Examining the spatiotemporal dynamics and determinants of land urbanization is critical for promoting healthy urban development and the rational use of land resources.Based on the dataset consisting of land use change...Examining the spatiotemporal dynamics and determinants of land urbanization is critical for promoting healthy urban development and the rational use of land resources.Based on the dataset consisting of land use change data and selected factors in 2010 and2020,this study used visual analysis to reveal the spatiotemporal dynamics of land urbanization across prefecture-level cities in China.Meanwhile,the driving forces underlying land urbanization were examined by using geographical detector technique.Following are the findings:1)we find that there exist notable spatial variances in land urbanization across prefecture-level cities.Currently,the differentiation in land urbanization between the northern and southern cities is more pronounced than that between the coastal and inland cities,or between the eastern and western cities.Prefecture-level cities located in central and western China have experienced the most rapid growth in land urbanization.Conversely,the growth rate in northeastern China is the lowest,while the velocity in eastern China remains relatively stable.By using spatial autocorrelation analysis,this study reveals that the land urbanization level in prefecture-level cities has significant spatial agglomeration.2)We further find that land urbanization in China is influenced by factors related to urban land supply and demand,and urban population growth,economic growth,land financial and political incentive have greater impact on land urbanization than other factors.3)We also find that the impacts of determinants on China’s land urbanization vary over time,the explanatory power of economic development increased,while the explanatory power of state forces declined.We argue that integrating the supply and demand factors of land urbanization can provide a more comprehensive understanding of the driving mechanisms underlying land urbanization in China and other transitional countries,and help decision-makers in these countries formulate more detailed and specific land urbanization policies.展开更多
In recent years, the frequency of geological disasters gradually increases in the gully region of the Loess Plateaus centred with Yanhe River Basin. The research on the forming of the geological disasters in gully reg...In recent years, the frequency of geological disasters gradually increases in the gully region of the Loess Plateaus centred with Yanhe River Basin. The research on the forming of the geological disasters in gully region and the disaster process will help us further understand the development of geological disasters and the disaster process. According to the detailed survey of geological disasters in Yan’an City, the river and gully erosion is the main natural predisposing factor that caused the geological disasters in the river gully region. In the forming of ditches and gullies, the surface water system changes the stress form of the original slope and reduces the strength combination of the slope in ways of water erosion and gravity erosion. Gully’s forming stage and stratigraphic contact form have some influence on the geological disasters and disaster process.展开更多
Mounting evidence in stem cell biology has shown that microRNAs(miRNAs) play a crucial role in cell fate specification, including stem cell self-renewal, lineagespecific differentiation, and somatic cell reprogramming...Mounting evidence in stem cell biology has shown that microRNAs(miRNAs) play a crucial role in cell fate specification, including stem cell self-renewal, lineagespecific differentiation, and somatic cell reprogramming.These functions are tightly regulated by specific gene expression patterns that involve miRNAs and transcription factors. To maintain stem cell pluripotency, specific miRNAs suppress transcription factors that promote differentiation, whereas to initiate differentiation, lineagespecific miRNAs are upregulated via the inhibition of transcription factors that promote self-renewal. Small molecules can be used in a similar manner as natural miRNAs, and a number of natural and synthetic small molecules have been isolated and developed to regulate stem cell fate. Using miRNAs as novel regulators of stem cell fate will provide insight into stem cell biology and aid in understanding the molecular mechanisms and crosstalk between miRNAs and stem cells.Ultimately, advances in the regulation of stem cell fate will contribute to the development of effective medical therapies for tissue repair and regeneration. This review summarizes the current insights into stem cell fate determination by miRNAs with a focus on stem cell self-renewal, differentiation, and reprogramming. Small molecules that control stem cell fate are also highlighted.展开更多
This study analyzed the spatial-temporal heterogeneity of green development efficiency and its influencing factors in the growing Xuzhou Metropolitan Area for the period 2000–2015.The slacks-based measure(SBM)model,s...This study analyzed the spatial-temporal heterogeneity of green development efficiency and its influencing factors in the growing Xuzhou Metropolitan Area for the period 2000–2015.The slacks-based measure(SBM)model,spatial autocorrelation,and the geographically weighted regression(GWR)model were used to conduct the analysis.The conclusions were as follows:first,the overall efficiency of green development of the Xuzhou Metropolitan Area decreased,the regional differences and spatial agglomeration shrunk and differences within the region were the main contributors to the regional differences of green development efficiency.Second,the counties with high-efficiency green development were distributed along the coast,and along the routes of the Beijing-Shanghai and the Eastern Longhai railways.A developing axis of the high-efficiency counties was the main feature of the spatial pattern for green development efficiency.Third,regarding spatial correlation and green development efficiency,the High-High type counties in the Xuzhou Metropolitan Area formed a centralized distribution corridor along the inter-provincial border areas of Henan and Jiangsu,whereas the Low-Low type counties were concentrated in the external,marginal parts of the metropolitan area.Fourth,the major factors(ranked in decreasing order of impact)influencing green development efficiency were innovation,government regulations,the economic development level,energy consumption,and industrial structure.These factors exerted their influence to varying extents;the influence of the same factor had different effects in different regions and obvious spatial differences were observed for the different regions.展开更多
