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Abstract Background Lgr5 (leucine-rich-repeat-containing G-protein-coupled receptor 5) has recently been identified as an intestinal stem cell marker. In order to determine whether Lgr5 is a potential marker of cancer stem cells, we investigated whether Lgr5 expression correlated with Ki-67 expression and prognosis in colorectal carcinoma. Methods Lgr5 and Ki-67 expression were evaluated by immunohistochemistry in 192 colorectal carcinoma specimens. Selection of side population (SP) cells was performed by staining with Hoechest 33342, and Lgr5 expression in Colo205 SP cells was then detected by immunofluorescence. Results Lgr5 expression was significantly higher in carcinoma than in normal mucosa (P=0.001). Lgr5 was positively correlated with histological grade (P=0.001), depth of invasion (P=0.001), lymph node metastasis (P=0.001), distant metastasis (P=0.004), pTNM stage (P=0.001), and Ki-67 (r=0.446, P=0.001). Multivariate analysis showed that the effect of Lgr5 on survival was independent of Ki-67 (P=0.037). In the in vitro study, Hoechst low-staining cells were counted in 7% of the Colo205 colon cancer cell line population, and Lgr5 expression was strikingly stronger in Hoechst low-staining cells than in high-staining cells (P=0.001). Conclusions These findings suggest that Lgr5 may play an important role in the progression and prognosis of colorectal carcinoma, and may be a potential new therapeutic target for the treatment of colorectal cancer patients. It may also be considered as a potential marker for colorectal cancer stem cells (CSCs).

We report experimental investigation of the resistivity and Nernst effect in two-dimensional (2D) NbSe2 crystals. A strongly enhanced Nernst effect, 100 times larger than that in bulk NbSe2, caused by moving vortices is observed in thin film. It is found that in the low temperature, high magnetic field regime, pinning effects show little dependence on the thickness and resistivity of the superconductor films. Strong Nernst signals persist above the superconducting transition, suggesting that the Nernst effect is a sensitive probe to superconducting fluctuations. A magnetic field induced superconductor--insulator transition (SIT) is evident, which is surprising in that such a SIT usually takes place in disordered dirty superconductors, while our samples are highly crystalline and close to the clean limit. Hence, our results expand the scope of SIT into 2D crystal clean superconductors. [ABSTRACT FROM AUTHOR]

We report experimental investigation of the resistivity and Nernst effect in two-dimensional (2D) NbSe2 crystals. A strongly enhanced Nernst effect, 100 times larger than that in bulk NbSe2, caused by moving vortices is observed in thin film. It is found that in the low temperature, high magnetic field regime, pinning effects show little dependence on the thickness and resistivity of the superconductor films. Strong Nernst signals persist above the superconducting transition, suggesting that the Nernst effect is a sensitive probe to superconducting fluctuations. A magnetic field induced superconductor--insulator transition (SIT) is evident, which is surprising in that such a SIT usually takes place in disordered dirty superconductors, while our samples are highly crystalline and close to the clean limit. Hence, our results expand the scope of SIT into 2D crystal clean superconductors. [ABSTRACT FROM AUTHOR]

The relationship between the electrical properties and structure evolution of single layer graphene was studied by gradually introducing the gallium ion irradiation. Raman spectrums show a structural transition from nano-crystalline graphene to amorphous carbon as escalating the degree of disorder of the graphene sample, which is in correspondence with the electrical transition from a Boltzmann diffusion transport to a carrier hopping transport. The results show a controllable method to tune the properties of graphene. [ABSTRACT FROM AUTHOR]

To improve operation stability of pulse detonation engine and shorten the distance of deflagration to detonation transition, a series of multi-cycle detonation experiments were investigated with six different air inlet systems. Using air as oxidizer and liquid C8H18 as fuel, the effect of different air inlet systems on pulse detonation engine with frequency of 14 Hz and equivalence ratio of 1.5 was analyzed. Pressure history along detonation tube was recorded by five dynamic piezoelectric pressure transducers. It was approved by a particle image velocimetry that centrifugal forces from rotating airflow had a significant negative impact on the uniformity of fuel distribution in detonation tube. Furthermore, the experimental results indicated that operation stability of pulse detonation engine was increased with the improvement of fuel distribution, and deflagration to detonation transition distance was obviously decreased with the increase of thrust wall sealing. In these different air inlet systems, the pulse detonation engine with air inlet system of reed valve achieved the shortest deflagration to detonation transition distance, the best stability and stable operation of about 1 min at 14 Hz. This study provided references for the development of pulse detonation engine. [ABSTRACT FROM AUTHOR]

