Nano-twinned copper(nt-Cu),with a preferred orientation,is highly promising as interconnect materials in high-density advanced packaging due to its considerable mechanical strength,excellent electrical conductivity,an...Nano-twinned copper(nt-Cu),with a preferred orientation,is highly promising as interconnect materials in high-density advanced packaging due to its considerable mechanical strength,excellent electrical conductivity,and resistance to thermal migration.However,its application is impeded by sulfur-containing byproducts from the electroplating process,exacerbating the formation of Kirkendall voids within solder joints during thermal aging.Herein,through the incorporation of Zinc(Zn)into the nt-Cu layer,we develop a nt-Cu/Zn composite structure.Our findings provide the first definitive confirmation of the mechanism by which sulfur atoms migrate to the Cu_(3)Sn/nt-Cu interface through interstitial diffusion,thereby reducing the activation energy for vacancy formation.We further demonstrate that Zn effectively an-choring sulfur atoms,forming ZnS within the nt-Cu layer during heat treatment,which increases the vacancy formation energy and inhibits the development of Kirkendall voids.Remarkably,no Kirkendall voids are observed in the modified interconnects even after prolonged aging at 150℃ for 1000 h.The nt-Cu/Zn composite metallization layers significantly decrease the growth rate of interfacial intermetallic compounds by 33.6% and enhance the shear strength of solder interconnections to 228.9%.This research underscores the potential of nt-Cu in advanced electronic packaging,offering new pathways for improving the power density and reliability of electronic devices.展开更多
Soliton molecules(SMs),bounded and self-assembled of particle-like dissipative solitons,exist with versatile mutual interactions and manifest substantial potential in soliton communication and optical data storage.How...Soliton molecules(SMs),bounded and self-assembled of particle-like dissipative solitons,exist with versatile mutual interactions and manifest substantial potential in soliton communication and optical data storage.However,controllable manipulation of the bounded molecular patterns remains challenging,as reaching a specific operation regime in lasers generally involves adjusting multiple control parameters in connection with a wide range of accessible pulse dynamics.An evolutionary algorithm is implemented for intelligent control of SMs in a 2μm ultrafast fiber laser mode locked through nonlinear polarization rotation.Depending on the specifications of the merit function used for the optimization procedure,various SM operations are obtained,including spectra shape programming and controllable deterministic switching of doublet and triplet SMs operating in stationary or pulsation states with reconfigurable temporal separations,frequency locking of pulsation SMs,doublet and SM complexes with controllable pulsation ratio,etc.Digital encoding is further demonstrated in this platform by employing the self-assembled characteristics of SMs.Our work opens up an avenue for active SM control beyond conventional telecom bands and brings useful insights into nonlinear science and applications.展开更多
The second near-infrared window(NIR-II,900-1880 nm)overcomes critical limitations of visible(360-760 nm)and NIR-I(760-900 nm)imaging—including restricted penetration depth,low signal-to-back⁃ground ratio,and tissue a...The second near-infrared window(NIR-II,900-1880 nm)overcomes critical limitations of visible(360-760 nm)and NIR-I(760-900 nm)imaging—including restricted penetration depth,low signal-to-back⁃ground ratio,and tissue autofluorescence—establishing its pivotal role for in vivo deep-tissue bioimaging.With exponential growth in NIR-II photodiagnosis and phototherapy research over the past decade,bibliometric analy⁃sis is essential to map the evolving landscape and guide strategic priorities.We systematically analyzed 2,491 NIR-II-related publications(2009-2023)from the Web of Science Core Collection,employing scientometric tools for distinct analytical purposes:(a)VOSviewer,SCImago Graphica,and Gephi for co-authorship and co-occur⁃rence network mapping;(b)the R bibliometrix package for tracking field evolution and identifying high-impact publications/journals.The search retrieved 2491 studies from 359 journals originating from 54 countries.The country with the most published articles is China.Chinese institutions drive>60%of publications,with Stanford University(USA)and Nanyang Technological University(Singapore)ranked as the top two institutions by re⁃search quality.International cooperation is becoming increasingly frequent.Fan Quli,Tang Benzhong and Dai Hongjie are the top 3 productive authors in this field.Keyword evolution identifies"photodynamic therapy"and"immunotherapy"as pivotal future directions.We summarize the most cited literatures and NIR-II imaging clini⁃cal trials.This study delineates the NIR-II research trajectory,highlighting China's leadership,intensifying glob⁃al collaboration,and interdisciplinary convergence.Future efforts should prioritize the novel NIR-II probe devel⁃opment for NIR-II imaging and clinical translation of photodynamic/immunotherapy combinational platforms.展开更多
Interlayer exchange coupling(IEC)plays a critical role in spin-orbit torque(SOT)switching in synthetic magnets.This work establishes a fundamental correlation between IEC and SOT dynamics within Co/Pt-based synthetic ...Interlayer exchange coupling(IEC)plays a critical role in spin-orbit torque(SOT)switching in synthetic magnets.This work establishes a fundamental correlation between IEC and SOT dynamics within Co/Pt-based synthetic antiferromagnets and synthetic ferromagnets.The antiferromagnetic and ferromagnetic coupling states are precisely engineered through Ruderman-Kittel-Kasuya-Yosida(RKKY)interactions by modulating the Ir spacer thickness.Experimental results reveal that the critical switching current density exhibits a strong positive correlation with the IEC strength,regardless of the coupling type.A comprehensive theoretical framework based on the Landau-Lifshitz-Gilbert equation elucidates how IEC contributes to the effective energy barrier that must be overcome during SOT-induced magnetization switching.Significantly,the antiferromagnetically coupled samples demonstrate enhanced SOT efficiency,with the spin Hall angle being directly proportional to the antiferromagnetic exchange coupling field.These insights establish a coherent physical paradigm for understanding IEC-dependent SOT dynamics and provide strategic design principles for the development of energy-efficient next-generation spintronic devices.展开更多
