In the past, perfect metamaterial absorbers (PMAs) have required nanolithography patterning to boost broadband absoprtion. Tapered structures, in particular, are shown to achieve close-to-unity ...absorption over broadband using adiabatic light coupling. A nontapered PMA is desirable due to the fact that it is easier to fabricate using regular lithography techniques. This facilitates the scalability to large-area photonic applications such as thermophotovoltaics. In this work, we propose a fully planarized design with ultrathin metallic films for broadband PMAs. The design provides close-to-unity absorbance over a wide spectral range and is wavelength scalable from middle ultraviolet to long wavelength infrared. The planarized design is extremely easy to fabricate, and it requires no lithography nor etching. The design can be used with different moderate-extinction metals such as tungsten, titanium, tantalum, and nickel. The physics is that the thin layer of the moderate-extinction metal allows photons to penetrate through itself. The insertion of the dielectric between thin metal layers is necessary to spatially separate the ultrathin metallic thin film to boost the effect of thin-film absorption. As far as the bandwidth normalized to center wavelength is concerned, we believe that the experimental result demonstrated here shows the broadest bandwidth to date.
We propose an extremely simple multiple-metal metamaterial perfect absorber (MPA). The dimension of our proposed design is only 221 nm for the visible wavelength range from 400 to 700 nm. This is ...comparable with past efforts on MPAs using plasmonics at the same wavelength range, whereas the plasmonic excitation is absent in our proposal. A unity broadband absorption can be achieved with ultrathin metallic films. In addition, the wavelength scalability is possible using our design, and the fully planar simple configuration facilitates large-area photonic design without the need for lithography and etching. The physics is the field penetration and the field absorption for the photons at different wavelength ranges using different metallic layers. We also show that the adjustment of the individual layer thickness is critical to attaining a perfect wave impedance matching to vacuum. The titanium (Ti), nickel (Ni), and aluminum (Al) triple-metal configuration is used to demonstrate the concept experimentally, and a close match to the theoretical result is observed. The absorption band can be further widened with more stacking layers with various metals. We believe that the proposed design is very promising in the aspects of simple processing and scalable for large-area broadband unity absorption. It thus improves the future implementation of MPAs and facilitates a wide range of relevant applications.
A novel scheme for a perfect hyperbolic metamaterial (HMM) absorber is proposed, and experimental verification is provided. It has been shown previously that tapered HMM stacks can provide adiabatic ...waveguiding over a wide spectral range and thus are an ideal opaque absorber. Here, nontapered shape-optimized HMM absorbers are proposed, which facilitates the fabrication and promotes the large-area applications such as thermophotovoltaics (TPV). In the synthesis of the optimal patterns, we use 5-harmonic rigorously coupled wave analysis (RCWA) and experimental trials to shorten the trial-and-error time. The best pattern provides an averaged broadband experimental absorption of 88.38% over λ = 1 μm to λ = 2 μm, which is comparable to the state-of-the-art experimental effort using tapered HMM. The nontapered nature can be easier to fabricate from the semiconductor processing viewpoint. The physics behind the pattern-optimized HMM cavity is the broadband light coupling by the air-cavity and the unbounded photonic density of the states (PDOS) associated with the HMM. The topology optimized air cavity effectively couples the incident photons into the metal-dielectric stacking, eliminating the need of sidewall tapers. We believe the proposed topology-optimization methodology benefits the future design of compact metamaterial perfect absorbers (MPA), sensors, antenna, and thermophotovoltaic emitters, and absorbers.
Compared with conventional solar cells, thermophotovoltaics (TPV) can be more efficient and, thus, exceeds the detailed balance efficiency limit. In particular, the emitter of TPV is a critical ...design since it determines whether the thermalization loss can be reduced and whether the sub-band-gap radiation can be suppressed, as far as the photovoltaic (PV) process is concerned. In this paper, we propose a selective planar emitter composed of alternating ultrathin metal and dielectric layers. An aperiodic dielectric stacking is designed to tailor the emission spectrum by shaping the emission peak and by adjusting the emission wavelength. We show that the peak emission wavelength (λ emission ) is adjustable from λ = 1500 nm to λ = 2500 nm. Furthermore, the long-wavelength cutoff is very sharp for our proposed emitter structure, and the absorption is suppressed to 0.1 beyond the cutoff. The preliminary experiment is also conducted to fulfill the concept of a fully planar ultrathin refractory metal emitter design, and the result is similar to the calculated ones. We believe that the planar thermal emitter based on ultrathin metals and aperiodic dielectric stacking is very promising for future thermal emission applications since it requires no lithography and etching, provides strong peak emission power, and possesses wide wavelength scalability.
Indoleamine 2,3-dioxygenase 1 (IDO1), promoting immune escape of tumors, is a therapeutic target for the cancer immunotherapy. A number of IDO1 inhibitors have been identified, but only limited ...structural biology studies of IDO1 inhibitors are available to provide insights on the binding mechanism of IDO1. In this study, we present the structure of IDO1 in complex with 24, a NLG919 analogue with potent activity. The complex structure revealed the imidazole nitrogen atom of 24 to coordinate with the heme iron, and the imidazoleisoindole core situated in pocket A with the 1-cyclohexylethanol moiety extended to pocket B to interact with the surrounding residues. Most interestingly, 24 formed an extensive hydrogen bond network with IDO1, which is a distinct feature of IDO1/24 complex structure and is not observed in the other IDO1 complex structures. Further structure–activity relationship, UV spectra, and structural biology studies of several analogues of 24 demonstrated that extensive hydrophobic interactions and the unique hydrogen bonding network contribute to the great potency of imidazoleisoindole derivatives. These results are expected to facilitate the structure-based drug design of new IDO inhibitors.
