Physiological and ecological mechanisms that define treelines are still debated. It has been suggested that the absence of trees above the treeline is caused by low temperatures that limit growth. Thus, we hypothesize...Physiological and ecological mechanisms that define treelines are still debated. It has been suggested that the absence of trees above the treeline is caused by low temperatures that limit growth. Thus, we hypothesized that there is a critical minimum temperature （CTmin） preventing xylogenesis at treeline. We tested this hypothesis by examining weekly xylogenesis across three and four growing seasons in two natural Smith fir （Abies georgei var. srnithii） treeline sites on the southeastern Tibetan Plateau. Despite differences in the timing of cell differentiation among years, minimum air temperature was the dominant climatic variable associated with xylem growth; the critical minimum temperature （CTmin） for the onset and end of xylogenesis occurred at 0.7 ±0.4 ℃. A process-based modelling chronology of tree-ring formation using this CTmin was consistent with actual tree-ring data. This extremely low CTmin permits Smith fir growing at treeline to complete annual xylem production and maturation and provides both support and a mechanism for treeline formation.展开更多
Pore structure of Chinese coals with heating and pressurization treatments was studied using small angle X-ray scattering （SAXS）, N2 adsorption/desorption isotherms and scanning electron microscope （SEM）. SAXS was...Pore structure of Chinese coals with heating and pressurization treatments was studied using small angle X-ray scattering （SAXS）, N2 adsorption/desorption isotherms and scanning electron microscope （SEM）. SAXS was performed for some sam- ples after heat treatment at seven elevated temperatures from 25 to 250℃ at 0 MPa and for other samples with hydrostatic pressure treatment at 0, 5, 10, 15 and 20 MPa at the room temperature. The results show that N2 adsorption isotherm together with SAXS could be a comprehensive method to evaluate the pore shape and the pore size distribution： the pore shapes are generally spherical for low rank coal and they are mainly ellipsoidal for high rank coal. All these measurements were then interpreted using the fractal theory to reveal relationship between surface fractals and coal rank, and the evolution of surface fractals under heating and pressurization treatments. The results show that surface fractal dimension （Ds） changes with different treating temperature and pressure and maximum vitrinite reflectance （Ro,m）. Especially in the bituminous stage, Ds shows an increasing trend with Ro,m under varied temperatures. Moreover, Ds shows an increasing trend with increasing temperature before 200℃, and a decreasing trend after 200℃. Furthermore, the results show that Ds has a more complex relationship with Ro.m under varied treating temperature than that under varied treating pressure.展开更多
Integrated disaster mitigation needs interpreting torrent catchment areas as complex landscape systems. The history of valley-evolution shows the influence of climate and vegetation on the valley-evolution. The energy...Integrated disaster mitigation needs interpreting torrent catchment areas as complex landscape systems. The history of valley-evolution shows the influence of climate and vegetation on the valley-evolution. The energy-concept (energy dissipation concept including the idea of the energy-line) is used for a simple explanation of debris flow. Examples of heavy debris flow disasters in controlled torrents in the Alps and Pyrenees give hints, which expanding the time scale can show that side-effects restrict or counteract the mitigation measures. A pallet of different mitigation measures to avoid or to reduce some of the side-effects is shown. The comprehensive method of disaster mitigation also includes the effect of vegetation. The pallet includes: avoiding hazards (hazard mapping, warning and alarming), appropriate land use and avoiding disaster-enhancing measures in the landscape and technical measures, which take into account their side-effects. The energy line is used as simple design theory. The Jiu-Jitsu Principle is explained too. With this comprehensive method a more sustainable reduction of disasters seems possible.展开更多
With the rapid increase in the number of three-dimensional （3D） models each year, to quickly and easily find the part desired has become a big challenge of enterprises. Meanwhile, many methods and algorithms have be...With the rapid increase in the number of three-dimensional （3D） models each year, to quickly and easily find the part desired has become a big challenge of enterprises. Meanwhile, many methods and algorithms have been proposed for part retrieval. However, most of the existing methods are designed lbr mechanical parts, and can not be well worked for sheet metal part re- trieval. An approach to feature-based retrieval of sheet metal parts is presented. Firstly, the features frequently used in sheet metal part design are chosen as the ＂＇key words＂ in retrieval. Based on those features, a relative position model is built to express the different relationships of the features in 3D space. Secondly, a description method of the model is studied. With the descrip- tion method the relative position of features in sheet metal parts can be expressed by four location description matrices. Thirdly, based on the relative position model and location description matrices, the equivalent definition of relationships of two feature groups is given which is the basis to calculate the similarity of two sheet metal parts. Next, the tbrmula of retrieval algorithm for sheet metal parts is given. Finally, a prototype system is developed to test and verify the effectiveness of the retrieval method suggested. Experiments verify that the new method is able to meet the requirements of searching sheet metal parts and possesses potentials in practical application.展开更多
