Phonon signatures for polaron formation in an anharmonic semiconductor.

Mechanistic studies on lead halide perovskites (LHPs) in recent years have suggested charge carrier screening as partially responsible for long carrier diffusion lengths and lifetimes that are key to superior optoelectronic properties. These findings have led to the ferroelectric large polaron proposal, which attributes efficient charge carrier screening to the extended ordering of dipoles from symmetry-breaking unit cells that undergo local structural distortion and break inversion symmetry. It remains an open question whether this proposal applies in general to semiconductors with LHP-like anharmonic and dynamically disordered phonons. Here, we study electron-phonon coupling in Bi2O2Se, a semiconductor which bears resemblance to LHPs in ionic bonding, spin-orbit coupling, band transport with long carrier diffusion lengths and lifetimes, and phonon disorder as revealed by temperature-dependent Raman spectroscopy. Using coherent phonon spectroscopy, we show the strong coupling of an anharmonic phonon mode at 1.50 THz to photo-excited charge carriers, while the Raman excitation of this mode is symmetry-forbidden in the ground-state. Density functional theory calculations show that this mode, originating from the A1g phonon of out-of-plane Bi/Se motion, gains oscillator strength from symmetry-lowering in polaron formation. Specifically, lattice distortion upon ultrafast charge localization results in extended ordering of symmetry-breaking unit cells and a planar polaron wavefunction, namely a two-dimensional polaron in a three-dimensional lattice. This study provides experimental and theoretical insights into charge interaction with anharmonic phonons in Bi2O2Se and suggests ferroelectric polaron formation may be a general principle for efficient charge carrier screening and for defect-tolerant semiconductors.

The association between endometrial polyps and insulin resistance from the expression of PI3K and AKT proteins perspective.

BACKGROUND: Insulin resistance (IR) induces hyperinsulinemia, which activates downstream signaling pathways such as the phosphatidylinositol-3-kinase/protein kinase B (PI3K/AKT) pathway, ultimately leading to abnormal proliferation and apoptosis of endometrial cells. This is thought to be a key pathogenic mechanism underlying the development of endometrial polyps (EP). This study aims to investigate the relationship between IR and the development of EP, the expression levels of downstream signaling molecules, including PI3K and AKT, and related laboratory parameters were examined. METHODS: A total of 100 patients who visited the gynecology outpatient clinic of Zhongda Hospital affiliated with Southeast University from May 2021 to March 2023 and were diagnosed with abnormal endometrial echoes by vaginal ultrasound and underwent hysteroscopic diagnostic curettage were enrolled in this study. General data and relevant hematological indicators were compared, and intraoperative specimens were obtained for pathological examination. Possible factors influencing the development of endometrial polyps were analyzed using Pearson correlation analysis and logistic regression analysis. RESULTS: In terms of body mass index, waist circumference, fasting insulin, insulin resistance index, serum total testosterone, and free testosterone index, women of childbearing age in the endometrial polyp group had higher values than those in the non-polyp group, while sex hormone-binding globulin in the endometrial polyp group was lower than that in the non-polyp group, and the differences were statistically significant (P < 0.05). The expression scores and mRNA expression levels of PI3K and AKT proteins were higher in the EP group than in the non-EP group (p < 0.05). Pearson correlation analysis showed a positive correlation between HOMA-IR and the expression scores of PI3K and AKT proteins (p < 0.01). CONCLUSIONS: Insulin resistance and abnormal activation of the phosphatidylinositol 3-kinase/protein kinase B signaling pathway may be potential pathogenic mechanisms for the development of endometrial polyps.

Decoding ultrafast polarization responses in lead halide perovskites by the two-dimensional optical Kerr effect.

