Observation of Blue-Light Emission Band from Eu-Doped Ta₂O₅Thin Films Prepared Using Co-Sputtering

In this paper, we report on the first observation of blue-light emission bands from europium-doped tantalum pentoxide (Ta2O5:Eu) thin films prepared using a simple co-sputtering method. We prepared four specimens from one as-deposited sample, and we subsequently annealed them at 700&degC, 800&degC, 900&degC, or 1000&degC for 20 min. Four remarkable photoluminescence (PL) peaks at wavelengths of 600, 620, 650, and 700 nm due to the 5D0→7F1, 5D0→7F2, 5D0→7F3, and 5D0→7F4 transitions of Eu3+ were observed from all the specimens, and blue PL peaks around a wavelength of 450 nm were also observed from the specimens annealed at 800&degC, 900&degC, and 1000&degC. The blue PL peaks seem to be originated from the 4f65d1→4f7 transition of Eu2+. Both Eu3+ and Eu2+ ions seem to exist in our Ta2O5:Eu co-sputtered thin films annealed at temperatures from 800&degC to 1000&degC. Such Ta2O5:Eu co-sputtered thin films seem to be used as multi-functional coating films having both anti-reflection and down-conversion effects for realizing high-efficiency silicon solar cells.

Shear band evolution and acoustic emission characteristics of sandstone containing non-persistent flaws

Direct shear tests were conducted on sandstone specimens under different constant normal stresses to study the coalescence of cracks between non-persistent flaws and the shear sliding characteristics of the shear-formed fault.Digital image correlation and acoustic emission(AE)techniques were used to monitor the evolution of shear bands at the rock bridge area and microcracking behaviors.The experimental results revealed that the shear stresses corresponding to the peak and sub-peak in the stressdisplacement curve are significantly affected by the normal stress.Strain localization bands emerged at both the tip of joints and the rock bridge,and their extension and interaction near the peak stress caused a surge in the AE hit rate and a significant decrease in the AE b value.Short and curvilinear strain bands were detected at low normal stress,while high normal stress generally led to more microcracking events and longer coplanar cracks at the rock bridge area.Furthermore,an increase in normal stress resulted in a higher AE count rate and more energetic AE events during friction sliding along the shearformed fault.It was observed that the elastic energy released during the crack coalescence at the prepeak stage was much greater than that released during friction sliding at the post-peak stage.More than 75%of AE events were located in the low-frequency band(0e100 kHz),and this proportion continued to rise with increasing normal stress.Moreover,more AE events of low AF value and high RA value were observed in specimens subjected to high normal stress,indicating that greater normal stress led to more microcracks of shear nature.

Clinical relevance of fluorodeoxyglucose positron emission tomography/computed tomography and magnifying endoscopy with narrow band imaging in decision-making regarding the treatment strategy for esophageal squamous cell carcinoma

