Computational Study on Redox-Switchable 2D Second-Order Nonlinear Optical Properties of Push−Pull Mono-tetrathiafulvalene-Bis(Salicylaldiminato) Zn(II) Schiff Base Complexes

The redox-switchable 2D second-order nonlinear optical (NLO) property of a series of tetrathiafulvalene (TTF) derivatives has been studied based on the density functional theory (DFT) calculations. The redox-active TTF unit has been considered as a manipulative center for switching the 2D second-order NLO properties. Our DFT calculations show that introduction of the TTF unit cannot effectively enhance the second-order NLO properties relative to the reference system 1 because the nonplane embowed arrangement of the TTF unit reduces the electron donor capacity. The electronic structure analysis shows that the TTF unit acts as the oxidized center in one- and two-electron-oxidized processes for 5. A significant transformation on the structure of the TTF unit, the TTF unit changes from the embowed structure to a planar structure, has been found in the series of oxidized processes according to DFT-optimized calculations. This leads to the low excited energy and different charge transfer features of the oxidized species relative to its reduced parents, and thus enhances the static first hyperpolarizabilities. The β value of one- and two-electron-oxidized species is at least ∼15 and ∼8.6 times as large as that of its reduced parents according to our DFT calculations. Simultaneously, the oxidized process increases the contributions from the y-polarized transition, and thus improves the 2D second-order NLO property

Redox and Photoisomerization Switching the Second-Order Nonlinear Optical Properties of a Tetrathiafulvalene Derivative Across Six States: A DFT Study

The switching of second-order nonlinear optical (NLO) properties for a tetrathiafulvalene (TTF) derivative across the six stable states has been studied by using the density functional theory (DFT) calculations. The redox-active TTF unit and a photoisomerized chromophore 1,2-dithienylperfluorocyclopentene (DTE) have been implemented to switch the second-order NLO responses. Our DFT calculations with three functionals demonstrate that introduction of the DTE moiety into the π-conjugated bridge can significantly enhance the second-order NLO response relevant to the donor/acceptor end in this work. Our DFT calculations illustrate that photoisomerization bring forth a large change in the geometry of the series of compounds. The closed-ring form possesses a good π-conjugation relative to the open-ring form and thus a large second-order NLO response. The electronic structure analysis shows that the TTF unit will perform as an oxidation center in the one- and two-electron-oxidation processes. The one- and two-electron-oxidized species have better planar structures of TTF unit than its neutral compound, which ultimately leads to the low excited energy and enhances the static first hyperpolarizability. Our present DFT calculations using three functionals show that the TTF derivative 4 can switch the second-order NLO properties across six stable states, which is a rare example in previously reported second-order NLO switches

Estimation of various chemical bond dissociation enthalpies of large-sized kerogen molecules using DFT methods

<p>Kerogen is irregularly connected by a variety of chemical bonds including C–C bond, C=C bond, C–O bond, C–N bond, C–H bond and C–S bond. It is difficult to identify selective bond breaking events using the existing experimental conditions. In this study, we predict dissociation tendencies of chemical bonds in various kerogen molecules by using 554 small molecular model compounds based on the density functional theoretical (DFT) calculations. Results from our DFT study indicate that the calculated various subtypes of bond dissociation enthalpies (BDEs) changing tendency is that C–S bond < C–N bond < C–O bond < C–C bond < C–H bond < C=C bond. However, for each bond type, the BDE value has a large range and overlaps each other, and the BDE mostly relies on the local environment (the functional groups and position) of chemical bonds and radical stability. For the C–C bond, a linear relationship (<i>R</i> = 0.85) between C–C bond distances and BDE has been achieved. Thus, the bond distance can serve as a good indicator of bond strength for C–C bond linkages. All results support that the BDE is a good choice to evaluate the dissociation tendencies of kerogen and this work provides an effective path to reveal the nature of chemical bonding for large-sized kerogen molecules.</p

Additional file 1 of Human amniotic stem cells-derived exosmal miR-181a-5p and miR-199a inhibit melanogenesis and promote melanosome degradation in skin hyperpigmentation, respectively

Additional file 1. Figure S1. The identification of hASCs and the effect of their CM on the proliferation and migration of B16F10. Figure S2. Exosomes derived from hAESCs inhibited hyperpigmentation. Figure S3. Bioinformatics analysis of hAMSCs-derived exosomes. Figure S4. Quantitative analysis is shown in Western blotting. Table S1. The sequences of Real-Time PCR primers. Table S2. miRNAs expression in top from hAMSCs-secreted exosomes

Three-Dimensional Structure of a Huadian Oil Shale Kerogen Model: An Experimental and Theoretical Study

