Spatial photoluminescence and lifetime mappings of quasi-2D perovskites coupled with a dielectric metasurface.

Light-matter interaction between quantum emitters and optical cavities plays a vital role in fundamental quantum photonics and the development of optoelectronics. Resonant metasurfaces are proven to be an efficient platform for tailoring the spontaneous emission (SE) of the emitters. In this work, we study the interplay between quasi-2D perovskites and dielectric TiO2 metasurfaces. The metasurface, functioning as an open cavity, enhances electric fields near its plane, thereby influencing the emissions of the perovskite. This is verified through angle-resolved photoluminescence (PL) studies. We also conducted reflectivity measurements and numerical simulations to validate the coupling between the quasi-2D perovskites and photonic modes. Notably, our work introduces a spatial mapping approach to study Purcell enhancement. Using fluorescence lifetime imaging microscopy (FLIM), we directly link the PL and lifetimes of the quasi-2D perovskites in spatial distribution when positioned on the metasurface. This correlation provides unprecedented insights into emitter distribution and emitter-resonator interactions. The methodology opens a new (to the best of our knowledge) approach for studies in quantum optics, optoelectronics, and medical imaging by enabling spatial mapping of both PL intensity and lifetime, differentiating between uncoupled quantum emitters and those coupled with different types of resonators.

Recurrent paradoxical cerebral embolism caused by a thrombus entrapped in a patent foramen ovale: a case report.

Introduction: A thrombus straddling the patent foramen ovale (PFO) is a very rare clinical entity. Optimal management remains unclear due to the availability of various therapeutic options; thus, an individualized approach is recommended. Case presentation: The authors describe a case presenting with recurrent cerebral embolism and a large and mobile thrombus straddled in the PFO. Historically, cardiac surgery, thrombolysis or anticoagulation were possible management options for this patient. However, there are no guidelines on what the optimal treatment is. Our patient was a poor surgical candidate because of advanced age and multiple comorbidities. Furthermore, she had a recent ischaemic stroke which was a relative contraindication to thrombolysis. After consulting the Heart Team, medical treatment alone with systemic anticoagulation was administered. Subsequent transthoracic echocardiography (TTE) after 1 week showed complete thrombus resolution. After 4 months, the PFO was successfully occluded with an Amplatzer device. The patient received rehabilitation therapy and had good functional recovery. Clinical discussion: Anticoagulant therapy alone was chosen because of high risk for surgery. Complete thrombus resolution was achieved after 1 week although the initial thrombus size was quite large. Nevertheless, this approach may not be applicable to every patient. In addition to TTE, multimodality imaging using transesophageal echocardiography and cardiac magnetic resonance is helpful to identify the mechanism of stroke, which in our case is a thrombus-straddled PFO, and to make early treatment decisions. Serial TTEs help assess the response to anticoagulation. An individualized approach should be made with a multidisciplinary Heart Team. Conclusion: Echocardiography plays an important role in the diagnosis and treatment evaluation for patients with a thrombus straddling a PFO. An individualized approach to manage the patient should be made with a multidisciplinary Heart Team.

Multivalvular involvement associated with Libman-Sacks endocarditis detected by multimodality imaging: A case report.

Libman-Sacks endocarditis accounts for 6-11 percent of systemic lupus erythematosus patients and is associated with varying degrees of valvular dysfunction, increased risk for stroke and transient ischemic attacks, and increased mortality. In previous studies, left-sided valvular Libman-Sacks vegetations were more frequently detected than right sided vegetations; reported cases of bilateral involvement is very rare. A comprehensive clinical assessment and the multimodality imaging is of utmost importance in the management of systemic lupus erythematosus. In this case report, we describe a 31-year-old female patient with uncontrolled systemic lupus erythematosus initially presented with gastrointestinal symptoms but eventually had a vegetation-like structure on the posterior leaflet of the mitral valve which was revealed during routine echocardiography. Two-dimensional/three-dimensional transthoracic and transesophageal echocardiography, cardiac magnetic resonance, and cardiac computed tomography further characterized the mitral valve vegetation and revealed an additional vegetation of the pulmonary valve. Echocardiography remains the cornerstone for the detection of Libman-Sacks vegetations. Cardiac MRI and cardiac CT are useful in characterizing lesion size and effects and may prove particularly helpful in the assessment of right-sided or multivalvular endocarditis. The presence of focal brain lesions on brain MRI prompted antithrombotic therapy.

