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1.
ACS Appl Mater Interfaces ; 12(19): 22357-22364, 2020 May 13.
Artigo em Inglês | MEDLINE | ID: mdl-32293866

RESUMO

Self-powered electronic skin is a promising field for human-machine interfaces to the next generation of intelligent and interactive products due to its capability of including multiple physical parameters for sensing without additional energy supply. This paper reports a novel active multifunctional electronic skin capable of independently detecting contact trajectory, acceleration, velocity, and pressure based on the synchronized triboelectrification and piezoelectric effect. Motion trajectories in the full plane can be identified by using a net-cross electrodes configuration design. Under this electrode special structure design, the motion information such as velocity and acceleration can be accurately obtained by the time difference between the peak values of the triboelectric signal. Real-time detection of dynamic pressure with only two electrodes is achieved by a spacer-grid design and a high quality piezoelectric nanofiber film. By virtue of its high sensitivity and precision, a smart anti-counterfeiting signature system (SASS) can be achieved by this self-powered multifunctional electronic skin with the capability of recognizing the writing habits of people within a 100 ms error for security. It is also a promising candidate in terms of human-machine interaction, cyber security, and so on.

2.
J Chem Phys ; 151(16): 164110, 2019 Oct 28.
Artigo em Inglês | MEDLINE | ID: mdl-31675858

RESUMO

The stochastic differential equation is a powerful tool for describing the dynamics of a dissipative system in which noise characterizes the influence of the environment. For the Ornstein-Uhlenbeck noise, both the formula of differentiation and the hierarchy approach provide efficient numerical simulations, with the stochastic differential equation transformed into a set of coupled, linear ordinary differential equations. We show that while these two deterministic schemes result in different sets of equations, they can be regarded as two representations of an underlying linear-dynamics. Moreover, by manipulating the involved Ornstein-Uhlenbeck noise, we propose a unified algorithm that may reduce to the hierarchy approach or the formula of differentiation in different limits. We further analyze the numerical performance of this algorithm and find that the hierarchy approach appears to be more efficient for our numerical model studies.

3.
Sci Rep ; 9(1): 13818, 2019 09 25.
Artigo em Inglês | MEDLINE | ID: mdl-31554868

RESUMO

Members of the MYB superfamily act as regulators in a wide range of biological processes in plants. Despite this, the MYB superfamily from the Orchidaceae has not been identified, and MYB genes related to bioactive water-soluble polysaccharide (WSP) biosynthesis are relatively unknown. In this study, we identified 159 and 165 MYB genes from two orchids, Phalaenopsis equestris and Dendrobium officinale, respectively. The MYB proteins were classified into four MYB classes in both orchids: MYB-related (MYBR), R2R3-MYB, 3R-MYB and atypical MYB proteins. The MYBR proteins in both orchids were classified into five subfamilies and 12 genes were strongly up-regulated in response to cold stress in D. officinale. The R2R3-MYB proteins were both divided into 31 clades in P. equestris and D. officinale. Among these clades, nine contained MYB TFs related to secondary cell wall biosynthesis or testa mucilage biosynthesis in Arabidopsis thaliana. In D. officinale, 10 candidate genes showed an expression pattern corresponding to changes in the WSP content. Overexpression of one of these candidate genes (DoMYB75) in A. thaliana increased seed WSP content by about 14%. This study provides information about MYB genes in two orchids that will further help to understand the transcriptional regulation of WSP biosynthesis in these orchids as well as other plant species.

