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Life sciences are devoted to the research of all aspects of living organisms. As the basic unit of a living organism, biological cells are diverse and different. These differences are a direct reflection of their corresponding biological characteristics, so "seeing the cell more clearly" has been the goal of scientists at home and abroad. Based on the principle of coherent imaging, digital holographic quantitative phase microscopy imaging technology adopts digital recording and numerical reconstruction to realize phase retrieval and three-dimensional reconstruction. It has become one of the most promising methods in cellular research with better imaging efficiency, reconstruction accuracy, and stability. However, in the band-pass filtering process, tilt aberrations are often introduced due to manual frame selection of the +1 order spectrum, which is detrimental to the imaging quality of the system. To address this problem, this paper proposes a method to automatically determine the spectral center based on the surface fitting of a two-dimensional Hann window function, which improves the phase retrieval accuracy and imaging quality without reducing the computational speed. A more accurate spectral center can be obtained by conducting the sub-pixel spectral center of surface fitting. In addition, the accuracy is sub-pixel level and requires sub-pixel displacement correction of the tilted phase plane to obtain better quantitative phase retrieval results and imaging quality.

Achieving the directional transport of micron-sized liquid droplets in aqueous media and using such transport to rapidly and highly efficiently collect tiny oil droplets continuously on a surface are still challenging endeavors. Herein, we present a new strategy to achieve the highly efficient directional collection of micron-sized underwater oil droplets on an anisotropic porous polystyrene (PS) film-coated cone surface under an applied electric field. The results revealed that underwater oil droplets can be continuously and directionally transported from the tip of the cone to its base along the anisotropic porous cone surface under the cooperative driving force of a Laplace pressure gradient, resulting from the geometric cone gradient and surface porous microstructure gradient, and buoyant force with the assistance of electrocapillary pressure. Based on the above theoretical and experimental results, an integrated device with an array of porous PS-coated cones was fabricated, and achieved the highly efficient collection of oil from an oil–water mixture. We expect this work to open new avenues to improve the treatment of oily water, and also to be useful for constructing artificial directional transport systems for catalytic reactions, energy transfer, selective separation, and micro/nanofluidic devices.

Analyzing the mass of behind-armor debris (BAD) generated by Rolled Homogeneous Armor (RHA) subjected to normal penetration of variable cross-section Explosively Formed Projectile (EFP) is the purpose of this paper. So theoretical analysis, numerical simulation and experimental data are combined to analyze the influence of variable cross-section characteristic on the time history of crater radius. Moreover the relationships between time history of crater radius (as well as mass of BAD) and the thickness of RHA (from 30 mm to 70 mm) and the impact velocity of EFP (1650 m/s to 1860 m/s) are also investigated. The results indicate that: 1) being compared to the variable cross-section characteristic is ignored, the theoretical time history of crater radius is in better agreement with the simulation results when the variable cross-section characteristic is considered; 2) being compared to the other three conditions of plug, the theoretical mass of BAD is in the best agreement with the simulation results when the shape of plug is frustum of a cone and the angle between generatrix and bottom is 45° and the axial length of mushroom is considered. Keywords: Explosively formed projectile, Behind-armor debris, Variable cross-section characteristic, Shape of plug, Axial length of mushroom, Theoretical model

Moire tomography has been considered as powerful diagnostic tool to flow fields with advantages of noncontact, compact optical structure, strong anti-vibration capability and large dynamic range. However, the refractive index reconstructions in the existing moire tomography are based on the straight ray assumption, by which the light propagation effects caused by the inhomogeneities of flow fields are not taken into account. In this paper, a spatial-domain filtered back-propagation (FBPP) algorithm for moire tomography is studied from the wave equation in inhomogeneous media. Three advancements can be achieved by the algorithm: (1) the weak scattering effect caused by the inhomogeneities of flow field is considered; (2) the first-order derivative of the projected phase measured by moire deflectometry can be directly employed to quantitatively reconstruct the refractive index; (3) the reconstruction is calculated in pure spatial domain, which can reduce the errors resulted by the conversions in frequency domain in the conventional FBPP algorithm. The feasibility and accuracy of the algorithm is checked by numerical simulations. Finally, the refractive index of an axisymmetric propane-air premixed flame is measured by moire tomography with the proposed reconstruction algorithm and the temperature distribution is deduced.

