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1.
Summary Indole alkaloids, particularly vindoline and catharanthine, were extracted from the leaves of Catharanthus roseus by supercritical extraction with CO 2. The contents of vindoline and catharanthine in the extracts were determined by HPLC and identified by LC/MS. About 52 %(w/w)
of the initial vindoline content, 1.5 mg vindoline/g dry wt leaves, was recovered after extracting this material for 10 h
with the CO 2 flow rate of 400 ml/min at 40°C and 150 bar. Vindoline concentration in the extract was 67 %(w/w). 相似文献
2.
Ubiquinone (Coenzyme Q10, CoQ10), a yellow-to-orange-colored lipophilic substance having nutraceutical value, was extracted
from dried biomass of Pseudomonas diminuta using supercritical carbon dioxide (SC-CO 2). The effect of different operational parameters (temperature, pressure, and extraction time) and addition of co-solvent
on SC-CO 2 extraction of CoQ10 was studied in detail. The solubility parameter of CoQ10, CO 2, and CO 2 with ethanol and methanol as co-solvents was calculated and validated with experimental results. Theoretically, ethanol and
methanol had significant effect as co-solvent, and the difference between the two was only marginal. A maximum recovery of
22.33% was obtained using pure SC-CO 2 at 40 °C, 150 bar, and run time of 60 min. Ethanol as co-solvent at 3 mL/g of dried biomass at 40 °C and 150 bar increased
the recovery from 22.33 to 68.57%. Further optimization of the extraction conditions by Box–Behnken design effectively increased
the recovery to 96.2%. The optimized conditions were a temperature of 38 °C, pressure of 215 bar, and run time of 58 min. 相似文献
3.
Physical cleaning and/or chemical cleaning have been generally used to control biofouling in the reverse osmosis (RO) process. However, conventional membrane cleaning methods to control biofouling are limited due to the generation of by-products and the potential for damage to the RO membranes. In this study, supercritical carbon dioxide (SC CO 2) treatment, an environmentally friendly technique, was introduced to control biofouling in the RO process. SC CO 2 (100 bar at 35°C) treatment was performed after biofouling was induced on a commercial RO membrane using Pseudomonas aeruginosa PA01 GFP as a model bacterial strain. P. aeruginosa PA01 GFP biofilm cells were reduced on the RO membrane by >8 log within 30 min, and the permeate flux was sufficiently recovered in a laboratory-scale RO membrane system without any significant damage to the RO membrane. These results suggest that SC CO 2 treatment is a promising alternative membrane cleaning technique for biofouling in the RO process. 相似文献
4.
Glucoamylase, acid protease, and acid carboxypeptidase in namazake were inactivated with microbubble super critical carbon dioxide (SC CO 2) at 25 MPa, 35°C for 30 min. After the treatment, their activities decreased from 330, 20.1, and 115 U /ml sake to 51.8, 1.8, and 0 U/ml sake, respectively. During the storage at 20°C for 60 days, no increase in amino acid value was observed. On the other hand, glucose concentration in the sake treated with SC CO 2 increased as well as namazake. The formation of lactic acid, acetic acid, and ethanol were depressed, and acidity was constant during storage. On the contrary, the decrease of pyruvic and malic acid after 20 days of storage could be depressed. Analysis of volatile compounds suggests that the treatment with SC CO 2 did not cause the formation of volatile compounds in contrast to heat-treatment. As a result of sensory evaluation, the sake treated with SC CO 2 at 20 MPa, 35°C for 30 min was given sensory scores near to those of namazake. 相似文献
5.
Conventional solvent extraction methods cannot attain high‐quality antioxidant extracts from microalgae and also require solvent recovery and posttreatment. In this study, we utilized environmental friendly supercritical carbon dioxide fluid extraction (SFE‐CO 2) techniques to obtain pigment (i.e. astaxanthin) from Haematococcus pluvialis. The effects of key operating parameters on the extraction efficiency of astaxanthin were investigated, giving an optimal condition of H. pluvialis weight, 6.5 g; CO 2‐flow rate, 6.0 NL/min; extraction time, 20 min; extraction pressure, 4500 psi; volume of ethanol modifier added, 9.23 mL/g; extraction temperature, 50°C; modifier composition, 99.5%. Under these optimum conditions, the astaxanthin yield was 73.9% (10.92 mg/g dry H. pluvialis powder) after eight cycle of extraction cycles. The saponification index (C S/C 0, representing the ratio of astaxanthin concentration after and before the saponification procedures) of the extract could be increased from 1 to 12.78 by saponification with 3.5 M NaOH. 相似文献
6.
