利用可再生电力将二氧化碳转化为高附加值产品的电催化二氧化碳还原反应(CO_(2)RR)是一项具有革命性潜力的技术,因而备受关注.其中,一氧化碳被视为CO_(2)RR中最具经济效益的产物之一,可直接利用费托合成工艺将其用于合成醛、酮、烃类等...利用可再生电力将二氧化碳转化为高附加值产品的电催化二氧化碳还原反应(CO_(2)RR)是一项具有革命性潜力的技术,因而备受关注.其中,一氧化碳被视为CO_(2)RR中最具经济效益的产物之一,可直接利用费托合成工艺将其用于合成醛、酮、烃类等产品.酞菁钴(CoPc)作为单位点催化剂,因其高原子利用率和高催化选择性能,在二氧化碳转化为一氧化碳过程中具有很大优势.然而,CoPc无法为CO_(2)RR中的质子化过程提供足够质子,导致其在工业大电流密度下的效率较低.因此,探索一种能够解决CO_(2)RR中质子供给不足问题的高效电催化剂对于提升CO_(2)RR的性能至关重要.本文设计了具有增强质子供给作用的缺陷碳纳米管(d-CNT),将其作为导电载体分散CoPc,用于制备CoPc/d-CNT电催化剂.通过引入富缺陷的碳纳米管(d-CNT),加速水解离进而增加CO_(2)RR的质子供给量.X射线光电子能谱、X射线吸收近边光谱和扩展X射线吸收精细结构谱结果表明,CoPc/d-CNT成功合成,同时保留了CoPc完整的Co-N4配位结构.透射电镜、粉末X射线衍射谱和拉曼光谱共同表明,d-CNT表面缺陷相对于商用CNT明显增加.动力学实验和原位衰减全反射表面增强红外吸收光谱研究表明,含大量缺陷的d-CNT具有加速水解离的能力,显著提高了二氧化碳还原反应过程中的质子供给,从而促进了CoPc_上CO_(2)活化生成*COOH.同时,密度泛函理论计算结果表明,d-CNT表面缺陷位点上从吸附水(*H2O)到质子水(H3O+)的吉布斯自由能为0.74 eV,远低于CNT(超过2 eV),表明d-CNT促进了水解过程和质子传递,再次证实了d-CNT降低了水分子解离的势垒.通过实验和理论的共同验证,阐明了d-CNT中的缺陷能够促进水解离,改善CO_(2)RR反应过程中质子供给,增强CoPc高效催化CO_(2)RR的能力.因此,CoPc/d-CNT混合材料表现出较好的催化性能.在电流密度为500 mA cm^(-2)的流动电池中,CoPc/d-CNT的CO法拉第效率(FECO)高达96%.相对而言,CoPc/CNT在200 mA cm^(-2)时FECO已经下降到90%以下.此外,在150 mA cm^(-2)的电流密度下,CoPc/d-CNT能够在20 h内维持FECO超过90%.综上,本文通过引入具有水解离能力的缺陷碳位点,解决了单位点催化剂CoPc在CO_(2)RR中质子供给不足的问题,为设计高性能催化剂提供了新见解.展开更多
近年来,具有独特电子效应和协同效应的异质界面工程策略在扩展催化功能和提高本征活性方面显示出较大的应用潜力.其中,具有晶型/无定形(c/a)异质结构的电催化剂,由于结构上的巨大差异,展现出显著的催化活性.然而,c/a-异质界面的可控调...近年来,具有独特电子效应和协同效应的异质界面工程策略在扩展催化功能和提高本征活性方面显示出较大的应用潜力.其中,具有晶型/无定形(c/a)异质结构的电催化剂,由于结构上的巨大差异,展现出显著的催化活性.然而,c/a-异质界面的可控调控及其与电催化性能的内在联系仍缺乏系统研究.因此,本文采用“酸刻蚀-气相磷硫化-淬火”方法,合成了具有可调控c/a异质界面的q-CoPS材料,并将其应用于碱性整体水分解.同时,通过控制淬火的初始温度,实现了对CoPS纳米棒中c/a比例的有效调控.一般来说,在晶型材料中,表面催化往往发生在固定的晶面上.而无定形材料可以同时满足体积和表面的催化.同时,无定形材料具有柔韧性,在催化反应过程中可以转化为任何需要的其他形式,因此在耐腐蚀方面也具有较好的自愈性能.此外,无定形材料还具有丰富的缺陷,运用缺陷工程可以带来一定的性能提升.因此,二者的协同作用可以提升催化剂的催化性能.本文创新性地提出了通过改变淬火初始温度对CoPS纳米棒中c/a比进行调控.采用“酸刻蚀-气相磷硫化-淬火”方法,成功制备了具有独特c/a-CoPS核壳异质结构的q-CoPS纳米棒.随着淬火初始温度的升高,无定形CoPS壳的面积也在逐渐增大.这可能是由于处于非平衡状态的磷硫化物在超低温液氮中突然淬火,处于热运动的Co,P和S原子会迅速冷却,趋向于形成无序的CoPS无定形材料.值得注意的是,制备得到的q-CoPS纳米棒具有合适的c/a含量比,提供了丰富的c/a界面活性位点,并优化了Co位点的电子构型.在析氢反应(HER)中,q-CoPS/CF仅需90 m V的过电位即可以达到1000 m Acm^(-2)的工业级电流密度,结果优于先进的Pt/C.同时,q-CoPS/CF在肼氧化反应(HzOR)中,仅0.06 V时即可实现1000 m Acm^(-2)的电流密度.密度泛函理论计算表明,在HER和HzOR中,界面处的Co原子的内在活性远高于P原子和S原子,c/a-异质界面处活性位点的能垒远低于晶型CoPS和无定形CoPS.此外,Co位点作为c/a界面的双功能活性位点,有效地优化了HER和HzOR的反应动力学.综上所述,q-CoPS/CF催化剂电催化性能的提升主要是由于其具备高活性的CoPS、合适的晶型/无定形(c/a)比例和较大的比表面积.本文为设计具有c/a异质结构的高活性电极提供参考,为进一步探索c/a异质结构的演化和确定c/a界面的活性位点提供借鉴.展开更多
The DarkSHINE experiment proposes a novel approach to single-electron-on-fixed-target exploration that focuses on the search for dark photons through their invisible decay into dark matter particles.Central to this in...The DarkSHINE experiment proposes a novel approach to single-electron-on-fixed-target exploration that focuses on the search for dark photons through their invisible decay into dark matter particles.Central to this initiative is an advanced tracking detector designed to achieve exceptional sensitivity in the detection of light dark matter candidates.This study evaluates the performance of several prototype AC-coupled low-gain avalanche diode(AC-LGAD)strip sensors specifically developed for the DarkSHINE tracking detector.The electrical properties of the sensors from two batches of wafers with different n^(+)doses are thoroughly evaluated.Spatial and temporal resolutions are measured using an infrared laser source.The spatial resolutions range from 6.5 to 8.2μm and from 8.8 to 12.3μm for the sensors from two distinct dose batches,each with a 100μm pitch size.Furthermore,the sensors demonstrate time resolutions of 8.3 and 11.4 ps,underscoring the potential of AC-LGAD technology in enhancing the performance of the DarkSHINE tracking detector.展开更多
Improving the speed of ghost imaging is one of the main ways to leverage its advantages in sensitivity and imperfect spectral regions for practical applications.Because of the proportional relationship between image r...Improving the speed of ghost imaging is one of the main ways to leverage its advantages in sensitivity and imperfect spectral regions for practical applications.Because of the proportional relationship between image resolution and measurement time,when the image pixels are large,the measurement time increases,making it difficult to achieve real-time imaging.Therefore,a high-quality ghost imaging method based on undersampled natural-order Hadamard is proposed.This method uses the characteristics of the Hadamard matrix under undersampling conditions where image information can be fully obtained but overlaps,as well as deep learning to extract aliasing information from the overlapping results to obtain the true original image information.We conducted numerical simulations and experimental tests on binary and grayscale objects under undersampling conditions to demonstrate the effectiveness and scalability of this method.This method can significantly reduce the number of measurements required to obtain high-quality image information and advance application promotion.展开更多
