In The Old Man and the Sea, Hemingway depicts a simple but fascinating story of a fisherman who catches and loses a big fish after struggling for eight four days at sea. By means of text analysis, this paper aims to a...In The Old Man and the Sea, Hemingway depicts a simple but fascinating story of a fisherman who catches and loses a big fish after struggling for eight four days at sea. By means of text analysis, this paper aims to analyze the fiction in terms of its title, its main character, Santiago and its writing style—"the Iceberg Theory", thus draws the conclusion that beneath the story's simplicity lies in its greatness and sublimity.展开更多
Looking at the last decades of the 19th and 20th century from our vantage point encourages parallels to be drawn between the two periods: in fact, both are affected by a process of cultural fragmentation, social, and...Looking at the last decades of the 19th and 20th century from our vantage point encourages parallels to be drawn between the two periods: in fact, both are affected by a process of cultural fragmentation, social, and epistemological transformations and crises that permeate the whole civil society. In the specific field of English literature, the genre of the fantastic is undoubtedly a common presence. In Fantasy: The Literature of Subversion, Jackson (1981) noted the re-emergence of the fantastic as a transgressive force at moments of cultural stress and repression. Waugh (1995) held a similar view in The Harvest of the Sixties. At the end of the 20th century, in its postmodernist shape, fantastic literature becomes one of the favourite genres of a number of feminist writers, and among them, Jeanette Winterson transforms it into a truly transgressive genre. This paper examines Winterson's The Passion (1996) and Sexing the Cherry (1990) in the light of Jackson's theory of the fantastic, as a narrative that establishes an oppositional dialogic relationship with the "real", to interrogate it and collapse the traditional distinction between the normative and the "other". In The Passion, the real is signified by the dominant ideological discourse, exemplified by Napoleon; the fantastic by Villanelle's webbed feet and her ability to walk on water. In Sexing the Cherry, the real is represented by the Puritans with their bigoted and hypocritical morality; the fantastic by the huge Dog-Woman and her foundling son, Jordan. Besides, in both novels, the female body is metamorphosed to challenge the view of a "normal", acceptable femininity; what emerges is a monstrous and sublime body that collapses distinctions between gender boundaries. In Sexing the Cherry (1990), Winterson created the grotesque, gigantic body of the Dog-Woman, a figure of Kristevan "abjection". In The Passion (1996), she gave life to the hybrid body of Villanelle, an oxymoronic combination of the terrible beautiful. The conclusion of the paper argues that Winterson deploys the fantastic to deconstruct the gendered subject of the dominant signifying order and create a dislocated world outside commercial culture, where new voices can be heard, speaking for unheard, neglected groups, particularly women.展开更多
Longinus's On the Sublime holds a uniquely unparalleled position in Western critical theories. By analyzing Li Bai's well-known poem Cataract on Mount Lu from the perspective of sublimity, attempt is made to a...Longinus's On the Sublime holds a uniquely unparalleled position in Western critical theories. By analyzing Li Bai's well-known poem Cataract on Mount Lu from the perspective of sublimity, attempt is made to appreciate the ancient Chinese poems by using Western critical theory and thus derive another kind of aesthetic beauty.展开更多
In this work, comprehensive studies of 2,4-dinitroanisole(2,4DNAN) were carried out using powder thermorentgenography of the internal standard. The time of the complete polymorphic transition in the solid phase β→a ...In this work, comprehensive studies of 2,4-dinitroanisole(2,4DNAN) were carried out using powder thermorentgenography of the internal standard. The time of the complete polymorphic transition in the solid phase β→a in 2,4DNAN under various combinations of conditions has been determined. It has been established that, regardless of the season of manufacture of the substance, when it is stored for 8-9months, with a change in ambient temperature from minus 30℃ to plus 30℃, a complete polymorphic transition β→a occurs. When stored in conditions below minus 5℃, polymorphic transition does not occur. When stored in conditions above plus 30℃ in a closed container, polymorphic transition occurs within 3 weeks. The polymorphic transition is accompanied by a decrease in density by 1.3%-1.5% and an increase in melting temperature by 10-12℃, depending on the degree of purity of the starting substance. The activation energy of the molecular rearrangement was 68-70 k J/mol(16.5 ± 3 kcal/mol). The mechanism of polymorphic transition has been evaluated, which is presumably based on internal homodiffusion and energy transfer to the surface of the mass of powder particles and the product. The average activation energy of the polymorphic transition process was 110 ± 6.2 k J/mol(26.2 kcal/mol). In an open container, reactions proceed by a homogeneous mechanism, and in a closed container by a heterogeneous mechanism involving the gas phase.展开更多
Close-space sublimation(CSS)has been demonstrated as an alternative vacuum deposition technique for fabricating organic light-emitting diodes(OLEDs).CSS utilizes a planar donor plate pre-coated with organic thin films...Close-space sublimation(CSS)has been demonstrated as an alternative vacuum deposition technique for fabricating organic light-emitting diodes(OLEDs).CSS utilizes a planar donor plate pre-coated with organic thin films as an area source to rapidly transfer the donor film to a device substrate at temperatures below 200℃.CSS is also conformal and capable of depositing on odd-shaped substrates using flexible donor media.The evaporation behaviors of organic donor films under CSS were fully characterized using model OLED materials and CSS-deposited films exhibited comparable device performances in an OLED stack to films deposited by conventional point sources.The low temperature and conformal nature of CSS,along with its high material utilization and short process time,make it a promising method for fabricating flexible OLED displays.展开更多
