Optimizing focus: switchable modes and sub-diffraction spots in inverse circular Airy beams.

We report an experimental investigation into the tight-focusing characteristics of linearly polarized inverse circular Airy beams (ICABs). Our study reveals that tightly focused ICABs exhibit Bessel-like, needle-like, or dual foci profiles depending on whether the main ring's radius is smaller than, equal to, or larger than the critical radius. The emergence of the dual foci structure is attributed to the constrained entrance aperture of the microscope objective (MO). In contrast to traditional Gaussian beams (GBs), ICABs demonstrate remarkable advantages in terms of focal spot size. Notably, we observe a focal spot with a size of 245 nm, representing a 26.4% reduction compared to the diffraction limit. These unique properties open up promising avenues for potential applications in optical multi-plane particle trapping, conveying, and super-resolution optical imaging.

Controlling the Goos-Hänchen shift in a double prism structure using three-level Raman gain medium.

We propose a scheme to control the Goos-Hänchen (GH) shift of TE and TM reflected light beams in a double-prism structure, where a three-level Raman gain medium is filling the gap between the two prisms. We find that it is possible to control the GH shift in this structure by externally adjusting the optical properties of the Raman gain atomic medium while the gap width between the two prisms is fixed. Inspired by recent successful implementation of the double-prism configuration with an air gap to measure the GH shift, we expected that our proposal to control the GH shift can be achieved experimentally and used in different potential applications of the GH shift.

Experimental observation and manipulation of optical tornado waves.

We report experimental realization and manipulation of optical tornado waves (ToWs). By controlling the self-focusing length, total angular momentum, and foci deviation of ToWs, the propagation properties of optical ToWs, especially their angular velocity, can be manipulated. Controlling the accumulated rotation angle of the main intensity lobes of ToWs from 0° through 1100° is experimentally demonstrated, and their angular velocity is predicted to be the highest around the foci overlap situation. Our experimental results are in good agreement with numerical results.

Influence of spatial dispersion on phase and lateral shifts near the reflection dip in the Kretschmann-Raether structure.

The influence of spatial dispersion of metals on phase and Goos-Hänchen (GH) shifts near the reflection dip has been investigated in the Kretschmann-Raether configuration, within the hydrodynamic model framework. We have derived an analytical expression of the reflection coefficient and discussed the optical properties when the nonlocality of metals based on the phenomenological model and Kretchmann's theory is taken into account. Our results show that nonlocality has a significant impact for large wavevectors and causes a shift of the critical point corresponding to the total absorption. Furthermore, these changes also lead to diverse changes in the optical properties including amplitude, phase and GH shift close to the conditions of excitation for the surface plasmon. Our work provides a solid foundation for the understanding of nonlocality in multilayered plasmonic structures and paves the way for future experiments.

Light chaotic dynamics in the transformation from curved to flat surfaces.

Light propagation on a two-dimensional curved surface embedded in a three-dimensional space has attracted increasing attention as an analog model of four-dimensional curved spacetime in the laboratory. Despite recent developments in modern cosmology on the dynamics and evolution of the universe, investigation of nonlinear dynamics of light on non-Euclidean geometry is still scarce, with fundamental questions, such as the effect of curvature on deterministic chaos, challenging to address. Here, we study classical and wave chaotic dynamics on a family of surfaces of revolution by considering its equivalent conformally transformed flat billiard, with nonuniform distribution of the refractive index. We prove rigorously that these two systems share the same dynamics. By exploring the Poincaré surface of section, the Lyapunov exponent, and the statistics of eigenmodes and eigenfrequency spectrum in the transformed inhomogeneous table billiard, we find that the degree of chaos is fully controlled by a single, curvature-related geometric parameter of the curved surface. A simple interpretation of our findings in transformed billiards, the "fictitious force," allows us to extend our prediction to other classes of curved surfaces. This powerful analogy between two a priori unrelated systems not only brings forward an approach to control the degree of chaos, but also provides potentialities for further studies and applications in various fields, such as billiards design, optical fibers, or laser microcavities.

Precise measurement of trapping and manipulation properties of focused fractional vortex beams.