In order to research the drag reduction characteristics of base bleed in supersonic flow, three-dimensional Navier-Stokes equations with chemical reactions are solved by the high-accuracy upwind scheme (AUSMPW +), k-ω SST turbulence model, 8 species/12 reaction kinetics model, and second-order turbulent combustion model. The flow field based on the actual base bleed gas in supersonic flow is numerically simulated by verifying the effectiveness and reliability of the numerical methods. The calculated results show that, with the increase in base bleed parameter, the base pressure ratio increases and then decrease, and finally it tends to increase. When the base bleed parameter is small, base pressure ratio does not change with base bleed area. While base bleed parameter is large, the base pressure ratio increases with base bleed area. Increasing the temperature of base bleed gas is favorable to increase the base pressure ratio. The intensity of the secondary combustion improves with the increase in the content of fuel-rich gas in base bleed gas, which can improve the base pressure ratio. The results can provide reference for the engineering application of base bleed projectile. [ABSTRACT FROM AUTHOR]

The combustion characteristics of polymethyl methacrylate(PMMA) in the SFRJ were investigated using a direct tube test facility. The effect of factors, such as fuel port diameter, aft-mixing combustion chamber pressure, and air mass flow rate, on regression rate and performance was investigated. The pressure, temperature, local regression rate and their average value were got. The results show that the fuel mean regression rate decreases with the increase in fuel port diameter, but the aft-mixing combustion chamber pressure and temperature were enhanced. In addition, the pressure and temperature of aft-mixing combustion chamber decreased under the condition of low pressure ( less than 0. 8 MPa), but this effect was limited. It is first found that an erosion effect phenomenon is produced in the SFRJ combustion chamber when the fuel port diameter is smaller (Dp = 30 mm). [ABSTRACT FROM AUTHOR]

In order to optimize the design of kerosene gel supply pipeline and tapered injector, the power-law constitutive model is used to build a solution method of two-dimensional/three-dimensional incompressible steady flow. The flow characteristics of kerosene gel are numerically studied based on a SIMPLE algorithm. The analytical solution of parameters of propellant in straight round pipe and the kinetic energy correction coefficient of laminar flow are presented. The results show that the plunger flow area of straight round pipe is fixed when pipe diameter is unchanged. To reduce the average apparent viscosity of the injector outlet cross section, the length of outlet section needs to be decreased. The reasonable contraction angle of injector is about 40°. In elbow pipe, The secondary flow in the form of double vortices exits in elbow pipe. The asymmetries of shear rate and apparent viscosity are more significant than the asymmetry of flow velocity. [ABSTRACT FROM AUTHOR]

We report experimental investigation of the resistivity and Nernst effect in two-dimensional (2D) NbSe2 crystals. A strongly enhanced Nernst effect, 100 times larger than that in bulk NbSe2, caused by moving vortices is observed in thin film. It is found that in the low temperature, high magnetic field regime, pinning effects show little dependence on the thickness and resistivity of the superconductor films. Strong Nernst signals persist above the superconducting transition, suggesting that the Nernst effect is a sensitive probe to superconducting fluctuations. A magnetic field induced superconductor--insulator transition (SIT) is evident, which is surprising in that such a SIT usually takes place in disordered dirty superconductors, while our samples are highly crystalline and close to the clean limit. Hence, our results expand the scope of SIT into 2D crystal clean superconductors. [ABSTRACT FROM AUTHOR]

We report experimental investigation of the resistivity and Nernst effect in two-dimensional (2D) NbSe2 crystals. A strongly enhanced Nernst effect, 100 times larger than that in bulk NbSe2, caused by moving vortices is observed in thin film. It is found that in the low temperature, high magnetic field regime, pinning effects show little dependence on the thickness and resistivity of the superconductor films. Strong Nernst signals persist above the superconducting transition, suggesting that the Nernst effect is a sensitive probe to superconducting fluctuations. A magnetic field induced superconductor--insulator transition (SIT) is evident, which is surprising in that such a SIT usually takes place in disordered dirty superconductors, while our samples are highly crystalline and close to the clean limit. Hence, our results expand the scope of SIT into 2D crystal clean superconductors. [ABSTRACT FROM AUTHOR]

Objective: To examine expression of stromal cell-derived factor-1 (SDF-1) and CXC chemokine receptor 4 (CXCR4) in rat cornea tissue and their role in corneal allograft rejection., Methods: With 15 Wistar rats as the normal control group, 22 Wistar rats received autologous corneal graft transplantation, and 44 Wistar rats received transplantation of corneal graft from SD rats with penetrating keratoplasty. From the rats with allograft transplantation, 22 were selected randomly for treatment with TobraDex eye drops for 30 days after the operation (twice a day), and the remaining 22 rats were treated with normal saline only. Clinical assessment of the corneal grafts was carried out using Larkin's method; histopathological observation, immunohistochemistry, and real-time quantitative PCR of the corneal grafts were performed on days 5 and 9 after the transplantation., Results: Graft rejection occurred in none of the rats in autograft group. In rats treated with TobraDex, the graft survival time was significantly longer than that in rats with saline treatment (24∓0.32 vs 10∓0.36 days, P<0.001), and histopathological examination revealed numerous inflammatory cells and neovascularization in the allografts in the latter group. SDF-1 and CXCR4 mRNA expression in the corneal tissue increased significantly in rats receiving allograft transplantation and saline treatment (P<0.001 on day 5 and P<0.01 on day 5), and their expression was obviously lowered in rats with TobraDex treatment. Immunohistochemical examination revealed that the expression of SDF-1 and CXCR4, found mainly in the corneal epithelium and stroma, was significantly increased in the allografts in rats with saline treatment., Conclusion: SDF-1/CXCR4 may participate in corneal graft rejection in rats early after transplantation possibly through the mechanism that SDF-1 specifically induces CXCR4 + cell maturation and chemotaxis toward the allograft to promote corneal neovascularization.

