Concurrent Spatial Mapping of the Viscoelastic Behavior of Heterogeneous Soft Materials Via a Polymer-Based Microfluidic Device

This dissertation presents a novel experimental technique, namely concurrent spatial mapping (CSM), for measuring the viscoelastic behavior of heterogeneous soft materials via a polymer-based microfluidic device. Comprised of a compliant polymer microstructure and an array of electrolyte-enabled distributed resistive transducers, the microfluidic device detects both static and dynamic distributed loads. Distributed loads deform the polymer microstructure and are recorded as resistance changes at the locations of the transducers. The CSM technique identifies the elastic modulus of soft materials by applying a precisely controlled indentation depth using a rigid probe to a sample placed on the device. The spatially-varying elastic modulus of the sample translates to a non-uniform load, causing a non-uniform deformation of the microstructure and variations in the recorded resistance changes. The CSM technique measures the loss modulus of soft materials through a dynamic measurement by applying varying sinusoidal loads to a sample placed on the device. The spatially-varying loss modulus of the sample causes the microstructure to respond with corresponding time delay. Consequently, the phase shift between the sinusoidal load and deflection of the sample along its length are captured by the distributed transducers. As the first step of the experimental protocol, control experiments are implemented on the device to determine its static performance and system-level dynamic parameters. Next, the CSM technique is applied to both homogeneous and heterogeneous synthetic soft materials to measure their elastic moduli by applying a precisely controlled indentation depth through a probe, and the recorded load and device deflection are the output. The data are processed to obtain the overall load and the deflection of the sample at each transducer location and are further used to extract the elastic modulus distribution of the sample. The CSM technique is then applied to measure the loss modulus of soft materials. The measurable sinusoidal loads are the input, and the sinusoidal deflections of the device are the output. By applying the Fast Fourier Transform (FFT) algorithm and the nonlinear regression method, the data are processed to obtain the phase shift between the applied load and the device response along its microchannel length as well as the system-level parameters, namely stiffness (K), damping coefficient (D), and mass (M). In conjunction with the system-level parameters of the system with the device, obtained from the control experiment, the stiffness and the damping coefficient of a sample are calculated, and the sample’s loss modulus distribution is estimated accordingly. This CSM technique successfully measures the spatially-varying elastic modulus and loss modulus of soft materials. As compared with the nanoindentation-based technique, the CSM technique demonstrates its efficiency in spatially mapping the viscoelastic behavior of a sample without excluding interactions among neighboring compositions in a sample

A Sterically Congested Nitrogenated Benzodipentaphene with a Double π-Expanded Helicene Structure

Herein, we describe a series of three sterically congested nitrogenated benzodipentaphenes, one of which shows a highly distorted aromatic backbone with an unprecedented double π-expanded helicene structure.A.M.-A. acknowledge support of the Basque Science Foundation for Science (Ikerbasque), POLYMAT, the University of the Basque Country (Grupo de Investigación No. GIU17/054), Gobierno Vasco (No. PIBA 2019-09 and BERC program), and Gobierno de España (Ministerio de Economı́a y Competitividad No. CTQ2016-77970-R) and thank for technical and human support provided by SGIker of UPV/EHU and European funding (ERDF and ESF). F.C. and A.M.-A acknowledge that this project has received funding from the European Union’s Horizon 2020 Research and Innovation Programme, under the Marie Skłodowska-Curie Grant Agreement No. 839626. A.M.-A. acknowledge that this project has received funding from the European Research Council (ERC) under the European Union’s Horizon 2020 Research and Innovation Programme (Grant Agreement No. 722951). A.S. acknowledges the support of Japan Society for the Promotion of Science (JSPS) with the KAKENHI Grant-in-Aid for Scientific Research (A) (Grant No. JP16H02285). M.M.-F. acknowledges support from the Portuguese Foundation for Science and Technology (FCT), under the project IF/00894/2015, and the project CICECO-Aveiro Institute of Materials, FCT ref. UID/CTM/50011/2019, UIDB/50011/2020, and UIDP/50011/2020, financed by national funds through the FCT/MEC and, when appropriate, cofinanced by FEDER, under the PT2020 Partnership Agreement

Informing a risk prediction model for binary outcomes with external coefficient information

Peer Reviewedhttps://deepblue.lib.umich.edu/bitstream/2027.42/146799/1/rssc12306-sup-0001-SupInfo.pdfhttps://deepblue.lib.umich.edu/bitstream/2027.42/146799/2/rssc12306_am.pdfhttps://deepblue.lib.umich.edu/bitstream/2027.42/146799/3/rssc12306.pd

A POLYMER-BASED MICROFLUIDIC RESISTIVE SENSOR FOR DETECTING DISTRIBUTED LOADS

ABSTRACT This paper reports on a polymer-based microfluidic resistive sensor for detecting distributed loads. The sensor is comprised of a polymer rectangular microstructure with an embedded electrolyte-filled microchannel and an array of electrodes aligned along the microchannel length. Electrolyte solution in the microchannel serves as impedance transduction. Distributed loads acting on the polymer microstructure give rise to different deflection along the microstructure length, which is recorded as the resistance change in electrolyte solution. This sensor can detect distributed loads by monitoring the resistance change at each pair of electrodes. A sensor with an in-plane dimension of ~20mm10mm and five pairs of electrodes is fabricated using a CNC machine. 1M KCl solution is used as the electrolyte. Using a custom built electronic circuit on breadboard and a custom LabVIEW program, the static and dynamic performance of the sensor is characterized, demonstrating the feasibility of employing this sensor to detect distributed loads

