Unraveling the Marked Differences of the Excited-State Properties of Arylgold(III) Complexes with C∧N∧C Tridentate Ligands.

Three structurally similar gold(III) complexes with C∧N∧C tridentate ligands, [1; C∧N∧C = 2,6-diphenylpyridine], [2; C∧N∧C = 2,6-diphenylpyrazine], and [3; C∧N∧C = 2,6-diphenyltriazine], have been investigated theoretically to rationalize the marked difference in emission behaviors. The geometrical and electronic structures, spectra properties, radiative and nonradiative decay processes, as well as reverse intersystem crossing and reverse internal conversion (RIC) processes were thoroughly analyzed using density functional theory (DFT) and time-dependent DFT calculations. The computed results indicate that there is a small energy difference ΔET1-T1' between the lowest-energy triplet state (T1) and the second lowest-energy triplet state (T1') of complexes 2 and 3, suggesting that the excitons in the T1 state can reach the emissive higher-energy T1' through the RIC process. In addition, the non-emissive T1 states of gold(III) complexes in solution can be ascribed to the easily accessible metal-centered (3MC) state or possibly tunneling into high-energy vibrationally excited singlet states for nonradiative decay. The low efficiency of 3 is attributed to the deactivation pathway via the 3MC state. The present study elucidates the relationship between structure and property of gold(III) complexes featuring C∧N∧C ligands and providing a comprehensive understanding of the significant differences in their luminescence behaviors.

Large and tunable negative thermal expansion induced by a synergistic effect in M2II[MIV(CN)8] Prussian blue analogues.

Designing negative thermal expansion (NTE) materials with a larger NTE coefficient and a wider temperature window is a great challenge nowadays, leading to the limitation of existing NTE materials such that only about 150 kinds of NTE materials have been discovered since 1996. Here, using first-principles calculations combined with the quasi-harmonic approximation (QHA), we find that the synergistic effect of different vibrational modes can significantly enhance the NTE in open framework compounds. We systematically investigate the NTE properties of the M2IIMIV(CN)8 (MII = Ni, Co, Fe, and Mn; MIV = Mo and W) family, which is the first kind of Prussian blue analogues (PBAs) with a 2D and 3D topology structure, to explore the synergistic enhancement effect in NTE. We reveal that both the optical modes of the rotational motion of [W(CN)8] and [Ni(NC)4] rigid units and the low frequency acoustic modes of the transverse vibration contribute significantly to the NTE. Furthermore, the coefficients of NTE increase monotonously with increasing ionic radius upon substituting Ni in M2IIW(CN)8 with Co, Fe, or Mn, respectively. Analyzing the vibrational modes of the substituted systems indicates that the dramatic changes in NTE originate from a highly synergistic effect, in which all the frequencies of these NTE modes have the same trend, i.e. the lower the frequencies, the larger the coefficient of NTE. This work clearly presents a synergistic mechanism of enhancing NTE in PBA materials, and sheds light on designing new materials with better properties.

The unexpectedly rich reconstructions of rutile TiO2(011)-(2 × 1) surface and the driving forces behind their formation: an ab initio evolutionary study.

In this paper, we employ state-of-the-art theoretical approaches to elucidate the structures of the (011) surface of rutile (R-)TiO2. An unexpectedly rich chemistry has been uncovered. Titanyl-TiO2 and titanyl-Ti2O3 reconstructions can be used for rationalizing the experimental findings, matching the STM images and the changes in the band gap. From the viewpoint of thermodynamics, the predicted MF(111)-TiO reconstruction is more reasonable than the previously proposed MF(111)-TiO3 model, although there is a structural similarity. The richness of surface phases, the formation of which is driven by thermodynamic conditions and surface stress release, implies the multifunctionality of the R-TiO2(011) surface. After the clarification of TiO2(011) and TiO2(110) surface structures {PRL, 2014, 113, 266101} (the most important surfaces of rutile), the origin of the Brønsted acidity of R-TiO2, which has remained a mystery at the atomic level, can also be addressed in the near future.

New reconstructions of the (110) surface of rutile TiO2 predicted by an evolutionary method.

Reconstructions of the (110) surface of rutile TiO2 (the dominant surface of this important mineral and catalyst) are investigated using the evolutionary approach, resolving previous controversies. Depending on thermodynamic conditions, four different stable reconstructions are observed for this surface. We confirm the recently proposed "Ti2O3-(1×2)" and "Ti2O-(1×2)" reconstructions and predict two new reconstructions "Ti3O2-(1×2)" and "Ti3O3-(2×1)," which match experimental results. Furthermore, we find that surface electronic states are sensitive to reconstructions and, therefore, depend on thermodynamic conditions.

