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1.
Nanoscale ; 2020 Feb 11.
Artigo em Inglês | MEDLINE | ID: mdl-32043508

RESUMO

Based on ab initio calculations and the Wannier-based tight-binding method, we studied the topological electronic properties and strain modulation of transition metal monochalcogenides (TMM) Mo2XY (X, Y = S, Se, Te, X ≠ Y). These materials are nodal line semimetals in the absence of spin-orbit coupling (SOC). The presence of SOC turns them into Weyl semimetals with 24 Weyl nodes located in the kz ≠ 0 planes and related by time-reversal, rotation C3z, and mirror symmetries. The maximal separation between two neighboring Weyl points with opposite chirality is of the order of magnitude of 0.10 Å-1, which can be readily accessed by angle-resolved photoemission spectroscopy (ARPES). The Weyl semimetal phase shows great robustness and demonstrates different responses under uniaxial and biaxial strain. Intriguingly, the location of the Weyl point changes significantly, resulting in a striking modulation of topological properties under in-plane biaxial strain. Our finding provides a realistic and promising platform for studying and manipulating the behavior of Weyl fermions in experiments.

2.
J Phys Condens Matter ; 32(3): 035502, 2020 Jan 16.
Artigo em Inglês | MEDLINE | ID: mdl-31553961

RESUMO

Using the first-principles calculation, we systematically studied the electronic properties of the bilayer transition metal dichalcogenides (TMDs) MX2 (M = Mo, W; X = S, Se, Te) with replacing one, two, three or four layers of X atoms as Y atoms (X ≠ Y = S, Se, Te). By comparison, it is found that when the inner two layers of chalcogenide atoms are different, the system has both valence band offset (VBO) and conduction band offset (CBO). Among them, values of the band offsets reach maxima when the inner one layer of X atoms is replaced by Y atoms, namely forming the asymmetric Janus bilayer XMX/YMX. We take SMoS/SeMoS as an example to analyze the formation of the band offsets and the improvement of optoelectronic properties. Importantly, it is also found that both external electric field and biaxial strain can regulate electronic structures of asymmetric Janus bilayer TMDs with noticeable modulation of the values of band offsets. When the external electric field changes from negative to positive continually, CBO decreases and VBO increases. While when the biaxial strain changes from compression to stretch continually, CBO increases and VBO decreases. These findings enrich the study of bilayer TMDs that can be used as optoelectronic, nanoelectronic and valleytronic devices.

3.
Nanotechnology ; 31(9): 095704, 2019 Nov 14.
Artigo em Inglês | MEDLINE | ID: mdl-31726437

RESUMO

Thermal anisotropy/isotropy is one of the fundamental characteristics of the thermal properties of a material, playing a significant role in the high-performance thermal management in micro-/nanoelectronics. It has been well documented in the literature that the symmetry of geometric structures governs the anisotropy/isotropy of thermal transport. However, the fundamental correlation and the underlying mechanism remain unclear. In this paper, using a new two-dimensional (2D) van der Waals (vdW) phosphorus nanotube array as a case study, we show that the lattice thermal conductivity can be abnormally almost isotropic although the geometric structure presents remarkable anisotropy, which contradicts the previous consensus. The key factor for the abnormal isotropic thermal conductivity is mainly the essentially analogous group velocities along the intratube and intertube directions. Compared with a carbon-nanotube array, a traditional vdW system, a microscopic picture is established to underpin the underlying mechanism. The quasi-bond (non-covalent bonding, but far stronger than the vdW interatomic interaction) between the phosphorus nanotubes is found to be responsible for such diverse isotropic transport phenomena. The findings in this paper are expected to deepen our understanding of the anisotropy/isotropy thermal transport of materials and are also helpful for future thermal management technology.

