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Due to less light scattering and a better signal-to-noise ratio in deep imaging, two-photon fluorescence microscopy (TPFM) has been widely used in biomedical photonics since its advent. However, optical aberrations degrade the performance of TPFM in terms of the signal intensity and the imaging depth and therefore restrict its application. Here, we introduce adaptive optics based on the genetic algorithm to detect the distorted wavefront of the excitation laser beam and then perform aberration correction to optimize the performance of TPFM. By using a spatial light modulator as the wavefront controller, the correction phase is obtained through a signal feedback loop and a process of natural selection. The experimental results show that the signal intensity and imaging depth of TPFM are improved after aberration correction. Finally, the method was applied to two-photon fluorescence lifetime imaging, which helps to improve the signal-to-noise ratio and the accuracy of lifetime analysis. Furthermore, the method can also be implemented in other experiments, such as three-photon microscopy, light-sheet microscopy, and super-resolution microscopy.
We address a challenge of active flow control: the optimization of many actuation parameters guaranteeing fast convergence and avoiding suboptimal local minima. This challenge is addressed by a new optimizer, called the explorative gradient method (EGM). EGM alternatively performs one exploitive downhill simplex step and an explorative Latin hypercube sampling iteration. Thus, the convergence rate of a gradient based method is guaranteed while, at the same time, better minima are explored. For an analytical multi-modal test function, EGM is shown to significantly outperform the downhill simplex method, the random restart simplex, Latin hypercube sampling, Monte Carlo sampling and the genetic algorithm. EGM is applied to minimize the net drag power of the two-dimensional fluidic pinball benchmark with three cylinder rotations as actuation parameters. The net drag power is reduced by 29 % employing direct numerical simulations at a Reynolds number of $100$ based on the cylinder diameter. This optimal actuation leads to 52 % drag reduction employing Coanda forcing for boat tailing and partial stabilization of vortex shedding. The price is an actuation energy corresponding to 23 % of the unforced parasitic drag power. EGM is also used to minimize drag of the $35^\circ$ slanted Ahmed body employing distributed steady blowing with 10 inputs. 17 % drag reduction are achieved using Reynolds-averaged Navier–Stokes simulations at the Reynolds number $Re_H=1.9 \times 10^5$ based on the height of the Ahmed body. The wake is controlled with seven local jet-slot actuators at all trailing edges. Symmetric operation corresponds to five independent actuator groups at top, middle, bottom, top sides and bottom sides. Each slot actuator produces a uniform jet with the velocity and angle as free parameters, yielding 10 actuation parameters as free inputs. The optimal actuation emulates boat tailing by inward-directed blowing with velocities which are comparable to the oncoming velocity. We expect that EGM will be employed as efficient optimizer in many future active flow control plants as alternative or augmentation to pure gradient search or explorative methods.
Previously, we reported the myelin regulatory factor (MYRF) as a candidate gene for nanophthalmos. We have also produced Myrf knockdown (Myrf+/−) mouse strain to investigate the cellular and molecular phenotypes of reduced MYRF expression in the retina. Myrf+/− mouse strain was generated using the CRISPR/Cas9 system. Optomotor response system, electroretinogram (ERG), spectral-domain optical coherence tomography (SD-OCT), histology, and immunohistochemistry were performed to evaluate retinal spatial vision, electrophysiological function, retinal thickness, and pathological changes in cone or rod photoreceptors, respectively. RNA sequencing (RNA-seq) was performed to investigate the underlying molecular mechanism linking Myrf deficiency with photoreceptor defects. The genotype and phenotype of CRISPR/Cas9-induced Myrf+/− mice and their offspring were comprehensively investigated. Photoreceptor defects were detected in the retinas of Myrf+/− mice. Visual acuity and ERG responses were decreased in Myrf+/− mice compared with the control mice (Myrf+/+). The loss of cone and rod neurons was proportional to the decreased outer nuclear layer (ONL) thickness. Moreover, RNA-seq revealed that phototransduction and estrogen signaling pathways played important roles in the Kyoto Encyclopedia of Genes and Genomes (KEGG) analysis. Myrf+/− mouse strain provides a good model to investigate the function of the MYRF gene. Photoreceptor defects with impaired functions of spatial vision and retinal electrophysiology indicate an important role played by MYRF in retinal development. Alterations in phototransduction and estrogen signaling pathways play important roles in linking Myrf deficiency with retinal photoreceptor defects.