Frequency-Agile Beam-Switchable Antenna

A novel antenna with both frequency and pattern reconfigurability is presented. The reconfigurability is achieved by integrating an active frequency selective surface (AFSS) with feed antenna. The smart FSS comprises a printed slot array loaded by varactors. A novel dc biasing arrangement is proposed to feed the slots vertically so that the unwanted effects caused by bias lines are minimized. A monopole antenna is designed to illuminate the AFSS. The resulting structure can operate in a frequency tuning range of 30%. By reconfiguring the different sections of active FSS cylinder into a transparent or reflector mode, the omnidirectional pattern of the source antenna can be converted to a directive beam. As an illustration, half of the AFSS cylinder is successively biased, enabling the beam switching to cover the entire horizontal plane over a range of frequencies. An antenna prototype was fabricated and measured. Experimental results demonstrate the capability of providing useful gain levels and good impedance matching from 1.7 to 2.3 GHz. The antenna offers a low-cost, low-power solution for wireless systems that require frequency and beam reconfigurable antennas. The proposed design consumes about 1000 times less dc power than the equivalent narrowband beam-switching antenna design using p-i-n diode-loaded AFSS

Tenofovir alafenamide versus entecavir for treating hepatitis B virus-related acute-on-chronic liver failure: real-world study

Background and aimsReal-world data regarding hepatitis B virus-related acute-on-chronic liver failure (HBV-ACLF) patients receiving tenofovir alafenamide (TAF) as an antiviral drug are limited. Hence, we evaluated the efficacy and kidney safety of TAF among this population.MethodsA total of 272 HBV-related ACLF patients hospitalized at Xiangya Hospital of Central South University were enrolled in this retrospective research. All patients received antiviral therapy with TAF (n = 100) or ETV (n = 172) and comprehensive medical treatments.ResultsThrough 1:1 propensity score matching, 100 patients were finally included in each group. At week 48, the survival rates without transplantation of the TAF group and ETV group were 76.00 and 58.00%, separately (P = 0.007). After 4 weeks of treatment, the TAF treatment group exhibited a significantly decline in HBV DNA viral load (P = 0.029). The mean estimated glomerular filtration rate was apparently improved in the TAF group compared with the ETV group (TAF 5.98 ± 14.46 vs. ETV 1.18 ± 18.07 ml/min/1.73 m2) (P < 0.05). There were 6 patients in TAF group and 21 patients in ETV group with chronic kidney disease (CKD) stage progression ≥ 1. By contrast, the ETV treatment group has a greater risk of renal function progression in CKD 1 stage patients (P < 0.05).ConclusionThis real-world clinical study showed that TAF is more effective than ETV in reducing viral load and improving survival rate in HBV-ACLF patients and the risk of renal function decline is lower.Clinical trial registrationhttps://ClinicalTrials.gov, identifier NCT05453448

Analysis of etiology and clinical features of spontaneous downbeat nystagmus: a retrospective study

ObjectiveTo investigate the topical diagnosis, possible etiology and mechanism of spontaneous downbeat nystagmus (sDBN) patients with dizziness/vertigo.MethodsThe clinical features of dizziness/vertigo patients accompanied with DBN were retrospectively reviewed in the Vertigo Center of our hospital from January 2018 to March 2021. The clinical features of dizziness/vertigo patients accompanied with DBN were reviewed. Comprehensive VNG, bithermal caloric testing, video-head-impulse test (vHIT), vestibular-evoked myogenic potentials (VEMP), head magnetic resonance imaging (MRI), three-dimensional fluid-attenuated incersion recovery magnetic resonance imaging (3D-FLAIR MRI) in the inner ear, serum immunology and other examinations were to determine the lesion site, and analyze its possible etiology and mechanism.ResultsA total of 54 patients were included. Among them, 70.4% (n = 38) of DBN patients were diagnosed with episodic vestibular syndrome (EVS), 22.2% (n = 12) with chronic vestibular syndrome (CVS), and 7.4% (n = 4) with acute vestibular syndrome (AVS). Among all the patients, 51.9% of DBN patients had clear etiology, with central lesions of 29.6% and peripheral diseases of 22.2%. The most common diseases in DBN patients were cerebellar lesions (13.0%, n = 7) and vestibular migraine (13.0%, n = 7), followed by benign positional paroxysmal vertigo (7.4%, n = 4) and drug-related dizziness/vertigo (5.6%, n = 3). The other 48.1% of the patients had unknown etiology. 53.8% (14/26) of patients with idiopathic DBN had decreased semicircular canal function, with 42.9% (6/14) decreased posterior semicircular canal function. The posterior semicircular canal gain in DBN patients decreased compared to the anterior semicircular canal in the same conjugate plane. Patients with peripheral DBN were more prone to horizontal/torsional nystagmus during positional testing.ConclusionIn our study, DBN patients have a relative decrease in posterior semicircular canal gain, which is possibly a particular result found in a subset of downbeat nystagmus patients. The changes in nystagmus during positional testing may be helpful in distinguishing between peripheral and central causes