Comparison of treatment performance and microbial community evolution of typical dye wastewater by different combined processes.

The degradation of typical dye wastewater is a focus of research in the printing and dyeing industry. In this study, a combined micro-electrolysis and microbial treatment method was established to treat refractory dye wastewater, and the pivotal factors in the microbial treatment were optimized. In the series and coupled modes, the removal rates of chroma reached 98.75% and 92.50%, and the removal rates of chemical oxygen demand (COD) reached 96.17% and 82.29%, respectively. The high-throughput sequencing results showed that the microbial communities in the microbial system varied at different treatment stages. From the culture stage to the domestication stage, the dominant phylum was Proteobacteria; however, the community abundance of microorganisms decreased. A combination of micro-electrolysis and biological methods can alter the characteristics of the microbial community, increase the number of dominant phyla, and increase the abundance of microorganisms. The degradation effect of the series mode and the overall strengthening effect of micro-electrolysis on the microorganisms were better than those of the coupled mode. In actual wastewater, the maximum removal rates of chroma, COD, total nitrogen (TN), ammonia nitrogen (NH3-N), and total phosphorus (TP) are 97.50%, 98.90%, 94.35%, 93.95%, and 91.17%, respectively. Three-dimensional fluorescence spectrum analysis showed that microbial processes could significantly degrade fluorescent components in wastewater, and methanogenic active enzymes in anaerobic processes could continue to react. The combined process can realize the efficient treatment of toxic dye wastewater by reducing the toxicity of wastewater and efficiently degrading organic matter, which has important guiding significance for the treatment of refractory dye wastewater.

Nonlinear evolution of modulational instability under the interaction of Kerr nonlinearity with pure higher, even-order dispersion.

We investigate the nonlinear evolutions of modulation instability (MI) under the interaction of Kerr nonlinearity with pure higher, even-order dispersion (HEOD) by using the truncating method of three-wave mixing. For any HEOD, we find the phase-plane topological structure of the MI changes in three frequency regions whose ranges depend on the order of HEOD. And we present the novel types of nonlinear evolutions of the MI, which do not exist in the case of quadratic dispersion. Taking the pure-sextic dispersion as an example, the theoretical predictions of the MI evolutions are confirmed by numerically solving the modified nonlinear Schrödinger equation. Our results not only further deepen the understanding of MI, but also provide a universal guideline for experimental investigation of nonlinear waves, such as breather solitons or rogue waves excitation, in nonlinear Kerr media with pure HEOD.

Symmetry-breaking enabled topological phase transitions in spin-orbit optics.

The topological phase transitions (TPT) of light refers to a topological evolution from one type of spin-orbit interaction to another, which has been recently found in beam scattering at optical interfaces and propagation in uniaxial crystals. In this work, the focusing of off-axis and partially masked circular-polarization Gaussian beams are investigated by using of a full-wave theory. Moreover, two different types of spin-orbit interactions (i.e., spin-dependent vortex generation and photonic spin-Hall effect) in the focusing system are unified from the perspective of TPT. It is demonstrated that as the off-axis distance or the masked area increases, a TPT phenomenon in the focused optical field takes place, evolving from the spin-dependent vortex generation to the spin-Hall shift of the beam centroids. The intrinsic mechanism is attributed to the cylindrical symmetry-breaking of the system. This symmetry-breaking induced TPT based on the method of vortex mode decomposition is further examined. The main difference between the TPT phenomenon observed here and that trigged by oblique incidence at optical interfaces or oblique propagation in uniaxial crystals is also uncovered. Our findings provide fruitful insights for understanding the spin-orbit interactions in optics, providing an opportunity for unifying the TPT phenomena in various spin-orbit photonics systems.

Role of beam parameters in the spin-orbit interactions of light.

