Preparation and Characteraction of New Magnetic Co–Al HTLc/Fe3O4Solid Base

Novel magnetic hydrotalcite-like compounds (HTLcs) were synthesized through introducing magnetic substrates (Fe3O4) into the Co–Al HTLcs materials by hydrothermal method. The magnetic Co–Al HTLcs with different Fe3O4contents were characterized in detail by XRD, FT-IR, SEM, TEM, DSC, and VSM techniques. It has been found that the magnetic substrates were incorporated with HTLcs successfully, although the addition of Fe3O4might hinder the growth rate of the crystal nucleus. The morphology of the samples showed the relatively uniform hexagonal platelet-like sheets. The grain boundaries were well defined with narrow size distribution. Moreover, the Co–Al HTLcs doped with magnetic substrates presented the paramagnetic property

Jitter analysis of a superconducting nanowire single photon detector

Jitter is one of the key parameters for a superconducting nanowire single photon detector (SNSPD). Using an optimized time-correlated single photon counting system for jitter measurement, we extensively studied the dependence of system jitter on the bias current and working temperature. The signal-to-noise ratio of the single-photon-response pulse was proven to be an important factor in system jitter. The final system jitter was reduced to 18 ps by using a high-critical-current SNSPD, which showed an intrinsic SNSPD jitter of 15 ps. A laser ranging experiment using a 15-ps SNSPD achieved a record depth resolution of 3 mm at a wavelength of 1550 nm.Comment: 7 pages, 6 figure

Large-sensitive-area superconducting nanowire single-photon detector at 850 nm with high detection efficiency

Satellite-ground quantum communication requires single-photon detectors of 850-nm wavelength with both high detection efficiency and large sensitive area. We developed superconducting nanowire single-photon detectors (SNSPDs) on one-dimensional photonic crystals, which acted as optical cavities to enhance the optical absorption, with a sensitive-area diameter of 50 um. The fabricated multimode fiber coupled NbN SNSPDs exhibited a maximum system detection efficiency (DE) of up to 82% and a DE of 78% at a dark count rate of 100 Hz at 850-nm wavelength as well as a system jitter of 105 ps.Comment: 8 pages, 4 figure

Anti-Apoptosis Effect of Astragaloside Iv on Alzheimer's Disease Rat Model via Enhancing the Expression of Bcl-2 And Bcl-Xl

The aim is to explore the protective effect of Astragaloside IV on Alzheimer’s disease (AD) in rats induced  by amyloid-ß peptide (Aß1-42) and its potential therapeutic mechanism. Methods: 50 Male Sprague Dawley  rats were divided into five groups (10 rats for each): control group, model group, treatment groups 1~3.  10μg Aß1-42 was injected bilaterally into the dorsal dentate gyrus of the hippocampus of rats in the model  and treatment groups to prepare the AD models. 24h after modeling, Astragaloside IV administration, with  different drug dosages of 20mg/(kg•day), 40mg/(kg•day) and 60mg/(kg•day), was performed by gastric  perfusion for rats in the treatment group 1~3. Later on, the cognitive ability of rats was examined by a series  of behavioral tests, and the expression of Bcl-2 and Bcl-xl in the hippocampus of rats was detected by the  fluorescein based Quantitative RT-PCR. Results: The spontaneous alternation test in a Y maze and Morris  water maze task have demonstrated that the repeated daily administration of Astragaloside IV at the doses  of 20mg/kg bw/day) (p<0.05), 40mg/kg bw/day) (p<0.01), and 60mg/kg bw/day) (p<0.01) significantly  ameliorated the impairment of performance caused by Aß1–42. Furthermore, Astragaloside IV also enhanced  the expression of Bcl-2 and Bcl-xl in hippocampal neurons of rats in a dosage-dependent manner. Conclusion:  These findings suggest that Astragaloside IV could alleviate cognitive impairment and enhance the  expression of Bcl-2 and Bcl-xl in hippocampus of rat models with AD.

An Accurate Virtual Signal Injection Control of MTPA for IPMSM with Fast Dynamic Response

A maximum torque per ampere (MTPA) control based on virtual signal injection for interior permanent magnet synchronous motor (IPMSM) with fast dynamic response is proposed in this paper. A small square wave signal is mathematically injected into current angle for accurately tracking MTPA points. The extracted derivative of elctromagnetic torque is utilized to compensate the initially set current angle to the real MTPA operation current angle. Due to the absence of bandpass and lowpass filters which are essential in the sinusoidal injected signal scheme, this method shows good dynamic response. By incorporating a modified equation for the torque after signal injection, the steady-state accuracy is also enhanced. The d- and q-axes current references are obtained through the current vector magnitude and optimal current angle instead of using the torque equation with nominal motor parameters, which guarantees the accuracy of the output torque. The proposed scheme is parameter independent and no real signal is injected to the current or voltage command. Thus, the problems of high-frequency signal injection method are avoided. A prototype is set up and experiments are carried out to verify effectiveness and robustness of the proposed control scheme

Arbitrary Engineering of Spatial Caustics with 3D-printed Metasurfaces

Caustics occur in diverse physical systems, spanning the nano-scale in electron microscopy to astronomical-scale in gravitational lensing. As envelopes of rays, optical caustics result in sharp edges or extended networks. Caustics in structured light, characterized by complex-amplitude distributions, have innovated numerous applications including particle manipulation, high-resolution imaging techniques, and optical communication. However, these applications have encountered limitations due to a major challenge in engineering caustic fields with customizable propagation trajectories and in-plane intensity profiles. Here, we introduce the compensation phase via 3D-printed metasurfaces to shape caustic fields with curved trajectories in free space. The in-plane caustic patterns can be preserved or morphed from one structure to another during propagation. Large-scale fabrication of these metasurfaces is enabled by the fast-prototyping and cost-effective two-photon polymerization lithography. Our optical elements with the ultra-thin profile and sub-millimeter extension offer a compact solution to generating caustic structured light for beam shaping, high-resolution microscopy, and light-matter-interaction studies