Thin Cap Research Articles

A high-performance, metallodielectric 2D photonic crystal for thermophotovoltaics

Fuel-combustion-based thermophotovoltaic (TPV) systems are emerging as a viable power source for small, portable generators for a spectrum of applications such as UAVs, robotic platforms, and sensors. In TPV systems, an emitter heated to above 1000 K emits radiation that is then converted to electricity by a low bandgap photovoltaic cell. One promising class of TPV emitters are two-dimensional photonic crystals (PhCs) made of tantalum, which have shown high-temperature stability at 1150–1250K over hundreds of hours [1] , [2] and have been implemented in a prototype system with 4.4% fuel-to-electricity efficiency [1] . Tantalum PhCs filled and capped with hafnium oxide can enable even higher optical performance with in-band emissivities of 0.8–0.9. However, two key features are difficult to realize simultaneously: a uniformly filled cavity and a thin capping layer of hafnium oxide [3] , [4] . Here, we present a process that results in reduced roughness and better thickness control of the capping layer. We use room temperature reflectance measurements and full system simulations to estimate system performance gains. This selective emitter paves the way toward efficient, practical, and portable mesoscale generators. • A broadband selective emitter for TPV has been fabricated and measured. • Emitter consists of tantalum photonic crystal, filled and capped with hafnium oxide. • Up to 37.5% increase in power output is estimated over previous system prototype.

Vibrational Spectrum and Thermal Conductivity of Rare‐Earth Semiconducting Erbium Nitride Thin Films

Rare‐earth semiconducting mononitrides (RENs) are an emerging class of materials due to their unique electronic and magnetic properties originating from strongly localized 4f orbitals. Erbium nitride (ErN) is one of the most promising REN and attracts significant interest for spintronics, thermoelectric, and Gifford–McMahon cryo‐cooler applications. However, despite such progress, growth and characterization of the physical properties of ErN are rather challenging due to its propensity for oxidation, and no report on its thermal transport properties exists to date. Recently, high‐quality ErN thin films are deposited and are stabilized in ambient with thin capping layers. Herein this letter, first‐principles density functional perturbation theory to model the vibrational spectrum of ErN is utilized and the calculations with the phonon frequency measurements with inelastic Raman spectroscopy are verified. Consistent with its polar dielectric nature, ErN exhibits a longitudinal‐optical transverse‐optical phonon mode splitting at the Γ‐point with a separation of 333 cm−1. Time‐domain thermoreflectance is used to measure the low‐temperature (80 –300 K) thermal conductivity of ErN films. At room temperature, ErN films exhibit a low thermal conductivity of 1.16 ± 0.15 and 2 ± 0.2 W mK−1 on (001) MgO and (0001) Al2O3 substrates, respectively, making them attractive for thermoelectrics and thermal barrier coating applications.

Effect of Graphene vs. Reduced Graphene Oxide in Gold Nanoparticles for Optical Biosensors-A Comparative Study.

Aiming to develop a nanoparticle-based optical biosensor using gold nanoparticles (AuNPs) synthesized using green methods and supported by carbon-based nanomaterials, we studied the role of carbon derivatives in promoting AuNPs localized surface plasmon resonance (LSPR), as well as their morphology, dispersion, and stability. Carbon derivatives are expected to work as immobilization platforms for AuNPs, improving their analytical performance. Gold nanoparticles (AuNPs) were prepared using an eco-friendly approach in a single step by reduction of HAuCl4·3H2O using phytochemicals (from tea) which act as both reducing and capping agents. UV–Vis spectroscopy, transmission electron microscopy (TEM), zeta potential (ζ-potential), and X-ray photoelectron spectroscopy (XPS) were used to characterize the AuNPs and nanocomposites. The addition of reduced graphene oxide (rGO) resulted in greater dispersion of AuNPs on the rGO surface compared with carbon-based nanomaterials used as a support. Differences in morphology due to the nature of the carbon support were observed and are discussed here. AuNPs/rGO seem to be the most promising candidates for the development of LSPR biosensors among the three composites we studied (AuNPs/G, AuNPs/GO, and AuNPs/rGO). Simulations based on the Mie scattering theory have been used to outline the effect of the phytochemicals on LSPR, showing that when the presence of the residuals is limited to the formation of a thin capping layer, the quality of the plasmonic resonance is not affected. A further discussion of the application framework is presented.

