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The polynuclear metal clusters continually attract wide interest due to their intriguing structures and potential applications in various scientific fields. Here, four actinide clusters have been synthesized by the utilization of multifunctional ligand ferrocenecarboxylic acid (HFcc) and Th4+/U4+ ions by solvent evaporation or solvothermal synthesis strategies in different solvents. Therein, compounds 1, 2 and 4 feature similar [An6(μ3‐O)4(μ3‐OH)4]12+ cores, which are further coordinated by 12 Fcc− ligands and different solvent molecules. The U6Fe12 cluster of compound 4 is linked by four free HFcc molecules via multiple hydrogen bonding to form a supramolecular cluster [U6(μ3‐O)4(μ3‐OH)4(Fcc)12(H2O)4] ⋅ 4HFcc. The cluster core of compound 3 is a μ3‐O2− bridged [U3(μ3‐O)]10+ unit, which is further coordinated by 10 Fcc− ligands via three kinds of coordination modes. It is worth noting that multifunctional Fcc− ligand not only endows compound 1 a main redox wave at E1/2=0.720 V in CH2Cl2/DMF solution, but also enables it to exhibit aggregation‐induced emission (AIE) property. [ABSTRACT FROM AUTHOR]

A two-dimensional bi-layered supramolecular compound [Cu 2 (C 7 H 8 N 4 O) 4 ](ClO 4 ) 2 has been synthesized by the solvothermal method, and characterized via IR and CHN elemental analysis. The single crystal X-ray data of this compound reveal the complex to be dimeric as a result of terminal –NH 2 group of the semicarbazone moiety bridging, which is relatively rare. On this bi-copper(I) complex, another remarkably structural feature is that each Cu atom adopts an unsymmetrical T-shaped geometry comprised of three N atoms from three pyridine-3-carbaldehyde semicarbazone ligands. The molecules are linked into a two-dimensional bi-layered framework by intermolecular N–H  ···  O hydrogen bonds. [ABSTRACT FROM AUTHOR]

Experimental fatigue tests were carried out on three tubular T joints having the same geometrical parameters subjected to in-plane bending (IPB) only, combination of IPB and out-of-plane bending (OPB), and a combination of axial loading, IPB and OPB respectively. Static tests were first carried out to investigate the Hot Spot Stress (HSS) distribution along the intersection of chord and brace, and to determine the peak HSS and its location when the joints were subjected to these load cases. The peak HSS location was used to determine the placement of the probes. An alternating current potential drop technique was then employed to monitor the crack growth and crack shape development on the joints at a preset number of cycles. The experimental data were recorded, and the fatigue performance of the three T joints subjected to basic and combined load cases were investigated. The crack growth curves and crack growth rate on each specimen were presented. The results confirmed that the United Kingdom Department of Energy tubular joint fatigue design T curve derived from a single axis test data is conservative even for combined load cases. [ABSTRACT FROM AUTHOR]

Background: Increased oxidative stress contributes to enhanced osteoclastogenesis and age-related bone loss. Melatonin (MT) is an endogenous antioxidant and declines with aging. However, it was unclear whether the decline of MT was involved in the enhanced osteoclastogenesis during the aging process. Methods: The plasma level of MT, oxidative stress status, bone mass, the number of bone marrow-derived monocytes (BMMs) and its osteoclastogenesis were analyzed in young (3-month old) and old (18-month old) mice (n = 6 per group). In vitro, BMMs isolated from aged mice were treated with or without MT, followed by detecting the change of osteoclastogenesis and intracellular reactive oxygen species (ROS) level. Furthermore, old mice were treated with MT for 2 months to investigate the therapeutic effect. Results: The plasma level of MT was markedly lower in aged mice compared with young mice. Age-related decline in MT was accompanied by enhanced oxidative stress, osteoclastogenic potential and bone loss. MT intervention significantly suppressed the receptor activator of nuclear factor-κB ligand (RANKL)-induced osteoclastogenesis, decreased intracellular ROS and enhanced antioxidant capacity of BMMs from aged mice. MT supplementation significantly attenuated oxidative stress, osteoclastogenesis, bone loss and deterioration of bone microstructure in aged mice. Conclusions: These results suggest that age-related decline of MT enhanced osteoclastogenesis via disruption of redox homeostasis. MT may serve as a key regulator in osteoclastogenesis and bone homeostasis, thereby highlighting its potential as a preventive agent for age-related bone loss. [ABSTRACT FROM AUTHOR]

Transient mixing and ignition mechanisms in a simplified pre-chamber/main-chamber system are investigated using direct numerical simulation (DNS) with detailed chemical kinetics. Full ignition and flame propagation processes in the premixed methane/air mixtures are simulated. Ignition, the progress and topology of flame evolution, and the mean burning velocity in the main chamber are analyzed in detail. Four important phases in the ignition and flame propagation processes are identified based on the flame structure development in the main chamber, the pressure and velocity evolution at typical points in both the pre-chamber and main chamber. Results show that the intermediate species OH, CH 2 O, and HO 2 are critical for flame stabilization and propagation in the main chamber due to their high reactivity. This is sorted as the chemical effect that the pre-chamber jet acts on the main chamber. The high temperature jet also brings heat and unburned fuel into the main chamber, which are sorted as thermal and enrichment effect, respectively. The heat release rate is found to be approximately proportional to the product of CH 2 O and OH mass fractions, which could be regarded as a reliable and effective marker for the heat release rate of methane/air mixtures. It is found that the mean burning velocity in the main chamber can be elevated up to 30 times under the condition investigated. [ABSTRACT FROM AUTHOR]

Hyperalgesia is typified by reduced pain thresholds and heightened responses to painful stimuli, with a notable prevalence in menopausal women, but the underlying mechanisms are far from understood. β-Aminoisobutyric acid (BAIBA), a product of valine and thymine catabolism, has been reported to be a novel ligand of the Mas-related G protein coupled receptor D (MrgprD), which mediates pain and hyperalgesia. Here, we established a hyperalgesia model in 8-week-old female mice through ovariectomy (OVX). A significant increase in BAIBA plasma level was observed and was associated with decline of mechanical withdrawal threshold, thermal and cold withdrawal latency in mice after 6 weeks of OVX surgery. Increased expression of MrgprD in dorsal root ganglion (DRG) was shown in OVX mice compared to Sham mice. Interestingly, chronic loading with BAIBA not only exacerbated hyperalgesia in OVX mice, but also induced hyperalgesia in gonadally intact female mice. BAIBA supplementation also upregulated the MrgprD expression in DRG of both OVX and intact female mice, and enhanced the excitability of DRG neurons in vitro. Knockout of MrgprD markedly suppressed the effects of BAIBA on hyperalgesia and excitability of DRG neurons. Collectively, our data suggest the involvement of BAIBA in the development of hyperalgesia via MrgprD-dependent pathway, and illuminate the mechanisms underlying hyperalgesia in menopausal women. • Increased BAIBA levels associated with the development of hyperalgesia in ovariectomized (OVX) mice. • Reduced expression of AGXT2 and ABAT in OVX mice contributes to the elevation of BAIBA. • BAIBA enhances the excitability of DRG neurons via MrgprD. • MrgprD signaling is pivotal for BAIBA-induced hyperalgesia. [ABSTRACT FROM AUTHOR]