The ultrafast polarization response to incident light and ensuing exciton/carrier generation are essential to outstanding optoelectronic properties of lead halide perovskites (LHPs). A large number of mechanistic studies in the LHP field to date have focused on contributions to polarizability from organic cations and the highly polarizable inorganic lattice. For a comprehensive understanding of the ultrafast polarization response, we must additionally account for the nearly instantaneous hyperpolarizability response to the propagating light field itself. While light propagation is pivotal to optoelectronics and photonics, little is known about this in LHPs in the vicinity of the bandgap where stimulated emission, polariton condensation, superfluorescence, and photon recycling may take place. Here we develop two-dimensional optical Kerr effect (2D-OKE) spectroscopy to energetically dissect broadband light propagation and dispersive nonlinear polarization responses in LHPs. In contrast to earlier interpretations, the below-bandgap OKE responses in both hybrid CH3NH3PbBr3 and all-inorganic CsPbBr3 perovskites are found to originate from strong hyperpolarizability and highly anisotropic dispersions. In both materials, the nonlinear mixing of anisotropically propagating light fields results in convoluted oscillatory polarization dynamics. Based on a four-wave mixing model, we quantitatively derive dispersion anisotropies, reproduce 2D-OKE frequency correlations, and establish polarization-dressed light propagation in single-crystal LHPs. Moreover, our findings highlight the importance of distinguishing the often-neglected anisotropic light propagation from underlying coherent quasiparticle responses in various forms of ultrafast spectroscopy.

Comparative effects of different metals on the Japanese medaka embryos and larvae.

Rapid evaluation of the toxicity of metals using fish embryo acute toxicity is facilitative to ecological risk assessment of aquatic organisms. However, this approach has seldom been utilized for the comparative study on the effects of different metals to fish. In this study, acute and sub-chronic tests were used to compare the toxicity of Se(IV) and Cd in the embryos and larvae of Japanese medaka (Oryzias latipes). The embryos with different levels of dechorionation and/or pre-exposure were also exposed to Se(IV) and Cd at various concentrations. The results showed that the LC50-144 h of Cd was 1.3-5.2 folds higher than that of Se(IV) for the embryos. In contrast, LC50-96 h of Se(IV) were 200-400 folds higher than that of Cd for the larvae. Meanwhile, dechorionated embryos were more sensitive to both Se and Cd than the intact embryos. At elevated concentrations, both Se and Cd caused mortality and deformity in the embryos and larvae. In addition, pre-exposure to Cd at the embryonic stages enhanced the resistance to Cd in the larvae. However, pre-exposure to Se(IV) at the embryonic stages did not affect the toxicity of Se(IV) to the larvae. This study has distinguished the nuance differences in effects between Se(IV) and Cd after acute and sub-chronic exposures with/without chorion. The approach might have a potential in the comparative toxicology of metals (or other pollutants) and in the assessment of their risks to aquatic ecosystems.

Nanographene with a Nitrogen-Doped Cavity.

Nitrogen-doped cavities are pervasive in graphenic materials, and represent key sites for catalytic and electrochemical activity. However, their structures are generally heterogeneous. In this study, we present the synthesis of a well-defined molecular cutout of graphene featuring N-doped cavity. The graphitization of a macrocyclic pyridinic precursor was achieved through photochemical cyclodehydrochlorination. In comparison to its counterpart with pyridinic nitrogen at the edges, the pyridinic nitrogen atoms in this nanographene cavity exhibit significantly reduced basicity and selective binding to Ag+ ion. Analysis of the protonation and coordination equilibria revealed that the tri-N-doped cavity binds three protons, but only one Ag+ ion. These distinct protonation and coordination behaviors clearly illustrate the space confinement effect imparted by the cavities.

CircXRN2 suppresses tumor progression driven by histone lactylation through activating the Hippo pathway in human bladder cancer.

