Preliminary geological interpretation of long-wavelength magnetic anomalies over China and surrounding regions

Long-wavelength(>500 km)magnetic anomalies originating in the lithosphere were first found in satellite magnetic surveys.Compared to the striking magnetic anomalies around the world,the long-wavelength magnetic anomalies in China and surrounding regions are relatively weak.Specialized research on each of these anomalies has been quite inadequate;their geological origins remain unclear,in particular their connection to tectonic activity in the Chinese and surrounding regions.We focus on six magnetic high anomalies over the(1)Tarim Basin,(2)Sichuan Basin(3)Great Xing’an Range,(4)Barmer Basin,(5)Central Myanmar Basin,and(6)Sunda and Banda Arcs,and a striking magnetic low anomaly along the southern part of the Himalayan-Tibetan Plateau.We have analyzed their geological origins by reviewing related research and by detailed comparison with geological results.The tectonic backgrounds for these anomalies belong to two cases:either ancient basin basement,or subduction-collision zone.However,the geological origins of large-scale regional magnetic anomalies are always subject to dispute,mainly because of limited surface exposure of sources,later tectonic destruction,and superposition of multi-phase events.

Investigation of long-wavelength elastic wave propagation through wet bentonite-filled rock joints

The saturation of the compacted bentonite buffer in the deep geological repository can cause bentonite swelling,intrusion into rock fractures,and erosion.Inevitably,erosion and subsequent bentonite mass loss due to groundwater inflow can aggravate the overall integrity of the engineered barrier system.Therefore,the coupled hydro-mechanical interaction between the buffer and rock during groundwater inflow and bentonite intrusion should be evaluated to guarantee the long-term safety of deep geological disposal.This study investigated the effect of bentonite erosion and intrusion on the elastic wave propagation characteristics in jointed rocks using a quasi-static resonant column test.Jointed rock specimens with different joint conditions(i.e.joint surface saturation and bentonite filling)were prepared using granite rock discs sampled from the Korea Underground Research Tunnel(KURT)and Gyeongju bentonite.The long-wavelength longitudinal and shear wave velocities were measured under different normal stress levels.A Hertzian-type power model was used to fit the wave velocities,and the relationship between the two fitted parameters provided the trend of joint conditions.Numerical simulations using three-dimensional distinct element code(3DEC)were conducted to better understand how the long-wavelength wave propagates through wet bentonite-filled rock joints.

Development of long-wavelength infrared detector and its space-based application requirements

Infrared detection technology has greatly expanded the ability of mankind to study the earth and the universe. In recent years, the demand for long-wavelength infrared detectors is increasing for their advantages in exploring the earth and the universe. A variety of long-wavelength infrared detectors have been made based on thermal resistive effect, photoelectric effect, etc., in the past few decades. Remarkable achievements have been made in infrared materials, device fabrication,readout circuit, and device package. However, high performance long-wavelength infrared detectors, especially those for large format long-wavelength infrared detector focus plane array, are still unsatisfactory. Low noise, high detectivity, and large format long-wavelength infrared detector is necessary to satisfy space-based application requirements.

Growth of high material quality InAs/GaSb type-Ⅱ superlattice for long-wavelength infrared range by molecular beam epitaxy

By optimizing theⅤ/Ⅲbeam-equivalent pressure ratio,a high-quality InAs/GaSb type-Ⅱsuperlattice material for the long-wavelength infrared(LWIR)range is achieved by molecular beam epitaxy(MBE).High-resolution x-ray diffraction(HRXRD),atomic force microscopy(AFM),and Fourier transform infrared(FTIR)spectrometer are used to characterize the material growth quality.The results show that the full width at half maximum(FWHM)of the superlattice zero-order diffraction peak,the mismatching of the superlattice zero-order diffraction peak between the substrate diffraction peaks,and the surface roughness get the best results when the beam-equivalent pressure(BEP)ratio reaches the optimal value,which are 28 arcsec,13 arcsec,and 1.63?,respectively.The intensity of the zero-order diffraction peak is strongest at the optimal value.The relative spectral response of the LWIR detector shows that it exhibits a 100%cut-off wavelength of 12.6μm at 77 K.High-quality epitaxial materials have laid a good foundation for preparing high-performance LWIR detector.