Objective: The purpose of this study was to evaluate the correlation between CT perfusion parameters and the hypoxia-inducible factor-1 alpha (HIF-1α), vascular en-dothelial growth factor (VEGF), matrix metalloprotei...Objective: The purpose of this study was to evaluate the correlation between CT perfusion parameters and the hypoxia-inducible factor-1 alpha (HIF-1α), vascular en-dothelial growth factor (VEGF), matrix metalloproteinase-2 (MMP-2) and microvessel density (MVD) marked by CD34 molecular of rabbit VX2 liver tumors and to investigate the value of CT perfusion imaging in evaluating tumor angiogenesis. Material and methods: Twenty-four cases of rabbit VX2 liver tumor were performed by CT perfusion scanning. Hepatic artery perfusion (HAP), portal vein perfusion (PVP), total hepatic blood flow (THBF) and hepatic perfusion index (HPI) were measured by perfusion software. HIF-1α, VEGF and MMP-2 expression and MVD were detected in the 24 rabbit VX2 liver tumor tissue samples using immunohistochemical method. The correlation between the HIF-1α, VEGF, MMP-2 expression and MVD and CT perfusion parameters were analyzed. Results: Correlation analysis revealed that the expression of HIF-1α, MMP-2, MVD were positively related to the HAP, THBF, HPI (p < 0.01), but no relations with PVP (p > 0.05);and correlation analysis revealed that the expression of VEGF was positively related to the HAP, HPI (p 0.05). There was a positive relationship between the expression of HIF-1α, VEGF, MMP-2 and MVD (p < 0.01). Conclusions: CT perfusion imaging can reflect the blood perfusion of the rabbit VX2 liver tumors and evaluate the information of angiogenesis about tumors.展开更多
ChatG PT,an artificial intelligence generated content (AIGC) model developed by OpenAI,has attracted worldwide attention for its capability of dealing with challenging language understanding and generation tasks in th...ChatG PT,an artificial intelligence generated content (AIGC) model developed by OpenAI,has attracted worldwide attention for its capability of dealing with challenging language understanding and generation tasks in the form of conversations.This paper briefly provides an overview on the history,status quo and potential future development of ChatGPT,helping to provide an entry point to think about ChatGPT.Specifically,from the limited open-accessed resources,we conclude the core techniques of ChatGPT,mainly including large-scale language models,in-context learning,reinforcement learning from human feedback and the key technical steps for developing ChatGPT.We further analyze the pros and cons of ChatGPT and we rethink the duality of ChatGPT in various fields.Although it has been widely acknowledged that ChatGPT brings plenty of opportunities for various fields,mankind should still treat and use ChatG PT properly to avoid the potential threat,e.g.,academic integrity and safety challenge.Finally,we discuss several open problems as the potential development of ChatGPT.展开更多
Hepatic myelopathy is a complication seen in patients with chronic liver failure with physiologic or iatrogenic portosystemic shunting. The main symptom is progressive lower limb dyskinesia. The role of the brain moto...Hepatic myelopathy is a complication seen in patients with chronic liver failure with physiologic or iatrogenic portosystemic shunting. The main symptom is progressive lower limb dyskinesia. The role of the brain motor control center in hepatic myelopathy is unknown. This study aimed to investigate the gray matter changes in patients with hepatic myelopathy secondary to transjugular intrahepatic portosystemic shunt and to examine their clinical relevance. This was a cross-sectional study. Twenty-three liver failure patients with hepatic myelopathy(hepatic myelopathy group), 23 liver failure patients without hepatic myelopathy(non-hepatic myelopathy group) after transjugular intrahepatic portosystemic shunt, and 23 demographically matched healthy volunteers were enrolled from March 2014 to November 2016 at Xijing Hospital, Air Force Military Medical University(Fourth Military Medical University), China. High-resolution magnetization-prepared rapid gradient-echo brain imaging was acquired. Group differences in regional gray matter were assessed using voxel-based morphometry analysis. The relationship between aberrant gray matter and motor characteristics was investigated. Results demonstrated that compared with the non-hepatic myelopathy group, gray matter volume abnormalities were asymmetric, with decreased volume in the left insula(P = 0.003), left thalamus(P = 0.029), left superior frontal