Three-dimensional(3D) flame chemiluminescence tomography (FCT) is realized in multi-direction and multi-angle using traditional iterative algorithms. However, 3D-FCT is often challenged by insufficient sampling data because of the limited observation windows provided in practical for flame measurement. To obtain flame multiple projections in limited observation windows, we develop a camera array arrangement in FCT. In addition, a residual network with a new loss function combing physical model of flame is proposed to achieve higher reconstruction accuracy, faster reconstruction speed and efficient image feature in residual network for 3D FCT measurement. Furthermore, the determination of the weight coefficient in the loss function is performed by numerical simulation experiments. The flame reconstruction results show that the proposed residual network method including the new loss function has more reliable structural similarity and noise immunity compared with the ART algorithm and the CNN algorithm. This work provides a faster and more accurate method for combustion diagnosis under limited observation windows with insufficient projections.

Paulomycins (PAUs) refer to a group of glycosylated antibiotics with attractive antibacterial activities against Gram-positive bacteria. They contain a special ring A moiety that is prone to dehydrate between C-4 and C-5 to a quinone-type form at acidic condition, which will reduce the antibacterial activities of PAUs significantly. Elucidation of the biosynthetic mechanism of the ring A moiety may facilitate its structure modifications by combinatorial biosynthesis to generate PAU analogues with enhanced bioactivity or stability. Previous studies showed that the ring A moiety is derived from chorismate, which is converted to 3-hydroxyanthranilic acid (3-HAA) by a 2-amino-2-deoxyisochorismate (ADIC) synthase, a 2,3-dihydro-3-hydroxyanthranilic acid (DHHA) synthase, and a DHHA dehydrogenase. Unfortunately, little is known about the conversion process from 3-HAA to the highly decorated ring A moiety of PAUs. In this work, we characterized Pau17 as an unprecedented 3-HAA 6-hydroxylase responsible for the conversion of 3-HAA to 3,6-DHAA by in vivo and in vitro studies, pushing one step forward toward elucidating the biosynthetic mechanism of the ring A moiety of PAUs.

The liquid jet formation can be induced by the asymmetric collapse of the cavitation bubble located nearby boundaries. The jet translational direction and speed can be influenced by the type of the boundary, e.g. solid boundary, free surface or elastic boundary, and the relative locations of the cavitation bubble and the boundary. The mechanisms of the liquid jet formation of a single bubble generated between two parallel solid plates are investigated through the strobe photography experimental method and numerical simulations. It is found that there are two conditions for the bubble to split into two smaller bubbles, which could collapse respectively toward the boundary closer to them and form the liquid jet. The first condition is that the proportion of the maximum bubble diameter to the distance of the two plates, which is denoted as ρ , surpasses the threshold of 0.78. The distance of the bubble center to one of the plates, which is closer to the bubble, is denoted as d . The proportion of d to the maximum bubble radius is denoted as γ . The second condition is that γ surpasses the minimum value, which decreases from 1.1 to 0.3 as ρ grows from 0.78 to 1.35. The size of the separated bubble, that locates closer to one of the plates, decreases as the original bubble moves from the middle toward the other plate. Furthermore, it is found that the maximum jet speed of about 100 m/s appeared when the optimum relative bubble size equals to 1.09 and for the bubble located at the middle of the plates. Therefore, the jet speed and diameter could be adjusted by the relative size and generation position of the bubble between the plates. In this way, the laser energy can be controllably transformed into the directional mechanical force through bubble interactions with a pair of solid plates.

The flow-induced lateral vibration phenomenon of the terminal sensitive bullets (TSB) when it is dispersed by the airborne distributor is taken as the research background. Based on the Fluent, the flow around a rotating short cylindrical TSB (L/D < 1) is simulated and analyzed varying with relative rotation velocity at high Re number (1×105 ≤ Re ≤ 3×106). The simulation results show that the flow field structure of the short cylinder with two free ends is different from the symmetry of the short cylindrical flow field with one free end, and there is no horseshoe vortex. Compared to the long cylinder with double free ends, the Cd of the short cylinder is more sensitive to the change of Re. With the increase of Re, the Cd of the short cylinder decreases, and the value is between the infinite cylinder and the sphere in the non-critical region. When the short cylinder rotates at the angular velocity ω, the top vortex bends and deforms to a ‘C’ shape on the leeward side where the fluid is accelerated. Due to the periodic disturbance of the detector, the aerodynamic coefficient of the rotating TSB is periodically vibrated. In a single cycle, the waveform of the cd shows a ‘W’ shape, and the waveform of the cl is ‘M’.