Schisandrin B mitigates hepatic steatosis and promotes fatty acid oxidation by inducing autophagy through AMPK/mTOR signaling pathway.

BACKGROUND: Schisandrin B (Sch B), which inhibits hepatic steatosis caused by non-alcoholic fatty liver disease (NAFLD), is one of the most active dibenzocyclooctadienes isolated from Schisandra chinensis (Turcz.) Baill with various pharmacological activities. In this study, the role of Sch B-induced autophagy in lipid-lowering activities of Sch B was examined and the underlying mechanisms were elucidated. METHODS: Free fatty acid (FFA)-stimulated HepG2 cells and mouse primary hepatocytes (MPHs) and high-fat diet (HFD)-fed mice were used as NAFLD models. The role of Sch B-induced autophagy in lipid-lowering effects of Sch B was assessed using ATG5/TFEB-deficient cells and 3-methyladenine (3-MA)-treated hepatocytes and mice. RESULTS: Sch B simultaneously active autophagy through AMPK/mTOR pathway and decreased the number of lipid droplets in FFA-treated HepG2 cells and MPHs. Additionally, siATG5/siTFEB transfection or 3-MA treatment mitigated Sch B-induced autophagy and activation of fatty acid oxidation (FAO) and ketogenesis in FFA-treated HepG2 cells and MPHs. Sch B markedly decreased hepatic lipid content and activated the autophagy through AMPK/mTOR pathway in HFD-fed mice. However, the activities of Sch B were suppressed upon 3-MA treatment. Sch B upregulated the expression of key enzymes involved in FAO and ketogenesis, which was mitigated upon 3-MA treatment. Moreover, changes in hepatic lipid components and amino acids may be related to the Sch B-induced autophagy pathway. CONCLUSION: These results suggested that Sch B inhibited hepatic steatosis and promoted FAO by activation of autophagy through AMPK/mTOR pathway. Our study provides novel insights into the hepatic lipophagic activity of Sch B and its potential application in the management of NAFLD.

Quanduzhong capsules for the treatment of grade 1 hypertension patients with low-to-moderate risk: A multicenter, randomized, double-blind, placebo-controlled clinical trial.

Background: Duzhong [DZ (Eucommia ulmoides Oliv.)] is regarded as a traditional Chinese medicine with a history dating back more than 2000 years. This herb is considered a nourishing herb in China and is commonly used as a tonic to strengthen muscles and bones, nourish the kidneys and liver, and soothe miscarriages. Moreover, there is evidence that DZ is capable of regulating blood pressure (BP), and several compounds isolated from DZ have been shown to have a BP-lowering effect. Quanduzhong capsules contain an extract of DZ [Eucommia ulmoides Oliv. (Eucommiaceae; Eucommiae cortex)] that is effective in treating hypertension. This multicenter, randomized, double-blind, placebo-controlled clinical trial sought to evaluate the clinical efficacy of Quanduzhong capsules in the treatment of low-to-moderate risk grade 1 hypertension patients. Materials and methods: A total of 60 patients from 3 centers with documented low-to-moderate risk grade 1 hypertension were randomly assigned in a 1:1 ratio to the test group or the control group. After a 1 week lead-in period using sham Quanduzhong capsules, all patients who met the entry criteria (29 cases in the test group and 29 cases in the control group) entered the 4 week test period. The test group took Quanduzhong capsules, and the control group continued to take sham Quanduzhong capsules. The primary endpoints [24-h mean systolic blood pressure (SBP) and diastolic blood pressure (DBP) determined via 24-h ambulatory blood pressure monitoring (ABPM); office SBP and DBP] and secondary endpoints [mean arterial pressure; mean pulse; daytime mean SBP and DBP; nocturnal mean SBP and DBP; SBP and DBP load; area under the blood pressure (BP) curve; morning peak BP; early morning SBP and DBP; smoothness index of SBP and DBP; 24 h BP mean coefficient of variation (CV); percentage of patients with circadian restoration in ABPM; home BP; quality of life evaluated by WHO Quality of Life-BREF questionnaire; grading and quantitative evaluation of hypertension symptoms; values of plasmatic renin activity, angiotensin II, aldosterone, ß-2 microglobulin and homocysteine] were assessed following the treatment. Drug-related adverse events and adverse drug reactions were also compared. Results: After a 4 week test period, a significant difference in the DBP CV between the two groups was observed (-2.49 ± 4.32 vs. 0.76 ± 4.3; p < .05). Moreover, the mean office SBP change was -7.62 ± 9.32 mmHg, and the mean DBP change was -4.66 ± 6.03 (p < .05). Among the three subjects with abnormal homocysteine levels in the test group, homocysteine levels decreased by 6.23 ± 9.15 µmol/L after treatment. No differences were observed between the two groups in any other indicators. After 4 weeks of treatment, there were no significant differences between the groups in terms of safety indicators (p > .05). No abnormal vital signs (except BP) or severe liver or renal function impairment were observed during the treatment periods; in addition, adverse events and drug reactions were mild. Conclusion: Treatment with Quanduzhong capsules reduced office SBP and DBP as well as DBP CV determined by 24-h ambulatory BP monitoring in patients with grade 1 hypertension at low-to-moderate risk. Clinical Trial Registration: https://www.chictr.org.cn/showproj.aspx?proj=32531, identifier ChiCTR1900021699.