gyrus(P = 0.006), and right middle cingulate cortex(P = 0.021), and increased volume in the right caudate nucleus(P = 0.017), corrected with open-source software. The volume of the right caudate nucleus in the hepatic myelopathy group negatively correlated with the lower limb clinical rating of the Fugl-Meyer Assessment(r = –0.53, P = 0.01). Compared with healthy controls, patients with and without hepatic myelopathy exhibited overall increased gray matter volume in both thalami, and decreased gray matter volume in both putamen, as well as in the globus pallidus, cerebellum, and vermis. The gray matter abnormalities we found predominantly involved motor-related regions, and may be associated with motor dysfunction. An enlarged right caudate nucleus might help to predict weak lower limb motor performance in patients with preclinical hepatic myelopathy after transjugular intrahepatic portosystemic shunt. This study was approved by the Ethics Committee of Xijing Hospital, Air Force Military Medical University(Fourth Military Medical University), China(approval No. 20140227-6) on February 27, 2014.展开更多
碱性析氢反应(HER)可将间歇性可再生能源转化为可存储的清洁能源,因而备受关注.然而,水解离速度缓慢以及H中间体(*H)吸附和解吸困难限制了碱性HER的进一步发展.目前,针对碱性电解水解离缓慢问题,通常采用调整电催化剂结构降低水分解热...碱性析氢反应(HER)可将间歇性可再生能源转化为可存储的清洁能源,因而备受关注.然而,水解离速度缓慢以及H中间体(*H)吸附和解吸困难限制了碱性HER的进一步发展.目前,针对碱性电解水解离缓慢问题,通常采用调整电催化剂结构降低水分解热动力学能垒,以及改变三相界面微环境加速中间产物的扩散等方法来促进水分解进行.此外,可以通过调控活性位点电子结构来优化*H的吸脱附.但是采用单一的策略很难同时促进H_(2)O的解离和*H的吸脱附,难以获得令人满意的碱性HER性能.因此,探索一种能同时促进H_(2)O的解离和*H的吸脱附协同策略对提升碱性HER的性能至关重要.本文提出了一种协同策略,通过构建高曲率二硫化钴纳米针(CoS_(2)NNs)和原子级铜(Cu)的掺杂分别实现诱导纳米尺度的局域电场和原子尺度的电子局域化,从而促进碱性HER的H_(2)O解离和*H吸脱附.首先,采用有限元法模拟和密度泛函理论计算,从理论上分别证实了纳米尺度局域电场可以加速H_(2)O解离以及原子尺度电子局域化可以促进*H吸附.受理论计算结果启发,通过一步水热法和原位硫化相结合的方法制备了高曲率的Cu掺杂CoS_(2)纳米针(Cu-CoS_(2)NNs).采用扫描电镜(SEM)、透射电镜(TEM)、X射线衍射(XRD)和四探针测试等技术进行表征,研究了Cu-CoS_(2)NNs的形貌、物相结构、化学组成和导电性.结果表明,在Cu原子引入后,Cu-CoS_(2)NNs依然保持着高曲率的纳米针结构,证明了Cu在CoS_(2)NNs中的原子分散状态.相较于低曲率的Cu掺杂CoS_(2)纳米线(Cu-CoS_(2)NWs),Cu-CoS_(2)NNs只存在形貌上的区别,二者的化学组成和比例均非常接近.同时,上述材料都具有很强的导电性,且电导率基本相同,这与有限元模拟结果一致.原位衰减全反射红外光谱和电响应测试结果表明,Cu-CoS_(2)NNs具有较好的解离H_(2)O和吸附*H的能力.在1 mol L^(-1)KOH溶液和10 mA cm^(-2)电流密度下,该催化剂的析氢过电位仅为64 mV,展现出较好的电化学析氢性能.催化剂还表现出非常好的碱性析氢稳定性,在标准氢电势(RHE)-0.18 V下,可在100 mA cm^(-2)电流密度下稳定工作达100 h.综上所述,本文通过诱导局域电场和电子局域化构建了一种协同策略,所制备的Cu-CoS_(2)NNs表现出很好的催化碱性HER性能和应用前景,为碱性HER电催化剂的理性设计提供了一定的参考.展开更多
To examine the feasibility of using a computer tool for stratifying the severity of Coronavirus Disease 2019(COVID-19)based on computed tomography(CT)images.We retrospectively examined 44 confirmed COVID-19 cases.All ...To examine the feasibility of using a computer tool for stratifying the severity of Coronavirus Disease 2019(COVID-19)based on computed tomography(CT)images.We retrospectively examined 44 confirmed COVID-19 cases.All cases were evaluated separately by radiologists(visually)and through an in-house computer software.The degree of lesions was visually scored by the radiologist,as follows,for each of the 5 lung lobes:0,no lesion present;1,<1/3 involvement;2,>1/3 and<2/3 involvement;and 3,>2/3 involvement.Lesion density was assessed based on the proportion of ground-glass opacity(GGO),consolidation and fibrosis of the lesions.The parameters obtained using the computer tool included lung volume(mL),lesion volume(mL),lesion percentage(%),and mean lesion density(HU)of the whole lung,right lung,left lung,and each lobe.The scores obtained by the radiologists and quantitative results generated by the computer software were tested for correlation.A Chi-square test was used to test the consistency of radiologist-and computer-derived lesion percentage in the right/left lung,upper/lower lobe,and each of the 5 lobes.The results showed a strong to moderate correlation between lesion percentage scores obtained by radiologists and the computer software(r ranged from 0.7679 to 0.8373,P<0.05),and a moderate correlation between the proportion of GGO and mean lesion density(r=-0.5894,P<0.05),and proportion of consolidation and mean lesion density(r=0.6282,P<0.05).Computer-aided quantification showed a statistical significant higher lesion percentage for lower lobes than that assessed by the radiologists(x^2=8.160,P=0.004).Our experiments demonstrated that the computer tool could reliably and accurately assess the severity and distribution of pneumonia on CT scans.展开更多