Detection of Vulnerable Coronary Plaques Using Invasive and Non-Invasive Imaging Modalities.

Acute coronary syndrome (ACS) mostly arises from so-called vulnerable coronary plaques, particularly prone for rupture. Vulnerable plaques comprise a specific type of plaque, called the thin-cap fibroatheroma (TFCA). A TCFA is characterized by a large lipid-rich necrotic core, a thin fibrous cap, inflammation, neovascularization, intraplaque hemorrhage, microcalcifications or spotty calcifications, and positive remodeling. Vulnerable plaques are often not visible during coronary angiography. However, different plaque features can be visualized with the use of intracoronary imaging techniques, such as intravascular ultrasound (IVUS), potentially with the addition of near-infrared spectroscopy (NIRS), or optical coherence tomography (OCT). Non-invasive imaging techniques, such as computed tomography coronary angiography (CTCA), cardiovascular magnetic resonance (CMR) imaging, and nuclear imaging, can be used as an alternative for these invasive imaging techniques. These invasive and non-invasive imaging modalities can be implemented for screening to guide primary or secondary prevention therapies, leading to a more patient-tailored diagnostic and treatment strategy. Systemic pharmaceutical treatment with lipid-lowering or anti-inflammatory medication leads to plaque stabilization and reduction of cardiovascular events. Additionally, ongoing studies are investigating whether modification of vulnerable plaque features with local invasive treatment options leads to plaque stabilization and subsequent cardiovascular risk reduction.

Dynamic Entropy of Two-Dimensional Active Brownian Systems in Colloidal Plasmas.

We analyze the experimental data on the motion of active Brownian micrograins in RF discharge plasmas. In the experiments, two types of microparticles were used: first—plastic grains fully covered with metal, and second—Janus particles with a thin metal cap. We have tracked the trajectories of the separate grains and plotted the pair correlation functions of the observed structures. To examine the motion of the grains, we studied the dependencies of the MFPT dynamic entropy on the coarsening parameter, the fractal dimension of the system on its mean kinetic temperature, and the mean localization area of the grain on its mean kinetic temperature. Based on the obtained results, we conclude that the character of motion of our active Brownian systems changes as the power of an illuminating laser (and, therefore, the mean kinetic temperature of the grains) increases. Janus particles change their trajectories from more chaotic to spiral-like ones; in the case of fully covered particles, we observe the dynamical phase transition from the more ordered structure to the less ordered one.

Development of 3-D Wafer Level Packaging for SAW Filters Using Thin Glass Capping Technology

The introduction of 5G mobile communication created the need to support a large number of radio frequency (RF) bands. This required high performance and reduced size for microacoustic filters. Based on these requirements, a new three-dimensional wafer-level packaging (3-D WLP) solution based on the predecessors’ developed technology was presented to resolve reliability issues for surface acoustic wave (SAW) filter packages with large cavities. In the 3-D WLP, vertical interconnects were realized using through glass vias (TGVs). To enable such a process scheme, thin glass caps with TGVs were formed through laser-induced chemical etching. Then, glass capping dies were bonded on the corresponding LiTaO <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">3</sub> (LT) device wafer to generate a cavity structure. Partial filling of the vias on the pad was used, and a metal trace was formed on the glass. Ball grid arrays (BGAs) were formed on top of the glass. Finally, an SAW filter WLP was fabricated. This glass capping packaging avoids the outgassing problem of conventional thin-film acoustic packaging at high temperatures, which would cause the contamination of the interdigital transducers (IDTs). In addition, a numerical study based on the 3-D finite element (FE) model has been conducted to analyze the reliability of the package. The built model was applied to perform parametric studies on the effects of package geometry, material properties, and the processing conditions on reliability. Based on the above studies, the optimized SAW filter WLP successfully passed the reliability test of pre-con level 3 and temperature cycling test (TCT, −40 °C ~ 125 °C).

Identification and treatment of the vulnerable coronary plaque.

