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1.
The separation of two amino acids, phenylalanine and tryptophan, was carried out using laboratory simulated moving bed (SMB)
chromatography. The SMB process consisted of four zones, with each zone having 2 columns. The triangle theory was used to
obtain the operating conditions for the SMB. The mass transfer coefficients of the two amino acids were obtained from the
best-fit values by comparing simulated and experimental pulse data. The competitive adsorption isotherms of the two amino
acids were obtained by single and binary frontal analyses, taking into consideration the competition between the two components.
A competitive Langmuir isotherm, obtained from single-component frontal chromatography, was used in the first run, and the
isotherm from binary frontal chromatography in the second, with the flow rate of zone I modified to improve the purity. Compared
to the first and second runs, the competitive Langmuir isotherm from the binary frontal chromatography showed good agreement
with the experimental results. Also, adjusting the flow rate in zone I increased the purity of the products. The purities
of the phenylalanine in the raffinate and the tryptophan in the extract were 99.84 and 99.99%, respectively. 相似文献
2.
Xuefang Li Wanzhi Wei Xiandong Zeng Jinxiang Zeng Jian Yin Ling Wu 《World journal of microbiology & biotechnology》2007,23(10):1465-1471
This paper provided information on the use of linear sweep anodic stripping voltammetry for evaluating the process of copper
biosorption onto Pseudomonas aeruginosa. This technique was suited to determine the concentration of free copper ion on site on the mercaptoethane sulfonate modified
gold electrode surface without any pretreatment. It was in favor of the study of kinetic process as the fast changing kinetic
data characteristic just after the beginning of biosorption could be accurately depicted. Based on the electrochemical results,
the kinetics and equilibrium of biosorption were systematically examined. The pseudo-second-order kinetic model was used to
correlate the kinetic experimental data and the kinetic parameters were evaluated. The Langmuir and Freundlich models were
applied to describe the biosorption equilibrium. It was found that the Langmuir isotherm fitted the experimental data better
than the Freundlich isotherm. Maximum adsorption capacity of copper ion onto Pseudomonas aeruginosa was 0.9355 μmol mg−1 (about 59.4417 mg g−1). 相似文献
3.
M. Prado Acosta E. Valdman S. G. F. Leite F. Battaglini S. M. Ruzal 《World journal of microbiology & biotechnology》2005,21(6-7):1157-1163
Summary Biosorption of heavy metals by gram-positive, non-pathogenic and non-toxicogenic Paenibacillus polymyxa P13 was evaluated. Copper was chosen as a model element because it is a pollutant originated from several industries. An
EPS (exopolysaccharide)-producing phenotype exhibited significant Cu(II) biosorption capacity. Under optimal assay conditions
(pH 6 and 25 °C), the adsorption isotherm for Cu(II) in aqueous solutions obeyed the Langmuir model. A high q value (biosorption capacity) was observed with whole cells (qmax=112 mgCu g−1). EPS production was associated with hyperosmotic stress by high salt (1 M NaCl), which led to a significant increase in
the biosorption capacity of whole cells (qmax=150 mgCu g−1). Biosorption capacity for Cu(II) of the purified EPS was investigated. The maximum biosorption value (q) of 1602 mg g−1 observed with purified EPS at 0.1 mg ml−1 was particularly promising for use in field applications. 相似文献
4.
Biosorption is an effective means of removal of heavy metals from wastewater. In this work the biosorption behavior of Cladophora fascicularis was investigated as a function of pH, amount of biosorbent, initial Cu2+ concentration, temperature, and co-existing ions. Adsorption equilibria were well described by Langmuir isotherm models.
The enthalpy change for the biosorption process was found to be 6.86 kJ mol−1 by use of the Langmuir constant b. The biosorption process was found to be rapid in the first 30 min. The presence of co-existing cations such as Na+, K+, Mg2+, and Ca2+ and anions such as chloride, nitrate, sulfate, and acetate did not significantly affect uptake of Cu2+ whereas EDTA substantially affected adsorption of the metal. When experiments were performed with different desorbents the
results indicated that EDTA was an efficient desorbent for the recovery of Cu2+ from biomass. IR spectral analysis suggested amido or hydroxy, C=O, and C–O could combine strongly with Cu2+. 相似文献
5.