Mineralogical,geochemical and isotopic(Sr and Nd) studies on the recently reported ca. 124 Ma'anorogenic lamproite' dyke from the Palanpur area, Kutch seismogenic rift zone, northwestern India, are presented. ...Mineralogical,geochemical and isotopic(Sr and Nd) studies on the recently reported ca. 124 Ma'anorogenic lamproite' dyke from the Palanpur area, Kutch seismogenic rift zone, northwestern India, are presented. We propose a new classification for the dyke as a damtjernite(ultramafic lamprophyre; UML)based on its porphyritic-panidiomorphic texture, abundance of phlogopite, presence of nepheline in the groundmass, and the composition of liquidus phases such as olivine, phlogopite, magnetite, and clinopyroxene(diopside). The Palanpur UML is primitive(Mg# =74-77),silica-undersaturated(SiO_2<40 wt.%),potassic to slightly sodic in nature, and is strikingly similar to the ～69 Ma UML dykes and sills of the Tethyan Indus suture zone, which are considered as the earliest yet known manifestations of the Deccan Large Igneous Province(LIP). Bulk-rock(^(87)Sr/^(86)Sr)_i(0.70460-0.70461) and ε_(N)d(t)(+2.56 to-0.69) of the Palanpur UML signify derivation from a slightly depleted mantle source similar to that of asthenospheric magmas such as OIB. This is further attested to by the high incompatible trace element ratios(viz., La/Ba, Nb/U, Nb/La and Ta/Yb) that are typical of plume-type magmas. However, the Neoproterozoic T_(DM) depleted mantle Nd model ages( ～655-919 Ma) also necessitate some involvement of a lithospheric mantle component in its genesis. High bulk-rock Fe_2 O_3~t and TiO_2 contents require the involvement of a fertile peridotitic mantle source, whereas high La/Yb(60-80) implies a control by residual garnet. Higher Rb/Sr and lower Ba/Rb suggest phlogopite as a residual phase and high Nb and lower La/Sm favour carbonatite, rather than silicate melt as metasomatising agent. Low degrees of partial melting of a primitive garnet lherzolite mantle can account for the observed REE patterns in the Palanpur UML. The Palanpur UML shares a temporal similarity to the Kerguelen plume-derived Rajmahal basalts and associated alkaline rocks from the eastern India. The tectonomagmatic significance of its emplacement during the mid-Cretaceous vis-a-vis various models involving the timing of eruption of the Deccan and the Rahmahal Traps and the rifting in the Kutch basin induced by far-field plate reorganization is evaluated.展开更多
A rapid and continuous method for production of LiFePO4/C nanoparticles in super heated water is described, wherein soluble starch was used as carbon precursor. The effects of pH, flow rate, temperature, and pressure ...A rapid and continuous method for production of LiFePO4/C nanoparticles in super heated water is described, wherein soluble starch was used as carbon precursor. The effects of pH, flow rate, temperature, and pressure on the formation of LiFePO4/C particles were investigated. Results showed that the pH value was the key factot on the formation of phase pure LiFePO4, which only formed at pH = 7; the LiFePO4/C-occurred as particles with about 70-200 nm size and LiFePO4 was covered by a thin carbon layer; higher flow rate, higher pressure, and lower temperature led to smaller particles of LiFePO4/C.展开更多
Near-infrared(NIR) nanoparticles(NPs) based on fluorescence resonance energy transfer(FRET) were prepared by coencapsulation of a red aggregation-induced emission(AIE) molecule, 2-(4-bromophenyl)-3-(4-(4-(diphenylamin...Near-infrared(NIR) nanoparticles(NPs) based on fluorescence resonance energy transfer(FRET) were prepared by coencapsulation of a red aggregation-induced emission(AIE) molecule, 2-(4-bromophenyl)-3-(4-(4-(diphenylamino)styryl)phenyl)fumaronitrile(TB), and a commercial NIR fluorescence dye, silicon 2,3-naphthalocyanine bis(trihexylsilyloxide)(NIR775) with an amphiphilic polymer poly(styrene-co-maleic anhydride)(PSMA). The surface of the NPs, PSMA@TB/NIR775, was modified with poly(ethylene glycol)(PEG) to increase the in vivo biocompatibility of the NPs. The PSMA@TB/NIR775 NPs showed a strong NIR(780 nm) narrow emission and excellent two-photon absorption property. Moreover, the NPs exhibited good monodispersity, stability, and low cytotoxicity.Under the excitation of a 1040 nm femtosecond(fs) laser, the emission peaks at 680 nm of TB and 780 nm of NIR775 excited by FRET were obtained. We utilized PSMA@TB/NIR775 NPs as fluorescent contrast agents for two-photon excited NIR microscopic imaging, and good NIR imaging effect of mouse brain vasculature was obtained with the imaging depth of about 150 μm. The FRET strategy by coencapsulating AIE molecule and NIR dye will be helpful in preparing more narrow emission NIR probes for deep-tissue biological imaging.展开更多
Nanocomposite Ti-Si-N thin films have been deposited on Si （100） substrate by direct current/radio frequency （DC/RF） magnetron sputtering. The effect of varying deposition parameters on the structure and mechanica...Nanocomposite Ti-Si-N thin films have been deposited on Si （100） substrate by direct current/radio frequency （DC/RF） magnetron sputtering. The effect of varying deposition parameters on the structure and mechanical properties of Ti-Si-N films has been investigated by characterization techniques such as X-ray dif- fraction （XRD）, field emission scanning electron microscopy （FE-SEM）, atomic force microscopy （AFM） and nanoindentation, respectively. XRD analysis of the thin films exhibit all （111）, （200） and （220） peaks initially with varying sputtering pressure, but （111） peak dominates at higher sputtering pressure. The crystallite size calculated from XRD peaks shows that it increases with increasing sputtering pressure. Microstructural analy- sis reveals that the dense blurred grains transform into uniform grains in the films and shows porosity with increasing sputtering pressure. The surface roughness of the Ti-Si-N films increases with varying sputtering pressure. The hardness and Youngrs modulus values of Ti-Si-N films are 33.7 and 278.6 GPa, respectively, with 0.7 Pa sputtering pressure but it decreases with further increase in sputtering pressure due to an increase in porosity of the films.展开更多
Current gradient-index(GRIN)lens based proximal-driven intracoronary optical coherence tomography(ICOCT)probes consist of a spacer and a GRIN lens with large gradient constant.This design provides great flexibility to...Current gradient-index(GRIN)lens based proximal-driven intracoronary optical coherence tomography(ICOCT)probes consist of a spacer and a GRIN lens with large gradient constant.This design provides great flexibility to control beam profiles,but the spacer length should be well controlled to obtain desired beam profiles and thus it sets an obstacle in mass catheter fabrication.Besides,although GRIN lens with large gradient constant can provide tight focus spot,it has short depth of focus and fast-expanded beam which leads to poor lateral resolution for deep tissue.In this paper,a type of spacer-removed probe is demonstrated with a small gradient constant GRIN lens.This design simplifies the fabrica-tion process and is suitable for mass production.The output beam of the catheter is a narrow nearly collimated light beam,referred to as pencil beam here.The full width at half maximum beam size varies from 35.1μm to 75.3μm in air over 3-mm range.Probe design principles are elaborated with probe/catheter fabrication and performance test.The in vivo imaging of the catheter was verified by a clinical ICOCT system.Those results prove that this novel pencil-beam scanning catheter is potentially a good choice for ICOCT systems.展开更多
It has been nearly 50 years since the first glimpse of the relationship between myopia and peripheral refractive errors. According to experiments on both animals and humans, the eyes with hyperopic peripheral vision a...It has been nearly 50 years since the first glimpse of the relationship between myopia and peripheral refractive errors. According to experiments on both animals and humans, the eyes with hyperopic peripheral vision appear to be at higher risk of developing myopia than those with myopic peripheral refractive errors. Despite the first measurement of peripheral refraction being achieved by a modified manual optometer, the concept of emmetropization triggered a rapidly increasing number of studies on peripheral aberrations. Not only the horizontal off-axis aberrations but also the meridional aberrations at different angles are measured by researchers during the development of peripheral aberrations measuring techniques. According to the differences among the working principles, a variety of techniques have been adopted for performing such measurements. The methods developed to realize the high-performance measurement involve the subject cooperating actively by rotating the head or eyes, the rotation of the whole optical path, and the combination of measurements of many light paths. This paper provides a review of the peripheral aberrations measuring techniques and their current status. This article also highlights the development trend of the measuring techniques of peripheral aberrations and practical applications of peripheral aberration measurements, such as the control of the accommodation, the measuring time, and the dynamic range problem of the wavefront sensor. Although wavefront sensing peripheral measurement is widely recognized for its capability to reveal both lower-order aberrations and higher-order aberrations, the efficiency of an autorefractometer is incomparable. The current study reveals that the most widely used peripheral aberration measurement methods are the use of an open field autorefractometer and Hartman-shack wavefront sensor-based techniques.展开更多