BACKGROUND Recent advances in endoscopic technology,especially magnifying endoscopy with narrow band imaging(ME-NBI)enable us to detect superficial esophageal squamous cell carcinoma(ESCC),but determining the appropriate method of resection,endoscopic resection(ER)vs surgical resection,is often challenging.Recently,several studies have reported that 18F-fluorodeoxyglucose positron emission tomography(FDG-PET)is a useful indicator for decision-making regarding treatment for superficial ESCC.Although,there are not enough reports on association between FDG-PET uptake and clinicopathological characteristics of superficial ESCC.And,there are not enough reports on evaluating the usefulness of combination of FDG-PET and ME-NBI for determining the treatment strategy for superficial ESCC.This study evaluated clinical relevance of FDG-PET and ME-NBI in decision-making regarding the treatment strategy for ESCC.AIM To investigate the association between FDG uptake and the clinicopathological characteristics of superficial ESCC and its usefulness of combination of FDG-PET and ME-NBI for determining the treatment strategy for superficial ESCC.METHODS A database of all patients with superficial ESCC who had undergone both MENBI and FDG-PET for pre-treatment staging at Aichi Cancer Center Hospital between January 2008 and November 2018 was retrospectively analyzed.FDG uptake was defined positive or negative whether the primary lesion was visualized or could be distinguished from the background,or not.The invasion depth of ESCC was classified according to the Japan Esophageal Society.Primary endpoint is to evaluate the association between FDG uptake and clinicopathological characteristics of superficial ESCC.Secondary endpoint is to investigate the efficacy of combination of FDG-PET and ME-NBI for determining the treatment strategy for superficial ESCC.RESULTS A total of 82 lesions in 82 patients were included.FDG-PET showed positive uptake in 29(35.4%)lesions.Univariate analysis showed that uptake of FDG-PET had significant correlations with circumferential extension(P=0.014),pathological depth of tumor invasion(P<0.001),infiltrative growth pattern(P<0.001),histological grade(P=0.002),vascular invasion(P=0.001),and lymphatic invasion(P<0.001).On multivariate analysis,only depth of tumor invasion was independently correlated with FDG-PET/computed tomography visibility(P=0.018).The sensitivity,specificity,positive predictive value(PPV),negative predictive value(NPV),and accuracy of Type B2 in ME-NBI for the invasion depth of T1a muscularis mucosae and T1b upper submucosal layer were 68.4%/79.4%/50.0%/89.3%/76.8%,respectively,and those of Type B3 for the depth of T1b middle and deeper submucosal layers(SM2 and SM3)were 46.7%/100%/100%/89.3%/90.2%,respectively.On the other hand,those of FDGPET for SM2 and SM3 were 93.3%/77.6%/48.2%/98.1%/80.5%,respectively,whereas,if the combination of positive FDG uptake and type B2 and B3 was defined as an indicator for radical esophagectomy or definitive chemoradiotherapy,the sensitivity,specificity,PPV,NPV,and accuracy were 78.3%/91.5%/78.3%/91.5%/87.8%,respectively.CONCLUSION FDG uptake was correlated with the invasion depth of superficial ESCC.Combined use of FDG-PET and ME-NBI,especially with the microvascular findings of Type B2 and B3,is useful to determine whether ER is indicated for the lesion.

Unidentified Infrared Discrete Emission Bands

Unidentified Infrared emission bands (UIBs) are infrared discrete emissions from circumstellar regions, interstellar media (ISM), star-forming regions, and extragalactic objects for which the identity of the emitting materials is unknown. The main infrared features occur around peaks at 3.3, 6.2, 7.7, 8.6, 11.2, and 12.7 μm with the photon’s rest energy at the peaks 0.376, 0.200, 0.161, 0.144, 0.111, and 0.098 eV, respectively. The UIB emission phenomenon has been studied for about forty five years. The prevailing hypothesis is that the materials responsible for UIB are polycyclic aromatic hydrocarbon (PAH) molecules. PAHs are thought to be one of the main forms in which carbon exists in space. And yet, not a single member of this group of compounds had been identified in space definitively until now [1]. In frames of Hypersphere World-Universe Model (WUM), we introduced Dark Matter (DM) particles, named DIONs, with the rest energy 0.199 eV and an energy density of 68.8% of the total energy density of the World. DIONs compose Outer shells of DM Supercluster’s Cores—the main objects of the World [2]. In this paper, we give an explanation of UIB emission based on the self-annihilation of DM particles DIONs and biDIONs (DIONs pairs) with a rest energy about 0.38 eV that depends on the binding energy. To the best of our knowledge, WUM is the only cosmological model in existence that is consistent with UIB emission phenomenon.

Band Edge Emission Improvement by Energy Transfer in HybridⅢ-Nitride/Organic Semiconductor Nanostructure

GaN nanorods are fabricated using inductively coupled plasma etching with Ni nano-island masks. The poly [2- methoxy-5-（2-ethyl）hexoxy-l,4-phenylenevinylene] （MEH-PPV）/GaN-nanorod hybrid structure is fabricated by depositing the MEH-PPV film on the GaN nanorods by using the spin-coating process. In the hybrid structure, the spatial separation is minimized to achieve high-emciency non-radiative resonant energy transfer. Optical properties of a novel device consisting of MEH-PPV/GaN-nanorod hybrid structure is studied by analyzing photoluminescenee （PL） spectra. Compared with the pure GaN nanorods, the PL intensity of the band edge emission of GaN in the MEH-PPV/GaN-nanorods is enhanced as much as three times, and the intensity of the yellow band is suppressed slightly. The obtained results are analyzed by energy transfer between the GaN nanorods and the MEH-PPV. An energy transfer model is proposed to explain the phenomenon.

