“翻转课堂”教学模式在大学物理实验教学中的探索与实践

为了激发学生的学习兴趣,增强学生自主思考、主动学习的意识和创新研究能力,基于"翻转课堂"模式,对我校目前开设的以验证性为主的工科大学物理实验项目进行教学设计及实践应用。从教学目标的制定、教学活动的实施等方面对大学物理实验教学进行了初步的改革探讨和实践,取得了较好的教学效果。     

Physicochemical properties of nanoparticles affect translocation across pulmonary surfactant monolayer

Interaction between nanoparticles (NPs) and pulmonary surfactant monolayer is one of the most important parts in NP-based pulmonary drug delivery system, which can affect the result of the inhaled nano-drugs and their potential efficacy. Here, we show how surface charge of NPs affects translocation across pulmonary surfactant monolayer with coarse-grained molecular dynamics simulations. The results reveal that the surface charge position of NPs can determine the fate of the inhaled NPs about whether they can have the ability of translocation across the pulmonary surfactant monolayer, which is that NPs with face surface charge can penetrate the pulmonary surfactant monolayer and NPs with edge surface charge cannot. Besides, dynamic process, phase state and the potential of mean force profiles further confirm this result. Moreover, compared to anionic NPs, there is a greater chance for cationic NPs to be adsorbed on the surface of the pulmonary surfactant monolayer, which can further decrease the thickness of the pulmonary surfactant monolayer and reduce the distance between charged NPs and the pulmonary surfactant monolayer. Our researches provide a novel simulation model of NPs on translocation across pulmonary surfactant monolayer and the study of NP-based pulmonary drug delivery system should consider the surface charge of NPs.     

火焰辐射及偶丝导热对热电偶测温影响的数值分析

本文利用层流同向扩散乙烯火焰的数值模拟结果,根据所得的火焰温度场、气体速度场、火焰辐射场,分析火焰辐射、热电偶偶丝导热对热电偶测温的影响.结果表明在火焰的低温区火焰辐射要大于节点向外辐射,节点得到的能量要高于节点损失的能量,因此在火焰的低温区节点温度要高于当地的气体温度;同时直径为100μm的热电偶存在较大的导热,对节点温度测量有较大的影响.     

Causal impedance matching for broadband hybrid noise absorption

The complementary strengths and weaknesses of passive and active noise control (ANC) methods have motivated many researchers to develop hybrid noise absorbers that integrate both control strategies. The impedance matching technique (IMT) is the most effective for such a purpose. An unsolved problem with available IMT schemes is the a priori reference signal that limits IMT applications. This study proposes the use of the forward wave, available by the two-microphone method, as the reference signal. Due to inevitable errors in wave separation and inlet reflection of the control signal, the absorber becomes a feedback system. A simple and stable ANC is developed for impedance matching without the a priori reference signal. The proposed absorber has an absorption coefficient of 0.9 or above in a frequency range of 60-850 Hz. It is stable in the presence of sensor mismatch and robust with respect to significant variation of inlet boundary conditions.     

基于光谱法舌诊的脂肪肝快速诊断

提出了一种基于光谱技术的脂肪肝无创、快速诊断新方法。由于舌体能较客观的反映人体生理、病理变化,因此采集志愿者舌体舌尖部位的反射光谱,然后对数据进行分析,计算反射光谱的归一化反射率。建立3层BP网络模型,从采集来的115例样本中抽取32例健康人和44例脂肪肝患者的光谱归一化反射率作为神经网络的输入,再对未知的14例健康人样本和25例脂肪肝患者样本进行分类预测,分类正确率达到89.7%,实验结果表明了光谱法运用于脂肪肝快速无创诊断的可行性。同时,实验结果说明光谱法能更客观全面地反映人舌所携带的组织细胞、微循环等方面的信息,有可能为临床提供一种快速、简便的诊断手段,也为今后的中医证侯的度量提供借鉴。     

Analysis theory of random energy of train derailment in wind

Based on the analysis theory of random energy of train derailment, an analysis theory of random energy of train derailment in wind is suggested. Two methods are proposed -the time domain method and the frequency domain method of analysis theory of random energy of train derailment in wind. The curves of σ pw -v under various wind speeds are obtained through the computation. The original curve of σ p -v is expanded, which turns the analysis theory of random energy of train derailment into the all-weather theory. Train derailment condition has been established under wind action. The first and second criterions of train derailment have been proposed in light of wind action. The analysis of train derailment cases at home or abroad is made, in- cluding the first analysis of Xinjiang train derailment case encountered 13-level of gale, which explained the inevitability of train derailment. The analysis theory of random energy of train derailment in wind shows its validity and accuracy. The input energy σ pw of the transverse vibration of train-track(bridge)-wind system is linked to train speed. With the establishment of the analysis theory of random energy of train derailment in wind, It is likely to initiate an all-weather speed limit map for a train or any high-speed train.     

