NOVEL MICROSTRIP DUAL-MODE BANDPASS FILTER WITH COUPLING ENHANCEMENT AND WIDEBAND SPURIOUS RESPONSE SUPPRESSION

The microstrip dual-mode filter （DMF） with conventional coupling structure has some limitations in- eluding the port coupling strength limited by fabrication tolerance and the existence of serious second order spuri- ous band. Therefore, a novel DMF with a offset-feed bended coupling structure and a stepped-impedance dual- mode resonator is proposed for coupling enhancement and spurious response suppression. Based on the analysis of the change of spur frequencies and the current distribution of spur resonant modes, all spurs near passband of the cascaded DMF can be fully suppressed by optimizing the structure parameters of parasite resonators, which bene- fits from the inherent well-controlled transmission zeros. Experimental results show that the proposed DMF ex- hibits lower insertion loss ,much sharper rate of cutoff and wider spur-free stop band compared with conventional DMF. This design is applicable for spur suppression in wideband communication.

Design and analysis of dual-mode structure repetitive control based hybrid current regulation scheme for active power filters

An all-digital hybrid current regulation scheme for the single-phase shunt active power filter （APF） is presented. The proposed hybrid current control scheme integrates the deadbeat control and the dual-mode structure repetitive control （DMRC） so that it can offer superior steady-state performance and good transient features. Unlike the conventional schemes, the proposed scheme-based APF can compensate both the odd and the even order harmonics in grid. The detailed design criteria and the stability analysis of the proposed hybrid current controller are presented. Moreover, an improved structure which incorporates the proposed hybrid controller and the resonant controller for tracking specific order harmonics is given. The relationships between the resonant controller and different repetitive control schemes are discussed. Experimental results verify the effectiveness and advantages of the proposed hybrid control scheme.

Magnetically-coated silica nanospheres for dual-mode imaging at low ultrasound frequency

AIM: To experimentally investigate the acoustical behavior of different dual-mode nanosized contrast agents(NPCAs) for echographic medical imaging at low ultrasound(US) frequency. METHODS: We synthesized three different nanosized structures:(1) Pure silica nanospheres(SiNSs);(2) FePt-iron oxide(FePt-IO)-coated SiNSs; and(3) IOcoated SiNSs, employing three different diameter of SiNS-core(160, 330 and 660 nm). Tissue mimicking phantoms made of agarose gel solution containing 5 mg of different NPCAs in 2 mL-Eppendorf tubes, were insonified by a commercial echographic system at three different low US pulse values(2.5, 3.5 and 4.5 MHz). The raw radiofrequency signal, backscattered from each considered NPCA containing sample, has been processed in order to calculate the US average backscatter intensity and compare the acoustic behavior of the different NPCA types. RESULTS: The highest US contrast was exhibited by pure SiNSs; FePt-IO-coated SiNSs acoustical behavior followed a similar trend of pure SiNSs with a slight difference in terms of brightness values. The acoustic response of the examined NPCAs resulted function of both SiNS diameter and US frequency. Specifically, higher US frequencies determined higher value of the backscatter for a given SiNS diameter. Frequencydependent enhancement was marked for pure SiNSs and became less remarkable for FePt-IO-coated SiNSs, whereas IO-coated SiNSs resulted almost unaffected by such frequency variations. Pure and FePt-IO-coated SiNSs evidenced an image backscatter increasing with the diameter up to 330 nm. Conversely, among the types of NPCA tested, IO-coated SiNSs showed the lowest acoustical response for each synthesized diameter and employed US frequency, although a diameter-dependent raising trend was evidenced. CONCLUSION: The US characterization of magnetically covered SiNS shows that FePt-IO, rather than IO, was the best magnetic coating for realizing NPCAs suitable for dual mode imaging of deep organs, combining US and magnetic resonance imaging.

Simultaneous Multimode Oscillation of Stress-Compensated Cut Quartz Resonator with Narrow-Band Wide Variable-Range Quartz Crystal Oscillator

A multimode-quartz-crystal oscillator was developed to excite stable dual-mode resonance at different frequencies: The oscillation of the 3rd harmonic resonance of the principle C-mode and an additional resonance B-mode of SC-cut crystal. Harmonic combinations of the 3rd and fundamental mode of B-mode with the 3rd harmonics of C-mode are demonstrated. The measurement of the temperature dependence of the oscillation frequency is demonstrated along with the stability determined by root Allan variance. Dependence on the open conductance of the active circuit and the dependence on the coupling capacitors are discussed.

