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1.
Fruits of Garden Lettuce, imbibed in 0.01 M KNO3, were depleted of maternal active phytochrome B by saturating deep-red exposure and photosensitized by chilling for 1 week
at 4 °C. Twenty saturated fluence-response curves for photoinduced germination were elaborated between 300 and 800 nm, using
exposure periods from 6 to 600 s at 22.5 °C; there is linear and closely parallel regression in the logarithmic probability
net. The reciprocals of the half-response fluences obtained gave the apparent conversion spectrum of the controlling pigments
and this was corrected for the transmittance of the seed-coat. It is a phytochrome spectrum of P
r with photoconversion cross-sections of 1.2·109 and 4.5·103 m2 mol–1 at 666 and 800 nm, respectively. This means that for half-saturated germination of sensitized seed, fewer than 1 out of 200,000
phytochrome A molecules have to be photoconverted to P
fr, and no photo-reversibility by deep-red was found. Therefore, all spectral colours of nightly moon- or skylight should stimulate
the germination of sensitized weed seeds if they are exposed at the soil surface between sequential tillage operations.
Received: 28 April 2000 / Accepted in revised form: 28 July 2000 相似文献
2.
We have found that giant hornets (Vespa mandarinia japonica) are killed in less than 10 min when they are trapped in a bee ball created by the Japanese honeybees Apis cerana japonica, but their death cannot be solely accounted for by the elevated temperature in the bee ball. In controlled experiments, hornets
can survive for 10 min at the temperature up to 47°C, whereas the temperature inside the bee balls does not rise higher than
45.9°C. We have found here that the CO2 concentration inside the bee ball also reaches a maximum (3.6 ± 0.2%) in the initial 0–5 min phase after bee ball formation.
The lethal temperature of the hornet (45–46°C) under conditions of CO2 concentration (3.7 ± 0.44%) produced using human expiratory air is almost the same as that in the bee ball. The lethal temperature
of the honeybee is 50–51°C under the same air conditions. We concluded that CO2 produced inside the bee ball by honeybees is a major factor together with the temperature involved in defense against giant
hornets. 相似文献
3.
Xiaoming Xu Jie Tang Zhaoyang Li Chang Liu Weizheng Han 《Mitigation and Adaptation Strategies for Global Change》2011,16(6):721-731
In this study, paddy fields in Jilin province which are flooded parcel of arable lands used for growing rice (Oryza sativa Linn.) were selected as the object. Long-term exploitation of paddy fields led to variations of soil organic carbon (SOC) and green
house gases (GHGs) emissions which might contribute to global warming. In order to calculate the amount of global warming
potentials (GWPs) of emissions from ricepaddies and find the correlations among rice yield, SOC storage and GWP, DeNitrification-DeComposition
(DNDC) model was used to simulate SOC densities and fluxes of main GHGs emitted from paddy fields. After verification, simulation
results were used to calculate SOC storages and 100-year GWPs from 1949 to 2009. Results indicated that SOC densities in depths
of 0–10 cm, 10–20 cm and 20–30 cm all kept increasing. Average methane (CH4) and nitrous oxide (N2O) fluxes were 278.55 kg carbon (kgC) ha−1 a−1 and 2.22 kg nitrogen (kgN) ha−1 a−1. The SOC storage (0–30 cm) had increased from 3.96 × 109kgC in 1949 to 47.85 × 109kgC in 2009. In addition, GWP emission was increasing exponentially in the past 61 years, from 0.16 × 106 Mg carbon dioxide equivalents (CO2-equivalents) to 66.36 × 106 Mg CO2-equivalents. Both SOC storage and GWP presented obviously linear relation to rice yields. Overall, the research suggested
that long-term rice yields could be used to estimate the SOC storage and GWP variations. 相似文献
4.