Cellulose was first grafted with glycidyl methacrylate （GMA） in an ionic liquid via atom transfer radical polymerization （ATRP） and then the introduced epoxy groups were reacted with ethanediamine （EDA） to obtai...Cellulose was first grafted with glycidyl methacrylate （GMA） in an ionic liquid via atom transfer radical polymerization （ATRP） and then the introduced epoxy groups were reacted with ethanediamine （EDA） to obtain an amino adsorbent. The grafting copolymer and the obtained adsorbent were characterized by FTIR, aH NMR, TEM and SEM. The results showed that the grafted copolymers had grafted polymer chains with well-controlled molecu- lar weight and polydispersity, the polymerization was a controlled system. The cellulose adsorbent had numerous micropores on the surface and showed high performance for Cr（VI） adsorption. The adsorption behavior was pH dependent and the sorption equilibrium was achieved within 2 h on the adsorbent.展开更多
The adaptive generalized Riemann problem(GRP)scheme for 2-D compressible fluid flows has been proposed in[J.Comput.Phys.,229(2010),1448–1466]and it displays the capability in overcoming difficulties such as the start...The adaptive generalized Riemann problem(GRP)scheme for 2-D compressible fluid flows has been proposed in[J.Comput.Phys.,229(2010),1448–1466]and it displays the capability in overcoming difficulties such as the start-up error for a single shock,and the numerical instability of the almost stationary shock.In this paper,we will provide the accuracy study and particularly show the performance in simulating 2-D complex wave configurations formulated with the 2-D Riemann problems for compressible Euler equations.For this purpose,we will first review the GRP scheme briefly when combined with the adaptive moving mesh technique and consider the accuracy of the adaptive GRP scheme via the comparison with the explicit formulae of analytic solutions of planar rarefaction waves,planar shock waves,the collapse problem of a wedge-shaped dam and the spiral formation problem.Then we simulate the full set of wave configurations in the 2-D four-wave Riemann problems for compressible Euler equations[SIAM J.Math.Anal.,21(1990),593–630],including the interactions of strong shocks(shock reflections),vortex-vortex and shock-vortex etc.This study combines the theoretical results with the numerical simulations,and thus demonstrates what Ami Harten observed"for computational scientists there are two kinds of truth:the truth that you prove,and the truth you see when you compute"[J.Sci.Comput.,31(2007),185–193].展开更多
SiO2 functional films were deposited on the surface of titanium by plasma assisted chemical vapour deposition(PACVD) and the composition of films was studied by XPS. Samples deposited with SiO2 films were immersed in ...SiO2 functional films were deposited on the surface of titanium by plasma assisted chemical vapour deposition(PACVD) and the composition of films was studied by XPS. Samples deposited with SiO2 films were immersed in different concentration simulated body fluid(SBF) for biomimetic deposition of hydroxyapatite(HA). The results show that SiO2 functional films deposited on titanium surface with PACVD have good bioactivity. Hydroxyapatite is formed while titanium coated with SiO2 is immersed in simulated body fluid for seven days.展开更多
Sorption isotherms of hydrocarbon and carbon dioxide （CO2） provide crucial information for designing processes to sequester CO2 and recover natural gas from unmineable coal beds. Methane （CH4）, ethane （C2H6）, an...Sorption isotherms of hydrocarbon and carbon dioxide （CO2） provide crucial information for designing processes to sequester CO2 and recover natural gas from unmineable coal beds. Methane （CH4）, ethane （C2H6）, and CO2 adsorption isotherms on dry coal and the temperature effect on their maximum sorption capacity have been studied by performing combined Monte Carlo （MC） and molecular dynamics （MD） simulations at temperatures of 308 and 370 K （35 and 97 ~C） and at pressures up to 10 MPa. Simulation results demonstrate that absolute sorption （expressed as a mass basis） divided by bulk gas density has negligible temperature effect on CH4, C2H6, and CO2 sorption on dry coal when pressure is over 6 MPa. CO2 is more closely packed due to stronger interaction with coal and the stronger interaction between CO2 mole- cules compared, respectively, with the interactions between hydrocarbons and coal and between hydrocarbons. The results of this work suggest that the ＂a＂ constant （pro- portional to TcPc） in the Peng-Robinson equation of state is an important factor affecting the sorption behavior of hydrocarbons. CO2 injection pressures of lower than 8 MPa may be desirable for CH4 recovery and CO2 sequestration. This study provides a quantitative under- standing of the effects of temperature on coal sorptioncapacity for CH4, C2H6, and CO2 from a microscopic perspective.展开更多