Livestock cultivation is a significant source of greenhouse gas(GHG) emissions, accounting for 14.5% of the total anthropogenic emissions. China is responsible for a considerable share of the global livestock emission...Livestock cultivation is a significant source of greenhouse gas(GHG) emissions, accounting for 14.5% of the total anthropogenic emissions. China is responsible for a considerable share of the global livestock emissions, particularly caused by pork production. We used the Kaya identity and the logarithmic mean Divisia index(LMDI) to decompose the national annual GHG emissions from enteric fermentation and manure management in pig farming in China from 1976 to 2016. We decomposed the sources of the emissions into five driving factors:(1) technological progress(e.g., feed improvement);(2) structural adjustment in the livestock sector;(3) structural adjustment in agriculture;(4) affluence;and(5) population growth. The results showed that the net GHG emissions from the pig sector in China increased 16 million tons(Mt) of carbon dioxide equivalents(CO2 eq) during the study period. The decomposition analysis revealed that structural adjustment in agriculture, growing affluence, and population growth contributed to an increase of the GHG emissions of pork production by 23, 41, and 13 Mt CO2 eq, respectively. The technological progress and structural changes in animal husbandry mitigated emissions by –51 and –11 Mt CO2 eq, respectively. Further technological progress in pig production and optimizing the economic structures are critical for further reducing GHG emissions in China's pig industry. Our results highlight the dominant role of technological changes for emission reductions in the pig farming.展开更多
A well-preserved Late Cretaceous-Paleogene palynological flora from the middle member of the Tsagajan Formation and the upper member of the Tsagajan Formation including the Kivda Beds is reported for the first time fr...A well-preserved Late Cretaceous-Paleogene palynological flora from the middle member of the Tsagajan Formation and the upper member of the Tsagajan Formation including the Kivda Beds is reported for the first time from the Arkhara-Boguchan brown coal mine, southeastern part of the Zeya-Bureya Basin. Four palynocomplexes were established for the Cretaceous-Tertiary transition. The climate and phytocoenoses were also analyzed,based on the detailed palynological data. The results are coincident with those of mega-flora studied by Akhmetiev et al. (2002).展开更多
The results of the palynologic and paleobotanic analyses have allowed determining the Paleocene (including Danian) and Eocene deposits in the series of coal-bearing sediments of southeastern flanks of the Raichikhinsk...The results of the palynologic and paleobotanic analyses have allowed determining the Paleocene (including Danian) and Eocene deposits in the series of coal-bearing sediments of southeastern flanks of the Raichikhinsk brown coal field. Their age was corroborated by the palynologic and paleobotanic data. The detailed biostartigraphic data were obtained in the area"Pioneer"for the first time. The coal-bearing strata were correlated with those from the sections of the Arkhara-Boguchan brown coal field and the stratotype of the Tsagajan Formation of the Bureya Belogor’ye.展开更多
Too many climate committees, conferences, articles and publications continue to suggest a one and a half (1.5<span style="white-space:nowrap;">°</span>C) to two degrees (2<span style=&quo...Too many climate committees, conferences, articles and publications continue to suggest a one and a half (1.5<span style="white-space:nowrap;">°</span>C) to two degrees (2<span style="white-space:nowrap;">°</span>C) Celsius as an achievable global limit to climate changes without establishment of any causal link to the proposed anti-warming mechanism. A comprehensive review has found instead that observationally informed projections of climate science underlying climate change offer a different outlook of five to six-degree (5<span style="white-space:nowrap;">°</span>C - 6<span style="white-space:nowrap;">°</span>C) increase as “most accurate” with regard to present trends, climate history and models, yielding the most likely outcome for 2100. The most causative triad for the present warming trend from 1950 to the present is identified in this paper: 1) the tripling (3×) of world population;2) the quadrupling (4×) of carbon emissions;and 3) the quintupling (5×) of the world energy consumption. This paper presents a quantitative, linear global temperature correlation to carbon dioxide levels that has great predictive value, a short temporal feedback loop, and the finding that it is also reversible. The Vostok ice core temperature and CO2 values for the past 400,000 years, with past sea level estimates have produced the sufficiently evidential “Hansen’s Graph”. Detailed analysis results in an equation for global average temperature change and an indebted, long-term sea level rise, from even a 20 ppm of CO2 change above 290 ppm, commonly taken as a baseline for levels before 1950. Comparison to the well-known 800,000 year old Dome C ice core is also performed. The best-performing climate change models and observational analysis are seen to project more warming than the average model often relied upon. World atmosphere, temperature, and sea level trends for 2100 and beyond are analyzed. A laboratory experiment proves the dramatic heat-entrapment capability of CO<sub>2</sub> compared to pure air, which yields insights into the future global atmospheric system. Policy-relevant climate remediation, including gigaton carbon capture, zero and negative emissions and positive individual action, are reviewed and updated, with recommendations.展开更多
Wideband acoustic imaging,which combines compressed sensing(CS)and microphone arrays,is widely used for locating acoustic sources.However,the location results of this method are unstable,and the computational efficien...Wideband acoustic imaging,which combines compressed sensing(CS)and microphone arrays,is widely used for locating acoustic sources.However,the location results of this method are unstable,and the computational efficiency is low.In this work,in order to improve the robustness and reduce the computational cost,a DCS-SOMP-SVD compressed sensing method,which combines the distributed compressed sensing using simultaneously orthogonal matching pursuit(DCS-SOMP)and singular value decomposition(SVD)is proposed.The performance of the DCS-SOMP-SVD is studied through both simulation and experiment.In the simulation,the locating results of the DCS-SOMP-SVD method are compared with the wideband BP method and the DCS-SOMP method.In terms of computational efficiency,the proposed method is as efficient as the DCS-SOMP method and more efficient than the wideband BP method.In terms of locating accuracy,the proposed method can still locate all sources when the signal to noise ratio(SNR)is−20 dB,while the wideband BP method and the DCS-SOMP method can only locate all sources when the SNR is higher than 0 dB.The performance of the proposed method can be improved by expanding the frequency range.Moreover,there is no extra source in the maps of the proposed method,even though the target sparsity is overestimated.Finally,a gas leak experiment is conducted to verify the feasibility of the DCS-SOMP-SVD method in the practical engineering environment.The experimental results show that the proposed method can locate both two leak sources in different frequency ranges.This research proposes a DCS-SOMP-SVD method which has sufficient robustness and low computational cost for wideband acoustic imaging.展开更多
