Comput Med Imaging Graph
January 2021
Deep learning, for image data processing, has been widely used to solve a variety of problems related to medical practices. However, researchers are constantly struggling to introduce ever efficient classification models. Recent studies show that deep learning can perform better and generalize well when trained using a large amount of data.
View Article and Find Full Text PDFCrown ethers, as a kind of heterocycle, have been the subject of great interest over recent decades due to their selective capability to bind to metal cations. The use of a constant crown ether, such as naphtho-15-crown-5 (N15C5), and varied metal cations (Li, Na, K, Be, Mg, Ca, Co, Ni, Cu) makes it possible to determine the contributions of the metal cations to nonlinear optical (NLO) responses and to design an appropriate NLO-based cation detector. N15C5 and its metal cation derivatives have been systematically investigated by density functional theory.
View Article and Find Full Text PDFIt is of great significance to evaluate the soil heavy metal pollution level and to know their spatial distribution characteristics. Taking soil heavy metals As, Cd, Cr, Cu, Hg, Ni, Pb and Zn in a town of southern Jiangsu as research objects, using the single factor evaluation method, Nemerow comprehensive evaluation method, geostatistical analysis method together with the landscape pattern grain effect and the landscape index analysis method, we studied their characteristics of landscape patterns in the study area based on pollution evaluation. The results showed that:① The average value range of single factor pollution index and Nemerow comprehensive evaluation index for soil heavy metals in study area was 0.
View Article and Find Full Text PDFCarborane has been the subject of great interest over the last decades due to its high structural, chemical, biological stability and diverse applications. In the present work, carboranyl-substituted indole/indoline compounds and their functionalized derivatives have been systematically investigated by density functional theory (DFT) method with the view of assessing their electronic structures and first hyperpolarizabilities. Significantly, the first hyperpolarizabilities can be obviously enhanced by the introduction of a strong electron-withdrawing group for closed-ring forms, while the strong electron-donating group is beneficial for large first hyperpolarizabilities for open-ring forms.
View Article and Find Full Text PDFIon-buckybowl complexes have received considerable attention in modern chemical research due to its fundamental and practical importance. Herein, we performed density functional theory (DFT) to calculate the geometical structure, binding interactions, dipole moments and the first hyperpolarizabilities (βtot) of ion-buckybowl complexes (ions are Cl(-) and Na(+), buckybowls are quadrannulene, corannulene and sumanene). It is found that the stabilities of ion-buckybowl compounds primarily originate from the interaction energy, which was proved by a new isomerization energy decomposition analysis approach.
View Article and Find Full Text PDFThe electron donor-acceptor complexes, which undergo intramolecular charge transfer under external stimulus, are an emerging class of materials showing important application in nonlinear optics. Synthesizing ferrocene/fullerene complexes through face-to-face fusion would enjoy the merits of both ferrocene and fullerene due to their strong donor-acceptor interactions. Four ferrocene/fullerene hybrid complexes with the gradual extension of fullerene cage size, including CpFe(C60H5), CpFe(C66H5), CpFe(C70H5), and CpFe(C80H5) (Cp is cyclopentadienyl), have been investigated by density functional theory.
View Article and Find Full Text PDFMuch effort has been devoted to investigating the molecular geometries, electronic structures, redox properties and nonlinear optical (NLO) properties of Ir complexes involving o-, m- or p-carborane groups by density functional theory (DFT) methods. Switchable second-order NLO properties were induced by redox processes involving these complexes, and it was found that mainly the coordination bonds of Ir complexes changed during the oxidation process. Our calculations revealed that oxidation reactions have a significant influence on the second-order NLO response owing to the change in charge transfer pattern.
