Subsurface multi-physical characterization of mountain excavation and city construction in loess plateau with a fiber-optic sensing system

Mountain excavation and city construction(MECC)projects being launched in the Loess Plateau in China involve the creation of large-scale artificial land.Understanding the subsurface evolution characteristics of the artificial land is essential,yet challenging.Here,we use an improved fiber-optic monitoring system for its subsurface multi-physical characterization.The system enables us to gather spatiotemporal distribution of various parameters,including strata deformation,temperature,and moisture.Yan’an New District was selected as a case study to conduct refined in-situ monitoring through a 77 m-deep borehole and a 30 m-long trench.Findings reveal that the ground settlement involves both the deformation of the filling loess and the underlying intact loess.Notably,the filling loess exhibits a stronger creep capability compared to underlying intact loess.The deformation along the profile is unevenly distributed,with a positive correlation with soil moisture.Water accumulation has been observed at the interface between the filling loess and the underlying intact loess,leading to a significant deformation.Moreover,the temperature and moisture in the filling loess have reached a new equilibrium state,with their depths influenced by atmospheric conditions measuring at 31 m and 26 m,respectively.The refined investigation allows us to identify critical layers that matter the sustainable development of newly created urban areas,and provide improved insights into the evolution mechanisms of land creation.

Application of Vacuum Photoelectric Detection Technology in Super-Resolution System

Due to the wave characteristics of light, diffraction occurs when the light passes through the optical system, so that the resolution of the ordinary far-field optical system is limited by the size of the Airy disk diameter. There are various factors that cause image quality degradation during system detection and imaging, such as optical system aberrations, atmospheric inter-ference, defocusing, system noise and so on. Super-resolution optical imaging technology is the most innovative breakthrough in the optical imaging and detection field in this century. It goes beyond the resolution limit of ordinary optical systems or detectors, and can get more details and information of the structure, providing unprecedented tools for various fields. Compared with ordinary optical systems, super-resolution systems have very high requirements on the signals to be detected, which cannot be met by ordinary detection techniques. Vacuum photoelectric detection and imaging technology is equipped with the characteristics of high sensitivity and fast response. It is widely used in super-resolution systems and has played a great role in super-resolution systems. In this paper, the principles and structure of the image-converter streak camera super-resolution system, scanning electron microscopy super-resolution system and laser scanning confocal super-resolution system will be sorted out separately, and the essential role of the vacuum photoelectric detection technology in the ultra-microscopic sys-tem will be analyzed.

Performance evaluation of two types of heated cables for distributedtemperature sensing-based measurement of soil moisture content

Distributed temperature sensing(DTS)using heated cables has been recently developed for distributed monitoring of in-situ soil moisture content.In this method,the thermal and electrical properties of heated cables have a significant influence on the measurement accuracy of soil moisture content.In this paper,the performances of two heated cables,i.e.the carbon-fiber heated cable(CFHC)and the metalnet heated cable(MNHC),are studied in the laboratory.Their structures,uniformity in the axial direction,measurement accuracy and suitability are evaluated.The test results indicate that the MNHC has a better uniformity in the axial direction than CFHC.Both CFHC and MNHC have high measurement accuracy.The CFHC is more suitable for short-distance measurement(500 m),while the MNHC can be used for longdistance measurement(>500 m).

Effect of burden and origin sites of premature ventricular contractions on left ventricular function by 7-day Holter monitor

