PMMA/PS-b-PMMA超临界二氧化碳微孔发泡——胶束尺寸和密度对发泡行为的影响

以均聚物聚甲基丙烯酸甲酯(PMMA)和二嵌段共聚物聚苯乙烯-聚甲基丙烯酸甲酯(PS-b-PMMA)共混物为考察对象,利用超临界二氧化碳(scCO_2)发泡技术制备纳米发泡材料。通过改变PMMA的相对分子质量以及PS-b-PMMA的含量来调控共混物中胶束的尺寸和密度,系统研究其对材料发泡行为的影响。实验结果表明,对于纯PMMA发泡体系来说,随着PMMA相对分子质量的增大,发泡材料的泡孔孔径逐渐减小,但可发泡性变差;当PS-b-PMMA含量为5%时,共混物的可发泡性得到改善,泡孔孔径更加均匀,但泡孔孔径增大;将PS-b-PMMA含量提高到10%时,得到孔径更小、更均匀的纳米发泡材料。

Characteristics and Risk Factors of Infections among Patients with Autoimmune Bullous Diseases: A Retrospective Single-Center Study in China

Background: Since infections can lead to adverse outcomes in autoimmune bullous diseases (AIBD), this study aimed to analyze infection characteristics in AIBD, predict infection risk factors and provide probable suggestions to infection prevention, which will spot a light on early discovery and prevention of infections in AIBD patients. Methods: This is a retrospective study of the medical records of inpatients diagnosed with AIBD at the Department of Infectious Diseases and Dermatology, Huashan Hospital from January 2017 to December 2021. We collected patients’ clinical manifestations and laboratory examination results. Risk factors for infections were evaluated using multivariate logistic regression. Results: A total of 263 AIBD patients were included in the study. The overall incidence of infection was 42.2% (111/263). Pemphigus had a higher infection rate (74/142, 52.1%) than bullous pemphigoid (37/121, 30.6%). Among the patients with infections, 49.5% (55/111) had bacterial infections, 13.5% (15/111) had fungal infections, 2.7% (3/111) had virus infections, and 34.2% (38/111) had mixed infections. Staphylococcus aureus and Candida were the most common pathogens in localized infections, while Cryptococcus and Candida were predominant in systemic infections. In the multivariate logistic model, pemphigus (odds ratio [OR] = 2.56, 95% confidence interval [CI] 1.41-4.63), hypoalbuminemia (OR = 3.78, 95% CI 1.68-8.50), and systemic glucocorticoid treatment (OR = 4.67, 95% CI 2.51-8.68) were independent risk factors for infection in AIBD patients. Bullous pemphigoid (OR = 3.99, 95% CI 1.03-15.45), high-dose (average > 24 mg/day) compared to low-dose (average ≤ 6 mg/day) and medium-dose (average 6-24 mg/day) systemic glucocorticoid treatment (OR = 19.31, 95% CI 3.32-112.28, and OR = 5.71, 95% CI 1.37-23.79) were associated with increased risk factors of systemic infection in AIBD patients with systemic glucocorticoid treatment. A methylprednisolone dose averaging 14 mg/day over the past three months had a 75.0% positive predictive value for infections in AIBD patients. Conclusions: The incidence of infection in AIBD patients is high, with a broad spectrum of pathogens and infection locations. AIBD patients undergoing systemic glucocorticoid treatment, especially those receiving high doses in the previous three months, should be cautious about infection.