Acute coronary syndrome mostly arises from rupture or erosion of a vulnerable plaque. Vulnerable plaques typically appear as lipid-rich plaques with a thin cap, called thin-cap fibroatheromas. Various intracoronary imaging techniques can be used to detect vulnerable plaques, such as intravascular ultrasound (IVUS), optical coherence tomography (OCT) and near-infrared spectroscopy (NIRS), each visualizing different high-risk plaque characteristics. IVUS and its post-processing techniques, such as virtual histology IVUS, can primarily be used to identify calcified and soft plaques, while OCT is also able to quantitatively measure the cap thickness. The addition of NIRS allows the exact measurement of lipid content in the plaque. Non-invasive imaging techniques to identify vulnerable plaques, such as computed tomography, are less often used but are evolving and may be of additional diagnostic use, especially when prophylactic treatments for vulnerable plaques are further established. Pharmacological treatment with lipid-lowering or anti-inflammatory medication leads to plaque stabilization and reduction of cardiovascular events. Moreover, the implantation of a stent or scaffold for the local treatment of vulnerable plaques has been found to be safe and to stabilize high-risk plaque features. The use of drug-coated balloons to treat vulnerable plaques is the subject of ongoing research. Future studies should focus on non-invasive imaging techniques to adequately identify vulnerable plaques and further randomized clinical studies are necessary to find the most appropriate treatment strategy for vulnerable plaques.

Engineering Surface Architectures for Improved Durability in III–V Photocathodes

GaInP2 has shown promise as the wide bandgap top junction in tandem absorber photoelectrochemical (PEC) water splitting devices. Among previously reported dual-junction PEC devices with a GaInP2 top cell, those with the highest performance incorporate an AlInP2 window layer (WL) to reduce surface recombination and a thin GaInP2 capping layer (CL) to protect the WL from corrosion in electrolytes. However, the stability of these III-V systems is limited, and durability continues to be a major challenge broadly in the field of PEC water splitting. This work provides a systematic investigation into the durability of GaInP2 systems, examining the impacts of the window layer and capping layer among single junction pn-GaInP2 photocathodes coated with an MoS2 catalytic and protective layer. The photocathode with both a CL and WL demonstrates the highest PEC performance and longest lifetime, producing a significant current for >125 h. In situ optical imaging and post-test characterization illustrate the progression of macroscopic degradation and chemical state. The surface architecture combining an MoS2 catalyst, CL, and WL can be translated to dual-junction PEC devices with GaInP2 or other III-V top junctions to enable more efficient and stable PEC systems.

The influence of high-density lipoprotein cholesterol on maximal lipid core burden indexing thin cap fibrous atheroma lesions as assessed by near infrared spectroscopy

BackgroundPrevious studies suggest that higher plasma concentrations of several lipid molecules are associated with higher lipid core burden index (LCBI) near infrared spectroscopy (NIRS) imaging. The aim of this study was to investigate whether an association between plasma lipids depends on plaque morphology (thin cap fibrous atheroma [TCFA] vs. non-TFCA) as measured by near-infrared spectroscopy–intravascular ultrasound (NIRS-IVUS).MethodsSixty-four patients retrospectively enrolled were diagnosed with stable coronary artery disease or acute coronary syndrome who underwent NIRS-IVUS imaging. Before percutaneous coronary intervention, blood samples were collected for measurement of serum levels of total cholesterol (TC), low-density lipoprotein cholesterol (HDL-C), high-density lipoprotein cholesterol (HDL-C) and triglycerides (TG). Patients were divided into two groups based on maxLCBI4mm and IVUS imaging. Those with maxLCBI4mm ≥ 323 were included into TCFA group (n = 35) while others were assigned to the non-TCFA group (n = 29).ResultsThin cap fibrous atheroma lesions were significantly longer than the non-TCFA lesions (25.66 ± 9.56 vs. 17.03 ± 9.22, p = 0.001). TCFA characterizes greater plaque burden (78.4 [70.9, 82.2] vs. 72.70 [64.77, 76,05]; p = 0.021) and plaque volume (176.1 [110.75, 247.5] vs. 68.1 [55.58, 143.35]; p = 0.000) as compared to non-TCFA. In TCFA suspected lesions, there was no correlation between max-LCBI4mm and LDL levels (r = 0.105, p = 0.549) nor TC levels (r = –0.035, p = 0.844) but a negative correlation was found between HDL-C and maxLCBI4mm (r = −0.453, p = 0.007).ConclusionsThe present study showed that there was no correlation between plasma LDL-C, TC and TG level and the amount of lipids in coronary plaque assessed by NIRS in both TCFA and non-TCFA groups. Only HDL-C correlated with maxLCBI4mm in TCFA lesions.