Recent studies have shown that premature ventricular contractions （PVCs） could enlarge the heart, but its risk factors are incompletely understood as a single 24-hour recording cannot reflect the true PVC burden due to day-to-day variability. Our purpose was to investigate the effect of burden and origin sites on left ventricular （LV） function in patients with PVCs by 7-day Holter electrocardiography （ECG）. From May 2012 to August 2013, 112 consecutive patients with PVCs were recruited from the authors＇ affiliated hospital. All patients received 2-dimensional transthoracic echocardiography, 12-lead routing ECG and 7-days Holter ECG. Serum N-terminal pro- brain natriuretic peptide （NT-proBNP） levels were measured. A total of 102 participants with PVCs were included in the final analysis. Origin of PVCs from the tricuspid annulus had the highest burden and NT-proBNP level. LV papillary muscle had a higher LV ejection fraction （EF） level and a lower LV end-systolic dimension （ESD） than other PVC foci （P〈0.05）. The high burden group had a higher LV end-diastolic dimension （EDD） and LVESD but lower LVEF than the other two groups （P〈0.05）. Female, older age, physical work, and history of PVCs had a significantly positive correlation with symptoms. Male, older age, physical work, and high burden were positive predictors of enlarged LVEDD, LVESD and higher serum NT-proBNP level, but lower LVEF. Seven-day dynamic ECG Holter monitor showed the true PVC burden on patients with PVCs. PVCs with a lower burden or origin from the LV papillary muscle and the fascicle were relatively benign, while PVCs with a higher burden or origin from the tricuspid annulus may lead to cardiac dysfunction.

Epicardial adipose tissue around the superior vena cava: A single center study of factors related to atrial fibrillation

The superior vena cava(SVC)is the main component of non-pulmonary vein(PV)ectopy in patients with atrial fibrillation(AF).Researchers have found that epicardial adipose tissue(EAT)volume is related to the AF substrate,which can be defined by the low voltage area(LVA).This study aimed to investigate the relationship between SVC-EAT and SVC-AF.Twenty-six patients with SVC-AF triggers were identified as the SVC-AF group.Other three groups were defined and included as the LVA-AF group(LVA>5%),non-LVA-AF group(LVA<5%),and physical examination(PE)group.EAT around left atrium(LA-EAT)and SVC-EAT volumes were obtained using a cardiac risk assessment module.According to the SVC/LA-EAT ratio,there are significant differences between the SVC-AF group and the three control groups(the SVC-AF group 0.092±0.041 vs.the LVA-AF group 0.054±0.026,the non-LVA-AF group 0.052±0.022,and the PE group 0.052±0.019,all P<0.001).Receiver operating characteristic curve analysis suggests the optimal cut-off point of SVC/LA-EAT ratio is 6.8%for detecting SVC-AF patients,with 81.1%sensitivity,73.1%specificity,and an area under the curve of 0.83(95%confidence interval,0.75-0.91).Those with SVC-AF have a higher SVC/LA-EAT ratio and empirical SVC isolation could be considered if the SVC/LA-EAT ratio was over 6.8%.

Surface-Driven High-Pressure Processing

The application of high pressure favors many chemical processes, providing higher yields or improved rates in chemical reactions and improved solvent power in separation processes, and allowing activation barriers to be overcome through the increase in molecular energy and molecular collision rates. High pressures-up to millions of bars using diamond anvil cells-can be achieved in the laboratory, and lead to many new routes for chemical synthesis and the synthesis of new materials with desirable thermody- namic, transport, and electronic properties. On the industrial scale, however, high-pressure processing is currently limited by the cost of compression and by materials limitations, so that few industrial processes are carried out at pressures above 25 MPa. An alternative approach to high-pressure processing is pro- posed here, in which very high local pressures are generated using the surface-driven interactions from a solid substrate. Recent experiments and molecular simulations show that such interactions can lead to local pressures as high as tens of thousands of bars （1 bar=1×10^5 Pa）, and even millions of bars in some cases. Since the active high-pressure processing zone is inhomogeneous, the pressure is different in dif- ferent directions. In many cases, it is the pressure in the direction parallel to the surface of the substrate （the tangential pressure） that is most greatly enhanced. This pressure is exerted on the molecules to be processed, but not on the solid substrate or the containing vessel. Current knowledge of such pressure enhancement is reviewed, and the possibility of an alternative route to high-pressure processing based on surface-driven forces is discussed. Such surface-driven high-pressure processing would have the advantage of achieving much higher pressures than are possible with traditional bulk-phase processing, since it eliminates the need for mechanical compression. Moreover, no increased pressure is exerted on the containing vessel for the process, thus eliminating concerns about materials failure.

