Geometric Origin of Non-Bloch PT Symmetry Breaking.

The parity-time (PT) symmetry of a non-Hermitian Hamiltonian leads to real (complex) energy spectrum when the non-Hermiticity is below (above) a threshold. Recently, it has been demonstrated that the non-Hermitian skin effect generates a new type of PT symmetry, dubbed the non-Bloch PT symmetry, featuring unique properties such as high sensitivity to the boundary condition. Despite its relevance to a wide range of non-Hermitian lattice systems, a general theory is still lacking for this generic phenomenon even in one spatial dimension. Here, we uncover the geometric mechanism of non-Bloch PT symmetry and its breaking. We find that non-Bloch PT symmetry breaking occurs by the formation of cusps in the generalized Brillouin zone (GBZ). Based on this geometric understanding, we propose an exact formula that efficiently determines the breaking threshold. Moreover, we predict a new type of spectral singularities associated with the symmetry breaking, dubbed non-Bloch van Hove singularity, whose physical mechanism fundamentally differs from their Hermitian counterparts. This singularity is experimentally observable in linear responses.

Non-Hermitian Edge Burst.

We unveil an unexpected non-Hermitian phenomenon, dubbed edge burst, in non-Hermitian quantum dynamics. Specifically, in a class of non-Hermitian quantum walk in periodic lattices with open boundary condition, an exceptionally large portion of loss occurs at the system boundary. The physical origin of this edge burst is found to be an interplay between two unique non-Hermitian phenomena: non-Hermitian skin effect and imaginary gap closing. Furthermore, we establish a universal bulk-edge scaling relation underlying the non-Hermitian edge burst. Our predictions are experimentally accessible in various non-Hermitian systems including quantum-optical and cold-atom platforms.

Facile Preparation Method of TiO2/Activated Carbon for Photocatalytic Degradation of Methylene Blue.

The development of nanocomposite photocatalysts with high photocatalytic activity, cost-effectiveness, a simple preparation process, and scalability for practical applications is of great interest. In this study, nanocomposites of TiO2 Degussa P25 nanoparticles/activated carbon (TiO2/AC) were prepared at various mass ratios of (4:1), (3:2), (2:3), and (1:4) by a facile process involving manual mechanical pounding, ultrasonic-assisted mixing in an ethanol solution, paper filtration, and mild thermal annealing. The characterization methods included XRD, SEM-EDS, Raman, FTIR, XPS, and UV-Vis spectroscopies. The effects of TiO2/AC mass ratios on the structural, morphological, and photocatalytic properties were systematically studied in comparison with bare TiO2 and bare AC. TiO2 nanoparticles exhibited dominant anatase and minor rutile phases and a crystallite size of approximately 21 nm, while AC had XRD peaks of graphite and carbon and a crystallite size of 49 nm. The composites exhibited tight decoration of TiO2 nanoparticles on micron-/submicron AC particles, and uniform TiO2/AC composites were obtained, as evidenced by the uniform distribution of Ti, O, and C in an EDS mapping. Moreover, Raman spectra show the typical vibration modes of anatase TiO2 (e.g., E1g(1), B1g(1), Eg(3)) and carbon materials with D and G bands. The TiO2/AC with (4:1), (3:2), and (2:3) possessed higher reaction rate constants (k) in photocatalytic degradation of methylene blue (MB) than that of either TiO2 or AC. Among the investigated materials, TiO2/AC = 4:1 achieved the highest photocatalytic activity with a high k of 55.2 × 10-3 min-1 and an MB removal efficiency of 96.6% after 30 min of treatment under UV-Vis irradiation (120 mW/cm2). The enhanced photocatalytic activity for TiO2/AC is due to the synergistic effect of the high adsorption capability of AC and the high photocatalytic activity of TiO2. Furthermore, TiO2/AC promotes the separation of photoexcited electron/hole (e-/h+) pairs to reduce their recombination rate and thus enhance photocatalytic activity. The optimal TiO2/AC composite with a mass ratio of 4/1 is suggested for treating industrial or household wastewater with organic pollutants.

What is the optimal cutoff value of the axis-line-angle technique for evaluating trunk imbalance in coronal plane?