An unprecedented [4 + 3] annulation reaction of aza- ortho-quinone methides with arylcarbohydrazonoyl chlorides has been achieved under mild conditions. The annulation underwent a sequential conjugate addition/intramolecular annulation/rearrangement, providing a useful method for the synthesis of biologically interesting 2,3-dihydro-1 H-benzo[ e][1,2,4]triazepine.

To realize volume moire tomography (VMT) for the real three-dimensional (3D) diagnosis of combustion fields, according to 3D filtered back projection (FBP) reconstruction algorithm, the radial derivatives of the projected phase should be measured firstly. In this paper, a simple spatial phase-shifting moire deflectometry with double cross gratings is presented to measure the radial first-order derivative of the projected phase. Based on scalar diffraction theory, the explicit analytical intensity distributions of moire patterns on different diffracted orders are derived, and the spatial shifting characteristics are analyzed. The results indicate that the first-order derivatives of the projected phase in two mutually perpendicular directions are involved in moire patterns, which can be combined to compute the radial first-order derivative. And multiple spatial phase-shifted moire patterns can be simultaneously obtained; the phase-shifted values are determined by the parameters of the system. A four-step phase-shifting algorithm is proposed for phase extraction, and its accuracy is proved by numerical simulations. Finally, the moire deflectometry is used to measure the radial first-order derivative of projected phase of a propane flame with plane incident wave, and the 3D temperature distribution is reconstructed.

In this paper, a transient multi-parameter three-dimensional (3D) reconstruction method is proposed to diagnose and visualize a combustion flow field. Emission and transmission tomography based on spatial phase-shifted technology are combined to reconstruct, simultaneously, the various physical parameter distributions of a propane flame. Two cameras triggered by the internal trigger mode capture the projection information of the emission and moire tomography, respectively. A two-step spatial phase-shifting method is applied to extract the phase distribution in the moire fringes. By using the filtered back-projection algorithm, we reconstruct the 3D refractive-index distribution of the combustion flow field. Finally, the 3D temperature distribution of the flame is obtained from the refractive index distribution using the Gladstone–Dale equation. Meanwhile, the 3D intensity distribution is reconstructed based on the radiation projections from the emission tomography. Therefore, the structure and edge information of the propane flame are well visualized.

We present the optical design of a Czerny-Turner imaging spectrometer for which astigmatism is corrected using off-the-shelf optics resulting in spectral resolution of 0.1 nm. The classic Czerny-Turner imaging spectrometer, consisting of a plane grating, two spherical mirrors, and a sensor with 10-μm pixels, was used as the benchmark. We comparatively assessed three configurations of the spectrometer that corrected astigmatism with divergent illumination of the grating, by adding a cylindrical lens, or by adding a cylindrical mirror. When configured with the added cylindrical lens, the imaging spectrometer with a point field of view (FOV) and a linear sensor achieved diffraction-limited performance over a broadband width of 400 nm centered at 800 nm, while the maximum allowable bandwidth was only 200 nm for the other two configurations. When configured with the added cylindrical mirror, the imaging spectrometer with a one-dimensional field of view (1D FOV) and an area sensor showed its superiority on imaging quality, spectral nonlinearity, as well as keystone over 100 nm bandwidth and 10 mm spatial extent along the entrance slit.

The measurement and visualization of transient three-dimensional (3-D) physical parameters (density and temperature) distribution of complex flow fields are critical technologies for the characteristics studies of flow fields in modern energy engineering. Among the optical computed tomography (OCT) methods, Moire tomography has the advantages of simple optical path structure, strong anti-interference ability and wide measurement range, which is especially suitable for complex flow field measurement in noisy environments. Acquiring the transient phase information from the moire projection is of great importance for the dynamic 3-D parameters reconstruction of complex flow fields. In this paper, the dynamic phase retrieve methods including Fourier and spatial phase-shifting in moire tomographic are studied, respectively. In the Fourier method, an adaptive first-order spectrum extraction algorithm for Fourier transform moire fringe and a phase calculation method are proposed. Through this, the projection phase can be obtained directly by multiplying the inverse Fourier transform of the positive first-order spectrum of deformed fringe with the inverse Fourier transform of the negative first-order spectrum of reference fringe. In spatial phase-shifting method, a spatial phase-shifting- interferometry-based moire volume computed tomography (MVCT) method was proposed to extract the radial shearing phase distribution of grid moire fringe. The measured results for the first-order partial derivative of the phase projection of a propane flame both by Fourier and spatial phase-shifting methods in the experimental moire computed tomography systems are presented. The research will be valuable for monitoring the combustion state in energy engineering.