Flexible Magnetic Metasurface with Defect Cavity for Wireless Power Transfer System.

In this paper, we present a flexible magnetic metamaterial structure for enhancing the efficiency of wireless power transfer (WPT) systems operating at 13.56 MHz. The metasurface between transmitter (Tx) and receiver (Rx) coils of the WPT system is constructed of a 3 × 5 metamaterial unit cell array with a total size of 150 × 300 mm2. Most metamaterial structures integrated into WPT systems are in planar configurations with a rigid substrate, which limits practical applications. The proposed metasurface is fabricated on an FR-4 substrate with a thin thickness of 0.2 mm; therefore, it can be bent with radii greater than 80 mm. A defect cavity is formed in the non-homogeneous metasurface by controlling the resonant frequency of the unit cell with an external capacitor. Simulation and measurement results show that the efficiency of the WPT system is significantly enhanced with metasurfaces. The performance of the WPT system can also be optimized with suitable bend profiles of metasurfaces. This proposed flexible metasurface could be widely applied to WPT systems, especially asymmetric, bendable, or wearable WPT systems.

Multimodality imaging in the diagnosis of bioprosthetic aortic valve endocarditis: A case report.

Introduction: Prosthetic valve infective endocarditis (PVE) is a diagnostic challenge even in the era of multimodality cardiovascular imaging. Case presentation: The patient was a 67-year-old male with a three-year history of bioprosthetic aortic valve replacement who presented with persistent fever and negative blood cultures. The initial transthoracic echocardiography revealed a thickened aortic root. An abscess formation was visualized upon subsequent three-dimensional transesophageal echocardiography and positron emission tomography/computerized tomography (PET/CT). The patient underwent an urgent necrotic tissue debridement and a redo Bentall surgery. The real-time polymerase chain reaction of excised tissues was positive for Streptococcus. Clinical discussion: The diagnosis of PVE and its complications requires the integration of clinical, microbiological, and serial imaging data. Although advanced imaging modalities like PET/CT allow a timely diagnosis and management, their routine use in resource-limited scenarios is difficult. Conclusion: Multimodality cardiovascular imaging plays an important role in the diagnosis of PVE. Serial echocardiographic and clinical assessments are possible alternatives when the access to advanced cardiovascular imaging modalities is limited.

Rotary bi-layer ring-shaped metamaterials for reconfiguration absorbers: publisher's note.

This publisher's note corrects errors in Appl. Opt.61, 9078 (2022)APOPAI0003-693510.1364/AO.471949.

Rotary bi-layer ring-shaped metamaterials for reconfiguration absorbers.

A reconfigurable metamaterial absorber (MA) in the microwave region is numerically and experimentally demonstrated based on a multi-layered metamaterial. The proposed structure can be mechanically switched between two different configurations to obtain designated absorption behaviors. By rotating the upper ring layer by multiples of 90 deg, two separated absorption modes of the MA are created. The first configuration acts as a single-band absorber, while the second configuration performs multi-band perfect absorption. In addition, the proposed structure can be easily switched into two different configurations to obtain a designated absorption feature. Our work is expected to provide an effective approach to obtaining reconfigurable MAs, which are useful for various applications.

Optimal frequency for magnetic resonant wireless power transfer in conducting medium.

In this article, we investigated the efficiency of a magnetic resonant wireless power transfer (MR-WPT) in conducting medium and found out an optimal frequency for designing the system. In conducting environment, the eddy current loss is generated by the high-frequency alternating currents in the coils. It is manifested by increased radiation resistance of resonator coil leads to decrease the quality factor (Q-factor), which reduces the wireless power transfer (WPT) efficiency in conducting medium. The Q-factor of the resonator coil strongly depending on the conductivity, frequency, and thickness of conducting block. Two MR-WPT systems operating at 10.0 MHz and 20.0 MHz are implemented to study the effect of conducting medium on efficiency. The achieved results indicated that the 20.0 MHz system has higher efficiency at a conductivity smaller than 6.0 S/m. However, at the larger conductivity, the 10.0 MHz system is more efficient. The results provide a method to determine the optimal frequency of a WPT system operating in the conducting medium with various conductivities and thickness blocks. This method can be used to design MR-WPT systems in numerous situations, such as autonomous underwater vehicles and medical implants.