4.
J Org Chem ; 84(15): 9714-9725, 2019 08 02.
Artigo em Inglês | MEDLINE | ID: mdl-31298854

RESUMO

The formation of cyclobutane rings is a promising strategy in the development of potential drugs and/or synthetic intermediates, typically challenging to obtain due to their constrained nature. In this work, the [2 + 2] photocycloaddition reaction of S,S-dioxobenzothiophene-2-methanol was explored in microcrystalline powders and its outcome was compared to that observed in solution. It was found that the molecular constraints inherited within the crystal lattice provide an optimal environment that leads to photodimer 4 as the major product in ca. 9.6:0.4 diastereomeric ratios with conversions >95%. The photoreaction was analyzed via X-ray, displaying a crystalline-to-amorphous transformation and showing that units of monomer 2 align to generate the corresponding dimer with a syn-head-to-tail regio- and diastereoselectivity. This result contrasted with that obtained in solution, where the diastereomeric ratio varied as a function of the excited state that is generated, to yield mixtures of dimers 4 and 5 (anti-head-to-tail), or exclusively 5 in the triplet-sensitized photoreaction, in the presence of benzophenone. Density functional theory was used to elucidate a plausible detailed mechanism for the phototransformation, which aided in justifying the results that led to the corresponding dimers. X-ray crystallography allowed us to establish the stereochemical assignment of the obtained cyclobutyl rings. Thus, the use of solid-state or solution photochemistry can be used to gain control of diastereo- and regioselectivities in the formation of this important moiety.

5.
Cell Cycle ; 18(12): 1364-1378, 2019 06.
Artigo em Inglês | MEDLINE | ID: mdl-31131683

RESUMO

Multi-fluorescent imaging of cell cycle progression is essential for the study of cell proliferation in vitro and in vivo. However, there remain challenges, particularly to image cell cycle progression in living cell with available imaging techniques due to lacking the suitable probe. Here, we design a triple fluorescent sensors system making the cell cycle progression visible. Multi-fluorescent sensor shows the proliferating or proliferated cells with different colors. We thus generate the construct and adenovirus to probe cell cycle progression in living cell lines and primary cardiomyocytes. Furthermore, we create the knock-in transgenic mouse to monitor cell cycle progression in vivo. Together, the system can be applied to investigate cell proliferation or cell cycle progression in living cells and animals.

6.
Med Phys ; 46(5): 2522-2525, 2019 May.
Artigo em Inglês | MEDLINE | ID: mdl-30859583

RESUMO

PURPOSE: To evaluate the effectiveness of Bioelectrical Impedance Spectroscopy (BIS) in order to rapidly distinguish malignant vs benign breast masses. METHODS: A total of 622 breast masses from 489 patients were collected from January 2015 to June 2017. Every specimen was evaluated by a breast tissue bioimpedance analyzer (MScan1.0B) followed by morphological examination by pathologists. The results from BIS were compared with the morphological results from pathology (as a gold standard). The specificity and sensitivity of BIS were evaluated and the consistency test was performed. RESULTS: Compared with the pathology standard, BIS had good sensitivity (92.4%), specificity (96.0%), false positive rate (3.96%), and false negative rate (7.58%). The positive likelihood ratio, negative likelihood ratio, positive predictive value, and negative predictive values of BIS were 23.36, 0.0789, 73.49%, 99.07%, respectively. The kappa value of BIS was 0.794 ± 0.038 in the consistency test. CONCLUSION: Compared with the pathology standard, the BIS is an effective, convenient, and economical detection method to quickly differentiate benign and malignant breast masses with high accuracy. It may serve as a potential supplement of intraoperative pathological examinations.


Assuntos
Neoplasias da Mama/diagnóstico , Espectroscopia Dielétrica , Adolescente , Adulto , Idoso , Diagnóstico Diferencial , Feminino , Humanos , Pessoa de Meia-Idade , Fatores de Tempo , Adulto Jovem
7.
J Phys Chem A ; 123(9): 1882-1893, 2019 Mar 07.
Artigo em Inglês | MEDLINE | ID: mdl-30735383

RESUMO

The multilayer improved relaxation is applied to study the delocalization-localization transition in the spin-boson model at zero temperature-a well-known example of quantum phase transition. Calculations of energy eigenstates are obtained by iteratively diagonalizing the matrix of the Boltzmann operator in the top layer representation, using a Lanczos/Arnoldi method while relaxing the single particle functions of all layers using the multilayer multiconfiguration time-dependent Hartree imaginary time propagation. Two properties are used to examine the quantum phase transition: the energy splitting for the lowest pair of eigenstates and the magnetic susceptibility. Consistent findings are obtained with appropriate scaling parameters.