This paper establishes a new framework for assessing multimodal statistical causality between cryptocurrency market(cryptomarket)sentiment and cryptocurrency price processes.In order to achieve this,we present an effi...This paper establishes a new framework for assessing multimodal statistical causality between cryptocurrency market(cryptomarket)sentiment and cryptocurrency price processes.In order to achieve this,we present an efficient algorithm for multimodal statistical causality analysis based on Multiple-Output Gaussian Processes.Signals from different information sources(modalities)are jointly modelled as a Multiple-Output Gaussian Process,and then using a novel approach to statistical causality based on Gaussian Processes(GPs),we study linear and non-linear causal effects between the different modalities.We demonstrate the effectiveness of our approach in a machine learning application by studying the relationship between cryptocurrency spot price dynamics and sentiment time-series data specific to the crypto sector,which we conjecture influences retail investor behaviour.The investor sentiment is extracted from cryptomarket news data via methods developed in the area of statistical machine learning known as Natural Language Processing(NLP).To capture sentiment,we present a novel framework for text to time-series embedding,which we then use to construct a sentiment index from publicly available news articles.We conduct a statistical analysis of our sentiment statistical index model and compare it to alternative state-of-the-art sentiment models popular in the NLP literature.In regard to the multimodal causality,the investor sentiment is our primary modality of exploration,in addition to price and a blockchain technologyrelated indicator(hash rate).Analysis shows that our approach is effective in modelling causal structures of variable degree of complexity between heterogeneous data sources and illustrates the impact that certain modelling choices for the different modalities can have on detecting causality.A solid understanding of these factors is necessary to gauge cryptocurrency adoption by retail investors and provide sentiment-and technologybased insights about the cryptocurrency market dynamics.展开更多
This study in 2010 determined the prevalence of smoking and its associated factors among universities students in Shahroud located in the North Eastern of Iran. 1800 students were selected randomly among 20000 student...This study in 2010 determined the prevalence of smoking and its associated factors among universities students in Shahroud located in the North Eastern of Iran. 1800 students were selected randomly among 20000 students of Shahroud universities, to complete a questionnaire Which was prepared based on the Global Youth Tobacco Survey. The prevalence of current smoking was 20% (80% male and 20% female). The most important factors in the tendency to smoking were: friends smoking, stress, separation from family and fun.展开更多
Bi-metallic(Pt–Sn and Sn–Ni) and tri-metallic(Pt–Sn–Ni) catalysts,supported on Al-containing hexagonal mesoporous silica(Al-HMS)(Si/Al = 20) materials,were synthesized.N_2 adsorption–desorption,X-ray diffraction(...Bi-metallic(Pt–Sn and Sn–Ni) and tri-metallic(Pt–Sn–Ni) catalysts,supported on Al-containing hexagonal mesoporous silica(Al-HMS)(Si/Al = 20) materials,were synthesized.N_2 adsorption–desorption,X-ray diffraction(XRD),Brunauer–Emmett–Teller(BET) test,and temperature programed desorption(NH3-TPD)were used to characterize physicochemical characteristics and textural properties of the Al-HMS catalysts.Catalytic performances on hydro-cracking of n-decane at different reaction conditions were studied in a microreactor.Comparison between Pt–Sn,Sn–Ni and Pt–Sn–Ni catalyst under different hydro-cracking conditions was made.The experimental results indicate that the proper balance between the acid and metal functions is the key in synthesizing a catalyst with a better performance in hydro-cracking.Tri-metallic catalyst exhibits the best catalytic performance in n-decane hydro-cracking than two bi-metallic catalysts.展开更多
By using the daily-14 year(1983—1996)NCEP/NCAR 2.5°×2.5° reanalysis data,we carefully study in each pentad the advance and retreat of the summer monsoon in China and given to it a new definition.This d...By using the daily-14 year(1983—1996)NCEP/NCAR 2.5°×2.5° reanalysis data,we carefully study in each pentad the advance and retreat of the summer monsoon in China and given to it a new definition.This definition considered the intensity of southwesterly winds at 850 hPa together with its degree in temperature and moisture.The result revealed that: (1)The advance of the summer monsoon in China shows three abrupt northward shifts and four relatively stationary stays.The four stable stages correspond to the peak of the pro-summer rainy period in South China,the“Meiyu”season in the Changjiang(Yangtze)-Huaihe River Valleys.the rainy season in the downstream of the Huanghe(Yellow)Riyer Valleys and the rainy season in northern China.The retreat of the summer monsoon is so fast that it totally retreats from the mainland at about the mid-August. (2)The northward advance of summer monsoon in China is basically controlled by the seasonal variation latitudinally of the upper level planetary westerlies.It is in roughly accord with the temporal variation in the position of 15 m s^(-1) isotaeh at 200 hPa.The fast retreat of the summer monsoon is mainly due to the blocking effect of the Tibetan Plateau. (3)The advance of 500 hPa subtropical high of the western Pacific is also in aecordanee with the advance of the summer monsoon in China.During the advancement of the summer monsoon, the eastward movement of the subtropical high shows great meaning that it creates the essential condition for the convergence of southward intrusion cold airs with the warm and humid southwesterly winds,which result in precipitation.There are three manifest eastward movements of the subtropical high during its northward advancement.They coincide correspondingly to the beginning of the peak of the pre-summer rainy period in South China,the“Meiyu”season in the Changjiang(Yangtze)-Huaihe River Valleys and finally the rainy season in northern China.The western part of the subtropical high moves eastward to the region of Japan in late July and 展开更多