Simple design of efficient broadband multifunctional polarization converter for X-band applications.

A simple design of a broadband multifunctional polarization converter using an anisotropic metasurface for X-band application is proposed. The proposed polarization converter consists of a periodic array of the two-corner-cut square patch resonators based on the FR-4 substrate that achieves both cross-polarization and linear-to-circular polarization conversions. The simulated results show that the polarization converter displays the linear cross-polarization conversion in the frequency range from 8 to 12 GHz with the polarization conversion efficiency above 90%. The efficiency is kept higher than 80% with wide incident angle up to 45°. Moreover, the proposed design achieves the linear-to-circular polarization conversion at two frequency bands of 7.42-7.6 GHz and 13-13.56 GHz. A prototype of the proposed polarization converter is fabricated and measured, showing a good agreement between the measured and simulated results. The proposed polarization converter exhibits excellent performances such as simple structure, multifunctional property, and large cost-efficient bandwidth and wide incident angle insensitivity in the linear cross polarization conversion, which can be useful for X-band applications. Furthermore, this structure can be extended to design broadband polarization converters in other frequency bands.

Broadband microwave coding metamaterial absorbers.

In this paper, a broadband metamaterial microwave absorber is designed, simulated and measured. Differently from the traditional method which is only based on unit cell boundary conditions, we carried out full-wave finite integration simulations using full-sized configurations. Starting from an elementary unit cell structure, four kinds of coding metamaterial blocks, 2 × 2, 3 × 3, 4 × 4 and 6 × 6 blocks were optimized and then used as building blocks (meta-block) for the construction of numerous 12 × 12 topologies with a realistic size scale. We found the broadband absorption response in the frequency range 16 GHz to 33 GHz, in good agreement with the equivalent medium theory prediction and experimental observation. Considering various applications of metamaterials or metamaterial absorbers in the electromagnetic wave processing, including the radars or satellite communications, requires the frequency in the range up to 40 GHz. Our study could be useful to guide experimental work. Furthermore, compared to the straightforward approach that represents the metamaterials configurations as 12 × 12 matrices of random binary bits (0 and 1), our new approach achieves significant gains in the broadband absorption. Our method also may be applied to the full-sized structures with arbitrary dimensions, and thus provide a useful tool in the design of metamaterials with specific desired frequency ranges.

Tunable broadband-negative-permeability metamaterials by hybridization at THz frequencies.

We present a numerical study of thermo-tunable broadband-negative-permeability metamaterial based on second-order hybridization operating at the THz regime. The conventional metal is replaced by InSb, in which the temperature-dependent conductivity plays a key role in tuning the separation of second-order-hybridization magnetic-resonance modes. It is demonstrated that the hybridization in a simple disk-pair dimer can be tuned by temperature, leading to a significant broadening of the negative-permeability at THz frequencies. By increasing the temperature of the InSb patterns in the structure from 300 to 450 K, the fractional bandwidth (FBW) of the negative permeability curve varies from 4.4% to 12.9%. The thermally-increased carrier-density of InSb reduces the kinetic inductance, the main mechanism of the enhanced magnetic-resonance and the stronger activated-hybridization. Moreover, optimization for the bandwidth of negative permeability is also carried out by changing the geometrical parameters to have a FBW of 20.9%. The equivalent LC-circuit model and standard retrieval method are performed to elaborate our proposed idea. Our results would pave the way for the implementations of diversified semiconductors in tunable broadband-negative-permeability and broadband-negative-refractive-index metamaterials at THz frequencies.

Ultra-subwavelength thickness for dual/triple-band metamaterial absorber at very low frequency.