Sperm acrosome status before and during fertilization in the Chinese hamster (Cricetulus griseus), and observation of oviductal vesicles and globules.

The present study was conducted to determine exact location where the acrosome reaction of fertilizing spermatozoa begins in the oviduct of the Chinese hamster. Unlike spermatozoa of other rodent species, Chinese hamster spermatozoa did not spontaneously undergo the acrosome reaction in fertilization-supporting media. In naturally mated females, spermatozoa in the uterus had intact acrosomes, whereas those in the lower oviductal isthmus had visibly thin acrosomal caps. The acrosomal cap was lost when spermatozoa passed through the cumulus oophorus. Thus, Chinese hamster spermatozoa begin the acrosome reaction in the lower isthmus and complete it in the cumulus oophorus. The mucosal epithelium of the oviductal isthmus released many "transparent" vesicles into the lumen, was very fragile and readily sloughed off by rough handling or rapid flushing with medium. Globular materials that oozed out of the dissected oviduct were most likely mucosa cells destroyed by rough handling. Although the oviducts of Chinese hamsters may be exceptionally delicate, this observation nevertheless warns us to cautiously handle the oviducts of any species when studying oviduct secretions that could be involved in inducing capacitation and the acrosome reaction of spermatozoa within the female genital tract.

Abstract 11050: Sex Differences in Culprit Plaque Characteristics in Acute Coronary Syndromes

Introduction: Despite the significant decline in cardiovascular mortality in women over the past few decades, sex differences in the underlying mechanisms remain poorly understood. Previous postmortem studies have demonstrated differences between men and women in coronary plaque characteristics with a higher prevalence of plaque erosion in young women, but more plaque rupture (PR) in older women after menopause. However, in vivo data are limited. Methods: This study included 1368 patients with acute coronary syndrome undergoing pre-intervention optical coherence tomography (OCT) imaging from a multicenter international registry. The culprit plaque was categorized as plaque rupture, plaque erosion or calcified plaque, and stratified by age. Plaque microstructures at culprit lesion were also analyzed. Results: Sex differences were found in the underlying mechanisms of the culprit lesion: In women a significant ascending trend with age (P&lt;0.001) was observed in PR and plaque vulnerability with lipid rich plaque (P&lt;0.001) and thin cap fibroatheroma (TCFA) (P=0.005), whereas this trend was not obvious in men. In multivariate analysis, age was identified as an independent predictor for PR (odds ratio (OR) 1.039; 95% CI, 1.015-1.062, P &lt;0.001) and for lipid rich plaque (OR 1.054; 95% CI 1.030-1.079, P&lt;0.001) in women. Conclusions: An increasing trend in the prevalence of PR and plaque vulnerability with age was observed only in women but not in men.

Abstract 9862: Correlation of Lipoprotein(a) and Plaque Morphology in Very Young Acute Coronary Syndrome Patients Using Optical Coherence Tomography

Background: Levels of lipoprotein (Lp) (a) are a useful marker for risk stratification of cardiovascular diseases. This genetic biomarker is suggestive of patient predisposition to an acute coronary event. Its correlation with the plaque morphology is yet to be explored with optical coherence tomography (OCT). Aim: To study the correlation of Lp(a) levels and plaque morphology in very young (&lt;35 years) patients presenting with acute coronary syndrome(ACS). Methods: A prospective, single-centre, observational study was conducted at a tertiary-care centre. Very young patients with acute coronary syndrome and fit for OCT guided invasive coronary angiography were included. Lp(a) levels were compared between healthy controls and these very young ACS patients. Correlation of Lp(a) levels and plaque characteristics in very young ACS patients was done using OCT imaging. Results: A total of 80 subjects were enrolled in the study. Out of these 40 were very young ACS and 40 were age matched healthy controls. Mean levels of Lp(a) were 28.10±13.96 nmol/l and 61.20±55.88 nmol/l in healthy controls and very young patients with ACS respectively (p=0.022). In very young patients, plaque rupture and erosion were the mechanism of acute coronary syndrome in 67.5% and 32.5% patients, respectively. Among very young ACS patients, those with Lp(a) levels &lt;75 nmol/l had a mean thin cap fibroatheroma thickness of 96.89±65.52 μm and those with Lp(a) levels ≥75 nmol/l had a mean thin cap fibroatheroma thickness of 67.85±53.80 μm (p=0.158). Conclusion: It was revealed that patients with higher Lp(a) levels had lesser thickness of fibrous cap on OCT imaging compared with lower levels of Lp(a). Lp(a) levels were independently associated with ACS in very young (&lt;35 years) patients, with plaque rupture being the commonest mechanism. Hence, we conclude that higher Lp(a) levels predispose to ACS at a very young age associated with lowering of fibrous cap thickness.

