Ambient electrochemical N
reduction is emerging as a highly promising alternative to the Haber-Bosch process but is typically hampered by a high reaction barrier and competing hydrogen evolution, ...leading to an extremely low Faradaic efficiency. Here, we demonstrate that under ambient conditions, a single-atom catalyst, iron on nitrogen-doped carbon, could positively shift the ammonia synthesis process to an onset potential of 0.193 V, enabling a dramatically enhanced Faradaic efficiency of 56.55%. The only doublet coupling representing
NH
in an isotopic labeling experiment confirms reliable NH
production data. Molecular dynamics simulations suggest efficient N
access to the single-atom iron with only a small energy barrier, which benefits preferential N
adsorption instead of H adsorption via a strong exothermic process, as further confirmed by first-principle calculations. The released energy helps promote the following process and the reaction bottleneck, which is widely considered to be the first hydrogenation step, is successfully overcome.
As a new family of two-dimensional (2D) materials, MXene, with many attractive physicochemical properties, has attracted increasing attentions and been applied for various applications. Here, for the ...first time, ultrathin MXene membranes with thickness down to several tens of nanometers were developed for pervaporation desalination by stacking synthesized atomic-thin MXene nanosheets. Influences such as lateral size of MXene nanosheets and feed temperature on the resulting membrane performance were systematically investigated. Owing to unique 2D interlayer channels as well as high hydrophilicity, the ultrathin MXene membrane with ~60nm exhibited high water flux (85.4Lm−2h−1) and salt rejection (99.5%) with feed concentration of 3.5wt% NaCl at 65°C. In addition, the MXene membrane showed a good long-term stability and performance in synthetic seawater system. The high-performing ultrathin 2D MXene membrane developed here in this work offers great potential for pervaporation applications.
Display omitted
•Ultrathin 2D Ti3C2Tx MXene membrane was designed and fabricated.•MXene membrane was first reported for pervaporation process.•Abundant oxygen-containing groups enabled MXene membranes to be hydrophilic.•High water flux (85.4Lm-2h-1) with high salt rejection (99.5%) was realized.
Full text
Available for:
GEOZS, IJS, IMTLJ, KILJ, KISLJ, NLZOH, NUK, OILJ, PNG, SAZU, SBCE, SBJE, UL, UM, UPUK, ZRSKP
Statins are inhibitors of HMG-CoA reductase, the rate-limiting enzyme of cholesterol biosynthesis, and have been clinically used to treat cardiovascular disease. However, a paradoxical increase of ...reductase protein following statin treatment may attenuate the effect and increase the side effects. Here we present a previously unexplored strategy to alleviate statin-induced reductase accumulation by inducing its degradation. Inspired by the observations that cholesterol intermediates trigger reductase degradation, we identify a potent degrader, namely Cmpd 81, through structure-activity relationship analysis of sterol analogs. Cmpd 81 stimulates ubiquitination and degradation of reductase in an Insig-dependent manner, thus dramatically reducing protein accumulation induced by various statins. Cmpd 81 can act alone or synergistically with statin to lower cholesterol and reduce atherosclerotic plaques in mice. Collectively, our work suggests that inducing reductase degradation by Cmpd 81 or similar chemicals alone or in combination with statin therapy can be a promising strategy for treating cardiovascular disease.
Lithium–sulfur (Li–S) batteries, due to the high theoretical energy density, are regarded as one of the most promising candidates for breaking the limitations of energy‐storage system based on Li‐ion ...batteries. Tremendous efforts have been made to meet the challenge of high‐performance Li–S batteries, in which a sulfur loading of above 5 mg cm−2 delivers an areal capacity higher than 5 mAh cm−2 without compromising specific capacity and cycling stability for practical applications. However, serious problems have been exposed during the scaling up of the sulfur loading. In this review, based on mechanistic insights into structural configuration, catalytic conversion, and interfacial engineering, the problems and corresponding strategies in the development of high‐loading Li–S batteries are highlighted and discussed, aiming at bridging the gap between fundamental research and practical cell‐level designs. Stemming from the current achievements, future directions targeting the high‐energy‐density Li–S batteries for commercialization are proposed.
Challenges and corresponding strategies involving high‐loading lithium–sulfur batteries are comprehensively summarized and discussed based on shared mechanisms and concepts, from which perspectives and guidelines are provided for developing future strategies tackling intrinsic problems in high‐loading Li–S batteries.