The size of underground openings in rock masses in metal mines is critical to the performance of the openings. In this study, the mechanical and acoustic emission (AE) characteristics of brittle rock-like specimens co...The size of underground openings in rock masses in metal mines is critical to the performance of the openings. In this study, the mechanical and acoustic emission (AE) characteristics of brittle rock-like specimens containing a circular opening with different ratios of opening diameter to sample size λ (λ = 0.1, 0.13, 0.17, 0.2, and 0.23) were investigated under uniaxial compression with AE monitoring. The results indicate that the opening size strongly affected the peak strength and the elastic modulus. Crack initiation first started from the upper surface of the specimens, not from the periphery of the openings. Tensile and shear cracks coexisted on the roof and floor of the specimens, whereas tensile cracks were dominant on the two sides. The fracture mode of samples with openings was partially affected by the relative size of the pillars and openings. The AE response curves (in terms of counts, cumulative energy, cumulative counts, and b-value) show that brittle failure was mainly a progressive process. Moreover, the AE information corresponded well with microcrack evolution in the samples and thus can be used to predict sample failure.展开更多
The occurrence of coal-bearing strata in a variety of coal-bearing basins of China is characterized by late tectonic deformation and remarkable spatial and geochronologic differences.The main controlling factors,which...The occurrence of coal-bearing strata in a variety of coal-bearing basins of China is characterized by late tectonic deformation and remarkable spatial and geochronologic differences.The main controlling factors,which determine the tectonic framework of coalfields,include the geodynamic environment,tectonic evolution,deep structures,tectonic stress,and lithologic combination of the coal measures.The Chinese continent has experienced multi-stage tectonic movements since the Late Paleozoic.The spatial and temporal heterogeneity of its continental tectonic evolution,the complexity of its basement properties,and its stratigraphic configurations control the tectonic framework of its coalfields’present complex and orderly patterns.The concept of coal occurrence structural units is proposed in this paper and is defined as the structural zoning of coal occurrence.China’s coalfields are divided into five coal occurrence structural areas,and the structural characteristics of the coalfields in five main coal occurrence areas throughout the country are summarized.Based on the analysis of the relationship between the structure characteristics and occurrence of coal in these coalfields,the coal-controlling structures are divided into six groups:extensional structural styles,compressional structural styles,shearing and rotational structural styles,inverted structural styles,sliding structural styles,and syn-depositional structural styles.In addition,the distribution of coal-controlling structural styles is briefly summarized in this paper.展开更多
Transition metal sulfides are an important category for hydrogen evolution reaction(HER).However,only few edge unsaturated sulfurs functionalize as catalytic sites,which has dramatically limited the catalytic activity...Transition metal sulfides are an important category for hydrogen evolution reaction(HER).However,only few edge unsaturated sulfurs functionalize as catalytic sites,which has dramatically limited the catalytic activity and stability.In this work,planar unsaturated sulfurs in(211)plane of the CoS_(2)nanowires have been successfully activated through constructing Graphdiyne-CoS_(2)heterojunction nanocomposites.The corresponding electrons transfer energy barriers for these planar unsaturated sulfurs have been significantly diminished,which are induced by the synergetic effects of the sp~1 hybridized carbons and unsaturated planar sulfurs.In addition,DFT simulations reveal the synergetic effects of the sp~1 hybridized carbons and unsaturated planar sulfurs can promote electron transfer kinetics of the key step,VolmerHeyrovsky step,of the reaction.As expected,the Graphdiyne-CoS_(2)heterojunction nanocomposites exhibit superior HER catalytic performance with low overpotential of 97 mV at 10 mA cm^(-2),and the Tafel slope of 56 mV dec^(-1).Furthermore,the heterojunction shows outstanding stability as well due to the pr tection of the Graphdiyne(GDY).The approach thus paves the way for the further efficient transition metal disulfides catalyst manufactures.展开更多