CaS phosphor activated with Dy ions is prepared by the solid-state diffusion method. The phosphor is characterized by x-ray powder diffraction, thermogravimetric analysis and photoiuminescence. Defect centres formed i...CaS phosphor activated with Dy ions is prepared by the solid-state diffusion method. The phosphor is characterized by x-ray powder diffraction, thermogravimetric analysis and photoiuminescence. Defect centres formed in CaS：Dy are studied using the technique of electron spin resonance. The thermoluminescence glow curve shows peaks at around 117℃ and 345℃. Irradiated CaS：Dy exhibits ESR lines due to defect centres. The thermal annealing behaviour of one of the defect centres appears to correlate with the TL peaks at 117℃ and 345℃. This centre is characterized by an isotropic g-value of 2.0035 and is assigned to an F^＋ centre.展开更多
Compared with visible light,near infrared(NIR)light has deeper penetration in biological tisues.Three-photon fuorescence microscopy(3PFM)can effectively utilize the NIR excitation to obtain high-contrast images in the...Compared with visible light,near infrared(NIR)light has deeper penetration in biological tisues.Three-photon fuorescence microscopy(3PFM)can effectively utilize the NIR excitation to obtain high-contrast images in the deep tisue.However,the weak three photon fluorescence signals may be not well presented in the traditional fuorescence intensity imaging mode.Fluorescence lifetime of certain probes is insensitive to the intensity of the excitation laser.Moreover,fluorescence lifetimne imaging microscopy(FLIM)can detect weak signals by utilizing time correlated single photon counting(TCSPC)technique.Thus,it would be an improved strategy to combine the 3PFM imaging with the FLIM together.Herein,DCDPP-2TPA,a novel agegation-induced emission luminogen(AIEgen),was adopted as the fluorescent probes.The three-photon absorption cros-section of the AlEgen,which has a deep-red fluorescence emission,was proved to be large.DCDPP-2TPA nanoparticles were synthesized,and the three photon fluorescence lifetime of which was measured in water.Moreover,in vrivo thre-photon fuorescence lifetime microscopic imaging of a craniotomy mouse was conducted via a home made optical system.High contrast cerebrovascular images of different vertical depths were obtained and the maximun depth was about 600 pumn.Even reaching the depth of 600 pum,tiny capillary vessels as small as 1.9 pum could still be distinguished.The three photon fuorescence lifetimes of the capillaries in some representative images were in accord with that of DCDPP-2TPA nanoparticles in water.A vivid 3D reconstruction was further organized to present a wealth of lifetime information.In the future,the combination strategy of 3PFM and FLIM could be further applied in the brain functional imaging.展开更多
As an important wide-bandgap semiconductor,gallium nitride(GaN)has attracted considerable attention.This paper describes the use of confocal Raman spectroscopy to characterize undoped GaN,n-type GaN,and p-type GaN thr...As an important wide-bandgap semiconductor,gallium nitride(GaN)has attracted considerable attention.This paper describes the use of confocal Raman spectroscopy to characterize undoped GaN,n-type GaN,and p-type GaN through depth profiling using 405-,532-,and 638-nm wavelength lasers.The Raman signal intensity of the sapphire substrate at different focal depths is studied to analyze the depth resolution.Based on the shift of the E2 H mode of the GaN epitaxial layer,the interfacial stress for different types of GaN is characterized and calculated.The results show that the maximum interfacial stress appears approximately at the junction of the GaN and the sapphire substrate.Local interfacial stress analysis between the GaN epitaxial layer and the substrate will be very helpful in furthering the applications of GaN devices.展开更多
The objective of the present work is to investigate the effect of various sputtering parameters such as nitrogen flow rate, deposition time and sputtering pressure on structural, wettability and optical properties of ...The objective of the present work is to investigate the effect of various sputtering parameters such as nitrogen flow rate, deposition time and sputtering pressure on structural, wettability and optical properties of titanium oxynitride films deposited on glass substrate by reactive magnetron sputtering. The X-ray diffraction graphs of titanium oxynitride films show evolution of various textures of TiO=N and TiN phases with increasing nitrogen flow rate and deposition time, but an increase in sputtering pressure from 4.0 to 8.0 Pa results in decline of various textures observed for TiO=Ny and TiN phases. The stress and strain calculated by sin2~ method are compressive, which decrease with increasing nitrogen flow rate from 55 to I00 sccm （standard cubic centimeter per minute） and increase with increasing deposition time from 80 to I40 min due to atomic penning effect and increasing thickness of the deposited films. The titanium oxynitride films have contact angle values above 90 deg., indicating that films are hydrophobic. The maximum contact angle of I09.1 deg. is observed at deposition time of 140 min. This water repellent property can add value to potential protective, wear and corrosion resistant application of titanium oxynitride films. The band gap decreases from 1.98 to 1.83 eV as nitrogen flow rate is increased from 55 to 100 sccm; it decreases from 1.93 to 1.79 eV as deposition time is increased from 80 to 140 min as more nitrogen incorporation results in higher negative potential of valence band N2p orbital. But it increases from 2.26 to 2.34 eV for titanium oxynitride films as sputtering pressure increases from 4.0 to 8.0 Pa.展开更多
Two-photon luminescence with near-infrared(NIR)excitation of upconversion nanoparticles(NPs)is of great importance in biological imaging due to deep penetration in high-scattering tissues,low auto-luminescence and goo...Two-photon luminescence with near-infrared(NIR)excitation of upconversion nanoparticles(NPs)is of great importance in biological imaging due to deep penetration in high-scattering tissues,low auto-luminescence and good sectioning ability.Unfortunately,common two-photon luminescence is in visible band with an extremely high exciation power density,which limits its application.Here,we synthesized NaYF_(4):Yb/Tm@NaYF_(4)upconversion NPs with strong twophoton NIR emission and a low excitation power density.Furthermore,NaYF_(4):Yb/Tm@NaYF_(4)@SiO_(2)@OTMS@F127 NPs with high chemical stability were obtained by a modified multilayer coating method which was applied to upconversion NPs for thefirst time.In addition,it is shown that the as-prepared hydrophillic upconversion NPs have great biocompatibility and kept stable for 6 hours during in vivo whole-body imaging.The vessels with two-photon luminescence were clear even under an excitation power density as low as 25mW/cm^(2).Vivid visualizations of capillaries and vessels in a mouse brain were also obtained with low background and high contrast.Because of cheaper instruments and safer power density,the NIR two-photon luminescence of NaYF_(4):Yb/Tm@NaYF_(4)upconversion NPs could promote wider application of two-photon technology.The modified multilayer coating method could be widely used for upconversion NPs to increase the stable time of the in vivo circulation.Our work possesses a great potential for deep imaging and imaging-guided treatment in the future.展开更多
