Structure–property relations of three-dimensional nanoporous template-based graphene foams

Recently, much attention has been directed to 3D graphene structures due to their potential of retaining intrinsic 2D graphene properties, in combination with structural flexibility and tunable porosity. From a theoretical point of view, however, it is challenging to build 3D graphene foam structures that accurately represent experimental topological configurations. Here, we generate open-cell 3D graphene structures that closely reflect template-based manufacturing techniques and investigate their mechanical properties. We use all-atom molecular dynamics simulations to relate the overall stiffness, collapse stress and fracture properties to the underlying graphene microstructure represented by the graphene relative density, template relative density and number of graphene layers. We do so for four different template morphologies: gyroids, regular foam (BCC), random foam and nanoporous gold. The overall mechanical properties as a function of graphene relative density are analyzed in terms of power law relations to probe the microstructural deformation modes. Our results show that the open-cell 3D graphene structures feature bending as the dominant deformation mode, with regular graphene foams having the highest stiffness and strength and random foams the lowest. For gyroids we found that a higher template relative density leads to reduced mechanical properties but improved ductility. A similar trend was observed when the number of graphene layers was increased: enhanced ductility but at the expense of a reduced strength. Interestingly, we found that for low graphene density, the gyroids feature a strong self-stiffening response, leading to improvements in both strength as well as ductility. Our findings can be used as a guideline for the experimental design of innovate and lightweight graphene structures with strongly enhanced mechanical properties

A critical review of a computational fluid dynamics (CFD)-based explosion numerical analysis of offshore facilities

In oil and gas industries, the explosive hazards receive lots of attention to achieve a safety design of relevant facilities. As a part of the robust design for offshore structures, an explosion risk analysis is normally conducted to examine the potential hazards and the influence of them on structural members in a real explosion situation. Explosion accidents in the oil and gas industries are related to lots of parameters through complex interaction. Hence, lots of research and industrial projects have been carried out to understand physical mechanism of explosion accidents. Computational fluid dynamics-based explosion risk analysis method is frequently used to identify contributing factors and their interactions to understand such accidents. It is an effective method when modelled explosion phenomena including detailed geometrical features. This study presents a detailed review and analysis of Computational Fluid Dynamics-based explosion risk analysis that used in the offshore industries. The underlying issues of this method and current limitation are identified and analysed. This study also reviewed potential preventative measures to eliminate such limitation. Additionally, this study proposes the prospective research topic regarding computational fluid dynamics-based explosion risk analysis

Frequent copy number variations of PI3K/AKT pathway and aberrant protein expressions of PI3K subunits are associated with inferior survival in diffuse large B cell lymphoma

BACKGROUND: It has been reported that the PI3K/AKT signaling pathway is activated in diffuse large B-cell lymphoma (DLBCL), PI3K constitutive activation plays a crucial role in PI3K/AKT pathway. However, the copy number variations (CNVs) of PI3K subunits on gene level remain unknown in DLBCL. Therefore, the aim of the study is to investigate the CNV of PI3K subunits and their relationship with clinicopathological features exploring the possible mechanism underlying of PI3K activation in DLBCL. METHODS: CNV of 12 genes in the PI3K/AKT pathway was detected by NanoString nCounter in 60 de novo DLBCLs and 10 reactive hyperplasia specimens as controls. Meanwhile, immunohistochemistry (IHC) was performed to examine the expression of p110α, p110β, p110γ, p110δ, and pAKT on DLBCL tissue microarrays. RESULTS: All PI3K and AKT subunits, except for PIK3R1, had various CNVs in the form of copy number amplifications and copy number losses. Their rates were in the range of 8.3–20.0%. Of them PIK3CA and PIK3CB gene CNVs were significantly associated with decreased overall survival (P = 0.029 and P = 0.019, respectively). IHC showed that the frequency of strong positive expression of p110α, p110β, p110γ, and p110δ were 26.7%, 25.0%, 18.3%, and 25.0% respectively, and they were found to be associated with decreased survival (P = 0.022, P = 0.015, P = 0.015, and P = 0.008, respectively). Expression of p110α was not only significantly associated with CNVs of PIK3CA (P = 0.002) but also positively correlated with strong positive expression of pAKT (P = 0.026). CONCLUSIONS: CNV of PIK3CA is highly associated with aberrant p110α protein expression and subsequent activation of PI3K/AKT pathway. CNVs of PIK3CA and PIK3CB, and aberrant protein expression of p110 isoforms are of great important value for predicting inferior prognosis in DLBCL. Frequent CNVs of PI3K/AKT subunits may play an important role in the tumorigenesis of DLBCL

Rigorous assessment of Cl−‐based anolytes on electrochemical ammonia synthesis

Many challenges in the electrochemical synthesis of ammonia have been recognized with most effort focused on delineating false positives resulting from unidentified sources of nitrogen. However, the influence of oxidizing anolytes on the crossover and oxidization of ammonium during the electrolysis reaction remains unexplored. Here it is reported that the use of analytes containing halide ions (Cl− and Br−) can rapidly convert the ammonium into N2, which further intensifies the crossover of ammonium. Moreover, the extent of migration and oxidation of ammonium is found to be closely associated with external factors, such as applied potentials and the concentration of Cl−. These findings demonstrate the profound impact of oxidizing anolytes on the electrochemical synthesis of ammonia. Based on these results, many prior reported ammonia yield rates are calibrated. This work emphasizes the significance of avoiding selection of anolytes that can oxidize ammonium, which is believed to promote further progress in electrochemical nitrogen fixation