View Article and Find Full Text PDFHexathiophenalenylium (HTPLY) has gained increasing attention for its interesting and potentially useful optical properties as a result of the enhancement in spin delocalization and charge-transfer of phenalenyl radicals, occasioned by the attachment of successive three disulfide linkages. Herein, we performed density functional theory to calculate the binding interactions, electronic absorption spectra and the second hyperpolarizabilities of cation and radical dimers of HTPLY and its nitro derivatives. It is found that the equilibrium structures of the π dimers at fully staggered position are most stable.
View Article and Find Full Text PDFThe studies of geometrical structures, thermal stabilities, redox properties, nonlinear responses and optoelectronic properties have been carried out on a series of novel ferrocenyl (Fc) chromophores with the view of assessing their switchable and tailorable second order nonlinear optics (NLO). The use of a constant Fc donor and a 4,4'-bipyridinium acceptor and varied conjugated bridges makes it possible to systematically determine the contribution of organic connectors to chromophore nonlinear optical activities. The structures reveal that both the reduction reactions and organic connectors have a significant influence on 4,4'-bipyridinium.
View Article and Find Full Text PDFThe unusual properties of Li-doped boron nitride nanomaterials have been paid further attention due to their wide applications in many promising fields. Here, density functional theory (DFT) calculations have been carried out to investigate the second-order nonlinear optical (NLO) properties of boron nitride nanocone (BNNC) and its Li-doped BNNC derivatives. The natural bond orbital charge, electron location function, localized orbital locator and frontier molecular orbital analysis offer further insights into the electron density of the Li-doped BNNC derivatives.
View Article and Find Full Text PDFThe polycyclic p-quinodimethanes are proposed to be the novel candidates of the high-performance nonlinear optical (NLO) materials because of their large third order polarizabilities (γ). We investigate the switchable NLO responses of a series of polycyclic p-quinodimethanes with redox properties by employing the density functional theory (DFT). The polycyclic p-quinodimethanes are forecasted to exhibit obvious pure diradical characters because of their large y 0 index (the y 0 index is a value between 0 [closed-shell state] and 1 [pure biradical state]).
View Article and Find Full Text PDFThe second-order nonlinear optical (NLO) properties of a series of Pt(II) dithienylethene (DTE) complexes possessing the reversible photochromic behavior have been investigated by density functional theory (DFT) combined with the analytic derivatives method. The results show that the calculated static first hyperpolarizabilities (βtot) of the open-ring and closed-ring systems significantly increase in the range of 2.1-4.
View Article and Find Full Text PDFWe had reported that N-myc downstream-regulated gene (NDRG2) regulates colorectal cancer, breast cancer, clear cell renal cell carcinoma, pancreatic cancer, thyroid cancer and esophageal squamous cell proliferation, development, and apoptosis. The goal of this study was to determine the expression pattern of NDRG2 in human lung cancer and its correlation with prognosis. Immunohistochemistry, RT-PCR and western blot were used to explore the expression of NDRG2 in 185 human lung cancer patients.
View Article and Find Full Text PDFAs a kind of novel organometallic complexes, the cyclopentadienylcobalt (CpCo) linear [4]phenylene complexes (4 = number of benzene rings) display efficient switchable nonlinear optical (NLO) response when CpCo reversibly migrates along the linear [4]phenylene triggered by heating or lighting. In this paper, the second-order NLO properties for CpCo linear [4]phenylene complexes were calculated by using the density functional theory (DFT) methods with four functionals. All of the functionals yield the same order of β tot values: 1<2<4<3.
View Article and Find Full Text PDFZhonghua Liu Xing Bing Xue Za Zhi
January 2012
Objective: To study the chemical constituents of Codonopsis lanceolata.
Methods: Chemical constituents were separated with the column chromatographic, and their structures were identified by chemical and spectroscopic methods.
Results: Six compounds were isolated and identified as syringin (1), shikimic acid (2), friedelin (3), alpha-spinasterol (4), stigmasterol (5), stigmasta-7-dien-3beta-ol (6).