An integrated model utilizing external parasitic capacitors for a dual-band metamaterial perfect absorber (DMPA) is proposed and demonstrated in the UHF radio band. By adjusting the lumped capacitors on a simple meta-surface, the thickness of absorber is reduced to be only 1/378 and 1/320 with respect to the operating wavelength at 305 and 360.5 MHz, respectively. The simulations and the experiments confirm that the DMPA can maintain an absorption over 91% in a wide range of incident angle (up to 55°) and independent of the polarization of incident radiation. Additionally, we examine the integrated model for smaller dual-band absorber and absorption performance at higher frequencies (LTE band). Finally, we consolidate our approach by fabricating an ultrathin triple-band perfect absorber miniaturized to be only 1/591 of the longest operating wavelength. Our work is expected to contribute to the actualization of metamaterial-based devices working at radio frequency.

Polarization-independent, wide-incident-angle and dual-band perfect absorption, based on near-field coupling in a symmetric metamaterial.

We numerically and experimentally investigated a dual-band metamaterial perfect absorber (MPA), utilizing the near-field coupling of double split-ring resonators (DSRRs). Owing to the near-field coupling between resonators, two arms in each DSRR resonate in different phases, leading to a dual-band perfect absorption. The proposed MPA also exhibits polarization-insensitive behavior and maintains the high absorption above 90% up to a wide range of incident angle more than 45°. Finally, to further consolidate our approach, a multi-band absorption is also studied by exploiting the near-field coupling among a larger number of DSRRs. Our work is expected to be applied to future broadband devices using MPA.

National logistics working groups: A landscape analysis study.

Several countries have acknowledged the contributions made by national logistics working groups (NLWG) to ensure equitable access to the expanded program on immunization's (EPI) vaccines against preventable diseases. In order to provide key insights to the United Nations Children's Fund (UNICEF) and the World Health Organization (WHO) supply chain hub - as well as other players, including national EPI - a landscape analysis study was conducted from September 2015 to February 2016. This is a cross-sectional survey taken by 43 countries that combines qualitative and quantitative approaches. Data was collected through a desk review, consultation, interviews, and distance questioning. References and guidance were used to determine and specify the underlying mechanisms of NLWGs. The key findings are:This study has provided a general overview of the status of NLWGs for immunization in various countries. Based on the key insights of the study, technical assistance needs have been identified, and immunization partners will be required to help countries create and reinforce their NLWGs.

Miniaturization for ultrathin metamaterial perfect absorber in the VHF band.

An efficient resolution for ultrathin metamaterial perfect absorber (MPA) is proposed and demonstrated in the VHF radio band (30-300 MHz). By adjusting the lumped capacitors and the through vertical interconnects, the absorber is miniaturized to be only λ/816 and λ/84 for its thickness and periodicity with respect to the operating wavelength (at 102 MHz), respectively. The detailed simulation and calculation show that the MPA can maintain an absorption rate over 90% in a certain range of incident angle and with a wide variation of capacitance. Additionally, we utilized the advantages of the initial single-band structure to realize a nearly perfect dual-band absorber in the same range. The results were confirmed by both simulation and experiment at oblique incidence angles up to 50°. Our work is expected to contribute to the actualization of future metamaterial-based devices working at radio frequency.

Ambient and Emission Trends of Toxic Air Contaminants in California.

After initiating a toxic air contaminant (TAC) identification and control program in 1984, the California Air Resources Board adopted regulations to reduce TAC emissions from cars, trucks, stationary sources, and consumer products. This study quantifies ambient concentration and emission trends for the period 1990-2012 for seven TACs that are responsible for most of the known cancer risk associated with airborne exposure in California. Of these seven, diesel particulate matter (DPM) is the most important; however DPM is not measured directly. Based on a novel surrogate method, DPM concentrations declined 68%, even though the state's population increased 31%, diesel vehicle-miles-traveled increased 81%, and the gross state product (GSP) increased 74%. Based on monitoring data, concentrations of benzene, 1,3-butadiene, perchloroethylene, and hexavalent chromium declined 88-94%. Also, the ambient and emissions trends for each of these four TACs were similar. Furthermore, these declines generally occurred earlier in California than elsewhere. However, formaldehyde and acetaldehyde, which are formed in the air photochemically from volatile organic compounds (VOCs), declined only 20-21%. The collective cancer risk from exposure to these seven reviewed TACs declined 76%. Significant reduction in cancer risk to California residents from implementation of air toxics controls (especially for DPM) is expected to continue.