Effect of Activated Carbon in Thin Sand Caps Challenged with Ongoing PCB Inputs from Sediment Deposition: PCB Uptake in Clams (Mercenaria mercenaria) and Passive Samplers.

Ongoing inputs, in the form of sediment deposition along with associated dissolved contaminants, have challenged the assessment of cap performance at contaminated sediment sites. To address this issue, thin 2-3cm layer sand caps amended with activated carbon (AC) were investigated for the remediation of polychlorinated biphenyl (PCB) contaminated marine sediments using 90-day mesocosms. All treatments were challenged with (1) ongoing clean or marker-PCB-spiked sediment inputs and (2) bioturbation. Bioaccumulation in hard clams (filter feeding near the cap-water interface) was evaluated to best understand cap effectiveness, relative to sheepshead minnows (confined to the surface water) and sandworms (which burrowed through the caps). All caps (sand and AC amended sand) provided isolation of native bedded PCBs (i.e., PCBs sourced from the bed), reducing uptake in organisms. Total PCB bioaccumulation in clams indicated that AC addition to the cap provided no benefit with spiked influx, or some benefit (56% reduction) with clean influx. Spiked input PCBs, when added to the depositional input sediment, were consistently detected in clams and passive samplers, with and without AC in the cap. PCB uptake by passive samplers located in the caps did not reflect the performance of the remedy, as defined by clam bioaccumulation. However, PCB uptake by passive samplers in the overlying water reasonably represented clam bioaccumulation results.