[Objective] This study aimed to compare the effects of sublimed sulfur and acaricide on controlling bee mites.[Method] Three independent experiments were carried out in the same apiary during 2007-2009.[Results] The r...[Objective] This study aimed to compare the effects of sublimed sulfur and acaricide on controlling bee mites.[Method] Three independent experiments were carried out in the same apiary during 2007-2009.[Results] The results showed that this method is effective in eliminating mites settled on combs or hidden during pupae phase,but not in controlling the mites parasitized on adult bees.The control effect on killing Varroa destructor after treated appeared optimal in the first day and then decreased,and that on killing Tvopilaelaps clareae happened in the second day.The results indicated that the effect would be much better if the bees can be treated 1 time to 2 times again in the following 2-5 days after the first treatment.Back to data pool,we found that the treatment of sublimed sulfur paired with acaricide is effective in controlling V.destructor and T.clareae.[Conclusion] This technique could facilitate the apicultural production in the regions suffered from V.destructor and T.clareae.展开更多
Through defining the differences between literary and non-literary translation and quoting some relating theories of aestheticalness,this paper sets the translation of Mr. Zhu Ziqing's famous prose《荷塘月色》as ...Through defining the differences between literary and non-literary translation and quoting some relating theories of aestheticalness,this paper sets the translation of Mr. Zhu Ziqing's famous prose《荷塘月色》as an example to analyze how to transform the artistic conception into translation without any deviation to realize the true reciprocity in literary translation. It mainly explain the theory from three aspects:Phonological beauty,Symmetrical beauty and Conceptional beauty. It may have certain guiding meanings for the practices of literary translation.展开更多
Yeats' lyrics of sublimation is one of his major concerns in his later years. Sublimation for Yeats is essentially the transmutation and elevation of bitterness and tragic facts of being into happiness, into tranq...Yeats' lyrics of sublimation is one of his major concerns in his later years. Sublimation for Yeats is essentially the transmutation and elevation of bitterness and tragic facts of being into happiness, into tranquility of mind, then into the emotionless emotion, as Yeats names it as "innocence". The process of sublimation enriches the creativity of Yeats as artist when he is confronted with severity of aging spiritually and physically.展开更多
This paper establishes the mathematical model in calculating the effective thermal conductivity and the effective mass diffusivity of dried layer of beef undergoing freeze drying process.First,experimental measurement...This paper establishes the mathematical model in calculating the effective thermal conductivity and the effective mass diffusivity of dried layer of beef undergoing freeze drying process.First,experimental measurements are done on the dehydrated quantity as well as temperature variations at different locations of the beef steak.Then the effective thermal conductivity and the effective mass diffusivity are calculated by applying the above mathematical model on the data of the dehydrated quantity.These two coefficients are further used in the calculation of temperature distribution.The result is in agreement with the measurement,thus confirming the correctness of the model and the values of the coefficients.展开更多
Freeze drying or lyophilization of aqueous solutions is widely used in pharmaceutical industry. The in-creased importance Of the process is gaining a worldwide interest of research. A growing body of literature has de...Freeze drying or lyophilization of aqueous solutions is widely used in pharmaceutical industry. The in-creased importance Of the process is gaining a worldwide interest of research. A growing body of literature has demonstrated that the scientific approach can result in improved product quality with minimum trial and error em-piricism. Formulation and process development need a systematical understanding of the physical chemistry of freezing and freeze drying, material science and mechanisms of heat and mass transfer. This paper presents an overview on freeze ding of aqueous solutions based on publications in the past few decades. The important issuesof the process are analyzed.展开更多
High-resolution X-ray diffractometry(HRXRD)was used to assess the quality of 6H-SiC crystals grown by sublimation method.The results show the occurrence of low-angle grain boundaries(LB)is close relative to the inclin...High-resolution X-ray diffractometry(HRXRD)was used to assess the quality of 6H-SiC crystals grown by sublimation method.The results show the occurrence of low-angle grain boundaries(LB)is close relative to the inclination of the crystal interface.At the central faceted region with 0°inclination the crystal is of high structural perfection.However,at the region close to the facet with less than 5°inclination LB occurs slightly and at the region close to the peripheral polytype ring with more than 5°inclination LB defect occurs heavily.The density of LB can be drastically reduced by decreasing radial temperature gradient that determines the shape of the crystal growth interface.展开更多