The rare earth elements(REE)content of the coal in the Erlian Basin was determined by inductively coupled plasma mass spectrometry(ICP-MS),and it turns out that the REE content from different geological age shows a si...The rare earth elements(REE)content of the coal in the Erlian Basin was determined by inductively coupled plasma mass spectrometry(ICP-MS),and it turns out that the REE content from different geological age shows a significant difference:The REE content of the coal in the Jurassic Alatanheli Group is from 152.05×10^(−6) to 1416.21×10^(−6),with an average value of 397.31×10^(−6),and the relative concentration factor shows enriched;the REE content of the coal in Early Cretaceous Baiyanhua Group is from 20.65×10^(−6) to 102.53×10^(−6),the mean value is 49.06×10^(−6),and the relative concentration factor shows normally.The REE distribution patterns samples in Jurassic and Cretaceous shows the difference:The REE pattern in Jurassic coal mainly manifests as H-type distribution,with the Y,Lu positive anomaly,it is speculated that the fluid carried REE ions into the coal-bearing basin,and the heavy REE gather in the coal due to the different chemical properties of each REE.The REE occurrence mode is presumed to be mainly organic.Flat type is the REE main distribution pattern in Cretaceous coal.The REE patterns in clastic rocks of the roof,parting and floor of coal seam are similar to the REE patterns in the coal and the most possible reason is that the REE main source is from the clastic rock.It showed that the coal of the Early Jurassic,especially of Amugulen coalfield has resource value.展开更多
Copper (Cu) is a special electrocatalyst for CO_(2) reduction reaction (CO_(2)RR) to multi-carbon products.Experimentally introducing grain boundaries (GBs) into Cu-based catalysts is an efficient strategy to improve ...Copper (Cu) is a special electrocatalyst for CO_(2) reduction reaction (CO_(2)RR) to multi-carbon products.Experimentally introducing grain boundaries (GBs) into Cu-based catalysts is an efficient strategy to improve the selectivity of C^(2+) products.However,it is still elusive for the C^(2+) product generation on Cu GBs due to the complex active sites.In this work,we found that the tandem catalysis pathway on adjacent active motifs of Cu GB is responsible for the enhanced activity for C^(2+)production by first principles calculations.By electronic structure analysis shows,the d-band center of GB site is close to the Fermi level than Cu(100) facet,the Cu atomic sites at grain boundary have shorter bond length and stronger bonding with*CO,which can enhance the adsorption of*CO at GB sites.Moreover,CO_(2)protonation is more favorable on the region Ⅲ motif (0.84 e V) than at Cu(100) site (1.35 e V).Meanwhile,the region Ⅱ motif also facilitate the C–C coupling (0.72 e V) compared to the Cu(100) motif (1.09 e V).Therefore,the region Ⅲ and Ⅱ motifs form a tandem catalysis pathway,which promotes the C^(2+)selectivity on Cu GBs.This work provides new insights into CO_(2)RR process.展开更多
文摘利用可再生电力将二氧化碳转化为高附加值产品的电催化二氧化碳还原反应(CO_(2)RR)是一项具有革命性潜力的技术,因而备受关注.其中,一氧化碳被视为CO_(2)RR中最具经济效益的产物之一,可直接利用费托合成工艺将其用于合成醛、酮、烃类等产品.酞菁钴(CoPc)作为单位点催化剂,因其高原子利用率和高催化选择性能,在二氧化碳转化为一氧化碳过程中具有很大优势.然而,CoPc无法为CO_(2)RR中的质子化过程提供足够质子,导致其在工业大电流密度下的效率较低.因此,探索一种能够解决CO_(2)RR中质子供给不足问题的高效电催化剂对于提升CO_(2)RR的性能至关重要.本文设计了具有增强质子供给作用的缺陷碳纳米管(d-CNT),将其作为导电载体分散CoPc,用于制备CoPc/d-CNT电催化剂.通过引入富缺陷的碳纳米管(d-CNT),加速水解离进而增加CO_(2)RR的质子供给量.X射线光电子能谱、X射线吸收近边光谱和扩展X射线吸收精细结构谱结果表明,CoPc/d-CNT成功合成,同时保留了CoPc完整的Co-N4配位结构.透射电镜、粉末X射线衍射谱和拉曼光谱共同表明,d-CNT表面缺陷相对于商用CNT明显增加.动力学实验和原位衰减全反射表面增强红外吸收光谱研究表明,含大量缺陷的d-CNT具有加速水解离的能力,显著提高了二氧化碳还原反应过程中的质子供给,从而促进了CoPc_上CO_(2)活化生成*COOH.同时,密度泛函理论计算结果表明,d-CNT表面缺陷位点上从吸附水(*H2O)到质子水(H3O+)的吉布斯自由能为0.74 eV,远低于CNT(超过2 eV),表明d-CNT促进了水解过程和质子传递,再次证实了d-CNT降低了水分子解离的势垒.通过实验和理论的共同验证,阐明了d-CNT中的缺陷能够促进水解离,改善CO_(2)RR反应过程中质子供给,增强CoPc高效催化CO_(2)RR的能力.因此,CoPc/d-CNT混合材料表现出较好的催化性能.在电流密度为500 mA cm^(-2)的流动电池中,CoPc/d-CNT的CO法拉第效率(FECO)高达96%.相对而言,CoPc/CNT在200 mA cm^(-2)时FECO已经下降到90%以下.此外,在150 mA cm^(-2)的电流密度下,CoPc/d-CNT能够在20 h内维持FECO超过90%.综上,本文通过引入具有水解离能力的缺陷碳位点,解决了单位点催化剂CoPc在CO_(2)RR中质子供给不足的问题,为设计高性能催化剂提供了新见解.
文摘近年来,具有独特电子效应和协同效应的异质界面工程策略在扩展催化功能和提高本征活性方面显示出较大的应用潜力.其中,具有晶型/无定形(c/a)异质结构的电催化剂,由于结构上的巨大差异,展现出显著的催化活性.然而,c/a-异质界面的可控调控及其与电催化性能的内在联系仍缺乏系统研究.因此,本文采用“酸刻蚀-气相磷硫化-淬火”方法,合成了具有可调控c/a异质界面的q-CoPS材料,并将其应用于碱性整体水分解.同时,通过控制淬火的初始温度,实现了对CoPS纳米棒中c/a比例的有效调控.一般来说,在晶型材料中,表面催化往往发生在固定的晶面上.而无定形材料可以同时满足体积和表面的催化.同时,无定形材料具有柔韧性,在催化反应过程中可以转化为任何需要的其他形式,因此在耐腐蚀方面也具有较好的自愈性能.此外,无定形材料还具有丰富的缺陷,运用缺陷工程可以带来一定的性能提升.因此,二者的协同作用可以提升催化剂的催化性能.本文创新性地提出了通过改变淬火初始温度对CoPS纳米棒中c/a比进行调控.采用“酸刻蚀-气相磷硫化-淬火”方法,成功制备了具有独特c/a-CoPS核壳异质结构的q-CoPS纳米棒.随着淬火初始温度的升高,无定形CoPS壳的面积也在逐渐增大.这可能是由于处于非平衡状态的磷硫化物在超低温液氮中突然淬火,处于热运动的Co,P和S原子会迅速冷却,趋向于形成无序的CoPS无定形材料.值得注意的是,制备得到的q-CoPS纳米棒具有合适的c/a含量比,提供了丰富的c/a界面活性位点,并优化了Co位点的电子构型.在析氢反应(HER)中,q-CoPS/CF仅需90 m V的过电位即可以达到1000 m Acm^(-2)的工业级电流密度,结果优于先进的Pt/C.同时,q-CoPS/CF在肼氧化反应(HzOR)中,仅0.06 V时即可实现1000 m Acm^(-2)的电流密度.密度泛函理论计算表明,在HER和HzOR中,界面处的Co原子的内在活性远高于P原子和S原子,c/a-异质界面处活性位点的能垒远低于晶型CoPS和无定形CoPS.此外,Co位点作为c/a界面的双功能活性位点,有效地优化了HER和HzOR的反应动力学.综上所述,q-CoPS/CF催化剂电催化性能的提升主要是由于其具备高活性的CoPS、合适的晶型/无定形(c/a)比例和较大的比表面积.本文为设计具有c/a异质结构的高活性电极提供参考,为进一步探索c/a异质结构的演化和确定c/a界面的活性位点提供借鉴.
基金supported by the National Natural Science Foundation of China(No.12150006)Shanghai Pilot Program for Basic Research-Shanghai Jiao Tong University(No.21TQ1400209)the Young Talents of National Talent Support Programs(No.24Z130300579).
