and the maintenance coefficient 0.005 g g–1 h–1 lactose per biomass, respectively. The maximum biomass productivity achieved was 2 g l–1 h–1 biomass at dilution rates of 0.16–0.17 h–1 with a lactose concentration of 20 g l–1 in the feed. The crude protein and total nucleic acid contents increased with a dilution rate, crude protein content varied from 43% to 54% and total nucleic acids from 6 to 9% in the range of dilution rates from 0.05 to 0.2 h–1, while the Lowry protein content was almost constant at approximately 37.5% of dry matter.Nomenclature (mg l–1)
Co initial concentration of dissolved oxygen
- (h–1)
D dilution rate
- (mg l–1)
K02 saturation coefficient for oxygen
- (g l–1)
Ks saturation coefficient for substrate
- (g g–1 h–1) lactose per biomass)
m maintenance energy coefficient
- (mM g–1 h–1O2 per biomass)
Q02 specific oxygen uptake rate
- (g l–1)
S residual substrate concentration at steady state
- (g l–1)
So initial substrate concentration in feed
- (min)
t1/2 time when Co is equal to Co/2
- (g l–1)
X biomass concentration
- (g l–1)
X biomass concentration at steady state
- (g g–1 biomass per lactose)
YG yield coefficient for cell growth
- (g g–1 biomass per lactose)
Yx/s overall yield coefficient
- (h–1)
specific growth rate 相似文献