In this work, we present the result of nickel (Ni)-based metamaterial perfect absorbers (MPA) with ultra-broadband close-to-one absorbance. The experimental broadband characteristic is significantly ...improved over the past effort on metamaterial perfect absorbers. An in-depth physical picture and quantitative analysis is presented to reveal the physical origin of its ultrabroadband nature. The key constituent is the cancellation of the reflected wave using ultra-thin, moderate-extinction metallic films. The ultra-thin metal thickness can reduce the reflection as the optical field penetrates through the metallic films. This leads to minimal reflection at each ultra-thin metal layer, and light is penetrating into the Ni/SiO
stacking. More intuitively, when the layer thickness is much smaller than the photon wavelength, the layer is essentially invisible to the photons. This results in absorption in the metal thin-film through penetration while there is minimal reflection by the metal film. More importantly, the experimental evidence for omni-directionality and polarization-insensitivity are established for the proposed design. Detailed measurement is conducted. Due to the ultrathin metal layers and the satisfactory tolerance in dielectric thickness, the broadband absorption has minimal degradation at oblique incidence. Such a wide angle, polarization-insensitive, ultra-broadband MPA can be very promising in the future, and the optical physics using sub-skin-depth metal film can also facilitate miniaturized high-performance nano-photonic devices.
Chronic kidney disease (CKD) is a global health problem with a high economic burden, which is particularly prevalent in Taiwan. Mobile health apps have been widely used to maintain continuity of ...patient care for various chronic diseases. To slow the progression of CKD, continuity of care is vital for patients' self-management and cooperation with health care professionals. However, the literature provides a limited understanding of the use of mobile health apps to maintain continuity of patient-centered care for CKD.
This study identified apps related to the continuity of patient-centered care for CKD on the App Store, Google Play, and 360 Mobile Assistant, and explored the information and frequency of changes in these apps available to the public on different platforms. App functionalities, like patient self-management and patient management support for health care professionals, were also examined.
We used the CKD-related keywords "kidney," "renal," "nephro," "chronic kidney disease," "CKD," and "kidney disease" in traditional Chinese, simplified Chinese, and English to search 3 app platforms: App Store, Google Play, and 360 Mobile Assistant. A total of 2 reviewers reached consensus on coding guidelines and coded the contents and functionalities of the apps through content analysis. After coding, Microsoft Office Excel 2016 was used to calculate Cohen kappa coefficients and analyze the contents and functionalities of the apps.
A total of 177 apps related to patient-centered care for CKD in any language were included. On the basis of their functionality and content, 67 apps were recommended for patients. Among them, the most common functionalities were CKD information and CKD self-management (38/67, 57%), e-consultation (17/67, 25%), CKD nutrition education (16/67, 24%), and estimated glomerular filtration rate (eGFR) calculators (13/67, 19%). In addition, 67 apps were recommended for health care professionals. The most common functionalities of these apps were comprehensive clinical calculators (including eGFR; 30/67; 45%), CKD medical professional information (16/67, 24%), stand-alone eGFR calculators (14/67, 21%), and CKD clinical decision support (14/67, 21%). A total of 43 apps with single- or multiple-indicator calculators were found to be suitable for health care professionals and patients. The aspects of patient care apps intended to support self-management of CKD patients were encouraging patients to actively participate in health care (92/110, 83.6%), recognizing and effectively responding to symptoms (56/110, 50.9%), and disease-specific knowledge (53/110, 48.2%). Only 13 apps contained consulting management functions, patient management functions or teleconsultation functions designed to support health care professionals in CKD patient management.
This study revealed that the continuity of patient-centered care for CKD provided by mobile health apps is inadequate for both CKD self-management by patients and patient care support for health care professionals. More comprehensive solutions are required to enhance the continuity of patient-centered care for CKD.
A wireless electronic endoscope that transmits signals by Wi-Fi is developed for use in single-hole endoscopic surgery and future application to natural orifice surgery. The innovative electronic ...endoscope developed in this study has a disposable design, completely preventing patents from taking risks of cross infection. The main components of the endoscope are a disposable component of the front tip and the hand-held part of the rear tip. The front tip consists of a lens, metallic tube, and electronic joint whereas the rear tip consists of a power switch, image converter, wireless transceiver chip, and antenna. Experimental applications of the wireless electronic endoscope show that after 3 hours and 30 minutes of normal use, the temperature of metallic tube at the front tip averages 45 °C. Regarding the measured luminance result, when the focal distance is 5 cm, luminance reaches 1410 lux. In an indoor environment, when the measured distance is 3 m and there is no disruptor, the Wi-Fi transmitted signal of the endoscope is at strength −51 dBm. If the disruptor is established between the sending and receiving ends, signal strength is −53 dBm. Increasing the measured distance to 8 m obtains a signal strength of −74 dBm. Test practical applications indicate that the wireless Wi-Fi electronic endoscope fully meets the needs of surgery room.
This study examined staff perceptions of planned obsolescence during a transition from old to new handheld devices for long-term mobile healthcare. Questionnaires based on the technology acceptance ...model were used to evaluate perceived ease of use and usefulness. This study recruited 120 staff from 26 long-term care facilities who used the old device and 86 staff from nine of the 26 original facilities who used the new device. Although the new devices with advanced features scored significantly higher in acceptance ratings, users still expressed high acceptance of, satisfaction with, and willingness to use the old device, which featured an effective and carefully designed user interface. Usability design plays an essential role in preventing the obsolescence of mobile handheld technology.
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