Dispersion-less Kerr solitons in spectrally confined optical cavities

Solitons are self-reinforcing localized wave packets that manifest in the major areas of nonlinear science,from optics to biology and Bose-Einstein condensates.Recently,optically driven dissipative solitons have attracted great attention for the implementation of the chip-scale frequency combs that are decisive for communications,spectroscopy,neural computing,and quantum information processing.In the current understanding,the generation of temporal solitons involves the chromatic dispersion as a key enabling physical effect,acting either globally or locally on the cavity dynamics in a decisive way.Here,we report on a novel class of solitons,both theoretically and experimentally,which builds up in spectrally confined optical cavities when dispersion is practically absent,both globally and locally.Precisely,the interplay between the Kerr nonlinearity and spectral filtering results in an infiinite hierarchy of eigenfunctions which,combined with optical gain,allow for the generation of stable dispersion-less dissipative solitons in a previously unexplored regime.When the filter order tends to infinity,we find an unexpected link between dissipative and conservative solitons,in the form of Nyquist-pulse-like solitons endowed with an ultra-flat spectrum.In contrast to the conventional dispersion-enabled nonlinear Schr?dinger solitons,these dispersion-less Nyquist solitons build on a fully confined spectrum and their energy scaling is not constrained by the pulse duration.Dispersion-less soliton molecules and their deterministic transitioning to single solitons are also evidenced.These findings broaden the fundamental scope of the dissipative soliton paradigm and open new avenues for generating soliton pulses and frequency combs endowed with unprecedented temporal and spectral features.

Design of PANDA ring-core fiber with 10 polarization-maintaining modes

We present a polarization-maintaining PANDA ring-core fiber(PM-PRCF) characterized by the combination of a ring-core structure with two stress-applying rods. This special fiber design separates the adjacent modes and avoids the cutoff of the higher-order modes, which is a common problem in elliptical core polarization-maintaining few-mode fibers. Using a high-contrast index ring and stress-induced birefringence, the PM-PRCF features support for 10 vector modes, with effective refractive index separations from their adjacent modes >10^(-4).Broadband performance is investigated subsequently over a wide wavelength range from 1500 to 1630 nm.The proposed fiber is targeted at applications in space-division multiplexing while eliminating the complex multiple-input multiple-output signal processing.

Broadband photonic ADC for microwave photonics-based radar receiver

A broadband photonic analog-to-digital converter（ADC） for X-band radar applications is proposed and experimentally demonstrated. An X-band signal with arbitrary waveform and a bandwidth up to 2 GHz can be synchronously sampled and processed due to the optical sampling structure. In the experiment, the chirp signal centered at 9 GHz with a bandwidth of 1.6 GHz is sampled and down-converted with a signal-to-noise ratio of 7.20 d B and an improved noise figure. Adopting the photonic ADC in the radar receiver and the above signal as the transmitted radar signal, an X-band inverse synthetic aperture radar system is set up, and the range and cross-range resolutions of 9.4 and 8.3 cm are obtained, respectively.

Soliton regulation in microcavities induced by fundamental–second-harmonic mode coupling

Microcomb generation with simultaneous χ2 and χ3 nonlinearities brings new possibilities for ultrabroadband and potentially self-referenced integrated comb sources. However, the evolution of the intracavity field involving multiple nonlinear processes shows complex dynamics that are still poorly understood. Here, we report on strong soliton regulation induced by fundamental–second-harmonic(FD-SH) mode coupling. The formation of solitons from chaos is extensively investigated based on coupled Lugiato–Lefever equations. The soliton generation shows more deterministic behaviors in the presence of FD-SH mode interaction, which is in sharp contrast with the usual cases where the soliton number and relative locations are stochastic. Deterministic single soliton transition, soliton binding, and prohibition are observed, depending on the phase-matching condition and coupling coefficient between the fundamental and second-harmonic waves. Our finding provides important new insights into the soliton dynamics in microcavities with simultaneous χ~2and χ~3nonlinearities and can be immediate guidance for broadband soliton comb generation with such platforms.

Visual Information Based Social Force Model for Crowd Evacuation

With the increase in large-scale incidents in real life, crowd evacuation plays a pivotal role in ensuring the safety of human crowds during emergency situations. The behavior patterns of crowds are well rendered by existing crowd dynamics models. However, most related studies ignore the information perception of pedestrians.To overcome this issue, we develop a visual information based social force model to simulate the interpretable evacuation process from the perspective of visual perception. Numerical experiments indicate that the evacuation efficiency and decision-making ability promote rapidly within a small range with the increase in unbalanced prior knowledge. The propagation of acceleration behavior caused by emergencies is asymmetric due to the anisotropy of visual information. Therefore, this model effectively characterizes the effect of visual information on crowd evacuation and provides new insights into the information perception of individuals in complex scenarios.