BACKGROUND: Bladder cancer (BCa) is the fourth most common malignant tumor with a poor prognosis worldwide. Further exploration and research are needed to unmask the underlying roles and molecular mechanisms of circular RNAs. In the current study, our findings showed that circXRN2 suppresses tumor progression driven by histone lactylation by activating the Hippo pathway in human bladder cancer. METHODS: RNA immunoprecipitation (RIP) followed by circRNA sequencing confirmed circXRN2 as the research object. Overexpression of circXRN2 and knockdown of TAZ/YAP further verified the biological functions in T24 and TCCSUP cells. RIP, immunoprecipitation and coimmunoprecipitation were used to elucidate the interaction between circXRN2 and LATS1. A Seahorse metabolic analyzer was used to determine the glycolytic rate. Cleavage under targets and Tagmentation (CUT&Tag) and chromatin immunoprecipitation (ChIP) were employed to ensure the regulatory roles of H3K18 lactylation in the transcriptional activity of LCN2. RESULTS: CircXRN2 is aberrantly downregulated in bladder cancer tissues and cell lines. CircXRN2 inhibits the proliferation and migration of tumor cells both in vitro and in vivo. In addition, circXRN2 serves as a negative regulator of glycolysis and lactate production. Mechanistically, circXRN2 prevents LATS1 from SPOP-mediated degradation by binding to the SPOP degron and then activates the Hippo signaling pathway to exert various biological functions. The circXRN2-Hippo pathway regulatory axis further modulates tumor progression by inhibiting H3K18 lactylation and LCN2 expression in human bladder cancer. CONCLUSIONS: CircXRN2 suppresses tumor progression driven by H3K18 lactylation by activating the Hippo signaling pathway in human bladder cancer. Our results indicated novel therapeutic targets and provided promising strategies for clinical intervention in human bladder cancer.

Automatic optimization of miniaturized bound states in the continuum cavity.

Bound states in the continuum (BICs) provide, what we believe to be, a novel and efficient way for light trapping. However, using BICs to confine the light into a three-dimensional compact volume remains a challenging task, since the energy leakage at the lateral boundaries dominates the cavity loss when its footprint shrinks to considerably small, and hence, sophisticated boundary designs turn out to be inevitable. Conventional design methods fail in solving the lateral boundary problem because a large number of degree-of-freedoms (DOFs) are involved. Here, we propose a fully automatic optimization method to promote the performance of lateral confinement for a miniaturized BIC cavity. Briefly, we combine a random parameter adjustment process with a convolutional neural network (CNN), to automatically predict the optimal boundary design in the parameter space that contains a number of DOFs. As a result, the quality factor that is accounted for lateral leakage increases from 4.32 × 104 in the baseline design to 6.32 × 105 in the optimized design. This work confirms the effectiveness of using CNNs for photonic optimization and will motivate the development of compact optical cavities for on-chip lasers, OLEDs, and sensor arrays.

Genome-wide re-sequencing data reveals the genetic diversity and population structure of Wenchang chicken in China.

Wenchang (WC) chicken, the only indigenous chicken breed listed in Chinese genetic resources in Hainan province, is well known for its excellent meat quality and is sold all over southeast Asia. In recent years, the number of WC has decreased sharply with considerable variability in the quality at market. To explore the genetic diversity and population structure of WC chickens, the whole-genome data of 235 WC individuals from three conservation farms were obtained using the Illumina 150 bp paired-end platform and used in conjunction with the sequencing data from 123 individuals from other chicken breeds (including eight Chinese indigenous chicken breeds and three foreign or commercial breeds) downloaded from a public database. A total of 12 111 532 SNPs were identified, of which 11 541 878 SNPs were identified in WC. The results of gene enrichment analyses revealed that the SNPs harbored in WC genomes are mainly related to environmental adaptation, disease resistance and meat quality traits. Genetic diversity statistics, quantified by expected heterozygosity, observed heterozygosity, linkage disequilibrium, nucleotide diversity and fixation statistics, indicated that WC displays high genetic diversity compared with other Chinese indigenous chicken breeds. Genetic structure analyses showed that each population displayed great differentiation between WC and the other breeds, indicating the uniqueness of WC. In conclusion, the results of our study provide the first genomic overview of genetic variants, genetic diversity and population structure of WC from three conservation farms. This information will be valuable for the future breeding and conservation of WC and other surveyed populations.

Reconstruction of complicated spinal tuberculosis with long-segment fibula transplantation: a case report.