Jie Tang Xiaoming Xu Zhaoyang Li Weizheng Han 《Mitigation and Adaptation Strategies for Global Change》2012,17(1):103-109
The study area of this article, Western Jilin province of China, was a typical area responding to global changing in middle
latitude areas. In this paper, by interpreting the thematic mapper (TM) images of the study area in the years of 1989, 1996,
2000 and 2004, the land use/cover change (LUCC) data were achieved, which included the area of paddy fields and its spatial
distributions. 113 soil samples were collected to obtain soil organic carbon (SOC) data of different land use types. After
that, the organic matter contents of these samples were measured by using the potassium dichromate oxidation-outer heating
method. Based on the data above, the amount of SOC sequestrated by the surface soil (0~30 cm) of paddy fields was calculated.
The result showed that: the area of paddy fields was increasing continuously in western Jilin, from 11.28 × 104 hm2 in 1989 to 22.77 × 104 hm2 in 2004. Paddy fields transferred from wetlands, grasslands and water areas accounted for the main part of the paddy fields
in 2004, the areas were 3.09 × 104 hm2, 2.98 × 104 hm2 and 2.8 × 104 hm2, respectively. And paddy fields with a total area of 0.83 × 104 hm2 degraded into saline-alkali lands. The amount of organic carbon sequestration in the surface layer (0–30 cm) of paddy fields
was 658.86 × 104 t. The primary SOC sinks located around the joint of Baicheng City and Zhenlai County, while the major SOC source located
at Songyuan City and northern Qianguo County. 相似文献
5.
Stephan Baumgartner Martin Wolf Peter Skrabal Felix Bangerter Peter Heusser André Thurneysen Ursula Wolf 《Die Naturwissenschaften》2009,96(9):1079-1089
Quantitative meta-analyses of randomized clinical trials investigating the specific therapeutic efficacy of homeopathic remedies
yielded statistically significant differences compared to placebo. Since the remedies used contained mostly only very low
concentrations of pharmacologically active compounds, these effects cannot be accounted for within the framework of current
pharmacology. Theories to explain clinical effects of homeopathic remedies are partially based upon changes in diluent structure.
To investigate the latter, we measured for the first time high-field (600/500 MHz) 1H T1 and T2 nuclear magnetic resonance relaxation times of H2O in homeopathic preparations with concurrent contamination control by inductively coupled plasma mass spectrometry (ICP-MS).
Homeopathic preparations of quartz (10c–30c, n = 21, corresponding to iterative dilutions of 100−10–100−30), sulfur (13x–30x, n = 18, 10−13–10−30), and copper sulfate (11c–30c, n = 20, 100−11–100−30) were compared to n = 10 independent controls each (analogously agitated dilution medium) in randomized and blinded experiments. In none of the
samples, the concentration of any element analyzed by ICP-MS exceeded 10 ppb. In the first measurement series (600 MHz), there
was a significant increase in T1 for all samples as a function of time, and there were no significant differences between homeopathic potencies and controls.
In the second measurement series (500 MHz) 1 year after preparation, we observed statistically significant increased T1 relaxation times for homeopathic sulfur preparations compared to controls. Fifteen out of 18 correlations between sample
triplicates were higher for controls than for homeopathic preparations. No conclusive explanation for these phenomena can
be given at present. Possible hypotheses involve differential leaching from the measurement vessel walls or a change in water
molecule dynamics, i.e., in rotational correlation time and/or diffusion. Homeopathic preparations thus may exhibit specific
physicochemical properties that need to be determined in detail in future investigations.
Electronic supplementary material The online version of this article (doi:) contains supplementary material, which is available to authorized users. 相似文献
6.
Marcelo Perantoni Darci M. S. Esquivel Eliane Wajnberg Daniel Acosta-Avalos Geraldo Cernicchiaro Henrique Lins de Barros 《Die Naturwissenschaften》2009,96(6):685-690
Magnetotactic microorganisms use the interaction of internal biomineralized nanoparticles with the geomagnetic field to orientate.
