Asymmetric localization and symmetric diffraction-free transmission in synthetic photonic lattice with anti-parity-time symmetry.

We study, to the best of our knowledge, the first observations of light propagation in synthetic photonic lattice with anti-parity-time symmetry by tuning the gain or loss of two coupled fiber rings alternatively and corresponding phase distribution periodically. By tuning the phase φ and the wave number Q in the lattice, asymmetric transmission of the light field can be achieved for both long and short loops when φ≠nπ/2 (n is an integer). Further investigations demonstrate that asymmetric localization of the light field in the long loop and symmetric diffraction-free transmission in two loops can both be realized by changing these two parameters. Our work provides a new method to obtain anti-parity-time symmetry in synthetic photonic lattice and paves a broad way to achieve novel optical manipulation in photonic devices.

Asymmetric localization induced by non-Hermitian perturbations with PT symmetry in photonic lattice.

We study both theoretically and numerically the asymmetric localization of lightwave in a three-layered photonic lattice with non-Hermitian perturbations. The results indicate that the gauge potential for photons can arise from the non-Hermitian perturbations, once the perturbations satisfy parity-time symmetry. Further study shows that the Peierls phase between adjacent waveguides has an important impact on the shapes of the band structures, which result in asymmetric localization of a lightwave in such a system when the wave number and Peierls phase satisfy k=ϕ=±π/2. This Letter provides a new way to control the light transmission and a feasible method to realize gauge potential for photons.

In vitro study of SPIO-labeled human pancreatic cancer cell line BxPC-3.

The survivin gene is highly expressed in pancreatic cancer. The purpose of this study was to design and synthesize functionalized magnetic iron oxide nanoparticles (MNPs) targeting survivin gene for the detection of pancreatic cancer. The pancreatic cancer cell line BxPC-3 with survivin gene expression was selected in this study. The healthy lung fibroblast cell was used as a control. Chitosan-coated MNPs (CS@MNPs) and antisense oligodeoxynucleotide of survivin gene were conjugated to MNPs to give Sur-MNPs. Fourier transform infrared spectroscopy was performed to confirm the conjunction of chitosan. The interactions of MNPs, CS@MNPs, and Sur-MNPs in BxPC-3 cells were observed, recorded and analyzed. The size, morphology, cell uptake, cytotoxicity and stability of those particles were assessed by transmission electron microscope, Prussian blue staining, MTT assay and agarose gel electrophoresis. The magnetic resonance signal intensities of pancreatic cells labeled with CS@MNPs and MNPs, and Sur-MNPs, were compared on T2-weighted images. The results demonstrated that the level of cellular uptake of CS@MNPs was higher than that of naked MNPs. The Sur-MNPs had a suitable size (12 nm sized core), high stability, no cytotoxicity and good water dispersion. Sur-MNPs did not accumulate in healthy lung fibroblast cells, while being taken up by BxPC-3 cells. The Sur-MNPs in BxPC-3 cells could be visualized on T2-weighted images, which suggested that Sur-MNPs could be used to detect the expression of survivin gene. Thus, Sur-MNPs may be a potential molecular imaging probe targeting survivin gene for early detection of pancreatic cancer cells.

Lymphangiogenesis and biological behavior in pancreatic carcinoma and other pancreatic tumors.