Full-field optical coherence tomography (FF-OCT) has been reported with its label-free subcellular imaging performance. To realize quantitive cancer detection, the support vector machine model of classifying normal and cancerous human liver tissue is proposed with en face tomographic images. Twenty samples (10 normal and 10 cancerous) were operated from humans and composed of 285 en face tomographic images. Six histogram features and one proposed fractal dimension parameter that reveal the refractive index inhomogeneities of tissue were extracted and made up the training set. The other different 16 samples (8 normal and 8 cancerous) were imaged (190 images) and employed as the test set with the same features. First, a subcellular-resolution tomographic image library for four histopathological areas in liver tissue was established. Second, the area under the receiver operating characteristics of 0.9378, 0.9858, 0.9391, 0.9517 for prediction of the cancerous hepatic cell, central vein, fibrosis, and portal vein were measured with the test set. The results indicate that the proposed classifier from FF-OCT images shows promise as a label-free assessment of quantified tumor detection, suggesting the fractal dimension-based classifier could aid clinicians in detecting tumor boundaries for resection in surgery in the future.

Synthetic aperture particle image velocimetry (SAPIV) provides a non-invasive means of revealing the physics of complex flows using a compact camera array to resolve the 3D flow field with high temporal and spatial resolution. Intensity-threshold-based methods of reconstructing the flow field are unsatisfactory in nonuniform illuminated fluid flows. This article investigates the characteristics of the focused particles in re-projected image stacks, and presents a convolutional neural network (CNN)-based particle field reconstruction method. The CNN architecture determines the likelihood of each area containing focused particles in the re-projected 3D image stacks. The structural similarity between the images projected by the reconstructed particle field and the images captured from the cameras is then computed, allowing in-focus particles to be extracted. The feasibility of our method is investigated through synthetic simulations and experiments. The results show that the proposed technique achieves remarkable performance, paving the way for non-uniformly illuminated particle field applications in 3D velocity measurements.

The purpose of this study is to analyse how the thickness of Rolled Homogeneous Armor (RHA) and impact velocity of an Explosively Formed Projectile (EFP) influence the middle mass behind-armor debris (BAD) when a variable cross-section EFP penetrates RHA normally. Numerical simulation is adopted, the thickness of RHA varies from 10mm to 70mm, and the impact velocity of the EFP varies from 1650m/s to 1860m/s. The results indicate that: (1) when the impact velocity of the EFP is 1650m/s and the thickness of RHA varies from 10mm to 70mm, p1g of the RHA and EFP decreases with increasing H0. The thin target could be used to produce a large proportion of the middle mass BAD from RHA (including BAD from the EFP and BAD from the RHA and EFP). (2) When the impact velocity of the EFP varies from 1650m/s to 1860m/s and the thickness of the RHA is 40mm, p1g of the RHA is less than 50%, p1g of the EFP is more than 70%, and p1g of the RHA and EFP is more than 50%.

Computed tomography of chemiluminescence (CTC) is an effective technique for three-dimensional (3D) combustion diagnostics. It reconstructs the 3D concentrations of intermediate species or 3D images of flame topology by multiple chemiluminescence projections captured from different perspectives. In the previous studies of CTC systems, it was assumed that projections from arbitrary perspectives are available. However, for some practical applications, the range of view angles and the number of projections might be restricted due to the optical access limitation, greatly affecting the reconstruction quality. In this paper, the exact reconstruction condition for angle-limited computed tomography of chemiluminescence was studied based on Mojette transform theories, and it was demonstrated by numerical simulations and experiments. The studies indicate that the object tested within limited angles can be well reconstructed when the number of grids, the number of projections, and the sampling rate of projections satisfy the exact reconstruction condition. By increasing the sampling rate of projections, high-quality tomographic reconstruction can be achieved by a few projections in a small angle range. Although this technique is discussed under combustion diagnostics, it can also be used and adapted for other tomography methods.