White matter abnormalities in children and adolescents with temporal lobe epilepsy

Background and Purpose

The widespread propagation of synchronized neuronal firing in seizure disorders may affect cortical and subcortical brain regions. Diffusion tensor imaging (DTI) can noninvasively quantify white matter integrity. The purpose of this study was to investigate the abnormal changes of white matter in children and adolescents with focal temporal lobe epilepsy (TLE) using DTI.

Materials and Methods

Eight patients with clinically diagnosed TLE and eight age- and sex-matched healthy controls were studied. DTI images were obtained with a 3-T magnetic resonance imaging scanner. The epileptic foci were localized with magnetoencephalography. Fractional anisotropy (FA), mean diffusivity (MD), parallel (λ_||) and perpendicular (λ_⊥) diffusivities in the genu of the corpus callosum, splenium of the corpus callosum (SCC), external capsule (EC), anterior limbs of the internal capsule (AIC), and the posterior limbs of the internal capsule (PIC) were calculated. The DTI parameters between patients and controls were statistically compared. Correlations of these DTI parameters of each selected structure with age of seizure onset and duration of epilepsy were analysed.

Results

In comparison to controls, both patients' seizure ipsilateral and contralateral had significantly lower FA in the AIC; PIC and SCC and higher MD, λ_|| and λ_⊥ in the EC, AIC, PIC and SCC. The MD, λ_|| and λ_⊥ were significantly correlated with age of seizure onset in the EC and PIC. λ_|| was significantly correlated with the duration of epilepsy in the EC and PIC.

Conclusion

The results of the present study indicate that children and adolescents with TLE had significant abnormalities in the white matter in the hemisphere with seizure foci. Furthermore, these abnormalities may extend to the other brain hemisphere. The age of seizure onset and duration of epilepsy may be important factors in determining the extent of influence of children and adolescents TLE on white matter.     

Non-Markovian relaxation of a three-level system: quantum trajectory approach

The non-Markovian dynamics of a three-level quantum system coupled to a bosonic environment is a difficult problem due to the lack of an exact dynamic equation such as a master equation. We present for the first time an exact quantum trajectory approach to a dissipative three-level model. We have established a convolutionless stochastic Schr?dinger equation called the time-local quantum state diffusion (QSD) equation without any approximations, in particular, without Markov approximation. Our exact time-local QSD equation opens a new avenue for exploring quantum dynamics for a higher dimensional quantum system coupled to a non-Markovian environment.     

Microemulsion-mediated in-situ synthesis and magnetic characterization of polyaniline/Zn<Subscript>0.5</Subscript>Cu<Subscript>0.5</Subscript>Fe<Subscript>2</Subscript>O<Subscript>4</Subscript> nanocomposite

Polyaniline/Zn_0.5Cu_0.5Fe₂O₄ nanocomposite was synthesized by a simple, general and inexpensive in-situ polymerization method in w/o microemulsion. The effects of polyaniline coating on the magnetic properties of Zn_0.5Cu_0.5Fe₂O₄ nanoparticles were investigated. The structural, morphological and magnetic properties of as-prepared samples were characterized by X-ray diffraction (XRD), Fourier transform infrared (FTIR) spectra, scanning electron microscopy (SEM) and magnetic measurements. The morphology analysis confirmed that polyaniline was deposited on the porous surface of magnetic Zn_0.5Cu_0.5Fe₂O₄. It was shown that the saturation magnetization and coercivity of Zn_0.5Cu_0.5Fe₂O₄ decreased after polyaniline coating, which can be interpreted by the interparticle dipole–dipole interactions that contributed to magnetic anisotropy and changed the magnetic properties of the nanoparticles. PACS  74.25.Ha; 81.05.-t; 81.05.Lg