Lymphatic vessels in primary tumor tissue play an important role in lymphatic metastasis. Lymphatic metastasis of malignant neoplasms is significantly related to prognosis, influencing both recurrence and survival. The aim of this study was to investigate the correlation of intra-tumoral lymphatic vessel density (iLVD) and peri-tumoral lymphatic vessel density (pLVD) with biological behavior and prognostic parameters in pancreatic carcinoma (PC) and other pancreatic tumors. Lymphangiogenesis was examined using the D2-40 monoclonal antibody in 33 cases of PC, 7 neuroendocrine tumors of the pancreas (NETP), 7 solid pseudopapillary tumors of the pancreas (SPTP) and 3 cystadenomas of the pancreas (CP). Positively-stained microvessels were counted at magnification x400 in dense lymphatic vascular foci (hotspots). The LVD of PC was compared to 3 other pancreatic tumors. The relationships among the LVD, the extent of differentiation, lymphatic invasion, lymph node metastasis and other clinicopathological parameters of PC were analyzed. There was no difference in the iLVD among PC, NETP, SPTP and CP. The pLVD of NETP was markedly higher than that of PC, SPTP and CP. The pLVD of PC was significantly higher than that of SPTP and CP, but there was no difference between SPTP and CP. The pLVD of PC was significantly associated with the extent of differentiation, lymphatic invasion and lymph node metastasis, whereas it was not associated with age, gender, tumor size, tumor location and peri-pancreatic invasion. The iLVD of PC was not correlated with these clinicopathological parameters. There was no difference in iLVD and no marked difference in pLVD among the pancreatic tumors. Detection of pLVD is of greater importance than detecting iLVD in these pancreatic tumors, as pLVD can be utilized for the prediction of lymph node metastasis, thus aiding in the evaluation of patient prognosis.

[3.0 T magnetic resonance imaging of pancreatic cancer in an orthotopic nude murine model].

OBJECTIVE: To assess the methods of establishing an orthotopic nude murine model of human pancreatic cancer and explore the manifestations of MRI (magnetic resonance imaging) and its pathological fundamentals so as to provide research rationales for human pancreatic cancer. METHODS: The BXPC-3 cell of human pancreatic cancer was orthotopically planted in nude mice. And the animals were examined by a clinical 3.0 T magnetic resonance imager. The MRI examinations were analyzed along with their pathological findings. RESULTS: Among 18 mice, 15 of them grew tumors with a success ratio of 83.3%. The pathological findings conformed to those of high differentiation pancreatic parenchyma cancer. Comparing with the neighbor muscles, the tumors were homogeneous (66.7%, 10/15) or heterogeneous (33.3%, 5/15) of hypointense on T1-weighted images while homogeneous (26.7%, 4/15) or heterogeneous (73.3%, 11/15) hyperintense on T2-weighted images with heterogeneous enhancement. The border became obviously enhanced and there was mild central enhancement while the necrotic part showed no enhancement. CONCLUSION: 3.0T MRI can detect pancreatic neoplasms ≥ 2 mm and visualize clearly their locations, shapes, dimensions and internal structures in an orthotopic nude murine model. Thus it provides a visible framework for further studies of human pancreatic cancer.

[Radiographic and computed tomographic manifestations of chest in patients with acute chlorine gas poisoning].

OBJECTIVE: To investigate the radiographic and computerized tomographic features of chest in patients with acute chlorine poisoning and its diagnostic value. METHODS: Twenty-eight cases of chlorine poisoning were reviewed. And their radiographic and computerized tomographic features were compared and analyzed. RESULTS: Radiographic findings: among 28 patients, 9 cases were normal and 2 cases had no abnormalities on the first chest X-ray and became abnormal one or two days later. And there were abnormal findings in first chest X-ray in 17 patients:acute tracheal inflammation of peribronchitis (n = 3), acute chemical bronchopneumonia (n = 6) and diffuse interstitial and central pulmonary edema (n = 8). CT manifestations: At Days 1-3, the patients of mild poisoning had scattered patchy dense shadow; those of moderate to severe poisoning showed multiple patchy or diffuse infiltration (ground-glass opacity). And partial consolidation, air bronchogram and pleural effusion could be observed. At Days 4-10, the manifestations of mild poisoning were largely absorbed; those of moderate to severe poisoning manifested the absorption of diffuse or multiple patchy effusion and a fading of shadow. And the size of lung consolidation became smaller than before. At Day 10 after onset, 4 patients completely recovered. At Days 30-40, 6 cases showed traces of fibrous shadow and one case showed small punctiform opacities in both lungs. And at Day 42, there was slight ground-glass change. CONCLUSION: Acute chlorine gas poisoning in varying degrees may manifest acute bronchial pneumonia and acute pulmonary edema. During treatment, a series of chest X-ray examinations will help to follow the changes of disease. And CT examination can offer a more accurate evaluation of lung lesions.