In order to remediate heavy metal ions from waste water,Al2O3–SiO2 composite aerogels are prepared via a sol–gel and an organic solvent sublimation drying method.Various characterisation techniques have been employe...In order to remediate heavy metal ions from waste water,Al2O3–SiO2 composite aerogels are prepared via a sol–gel and an organic solvent sublimation drying method.Various characterisation techniques have been employed including X-ray diffraction(XRD),Fourier transform infrared spectrometry(FTIR),scanning electron microscope(SEM),Energy-dispersion X-ray spectroscopy(EDX),Brunauer–Emmett–Teller(BET)N2 adsoprtion isotherm,and atomic absorption spectrometer(AAS).XRD and FTIR suggest that the aerogels are composed of mainly Al2O3 and minor SiO2.They have a high specific surface area(827.544 m^2/g)and high porosity(86.0%)with a pore diameter of~20 nm.Their microstructures show that the distribution of Al,Si,and O is homogeneous.The aerogels can remove~99%Cu^2+within~40 min and then reach the equilibrium uptake(~69 mg/g).Preliminary calculations show that the Cu2+uptake by the aerogels follows pseudo second-order kinetics where chemical sorption may take effect owing largely to the high surface area,high porosity,and abundant functional groups,such as Al–OH and Si–OH,in the aerogel network.The prepared aerogels may serve as efficient absorbents for Cu^2+removal.展开更多
This paper reports the ignition performance of the iodine-fueled radio frequency(RF)ion thruster(IRIT)at different anode temperaturesT_(a0).The experimental results show that the anode temperature plays important role...This paper reports the ignition performance of the iodine-fueled radio frequency(RF)ion thruster(IRIT)at different anode temperaturesT_(a0).The experimental results show that the anode temperature plays important role on the ignition process of the IRIT.There were two characteristic temperatures related to the anode:the minimum ignition temperatureT_(i0)and the stable ignition temperatureT_(is),which were much lower than the pipeline temperature and the storage tank temperature.AtT_(a0)<T_(i0),it failed to discharge.WhenT_(i0)≤T_(a0)<T_(is),it was ignited with dramatical oscillations.AtT_(a0)≥T_(is),the discharge was stable in a large anode temperature range.The analysis showed that the different discharge phenomena at different anode temperatures were attributed to the change of iodine flow rate during the process of the iodine deposition-clogging and sublimation-clearing inside the thruster.The research helps improve the preheating design of the iodine-fueled electric thruster.展开更多
The structure and characteristics of CdTe thin filrns are closely dependent on the whole deposition process in close-space sublimation (CSS). The physical mechanism of CSS was analyzed aud the temperature distributi...The structure and characteristics of CdTe thin filrns are closely dependent on the whole deposition process in close-space sublimation (CSS). The physical mechanism of CSS was analyzed aud the temperature distribution in CSS system was measured, and the influences of the increasing-temperature process and pressure on the preliminary nucleus creation were studied. The resuits indicate : tire samples deposited at different pressures hare a cubical structure of CdTe and the diffraction peaks of CdS and SnO2 : F. As the atmosphere pressure increases, the crystal size of CdTe decreases, the rate of the transparency of the thin film decreases and the absorption side moves towards the short-wave direction. After a 4-minute depositing process with a substrate teraw.rature of 500℃ and a source temperature of 620 ℃, the polycostallinc thin films can be mmade , so the production of high-quality integrated cell with StrO2: F/ CdS/ CdTe/ Au structure is hopeful.展开更多
Freeze-drying of the initially porous frozen material with pre-built pores from liquid material was found experimentally to save drying time by over 30% with an initial saturation being 0.28 compared with the conventi...Freeze-drying of the initially porous frozen material with pre-built pores from liquid material was found experimentally to save drying time by over 30% with an initial saturation being 0.28 compared with the conventional operation with the initial saturation being 1, using mannitol as the solid material. In order to understand the mass and heat transfer phenomena of this novel process, a two-dimensional mathematical model of coupled mass and heat transfer was derived with reference to the cylindrical coordinate system. Three adsorption–desorption equilibrium relationships between the vapour pressure and saturation value namely, power-law, Redhead's style and Kelvin's style equation, were tested. Kelvin's style in exponential form of adsorption equilibrium relation gave an excellent agreement between the model prediction and experimental measurement when the equation parameter, γ, of 5000 was applied. Analyses of temperature and ice saturation profiles show that additional heat needs to be supplied to increase the sample temperature in order to promote the desorption process. Simulation also shows that there is a threshold initial porosity after which the drying time decreased with the increase in the initial porosity. Enhanced freeze-drying is expected to be achieved by simultaneously enhancing mass and heat transfer of the process.展开更多