We investigated the connectivity of high-energy random grain boundaries through fractal analyses of specimens with different grain boundary (GB) microstructures in BFe10-1-1 copper–nickel alloy. It was found that the profile of maximum random boundary network possesses a fractal nature and more than one fractal dimension can exist. The fraction of special boundaries and grain size homogeneity can play an important role on GB character distribution. Here, GB microstructures are combined with quantitative materials structure–property relationship models to predict intergranular corrosion properties. The experimental results are accurately consistent with the theoretical predictions.
The Richtmyer–Meshkov instability on a three-dimensional single-mode light/heavy interface is experimentally studied in a converging shock tube. The converging shock tube has a slender test section so that the non-uniform feature of the shocked flow is amply exhibited in a long testing time. A deceleration phenomenon is evident in the unperturbed interface subjected to a converging shock. The single-mode interface presents three-dimensional characteristics because of its minimum surface feature, which leads to the stratified evolution of the shocked interface. For the symmetry interface, it is quantitatively found that the perturbation amplitude experiences a rapid growth to a maximum value after shock compression and finally drops quickly before the reshock. This quick reduction of the interface amplitude is ascribed to a significant Rayleigh–Taylor stabilization effect caused by the deceleration of the light/heavy interface. The long-term effect of the Rayleigh–Taylor stabilization even leads to a phase inversion on the interface before the reshock when the initial interface has sufficiently small perturbations. It is also found that the amplitude growth is strongly suppressed by the three-dimensional effect, which facilitates the occurrence of the phase inversion.
Chinese jiaotou is an economically important crop that is widely cultivated in East Asia. The lack of simple sequence repeat (SSR) markers has been a major obstacle for genetic studies of this crop. In the present study, SSR markers were developed for Chinese jiaotou on a large scale, based on the crop's transcriptome assembled de novo by a previous study. A search for SSR loci in the transcriptome's expressed sequence tags (ESTs) revealed 2157 SSRs, of which primer pairs could be developed for 1494. Among these resulting SSRs, trinucleotide repeat motifs were the most abundant type, with GAA/TTC motifs occurring most frequently. Analysing the annotated function of SSR-containing ESTs revealed that they enriched into the GO categories involved in transcription regulation, oxidation–reduction, transport, etc. The quality and transferability of these markers were also assessed using 100 randomly selected EST–SSRs, and the result showed that these markers were of good quality and possessed high cross-species transferability. In addition, the developed SSR markers were used to analyse the genetic diversity of 19 cultivated and four wild accessions, resulting in three distinct groups, cluster I, II and III. Interestingly, all four wild accessions were assigned to cluster III, and two local varieties from northern Hunan, China, were closely related to the wild genotypes. These results provide new insights into the origin of Chinese jiaotou. The EST–SSRs developed herein represent the first large-scale development of SSR markers in Chinese jiaotou, and they can be widely used for genetic studies of the crop.
The objective of maintaining the cleanliness of the multi-segment disk amplifier in Shenguang-II (SG-II) is to reduce laser-induced damage for optics. The flow field of clean gas, which is used for the transportation of contaminant particles, is a key factor affecting the cleanliness level in the multi-segment disk amplifier. We developed a gas–solid coupling and three-dimensional flow numerical simulation model. The three-dimensional and two-phase flow model is verified by the flow-field smog experiment and the particle concentration measurement experiment with the 130-disk amplifier in SG-II. By optimizing the boundary conditions with the same flow rate, the multi-inlet vector flow scheme can not only effectively reduce the purging time, but also prevent the reverse diffusion of contaminant particles in the multi-segment disk amplifier and the deposition of contaminant particles on the surface of the Nd:glass.
We propose a 3D-printable soft, stretchable, and transparent hydrogel-elastomer device that is able to detect simulated ‘nerve’ signals. The signal is passed to a conductive hydrogel electrode through a non-contact method of capacitive coupling through polydimethylsiloxane (PDMS). We demonstrate that the device is able to detect sinusoidal waveforms passed through a simulated ‘nerve’ made from conductive hydrogel over a range of frequencies (1 kHz – 1 MHz). Analysis of signal detection showed a correlation to the electrode contact area and a Vin/Vout of larger than 10%. This provides the framework for the future development of a soft, 3D-printable, capacitive coupling device that can be used as a cuff electrode for detecting peripheral nerve signals.
