Search

A MOF-based gel with simultaneous fluorescence and morphologic changes triggered by water was developed and applied in a visible rewriting pattern and a smart artificial actuator.

SARS-CoV-2 has high infectivity and some of its variants have higher transmissibility. To explore the high infectivity mechanism, the charge distributions of SARS-CoV, SARS-CoV-2, and variants of concern were calculated through a series of net charge calculation formulas. The results showed that the SARS-CoV-2 spike protein had more positive charges than that of SARS-CoV. Further results showed that the variants had similar but higher positive charges than preexisting SARS-CoV-2. In particular, the Delta variant had the greatest increase in positive charges in S1 resulting in the highest infectivity. In particular, the S1 positive charge increased greatly in the Delta variant. The S1 positive charge increased, and due to the large negative charge of angiotensin-converting enzyme-2 (ACE2), this resulted in a large increase in Coulomb’s force between S1 and ACE2. This finding agrees with the expectation that the positive charges in the spike protein result in more negative charges on SARS-CoV-2 antibodies than that of SARS-CoV. Thus, the infectivity of a novel SARS-CoV-2 variant may be evaluated preliminarily by calculating the charge distribution.

Bifunctional metalens for generation of pure longitudinal magnetization focal spot with reversible magnetization direction is greatly desired for the miniaturization and integration of all-optical magnetic storage. In this paper, we demonstrate a bifunctional triplex metalens that integrates the functions of an azimuthal polarizer, a helical phase plate, and a focusing lens for all-optical magnetic storage. Constructing the triplex metalens with tetratomic macropixels, the direction of the longitudinal magnetization at the focal spot can be flexibly switched by reversing the handedness of the incident light. Nearly perfect circularly polarized focal spot for left-handed or right-handed incident polarization are experimentally demonstrated, which is well consistent with the numerical simulations. The proposed bifunctional triplex metalens paves the way for the application of metalens in all-optical magnetic storage.

Grb2 associated binding protein 1 (Gab1) is an adaptor protein that is important for intracellular signal transduction which involved in several pathological process. However, the role of Gab1 in pressure overload-induced ventricular arrhythmias (VAs) remain poorly understood. In the current study, we aimed to test the role of Gab1 in VA susceptibility induced by pressure overload.We overexpressed Gab1 in the hearts using an adeno-associated virus 9 (AAV9) system through tail vein injection. Aortic banding (AB) surgery was performed in C57BL6/J mice to induce heart failure (HF). Four weeks following AB, histology, echocardiography, and biochemical analysis were conducted to investigate cardiac structural remodeling and electrophysiological studies were performed to check the electrical remodeling. Western blot analysis was used to explore the underlying mechanisms.The mRNA and protein expression were downregulated in AB hearts compared to sham hearts. Gab1 overexpression significantly reversed AB-induced cardiac structural remodeling including ameliorated AB-induced cardiac dysfunction, cardiac fibrosis, and inflammatory response. Moreover, Gab1 overexpression also markedly alleviated AB-induced electrical remodeling including ion channel alterations and VA susceptibility. Mechanistically, we found that TLR4/MyD88/NF-κB contributes to the cardio protective effect of Gab1 overexpression on AB-induced VAs.Our study manifested that Gab1 may serve as a promising anti-arrhythmic target via inhibiting TLR4/MyD88/NF-κB signaling pathway induced by AB.

A long-range, high-precision, and compact transverse displacement metrology method is of crucial importance in many research areas. Recent schemes using optical antennas are limited in efficiency and the range of measurement due to the small size of the antenna. Here, we demonstrated the first prototype polarization-encoded metasurface for ultrasensitive long-range transverse displacement metrology. The transverse displacement of the metasurface is encoded into the polarization direction of the outgoing light via the Pancharatnam-Berry phase, which can be read out directly according to the Malus law. We experimentally demonstrate nanometer displacement resolution with the uncertainty on the order of 100 picometers for a large measurement range of 200 micrometers with the total area of the metasurface being within 900 micrometers by 900 micrometers. The measurement range can be extended further using a larger metasurface. Our work opens new avenues of applying metasurfaces in the field of ultrasensitive optical transverse displacement metrology.