The ability of spring barley (Hordeum vulgare cv. Akcent) to adjust the composition and function of the photosynthetic apparatus to growth irradiances of 25–1200 μmol
m−2 s−1 was studied by gas exchange and chlorophyll a fluorescence measurements and high-performance liquid chromatography. The increased growth irradiance stimulated light- and
CO2-saturated rates of CO2 assimilation expressed on a leaf area basis up to 730 μmol m−2 s−1 (HL730), whereas at an irradiance of 1200 μmol m−2 s−1 (EHL1200) both rates decreased significantly. Further, the acclimation to EHL1200 was associated with an extremely high chlorophyll
a/b ratio (3.97), a more than doubled xanthophyll cycle pool (VAZ) and a six-fold higher de-epoxidation state of the xanthophyll
cycle pigments as compared to barley grown under 25 μmol m−2 s−1 (LL25). EHL1200 plants also exhibited a long-term inhibition of Photosystem II (PS II) photochemical efficiency (F
v/F
m). Photosynthetic capacity, chlorophyll a/b and VAZ revealed a linear trend of dependence on PS II excitation pressure in a certain range of growth irradiances (100–730
μmol m−2 s−1). The deviation from linearity of these relationships for EHL1200 barley is discussed. In addition, the role of increased
VAZ and/or accumulation of zeaxanthin and antheraxanthin in acclimation of barley to high irradiance is studied with respect
to regulation of non-radiative dissipation and/or photochemical efficiency within PS II.
This revised version was published online in June 2006 with corrections to the Cover Date. 相似文献
6.
Abrunhosa L Costa M Areias F Venâncio A Proença F 《Journal of industrial microbiology & biotechnology》2007,34(12):787-792
The activity on Aspergillus spp. growth and on ochratoxin A production of two novel chromene dimers (3) was evaluated. The results of the bioassays indicate that the chromene dimer 3a inhibited mycelia growth by approximately 50% (EC50) at 140.1 μmol L−1 for A. niger, 384.2 μmol L−1 for A. carbonarius, 69.1 μmol L−1 for A. alliaceus and 559.1 μmol L−1 for A. ochraceus. When applied at concentrations of 2 mmol L−1, 3a totally inhibited the growth of all Aspergillus spp. tested. Furthermore, ochratoxin A production by A. alliaceus was reduced by about 94% with a 200 μmol L−1 solution of this compound. A moderate inhibitory effect was observed for the analogous structure 3b on ochratoxin A production but not in mycelia growth. No inhibition was registered for compounds 2a and 2b, used as synthetic precursors of the dimeric species 3. 相似文献
7.
Summary A tropical white-rot basidiomycete, BDT-14 (DSM 15396) was investigated for its chromium (VI) biosorption potential from an
aqueous solution. Pre-treatment of fungal biomass with acid resulted in 100% metal adsorption compared to only 26.64% adsorption
without any pre-treatment. Chromium adsorption was a rapid process at early exposure resulting in 60% chromium removal within
the first 2 h of exposure. An increase in biomass showed an increase in the total metal ions adsorption but a decrease in
specific uptake of metal ions. The concentrations of chromium had a pronounced effect on the rate of adsorption. The adsorption
efficiency was 100% when the initial Cr (VI) concentration was 100 mg l−1 with 1,000 mg biomass. Only 47.5% adsorption was observed with 500 mg l−1 Cr (VI) concentration. The adsorption data fit well with the Langmuir and Freundlich isotherm models. Comprehensive characterization
of parameters indicates BDT−14 biomass as a promising material for Cr (VI) adsorption. 相似文献
8.
Ling-zhi Huang Guang-ming Zeng Dan-lian Huang Li-feng Li Peng-mian Huang Chang-bin Xia 《Biodegradation》2009,20(5):651-660
The adsorption of Pb(II) onto Hydrilla verticillata was examined in aqueous solution with parameters of pH, adsorbent dosage, contact time and temperature. The linear Langmuir
and Freundlich models were applied to describe equilibrium isotherms, and both models fitted well. The monolayer adsorption
capacity of Pb(II) was found as 104.2 mg/g at pH 4 and 25°C. Dubinin–Radushkevich (D–R) isotherm model was also applied to
the equilibrium data. The mean free energy of adsorption (15.81 kJ/mol) indicated that the adsorption of Pb(II) onto H. verticillata may be carried out via chemical ion-exchange mechanism. Thermodynamic parameters, free energy (ΔG
0), enthalpy (ΔH
0) and entropy (ΔS
0) of adsorption were also calculated. These parameters showed that the adsorption of Pb(II) onto H. verticillata was a feasible, spontaneous and exothermic process in nature. The influence of Cd2+, Cu2+ and Ni2+ on adsorption of Pb2+ onto H. verticillata was studied, too. In the investigated range of operating conditions, it was found that the existence of Cd 2+, Cu 2+ and Ni 2+ had no impact on the adsorption of Pb2+. 相似文献
9.