New Planar Dual-Mode Filters without Coupling Gaps

A class of new planar dual-mode filters without coupling gaps is proposed. The proposed structures use a single patch wiuhout coupling gaps. Attenuation poles can be implemented on either side of the passband by changing the locations of two feed lines. By cutting two corners in the patch, two attenuation poles on both sides of passband are implemented. A novel dual-mode elliptic-function bandpass filter structure without coupling gaps is also proposed. These new filters can provide a low insertion loss and reduce uncertainty in fabrication owing to the absence of coupling gaps.

Topological resonators based on hexagonal-star valley photonic crystals

In valley photonic crystals, topological edge states can be gained by breaking the spatial inversion symmetry without breaking time-reversal symmetry or creating pseudo-spin structures, making highly unidirectional light transmission easy to achieve. This paper presents a novel physical model of a hexagonal-star valley photonic crystal. Simulations based on the finite element method(FEM) are performed to investigate the propagation of TM polarized mode and its application to ring resonators. The results show that such a topologically triangular ring resonator exhibits an optimum quality factor Q of about 1.25×104, and Q has a maximum value for both frequency and the cavity length L. Our findings are expected to have significant implications for developing topological lasers and wavelength division multiplexers.

Mesoporous MnSiO3@Fe3O4@C Nanoparticle as p H-responsive T1-T2* Dual-modal Magnetic Resonance Imaging Contrast Agent for Tumor Diagnosis

Mesoporous structured MnSiO3@Fe3O4@C nanoparticles(NPs)were prepared via a facile and efficient strategy,with negligible cytotoxicity and minor side efforts.The as-prepared MnSiO3@Fe3O4@C NPs hold great potential in serving as pH-responsive T1-T2^*dual-modal magnetic resonance(MR)imaging contrast agents.The released Mn^2+shortened T1 relaxation time,meanwhile the superparamagnetic Fe3O4 enhanced T2 contrast imaging.The release rate of Mn ions reaches 31.66%under the condition of pH=5.0,which is similar to tumor microenvironment and organelles.Cytotoxicity assays show that MnSiO3@Fe3O4@C NPs have minor toxicity,even at high concentrations.After intravenous injection of MnSiO3@Fe3O4@C NPs,a rapid contrast enhancement in tumors was achieved with a significant enhancement of 132%after 24 h of the administration.Moreover,a significant decreasement of 53.8%was witnessed in T2 MR imaging signal.It demonstrated that MnSiO3@Fe3O4@C NPs can act as both positive and negative MR imaging contrast agents.Besides,owing to the pH-responsive degradation of mesoporous MnSiO3,MnSiO3@Fe3O4@C NPs can also be used as potential drug systems for cancer theranostics.

Triangular Au-Ag framework nanostructures prepared by multi-stage replacement and their spectral properties

Triangular Au-Ag framework nanostructures （TFN） were synthesized via a multi-step galvanic replacement reaction （MGRR） of single-crystalline triangular silver nanoplates in a chlorauric acid （HAuCl4） solution at room temperature. The morphological, compositional, and crystal structural changes involved with reaction steps were analyzed by using transmission electron microscopy（TEM）, energy-dispersive X-ray spectrometry （EDX）, and X-ray diffraction. TEM combined with EDX and selected area electron diffraction confirmed the replacement of Ag with Au. The in-plane dipolar surface plasmon resonance （SPR） absorption band of the Ag nanoplates locating initially at around 700 nm gradually redshifted to 1 100 nm via a multi-stage replacement manner after 7 stages. The adding amount of HAuCl4 per stage influenced the average redshift value per stage, thus enabled a fine tuning of the in-plane dipolar band. A proposed formation mechanism of the original Ag nanoplates developing pores while growing Au nanoparticles covering this underlying structure at more reaction steps was confirmed by exploiting surface-enhanced Raman scattering （SERS）.

Fe3O4-based Nanoparticles for pH-responsive Dual-modality Imaging and Photothermal Therapy

The study designed a polyacrylic acid(PAA)modified Fe3O4@MnO2 nanoparticles(Fe3O4@MnO2@PAA)for T1/T2 dualmode imaging.In addition,this nano-drug has pH response and anti-tumor photothermal therapy.First,using Fe3O4 as the core can significantly reduce the signal of Fe3O4@MnO2@PAA nanoparticles.MnO2 nanoshells can be decomposed into paramagnetic Mn2+under the acidic environment in the tumor,which enhanced the T1 signal.The pH-responsive T1/T2 dual-mode magnetic resonance imaging(MRI)contrast agent had good sensitivity and specificity,providing more comprehensive and detailed information for tumor diagnosis.In addition,Fe3O4@MnO2@PAA nanoparticles showed excellent absorption capacity in the near-infrared region(NIR),which could be used as a good photothermal conversion material to mediate photothermal treatment of tumors.Therefore,the pHresponsive dual-mode MRI nanoparticle-mediated photothermal therapy showed good application potential in tumor treatment and diagnosis.

