How to restore the destroyed forest after forest fire is a key question that man must face. This paper reviewed the research situation and history on the forest restoration burned blanks and summed up the research met...How to restore the destroyed forest after forest fire is a key question that man must face. This paper reviewed the research situation and history on the forest restoration burned blanks and summed up the research methods used into four scales: seed-bank scale, community scale, ecosystem scale and landscape scale. The new technologies such as GIS & Remote Sensing used to vegetation restoration were also summarized. The strategies and developing trend of vegetation restoration research on burned blanks were discussed.展开更多
The structure and dynamic succession law of natural secondary forest after severe fire interference in recent 20 years were studied by adopting the method of deducing time series from the spatial sequence of vegetatio...The structure and dynamic succession law of natural secondary forest after severe fire interference in recent 20 years were studied by adopting the method of deducing time series from the spatial sequence of vegetation in Heihe region, Heilongjiang, China. Two typical and widely distributed forest types in the study area, namely forest type A and forest type B, were selected as study subjects. Forest type A is pure broadleaf forest or broadleaf mixed forest mainly composing of superior Betula platyphylla and Populus davidiana in the area with gradient 〈25°, while forest type B is pure forest or mixed forest composing of superior Quercus mongolica and Betula davurica in the area with gradient 〉25°. Species richness, vegetation coverage, important value, and similarity index of commtmity in different layers (Herb, shrub, small tree, and arbor layers) were investigated and analyzed for the two typical forests. The results show that after fire interference, the species richness and coverage in each layer in forest type A were higher than that in forest type B. Both for forest type A and B, with elapse of post-fire years, the species richness and coverage of herbs and shrubs showed a decline tendency, while those of arbor layer present a rising tendency. Through comparison of the important values of species in each layer and analysis of community structure changes, the dynamic process of post-fire vegetation succession for forest type A and B was separately determined. Post-fire 80 years' succession tendency of forest type A is B. platyphylla and Larix gmelinii mixed forest. Its shrub layer is mainly composed of Corylus heterophylla and Vaccinium uliginosum, and herb layer is dominated by Carex tristachya, Athyrium multidentatum, and Pyrola incarnate; whereas, the post-fire 80 years' succession of forest type B is Q. mongolica and B. davurica mixed forest. Its shrub layer is mainly composed of lespedeza bicolar and corylus heterophylla and herb layer is dominated by Carex tristachya, Asparagus densiflorus, and Hemerocallis minor.展开更多
Blue luminescence at about 431nm is obtained from epitaxial silicon after C+ implantation,annealing in hydrogen ambience and chemical etching sequentially.With increase of chemical etching,the blue peak is enhanced at...Blue luminescence at about 431nm is obtained from epitaxial silicon after C+ implantation,annealing in hydrogen ambience and chemical etching sequentially.With increase of chemical etching,the blue peak is enhanced at first,then decreased and substituted by a red peak at last.C=O compounds are introduced during C+ implantation and embedded in the surface of nanometer Si formed during annealing,and at last is formed nanometer silicon with embedded structure,which contributes to the blue emission.Presented is the possible mechanism of photoluminescence.展开更多
Based on stochastic optimization strategy, a formulation methodology is proposed for synthesizing distillation column sequences, allowing more than one middle component as the distributing components between a pair of...Based on stochastic optimization strategy, a formulation methodology is proposed for synthesizing distillation column sequences, allowing more than one middle component as the distributing components between a pair of key components in the non-sharp split. In order to represent and manipulate the distillation configuration structures, a new coding procedure is proposed in the form of one-dimensional array. Theoretically, an array can represent any kind of split(non-sharp and sharp). With the application of a binary sort tree approach, a robust flow sheet encoding and decoding procedure is developed so that the problem formulation and solution becomes tractable. In this paper,the synthesis problem is formulated as a mixed-integer nonlinear programming(MINLP) problem and an improved simulated annealing approach is adopted to solve the optimization problem. Besides, a shortcut method is applied to the evaluation of all required design parameters as well as the total function.展开更多