We employ a full-wave theory to systematically investigate two types of spin-orbit interactions and their topological phase transitions for various light beams (e.g., Laguerre-Gaussian, Bessel, and Bessel-Gaussian beams) at optical interfaces, and explore the influence of beam parameters on the spin-Hall shift. It is demonstrated that at small-angle incidence, the beam profile and spin-Hall shift are significantly affected by the beam parameters (e.g., waist radius, radial index, azimuthal index, and cone angle), whereas at large-angle incidence, only the azimuthal index has a salient influence on them. We further find that the Bessel beam and the Gaussian-modulated ones (i.e., Laguerre-Gaussian and Bessel-Gaussian beams) have similar topological phase transition phenomena but different shifts. Quantitative dependences of beam parameters, such as waist radius, radial index, azimuthal index, and cone angle, on the shift are also presented. Our findings offer alternative degrees of freedom in controlling the topological phase transitions of light, and suggest a valuable insight for exploring the applications of SOIs of diverse light fields.

Enhancement of the conversion efficiency of optical spin-orbit interactions in PT symmetric systems.

The optical spin-orbit interaction (SOI) caused by momentum-dependent Pancharatnam-Berry phase (PB) provides new opportunities in the development of spin-optical devices, but the relatively low conversion efficiency limits its application. Here, through rigorous full-wave analyses on it in a parity-time (PT) symmetric system with thickness less than a wavelength, we find that the conversion efficiency of the SOI can be enhanced in both transmission and reflection in a wide range of incidence angles. When the parameters of the PT symmetric system meet the requirement of coherent perfect absorbers-laser mode, the effective anisotropy between the TM and TE components (e.g., a difference of their Fresnel coefficients) within the beam will be amplified dramatically, which results in significantly enhanced conversion efficiency of SOIs (up to 106). These findings offer an effective way to modulate the SOIs with an ultra-thin PT symmetric system, and may exhibit applications in spin-orbit optical devices.

Raman-induced frequency shift of pure quartic solitons in optical fiber with quartic dispersion.

We investigate the impact of Raman scattering on pure quartic solitons (PQSs) in an optical fiber with quartic dispersion. An analytical expression of the Raman-induced frequency shift (RIFS) of a PQS is obtained by using the variational approach with the Gaussian function ansatz. We find the RIFS of a PQS is inversely proportional to the sixth power of pulse width, when the fiber is short enough. The RIFS of a PQS is more sensitive to the pulse width, compared with that of a conventional soliton which is inversely proportional to the fourth power of pulse width. The theoretical predictions show good agreement with numerical results. In addition, we also discuss the RIFS of the other three typical pulses with the same peak power and pulse width as the PQS. These results provide a thorough understanding of the role of higher-order nonlinear effects on the propagation dynamics of PQSs.

Spin-orbit interactions in a nonlinear medium due to a nonlinear-induced geometric phase.

In general, a spin-polarized light beam cannot couple its spin angular momentum (SAM) with intrinsic orbital angular momentum (IOAM) without spin reversal. Here we find that nonlinear media can give the spin-polarized photon an IOAM, as they travel in the media due to the nonlinear susceptibility along the transmission direction, which does not require spin reversal. To characterize this SAM-to-IOAM conversion process, we establish an evolution ray equation for photons carrying IOAM by reference to the Schrödinger equation. We further reveal the inherent physics of such a phenomenon from a full-wave perspective and find that the vortex generation originates from the nonlinear-induced geometric phase.

Vortex generation in the spin-orbit interaction of a light beam propagating inside a uniaxial medium: origin and efficiency.

It has been known that an optical vortex with a topological charge ±2 can be generated as a circularly polarized (CP) light beam propagates in a bulk uniaxial crystal, but its physical origin remains obscure which also hinders its practical applications. Here, through a rigorous full-wave analyses on the problem, we show that, as a CP beam possessing a particular spin (handedness) propagates inside a uniaxial crystal, two beams with opposite spins can be generated caused by the unique spin-sensitive light-matter interactions in the anisotropic medium. Flipping the spin can offer the light beam an vortex phase with a topological charge of ±2 owing to the Pancharatnam-Berry mechanism, with efficiency dictated by the material properties of the uniaxial medium and the topological structure of the beam itself. With its physical origin fully uncovered, we finally discuss how to improve the efficiency of such effect, and compare the mechanisms of vortex generations in different systems. Our findings not only provide deeper understandings on such an intriguing effect, but also shed light on other spin-orbit-interaction-induced effects.