To solve the problem of stray interference to star point target identification while a star sensor imaging to the sky, a study on space luminous environment adaptability of missile-borne star sensor was carried out. B...To solve the problem of stray interference to star point target identification while a star sensor imaging to the sky, a study on space luminous environment adaptability of missile-borne star sensor was carried out. By Plank blackbody radiation law and some astronomic knowledge, irradiancies of the stray at the star sensor working height were estimated. By relative astrophysical and mathematics knowledge, included angles between the star sensor optical axis point and the stray at any moment were calculated. The calculation correctness was verified with the star map software of Stellarium. By combining the upper analysis with the baffle suppression effect, a real-time model for space luminous environment of missile-borne star sensor was proposed. By signal-noise rate （SNR） criterion, the adaptability of missile-borne star sensor to space luminous environment was studied. As an example, a certain type of star sensor was considered when imaging to the starry sky on June 22, 2011 （the Summer Solstice） and September 20, 2011 （August 23 of the lunar year, last quarter moon） in Beijing. The space luminous environment and the adaptability to it were simulated and analyzed at the star sensor working height. In each period of time, the stray suppression of the baffle is analyzed by comparing the calculated included angle between the star sensor optical axis point and the stray with the shielded provided by system index. When the included angle is larger than the shielded angle and less than 90~, the stray is restrained by the baffle. The stray effect on star point target identification is analyzed by comparing the irradiancy of 6 magnitude star with that of the stray on star sensor sensitization surface. When the irradiancy of 6 magnitude star is 5 times more than that of the stray, there is no effect on the star point target identification. The simulation results are identicat with the actual situation. The space luminous environment of the missile-borne star sensor can be estimated real-timely by this model. The adaptability of the star sensor to space luminous environment can be analyzed conveniently. A basis for determining the relative star sensor indexes, the navigation star chosen strategy and the missile launch window can be provided.展开更多
Annealing nanodiamonds(ND) at high temperatures up to 1700 ℃ is a common method to synthesize carbon onions. The transformation from NDs to carbon onions is particularly interesting because of carbon onions' pote...Annealing nanodiamonds(ND) at high temperatures up to 1700 ℃ is a common method to synthesize carbon onions. The transformation from NDs to carbon onions is particularly interesting because of carbon onions' potential in the field of tribology and their application in ultra-charge/discharge devices. In this paper, a novel surface-enhanced Raman scattering technique that involves coating the sample with nanoscopic gold particles is proposed to characterize the NDs after different annealing treatments. Conventional Raman and surfaceenhanced Raman spectra were obtained, and the changes of peak parameters as the function of annealing temperature were evaluated. It was found that the widths of the D and the G peaks decreased with increasing annealing temperature, reflecting an improved order in the sp^2-hybridized carbon during the transformation from NDs to carbon onions. After annealing at 1700 ℃, the sp^2?carbon was highly ordered, indicating desirable electrical conductivity and lubricity. With increasing annealing temperature, the D peak showed a blue shift of almost30 cm^(-1), while the G peak merely shifted by 5 cm^(-1). For annealing temperatures above 1100 ℃, an increase of intensity ratio ID/IGwas observed. Compared to the uncoated area, red shifts of 0.5-2 cm^(-1) and of 5-9 cm^(-1) for the G and D peaks, respectively, were detected for the gold-coated area, which was due to the coupling of the plasmons and the phonons of the samples.展开更多
Compact microstrip antennas have recently received much attention due to the increasing demand of small antennas for personal communication equipment. The problem of achieving a wide impedance bandwidth for compact mi...Compact microstrip antennas have recently received much attention due to the increasing demand of small antennas for personal communication equipment. The problem of achieving a wide impedance bandwidth for compact microstrip antennas is becoming an important topic in microstrip antenna design. In this paper the design and development of a 2 × 1 array of a low cost slotted microstrip line fed shorted patch antenna (MFSPA) has been presented. Both the shorted patch and microstrip line feed network have air substrate. The material cost is thus reduced to a minimum. The array consists of two adjacent patches fed, using a simple microstrip T network. The impedance bandwidth of nearly 40%, covering the bandwidth requirement of 1750 MHz band is obtained. Also the antenna exhibits dual band operation. The cross polarization radiation in H-Plane observed with a single element antenna has been reduced considerably with 2 × 1 array. A peak antenna gain of 9.2 dBi is obtained with a small variation of 0.8 dBi. From the results obtained it is clear that the antenna array studied has a low cost fabrication and is suitable for applications in DCS mobile communication base station.展开更多
With the rapid advancement of terahertz technologies,electromagnetic interference(EMI)shielding materials are needed to ensure secure electromagnetic environments.Enormous efforts have been devoted to achieving highly...With the rapid advancement of terahertz technologies,electromagnetic interference(EMI)shielding materials are needed to ensure secure electromagnetic environments.Enormous efforts have been devoted to achieving highly efficient EMI shielding films by enhancing flexibility,lightweight,mechanical robustness,and high shielding efficiency.However,the consideration of the optical properties of these shielding materials is still in its infancy.By incorporating transparency,visual information from protected systems can be preserved for monitoring interior working conditions,and the optical imperceptibility allows nonoffensive and easy cover of shielding materials for both device and biology.There are many materials that can be applied to transparent EMI shields.In particular,two-dimensional transition metal carbide/nitrides(MXenes),possessing the advantages of superior conductivity,optical properties,favorable flexibility,and facile processibility,have become a great candidate.This work reviews the recent research on developing highly efficient and optically transparent EMI shields in a comprehensive way.Materials from MXenes,indium tin oxide,metal,carbon,and conductive polymers are covered,with a focus on the employment of MXene-based composites in transparent EMI shielding.The prospects and challenges for the future development of MXene-based transparent EMI shields are discussed.This work aims to promote the development of high-performance,optically transparent EMI shields for broader applications by leveraging MXenes.展开更多
基金financially supported by National Natural Science Foundation of China(No.U2241223)Pre-Research Foundation of China(No.909010203-202).
