高沉浸式学习环境:学习环境设计的新视角

2021年兴起的教育元宇宙为学习环境的设计提供新视角,为回应对学习过程中沉浸体验日渐增长的需求,设计与构建高沉浸式学习环境(High Immersion Learning Environment,HILE)。从沉浸式学习环境的发展现状出发,提出融入XR、数字孪生等技术的一种高沉浸式学习环境,阐述其内涵与特征,并对其架构与应用场景进行设计与分析。HILE的四大特征(融合性、自然性、发展性、人本性)与四层架构(物理层、技术层、功能层、应用层),能实现多情境创设、自然沉浸与自主孪生,支持创设沉浸教室、虚拟远程教室、虚拟学习社区等10类学习情境,应用范围涵盖学科教育、特殊教育、文化场馆教育等在内的所有正式与非正式学习场合。基于HILE的前瞻性研究,对打破目前沉浸式虚拟环境的固有局限性与弊端、促进学习者的高沉浸感学习体验,具有重要意义。

Response of vegetation to temperature and precipitation in Xinjiang during the period of 1998-2009

In this paper,10-day spatio-temporal response of vegetation to the change of temperature and precipitation in spring,summer,autumn and whole year during the period of 1998―2009 was analyzed based on the data of SPOT VEGETATION-NDVI and 10-day average temperature or precipitation from 54 meteorological stations in Xinjiang.The results show that the response of 10-day NDVI to temperature was more significant than that to precipitation,and the maximal response of vegetation to temperature and precipitation lagged for two 10-day periods.Seasonally,the effect of temperature and precipitation on vegetation NDVI was most marked in autumn,then in spring,and it was not significant in summer.The response of vegetation to 10-day change of meteorological factors was positive with a long affecting duration in spring,and it had a relatively short affecting duration in autumn and summer.Spatially,the 10-day maximal response of NDVI to temperature in northern Xinjiang was higher than that in southern Xinjiang.The correlation between the 10-day NDVI in whole year and the temperature in the 0-8th 10-day period was significantly higher than that between the annual NDVI and the annual temperature at all meteorological stations;the interannual change of NDVI was accordant well with the change of annual precipitation.However,the effect of precipitation within a year on NDVI was not strong.The results indicated that interannual change of temperature was not the dominant factor affecting the change of vegetation NDVI in Xinjiang,but the decrease of annual precipitation was the main factor resulting in the fluctuation of vegetation coverage.Ten-day average temperature was an important factor to promote vegetation growth in Xinjiang within a year,but the effect of precipitation on vegetation growth within a year was not strong.

河西走廊-塔克拉玛干沙漠边缘阻击战核心区现状、区划及任务

为了贯彻习近平总书记关于加强荒漠化综合防治、深入推进“三北”等重点生态工程建设重要讲话精神,打赢、打好河西走廊-塔克拉玛干沙漠边缘阻击战,开展阻击战核心区治理区划与分区治理任务研究。依据区域荒漠化土地和风沙活动特点,以“沙源不再危害,尘源有效控制”为目标,在对区域风、沙、尘源地,风沙输移规律、路径及其影响范围,自然地理特征,沙尘源地、风沙口、绿洲间防护缺口、绿洲外围流沙入侵地等空间分布进行系统梳理与分析基础上,提出区域荒漠化治理区划与分区治理的重点任务,以期为打好河西走廊-塔克拉玛干沙漠边缘阻击战提供科学支撑。

The spatio-temporal responses of the carbon cycle to climate and land use/land cover changes between 1981-2000 in China

This paper represents the first national effort of its kind to systematically investigate the impact of changes in climate and land use and land cover （LULC） on the carbon cycle with high-resolution dynamic LULC data at the decadal scale （1990s and 2000s）. Based on simulations using well calibrated and validated Carbon Exchanges in the Vegetation-Soil-Atmosphere （CEVSA） model, tem- poral and spatial variations in carbon storage and fluxes in China may be generated empower us to relate these variations to climate variability and LULC with respect to net primary productivity （NPP）, heterotrophic respiration （HR）, net ecosystem productivity （NEP）, storage and soil carbon （SOC）, and vegetation carbon （VEGC） individually or collectively. Overall, the increases in NPP were greater than HR in most cases due to the effect of global warming with more precipitation in China from 1981 to 2000. With this trend, the NEP remained positive during that period, resulting in a net increase of total amount of carbon being stored by about 0.296 PgC within a 20-year time frame. Because the climate effect was much greater than that of changes of LULC, the total carbon storage in China actually increased by about 0.17 PgC within the 20-year time period. Such findings will contribute to the generation of carbon emissions control policies under global climate change impacts.