Fractional vortex beams (FVBs) were believed to be hard to rotate microparticles at a half-integer topological charge due to the unique radial opening (low-intensity gap) in their intensity ring. However, recent research discovered more symmetric intensity structures with less intensity inhomogeneity of practical FVBs at the focal plane. Here, we experimentally demonstrated the manipulation of trapped microparticles and precisely measured their rotation periods at the focal plane of practical FVBs by using a high-speed camera. We verified that the measured orbital angular momentum (OAM) derived from the collective microparticle rotation is roughly proportional to the fractional OAM of practical FVBs. Furthermore, we also experimentally obtained the trapped microparticles' power spectra under the illumination of FVBs, from which we achieved the average trap stiffness to evaluate the two-dimensional trapping strength of the practical focused FVB intensity ring. Our results provide a new insight and an efficient tool on finely trapping and rotating microparticles and bio-cells by using fractional vortex beams.

LINC00536 promotes hepatocellular carcinoma progression via the miR-203b-5p/VEGFA axis.

LncRNAs exert comprehensive effects in regulating the initiation and deterioration of hepatocellular carcinoma (HCC). However, the specific expression profiles and functional mechanisms of LINC00536 in HCC need to be disclosed. The study is intended to clarify the leverage of LINC00536 in HCC and investigate the potential mechanisms for the regulatory role of LINC00536 in the progression of HCC. In our study, LINC00536 was overexpressed in tumor samples of HCC patients and was related to poor prognosis. LINC00536 knockdown impaired cell viability, proliferation, migration, and invasion. LINC00536 can directly bind with miR-203b-5p, trimming the miR-203b-5p expression levels. VEGFA designates as a target of miR-203b-5p. Rescue research indicated that the miR-203b-5p inhibition or VEGFA overexpression could reverse the impaired cell phenotypes induced by LINC00536 knockdown. The in vivo experiments upheld the LINC00536/miR-203b-5p/VEGFA axis in HCC. Conclusively, LINC00536 could promote HCC deterioration via tuning the miR-203b-5p/VEGFA axis. This research may provide theoretical evidence for LINC00536 to get a gratifying therapeutic target for HCC.

Impact of Nonlocality on Group Delay and Reflective Behavior Near Surface Plasmon Resonances in Otto Structure.

In this work, we study the effects of nonlocality on the optical response near surface plasmon resonance of the Otto structure, and such nonlocality is considered in the hydrodynamic model. Through analyzing the dispersion relations and optical response predicted by the Drude's and hydrodynamic model in the system, we find that the nonlocal effect is sensitive to the large propagation wavevector, and there exists a critical incident angle and thickness. The critical point moves to the smaller value when the nonlocal effect is taken into account. Before this point, the absorption of the reflected light pulse enhances; however, the situation reverses after this point. In the region between the two different critical points in the frequency scan calculated from local and nonlocal theories, the group delay of the reflected light pulse shows opposite behaviors. These results are explained in terms of the pole and zero phenomenological model in complex frequency plane. Our work may contribute to the fundamental understanding of light-matter interactions at the nanoscale and in the design of optical devices.

Genetic Architecture Underlying Nascent Speciation-The Evolution of Eurasian Pigs under Domestication.

Speciation is a process whereby the evolution of reproductive barriers leads to isolated species. Although many studies have addressed large-effect genetic footprints in the advanced stages of speciation, the genetics of reproductive isolation in nascent stage of speciation remains unclear. Here, we show that pig domestication offers an interesting model for studying the early stages of speciation in great details. Pig breeds have not evolved the large X-effect of hybrid incompatibility commonly observed between "good species." Instead, deleterious epistatic interactions among multiple autosomal loci are common. These weak Dobzhansky-Muller incompatibilities confer partial hybrid inviability with sex biases in crosses between European and East Asian domestic pigs. The genomic incompatibility is enriched in pathways for angiogenesis, androgen receptor signaling and immunity, with an observation of many highly differentiated cis-regulatory variants. Our study suggests that partial hybrid inviability caused by pervasive but weak interactions among autosomal loci may be a hallmark of nascent speciation in mammals.

Self-healing property of focused circular Airy beams.