文摘Nano-twinned copper(nt-Cu),with a preferred orientation,is highly promising as interconnect materials in high-density advanced packaging due to its considerable mechanical strength,excellent electrical conductivity,and resistance to thermal migration.However,its application is impeded by sulfur-containing byproducts from the electroplating process,exacerbating the formation of Kirkendall voids within solder joints during thermal aging.Herein,through the incorporation of Zinc(Zn)into the nt-Cu layer,we develop a nt-Cu/Zn composite structure.Our findings provide the first definitive confirmation of the mechanism by which sulfur atoms migrate to the Cu_(3)Sn/nt-Cu interface through interstitial diffusion,thereby reducing the activation energy for vacancy formation.We further demonstrate that Zn effectively an-choring sulfur atoms,forming ZnS within the nt-Cu layer during heat treatment,which increases the vacancy formation energy and inhibits the development of Kirkendall voids.Remarkably,no Kirkendall voids are observed in the modified interconnects even after prolonged aging at 150℃ for 1000 h.The nt-Cu/Zn composite metallization layers significantly decrease the growth rate of interfacial intermetallic compounds by 33.6% and enhance the shear strength of solder interconnections to 228.9%.This research underscores the potential of nt-Cu in advanced electronic packaging,offering new pathways for improving the power density and reliability of electronic devices.
基金supported by the Research Grants Council of the Hong Kong Special Administrative Region of China(Grant Nos.HKU 17212824,HKU 17210522,HKU C7074-21G,HKU R7003-21,and HKU 17205321)the Innovation and Technology Commission of the Hong Kong SAR Government(Grant Nos.MHP/073/20 and MHP/057/21),and the Health@InnoHK program.
文摘Soliton molecules(SMs),bounded and self-assembled of particle-like dissipative solitons,exist with versatile mutual interactions and manifest substantial potential in soliton communication and optical data storage.However,controllable manipulation of the bounded molecular patterns remains challenging,as reaching a specific operation regime in lasers generally involves adjusting multiple control parameters in connection with a wide range of accessible pulse dynamics.An evolutionary algorithm is implemented for intelligent control of SMs in a 2μm ultrafast fiber laser mode locked through nonlinear polarization rotation.Depending on the specifications of the merit function used for the optimization procedure,various SM operations are obtained,including spectra shape programming and controllable deterministic switching of doublet and triplet SMs operating in stationary or pulsation states with reconfigurable temporal separations,frequency locking of pulsation SMs,doublet and SM complexes with controllable pulsation ratio,etc.Digital encoding is further demonstrated in this platform by employing the self-assembled characteristics of SMs.Our work opens up an avenue for active SM control beyond conventional telecom bands and brings useful insights into nonlinear science and applications.
基金Supported by National Natural Science Foundation of China(81874059 and 82102105)the Natural Science Foundation of Zhejiang Province(LQ22H160017)the China Postdoctoral Science Foundation(2021M702825).
文摘The second near-infrared window(NIR-II,900-1880 nm)overcomes critical limitations of visible(360-760 nm)and NIR-I(760-900 nm)imaging—including restricted penetration depth,low signal-to-back⁃ground ratio,and tissue autofluorescence—establishing its pivotal role for in vivo deep-tissue bioimaging.With exponential growth in NIR-II photodiagnosis and phototherapy research over the past decade,bibliometric analy⁃sis is essential to map the evolving landscape and guide strategic priorities.We systematically analyzed 2,491 NIR-II-related publications(2009-2023)from the Web of Science Core Collection,employing scientometric tools for distinct analytical purposes:(a)VOSviewer,SCImago Graphica,and Gephi for co-authorship and co-occur⁃rence network mapping;(b)the R bibliometrix package for tracking field evolution and identifying high-impact publications/journals.The search retrieved 2491 studies from 359 journals originating from 54 countries.The country with the most published articles is China.Chinese institutions drive>60%of publications,with Stanford University(USA)and Nanyang Technological University(Singapore)ranked as the top two institutions by re⁃search quality.International cooperation is becoming increasingly frequent.Fan Quli,Tang Benzhong and Dai Hongjie are the top 3 productive authors in this field.Keyword evolution identifies"photodynamic therapy"and"immunotherapy"as pivotal future directions.We summarize the most cited literatures and NIR-II imaging clini⁃cal trials.This study delineates the NIR-II research trajectory,highlighting China's leadership,intensifying glob⁃al collaboration,and interdisciplinary convergence.Future efforts should prioritize the novel NIR-II probe devel⁃opment for NIR-II imaging and clinical translation of photodynamic/immunotherapy combinational platforms.
基金Project supported by the“Pioneer”and“Leading Goose”R&D Program of Zhejiang Province(Grant No.2022C01053)the Key Research and Development Program of Zhejiang Province(Grant No.2021C01039)+1 种基金the National Natural Science Foundation of China(Grant No.62293493)the Natural Science Foundation of Zhejiang Province,China(Grant No.LQ21A050001)。
文摘Interlayer exchange coupling(IEC)plays a critical role in spin-orbit torque(SOT)switching in synthetic magnets.This work establishes a fundamental correlation between IEC and SOT dynamics within Co/Pt-based synthetic antiferromagnets and synthetic ferromagnets.The antiferromagnetic and ferromagnetic coupling states are precisely engineered through Ruderman-Kittel-Kasuya-Yosida(RKKY)interactions by modulating the Ir spacer thickness.Experimental results reveal that the critical switching current density exhibits a strong positive correlation with the IEC strength,regardless of the coupling type.A comprehensive theoretical framework based on the Landau-Lifshitz-Gilbert equation elucidates how IEC contributes to the effective energy barrier that must be overcome during SOT-induced magnetization switching.Significantly,the antiferromagnetically coupled samples demonstrate enhanced SOT efficiency,with the spin Hall angle being directly proportional to the antiferromagnetic exchange coupling field.These insights establish a coherent physical paradigm for understanding IEC-dependent SOT dynamics and provide strategic design principles for the development of energy-efficient next-generation spintronic devices.