BACKGROUND CONTEXT: Accurately evaluating the extent of trunk imbalance in the coronal plane is significant for patients before and after treatment. We preliminarily practiced a new method, axis-line-angle technique (ALAT), for evaluating coronal trunk imbalance with excellent intra-observer and interobserver reliability. Radiologists and surgeons were encouraged to use this method in clinical practice. However, the optimal cutoff value of the ALAT for determination of the extent of coronal trunk imbalance has not been calculated up to now. PURPOSE: The purpose of this study was to identify the cutoff value of the ALAT that best predicts a positive measurement point to assess coronal balance or imbalance. STUDY DESIGN/SETTING: A retrospective study at a university affiliated hospital was carried out. PATIENT SAMPLE: A total of 130 patients with C7-central sacral vertical line (CSVL) >0 mm and aged 10-18 years were recruited in this study from September 2013 to December 2014. OUTCOME MEASURES: Data were analyzed to determine the optimal cutoff value of the ALAT measurement. METHODS: The C7-CSVL and ALAT measurements were conducted respectively twice on plain film within a 2-week interval by two radiologists. The optimal cutoff value of the ALAT was analyzed via receiver operating characteristic (ROC) curve. Comparison variables were performed with chi-square test between the C7-CSVL and ALAT measurements for evaluating trunk imbalance. Kappa agreement coefficient method was used to test the intra-observer and interobserver agreement of C7-CSVL and ALAT. RESULTS: The ROC curve area for the ALAT was 0.82 (95% confidence interval: 0.753-0.894, p<.001). The maximum Youden index was 0.51, and the corresponding cutoff point was 2.59°. No statistical difference was found between the C7-CSVL and ALAT measurements for evaluating trunk imbalance (p>.05). Intra-observer agreement values for the C7-CSVL measurements by observers 1 and 2 were 0.79 and 0.91 (p<.001), respectively, whereas intra-observer agreement values for the ALAT measurements were both 0.89 by observers 1 and 2 (p<.001). The interobserver agreement values for the first and second measurements with the C7-CSVL were 0.78 and 0.85 (p<.001), respectively, whereas the interobserver agreement values for the first and second measurements with the ALAT were 0.91 and 0.88 (p<.001), respectively. CONCLUSIONS: The newly developed ALAT provided an acceptable optimal cutoff value for evaluating trunk imbalance in the coronal plane with a high level of intra-observer and interobserver agreement, which suggests that the ALAT is suitable for clinical use.

Decreased expression of the mitochondrial metabolic enzyme aconitase (ACO2) is associated with poor prognosis in gastric cancer.

Alterations in energy metabolism play a major role in cancer development. Aconitase (ACO2) is an essential enzyme located in the mitochondria and catalyzes the interconversion of citrate and isocitrate in the tricarboxylic acid cycle. Recent studies suggest that the expression of ACO2 may be altered in certain types of cancer. The purpose of this study was to examine ACO2 expression in clinical tumor specimens from patients with gastric cancer and to evaluate the clinical relevance of ACO2 expression in gastric cancer. A total of 456 paraffin-embedded gastric cancer tissues and 30 pairs of freshly frozen tissues were used in this study. Real-time quantitative reverse transcription polymerase chain reaction, western blotting, and immunohistochemical staining were performed to measure ACO2 expression in tumor tissues and matched adjacent non-tumorous tissues. The results showed that the expression of ACO2 was significantly down-regulated in gastric cancer tissues compared with matched adjacent nontumorous tissues and was associated with clinical stage (p = 0.001), T classification (p = 0.027), N classification (p = 0.012), M classification (p = 0.002), and pathological differentiation states (p = 0.036). Patients with lower ACO2 expression had a shorter survival time than those with higher ACO2 expression. Univariate and multivariate analyses indicated that ACO2 expression functions as an independent prognostic factor (p < 0.001). Our data suggested that ACO2 could play an important role in gastric cancer and may potentially serve as a prognostic biomarker.

[Generation and preliminary functional study of a CD133-2-harboring L929 cell line].

AIM: To generate an engineered L929 cell line harboring human CD133-2 and perform the functional study of the gene-modified cell line. METHODS: The human CD133-2 gene was obtained by PCR from a cDNA library of foetus liver. After digested with Hind III and BamH I, the PCR product was cloned into pIRES2-EGFP vector. The recombinant plasmid CD133-2/pIRES2-EGFP was transfected into L929 cell line using lipofectamine, followed by G418 selection. RT-PCR, Western blot and flow cytometry (FCM) were used to detect the expression of CD133-2. MTT was used to analyze the effect of the CD133-2/L929 cells on proliferation of T cells. FCM was performed to monitor T cell activation by detecting T cell surface markers of CD4CD25 and CD8CD25 after T cells were cocultured with the CD133-2/L929 cells in the presence of an anti-CD3 mAb. RESULTS: A stable cell line constitutively expressing the human CD133-2 was established successfully. In the presence of the anti-CD3 mAb, CD133-2/L929 cells caused inhibition of T cell proliferation and down-regulation of the activation markers of CD4CD25 and CD8CD25 on T cells. CONCLUSION: The engineered CD133-2/L929 cell line provides a gain-of-function cell model for further understanding the biological role of CD133-2.