4.
Nanoscale ; 11(39): 18358-18366, 2019 Oct 10.
Artigo em Inglês | MEDLINE | ID: mdl-31573592

RESUMO

We investigate the topological properties of the Janus superlattices WTeS and WTeSe by first-principles methods and Wannier-based tight-binding Hamiltonians. The thermal stability of the Janus structures is checked by first-principles molecular dynamics. The topological properties are identified through node chirality, surface states and surface Fermi arcs. Our calculations reveal that both WTeS and WTeSe are Type-I Weyl semimetals with only four Weyl nodes in the Brillouin zone, which is a minimal number in a time reversal symmetry system. This small number of Weyl nodes makes them an excellent platform to study their topological properties experimentally. The Weyl nodes are located in four different quadrants of the Brillouin zone and consequently the separation of Weyl points in reciprocal space, and the length of Fermi arc, is of the order of the magnitude of the reciprocal lattice vector |Gz| as might be easily observed in experiment. The Weyl nodes have approximately the same energy below the Fermi level and are hence accessible by conventional ARPES. In addition, under external strain, the Weyl semimetal state is more robust than the sister compounds Td-WTe2/MoTe2. Our findings are important to explore Weyl fermion physics and useful for realizing possible applications of Weyl semimetal materials in future topological electronic devices.

5.
Theranostics ; 9(18): 5298-5314, 2019.
Artigo em Inglês | MEDLINE | ID: mdl-31410216

RESUMO

Rationale: Hypoxia has been proved to contribute to aggressive phenotype of cancers, while functional and regulatory mechanism of long noncoding RNA (lncRNA) in the contribution of hypoxia on pancreatic cancer (PC) tumorigenesis is incompletely understood. The aim of this study was to uncover the regulatory and functional roles for hypoxia-induced lncRNA-MTA2TR (MTA2 transcriptional regulator RNA, AF083120.1) in the regulation of PC tumorigenesis. Methods: A lncRNA microarray confirmed MTA2TR expression in tissues of PC patients. The effects of MTA2TR on proliferation and metastasis of PC cells and xenograft models were determined, and the key mechanisms by which MTA2TR promotes PC were further dissected. Furthermore, the expression and regulation of MTA2TR under hypoxic conditions in PC cells were assessed. We also assessed the correlation between MTA2TR expression and PC patient clinical outcomes. Results: We found that metastasis associated protein 2 (MTA2) transcriptional regulator lncRNA (MTA2TR) was overexpressed in PC patient tissues relative to paired noncancerous tissues. Furthermore, we found that depletion of MTA2TR significantly inhibited PC cell proliferation and invasion both in vitro and in vivo. We further demonstrated that MTA2TR transcriptionally upregulates MTA2 expression by recruiting activating transcription factor 3 (ATF3) to the promoter area of MTA2. Consequentially, MTA2 can stabilize the HIF-1α protein via deacetylation, which further activates HIF-1α transcriptional activity. Interestingly, our results revealed that MTA2TR is transcriptionally regulated by HIF-1α under hypoxic conditions. Our clinical samples further indicated that the overexpression of MTA2TR was correlated with MTA2 upregulation, as well as with reduced overall survival (OS) in PC patients. Conclusions: These results suggest that feedback between MTA2TR and HIF-1α may play a key role in regulating PC tumorigenesis, thus potentially highlighting novel avenues PC treatment.

6.
ACS Appl Mater Interfaces ; 11(39): 35863-35870, 2019 Oct 02.
Artigo em Inglês | MEDLINE | ID: mdl-31430114

RESUMO

Bismuth (Bi), a topological material, where many interesting condensed matter phenomena have been observed, possesses unique physical properties when its thickness is reduced to thin film. Here, we prepared the highly stable, single-crystalline, continuous Bi thin film via the vapor deposition (VD) method and found that the Bi thin film can exhibit broadband, ultrafast nonlinear optical response with low saturable intensity ranging from the near-infrared to mid-infrared spectral range under strong excitation. Moreover, we demonstrated that the Bi thin film was favorable to act as a nonlinear pulse modulator toward a high performance pulsed laser operating in optical communication and mid-infrared wavelengths. The experimental results highlight the prospects of Bi thin film as broadband pulsed modulators and may open new avenues toward advanced Bi-based broadband photonic devices.