Electrogravitics and electrokinetics can be traced to T. Townsend Brown’s first article “How I Control Gravity” (Science and Invention, 1929) with the unexplained alignment of the “molecular gravitors”. Brown rep...Electrogravitics and electrokinetics can be traced to T. Townsend Brown’s first article “How I Control Gravity” (Science and Invention, 1929) with the unexplained alignment of the “molecular gravitors”. Brown reported that the dielectrics had high propulsive force when the “differently charged elements” were aligned with the voltage source. Perhaps electrogravitics was also revealed in the article “Gravity Nullified: Quartz Crystals Charged by High Frequency Currents Lose Their Weight” which appeared two years earlier in the same magazine in September of 1927. The editors had a change of heart however, in the following issue, they rescinded the article. Much of what we know about T. T. Brown is from his numerous patents and articles, reprinted inElectrogravitics Systems Volume I, by this author who was fortunate to correspond with him in 1981 when he was at the University of Florida. A sample of his detailed correspondence is contained in the out-of-print book,?Ether-Technology:?A Rational Approach to Gravity-Control?by Rho Sigma (1977) and in the recent?Defying Gravity:?The Parallel Universe of T. Townsend Brown,?Paul Schatzkin, (2009, Embassy Books). Also, a five-minute Brown-Bahnson Lab video online shows many of the experimental models that Brown developed toward 1960 with colleague Agnew Bahnson? (http://www.youtube.com/watch?v=Rp4hygoD3RU).展开更多
In this paper,a new storage method for the three-dimensional temperature field data based on artificial neural network(ANN)was proposed.A multilayer perceptron that takes the coordinate(x,y,z)as inputs and temperature...In this paper,a new storage method for the three-dimensional temperature field data based on artificial neural network(ANN)was proposed.A multilayer perceptron that takes the coordinate(x,y,z)as inputs and temperature T as output,is used to fit the three-dimension-al welding temperature field.Effect of number of ANN layers and number of neurons on the fitting errors is investigated.It is found that the errors decrease with the number of hidden layers and neural numbers per layers generally.When the number of hidden layers increases from 1 to 6,the maximum temperature error decreases from 74.74℃to less than 2℃.The three-dimensional temperature field data is obtained by finite element simulation,and the experimental verification is completed by comparing the simulation peak temperatures with the measured results.As an example,an ANN with 4 hidden layers and 12 neurons in each layer were applied to test the performance of the proposed method in storage of the three-dimensional temperature field data during friction stir welding.It is found that the average error between the temperature data stored in ANN and the original simulation data that stored point-by-point is 0.517℃,and the error on the maximum temper-ature is 0.193℃,while the occupied disk space is only 0.27%of that is required in the conventional point-by-point storage.展开更多
As the world’s population has tripled(3x)since 1950,with another 50%increase expected by 2100,global annual carbon dioxide emissions growth rate has quadrupled(4x)since 1950 and global energy demand has quintupled(5x...As the world’s population has tripled(3x)since 1950,with another 50%increase expected by 2100,global annual carbon dioxide emissions growth rate has quadrupled(4x)since 1950 and global energy demand has quintupled(5x),all in the same time period.This discontinuous combination can be called a“3-4-5 Triad”and the sudden acceleration in all three arenas is too stressful on the environment and the damaging effects will be felt globally for centuries to come unless drastic action is taken.More importantly,the energy demand at 5x is outstripping the other two.This clearly means that as the population explodes at 3x,the emerging middle class wants almost twice as much as their usual share as fossil-fueled generators spread around the globe and modern conveniences become more and more desirable.However,such energy demand at 5x is an artificial human need that is predicted by RMI.org to result in four to five billion new window-mounted air conditioners by 2050 that will add even more to the global warming caused by increasing atmospheric carbon.By an examination of paleoclimatology for the past 420,000 years,it is demonstrable that reducing the concentration of this single most prolific heat-trapping gas by geoengineering back to pre-industrial levels of less than 300 ppm can actually give humankind a collective control over the world’s rapidly rising average global temperature and once more,a temperate climate to live in.展开更多
Many years have passed since the two cosmic bodies of the Tunguska meteorite and the Vitim bollid fell to Earth, but so far the substance of these bodies has not been found on Earth. Therefore, each metal body found o...Many years have passed since the two cosmic bodies of the Tunguska meteorite and the Vitim bollid fell to Earth, but so far the substance of these bodies has not been found on Earth. Therefore, each metal body found on the territory of their passage is of particular interest. The body of iron silicide weighing 12 kg was studied, which was accidentally discovered by a hunter of the village of Kyker in the Siberian taiga on the right bank of the Nercha River, Tungokochensky district, Trans-Baikal Territory. Coordinates of the place of discovery are: 53º19'N lat, 116º19'E long. The territory is located in the zone of the passage of the Tunguska meteorite and the Vitim bollid, 25 km from the hunting village of Green Lake. The body is named “Ilekta” after the nearest stream flowing into the Nercha River. The composition and magnetic properties of the exotic find have been determined. It is established that its main mass is composed of iron silicide, gupesiite Fe3Si (zussite?) and contains inclusions of needle-like rhabdite. On the surface, the body is covered with a melting crust, with signs of boiling, a bubbly structure and a film of clay minerals of terrestrial origin. In the molten porous crust, eutectic-schreibersite-gupeiite is observed, and rare titanium carbide crystals are also noted. The magnetic susceptibility of the samples is not uniform (286.6 - 461.8 10-6E-06 m<sup>3</sup>/kg). It is assumed that a drop of melt separated from the flying space body, and experienced overheating and boiling of the surface layer in the dense layers of the atmosphere.展开更多