Dual-color ultrasensitive bright-field RNA in situ hybridization with RNAscope.

In situ hybridization (ISH) techniques have been important to the study of gene expression signatures in cells and tissues. The ability to detect multiple targets simultaneously is especially valuable, since it allows dissecting gene expression of distinct cell types with precise cellular and subcellular resolution within morphological context. Recently, we have reported using a novel dual-color ultrasensitive bright-field RNA in situ hybridization for detection of clonally restricted immunoglobulin light chain mRNA expression in B cell lymphomas. Here, we present detailed protocols of RNAscope 2-Plex assays for FFPE tissue sections. The protocols describe the tissue preparation, pretreatment, probe hybridization, signal amplification, visualization, and analysis, as well as emphasize the critical steps for ensuring successful staining.

Quantitative ultrasensitive bright-field RNA in situ hybridization with RNAscope.

RNA in situ hybridization (ISH) can provide valuable morphological context for molecular markers on one hand and enable morphological analysis in molecular context on the other hand. It has become increasingly important, thanks to increasing interest in new biomarkers and noncoding RNAs in both research and clinical applications. We have developed an ultrasensitive RNA ISH technology, RNAscope, employing a unique probe design strategy that allows target-specific signal amplification while suppressing background noise. This approach enables single RNA molecule detection in formalin-fixed paraffin-embedded (FFPE) specimens under standard bright-field microscopy and is capable of multiplex detection at the single cell level. After staining, target-specific signals appear as punctate dots present in individual cells in well-preserved tissue morphological context, which facilitates both semiquantitative manual scoring and software-assisted quantitative analysis. Here, we present detailed protocols of RNAscope for FFPE tissue sections. The step-by-step protocols describe tissue preparation, pretreatment, probe hybridization, signal amplification, visualization, and analysis. We also highlight the critical steps for ensuring successful staining.

RNAscope for in situ detection of transcriptionally active human papillomavirus in head and neck squamous cell carcinoma.

The 'gold standard' for oncogenic HPV detection is the demonstration of transcriptionally active high-risk HPV in tumor tissue. However, detection of E6/E7 mRNA by quantitative reverse transcription polymerase chain reaction (qRT-PCR) requires RNA extraction which destroys the tumor tissue context critical for morphological correlation and has been difficult to be adopted in routine clinical practice. Our recently developed RNA in situ hybridization technology, RNAscope, permits direct visualization of RNA in formalin-fixed, paraffin-embedded (FFPE) tissue with single molecule sensitivity and single cell resolution, which enables highly sensitive and specific in situ analysis of any RNA biomarker in routine clinical specimens. The RNAscope HPV assay was designed to detect the E6/E7 mRNA of seven high-risk HPV genotypes (HPV16, 18, 31, 33, 35, 52, and 58) using a pool of genotype-specific probes. It has demonstrated excellent sensitivity and specificity against the current 'gold standard' method of detecting E6/E7 mRNA by qRT-PCR. HPV status determined by RNAscope is strongly prognostic of clinical outcome in oropharyngeal cancer patients.

Automated quantitative RNA in situ hybridization for resolution of equivocal and heterogeneous ERBB2 (HER2) status in invasive breast carcinoma.

Patient management based on HER2 status in breast carcinoma is an archetypical example of personalized medicine but remains hampered by equivocal testing and intratumoral heterogeneity. We developed a fully automated, quantitative, bright-field in situ hybridization technique (RNAscope), applied it to quantify single-cell HER2 mRNA levels in 132 invasive breast carcinomas, and compared the results with those by real-time quantitative PCR (qPCR) and Food and Drug Administration-approved methods, including fluorescence in situ hybridization (FISH), IHC, chromogenic in situ hybridization, and dual in situ hybridization. Both RNAscope and qPCR were 97.3% concordant with FISH in cases in which FISH results were unequivocal. RNAscope was superior to qPCR in cases with intratumoral heterogeneity or equivocal FISH results. This novel assay may enable ultimate HER2 status resolution as a reflex test for current testing algorithms. Quantitative in situ RNA measurement at the single-cell level may be broadly applicable in companion diagnostic applications.