Tunable diode laser absorption spectroscopy (TDLAS) technology combined with wavelength modulation spectroscopy (WMS) technology is an important technique for trace gas detection. Detected with the lock-in amplifier, the second harmonic signal obtained after demodulation is analyzed to get the gas absorption information. However, the second harmonic signal is affected by noise which reduces the accuracy and stability of the detection system. To improve the signal to noise ratio (SNR) of the TDLAS detection system, a denoising method based on Gabor transform is proposed for second harmonic signal noise reduction. Taking the CH4 absorption spectrum at 1 653.72 nm as an example, the effectiveness of the noise reduction method is verified through simulation and experiments. The simulation results show that the signal to noise ratio for the second harmonic signal of 0 dB can be improved 15.73 dB with Gabor transform-based denoising method. Experimental results show that with the Gabor transform-based denoising method, the linear correlation coefficient r can be as high as 0.996 59 between the second harmonic peak value and the CH4 concentration in the range of 0.001%~0.02%. At the same time, the detection accuracy and stability of the system have been improved significantly.

Rapid and real-time analysis of cigarette smoke is of great significance to study the puff-by-puff transfer rules in the suction process and to explore the relationship between smoking and health. By combining with the modified commercial smoking machine herein, cigarette smoke online analysis system was established based on the TDLAS technology. The puff-by-puff stability of this system was verified by simulated cigarette composed of a pocket containing CH₄ (volume fraction of 0.4), of which the second harmonic peaks are near 1.39. Using this system, the concentration of CH₄ in four different kinds of cigarettes was analyzed puff-by-puff by a semiconductor laser, of which center wavelength was at 1 653.72 nm. The results showed that the CH₄ concentration of cigarette smoke increased puff-by-puff. CH₄ concentration in the flue-cured cigarette is obviously higher than that of blended cigarette by comparing the content of all and puff-by-puff concentration. The puff-by-puff concentration of flue-cured cigarette increased from 400 to 900 ppm, however, the puff-by-puff concentration of blended cigarette increased from 200 to 600 ppm. Simultaneously, there was significant difference between different kinds of the flue-cured. Comparing to tradi- tional analysis methods, this system can effectively avoid the interference of other gases in the smoke cigarette as a result of its strong anti-interference. At the same time, it can finish analysis between suction interval without sample pretreatment. The technology has a good prospect in the online puff-by-puff analysis of cigarette smoke.

Objective: To evaluate the clinical effectiveness and safety of intubation-surfactant-extubation (INSURE) method in the treatment of neonatal respiratory distress syndrome (NRDS), and to investigate its possible mechanisms., Methods: Sixty-four premature infants, who were admitted for NRDS and treated with pulmonary surfactant from March 2010 to March 2012, were enrolled in the study. They were randomly divided into INSURE (n=32) and conventional mechanical ventilation (CMV) groups (n=32). The two groups were compared in terms of respiratory function, ventilation time, duration of oxygen therapy, complications, and prognosis, as well as expression of interleukin-10 (IL-10), tumor necrosis factor-α (TNF-α) and serum ferritin (SF)., Results: Oxygenation index in the INSURE group was significantly higher than in the CMV group at 48 hours after treatment (P<0.05). Compared with the CMV group, the INSURE group showed significantly lower incidence of ventilator-associated pneumonia (VAP) and significantly shorter duration of oxygen therapy (P<0.05 for all comparisons). There were no significant differences in ventilation time and the incidence of pneumothorax, intracranial hemorrhage, necrotizing enteroolitis, bronchopulmonary dysplasia, and pneumorrhagia between the two groups (P>0.05). The levels of TNF-α and SF were significantly lower in the INSURE group than in the CMV group at 6, 24, 48, and 72 hours after treatment (P<0.05), while the level of IL-10 was significantly higher in the INSURE group than in the CMV group (P<0.05)., Conclusions: INSURE method can improve the oxygenation function of the lung, decrease the incidence of VAP and shorten the duration of oxygen therapy in neonates with NRDS, which is probably due to the fact that this method can reduce the production of TNF-α and SF and inhibit the decrease of IL-10.