7.
Theranostics ; 9(16): 4795-4810, 2019.
Artigo em Inglês | MEDLINE | ID: mdl-31367258

RESUMO

Rationale: Emerging evidences have highlighted the critical roles of lncRNAs in human cancer development. The work sought to assess the biological role and potential underlying mechanisms of lncRNA-CF129 (CF129) which is significantly reduced in pancreatic cancer (PC). Methods: CF129 expression and its association with multiple clinicopathologic characteristics in PC specimens were analyzed. The role of CF129 both in vitro and in vivo was assessed, with RNA pull-down and immunoprecipitation assays being performed to detect the interaction between CF129 and p53 and E3 ligase MKRN1. Chromatin immunoprecipitation and luciferase assays were utilized to identify the interaction between p53 and FOXC2 promoter, HIF-1α/HDAC1 complex and CF129 promoter, FOXC2 and HIF-1α promoter, respectively. Results: CF129 levels were markedly lower in PC compared with paired non-tumor adjacent tissues. Low CF129 expression predicted short overall survival in PC patients. CF129 inhibited invasion and metastasis of PC cells in a FOXC2-dependent manner. In addition, CF129 regulates FOXC2 transcription through association with mutant p53. CF129 directly binds to p53 and E3 ligase MKRN1, and such an interaction leading to p53 protein ubiquitination and degradation. Furthermore, CF129 is a hypoxia-responsive lncRNA, which is transcriptionally downregulated by binding between HIF-1α/HDAC1 complex and CF129 promoter. Finally, it is revealed that HIF-1α is reciprocally regulated by FOXC2 in transcriptional level. Clinically, CF129 downregulation coordinates overexpression of FOXC2. Conclusions: Our study suggests that CF129 inhibits pancreatic cell proliferation and invasion by suppression of FOXC2 transcription, which depends on MKRN1-mediated ubiquitin-dependent p53 degradation. The HIF-1α/CF129/ p53/FOXC2 axis may function as a potential biomarker and therapeutic target.

8.
Can J Gastroenterol Hepatol ; 2019: 9046260, 2019.
Artigo em Inglês | MEDLINE | ID: mdl-31380321

RESUMO

Purpose: To investigate the efficacy of telbivudine (LdT) in blocking mother-to-child transmission (MTCT) of hepatitis B virus (HBV) during late pregnancy. Methods: A total of 651 pregnant women aged 18-40 in Nantong Third People's Hospital and Hospital affiliated to Nantong University with positive hepatitis B surface antigen (HBsAg) and HBV DNA were enrolled between January 2011 and December 2015. Patients with HBV DNA≥106 copies/mL (n=251) received LdT during late pregnancy according to the patients' will, while 136 high viral patients with HBV DNA≥106 copies/mL who did not take LdT therapy and 268 low viral patients with HBV DNA<106 copies/mL served as the controls. Results: At 7 months and 1 year postpartum, the basal HBV DNA serum level of treated patients declined significantly (P<0.001), while no obvious decline was observed in the untreated high viraemic controls (P<0.05) and untreated low viraemic controls (P<0.05). Only 1 infant (0.4%) in LdT group was HBsAg positive at 7 months, while 14 (5.2%) were in the untreated low viraemic controls (P<0.001) and 15 (11.0%) were in untreated high viraemic controls (P<0.001). Conclusion: For pregnant women with HBV DNA≥106 copies/mL, the use of LdT during late pregnancy could effectively reduce the MTCT rate of HBV.