Observation of Violet-Light Emission Band for Thulium-Doped Tantalum-Oxide Films Produced by Co-Sputtering

We prepared thulium-doped tantalum (V) oxide (Ta2O5:Tm) thin films using co-sputtering of two Tm2O3 pellets and a Ta2O5 disc, and we observed photoluminescence (PL) peaks not only around a wavelength of 800 nm due to the 3H4→3H6 transition of Tm3+ but also around a wavelength of 400 nm (violet) from the films after annealing for the first time. Comparatively narrow PL peaks around the wavelength of 400 nm were observed from the films annealed at 800°C and 900°C for 20 min. The peak intensity from the film annealed at 900°C was approximately four-times stronger than that from the film annealed at 800°C. The origin of the 400-nm peaks seems to be the same as our non-doped Ta2O5 thin films deposited using radio-frequency sputtering because we observe PL peaks around 400 - 430 nm from the Ta2O5 films. Such a Ta2O5:Tm co-sputtered thin film seems to be used as a multi-functional coating film having both anti-reflection and down-conversion effects for realizing a high-efficiency silicon solar cell.

Origion of Band-like and Atom-like Features of the Valence Band Auger Emission from Thansition Metals

The occurrence of both band-like and atom-like Auger spectra involving valence band electron of d-transition metals is discussed based on the two-step model of the Auger electron emission, i.e.an initial core-hole is first generated and the Auger transition occurs between the core-hole andthe valence states, The occupied vaIence states relax to screen the core-hole which results in a redistribution of the valence electrons, The electronic states concerned by the Auger transitionare calculated by the FLAPW method. There is a clear relation between band-like and atom-like features of the spectra and the different responses of these metals to the existence of a core-hole.

CE/FCC认证中Spectrum Emission Mask与Band Edge的测试解析

在CE/FCC认证中,无线通信终端的杂波信号都是重点测试指标,而相邻信道的杂波信号最不容易察觉,所以在每一个国家都有着严格的规定,但是检测的方式却有些不大一样。Spectrum Emission Mask(频谱发射模板)测量单个信道的杂波信号是否有超出规定的框架范围,而Band Edge(频带边沿)是检查整个频宽高低信道的杂波信号是否有超出规定的框架范围。

Fluorescence Emission Centres and the Corresponding Infrared Fluorescence Saturation in a Bismuth-Doped Silica Fibre

We investigate the fluorescence characteristics of bismuth doped silica fibres with and without A1 co-dopant which are fabricated by means of modified chemical vapour deposition （MCVD） technique, and find that the fluorescences in the red region （centred around 750nm） and in the infrared region （centred around llOOnm） may originate from different emission sites in the fibre. Strong upconversion phenomena are observed in both Al-codoped and non A1 codoped bismuth fibres when the fibres are excited by an acoustic-optic Q-switched Nd：YVO4 laser. Both the aspects indicate that the upper energy level absorption reported in the work of the bismuth doped silica fibre lasers may result from the fluorescence emission sites that are not responsible for the infrared emission. It is thus expected that optimizing the compositions and the fabrication conditions of the fibre and then transferring more fluorescence emission centres are helpful for the infrared emission.

A possible UL Fseismice lectro-magnetic emission

A possible electro-magnetic emission (EME) associated with earthquakes are presented in the paper throughanalysis of the anomaly EME in ultra-low frequency range (ULF) observed at some sites before two earthquakesnear Beijing and the comparison with similar signals observed prior to the 1988 Armenia and 1989 Loma Prietaearthquakes. The anomaly features are as follows: ①the anomalous disturbances occur discontinuously severaldays before earthquakes and signal frequencies are higher remarkably than geomagnetic pulsation and magneticdisturbances during magnetic storms in ULF band and at least not lower than 1 Hz; ②similar signals are ohserved by similar observation systems at same site for the same earthquake ; ③the anomaly occurrence times andfrequencies at sites near the epicenter are earlier and higher respectively than that at farther sites; ④the signalenergy distribution in different frequency ranges may not be the same and the signal magnitudes may be relatedto earthquake magnitudes and greater earthquake may emit stronger EME signals; ⑤there may be a seismicmagnitude threshold for observable ULF EME anomalies and if smaller earthquakes possess of EME signals also,they may not be observed by the present observation system.