MRI 3D-MERGE序列对三角纤维软骨复合体损伤的诊断价值

目的探讨MRI三维-多回波恢复梯度回波(three dimensional-multiple-echo recalled gradient echo,3D-MERGE)序列在腕关节三角纤维软骨复合体(triangular fib roc a rt ilage complex,TFCC)损伤中的诊断价值。方法回顾性分析四川省骨科医院2021年1月-2022年1月因腕尺侧疼痛就诊的76例患者的临床资料,其中男性35例,女性41例,年龄16-52岁,平均年龄39.6岁。所有患者行腕关节MRI 3D-MERGE序列检查,并在随后接受腕关节镜手术。将TFCC损伤分为中心型损伤和边缘型损伤。以腕关节镜结果为金标准,探讨分析MRI 3D-MERGE序列诊断TFCC损伤的敏感度、特异度。结果腕关节镜检查确诊TFCC损伤者60例,其中中心型16例,边缘型28例,中心型和边缘型损伤同时存在16例;MRI 3D-MERGE序列检查TFCC损伤70例,中心型13例,边缘型35例,22例同时存在中心型和边缘型损伤。对比得出MRI 3D-MERGE序列诊断TFCC损伤中心型损伤的敏感度、特异度分别为0.93、0.89,边缘型损伤的敏感度、特异度分别为0.80、0.62。结论MRI3D-MERGE序列对TFCC损伤有较高的诊断价值,但相对于中心型损伤,MRI 3D-MERGE序列对边缘型损伤显示较低的特异度,因此在临床中,对于MRI提示的边缘型损伤患者,医师还需结合患者临床病史和体格检查进行谨慎诊断。

Integration of PEG-conjugated gadolinium complex and superparamagnetic iron oxide nanoparticles as T_(1)-T_(2) dual-mode magnetic resonance imaging probes

The T_(1)-T_(2) dual-mode probes for magnetic resonance imaging(MRI)can non-invasively acquire comprehensive information of different tissues or generate self-complementary information of the same tissue at the same time,making MRI a more flexible imaging modality for complicated applications.In this work,three Gadolinium-diethylene-triaminepentaaceticacid(Gd-DTPA)complex conjugated superparamagnetic iron oxide(SPIO)nanoparticles with different Gd/Fe molar ratio(0.94,1.28 and 1.67)were prepared as T_(1)-T_(2) dual-mode MRI probes,named as SPIO@PEG-GdDTPA0.94,SPIO@PEGGdDTPA1.28 and SPIO@PEG-GdDTPA1.67,respectively.All SPIO@PEG-GdDTPA nanocomposites with 8 nm spherical SPIO nanocrystals showed good Gd3þchelate stability.SPIO@PEG-GdDTPA0.94 nanocomposites with lowest Gd/Fe molar ratio show no cytotoxicity to Raw 264.7 cells as compared to SPIO@PEG-GdDTPA1.28 and SPIO@PEG-GdDTPA1.67.SPIO@PEG-GdDTPA0.94 nanocomposites with r1(8.4mM^(-1)s^(-1)),r2(83.2mM^(-1)s^(-1))and relatively ideal r2/r1 ratio(9.9)were selected for T_(1)-T_(2) dual-mode MRI of blood vessels and liver tissue in vivo.Good contrast images were obtained for both cardiovascular system and liver in animal studies under a clinical 3 T scanner.Importantly,one can get high-quality contrast-enhanced blood vessel images within the first 2 h after contrast agent administration and acquire liver tissue anatomy information up to 24 h.Overall,the strategy of one shot of the dual mode MRI agent could bring numerous benefits not only for patients but also to the radiologists and clinicians,e.g.saving time,lowering side effects and collecting data of different organs sequentially.