9.
J Phys Chem Lett ; : 5027-5035, 2019 Aug 16.
Artigo em Inglês | MEDLINE | ID: mdl-31357864

RESUMO

Atomically thin transition-metal dichalcogenide (TMDC) heterostructures have attracted increasing attention because of their unprecedented potential in the fields of electronics and optoelectronics. However, selective growth of either lateral or vertical TMDC heterostructures remains challenging. Here, we report that lateral and vertical MoS2/MoSe2 epitaxial heterostructures can be successfully fabricated via a one-step growth strategy, which includes triggering by the concentration of sulfur precursor vapor and a high-temperature annealing process. Vertically stacked MoS2/MoSe2 heterostructures can be synthesized via control of the nucleation and growth kinetics, which is induced by high sulfur vapor concentration. The high-temperature annealing process results in the formation of fractured MoSe2 and in situ epitaxial growth of lateral MoSe2-MoS2 heterostructures. This study has revealed the importance of sulfur vapor concentration and high-temperature annealing processes in the controllable growth of MoSe2-MoS2 heterostructures, paving a new route for fabricating two-dimensional TMDC heterostructures.

10.
J Phys Condens Matter ; 31(36): 365002, 2019 Sep 11.
Artigo em Inglês | MEDLINE | ID: mdl-31100737

RESUMO

Based on first principles calculations, we study the electronic properties of heterostructures formed by a 2D ferromagnetic insulator semihydrogenated graphene (SG) and topological insulator Bi2Se3 thin films of a few quintuple layers (QLs). It is found that the unsaturated C atoms in SG form bonds with Se atoms in Bi2Se3 thin film and the top surface states (at the interface) are strongly hybridized with SG. Due to breaking of time-reversal symmetry, the surface states open gaps of 40 meV and 150 meV for SG/3QL-Bi2Se3 and SG/5QL-Bi2Se3 heterostructures, respectively. Furthermore, a giant Rashba spin splitting is found induced by the SG layer.

11.
Mol Med Rep ; 19(5): 3575-3583, 2019 May.
Artigo em Inglês | MEDLINE | ID: mdl-30864742

RESUMO

MicroRNAs (miRNA/miRs) have been demonstrated to be critical post­transcriptional modulators of gene expression during tumorigenesis. Numerous miRNAs have been revealed to be downregulated in human epithelial ovarian cancer (EOC). In the present study, it was observed that the expression of miR­145 was decreased in EOC tissues and cell lines. Overexpression of miR­145 inhibited the proliferation, migration and invasion of EOC cells. The D­type cyclin 2, cyclin D2 (CCND2), and E2F transcription factor 3 (E2F3) were confirmed to be targets of miR­145. In addition, restoration of these 2 genes significantly reversed the tumor suppressive effects of miR­145. Collectively, the results indicated that miR­145 serves a critical role in suppressing the biological behavior of EOC cells by targeting CCND2 and E2F3. Therefore, miR­145 was suggested to be a potential miRNA­based therapeutic target in ovarian cancer.


Assuntos
Ciclina D2/genética , Fator de Transcrição E2F3/genética , Regulação Neoplásica da Expressão Gênica , MicroRNAs/genética , Neoplasias Ovarianas/genética , Neoplasias Ovarianas/patologia , Interferência de RNA , Regiões 3' não Traduzidas , Adulto , Idoso , Ciclo Celular/genética , Linhagem Celular Tumoral , Movimento Celular/genética , Proliferação de Células , Feminino , Genes Reporter , Humanos , Pessoa de Meia-Idade
12.
Cancer Biother Radiopharm ; 34(2): 110-118, 2019 Mar.
Artigo em Inglês | MEDLINE | ID: mdl-30376358