This study reports an improved method for activating asphalt to produce ultra‐high surface area porous carbons. Pretreatment of asphalt (untreated Gilsonite, uGil ) at 400 °C for 3 h removes the more volatile organic compounds to form pretreated asphalt ( uGil‐P ) material with a larger fraction of higher molecular weight π‐conjugated asphaltenes. Subsequent activation of uGil‐P at 900 °C gives an ultra‐high surface area (4200 m 2 g ?1) porous carbon material ( uGil‐900 ) with a mixed micro and mesoporous structure. uGil‐900 shows enhanced room temperature CO 2 uptake capacity at 54 bar of 154 wt% (35 mmol g ?1). The CH 4 uptake capacity is 37.5 wt% (24 mmol g ?1) at 300 bar. These are relevant pressures in natural gas production. The room temperature working CO 2 uptake capacity for uGil‐900 is 19.1 mmol g ?1 (84 wt%) at 20 bar and 32.6 mmol g ?1 (143 wt%) at 50 bar. In order to further assess the reliability of uGil‐900 for CO 2 capture at elevated pressures, the authors study competitive sorption of CO 2 and CH 4 on uGil‐900 at pressures from 1 to 20 bar at 25 °C. CO 2/CH 4 displacement constants are measured at 2 to 40 bar, and found to increase significantly with pressure and surface area. 相似文献
7.
Many studies report that water flux through trees declines in response to elevated CO 2, but this response may be modified by exposure to increased temperatures. To determine whether elevated CO 2 and temperature interact to affect hydraulic conductivity, we grew ponderosa pine seedlings for 24 wk in growth chambers with one of four atmospheric CO 2 concentrations (350, 550, 750, and 1100 ppm) and either a low (15°C nights, 25°C days) or high (20°C nights, 30°C days) temperature treatment. Vapor pressure deficits were also higher in the elevated temperature treatment. Seedling biomass increased with CO 2 concentration but was not affected by temperature. Root : shoot ratio was unaffected by CO 2 and temperature. Leaf : sapwood area ratio ( AL/ AS) declined in response to elevated temperature but was not influenced by CO 2. Larger tracheid diameters at elevated temperature caused an increase in xylem-specific hydraulic conductivity ( KS). The increase in KS and decrease in AL/ AS led to higher leaf-specific hydraulic conductivity ( KL) at elevated temperature. Stomatal conductance ( gS) was correlated with KL across all treatments. Neither KS, KL, nor gS were affected by elevated CO 2 concentrations. High KL in response to elevated temperature may support increased transpiration or reduce the incidence of xylem cavitation in ponderosa pine in future, warmer climates. 相似文献
8.
The relation between photosynthesis and water content was investigated using detached leaves of Populus euramericana (Dode) Guinier cv. Robusta. The time course of photosynthesis was measured at different light intensities, at different CO 2 contents of the air and at constant temperature during the desiccation of the leaves. The time course of decreasing water content was obtained from continuous measurement of water transpired from the leaves. A large reduction of light saturated (400 W × m −2) photosynthetic rates was observed with decreasing water contents between 78 and 64% (water potential between −14 and −24 atm (bar)). This reduction was much greater in air with 0.3 % CO 2 than in air with 5 % CO 2, indicating a significant influence of CO 2 diffusion resistance on rate of photosynthesis. The reduction of the rate of light and CO 2 saturated photosynthesis (at 400 W × m –2 and 5% CO 2 in the air) is a measure of the inactivation of the photosynthetic enzyme system by desiccation. A proportional reduction of the light saturated and light limited rate of photosynthesis (for different H 2O contents) was found, when measured in air containing a saturating amount of CO 2 (5 %). The reduction of the light limited rate of photosynthesis (at 20 W × m −2) was the same at both CO 2 levels. 相似文献
9.