BACKGROUND: Treating complex cases of spinal tuberculosis (STB) that involve multiple vertebral bodies and cause destruction of the spinal structure, kyphotic deformity, and acute nerve injury can be challenging. This report describes the course of treatment and 5-year follow-up of a complex case of multisegmental STB. CASE PRESENTATION: This report describes a case of tuberculosis affecting the vertebrae extending from thoracic 12 to lumbar 5 in a 60-year-old woman who suffered sudden paralysis in both lower extremities. The patient underwent emergency posterior paraspinal abscess clearance, laminectomy with spinal decompression. Partial correction of the kyphotic deformity via long-segment fixation from the T9 vertebral body to the ilium in a one-stage posterior procedure. The patient's neurological status was diagnosed as grade E on the American Spinal Injury Association (ASIA) scale after the one-stage operation. Following standardized 4-combination anti-tuberculosis drug therapy for three months in postoperative patients, the patient underwent two-stage transabdominal anterior abscess removal, partial debridement of the lesion and bilateral fibula graft support. One year after the two-stage operation, the patient's visual analog scale (VAS) score of back pain was 1 point, and the patient's erythrocyte sedimentation rate (ESR) and C-reactive protein (CRP) levels returned to normal. Five years after the second-stage operation, the Oswestry disability index (ODI) of patient quality of life was 14 points. There was a 4-degree change in the Cobb angle over five years. During the five-year follow-up period, the grafted fibula did not experience any subsidence. CONCLUSION: For patients with spinal tuberculosis and acute paralysis, it is essential to relieve spinal cord compression as soon as possible to recover spinal cord function. For lesions that cannot be debrided entirely, although limited debridement combined with anti-tuberculosis drug therapy has the risk of sinus formation and tuberculosis recurrence, it is much safer than the risk of thorough debridement surgery. In this case, an unconventional long-segment fibula graft, pelvis-vertebral support, was an effective reconstruction method.

Effectiveness and safety analysis of titanium mesh grafting versus bone grafting in the treatment of spinal Tuberculosis: a systematic review and meta-analysis.

BACKGROUND: To systematically assess the safety and effectiveness of titanium mesh grafting compared with bone grafting in the treatment of spinal tuberculosis. METHODS: Electronic databases, including PubMed, Embase, Web of Science, and Cochrane Library, were searched from their inception until April 2023. The outcome indicators for patients treated with titanium mesh grafting or bone grafting for spinal tuberculosis include surgical duration, intraoperative blood loss, graft fusion time, American Spinal Injury Association (ASIA) Spinal Cord Injury Grade E assessment, VAS score, lumbar pain score, post-graft kyphotic angle, and postoperative complications. The Newcastle-Ottawa Scale (NOS) and the Grading of Recommendations Assessment, Development, and Evaluation (GRADE) approach were used for quality assessment and evidence grading of clinical studies. Funnel plots and Begg's test were employed for bias assessment. RESULTS: A total of 8 studies were finally included, comprising 523 patients, with 267 cases of titanium mesh fixation and 256 cases of bone grafting. The meta-analysis showed no significant statistical differences in surgical duration (Weighted Mean Difference (WMD) = -7.20, 95% Confidence Interval (CI): -28.06 to 13.67, P = 0.499), intraoperative blood loss (WMD = 16.22, 95% CI: -40.62 to 73.06, P = 0.576), graft fusion time (WMD = 0.97, 95% CI: -0.88 to 2.81, P = 0.304), ASIA Spinal Cord Injury Grade E assessment (Relative Risk (RR) = 1.03, 95% CI: 0.97 to 1.09, P = 0.346), and overall complications (RR = 0.87, 95% CI: 0.49 to 1.55, P = 0.643). Differences in VAS score, ODI lumbar pain score, and post-graft kyphotic angle between the titanium mesh grafting group and the bone grafting group were not significant within the 95% CI range. The rate of postoperative implant subsidence was slightly lower in bone grafting than in titanium mesh grafting (RR = 9.30, 95% CI: 1.05 to 82.22, P = 0.045). CONCLUSIONS: Both bone grafting and titanium mesh grafting are effective and safe for the surgery, with no significant statistical differences in the results. Considering the limitations of the present study, large-scale randomized controlled trials are warranted to further verify the reliability of this finding.

[Content analysis and quality evaluation of main active components and mineral elements of Cynomorium songaricum in different habitats].

