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.

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.

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.

Gadolinium-containing semiconducting polymer nanoparticles for magnetic resonance/fluorescence dual-modal imaging and photothermal therapy of oral squamous cell carcinoma

Oral squamous cell carcinoma(OSCC)is the most common malignant tumor of the oral and maxillofacial region.Due to its unique location,earlier and more accurate diagnosis and more minimally invasive treatment of OSCC is of major importance.Herein,gadolinium-containing semiconductor polymer nanoparticles(SPN-Gd)were designed and prepared.The nanoparticles consist of a near-infrared(NIR)absorption semiconductor polymer(PCPDTBT)served as fluorescence signal source and a photothermal conversion agent(PTA)and a gadolinium-grafted triblock amphiphilic copolymer(F127-DTPA-Gd)served as a magnetic resonance imaging(MRI)contrast agent and nanocarrier.The experiments in vivo showed that SPN-Gd could act as an MRI contrast agent and optical image agent with a long retention time,and it had a significant inhibiting effect on tumors of OSCC mice model through photothermal therapy(PTT).Thus our study provides a simple nanotheranostic platform composed of two components for efficient MR/fluorescence dual-modal imaging-guided PTT.

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.

Polymeric dual-modal imaging nanoprobe with two-photon aggregation-induced emission for fluorescence imaging and gadolinium-chelation for magnetic resonance imaging

Nanoprobes that offer both fluorescence imaging(FI)and magnetic resonance imaging(MRI)can provide supplementary information and hold synergistic advantages.However,synthesis of such dual-modality imaging probes that simultaneously exhibit tunability of functional groups,high stability,great biocompatibility and desired dual-modality imaging results remains challenging.In this study,we used an amphiphilic block polymer from(ethylene glycol)methyl ether methacrylate(OEGMA)and N-(2-hydroxypropyl)methacrylamide(HPMA)derivatives as a carrier to conjugate a MR contrast agent,Gd-DOTA,and a two-photon fluorophore with an aggregation-induced emission(AIE)effect,TPBP,to construct a MR/two-photon fluorescence dual-modality contrast agent,Gd-DOTA-TPBP.Incorporation of gadolinium in the hydrophilic chain segment of the OEGMA-based carrier resulted in a high r_(1)value for Gd-DOTA-TPBP,revealing a great MR imaging resolution.The contrast agent specifically accumulated in the tumor region,allowing a long enhancement duration for vascular and tumor contrast-enhanced MR imaging.Meanwhile,coupling TPBP with AIE properties to the hydrophobic chain segment of the carrier not only improved its water solubility and reduced its cytotoxicity,but also significantly enhanced its imaging performance in an aqueous phase.Gd-DOTA-TPBP was also demonstrated to act as an excellent fluorescence probe for two-photon-excited bioimaging with higher resolution and greater sensitivity than MRI.Since high-resolution,complementary MRI/FI dual-modal images were acquired at both cellular and tissue levels in tumor-bearing mice after application of Gd-DOTA-TPBP,it has great potential in the early phase of disease diagnosis.

A transferrin receptor targeting dual-modal MR/NIR fluorescent imaging probe for glioblastoma diagnosis

The prognosis of glioblastoma(GBM)remains challenging,primarily due to the lack of a precise,effective imaging technique for comprehensively characterization.Addressing GBM diagnostic challenges,our study introduces an innovative dual-modal imaging that merges near-infrared(NIR)fluorescent imaging with magnetic resonance imaging(MR).This method employs superparamagnetic iron oxide nanoparticies coated with NIR fluorescent dyes,specifically Cyanine 7,and targeted peptides.This synthetic probe facilitates MRI functionality through superparamagnetic iron oxide nanoparticles,provides NIR imaging capability via Cyanine 7 and enhances tumor targeting trough peptide interactions,offering a comprehensive diagnostic tool for GBM.Notably,the probe traverses the blood-brain barrier,targeting GBM in vivo via peptides,producing clear and discermible images in both modalities.Cytotoxicity and histopathology assessments confirm the probe's favorable safet profile.These findings suggest that the dual-modal MRINIR fluorescent imaging probe could revolutionize GBM prognosis and survival rate which can also be extended to other tumors type.