Virus-free individuals of the plant-hopper Javesella pellucida (Fabr.) infected plants with European wheat striate mosaic virus (EWSMV) after being injected at 5° C. with extracts of either plants or hoppers, but extracts of hoppers provided a better inoculum. Hoppers were unable to infect plants until at least 8 days at 20–25° C. after they were injected, and nymphs fed on infected plants similarly required 8 days before they gave infective extracts. Few hoppers survived more than a week after injection with untreated extracts of hoppers or with material sedimented from them by centrifuging the extracts at 8000 g, but 60–70% survived injection with purer virus preparations. Injection of the virus seemed harmless, because as many hoppers survived CO 2 anaesthesis + injection, whether or not they later infected plants, as survived anaesthesis without injection. Attempts to determine the properties of the virus in vitro gave inconsistent results, but virus from hoppers was still infective after 10 min. at 30° C, 36 hr. at 5° C, precipitation at pH 4.0, storage for several months at -15° C, or at a dilution equivalent to 0.0014 g. hopper/ml. The best extraction medium contained 0.2 M-Na 2HPO 4+ ascorbic acid + 0.01 M-DIECA at pH 7.0–7.3. In sucrose density-gradients, EWSMV sedimented more slowly than tobacco mosaic virus. No specific particle with which infectivity could be correlated was seen by electron microscopy. 相似文献
10.
The effect of a wide range of temperatures (?15 and 60°C) in darkness or under strong irradiation [1,600 μmol(photon) m ?2 s ?1] on quantum yield of photosystem II photochemistry and xanthophyll cycle pigments was investigated in a tropical fruit crop ( Musa sp.) and a temperate spring flowering plant ( Allium ursinum L.). In darkness within the nonlethal thermal window of A. ursinum (from ?6.7 to 47.7°C; 54.5 K) and of Musa sp. (from ?2.2°C to 49.5°C; 51.7 K) maximal quantum yield of PSII photochemistry (F v/F m) was fairly unaffected by temperature over more than 40 K. At low temperature F v/F m started to drop with ice nucleation but significantly only with initial frost injuries (temperature at 10% frost damage; LT 10). The critical high temperature threshold for PSII (T c) was 43.8°C in A. ursinum and 44.7°C in Musa sp. Under strong irradiation, exposure to temperatures exceeding the growth ones but being still nonlethal caused photoinhibition in both species. Severity of photoinhibition increased with increasing distance to the growth temperature range. ΔF/F m′ revealed distinctly different optimum temperature ranges: 27–36°C for Musa sp. and 18–27°C for A. ursinum exceeding maximum growth temperature by 2–7 K. In both species only at temperatures > 30°C zeaxanthin increased and violaxanthin decreased significantly. At nonlethal low temperature relative amounts of xanthophylls remained unchanged. At temperatures > 40°C β-carotene increased significantly in both species. In Musa sp. lutein and neoxanthin were significantly increased at 45°C, in A. ursinum lutein remained unchanged, neoxanthin levels decreased in the supraoptimal temperature range. In darkness, F v/F m was highly temperature-insensitive in both species. Under strong irradiation, whenever growth temperature was exceeded, photoinhibition occurred with xanthophylls being changed only under supraoptimal temperature conditions as an antiradical defence mechanism. 相似文献
11.
Unstable snow cover and more frequent freeze–thaw events have been predicted for montane areas in southern Norway, where stable winters are common today. These systems are important contributors to the flux of carbon (C) and nitrogen (N) to air and water. Here we quantify and compare the effects of freeze–thaw on C and N release from soils collected below Calluna, Molinia or Sphagnum. Intact organic soil cores were subjected to four different freeze–thaw regimes for four consecutive 2‐week periods: (1) slow cycling (SC) with one long freezing event during each 2‐week period, (2) fast cycling (FC) with four short freezing events during each 2‐week period, (3) permanent frost (PF) and (4) permanent thaw (PT). The freezing temperature was −5 °C and the thawing temperature was 5 °C. Before start of treatment, at the end of each 2‐week period, and during postincubation periods, carbon dioxide (CO 2) emission as well as leachable dissolved organic C (DOC), dissolved organic N (DON), ammonium (NH 4), nitrate (NO 3) and absorbance at 254 nm were measured. In soils from all three vegetations, PF increased the release of CO 2, DOC, DON and NH 4 compared with PT. SC caused some scattered effects whereas FC only resulted in some increase in NO 3 release below Molinia. Generally, the emission of CO 2 and leaching of DOC, DON and NH 4 increased in the following order: Sphagnum < Calluna < Molinia. The release of NO 3 was greatest below Calluna. Our data suggest that vegetation cover and composition seem at least as important as increased soil frost for future winter fluxes of CO 2, DOC, DON and dissolved inorganic N (DIN) from the soil to air and water. The freezing period needs to be sufficiently long to give significant effects. 相似文献
12.