RESUMO

BACKGROUND: Circular RNAs (circRNAs) comprise a class of noncoding RNA molecules that play an important role in several normal cellular functions, as well as tumorigenesis in humans. However, the expression patterns and biological functions of circRNAs in ovarian cancer (OC) remain unclear. METHODS: Therefore, we investigated the expression profiles and biological functions of certain circRNAs in OC tumor tissues. The expression of three circRNAs (VPS13C-has-circ-001567, RAD50-has-circ-00718, and SPECC1-has-circ-000013) was detected by real-time polymerase chain reaction in OC cell lines, and also in tumor and pericarcinous tissues obtained from 20 patients with OC. The function of VPS13C-has-circ-001567 in SKOV3 and OV-1063 cells was investigated by knockdown of VPS13C-has-circ-001567 and then analyzing any resultant effects on the cell cycle, cell proliferation, apoptosis, and cell invasion ability. E-cadherin and N-cadherin expressions were analyzed by immunofluorescence and western blotting. Finally, the tumorigenicity of OC cells was assessed in nude mice. RESULTS: The results showed that VPS13C-has-circ-001567 was expressed at significantly higher levels in OC tumor tissues compared with pericarcinous tissues, and this overexpression was associated with tumor node metastasis stage and lymph node metastasis. We found that knockdown of VPS13C-has-circ-001567 significantly promoted apoptosis and inhibited the proliferation of SKOV3 and OV-1063 cells in vitro. Knockdown of VPS13C-has-circ-001567 led to cell cycle arrest at G1 phase and decreased the percentage of S1 phase cells. Additionally, knockdown of VPS13C-has-circ-001567 decreased the invasion ability of SKOV3 and OV-1063 cells, and also changed the levels of E-cadherin and N-cadherin expressions. Knockdown of VPS13C-has-circ-001567 significantly reduced the tumorigenicity of OC cells. CONCLUSIONS: Taken together, our results suggest that VPS13C-has-circ-001567 plays a role in the development of OC and might be a prognostic marker and therapeutic target for OC.


Assuntos
Neoplasias Ovarianas/genética , Neoplasias Ovarianas/metabolismo , RNA/biossíntese , RNA/genética , Proteínas de Ciclo Celular , Linhagem Celular Tumoral , Proliferação de Células/fisiologia , Enzimas Reparadoras do DNA/genética , Proteínas de Ligação a DNA/genética , Feminino , Humanos , Invasividade Neoplásica , Proteínas Nucleares/genética , Neoplasias Ovarianas/patologia , Proteínas/genética , Regulação para Cima
13.
Cancer Res ; 79(7): 1398-1412, 2019 04 01.
Artigo em Inglês | MEDLINE | ID: mdl-30563888

RESUMO

Cancer cells are known to undergo metabolic reprogramming, such as glycolysis and glutamine addiction, to sustain rapid proliferation and metastasis. It remains undefined whether long noncoding RNAs (lncRNA) coordinate the metabolic switch in pancreatic cancer. Here we identify a nuclear-enriched antisense lncRNA of glutaminase (GLS-AS) as a critical regulator involved in pancreatic cancer metabolism. GLS-AS was downregulated in pancreatic cancer tissues compared with noncancerous peritumor tissues. Depletion of GLS-AS promoted proliferation and invasion of pancreatic cancer cells both in vitro and in xenograft tumors of nude mice. GLS-AS inhibited GLS expression at the posttranscriptional level via formation of double stranded RNA with GLS pre-mRNA through ADAR/Dicer-dependent RNA interference. GLS-AS expression was transcriptionally downregulated by nutrient stress-induced Myc. Conversely, GLS-AS decreased Myc expression by impairing the GLS-mediated stability of Myc protein. These results imply a reciprocal feedback loop wherein Myc and GLS-AS regulate GLS overexpression during nutrient stress. Ectopic overexpression of GLS-AS inhibited proliferation and invasion of pancreatic cancer cells by repressing the Myc/GLS pathway. Moreover, expression of GLS-AS and GLS was inversely correlated in clinical samples of pancreatic cancer, while low expression of GLS-AS was associated with poor clinical outcomes. Collectively, our study implicates a novel lncRNA-mediated Myc/GLS pathway, which may serve as a metabolic target for pancreatic cancer therapy, and advances our understanding of the coupling role of lncRNA in nutrition stress and tumorigenesis.Significance: These findings show that lncRNA GLS-AS mediates a feedback loop of Myc and GLS, providing a potential therapeutic target for metabolic reprogramming in pancreatic cancer.Graphical Abstract: http://cancerres.aacrjournals.org/content/canres/79/7/1398/F1.large.jpg.See related commentary by Mafra and Dias, p. 1302.