A class Ф of 5-dimensional functions was introduced and an existence and uniqueness of common fixed points for a family of non-self mappings satisfying a Фi- quasi-contractive condition and a certain boundary condit...A class Ф of 5-dimensional functions was introduced and an existence and uniqueness of common fixed points for a family of non-self mappings satisfying a Фi- quasi-contractive condition and a certain boundary condition was given on complete metrically convex metric spaces, and from which, more general unique common fixed point theorems were obtained. Our main results generalize and improve many same type common fixed point theorems in references.展开更多
Objectives.To examine the prognostic significance of the protein expression of E-cadherin,α-,β-,andγ-catenin in early squamous cervical carcinoma (SCC).Methods.We studied 219patients who underwent r adical hysterec...Objectives.To examine the prognostic significance of the protein expression of E-cadherin,α-,β-,andγ-catenin in early squamous cervical carcinoma (SCC).Methods.We studied 219patients who underwent r adical hysterectomy and bilateral lymphadenectomy at ou r institution for stage IB SCC between 1987and 1993.Immunoh istochemistry using monoclonal antibodies against E-cadherin,α-,β-,andγ-catenin was used to examine protein expression.Ten patients who underwent hysterectom y for uterine prolapse served as controls.Results.Membra ne expression for E-cadherin,α-,β-,andγ-catenin was decreased and low expression(≤50%positive cells)was found in 198/219(90%),154/219(70%),157/219(72%),and 181/219(83%)tumors,respectively,and high(>50%pos-itive cells)in 21/219(10%),65/219(30%),62/219(28%),and 38/219(17%)tumors,respectively.In u-nivariate analysis,all classical c linicopathological param-eters but none of the investigated pr oteins were associated with prognosis.In multivariate analysis,only deep stromal invasion was independently related to survival.Conclu-sion.E-cadherin,α-,β-,andγ-catenin were not inde-pendently associated with prognosis in stage IB SCC.展开更多
Understanding the ecology of the gastrointestinal tract and the impact of the contents on the host mucosa is emerging as an important area for defining both wellness and susceptibility to disease. Targeted delivery of...Understanding the ecology of the gastrointestinal tract and the impact of the contents on the host mucosa is emerging as an important area for defining both wellness and susceptibility to disease. Targeted delivery of drugs to treat specific small intestinal disorders such as small bowel bacterial overgrowth and targeting molecules to interrogate or to deliver vaccines to the remote regions of the small intestine has proven difficult. There is an unmet need for methodologies to release probes/drugs to remote regions of the gastrointestinal tract in furthering our understanding of gut health and pathogenesis. In order to address this concern, we need to know how the regional delivery of a surrogate labeled test compound is handled and in turn, if delivered locally as a liquid or powder, the dynamics of its subsequent handling and metabolism. In the studies we report on in this paper, we chose ^13 C sodium acetate（^13C-acetate）, which is a stable isotope probe that once absorbed in the small intestine can be readily measured non-invasively by collection and analysis of ^13CO2 in the breath. This would provide information of gastric emptying rates and an indication of the site of release and absorptive capacity. In a series of in vitro and in vivo pig experiments, we assessed the enteric-protective properties of a commercially available polymer EUDRAGIT L100-55 on gelatin capsules and also on DRcaps. Test results demonstrated that DRcaps coated with EUDRAGIT L100-55 possessed enhanced enteric-protective properties, particularly in vivo. These studies add to the body of knowledge regarding gastric emptying in pigs and also begin the process of gathering specifications for the design of a simple and cost-effective enteric-coated capsule for delivery of acid-labile macromolecules to the small intestine.展开更多
AIM To identify significant liver disease [including nodular regenerative hyperplasia(NRH)] in asymptomatic Didanosine(DDI) exposed human immunodeficiency virus(HIV) positive patients.METHODS Patients without known li...AIM To identify significant liver disease [including nodular regenerative hyperplasia(NRH)] in asymptomatic Didanosine(DDI) exposed human immunodeficiency virus(HIV) positive patients.METHODS Patients without known liver disease and with > 6 mo previous DDI use had liver stiffness assessed by transient elastography(TE). Those with alanine transaminase(ALT) above upper limit normal and/or TE > 7.65 k Pa underwent ultrasound scan(U/S). Patients with:(1) abnormal U/S; or(2) elevated ALT plus TE > 7.65 k Pa;or(3) TE > 9.4 k Pa were offered trans-jugular liver biopsy(TJLB) with hepatic venous pressure gradient(HVPG) assessment.RESULTS Ninety-nine patients were recruited, median age 50 years(range 31-70), 81% male and 70% men who have sex with men. Ninety-five percent with VL < 50 copies on antiretroviral therapy with median CD4 count 639 IU/L. Median DDI exposure was 3.4 years(range 0.5-14.6). Eighty-one had a valid TE readings(interquartile range/score ratio < 0.3): 71(88%) < 7.65 k Pa, 6(7%) 7.65-9.4 k Pa and 4(6%) > 9.4 k Pa. Seventeen(17%) met criteria for TJLB, of whom 12 accepted. All had HVPG < 6 mm Hg. Commonest histological findings were steatosis(n = 6), normal architecture(n = 4) and NRH(n = 2), giving a prevalence of previously undiagnosed NRH of 2%(95%CI: 0.55%, 7.0%).CONCLUSION A screening strategy based on TE, liver enzymes and U/S scan found a low prevalence of previously undiagnosed NRH in DDI exposed, asymptomatic HIV positive patients. Patients were more likely to have steatosis highlighting the increased risk of multifactorial liver disease in this population.展开更多
