56016 research outputs found
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No full textEffect of steric hindrance on the interfacial connection of MOF-on-MOF architectures
No full textMOF-on-MOF is attracting great attention due to its improved and/or synergistic properties not exhibited in a single MOF. In particular, the non-isostructural pairs of MOF-on-MOFs can have great potential induced by large heterogeneity, which enables diverse applications in a wide range of fields. HKUST-1@IRMOF is a fascinating platform because the alteration of the IRMOF pores with bulkier substituent groups on the ligands can provide a more microporous environment. However, the sterically hindered linker can affect the seamless growth at the interface, an important issue in practical research fields. Despite many efforts to reveal the growth of a MOF-on-MOF, there is still a lack of studies on a MOF-on-MOF consisting of a sterically hindered interface. Indeed, the effect of a bulky linker at an interface of HKUST-1@IRMOF, a non-isostructural MOF-on-MOF system, has not yet been reported, and thus, how the interfacial strain affects the interfacial growth remains unknown. In this study, we investigate the effect of an interfacial strain on a chemical connection point in an MOF-on-MOF system through a series of theoretical and synthetic experiments using a HKUST-1@IRMOF system. Our results reveal the importance of the proximity of each coordinating site at a MOF-on-MOF interface as well as lattice parameter matching for an effective secondary growth to achieve a well-connected MOF-on-MOF
A practical approach based on learning-based model predictive control with minimal prior knowledge of patients for artificial pancreas
No full textBackground and objectives: Complete identification of the glucose dynamics for a patient generally re-quires prior clinical procedures and several measurements for the patient. However, these steps may not be always feasible. To address this limitation, we propose a practical approach integrating learning-based model predictive control (MPC), adaptive basal and bolus injections, and suspension with minimal re-quirements of prior knowledge of the patient. Methods: The glucose dynamic system matrices were periodically updated using only input values, with-out any pretrained models. The optimal insulin dose was calculated based on a learning-based MPC al-gorithm. Meal detection and estimation modules were also introduced. The basal and bolus insulin in-jections were fine-tuned using the performance of glucose control from the previous day. To validate the proposed method, evaluations with 20 virtual patients from a type 1 diabetes metabolic simulator were employed. Results: Time-in-range (TIR) and time-below-range (TBR) were 90.8% (84.1% - 95.6%) and 0.3% (0% - 0.8%), as represented by the median, first (Q1), and third quartiles (Q3), respectively, when meal intakes were fully announced. When one out of three meal intake announcements was missing, TIR and TBR were 85.2% (75.0% - 88.9%) and 0.9% (0.4% - 1.1%), respectively. Conclusions: The proposed approach obviates the need for prior tests from patients and shows effective regulation of blood glucose levels. From the perspective of practical implementation in clinical environ-ments, to deal with minimal prior information of the patient, our study demonstrates how essential clin-ical knowledge and learning-based modules can be integrated into a control framework for an artificial pancreas. & COPY; 2023 Elsevier B.V. All rights reserved
Ultrathin Superhydrophobic Coatings for Air-Stable Inorganic Solid Electrolytes: Toward Dry Room Application for All-Solid-State Batteries
No full textInorganic solid electrolytes (SEs), such as sulfides and halides, are crucial for developing practical all-solid-state batteries (ASSBs) owing to their high ionic conductivities and mechanical sinterabilities. However, their sensitivity to humid air necessitates stringent dry-room conditions during processing, which increases production costs. This study demonstrates that ultrathin (& AP;5 nm) superhydrophobic polydimethylsiloxane (PDMS) or fluorinated PDMS (F-PDMS) protective layers can enhance the stability of air-sensitive sulfide (Li6PS5Cl (LPSCl)) and halide (Li2.5Zr0.5In0.5Cl6) SEs in ASSBs. The (F)-PDMS coatings are applied using a scalable, straightforward vapor-phase deposition process, achieving high Li+ conductivity retention (92%, from 2.5 to 2.3 mS cm-1 at 30 & DEG;C). The protective layers effectively inhibit LPSCl degradation under practically relevant dry room conditions (dew point of -50 & DEG;C or -10 & DEG;C): e.g., from 2.3 to 0.97 mS cm-1 for PDMS-coated LPSCl versus from 2.5 to 0.57 mS cm-1 for bare LPSCl. Surprisingly, the superhydrophobic coatings facilitate the recovery of Li+ conductivity via vacuum heat treatment. This new phenomenon, known as regeneration, is achieved by the facile elimination of adsorbed water. Furthermore, the regenerated (F)-PDMS-coated LPSCl demonstrates significant performance in NCM||Li-In ASSB cells. These findings suggest that superhydrophobic (F)-PDMS coatings are a promising solution for practical all-solid-state technologies. Superhydrophobic coating strategies for air-stable inorganic solid electrolytes are designed using a facile vapor deposition method. The ultrathin 5 nm-thick layers suppress degradation by atmospheric air by blocking the intrusion of moisture and facilitate the recovery of Li+ conductivity by vacuum heat treatment. The layers exhibit excellent performance in dry room applications.imag