Full text
Available for:
FZAB, GIS, IJS, KILJ, NLZOH, NUK, OILJ, SAZU, SBCE, SBMB, UL, UM, UPUK
To understand the effect of third order Lovelock gravity,
P
–
V
criticality of topological AdS black holes in Lovelock–Born–Infeld gravity is investigated. The thermodynamics is further explored with ...some more extensions and in some more detail than the previous literature. A detailed analysis of the limit case
β
→
∞
is performed for the seven-dimensional black holes. It is shown that, for the spherical topology,
P
–
V
criticality exists for both the uncharged and the charged cases. Our results demonstrate again that the charge is not the indispensable condition of
P
–
V
criticality. It may be attributed to the effect of higher derivative terms of the curvature because similar phenomenon was also found for Gauss–Bonnet black holes. For
k
=
0
, there would be no
P
–
V
criticality. Interesting findings occur in the case
k
=
-
1
, in which positive solutions of critical points are found for both the uncharged and the charged cases. However, the
P
–
v
diagram is quite strange. To check whether these findings are physical, we give the analysis on the non-negative definiteness condition of the entropy. It is shown that, for any nontrivial value of
α
, the entropy is always positive for any specific volume
v
. Since no
P
–
V
criticality exists for
k
=
-
1
in Einstein gravity and Gauss–Bonnet gravity, we can relate our findings with the peculiar property of third order Lovelock gravity. The entropy in third order Lovelock gravity consists of extra terms which are absent in the Gauss–Bonnet black holes, which makes the critical points satisfy the constraint of non-negative definiteness condition of the entropy. We also check the Gibbs free energy graph and “swallow tail” behavior can be observed. Moreover, the effect of nonlinear electrodynamics is also included in our research.
Full text
Available for:
DOBA, IZUM, KILJ, NUK, PILJ, PNG, SAZU, SIK, UILJ, UKNU, UL, UM, UPUK
The impact of crop peels on reducing pesticide residue levels in crops during household food processing was evaluated in this study. We proposed a series of pesticide fate models to simulate the ...removal efficiency of residues in crop peels and medullas (i.e., pulps) via soaking and washing. The simulated results indicated that the variation in the peel thickness had a significant impact on residue removal from the peel compartment. However, the peel compartment had a low impact on the removal efficiency of pesticide residues from the medulla compartment, as demonstrated by the simulated results from the non-peel model (i.e., already peeled crops). In addition, we observed that even though systemic pesticides have a higher potential to penetrate from the peel into the medulla, the increasing residue level caused by the mass transfer from the peel into the medulla is too low to cause human health damage, because the absolute mass of residues in the peel is considerably small. Based on the simulation results, we concluded that washing or soaking crops with or without peels using water is not effective in reducing residue levels in crop medullas. Modifying crops into slices, instead of directly washing or soaking crops, could significantly improve the removal efficiency of pesticide residues inside the medulla. The models proposed in this study can improve our understanding on the fate of pesticides in crops during household food processing.
Full text
Available for:
CEKLJ, EMUNI, FIS, FZAB, GEOZS, GIS, IJS, IMTLJ, KILJ, KISLJ, MFDPS, NLZOH, NUK, OILJ, PNG, SAZU, SBCE, SBJE, SBMB, SBNM, UKNU, UL, UM, UPUK, VKSCE, ZAGLJ
The oxygen evolution reaction (OER) has been explored extensively for reliable hydrogen supply to boost the energy conversion efficiency. The superior OER performance of newly developed non‐noble ...metal electrocatalysts has concealed the identification of the real active species of the catalysts. Now, the critical active phase in nickel‐based materials (represented by NiNPS) was directly identified by observing the dynamic surface reconstruction during the harsh OER process via combining in situ Raman tracking and ex situ microscopy and spectroscopy analyses. The irreversible phase transformation from NiNPS to α‐Ni(OH)2 and reversible phase transition between α‐Ni(OH)2 and γ‐NiOOH prior to OER demonstrate γ‐NiOOH as the key active species for OER. The hybrid catalyst exhibits 48‐fold enhanced catalytic current at 300 mV and remarkably reduced Tafel slope to 46 mV dec−1, indicating the greatly accelerated catalytic kinetics after surface evolution.