基金supported by the National Natural Science Foundations of China(41525001,41661144040,41601204)supported by the Bilateral Project between China and Slovenia(BI-CN/09–11-012)+1 种基金COST Action(FP1106,STRe ESS)supported by the Chinese Academy of Sciences President International Fellowship Initiative for Visiting Scientists(2016VBA074)
文摘Physiological and ecological mechanisms that define treelines are still debated. It has been suggested that the absence of trees above the treeline is caused by low temperatures that limit growth. Thus, we hypothesized that there is a critical minimum temperature （CTmin） preventing xylogenesis at treeline. We tested this hypothesis by examining weekly xylogenesis across three and four growing seasons in two natural Smith fir （Abies georgei var. srnithii） treeline sites on the southeastern Tibetan Plateau. Despite differences in the timing of cell differentiation among years, minimum air temperature was the dominant climatic variable associated with xylem growth; the critical minimum temperature （CTmin） for the onset and end of xylogenesis occurred at 0.7 ±0.4 ℃. A process-based modelling chronology of tree-ring formation using this CTmin was consistent with actual tree-ring data. This extremely low CTmin permits Smith fir growing at treeline to complete annual xylem production and maturation and provides both support and a mechanism for treeline formation.
基金National Major Research Program for Science and Technology of China (Grant No. 2011ZX05034-01)
文摘Pore structure of Chinese coals with heating and pressurization treatments was studied using small angle X-ray scattering （SAXS）, N2 adsorption/desorption isotherms and scanning electron microscope （SEM）. SAXS was performed for some sam- ples after heat treatment at seven elevated temperatures from 25 to 250℃ at 0 MPa and for other samples with hydrostatic pressure treatment at 0, 5, 10, 15 and 20 MPa at the room temperature. The results show that N2 adsorption isotherm together with SAXS could be a comprehensive method to evaluate the pore shape and the pore size distribution： the pore shapes are generally spherical for low rank coal and they are mainly ellipsoidal for high rank coal. All these measurements were then interpreted using the fractal theory to reveal relationship between surface fractals and coal rank, and the evolution of surface fractals under heating and pressurization treatments. The results show that surface fractal dimension （Ds） changes with different treating temperature and pressure and maximum vitrinite reflectance （Ro,m）. Especially in the bituminous stage, Ds shows an increasing trend with Ro,m under varied temperatures. Moreover, Ds shows an increasing trend with increasing temperature before 200℃, and a decreasing trend after 200℃. Furthermore, the results show that Ds has a more complex relationship with Ro.m under varied treating temperature than that under varied treating pressure.
文摘Integrated disaster mitigation needs interpreting torrent catchment areas as complex landscape systems. The history of valley-evolution shows the influence of climate and vegetation on the valley-evolution. The energy-concept (energy dissipation concept including the idea of the energy-line) is used for a simple explanation of debris flow. Examples of heavy debris flow disasters in controlled torrents in the Alps and Pyrenees give hints, which expanding the time scale can show that side-effects restrict or counteract the mitigation measures. A pallet of different mitigation measures to avoid or to reduce some of the side-effects is shown. The comprehensive method of disaster mitigation also includes the effect of vegetation. The pallet includes: avoiding hazards (hazard mapping, warning and alarming), appropriate land use and avoiding disaster-enhancing measures in the landscape and technical measures, which take into account their side-effects. The energy line is used as simple design theory. The Jiu-Jitsu Principle is explained too. With this comprehensive method a more sustainable reduction of disasters seems possible.
基金National High-tech Research and Development Program of China (2009AA043302)
文摘With the rapid increase in the number of three-dimensional （3D） models each year, to quickly and easily find the part desired has become a big challenge of enterprises. Meanwhile, many methods and algorithms have been proposed for part retrieval. However, most of the existing methods are designed lbr mechanical parts, and can not be well worked for sheet metal part re- trieval. An approach to feature-based retrieval of sheet metal parts is presented. Firstly, the features frequently used in sheet metal part design are chosen as the ＂＇key words＂ in retrieval. Based on those features, a relative position model is built to express the different relationships of the features in 3D space. Secondly, a description method of the model is studied. With the descrip- tion method the relative position of features in sheet metal parts can be expressed by four location description matrices. Thirdly, based on the relative position model and location description matrices, the equivalent definition of relationships of two feature groups is given which is the basis to calculate the similarity of two sheet metal parts. Next, the tbrmula of retrieval algorithm for sheet metal parts is given. Finally, a prototype system is developed to test and verify the effectiveness of the retrieval method suggested. Experiments verify that the new method is able to meet the requirements of searching sheet metal parts and possesses potentials in practical application.
