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1.
Chemistry ; 30(18): e202303919, 2024 Mar 25.
Artigo em Inglês | MEDLINE | ID: mdl-38263478

RESUMO

Encouraged by the successful fabrication of C60-GNR (GNR=graphene nanoribbon) single-molecule transistors in experiments, four Fe-containing derived double-layered devices of Fe@C60-GNR are designed by employing different electrode linkages and their transport properties are investigated by using density functional theory (DFT) and nonequilibrium Green's function (NEGF) methods. Regardless of electrode connection, all these devices give rise to a smaller negative differential resistance (NDR) peak at V=0.2 and a higher peak at 1.2 V, suggesting their stable maneuverability as molecular devices and good candidates for developing on(off)-off(on)-on(off) current switches. The macroscopic NDR performance depends on the delocalization character and the crossing mechanism of the frontier orbitals. The peak-to-valley current ratios (Rmax) range from 454 to 2737, determined by the electrode linkage. Such a large Rmax-value is necessary for developing dynamic random-access memory (DRAM) cells. Encapsulating the Fe atom inside C60 not only improves the conductivity but also introduces the spin-polarized transport property. The spin-filtering efficiency (SFE) of almost all devices oscillates up and down in response to the bias voltage, indicating the possibility of designing on(off)-off(on)-on(off) spin switches and up-down spin switches. All these fascinating properties provide an important clue for designing similar molecular devices with multiple functions by trapping magnetic transition metal atoms inside fullerenes.

2.
J Mater Sci Mater Med ; 35(1): 35, 2024 Jun 20.
Artigo em Inglês | MEDLINE | ID: mdl-38900360

RESUMO

Bioabsorbable sutures can improve the medical functions of existing non-absorbable sutures, and may produce new medical effects, and are expected to become a new generation of medical degradable materials. In this study, the cytocompatibility of triclosan coated polyglactin910 sutures (CTS-PLGA910) was analyzed and different concentrations of sutures were prepared. The effects of sutures on the cytotoxicity and cell proliferation of HUVEC were studied by CCK-8 assay. The hemolysis, total antioxidant capacity (T-AOC) activity and nitric oxide (NO) content were investigated to improve the blood compatibility of sutures. The results showed that the hemolysis rate of CTS-PLGA910 was less than 5%. After treatment on HUVEC cells for 48 and 72 h, there was no significant change in NO content in CTS-PLGA910 groups compared with the control group, while T-AOC activity and antioxidant capacity were significantly increased in medium and high dose groups. In summary, the blood compatibility and cell compatibility were significantly improved, which provided a basis for the clinical application of sutures in the future.


Assuntos
Proliferação de Células , Materiais Revestidos Biocompatíveis , Células Endoteliais da Veia Umbilical Humana , Teste de Materiais , Poliglactina 910 , Suturas , Triclosan , Humanos , Triclosan/farmacologia , Triclosan/química , Poliglactina 910/química , Materiais Revestidos Biocompatíveis/química , Materiais Revestidos Biocompatíveis/farmacologia , Proliferação de Células/efeitos dos fármacos , Hemólise/efeitos dos fármacos , Antioxidantes/farmacologia , Antioxidantes/química , Materiais Biocompatíveis/química , Óxido Nítrico/metabolismo , Sobrevivência Celular/efeitos dos fármacos
3.
Hum Brain Mapp ; 44(9): 3730-3743, 2023 06 15.
Artigo em Inglês | MEDLINE | ID: mdl-37042391