Blowing snow is an important part of snow hydrologic processes in mountainous region, however the related researches were rare for the Qilian mountainous region where blowing snow is frequent. Using the observation da...Blowing snow is an important part of snow hydrologic processes in mountainous region, however the related researches were rare for the Qilian mountainous region where blowing snow is frequent. Using the observation dataset in 2008 snow season in Binggou wa- tershed in Qilian mountainous region, we systematically studied the energy and mass processes of blowing snow by field observation and model simulation. The results include the analysis of snow observation, the occurrence probability of blowing snow, blowing snow transport and blowing snow sublimation. It was found that blowing snow was obvious in high altitude region (4,146 m), the snow redislribution phenomena was remarkable. In Yakou station in the study region, blowing snow was easily occurred in midwinter and early spring when no snowmelt, the blowing snow transport was dominated in this period; when snowmelt beginning, the occur- rence probability of blowing snow decreased heavily because of the increasing air temperature, melt, and refrozen phenomena. The blowing snow sublimation accounted for 41.5% of total snow sublimation at Yakou station in 2008 snow season.展开更多
Drying is an important unit operation in processing of biological resources. The drying process may influence the product properties and quality, which may shrink, break or undergo rheological, physical and biochemica...Drying is an important unit operation in processing of biological resources. The drying process may influence the product properties and quality, which may shrink, break or undergo rheological, physical and biochemical changes. The important parameters responsible for such changes are drying conditions, type of drying technology and residence drying time. Thermal conductivity, thermal-mass diffusivity, enthalpy, porosity and density are the main material property and heat-mass transfer parameters, which are essential for understanding the changes in product quality and for designing and dimensioning the drying processes. In this paper physical properties of food products undergoing a combined sublimation and evaporation were studied. Pieces of vegetables and potatoes were dried in a heat pump fluidized bed dryer at combined modes with temperatures below the freezing point in the beginning and a final drying step at temperatures above the freezing point. Samples of products were tested at different moisture contents with respect to physical properties. Physical properties of leek and potato samples were measured and mass diffusivities were determined from drying kinetic data. Based on bulk density and rehydration measurements it was clearly observed that drying temperature and modes influenced the final product physical properties. The potato cube run dried with initial atmospheric freeze-drying step had rehydration ability 430%above a run dried only above the freezing point. The average effective mass diffusivity for 5 mm slabs of leek was 0.5 x 10-11m2·s-1 for the sublimation stage and 2.2 x 10-11m2·s-1 for the evaporation stage.展开更多
We report the effects of post-thermal treatment on the quality of 2-inch 6H-SiC wafer cut from a crystal boule grown by physical vapour transportation method. The full widths at half maximum of x-ray diffraction rocki...We report the effects of post-thermal treatment on the quality of 2-inch 6H-SiC wafer cut from a crystal boule grown by physical vapour transportation method. The full widths at half maximum of x-ray diffraction rocking curves measured on sites across the 2-inch wafer become narrower, indicating the quality improvement after a three-step post-thermal treatment. It is found that the most common defects such as micropipes and inclusions can be significantly reduced after the treatment. Our results show that the post-thermal treatment is an effective route to improve the quality of SiC single crystals.展开更多
CdTe films are prepared by closed-space sublimation technology. Dependence of film crystalline on substrate materials and substrate temperature is investigated. It is found that films exhibit higher crystallinity at s...CdTe films are prepared by closed-space sublimation technology. Dependence of film crystalline on substrate materials and substrate temperature is investigated. It is found that films exhibit higher crystallinity at substrate temperature higher than 400 ℃. And the CdTe films deposited on CdS films with higher crystallinity have bigger crystallite and higher uniformity. Treatment with CdCl 2 methanol solution promotes the crystallite growth of CdTe films during annealing.展开更多
6H-SiC single crystals were grown by sublimation method. It is found that foreign grains occur frequently on the facets of the crystals. To characterize the foreign grain, a longitudinal and a sectional cut samples we...6H-SiC single crystals were grown by sublimation method. It is found that foreign grains occur frequently on the facets of the crystals. To characterize the foreign grain, a longitudinal and a sectional cut samples were prepared by standard mechanical processing method. Raman spectrum confirms that the foreign grain is actually a mis-oriented 6H-SiC grain. The surface structure of the foreign grain was studied by chemical etching and optical microscopy. It is shown that etch pits in foreign grain region take the shape of isosceles triangle, which are different from those in mono-crystalline region, and high density stacking faults are observed on the surface of the foreign grain. The orientation of foreign grain surface is determined to be (10]-4) plane by back-scattering X-ray Laue image. The X-ray powder diffraction reveals that the powder is partly graphitized after a long crystal growth rim. Therefore it is believed that the loss of Si results in the formation of C inclusions, which is responsible for the nucleation of foreign grain in the facet region.展开更多
文摘In The Old Man and the Sea, Hemingway depicts a simple but fascinating story of a fisherman who catches and loses a big fish after struggling for eight four days at sea. By means of text analysis, this paper aims to analyze the fiction in terms of its title, its main character, Santiago and its writing style—"the Iceberg Theory", thus draws the conclusion that beneath the story's simplicity lies in its greatness and sublimity.