We investigate the self-healing property of focused circular Airy beams (FCAB), and this property is associated with the transverse Poynting vector (energy flow) for a better interpretation. We both experimentally and numerically show the effect of the obstruction's position, size and shape on the self-healing property of FCAB. It is found that FCAB will heal if the obstruction is placed at the area between the two foci of FCAB, and it has the least influence on the FCAB when the obstruction is placed near the lens' rear focal plane, whereas FCAB cannot heal if the obstruction is out of the area between two foci. Our experimental results are in good agreement with numerical results.

Hanbury Brown and Twiss effect in spatiotemporal domain.

Hanbury Brown and Twiss (HBT) effect has broad applications in optics and other branches of physics, and traditionally this effect is considered in pure spatial or temporal domain. Here we investigate the spatiotemporal HBT effect, extending this phenomenon from spatial or temporal to spatiotemporal domain. By assuming the Gaussian statistics of partially coherent spatiotemporal pulsed sources, we find the generalized analytical results for spatiotemporal HBT effect in the compact form, with the help of the matrix-optics method, which can consider the HBT effect in spatial and temporal domain simultaneously. Furthermore, for Gaussian Schell-model pulsed beams (GSMPBs) used as a spatiotemporal correlated source, we have obtained the generalized expression to calculate spatiotemporal HBT effect, which is useful for up to three-dimensional cases in any second-order linear dispersive medium. By taking a simple two-dimensional case and using air as an example of a linear dispersive medium, we numerically illustrate the properties of the spatiotemporal HBT effect by adjusting the spatial and temporal parameters of the GSMPB source, and reveal the influence of both the spatial and temporal parameters on the spatiotemporal HBT effect. This work paves the path towards the detailed study of HBT effect for a source containing spatiotemporal information with Gaussian statistics.

Residual concentrations and ecological risks of neonicotinoid insecticides in the soils of tomato and cucumber greenhouses in Shouguang, Shandong Province, East China.

Neonicotinoid insecticides (NNIs) are the most widely used insecticides in China and worldwide. Continuous use of NNIs can lead to their accumulation in soil, causing potential ecological risks due to their relatively long half-life. We used liquid chromatography-tandem mass spectrometry (LC-MS/MS) to investigate the residual levels of nine neonicotinoids in greenhouse soils in Shouguang, East China, at different soil depths and with different crops (tomato and cucumber) after varying periods of cultivation. Seven neonicotinoids were detected in the soils of the tomato greenhouses and six were detected in the soils of the cucumber greenhouses, with total concentrations ranging from 0.731 to 11.383 µg kg-1 and 0.363 to 19.224 µg kg-1, respectively. In all samples, the neonicotinoid residues in the soils cultivated for 8-9 years were lower than in those cultivated for 2 years and 14-17 years. In the tomato greenhouse soils, the residual levels of NNIs were highest in the topsoil, with progressively lower concentrations found with depth. Under cucumber cultivation, the NNI residue levels were also highest in the topsoil but there was little difference between the middle and lower soil layers. Total organic carbon (TOC) decreased with soil depth while pH showed the opposite trend, showing a significant negative correlation in both types of soils (tomato soils ρ = -0.900, p = .001; cucumber soils ρ = -0.883, p = .002). Furthermore, TOC was significantly positively correlated, and pH was negatively correlated, with total NNI concentrations in both types of soils (TOC: tomato soils ρ = 0.800, p = .010; cucumber soils ρ = 0.881, p = .004; pH: tomato soils ρ = -0.850, p = .004; cucumber soils ρ = -0.643, p = .086). The results of an ecological risk analysis showed that acetamiprid represents a particularly high toxicity risk in these soils. Based on our analysis, NNI residues in the soils of tomato greenhouses and their associated ecological risks deserve more attention than those of cucumber greenhouse soils.

Effects of pesticide residues on bacterial community diversity and structure in typical greenhouse soils with increasing cultivation years in Northern China.