To clarify the content characteristics of the main active components and mineral elements of Cynomorium songaricum under different habitat conditions, and further explore the relationship between the quality of C. songaricum and habitats, this study took C. songaricum from 25 different habitats in China as the research object, and measured the contents of 8 main active components and 12 mineral elements separately. Diversity analysis, correlation analysis, principal component analysis and cluster analysis were carried out. The results showed that the genetic diversity of total flavonoids, ursolic acid, ether extract, potassium(K), phosphorus(P) and zinc(Zn) in C. songaricum was high. The coefficient of variation of crude polysaccharide, ether extract, gallic acid, protocatechuic aldehyde, catechin, epicatechin, calcium(Ca), sodium(Na), magnesium(Mg), sulfur(S), iron(Fe), manganese(Mn), selenium(Se) and nickel(Ni) were all over 36%, indicating that the quality of C. songaricum was significantly affected by habitats. There were strong synergistic and weak antagonistic effects among the contents of the 8 active components, and complex antagonistic and synergistic effects among the contents of the 12 mineral elements. Principal component analysis revealed that crude polysaccharide, ursolic acid, catechin, epicatechin and total flavonoids could be used as the characteristic components to evaluate the quality of C. songaricum, and Na, copper(Cu), Mn and Ni were the characteristic elements to evaluate the quality of C. songaricum. In cluster ana-lysis, the second group with the main active components as cluster center had better quality in terms of the content of active substances, and the second group with the mineral elements as cluster center had higher utilization potential in the exploitation of mineral elements. This study could provide a basis for resource evaluation and breeding of excellent varieties of C. songaricum in different habitats, and provide a reference for cultivation and identification of C. songaricum.

Photoluminescence Anisotropy in Eutectic Crystals of Polynuclear Lanthanide Complexes and Silver Clusters.

Anisotropy is an intrinsic property of crystalline materials. However, the photoluminescence anisotropy in eutectic crystals of organometallic complexes has remained unexplored. Herein, the eutectic of polynuclear lanthanide complexes and Ag clusters was prepared, and the crystal shows significant photoluminescence anisotropy. The polarization anisotropy of emission δ and degree of excitation polarization P are 2.62 and 0.53, respectively. The rare excitation polarization properties have been proved to be related to the regular arrangement of electric transition dipole moments of luminescent molecules in the crystal. Our design provides a reference for developing new photoluminescence anisotropy materials and expanding their applications.

Analytical theory of finite-size photonic crystal slabs near the band edge.

An analytical three-dimensional (3D) coupled-wave theory (CWT) for the finite-size photonic crystal slabs (PhCs) has been presented to depict the discretized modes at band-edges residing inside and outside the continuum. Specifically, we derive the CWT equations of slow-varying envelop function of dominant Bloch waves. By combining the trial solutions that are composed of a basis of bulk states with appropriate boundary conditions (B.C.), we analytically solve the equations and discuss the far-field patterns, asymptotic behavior and flatband effect of the finite-size modes, respectively. The proposed method presents a clear picture in physics for the origins of finite-size modes and provides an efficient and comprehensive tool for designing and optimizing PhC devices such as PCSELs.

All-pass phase shifting enabled by symmetric topological unidirectional guided resonances.

All-pass phase shifting (APS), which involves a wave propagating at a constant, unitary amplitude but with pure phase variation, is extremely desired in many optoelectronic applications. In this work, we propose a method of realizing APS by out-of-plane excitation of a topologically enabled unidirectional guided resonance (UGR), which resides in a photonic crystal slab with P or C2z symmetries. Briefly, the symmetries and unidirectional features reduce the number of ports to one that simultaneously adds or drops energy. As a result, the phase independently shifts by varying the frequency but the amplitude remains as unitary under plane wave excitation. Theory and simulations confirm our findings. A paradox that the background contribution deviates from Fabry-Perot resonance is clarified from a multi-resonances picture.

One-step detection of alpha fetal protein based on gold microelectrode through square wave voltammetry.