Changes in permanent sample plots in the lowland,submontane and montane forests on Mount Cameroon(4,095 m above sea level),an active volcano,are described for 15 years from 1989 to 2004.Throughout the study period,the...Changes in permanent sample plots in the lowland,submontane and montane forests on Mount Cameroon(4,095 m above sea level),an active volcano,are described for 15 years from 1989 to 2004.Throughout the study period,the stocking level of trees with a diameter at breast height(DBH) ≥ 10 cm in the three forests were lower than in pan-tropical stands suggesting a significant impact of volcanic and human-related activities on the vegetation communities on the mountain.Annual mortality rates in the submontane and montane forests were consistent with those reported for comparable altitudinal ranges in the Blue Mountains of Jamaica.The annual mortality rate was higher in the lowland forest than other lowland sites included.Divergence between recruitment and mortality rates was large suggesting that the three vegetation communities have not reached their climax.The seven-year difference in half-life of large trees(with a DBH ≥ 50 cm) in the submontane and montane forests suggests an altitudinal effect on turnover of larger trees that in turn contributes to the frequent small stature of high altitude forests.There was little evidence of an altitudinal effect on species turnover and growth rate.This finding supports generalizations about the zero effect of growth on the stature of high altitude trees.Understanding forest dynamics is crucially important in the management of tropical montane environmentsand in this instance particularly so given the recent creation of the Mount Cameroon National Park.展开更多
It is in the spirit of a "new family unit" that Dracula attempts vampire procreation in Bram Stoker's Dracula (2000) The themes of proper lineage and procreation juxtaposed with archaic late Victorian ideas invit...It is in the spirit of a "new family unit" that Dracula attempts vampire procreation in Bram Stoker's Dracula (2000) The themes of proper lineage and procreation juxtaposed with archaic late Victorian ideas invite exploration in this timeless novel. The novel is considered Gothic, yet it meets the cultural milieu of the fin de sikcle contemporary London of the 1890s. As the novel is considered fairly contemporary for its time, it is important to note that given new scientific theories such as eugenics, it is possible that Stoker was attempting to show a new kind of family unit---one that is not begot of the actual sex-act, but rather one that is propagated through the mingling of blood as a replacement for semen. There is much evidence in the novel to suggest that he not only wants to continue his family, but also that he is a true Renaissance "man" in his knowledge of other cultures, his pleasure and decadence in the finer material possessions, and his consumption of private property to continue his lineage in comfort and safety. It is clear in the novel that a brief analysis of the concepts of progeny and eugenics that the character of Dracula can be read as a "regular guy" simply trying to continue his lineage in an unforgiving and judgmental world. Dracula is violent in his preservation of his lineage, but he only does so to ensure he will not have to be a night-dweller on his own for eternity. He is a kind of demonic cupid with piercing fangs instead of angelic arrows He has to kill the human soul to obtain this obsessive dream of hearth and home展开更多
Most Mediterranean regions face a high risk to forest fires, estimation and anticipation of this risk modeled as a stochastic propagation process reproduces well some fire properties. This model needs information on t...Most Mediterranean regions face a high risk to forest fires, estimation and anticipation of this risk modeled as a stochastic propagation process reproduces well some fire properties. This model needs information on the behavior of the bio-physical properties of vegetation associated to combustion. An experimental study to analyze the structure of a leaf of Laurel shrub at different biological stages is presented; it allows following the structural exchanges induced on the leaf by the effect of increasing temperature. For this purpose, both dielectric and TGA (Thermogravimetric Analysis)/DTA (Differentialthermal Analysis) was performed to a better understanding of the pyrolysis phenomenon. The results obtained provide information on the process of thermal degradation caused by fire. The evolution of the leaf impedance as a function of the applied frequency characterizes the moisture loss in plant species during pyrolysis. The dielectric response confirms the proposition to the equivalent circuit of the leaf as a composite of liquid and solid parts. The TGA/DTA results detected the behaviour of the solid parts in the fire under a constant heating rate, and were able to show all the transformation subjected by the Laurel leaf until ignition and all the gases released during it.展开更多