基金This research was supported by the National Natural Science Foundation of China，the Natural Science Foundation of Fujian Province
文摘Cellulose was first grafted with glycidyl methacrylate （GMA） in an ionic liquid via atom transfer radical polymerization （ATRP） and then the introduced epoxy groups were reacted with ethanediamine （EDA） to obtain an amino adsorbent. The grafting copolymer and the obtained adsorbent were characterized by FTIR, aH NMR, TEM and SEM. The results showed that the grafted copolymers had grafted polymer chains with well-controlled molecu- lar weight and polydispersity, the polymerization was a controlled system. The cellulose adsorbent had numerous micropores on the surface and showed high performance for Cr（VI） adsorption. The adsorption behavior was pH dependent and the sorption equilibrium was achieved within 2 h on the adsorbent.
基金supported by the Key Program from Beijing Educational Commission(KZ200910028002)PHR(IHLB)and NSFC(10971142,11031001)+3 种基金supported by the National Basic Research Program under the Grant 2005CB321703the National Natural Science Foundation of China(No.10925101,10828101)the Program for New Century Excellent Talents in University(NCET-07-0022)the Doctoral Program of Education Ministry of China(No.20070001036).
文摘The adaptive generalized Riemann problem(GRP)scheme for 2-D compressible fluid flows has been proposed in[J.Comput.Phys.,229(2010),1448–1466]and it displays the capability in overcoming difficulties such as the start-up error for a single shock,and the numerical instability of the almost stationary shock.In this paper,we will provide the accuracy study and particularly show the performance in simulating 2-D complex wave configurations formulated with the 2-D Riemann problems for compressible Euler equations.For this purpose,we will first review the GRP scheme briefly when combined with the adaptive moving mesh technique and consider the accuracy of the adaptive GRP scheme via the comparison with the explicit formulae of analytic solutions of planar rarefaction waves,planar shock waves,the collapse problem of a wedge-shaped dam and the spiral formation problem.Then we simulate the full set of wave configurations in the 2-D four-wave Riemann problems for compressible Euler equations[SIAM J.Math.Anal.,21(1990),593–630],including the interactions of strong shocks(shock reflections),vortex-vortex and shock-vortex etc.This study combines the theoretical results with the numerical simulations,and thus demonstrates what Ami Harten observed"for computational scientists there are two kinds of truth:the truth that you prove,and the truth you see when you compute"[J.Sci.Comput.,31(2007),185–193].
文摘SiO2 functional films were deposited on the surface of titanium by plasma assisted chemical vapour deposition(PACVD) and the composition of films was studied by XPS. Samples deposited with SiO2 films were immersed in different concentration simulated body fluid(SBF) for biomimetic deposition of hydroxyapatite(HA). The results show that SiO2 functional films deposited on titanium surface with PACVD have good bioactivity. Hydroxyapatite is formed while titanium coated with SiO2 is immersed in simulated body fluid for seven days.
基金supported by the National Basic Research Program of China (2014CB239004)the ‘‘Element and Process Constraint Petroleum System Modeling’’ project (No. 2011A-0207) under the Petro China Science Innovation program
文摘Sorption isotherms of hydrocarbon and carbon dioxide （CO2） provide crucial information for designing processes to sequester CO2 and recover natural gas from unmineable coal beds. Methane （CH4）, ethane （C2H6）, and CO2 adsorption isotherms on dry coal and the temperature effect on their maximum sorption capacity have been studied by performing combined Monte Carlo （MC） and molecular dynamics （MD） simulations at temperatures of 308 and 370 K （35 and 97 ~C） and at pressures up to 10 MPa. Simulation results demonstrate that absolute sorption （expressed as a mass basis） divided by bulk gas density has negligible temperature effect on CH4, C2H6, and CO2 sorption on dry coal when pressure is over 6 MPa. CO2 is more closely packed due to stronger interaction with coal and the stronger interaction between CO2 mole- cules compared, respectively, with the interactions between hydrocarbons and coal and between hydrocarbons. The results of this work suggest that the ＂a＂ constant （pro- portional to TcPc） in the Peng-Robinson equation of state is an important factor affecting the sorption behavior of hydrocarbons. CO2 injection pressures of lower than 8 MPa may be desirable for CH4 recovery and CO2 sequestration. This study provides a quantitative under- standing of the effects of temperature on coal sorptioncapacity for CH4, C2H6, and CO2 from a microscopic perspective.
基金Ioannis Chalkiadakis acknowledges the support of Heriot-Watt University through a James-Watt scholarship while undertaking this work.