A novel polymer ammonium salt of polyethyleneimine phosphate phosphonic acid (APEMPPA) flame retardant for cotton fabrics was synthesized and characterized by nuclear magnetic resonance (NMR), in which some ammonium phosphoric acid groups were replaced by phosphate ester groups to decrease the phenomena that the ammonium ions in flame retardant would exchange with metal ions such as Ca

Due to the diffraction limit, subwavelength nanoslits (whose width is strictly smaller than λ/2) are hard to resolve by optical microscopy. Here, we overcome the diffraction limit by measuring the full Stokes parameters of the scattered field of the subwavelength nanoslits with varying width under the illumination of a linearly-polarized laser with a 45° polarization orientation angle. Because of the depolarization effect arising from the different phase delay and amplitude transmittance for TM polarization (perpendicular to the long axis of slit) and TE polarization (parallel to the long axis of slit), the state of polarization (SOP) of the scattered light strongly depends on the slit width for subwavelength nanoslits. After correcting for residual background light, the nanoslit width measured by the SOP of scattered light is consistent with the scanning electron microscopy (SEM) measurement. The simulation and experiment in this work demonstrate a new far-field optical technique to determine the width of subwavelength nanoslits by studying the SOP of the scattered light.

Two-dimensional transition metal dichalcogenides (TMDs) have a promising future in the nanophotonics field due to their unique optoelectronic properties such as large exciton binding energies and c...

A novel P–N based, flame retardant ammonium salt of pentaethylenehexamine octa (methylene-phosphoric acid) (APHOMPA) was synthesized in this study. The structure of the prepared material flame retardant contains eight reactive ammonium phosphorus groups and was characterized by 1H NMR, 13C NMR, 31P NMR, and (Fourier-transform infrared) FT-IR. The results showed that cotton fabrics finished with this flame retardant exhibited excellent flame retardancy and durability. The cotton fabrics finished with 30% APHOMPA solution had limiting oxygen index value 40.5%, and maintained 28.8% even after 50 laundering cycles. The FT-IR results showed that APHOMPA could be grafted on cellulose through P–O–C covalent bond. Vertical flammability, cone calorimetry, thermogravimetric (TG), and TG-IR results revealed the excellent flame retardancy of the finished cotton fabrics and suggested that the flame retardant mechanism of APHOMPA is a condensed phase process. Scanning electron microscopy results suggested the flame retardant entered the inner space of the cotton fabrics, and the X-ray diffraction results showed slight changes to the cotton crystal structure in the finishing process. The breaking strength, softness, and whiteness of finished cotton fabrics were sufficient, suggesting this retardant can be used to prepare treated cotton for multiple applications.

In the field of evolutionary genome analysis, biologists seek to identify important genes or chromosome regions by comparing phylogenetic trees and analyzing the mutation at which locus might affect phenotypic traits. Unfortunately, the tree comparison and accompanying analysis are often performed manually. In this paper, we characterize the workflow of evolutionary genome analysis and present a task analysis for the fundamental questions asked by biologists during the analysis procedure. We propose two algorithms to enable quantitative tree comparison. One is to measure the differences between corresponding leaf nodes on two trees, and the other is to compute the classification inconsistency of each leaf node by comparing tree structure with a given biological classification. Configuring with the obtained difference and inconsistency, we present a visual analysis system, visual comparison of phylogenetic trees for evolutionary genome analysis, which not only enables biologists to intuitively explore trees but also identify locus which affects their traits by comparing SNP variants of selected leaf nodes. We conclude with case studies from two biologists who used our system to augment their previous manual analysis workflow and demonstrate that our system can reveal more insight. published

Aiming at the problems of poor consistency and low efficiency in the manual plugging test of 5G RF(Radio Frequency) device, an intelligent plugging system based on robotic manipulation and machine vision is proposed. The mathematical model of the RF device is firstly established. The pixel size calibration and hand-in-eye calibration algorithms are then designed. A positioning algorithm is proposed, consisted of monocular vision and binocular vision. The monocular vision is employed to calculate the position information of the 5G RF device, and consequently, the binocular vision facilitates more accurate positioning, which reduces the positioning error between the actual model and the theoretical model and improves the positioning accuracy. In the binocular ranging, this algorithm improves the traditional Census transform by adopting a double cross window and utilizing the median value of the pixels in the window as the reference value, effectively reducing the impact of noise and meanwhile preserving detailed information. The experimental results show that the average absolute error of the coordinate axis X direction is 0.33mm, the average absolute error of the coordinate axis Y direction is 0.46mm, the average absolute error of the coordinate axis Z direction is 0.27mm, and the plugging success rate is 100%.

A long range, high precision and compact transverse displacement metrology method is of crucial importance in many research areas. We propose and experimentally demonstrate the first prototype polarization-encoded metasurface for ultrasensitive transverse displacement metrology. The transverse displacement of the metasurface is encoded into the polarization direction of the outgoing light via the Pancharatnam-Berry phase. By measuring the output light polarization direction, the metasurface’s position can be readout directly according to the Malus law. We experimentally demonstrate nanometer displacement resolution with the uncertainty on the order of 100 pm for a large measurement range of 200 µm with the total area of the metasurface being within 900 µm x 900 µm. The measurement range can be extended further using a larger metasurface. Our work largely broadens the existing application areas of metasurface and opens new avenue of applying metasurface in the field of ultrasensitive optical transverse displacement metrology.