RESUMO

Anxiety is characterized by altered brain networks. Directional information flows among dynamic brain networks concerning neuropathogenesis of anxiety have not yet been investigated. The role of directional influences between networks in gene-environment effects on anxiety remains to be further elucidated. In a large community sample, this resting-state functional MRI study estimated dynamic effective connectivity among large-scale brain networks based on a sliding-window approach and Granger causality analysis, providing dynamic and directional information for signal transmission in networks. We first explored altered effective connectivity among networks related to anxiety in distinct connectivity states. Due to the potential gene-environment effects on brain and anxiety, we further performed mediation and moderated mediation analyses to investigate the role of altered effective connectivity networks in relationships between polygenic risk scores, childhood trauma, and anxiety. State and trait anxiety scores showed correlations with altered effective connectivity among extensive networks in distinct connectivity states (p < .05, uncorrected). Only in a more frequent and strongly connected state, there were significant correlations between altered effective connectivity networks and trait anxiety (PFDR <0.05). Furthermore, mediation and moderated mediation analyses showed that the effective connectivity networks played a mediating role in the effects of childhood trauma and polygenic risk on trait anxiety. State-dependent effective connectivity changes among brain networks were significantly related to trait anxiety, and mediated gene-environment effects on trait anxiety. Our work sheds novel light on the neurobiological mechanisms underlying anxiety, and provides new insights into early objective diagnosis and intervention evaluation.


Assuntos
Mapeamento Encefálico , Imageamento por Ressonância Magnética , Humanos , Encéfalo , Ansiedade/diagnóstico por imagem , Transtornos de Ansiedade
4.
J Magn Reson Imaging ; 55(4): 1171-1180, 2022 04.
Artigo em Inglês | MEDLINE | ID: mdl-34487595

RESUMO

BACKGROUND: Corticospinal tract (CST) injury has been shown to exert a major influence on functional recovery after ischemic stroke. PURPOSE: To evaluate the prognostic value of CST injury estimated using a recent developed tractometry-based method. STUDY TYPE: Prospective. POPULATION: Forty-eight patients with CST damage induced by stroke lesion who underwent brain magnetic resonance imaging within 7 days from onset. SEQUENCE: Diffusion-weighted imaging (b = 1000 seconds/mm2 ) and diffusion kurtosis imaging (DKI) spin-echo echo-planar sequence with three b-values (0, 1250, and 2500 seconds/mm2 ) at 3.0 T. ASSESSMENT: A recently developed approach that combines tract segmentation and orientation mapping was used for CST-specific tractography and tractometry. CST injury was estimated using the proposed method with diffusion metrics extracted from DKI sequence and with the first principal component (PC1) of the metrics. We also calculated the weighted lesion load (wLL) for comparison. Clinical evaluation included the National Institutes of Health Stroke Score in the acute phase and the modified Rankin scale at 3 months post-stroke. The correlations between CST injury and initial motor impairment, as well as the prognostic values of CST injury for functional outcomes were evaluated. STATISTICAL TESTS: Pearson correlation and logistic regression. Area under the receiver operating characteristic curve. P < 0.05 was considered statistically significant. RESULTS: CST injury calculated with diffusion metrics except fractional anisotropy all showed significant correlations with initial motor impairment. PC1 achieved the largest correlation coefficient (R = 0.65) compared with wLL and other diffusion metrics. In addition to wLL, DKI_AK, AFD_total, and PC1 maximum all showed predictive values for functional outcomes. DATA CONCLUSION: Structural injury to CST is important for the assessment of the extent of injury and the prediction of functional outcome. The method proposed in our study could provide an imaging indicator to quantify the CST injury after ischemic stroke. LEVEL OF EVIDENCE: 2 TECHNICAL EFFICACY: Stage 1.


Assuntos
AVC Isquêmico , Acidente Vascular Cerebral , Imagem de Tensor de Difusão , Humanos , Estudos Prospectivos , Tratos Piramidais/diagnóstico por imagem , Acidente Vascular Cerebral/diagnóstico por imagem
5.
Mol Biol Rep ; 49(9): 8715-8725, 2022 Sep.
Artigo em Inglês | MEDLINE | ID: mdl-35781603