Glioblastoma(GBM)is the most aggressive malignant brain tumor and has a high mortality rate.Photodynamic therapy(PDT)has emerged as a promising approach for the treatment of malignant brain tumors.However,the use of P...Glioblastoma(GBM)is the most aggressive malignant brain tumor and has a high mortality rate.Photodynamic therapy(PDT)has emerged as a promising approach for the treatment of malignant brain tumors.However,the use of PDT for the treatment of GBM has been limited by its low blood-brain barrier(BBB)permeability and lack of cancer-targeting ability.Herein,brain endothelial cell-derived extracellular vesicles(bEVs)were used as a biocompatible nanoplatform to transport photosensitizers into brain tumors across the BBB.To enhance PDT efficacy,the photosensitizer chlorin e6(Ce6)was linked to mitochondria-targeting triphenylphosphonium(TPP)and entrapped into bEVs.TPPconjugated Ce6(TPP-Ce6)selectively accumulated in the mitochondria,which rendered brain tumor cells more susceptible to reactive oxygen species-induced apoptosis under light irradiation.Moreover,the encapsulation of TPP-Ce6 into b EVs markedly improved the aqueous stability and cellular internalization of TPP-Ce6,leading to significantly enhanced PDT efficacy in U87MG GBM cells.An in vivo biodistribution study using orthotopic GBM-xenografted mice showed that b EVs containing TPP-Ce6[b EV(TPP-Ce6)]substantially accumulated in brain tumors after BBB penetration via transferrin receptor-mediated transcytosis.As such,b EV(TPP-Ce6)-mediated PDT considerably inhibited the growth of GBM without causing adverse systemic toxicity,suggesting that mitochondria are an effective target for photodynamic GBM therapy.展开更多
mitochondrial-targeting moieties to anticancer drugs, antioxidants and sensor molecules. Among them, the most widely applied mitochondrial targeting moiety is triphenylphosphonium(TPP), which is a delocalized cationic...mitochondrial-targeting moieties to anticancer drugs, antioxidants and sensor molecules. Among them, the most widely applied mitochondrial targeting moiety is triphenylphosphonium(TPP), which is a delocalized cationic lipid that readily accumulates and penetrates through the mitochondrial membrane due to the highly negative mitochondrial membrane potential. Other moieties, including short peptides,dequalinium, guanidine, rhodamine, and F16, are also known to be promising mitochondrial targeting agents. Direct conjugation of mitochondrial targeting moieties to anticancer drugs, antioxidants and sensors results in increased cytotoxicity, anti-oxidizing activity and sensing activity, respectively,compared with their non-targeting counterparts, especially in drug-resistant cells. Although many mitochondria-targeted anticancer drug conjugates have been investigated in vitro and in vivo, further clinical studies are still needed. On the other hand, several mitochondria-targeting antioxidants have been analyzed in clinical phases I, II and III trials, and one conjugate has been approved for treating eye disease in Russia. There are numerous ongoing studies of mitochondria-targeted sensors.展开更多
Objective: To investigate the anti-oxidative stress and preventive effect of modified Gongjin-dan (WSY-1075) in a detrusor underactivity rat model. Methods: Rats were randomly allocated to three groups: sham- ope...Objective: To investigate the anti-oxidative stress and preventive effect of modified Gongjin-dan (WSY-1075) in a detrusor underactivity rat model. Methods: Rats were randomly allocated to three groups: sham- operated (control), bladder outlet obstruction-induced detrusor underactivity (BOO-DU), and BOO-DU with WSY-1075 (WSY) groups. WSY-1075 was orally administrated to rats 200 mg daily for 2 weeks pdor to the operation and 4 weeks after the operation. Bladder outlet obstruction was surgically induced in rats by ligation around the urethra avoiding total obstruction. Cystometrography was conducted on rats in each group for examination of bladders. Results: Compared with the control group, bladder outlet obstruction led to a significant increase in oxidative stress with consequent changes to molecular composition, and decrease in maximal detrusor pressure (P〈0.05). WSY-1075 treatment significantly suppressed oxidative stress and prevented degenerative and dysfunctional changes in bladder, as compared with BOO-DU group (P〈0.05). Conclusion: WSY-1075 had beneficial effect on prevention of BOO-DU.展开更多
Objective:To investigate the antiproliferative activity of Salvia miltiorrhiza Bunge.(SM)on the castration-resistant prostate cancer(CRPC)cell line DU-145 in vitro and in vivo.Methods:Prostate cancer cell line(DU-145)...Objective:To investigate the antiproliferative activity of Salvia miltiorrhiza Bunge.(SM)on the castration-resistant prostate cancer(CRPC)cell line DU-145 in vitro and in vivo.Methods:Prostate cancer cell line(DU-145)and normal prostate cell line(RWPE-1)were treated with SM at different concentrations(3.125,12.5,25 and 50μg/mL)to investigate the antiproliferative effects.DNA laddering analysis was performed to investigate the apoptosis of DU-145 cells.Molecular mechanism was investigated by Western blot analysis of p53,Bcl-2,prostate specific antigen(PSA),and androgen receptor(AR).Six-week-old male BALB/c nude mice were randomly divided into normal control group(n=101)and treated group(n=101)which administered 500 mg/kg SM for 2 weeks.Tumor volumes were measured.Results:Treatment with SM resulted in a dose-dependent decrease in cell number of DU-145 cells in comparison with RWPE-1.DNA laddering analysis indicated the apoptosis of DU-145 cells.Treatment with SM increased the expression of p53 and reduced the expression of Bcl-2 proteins.The levels of PSA were considerably reduced in SM-treated group compared to the controls,and a decrease in AR expression was observed when cells were treated with SM in the same pattern as a reduction in PSA.In the tumour xenograft study,SM given once a day for 2 weeks significantly inhibited tumour growth.Conclusion:SM might contribute to the anticancer actions such as induction of apoptosis and inhibition of proliferation of prostate cancer cells.展开更多
基金Under the auspices of National Natural Science Foundation of China(No.42201202,42271177)General Project of Philosophy and Social Science Research in Jiangsu Universities(No.2022SJYB1161)Priority Academic Program Development of Jiangsu Higher Education Institutions(PAPD)。