文摘This paper establishes a new framework for assessing multimodal statistical causality between cryptocurrency market(cryptomarket)sentiment and cryptocurrency price processes.In order to achieve this,we present an efficient algorithm for multimodal statistical causality analysis based on Multiple-Output Gaussian Processes.Signals from different information sources(modalities)are jointly modelled as a Multiple-Output Gaussian Process,and then using a novel approach to statistical causality based on Gaussian Processes(GPs),we study linear and non-linear causal effects between the different modalities.We demonstrate the effectiveness of our approach in a machine learning application by studying the relationship between cryptocurrency spot price dynamics and sentiment time-series data specific to the crypto sector,which we conjecture influences retail investor behaviour.The investor sentiment is extracted from cryptomarket news data via methods developed in the area of statistical machine learning known as Natural Language Processing(NLP).To capture sentiment,we present a novel framework for text to time-series embedding,which we then use to construct a sentiment index from publicly available news articles.We conduct a statistical analysis of our sentiment statistical index model and compare it to alternative state-of-the-art sentiment models popular in the NLP literature.In regard to the multimodal causality,the investor sentiment is our primary modality of exploration,in addition to price and a blockchain technologyrelated indicator(hash rate).Analysis shows that our approach is effective in modelling causal structures of variable degree of complexity between heterogeneous data sources and illustrates the impact that certain modelling choices for the different modalities can have on detecting causality.A solid understanding of these factors is necessary to gauge cryptocurrency adoption by retail investors and provide sentiment-and technologybased insights about the cryptocurrency market dynamics.
文摘This study in 2010 determined the prevalence of smoking and its associated factors among universities students in Shahroud located in the North Eastern of Iran. 1800 students were selected randomly among 20000 students of Shahroud universities, to complete a questionnaire Which was prepared based on the Global Youth Tobacco Survey. The prevalence of current smoking was 20% (80% male and 20% female). The most important factors in the tendency to smoking were: friends smoking, stress, separation from family and fun.
文摘Bi-metallic(Pt–Sn and Sn–Ni) and tri-metallic(Pt–Sn–Ni) catalysts,supported on Al-containing hexagonal mesoporous silica(Al-HMS)(Si/Al = 20) materials,were synthesized.N_2 adsorption–desorption,X-ray diffraction(XRD),Brunauer–Emmett–Teller(BET) test,and temperature programed desorption(NH3-TPD)were used to characterize physicochemical characteristics and textural properties of the Al-HMS catalysts.Catalytic performances on hydro-cracking of n-decane at different reaction conditions were studied in a microreactor.Comparison between Pt–Sn,Sn–Ni and Pt–Sn–Ni catalyst under different hydro-cracking conditions was made.The experimental results indicate that the proper balance between the acid and metal functions is the key in synthesizing a catalyst with a better performance in hydro-cracking.Tri-metallic catalyst exhibits the best catalytic performance in n-decane hydro-cracking than two bi-metallic catalysts.
基金Supported by the South China Sea Monsoon Experiment,Climbing Programme"A"of China.
文摘By using the daily-14 year(1983—1996)NCEP/NCAR 2.5°×2.5° reanalysis data,we carefully study in each pentad the advance and retreat of the summer monsoon in China and given to it a new definition.This definition considered the intensity of southwesterly winds at 850 hPa together with its degree in temperature and moisture.The result revealed that: (1)The advance of the summer monsoon in China shows three abrupt northward shifts and four relatively stationary stays.The four stable stages correspond to the peak of the pro-summer rainy period in South China,the“Meiyu”season in the Changjiang(Yangtze)-Huaihe River Valleys.the rainy season in the downstream of the Huanghe(Yellow)Riyer Valleys and the rainy season in northern China.The retreat of the summer monsoon is so fast that it totally retreats from the mainland at about the mid-August. (2)The northward advance of summer monsoon in China is basically controlled by the seasonal variation latitudinally of the upper level planetary westerlies.It is in roughly accord with the temporal variation in the position of 15 m s^(-1) isotaeh at 200 hPa.The fast retreat of the summer monsoon is mainly due to the blocking effect of the Tibetan Plateau. (3)The advance of 500 hPa subtropical high of the western Pacific is also in aecordanee with the advance of the summer monsoon in China.During the advancement of the summer monsoon, the eastward movement of the subtropical high shows great meaning that it creates the essential condition for the convergence of southward intrusion cold airs with the warm and humid southwesterly winds,which result in precipitation.There are three manifest eastward movements of the subtropical high during its northward advancement.They coincide correspondingly to the beginning of the peak of the pre-summer rainy period in South China,the“Meiyu”season in the Changjiang(Yangtze)-Huaihe River Valleys and finally the rainy season in northern China.The western part of the subtropical high moves eastward to the region of Japan in late July and
基金supported by the National Natural Science Foundation of China(No.11361064)
文摘A class Ф of 5-dimensional functions was introduced and an existence and uniqueness of common fixed points for a family of non-self mappings satisfying a Фi- quasi-contractive condition and a certain boundary condition was given on complete metrically convex metric spaces, and from which, more general unique common fixed point theorems were obtained. Our main results generalize and improve many same type common fixed point theorems in references.