The understanding of soil microbiome is important for sustainable cultivation, especially under greenhouse conditions. Here, we investigated the changes in soil pesticide residues and microbial diversity and community structure at different cultivation years under a greenhouse system. The 9-to-14 years sites were found to have the least diversity/rich microbial population as compared to sites under 8 years and over 16 years, as analyzed with alpha diversity index. In total, 42 bacterial phyla were identified across soils with different pesticide residues and cultivation ages. Proteobacteria, Acidobacteria, and Bacteroidetes represented the dominant phyla, that accounted for 34.2-43.4%, 9.7-19.3% and 9.2-16.5% of the total population, respectively. Our data prove that certain pesticides contribute to variation in soil microbial community and that soil bacteria respond differently to cultivation years under greenhouse conditions. Thus, this study provides an insight into microbial community structure changes by pesticides under greenhouse systems and natural biodegradation may have an important part in pesticides soil decontamination.

[Impacts of one-off fertilization on nitrogen leaching and economic benefits for rice-rape rotation system]. / 一次性施肥技术对水稻-æ²¹èœè½®ä½œç³»ç»Ÿæ°®ç´ æ·‹å¤±ç‰¹å¾åŠç»æµŽæ•ˆç›Šçš„å½±å“.

One-off fertilization is a new technology of one-time applying base fertilizer near the rhizosphere during whole crop cultivation period. It has the advantages of simplifying fertilization manage-ment and reducing labor costs, but its impacts on environment, such as leaching characteristics need further analysis. We set five treatments in the typical rice-rape rotation system in the middle and lower reaches of the Yangtze River, including control treatment (CK), farmers' practice treatment (FP), optimal fertilizer treatment (OPT), one-off application of urea fertilizer treatment (UA) and one-off application of controlled release urea treatment (CRF). Using in situ leaching monitoring method, nitrogen (N) leaching characteristics at 90 cm depth of soil in rice-rape rotation system under different treatments were obtained, the impacts of one-off fertilization on N lea-ching were evaluated and its economic benefits were comprehensively analyzed. The results showed that the main forms of N in leachate were different for rape and rice. In the rape season, NO3--N was the major component of leachate, while for rice season NO3--N and NH4+-N were equally important. In the whole rotation period, the inorganic N leaching mainly occurred in the rice season, and compared with FP, OPT and UA, the total amount of inorganic N leached by CRF were significantly reduced by 33.7%, 20.8%, and 20.7%, respectively. However, the effects of different fertilization treatments on N leaching in rape season were not significantly different. Under the same N application rates, compared with OPT, UA ensured the stable yield of rape and rice and significantly increased the NAE in rape season by 15.1%, but failed to improve the NAE in rice season. There was no significant difference between OPT and CRF in rice yield and NAE, but rape yield and NAE of CRF significantly increased by 10.7% and 18.9%, respectively. From the economic front, compared with OPT, UA and CRFincreased rapeseed income by 3660 and 3048 yuan·hm-2, and rice income by 3162 and 2220 yuan·hm-2. Therefore, considering the effects of various fertilizer treatments on N leaching, crop yield, and economic benefits, one-off base fertilization application of controlled release fertilizer technology could ensure stable or increase crop yields, and improve farmers' income, while significantly reduce the inorganic N leaching loss. Such technology is recommended for future rice-rape rotation cultivation.

Vortex strength and beam propagation factor of fractional vortex beams.

Fractional vortex beams (FVBs) with non-integer topological charges attract much attention due to unique features of propagations, but different viewpoints still exist on the change of their total vortex strength. Here we have experimentally demonstrated the distribution and number of vortices contained in FVBs at the Fraunhofer diffraction region. We have verified that the jumps of total vortex strength for FVBs happen only when non-integer topological charge is before and after (but very close to) any even integer number that originates from two different mechanisms for generation and movement of vortices on focal plane. Meanwhile, we have also measured the beam propagation factor (BPF) of such FVBs and have found that their BPF values almost increase linearly in the x component (along the initial edge dislocation) and oscillate increasingly in the y component (vertical to the initial edge dislocation). Our experimental results are in good agreement with numerical results.

P68 RNA helicase promotes invasion of glioma cells through negatively regulating DUSP5.