Tetraphenylethylene-conjugated polycation covered iron oxide nanoparticles for magnetic resonance/optical dual-mode imaging

Magnetic resonance(MR)/optical dual-mode imaging with high sensitivity and high tissue resolution have attracted many attentions in biomedical applications.To avert aggregation-caused quenching of conventional fluorescence chromophores,an aggregation-induced emission molecule tetraphenylethylene(TPE)-conjugated amphiphilic polyethylenimine(PEI)covered superparamagnetic iron oxide(Alkyl-PEI-LAC-TPE/SPIO nanocomposites)was prepared as an MR/optical dual-mode probe.Alkyl-PEI-LAC-TPE/SPIO nanocomposites exhibited good fluorescence property and presented higher T2 relaxivity(352 Fe mM1s1)than a commercial contrast agent Feridex(120 Fe mM1s1)at 1.5 T.The alkylation degree of Alkyl-PEI-LAC-TPE effects the restriction of intramolecular rotation process of TPE.Reducing alkane chain grafting ratio aggravated the stack of TPE,increasing the fluorescence lifetime of Alkyl-PEI-LAC-TPE/SPIO nanocomposites.Alkyl-PEI-LAC-TPE/SPIO nanocomposites can effectively labelled HeLa cells and resulted in high fluorescence intensity and excellent MR imaging sensitivity.As an MR/optical imaging probe,Alkyl-PEI-LAC-TPE/SPIO nanocomposites may be used in biomedical imaging for certain applications.

微光学陀螺双频率调制理论与实验研究

对微光学陀螺双频率调制中需要极高调制频率差的问题,提出了一种基于三角波的双频率调制技术。解决了双频率锯齿波调制的回扫时间问题以及数字波形中的台阶效应;指出了不同检测范围和检测精度对应于不同的调制信号频率差;确定了产生特定调制频差的三角波信号波形参数的选取及其实现方法;指明了三角波斜率转折点对调制结果的影响,并提出该问题的解决方法。采用自由谱线宽度1.61GHz、本征谱线宽度30.1MHz的集成光学谐振腔陀螺进行实验,完成静态双光路锁定,验证了三角波调制的可行性和优越性。

用双还原法制备三角形银纳米片及其光学性能

在硼氢化钠和柠檬酸三钠共存的体系中还原硝酸银,以聚乙烯吡咯烷酮(PVP)为表面活性剂和保护剂,水浴加热制备得到三角形银纳米片,用X射线衍射(XRD)、透射电子显微镜(TEM)、紫外-可见(UV-Vis)吸收光谱、表面增强拉曼散射(SERS)光谱对其进行了表征.结果表明:三角形银纳米片产物为立方相金属银,边长为(100±40)nm,厚度为(10±5)nm;产物表现出与球形银纳米粒子完全不同的吸收光谱;柠檬酸根在银晶核不同晶面的选择吸附、PVP的包覆作用及Ag(111)晶面的层错对产物的形成起决定作用;与球形纳米颗粒相比,三角形银纳米片膜对吡啶(Py)分子有显著的SERS活性.

关于1/1轨道共振区域问题

本文用讨论轨道共振问题的方法,具体给出1/1共振对应的三角秤动点附近稳定区域的尺度,从而解释Trojan小行群的空间分布.结果表明,对于不同的系统,如太阳—木星—小行星,太阳—土星—小质点,太阳—小行星No.29—小质点,上述稳定区域的尺度同样为ε^(1╱2)的量级,ε是作为受摄二体问题的摄动小参数。对太阳—木星—小行星系统而言,1/1和3/2情况类似,共振态的结构是稳定的。

腕关节不稳合并TFCC损伤患者早期MRI表现

目的分析腕关节不稳合并三角纤维软骨复合体(TFCC)损伤患者早期磁共振成像(MRI)表现,为临床早期确诊及治疗提供客观的影像学依据。方法回顾性分析2015年1月至2017年1月哈励逊国际和平医院核磁共振室高年资医师诊断腕关节不稳合并TFCC损伤78例患者的影像资料,根据Palmer分型标准对其MRI表现进行归纳总结。结果 78例腕关节不稳合并TFCC损伤患者中,创伤性TFCC损伤患者58例(其中ⅠA 11例,ⅠB 27例,ⅠC 5例,ⅠD 15例),在压脂的质子密度加权成像(PD-FS)及3D薄层T2加权成像(T2-iso)冠状位薄层扫描序列上表现为三角纤维软骨盘(TFC)中心可出现裂隙状、线状或片状高信号,软骨面不光滑及撕裂,尺骨茎突连接部及桡骨乙状切迹连接部结构模糊,部分患者出现尺月韧带及尺三角韧带损伤,信号增高,远端桡尺关节积液。退行性TFCC损伤20例(其中ⅡA 5例,ⅡB 4例,ⅡC 3例,ⅡD 2例,ⅡE 6例),在PD-FS及T2-iso冠状位薄层扫描序列上表现为TFC形态变薄,结构模糊,软骨面不光滑,信号不均匀,可见混杂中高信号,邻近月骨、三角骨软骨变薄,内可见小片状水肿信号、囊变,月三角韧带结构模糊,桡尺关节积液。结论 MRI可精确显示腕关节不稳患者TFCC的精细解剖结构,其早期MRI影像表现对临床诊治具有重要价值。