文摘Examining the spatiotemporal dynamics and determinants of land urbanization is critical for promoting healthy urban development and the rational use of land resources.Based on the dataset consisting of land use change data and selected factors in 2010 and2020,this study used visual analysis to reveal the spatiotemporal dynamics of land urbanization across prefecture-level cities in China.Meanwhile,the driving forces underlying land urbanization were examined by using geographical detector technique.Following are the findings:1)we find that there exist notable spatial variances in land urbanization across prefecture-level cities.Currently,the differentiation in land urbanization between the northern and southern cities is more pronounced than that between the coastal and inland cities,or between the eastern and western cities.Prefecture-level cities located in central and western China have experienced the most rapid growth in land urbanization.Conversely,the growth rate in northeastern China is the lowest,while the velocity in eastern China remains relatively stable.By using spatial autocorrelation analysis,this study reveals that the land urbanization level in prefecture-level cities has significant spatial agglomeration.2)We further find that land urbanization in China is influenced by factors related to urban land supply and demand,and urban population growth,economic growth,land financial and political incentive have greater impact on land urbanization than other factors.3)We also find that the impacts of determinants on China’s land urbanization vary over time,the explanatory power of economic development increased,while the explanatory power of state forces declined.We argue that integrating the supply and demand factors of land urbanization can provide a more comprehensive understanding of the driving mechanisms underlying land urbanization in China and other transitional countries,and help decision-makers in these countries formulate more detailed and specific land urbanization policies.
基金“Twelfth National Five-Year Plan” for science in 2013 “Research and demonstration of key technology of engineering construction in loess hill-gully area” (Item number: 2013BAJ06B03, 2013BAJ06B04)Science and technology co-ordinating innovative engineering projects in Shaanxi Province in 2013 “Research on geological and geotechnical engineering construction in loess hill-gully area of Yan’an City” (Item number: 2012KTZD03-04, 07)
文摘In recent years, the frequency of geological disasters gradually increases in the gully region of the Loess Plateaus centred with Yanhe River Basin. The research on the forming of the geological disasters in gully region and the disaster process will help us further understand the development of geological disasters and the disaster process. According to the detailed survey of geological disasters in Yan’an City, the river and gully erosion is the main natural predisposing factor that caused the geological disasters in the river gully region. In the forming of ditches and gullies, the surface water system changes the stress form of the original slope and reduces the strength combination of the slope in ways of water erosion and gravity erosion. Gully’s forming stage and stratigraphic contact form have some influence on the geological disasters and disaster process.
基金supported by a South Korea Science and Engineering Foundation grant funded by the South Korea government(MEST)(2011-0019243,2011-0019254)a grant from the South Korea Health 21 R and D Project,Ministry of Health and Welfare,South Korea(A120478)a grant from the Korea Health 21 R and D Project,Ministry of Health and Welfare,South Korea(A085136)
文摘Mounting evidence in stem cell biology has shown that microRNAs(miRNAs) play a crucial role in cell fate specification, including stem cell self-renewal, lineagespecific differentiation, and somatic cell reprogramming.These functions are tightly regulated by specific gene expression patterns that involve miRNAs and transcription factors. To maintain stem cell pluripotency, specific miRNAs suppress transcription factors that promote differentiation, whereas to initiate differentiation, lineagespecific miRNAs are upregulated via the inhibition of transcription factors that promote self-renewal. Small molecules can be used in a similar manner as natural miRNAs, and a number of natural and synthetic small molecules have been isolated and developed to regulate stem cell fate. Using miRNAs as novel regulators of stem cell fate will provide insight into stem cell biology and aid in understanding the molecular mechanisms and crosstalk between miRNAs and stem cells.Ultimately, advances in the regulation of stem cell fate will contribute to the development of effective medical therapies for tissue repair and regeneration. This review summarizes the current insights into stem cell fate determination by miRNAs with a focus on stem cell self-renewal, differentiation, and reprogramming. Small molecules that control stem cell fate are also highlighted.
基金Under the auspices of the National Natural Science Foundation of China(No.41671123,41971158,41671122)Major Project of Philosophy and Social Science Research of Jiangsu Universities(No.2018SJZDA010).
文摘This study analyzed the spatial-temporal heterogeneity of green development efficiency and its influencing factors in the growing Xuzhou Metropolitan Area for the period 2000–2015.The slacks-based measure(SBM)model,spatial autocorrelation,and the geographically weighted regression(GWR)model were used to conduct the analysis.The conclusions were as follows:first,the overall efficiency of green development of the Xuzhou Metropolitan Area decreased,the regional differences and spatial agglomeration shrunk and differences within the region were the main contributors to the regional differences of green development efficiency.Second,the counties with high-efficiency green development were distributed along the coast,and along the routes of the Beijing-Shanghai and the Eastern Longhai railways.A developing axis of the high-efficiency counties was the main feature of the spatial pattern for green development efficiency.Third,regarding spatial correlation and green development efficiency,the High-High type counties in the Xuzhou Metropolitan Area formed a centralized distribution corridor along the inter-provincial border areas of Henan and Jiangsu,whereas the Low-Low type counties were concentrated in the external,marginal parts of the metropolitan area.Fourth,the major factors(ranked in decreasing order of impact)influencing green development efficiency were innovation,government regulations,the economic development level,energy consumption,and industrial structure.These factors exerted their influence to varying extents;the influence of the same factor had different effects in different regions and obvious spatial differences were observed for the different regions.