1.27 μm O_(2)(a^(1)Δ g)气辉临边观测辐射传 输特性

1.27μm波段的O_(2)(a^(1)Δg)气辉辐射具有辐射信号强、空间跨度大、自吸收效应弱等诸多内禀优势,是临近空间大气遥感的重要目标源,对于中高层大气的动力学及热学特性研究,全球温室气体探测,以及臭氧浓度三维层析等卫星遥感具有重要的科学意义和应用价值。首先基于O_(2)(a^(1)Δg)光化学反应模型,研究了O_(2)(a^(1)Δg)气辉的产生机制及湮灭机理,在此基础上,计算得到了O_(2)(a^(1)Δg)气辉体辐射率廓线,并基于HITRAN数据库给出的谱线强度及爱因斯坦系数,提出了两种计算O_(2)(a^(1)Δg)气辉光谱分布的方法。采用最新的分子光谱参数、光化学反应速率常数及F10.7太阳紫外通量等参数,结合光化学反应模型计算得到的O_(2)(a^(1)Δg)气辉体辐射率廓线信息,借助逐线积分算法,建立了1.27μm O_(2)(a^(1)Δg)气辉临边观测辐射传输理论模型,并分析了自吸收效应对不同临边观测高度处气辉辐射光谱强度的影响。然后,利用剥洋葱算法,对大气图像扫描成像吸收光谱仪(SCIAMACHY)在临边观测模式下测得的O_(2)分子近红外大气带的气辉辐射信号进行处理得到了目标层O_(2)(a^(1)Δg)气辉辐射光谱,并通过谱积分算法反演得到了O_(2)(a^(1)Δg)气辉的体辐射率廓线信息。最后通过对比气辉临边观测辐射传输理论模型计算得到的以及SCIAMACHY仪器测量反演得到的1.27μm O_(2)(a^(1)Δg)辐射光谱及体辐射率廓线信息,验证1.27μm O_(2)(a^(1)Δg)气辉临边观测辐射传输理论模型的可靠性与合理性。基于比对结果,对O_(2)(a^(1)Δg)气辉临边辐射强度和体辐射率的影响因素进行了分析。分析结果表明,在50 km以上的高空区域,理论计算结果与卫星实测结果吻合性较好,而随着海拔高度的降低,两者的偏差逐渐增大,这是因为在临边观测模式下,中低空区域的卫星遥感信号受自吸收效应及大气散射效应影响严重。此外,与HITRAN数据库给出的谱线强度参数相比,基于爱因斯坦系数建立的O_(2)(a^(1)Δg)气辉临边辐射模型与卫星实测结果更加吻合。1.27μm O_(2)(a^(1)Δg)气辉临边观测辐射传输理论模型的建立,对于临近空间大气遥感,奠定了理论基础。

原煤与型煤损伤破坏的应力声发射变化特征对比研究

在研究声发射特征与煤样和断裂的关系时,原煤和型煤都可用作实验样本。大多煤层材质较软,制造标准的原煤试样较为困难,因此使用型煤作为研究样本的实验较普遍,但型煤改变了煤的原始结构,影响了其物理和力学性质,使用型煤替代原煤作为实验样本的适用性一直是学术界讨论的焦点。此外,目前对于原煤和型煤在假三轴压缩实验中表现出的声发射特征差异的研究相对有限。针对上述问题,开展了原煤和型煤假三轴压缩声发射实验,从力学性能、断裂模式和声发射时空演化、频带能量分布、非线性特征等方面着重讨论和分析。结果表明:加载过程中释放的声发射能量和峰值应力总能量与煤样强度密切相关,原煤主要为剪切和拉伸混合破坏模式,型煤主要为拉伸轴裂破坏模式;煤样的声发射位置分别对应其宏观破裂形态,但发生时间和空间分布不同;在峰前加载阶段,原煤的声发射信号相对较少,而型煤的声发射响应剧烈,并在峰值应力时刻达到最大值;通过小波包分析得到型煤的声发射频带能量分布范围小于原煤,原煤的声发射信号频率主要集中在10~120 kHz,而型煤的声发射信号仅在0~100 kHz频率范围内活跃,说明型煤的微破裂规模大于原煤;原煤和型煤的波形能量90%活跃在0~150 kHz;当加载试样接近失稳破坏时,即加载应力为峰值应力的99%左右时,原煤和型煤声发射信号的Hurst指数均大于0.5,表明声发射时间序列与加载过程具有长期相关性。