8.
J Biol Chem ; 294(5): 1451-1463, 2019 02 01.
Artigo em Inglês | MEDLINE | ID: mdl-30514760

RESUMO

Polycomb group (PcG) proteins repress master regulators of development and differentiation through organization of chromatin structure. Mutation and dysregulation of PcG genes cause developmental defects and cancer. PcG proteins form condensates in the cell nucleus, and these condensates are the physical sites of PcG-targeted gene silencing via formation of facultative heterochromatin. However, the physiochemical principles underlying the formation of PcG condensates remain unknown, and their determination could shed light on how these condensates compact chromatin. Using fluorescence live-cell imaging, we observed that the Polycomb repressive complex 1 (PRC1) protein chromobox 2 (CBX2), a member of the CBX protein family, undergoes phase separation to form condensates and that the CBX2 condensates exhibit liquid-like properties. Using site-directed mutagenesis, we demonstrated that the conserved residues of CBX2 within the intrinsically disordered region (IDR), which is the region for compaction of chromatin in vitro, promote the condensate formation both in vitro and in vivo We showed that the CBX2 condensates concentrate DNA and nucleosomes. Using genetic engineering, we report that trimethylation of Lys-27 at histone H3 (H3K27me3), a marker of heterochromatin formation produced by PRC2, had minimal effects on the CBX2 condensate formation. We further demonstrated that the CBX2 condensate formation does not require CBX2-PRC1 subunits; however, the condensate formation of CBX2-PRC1 subunits depends on CBX2, suggesting a mechanism underlying the assembly of CBX2-PRC1 condensates. In summary, our results reveal that PcG condensates assemble through liquid-liquid phase separation (LLPS) and suggest that phase-separated condensates can organize PcG-bound chromatin.


Assuntos
Proteínas de Ciclo Celular/metabolismo , Núcleo Celular/metabolismo , DNA/metabolismo , Heterocromatina/metabolismo , Histonas/metabolismo , Nucleossomos/metabolismo , Complexo Repressor Polycomb 1/metabolismo , Animais , Proteínas de Ciclo Celular/genética , Núcleo Celular/genética , Células Cultivadas , Montagem e Desmontagem da Cromatina , DNA/genética , Células-Tronco Embrionárias/citologia , Células-Tronco Embrionárias/metabolismo , Histonas/genética , Camundongos , Camundongos Knockout , Nucleossomos/genética , Complexo Repressor Polycomb 1/genética , Ligação Proteica
9.
J Chem Phys ; 149(10): 104105, 2018 Sep 14.
Artigo em Inglês | MEDLINE | ID: mdl-30219023

RESUMO

We relate the memory kernel in the Nakajima-Zwanzig-Mori time-convolution approach to the reduced system propagator which is often used to obtain the kernel in the Tokuyama-Mori time-convolutionless approach. The connection provides a robust and simple formalism to compute the memory kernel for a generalized system-bath model circumventing the need to compute high order system-bath observables, thus streamlining the use of numerically exact solvers for calculating the memory kernel. We illustrate this for a model system with electron-electron and electron-phonon couplings, driven away from equilibrium.

10.
J Chem Phys ; 149(4): 044119, 2018 Jul 28.
Artigo em Inglês | MEDLINE | ID: mdl-30068178

RESUMO

In a recent paper [H.-D. Meyer and H. Wang, J. Chem. Phys. 148, 124105 (2018)], we have examined the regularization of the equations of motion (EOMs) of the multiconfiguration time-dependent Hartree (MCTDH) approach. We could show that the standard regularization scheme used by almost all researchers in the field is not optimal. The improved regularization allows for larger values of the regularization parameter ϵ, is less sensitive to the actual choice of ϵ, and performs the rotation of initially unoccupied single-particle functions into the "correct" direction in Hilbert space much faster than the old scheme. The latter point increases both the accuracy and efficiency of time propagation for challenging problems. For simple problems, the new scheme requires some additional numerical work as compared with the old scheme, ranging from negligible to almost doubling the total numerical labor. For demanding problems, on the other hand, the additional numerical work of the new scheme is often overcompensated by less steps taken by the integrator. In the present paper, we generalize the new regularization scheme to the multi-layer (ML) extension of MCTDH. Although the principle idea of the new regularization scheme remains unaltered, it was not obvious how the new scheme should be implemented into ML-MCTDH. The ML-MCTDH EOMs are much more complicated than the MCTDH ones, and for optimal numerical performance it was necessary to derive a recursive algorithm for implementing the new regularization scheme.