The movement of the magnetotactic multicellular prokaryote Candidatus Magnetoglobus multicellularis under an applied magnetic field was observed. A method using digital image processing techniques
was used to track the organism trajectory to simultaneously obtain its body radius, velocity, U-turn diameter, and the reorientation
time. The magnetic moment was calculated using a self-consistent method. The distribution of magnetic moments and radii present
two well-characterized peaks at (9 ± 2) × 10−15 and (20 ± 3) × 10−15 A m2 and (3.6 ± 0.1) and (4.3 ± 0.1) μm, respectively. For the first time, simultaneous determination of the distribution of the
organism radii and magnetic moment was obtained from the U-turn method by a new digital imaging processing. The bimodal distributions
support an organism reproduction process model based on electron microscopy observations. These results corroborate the prokaryote
multicellular hypothesis for Candidatus M. multicellularis. 相似文献
7.
Light-dependent magnetoreception in birds: the effect of intensity of 565-nm green light 总被引:1,自引:0,他引:1
In a previous study, Australian silvereyes tested in autumn under monochromatic 565-nm green light at intensities of 2.1
and 7.5 mW m–2 preferred their normal northerly migratory direction, whereas they showed a significantly different tendency towards northwest
at 15.0 mW m–2. Repeating these experiments in spring with silvereyes migrating southward, we again observed well-oriented tendencies in
the migratory direction at 2.1 and 7.5 mW m–2. At 15.0 mW m–2, however, the birds once more preferred northwesterly directions, i.e. their response under this condition proved to be independent
of the migratory direction. This contradicts the interpretation that monochromatic green light of this high intensity leads
to a rotation of compass information; instead, it appears to produce sensory input that causes birds to give up their migratory
direction in favor of a fixed direction of as yet unknown origin.
Received: 3 April 2000 / Accepted in revised form: 19 June 2000 相似文献
8.
Summer phytoplankton assemblages from surface waters off Kuwait were enriched with levels of eolian dust (105, 106, and 107 mg/m3), similar to seasonal dust fallout for this region. Algal growth was positive and dose dependent. Highest biomass was up
to 527 μg chlorophyll a/l on day 5. The maximum doublings of biomass per day were 0.64, 0.77, and 1.42, corresponding to 105, 106, and 107 mg/m3 enrichment and were significantly higher than the 0.56 for control. Changes in the phytoplankton species composition occurred
with changes in biomass, with small algae dominating peak populations. It is suggested that through enrichment of trace elements
via eolian dust, a high level of phytoplankton biomass and growth can be sustained in this arid environment.
Received: 15 October / Accepted in revised form: 16 June 1999 相似文献
9.
Yury G. Shckorbatov 《Die Naturwissenschaften》1999,86(9):452-453
Cells of human buccal epithelium were irradiated in vitro by laser light at a wavelength of 632.8 nm and and an intensity
of 1 mW/cm2. The irradiation induced changes in the chromatin condensation state. The effect of irradiation depends on exposure time,
and cells of different donors reveal varying sensitivity to laser light. In some donors 1 s exposure induced decondensation,
but 2.5 min and 5 min condensation of chromatin in all donors.
Received: 10 June 1998 / Accepted in revised form: 7 May 1999 相似文献
10.
Numerical dating of the Eckfeld maar fossil site, Eifel, Germany: a calibration mark for the Eocene time scale 总被引:1,自引:0,他引:1
Sediments of the Eckfeld maar (Eifel, Germany) bear a well-preserved Eocene fauna and flora. Biostratigraphically, Eckfeld
corresponds to the Middle Eocene mammal reference level MP (Mammals Paleogene) 13 of the ELMA (European Land Mammal Age) Geiseltalian.
In the maar crater, basalt fragments were drilled, representing explosion crater eruption products. By 40Ar/39Ar dating of the basalt, for the first time a direct numerical calibration mark for an Eocene European mammal locality has
been established. The Eckfeld basalt inverse isochron date of 44.3±0.4 Ma suggests an age for the Geiseltalian/Robiacian boundary
at 44 Ma and, together with the 1995 time scale of Berggren et al., a time span ranging from 49 to 44 Ma for the Geiseltalian
and from 44 to 37 Ma for the Robiacian, respectively. Additional 40Ar/39Ar dating on a genetically related basalt occurrence close to the maar confirms a period of volcanism of ca. 0.6 m.y. in the
Eckfeld area, matching the oldest Eocene volcanic activity of the Hocheifel volcanic field.