We demonstrated a tunable Q-switched Er-doped fiber laser (EDFL) by employing one single mode fiber–step-index multimode fiber–single mode fiber (SMF–SIMF–SMF) structure as both saturable absorber (SA) and filter. Such SMF–SIMF–SMF structure is based on multimode interference. A tunable Q-switched EDFL with a tuning range from 1553 to 1569 nm was achieved by bending SIMF. When the Q-switched fiber laser operated at 1560 nm, a repetition rate of 84 kHz was obtained, together with pulse width and pulse energy of 1. 47 μ s and 104.7 nJ under the maximum pump power of 800 mW. Our results show that the SMF–SIMF–SMF structure is promising difunctional device for wavelength and pulse modulation.

A Lewis-base-catalyzed enantioselective [3 + 3] annulation reaction of Morita–Baylis–Hillman (MBH) carbonates with α-arylidene pyrazolinones is described, affording the pyrazolone-fused spirocyclohexenes bearing an all-carbon quaternary stereocenter in high yields with good to excellent diastereoselectivities and excellent enantioselectivities.

Driving a liquid droplet with control of directional motion on a solid surface, by introducing a surface wettability gradient or external stimuli, has attracted considerable research attention. There still remain challenges, however, due to the slow response rate and slow speed of continuous liquid droplet motion on the structured surface. Here, an approach to continuously drive the underwater oil droplet with control of directional motion by the cooperative effects of an electric field and the gradient of a porous polystyrene microstructure is demonstrated. The gradient microstructure induces the liquid droplet to take on an asymmetrical shape, causing unbalanced pressure on both ends to orient the droplet for motion in a particular direction. Meanwhile, the electric field decreases the contact area and the corresponding viscous drag between the droplet and the gradient-structured surface. Then, the unbalanced pressure pushes the underwater oil droplet to move directionally and continuously at a certain voltage. This work provides a new strategy to control underwater oil droplets and realize unidirectional motion. It is also promising for the design of new smart interface materials for applications such as electrofluidic displays, biological cell and particle manipulation, and other types of microfluidic devices.

Camera calibration is necessary for accurate image measurements, particularly in multicamera systems. The calibration process involves corresponding the coordinates of 3D calibration points with a 2D image and requires the establishment of a reliable 3D world coordinate system. This paper presents a convenient multicamera calibration method that uses a rotating calibration plate and multi-view stereo vision to calculate 3D points and their relationship with the image coordinates. Despite simple implementation, the rotation of the calibration plate presents numerous calibration points from various planes, increasing the stability of the solution and the noise reduction. The relocation accuracy and reprojection error are experimentally verified.

The flow field velocity is an important parameter for completely characterizing the topologies of unsteady coherent flow structures. Synthetic aperture (SA)-based particle image velocimetry (SAPIV) has been used for three-dimensional flow measurements, owing to its wide range of acceptable tracer particle intensities and ability to view partially occluded fields. However, SAPIV typically suffers from poor reconstruction quality for nonuniformly illuminated particle volumes. In this paper, we propose a hybrid remapping particle field reconstruction method for SAPIV in a nonuniformly illuminated fluid flow. Both additive and minimum line-of-sight remapping are used to reconstruct the in-focus particles from the refocused image stacks. The structural similarity between the images projected by the reconstructed particle field and the images captured by the cameras are used to determine the reconstruction quality. This method was verified by both synthetic simulation and an experimental implementation. The performance of the proposed technique was compared with existing methods. The proposed method has the best reconstruction quality and computational speed among the considered methods.

Subaperture stitching interferometry (SAS) is an important method for map testing of large aperture optical components, in which a mechanical structure is often employed for the testing of each subaperture. By eliminating the phase deviation of the corresponding points in the overlapping regions of every adjacent subaperture, the whole aperture map can be obtained. Accurate subaperture positioning is an important guarantee for precise stitching. In this paper, a hybrid optimization algorithm is proposed to realize subpixel-level positioning accuracy in SAS based on the combination of the phase correlation and iterative gradient methods. The phase correlation method is adopted to calculate the pixel-level positioning deviation first, and the subpixel deviation is derived and then corrected by iterative optimization through the gradient method. The subpixel-level positioning accuracy of the proposed optimization algorithm is verified by simulations and a 76.2 mm off-axis parabolic mirror is chosen as an experimental testing sample. The surface map obtained from the proposed hybrid optimization method is consistent with the full aperture testing result, which also verifies that the proposed optimization algorithm is a powerful tool with subpixel-level positioning accuracy in SAS testing.