The molecular structural information on a kerogen isolated from Huadian oil shale was obtained using solid-state ¹³C nuclear magnetic resonance (NMR), X-ray photoelectron spectroscopy (XPS), Fourier transform infrared (FTIR), and X-ray diffraction (XRD) techniques. Then, a series of Huadian kerogen isomers were constructed on the basis of these structural data. The possible carbon skeleton isomer and the substituted position effects of the aromatic ring, aliphatic ether bond, carboxylic acid, and carboxylic acid derivative as well as the quantity of tertiary and quaternary carbons on Huadian kerogen model stability have been systematically studied on the basis of density functional theory (DFT) calculations. For the carbon skeleton isomer, the calculated total energy decreases with the increasing number of the closed annular space (grid), which is constituted by connecting the aliphatic chain to the aromatic cluster or other aliphatic chain. DFT calculations show an about 16.8 kcal mol^–1 decrease in total energy for every grid increase when the number of grids increases from 2 to 11. A significant break in the decrease of the total energy has been obtained for an isomer with 11 grids, which means that a proper number of grids (11 grids is appropriate in this paper) in carbon skeleton should be considered for building the chemical structure of Huadian kerogen. For the substituted position effects, aliphatic ether bonding to quaternary carbon, carboxylic acid attaching to secondary carbon, and carboxylic acid derivative bonding to quaternary carbon seem to give a lower energy structure than other connections. Besides, a high quantity of tertiary and quaternary carbons is conducive to a stable model for Huadian kerogen. The aromatic cluster dispersed distribution also makes a contribution to improve the stability of the model. According to these results, we proposed a relatively stable Huadian kerogen three-dimensional (3D) model. Moreover, this 3D model was testified reasonablely through the match between calculated and experimental ¹³C NMR spectra

Data_Sheet_1_Synthesis and Microwave Absorbing Properties of Porous One-Dimensional Nickel Sulfide Nanostructures.docx

One-dimensional (1D) porous NixSy nanostructures have been successfully fabricated by two-step method consisting of solvothermal and subsequent annealing process. The suitable heat treatment temperature and reaction time play crucial roles in the final structure, morphology, as well as performance. The uniform and perfect porous NixSy nanostructures obtained at 310°C exhibit outstanding microwave absorption performances. A minimum reflection loss of −35.6 dB is achieved at 8.5 GHz, and the effective absorption bandwidth almost covers 14.5 GHz with the absorber thickness range of 2.0–5.0 mm. It can be supposed that this porous structure with rough surface which is favor for increasing the microwave multiple reflection and scattering, contributes a high-performance electromagnetic absorption.</p

Image_1_CD38 Deficiency Alleviates D-Galactose-Induced Myocardial Cell Senescence Through NAD+/Sirt1 Signaling Pathway.pdf

Our previous research showed that CD38 played vital roles in Ang-II induced hypertrophy and high fat diet induced heart injury. However, the role of CD38 in heart aging is still unknown. In the present study, we reported that CD38 knockdown significantly protected cardiomyocytes from D-galactose (D-gal)-induced cellular senescence. Cellular senescence was evaluated by β-galactosidase staining, the expressions of genes closely related to aging including p16 and p21, and the ROS production, MDA content and the expressions of oxidant stress related genes were examined by biochemical analysis, Western blot and QPCR. Our results showed that the expression of CD38 was increased in H9c2 cells after D-gal treatment and the expressions of NAMPT and Sirt1 were downregulated in heart tissue from old mice. CD38 knockdown significantly reduced the number of SA-β-gal-positive cells and the expressions of p16 and p21 in H9c2 cells with or without D-gal treatment. The acetylation level of total protein was decreased in CD38 knockdown group, but the expression of Sirt3 was increased in CD38 knockdown group treated with D-gal. In addition, knockdown of CD38 significantly attenuated D-gal induced ROS production, MDA content and NOX4 expression in the cells. Inhibition Sirt1 partially reversed the effects of CD38 knockdown on D-gal induced senescence and oxidative stress. Furthermore, NAD+ supplementation reduced D-gal induced cellular senescence, ROS production and MDA content. The expression of SOD2 was increased and the NOX4 expression was decreased in H9c2 cells after NAD+ supplementation. Taken together, our results demonstrated that CD38 knockdown alleviated D-gal induced cell senescence and oxidative stress via NAD+/Sirt1 signaling pathway.</p

Additional file 2 of Human amniotic mesenchymal stem cells-derived IGFBP-3, DKK-3, and DKK-1 attenuate liver fibrosis through inhibiting hepatic stellate cell activation by blocking Wnt/β-catenin signaling pathway in mice

Additional file 2: Fig. S1. hAMSCs and hAMSC-CM treatment inhibited the expression of P-ERK1/2 and P-JNK in LX-2 cells. (A, C) LX-2 cells were treated with normal medium (control), hAMSCs, and hAMSC-CM. The expression levels of ERK1/2, P-ERK1/2, JNK, and P-JNK in LX-2 cells of different groups were analyzed by western blot after 48 h of treatment. (B, D) Western blot detection of P-ERK1/2, P-JNK, and α-SMA protein expression in LX-2 after PD98059 or SP600125 treatment. The normal LX-2 was used as control

Additional file 1 of Human amniotic mesenchymal stem cells-derived IGFBP-3, DKK-3, and DKK-1 attenuate liver fibrosis through inhibiting hepatic stellate cell activation by blocking Wnt/β-catenin signaling pathway in mice

Additional file 1: Table S1. The expression levels of 440 cytokines in the culture supernatant of the LX-2, hAMSCs, and co-culture group