Gliomas are the most common central nervous system tumors. They show malignant characteristics indicating rapid proliferation and a high invasive capacity and are associated with a poor prognosis. In our previous study, p68 was overexpressed in glioma cells and correlated with both the degree of glioma differentiation and poor overall survival. Downregulating p68 significantly suppressed proliferation in glioma cells. Moreover, we found that the p68 gene promoted glioma cell growth by activating the nuclear factor-κB signaling pathway by a downstream molecular mechanism that remains incompletely understood. In this study, we found that dual specificity phosphatase 5 (DUSP5) is a downstream target of p68, using microarray analysis, and that p68 negatively regulates DUSP5. Upregulating DUSP5 in stably expressing cell lines (U87 and LN-229) suppressed proliferation, invasion, and migration in glioma cells in vitro, consistent with the downregulation of p68. Furthermore, upregulating DUSP5 inhibited ERK phosphorylation, whereas downregulating DUSP5 rescued the level of ERK phosphorylation, indicating that DUSP5 might negatively regulate ERK signaling. Additionally, we show that DUSP5 levels were lower in high-grade glioma than in low-grade glioma. These results suggest that the p68-induced negative regulation of DUSP5 promoted invasion by glioma cells and mediated the activation of the ERK signaling pathway.

[Emission of NH3 and N2O from Spinach Field Treated with Different Fertilizers].

Agricultural management techniques such as fertilizer or manure application have substantial influence on NH3 and N2O emissions and, by understanding this influence, management strategies can be developed to reduce them. An experiment was conducted in a greenhouse at Hunan Agricultural University during 2012 to 2013, to investigate effects of different fertilizers on NH3 and N2O emissions. The treatments included control without fertilizer (CK), swine composting fertilizer (SC), stored swine manure fertilizer (SS), and chemical fertilizer (FC). The fluxes of NH3 and N2O were collected by venting method and static-chamber method, respectively. The results showed that during the spinach growth season, compared with FC, loss of both NH3 and N2O for SC were reduced by 52.9% and 95.12%, respectively(P<0.01). However, loss of NH3 for SS increased by 24.8%, and loss of N2O reduced by 48.8% compared with FC. Loss rate of NH3 were SS (10.97%) > FC (4.19%) > SC(2.74%), and emission coefficient for N2O were FC(4.50%) > SC(2.21%) > SS(0.60%). Yield and utilization of nitrogen for SC were reduced by 19.61% and 13.20% compared with FC, respectively, but not significantly; and significantly reduced by 27.9% and 40.0% compared with SS, respectively. Loss of gases (NH3 and N2O) for SC were 1.83%, which was the lowest, while utilization of nitrogen for SC was 13.20%, similar with FC. Greenhouse temperature was not the critical factor during the spinach planting in winter, but soil water was. Therefore, optimizing manure management could reduce ammonia volatilization and N2O emission loss without decreasing vegetables production, and the present data indicated that SC would be optimal for better yields with reduced ammonia volatilization and N2O emission loss.

Parabolic-Gaussian Schell-model sources and their propagations.

In this work, a new class of partially coherent Schell-type sources is introduced by modifying its degree of coherence, which is a product of a parabolic function and a Gaussian function. Such sources are confirmed to be physically genuine and may be called parabolic-Gaussian Schell-model (PGSM) sources. The propagating expression of the cross-spectral density function of such PGSM sources is derived in a general linear optical system. In particular, the propagation properties of such PGSM beams in both free space and lens systems are discussed. The results show that such PGSM sources can produce dark-hollow intensity profiles in the regions of free space very near as well as far away from the source plane, or in the focal region of the lens system.

Zitterbewegung near new Dirac points in graphene superlattices.

New Dirac points may appear when periodic potentials are applied to graphene, and there are many interesting effects near them. Here we investigate the Zitterbewegung effect of fermions described by a Gaussian wave packet in graphene superlattice near these points. The Zitterbewegung near different Dirac points has similar characteristics, while fermions near new ones have different group velocities in both x- and y-direction, which causes the different properties of the Zitterbewegung near them. We also investigate the Zitterbewegung effect influenced by multi Dirac points, and get the evolution with changing potential. Our results suggest that graphene superlattice may provide an appropriate system to study the Zitterbewegung effect near new Dirac points experimentally.