文摘Mineralogical,geochemical and isotopic(Sr and Nd) studies on the recently reported ca. 124 Ma'anorogenic lamproite' dyke from the Palanpur area, Kutch seismogenic rift zone, northwestern India, are presented. We propose a new classification for the dyke as a damtjernite(ultramafic lamprophyre; UML)based on its porphyritic-panidiomorphic texture, abundance of phlogopite, presence of nepheline in the groundmass, and the composition of liquidus phases such as olivine, phlogopite, magnetite, and clinopyroxene(diopside). The Palanpur UML is primitive(Mg# =74-77),silica-undersaturated(SiO_2<40 wt.%),potassic to slightly sodic in nature, and is strikingly similar to the ～69 Ma UML dykes and sills of the Tethyan Indus suture zone, which are considered as the earliest yet known manifestations of the Deccan Large Igneous Province(LIP). Bulk-rock(^(87)Sr/^(86)Sr)_i(0.70460-0.70461) and ε_(N)d(t)(+2.56 to-0.69) of the Palanpur UML signify derivation from a slightly depleted mantle source similar to that of asthenospheric magmas such as OIB. This is further attested to by the high incompatible trace element ratios(viz., La/Ba, Nb/U, Nb/La and Ta/Yb) that are typical of plume-type magmas. However, the Neoproterozoic T_(DM) depleted mantle Nd model ages( ～655-919 Ma) also necessitate some involvement of a lithospheric mantle component in its genesis. High bulk-rock Fe_2 O_3~t and TiO_2 contents require the involvement of a fertile peridotitic mantle source, whereas high La/Yb(60-80) implies a control by residual garnet. Higher Rb/Sr and lower Ba/Rb suggest phlogopite as a residual phase and high Nb and lower La/Sm favour carbonatite, rather than silicate melt as metasomatising agent. Low degrees of partial melting of a primitive garnet lherzolite mantle can account for the observed REE patterns in the Palanpur UML. The Palanpur UML shares a temporal similarity to the Kerguelen plume-derived Rajmahal basalts and associated alkaline rocks from the eastern India. The tectonomagmatic significance of its emplacement during the mid-Cretaceous vis-a-vis various models involving the timing of eruption of the Deccan and the Rahmahal Traps and the rifting in the Kutch basin induced by far-field plate reorganization is evaluated.
基金Supported by Shanghai Special Foundation on Nanomaterials (0243nm305)
文摘A rapid and continuous method for production of LiFePO4/C nanoparticles in super heated water is described, wherein soluble starch was used as carbon precursor. The effects of pH, flow rate, temperature, and pressure on the formation of LiFePO4/C particles were investigated. Results showed that the pH value was the key factot on the formation of phase pure LiFePO4, which only formed at pH = 7; the LiFePO4/C-occurred as particles with about 70-200 nm size and LiFePO4 was covered by a thin carbon layer; higher flow rate, higher pressure, and lower temperature led to smaller particles of LiFePO4/C.
基金financially supported by the National Natural Science Foundation of China (Nos. 21835001, 51773080, 21674041, 51573068, and 21221063)Program for Changbaishan Scholars of Jilin Province, Jilin Province (No. 20160101305JC)the "Talents Cultivation Program" of Jilin University
文摘Near-infrared(NIR) nanoparticles(NPs) based on fluorescence resonance energy transfer(FRET) were prepared by coencapsulation of a red aggregation-induced emission(AIE) molecule, 2-(4-bromophenyl)-3-(4-(4-(diphenylamino)styryl)phenyl)fumaronitrile(TB), and a commercial NIR fluorescence dye, silicon 2,3-naphthalocyanine bis(trihexylsilyloxide)(NIR775) with an amphiphilic polymer poly(styrene-co-maleic anhydride)(PSMA). The surface of the NPs, PSMA@TB/NIR775, was modified with poly(ethylene glycol)(PEG) to increase the in vivo biocompatibility of the NPs. The PSMA@TB/NIR775 NPs showed a strong NIR(780 nm) narrow emission and excellent two-photon absorption property. Moreover, the NPs exhibited good monodispersity, stability, and low cytotoxicity.Under the excitation of a 1040 nm femtosecond(fs) laser, the emission peaks at 680 nm of TB and 780 nm of NIR775 excited by FRET were obtained. We utilized PSMA@TB/NIR775 NPs as fluorescent contrast agents for two-photon excited NIR microscopic imaging, and good NIR imaging effect of mouse brain vasculature was obtained with the imaging depth of about 150 μm. The FRET strategy by coencapsulating AIE molecule and NIR dye will be helpful in preparing more narrow emission NIR probes for deep-tissue biological imaging.
文摘Nanocomposite Ti-Si-N thin films have been deposited on Si （100） substrate by direct current/radio frequency （DC/RF） magnetron sputtering. The effect of varying deposition parameters on the structure and mechanical properties of Ti-Si-N films has been investigated by characterization techniques such as X-ray dif- fraction （XRD）, field emission scanning electron microscopy （FE-SEM）, atomic force microscopy （AFM） and nanoindentation, respectively. XRD analysis of the thin films exhibit all （111）, （200） and （220） peaks initially with varying sputtering pressure, but （111） peak dominates at higher sputtering pressure. The crystallite size calculated from XRD peaks shows that it increases with increasing sputtering pressure. Microstructural analy- sis reveals that the dense blurred grains transform into uniform grains in the films and shows porosity with increasing sputtering pressure. The surface roughness of the Ti-Si-N films increases with varying sputtering pressure. The hardness and Youngrs modulus values of Ti-Si-N films are 33.7 and 278.6 GPa, respectively, with 0.7 Pa sputtering pressure but it decreases with further increase in sputtering pressure due to an increase in porosity of the films.
基金financial supports from the National Natural Science Foundation of China(Grant No.81927805)Shenzhen Municipal Science and Technology Plan Project,China(Grant No.JCYJ20160427183803458)。
文摘Current gradient-index(GRIN)lens based proximal-driven intracoronary optical coherence tomography(ICOCT)probes consist of a spacer and a GRIN lens with large gradient constant.This design provides great flexibility to control beam profiles,but the spacer length should be well controlled to obtain desired beam profiles and thus it sets an obstacle in mass catheter fabrication.Besides,although GRIN lens with large gradient constant can provide tight focus spot,it has short depth of focus and fast-expanded beam which leads to poor lateral resolution for deep tissue.In this paper,a type of spacer-removed probe is demonstrated with a small gradient constant GRIN lens.This design simplifies the fabrica-tion process and is suitable for mass production.The output beam of the catheter is a narrow nearly collimated light beam,referred to as pencil beam here.The full width at half maximum beam size varies from 35.1μm to 75.3μm in air over 3-mm range.Probe design principles are elaborated with probe/catheter fabrication and performance test.The in vivo imaging of the catheter was verified by a clinical ICOCT system.Those results prove that this novel pencil-beam scanning catheter is potentially a good choice for ICOCT systems.
基金the financial support from Science Foundation Ireland (SFI) (No. 15/RP/B3208)‘111’ project by the State Administration of Foreign Experts Affairs and the Ministry of Education of China (No. B07014)。
文摘It has been nearly 50 years since the first glimpse of the relationship between myopia and peripheral refractive errors. According to experiments on both animals and humans, the eyes with hyperopic peripheral vision appear to be at higher risk of developing myopia than those with myopic peripheral refractive errors. Despite the first measurement of peripheral refraction being achieved by a modified manual optometer, the concept of emmetropization triggered a rapidly increasing number of studies on peripheral aberrations. Not only the horizontal off-axis aberrations but also the meridional aberrations at different angles are measured by researchers during the development of peripheral aberrations measuring techniques. According to the differences among the working principles, a variety of techniques have been adopted for performing such measurements. The methods developed to realize the high-performance measurement involve the subject cooperating actively by rotating the head or eyes, the rotation of the whole optical path, and the combination of measurements of many light paths. This paper provides a review of the peripheral aberrations measuring techniques and their current status. This article also highlights the development trend of the measuring techniques of peripheral aberrations and practical applications of peripheral aberration measurements, such as the control of the accommodation, the measuring time, and the dynamic range problem of the wavefront sensor. Although wavefront sensing peripheral measurement is widely recognized for its capability to reveal both lower-order aberrations and higher-order aberrations, the efficiency of an autorefractometer is incomparable. The current study reveals that the most widely used peripheral aberration measurement methods are the use of an open field autorefractometer and Hartman-shack wavefront sensor-based techniques.