11.
Nanoscale ; 10(30): 14586-14593, 2018 Aug 02.
Artigo em Inglês | MEDLINE | ID: mdl-30027984

RESUMO

Chiral nanostructures have been attracting extensive interest in recent years primarily because of the unique materials properties that can be exploited for diverse applications. In this study, gold Janus nanoparticles, with hexanethiolates and 3-mercapto-1,2-propanediol segregated on the two hemispheres of the metal cores (dia. 2.7 ± 0.4 nm), self-assembled into vesicle-like, hollow nanostructures in both water and organic media, and exhibited apparent plasmonic circular dichroism (PCD) absorption in the visible range. This was in contrast to individual Janus nanoparticles, bulk-exchange nanoparticles where the two ligands were homogeneously mixed on the nanoparticle surface, or nanoparticles capped with only one kind of ligand. The PCD signals were found to become intensified with increasing coverage of the 3-mercapto-1,2-propanediol ligands on the nanoparticle surface. This was accounted for by the dipolar property of the structurally asymmetrical Janus nanoparticles, and theoretical simulations based on first principles calculations showed that when the nanoparticle dipoles self-assembled onto the surface of a hollow sphere, a vertex was formed which gave rise to the unique chiral characteristics. The resulting chiral nanoparticle vesicles could be exploited for the separation of optical enantiomers, as manifested in the selective identification and separation of d-alanine from the l-isomer.

12.
Nat Commun ; 9(1): 2080, 2018 05 25.
Artigo em Inglês | MEDLINE | ID: mdl-29802243

RESUMO

Over 80% of diffuse intrinsic pontine gliomas (DIPGs) harbor a point mutation in histone H3.3 where lysine 27 is substituted with methionine (H3.3K27M); however, how the mutation affects kinetics and function of PcG proteins remains elusive. We demonstrate that H3.3K27M prolongs the residence time and search time of Ezh2, but has no effect on its fraction bound to chromatin. In contrast, H3.3K27M has no effect on the residence time of Cbx7, but prolongs its search time and decreases its fraction bound to chromatin. We show that increasing expression of Cbx7 inhibits the proliferation of DIPG cells and prolongs its residence time. Our results highlight that the residence time of PcG proteins directly correlates with their functions and the search time of PcG proteins is critical for regulating their genomic occupancy. Together, our data provide mechanisms in which the cancer-causing histone mutation alters the binding and search dynamics of epigenetic complexes.


Assuntos
Neoplasias do Tronco Encefálico/patologia , Glioma/patologia , Histonas/genética , Complexo Repressor Polycomb 1/metabolismo , Complexo Repressor Polycomb 2/metabolismo , Animais , Neoplasias do Tronco Encefálico/genética , Cromatina/genética , Cromatina/metabolismo , Epigênese Genética , Regulação Neoplásica da Expressão Gênica , Glioma/genética , Células HEK293 , Histonas/metabolismo , Humanos , Microscopia Intravital , Camundongos , Mutação , Complexo Repressor Polycomb 1/genética , Complexo Repressor Polycomb 2/genética , Cultura Primária de Células , Imagem Individual de Molécula , Células Tumorais Cultivadas
13.
J Chem Phys ; 148(12): 124105, 2018 Mar 28.
Artigo em Inglês | MEDLINE | ID: mdl-29604814

RESUMO

The Multiconfiguration Time-Dependent Hartree (MCTDH) approach leads to equations of motion (EOM) which become singular when there are unoccupied so-called single-particle functions (SPFs). Starting from a Hartree product, all SPFs, except the first one, are unoccupied initially. To solve the MCTDH-EOMs numerically, one therefore has to remove the singularity by a regularization procedure. Usually the inverse of a density matrix is regularized. Here we argue and show that regularizing the coefficient tensor, which in turn regularizes the density matrix as well, leads to an improved performance of the EOMs. The initially unoccupied SPFs are rotated faster into their "correct direction" in Hilbert space and the final results are less sensitive to the choice of the value of the regularization parameter. For a particular example (a spin-boson system studied with a transformed Hamiltonian), we could even show that only with the new regularization scheme could one obtain correct results. Finally, in Appendix A, a new integration scheme for the MCTDH-EOMs developed by Lubich and co-workers is discussed. It is argued that this scheme does not solve the problem of the unoccupied natural orbitals because this scheme ignores the latter and does not propagate them at all.