Assuntos
Neoplasias Pancreáticas/genética , RNA Longo não Codificante/genética , Animais , Glutaminase , Camundongos , Camundongos Nus , Nutrientes
14.
Biochem Biophys Res Commun ; 509(2): 448-454, 2019 02 05.
Artigo em Inglês | MEDLINE | ID: mdl-30594392

RESUMO

Thousands of lncRNAs have been identified but few have been functionally characterized in triple negative breast cancer (TNBC). LINC00152 was known as cytoskeleton regulator RNA (CYTOR) and expressed in various cancers including breast cancer. But the underlying molecular mechanism of LINC00152 in pathogenesis of TNBC have not been elucidated. In our study, we identified that LINC00152 expression was dramatically elevated in TNBC tissue and cells. Inhibition or overexpression of LINC00152 obviously increased or suppressed PTEN protein expression but did not affect the mRNA expression level. Our further experiments showed up-regulated LINC00152 in TNBC obviously enhanced NEDD4-1 mediated ubiquitination and degradation of PTEN protein. Finally, we demonstrated that YY1 bound with LINC00152 promotor and mostly inhibited the transcription of LINC00152. Furthermore, analysis of clinical samples resource retrieved from databases suggested high LINC00152 expression was correlated with ER or PR negative expression, late TNM stage and lymphatic invasion, as well as shorter overall survival time in patients. Consequently, this study firstly reveals that up-regulated LINC00152 mediates PTEN protein stability attenuation in TNBC.


Assuntos
Regulação Neoplásica da Expressão Gênica , PTEN Fosfo-Hidrolase/genética , RNA Longo não Codificante/genética , Neoplasias de Mama Triplo Negativas/genética , Fator de Transcrição YY1/genética , Sítios de Ligação , Linhagem Celular Tumoral , Movimento Celular , Proliferação de Células , Progressão da Doença , Feminino , Genes Reporter , Humanos , Luciferases/genética , Luciferases/metabolismo , Metástase Linfática , Ubiquitina-Proteína Ligases Nedd4/genética , Ubiquitina-Proteína Ligases Nedd4/metabolismo , PTEN Fosfo-Hidrolase/metabolismo , Ligação Proteica , Estabilidade Proteica , Proteólise , RNA Longo não Codificante/antagonistas & inibidores , RNA Longo não Codificante/metabolismo , Transdução de Sinais , Análise de Sobrevida , Neoplasias de Mama Triplo Negativas/diagnóstico , Neoplasias de Mama Triplo Negativas/mortalidade , Neoplasias de Mama Triplo Negativas/patologia , Ubiquitinação , Fator de Transcrição YY1/metabolismo
15.
Phys Rev Lett ; 121(17): 175701, 2018 Oct 26.
Artigo em Inglês | MEDLINE | ID: mdl-30411915

RESUMO

The energy landscape of carbon is exceedingly complex, hosting diverse and important metastable phases, including diamond, fullerenes, nanotubes, and graphene. Searching for structures, especially those with large unit cells, in this landscape is challenging. Here we use a combined stochastic search strategy employing two algorithms (ab initio random structure search and random sampling strategy combined with space group and graph theory) to apply connectivity constraints to unit cells containing up to 100 carbon atoms. We uncover three low energy carbon polymorphs (Pbam-32, P6/mmm, and I4[over ¯]3d) with new topologies, containing 32, 36, and 94 atoms in their primitive cells, respectively. Their energies relative to diamond are 96, 131, and 112 meV/atom, respectively, which suggests potential metastability. These three carbon allotropes are mechanically and dynamically stable, insulating carbon crystals with superhard mechanical properties. The I4[over ¯]3d structure possesses a direct band gap of 7.25 eV, which is the widest gap in the carbon allotrope family. Silicon, germanium, and tin versions of Pbam-32, P6/mmm, and I4[over ¯]3d also show energetic, dynamical, and mechanical stability. The computed electronic properties show that they are potential materials for semiconductor and photovoltaic applications.