Atomic-scale Dopant Integration During CMOS Device Fabrication

As CMOS device dimensions shrink and reach scaling limits, atomic layer-based processing has opened new routes for device fabrication and varied device physics. Atomic precision advanced manufacturing (APAM) for precise placement of dopants in Si either as individual atoms, scanning tunneling microscope (STM)-patterned lines, or as sheets of dopants (a delta layer) opens the opportunity to precisely engineer electronic structure and achieve doping above the traditional solubility limit [1]. APAM processing can complement traditional CMOS devices, modifying or augmenting chips including standard integrated circuits, and here we demonstrate a direct CMOS-integrated process flow for APAM processing.During APAM processing, a clean Si surface is exposed to vapor-phase dopant precursors such as phosphine which adsorb on exposed dangling Si bonds, followed by a thin Si cap. Traditionally, the surface preparation involves flash anneals near 1200 °C to achieve a clean, reconstructed Si surface as well as processing in ultrahigh vacuum for the doping and capping. Atomic-precision patterning is achieved with hydrogen termination then STM-based removal of H using the tip to reach pre-implanted contacts [2], though recent efforts have shown delta layer patterning without the STM using photothermal desorption of the H [3]. The high-temperature surface preparation is incompatible with CMOS process flows, but efforts to reduce the temperature have shown that temperatures of 800 °C or below may be sufficient to produce a clean Si surface [2,4].For direct integration of APAM structures in a CMOS flow, the middle-of-line processing near CMOS contact formation is a natural insertion point, when the device Si is accessible but the transistors’ high-temperature gate and dopant activation steps are finished. We estimate that APAM processing requires temperatures of 400-800 °C for surface preparation, but after APAM processing the devices should stay below about 600 °C to avoid dopant diffusion. By doing APAM processing before metal (copper or aluminum) deposition, the low 500-600 °C limit for MEMS-on-CMOS processing may be avoided [5].As a test platform, custom CMOS devices were fabricated in Sandia’s fab using the 0.35-micron node, including both discrete transistors and simple circuits such as gates and ring oscillators. Specialized cells in the layout enable the demonstration of APAM doping integrated with CMOS elements, with minimal changes to the CMOS flow and masks. After completing gate formation, the wafers are pulled near the contact module for UHV APAM processing, then finished with metallization in a separate fab to do electrical testing.Initial tests subjecting the CMOS chips to surface preparation techniques used for APAM processing show that the CMOS circuits can survive gentle flash anneals and sputter cleans, even when silicide and tungsten contacts are already in place. More in-depth rapid thermal anneal (RTA) studies of the chips’ thermal budget reveal degradation in drive currents and threshold voltages in n-channel devices starting about 600 °C, but switching operation is maintained through 800 °C where the tungsten contacts begin to severely degrade. Current work is ongoing to process samples without tungsten contacts already in place and to achieve delta layer doping on these chips. Our goal is to demonstrate atomic layer doping directly integrated with a CMOS process flow.In summary, atomic-precision device doping is integrated with a standard CMOS process flow, with the thermal budget of both the APAM and CMOS elements determining the fab requirements. If silicide and tungsten contacts are in place, the Si surface preparation techniques are limited to a temperature of about 600 °C which should be compatible with low-temperature options such as Ne sputtering and gentle anneals.SNL is managed and operated by NTESS under DOE NNSA contract DE-NA0003525.[1] B. Weber et al., Science 335, 64 (2012).[2] D. R. Ward et al., Appl. Phys. Lett. 111, 193101 (2017).[3] A. M. Katzenmeyer et al., J. Micro/Nanopattern. Mats. Metro. 20, 014901 (2021).[4] T. Skeren et al., Nanotechnology 29, 435302 (2018).[5] H. Takeuchi et al., IEEE Transactions on Electron Devices 52, 2081 (2005).

Prognostic implications of cholesterol chrystals at ACS causing culprit lesions, insights from the translational OPTICO-ACS study program

Abstract Aims Cholesterol chrystals (CC) represent a feature of advanced plaque remodeling. Optical coherence tomography (OCT) allows for detailed morphological assessment of the culprit lesion, including the presence of CCs, in vivo. Since CCs have been identified as prognostically relevant plaque feature in coronary artery disease (CAD), the present analysis aims to further characterize their impact on adverse cardiovascular outcome in a large cohort of patients, presenting with acute coronary syndrome (ACS). Methods Within the translational OPTICO-ACS study program, 371 consecutive ACS-patients were included into the final analysis. OCT-characteristics, including the presence of CCs, were assessed by a standardized CoreLab analysis following universal consensus standards for OCT-derived plaque features. All patients were followed up for 12 months after the index event and major adverse cardiac events (MACE) consisting of death, myocardial infarction, target vessel revascularization plus re-hospitalization due to unstable or progressive angina pectoris were documented. Results 215 patients (58.1%) presented with cholesterol chrystals (CCs) at the culprit lesion. Plaque rupture (RFC-ACS) represented the primary ACS-causing pathophysiology (75.3%) in those patients. Further, the presence of CCs was associated with other high-risk features within the culprit lesion, i.e. the presence of thin cap fibroatheroma (77.7% vs. 63.2%; p&amp;lt;0.05), plaque calcification (80.5% vs. 67.1; p&amp;lt;0.01) and microchannels (80.1% vs. 70.1; p&amp;lt;0.05) as well as an increased area stenosis (0.77 vs. 0.73 mm2; p&amp;lt;0.01) and a greater maximum lipid arc (282.8 vs. 242.6°; p&amp;lt;0.01) as compared to culprit lesions free of CCs. Of note, there was a strong association among the occurrence of macrophages within the plaque and cholesterol crystals. Finally, and most importantly MACE during 12 months follow-up, consisting of cardiac death, myocardial infarction, target vessel revascularization and re-hospitalization due to progressive or unstable angina pectoris, occurred with nearly twice the frequency in CC-patients (20.3% vs. 10.6%; p&amp;lt;0.01) as compared to patients without CCs at the culprit site. Conclusion The present analysis introduces cholesterol chrystals as a novel prognostically relevant high-risk plaque feature allowing individual risk stratification for patients after ACS. Funding Acknowledgement Type of funding sources: None.