In this paper, we review the status of the multifunctional experimental platform at the National Laboratory of High Power Laser and Physics (NLHPLP). The platform, including the SG-II laser facility, SG-II 9th beam, SG-II upgrade (SG-II UP) facility, and SG-II 5 PW facility, is operational and available for interested scientists studying inertial confinement fusion (ICF) and a broad range of high-energy-density physics. These facilities can provide important experimental capabilities by combining different pulse widths of nanosecond, picosecond, and femtosecond scales. In addition, the SG-II UP facility, consisting of a single petawatt system and an eight-beam nanosecond system, is introduced including several laser technologies that have been developed to ensure the performance of the facility. Recent developments of the SG-II 5 PW facility are also presented.
This paper systematically compares the numerical implementation and computational cost between the Fourier spectral iterative perturbation method (FSIPM) and the finite element method (FEM) in solving partial differential equilibrium equations with inhomogeneous material coefficients and eigen-fields (e.g., stress-free strain and spontaneous electric polarization) involved in phase-field models. Four benchmark numerical examples, including inhomogeneous elastic, electrostatic, and steady-state heat conduction problems demonstrate that (1) the FSIPM rigorously requires uniform hexahedral (3D) and quadrilateral (2D) mesh and periodic boundary conditions for numerical implementation while the FEM permits arbitrary mesh and boundary conditions; (2) the FSIPM solutions are comparable to their FEM counterparts, and both of them agree with the analytic solutions, (3) the FSIPM is much faster in solving equilibrium equations than the FEM to achieve the accurate solutions, thus exhibiting a greater potential for large-scale 3D computations.
In C-Band transfer measuring systems, the Precise Orbit Determination (POD) precision of Geostationary Earth Orbit (GEO) satellites is limited by signal biases such as the station delay biases, transponder delay biases, the ionospheric delay model bias, etc. In order to improve the POD precision, the signal biases of the Chinese Area Positioning System (CAPS) are calibrated using Satellite Laser Ranging (SLR) and C-Band Transfer Ranging (CBTR) observations. Since the Changchun SLR site and C-Band station are close to each other, the signal biases of the Changchun C-Band station are calibrated using the co-location comparison method. Then the signal biases of the other two CAPS C-Band stations, located in Linton and Kashi, are calibrated using the combined POD method, with the signal biases of the Changchun C-Band station being fixed. After the signal biases are calibrated, the RMS of the line-of-sight residuals of the Changchun SLR observations decrease by 0·4 m, with the percentage improvement being 75·19%.
The aim of the present study was to investigate the effects of different dietary sustained-release microencapsulated sodium butyrate (MSB) products (0 (non-supplement), 1·5 and 3·0 h) for a control or oxidised soyabean oil (SBO) diet on fish production, intestinal mucosal condition, immunity and intestinal bacteria in juvenile common carp (Cyprinus carpio). Dietary MSB increased weight gain and reduced the feed conversion ratio within the control and oxidised SBO groups. Gut mucosa was damaged in the oxidised SBO group fed without MSB, in contrast to a normal appearance found in fish fed the MSB1·5 and MSB3·0 diets in the oxidised SBO group. Microvillus density increased in fish fed the MSB1·5 and MSB3·0 diets in the oxidised SBO group (P< 0·001); however, microvillus density was affected by the different pre-fed diets in the midgut (P< 0·001) and by the different sustained-release times of MSB in the distal gut (DG) (P= 0·003). The interaction between the pre-fed diets and the sustained-release times of dietary MSB was significant for the relative gene expression levels of gut heat shock protein-70 (HSP70), pro-inflammatory cytokines (IL-1β and TNF-α) and anti-inflammatory cytokines (transforming growth factor-β) within each gut segment, except for HSP70 in the DG and IL-1β in the foregut. Modulation of adherent bacterial communities within each gut segment investigated was not obvious when the common carp were fed the diets with MSB, as similarity coefficients of >0·79 were observed. These results indicated that MSB can be used as a dietary supplement to repair or prevent intestinal damage in carp fed oxidised SBO.