14.
Angew Chem Int Ed Engl ; 57(22): 6624-6628, 2018 05 28.
Artigo em Inglês | MEDLINE | ID: mdl-29660223

RESUMO

A strategy for the direct functionalization strategy of inertial dialkyl phosphonates with hydroxy compounds to afford diverse mixed phosphonates with good yields and functional-group tolerance has been developed. Mechanistic investigations involving both NMR studies and DFT studies suggest that an unprecedented highly reactive PV species (phosphoryl pyridin-1-ium salt), a key intermediate for this new synthetic transformation, is generated in situ from dialkyl phosphonate in the presence of Tf2 O/pyridine.

15.
Phys Chem Chem Phys ; 20(4): 2571-2584, 2018 Jan 24.
Artigo em Inglês | MEDLINE | ID: mdl-29318238

RESUMO

Four types of density functional theory (DFT)-based approaches are assessed in this work for the approximate construction of diabatic states and the evaluation of electronic couplings between these states. These approaches include the constrained DFT (CDFT) method, the constrained noninteracting electron (CNE) model to post-process Kohn-Sham operators, the approximate block-diagonalization (BD) of the Kohn-Sham operators, and the generalized Mulliken-Hush method. It is shown that the first three approaches provide a good description for long-distance intermolecular electron transfer (ET) reactions. On the other hand, inconsistent results were found when applying these approaches to intramolecular ET in strongly coupled, mixed-valence systems. Model analysis shows that this discrepancy is caused by the inappropriate use of the two-state model rather than the defects of the approaches themselves. The situation is much improved when more states are included in the model electronic Hamiltonian. The CNE and BD approaches can thus serve as efficient and robust alternatives for building ET models based on DFT calculations.

16.
Pathol Res Pract ; 213(9): 1180-1184, 2017 Sep.
Artigo em Inglês | MEDLINE | ID: mdl-28780081

RESUMO

Growth factor receptor bound protein-7 (Grb7) is a multi-domain adaptor protein that is co-opted by numerous tyrosine kinases involved in various cellular signaling. The objective of this study was to investigate the expression of Grb7 and its clinicopathological significance in cervical cancer. Utilising immunohistochemical staining, we examined the expression of Grb7 in 120 cases of human cervical cancer tissue and 10 cases of adjacent non-cancerous cervical tissue. The positive rate of Grb7 protein expression was 34.2%, which was significantly higher than that in adjacent non-cancerous cervical tissue (0%, p<0.05). The expression of Grb7 was found to be correlated with age, tumor size, serosal invasion, differentiated degree, tumor stage, early or advanced stage and lymph node metastasis. Kaplan-Meier survival analysis showed that patients with positive Grb7 protein expression had a lower overall survival rate than patients without Grb7 expression. In addition, Grb7 plays an important role in promoting tumor progression, including invasion and anti-apoptosis, in cervical cancer cell line. Down-regulation of Grb7 repressed the expression of MMP-9 and Bcl-2, and increased the expression of Bax in Grb7 knockdown Hela cells. Cell invasion assay showed decreased number of Grb7 knockdown Hela cells (18.7±2.1) compared to Hela cells (65.3±2.5, P<0.05). Our results indicated that Grb7 over-expression may facilitate invasion and inhibit apoptosis in cervical cancer and Grb7 is a potentially molecular target of cervical cancer chemotherapy.