The Long-Wavelength Mantle Structure, and the supercontinent Evolution since the Paleozoic

The Earth’s lower mantle structure,as revealed by seismic tomography studies,is best characterized by two large low seismic velocity provinces(i.e.,LLSVP)beneath Africa and Pacific and their surrounding,circum-

长/长波双色二类超晶格红外探测器研究

报道了长/长波双色二类超晶格红外焦平面探测器组件的研制。通过能带结构设计和分子束外延技术,获得了表面质量良好的长/长波双色超晶格外延材料。突破了长波超晶格低暗电流钝化、低损伤干法刻蚀等关键技术,制备出像元中心距30μm的320×256长/长波双色InAs/GaSb超晶格焦平面探测器芯片。将芯片与双色读出电路互连,采用杜瓦封装,与制冷机耦合形成探测器组件。组件双波段50%后截止波长分别为7.7μm(波段1)和10.0μm(波段2)。波段1平均峰值探测率达到8.21×10^(10)cm·W^(-1)·Hz^(1/2),NETD实现28.8 mK;波段2平均峰值探测率达到6.15×10^(10)cm·W^(-1)·Hz^(1/2),NETD为37.8 mK,获得了清晰的成像效果,实现长/长波双色探测。

人工微纳结构增强长波及甚长波红外探测器

红外探测器具有把物体辐射的光子信息转换为电信号的能力,拓宽了人们观察自然环境与人类活动的边界.当前,长波及甚长波红外探测器已在大气监测、夜间侦查、深空探测等领域有诸多应用.随着各国对高端红外探测器要求的快速提升,传统红外探测器难以兼顾高响应率、高响应速度以及多维探测等性能指标的瓶颈日益凸显.基于微纳光学理论设计的人工微纳结构,可实现其与红外光子的高效耦合,综合调控红外光场的振幅、偏振、相位及波长等自由度.为拓展红外探测器额外的调控自由度,进而在实现高量子效率的同时,兼顾较高的响应速率与优异的偏振或波长选择性,集成红外探测器与人工微纳结构的研究思路近年来被广泛应用.本文讨论了人工微纳结构在长波及甚长波红外探测领域的应用进展,详述了表面等离激元、局域等离激元、谐振腔结构、陷光结构、超透镜、赝表面等离激元、间隙等离激元和声子极化激元等机制的应用现状及各机制固有的优劣势,进而指出了人工微纳结构在长波及甚长波红外探测应用的发展前景与方向.

无热化设计的紧凑型长波折反式光学系统

介绍了一种无热化设计的紧凑型长波折反式光学系统,给出了光学系统的主要指标和要求,说明了系统的设计原理。该系统的工作波段为7.7～10.3μm,焦距为270 mm,F数为1.35。光学系统共由7个光学元件构成,构型紧凑,在-40～+60℃温度范围内具有良好像质,实现了无热化。

Long-wavelength(red to near-infrared) emissive carbon dots: Key factors for synthesis, fluorescence mechanism, and applications in biosensing and cancer theranostics

Carbon dots(CDs), as a new member of carbon nanostructures, have been widely applied in extensive fields due to their exceptional physicochemical properties. While, the emissions of most reported CDs are located in the blue to green range under the excitation of ultraviolet or blue light, which severely limits their practical applications, especially in photovoltaic and biological fields. Studies that focused on synthesizing CDs with long-wavelength(red to near-infrared) emission/excitation features(simply named L-w CDs) and exploring their potential applications have been frequently reported in recent years. In this review, we analyzed the key influence factors for the synthesis of CDs with long wavelength and multicolor(containing long wavelength) emissive properties, discussed possible fluorescence mechanism,and summarized their applications in sensing and cancer theranostics. Finally, the existing challenges and potential opportunities of L-w CDs are presented.

Investigation of active-region doping on InAs/GaSb long wave infrared detectors

The eight-band κ·p model is used to establish the energy band structure model of the type-II InAs/GaSb superlattice detectors with a cut-off wavelength of 10.5μm,and the best composition of M-structure in this type of device is calculated theoretically.In addition,we have also experimented on the devices designed with the best performance to investigate the effect of the active region p-type doping temperature on the quantum efficiency of the device.The results show that the modest active region doping temperature(Be:760℃)can improve the quantum efficiency of the device with the best performance,while excessive doping(Be:>760℃)is not conducive to improving the photo response.With the best designed structure and an appropriate doping concentration,a maximum quantum efficiency of 45% is achieved with a resistance-area product of 688?·cm^2,corresponding to a maximum detectivity of 7.35×10^11cm·Hz^1/2/W.