Through the Algerian orchid flora, several rare species remain endemic in the Maghreb. This note on the orchids will enrich the already existing data on the area of Tlemcen. Currently, the coexistence of orchids and s...Through the Algerian orchid flora, several rare species remain endemic in the Maghreb. This note on the orchids will enrich the already existing data on the area of Tlemcen. Currently, the coexistence of orchids and species (such as Quercus faginea subsp. tlemcenensis (DC.) M., Lonicera implexa L. and Ruscus aculeatus L.) indicates an ecological environment of dominant forest. Nevertheless, the significant frequency of fires and human pressure is leading to erosion of this area orchids richness. This work enabled us to establish a complete inventory of the orchids species that exist, with an estimate of the populations and a taxon illustration for each of them. Fourteen species (14) were indexed, during the period of spring 2011 only, in this reserve and the scoured areas which do not exceed 2000 ha, representing 29% of the total Algerian orchids species. Among the rare taxa signed ourselves: Ophrys subfusca subsp. battandieri (Rchb.) Batt. and Dactylorhiza durandii (Boiss. and Reuter) M. Lainz in Oranie (O)*展开更多
[Objective] The aim of this study was to observe variations of DON content in grain of two wheat cultivars during tempering at different temperatures, and explore the possible causes of the variations. [Method] Two na...[Objective] The aim of this study was to observe variations of DON content in grain of two wheat cultivars during tempering at different temperatures, and explore the possible causes of the variations. [Method] Two naturally Fusarium-infested wheat samples Youmai 3 and Yangmai 14 were selected as experimental materials. Tempering was carried out at different temperature (15, 25 and 35 ℃) for 48 h. During tempering, wheat grain samples were collected every 8 h. DON contents in tempered grain were measured by HPLC coupled with UV detector. [Result] For Youmai 3, DON contents were in the ranges of 3.94-12.49, 4.26-6.11 and 3.41- 7.91 μg/g during tempering at 15, 25 and 35 ℃, respectively. The highest DON contents were observed at the 32^nd hour at 15 ℃, the 8^th hour at 25 ℃ and the 32^rd hour at 35 ℃, respectively. After tempering for 48 h, DON contents in grain were increased by 175.1%, 27.5% and 7.2%, respectively. For Yangmai 14, DON contents were in the ranges of 0.55-1.56, 0.39-0.77 and 0.57-3.17 μg/g during tempering at 15, 25 and 35 ℃, respectively. The highest DON contents were ob- served at the 24^th hour at 15 ℃, the 40^th hour at 25 ℃ and the 48^th hour at 35 ℃, respectively. After tempering for 48 h, DON contents in grain were increased by 94.5% at 15 ℃ and 456.1% at 35 ℃, respectively, whereas it was decreased by 35.0% at 25 ℃. From the point of view of reducing DON level, 15 ℃ was not rea- sonable for the tempering of both wheat cultivars, and tempering at 35 ℃ for 16 h and tempering at 25 ℃ for 24 h appeared to be desirable for Youmai 3 and Yang- mai 14, respectively. [Conclusion] The results suggested controlling the tempering temperature and time would be helpful to reduce DON level in grain.展开更多
The hypothesis that bacteria and protozoa microorganisms are able to travel from one planet to another and become of exolife was not taken seriously by the scientific community for a long time. However at the end of t...The hypothesis that bacteria and protozoa microorganisms are able to travel from one planet to another and become of exolife was not taken seriously by the scientific community for a long time. However at the end of the 20th century the situation changed dramatically. Firstly, in 1990, meteorites consisting of Martian rocks were found. Secondly, it became clear that many microorganisms especially bacteria spores have an uncanny ability to endure the rugged environment of the outer space for a long time and then re-activate in a more favorable environment. If we compare these findings, the idea of interplanetary transmigration of the simplest forms of life on meteoroids ceases to look so illusory. The final dot in this issue was made by the works of academician Rozanov, and later Hoover (Professor Richard B. Hoover) through the discovery of fossilized microbes inside of a meteorite massif, that is to say, seeds of life. However, to tie only the simplest forms of life to meteorites or comets is to introduce strong constraints on the likelihood of delivery of seeds (spores of life) to Earth for many obvious reasons. Besides, exobiology does not negate the problem of origin of life, and transfers it into the era of the young universe. Therefore, it is necessary to consider in detail the essence of seeds of life or cosmic particles of dust and gas-dust streams as their carriers, their penetration path to Earth and forms of their existence.展开更多