Received: 27 December 1999 / Accepted in revised form: 6 April 2000 相似文献
11.
Alexander Lerchl 《Die Naturwissenschaften》1999,86(7):340-342
The relationship between average monthly air temperature and sex ratios at birth (SRB) was analyzed for children born in
Germany during the period 1946–1995. Both the absolute temperature and – more markedly – the monthly temperature deviations
from the overall mean were significantly positively correlated with the SRB (P<0.01) when temperatures were time-lagged against the SRB data by –10 or –11 months. It is concluded that the sex of the offspring
is partially determined by environmental temperatures prior to conception.
Received: 26 August 1998 / Accepted in revised form: 18 February 1999 相似文献
12.
Rebeca B. Rosengaus James F. A. Traniello Tammy Chen Julie J. Brown Richard D. Karp 《Die Naturwissenschaften》1999,86(12):588-591
Although pathogens appear to have exerted significant selective pressure on various aspects of sociality, mechanisms of disease
resistance in the social insects are poorly understood. We report here on an immune response to infection by the dampwood
termite, Zootermopsis angusticollis. Nymphs immunized with an injection of 7.6×107, 7.6×105, or 7.6×104 cells/ml glutaraldehyde-killed solution of the bacterium Pseudomonas aeruginosa had significantly higher survivorship than controls following a challenge with a lethal concentration of active bacteria.
Similarly, nymphs exposed to a 9×10–1 spores/ml suspension of the fungus Metarhizium anisopliae had higher survivorship than controls after a challenge with a lethal concentration of spores. Prior exposure to a pathogen
thus conferred upon termites a degree of protection during a subsequent encounter with the same pathogen. This represents
the first demonstration of immune function in vivo in a social insect.
Received: 18 May 1999 / Accepted in revised form: 26 August 1999 相似文献
13.
Qian Yao Hua Zhang Jun Wu Liming Shao Pinjing He 《Frontiers of Environmental Science & Engineering in China》2010,4(3):286-294
Batch biosorption experiments were conducted to remove Cr(III) from aqueous solutions using activated sludge from a sewage
treatment plant. An investigation was conducted on the effects of the initial pH, contact time, temperature, and initial Cr(III)
concentration in the biosorption process. The results revealed that the activated sludge exhibited the highest Cr(III) uptake
capacity (120 mg·g−1) at 45°C, initial pH of 4, and initial Cr(III) concentration of 100 mg·L−1. The biosorption results obtained at various temperatures showed that the biosorption pattern accurately followed the Langmuir
model. The calculated thermodynamic parameters, ΔGo° ( − 0.8–4.58 kJ·mol−1), ΔH° (15.6–44.4 kJ·mol−1), and ΔS° (0.06–0.15 kJ·mol−1·K−1) clearly indicated that the biosorption process was feasible, spontaneous, endothermic, and physical. The pseudo first-order
and second-order kinetic models were adopted to describe the experimental data, which revealed that the Cr(III) biosorption
process conformed to the second-order rate expression and the biosorption rate constants decreased with increasing Cr (III)
concentration. The analysis of the values of biosorption activation energy (E
a = −7 kJ·mol−1) and the intraparticle diffusion model demonstrated that Cr(III) biosorption was film-diffusion-controlled. 相似文献
14.
Where clocks are redundant: weak circadian mechanisms in reindeer living under polar photic conditions 总被引:1,自引:0,他引:1
Biological rhythms are a result of interplay between endogenous clocks and the ambient light–dark (LD) cycle. Biological timing
in resident polar organisms presents a conundrum because these experience distinct daily LD cycles for only a few weeks each
year. We measured locomotor activity in reindeer, Rangifer tarandus platyrhynchus (SR, n = 5 and 6) and R. tarandus tarandus (NR, n = 6), ranging freely at 78 and 70°N, respectively, continuously throughout 1 year using data loggers. NR, but not SR, are
gregarious which enabled us to examine the integrated effects of differences in social organisation and the photic environment
at two different latitudes on the organisation of activity. In both sub-species, ultradian bouts of activity and inactivity
alternated across the 24-h day throughout the year. This pattern was modified by the LD cycle in NR but barely at all in SR.