光纤耦合三角形金柱阵列的等离子体共振

为了满足表面等离子体传感器高灵敏度、高线性以及较大测量范围的需求,提出侧边抛磨光纤耦合的三角形纳米金柱阵列等离子体共振传感模型.用有限元法仿真得出侧边抛磨光纤倏逝场激发出三角形纳米金柱的三种等离子体共振模式,分别为传输等离子体、三角形纳米金柱的本征等离子体和柱间等离子体,在传感器透射谱中呈现三个共振波谷.本征等离子体和柱间等离子体均属于局域等离子体,所对应的共振波谷对外界环境折射率的灵敏度较低但具有很高的线性度.传输等离子体对应的波谷随折射率变化灵敏度很高且呈非线性关系,优化后三角形金柱阵列设计中,当折射率为1.38~1.42RIU时,灵敏度高达12 882nm/RIU.该传感结构集成了侧边抛磨光纤的强倏逝场,具有传输等离子体的高灵敏度、局域等离子体的高线性度和大测量动态范围等优点,有重要的研究意义和实用价值.

腕三角纤维软骨盘损伤:STIR序列诊断与关节镜对照

目的探讨应用短反转时间反转恢复(STIR)序列对腕三角纤维软骨盘(TFC)损伤的诊断价值,并与腕关节镜检查结果进行对照研究。资料与方法对56例临床诊断腕TFC损伤病人应用STIR序列进行腕关节MRI检查及关节镜探查。STIR序列扫描参数采用:TR:l164ms,TE:16ms,TI:90ms。以关节镜下TFC损伤的探查结果为标准,评价STIR序列诊断TFC损伤的敏感度、特异度、阳性预测值、阴性预测值及准确度。结果①STIR序列显示TFC正常10例;体部内小水肿或黏液样变性,但关节面缘光滑6例;体部水平撕裂,但未累及至关节面缘6例;关节面缘撕裂6例;中央部穿孔11例;桡骨附着端撕裂6例;尺骨附着端撕裂5例;尺、桡骨附着端均撕裂3例;整体形态不规则变薄3例。②关节镜下显示TFC正常21例;表面撕裂8例;中央部穿孔10例;桡骨附着端撕裂7例;尺骨附着端撕裂5例;尺、桡骨附着端均撕裂2例;整体形态不规则变薄3例。以关节镜为标准,STIR序列诊断TFC损伤的敏感度为85.7%,特异度23.8%,阳性预测值为65.2%,阴性预测值50%,准确度为62.5%。结论 STIR序列对TFC损伤具有较高的诊断价值。

腕关节疼痛病变的MRI研究进展

MRI检查能够清晰反映腕关节多方面内容:三角纤维软骨复合体(triangular fibrocartilage complex,TFCC)的形态、位置、关节软骨、腕骨间韧带、关节液、骨髓改变以及关节区多层次的骨结构改变。本文对磁共振成像技术在腕关节疼痛病变检查中的应用进行综述,介绍常用的腕关节磁共振检查方法、常见致腕关节疼痛病变的磁共振影像表现及一些新的成像方法。

玻璃基底上三角纳米银的原位生长与光谱特性研究

以经硅烷化后的玻璃片为基底,吸附三角形银纳米种子,采用柠檬酸钠为还原剂,在室温下还原硝酸银,制备出基底表面具有三角形银纳米粒子聚集结构的材料。应用透射电镜、扫描电镜、X射线衍射仪、吸收和荧光光谱对产物的结构和性质进行表征。结果表明:随着生长液体积的增加,基片上三角形银纳米盘的平均粒径长大约为300nm,且基底上出现了双层粒子堆叠;基底上纳米粒子的吸收光谱中出现了由银粒子的表面等离子体激元偶极子耦合引发的强烈吸收峰,耦合峰在600～800nm波段内移动;在215nm紫外光的激发下,基底上纳米粒子的荧光光谱在400nm处出现发射峰,荧光光谱的发光强度随着基底上粒子平均尺度增加而减弱。