Objective: To study mutations of tumor suppressor gene PTEN in human hepatocellular carcinomas and its effects on the proliferation and apoptosis of hepatocellular carcinoma cell line HHCC.
Methods: (1) PCR-SSCP and sequence analysis were used to detect the mutations of the 5th and 8th exon of PTEN in 42 cases of human primary hepatocellular carcinoma. (2) Eukaryotic expression vectors of the wild-type (pEGFP-wt-PTEN) and the mutant type (pEGFP-PTEN, G129R) of PTEN were constructed.
Objective: To study the effect of tumor suppressor gene PTEN on proliferation and cell cycle of hepatocellular carcinoma cell line HHCC.
Methods: Firstly, eukaryotic expression vectors of wild type and mutated type of PTEN gene were constructed, named as pEGFP-WT-PTEN and pEGFP-PTEN; G129R, respectively. Lipofectamine 2000 was used to transfect the constructed expression vectors into hepatocellular carcinoma cell line HHCC which was PTEN protein negative.
Di Yi Jun Yi Da Xue Xue Bao
December 2005
Objective: To investigate the effect of curcumin on cell apoptosis and c-myc and caspase-3 expressions in human melanoma A375 cell line.
Methods: A375 cells were exposed to curcumin treatment and growth inhibition of the cells was examined by MTT assay. Annexin V/propidium iodide double staining and DNA fragmentation analysis were employed for assay of the cell apoptosis and morphological changes of the cells were observed with inverted microscopy and transmission electron microscopy, respectively.
Aim: To investigate the survivin gene expression in human hepatocellular carcinoma cell line SMMC-7721 and the effects of survivin gene RNA interference (RNAi) on cell apoptosis and biological behaviors of SMMC-7721 cells.
Methods: Eukaryotic expression vector of survivin gene RNAi and recombinant plasmid pSuppressorNeo-survivin (pSuNeo-SVV), were constructed by ligating into the vector, pSuppressorNeo (pSuNeo) digested with restriction enzymes Xba I and Sal I and the designed double-chain RNAi primers. A cell model of SMMC-7721 after treatment with RNAi was prepared by transfecting SMMC-7721 cells with the lipofectin transfection method.
Zhonghua Fu Chan Ke Za Zhi
July 2004
Objective: To investigate the expression of hypoxia inducible factor-1alpha (HIF-1alpha) in placentas of pregnancy induced hypertension (PIH).
Methods: Placentas of 49 PIH pregnancies (PIH group 1) and 26 normotensive pregnancies (control group 1) were investigated for HIF-1alpha protein expression using microarray and immunohistochemistry. The expression of HIF-1alpha mRNA in placentas of 12 PIH pregnancies (PIH group 2) and 12 normal pregnancies(control group 2) was respectively detected by RT-PCR.
Xi Bao Yu Fen Zi Mian Yi Xue Za Zhi
July 2003
Aim: To construct the superantigen SEA (D227A) expression vector modulated by cis-acting element of AFP and express it specifically on AFP(+) hepatocellular carcinoma (HCC) cells.
Methods: The enhancer and promoter of AFP gene, SEA (D227A) cDNA and linker-CD80tm were amplified by PCR. The gene segments mentioned above were cloned into the multiple cloning sites of retrovirus vector pLXSN to construct an attenuated superantigen expression vector pLXSN-SEA (D227A)-linker-CD80tm modulated by cis-acting element of AFP gene.
Aim: To construct an eukaryotic superantigen gene expression vector containing the recombinant gene of SEA and CD80 molecule transmembrane region (CD80TM), and to express staphylococcus enterotoxin A (SEA) on the membrane of hepatocellular carcinoma (HCC) cell to form a superantigen gene modified tumor vaccine for HCC.
Methods: SEA and linker-CD80TM gene were amplified through PCR from plasmid containing cDNA of SEA and CD80. Gene fragments were then subcloned into the multiple cloning sites of retroviral vector pLXSN.