The synergistic effects of the Cu-CeO2(111) catalysts on the adsorption and dissociation of water molecules.

The interaction of water molecules with the Cu-CeO(2)(111) catalyst (Cu/CeO(2) and Cu(0.08)Ce(0.92)O(2)) is studied systematically by using the DFT+U method. Although both molecular and dissociative adsorption states of water are observed on all the considered Cu-CeO(2)(111) systems, the dissociation is preferable thermodynamically. Furthermore, the dissociation of water molecule relates to the geometric structure (e.g. whether or not there are oxygen vacancies; whether or not the reduced substrate retains a fluorite structure) and the electronic structure (e.g. whether or not there is reduced cerium, Ce(3+)) of the substrate.In addition, the adsorption of water molecules induces variations of the electronic structure of the substrate, especially for Cu/CeO(2-x)(111)-B (a Cu atom adsorbed symmetrically above the vacancy of the reduced ceria) and highly reduced Cu(0.08)Ce(0.92)O(2)(111), i.e. the Cu(0.08)Ce(0.92)O(2-x)(111)-h. The variations of electronic structure promote the dissociation of water for the highly reduced system Cu(0.08)Ce(0.92)O(2-x)(111)-h. More importantly, the improvement of WGS reaction by Cu-ceria is expected to be by the associative route through different intermediates.

Tibetan Medicine for Diabetes Mellitus: Overview of Pharmacological Perspectives.

Diabetes mellitus (DM) and its complications pose a major public health threat which is approaching epidemic proportions globally. Current drug options may not provide good efficacy and even cause serious adverse effects. Seeking safe and effective agents for DM treatment has been an area of intensive interest. As a healing system originating in Tibet, Traditional Tibetan Medicine (TTM) has been widely used by Tibetan people for the prevention and treatment of DM and its complications for hundreds of years. Tibetan Materia Medica (TMM) including the flower of Edgeworthia gardneri (Wall.) Meisn., Phyllanthi Fructus, Chebulae Fructus, Huidouba, and Berberidis Cortex are most frequently used and studied. These TMMs possess hypoglycemic, anti-insulin resistant, anti-glycation, lipid lowering, anti-inflammatory, and anti-oxidative effects. The underlying mechanisms of these actions may be related to their α-glucosidase inhibitory, insulin signaling promoting, PPARs-activating, gut microbiota modulation, islet ß cell-preserving, and TNF-α signaling suppressive properties. This review presents a comprehensive overview of the mode and mechanisms of action of various active constituents, extracts, preparations, and formulas from TMM. The dynamic beneficial effects of the products prepared from TMM for the management of DM and its complications are summarized. These TMMs are valuable materia medica which have the potential to be developed as safe and effective anti-DM agents.

miR-320a in serum exosomes promotes myocardial fibroblast proliferation via regulating the PIK3CA/Akt/mTOR signaling pathway in HEH2 cells.