Summary Red algae have the highest known selectivity factor (S rel) for CO 2 over O 2 of ribulose bisphosphate carboxylase-oxygenase (RUBISCO). This allows the prediction that a red alga relying on diffusive supply of CO 2 to RUBISCO from air-equilibrated solution should have less O 2 inhibition of photosynthesis than would an otherwise similar non-red alga with a lower S rel of RUBISCO. Furthermore, RUBISCO shows an increased S rel values at low temperatures. The prediction that O 2inhibition of photosynthesis should be small for marine red algae relying on diffusive CO 2 entry growing in the North Sea with an annual temperature range of 4–16°C was tested in O 2 electrode experiments at 12°C. Phycodrys rubens and Plocamium cartilagineum, which rely on diffusive CO 2 entry showed, as predicted, only a small inhibition at lower inorganic C concentrations. Palmaria palmata, which has a CO 2 concentrating mechanism, had the expected negligible O 2 inhibition of photosynthesis at any inorganic C concentration except (non-significantly) for saturating inorganic C. 相似文献
13.
The impact of in-situ CO2 nano-bubbles generation on the freezing properties of soft serve, milk, and apple juice was investigated. Carbonated (0, 1000, and 2000 ppm) liquid foods contained in a tube were submerged and cooled for 90 min in a pre-set ethylene glycol bath (−15 °C). Before the enclosed liquid reached 0 °C, the vibration was discharged through ultrasound in the bath to create nano-bubbles within the carbonated food samples, and the changes in temperature for 90 min of each food were recorded as a freezing curve. The time for onset of nucleation of control soft serve mix was halved in samples with 2000-ppm CO2 due to the presence of nano-bubbles. Likewise, the nucleation time for milk with and without nano-bubbles at the same CO2 concentration of 2000 ppm was 7.9 ± 0.1 and 2.8 ± 0.8 min, respectively. The generation of CO2 nano-bubbles from 2000-ppm CO2 level in 10 oBx apple juice displayed −9.3 ± 0.3 °C nucleation temperature while the control one had −11.7 ± 0.9 °C. 相似文献
14.
Abstract When tomato plants of the high-altitude species Lycopersicon hirsutum and of the cultivated Lycopersicon esculentum were grown at 24/18°C (day/night), the effects of temperature, photon flux density, and intercellular CO 2 concentration up to about 600 μl l ?1 on net CO 2 uptake were similar in the two species. Acclimation of these plants at 12/6°C (day/night) resulted, after 4 d or longer, in a similar downward shift of about 5°C in the optimum temperature for CO 2 uptake. However, in comparison with the cultivated species, the high-altitude plants achieved a higher rate of CO 2 uptake at saturating concentrations of intercellular CO 2, maintained a higher level of saturating-light CO 2 uptake rate at 10°C after exposure to chilling stress (10°C and photon flux density of 400 μmol m ?2s ?1 d and 5°C night) for 7–18 d, and displayed a better capacity for rapid recovery after prolonged stress. The greater capacity for CO 2 uptake observed in the high-altitude species during and after exposure to chilling stress was also reflected in its higher growth rate under those conditions compared with plants of L. esculentum. These advantages of the high-altitude species may partly explain its ability to survive and complete its life cycle under the environmental conditions prevailing in its natural habitat. 相似文献
15.