Removal of heavy metals (Pb2+, Zn2+) from aqueous solution by dried biomass of Spirulina sp. was investigated. Spirulina rapidly adsorbed appreciable amount of lead and zinc from the aqueous solutions within 15 min of initial contact with the
metal solution and exhibited high sequestration of lead and zinc at low equilibrium concentrations. The specific adsorption
of both Pb2+ and Zn2+ increased at low concentration and decreased when biomass concentration exceeded 0.1 g l−1. The binding of lead followed Freundlich model of kinetics where as zinc supported Langmuir isotherm for adsorption with
their r
2
values of 0.9659 and 0.8723 respectively. The adsorption was strongly pH dependent as the maximum lead biosorption occurred
at pH 4 and 10 whereas Zn2+ adsorption was at pH 8 and 10. 相似文献
10.
Durmaz-Sam S Sayar NA Topal-Sarikaya A Sayar AA 《Bioprocess and biosystems engineering》2011,34(8):997-1005
The potential of the dried yeast, wild-type Schizosaccharomyces pombe, to remove Ni(II) ion was investigated in batch mode under varying experimental conditions including pH, temperature, initial
metal ion concentration and biosorbent dose. Optimum pH for biosorption was determined as 5.0. The highest equilibrium uptake
of Ni(II) on S. pombe, q
e, was obtained at 25 °C as 33.8 mg g−1. It decreased with increasing temperature within a range of 25–50 °C denoting an exothermic behaviour. Increasing initial
Ni(II) concentration up to 400 mg L−1 also elevated equilibrium uptake. No more adsorption took place beyond 400 mg L−1. Equilibrium data fitted better to Langmuir model rather than Freundlich model. Sips, Redlich–Peterson, and Kahn isotherm
equations modelled the investigated system with a performance not better than Langmuir. Kinetic model evaluations showed that
Ni(II) biosorption process followed the pseudo-second order rate model while rate constants decreased with increasing temperature.
Gibbs free energy changes (ΔG°) of the system at 25, 30, 35 and 50 °C were found as −1.47E + 4, −1.49E + 4, −1.51E + 4, and −1.58E + 4 J mol−1, respectively. Enthalpy change (ΔH°) was determined as −2.57E + 3 J mol−1 which also supports the observed exothermic behaviour of the biosorption process. Entropy change (ΔS°) had a positive value (40.75 J mol−1 K−1) indicating an increase in randomness during biosorption process. Consequently, S. pombe was found to be a potential low-cost agent for Ni(II) in slightly acidic aqueous medium. In parallel, it has been assumed
to act as a separating agent for Ni(II) recovery from its aqueous solution. 相似文献
11.
Young Jae Choi Soon Koo Han Sung Taik Chung Kyung Ho Row 《Biotechnology and Bioprocess Engineering》2007,12(6):625-633
Utilizing a Simulated Moving Bed (SMB), the conditions for separating bupivacaine enantiomers, a racemic local anesthetic,
were determined by triangle theory and simulations using the gPROMS software and the Aspen Chromatography package. The SMB
model in this study assumed an axial dispersion flow for the liquid phase and the intraparticle mass transfer was described
in terms of a simple Linear Driving Force (LDF) approximation. The parameters (a andb) of the Langmuir Adsorption Isotherm (LAI) were determined using a dynamic method. In the optimal condition the calculated
concentrations were confirmed by the experimental results. Values projected by the gPROMS software more closely matched experimental
values than those projected by the Aspen Chromatography package. 相似文献
12.