MicroRNAs (miRNAs/miRs) serve an important role in the pathogenesis of chronic heart failure (CHF). A number of reports have illustrated the regulatory effect of serum exosomal miRNA on myocardial fibrosis. The present study aimed to investigate the expression of miR-320a in serum exosomes, as well as the effect of miR-320a on myocardial fibroblast proliferation. Serum exosome samples from 10 patients with CHF and 5 healthy volunteers were obtained and characterized. mRNA and protein expression levels were measured via reverse transcription-quantitative PCR and western blotting, respectively. The content of soluble growth stimulation expressed gene 2 (sST2) was determined via ELISA. HEH2 cell viability and apoptosis were detected by performing MTT assays and flow cytometry, respectively. The results demonstrated that serum miR-320a expression levels and sST2 content were significantly increased in patients with CHF compared with healthy controls, and the expression of serum miR-320a was significantly correlated with clinical CHF indexes. miR-320a expression levels were significantly increased in exosomes isolated from patients with CHF compared with those isolated from healthy controls. Phosphoinositide-3-kinase catalytic α polypeptide gene (PIK3CA) expression levels and sST2 content were increased in HEH2 cells following transfection with miR-320a mimics compared with NC-mimic, whereas miR-320a inhibitor displayed contrasting effects by reduced the cell viability and apoptosis in myocardial fibroblasts compared with the NC-inhibitor group. The protein expression levels of collagen I, collagen III, α-smooth muscle actin, phosphorylated (p)-mTOR (ser 2448)/mTOR, p-Akt (ser 473)/Akt, p-Akt (thr 308)/Akt and PIK3CA were significantly increased in miR-320a mimic-transfected HEH2 cells compared with the NC-mimics groups. By contrast, miR-320a inhibitor notably downregulated the expression levels of these proteins compared with the NC-inhibitor group. Collectively, the results of the present study demonstrated that miR-320a promoted myocardial fibroblast proliferation via regulating the PIK3CA/Akt/mTOR signaling pathway in HEH2 cells, suggesting that serum exosomal miR-320a may serve as a potential biomarker for the diagnosis of CHF.

Tetrahedral honeycomb surface reconstructions of quartz, cristobalite and stishovite.

Crystalline silica (SiO2) is a major material used in many technologies, yet the exact surface structures of silica polymorphs are still mostly unknown. Here we perform a comprehensive study of surface reconstructions of α-cristobalite (001), α-quartz (001) and stishovite (110) and (100) using evolutionary algorithm USPEX in conjunction with ab initio calculations. We found the well-known "dense surface" to be among low-energy reconstructions of α-quartz (001), as well as its previously proposed distorted version, which we call "shifted surface". For cristobalite and stishovite we show the formation of reconstructions without dangling bonds which share common features with well-known "dense surface" of α-quartz (001). We call them "dense cristobalite" and "dense stishovite" - all of these have honeycomb arrangements of corner-sharing SiO4-tetrahedra in the surface layers. These tetrahedral honeycombs have very low surface energies, and such tetrahedral surface pattern is observed even in stishovite (the bulk structure of which has SiO6-octahedra, rather than SiO4-tetrahedra).

Prediction of a new ground state of superhard compound B6O at ambient conditions.

Boron suboxide B6O, the hardest known oxide, has an Rm crystal structure (α-B6O) that can be described as an oxygen-stuffed structure of α-boron, or, equivalently, as a cubic close packing of B12 icosahedra with two oxygen atoms occupying all octahedral voids in it. Here we show a new ground state of this compound at ambient conditions, Cmcm-B6O (ß-B6O), which in all quantum-mechanical treatments that we tested comes out to be slightly but consistently more stable. Increasing pressure and temperature further stabilizes it with respect to the known α-B6O structure. ß-B6O also has a slightly higher hardness and may be synthesized using different experimental protocols. We suggest that ß-B6O is present in mixture with α-B6O, and its presence accounts for previously unexplained bands in the experimental Raman spectrum.

First-principles study on the incipient oxidization of Nb(110).

The incipient oxidization of Nb(110) has been investigated using the density functional theory method. We rationalize the well-known puzzle, i.e., Nb(110) is difficult to clean, by calculating the O dissolution, and the on-surface and subsurface adsorption at low concentration. It is found that the structure of on-surface O adsorption at 0.50 monolayer (ML) coverage has the largest binding energy and minimum work function, in agreement with experimental results. At 1.00 ML coverage, the inward diffusion of O atoms is promoted by O adatoms, attributed to the formation of a local electric field. Our theoretical results improve the understanding of the experiments showing that NbO(x) oxides on the surface can be formed and decomposed by treating samples at 1500-2000 K in vacuum. Furthermore, the thermodynamic analysis of the O/Nb(110) systems shows that bulk NbO is stable in vacuum, in agreement with the observed formation of NbO nanostructures on Nb(110).