Assuntos
Biomarcadores Tumorais/análise , Proteína Adaptadora GRB7/biossíntese , Neoplasias do Colo do Útero/patologia , Adulto , Idoso , Apoptose/fisiologia , Progressão da Doença , Feminino , Proteína Adaptadora GRB7/análise , Regulação Neoplásica da Expressão Gênica/fisiologia , Células HeLa , Humanos , Estimativa de Kaplan-Meier , Pessoa de Meia-Idade , Invasividade Neoplásica/patologia , Prognóstico , Análise de Sobrevida , Neoplasias do Colo do Útero/mortalidade
17.
J Chem Phys ; 146(12): 124112, 2017 Mar 28.
Artigo em Inglês | MEDLINE | ID: mdl-28388113

RESUMO

The multilayer multiconfiguration time-dependent Hartree method is applied in an interaction picture to simulate dynamics of the spin-boson model in the reaction-coordinate representation. The use of the interaction picture allows a more effective description of correlation effects, especially when the coupling strength between the reaction coordinate and the bath is very strong. Examples show that in most physical regimes the efficiency is improved significantly, in some cases up to several orders of magnitude. This opens up new avenues for studying quantum dynamical problems.

18.
J Chem Phys ; 147(24): 244112, 2017 Dec 28.
Artigo em Inglês | MEDLINE | ID: mdl-29289122

RESUMO

Within the framework of the hierarchy equation of motion (HEOM), the quantum kinetic expansion (QKE) method of the spin-boson model is reformulated in the matrix representation. The equivalence between the two formulations (HEOM matrices and quantum operators) is numerically verified from the calculation of the time-integrated QKE rates. The matrix formulation of the QKE is extended to the system-bath factorized initial state. Following a one-to-one mapping between HEOM matrices and quantum operators, a quantum kinetic equation is rederived. The rate kernel is modified by an extra term following a systematic expansion over the site-site coupling. This modified QKE is numerically tested for its reliability by calculating the time-integrated rate and non-Markovian population kinetics. For an intermediate-to-strong dissipation strength and a large site-site coupling, the population transfer is found to be significantly different when the initial condition is changed from the local equilibrium to system-bath factorized state.

19.
J Chem Phys ; 145(16): 164105, 2016 Oct 28.
Artigo em Inglês | MEDLINE | ID: mdl-27802656

RESUMO

The multilayer multiconfiguration time-dependent Hartree (ML-MCTDH) method is implemented in the interaction picture to allow a more effective description of correlation effects. It is shown that the artificial correlation present in the original Schrödinger picture can be removed with an appropriate choice of the zeroth-order Hamiltonian. Thereby, operators in the interaction picture are obtained through time-dependent unitary transformations, which have negligible computational cost compared with other parts of the ML-MCTDH algorithm. The efficiency of the method is demonstrated by application to a model of vibrationally coupled charge transport in molecular junctions.

20.
J Org Chem ; 81(19): 8947-8958, 2016 10 07.
Artigo em Inglês | MEDLINE | ID: mdl-27584708

RESUMO

Dodecamers of RNA [CUACGGAAUCAU] were functionalized with C2'-O-2-thiophenylmethyl groups to obtain oligonucleotides 10-14 and 17. The modified nucleotides were incorporated into RNA strands via solid-phase synthesis. The biophysical properties of these ONs were used to quantify the effects of this modification on RNA:RNA and RNA:DNA duplexes. A combination of UV-vis and circular dichroism were used to determine thermal stabilities of all strands, which hybridized into A-form geometries. Destabilization of the double stranded RNA was measured as a function of number of consecutive modifications, reflected in decreased thermal denaturation values (ΔTm, ca. 2.5-11.5 °C). Van't Hoff plots on a duplex containing one modification (10:15) displayed a ca. ΔΔG° of +4 kcal/mol with respect to its canonical analogue. Interestingly, hybridization of two modified strands (13:17, containing a total of eight modifications) resulted in increased stability and a distinct secondary structure, reflected in its CD spectrum. Molecular modeling based on DFT calculations shed light on the nature of this stability, with induced changes in the torsional angle δ (C5'-C4'-C3'-O3) and phosphate-phosphate distances that are in agreement with a compacted structure. The described synthetic methodology and structural information will be useful in the design of thermodynamically stable structures containing chemically reactive modifications.

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