Geostationary Earth Orbit (GEO) satellites play a significant role in the space segment of the Chinese Area Navigation System. The C-Band transfer ranging method developed by the National Time Service Center (NTSC) has been widely used in the Chinese Area Positioning System (CAPS), with its advantages of separating satellite ranging from time synchronization and being unaffected by weather. The explicit ranging correction models for the C-Band transfer ranging method are introduced in detail in this article for the first time. Precise Orbit Determination (POD) using C-Band pseudo-range observation of GEO satellite 2010-001A in July 2012 has been conducted. The residual Root Mean Square (RMS) of each site and POD are analysed with orbit difference over overlaps of adjacent orbit arcs. Moreover, the orbit of the GEO satellite has been evaluated by Satellite Laser Ranging (SLR) data from both domestic and foreign SLR sites for the first time. The residual RMS of POD using C-Band observation is better than 0·1 m, and the orbit difference over overlaps of adjacent orbit arcs is better than 3 m. In addition, the residual RMS in line-of-sight for a SLR site in China are better than 1 m, while the RMS for the Yarragadee site in Australia is about 3·4 m. It has been shown that the GEO satellite orbit accords very well with the C-Band observation. Also, the distribution of CAPS stations affects the orbit precision. All sites in CAPS are now located in China with low and medium latitudes. The residual RMS of the SLR site in the southern hemisphere is larger than that of the site in China.
In order to more restrict the transverse orbit error, a new method named “differenced ranges between slave stations by transfer”, similar to Very Long Baseline Interferometry (VLBI) observation, has been developed in the Chinese Area Positioning System (CAPS). This method has the number of baselines added, the baseline length increased and the data volume enlarged. In this article, the principle of “differenced ranges between slave stations by transfer” has been described in detail, with the clock offset between slave stations and system error which affects the precision of the differenced ranges observation being discussed. Using this method, the differenced observation of the SINOSAT-1 satellite with C-band between slave stations from 6 to 13 June 2005 was conducted. Then a comparison was made between the accuracy of orbit determination and orbit prediction. A conclusion can be drawn that the combination of pseudo-range receiving the own-station-disseminated signal and the differenced range observation between slave-slave stations has a higher orbit determination and prediction accuracy than using only the former.
Although ascarid nematodes are important parasites of wild animals of public health concern, few species of ascarids from wild animals have been studied at the molecular level so far. Here, the classification and phylogenetic relationships of roundworms from 21 species of captive wild animals have been studied by sequencing and analysis of parts of the ribosomal 18S and 28S genes and the mitochondrial (mt) 12S gene. Phylogenetic relationships were inferred by 3 methods (NJ/MP/ML) based on the data of single gene sequences and concatenated sequences. Homology analysis indicated that the 18S sequences were conserved among roundworms from all 21 species and that 28S showed interspecies variability. Divergence levels displayed in 12S suggested that 12S appears to be either intra- or interspecifically variable. Evolutionary trees indicated that the ascarids split into 2 families, 4 genera and 7 species, with high bootstrap support for each clade. Combined trees suggested that Baylisascaris ailuri is more closely related to B. transfuga than to B. schroederi. This study provides useful molecular markers for the classification, phylogenetic analysis and epidemiological investigation of roundworms from wild animals.
The Chinese Area Positioning System (CAPS) is a regional satellite navigation system; its space segment consists of some Geostationary Earth Orbit (GEO) satellites and 2∼3 Inclined Geo-Synchronous Orbit (IGSO) satellites. Only a few satellites are needed to provide good area coverage and hence it is an ideal space segment for a regional navigation system. A time transfer mode is used to transmit navigation signals, so no high-precision atomic clocks are required onboard the satellites; all of the transferred navigation signals are generated by the same atomic clock at the master control station on the ground. By using virtual clock technology, the time of emission of signals from the ground control station is transformed to the time of transfer of signals at the phase centre of the satellite antenna; thus the impact of ephemeris errors of satellite on positioning accuracy is greatly decreased, enabling the CAPS to have the capability of wide area augmentation. A novel technology of orbit determination, called Paired Observation Combination for Both Stations (POCBS), proposed by the National Time Service Centre, is used in CAPS. The generation and measurement of ranging signals for the orbit survey are carried out in the ground station and the instrument errors are corrected in real-time. The determination of the clock offset is completely independent of the determination of satellite orbit, so the error of the clock offset has no impact on orbit determination. Therefore, a very high precision of satellite orbits, better than 4·2 cm (1 drms) can be obtained by the stations under regional distribution.