Large in-plane asymmetric spin angular shifts of a light beam near the critical angle.

The photonic spin Hall effect (SHE) manifests itself as the transverse and in-plane spin-dependent shifts of a light beam. Normally, the spin shifts are tiny due to the weak spin-orbit coupling. Therefore, it is very important and interesting to explore some effective methods for enhancing this phenomenon. In this Letter, we theoretically propose and experimentally verify a simple method for obtaining large and asymmetric in-plane spin angular shifts when an arbitrary linearly polarized beam reflects near the critical angle (for total internal reflection). The universal expressions of spatial and angular shifts are deduced. Remarkably, by modulating the incident and polarization angles, the left- and right-handed circularly polarized components can be distinguished directly.

Transitional Goos-Hänchen effect due to the topological phase transitions.

We examine the Goos-Hänchen (GH) effect for a Gaussian beam impinging on the surface of silicene whose topological phase transitions can be modulated by external electric field and/or irradiating circular polarized light. It is shown that both the spatial and angular shifts in GH effect present a sharp jump due to the topological phase transitions. The transitional GH effect can be attributed to transitional optical conductivity, which relates to Berry curvature and Chern numbers. These results can be extensively extended to other two-dimensional atomic crystals in graphene family. We believe that the transitional GH effect may offer a possible way to determine the Berry curvature, Chern numbers, and topological phase transition by a direct optical measurement.

Recent advances in the spin Hall effect of light.

The spin Hall effect (SHE) of light, as an analogue of the SHE in electronic systems, is a promising candidate for investigating the SHE in semiconductor spintronics/valleytronics, high-energy physics and condensed matter physics, owing to their similar topological nature in the spin-orbit interaction. The SHE of light exhibits unique potential for exploring the physical properties of nanostructures, such as determining the optical thickness, and the material properties of metallic and magnetic thin films and even atomically thin two-dimensional materials. More importantly, it opens a possible pathway for controlling the spin states of photons and developing next-generation photonic spin Hall devices as a fundamental constituent of the emerging spinoptics. In this review, based on the viewpoint of the geometric phase gradient, we give a detailed presentation of the recent advances in the SHE of light and its applications in precision metrology and future spin-based photonics.

Measurements of Pancharatnam-Berry phase in mode transformations on hybrid-order Poincaré sphere.

We report direct measurements of the Pancharatnam-Berry (PB) phase in mode transformations on a hybrid-order Poincaré sphere. This geometric phase arises when the vector vortex states undergo a cyclic transformation over a closed circuit on a hybrid-order Poincaré sphere. The measured PB phase is proportional to the solid angle of the closed circuit, as well as to the variation of the total angular momenta between north and south poles. More importantly, a zero PB phase has been demonstrated, despite the vector vortex states taken through a closed circuit on the hybrid-order Poincaré sphere. This interesting phenomenon can be explained as being due to the zero Berry curvature.

Precise identification of graphene layers at the air-prism interface via a pseudo-Brewster angle.

We propose a simple method for the precise identification of graphene layers at the air-prism interface via a pseudo-Brewster angle, where the horizontally polarized reflection is close to zero. We find that the pseudo-Brewster angle is sensitive to the variation of graphene layers where the pseudo-Brewster angle is approximately linearly increased about 0.5 deg as the layer numbers increased. Furthermore, the sensitivity of the pseudo-Brewster angle can be greatly enhanced and reaches 0.04 deg by eliminating the influence of the cross-polarization effect. Our scheme can provide a simple and effective method to identify the layer numbers of graphene.