基金Supported by the National Natural Science Foundation of China under Grant No 20325516, and the Fund of National Grade Key laboratory of Tunable Laser Technology under Grant No 51472040JW1101.
文摘CaS phosphor activated with Dy ions is prepared by the solid-state diffusion method. The phosphor is characterized by x-ray powder diffraction, thermogravimetric analysis and photoiuminescence. Defect centres formed in CaS：Dy are studied using the technique of electron spin resonance. The thermoluminescence glow curve shows peaks at around 117℃ and 345℃. Irradiated CaS：Dy exhibits ESR lines due to defect centres. The thermal annealing behaviour of one of the defect centres appears to correlate with the TL peaks at 117℃ and 345℃. This centre is characterized by an isotropic g-value of 2.0035 and is assigned to an F^＋ centre.
基金supported by National Natural Science Foundation of China(61735016)Zhejiang Provincial Natural Science Foundation of China(LR17F050001).
文摘Compared with visible light,near infrared(NIR)light has deeper penetration in biological tisues.Three-photon fuorescence microscopy(3PFM)can effectively utilize the NIR excitation to obtain high-contrast images in the deep tisue.However,the weak three photon fluorescence signals may be not well presented in the traditional fuorescence intensity imaging mode.Fluorescence lifetime of certain probes is insensitive to the intensity of the excitation laser.Moreover,fluorescence lifetimne imaging microscopy(FLIM)can detect weak signals by utilizing time correlated single photon counting(TCSPC)technique.Thus,it would be an improved strategy to combine the 3PFM imaging with the FLIM together.Herein,DCDPP-2TPA,a novel agegation-induced emission luminogen(AIEgen),was adopted as the fluorescent probes.The three-photon absorption cros-section of the AlEgen,which has a deep-red fluorescence emission,was proved to be large.DCDPP-2TPA nanoparticles were synthesized,and the three photon fluorescence lifetime of which was measured in water.Moreover,in vrivo thre-photon fuorescence lifetime microscopic imaging of a craniotomy mouse was conducted via a home made optical system.High contrast cerebrovascular images of different vertical depths were obtained and the maximun depth was about 600 pumn.Even reaching the depth of 600 pum,tiny capillary vessels as small as 1.9 pum could still be distinguished.The three photon fuorescence lifetimes of the capillaries in some representative images were in accord with that of DCDPP-2TPA nanoparticles in water.A vivid 3D reconstruction was further organized to present a wealth of lifetime information.In the future,the combination strategy of 3PFM and FLIM could be further applied in the brain functional imaging.
基金the National Natural Science Foundation of China(Grant Nos.51575389 and 51761135106)the National Key Research and Development Program of China(Grant No.2016YFB1102203)+1 种基金the State Key Laboratory of Precision Measuring Technology and Instruments(Pilt1705)the‘111’Project of the State Administration of Foreign Experts Affairs and the Ministry of Education of China(Grant No.B07014).
文摘As an important wide-bandgap semiconductor,gallium nitride(GaN)has attracted considerable attention.This paper describes the use of confocal Raman spectroscopy to characterize undoped GaN,n-type GaN,and p-type GaN through depth profiling using 405-,532-,and 638-nm wavelength lasers.The Raman signal intensity of the sapphire substrate at different focal depths is studied to analyze the depth resolution.Based on the shift of the E2 H mode of the GaN epitaxial layer,the interfacial stress for different types of GaN is characterized and calculated.The results show that the maximum interfacial stress appears approximately at the junction of the GaN and the sapphire substrate.Local interfacial stress analysis between the GaN epitaxial layer and the substrate will be very helpful in furthering the applications of GaN devices.
基金supported by the Council of Scientific and Industrial Research (CSIR)(Grant No.03(1148)/09/EMR-II)the Defence Research and Development Organisation (DRDO) (Grant No.ERIP/ER/0800354/M/011125)
文摘The objective of the present work is to investigate the effect of various sputtering parameters such as nitrogen flow rate, deposition time and sputtering pressure on structural, wettability and optical properties of titanium oxynitride films deposited on glass substrate by reactive magnetron sputtering. The X-ray diffraction graphs of titanium oxynitride films show evolution of various textures of TiO=N and TiN phases with increasing nitrogen flow rate and deposition time, but an increase in sputtering pressure from 4.0 to 8.0 Pa results in decline of various textures observed for TiO=Ny and TiN phases. The stress and strain calculated by sin2~ method are compressive, which decrease with increasing nitrogen flow rate from 55 to I00 sccm （standard cubic centimeter per minute） and increase with increasing deposition time from 80 to I40 min due to atomic penning effect and increasing thickness of the deposited films. The titanium oxynitride films have contact angle values above 90 deg., indicating that films are hydrophobic. The maximum contact angle of I09.1 deg. is observed at deposition time of 140 min. This water repellent property can add value to potential protective, wear and corrosion resistant application of titanium oxynitride films. The band gap decreases from 1.98 to 1.83 eV as nitrogen flow rate is increased from 55 to 100 sccm; it decreases from 1.93 to 1.79 eV as deposition time is increased from 80 to 140 min as more nitrogen incorporation results in higher negative potential of valence band N2p orbital. But it increases from 2.26 to 2.34 eV for titanium oxynitride films as sputtering pressure increases from 4.0 to 8.0 Pa.
基金This work is partially supported by National Key Research and Development Program of China(Grant No.2018YFC1407503)the Fundamental Research Funds for the Central Universities(2018FZA5001)The National Natural Science Foundation of China(Grant No.11621101).
文摘Two-photon luminescence with near-infrared(NIR)excitation of upconversion nanoparticles(NPs)is of great importance in biological imaging due to deep penetration in high-scattering tissues,low auto-luminescence and good sectioning ability.Unfortunately,common two-photon luminescence is in visible band with an extremely high exciation power density,which limits its application.Here,we synthesized NaYF_(4):Yb/Tm@NaYF_(4)upconversion NPs with strong twophoton NIR emission and a low excitation power density.Furthermore,NaYF_(4):Yb/Tm@NaYF_(4)@SiO_(2)@OTMS@F127 NPs with high chemical stability were obtained by a modified multilayer coating method which was applied to upconversion NPs for thefirst time.In addition,it is shown that the as-prepared hydrophillic upconversion NPs have great biocompatibility and kept stable for 6 hours during in vivo whole-body imaging.The vessels with two-photon luminescence were clear even under an excitation power density as low as 25mW/cm^(2).Vivid visualizations of capillaries and vessels in a mouse brain were also obtained with low background and high contrast.Because of cheaper instruments and safer power density,the NIR two-photon luminescence of NaYF_(4):Yb/Tm@NaYF_(4)upconversion NPs could promote wider application of two-photon technology.The modified multilayer coating method could be widely used for upconversion NPs to increase the stable time of the in vivo circulation.Our work possesses a great potential for deep imaging and imaging-guided treatment in the future.