Study of Structural, Optical, Electrical and Dielectric Properties of Gd-Doped ZnO Composites Synthesized by Solid State Reaction Method

In this manuscript, we are reporting structural, bonding, optical, dielectric, and electrical properties of Gd-doped ZnO composite samples (Zn1−xGdxO, x = 0, 0.05, 0.10) prepared by solid-state reaction method. XRD spectra confirm the wurtzite hexagonal phase with a grain size distribution of 42 - 47 nm. The FT-IR spectra confirm bonding behavior like Zn-O, O=C=O, and O-H stretching modes. FESEM micrographs show that the grains of crystallites possess nearly spherical morphology. Optical absorption spectra confirm that the optical band gap decreases systematically from 3.19 eV to 3.15 eV for x = 0.0 to x = 0.10 samples. For all samples, PL spectra exhibited near-band emission, blue emission, and green emission peaks. The dielectric constant decreases as the applied frequency increases. Hall effect results show that with increasing doping concentration of Gd, mobility and resistivity increase while bulk concentration decreases. Current-Voltage study shows that current increases when temperature is increased. Rare earth-doped ZnO is potential material used for optoelectronics and spintronics device applications. Properties of Gd-doped ZnO are studied by various research groups, but dielectric studies are limitedly reported. Therefore, the present research work aims to study the change of electrical, optical, and dielectric properties of Gd-doped ZnO for device applications.

铁路机车电台设备电磁发射测量专用带阻滤波器设计

铁路无线通信设备发射的信号往往较强,因而在电磁发射测量过程中,极易导致测量接收机出现乱真响应。基于450 MHz无线列调机车电台通信设备的工作特性,研制了一种新型可调阶跃阻抗谐振器腔体窄带带阻滤波器,用于避免电磁发射测量过程中所引起的测量接收机过载问题。通过软件仿真和实物测试,验证了所设计的带阻滤波器较传统腔体滤波器减少了阻带带宽,具有良好的通带特性,且结构简单,体积较小,可以很好地满足机车电台电磁发射测量的需求,有效提高电磁发射测量结果的准确性。

基于背光显示应用的高量子效率窄带绿光荧光粉Mg_(0.388)Al_(2.408)O_(4):Mn^(2+)

目的:研究Mg_(0.388)Al_(2.408)O_(4):Mn^(2+)荧光粉的发光性能以及在宽色域背光显示领域的应用前景。方法:采用高温固相法合成了Mg_(0.388)Al_(2.408)O_(4):Mn^(2+)荧光粉,并对其物相结构、光致发光特性以及热稳定性进行了研究。结果:该荧光粉具有260~510 nm的宽激发带,最强的激发峰在蓝色光谱区,表明Mg_(0.388)Al_(2.408)O_(4):Mn^(2+)绿光荧光粉可以被商用蓝光芯片有效激发。在紫外光和蓝光的激发下,样品表现出明亮的绿色发射,其拥有较窄的半高宽(FWHM=40.4 nm),较高的色纯度(75.85%)和量子效率(81.5%),计算得到的Huang-Rhys因子表明样品具有较低的电子-声子耦合强度以及较好的热稳定性。制备的LED器件,色域可达118.2%的NTSC。结论:Mg_(0.388)Al_(2.408)O_(4):Mn^(2+)荧光粉在宽色域背光显示领域具有广阔的应用前景。