RESUMO

BACKGROUND: Presently, liver transplantation is the only treatment strategy for liver failure (LF). Although granulocyte-colony stimulating factor (G-CSF) exhibits protective functions in LF, it is not clear whether it directly affects the liver cells. METHODS AND RESULTS: We established an injured liver cell model and observed that G-CSF treatment promoted cell viability and enhanced Ki67 and VEGF-A expression. Thereafter, human umbilical vein endothelial cells (HUVECs) were cultured in a conditioned medium collected from the G-CSF-treated injured liver cells. HUVECs' proliferation and tubule formation were promoted. Furthermore, in an injured liver mouse model, confirmed via haematoxylin-eosin staining, we evaluated serum alanine aminotransferase activity, Ki67 expression, and microvessel density (MVD). G-CSF treatment significantly relieved liver injury, upregulated Ki67 expression, and enhanced MVD in the injured mouse liver tissue. Additionally, AKT and ERK signal targets were explored, and it was demonstrated that the effects of G-CSF on injured liver cells were mediated through the AKT and ERK signalling pathways. CONCLUSIONS: G-CSF promotes injured liver viability and angiogenesis by directly affecting injured liver cells via the AKT and ERK signalling pathways. These findings improve our understanding of the role of G-CSF in recovery from LF.


Assuntos
Fator Estimulador de Colônias de Granulócitos , Proteínas Proto-Oncogênicas c-akt , Animais , Fator Estimulador de Colônias de Granulócitos/farmacologia , Células Endoteliais da Veia Umbilical Humana/metabolismo , Humanos , Antígeno Ki-67 , Fígado/metabolismo , Camundongos , Neovascularização Patológica/tratamento farmacológico , Proteínas Proto-Oncogênicas c-akt/metabolismo
6.
Int J Mol Sci ; 23(14)2022 Jul 10.
Artigo em Inglês | MEDLINE | ID: mdl-35886977

RESUMO

Janus Sb and Bi monolayers as a new class of 2D topological insulator materials, which could be fulfilled by asymmetrical functionalizations with methyl or hydroxyl, are demonstrated by first-principles spin-orbit coupling (SOC) electronic structure calculations to conflate nontrivial topology, Rashba splitting and valley-contrast circular dichroism. Cohesive energies and phonon frequency dispersion spectra indicate that all Janus Sb and Bi monolayers possess a structural stability in energetic statics but represent virtual acoustic phonon vibrations of the hydrogen atoms passivating on monolayer surfaces. Band structures of Janus Sb and Bi monolayers and their nanoribbons demonstrate they are nontrivial topological insulators. Rashba spin splitting at G point in Brillouin zone of Janus Bi monolayers arises from the strong SOC px and py orbitals of Bi bonding atoms together with the internal out-of-plane electric field caused by asymmetrical functionalization. Janus Sb and Bi monolayers render direct and indirect giant bandgaps, respectively, which are derived from the strong SOC px and py orbitals at band-valley Brillouin points K and K' where valley-selective circular dichroism of spin valley Hall insulators is also exhibited.


Assuntos
Eletrônica , Fônons , Eletricidade , Meio Ambiente
7.
Anal Bioanal Chem ; 413(27): 6877-6887, 2021 Nov.
Artigo em Inglês | MEDLINE | ID: mdl-34595555

RESUMO

A study was carried out to investigate the binding mode of aptamer to ampicillin (AMP) and its electrochemical response behavior. The binding mode was confirmed using the molecular dynamics (MD) simulation method to obtain the corresponding binding dynamic change process. Following the confirmed binding mode, a qualitative elucidation was provided on the electrochemical response characteristics of a single-probe aptamer-based folding sensor. The results show that there exist two different binding modes in two different solution systems, Phys2 and H2O (0.1 M NaCl). These two binding modes can respectively induce two different contraction changes, thereby driving the methylene blue (MB)-modified aptamer probe to show a "close-to-interface" convergence behavior with different degrees on the actual electrode surface, which validates two apparently different electrochemical response behavior characteristics of "signal-on" for the sensor. By contrast, H2O (0.1 M NaCl) as the reaction medium is more conducive to the formation of a stable aptamer/AMP complex and the development of a high-sensitivity analytical method with a low detection limit of 0.033 µM. The simulation results effectively support the experimental results, which is helpful in gaining a deeper understanding of the relationship between the signaling mechanism and practical analytical performance for aptamer-based folding sensors at the molecular level.