Aims: This paper presents a research on the disinfection efficiency of inoculated textile swatches by compressed carbon dioxide, an environmental friendly way to disinfect textiles as opposed to the conventional laundering procedures using water. The disinfection efficiency was determined by using the following microbes inoculated on cotton test fabrics: Enterococcus faecium, Enterobacter aerogenes and Candida albicans. Methods and Results: The experiments were performed using the high pressure extraction device with a maximum pressure of 50 MPa and a small extraction vessel of 500 ml. Pure CO 2 and CO 2 with added disinfection agent or commercial detergent were used. The chosen disinfecting agent was hydrogen peroxide, a widespread disinfecting chemical. It was found that treatment with CO 2 for 25 min at 5 MPa and 40°C (313K) and the addition of 4 ml of specific detergent per litre of CO 2 assures at least a five log step reduction of Enterobacter aerogenes and C. albicans, whilst treatment at 50°C (323K) with CO 2 for 25 min at 5 MPa is sufficient for at least a five log step reduction for Enterococcus faecium. It was also found that a 15‐min CO 2 treatment at 7 MPa and 20°C (293K) was sufficient for the inactivation of the yeast C. albicans, whilst these conditions were not rigorous enough for the challenge bacteria. On the other hand, the labscale treatment with CO 2 for 25 min at pressure 4 and 6 MPa with the addition of detergent or hydrogen peroxide only yields a log step reduction of up to 4 log steps, thus proving the slightly disinfective properties of the CO 2 treatment with added agents, but not reaching efficient results as a 5 log step reduction was not reached. Conclusions: Addition of heat to the compressed CO 2 treatment of textiles inoculated with microorganisms proved more effective than the addition of detergent or disinfectant with compressed CO 2 treatment at temperature of 20°C. Significance and Impact of the Study: CO 2 treatment of textiles is a promising ecological alternative dry‐cleaning method for the disinfection of medical textiles. 相似文献
16.
To determine the effects of elevated CO 2 concentration ([CO 2]) on the temperature‐dependent photosynthetic properties, we measured gas exchange and chlorophyll fluorescence at various leaf temperatures (15, 20, 25, 30, 35 and 40°C) in 1‐year‐old seedlings of the Japanese white birch ( Betula platyphylla var. japonica), grown in a phytotron under natural daylight at two [CO 2] levels (ambient: 400 µmol mol ?1 and elevated: 800 µmol mol ?1) and limited N availability (90 mg N plant ?1). Plants grown under elevated [CO 2] exhibited photosynthetic downregulation, indicated by a decrease in the carboxylation capacity of Rubisco. At temperatures above 30°C, the net photosynthetic rates of elevated‐CO 2‐grown plants exceeded those grown under ambient [CO 2] when compared at their growth [CO 2]. Electron transport rates were significantly lower in elevated‐CO 2‐grown plants than ambient‐CO 2‐grown ones at temperatures below 25°C. However, no significant difference was observed in the fraction of excess light energy [(1 ? q P)× F v′/F m′] between CO 2 treatments across the temperature range. The quantum yield of regulated non‐photochemical energy loss was significantly higher in elevated‐CO 2‐grown plants than ambient, when compared at their respective growth [CO 2] below 25°C. These results suggest that elevated‐CO 2‐induced downregulation might not exacerbate the temperature‐dependent susceptibility to photoinhibition, because reduced energy consumption by electron transport was compensated for by increased thermal energy dissipation at low temperatures. 相似文献
17.
Three experimental trials have been carried out on the basil (Ocimum basilicum)–downy mildew (Peronospora belbahrii) pathosystem, under phytotron conditions, to evaluate the effect of simulated elevated atmospheric CO 2 concentrations and temperatures as well as that of their interaction. Six CO 2 and temperature combinations were tested to establish their effect on disease development. The photosynthetic efficiency (PI) and chlorophyll content index (CCI) of the basil plants were monitored throughout the trials. Average disease incidence was 43.8% under standard conditions (18–22°C and 400–450 ppm of CO 2) , while average disease severity was 22.1%. In the same temperature regime, a doubled level of CO 2 caused a significant increase in both disease incidence and severity. When temperatures ranged between 18 and 26°C, CO 2 at 800–850 ppm increased disease incidence. At the highest temperatures tested, that is at 26–30°C, which are not favourable for downy mildew development, the increase in CO 2 had no significant effect on disease incidence. A decreasing trend of PI was observed for the PI values of the inoculated plants. This trend was particularly pronounced for high CO 2 levels at the end of the experiment. In the same way as for disease development, lower values were recorded for the inoculated plants at the end of the experiment at 18–22°C for both CO 2 concentrations and at 22–26°C for 850 ppm of CO 2. The non‐inoculated plants showed higher photosynthetic efficiency than the inoculated plants. Similar trends were also observed for the CCI, thus confirming that downy mildew incidence and severity, which in particular caused foliar damage at high CO 2 concentrations, led to a decrease in the physiological performances. 相似文献
18.