文摘Looking at the last decades of the 19th and 20th century from our vantage point encourages parallels to be drawn between the two periods: in fact, both are affected by a process of cultural fragmentation, social, and epistemological transformations and crises that permeate the whole civil society. In the specific field of English literature, the genre of the fantastic is undoubtedly a common presence. In Fantasy: The Literature of Subversion, Jackson (1981) noted the re-emergence of the fantastic as a transgressive force at moments of cultural stress and repression. Waugh (1995) held a similar view in The Harvest of the Sixties. At the end of the 20th century, in its postmodernist shape, fantastic literature becomes one of the favourite genres of a number of feminist writers, and among them, Jeanette Winterson transforms it into a truly transgressive genre. This paper examines Winterson's The Passion (1996) and Sexing the Cherry (1990) in the light of Jackson's theory of the fantastic, as a narrative that establishes an oppositional dialogic relationship with the "real", to interrogate it and collapse the traditional distinction between the normative and the "other". In The Passion, the real is signified by the dominant ideological discourse, exemplified by Napoleon; the fantastic by Villanelle's webbed feet and her ability to walk on water. In Sexing the Cherry, the real is represented by the Puritans with their bigoted and hypocritical morality; the fantastic by the huge Dog-Woman and her foundling son, Jordan. Besides, in both novels, the female body is metamorphosed to challenge the view of a "normal", acceptable femininity; what emerges is a monstrous and sublime body that collapses distinctions between gender boundaries. In Sexing the Cherry (1990), Winterson created the grotesque, gigantic body of the Dog-Woman, a figure of Kristevan "abjection". In The Passion (1996), she gave life to the hybrid body of Villanelle, an oxymoronic combination of the terrible beautiful. The conclusion of the paper argues that Winterson deploys the fantastic to deconstruct the gendered subject of the dominant signifying order and create a dislocated world outside commercial culture, where new voices can be heard, speaking for unheard, neglected groups, particularly women.
文摘Longinus's On the Sublime holds a uniquely unparalleled position in Western critical theories. By analyzing Li Bai's well-known poem Cataract on Mount Lu from the perspective of sublimity, attempt is made to appreciate the ancient Chinese poems by using Western critical theory and thus derive another kind of aesthetic beauty.
基金supported by the Ministry of Science and Higher Education of the Russian Federation(Agreement with Zelinsky Institute of Organic Chemistry RAS Grant No.075-15-2020-803).
文摘In this work, comprehensive studies of 2,4-dinitroanisole(2,4DNAN) were carried out using powder thermorentgenography of the internal standard. The time of the complete polymorphic transition in the solid phase β→a in 2,4DNAN under various combinations of conditions has been determined. It has been established that, regardless of the season of manufacture of the substance, when it is stored for 8-9months, with a change in ambient temperature from minus 30℃ to plus 30℃, a complete polymorphic transition β→a occurs. When stored in conditions below minus 5℃, polymorphic transition does not occur. When stored in conditions above plus 30℃ in a closed container, polymorphic transition occurs within 3 weeks. The polymorphic transition is accompanied by a decrease in density by 1.3%-1.5% and an increase in melting temperature by 10-12℃, depending on the degree of purity of the starting substance. The activation energy of the molecular rearrangement was 68-70 k J/mol(16.5 ± 3 kcal/mol). The mechanism of polymorphic transition has been evaluated, which is presumably based on internal homodiffusion and energy transfer to the surface of the mass of powder particles and the product. The average activation energy of the polymorphic transition process was 110 ± 6.2 k J/mol(26.2 kcal/mol). In an open container, reactions proceed by a homogeneous mechanism, and in a closed container by a heterogeneous mechanism involving the gas phase.