Realizing p-type performance in low-thermal-conductivity BiSbSe_(3) via lead doping

BiSbSe_(3) is an intrinsic n-type thermoelectric material,which attracts a lot of research interest due to its low lattice thermal conductivity and multiple band structure,and it exhibits excellent thermoelectric properties in the midtemperature region.However,there is little research on p-type BiSbSe_(3).This work realized the successful preparation of p-type BiSbSe_(3) through Pb doping.The thermoelectric transport properties of Pb-doped p-type BiSbSe_(3)were investigated.Pb doping could further reduce the thermal conductivity of BiSbSe_(3).All Pb-doped samples exhibited and maintained stable p-type transmissionthroughout the working temperature range(300-723 K).This work proves that Pb can be successfully used as a p-type dopant for BiSbSe_(3).

A general methodology to measure the light-to-heat conversion efficiency of solid materials

Light-to-heat conversion has been intensively investigated due to the potential applications including photothermal therapy and solar energy harvesting.As a fundamental property of materials,accurate measurement of light-to-heat conversion efficiency(LHCE)is of vital importance in developing advanced materials for photothermal applications.Herein,we report a photothermal and electrothermal equivalence(PEE)method to measure the LHCE of solid materials by simulating the laser heating process with electric heating process.The temperature evolution of samples during electric heating process was firstly measured,enabling us to derive the heat dissipation coefficient by performing a linear fitting at thermal equilibrium.The LHCE of samples can be calculated under laser heating with the consideration of heat dissipation coefficient.We further discussed the effectiveness of assumptions by combining the theoretical analysis and experimental measurements,supporting the obtained small error within 5%and excellent reproducibility.This method is versatile to measure the LHCE of inorganic nanocrystals,carbon-based materials and organic materials,indicating the applicability of a variety of materials.

川西甲基卡锂矿3211 m科学深钻多物理量分布式光纤观测

川西甲基卡锂矿3211 m科学深钻位于青藏高原东缘鲜水河断裂及川藏铁路附近,是目前青藏高原上最深的科学钻孔.利用此深钻观测深部物理场和浅部环境的变化过程,对于研究青藏高原地壳活动、川藏铁路场地稳定性和生态环境保护等均具有重要意义.采用分布式光纤传感(distributed fiber optic sensing,DFOS)技术,我们研发了高强度、耐高温的特种传感光缆,成功植入甲基卡锂矿深钻中,建成了世界上海拔最高和深度最大的光纤观测孔,实现了应变、温度、振动、水分等多物理量的分布式原位观测.本文是甲基卡光纤观测孔第一阶段的成果,包括岩体热导率的原位测定、钻孔回填过程的分布式声波振动(distributed acoustic sensing,DAS)观测、地震监测与地震成像等方面的初步进展.研究表明:DFOS应用于深钻全断面多物理量观测是可行的,它完全能适应深钻高温和高压的观测环境,并具有长距离、实时、连续分布式观测的优势;将分布式温度传感光纤、应变传感光纤和声波传感光纤集于一根传感光缆的设计思路保障了深钻传感光缆的安装质量,并为DFOS技术应用于地球物理和地质工程的多物理场观测开辟了广阔的应用空间.

从天然动物丝到丝蛋白基材料的研究

作为具有优异综合力学性能的天然蛋白质纤维,丰产的动物丝特别是蚕丝长期伴随着人们的日常生活,近十余年来,各种具有特色的功能性丝蛋白基材料更是层出不穷.但在探索动物丝和丝蛋白基材料的过程中,动物丝纤维是经由蚕或蜘蛛等动物的纺器而纺制得到的简单事实往往被忽视;换言之,动物丝实际上是动物对丝蛋白进行体内“加工”后的产物,也是丝蛋白基材料中的一种.因此,天然动物丝中独特的各等级间构效关系与丝蛋白基材料的构效关系之间并不存在着必然的传承效应.本文着重介绍了我们在对动物丝和丝蛋白基材料探索中的经验和体会,即在强调以丝蛋白分子链结构与性能及其之间的关系为研究重点的基础上,从比较和发掘各种天然动物丝的特性入手,进而了解丝蛋白分子链在本体和溶液中的行为,并通过对动物丝蛋白分子链聚集态结构的调控,以达到设计制备一系列多形貌和多功能的动物丝蛋白基材料的目的.