基金financially supported by the National Social Science Fund of China (16CJL035)the China Scholarship Council Program for Visiting Scholars。
文摘Livestock cultivation is a significant source of greenhouse gas(GHG) emissions, accounting for 14.5% of the total anthropogenic emissions. China is responsible for a considerable share of the global livestock emissions, particularly caused by pork production. We used the Kaya identity and the logarithmic mean Divisia index(LMDI) to decompose the national annual GHG emissions from enteric fermentation and manure management in pig farming in China from 1976 to 2016. We decomposed the sources of the emissions into five driving factors:(1) technological progress(e.g., feed improvement);(2) structural adjustment in the livestock sector;(3) structural adjustment in agriculture;(4) affluence;and(5) population growth. The results showed that the net GHG emissions from the pig sector in China increased 16 million tons(Mt) of carbon dioxide equivalents(CO2 eq) during the study period. The decomposition analysis revealed that structural adjustment in agriculture, growing affluence, and population growth contributed to an increase of the GHG emissions of pork production by 23, 41, and 13 Mt CO2 eq, respectively. The technological progress and structural changes in animal husbandry mitigated emissions by –51 and –11 Mt CO2 eq, respectively. Further technological progress in pig production and optimizing the economic structures are critical for further reducing GHG emissions in China's pig industry. Our results highlight the dominant role of technological changes for emission reductions in the pig farming.
文摘A well-preserved Late Cretaceous-Paleogene palynological flora from the middle member of the Tsagajan Formation and the upper member of the Tsagajan Formation including the Kivda Beds is reported for the first time from the Arkhara-Boguchan brown coal mine, southeastern part of the Zeya-Bureya Basin. Four palynocomplexes were established for the Cretaceous-Tertiary transition. The climate and phytocoenoses were also analyzed,based on the detailed palynological data. The results are coincident with those of mega-flora studied by Akhmetiev et al. (2002).
文摘The results of the palynologic and paleobotanic analyses have allowed determining the Paleocene (including Danian) and Eocene deposits in the series of coal-bearing sediments of southeastern flanks of the Raichikhinsk brown coal field. Their age was corroborated by the palynologic and paleobotanic data. The detailed biostartigraphic data were obtained in the area"Pioneer"for the first time. The coal-bearing strata were correlated with those from the sections of the Arkhara-Boguchan brown coal field and the stratotype of the Tsagajan Formation of the Bureya Belogor’ye.
文摘Too many climate committees, conferences, articles and publications continue to suggest a one and a half (1.5<span style="white-space:nowrap;">°</span>C) to two degrees (2<span style="white-space:nowrap;">°</span>C) Celsius as an achievable global limit to climate changes without establishment of any causal link to the proposed anti-warming mechanism. A comprehensive review has found instead that observationally informed projections of climate science underlying climate change offer a different outlook of five to six-degree (5<span style="white-space:nowrap;">°</span>C - 6<span style="white-space:nowrap;">°</span>C) increase as “most accurate” with regard to present trends, climate history and models, yielding the most likely outcome for 2100. The most causative triad for the present warming trend from 1950 to the present is identified in this paper: 1) the tripling (3×) of world population;2) the quadrupling (4×) of carbon emissions;and 3) the quintupling (5×) of the world energy consumption. This paper presents a quantitative, linear global temperature correlation to carbon dioxide levels that has great predictive value, a short temporal feedback loop, and the finding that it is also reversible. The Vostok ice core temperature and CO2 values for the past 400,000 years, with past sea level estimates have produced the sufficiently evidential “Hansen’s Graph”. Detailed analysis results in an equation for global average temperature change and an indebted, long-term sea level rise, from even a 20 ppm of CO2 change above 290 ppm, commonly taken as a baseline for levels before 1950. Comparison to the well-known 800,000 year old Dome C ice core is also performed. The best-performing climate change models and observational analysis are seen to project more warming than the average model often relied upon. World atmosphere, temperature, and sea level trends for 2100 and beyond are analyzed. A laboratory experiment proves the dramatic heat-entrapment capability of CO<sub>2</sub> compared to pure air, which yields insights into the future global atmospheric system. Policy-relevant climate remediation, including gigaton carbon capture, zero and negative emissions and positive individual action, are reviewed and updated, with recommendations.
基金Supported by National Natural Science Foundation of China(Grant Nos.51675425,52075441)Shaanxi Provincial Key Research Program Project of China(Grant No.2020ZDLGY06-09)+1 种基金Dongguan Municipal Social Science and Technology Development(key)Project of China(Grant No.20185071021600)Science and Technology on Micro-system Laboratory Foundation of China(Grant No.6142804200405).
文摘Wideband acoustic imaging,which combines compressed sensing(CS)and microphone arrays,is widely used for locating acoustic sources.However,the location results of this method are unstable,and the computational efficiency is low.In this work,in order to improve the robustness and reduce the computational cost,a DCS-SOMP-SVD compressed sensing method,which combines the distributed compressed sensing using simultaneously orthogonal matching pursuit(DCS-SOMP)and singular value decomposition(SVD)is proposed.The performance of the DCS-SOMP-SVD is studied through both simulation and experiment.In the simulation,the locating results of the DCS-SOMP-SVD method are compared with the wideband BP method and the DCS-SOMP method.In terms of computational efficiency,the proposed method is as efficient as the DCS-SOMP method and more efficient than the wideband BP method.In terms of locating accuracy,the proposed method can still locate all sources when the signal to noise ratio(SNR)is−20 dB,while the wideband BP method and the DCS-SOMP method can only locate all sources when the SNR is higher than 0 dB.The performance of the proposed method can be improved by expanding the frequency range.Moreover,there is no extra source in the maps of the proposed method,even though the target sparsity is overestimated.Finally,a gas leak experiment is conducted to verify the feasibility of the DCS-SOMP-SVD method in the practical engineering environment.The experimental results show that the proposed method can locate both two leak sources in different frequency ranges.This research proposes a DCS-SOMP-SVD method which has sufficient robustness and low computational cost for wideband acoustic imaging.