基金financially supported by the General Research Fund(16309918)from the Research Grant Council,Hong Kongfunding from the Institute for Advanced Study of the Hong Kong University of Science and Technology。
文摘Close-space sublimation(CSS)has been demonstrated as an alternative vacuum deposition technique for fabricating organic light-emitting diodes(OLEDs).CSS utilizes a planar donor plate pre-coated with organic thin films as an area source to rapidly transfer the donor film to a device substrate at temperatures below 200℃.CSS is also conformal and capable of depositing on odd-shaped substrates using flexible donor media.The evaporation behaviors of organic donor films under CSS were fully characterized using model OLED materials and CSS-deposited films exhibited comparable device performances in an OLED stack to films deposited by conventional point sources.The low temperature and conformal nature of CSS,along with its high material utilization and short process time,make it a promising method for fabricating flexible OLED displays.
基金Supported by Special Fund for the Construction of Modern Agricultural Technology System(NYCYTX-43-syz3)~~
文摘[Objective] This study aimed to compare the effects of sublimed sulfur and acaricide on controlling bee mites.[Method] Three independent experiments were carried out in the same apiary during 2007-2009.[Results] The results showed that this method is effective in eliminating mites settled on combs or hidden during pupae phase,but not in controlling the mites parasitized on adult bees.The control effect on killing Varroa destructor after treated appeared optimal in the first day and then decreased,and that on killing Tvopilaelaps clareae happened in the second day.The results indicated that the effect would be much better if the bees can be treated 1 time to 2 times again in the following 2-5 days after the first treatment.Back to data pool,we found that the treatment of sublimed sulfur paired with acaricide is effective in controlling V.destructor and T.clareae.[Conclusion] This technique could facilitate the apicultural production in the regions suffered from V.destructor and T.clareae.
文摘Through defining the differences between literary and non-literary translation and quoting some relating theories of aestheticalness,this paper sets the translation of Mr. Zhu Ziqing&#39;s famous prose《荷塘月色》as an example to analyze how to transform the artistic conception into translation without any deviation to realize the true reciprocity in literary translation. It mainly explain the theory from three aspects:Phonological beauty,Symmetrical beauty and Conceptional beauty. It may have certain guiding meanings for the practices of literary translation.
文摘Yeats' lyrics of sublimation is one of his major concerns in his later years. Sublimation for Yeats is essentially the transmutation and elevation of bitterness and tragic facts of being into happiness, into tranquility of mind, then into the emotionless emotion, as Yeats names it as "innocence". The process of sublimation enriches the creativity of Yeats as artist when he is confronted with severity of aging spiritually and physically.
基金the National Natural Science Foundation of China!(No.597760 14 )
文摘This paper establishes the mathematical model in calculating the effective thermal conductivity and the effective mass diffusivity of dried layer of beef undergoing freeze drying process.First,experimental measurements are done on the dehydrated quantity as well as temperature variations at different locations of the beef steak.Then the effective thermal conductivity and the effective mass diffusivity are calculated by applying the above mathematical model on the data of the dehydrated quantity.These two coefficients are further used in the calculation of temperature distribution.The result is in agreement with the measurement,thus confirming the correctness of the model and the values of the coefficients.
基金Supported by the National Natural Science Foundation of China(21076042)Research Grants Council of Hong Kong SAR (RGC 600704)
文摘Freeze drying or lyophilization of aqueous solutions is widely used in pharmaceutical industry. The in-creased importance Of the process is gaining a worldwide interest of research. A growing body of literature has demonstrated that the scientific approach can result in improved product quality with minimum trial and error em-piricism. Formulation and process development need a systematical understanding of the physical chemistry of freezing and freeze drying, material science and mechanisms of heat and mass transfer. This paper presents an overview on freeze ding of aqueous solutions based on publications in the past few decades. The important issuesof the process are analyzed.
基金Project supported National Natural Science Foundation of China(60025409 and 50472068)National"863"High Technology Plan(2001AA311080)
文摘High-resolution X-ray diffractometry(HRXRD)was used to assess the quality of 6H-SiC crystals grown by sublimation method.The results show the occurrence of low-angle grain boundaries(LB)is close relative to the inclination of the crystal interface.At the central faceted region with 0°inclination the crystal is of high structural perfection.However,at the region close to the facet with less than 5°inclination LB occurs slightly and at the region close to the peripheral polytype ring with more than 5°inclination LB defect occurs heavily.The density of LB can be drastically reduced by decreasing radial temperature gradient that determines the shape of the crystal growth interface.