16.
Nanotechnology ; 29(48): 484003, 2018 Nov 30.
Artigo em Inglês | MEDLINE | ID: mdl-30207548

RESUMO

Recently, two-dimensional (2D) transition-metal dichalcogenides (TMDCs) have attracted much attention due to their promising applications in the fields of electronics and optoelectronics. Controllable growth of TMDC heterostructures stimulates new interest by tuning their optical and electronic properties. Herein, large-scale lateral MoSe2-MoS2 and MoSe2(1-x)S2x -MoS2 heterostructures have been synthesized through one-step epitaxial ambient-pressure chemical vapor deposition method and we found that the growth time plays an important role in the formation of lateral heterostructures. Lateral MoSe2-MoS2 heterostructures have been systematically characterized by using atomic force microscopy, Raman spectroscopy and photoluminescence spectroscopy. Corresponding surface potential and charge distributions of MoSe2-MoS2 heterostructures have been investigated by employing Kelvin probe force microscopy. We found that the electrostatic properties of MoSe2-MoS2 heterostructures can be effectively tuned by injecting charges through conductive atomic force microscopy. Our results pave a new route for constructing 2D lateral heterostructures toward electronic and optoelectronic applications.

17.
J Phys Condens Matter ; 30(36): 365001, 2018 Sep 12.
Artigo em Inglês | MEDLINE | ID: mdl-30063031

RESUMO

Based on first-principles calculations, the structure, electronic and magnetic properties of unilateral halogenated silicene Si2X1 (X = F, Cl, Br, I) are investigated. The formation energies of all the configurations of studied Si2X1 (X = F, Cl, Br, I) are found to be lower than that in pristine silicene, which indicates the strong stability. The band structure of half-fluorinated configuration Si2F1 presents metallic property, while other unilateral halogenated silicene Si2X1 (X = Cl, Br, I) exhibits half-metallic properties. In unilateral halogenated silicene Si2X1 (X = Cl, Br, I), the unpaired electrons in unsaturated silicon atom produce the localized magnetic moment. However, due to the strong electronegativity in F atom, the half-fluorinated silicene Si2F1 is almost non-magnetic. The metallic property of Si2F1 configuration can be tuned to half-metallic by applying biaxial tensile strain from 11.95% to 13.51%. Furthermore, applying biaxial tensile strains can tune the half-metallic property of unilateral halogenated silicene Si2X1 (X = Cl, Br, I) to a semiconductor. This half-metallic property in unilateral halogenated silicene Si2X1 (X = Cl, Br, I) can be recovered and can even be tuned to metallic if continually increasing the biaxial tensile strains.

18.
Nanoscale ; 10(35): 16759-16764, 2018 Sep 13.
Artigo em Inglês | MEDLINE | ID: mdl-30156239

RESUMO

A thickness dependent band gap is commonly found in layered two-dimensional (2D) materials. Here, using a C3N bilayer as a prototypical model, we systematically investigated the evolution of a band gap from a single layer to a bilayer using first principles calculations and tight binding modeling. We show that in addition to the widely known effect of interlayer hopping, de-charge transfer also plays an important role in tuning the band gap. The de-charge transfer is defined with reference to the charge states of atoms in the single layer without stacking, which shifts the energy level and modifies the band gap. Together with band edge splitting induced by the interlayer hopping, the energy level shifting caused by the de-charge transfer determines the size of the band gap in bilayer C3N. Our finding, applicable to other 2D semiconductors, provides an alternative approach for realizing band gap engineering in 2D materials.