8.
Molecules ; 26(4)2021 Feb 22.
Artigo em Inglês | MEDLINE | ID: mdl-33671512

RESUMO

The electronic structures and transition properties of three types of triangle MoS2 clusters, A (Mo edge passivated with two S atoms), B (Mo edge passivated with one S atom), and C (S edge) have been explored using quantum chemistry methods. The highest occupied molecular orbital (HOMO)-lowest unoccupied molecular orbital (LUMO) gap of B and C is larger than that of A, due to the absence of the dangling of edge S atoms. The frontier orbitals (FMOs) of A can be divided into two categories, edge states from S3p at the edge and hybrid states of Mo4d and S3p covering the whole cluster. Due to edge/corner states appearing in the FMOs of triangle MoS2 clusters, their absorption spectra show unique characteristics along with the edge structure and size.


Assuntos
Teoria da Densidade Funcional , Dissulfetos/química , Molibdênio/química , Eletrônica , Modelos Moleculares , Tamanho da Partícula , Propriedades de Superfície
9.
J Magn Reson Imaging ; 51(4): 1162-1169, 2020 04.
Artigo em Inglês | MEDLINE | ID: mdl-31448477

RESUMO

BACKGROUND: Previous studies have found widespread impairment of white matter (WM) integrity and disruption of structural network connectivity in cerebral small-vessel disease, but have not evaluated these changes jointly in nondemented patients. PURPOSE: To jointly investigate the microstructural impairment of WM and the related alterations of structural network topology in nondemented cerebral small-vessel disease (CSVD-ND). STUDY TYPE: Prospective. POPULATION: Thirty-seven CSVD-ND patients and 34 elderly controls, who were age-, sex-, and education-matched. FIELD STRENGTH/SEQUENCE: 3.0T/diffusion tensor imaging (DTI). ASSESSMENT: Clinical characteristics, lacunar infarct, and white matter hyperintensity (WMH) was assessed. A multiatlas likelihood fusion (MALF) algorithm was used for DTI-based brain segmentation and network node defining. Then the alterations of WM integrity and structural network topology were investigated jointly. STATISTICAL TESTS: Student's t-test, chi-square test, Mann-Whitney U-test, linear regression, Pearson correlation, and multiple comparison correction. RESULTS: Decreased fractional anisotropy and increased trace values were observed in predefined structures (P < 0.05, familywise error rate-corrected), including major commissural fibers, projection fibers, and some association fibers. Topologically, both groups showed small-worldness. CSVD-ND patients showed reduced global and local efficiency (P < 0.001). Despite widespread impairment of WM integrity, CSVD-ND patients only showed reduced nodal efficiency in the right superior occipital gyrus and the right lingual gyrus (P < 0.05, familywise error rate-corrected). The nodal local efficiency of the right precuneus was associated with the processing speed after adjusting the effect of lacunar infarct and WMH (r = -0.499, P = 0.038). DATA CONCLUSION: WM integrity was widely impaired in nondemented CSVD patients but structural network connectivity was relatively preserved. DTI may potentially provide information for the pathophysiology of CSVD in the nondemented phase. LEVEL OF EVIDENCE: 1 Technical Efficacy: Stage 3 J. Magn. Reson. Imaging 2020;51:1162-1169.


Assuntos
Doenças de Pequenos Vasos Cerebrais , Substância Branca , Idoso , Doenças de Pequenos Vasos Cerebrais/diagnóstico por imagem , Cognição , Imagem de Tensor de Difusão , Humanos , Estudos Prospectivos , Substância Branca/diagnóstico por imagem
10.
Anal Bioanal Chem ; 412(11): 2391-2397, 2020 Apr.
Artigo em Inglês | MEDLINE | ID: mdl-32076786

