DNA ploidy analysis and expression of MMP-9, TIMP-2, and E-cadherin in gastric carcinoma

AIM: To investigate DNA ploidy and expression of MMP-9,TIMP-2, and E-cadherin in gastric carcinoma and to explore the mechanism of invasion and metastasis of gastric carcinoma.METHODS: Immunohistochemical methods were used to detect the expressions of MMP-9, TIMP-2, and E-cadherin in 156 cases, including 99 cases of gastric carcinoma, 16cases of adjacent noncancerous mucosa, 16 cases of distant metastases and 25 cases of metastatic lymph node (LN) from gastric carcinoma. Flow cytometry DNA ploidy and S-phase fraction (SPF) analysis were performed on 57 cases, including 47 cases of gastric cancer, 6 cases of adjacent noncancerous mucosa, and 4 cases of distant metastatic cancer.RESULTS: The expression of MMP-9 was significantly correlated with Lauren's classification, Borrmann's classification, LN metastasis, tumor metastasis, and TNM stage, as well as depth of invasion (all P＜0.05). The positive rate was lower in noncarcinoma than in carcinoma (31.3% vs 66.7%, P＜0.01). The expression of TIMP-2was significantly correlated with Borrmann's classification,LN metastasis, and the depth of invasion (all P＜0.05).The expression of E-cadherin was significantly correlated with differentiation, Lauren's classification, Borrmann's classification, and LN metastasis, as well as the depth of invasion (P＜0.01 or ,P＜0.05). E-cadherin was less expressed in carcinoma than in noncarcinoma (42.4% vs 87.5%,P＜0.01). There was a positive correlation between MMP-9and TIMP-2 and a negative correlation between MMP-9and E-cadherin, but no correlation between TIMP-2 and E-cadherin. Also there was a positive correlation between DNA aneuploid rate and differentiation and LN metastasis.SPF that was higher than 15% was positively correlated with tumor size, differentiation and LN metastasis. And there was a significant difference between carcinoma and noncarcinoma in DNA aneuploid rate and SPF.CONCLUSION: With tumor progression and development of heterogeneity, the abnormal expressions of MMP-9,TIMP-2, and E-cadherin or DNA aneuploid rate or high SPF gradually increases, suggesting that they play a crucial role in gastric carcinoma progression.

First-Principles Study of Intrinsic Point Defects of Monolayer GeS

The properties of six kinds of intrinsic point defects in monolayer GeS are systematically investigated using the“transfer to real state”model,based on density functional theory.We find that Ge vacancy is the dominant intrinsic acceptor defect,due to its shallow acceptor transition energy level and lowest formation energy,which is primarily responsible for the intrinsic p-type conductivity of monolayer GeS,and effectively explains the native p-type conductivity of GeS observed in experiment.The shallow acceptor transition level derives from the local structural distortion induced by Coulomb repulsion between the charged vacancy center and its surrounding anions.Furthermore,with respect to growth conditions,Ge vacancies will be compensated by fewer n-type intrinsic defects under Ge-poor growth conditions.Our results have established the physical origin of the intrinsic p-type conductivity in monolayer GeS,as well as expanding the understanding of defect properties in lowdimensional semiconductor materials.

Theoretical understanding of correlation between magnetic phase transition and the superconducting dome in high-Tc cuprates

Many issues concerning the origin of high-temperature superconductivity(HTS)are still under debate.For example,how the magnetic order varies with doping and its relationship with the superconducting temperature(Tc);and why Tcalways peaks near the quantum critical point.In this paper,taking hole-doped La_(2)CuO_(4)as a classical example,we employ the first-principles band structure and total energy calculations with Monte Carlo simulations to explore how the symmetry-breaking magnetic ground state evolves with hole doping and the origin of a dome-shaped superconductivity region in the phase diagram.We demonstrate that the local antiferromagnetic order and doping play key roles in determining the electron-phonon coupling,thus Tc.Initially,the La_(2)CuO_(4)possesses a checkerboard local antiferromagnetic ground state.As the hole doping increases,Tcincreases with the enhanced electron-phonon coupling strength.But as the doping increases further,the strength of the antiferromagnetic interaction weakens and spin fluctuation increases.At the critical doping level,a magnetic phase transition occurs that reduces the local antiferromagnetism-assisted electron-phonon coupling,thus diminishing the Tc.The superconductivity disappears in the heavily overdoped region when the ferromagnetic order dominates.These observations could account for why cuprates have a dome-shaped superconductivity region in the phase diagram.Our study,thus,contributes to a fundamental understanding of the correlation between doping,local magnetic order,and superconductivity of HTS.

Reviewing and understanding the stability mechanism of halide perovskite solar cells

Finding sustainable and renewable energy to replace traditional fossil fuel is critical for reducing greenhouse gas emission and avoiding environment pollution.Solar cells that convert energy of sunlight into electricity offer a viable route for solving this issue.At present,halide perovskites are the most potential candidate materials for solar cell with considerable power conversion efficiency,whereas their stability remains a challenge.In this work,we summarize four different key factors that influence the stability of halide perovskites:(a)effect of environmental moisture on the degradation of halide perovskites.The performance of halide perovskite solar cells is reduced due to hydrated crystal hinders the diffusion of photo-generated carriers,which can be solved by materials encapsulation technique;(b)photoinduced instability.Through uncovering the underlying physical mechanism,we note that materials engineering or novel device structure can extend the working life of halide perovskites under continuous light exposure;(c)thermal stability.Halide perovskites are rapidly degraded into PbI2 and volatile substances as heating due to lower formation energy,whereas hybrid perovskite is little changed;(d)electric field effect in the degradation of halide perovskites.The electric field impacts significantly on the carrier separation,changes direction of photo-induced currents and generates switchable photovoltaic effect.For each key factor,we have shown in detail the underlying physical mechanisms and discussed the strategies to overcome this stability difficulty.We expect this review from both theoretical and experimental points of view can be beneficial for development of perovskite solar cell materials and promotes practical applications.

Ⅳ族半导体Ge_(1-x)Sn_(x)中的自发磁化及磁阻回滞现象

以硅基半导体为代表的Ⅳ族半导体在现代工业中扮演着举足轻重的作用.然而,Ⅳ族半导体因其缺乏非常强的交换相互作用难以产生铁磁序,从而限制了蓬勃发展的自旋电子学器件在Ⅳ族半导体领域的应用.本文通过分子束外延生长Ⅳ族半导体Ge_(1-x)Sn_(x),引入原子排列的无序效应,从而打破反演对称性,在实验上成功观测到了自发铁磁序的产生.通过低温输运测量,可以清晰观测到电阻的回滞现象.通过磁化特性测量,进一步可以观测到自发铁磁序对应的磁滞回线,从而清晰地证明了Ⅳ族半导体Ge_(1-x)Sn_(x)中自发铁磁序的存在.通过第一性原理计算,作者指出此自发铁磁序源于临近布里渊区中心的范霍夫奇点引起的自旋极化的半金属态(half-metallicity).该工作成功地在非磁性的Ⅳ族半导体中诱导出来自发铁磁序,对自旋电子学应用于Ⅳ族半导体进而和现行的硅基工业标准兼容具有重要意义.