用于压力传感的还原氧化石墨烯/丝蛋白基多孔复合材料

利用丝蛋白能够在还原氧化石墨烯片层上发生选择性聚集的特性,制备了还原氧化石墨烯片层上富集有丝蛋白微纤且分散性良好的还原氧化石墨烯片和丝蛋白混合溶液,并通过冷冻以及低温乙醇处理的方法得到一系列不同比例的还原氧化石墨烯/丝蛋白基多孔复合材料.随后,采用溶液浸泡的方法在多孔材料表面再次沉积还原氧化石墨烯,以进一步提高还原氧化石墨烯/丝蛋白基多孔复合材料的压敏导电性.系统观察和测试结果表明,还原氧化石墨烯的引入,不仅使得多孔材料内部出现了相应的微纳结构,同时也提高了多孔材料的力学性能.还原氧化石墨烯/丝蛋白基多孔复合材料在完全湿态下兼具较好的强度和弹性,可以在0%~80%的压缩应变之间实现良好的压缩回复效果和压力传感性能.其中,最佳比例下的还原氧化石墨烯/丝蛋白基多孔复合材料在低压力下的灵敏度可达0.15 kPa−1,在0~17.3 kPa范围内能够高效工作并且具有优异的电学稳定性和耐疲劳性.因此,还原氧化石墨烯/丝蛋白基多孔复合材料因其高灵敏度、宽工作范围、结构可调以及可塑性好等诸多优点,有望在柔性压力传感方面获得较好的应用.

Photoinduced Merging with Copper-or Nickel-Catalyzed 1,4-Cyanoalkylarylation of 1,3-Enynes to Access Multiple Functionalizatized Allenes in Batch and Continuous Flow

A three-component reaction of 1,3-enynes and cyclobutanone oxime esters in the presence of aryl boronic acids or organozinc reagents via the photoredox/copper or photoredox/nickel catalysis has been established.This redox-neutral 1,4-cyanoalkylarylation reaction has demonstrated mild condition,high catalytic reactivity and wide functional group compatibility,allowing access to a variety of functionalized tetra-substituted allene derivatives with high chemo-and regioselectivity.Moreover,using photocatalytic continuous flow technique to promote this process would result in increased yields(70%in flow vs.61%in batch),reduced reaction times(7 min in flow vs.6 h in batch),and easy scale-up(upgrade to gram scale),showcasing its potential as a synthetic platform.

DFOS Applications to Geo-Engineering Monitoring

Optical fiber sensing technology has developed rapidly since the 1980s with the development of the optical fiber and fiber optical communication technology.It is a new type of sensing technology that uses light as a carrier and optical fiber as a medium to sense and transmit external signals(measurands).Distributed fiber optical sensors(DFOS)can continuously measure the external physical parameters distributed along the geometric path of the optical fiber.Meanwhile,the spatial distribution and change information of the measured physical parameters over time can be obtained.This technology has unmatched advantages over traditional point-wise and electrical measurement monitoring technologies.This paper summarizes the state-of-the-art research of the application of the distributed optical fiber sensing tech no logy in geo-engineering in the past 10 years,mainly including the advantages of DFOS,the challenges in geo-engineering monitoring,related fundamental theoretical issues,sensing performance of the optical sensing cables,distributed optical fiber monitoring system for geo-engineering,and applications of optical fiber sensing technology in geo-engineering.

Effect of cross-section shape of rotating chute on particle movement and distribution at the throat of a bell-less top blast furnace

Rotating chutes are widely used to control the burden distribution and enhance the gas distribution in a blast furnace.The chute cross-section shape has a significant effect on the particle movement and distribution.Therefore,this study developed a three-dimensional model of a blast furnace top with rotating chute using the discrete element method.The effect of different chute shapes on the particle movement and radial burden distribution was then investigated.The results showed that the burden stream height at the chute discharge agrees well with the burden stream thickness at the burden surface.A semicircular chute had the largest main striking point,where the chute discharge joins the burden surface,and trapezoidal and rectangular chutes had successively smaller MSPs.The semicircular chute helped to obtain a uniform radial size distribution.The trapezoidal chute helped form an aggregated burden stream at low rotating speeds,while the rectangular shape chute achieved this at higher rotating speeds and different chute angles.