Multifunctional lymph-targeted platform based Mn@mSiO2 nanocomposites： Combining PFOB dual-mode imaging and DOX for cancer diagnose treatment on for and

A universal platform with M_n doping and hyaluronic acid （HA） modification, based on mesoporous silica （mSiO2）, was designed and used as a basic multifunctional material with magnetic resonance （MR） imaging. Furthermore, we added flexible functions through the addition of functional molecules. Specially, two typical compounds, hydrophobic perfluorooctyl bromide （PFOB） and hydrophilic doxorubicin （DOX）, were loaded into the channels to obtain PFOB@Mn@mSiO2@HA （PMMH） or DOX@Mn@mSiO2@HA （DMMH） or imaging and therapy, respectively. The were highly targeted to the lymph system in nanoparticles for dual-mode imaging PMMH and DMMH nanoparticles vitro and in vivo. MR and ultrasound imaging of PMMH nanoparticles were performed in the lymph system, while MR imaging and chemotherapy of DMMH nanoparticles was used to detect cancer. These results showed that both PMMH and DMMH nanoparficles can be designed with high lymph targeting efficiency. PMMH nanoparticles are a dual-mode contrast agent for both ultrasound and MR imaging for the lymph system and DMMH nanoparticles are powerful agents for the combined diagnosis and therapy of cancer in vivo.

Integrating lattice and gap plasmonic modes to construct dual-mode metasurfaces for enhancing light–matter interaction

Photonic structures with optical resonances beyond a single controllable mode are strongly desired for enhancing light±matter interactions and bringing about advanced photonic devices. However, the realization of effective multimodal photonic structures has been restricted by the limited tunable range of mode manipulation, the spatial dispersions of electric fields or the polarization-dependent excitations. To overcome these limitations, we create a dualmode metasurface by integrating the plasmonic surface lattice resonance and the gap plasmonic modes;this metasurface offers a widely tunable spectral range, good overlap in the spatial distribution of electric fields, and polarization independence of excitation light. To show that such dual-mode metasurfaces are versatile platforms for enhancing light±matter interactions, we experimentally demonstrate a significant enhancement of second-harmonic generation using our design, with a conversion efficiency of 1±3 orders of magnitude larger than those previously obtained in plasmonic systems. These results may inspire new designs for functional multimodal photonic structures.

Facile preparation of holmium(Ⅲ)-doped carbon nanodots for fluorescence/magnetic resonance dual-modal bioimaging

In this work, we report the synthesis of holmium（III）-doped carbon nanodots（Ho BCDs） as fluorescence/magnetic resonance（FL/MR） dual-modal imaging probes via a facile hydrothermal process using citrate acid（CA）, branched-polyethylenimine（BPEI） and diethylenetriamine pentaacetic acid hydrate holmium（III） dihydrogen salt（Ho-DTPA） as carbon source, passivating reagent and holmium source, respectively.The thus prepared Ho BCDs exhibited ultra-small particle size（~4 nm）, high water solubility and bright fluorescence with an absolute quantum yield of 8%. Additionally, grey-scaled T_1-weighted images of Ho BCDs solution appeared to be apparently brighter than that of deionized water and un-doped blue carbon nanodots（BCDs） solution. In addition, in vitro toxicity assay validated superior biocompatibility of Ho BCDs. Using He La cells as models, Ho BCDs-treated cells were observed to emit blue fluorescence located both in plasma and nucleus, and presented positive contrast enhancement in T_1-weighted images, suggesting their potentials for practical biomedical applications.