Mapping the Galactic disk with the LAMOST and Gaia Red clump sample: I: precise distances, masses, ages and 3D velocities of ∼\sim 140000 red clump stars

We present a sample of $\sim$ 140,000 primary red clump (RC) stars of spectral signal-to-noise ratios higher than 20 from the LAMOST Galactic spectroscopic surveys, selected based on their positions in the metallicity-dependent effective temperature--surface gravity and color--metallicity diagrams, supervised by high-quality $Kepler$ asteroseismology data. The stellar masses and ages of those stars are further determined from the LAMOST spectra, using the Kernel Principal Component Analysis method, trained with thousands of RCs in the LAMOST-$Kepler$ fields with accurate asteroseismic mass measurements. The purity and completeness of our primary RC sample are generally higher than 80 per cent. For the mass and age, a variety of tests show typical uncertainties of 15 and 30 per cent, respectively. Using over ten thousand primary RCs with accurate distance measurements from the parallaxes of Gaia DR2, we re-calibrate the $K_{\rm s}$ absolute magnitudes of primary RCs by, for the first time, considering both the metallicity and age dependencies. With the the new calibration, distances are derived for all the primary RCs, with a typical uncertainty of 5--10 per cent, even better than the values yielded by the Gaia parallax measurements for stars beyond 3--4 kpc. The sample covers a significant volume of the Galactic disk of $4 \leq R \leq 16$ kpc, $|Z| \leq 5$ kpc, and $-20 \leq \phi \leq 50^{\circ}$. Stellar atmospheric parameters, line-of-sight velocities and elemental abundances derived from the LAMOST spectra and proper motions of Gaia DR2 are also provided for the sample stars. Finally, the selection function of the sample is carefully evaluated in the color-magnitude plane for different sky areas. The sample is publicly available.Comment: 16 pages, 19 figures, 3 tables, accepted for publication in ApJ

R : Lithium-mediated electrochemical dinitrogen reduction reaction

The Haber–Bosch process is the dominant approach for NH3 production today, but the process has to be maintained at energy-intensive high temperatures and pressures. Li-mediated electrocatalytic dinitrogen reduction reaction (eN2RR) could instead enable sustainable and green NH3 production at ambient conditions. Lithium mediators realize the synthesis of NH3via the formation of Li3N, and thus lower the energy required for the direct cleavage of N2. There has now been a surge of interest in devising approaches to optimize the NH3 yield rate and faradaic efficiency of the eN2RR process by employing different catalysts as well as electrolytes. This review discusses the recent advances in the field of the Li-mediated eN2RR along with the latest insights into the proposed catalytic mechanisms. Moreover, it also highlights the state-of-the-art reported electrocatalysts and electrolytes that have revolutionized the field of the Li-mediated eN2RR. In addition to the above, our review provides a critical overview of certain limitations and a future prospectus that will provide a way forward to explore this area. Keywords: Nitrogen reduction reaction; Ammonia; Electrocatalysis; Lithium; Reaction mechanism

Simultaneously enhancing adsorbed hydrogen and dinitrogen to enable efficient electrochemical NH3 synthesis on Sm(OH)3

The electrochemical N2 reduction reaction (ENRR), driven by renewable electricity and run under ambient conditions, offers a promising sustainable avenue for carbon-neutral NH3 production. Yet, to efficiently bind and activate the inert N2 remains challenge. Herein, effective and stable electrochemical NH3 synthesis on Sm(OH)3 via enhanced adsorption of hydrogen and dinitrogen by dual integration of sulfur dopants and oxygen vacancies (VO) is reported. The resulting S-doped lanthanide electrocatalyst attains both a good NH3 yield rate, exceeding 21 μgNH3 h−1 mgcat.−1, and an NH3 faradaic efficiency of over 29% at −0.3 V (vs reversible hydrogen electrode) in an H-type cell using a neutral electrolyte, figures of merit that are largely maintained after 2 days of consecutive polarization. Density functional theory calculations show that the adsorption energy barrier of N2 on S-Sm(OH)3(VO) is greatly lowered by the introduction of VO. In addition, the S sites improve the adsorption of hydrogen produced via the Volmer reaction, which is conducive to the formation of the *N–NH intermediate (i.e., the potential determining step, PDS) on adjacent Sm sites, and thereby significantly promotes the reaction kinetics of ENRR. The PDS free energy for the catalyst is comparable with the values at the peak of the ENRR volcano plots of leading transition metal catalyst surfaces

Fragile X Mental Retardation Protein Regulates Proliferation and Differentiation of Adult Neural Stem/Progenitor Cells

Fragile X syndrome (FXS), the most common form of inherited mental retardation, is caused by the loss of functional fragile X mental retardation protein (FMRP). FMRP is an RNA–binding protein that can regulate the translation of specific mRNAs. Adult neurogenesis, a process considered important for neuroplasticity and memory, is regulated at multiple molecular levels. In this study, we investigated whether Fmrp deficiency affects adult neurogenesis. We show that in a mouse model of fragile X syndrome, adult neurogenesis is indeed altered. The loss of Fmrp increases the proliferation and alters the fate specification of adult neural progenitor/stem cells (aNPCs). We demonstrate that Fmrp regulates the protein expression of several components critical for aNPC function, including CDK4 and GSK3β. Dysregulation of GSK3β led to reduced Wnt signaling pathway activity, which altered the expression of neurogenin1 and the fate specification of aNPCs. These data unveil a novel regulatory role for Fmrp and translational regulation in adult neurogenesis