An irreversible phase transformation was tracked in situ from NiNPS to α‐Ni(OH)2. This result and potential‐dependent reversible conversion between α‐Ni(OH)2 and γ‐NiOOH prior to OER unveil the real active species of γ‐NiOOH in self‐reconstructed Ni‐based catalysts.
Full text
Available for:
BFBNIB, FZAB, GIS, IJS, KILJ, NLZOH, NUK, OILJ, SAZU, SBCE, SBMB, UL, UM, UPUK
Following an earlier study regarding Einstein–Gauss–Bonnet-massive black holes in the presence of a Born–Infeld nonlinear electromagnetic field (Hendi,
arXiv:1510.00108
,
2016
), we study ...thermodynamical structure and critical behavior of these black holes through various methods in this paper. Geometrical thermodynamics is employed to give a picture regarding the phase transition of these black holes. Next, a new method is used to derive critical pressure and radius of the horizon of these black holes. In addition, Maxwell equal area law is employed to study the Van der Waals like behavior of these black holes. Moreover, the critical exponents are calculated and by using Ehrenfest equations, the type of phase transition is determined.
Full text
Available for:
DOBA, IZUM, KILJ, NUK, PILJ, PNG, SAZU, SIK, UILJ, UKNU, UL, UM, UPUK
There is a pressing need to shorten the development period for new materials possessing desired properties. For example, bulk metallic glasses (BMGs) are a unique class of alloy materials utilized in ...a wide variety of applications due to their attractive physical properties. However, the lack of predictive tools for uncovering the relationships between BMGs' alloy composition and desired properties limits the further application of these materials. In this study, a machine-learning (ML) approach was developed, based on a dataset of 6471 alloys, to enable the construction of a predictive ML model to describe the glass-forming ability and elastic moduli of BMGs. The model's predictions of unseen data were found to be in good agreement with most experimental values. Consequently, we determined that an alloy with a large critical-casting diameter would likely have a high mixing entropy, a high thermal conductivity, and a mixing enthalpy of approximately −28 kJ/mol, and that a BMG with a small average atomic volume would likely have a high elastic modulus. The efficacy of ML was demonstrated in furnishing a mechanistic understanding and enabling the prediction of metallic-glass properties.
Display omitted
•The machine learning based models for predicting properties of metallic glasses are developed.•Key features are selected, and expressions based on those features are generated.•The machine learning based models and expressions show good predictive and generalization ability.
Full text
Available for:
GEOZS, IJS, IMTLJ, KILJ, KISLJ, NLZOH, NUK, OILJ, PNG, SAZU, SBCE, SBJE, UILJ, UL, UM, UPUK, ZAGLJ, ZRSKP
Cholesterol is an essential lipid and its synthesis is nutritionally and energetically costly
. In mammals, cholesterol biosynthesis increases after feeding and is inhibited under fasting conditions
.... However, the regulatory mechanisms of cholesterol biosynthesis at the fasting-feeding transition remain poorly understood. Here we show that the deubiquitylase ubiquitin-specific peptidase 20 (USP20) stabilizes HMG-CoA reductase (HMGCR), the rate-limiting enzyme in the cholesterol biosynthetic pathway, in the feeding state. The post-prandial increase in insulin and glucose concentration stimulates mTORC1 to phosphorylate USP20 at S132 and S134; USP20 is recruited to the HMGCR complex and antagonizes its degradation. The feeding-induced stabilization of HMGCR is abolished in mice with liver-specific Usp20 deletion and in USP20(S132A/S134A) knock-in mice. Genetic deletion or pharmacological inhibition of USP20 markedly decreases diet-induced body weight gain, reduces lipid levels in the serum and liver, improves insulin sensitivity and increases energy expenditure. These metabolic changes are reversed by expression of the constitutively stable HMGCR(K248R). This study reveals an unexpected regulatory axis from mTORC1 to HMGCR via USP20 phosphorylation and suggests that inhibitors of USP20 could be used to lower cholesterol levels to treat metabolic diseases including hyperlipidaemia, liver steatosis, obesity and diabetes.
Full text
Available for:
FZAB, GEOZS, IJS, IMTLJ, KILJ, KISLJ, MFDPS, NLZOH, NUK, OILJ, PNG, SAZU, SBCE, SBJE, SBMB, SBNM, UKNU, UL, UM, UPUK, VKSCE, ZAGLJ
PDF