Organic Nanoprobes for Fluorescence and ^19F Magnetic Resonance DuaI-Modality Imaging

Multimodal imaging techniques have been demonstrated to be greatly advantageous in achieving accurate diagnosis and gained increasing attention in recent decades. Herein, we present a new strategy to integrate the complementary modalities of I9F magnetic resonance imaging （19F MRI） and fluorescence imaging （FI） into a polymer nanoprobe composed of hydrophobic fluorescent organic core and hydrophilic fluorinated polymer shell. The alkyne-terminated fluorinated copolymer （Pn） of 2,2,2-trifluoroethyl acrylate （TFEA） and poly（ethylene glycol） methyl ether acrylate （PEGA） was first prepared vie atom transfer radical polymerization （ATRP）. The PEGA plays an important role in both improving ^19F signal and modulating the hydrophilicity of Pn. The alkynyl tail in Pn is readily conjugated with azide modified tetra-phenylethylene （TPE） through click chemistry to form azo polymer （TPE-azo-Pn）. The core-shell nanoprobes （TPE-P3N） with an average particle size of 57.2±8.8 nm are obtained via self-assembly with ultrasonication in aqueous solution. These nanoprobes demonstrate high water stability, good biocompatibility, strong fluorescence and good ^19F MRI performance, which present great potentials for simultaneous fluorescence imaging and ^19F-MR imaging.

Manganese-doped mesoporous polydopamine nanoagent for T1-T2 magnetic resonance imaging and tumor therapy

Theranostic nanodrugs combining magnetic resonance imaging(MRI)and cancer therapy have attracted extensive interest in cancer diagnosis and treatment.Herein,a manganese(Mn)-doped mesoporous polydopamine(Mn-MPDA)nanodrug incorporating the nitric oxide(NO)prodrug BNN6 and immune agonist R848 was developed.The nanodrug responded to the H^(+)and glutathione being enriched in tumor microenvironment to release R848 and Mn^(2+).The abundant Mn^(2+)produced through a Fenton-like reaction enabled a highly sensitive T1-T2 dual-mode MRI for monitoring the tumor accumulation process of the nanodrug,based on which an MRI-guided laser irradiation was achieved to trigger the NO gas therapy.Meanwhile,R848 induced the re-polarization of tumor-promoting M2-like macrophage to a tumoricidal M1 phenotype.Consequently,a potent synergistic antitumor effect was realized in mice bearing subcutaneous 4T1 breast cancer,which manifested the great promise of this multifunctional nanoplatform in cancer treatment.

Multifunctional Gd-CuS loaded UCST polymeric micelles for MR/PA imaging-guided chemo-photothermal tumor treatment

Hepatocellular carcinoma(HCC)is a life-threatening disease for which there is no effective treatment currently.Novel theranostics simultaneously having excellent imaging and therapeutic functions are highly desired in cancer therapy.Herein,we develop the sialic acid(SA)modified polymeric micelles at an upper critical solution temperature(UCST)of 43℃(sialic acid-poly(ethylene glycol)-poly(acrylamide-co-acrylonitrile),SA-PEG-p(AAm-co-AN)),which further encapsulated with doxorubicin(DOX)and Gd-CuS nanoparticles(Gd-CuS NPs)for chemo-photothermal treatment of HCC guided by magnetic resonance(MR)/photoacoustic(PA)dual-mode imaging.The resultant SA-PEG-p(AAm-co-AN)/DOX/Gd-CuS(SPDG)had an excellent photothermal conversion efficiency,enabling SPDG with an instantaneous release behavior of DOX under near-infrared(NIR)irradiation.This study also revealed that SPDG could actively target to HCC,which was due to that SA had a high affinity with E-selectin overexpressed at the tumor site.Moreover,benefiting from the HCC-targeted ability and NIR light-controlled on-demand delivery of DOX,SPDG showed a superior potential in MR/PA dual-mode imaging-guided chemo-photothermal treatment.Overall,our study reveals that the designed SPDG may be used as an ideal multifunctional nanoplatform for cancer theranostics.