All of the plants can be combusted. The mechanism of forest belts resistance is that the tree specieswerent liable to be burned compared with other plant species. In this paper new concepts on fire resistanttrees and ...All of the plants can be combusted. The mechanism of forest belts resistance is that the tree specieswerent liable to be burned compared with other plant species. In this paper new concepts on fire resistanttrees and fuel-breaks trees were presented. The fire resistance mechanism includes 3 aspects, fire-resistanttree species, rational construction forest belts and environment. Tree crowns can resist fire forwarding.Forest belts can form the environment, which is not easy to fire, and also make fuels distributed discontinuous.The network of forest belts has large area of conifer forest segregated. The ideal fire resistant tree species hadbetter to embrace some characteristics, such as high fire resistance, rational planting and biological characteristics.展开更多
Aims To explain how plant community copes with a recurring anthropogenic forest fire in Himalayan Chir pine forest,it is important to understand their postfire regeneration strategies.The primary aim of the study was ...Aims To explain how plant community copes with a recurring anthropogenic forest fire in Himalayan Chir pine forest,it is important to understand their postfire regeneration strategies.The primary aim of the study was to know:(i)how fire impact soil seed bank composition and(ii)how much soil seed bank composition differs with standing vegetation after the forest fire.Methods Soil samples were collected from burned and adjoining unburned sites in blocks using three layers down to 9 cm depth immediately after a forest fire and incubated in the net-house for seedling emergence.Same sites were revisited during late monsoon/early autumn season to know the species composition of standing vegetation recovered after a forest fire.Important Findings Soil contained viable seeds of>70 species.The average seed bank density was 8417 and 14217 seeds/m^(2) in the burned and unburned site,respectively.In both sites,it decreased with increasing soil depth.Overall fire had no significant impact on seed density;however,taking individual layers into consideration,fire had a significant impact on seed density only in the uppermost soil layer.The species richness of soil seed bank and standing vegetation was 73 and 100,respectively(with 35 shared species),resulting in a similarity of about 40%.In contrast,>80%species in soil seed bank was found similar between burned and unburned sites.Further,there were no significant differences in species richness of standing vegetation in burned(87 spp.)and unburned(78 spp.)sites.Our results showed that fire had an insignificant impact on soil seed bank composition and restoration potential of a plant species from seeds.The understory herb and shrub plant community’s ability to form a fire-resistant viable soil seed bank and capable to recover in the postfire rainy season,explains how they reduce the risk of recurring fire damage in maintaining their population.展开更多
Forty-eight vinegar samples including white vinegar, rice vinegar and mature vinegar were collected from several markets in Beijing. Butyltin compounds were determined by headspace solid-phase microextraction coupled ...Forty-eight vinegar samples including white vinegar, rice vinegar and mature vinegar were collected from several markets in Beijing. Butyltin compounds were determined by headspace solid-phase microextraction coupled with gas chromatography and flame photometric detector after in situ ethylation with sodium tetraethylborate. Butyltin species were detected in sixteen vinegar samples and ranged from 0.012 to 14.10 lag Sn L 1. The detection rate of white vinegar is higher than that of rice vinegar and mature vinegar. Vinegar samples with relatively high butyltin concentration (〉1.5 μg Sn L-1) were those stored in plastic bags, indicating that the plastic bag was one of the possible sources of butyltin contamination. This was further confirmed by the leaching experiments of three selected plastic bags, and monobutyltin was detected in the leaching solvents. According to the estimation, the average daily intake of total butyltin compounds through vinegar consumption is about 0.04 ng Sn/kg b.w., much lower than the Tolerable Daily Intake (TDI) of 100 ng Sn/kg b.w. set by the European Food Safety Authority (EFSA).展开更多