Infrared emissivities of Mn,Co co-doped ZnO powders

Infrared emissivities of Zn0.99-xMn0.01CoxO （x = 0.00, 0.01, 0.03, 0.05） powders synthesized at different calcination temperatures by solid-state reaction are investigated. Their phases, morphologies, UV absorption spectra, and infrared emissivities are studied by XRD, SEM, UV spectrophotometer, and an IR-2 dual-band infrared emissometer in a range of 8 μm-14 μm. Doped ZnO still has a wurtzite structure, and no peaks of other phases originating from impurities are detected. The optical band-gap decreases as the Co content and calcination temperature ascend, and of which the smallest optical band gap is 2.19 eV. The lowest infrared emissivity, 0.754, is observed in Zn0.98Mn0.01Co0.01O with the increase in Co concentration. The infrared emissivity experiences fluctuations as the calcination temperature increases, and its minimum value is 0.762 at 1100 ℃.

Preparation and infrared emissivities of alkali metal doped ZnO powders

Alkali metal(Li, Na, K) doped ZnO powders were synthesized by solid-state reaction at different calcination temperatures and holding time. Effects of holding time and K sources on the infrared emissivity of ZnO were investigated. The structure and surface morphologies of samples were characterized by X-ray diffraction(XRD) and scanning electron microscopy(SEM). The UV-Vis absorption and infrared emissivities were investigated by a UV-Vis spectrophotometer and an infrared emissometer, respectively. XRD patterns confirm the wurtzite structure of the as prepared samples with single phase. Smooth grain surfaces are detected in all doped ZnO samples, while ZnO:Li and ZnO:Na present the aggregation of grains. The redshifts in the optical band-gap are observed in K-, Na-, and Li-doped ZnO with the values 3.150, 3.144, and 3.142 eV. Due to better crystalline quality, ZnO:K shows a lower emissivity than others. The emissivity of K-doped ZnO decreases to the minimum value(0.804), at 1200 °C and holding 2 h. Compared with KNO3 as K source, K2CO3 doped ZnO has lower emissivities.

Numerical study of strained InGaAs quantum well lasers emitting at 2.33 μm using the eight-band model

We investigate the band structure of a compressively strained In（Ga）As/In0.53Ga0.47As quantum well （QW） on an InP substrate using the eight-band k.p theory. Aiming at the emission wavelength around 2.33 μm, we discuss the influences of temperature, strain and well width on the band structure and on the emission wavelength of the QW. The wavelength increases with the increase of temperature, strain and well width. Furthermore, we design an InAs /In0.53Ga0.47As QW with a well width of 4.1 nm emitting at 2.33 μm by optimizing the strain and the well width.

Measurement of the carrier recovery time in SOA based on four-wave mixing on narrow-band ASE spectrum

Carrier recovery time is a key parameter that determines the performance of a semiconductor optical amplifier （SOA）. A measurement method of carrier recovery time in SOA based on a nearly degenerate four-wave mixing of narrowband amplified spontaneous emission （ASE） spectra is presented. The results show the carrier times are 50.2, 44.6, and 23.6 ps when the injected currents are 120, 180, and 240 mA, respectively, which are in agreement with the nominal values of the sample.

Fowler-Nordheim Tunneling, Photovoltaic Applications and New Band Structure Models of Electroconductive a-CNx:H Films Formed by Supermagnetron Plasma CVD

Hydrogenated amorphous carbon nitride (a-CNx:H) films were formed on Al films deposited on Si or glass (SiO2) substrates, using pulsed radio frequency (PRF) supermagnetron plasma (SMP) chemical vapor deposition (CVD) with N2/i-C4H10 mixed gases. a-CNx:H films were grown under the upper and lower electrode RF powers (13.56 MHz) of continuous and pulsed conditions, respectively, which showed low band gap of about 0.7 eV. a-CNx:H films deposited on the Al/Si or Al/SiO2 substrates showed same low threshold emission electric field (ETH) of 12 V/μm. Multiple layer of Al or ITO (anode)/50nm-SiO2/a-CNx:H/Al (cathode)/Si structures showed Fowler-Nordheim (FN) electron tunneling effect in both forward and reverse current directions. 12.5 nm a-CNx:H film on p-Si substrate showed a photoelectric conversion. Energy band structure and electron conduction models were proposed for the active states of both the field emission and FN tunneling devices and photovoltaic cells.