Copper adsorption kinetics of cultured algal cells and freshwater phytoplankton with emphasis on cell surface characteristics 总被引:1,自引:0,他引:1
Comparative studies were carried out on the adsorption of copper by a range of laboratory-cultured algae and freshwater phytoplankton
samples. The level of surface mucilage associated with the cultured algae ranged from high (Anabaena spiroides, Eudorina elegans) to moderate (Anabaena cylindrica, Microcystis aeruginosa) to complete absence (Chlorella vulgaris, Asterionella formosa, Aulacoseira varians, Ceratium hirundinella). With laboratory cultures, the rapid uptake, EDTA release and quantitative similarity between living and dead (glutaraldehyde-fixed)
algae were consistent with physical binding of Cu at the cell surface. The higher Cu adsorption per unit surface area and
longer adsorption time of mucilaginous algae in the time-course study, and the relatively high level of Cu bound to mucilage
found by X-ray microanalysis suggest that mucilage played an important role in metal binding. For all species examined, Cu
adsorption kinetics (external Cu concentrations 1 to 1000 mg L−1) showed a clear fit to the Freundlich, but not the Langmuir isotherm, indicating a monolayer adsorption model with heterogenous
binding sites. The Freundlich adsorption capacity constant (Kf) was higher in mucilaginous (3.96–12.62) compared to nonmucilaginous (0.36–3.63) species, but binding intensity (Freundlich
constant 1/n) did not differ between the two cell types. The results suggest that mucilaginous algal species may have potential as biosorbents
for treatment of industrial effluents containing heavy metals. Investigation of the Cu adsorption behavior of four mixed phytoplankton
samples also revealed a good fit to the Freundlich, but not the Langmuir, isotherm. Freundlich constants were in the range
2.3–3.2 for samples dominated by Chlorophyta, Bacillariophyta and Cyanophyta, but recorded a value of 7.4 in the sample dominated
by Dinophyta. Comparison with data from laboratory monocultures suggested that the adsorption kinetics of mixed environmental
phytoplankton samples cannot be predicted simply in terms of the major algal species. 相似文献
13.
Chlorophyll-a (chl-a) and carotenoid pigments of the zooxanthellate octocoral Sinularia flexibilis were analyzed using high performance liquid chromatography following exposure to three light intensities for over 30 days.
From the coral fragments located at different light intensities, a total carotenoid of >41 μg g−1 dry weight, including peridinin, xanthophylls (likely diadinoxanthin + diatoxanthin), and chl-a as the most abundant pigments, with minor contents of astaxantin and β-carotene were detected. The whole content of chl-a weighed 5 μg g−1 dry weight in all coral colonies. Chl-a and carotenoids contributed 11.2% and 88.2%, respectively, to all pigments detected, and together accounted for 99.4% of
the total pigments present. The highest contents of carotenoids and chl-a was observed in the coral grafts placed in an irradiance of 100 μmol quanta m−2 s−1; they showed lower ratios of total carotenoids: chl-a compared to those exposed to 400 μmol quanta m−2 s−1 after >30 days of incubation. The ratios of peridinin and xanthophylls with respect to chl-a from the colonies at 400 μmol quanta m−2 s−1 were approximately double those observed at irradiances of 100 and 200 μmol quanta m−2 s−1. Partial quantification of pigments in this study showed that the carotenoids of S. flexibilis showed a decrease at irradiances above 100 μmol quanta m−2 s−1, with the exception of an increase in β-carotene at 200 μmol quanta m−2 s−1. 相似文献
14.
W. Bartels B. S. Law F. Geiser 《Journal of comparative physiology. B, Biochemical, systemic, and environmental physiology》1998,168(3):233-239
Little is known about torpor in the tropics or torpor in megachiropteran species. We investigated thermoregulation, energetics
and patterns of torpor in the northern blossom-bat Macroglossus minimus (16 g) to test whether physiological variables may explain why its range is limited to tropical regions. Normothermic bats
showed a large variation in body temperature (T
b) (33 to 37 °C) over a wide range of ambient temperatures (T
as) and a relatively low basal metabolic rate (1.29 ml O2 g−1 h−1). Bats entered torpor frequently in the laboratory at T
as between 14 and 25 °C. Entry into torpor always occurred when lights were switched on in the morning, independent of T
a. MRs during torpor were reduced to about 20–40% of normothermic bats and T
bs were regulated at a minimum of 23.1 ± 1.4 °C. The duration of torpor bouts increased with decreasing T
a in non-thermoregulating bats, but generally terminated after 8 h in thermoregulating torpid bats. Both the mean minimum T
b and MR of torpid M. minimus were higher than that predicted for a 16-g daily heterotherm and the T
b was also about 5 °C higher than that of the common blossom-bat Syconycteris australis, which has a more subtropical distribution. These observations suggest that variables associated with torpor are affected
by T
a and that the restriction to tropical areas in M. minimus to some extent may be due to their ability to enter only very shallow daily torpor.