Theoretical insight into the selectivities of copper-catalyzing heterogeneous reduction of carbon dioxide

The chemical reduction of carbon dioxide(CO2) has always drawn intensive attentions as it can not only remove CO2 which is the primary greenhouse gas but also produce useful fuels. Industrial synthesis of methanol utilizing copper-based catalysts is a commonly used process for CO2 hydrogenation. Despite extensive efforts on improving its reaction mechanism by identifying the active sites and optimizing the operating temperature and pressure, it is still remains completely unveiled. The selectivities of CO2 electroreduction at copper electrode could mainly be towards carbon monoxide(CO), formic acid(HCOOH), methane(CH4) or ethylene(C2H4), which depends on the chemical potentials of hydrogen controlled by the applied potential. Interestingly, methanol could hardly be produced electrochemically despite utilizing metallic copper as catalysts in both processes. Moreover, the mechanistic researches have also been performed aiming to achieve the higher selectivity towards more desirable higher hydrocarbons. In this work, we review the present proposals of reaction mechanisms of copper catalyzing CO2 reduction in industrial methanol synthesis and electrochemical environment in terms of density functional theory(DFT) calculations, respectively. In addition, the influences of the simulation methods of solvation and electrochemical model at liquid-solid interface on the selectivity are discussed and compared.

A first-principles microkinetic study on the hydrogenation of carbon dioxide over Cu(211) in the presence of water

The hydrogenation of carbon dioxide(CO2)is one of important processes to effectively convert and utilize CO2,which is also regarded as the key step at the industrial methanol synthesis.Water is likely to play an important role in this process,but it still remains elusive.To systematically understand its influence,here we computationally compare the reaction mechanisms of CO2 hydrogenation over the stepped Cu(211)surface between in the absence and presence of water based on microkinetic simulations upon density functional theory(DFT)calculations.The effects of water on each hydrogenation step and the whole activity and selectivity are checked and its physical origin is discussed.It is found that the water could kinetically accelerate the hydrogenation on CO2 to COOH,promoting the reverse water gas shift reaction to produce carbon monoxide(CO).It hardly influences the CO2 hydrogenation to methanol kinetically.In addition,the too high initial partial pressure of water will thermodynamically inhibit the CO2 conversion.

Fluorescence imaging-guided pelvic lymph node localization and resection of bladder cancer after intracutaneous injection of indocyanine green into the lower limbs and perineum

Background:Pelvic lymph node dissection(PLND)in radical cystectomy(RC)is of great significance,but the method and scope of PLND remain controversial.Based on the principle of indirect lymphadenography,we designed a method to localize the whole pelvic lymph nodes by intradermal injection of indocyanine green(ICG)through the lower limbs and perineum,and to evaluate the effectiveness of this method. Methods:In a single center,54 bladder cancer patients who underwent RC and PLND participated in a prospective clinical trial,which began on February 28,2022 and ended on December 30,2022.ICG solution was injected subcutaneously at the medial malleolus of both lower extremities and at both sides of the midline of the perineum.The fluorescent laparoscopy was used to trace,locate,and remove the targeted areas under the image fusion mode.The consistency of lymph node resection was determined by histopathological diagnosis.The impact of ICG guidance on the surgical time of PLND was compared with that of 11 bladder cancer patients who underwent RC and PLND without ICG injection,serving as the control group. Results:Perineal lower limb combined injection can provide comprehensive visualization of pelvic lymph nodes.This technique reduces PLND surgical time and increases the accuracy of PLND. Conclusion:Intracutaneous injection of ICG into the lower limbs and perineum can specifically mark pelvic lymph nodes.Intraoperative fluores-cence imaging can accurately identify,locate,and resect lymph nodes in the pelvic region,reducing PLND surgical time and increasing the accuracy of PLND.