Concurrent photonic measurement of angle-of-arrival and chirp rate of microwave LFM signal

A photonic approach to concurrently measure the angle-of-arrival(AOA) and the chirp rate of a linear frequency modulated(LFM) signal is proposed and experimentally demonstrated. The measurement is achieved by estimating the differential frequency of a two-tone signal output by a dual-parallel Mach–Zehnder modulator and an additional asymmetry Mach–Zehnder interferometer. Experiments show that the AOA and the chirp rate are measured simultaneously, with an AOA measurement error of ?0.1° at an signal-to-noise ratio(SNR) of 9.6 d B.When the SNR is-10.4 d B, the AOA error is ?1.3°, and the chirp rate, measured as 210.2 ? 1.5 Hz∕ps, has a standard deviation of 0.7%. The measured chirp rate agrees well with the real LFM signal.

Researches in microwave photonics based packages for millimeter wave system with wide bandwidth and large dynamic range

This paper presents an introduction to the researches in microwave photonics based packages and its application, a 973 project （No. 2012CB315600）, which focuses on addressing new requirements for millimeter wave （MMW） system to work with higher frequency, wider bandwidth, larger dynamic range and longer distance of signal distribution. Its key scientific problems, main research contents and objectives are briefed, and some latest achievements by the project team, including generation of linear frequency modulation wave （LFMW）, tunable optoelectronic oscillator （OEO） with lower phase noise, reconfigurable filter with higher Q value, time delay line with wider frequency range, down conversion with gain, and local oscillator （LO） transmission with stable phase, are introduced briefly.

Elements’important ranking of China drug safety management system:applying the non-structural fuzzy group decision method

Drug safety management is an important issue in China drug management system and attracts great attentions from the whole society.In order to reduce drug incident,this study discusses some important elements associated with China drug safety management system and analyzes the data collected by questionnaires.Besides,a methodology for rating the important elements is described and applied.The non-structural fuzzy group decision method not only considers the insufficient precise information but also combines the opinions of different kinds of respondents in China’s four municipalities.The results indicate that the sample systems are the most important in these important elements,and the order of importance is sampling systems,licensing systems,traceability systems,transaction models,pharmacovigilance and emergence management.This study not only points out the important ranking of the pivotal elements in China drug safety management but also gives some specific proposals about how to enhance drug safety management in China.

Research on pedestrian escape route without visibility based on Markov chain model

It is a pioneering work to use a Markov chain model to study the pedestrian escape route without visibility.In this paper,based on the Markov chain probability transition matrix,the algorithms with random numbers and the spatial-grid,an escape route in a limited invisible space is obtained.Six pace states(standing,crawling,walking,leaping,jogging,and running)are applied to describe the characteristics of pedestrian behaviors.Besides,eight main direction changes are used to describe the transition characteristic of a pedestrian.At the same time,this paper analyzes the escape route from two views,i.e.,pedestrian pace states and directions.The research results show that the Markov chain model is more realistic as a means of studying pedestrian escape routes.

Photonics-enabled distributed MIMO radar for high-resolution 3D imaging

Three-dimensional(3D)imaging radar is an advanced sensor applied in space surveillance and target recognition for supplying 3D geometric features and supporting visualization.However,high 3D resolution requires both broadband operation and a large 2D aperture,which are difficult and complex for conventional radars.This paper presents a photonics-enabled distributed multiple-input and multiple-output(MIMO)radar with a centralized architecture.By use of photonic multi-dimensional multiplexing,multi-channel signal generation and reception are implemented on a shared reference signal in a central office,enabling a highly coherent network with a simple structure.Additionally,a sparse array and a synthetic aperture are combined to efficiently reduce the required transceivers,further weakening the dilemma between system complexity and angular resolution.A 4×4 MIMO radar is established and evaluated in field tests.A high-resolution 3D image of a non-cooperative aircraft is obtained,in which rich details are displayed.From a comparison with electronics-based radar,significant resolution improvement is observed.The results verify the superior imaging capability and practicability of the proposed radar and its great potential to outperform conventional technologies in target classification and recognition applications.