The tandem nucleophilic addition-cycloaddition reaction has been developed for the synthesis of functionalized imidazolidine derivatives. A variety of α-iminoesters and aryne precursors were well tolerated under the mild reaction conditions. This asymmetric cycloaddition afforded imidazolidine derivatives with high yields, complete regioselectivities, and excellent diastereo- and enantioselectivities. Aryne-induced ylides working as 1,3-dipoles for asymmetric cycloaddition are the notable feature of the present reaction. In the tandem reaction, the [3+2] cycloaddition of aryne-induced ylides with metallized α-iminoesters and metal-catalyzed [3+2] cycloaddition of azomethine ylide with α-iminoesters are two concurrent pathways to imidazolidines.

In this paper, the application of moire and emission tomography in diagnosing the high-temperature and illuminant flow field in the open system is studied, and two flames with different spatial size are chosen as typical objects. First of all, the moire fringes and the corresponding measured two flames are obtained by integrating moire and emission tomography. After that, the distribution and the brightness of the moire fringes are compared for the two flame flow fields, as well as the distributions of the refractive index and the components. Then, the temperature distributions of the two flames are compared and analyzed. The results show that, when moire and emission tomography are applied in diagnosing the high-temperature and illuminant flow field in the open system, the size, the structure and the species components of the measured flow fields have important effect on the final temperature results. Consequently, the specific problem should be specifically analyzed for the optical diagnosis of flow fields.

Particle image velocimetry (PIV) is a necessary flow field diagnostic technique that provides instantaneous velocimetry information non-intrusively. Three-dimensional (3D) PIV methods can supply the full understanding of a 3D structure, the complete stress tensor, and the vorticity vector in the complex flows. In synthetic aperture particle image velocimetry (SAPIV), the flow field can be measured with large particle intensities from the same direction by different cameras. During SAPIV particle reconstruction, particles are commonly reconstructed by manually setting a threshold to filter out unfocused particles in the refocused images. In this paper, the particle intensity distribution in refocused images is analyzed, and a SAPIV particle field reconstruction method based on an adaptive threshold is presented. By using the adaptive threshold to filter the 3D measurement volume integrally, the three-dimensional location information of the focused particles can be reconstructed. The cross correlations between images captured from cameras and images projected by the reconstructed particle field are calculated for different threshold values. The optimal threshold is determined by cubic curve fitting and is defined as the threshold value that causes the correlation coefficient to reach its maximum. The numerical simulation of a 16-camera array and a particle field at two adjacent time events quantitatively evaluates the performance of the proposed method. An experimental system consisting of a camera array of 16 cameras was used to reconstruct the four adjacent frames in a vortex flow field. The results show that the proposed reconstruction method can effectively reconstruct the 3D particle fields.

Oily wastewater is always a threat to biological and human safety, and it is a worldwide challenge to solve the problem of disposing of it. The development of interface science brings hope of solving this serious problem, however. Inspired by the capacity for capturing water of natural fabrics and by the underwater superoleophobic self-cleaning property of fish scales, a strategy is proposed to design and fabricate micro/nanoscale hierarchical-structured fabric membranes with superhydrophilicity and underwater superoleophobicity, by coating scaly titanium oxide nanostructures onto fabric microstructures, which can separate oil/water mixtures efficiently. The microstructures of the fabrics are beneficial for achieving high water-holding capacity of the membranes. More importantly, the special scaly titanium oxide nanostructures are critical for achieving the desired superwetting property toward water of the membranes, which means that air bubbles cannot exist on them in water and there is ultralow underwater-oil adhesion. The cooperative effects of the microscale and nanoscale structures result in the formation of a stable oil/water/solid triphase interface with a robust underwater superoleophobic self-cleaning property. Furthermore, the fabrics are common, commercially cheap, and environmentally friendly materials with flexible but robust mechanical properties, which make the fabric membranes a good candidate for oil/water separation even under strong water flow. This work would also be helpful for developing new underwater superoleophobic self-cleaning materials and related devices.