Accepted: 22 September 1997 相似文献
15.
Using 77 K chlorophyll a (Chl a) fluorescence spectra in vivo, the development was studied of Photosystems II (PS II) and I (PS I) during greening of barley under intermittent light followed
by continuous light at low (LI, 50 μmol m−2 s−1) and high (HI, 1000 μmol m−2 s−1) irradiances. The greening at HI intermittent light was accompanied with significantly reduced fluorescence intensity from
Chl b excitation for both PS II (F685) and PS I (F743), in comparison with LI plants, indicating that assembly of light-harvesting
complexes (LHC) of both photosystems was affected to a similar degree. During greening at continuous HI, a slower increase
of emission from Chl b excitation in PS II as compared with PS I was observed, indicating a preferred reduction in the accumulation of LHC II. The
following characteristics of 77 K Chl a fluorescence spectra documented the photoprotective function of an elevated content of carotenoids in HI leaves: (1) a pronounced
suppression of Soret region of excitation spectra (410–450 nm) in comparison with the red region (670–690 nm) during the early
stage of greening indicated a strongly reduced excitation energy transfer from carotenoids to the Chl a fluorescing forms within PS I and PS II; (2) changes in the shape of the excitation band of Chl b and carotenoids (460–490 nm) during greening under continuous light confirmed that the energy transfer from carotenoids to
Chl a within PS II remained lower as compared with the LI plants.
This revised version was published online in June 2006 with corrections to the Cover Date. 相似文献
16.
This article reports rate constants for thiol–thioester exchange (k
ex), and for acid-mediated (k
a), base-mediated (k
b), and pH-independent (k
w) hydrolysis of S-methyl thioacetate and S-phenyl 5-dimethylamino-5-oxo-thiopentanoate—model alkyl and aryl thioalkanoates, respectively—in water. Reactions such as
thiol–thioester exchange or aminolysis could have generated molecular complexity on early Earth, but for thioesters to have
played important roles in the origin of life, constructive reactions would have needed to compete effectively with hydrolysis
under prebiotic conditions. Knowledge of the kinetics of competition between exchange and hydrolysis is also useful in the
optimization of systems where exchange is used in applications such as self-assembly or reversible binding. For the alkyl
thioester S-methyl thioacetate, which has been synthesized in simulated prebiotic hydrothermal vents, k
a = 1.5 × 10−5 M−1 s−1, k
b = 1.6 × 10−1 M−1 s−1, and k
w = 3.6 × 10−8 s−1. At pH 7 and 23°C, the half-life for hydrolysis is 155 days. The second-order rate constant for thiol–thioester exchange
between S-methyl thioacetate and 2-sulfonatoethanethiolate is k
ex = 1.7 M−1 s−1. At pH 7 and 23°C, with [R″S(H)] = 1 mM, the half-life of the exchange reaction is 38 h. These results confirm that conditions
(pH, temperature, pK
a of the thiol) exist where prebiotically relevant thioesters can survive hydrolysis in water for long periods of time and
rates of thiol–thioester exchange exceed those of hydrolysis by several orders of magnitude. 相似文献
17.
The differences in pigment levels, photosynthetic activity and the chlorophyll fluorescence decrease ratio R
Fd (as indicator of photosynthetic rates) of green sun and shade leaves of three broadleaf trees (Platanus acerifolia Willd., Populus alba L., Tilia cordata Mill.) were compared. Sun leaves were characterized by higher levels of total chlorophylls a + b and total carotenoids x + c as well as higher values for the weight ratio chlorophyll (Chl) a/b (sun leaves 3.23–3.45; shade leaves: 2.74–2.81), and lower values for the ratio chlorophylls to carotenoids (a + b)/(x + c) (with 4.44–4.70 in sun leaves and 5.04–5.72 in shade leaves). Sun leaves exhibited higher photosynthetic rates P
N on a leaf area basis (mean of 9.1–10.1 μmol CO2 m−2 s−1) and Chl basis, which correlated well with the higher values of stomatal conductance G
s (range 105–180 mmol m−2 s−1), as compared to shade leaves (G
s range 25–77 mmol m−2 s−1; P
N: 3.2–3.7 μmol CO2 m−2 s−1). The higher photosynthetic rates could also be detected via imaging the Chl fluorescence decrease ratio R
Fd, which possessed higher values in sun leaves (2.8–3.0) as compared to shade leaves (1.4–1.8). In addition, via R
Fd images it was shown that the photosynthetic activity of the leaves of all trees exhibits a large heterogeneity across the
leaf area, and in general to a higher extent in sun leaves than in shade leaves. 相似文献
18.