The detection of tumor markers in blood samples with high efficiency and sensitivity is in urgent need. In this work, a one-step quantitative detection assay for alpha fetal protein (AFP) based on gold microelectrode which is denoted as AuµE through square wave voltammetry using [Fe(CN)6]3-/4- as mediator was developed. As the biorecognition element of the assay, sulfydryl-modified AFP aptamer could be directly conjugated onto the surface of the AuµE, which could capture AFP with high specificity, and this attachment would cause the decrease of the capacitive current of the cyclic voltammetry due to the reduction of the active area of the electrodes. Under the optimized conditions, the AuµE aptasensor exhibited a linear detection range for AFP from 10-10 to 10-7 g/mL (S = 7.6 nA/dec, R2 = 0.991), and the detection limit is 2.5 × 10-11 g/mL. The AuµEs aptasensor demonstrates good selectivity against other types of proteins and small molecules, and has good reproducibility. The real blood samples were used for detection of AFP using the AuµEs aptasensor, the results agree well with those provided by the hospital through electrochemiluminescence method. Herein, the proposed one-step detection assay has a great application potential in point-of-care clinical diagnostics.

Solvated Electrons in Solids-Ferroelectric Large Polarons in Lead Halide Perovskites.

Solvation plays a pivotal role in chemistry and biology. A solid-state analogy of solvation is polaron formation, but the magnitude of Coulomb screening is typically an order of magnitude weaker than that of solvation in aqueous solutions. Here, we describe a new class of polarons, the ferroelectric large polaron, proposed initially by Miyata and Zhu in 2018 (Miyata, K.; Zhu, X.-Y. Ferroelectric Large Polarons. Nat. Mater. 2018, 17 (5), 379-381). This type of polaron allows efficient Coulomb screening of an electron or hole by extended ordering of dipoles from symmetry-broken unit cells. The local ordering is reflected in the ferroelectric-like THz dielectric responses of lead halide perovskites (LHPs) and may be partially responsible for their exceptional optoelectronic performances. Despite the likely absence of long-range ferroelectricity in LHPs, a charge carrier may be localized to and/or induce the formation of nanoscale domain boundaries of locally ordered dipoles. Based on the known planar nature of energetically favorable domain boundaries in ferroelectric materials, we propose that a ferroelectric polaron localizes to planar boundaries of transient polar nanodomains. This proposal is supported by dynamic simulations showing sheet-like transient electron or hole wave functions in LHPs. Thus, the Belgian-waffle-shaped ferroelectric polaron in the three-dimensional LHP crystal structure is a large polaron in two dimensions and a small polaron in the perpendicular direction. The ferroelectric large polaron may form in other crystalline solids characterized by dynamic symmetry breaking and polar fluctuations. We suggest that the ability to form ferroelectric large polarons can be a general principle for the efficient screening of charge carriers from scattering with other charge carriers, with charged defects and with longitudinal optical phonons, thus contributing to enhanced optoelectronic properties.

Comprehensive analysis of pyroptosis regulators and tumor immune microenvironment in clear cell renal cell carcinoma.

BACKGROUND: Increasing evidence has indicated that pyroptosis could regulate the tumor immune microenvironment (TIME) to affect the tumor development. As a highly immunogenic tumor, clear cell renal cell carcinoma (ccRCC) can benefit from immunotherapy, but related research on pyroptosis in the TIME of ccRCC is still deficient. METHODS: Available data derived from TCGA and GEO databases were analyzed to identify the different expression profiles of pyroptosis in ccRCC and normal tissues, and the correlation of pyroptosis regulators with TIME was evaluated in ccRCC. RESULTS: According to consensus clustering analysis, two differential expression levels of subtypes were identified to affect patient prognosis, and were related to histological tumor stage and grade. Immune cells were calculated by the CIBERSORT algorithm. Higher infiltrated levels of B cells naive, T cells CD4 memory resting, NK cells resting, monocytes, macrophages were observed in Cluster 1, while higher infiltrated levels of CD8+ T cells, T follicular helper cells, and Tregs were observed in Cluster 2. Gene set enrichment analysis indicated that Cluster 2 was enriched in multiple immune-related pathways, including the JAK-STAT signaling pathway. Moreover, overexpression of eight immune checkpoints was related to ccRCC development, especially in Cluster 2. As four potentially key pyroptosis regulators, AIM2, CASP5, NOD2, and GZMB were confirmed to be upregulated in ccRCC by RT-qPCR analysis and further verified by the HPA database. Further pan-cancer analysis suggested that these four pyroptosis regulators were differentially expressed and related to the TIME in multiple cancers. CONCLUSION: The present study provided a comprehensive view of pyroptosis regulators in the TIME of ccRCC, which may provide potential value for immunotherapy.