Manipulation of blue TADF top-emission OLEDs by the first-order optical cavity design: toward a highly pure blue emission and balanced charge transport

The broad luminescence spectrum of a thermally activated delayed fluorescence (TADF) organic light-emitting diode (OLED) is a critical issue to overcome for its application in high-color-purity displays. Herein, a novel device structure that utilizes the first-order microcavity optical mode with a high radiance intensity is demonstrated to solve this problem by considering the charge transport properties through the analysis of hole-only and electron-only devices. In addition, by tuning the optical interference near the semitransparent top cathode layers consisting of thin silver and organic capping layers, light extraction is increased by nearly 2 times compared to the device without a capping layer. Consequently, the optimized blue TADF top-emission OLED exhibits much lower full width at half-maximum, higher maximum current efficiency, and external quantum efficiency compared to the device before optimization. This approach is expected to provide a simple but effective way to further enhance the spectral purity of the conventional TADF-based OLEDs.

Zn-Doped CaP-Based Coatings on Ti–6Al–4V and Ti–6Al–7Nb Alloys Prepared by Magnetron Sputtering: Controllable Biodegradation, Bacteriostatic, and Osteogenic Activities

New TiNb-based alloys, such as Ti–6Al–7Nb, are currently being studied around the world as an alternative to other Ti alloys, e.g., instead of Ti–6Al–4V. We conducted a pilot study where thin (approximately 1.2 micron) CaP coatings containing low doses of Zn2+ (0.4–0.8 wt.%) were prepared by the radio frequency magnetron sputtering (RFMS) of Zn-hydroxyapatite (HA) target on Ti–6Al–4V and Ti–6Al–7Nb substrates and investigated their physicochemical properties, in vitro solubility, cytotoxicity, and antibacterial and osteogenic activities. The thickness of the obtained coatings was approximately 1.2–1.3 microns. Zn substitution did not result in roughness or structural or surface changes in the amorphous CaP coatings. The distributions of Ca, P, and Zn were homogeneous across the film thickness as shown by the EDX mapping of these elements. Zn doping of CaP coatings on both types of Ti-based alloys statistically influenced the results of the scratch-test. However, obtained values are satisfactory to use Zn-CaP coatings on biomedical implants. Increased Zn2+ release vs. tapered output of Ca and phosphate ions occurred during 5 weeks of an in vitro immersion test in 0.9% NaCl solution. Ti–6Al–7Nb alloy, unlike Ti–6Al–4V, promoted more linear biodegradation of CaP coatings in vitro. As a result, CaP-based surfaces on Ti–6Al–7Nb, compared with on Ti–6Al–4V alloy, augmented the total areas of Alizarin red staining in a 21-day culture of human adipose-derived mesenchymal stem cells in a statistically significant manner. Moreover, Zn–CaP coatings statistically reduced leukemic Jurkat T cell survival within 48 h of in vitro culture. Along with the higher solubility of the Zn–CaP surface, a greater reduction (4- to 5.5-fold) in Staphylococcus aureus growth was observed in vitro when 7-day extracts of the coatings were added into the microbial culture. Hence, Zn–CaP-coated Ti–6Al–7Nb alloy with controllable biodegradation as prepared by RFMS is a prospective material suitable for bone applications in cases where there is a risk of bacterial contamination with severe consequences, for example, in leukemic patients. Further research is needed to closely investigate the mechanical features and pathways of their solubility and antimicrobial, antitumor, and osteogenic activities.

Development and Reliability Study of 3-D Wafer Level Packaging for SAW Filter Using Thin Film Capping

The rapid growth of the advanced consumer 5G wireless mobile phones has propelled the demands of fabricating surface acoustic wave (SAW) filters with smaller size and high performance. Three-dimension wafer-level package (3-D WLP) for SAW filter is a promising solution to replace conventional surface mounted technology and chip-scale packaging. In this article, a new WLP for SAW filter with a size of 1.3 mm ×1.1 mm ×0.35 mm is developed using thin dry film capping. The new 3-D WLP significantly reduces the overall thickness which is particularly meaningful for low-profile smartphones and tablets. A number of key processes were developed. To improve the quality, finite element modeling (FEM) is used to simulate the mechanical stress to optimize cavity structure. Reliability tests were performed and the results indicated that there were no significant frequency response changes occurred and low insertion loss (IL) in pass band was less than 0.2 dB after pro-conditional level 3 test, unbiased highly accelerated stress (uHAST) test, and temperature cycling (TC) test on SAW filter packages. It can be concluded that 3-D WLP for SAW filter achieves miniaturization, good electrical performance, and reliability.