文摘Objectives.To examine the prognostic significance of the protein expression of E-cadherin,α-,β-,andγ-catenin in early squamous cervical carcinoma (SCC).Methods.We studied 219patients who underwent r adical hysterectomy and bilateral lymphadenectomy at ou r institution for stage IB SCC between 1987and 1993.Immunoh istochemistry using monoclonal antibodies against E-cadherin,α-,β-,andγ-catenin was used to examine protein expression.Ten patients who underwent hysterectom y for uterine prolapse served as controls.Results.Membra ne expression for E-cadherin,α-,β-,andγ-catenin was decreased and low expression(≤50%positive cells)was found in 198/219(90%),154/219(70%),157/219(72%),and 181/219(83%)tumors,respectively,and high(>50%pos-itive cells)in 21/219(10%),65/219(30%),62/219(28%),and 38/219(17%)tumors,respectively.In u-nivariate analysis,all classical c linicopathological param-eters but none of the investigated pr oteins were associated with prognosis.In multivariate analysis,only deep stromal invasion was independently related to survival.Conclu-sion.E-cadherin,α-,β-,andγ-catenin were not inde-pendently associated with prognosis in stage IB SCC.
基金Project supported by the Australian Research Council(ARC)Linkage Project Grant(No.LP0990847)
文摘Understanding the ecology of the gastrointestinal tract and the impact of the contents on the host mucosa is emerging as an important area for defining both wellness and susceptibility to disease. Targeted delivery of drugs to treat specific small intestinal disorders such as small bowel bacterial overgrowth and targeting molecules to interrogate or to deliver vaccines to the remote regions of the small intestine has proven difficult. There is an unmet need for methodologies to release probes/drugs to remote regions of the gastrointestinal tract in furthering our understanding of gut health and pathogenesis. In order to address this concern, we need to know how the regional delivery of a surrogate labeled test compound is handled and in turn, if delivered locally as a liquid or powder, the dynamics of its subsequent handling and metabolism. In the studies we report on in this paper, we chose ^13 C sodium acetate（^13C-acetate）, which is a stable isotope probe that once absorbed in the small intestine can be readily measured non-invasively by collection and analysis of ^13CO2 in the breath. This would provide information of gastric emptying rates and an indication of the site of release and absorptive capacity. In a series of in vitro and in vivo pig experiments, we assessed the enteric-protective properties of a commercially available polymer EUDRAGIT L100-55 on gelatin capsules and also on DRcaps. Test results demonstrated that DRcaps coated with EUDRAGIT L100-55 possessed enhanced enteric-protective properties, particularly in vivo. These studies add to the body of knowledge regarding gastric emptying in pigs and also begin the process of gathering specifications for the design of a simple and cost-effective enteric-coated capsule for delivery of acid-labile macromolecules to the small intestine.
基金Supported by The British HIV Association Research Award 2009-￡7800 in total awarded
文摘AIM To identify significant liver disease [including nodular regenerative hyperplasia(NRH)] in asymptomatic Didanosine(DDI) exposed human immunodeficiency virus(HIV) positive patients.METHODS Patients without known liver disease and with > 6 mo previous DDI use had liver stiffness assessed by transient elastography(TE). Those with alanine transaminase(ALT) above upper limit normal and/or TE > 7.65 k Pa underwent ultrasound scan(U/S). Patients with:(1) abnormal U/S; or(2) elevated ALT plus TE > 7.65 k Pa;or(3) TE > 9.4 k Pa were offered trans-jugular liver biopsy(TJLB) with hepatic venous pressure gradient(HVPG) assessment.RESULTS Ninety-nine patients were recruited, median age 50 years(range 31-70), 81% male and 70% men who have sex with men. Ninety-five percent with VL < 50 copies on antiretroviral therapy with median CD4 count 639 IU/L. Median DDI exposure was 3.4 years(range 0.5-14.6). Eighty-one had a valid TE readings(interquartile range/score ratio < 0.3): 71(88%) < 7.65 k Pa, 6(7%) 7.65-9.4 k Pa and 4(6%) > 9.4 k Pa. Seventeen(17%) met criteria for TJLB, of whom 12 accepted. All had HVPG < 6 mm Hg. Commonest histological findings were steatosis(n = 6), normal architecture(n = 4) and NRH(n = 2), giving a prevalence of previously undiagnosed NRH of 2%(95%CI: 0.55%, 7.0%).CONCLUSION A screening strategy based on TE, liver enzymes and U/S scan found a low prevalence of previously undiagnosed NRH in DDI exposed, asymptomatic HIV positive patients. Patients were more likely to have steatosis highlighting the increased risk of multifactorial liver disease in this population.