The Przewalski's gazelle (Procapra przewalskii) is critically endangered and has experienced significant decline in population numbers in the past, and now survives in four isolated populations: the Bird Island, Hudong-Ketu, Yuanzhe and Shadao-Gahai populations. To understand better the effect of habitat fragmentation and geographical isolation on gene flow and genetic variation, and uncover genetic units for conservation, we examined the hypervariable region (420 bp) of the mitochondrial DNA control region of 29 Przewalski's gazelles from four localities distributed throughout their present geographical range. Phylogenetic analysis consistently revealed four distinct mtDNA lineages within Przewalski's gazelle, with each lineage restricted to a single geographical location. The study revealed a marked divergence of lineages from the Bird Island population relative to other populations, which corresponds to the geographical association. The nucleotide diversity within populations was very low (less than 0.004). The value of Nm was less than 0.3 individuals per generation, indicating low gene flow between populations. It was suggested that the Yuanzhe, Hudong-Ketu and Shadao-Gahai populations be managed as a conservation unit because of their genetic and geographical closeness.
The partial mitochondrial 12S rRNA and 16S rRNA gene sequences (440 bp and 590 bp or so, respectively were determined of the Przewalski's gazelle Procapra przewalskii, Mongolian gazelle P. gutturosa, Tibetan gazelle P. picticaudata, goitered gazelle Gazella gutturosa, saiga Saiga tatarica, Tibetan antelope Pantholops hodgsoni, and thar Hemitragus jemlahicus. The average sequence divergence for all the species studied when both rRNA genes were combined was 8.4% (±0.7%), and the divergence values ranged from 0.5% to 13.3%. The average sequence divergence values for 16S rRNA gene and for 12S rRNA gene were 9.9% (±1.1%) and 6.3% (±1.1%), respectively. The sequence divergences among species of Procapra for 16S rRNA gene and for 12S rRNA gene were 1.4%(±0.5%) and 1.1% (±0.6%), respectively. Our phylogenetic analysis revealed the monophyly of the genus Procapra and that Przewalski's gazelle is more closely related to the Mongolian gazelle than to the Tibetan gazelle. We also found that the genus Procapra is closely related to Antilopini. We argued that the critically endangered Przewalski's gazelle should be treated as a species, not a subspecies of the Tibetan gazelle, which clearly warrants more attention from conservationists.
The performance of III-V nitride-based microelectronic and optoelectronic devices relates directly to the micro structure of these materials. Selective lateral overgrowth has been exploited to produce GaN heteroepitaxial films with low defect density . Si is a promising substrate due to its low cost, large size, and the potential for the intergration of GaN-based optoelectronic devices with Si-based electronics. It is also possible to produce high-quality GaN material for devices using lateral overgrowth on a Si substrate . At present, only limited information on the defect structure in GaN heteroepitaxial films grown by selective lateral growth is available, especially those grown on Si substrate. Recent work  on GaN pyramids grown on (111) Si substrates by this method has shown that in the center, or core, of the GaN pyramid (at and above the window area) dislocations thread through the pyramid nearly perpendicular to the substrate surface and the dislocation density is quite high.
The possible dislocations and slip systems in the wurtzite structure are the same as in hcp structure . The Burgers vectors of these dislocations are . The dislocations can lie on either the (0001) basal plane or prism planes. The dislocations lie on pyramidal planes. TEM studies have revealed that there are predominately three types of dislocations in a wurtzite GaN epilayer which has not been grown by selective overgrowth (e. g. [2, 3]). The majority of the dislocations are threading dislocations with Burgers vector which appear randomly in the epilayer, they result from the growth errors during the growth process. The other two types of dislocation are halflpops with a  or Burgers vector. The  dislocation half-loop lies on the prism plane and the dislocation half-loop lies on the (0001) basal plane which usually appears near the epilayer/substrate interface.