Due to its advantages of nonintrusiveness, wide measurement range, and insensitivity to variation, Moire deflectometry is a powerful tool for quantitative measurement of a flow field’s physical parameters such as density and temperature. Moire volume computed tomography (MVCT), combining the moire deflectometry and volume optical computed tomography (VOCT), can realize real three-dimensional parameters reconstruction, in which the radial derivatives extraction of the projected phase is of great importance. In this paper, a spatial phase-shifting-interferometry-based MVCT system was proposed to extract the radial shearing phase distribution. The system is simple and compact, and consists of three crossed gratings and lenses, with no wave plates or polarizers introduced. Via using a 4-f system, the optical path was shortened, and four spatial phase-shifting grid moire projections can be obtained simultaneously. Each grid interferogram was filtered and separated into two linear interferograms in two orthogonal directions. Moreover, a two-step spatial phase-shifting algorithm was applied to obtain the first-order derivative phase in two mutually perpendicular directions, respectively. Simulations were implemented to verify the feasibility and accuracy of the proposed phase retrieval method. The measured results for the radial first-order partial derivative of the phase projection of a propane flame in the experimental VOCT system are presented.

An enantioselective synthesis of biologically important imidazolidines has been achieved via a tandem [3 + 2] cycloaddition/1,4-addition reaction of azomethine ylide and aza-o-quinone methides. With the use of this tool, various imidazolidine derivatives are obtained in good yields with excellent diastereoselectivities and enantioselectivities.

To acquire phase projection information for moire tomography, a new spatial phase-shifting lateral shearing interferometry is presented in this paper. The system is very simple and contains only three linear gratings and two filters. No wave plates or polarization elements are introduced. Moreover, via using a 4-f system, the optical path is greatly shortened and two complete spatial phase-shifted lateral shearing interferograms can be obtained simultaneously. A corresponding two-step phase-shifting algorithm is used for phase retrieval and the interferometry is used to extract the first-order partial derivative of the spherical wave. The results show that the proposed method is not only feasible but also has high accuracy. Propane flame phase information is measured by the optical system. Finally, error analysis of phase projection extracted by two-step spatial phase-shifting method is mathematically conducted.

Computed tomography of chemiluminescence (CTC) is an effective tool for combustion diagnostics by using optical detectors to capture the projections of luminescence from multiple views and realizing the three-dimensional (3D) reconstruction by computed tomography (CT) theories. In the existing CTC, ordinary commodity lenses were employed in the system for imaging, the imaging effects complicate the projection model and the low sampling rate decreases the spatial resolution and reconstruction accuracy. In classical CT techniques, parallel projection based on 2D Radon transform is the simplest model, which has been widely used in CT applications. In this work, double telecentric lens is introduced in CTC to realize the acquisition of parallel projection with high sampling rate. Despite the parallel projection CT theories have been well studied, there are still a few theoretical and technological drawbacks need to be solved when utilizing double telecentric lens in CTC. Firstly, a simple method based on bilinear interpolation is studied to improve the calculation accuracy of the weight matrix. Secondly, the exact reconstruction condition for parallel projections is studied based on the discrete Radon transform theory. It establishes the theoretical relationship of the reconstruction quality and the sampling rate of the projections, the number of views, the range and the spatial resolution of the reconstructed region. In experiment, camera calibration technique for double telecentric lens is studied, and the results of which are used for projection correction. The tomographic reconstructions of an axisymmetric flame demonstrate the feasibility and accuracy of the studies.

Controllable surface adhesion of solid substrates has aroused great interest both in air and underwater in solving many challenging interfacial science problems such as robust antifouling, oil-repellent, and highly efficient oil/water separation materials. Recently, responsive surface adhesion, especially switchable adhesion, under external stimulus in air has been paid more and more attention in fundamental research and industrial applications. However, phototunable underwater oil adhesion is still a challenge. Here, an approach to realize phototunable underwater oil adhesion on aligned ZnO nanorod array-coated films is reported, via a special switchable contact mode between an unstable liquid/gas/solid tri-phase contact mode and stable liquid/liquid/solid tri-phase contact mode. The photo-induced wettability transition to water and air exists (or does not) in the micro/nanoscale hierarchical structure of the mesh films, playing important role in controlling the underwater oil adhesion behavior. This work is promising in the design of novel interfacial materials and functional devices for practical applications such as photo-induced underwater oil manipulation and release, with loss-free oil droplet transportation.

