SOFFLFM:Super-resolution optical fluctuation Fourierlight-field microscopy

Fourier light-field microscopy(FLFM)uses a microlens aray(MLA)to segment the Fourierplane of the microscopic objective lens to generate multiple two-dimensional perspective views,thereby reconstructing the threedimensional(3D)structure of the sample using 3D deconvo-lution calculation without scanning.However,the resolution of FLFM is stil limited by dif-fraction,and furthermore,it is dependent on the aperture division.In order to improve itsresolution,a super-resolution opticai fuctuation Fourier light-field microscopy(SOFFLFM)wasproposed here,in which the super-resolution optical fluctuation imaging(SOFI)with the abilityof super-resolution was introduced into FLFM.SOFFLFM uses higher-order cumulants statis-tical analysis on an image sequence collected by FLFM,and then carries out 3D deconvolutioncalculation to reconstruct the 3D structure of the sample.The theoretical basis of SOFFLFM onimproving resolution was explained and then verified with the simulations.Simulation resultsdemonstrated that SOFFLFM improved the lateral and axial resolution by more than V2 and 2times in the second-and fourth-order accumulations,compared with that of FLFM.

Taxonomic review of the ant genus Echinopla(Hymenoptera:Formicidae)in China

Three species of the ant genus Echinopla are recognized in China:E.cherapunjiensis,E.striata and E.lateropilosa.The last one is recorded for the first time in China.Morphological descriptions,measurements,distribution and high-resolution color pictures of the worker caste of each species are provided.A key to the known Chinese species based on worker caste is presented.

LH-Nts Neurons Regulate VTA Calcium Dynamics Via Releasing GABA and Nts

The peripheral and central nervous systems have numerous examples of two or more neuroactive products co-existing in the same neuron[1],which can simultaneously be released as both fast-acting neurotransmitters and slow-acting regulatory neuropeptides[2].For example,neurons in the lateral hypothalamus(LH)release both irritant neurotensin(Nts)and inhibitory-aminobutyric acid(GABA),two counterproductive substances[3].LH-Nts neurons project to the ventral tegmental area(VTA)and form synaptic connections with dopamine(DA)neurons to regulate reward[4-6].More critically,VTA-DA neurons express the Nts receptor Ntsrl and play a crucial role in cognition,anesthesia,reward,and disgust[4,7,8].Nevertheless,a mechanistic understanding of how stimulation and inhibition work together to control the output of neural circuits remains unclear.It is very difficult to selectively isolate these signaling pathways in cell and circuit-specific manners.

Three-dimensional tracking of multiple particles in large depth of field using dual-objective bifocal plane imaging

Tracking moving particles in cells by single particle tracking is an important optical approach widely used in biological research. In order to track multiple particles within a whole cell simultaneously, a parallel tracking approach with large depth of field was put forward. It was based on distorted grating and dual-objective bifocal imaging, making use of the distorted grating to expand the depth of field, dual-objective to gather as many photons as possible, and bifocal plane imaging to realize three-dimensional localization. Simulation of parallel tracking of two particles moving along the z axis demonstrated that even when the two are axially separated by10 μm, they can both be localized simultaneously with transversal precision better than 5 nm and axial precision better than 20 nm.

Graphene-loaded metal wire grating for deep and broadband THz modulation in total internal reflection geometry

We employed a metallic wire grating loaded with graphene and operating in total internal reflection (TIR) geometry to realize deep and broadband THz modulation. The non-resonant field enhancement effect of the evanescent wave in TIR geometry and in the subwavelength wire grating was combined to demonstrate a ～77% modulation depth (MD) in the frequency range of 0.2–1.4 THz. This MD, achieved electrically with a SiO_2∕Si gated graphene device, was 4.5 times higher than that of the device without a metal grating in transmission geometry. By optimizing the parameters of the metallic wire grating, the required sheet conductivity of graphene for deep modulation was lowered to 0.87 mS. This work has potential applications in THz communication and real-time THz imaging.

氮掺杂单层石墨烯上无中间层沉积高质量氮化镓

在石墨烯/氧化铝衬底上通过金属有机化学气相沉积法(MOCVD)范德华外延生长的氮化镓(GaN)可以减少由于氮化镓与衬底严重晶格失配产生的缺陷.然而,石墨烯表面缺少悬挂键导致氮化镓成核位点很少,因此,常利用薄层AlN或ZnO纳米壁作为中间层沉积于石墨烯上.在无缓冲层的氮掺杂石墨烯上,我们利用MOCVD法成功地直接获得低应力(0.023 GPa)和低螺位错密度(9.76×10^(7)cm^(-2))的高质量氮化镓晶体.第一性原理计算结果表明,与本征石墨烯相比,氮掺杂石墨烯表面对镓原子的吸附能力明显提高,这与氮化镓低温生长成核实验观察到的结果一致.在大多数情况下,氮化镓在经过氮原子预处理的单层石墨烯上倾向于形成C-Ga-N和N-Ga-N的成核位点.本研究证明了通过界面调控可在氮掺杂石墨烯上生长高质量的氮化镓薄膜,是一种有效的原子调控方法.本方法为新型半导体器件的工业发展提供了新思路.