文摘The DarkSHINE experiment proposes a novel approach to single-electron-on-fixed-target exploration that focuses on the search for dark photons through their invisible decay into dark matter particles.Central to this initiative is an advanced tracking detector designed to achieve exceptional sensitivity in the detection of light dark matter candidates.This study evaluates the performance of several prototype AC-coupled low-gain avalanche diode(AC-LGAD)strip sensors specifically developed for the DarkSHINE tracking detector.The electrical properties of the sensors from two batches of wafers with different n^(+)doses are thoroughly evaluated.Spatial and temporal resolutions are measured using an infrared laser source.The spatial resolutions range from 6.5 to 8.2μm and from 8.8 to 12.3μm for the sensors from two distinct dose batches,each with a 100μm pitch size.Furthermore,the sensors demonstrate time resolutions of 8.3 and 11.4 ps,underscoring the potential of AC-LGAD technology in enhancing the performance of the DarkSHINE tracking detector.
基金the Science and Technology Development Plan Project of Jilin Province,China(Grant No.20220204134YY)the National Natural Science Foundation of China(Grant No.62301140)+3 种基金Project of the Education Department of Jilin Province(Grant Nos.JJKH20231292KJ and JJKH20240242KJ)Program for Science and Technology Development of Changchun City(Grant No.23YQ11)Innovation and Entrepreneurship Talent Funding Project of Jilin Province(Grant No.2023RY17)the Project of Jilin Provincial Development and Reform Commission(Grant No.2023C042-4).
文摘Improving the speed of ghost imaging is one of the main ways to leverage its advantages in sensitivity and imperfect spectral regions for practical applications.Because of the proportional relationship between image resolution and measurement time,when the image pixels are large,the measurement time increases,making it difficult to achieve real-time imaging.Therefore,a high-quality ghost imaging method based on undersampled natural-order Hadamard is proposed.This method uses the characteristics of the Hadamard matrix under undersampling conditions where image information can be fully obtained but overlaps,as well as deep learning to extract aliasing information from the overlapping results to obtain the true original image information.We conducted numerical simulations and experimental tests on binary and grayscale objects under undersampling conditions to demonstrate the effectiveness and scalability of this method.This method can significantly reduce the number of measurements required to obtain high-quality image information and advance application promotion.
文摘Objective: The purpose of this study was to evaluate the correlation between CT perfusion parameters and the hypoxia-inducible factor-1 alpha (HIF-1α), vascular en-dothelial growth factor (VEGF), matrix metalloproteinase-2 (MMP-2) and microvessel density (MVD) marked by CD34 molecular of rabbit VX2 liver tumors and to investigate the value of CT perfusion imaging in evaluating tumor angiogenesis. Material and methods: Twenty-four cases of rabbit VX2 liver tumor were performed by CT perfusion scanning. Hepatic artery perfusion (HAP), portal vein perfusion (PVP), total hepatic blood flow (THBF) and hepatic perfusion index (HPI) were measured by perfusion software. HIF-1α, VEGF and MMP-2 expression and MVD were detected in the 24 rabbit VX2 liver tumor tissue samples using immunohistochemical method. The correlation between the HIF-1α, VEGF, MMP-2 expression and MVD and CT perfusion parameters were analyzed. Results: Correlation analysis revealed that the expression of HIF-1α, MMP-2, MVD were positively related to the HAP, THBF, HPI (p < 0.01), but no relations with PVP (p > 0.05);and correlation analysis revealed that the expression of VEGF was positively related to the HAP, HPI (p 0.05). There was a positive relationship between the expression of HIF-1α, VEGF, MMP-2 and MVD (p < 0.01). Conclusions: CT perfusion imaging can reflect the blood perfusion of the rabbit VX2 liver tumors and evaluate the information of angiogenesis about tumors.
基金supported by National Key Research and Development Program of China (2021YFB1714300)National Natural Science Foundation of China (62293502, 61831022, 61976211)Youth Innovation Promotion Association CAS。
文摘ChatG PT,an artificial intelligence generated content (AIGC) model developed by OpenAI,has attracted worldwide attention for its capability of dealing with challenging language understanding and generation tasks in the form of conversations.This paper briefly provides an overview on the history,status quo and potential future development of ChatGPT,helping to provide an entry point to think about ChatGPT.Specifically,from the limited open-accessed resources,we conclude the core techniques of ChatGPT,mainly including large-scale language models,in-context learning,reinforcement learning from human feedback and the key technical steps for developing ChatGPT.We further analyze the pros and cons of ChatGPT and we rethink the duality of ChatGPT in various fields.Although it has been widely acknowledged that ChatGPT brings plenty of opportunities for various fields,mankind should still treat and use ChatG PT properly to avoid the potential threat,e.g.,academic integrity and safety challenge.Finally,we discuss several open problems as the potential development of ChatGPT.
文摘Hepatic myelopathy is a complication seen in patients with chronic liver failure with physiologic or iatrogenic portosystemic shunting. The main symptom is progressive lower limb dyskinesia. The role of the brain motor control center in hepatic myelopathy is unknown. This study aimed to investigate the gray matter changes in patients with hepatic myelopathy secondary to transjugular intrahepatic portosystemic shunt and to examine their clinical relevance. This was a cross-sectional study. Twenty-three liver failure patients with hepatic myelopathy(hepatic myelopathy group), 23 liver failure patients without hepatic myelopathy(non-hepatic myelopathy group) after transjugular intrahepatic portosystemic shunt, and 23 demographically matched healthy volunteers were enrolled from March 2014 to November 2016 at Xijing Hospital, Air Force Military Medical University(Fourth Military Medical University), China. High-resolution magnetization-prepared rapid gradient-echo brain imaging was acquired. Group differences in regional gray matter were assessed using voxel-based morphometry analysis. The relationship between aberrant gray matter and motor characteristics was investigated. Results demonstrated that compared with the non-hepatic myelopathy group, gray matter volume abnormalities were asymmetric, with decreased volume in the left insula(P = 0.003), left thalamus(P = 0.029), left superior frontal gyrus(P = 0.006), and right middle cingulate cortex(P = 0.021), and increased volume in the right caudate nucleus(P = 0.017), corrected with open-source software. The volume of the right caudate nucleus in the hepatic myelopathy group negatively correlated with the lower limb clinical rating of the Fugl-Meyer Assessment(r = –0.53, P = 0.01). Compared with healthy controls, patients with and without hepatic myelopathy exhibited overall increased gray matter volume in both thalami, and decreased gray matter volume in both putamen, as well as in the globus pallidus, cerebellum, and vermis. The gray matter abnormalities we found predominantly involved motor-related regions, and may be associated with motor dysfunction. An enlarged right caudate nucleus might help to predict weak lower limb motor performance in patients with preclinical hepatic myelopathy after transjugular intrahepatic portosystemic shunt. This study was approved by the Ethics Committee of Xijing Hospital, Air Force Military Medical University(Fourth Military Medical University), China(approval No. 20140227-6) on February 27, 2014.