Robotic exoskeleton takes an important role in walking assistance for subjects with lower extremity impairment. However, most of the existing robotic exoskeletons are bulky and complicated in the mechanical structure, placing a large load on the wearer. In this paper, a soft exosuit with twisted string actuators (TSAs) is designed for walking assistance. The analytic model of the TSA is derived to prove its characteristic of variable stiffness, benefited from which, flexible and compliant assistive torque can be generated to knee joints whilst walking. Furthermore, a human-robot coupling dynamic model is established, and an admittance control strategy is utilized to improve the trajectory tracking performance. Finally, simulations are conducted to verify the proposed robot system.

In this Letter, a chromatic confocal measurement system with high stability and accuracy is presented to monitor the evaporation of a sessile water droplet. The stability and accuracy of the system are tested by measuring the thickness of a cover glass. To compensate for the measurement error caused by the lensing effect of the sessile water droplet, a spherical cap model is proposed. Together with the parallel plate model, the contact angle of the water droplet can also be obtained. The evaporation process of sessile water droplet under different environment is monitored experimentally in this work, which demonstrates the potential application of chromatic confocal measurement system in the field of experimental fluid dynamics.

A novel flame retardant, triethylenetetramine phosphonate ammonium (TECHPA), containing phosphonate and ammonium phosphate groups, was synthesized and characterized by 1H, 13C, and 31P nuclear magnetic resonance (NMR) spectroscopy. The results showed that the limiting oxygen index (LOI) of cotton fabric treated with 40 g/L TECHPA reached 36.8%, which remained at 31.1% after 50 laundering cycles. The infrared spectra and durability test results suggested that the flame retardant was grafted onto the cotton fibers through P–O–C covalent bonds. TG and cone calorimetry results indicated that the cotton fabrics treated with TECHPA flame retardant showed excellent flame retardancy. The SEM and XRD results suggested that the cotton fibers retained their original structures. For treated cotton fabrics, their stiffness increased slightly, their tensile strength decreased a little, and their crease recovery was greatly improved. No formaldehyde was detected in the cotton fabric after treatment. Overall, simultaneously introducing phosphonate and ammonium phosphate groups provided an effective method to increase the durability of treated cotton fabrics.

Enhancement of fluorescent radiation is of great importance for applications including biological imaging, high-sensitivity detectors, and integrated light sources. Strong electromagnetic fields can be created around metallic nanoparticles or in gap of nanostructures, where the local state density of radiating mode is then dramatically enhanced. While enhanced fluorescent emission has been demonstrated in many metallic nanoparticles and nanoparticle pairs, simultaneous mediation of absorption and emission processes of fluorescent emitters remains challenging in metallic nanostructures. Here, we investigate fluorescent emission mediated by metal-dielectric-metal fishnet metasurface, in which localized surface plasmon (LSP) and magnetic plasmon polaritons (MPPs) modes are coupled with absorption and emission processes, respectively. For absorption process, coupling of the LSP mode enables spatially-selective excitation of the fluorescent emitters by rotating the polarization of the pump laser beam. In addition, the polarization-dependent MPP mode enables manipulation of both polarization and wavelength of the fluorescent emission by introducing a rectangular fishnet structure. All the experimental observations are further corroborated by finite-difference time-domain simulations. The structure reported here has great potential for application to color light-emitting devices and nanoscale integrated light sources.

The bunching and deflection characteristics of low-power laser beam were investigated under electromagnetic field. On the basis of the Faraday effect, the cylindrical electromagnetic cavity was designed and implemented in the experiments. Several types of the magneto-optical elements were placed in the electromagnetic cavity individually. In the test of the deflection characteristics of low-power laser, the rotating angle, the polarization plane of linearly polarized light which passed through electromagnetic cavity, was measured by polarization extinction. We focus on the relation between the coil current and the rotating angle. The experimental data show that when the coil current varies in the range of 0–5 A, the rotating angles changed from 0° to 24.1°. Then, a fitting formula about the coil current and the rotating angle was obtained from the experimental data using the least square algorithm. The analysis shows that the rotating angle is proportional to the excitation current and the correlation coefficient is more than 0.9995. In order to study the beam bunching characteristics of low-power laser, the area of the laser facula was measured after the low-power laser passed through the electromagnetic cavity. The experiment data show that the laser facula area changes in a small range and the experimental data meet 3σ criteria.