Periodogram analysis revealed significant ultradian rhythmicity in both sub-species; the frequency of daily cycles of activity
increased from three per day in winter to nearly five in summer. We conclude that this increase, and a concomitant increase
in the level of daily activity, reflected the seasonal increase in the animals’ appetite and the quality of their forage.
Secondly, the combination, most evident in SR, of a weak photic response, weak circadian mechanisms and a weak social synchronization
reduces the constraints of biological timing in an environment which is effectively non-rhythmic most of the year and permits
expression of the basic ultradian pattern of ruminant activity. Third, the weaker 24-h rhythmicity in SR compared to NR indicates
a latitudinal decrease in circadian organization and photic responsiveness in Rangifer. 相似文献
15.
Light-Dependent Magnetoreception in Birds: Does Directional Information Change with Light Intensity?
Magnetic compass orientation in birds is based on light-dependent processes, with magnetoreception being possible only under
light containing blue and green wavelengths. To look for possible intensity-dependent effects we tested Australian silvereyes
during autumn migration under monochromatic green light (565 nm) produced by light-emitting diodes at various light levels.
At intensities of 0.0021 and 0.0075 W/m2, the birds showed normal activity and were oriented in their seasonally appropriate migratory direction. Under low light
of 0.0002 W/m2 the birds were less active; scatter increased, but they still oriented in their migratory direction. Under a high light level
of 0.0150 W/m2, however, the test birds showed a counterclockwise shift in direction, preferring west-northwest instead of north. This change
in behavior may reflect a change in the output of the magnetoreception system, resulting from a disruption of the natural
balance between the wavelengths of light.
Received: 18 June 1999 / Accepted in revised form: 20 September 1999 相似文献
16.
Cerumen, or propolis, is a mixture of plant resins enriched with bee secretions. In Australia, stingless bees are important
pollinators that use cerumen for nest construction and possibly for colony’s health. While extensive research attests to the
therapeutic properties of honeybee (Apis mellifera) propolis, the biological and medicinal properties of Australian stingless bee cerumen are largely unknown. In this study,
the chemical and biological properties of polar extracts of cerumen from Tetragonula carbonaria in South East Queensland, Australia were investigated using gas chromatography-mass spectrometry (GC-MS) analyses and in
vitro 5-lipoxygenase (5-LOX) cell-free assays. Extracts were tested against comparative (commercial tincture of A. mellifera propolis) and positive controls (Trolox and gallic acid). Distinct GC-MS fingerprints of a mixed diterpenic profile typical
of native bee cerumen were obtained with pimaric acid (6.31 ± 0.97%, w/w), isopimaric acid (12.23 ± 3.03%, w/w), and gallic
acid (5.79 ± 0.81%, w/w) tentatively identified as useful chemical markers. Characteristic flavonoids and prenylated phenolics
found in honeybee propolis were absent. Cerumen extracts from T. carbonaria inhibited activity of 5-LOX, an enzyme known to catalyse production of proinflammatory mediators (IC50 19.97 ± 2.67 μg/ml, mean ± SEM, n = 4). Extracts had similar potency to Trolox (IC50 12.78 ± 1.82 μg/ml), but were less potent than honeybee propolis (IC50 5.90 ± 0.62 μg/ml) or gallic acid (IC50 5.62 ± 0.35 μg/ml, P < 0.001). These findings warrant further investigation of the ecological and medicinal properties of this stingless bee cerumen,
which may herald a commercial potential for the Australian beekeeping industry. 相似文献
17.