基金This work was financially supported by the National Natural Science Foundation of China(No.51602018)the Beijing Municipal Natural Science Foundation(No.2154052)+1 种基金the China Postdoctoral Science Foundation(No.2014M560044)the Fundamental Research Funds for the Central Universities,China(No.FRF-GF-17-B7).
文摘In order to remediate heavy metal ions from waste water,Al2O3–SiO2 composite aerogels are prepared via a sol–gel and an organic solvent sublimation drying method.Various characterisation techniques have been employed including X-ray diffraction(XRD),Fourier transform infrared spectrometry(FTIR),scanning electron microscope(SEM),Energy-dispersion X-ray spectroscopy(EDX),Brunauer–Emmett–Teller(BET)N2 adsoprtion isotherm,and atomic absorption spectrometer(AAS).XRD and FTIR suggest that the aerogels are composed of mainly Al2O3 and minor SiO2.They have a high specific surface area(827.544 m^2/g)and high porosity(86.0%)with a pore diameter of~20 nm.Their microstructures show that the distribution of Al,Si,and O is homogeneous.The aerogels can remove~99%Cu^2+within~40 min and then reach the equilibrium uptake(~69 mg/g).Preliminary calculations show that the Cu2+uptake by the aerogels follows pseudo second-order kinetics where chemical sorption may take effect owing largely to the high surface area,high porosity,and abundant functional groups,such as Al–OH and Si–OH,in the aerogel network.The prepared aerogels may serve as efficient absorbents for Cu^2+removal.
基金financial support from National Natural Science Foundation of China(No.11805265)Key Laboratory of Micro-Satellites,Chinese Academy of Sciences(No.KFKT201903)is gratefully acknowledged。
文摘This paper reports the ignition performance of the iodine-fueled radio frequency(RF)ion thruster(IRIT)at different anode temperaturesT_(a0).The experimental results show that the anode temperature plays important role on the ignition process of the IRIT.There were two characteristic temperatures related to the anode:the minimum ignition temperatureT_(i0)and the stable ignition temperatureT_(is),which were much lower than the pipeline temperature and the storage tank temperature.AtT_(a0)<T_(i0),it failed to discharge.WhenT_(i0)≤T_(a0)<T_(is),it was ignited with dramatical oscillations.AtT_(a0)≥T_(is),the discharge was stable in a large anode temperature range.The analysis showed that the different discharge phenomena at different anode temperatures were attributed to the change of iodine flow rate during the process of the iodine deposition-clogging and sublimation-clearing inside the thruster.The research helps improve the preheating design of the iodine-fueled electric thruster.
文摘The structure and characteristics of CdTe thin filrns are closely dependent on the whole deposition process in close-space sublimation (CSS). The physical mechanism of CSS was analyzed aud the temperature distribution in CSS system was measured, and the influences of the increasing-temperature process and pressure on the preliminary nucleus creation were studied. The resuits indicate : tire samples deposited at different pressures hare a cubical structure of CdTe and the diffraction peaks of CdS and SnO2 : F. As the atmosphere pressure increases, the crystal size of CdTe decreases, the rate of the transparency of the thin film decreases and the absorption side moves towards the short-wave direction. After a 4-minute depositing process with a substrate teraw.rature of 500℃ and a source temperature of 620 ℃, the polycostallinc thin films can be mmade , so the production of high-quality integrated cell with StrO2: F/ CdS/ CdTe/ Au structure is hopeful.
基金Supported by the Fundamental Research Funds for the Central Universities(DUT14RC(3)008)the National Natural Science Foundation of China(21076042)the Research Grants Council of Hong Kong SAR(HKUST600704)
文摘Freeze-drying of the initially porous frozen material with pre-built pores from liquid material was found experimentally to save drying time by over 30% with an initial saturation being 0.28 compared with the conventional operation with the initial saturation being 1, using mannitol as the solid material. In order to understand the mass and heat transfer phenomena of this novel process, a two-dimensional mathematical model of coupled mass and heat transfer was derived with reference to the cylindrical coordinate system. Three adsorption–desorption equilibrium relationships between the vapour pressure and saturation value namely, power-law, Redhead's style and Kelvin's style equation, were tested. Kelvin's style in exponential form of adsorption equilibrium relation gave an excellent agreement between the model prediction and experimental measurement when the equation parameter, γ, of 5000 was applied. Analyses of temperature and ice saturation profiles show that additional heat needs to be supplied to increase the sample temperature in order to promote the desorption process. Simulation also shows that there is a threshold initial porosity after which the drying time decreased with the increase in the initial porosity. Enhanced freeze-drying is expected to be achieved by simultaneously enhancing mass and heat transfer of the process.