[Preparation of two mouse anti-human PD-1 monoclonal antibodies and identification of their biological characteristics].

AIM: To prepare mouse anti-human PD-1 monoclonal antibodies (mAbs) and identify their biological characteristics. METHODS: The BALB/c mice were immunized with the transfected cell line PD-1/L929. The cells were fused with Sp2/0 using monoclonal antibody techniques and the positive clones were screened by FCS with PD-1/L929. The secreted anti-PD-1 mAbs were identified through rapid isotyping analysis, karyotype analysis, Western blot, competitive inhibition test, indirect immunofluorescence assay, and tumor cell lines detection. RESULTS: Two mouse anti-human PD-1 hybridomas were obtained and their secreted mAbs were named (1F2 and 5F10). Their biological characteristics suggested that they could recognize a protein with approximate molecular weight 55 000 on PD-1/L929 cell lines and different epitopes. 1F2 could recognize PD-1 molecules expressed on SKHep-1 and 7721 while 5F10 could recognize Raji cells. CONCLUSION: Two mouse anti-human PD-1 hybridoma cell lines and their secreted monoclonal antibodies have been successfully obtained and identified.

[Effects of MSC on cell cycle, phenotype and cytokine secretion of T cells activated by PHA].

AIM: To study the effect of human bone marrow derived mesenchymal stem cell (MSC) on T cell cycle and activation, and to investigate the inhibitory effect of MSC on T cell proliferation and the underlying mechanism. METHODS: Human bone marrow derived MSC were isolated by gradient centrifugation. then in vitro MSC were cultured, expanded,and were used in test after third passage. FCM analysis and ELISA were used to investigate the effects of MSC on the early activation marker expression of T cells, cell cycle and cytokine secretion. RESULTS: T cells stimulated by PHA in the presence of MSC were arrested at G0/G1 phase. The expression of the early activation marker CD25 and CD69 of T cells was inhibited in the presence of MSC both in CD4(+) and CD8(+) T cell subpopulation. MSC caused a sharp decrease of cytokine secretion in IL-2 and IFN-gamma. CONCLUSION: Human bone marrow derived MSC can suppress the activation and proliferation of T cells by altering T cell cycle.

[Effects of costimulatory pathway OX40/OX40L on the pathogenesis of allergic asthma in mice].

OBJECTIVE: Allergic asthma is thought to be mediated by CD4+ T lymphocytes producing the Th2-associated cytokines, which play a critical role in the development of the airway hyper-responsiveness and the eosinophilic inflammatory response. The costimulatory pathway CD28/B7 has been shown to play an important role in CD4+ T cell activation in allergic asthma. This study was conducted to evaluate the role of another costimulatory pathway OX40/OX40 ligand (L) in the pathogenesis of allergic asthma in BALB/c mice. METHODS: An allergic asthma model in BALB/c mice was established. Thirty-six BALB/c mice were randomly divided into three groups with 12 in each. Mice in treatment group (group B) were treated with neutralizing anti-OX40L monoclonal antibody (mAb, 300 microg per mouse) during the sensitization period. Mice in two control groups, asthma model group (group A) and IgG antibody group (group C) were treated with normal saline (NS) and control IgG respectively instead of anti-OX40L mAb. Bronchoalveolar lavage fluid (BALF) was collected from the mice of each group for counting the total number of white blood cells (including neutrophil granulocyte, lymphocyte, monocyte and eosinophil granulocyte) and the proportions of these cells. The levels of IL-4 and INF-gamma in BALF were measured by ELISA. Lungs were removed for morphological examination after HE and PAS staining, and expression of OX40 in lungs was evaluated by immunohistochemical method. RESULTS: (1) The count of total number of white blood cells in BALF (x10(6)/ml) was lower in group B than that of group A and group C (26.6 +/- 4.6 vs. 36.8 +/- 5.2 and 34.3 +/- 6.9, respectively), the difference between the treatment group (group B) and two control groups (groups A and C) was significant; The proportions of eosinophils and lymphocytes in the BALF (%) were lower in group B than those in group A and group C (eosinophils 15.1 +/- 2.6 vs. 20.0 +/- 4.1 and 19.9 +/- 3.9, respectively; lymphocytes 7.0 +/- 0.9 vs. 8.9 +/- 1.6 and 8.6 +/- 1.8, respectively), the difference between the treatment group and two control groups was significant. (2) The IL-4 level in BALF (pg/ml) was lower in group B than that in group A and group C (672 +/- 58 vs. 809.57 +/- 106.00 and 784 +/- 58, respectively), but the INF-gamma levels in BALF (pg/ml) were higher than those in group A and group C (0.86 +/- 0.09 vs. 0.69 +/- 0.15 and 0.67 +/- 0.13 respectively), and all the differences were statistically significant. (3) The expression of OX40 in the lungs of mice in group B were at a lower level than that of group A and group C, and the morphological changes of asthma were ameliorated in the mice of the treatment group. The signs of mice in treatment group were obviously ameliorated as compared to the two control groups. CONCLUSION: Blocking the costimulatory pathway by administering the neutralizing anti-OX40L mAb during the sensitization period of allergic asthma model could balance the Th1/Th2 responses, inhibit lung inflammation and ameliorate the signs of mice model of asthma.