Unveiling the photonic spin Hall effect with asymmetric spin-dependent splitting.

The photonic spin Hall effect (SHE) manifests itself as the spin-dependent splitting of light beam. Usually, it shows a symmetric spin-dependent splitting, i.e., the left- and right-handed circularly polarized components are equally separated in position and intensity for linear polarization incidence. In this paper, we theoretically propose an asymmetric spin-dependent splitting at an air-glass interface under the illumination of elliptical polarization beam and experimentally demonstrate it with the weak measurement method. The left- and right-handed circularly polarized components show expectedly unequal intensity distributions and unexpectedly different spin-dependent shifts. Remarkably, the asymmetric spin-dependent splitting can be modulated by adjusting the handedness of incident polarization. The inherent physics behind this interesting phenomenon is attributed to the additional spatial Imbert-Fedorov shift. These findings offer us potential methods for developing new spin-based nanophotonic applications.

Propagation model for vector beams generated by metasurfaces.

A propagation model of vector beams generated by metasurfaces based on vector diffraction theory is established theoretically and verified experimentally. Considering the Pancharatnam-Berry phase introduced by the metasurface, analytical forms of vector beams for arbitrary incident polarization and topological charge of metasurfaces are found in the Fresnel and Fraunhofer diffraction regions, respectively. The complex amplitude of the resultant vector beam can be described in terms of a confluent hypergeometric function, with an intensity profile that manifests concentric rings in the Fresnel region and a single ring in the Fraunhofer one. Fraunhofer diffraction provides a method to create vector beams with simultaneously high purity and modal power. Further experiments verify the theoretical results.

[Correlation of oxidative stress with sperm DNA integrity and semen parameters in infertile men with varicocele].

OBJECTIVE: To investigate the relationship of oxidative stress with DNA integrity and semen parameters in infertile men with varicocele (VC). METHODS: This prospective study included 98 infertile males with VC. According to the levels of reactive oxygen species (ROS) in the semen, we divided the patients into a high ROS group (n=44) and a low ROS group (n=54), determined the sperm DNA fragmentation index (DFI), motility and morphology, and analyzed their correlation with ROS in the two groups of patients. RESULTS: Compared with the patients of the low ROS group, those of the high ROS group showed a significantly higher DFI (27.38±8.10 vs 34.49±6.05, P=0.039) and a higher concentration of seminal leukocytes (ï¼»0.65±0.15ï¼½×106/ml vs ï¼»0.86±0.41ï¼½×106/ml, P=0.022), but lower sperm motility (ï¼»36.16±22.83ï¼½% vs ï¼»18.22±25.21ï¼½%, P=0.017), percentage of progressively motile sperm (ï¼»23.34±11.53ï¼½% vs ï¼»16.34±9.22ï¼½%, P=0.041), sperm curvilinear velocity (ï¼»27.03±6.21ï¼½ vs ï¼»20.62±4.38ï¼½ µm/s, P=0.013), and sperm linearity (ï¼»29.75±8.24ï¼½% vs ï¼»18.30±7.93ï¼½%, P=0.024). Spearman correlation analysis indicated that the ROS level was correlated positively with the concentration of seminal leukocytes (r=0.41, P<0.01) and DFI (r=0.21, P=0.006), but negatively with sperm curvilinear velocity (r=－0.24, P=0.017), linearity (r=－0.24, P=0.021), motility (r=－0.31, P=0.002), and the percentage of progressively motile sperm (r=－0.41, P=0.012). Additionally, the sperm DFI manifested a significant negative correlation with sperm motility (r=－0.29, P<0.01) and the percentage of progressively motile sperm (r=－0.34, P<0.01). CONCLUSIONS: The level of seminal ROS is positively correlated with the sperm DFI in infertile men with varicocele, and both the ROS level and DNA integrity are associated with semen parameters.