2080 nm long-wavelength, high-power dissipative soliton resonance in a dumbbell-shaped thulium-doped fiber laser

We demonstrate a 2080 nm long-wavelength mode-locked thulium(Tm)-doped fiber laser operating in the dissipative soliton resonance(DSR) regime. The compact all-fiber dumbbell-shaped laser is simply constructed by a 50/50 fiber loop mirror(FLM), a 10/90 FLM, and a piece of large-gain Tm-doped double-clad fiber pumped by a 793 nm laser diode. The 10/90 FLM is not only used as an output mirror, but also acts as a periodical saturable absorber for initiating DSR mode locking. The stable DSR pulses are generated at the center wavelength as long as 2080.4 nm, and the pulse duration can be tunable from 780 to 3240 ps as the pump power is increased. The maximum average output power is 1.27 W, corresponding to a pulse energy of 290 nJ and a nearly constant peak power of 93 W. This is, to the best of our knowledge, the longest wavelength for DSR operation in a mode-locked fiber laser.

Serpentinized Peridotite as Source of Aeromagnetic Anomalies

The source of long-wavelength aeromagnetic anomalies appears to originate from the earth's deep crust. Constrained by previous studies on geochemical, petrologic analysis, the eclogite and serpentinized peridotite samples from drill hole ZK703 at Donghai in the western Sulu ultrahigh-pressure (UHP) terrane, East China, were unambiguously exhumed from the lower crust and the upper mantle, providing significant information about the magnetic properties of rocks at a deeper part of the crust. Results show that the serpentinization process favors the neoformation of nearly stoichiometric magnetite, resulting in the enhancement of its magnetization up to 8.6 A/m, which is sufficient enough to contribute to some magnetic anomalies. In contrast, eclogite samples have only weaker magnetization (generally less than 0.05 A/m) compared to serpentinized peridotite. Nevertheless, experiments under the lower crustal conditions are necessary to further support these conclusions.

On the exact solutions to the long short-wave interaction system

The complete discrimination system for polynomial method is applied to the long-short-wave interaction system to obtain the classifications of single traveling wave solutions. Compared with the solutions given by the （G~/G）-expansion method, we gain some new solutions.

Sensitivity analysis of an HgCdTe based photovoltaic receiver for long-wavelength free space optical communication systems

We examine theoretically the performance of an Hg0.77Cd0.23Te based p-n photodetector/HFET optical receiver due to its possible application at 10.6 μm free space optical communication system at high bit rate.A rigorous noise model of the receiver has been developed for this purpose.We calculate the total noise and sensitivity of the receiver.The front-end of the receiver exhibits a sensitivity of -45 dBm at a bit rate of 1 Gb/s and -30 dBm at a bit rate of 10 Gb/s,and the total mean-square noise curren t〈i2n〉=5×10-15 A2 at a bit rate of 1 Gb/s an d〈i2n〉 =10-12 A2 at a bit rate of 10 Gb/s,and a 3-dB bandwidth of 10 GHz.

Analysis on Depth Distribution and Precursor Mechanism of Small and Moderate Earthquakes

In this paper, the focus depth distribution of earthquakes with each magnitude has been analyzed. Statistic data show that the lower magnitude is, the wider focus depth distributes. With larger magnitude, the focus tends to be concentrated in upper or middle crustal layers. We analyzed the cause of focus depth distribution and explained the precursor mechanism of small and moderate earthquakes with occurring condition and characteristics of strong earthquakes. The results of this paper may be applied to determine risk sites of strong earthquakes.

Case Studies on Newly-emerging Long- and Medium-term Strategic Planning and Its Reference to Beijing

Responding to the significant impacts brought by social, political, economic and environmental changes, some countries, regions and cities in the world have introduced new forms of long- and medium-term strategic planning since 2000, so as to promote the sustainable development of the cities or regions through a higher-level thoughts and a wider-perspective exploration. Taking America 2050, Future Ruhr 2030, New York 2030 and some other long- and medium-term strategic plans as examples, the paper analyzes the evolution of long- and medium-term strategic planning from the aspects of plan-making methods, analyzing techniques, research contents development trends etc. at the state, regional, and city levels. Based on international experience, this paper puts forward the necessity for Beijing to launch a new long-term strategic planning study "Beijing 2049." The innovation, challenges and development direction of "Beijing 2049" is also expounded in the paper.