This study describes the extraction and characterization of a novel inhibitor against β-hydroxy-β-methyl glutaryl (HMG) Coenzyme
A (CoA) reductase from the mushroom Pholiota adiposa. Methanol extracts of P. adiposa PAD-022 fruiting body showed the highest HMG-CoA reductase-inhibitory activity of 55.8%. The HMG-CoA reductase-inhibitor, P. adipos a PAD-022, was maximally extracted when its fruiting body was treated with methanol at 30°C for 12 h. The HMG-CoA reductase-inhibitor
was obtained by systematic solvent extraction methods followed by gel column chromatography, and RP-HPLC. The purified product
was found to possess an activity of IC 50 6.8 μg and a yield of 1.8%. The molecular weight of purified HMG-CoA reductase-inhibitor was deduced to be 412.7 Da. The
inhibitor was identified as stigmasterol (C 29H 46O) by serial instrumental analyses, including LC-Mass. NMR, FT-IR, and UV spectrometry. 相似文献
19.
Two pennate diatoms, Amphora coffeaeformis and Nitzschia ovalis, were used to evaluate potential responses to the future CO 2 and temperature increases with respect to cell-specific growth rate, elemental composition, size, population growth rate, and carrying capacity. Diatoms were subjected to four different treatments over a 2 week period (approximately 4 generations): a control (28°C and present-day CO 2, ~400 ppm), high CO 2 (28°C with high CO 2, ~750 ppm), high temperature (31°C and present-day CO 2, ~400 ppm), and greenhouse-effect treatment (31°C with high CO 2, ~750 ppm). The results indicated that both the cell-specific growth rates and the carrying capacity of A. coffeaeformis decreased at the higher temperature treatment, whereas N. ovalis did not differ among all treatments. No significant difference was found in either species’ elemental cell composition, but higher C:N and C:P ratios were observed for A. coffeaeformis and N. ovalis, respectively, in high CO 2 and greenhouse-effect treatments. Smaller cell sizes were observed for both species under the greenhouse-effect treatment, a phenomenon that could alter benthic food webs in the future. 相似文献
20.
Prunus dulcis, the almond, is a predominantly self-incompatible (SI) species with a gametophytic self-incompatibility system mediated by
S-RNases. The economically important allele S
f
, which results in self-compatibility in P. dulcis, is said to have arisen by introgression from Prunus webbii in the Italian region of Apulia. We investigated the range of self-(in)compatibility alleles in Apulian material of the two
species. About 23 cultivars of P. dulcis (14 self-compatible (SC) and nine SI) and 33 accessions of P. webbii (16 SC, two SI and 15 initially of unknown status), all from Apulia, were analysed using PCR of genomic DNA to amplify S-RNase alleles and, in most cases, IEF and staining of stylar protein extracts to detect S-RNase activity. Some amplification products were cloned and sequenced. The allele S
f
was present in nearly all the SC cultivars of P. dulcis but, surprisingly, was absent from nearly all SC accessions of P. webbii. And of particular interest was the presence in many SI cultivars of P. dulcis of a new active allele, labelled S
30
, the sequence of which showed it to be the wild-type of S
f
so that S
f
can be regarded as a stylar part mutant S
30
°. These findings indicate S
f
may have arisen within P. dulcis, by mutation. One SC cultivar of P. dulcis, ‘Patalina’, had a new self-compatibility allele lacking RNase activity, S
n5
, which could be useful in breeding programmes. In the accessions of P. webbii, some of which were known to be SC, three new alleles were found which lacked RNase activity but had normal DNA sequences. 相似文献
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