RESUMO

By adding 6 thymines to lengthen the parent aptamer combined with the change of "on" and "off" induced by the target for an assistant stem-loop DNA probe (ASP-SLP-MB), a new folding-type electrochemical kanamycin (Kana) aptamer-engineering dual-probe-based sensor (sensor d) was developed. By purposefully reducing the background current and increasing the electron transfer efficiency of methylene blue (MB), the sensor obtained significantly enhanced detection sensitivity compared with non-aptamer-engineering one-probe-based sensor (sensor a). Such efficacy was validated by a big decrease from 530.6 to 210.2 nA for the background current signal and from 360 to 0.3 nM for the detection limit. In addition to the improved sensitivity, the sensor also exhibited good selectivity, anti-fouling detection performance, and potential quantitative analysis ability, showing a feasible potential practical analytical application in real-life complicated samples, for example, milk and serum. The released results prove that the aptamer-engineering method is effective in improving the analytical performance of folding-type sensors and provides a methodological guidance for the design and fabrication of other high-performance folding-type aptasensors. Graphical abstract.


Assuntos
Antibacterianos/análise , Aptâmeros de Nucleotídeos/química , Técnicas Biossensoriais/métodos , Canamicina/análise , Leite/química , Animais , Antibacterianos/sangue , Bovinos , Sondas de DNA/química , Técnicas Eletroquímicas/métodos , Canamicina/sangue , Hibridização de Ácido Nucleico
11.
Phys Chem Chem Phys ; 22(37): 21412-21420, 2020 Sep 30.
Artigo em Inglês | MEDLINE | ID: mdl-32940302

RESUMO

Using the density functional theory (DFT) calculations, we find that  Janus group-III chalcogenide monolayers can serve as a suitable substrate for silicene, and the Dirac electron band properties of silicene are also fully preserved. The maximum opened band gap can reach 179 meV at the Dirac point due to the interaction of silicene and the polar two-dimensional (2D) substrate. In addition, the electronic band structure of the heterostructure can be modulated by applying an electric field where its predicted band gap increases or decreases according to the direction of the applied external electric field. Furthermore, an insight into the electron structures can be understood by analyzing the electron energy-loss (EEL) spectra. From these results, we also predict that heterostructures with polar 2D substrates have broad application prospects in multi-functional devices. Besides, Janus group-III chalcogenide monolayers can be used as good substrates for growing silicene and the modulation of the electronic structure can also be applied to nanodevices and optoelectronic devices.

12.
Zhonghua Yi Xue Yi Chuan Xue Za Zhi ; 37(4): 415-418, 2020 Apr 10.
Artigo em Zh | MEDLINE | ID: mdl-32219825

RESUMO

OBJECTIVE: To detect potential variant in an ethical Han Chinese pedigree affected with breast cancer. METHODS: The proband and her relatives were subjected to next-generation sequencing using a target capture sequencing kit containing 121 cancer-related genes. Candidate variants were selected by analysis of their type, frequency in population, and segregation with the phenotype. Candidate variant was verified by Sanger sequencing and TA cloning. RESULTS: A c.2013_2014ins GT variant was detected in the BRCA1 gene among all breast cancer patients from this pedigree but not among healthy females. The variant was not recorded in the 1000 Genome Project database or the Exome Aggregation Consortium (ExAC) database. The frameshifting insertion was predicted to form an premature stop codon in gene transcript and can give rise to a truncated protein. CONCLUSION: The BRCA1 c.2013_2014ins GT variant probably underlies the pathogenesis of breast cancer in this Chinese pedigree.


Assuntos
Proteína BRCA1/genética , Neoplasias da Mama/genética , Povo Asiático , Exoma , Feminino , Sequenciamento de Nucleotídeos em Larga Escala , Humanos , Linhagem , Fenótipo
13.
Pak J Med Sci ; 36(6): 1382-1386, 2020.
Artigo em Inglês | MEDLINE | ID: mdl-32968413