The effects of heat loss on the structure of laminar flamelets,which are the constitutive elements of turbulent flames under the most common operating conditions,are investigated for typical aeronautical gas-turbine o...The effects of heat loss on the structure of laminar flamelets,which are the constitutive elements of turbulent flames under the most common operating conditions,are investigated for typical aeronautical gas-turbine operating conditions at take-off.The magnitude of heat loss is quantified via the "enthalpy defect" measured with respect to an adiabatic flame.A procedure to generate laminar flamelets with an assigned enthalpy defect at the boundaries is devised and applied to nonpremixed propane/air flames,as propane reproduces the essential features of higher hydrocarbon combustion.It is found,contrary to commonly held beliefs,that the enthalpy defect has a significant effect on the concentration not only of minor species,but also of main reaction products.Such effects are found in general to be more pronounced for fuel-rich conditions.An impact is anticipated on the formation rate of nitric oxides.The effects of scalar dissipation rate are also discussed.展开更多
文摘How to restore the destroyed forest after forest fire is a key question that man must face. This paper reviewed the research situation and history on the forest restoration burned blanks and summed up the research methods used into four scales: seed-bank scale, community scale, ecosystem scale and landscape scale. The new technologies such as GIS & Remote Sensing used to vegetation restoration were also summarized. The strategies and developing trend of vegetation restoration research on burned blanks were discussed.
文摘The structure and dynamic succession law of natural secondary forest after severe fire interference in recent 20 years were studied by adopting the method of deducing time series from the spatial sequence of vegetation in Heihe region, Heilongjiang, China. Two typical and widely distributed forest types in the study area, namely forest type A and forest type B, were selected as study subjects. Forest type A is pure broadleaf forest or broadleaf mixed forest mainly composing of superior Betula platyphylla and Populus davidiana in the area with gradient 〈25°, while forest type B is pure forest or mixed forest composing of superior Quercus mongolica and Betula davurica in the area with gradient 〉25°. Species richness, vegetation coverage, important value, and similarity index of commtmity in different layers (Herb, shrub, small tree, and arbor layers) were investigated and analyzed for the two typical forests. The results show that after fire interference, the species richness and coverage in each layer in forest type A were higher than that in forest type B. Both for forest type A and B, with elapse of post-fire years, the species richness and coverage of herbs and shrubs showed a decline tendency, while those of arbor layer present a rising tendency. Through comparison of the important values of species in each layer and analysis of community structure changes, the dynamic process of post-fire vegetation succession for forest type A and B was separately determined. Post-fire 80 years' succession tendency of forest type A is B. platyphylla and Larix gmelinii mixed forest. Its shrub layer is mainly composed of Corylus heterophylla and Vaccinium uliginosum, and herb layer is dominated by Carex tristachya, Athyrium multidentatum, and Pyrola incarnate; whereas, the post-fire 80 years' succession of forest type B is Q. mongolica and B. davurica mixed forest. Its shrub layer is mainly composed of lespedeza bicolar and corylus heterophylla and herb layer is dominated by Carex tristachya, Asparagus densiflorus, and Hemerocallis minor.
文摘Blue luminescence at about 431nm is obtained from epitaxial silicon after C+ implantation,annealing in hydrogen ambience and chemical etching sequentially.With increase of chemical etching,the blue peak is enhanced at first,then decreased and substituted by a red peak at last.C=O compounds are introduced during C+ implantation and embedded in the surface of nanometer Si formed during annealing,and at last is formed nanometer silicon with embedded structure,which contributes to the blue emission.Presented is the possible mechanism of photoluminescence.
基金Supported by the 973 Program of China(2012CB720503)the Open Research Project of State Kay Laboratory of Chemical Engineering(SKL-Ch E-13B02)
文摘Based on stochastic optimization strategy, a formulation methodology is proposed for synthesizing distillation column sequences, allowing more than one middle component as the distributing components between a pair of key components in the non-sharp split. In order to represent and manipulate the distillation configuration structures, a new coding procedure is proposed in the form of one-dimensional array. Theoretically, an array can represent any kind of split(non-sharp and sharp). With the application of a binary sort tree approach, a robust flow sheet encoding and decoding procedure is developed so that the problem formulation and solution becomes tractable. In this paper,the synthesis problem is formulated as a mixed-integer nonlinear programming(MINLP) problem and an improved simulated annealing approach is adopted to solve the optimization problem. Besides, a shortcut method is applied to the evaluation of all required design parameters as well as the total function.