Willis CK Turbill C Geiser F 《Journal of comparative physiology. B, Biochemical, systemic, and environmental physiology》2005,175(7):479-486
Data on thermal energetics for vespertilionid bats are under-represented in the literature relative to their abundance, as
are data for bats of very small body mass. Therefore, we studied torpor use and thermal energetics in one of the smallest
(4 g) Australian vespertilionids, Vespadelus vulturnus. We used open-flow respirometry to quantify temporal patterns of torpor use, upper and lower critical temperatures (T
uc and T
lc) of the thermoneutral zone (TNZ), basal metabolic rate (BMR), resting metabolic rate (RMR), torpid metabolic rate (TMR),
and wet thermal conductance (C
wet) over a range of ambient temperatures (T
a). We also measured body temperature (T
b) during torpor and normothermia. Bats showed a high proclivity for torpor and typically aroused only for brief periods. The
TNZ ranged from 27.6°C to 33.3°C. Within the TNZ T
b was 33.3±0.4°C and BMR was 1.02±0.29 mlO2 g−1 h−1 (5.60±1.65 mW g−1) at a mean body mass of 4.0±0.69 g, which is 55 % of that predicted for a 4 g bat. Minimum TMR of torpid bats was 0.014±0.006 mlO2 g−1 h−1 (0.079±0.032 mW g−1) at T
a=4.6±0.4°C and T
b=7.5±1.9. T
lc and C
wet of normothermic bats were both lower than that predicted for a 4 g bat, which indicates that V. vulturnus is adapted to minimising heat loss at low T
a. Our findings support the hypothesis that vespertilionid bats have evolved energy-conserving physiological traits, such as
low BMR and proclivity for torpor. 相似文献
19.
Long-term (30 d) effects of 100, 200, 300, and 400 mM NaCl on photosystem 2 (PS 2)-mediated electron transport activity and
content of D1 protein in the thylakoid membranes of chrysanthemum (Dendranthema grandiflorum) cultured in vitro at low irradiance 20 μmol(photon) m−2 s−1 were investigated. 100 mM NaCl increased contents of chlorophylls (Chl) a and b, carotenoids (Car; xanthophylls + carotenes), and the ratio of Chl a/b, and Car/Chl a+b. However, further increase in NaCl concentration led to the significant reduction in the contents of Chl a, and Chl b, and increase in the ratio of Chl a/b and Car/Chl a+b. NaCl treatment decreased the PS 2-mediated electron transport activity and contents of various thylakoid membrane polypeptides
including D1 protein. 相似文献
20.
Jan Pilarski 《Acta Physiologiae Plantarum》1999,21(4):365-373
The concentration of chlorophyll and a carotenoids in the bark of stems of different age and in the leaves of lilac (Syringa vulgaris L.) was determined.
The thickness of bark changes with the age of the stems, ranging from 0.73 mm in the current-year stems to 1.22 mm in 3-year-old
ones. Chlorophyll and carotenoids were present through the whole thickness of the bark, except the cork. It was found that
chlorophyll and carotenoids are located mainly in the outer layer of the bark, immediately under the cork, to a depth of 400
μm. In this layer the chlorophyll a/b ratio is the highest and the content of chlorophyll is four times larger than that of carotenoids. When penetrating deeper
into the bark, the content of chlorophyll and carotenoids as well as the chlorophyll a/b ratio diminishes.
Investigations of the leaves showed that most of the chlorophyll is found in the palisade parenchyma, the chlorophyll a/b ratio is the highest in the upper layer.
The highest concentration of chlorophyll in the bark is 0.44 mg·dm−2 and in leaves −1.2 mg−2·dm−2. The highest value of the chlorophyll a/b ratio in the bark is 3.8, and the lowest 0.5, while in the leaves it varies from 4.5 to 3.8 Low values of the chlorophyll
a/b ratio are due to the shade conditions existing in the bark and they are evidence of very great differentiation of light conditions
within it. 相似文献