19.
Oncogene ; 37(44): 5811-5828, 2018 11.
Artigo em Inglês | MEDLINE | ID: mdl-29970904

RESUMO

The contribution of long noncoding RNAs (lncRNAs) to pancreatic cancer progression and the regulatory mechanisms of their expression are attractive areas. In the present study, the overexpression of lncRNA-BX111887 (BX111) in pancreatic cancer tissues was detected by microarray and further validated in a cohort of pancreatic cancer tissues. We further demonstrated that knockdown or overexpression of BX111 dramatically repressed or enhanced proliferation and invasion of pancreatic cancer cells. Mechanically, BX111 activated transcription of ZEB1, a key regulator for epithelia-mesenchymal transition (EMT), via recruiting transcriptional factor Y-box protein (YB1) to its promoter region. Moreover, we revealed that BX111 transcription was induced by hypoxia-inducible factor (HIF-1α) in response to hypoxia. In addition, BX111 contributed to the hypoxia-induced EMT of pancreatic cells by regulating expression of ZEB1 and its downstream proteins E-cadherin and MMP2. Coincidence with in vitro results, BX111 depletion effectively inhibited growth and metastasis of xenograft tumor in vivo. The clinical samples of pancreatic cancer further confirmed a positive association between BX111 and ZEB1. Moreover, high BX111 expression was correlated with late TNM stage, lymphatic invasion and distant metastasis, as well as short overall survival time in patients. Taken together, our findings implicate a hypoxia-induced lncRNA contributes to metastasis and progression of pancreatic cancer, and suggest BX111 might be applied as a potential biomarker and therapeutic target for pancreatic cancer.


Assuntos
Regulação Neoplásica da Expressão Gênica , Neoplasias Pancreáticas/genética , RNA Longo não Codificante/fisiologia , Homeobox 1 de Ligação a E-box em Dedo de Zinco/genética , Animais , Hipóxia Celular , Linhagem Celular Tumoral , Progressão da Doença , Transição Epitelial-Mesenquimal/genética , Transição Epitelial-Mesenquimal/fisiologia , Humanos , Fator 1 Induzível por Hipóxia/genética , Fator 1 Induzível por Hipóxia/metabolismo , Subunidade alfa do Fator 1 Induzível por Hipóxia/genética , Subunidade alfa do Fator 1 Induzível por Hipóxia/metabolismo , Metástase Linfática , Camundongos , Camundongos Endogâmicos BALB C , Camundongos Nus , Neoplasias Pancreáticas/metabolismo , Neoplasias Pancreáticas/fisiopatologia , Neoplasias Pancreáticas/secundário , RNA Longo não Codificante/metabolismo , Transcrição Genética , Proteína 1 de Ligação a Y-Box/genética , Proteína 1 de Ligação a Y-Box/metabolismo , Homeobox 1 de Ligação a E-box em Dedo de Zinco/metabolismo
20.
Phys Chem Chem Phys ; 20(25): 17387-17392, 2018 Jun 27.
Artigo em Inglês | MEDLINE | ID: mdl-29905350

RESUMO

We have studied the stable geometries, band structures and magnetic properties of transition-metal (V, Cr, Mn, Fe, Co and Ni) atoms absorbed on MoS2/h-BN heterostructure systems by first-principles calculations. By comparing the adsorption energies, we find that the adsorbed transition metal (TM) atoms prefer to stay on the top of Mo atoms. The results of the band structure without spin-orbit coupling (SOC) interaction indicate that the Cr-absorbed systems behave in a similar manner to metals, and the Co-absorbed system exhibits a half-metallic state. We also deduce that the V-, Mn-, Fe-absorbed systems are semiconductors with 100% spin polarization at the HOMO level. The Ni-absorbed system is a nonmagnetic semiconductor. In contrast, the Co-absorbed system exhibits metallic state, and the bandgap of V-absorbed system decreases slightly according to the SOC calculations. In addition, the magnetic moments of all the six TM atoms absorbed on the MoS2/h-BN heterostructure systems decrease when compared with those of their free-standing states.

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