The Optical Coherence Tomographic Findings Which Predict Outcome of Calcified Coronary Lesions after Percutaneous Coronary Intervention: A Serial Follow-up Study

Objective: Imaging modalities such as intravascular ultrasonography or computed tomography or angiography have shown limitations in assessing coronary calcification. In this study, we investigated whether quantitative indices of optical coherence tomography (OCT) in calcified lesions are correlated with the late outcome of a coronary stent.Methods: We consecutively enrolled patients who had more than grade 2 coronary calcification on fluoroscopy. OCT was performed at baseline, immediately after stenting, and at 9 months after stenting. We analyzed qualitative and quantitative characteristics of plaque, calcification, and stent-related indices.Results: All images of 3-time points were available in a total of 10 patients. Calcified lesions were frequently associated with thin cap fibroatheroma (100%), plaque erosion (20%), or rupture (20%) before the procedure. Thrombus was found in 100% of cases in the OCT immediately after stenting. Maximal calcium area before stenting was strongly correlated with late luminal loss assessed by 9-month follow-up OCT (r= 0.766, P= 0.01).Conclusion: Preprocedural OCT assessment on calcified coronary lesion may predict high-risk procedure and late stent outcome. Further studies are warranted to confirm these findings.

The Association Between Quantitative Flow Ratio and Intravascular Imaging-defined Vulnerable Plaque Characteristics in Patients With Stable Angina and Non-ST-segment Elevation Acute Coronary Syndrome.

Background: This study aimed to examine whether quantitative flow ratio (QFR), an angiography-based computation of fractional flow reserve, was associated with intravascular imaging-defined vulnerable plaque features, such as thin cap fibroatheroma (TCFA) in patients with stable angina, and non-ST-segment elevation acute coronary syndrome.Methods: Patients undergoing optical coherence tomography (OCT) or intravascular ultrasound (IVUS) examinations were identified from two prospective studies and their interrogated vessels were assessed with QFR. Lesions in the OCT cohort were classified into tertiles: QFR-T1 (QFR ≤ 0.85), QFR-T2 (0.85 < QFR ≤ 0.93), and QFR-T3 (QFR > 0.93). Lesions in the IVUS cohort were classified dichotomously as low or high QFR groups.Results: This post-hoc analysis included 132 lesions (83 for OCT and 49 for IVUS) from 126 patients. The prevalence of OCT-TCFA was significantly higher in QFR-T1 (50%) than in QFR-T2 (14%) and QFR-T3 (19%) (p = 0.003 and 0.018, respectively). Overall significant differences were also observed among tertiles in maximum lipid arc, thinnest fibrous cap thickness, and minimal lumen area (p = 0.017, 0.040, and <0.001, respectively). Thrombus was more prevalent in QFR-T1 (39%) than in QFR-T2 (3%), and QFR-T3 (12%) (p = 0.001 and 0.020, respectively). In the multivariable analysis, QFR ≤ 0.80 remained as a significant determinant of OCT-TCFA regardless of the presence of NSTE-ACS and the level of low-density lipoprotein cholesterol (adjusted OR: 4.387, 95% CI 1.297–14.839, p = 0.017). The diagnostic accuracy of QFR was moderate in identifying lesions with OCT-TCFA (area under the curve: 0.72, 95% CI 0.58–0.86, p = 0.003). In the IVUS cohort, significant differences were found between two groups in minimal lumen area and plaque burden but not in the distribution of virtual histology (VH)-TCFA (p = 0.025, 0.036, and 1.000, respectively).Conclusions: Lower QFR was related to OCT-defined plaque vulnerability in angiographically mild-to-intermediate lesions. The QFR might be a useful tool for ruling out high-risk plaques without using any pressure wire or vasodilator.