文摘To solve the problem of stray interference to star point target identification while a star sensor imaging to the sky, a study on space luminous environment adaptability of missile-borne star sensor was carried out. By Plank blackbody radiation law and some astronomic knowledge, irradiancies of the stray at the star sensor working height were estimated. By relative astrophysical and mathematics knowledge, included angles between the star sensor optical axis point and the stray at any moment were calculated. The calculation correctness was verified with the star map software of Stellarium. By combining the upper analysis with the baffle suppression effect, a real-time model for space luminous environment of missile-borne star sensor was proposed. By signal-noise rate （SNR） criterion, the adaptability of missile-borne star sensor to space luminous environment was studied. As an example, a certain type of star sensor was considered when imaging to the starry sky on June 22, 2011 （the Summer Solstice） and September 20, 2011 （August 23 of the lunar year, last quarter moon） in Beijing. The space luminous environment and the adaptability to it were simulated and analyzed at the star sensor working height. In each period of time, the stray suppression of the baffle is analyzed by comparing the calculated included angle between the star sensor optical axis point and the stray with the shielded provided by system index. When the included angle is larger than the shielded angle and less than 90~, the stray is restrained by the baffle. The stray effect on star point target identification is analyzed by comparing the irradiancy of 6 magnitude star with that of the stray on star sensor sensitization surface. When the irradiancy of 6 magnitude star is 5 times more than that of the stray, there is no effect on the star point target identification. The simulation results are identicat with the actual situation. The space luminous environment of the missile-borne star sensor can be estimated real-timely by this model. The adaptability of the star sensor to space luminous environment can be analyzed conveniently. A basis for determining the relative star sensor indexes, the navigation star chosen strategy and the missile launch window can be provided.
基金supported by National Natural Science Foundation of China (No. 51575389, 51761135106, 51511130074)National Key Research and Development Program of China (2016YFB1102203)State key laboratory of precision measuring technology and instruments (Pilt1705)
文摘Annealing nanodiamonds(ND) at high temperatures up to 1700 ℃ is a common method to synthesize carbon onions. The transformation from NDs to carbon onions is particularly interesting because of carbon onions' potential in the field of tribology and their application in ultra-charge/discharge devices. In this paper, a novel surface-enhanced Raman scattering technique that involves coating the sample with nanoscopic gold particles is proposed to characterize the NDs after different annealing treatments. Conventional Raman and surfaceenhanced Raman spectra were obtained, and the changes of peak parameters as the function of annealing temperature were evaluated. It was found that the widths of the D and the G peaks decreased with increasing annealing temperature, reflecting an improved order in the sp^2-hybridized carbon during the transformation from NDs to carbon onions. After annealing at 1700 ℃, the sp^2?carbon was highly ordered, indicating desirable electrical conductivity and lubricity. With increasing annealing temperature, the D peak showed a blue shift of almost30 cm^(-1), while the G peak merely shifted by 5 cm^(-1). For annealing temperatures above 1100 ℃, an increase of intensity ratio ID/IGwas observed. Compared to the uncoated area, red shifts of 0.5-2 cm^(-1) and of 5-9 cm^(-1) for the G and D peaks, respectively, were detected for the gold-coated area, which was due to the coupling of the plasmons and the phonons of the samples.
基金the National Natural Science Foundation of China(81672520,81870484,61975172,and 82001874,used for procurement of materials and labor cost)Science and Technology Planning Project of Zhejiang(2019C03089,used for procurement of materials)Zhejiang Provincial Natural Science Foundation of China(LR17F050001,used for procurement of materials).
文摘Compact microstrip antennas have recently received much attention due to the increasing demand of small antennas for personal communication equipment. The problem of achieving a wide impedance bandwidth for compact microstrip antennas is becoming an important topic in microstrip antenna design. In this paper the design and development of a 2 × 1 array of a low cost slotted microstrip line fed shorted patch antenna (MFSPA) has been presented. Both the shorted patch and microstrip line feed network have air substrate. The material cost is thus reduced to a minimum. The array consists of two adjacent patches fed, using a simple microstrip T network. The impedance bandwidth of nearly 40%, covering the bandwidth requirement of 1750 MHz band is obtained. Also the antenna exhibits dual band operation. The cross polarization radiation in H-Plane observed with a single element antenna has been reduced considerably with 2 × 1 array. A peak antenna gain of 9.2 dBi is obtained with a small variation of 0.8 dBi. From the results obtained it is clear that the antenna array studied has a low cost fabrication and is suitable for applications in DCS mobile communication base station.
基金This work was supported by the National Key R&DProgram of China(No.2021YFB3502500)the NationalNatural Science Foundation of China(Nos.22205131,22375115)+6 种基金the Natural Science Foundation of ShandongProvince(Nos.2022HYYQ-014 ,ZR2016BM16)the New 20 Funded Programs for Universities of Jinan(2021GXRC036)Provincial Key Research and Develop-ment Program of Shandong(2021ZLGX01)the Disci-pline Construction Expenditure for Distinguished Young Scholars of Shandong University(31370089963141)Shenzhen Municipal Special Fund for Guiding LocalScientific and Technological Development(China,2021Szvup071)Qilu Young Scholar Program ofShandong University(No.31370082163127)The authorsacknowledge the assistance of the Shandong UniversityTesting and Manufacturing Center for Advanced Materi-als and the support of the Xiaomi Foundation/XiaomiYoung Talents Program.
文摘With the rapid advancement of terahertz technologies,electromagnetic interference(EMI)shielding materials are needed to ensure secure electromagnetic environments.Enormous efforts have been devoted to achieving highly efficient EMI shielding films by enhancing flexibility,lightweight,mechanical robustness,and high shielding efficiency.However,the consideration of the optical properties of these shielding materials is still in its infancy.By incorporating transparency,visual information from protected systems can be preserved for monitoring interior working conditions,and the optical imperceptibility allows nonoffensive and easy cover of shielding materials for both device and biology.There are many materials that can be applied to transparent EMI shields.In particular,two-dimensional transition metal carbide/nitrides(MXenes),possessing the advantages of superior conductivity,optical properties,favorable flexibility,and facile processibility,have become a great candidate.This work reviews the recent research on developing highly efficient and optically transparent EMI shields in a comprehensive way.Materials from MXenes,indium tin oxide,metal,carbon,and conductive polymers are covered,with a focus on the employment of MXene-based composites in transparent EMI shielding.The prospects and challenges for the future development of MXene-based transparent EMI shields are discussed.This work aims to promote the development of high-performance,optically transparent EMI shields for broader applications by leveraging MXenes.