基金funded by the National Natural Science Foundation of China(Grant Nos.913252034100124041071227)
文摘Blowing snow is an important part of snow hydrologic processes in mountainous region, however the related researches were rare for the Qilian mountainous region where blowing snow is frequent. Using the observation dataset in 2008 snow season in Binggou wa- tershed in Qilian mountainous region, we systematically studied the energy and mass processes of blowing snow by field observation and model simulation. The results include the analysis of snow observation, the occurrence probability of blowing snow, blowing snow transport and blowing snow sublimation. It was found that blowing snow was obvious in high altitude region (4,146 m), the snow redislribution phenomena was remarkable. In Yakou station in the study region, blowing snow was easily occurred in midwinter and early spring when no snowmelt, the blowing snow transport was dominated in this period; when snowmelt beginning, the occur- rence probability of blowing snow decreased heavily because of the increasing air temperature, melt, and refrozen phenomena. The blowing snow sublimation accounted for 41.5% of total snow sublimation at Yakou station in 2008 snow season.
文摘Drying is an important unit operation in processing of biological resources. The drying process may influence the product properties and quality, which may shrink, break or undergo rheological, physical and biochemical changes. The important parameters responsible for such changes are drying conditions, type of drying technology and residence drying time. Thermal conductivity, thermal-mass diffusivity, enthalpy, porosity and density are the main material property and heat-mass transfer parameters, which are essential for understanding the changes in product quality and for designing and dimensioning the drying processes. In this paper physical properties of food products undergoing a combined sublimation and evaporation were studied. Pieces of vegetables and potatoes were dried in a heat pump fluidized bed dryer at combined modes with temperatures below the freezing point in the beginning and a final drying step at temperatures above the freezing point. Samples of products were tested at different moisture contents with respect to physical properties. Physical properties of leek and potato samples were measured and mass diffusivities were determined from drying kinetic data. Based on bulk density and rehydration measurements it was clearly observed that drying temperature and modes influenced the final product physical properties. The potato cube run dried with initial atmospheric freeze-drying step had rehydration ability 430%above a run dried only above the freezing point. The average effective mass diffusivity for 5 mm slabs of leek was 0.5 x 10-11m2·s-1 for the sublimation stage and 2.2 x 10-11m2·s-1 for the evaporation stage.
基金Supported by the National Natural Science Foundation of China under Grant Nos 50132040 and 50302014, the National Basic Research Program of China, and the Knowledge Innovation Project of Chinese Academy of Sciences.
文摘We report the effects of post-thermal treatment on the quality of 2-inch 6H-SiC wafer cut from a crystal boule grown by physical vapour transportation method. The full widths at half maximum of x-ray diffraction rocking curves measured on sites across the 2-inch wafer become narrower, indicating the quality improvement after a three-step post-thermal treatment. It is found that the most common defects such as micropipes and inclusions can be significantly reduced after the treatment. Our results show that the post-thermal treatment is an effective route to improve the quality of SiC single crystals.
文摘CdTe films are prepared by closed-space sublimation technology. Dependence of film crystalline on substrate materials and substrate temperature is investigated. It is found that films exhibit higher crystallinity at substrate temperature higher than 400 ℃. And the CdTe films deposited on CdS films with higher crystallinity have bigger crystallite and higher uniformity. Treatment with CdCl 2 methanol solution promotes the crystallite growth of CdTe films during annealing.
基金Projects(2006AA03A145,2007AA03Z405) supported by the National High-Tech Research and Development Program of ChinaProjects(50721002,50802053) supported by the National Natural Science Foundation of ChinaProject (707039) supported by the Cultivation Fund of the Key Scientific and Technical Innovation Project,Ministry of Education of China
文摘6H-SiC single crystals were grown by sublimation method. It is found that foreign grains occur frequently on the facets of the crystals. To characterize the foreign grain, a longitudinal and a sectional cut samples were prepared by standard mechanical processing method. Raman spectrum confirms that the foreign grain is actually a mis-oriented 6H-SiC grain. The surface structure of the foreign grain was studied by chemical etching and optical microscopy. It is shown that etch pits in foreign grain region take the shape of isosceles triangle, which are different from those in mono-crystalline region, and high density stacking faults are observed on the surface of the foreign grain. The orientation of foreign grain surface is determined to be (10]-4) plane by back-scattering X-ray Laue image. The X-ray powder diffraction reveals that the powder is partly graphitized after a long crystal growth rim. Therefore it is believed that the loss of Si results in the formation of C inclusions, which is responsible for the nucleation of foreign grain in the facet region.