文摘碱性析氢反应(HER)可将间歇性可再生能源转化为可存储的清洁能源,因而备受关注.然而,水解离速度缓慢以及H中间体(*H)吸附和解吸困难限制了碱性HER的进一步发展.目前,针对碱性电解水解离缓慢问题,通常采用调整电催化剂结构降低水分解热动力学能垒,以及改变三相界面微环境加速中间产物的扩散等方法来促进水分解进行.此外,可以通过调控活性位点电子结构来优化*H的吸脱附.但是采用单一的策略很难同时促进H_(2)O的解离和*H的吸脱附,难以获得令人满意的碱性HER性能.因此,探索一种能同时促进H_(2)O的解离和*H的吸脱附协同策略对提升碱性HER的性能至关重要.本文提出了一种协同策略,通过构建高曲率二硫化钴纳米针(CoS_(2)NNs)和原子级铜(Cu)的掺杂分别实现诱导纳米尺度的局域电场和原子尺度的电子局域化,从而促进碱性HER的H_(2)O解离和*H吸脱附.首先,采用有限元法模拟和密度泛函理论计算,从理论上分别证实了纳米尺度局域电场可以加速H_(2)O解离以及原子尺度电子局域化可以促进*H吸附.受理论计算结果启发,通过一步水热法和原位硫化相结合的方法制备了高曲率的Cu掺杂CoS_(2)纳米针(Cu-CoS_(2)NNs).采用扫描电镜(SEM)、透射电镜(TEM)、X射线衍射(XRD)和四探针测试等技术进行表征,研究了Cu-CoS_(2)NNs的形貌、物相结构、化学组成和导电性.结果表明,在Cu原子引入后,Cu-CoS_(2)NNs依然保持着高曲率的纳米针结构,证明了Cu在CoS_(2)NNs中的原子分散状态.相较于低曲率的Cu掺杂CoS_(2)纳米线(Cu-CoS_(2)NWs),Cu-CoS_(2)NNs只存在形貌上的区别,二者的化学组成和比例均非常接近.同时,上述材料都具有很强的导电性,且电导率基本相同,这与有限元模拟结果一致.原位衰减全反射红外光谱和电响应测试结果表明,Cu-CoS_(2)NNs具有较好的解离H_(2)O和吸附*H的能力.在1 mol L^(-1)KOH溶液和10 mA cm^(-2)电流密度下,该催化剂的析氢过电位仅为64 mV,展现出较好的电化学析氢性能.催化剂还表现出非常好的碱性析氢稳定性,在标准氢电势(RHE)-0.18 V下,可在100 mA cm^(-2)电流密度下稳定工作达100 h.综上所述,本文通过诱导局域电场和电子局域化构建了一种协同策略,所制备的Cu-CoS_(2)NNs表现出很好的催化碱性HER性能和应用前景,为碱性HER电催化剂的理性设计提供了一定的参考.
基金supported by the Science and Technology Project of Shaanxi Province(No.2018SF-264)The National Natural Science Foundation of China(81701691)Natural and Science Foundation of Shaanxi Province(2019JM-361)。
文摘To examine the feasibility of using a computer tool for stratifying the severity of Coronavirus Disease 2019(COVID-19)based on computed tomography(CT)images.We retrospectively examined 44 confirmed COVID-19 cases.All cases were evaluated separately by radiologists(visually)and through an in-house computer software.The degree of lesions was visually scored by the radiologist,as follows,for each of the 5 lung lobes:0,no lesion present;1,<1/3 involvement;2,>1/3 and<2/3 involvement;and 3,>2/3 involvement.Lesion density was assessed based on the proportion of ground-glass opacity(GGO),consolidation and fibrosis of the lesions.The parameters obtained using the computer tool included lung volume(mL),lesion volume(mL),lesion percentage(%),and mean lesion density(HU)of the whole lung,right lung,left lung,and each lobe.The scores obtained by the radiologists and quantitative results generated by the computer software were tested for correlation.A Chi-square test was used to test the consistency of radiologist-and computer-derived lesion percentage in the right/left lung,upper/lower lobe,and each of the 5 lobes.The results showed a strong to moderate correlation between lesion percentage scores obtained by radiologists and the computer software(r ranged from 0.7679 to 0.8373,P<0.05),and a moderate correlation between the proportion of GGO and mean lesion density(r=-0.5894,P<0.05),and proportion of consolidation and mean lesion density(r=0.6282,P<0.05).Computer-aided quantification showed a statistical significant higher lesion percentage for lower lobes than that assessed by the radiologists(x^2=8.160,P=0.004).Our experiments demonstrated that the computer tool could reliably and accurately assess the severity and distribution of pneumonia on CT scans.
基金financially supported by the National Natural Science Foundation of China (No. 51774022)the State Key Research Development Program of China (No. 2016YFC0600801)+1 种基金the Beijing Natural Science Foundation (No. 2184108)the China Postdoctoral Science Foundation (No. 2017M620620)
文摘The size of underground openings in rock masses in metal mines is critical to the performance of the openings. In this study, the mechanical and acoustic emission (AE) characteristics of brittle rock-like specimens containing a circular opening with different ratios of opening diameter to sample size λ (λ = 0.1, 0.13, 0.17, 0.2, and 0.23) were investigated under uniaxial compression with AE monitoring. The results indicate that the opening size strongly affected the peak strength and the elastic modulus. Crack initiation first started from the upper surface of the specimens, not from the periphery of the openings. Tensile and shear cracks coexisted on the roof and floor of the specimens, whereas tensile cracks were dominant on the two sides. The fracture mode of samples with openings was partially affected by the relative size of the pillars and openings. The AE response curves (in terms of counts, cumulative energy, cumulative counts, and b-value) show that brittle failure was mainly a progressive process. Moreover, the AE information corresponded well with microcrack evolution in the samples and thus can be used to predict sample failure.