Novel tongue-positioning device to reduce tongue motions during radiation therapy for head and neck cancer: Geometric and dosimetric evaluation
No full textThis study aimed to assess the performance of a tongue-positioning device in interfractional tongue position reproducibility by cone-beam computed tomography (CBCT). Fifty-two patients treated with radiation therapy (RT) while using a tongue positioning device were included in the study. All patients were treated with 28 or 30 fractions using the volumetric modulated arc therapy technique. CBCT images were acquired at the 1(st), 7(th), 11(th), 15(th), 19(th), 23(th), and 27(th) fractions. Tongues on planning computed tomography (pCT) and CBCT images were contoured in the treatment planning system. Geometric differences in the tongue between pCT and CBCT were assessed by the Dice similarity coefficient (DSC) and averaged Hausdorff distance (AHD). Two-dimensional in vivo measurements using radiochromic films were performed in 13 patients once a week during sessions. The planned dose distributions were compared with the measured dose distributions using gamma analysis with criteria of 3%/3 mm. In all patients, the mean DSC at the 1(st) fraction (pCT versus 1st CBCT) was 0.80 while the mean DSC at the 27(th) fraction (pCT versus 27th CBCT) was 0.77 with statistical significance (p-value = 0.015). There was no statistically significant difference in DSC between the 1st fraction and any other fraction, except for the 27(th) fraction. There was statistically significant difference in AHD between the 1st fraction and the 19th, 23(th), and 27(th) fractions (p-value < 0.05). In vivo measurements showed an average gamma passing rate of 90.54%. There was no significant difference between measurements at the 1(st )week and those at other weeks. The tongue geometry during RT was compared between pCT and CBCT. In conclusion, the novel tongue-positioning device was found to minimize interfractional variations in position and shape of the tongue
Power Decoupling Methods of Four-Port Dual-Active-Bridge Converter for Grid-Connected and Islanding Modes
No full textThis study proposed a power decoupling method for a four-port dual-active-bridge (DAB) converter for grid-connected and islanding operation modes. Four-port converters based on the DAB converter have recently attracted attention due to its capability to transfer power in a bidirectional manner and its high power density in DC microgrid systems. The four-port converter can also be connected to various distributed resources. However, this converter causes a power coupling problem where the unintended power induces poor dynamic performance and prevents the converter from effectively regulating the output voltage. Conventional four-port converters use three inductors to prevent a power coupling problem among output ports. However, this conventional method cannot transfer power when the operating mode transitions from the grid-connected mode to the islanding mode. The proposed power decoupling method for the four-port DAB converter employs a relay circuit for the coupling inductors. Using this method, the power decoupling phenomenon was mitigated in both the grid-connected and islanding modes. A 3 kW prototype four-port DAB converter was implemented to verify the validity and performance of the proposed power decoupling method
Shape-Configurable MXene-Based Thermoacoustic Loudspeakers with Tunable Sound Directivity
No full textFilm-type shape-configurable speakers with tunable sound directivity are in high demand for wearable electronics. Flexible, thin thermoacoustic (TA) loudspeakers-which are free from bulky vibrating diaphragms-show promise in this regard. However, configuring thin TA loudspeakers into arbitrary shapes is challenging because of their low sound pressure level (SPL) under mechanical deformations and low conformability to other surfaces. By carefully controlling the heat capacity per unit area and thermal effusivity of an MXene conductor and substrates, respectively, it fabricates an ultrathin MXene-based TA loudspeaker exhibiting high SPL output (74.5 dB at 15 kHz) and stable sound performance for 14 days. Loudspeakers with the parylene substrate, whose thickness is less than the thermal penetration depth, generated bidirectional and deformation-independent sound in bent, twisted, cylindrical, and stretched-kirigami configurations. Furthermore, it constructs parabolic and spherical versions of ultrathin, large-area (20 cm x 20 cm) MXene-based TA loudspeakers, which display sound-focusing and 3D omnidirectional-sound-generating attributes, respectively. Ultrathin MXene thermoacoustic loudspeakers with the capability of shape configurations provide directivity-tunable and high sound generation under different mechanical deformations. MXene conductors with low heat-capacity-per-unit-area and parylene substrates with low thermal effusivity enable bidirectional and stable sound in concave/convex, on-needle, folded, and twisted configurations. High conformability can be affixed to diverse 3D surfaces, enabling focused and omnidirectional sound generation.imag