Estella F. Vedrova Fedor I. Pleshikov Vladimir Ya. Kaplunov 《Mitigation and Adaptation Strategies for Global Change》2006,11(1):173-190
The study was carried out in the Turukhansk Research Station of Yenisei Transect (65°46′N, 89°25′E). Larch (Larix gmelinii (Rupr.) Rupr.) is the dominant overstory tree species. The research has been conducted on four permanent test plots in same-age mature
(110-year old) and overmature (380-year old) post-fire larch stands of green moss and lichen groups of forest type. Carbon
cycle parameters were assessed based on a biometric method. Quantitative analysis of carbon pools and fluxes shows that net
ecosystem production of north taiga larch stands averages 32% of net primary production. Sink of atmospheric CO2 makes 1.22 and 0.74 t C ha− 1 year− 1 for mature and overmature green moss larch stands, and 0.65 and 0.35 t C ha− 1 year− 1 for lichen type. Net carbon sink in the tree layer make up 9% of net primary production carbon, ground vegetation – 15%,
and dead plant residues accumulation – 8% of atmospheric carbon uptake via photosynthesis. 相似文献
18.
Lou Shujuan Mao Jietai Wang Meihua 《Frontiers of Environmental Science & Engineering in China》2007,1(3):345-349
The objective of this study was to determine the black carbon concentration in Beijing in 2003. The aerosol properties were
measured using an Aethalometer and a tapered element oscillating microbalance (TEOM) on the roof of the Physics Building of
Peking University (39.99° N, 116.31° E) from July to August 2003 and from November 2003 to January 2004. The average black
carbon (BC) concentrations in the summer and winter were 8.80 and 11.4 μg/m3, respectively. During winter, two different cyclone cut offs were installed at the inlet of an aethalometer. The BC mass
concentration in TSP, PM10, and PM2.5 were obtained. The results indicated that in winter aerosol, 90% of BC exited in PM10 and 82.6% of BC exited in PM2.5. The BC in PM10 accounted for 5.11% of the PM10 mass.
Translated from Acta Scientiae Circumstantiae, 2005, 25(1): 17–22 [译自: 环境科学学报] 相似文献
19.
Jianguo LIU Wei SONG Yongfeng NIE 《Frontiers of Environmental Science & Engineering in China》2008,2(1):8-14
Temperature is the determining factor of pyrolysis, which is one of the alternative technologies for oil sludge treatment.
The effects of final operating temperature ranging from 350 to 550°C on pyrolysis products of oil sludge were studied in an
externally-heating fixed bed reactor. With an increase of temperature, the mass fraction of solid residues, liquids, and gases
in the final product is 67.00%–56.00%, 25.60%–32.35%, and 7.40%–11.65%, and their corresponding heat values are 34.4–13.8
MJ/kg, 44.41–46.6 MJ/kg, and 23.94–48.23 MJ/Nm3, respectively. The mass and energy tend to shift from solid to liquid and gas phase (especially to liquid phase) during the
process, and the optimum temperature for oil sludge pyrolysis is 500°C. The liquid phase is mainly composed of alkane and
alkene (C5–C29), and the gas phase is dominantly HCS and H2. 相似文献
20.
Yuchi Lee Shanglien Lo Jeff Kuo Chinghong Hsieh 《Frontiers of Environmental Science & Engineering in China》2012,6(1):17-25
Microwave-hydrothermal treatment of persistent and bioaccumulative perfluorooctanoic acid (PFOA) in water with persulfate
(S2O82−) has been found effective. However, applications of this process to effectively remediate PFOA pollution require a better
understanding on free-radical scavenging reactions that also take place. The objectives of this study were to investigate
the effects of pH (pH = 2.5, 6.6, 8.8, and 10.5), chloride concentrations (0.01–0.15 mol·L−1), and temperature (60°C, 90°C, and 130°C) on persulfate oxidation of PFOA under microwave irradiation. Maximum PFOA degradation
occurred at pH 2.5, while little or no degradation at pH 10.5. Lowering system pH resulted in an increase in PFOA degradation
rate. Both high pH and chloride concentrations would result in more scavenging of sulfate free radicals and slow down PFOA
degradation. When chloride concentrations were less than 0.04 mol·L−1 at 90°C and 0.06 mol·L−1 at 60°C, presence of chloride ions had insignificant impacts on PFOA degradation. However, beyond these concentration levels,
PFOA degradation rates reduced significantly with an increase in chloride concentrations, especially under the higher temperature. 相似文献