Organic Host-Guest Materials with Bright Red Room-Temperature Phosphorescence for Persistent Bioimaging

Organic room-temperature phosphorescence(RTP)materials have attracted immense attention in bioimaging due to their long emission lifetime and large Stokes shift.RTP materials with long emission wavelength can improve the penetration depth for bioimaging.However,the design of red persistent RTP materials is still challenging.In this study,a fused-ring structure has been proposed to effectively decrease the triplet energy level,thus extending the emission wavelength of phosphorescence.In addition,the fused-ring structure exhibits a high molar extinction coefficient(ɛ)and high luminescence efficiency due to the rigid structure.A new class of crystalline hosts(iminodibenzyl,IDB)are developed to stabilize the triplet excitons that are generated from the fused-ring molecules.The maximum RTP wavelength of doping materials can reach 635 nm with a lifetime of 9.35 ms.Water-disperse nanoparticles are successfully prepared for in vivo time-resolved bioimaging,which eliminates the background fluorescence interference from biological tissues.These reveal a delicate design strategy for the construction of long-wavelength emissive RTP materials for high-resolution bioimaging.

State-of-the-art development about cryogenic technologies to support space-based infrared detection

As a key technology for space-based Earth observation and astronomical exploration,cooled mid-wavelength and long-wavelength Infrared(IR)detection is widely used in national defense,astronomy exploration,medical imaging,environmental monitoring,agricultural and other areas.The performances of IR detectors,including cut-off wavelength,detectivity,sensitivity and temperature resolution,plays a significant role in efficiently observing and tracking the low-temperature far-distance moving targets.Achieving optimal detection performance requires the IR detectors to operate at cryogenic temperatures.The future development of space-based applications relies heavily on the mid-wavelength and long-wavelength IR detection technologies,which should be enabled by the long-life cryogenic refrigeration and high-efficiency energy transportation system operating below 40 K,to support the Earth observation and astronomical detection.However,the efficiency degradation caused by the super low temperature brings tremendous challenges to the life time of cryogenic refrigeration and energy transportation systems.This paper evaluates the influence of cryogenic temperature on the infrared detector performances,reviews the features,development and space applications of cryogenic cooling technologies,as well as the cryogenic energy transportation approaches.Additionally,it analyzes the future development trends and challenges in supporting the space-based IR detection.

长波和甚长波及其双色InAs/GaSb二类超晶格红外探测器的研究进展

本文报道了基于InAs/GaSb二类超晶格实现长波、甚长波及窄带长波/甚长波双色红外探测器的研究,生长的材料具有极高的材料质量.长波探测器单管器件在77 K条件下50%截止波长为9.6μm,峰值响应为3.2 A/W,峰值量子效率为51.6%;甚长波红外探测器单管器件在77 K条件下50%截止波长为14.5μm,量子效率为14%,热噪声限制的探测率为4.3×109 cm Hz1/2 W-1.通过改变偏压极性实现双色探测的窄带型长波/甚长波InAs/GaSb二类超晶格红外探测器两端器件,偏压小于0 V时在长波区工作,偏压大于40 mV时,在甚长波区工作.具体来说,偏压为-0.1 V时,器件光响应50%截止波长为10μm;而偏压为40 mV时,器件光响应50%截止波长为16μm.对于长波光响应,δλ/λ为44%,对于甚长波响应,δλ/λ为46%.甚长波对长波的串音为9.9%,长波对甚长波的串音为11.8%.

Selective biocompatibility and responsive imaging property of cationic conjugated polyelectrolyte to cancer cells

Optical imaging, as an important molecular imaging modality, has emerged many attractions in studying the biological or molecular events both in cell level and living subject because of its high resolution and sensitivity, noninvasive manner and low cost. Herein, we bring novel insights into a water-soluble conjugated polyelectlyte by deeply studying its properties in cells. Poly（9, 9-bis（6＇-N,N,N-trimethylammonium hexyl）fluorene phenylene）（PFP）, a good biosensing material, was studied in this paper. The biocompatibility of PFP was investigated in different cells, and cell cycle analysis was carried out to explore the reasons of different biocompatibility of PFP to cells. After irradiation, fluorescence enhancement of blue emission and turn-on of long-wavelength emission of PFP in HepG2 cells was observed, which was first reported as far as we know. The differentiated biocompatibility of PFP and its particular imaging properties in cancer cells can help to guide the application of conjugated polymers in cells and provide a new dimension in designing sensitive and responsive imaging materials.