文摘Electrogravitics and electrokinetics can be traced to T. Townsend Brown’s first article “How I Control Gravity” (Science and Invention, 1929) with the unexplained alignment of the “molecular gravitors”. Brown reported that the dielectrics had high propulsive force when the “differently charged elements” were aligned with the voltage source. Perhaps electrogravitics was also revealed in the article “Gravity Nullified: Quartz Crystals Charged by High Frequency Currents Lose Their Weight” which appeared two years earlier in the same magazine in September of 1927. The editors had a change of heart however, in the following issue, they rescinded the article. Much of what we know about T. T. Brown is from his numerous patents and articles, reprinted inElectrogravitics Systems Volume I, by this author who was fortunate to correspond with him in 1981 when he was at the University of Florida. A sample of his detailed correspondence is contained in the out-of-print book,?Ether-Technology:?A Rational Approach to Gravity-Control?by Rho Sigma (1977) and in the recent?Defying Gravity:?The Parallel Universe of T. Townsend Brown,?Paul Schatzkin, (2009, Embassy Books). Also, a five-minute Brown-Bahnson Lab video online shows many of the experimental models that Brown developed toward 1960 with colleague Agnew Bahnson? (http://www.youtube.com/watch?v=Rp4hygoD3RU).
基金supported by the National Natural Science Foundation of China(Grant No.52175334)the Award Cultivation Foundation from Beijing Institute of Petrochemical Technology(Project No.BIPTACF-009).
文摘In this paper,a new storage method for the three-dimensional temperature field data based on artificial neural network(ANN)was proposed.A multilayer perceptron that takes the coordinate(x,y,z)as inputs and temperature T as output,is used to fit the three-dimension-al welding temperature field.Effect of number of ANN layers and number of neurons on the fitting errors is investigated.It is found that the errors decrease with the number of hidden layers and neural numbers per layers generally.When the number of hidden layers increases from 1 to 6,the maximum temperature error decreases from 74.74℃to less than 2℃.The three-dimensional temperature field data is obtained by finite element simulation,and the experimental verification is completed by comparing the simulation peak temperatures with the measured results.As an example,an ANN with 4 hidden layers and 12 neurons in each layer were applied to test the performance of the proposed method in storage of the three-dimensional temperature field data during friction stir welding.It is found that the average error between the temperature data stored in ANN and the original simulation data that stored point-by-point is 0.517℃,and the error on the maximum temper-ature is 0.193℃,while the occupied disk space is only 0.27%of that is required in the conventional point-by-point storage.
文摘As the world’s population has tripled(3x)since 1950,with another 50%increase expected by 2100,global annual carbon dioxide emissions growth rate has quadrupled(4x)since 1950 and global energy demand has quintupled(5x),all in the same time period.This discontinuous combination can be called a“3-4-5 Triad”and the sudden acceleration in all three arenas is too stressful on the environment and the damaging effects will be felt globally for centuries to come unless drastic action is taken.More importantly,the energy demand at 5x is outstripping the other two.This clearly means that as the population explodes at 3x,the emerging middle class wants almost twice as much as their usual share as fossil-fueled generators spread around the globe and modern conveniences become more and more desirable.However,such energy demand at 5x is an artificial human need that is predicted by RMI.org to result in four to five billion new window-mounted air conditioners by 2050 that will add even more to the global warming caused by increasing atmospheric carbon.By an examination of paleoclimatology for the past 420,000 years,it is demonstrable that reducing the concentration of this single most prolific heat-trapping gas by geoengineering back to pre-industrial levels of less than 300 ppm can actually give humankind a collective control over the world’s rapidly rising average global temperature and once more,a temperate climate to live in.
文摘Many years have passed since the two cosmic bodies of the Tunguska meteorite and the Vitim bollid fell to Earth, but so far the substance of these bodies has not been found on Earth. Therefore, each metal body found on the territory of their passage is of particular interest. The body of iron silicide weighing 12 kg was studied, which was accidentally discovered by a hunter of the village of Kyker in the Siberian taiga on the right bank of the Nercha River, Tungokochensky district, Trans-Baikal Territory. Coordinates of the place of discovery are: 53º19'N lat, 116º19'E long. The territory is located in the zone of the passage of the Tunguska meteorite and the Vitim bollid, 25 km from the hunting village of Green Lake. The body is named “Ilekta” after the nearest stream flowing into the Nercha River. The composition and magnetic properties of the exotic find have been determined. It is established that its main mass is composed of iron silicide, gupesiite Fe3Si (zussite?) and contains inclusions of needle-like rhabdite. On the surface, the body is covered with a melting crust, with signs of boiling, a bubbly structure and a film of clay minerals of terrestrial origin. In the molten porous crust, eutectic-schreibersite-gupeiite is observed, and rare titanium carbide crystals are also noted. The magnetic susceptibility of the samples is not uniform (286.6 - 461.8 10-6E-06 m<sup>3</sup>/kg). It is assumed that a drop of melt separated from the flying space body, and experienced overheating and boiling of the surface layer in the dense layers of the atmosphere.