Stimuli-responsive surface wettability has been intensively studied, especially wettability controlled by photoelectric cooperation, which appears to be a trend for more effective surface wetting. In this field, the patterning of controllable surface wettability is still a challenge in the application of liquid-printing techniques because of the high adhesion and high responsive voltage, as well as low mechanical strength, of the substrate. Herein, we have demonstrated the patterning of liquid permeation controlled by photoelectric cooperative wetting on the micro/nano hierarchically structured ZnO mesh film. The special micro/nano hierarchically structured ZnO mesh is beneficial for lowering adhesion force on the mesh surface than those of the TiO2/AAO nanopore array films previously reported for the discontinuous tri-phase contact line, in addition to precisely controlled microscale liquid movement with considerably lower threshold voltage for the hierarchical structure. Moreover, the stainless-steel mesh with different pore sizes as a substrate behaves with higher mechanical strength and lower cost, compared with the anodized Ti mesh. Thus, this work is promising for accelerating the development of patterned liquid permeation and extending the application of micro/nanofluidic system and micronanoelectronic technology.

Moire tomography has been considered as an effective tool in studying flow fields because of its advantages such as non-contact measurement, strong anti-disturbing capability, and wide measurement range. The spatial phase-shifting method, which can simultaneously obtain several phase-shifted interferograms, can be applied in the flow field measurements by the moire tomography when the flow field varies rapidly. In this paper, we present a new spatial phase-shifting shearing interferometry. The optical structure of the interferometry, which only consists of a crossed grating and a linear grating, is very simple. With it six phase-shifted interferograms can be acquired simultaneously. Based on the scalar diffraction theory, the explicit forms of intensity distribution of the interferograms containing the phase information can be derived and a corresponding four-step phase-shifting algorithm is proposed to extract the first-order partial derivative of phase projection from the interferograms. Finally, the spatial phase shifting optical system is used to retrieve the first-order partial derivative of propane flame phase projection produced by plane incident wave. This work is crucial to accuracy reconstruction the physical parameter of the varied flow fields in moire tomography.

To realize three-dimensional (3D) instantaneous diagnoses for flow fields, many multidirectional optical computerized tomographic (optical CT) techniques based on laser interferometry have been proposed. Projections from different directions of these tomographic systems are captured simultaneously to reconstruct the test field. These projections are independent from each other. However, due to the inevitable errors from installation and difference between optical elements, projections will be imaged with different distortion and located at different positions on the sensors. Therefore, a multidirectional calibration should be performed to remap these projections to a unified coordinate system before CT reconstruction. As far as we know, the multidirectional calibration problem for laser interferometric CT techniques has never been discussed in previous research. In this paper, a six-directional moiré tomographic system is designed. Considering the projection characteristics of moiré deflectometry, a multidirectional affine calibration method is proposed to determine the extrinsic and intrinsic parameters of tomographic projections. With the calibration results, projections can be remapped to the unified coordinate system and the 3D distributions of flow field can be reconstructed.

Smart surfaces with responsive wettability to external stimulus have attracted considerable attention especially in oil/water/solid interface, whereas there still remain challenges of response in situ, low voltage, and stable substrate. Here, a strategy is proposed to achieve the electric field induced water selectively permeation for oil/water separation based on the stainless steel mesh coated with root-like polyaniline nanofibers fabricated by emulsion polymerization. Such micro/nanoscale hierarchical-structured polyaniline mesh is superhydrophobic and underwater superoleophobic, while its superhydrophobicity can turn to hydrophilicity at 160 V and can further selectively filter water at 170 V. As a result, the electric field induced oil/water separation is realized as long as the electric capillary pressure (ECP) is larger than the hydrostatic pressure of the membrane to water, i.e., ECP induced wettability to water transition. The mesh shows low underwater oil-adhesion force and the anti-corrosion of polyaniline, indicating that the mesh could keep working under severe environment during the practical application. Thus, this work is promising in the application of controllable oil/water separation and will also be beneficial to the study of smart filtration, microreactors, and microfluidic devices.