RESUMO

OBJECTIVE: To discuss the correlation between hormone levels and cardiovascular autonomic neuropathy (CAN) in menopausal patients with Type-2 diabetes mellitus (T2DM). METHODS: This clinical research study was conducted at Department of Endocrinology, Baoding No. 1 Hospital from January 2016 to December 2017. In this study a total of 386 menopausal female patients with T2 DM were selected and classified into two groups according to the CAN function test: the CAN group (80 cases) and the DM group (306 cases). The Kupperman score (KI integral) was calculated for all participants in the study, and the following indexes were measured: body mass index (BMI), blood estrogen (E2), follicle-stimulating hormone (FSH), luteinizing hormone (LH), thyroid-stimulating hormone (TSH), free thyroxine (FT4), free triiodothyronine (FT3), fasting blood-glucose (FBG), glycosylated hemoglobin (HbA1c), serum lipids, uric acid (SUA), hypersensitive c-reactive protein (CRP), etc. RESULTS: The FBG, HbA1c, TGs, Hs-CRP, SUA, KI score, TSH, FSH and LH of the CAN group were obviously higher than the same parameters in the DM group (P<0.01, P<0.05), while HDL-C, E2, FT3 and FT4 were significantly lower (Pπ.01, Pπ.05). Pearson correlation analysis indicated that CAN presents a positive correlation with HbA1c, TGs, hs-CRP and SUA and a negative correlation with HDL-C and E2, and the difference was statistically significant (P<0.05). The multifactor logistic regression analysis results showed that HbA1c (OR=3.980, 95%CI=1.268~10.319) and E2 (OR=3.075, 95%CI=1.167~7.366) are independent risk factors for CAN. CONCLUSION: The CAN morbidity of menopausal female patients with T2DM is high, and HbA1c and E2 should be mainly monitored to identify and treat CAN early.

14.
Eur Radiol ; 29(3): 1203-1210, 2019 Mar.
Artigo em Inglês | MEDLINE | ID: mdl-30105412

RESUMO

OBJECTIVES: Using MRSI as comparison, we aimed to explore the difference between amide proton transfer (APT) MRI and conventional semi-solid magnetization transfer ratio (MTR) MRI, and to investigate if molecular APT and structural MTR can provide complimentary information in assessing brain tumors. METHODS: Seventeen brain tumor patients and 17 age- and gender-matched volunteers were included and scanned with anatomical MRI, APT and MT-weighted MRI, and MRSI. Multi-voxel choline (Cho) and N-acetylaspartic acid (NAA) signals were quantified from MRSI and compared with MTR and MTRasym(3.5ppm) contrasts averaged from corresponding voxels. Correlations between contrasts were explored voxel-by-voxel by pooling values from all voxels into Pearson's correlation analysis. Differences in correlation coefficients were tested with the Z-test (set at p<0.05). RESULTS: APT and MT provide good contrast and quantitative parameters in tumor imaging, as do the metabolite (Cho and NAA) maps. MTRasym(3.5ppm) significantly correlated with MTR (R=-0.61, p<0.0001), Cho (R=0.568, p<0.0001) and NAA (R=-0.619, p<0.0001) in tumors, and MTR also significantly correlated with Cho (R=-0.346, p<0.0001) and NAA (R=0.624, p<0.0001). In healthy volunteers, MTRasym(3.5ppm) was non-significantly correlated with MTR (R=-0.049, p=0.239), Cho (R=0.030, p=0.478) and NAA (R=-0.083, p=0.046). Significant correlations were found among MTR with Cho (R=0.199, p<0.0001) and NAA (R=0.263, p<0.0001) in the group of healthy volunteers with lower correlation R values than those in tumor patients. CONCLUSIONS: APT and MT could provide independent and supplementary information for the comprehensive assessment of molecular and structural changes due to brain tumor cancerogenesis. KEY POINTS: • MTR asym(3.5ppm) positively correlated with Cho while negatively with NAA in tumors. • MTR positively correlated with NAA while negatively with Cho in tumors. • Combining APT/MT provides molecular and structural information similarly to MRSI.