Recombinant human B7-H4 expressed in Escherichia coli inhibits T lymphocyte proliferation and IL-2 secretion in vitro.

AIM: To explore the biofunctions of human B7-H4 generated from prokaryotic system. METHODS: The gene of human B7-H4 extracellular region (IgV-like and IgC-like domains) was obtained by PCR from human cDNA FLJ22418 and then inserted into the prokaryotic expression vector pGEX-5X-3 expressing glutathione s-transferase (GST) fusion protein. After being identified by restriction enzyme digestion and sequencing, the recombinant vector was transferred into host strain E coli BL21-RIL(DE3). A 47 kDa fusion protein (GST/hB7-H4) was induced by isopropyl-beta-D-thiogalactopyranoside (IPTG) and purified by standard methods reported in the prokaryotic system. The inhibitory effect of GST/hB7-H4 on proliferation of T cells was observed in vitro by CD3mAb activated T-cell culturing system and [(3)H]-thymidine incorporation assay. The concentrations of interleukin-2 and iterferon-g in the supernatants of T cells were determined by ELISA. RESULTS: We successfully constructed the method for high-level expression and purification of the hB7-H4 extracellular domain as GST fusion protein from E coli. The GST/hB7-H4 fusion protein produced in bacteria had obvious biological activity to inhibit T-lymphocyte proliferation and IL-2 secretion. CONCLUSION: The prokaryote expression system could be used to generate hB7-H4 protein with natural spatial conformations and biological functions, which provided an efficient and economical way for the preparation of this target protein.

Time courses of B7 family molecules expressed on activated T-cells and their biological significance.

B7 family molecules are mainly expressed on the outer membrane of antigen-presenting cells. Here, our results demonstrate that CD80, CD86, and PD-L1 molecules are also expressed on T-cells that have been activated by simultaneous exposure to anti-CD3 and anti-CD28 mAbs, but PD-L2 and GL50 molecules were not detectable during the first six days of culture that follow such stimulation. We have analysed the time course of B7 family molecule expression on activated T-cells. CD28 and its ligands, CD80/CD86, have a high degree of co-localization and exhibit compartmental distribution on the membrane of activated T-cells, which is visualized by confocal microscopy. Interestingly, the co-localization of PD-1 and its ligand also exhibit similar phenomenon. Additionally, we provide evidence indicating that the CD80, CD86, and PD-L1 molecules are functional, since T-cells expressing B7 family molecules are able to stimulate the proliferation of highly purified allogeneic or autologous T-cells. Anti-CD80, anti-CD86, and soluble CD28-Ig protein could significantly attenuate the proliferation of T-cells, whereas anti-PD-L1 mAb may lead to the expansion of activated T-cells. We can conclude that activated T-cells expressing B7 family molecules could act as "APC" to trigger purified T-cells, and B7 family molecules play important roles during the activation of T-cells. These results indicate a need for further work, exploring the regulatory roles these molecules may play in immune responses.