基金This study was financially supported by the Geological Survey Project of China Geological Survey National Potential Evaluation of Coal Resources project(121211121043)the National Natural Science Foundation of China(41572141,41772156).
文摘The occurrence of coal-bearing strata in a variety of coal-bearing basins of China is characterized by late tectonic deformation and remarkable spatial and geochronologic differences.The main controlling factors,which determine the tectonic framework of coalfields,include the geodynamic environment,tectonic evolution,deep structures,tectonic stress,and lithologic combination of the coal measures.The Chinese continent has experienced multi-stage tectonic movements since the Late Paleozoic.The spatial and temporal heterogeneity of its continental tectonic evolution,the complexity of its basement properties,and its stratigraphic configurations control the tectonic framework of its coalfields’present complex and orderly patterns.The concept of coal occurrence structural units is proposed in this paper and is defined as the structural zoning of coal occurrence.China’s coalfields are divided into five coal occurrence structural areas,and the structural characteristics of the coalfields in five main coal occurrence areas throughout the country are summarized.Based on the analysis of the relationship between the structure characteristics and occurrence of coal in these coalfields,the coal-controlling structures are divided into six groups:extensional structural styles,compressional structural styles,shearing and rotational structural styles,inverted structural styles,sliding structural styles,and syn-depositional structural styles.In addition,the distribution of coal-controlling structural styles is briefly summarized in this paper.
基金financially supported by the National Natural Science Foundation of China(No.51972175)the Natural Science Foundation of Tianjin(17JCYBJC40900,18YFZCGX00580)+3 种基金The National Natural Science Foundation of China(Grant No.21872174 and U1932148)the International S&T Cooperation Program of China(2017YFE0127800)the Hundred Youth Talents Program of Hunan.National Natural Science Foundation of China(No.21601171)the Natural Science Foundation of Shandong Province(No.ZR2016BB08)。
文摘Transition metal sulfides are an important category for hydrogen evolution reaction(HER).However,only few edge unsaturated sulfurs functionalize as catalytic sites,which has dramatically limited the catalytic activity and stability.In this work,planar unsaturated sulfurs in(211)plane of the CoS_(2)nanowires have been successfully activated through constructing Graphdiyne-CoS_(2)heterojunction nanocomposites.The corresponding electrons transfer energy barriers for these planar unsaturated sulfurs have been significantly diminished,which are induced by the synergetic effects of the sp~1 hybridized carbons and unsaturated planar sulfurs.In addition,DFT simulations reveal the synergetic effects of the sp~1 hybridized carbons and unsaturated planar sulfurs can promote electron transfer kinetics of the key step,VolmerHeyrovsky step,of the reaction.As expected,the Graphdiyne-CoS_(2)heterojunction nanocomposites exhibit superior HER catalytic performance with low overpotential of 97 mV at 10 mA cm^(-2),and the Tafel slope of 56 mV dec^(-1).Furthermore,the heterojunction shows outstanding stability as well due to the pr tection of the Graphdiyne(GDY).The approach thus paves the way for the further efficient transition metal disulfides catalyst manufactures.
基金This study was supported by the project of the China Geological Survey(DD20160187)the Science and Technology Special Project of the China National Administration of Coal Geology(ZMKJ-2019-J02).
文摘The rare earth elements(REE)content of the coal in the Erlian Basin was determined by inductively coupled plasma mass spectrometry(ICP-MS),and it turns out that the REE content from different geological age shows a significant difference:The REE content of the coal in the Jurassic Alatanheli Group is from 152.05×10^(−6) to 1416.21×10^(−6),with an average value of 397.31×10^(−6),and the relative concentration factor shows enriched;the REE content of the coal in Early Cretaceous Baiyanhua Group is from 20.65×10^(−6) to 102.53×10^(−6),the mean value is 49.06×10^(−6),and the relative concentration factor shows normally.The REE distribution patterns samples in Jurassic and Cretaceous shows the difference:The REE pattern in Jurassic coal mainly manifests as H-type distribution,with the Y,Lu positive anomaly,it is speculated that the fluid carried REE ions into the coal-bearing basin,and the heavy REE gather in the coal due to the different chemical properties of each REE.The REE occurrence mode is presumed to be mainly organic.Flat type is the REE main distribution pattern in Cretaceous coal.The REE patterns in clastic rocks of the roof,parting and floor of coal seam are similar to the REE patterns in the coal and the most possible reason is that the REE main source is from the clastic rock.It showed that the coal of the Early Jurassic,especially of Amugulen coalfield has resource value.
基金the National Natural Science Foundation of China(21872174,22002189,U1932148)the International Science and Technology Cooperation Program(2017YFE0127800,2018YFE0203402)+5 种基金the Hunan Provincial Science and Technology Program(2017XK2026)the Hunan Province Key Field R&D Program(2020WK2002)the Hunan Provincial Natural Science Foundation of China(2020JJ2041,2020JJ5691)the Shenzhen Science and Technology Innovation Project(JCYJ20180307151313532)the Fundamental Research Funds for the Central Universities of Central South University。
文摘Copper (Cu) is a special electrocatalyst for CO_(2) reduction reaction (CO_(2)RR) to multi-carbon products.Experimentally introducing grain boundaries (GBs) into Cu-based catalysts is an efficient strategy to improve the selectivity of C^(2+) products.However,it is still elusive for the C^(2+) product generation on Cu GBs due to the complex active sites.In this work,we found that the tandem catalysis pathway on adjacent active motifs of Cu GB is responsible for the enhanced activity for C^(2+)production by first principles calculations.By electronic structure analysis shows,the d-band center of GB site is close to the Fermi level than Cu(100) facet,the Cu atomic sites at grain boundary have shorter bond length and stronger bonding with*CO,which can enhance the adsorption of*CO at GB sites.Moreover,CO_(2)protonation is more favorable on the region Ⅲ motif (0.84 e V) than at Cu(100) site (1.35 e V).Meanwhile,the region Ⅱ motif also facilitate the C–C coupling (0.72 e V) compared to the Cu(100) motif (1.09 e V).Therefore,the region Ⅲ and Ⅱ motifs form a tandem catalysis pathway,which promotes the C^(2+)selectivity on Cu GBs.This work provides new insights into CO_(2)RR process.