Assuntos
Amidas/metabolismo , Neoplasias Encefálicas/metabolismo , Encéfalo/metabolismo , Imageamento por Ressonância Magnética/métodos , Tomografia por Emissão de Pósitrons/métodos , Espectroscopia de Prótons por Ressonância Magnética/métodos , Adulto , Encéfalo/diagnóstico por imagem , Neoplasias Encefálicas/diagnóstico , Feminino , Humanos , Masculino , Pessoa de Meia-Idade , Prótons , Adulto Jovem
15.
Phys Chem Chem Phys ; 20(10): 7167-7172, 2018 Mar 07.
Artigo em Inglês | MEDLINE | ID: mdl-29513307

RESUMO

With the continuous expansion of the family of two-dimensional (2D) materials, flexible electronics based on 2D materials have quickly emerged. Theoretically, predicting the transport properties of the flexible devices made up of 2D materials using first principles is of great importance. Using density functional theory combined with the non-equilibrium Green's function formalism, we calculated the transport properties of all-phosphorus flexible devices with non-collinear electrodes, and the results predicted that the device with compressed metallic phosphorene electrodes sandwiching a P-type semiconducting phosphorene shows a better and robust conducting behavior against the bending of the semiconducting region when the angle between the two electrodes is less than 45°, which indicates that this system is very promising for flexible electronics. The calculation of a quantum transport system with non-collinear electrodes demonstrated in this work will provide more interesting information on mesoscopic material systems and related devices.

16.
Phys Chem Chem Phys ; 20(18): 12618-12623, 2018 May 09.
Artigo em Inglês | MEDLINE | ID: mdl-29693090

RESUMO

The structures, circular dichroism (CD) spectra and nonlinear optical (NLO) responses of a series of inorganic double-helix chains, PnLin (n = 6-12), have been investigated using the quantum chemistry method. P-P and P-Li interactions play a major role in stabilizing double-helix chains. The distinctive CD spectra of the double-helix frameworks (namely, a sharp negative CD band at short-wavelength region and a positive CD band at long-wavelength region) become obvious with increasing number of PLi units. The NLO response augments with the length of the double-helix chains, and the contribution of the axial component along the chain direction gradually becomes crucial simultaneously. Synergistic effects, a decrease of crucial electronic transition energies and charge transfer excitation give rise to enhanced NLO responses. In particular, the electronic transitions from the highest occupied molecular orbital to the lowest unoccupied molecular orbital make significant contributions not only to the positive CD bands in the long-wavelength region, but also to the NLO responses of the double-helix PnLin (n = 6-12) chains.

17.
Phys Chem Chem Phys ; 20(30): 20280-20286, 2018 Aug 01.
Artigo em Inglês | MEDLINE | ID: mdl-30039822

RESUMO

Single-molecule junctions provide the additional flexibility of tuning the on/off conductance states through molecular design. Here, we focus on a family of organometallic complexes with a conjugated curved buckybowl as the ligand. Using first-principles calculations, a multi-mode reversible spin switching based on the CpFe·corannulene complex is predicted by the temperature control of the CpFe+ coordination position in corannulene. The different spin conductance states for three coordinated modes are ascribed to the different electronic spin states of the organometallic complex due to crystal field effects. The predicted relative stabilities of isomers and the energy barriers of isomerization reactions can ensure that the conversion among the three isomers can occur quickly and, at a specific temperature, a dominant isomer has a higher proportion than the other two isomers. This provides a new framework for understanding transport in organometallic complexes with localized d states. This presents an exciting opportunity for exploiting junctions involving molecular spin switching.

18.
Phys Chem Chem Phys ; 18(6): 4333-44, 2016 Feb 14.
Artigo em Inglês | MEDLINE | ID: mdl-26648018

RESUMO

Electronic structures and transport properties of prototype MoS2 nanotube (15, 0) nanocables, including undoped PSi@MoS2 and B- and P-doped PSi@MoS2 (where PSi refers to polysilane), are investigated using the density functional theory (DFT) and the non-equilibrium Green's function (NEGF) methods. It is found that transport properties of two-probe systems by sandwiching finite long nanocables between two Au electrodes are basically in agreement with the electronic structures of their corresponding infinitely long systems. Encapsulating undoped and doped PSi nanowires inside the MoS2 nanotubes could not significantly affect the electronic and transport properties. B-doping and P-doping upon PSi play different roles in the electronic and transport properties. B-doping may exert constructive and destructive effects on electron transport depending on its position and applied bias direction, while P-doping displays a negligible effect. In addition, we found that bi-doping by two adjacent B atoms could slightly enhance the conductivity. These results could offer some clues for conducting experiments to achieve nanoelectronic devices with intrinsic transport properties of MoS2 nanotubes.