Sodium butyrate inhibits migration and induces AMPK-mTOR pathway-dependent autophagy and ROS-mediated apoptosis via the miR-139-5p/Bmi-1 axis in human bladder cancer cells.

Bladder cancer is one of the most frequently occurring malignant tumors in the urinary system. Sodium butyrate (NaB) is a histone deacetylase inhibitor and exerts remarkable antitumor effects in various cancer cells. MicroRNAs (miRNAs) and autophagy play crucial roles in cancer occurrence and development. In the present study, we evaluated the anticancer effects, including cell migration inhibition and the apoptotic effects of NaB in human bladder cancer cells. Furthermore, we found that NaB inhibited migration and induced AMPK/mTOR pathway-activated autophagy and reactive oxygen species (ROS) overproduction via the miR-139-5p/Bmi-1 axis. In addition, we found that ROS overproduction contributed to NaB-induced caspase-dependent apoptosis and autophagy. The interplay between autophagy and apoptosis in NaB treatment was clarified. Our findings provide a further understanding of EMT reversion, apoptosis and autophagy induced by antitumor drugs and a novel perspective and alternative strategy for bladder cancer chemotherapy.

Device architectures for low voltage and ultrafast graphene integrated phase modulators.

The atomic layer thin geometry and semi-metallic band diagram of graphene can be utilized for significantly improving the performance matrix of integrated photonic devices. Its semiconductor-like behavior of Fermi-level tunability allows graphene to serve as an active layer for electro-optic modulation. As a low loss metal layer, graphene can be placed much closer to active layer for low voltage operation. In this work, we investigate hybrid device architectures utilizing semiconductor and metallic properties of the graphene for ultrafast and energy efficient electro-optic phase modulators on semiconductor and dielectric platforms. (1) Directly contacted graphene-silicon heterojunctions. Without oxide layer, the carrier density of graphene can be modulated by the directly contact to silicon layer, while silicon intrinsic region stays mostly depleted. With doped silicon as electrodes, carrier can be quickly injected and depleted from the active region in graphene. The ultrafast carrier transit time and small RC constant promise ultrafast modulation speed (3dB bandwidth of 67 GHz) with an estimated Vπ·L of 1.19 V·mm. (2) Graphene integrated lithium niobite modulator. As a transparent electrode, graphene can be placed close to integrated lithium niobate waveguide for improving coupling coefficient between optical mode profile and electric field with minimal additional loss (4.6 dB/cm). Numerical simulation indicates 2.5× improvement of electro-optic field overlap coefficient, with estimated V π of 0.2 V.

The ultrafast Kerr effect in anisotropic and dispersive media.

The ultrafast optical Kerr effect (OKE) is widely used to investigate the structural dynamics and interactions of liquids, solutions, and solids by observing their intrinsic nonlinear temporal responses through nearly collinear four-wave mixing. Non-degenerate mixing schemes allow for background free detection and can provide information on the interplay between a material's internal degrees of freedom. Here, we show a source of temporal dynamics in the OKE signal that is not reflective of the internal degrees of freedom but arises from a group index and momentum mismatch. It is observed in two-color experiments on condensed media with sizable spectral dispersion, a common property near an optical resonance. In particular, birefringence in crystalline solids is able to entirely change the character of the OKE signal via the off-diagonal tensor elements of the nonlinear susceptibility. We develop a detailed description of the phase-mismatched ultrafast OKE and show how to extract quantitative information on the spectrally resolved birefringence and group index from time-resolved experiments in one and two dimensions.