基金supported by the National Research Foundation of Korea(NRF)grant funded by the Korea government(MSIT)[(NRF-2022R1A2C1007207,Korea)Basic Research Laboratory Program(NRF-2020R1A4A2002894,Korea)+3 种基金Basic Science Research Program(NRF-2020R1A2B5B01001719,Korea)Engineering Research Center of Excellence Program(NRF-2016R1A5A1010148,Korea)]supported by Basic Science Research Program through the NRF funded by the Ministry of Education(NRF-2021R1I1A1A01042149,Korea)support by the Brigham Research Institute,USA。
文摘Glioblastoma(GBM)is the most aggressive malignant brain tumor and has a high mortality rate.Photodynamic therapy(PDT)has emerged as a promising approach for the treatment of malignant brain tumors.However,the use of PDT for the treatment of GBM has been limited by its low blood-brain barrier(BBB)permeability and lack of cancer-targeting ability.Herein,brain endothelial cell-derived extracellular vesicles(bEVs)were used as a biocompatible nanoplatform to transport photosensitizers into brain tumors across the BBB.To enhance PDT efficacy,the photosensitizer chlorin e6(Ce6)was linked to mitochondria-targeting triphenylphosphonium(TPP)and entrapped into bEVs.TPPconjugated Ce6(TPP-Ce6)selectively accumulated in the mitochondria,which rendered brain tumor cells more susceptible to reactive oxygen species-induced apoptosis under light irradiation.Moreover,the encapsulation of TPP-Ce6 into b EVs markedly improved the aqueous stability and cellular internalization of TPP-Ce6,leading to significantly enhanced PDT efficacy in U87MG GBM cells.An in vivo biodistribution study using orthotopic GBM-xenografted mice showed that b EVs containing TPP-Ce6[b EV(TPP-Ce6)]substantially accumulated in brain tumors after BBB penetration via transferrin receptor-mediated transcytosis.As such,b EV(TPP-Ce6)-mediated PDT considerably inhibited the growth of GBM without causing adverse systemic toxicity,suggesting that mitochondria are an effective target for photodynamic GBM therapy.
基金supported by the National Research Foundation of Korea (NRF)funded by the Korean government (MSIT) (NRF2017R1A4A1015036 and NRF-2015R1A1A05001459)the study was supported by BK21PLUS grant of NRF funded by the Korean government (ME) (22A20130012250)
文摘mitochondrial-targeting moieties to anticancer drugs, antioxidants and sensor molecules. Among them, the most widely applied mitochondrial targeting moiety is triphenylphosphonium(TPP), which is a delocalized cationic lipid that readily accumulates and penetrates through the mitochondrial membrane due to the highly negative mitochondrial membrane potential. Other moieties, including short peptides,dequalinium, guanidine, rhodamine, and F16, are also known to be promising mitochondrial targeting agents. Direct conjugation of mitochondrial targeting moieties to anticancer drugs, antioxidants and sensors results in increased cytotoxicity, anti-oxidizing activity and sensing activity, respectively,compared with their non-targeting counterparts, especially in drug-resistant cells. Although many mitochondria-targeted anticancer drug conjugates have been investigated in vitro and in vivo, further clinical studies are still needed. On the other hand, several mitochondria-targeting antioxidants have been analyzed in clinical phases I, II and III trials, and one conjugate has been approved for treating eye disease in Russia. There are numerous ongoing studies of mitochondria-targeted sensors.
基金Supported by the Korea Health Technology R&D Project through the Korea Health Industry Development Institute(KHIDI)funded by the Ministry of Health and Welfare,Republic of Korea(No.HI15C0099)
文摘Objective: To investigate the anti-oxidative stress and preventive effect of modified Gongjin-dan (WSY-1075) in a detrusor underactivity rat model. Methods: Rats were randomly allocated to three groups: sham- operated (control), bladder outlet obstruction-induced detrusor underactivity (BOO-DU), and BOO-DU with WSY-1075 (WSY) groups. WSY-1075 was orally administrated to rats 200 mg daily for 2 weeks pdor to the operation and 4 weeks after the operation. Bladder outlet obstruction was surgically induced in rats by ligation around the urethra avoiding total obstruction. Cystometrography was conducted on rats in each group for examination of bladders. Results: Compared with the control group, bladder outlet obstruction led to a significant increase in oxidative stress with consequent changes to molecular composition, and decrease in maximal detrusor pressure (P〈0.05). WSY-1075 treatment significantly suppressed oxidative stress and prevented degenerative and dysfunctional changes in bladder, as compared with BOO-DU group (P〈0.05). Conclusion: WSY-1075 had beneficial effect on prevention of BOO-DU.
基金Supported by the Bio&Medical Technology Development Program of the National Research Foundation funded by the Ministry of Science&ICT(No.2018M3A9E8020861),Republic of Korea。
文摘Objective:To investigate the antiproliferative activity of Salvia miltiorrhiza Bunge.(SM)on the castration-resistant prostate cancer(CRPC)cell line DU-145 in vitro and in vivo.Methods:Prostate cancer cell line(DU-145)and normal prostate cell line(RWPE-1)were treated with SM at different concentrations(3.125,12.5,25 and 50μg/mL)to investigate the antiproliferative effects.DNA laddering analysis was performed to investigate the apoptosis of DU-145 cells.Molecular mechanism was investigated by Western blot analysis of p53,Bcl-2,prostate specific antigen(PSA),and androgen receptor(AR).Six-week-old male BALB/c nude mice were randomly divided into normal control group(n=101)and treated group(n=101)which administered 500 mg/kg SM for 2 weeks.Tumor volumes were measured.Results:Treatment with SM resulted in a dose-dependent decrease in cell number of DU-145 cells in comparison with RWPE-1.DNA laddering analysis indicated the apoptosis of DU-145 cells.Treatment with SM increased the expression of p53 and reduced the expression of Bcl-2 proteins.The levels of PSA were considerably reduced in SM-treated group compared to the controls,and a decrease in AR expression was observed when cells were treated with SM in the same pattern as a reduction in PSA.In the tumour xenograft study,SM given once a day for 2 weeks significantly inhibited tumour growth.Conclusion:SM might contribute to the anticancer actions such as induction of apoptosis and inhibition of proliferation of prostate cancer cells.