Observation of photonic spin Hall effect with phase singularity at dielectric metasurfaces.

Observation of photonic spin Hall effect (SHE) near the phase singularity at dielectric metasurfaces is presented. The structured metasurface works as a space-variant Pancharatnam-Berry phase element and produces a vortex beam with phase singularity. The dynamical vortex phase is introduced to eliminate or enhance the phase singularity, thus realizing the manipulation of spin-dependent Pancharatnam-Berry phase. The spin-orbit coupling near the singularity of the Pancharatnam-Berry phase leads to the observation of the photonic SHE which manifests itself as spin-dependent splitting. The underlying mechanism is significantly different from previously reported cases. It thereby provides an alternative way to manipulate the spin states of photons.

Photonic spin Hall effect in dielectric metasurfaces with rotational symmetry breaking.

Observation of photonic spin Hall effect (SHE) in dielectric metasurfaces whose local optical axes are spatially rotated is presented. The photonic SHE manifests itself as a spin-dependent splitting in momentum space due to the space-variant Pancharatnam-Berry phase. We show that no spin-dependent splitting occurs when keeping the rotational symmetry of local optical axes. However, the splitting can be observed when the rotational symmetry is broken. The spin-dependent splitting in position space can be observed in the far field due to the high transmission efficiency of dielectric metasurfaces. Moreover, it can be enhanced by increasing the rotation rate of local optical axes in the metasurfaces.

[Association of BCL9 expression with prostate cancer clinicopathological features and survival].

OBJECTIVE: B-cell lymphoma 9 (BCL9) as a co-activator for ß-catenin-mediated transcription is highly expressed in tumors. The aim of our study is to investigate the expression of BCL9, and its clinicopathological significance in prostate cancer (PCa). METHODS: Immunohistochemistry was conducted to analyze the expression of BCL9 in 98 PCa samples and 20 benign prostate hyperplasia (BPH) samples. The associations of BCL9 expression with clinicopathological features and prognosis in PCa patients were analyzed with various statistical methods, such as chi-square test, Kaplan-Meier method and log-rank test. RESULTS: The positive rate of BCL9 was 53.1% (52/98) in prostate cancer group, and 25.0% (5/20) in benign group (P=0.022). In addition, BCL9 expression in PCa tissues was significantly associated with Gleason score (P=0.016), and biochemical recurrence (P=0.020). Moreover, Kaplan-Meier survival analysis showed that the higher expression of BCL9 was correlated with shorter biochemical recurrence-free survival (P=0.037). However, BCL9 was not an independent prognostic predictor for biochemical recurrence-free survival in patients with PCa after the multivariate analysis was conducted (Hazard ratio =1.73, P=0.384). CONCLUSION: Our study demonstrates the up-regulation of BCL9 is associated with PCa's early diagnosis and malignant degree.

MicroRNA-224 inhibits progression of human prostate cancer by downregulating TRIB1.

Our previous microarray data showed that microRNA-224 (miR-224) was downregulated in human prostate cancer (PCa) tissues compared with adjacent benign tissues. However, the underlying mechanisms by which miR-224 is involved in PCa remain unclear. In this study, we identified TRIB1 as a target gene of miR-224. Forced expression of miR-224 suppressed PCa cell proliferation, invasion and migration, and promoted cell apoptosis by downregulating TRIB1. Moreover, the expression level of miR-224 in PCa tissues was negatively correlated with that of TRIB1. miR-224 downregulation was frequently found in PCa tissues with metastasis, higher PSA level and clinical stage, whereas TRIB1 upregulation was significantly associated with metastasis. Both miR-224 downregulation and TRIB1 upregulation were significantly associated with poor biochemical recurrence-free survival of patients with PCa. In conclusion, these findings reveal that the aberrant expression of miR-224 and TRIB1 may promote PCa progression and have potentials to serve as novel biomarkers for PCa prognosis.