文摘Changes in permanent sample plots in the lowland,submontane and montane forests on Mount Cameroon(4,095 m above sea level),an active volcano,are described for 15 years from 1989 to 2004.Throughout the study period,the stocking level of trees with a diameter at breast height(DBH) ≥ 10 cm in the three forests were lower than in pan-tropical stands suggesting a significant impact of volcanic and human-related activities on the vegetation communities on the mountain.Annual mortality rates in the submontane and montane forests were consistent with those reported for comparable altitudinal ranges in the Blue Mountains of Jamaica.The annual mortality rate was higher in the lowland forest than other lowland sites included.Divergence between recruitment and mortality rates was large suggesting that the three vegetation communities have not reached their climax.The seven-year difference in half-life of large trees(with a DBH ≥ 50 cm) in the submontane and montane forests suggests an altitudinal effect on turnover of larger trees that in turn contributes to the frequent small stature of high altitude forests.There was little evidence of an altitudinal effect on species turnover and growth rate.This finding supports generalizations about the zero effect of growth on the stature of high altitude trees.Understanding forest dynamics is crucially important in the management of tropical montane environmentsand in this instance particularly so given the recent creation of the Mount Cameroon National Park.
文摘It is in the spirit of a "new family unit" that Dracula attempts vampire procreation in Bram Stoker's Dracula (2000) The themes of proper lineage and procreation juxtaposed with archaic late Victorian ideas invite exploration in this timeless novel. The novel is considered Gothic, yet it meets the cultural milieu of the fin de sikcle contemporary London of the 1890s. As the novel is considered fairly contemporary for its time, it is important to note that given new scientific theories such as eugenics, it is possible that Stoker was attempting to show a new kind of family unit---one that is not begot of the actual sex-act, but rather one that is propagated through the mingling of blood as a replacement for semen. There is much evidence in the novel to suggest that he not only wants to continue his family, but also that he is a true Renaissance "man" in his knowledge of other cultures, his pleasure and decadence in the finer material possessions, and his consumption of private property to continue his lineage in comfort and safety. It is clear in the novel that a brief analysis of the concepts of progeny and eugenics that the character of Dracula can be read as a "regular guy" simply trying to continue his lineage in an unforgiving and judgmental world. Dracula is violent in his preservation of his lineage, but he only does so to ensure he will not have to be a night-dweller on his own for eternity. He is a kind of demonic cupid with piercing fangs instead of angelic arrows He has to kill the human soul to obtain this obsessive dream of hearth and home
文摘Most Mediterranean regions face a high risk to forest fires, estimation and anticipation of this risk modeled as a stochastic propagation process reproduces well some fire properties. This model needs information on the behavior of the bio-physical properties of vegetation associated to combustion. An experimental study to analyze the structure of a leaf of Laurel shrub at different biological stages is presented; it allows following the structural exchanges induced on the leaf by the effect of increasing temperature. For this purpose, both dielectric and TGA (Thermogravimetric Analysis)/DTA (Differentialthermal Analysis) was performed to a better understanding of the pyrolysis phenomenon. The results obtained provide information on the process of thermal degradation caused by fire. The evolution of the leaf impedance as a function of the applied frequency characterizes the moisture loss in plant species during pyrolysis. The dielectric response confirms the proposition to the equivalent circuit of the leaf as a composite of liquid and solid parts. The TGA/DTA results detected the behaviour of the solid parts in the fire under a constant heating rate, and were able to show all the transformation subjected by the Laurel leaf until ignition and all the gases released during it.