19.
Phys Chem Chem Phys ; 18(6): 4385-93, 2016 Feb 14.
Artigo em Inglês | MEDLINE | ID: mdl-26790537

RESUMO

The electronic structure of a novel inorganic (8, 8) MoS2 nanotube nanocable, (VBz)n@MoS2NT, (where Bz refers as C6H6), is investigated using density functional theory. Transport property calculations are further performed employing non-equilibrium Green's function methods by modeling a two-probe device with a finite-sized nanocable sandwiched between two electrodes of its own. It is found that the transport properties of the nanocable agree well with its electronic structure. The core (VBz)n nanowire in the (VBz)n@MoS2NT plays a significant role in electron transportation, meanwhile, the sheath MoS2NT also participates in electron transportation. This phenomenon is different from those of (VBz)n@CNT and (VBz)n@BNNT nanocables. For the (VBz)n@CNT, the transport properties are majorly dominated by the metallic CNT sheath, while for the (VBz)n@BNNT, it is merely decided by the core (VBz)n. The conductivity of the (VBz)n@MoS2NT is slightly better in comparison with pure (VBz)n. Similar to pure (VBz)n, the (VBz)n@MoS2NT shows spin-polarized transport properties: the spin-down state gives a higher conductivity than the spin-up state. The values of the spin filter efficiency of the (VBz)n@MoS2NT can be up to >80%, indicating it to be a good candidate for spin filters. In addition, it is also found that encapsulating (VBz)n into the MoS2NT could introduce magnetism. More importantly, the ferromagnetic (VBz)n@MoS2NT is thermally rather stable. Therefore, encapsulating (VBz)n into the MoS2NT can effectively tune the electronic and transport properties for exploring novel functional nanodevices.

20.
Pharmazie ; 71(11): 640-643, 2016 11 02.
Artigo em Inglês | MEDLINE | ID: mdl-29441968

RESUMO

Drug resistance remains a major unresolved obstacle for gastric cancer (GC) treatment. Recently, increasing studies have showen that microRNAs (miRNAs) are involved in cancer chemotherapeutic resistance and can potentially be applied to reverse drug resistance in cancers. The relationship between miRNA-149 expression and cisplatin (DDP) resistance in GC cells is still unknown. Here, we detected miR-149 expression by using RT-PCR and found that expression of miR-149 was downregulated in SGC7901/DDP cells compared with SGC7901cells, indicating a role of miR-149 in determining cisplatin-resistance of GC cells. Then, SGC7901/DDP cells were tansfected with miR-149 mimics, MTT assay was performed to determine SGC7901/DDP cell viability, and showed that overexpression of miR-149 inhibited the cell viability after cisplatin treatment, suggesting that up-regulation of miR-149 enhanced SGC7901/DDP cell sensitivity to cisplatin. Furthermore, we confirmed that Forkhead box M1 (FoxM1) is a direct target of miR-149 in SGC7901/DDP cells by using luciferase reporter assay. Besides, we also demonstrated that miR-149 enhances SGC7901/DDP cell sensitivity to cisplatin by downregulating FoxM1 expression. In summary, our data provide new insights that miR-149 plays an important role in determining sensitivity of cisplatin-resistant GC cells by targeting FoxM1 and suggest that miR-149 could be a potential target for reversing drug resistance in GC.


Assuntos
Antineoplásicos/farmacologia , Cisplatino/farmacologia , Resistencia a Medicamentos Antineoplásicos/efeitos dos fármacos , Proteína Forkhead Box M1/efeitos dos fármacos , MicroRNAs/farmacologia , Neoplasias Gástricas/tratamento farmacológico , Regiões 3' não Traduzidas/genética , Linhagem Celular Tumoral , Sobrevivência Celular/efeitos dos fármacos , Regulação Neoplásica da Expressão Gênica/efeitos dos fármacos , Marcação de Genes , Humanos
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