文摘Through the Algerian orchid flora, several rare species remain endemic in the Maghreb. This note on the orchids will enrich the already existing data on the area of Tlemcen. Currently, the coexistence of orchids and species (such as Quercus faginea subsp. tlemcenensis (DC.) M., Lonicera implexa L. and Ruscus aculeatus L.) indicates an ecological environment of dominant forest. Nevertheless, the significant frequency of fires and human pressure is leading to erosion of this area orchids richness. This work enabled us to establish a complete inventory of the orchids species that exist, with an estimate of the populations and a taxon illustration for each of them. Fourteen species (14) were indexed, during the period of spring 2011 only, in this reserve and the scoured areas which do not exceed 2000 ha, representing 29% of the total Algerian orchids species. Among the rare taxa signed ourselves: Ophrys subfusca subsp. battandieri (Rchb.) Batt. and Dactylorhiza durandii (Boiss. and Reuter) M. Lainz in Oranie (O)*
基金Supported by Joint Innovation Fund of Industry-University-Research Institute of Jiangsu Province,China(BY2012208)
文摘[Objective] The aim of this study was to observe variations of DON content in grain of two wheat cultivars during tempering at different temperatures, and explore the possible causes of the variations. [Method] Two naturally Fusarium-infested wheat samples Youmai 3 and Yangmai 14 were selected as experimental materials. Tempering was carried out at different temperature (15, 25 and 35 ℃) for 48 h. During tempering, wheat grain samples were collected every 8 h. DON contents in tempered grain were measured by HPLC coupled with UV detector. [Result] For Youmai 3, DON contents were in the ranges of 3.94-12.49, 4.26-6.11 and 3.41- 7.91 μg/g during tempering at 15, 25 and 35 ℃, respectively. The highest DON contents were observed at the 32^nd hour at 15 ℃, the 8^th hour at 25 ℃ and the 32^rd hour at 35 ℃, respectively. After tempering for 48 h, DON contents in grain were increased by 175.1%, 27.5% and 7.2%, respectively. For Yangmai 14, DON contents were in the ranges of 0.55-1.56, 0.39-0.77 and 0.57-3.17 μg/g during tempering at 15, 25 and 35 ℃, respectively. The highest DON contents were ob- served at the 24^th hour at 15 ℃, the 40^th hour at 25 ℃ and the 48^th hour at 35 ℃, respectively. After tempering for 48 h, DON contents in grain were increased by 94.5% at 15 ℃ and 456.1% at 35 ℃, respectively, whereas it was decreased by 35.0% at 25 ℃. From the point of view of reducing DON level, 15 ℃ was not rea- sonable for the tempering of both wheat cultivars, and tempering at 35 ℃ for 16 h and tempering at 25 ℃ for 24 h appeared to be desirable for Youmai 3 and Yang- mai 14, respectively. [Conclusion] The results suggested controlling the tempering temperature and time would be helpful to reduce DON level in grain.
文摘The hypothesis that bacteria and protozoa microorganisms are able to travel from one planet to another and become of exolife was not taken seriously by the scientific community for a long time. However at the end of the 20th century the situation changed dramatically. Firstly, in 1990, meteorites consisting of Martian rocks were found. Secondly, it became clear that many microorganisms especially bacteria spores have an uncanny ability to endure the rugged environment of the outer space for a long time and then re-activate in a more favorable environment. If we compare these findings, the idea of interplanetary transmigration of the simplest forms of life on meteoroids ceases to look so illusory. The final dot in this issue was made by the works of academician Rozanov, and later Hoover (Professor Richard B. Hoover) through the discovery of fossilized microbes inside of a meteorite massif, that is to say, seeds of life. However, to tie only the simplest forms of life to meteorites or comets is to introduce strong constraints on the likelihood of delivery of seeds (spores of life) to Earth for many obvious reasons. Besides, exobiology does not negate the problem of origin of life, and transfers it into the era of the young universe. Therefore, it is necessary to consider in detail the essence of seeds of life or cosmic particles of dust and gas-dust streams as their carriers, their penetration path to Earth and forms of their existence.
基金The research was supported by Research and Demonstration of Key techniques for natural forests protection program(2004) and Key Technologies R&D Programme (No. 2001BA510B09 )
文摘All of the plants can be combusted. The mechanism of forest belts resistance is that the tree specieswerent liable to be burned compared with other plant species. In this paper new concepts on fire resistanttrees and fuel-breaks trees were presented. The fire resistance mechanism includes 3 aspects, fire-resistanttree species, rational construction forest belts and environment. Tree crowns can resist fire forwarding.Forest belts can form the environment, which is not easy to fire, and also make fuels distributed discontinuous.The network of forest belts has large area of conifer forest segregated. The ideal fire resistant tree species hadbetter to embrace some characteristics, such as high fire resistance, rational planting and biological characteristics.
基金supported by University Grants Commission(UGC)New Delhi under a Major Research Project[grant number:39-925/2010(SR)]to SSP.
文摘Aims To explain how plant community copes with a recurring anthropogenic forest fire in Himalayan Chir pine forest,it is important to understand their postfire regeneration strategies.The primary aim of the study was to know:(i)how fire impact soil seed bank composition and(ii)how much soil seed bank composition differs with standing vegetation after the forest fire.Methods Soil samples were collected from burned and adjoining unburned sites in blocks using three layers down to 9 cm depth immediately after a forest fire and incubated in the net-house for seedling emergence.Same sites were revisited during late monsoon/early autumn season to know the species composition of standing vegetation recovered after a forest fire.Important Findings Soil contained viable seeds of>70 species.The average seed bank density was 8417 and 14217 seeds/m^(2) in the burned and unburned site,respectively.In both sites,it decreased with increasing soil depth.Overall fire had no significant impact on seed density;however,taking individual layers into consideration,fire had a significant impact on seed density only in the uppermost soil layer.The species richness of soil seed bank and standing vegetation was 73 and 100,respectively(with 35 shared species),resulting in a similarity of about 40%.In contrast,>80%species in soil seed bank was found similar between burned and unburned sites.Further,there were no significant differences in species richness of standing vegetation in burned(87 spp.)and unburned(78 spp.)sites.Our results showed that fire had an insignificant impact on soil seed bank composition and restoration potential of a plant species from seeds.The understory herb and shrub plant community’s ability to form a fire-resistant viable soil seed bank and capable to recover in the postfire rainy season,explains how they reduce the risk of recurring fire damage in maintaining their population.
基金support under the National Basic Research Program of China (2009CB421605)National Key Water Program(2009ZX07207-002-03)National Natural Science Foundation of China (20977096)
文摘Forty-eight vinegar samples including white vinegar, rice vinegar and mature vinegar were collected from several markets in Beijing. Butyltin compounds were determined by headspace solid-phase microextraction coupled with gas chromatography and flame photometric detector after in situ ethylation with sodium tetraethylborate. Butyltin species were detected in sixteen vinegar samples and ranged from 0.012 to 14.10 lag Sn L 1. The detection rate of white vinegar is higher than that of rice vinegar and mature vinegar. Vinegar samples with relatively high butyltin concentration (〉1.5 μg Sn L-1) were those stored in plastic bags, indicating that the plastic bag was one of the possible sources of butyltin contamination. This was further confirmed by the leaching experiments of three selected plastic bags, and monobutyltin was detected in the leaching solvents. According to the estimation, the average daily intake of total butyltin compounds through vinegar consumption is about 0.04 ng Sn/kg b.w., much lower than the Tolerable Daily Intake (TDI) of 100 ng Sn/kg b.w. set by the European Food Safety Authority (EFSA).
文摘The effects of heat loss on the structure of laminar flamelets,which are the constitutive elements of turbulent flames under the most common operating conditions,are investigated for typical aeronautical gas-turbine operating conditions at take-off.The magnitude of heat loss is quantified via the "enthalpy defect" measured with respect to an adiabatic flame.A procedure to generate laminar flamelets with an assigned enthalpy defect at the boundaries is devised and applied to nonpremixed propane/air flames,as propane reproduces the essential features of higher hydrocarbon combustion.It is found,contrary to commonly held beliefs,that the enthalpy defect has a significant effect on the concentration not only of minor species,but also of main reaction products.Such effects are found in general to be more pronounced for fuel-rich conditions.An impact is anticipated on the formation rate of nitric oxides.The effects of scalar dissipation rate are also discussed.