Acetylene Semihydrogenation over Pd-Bi Intermetallic Compounds: A DFT Combined with Microkinetic Modeling Study.

Acetylene semihydrogenation is an important process both theoretically and experimentally. Pure Pd catalysts usually suffer from limited selectivity for ethylene products and poor stability. Pd-Bi bimetallic compounds are synthesized and show not only excellent catalytic performance but also remarkable long-term stability. However, the detailed mechanism is still unclear. In this paper, the acetylene semihydrogenation mechanism on Pd(100), Pd3Bi1(100), and Pd1Bi1(100) is studied by density functional theory (DFT) calculation and microkinetic modeling. Adding Bi causes the surface d-band center (εd) to move to a lower energy, and the adsorption strength of the intermediate becomes weaker. Besides, ethylidyne (CCH3) formation becomes more difficult on the Pd-Bi alloy due to the lack of continuous surface Pd atoms. As a spectator, CCH3 deactivates the Pd and Pd-Bi alloys by a steric effect. However, the selectivity for ethylene on the Pd-Bi alloy is still high because of the weakly bonded ethylene. We found the relationship between εd and the catalysts' activity and selectivity. This study may supply some clues for the design of selective hydrogenation catalysts.

Transcriptional evidence for transient regulation of muscle regeneration by brown adipose transplant in the rotator cuff.

Chronic rotator cuff (RC) injuries can lead to a degenerative microenvironment that favors chronic inflammation, fibrosis, and fatty infiltration. Recovery of muscle structure and function will ultimately require a complex network of muscle resident cells, including satellite cells, fibro-adipogenic progenitors (FAPs), and immune cells. Recent work suggests that signaling from adipose tissue and progenitors could modulate regeneration and recovery of function, particularly promyogenic signaling from brown or beige adipose (BAT). In this study, we sought to identify cellular targets of BAT signaling during muscle regeneration using a RC BAT transplantation mouse model. Cardiotoxin injured supraspinatus muscle had improved mass at 7 days postsurgery (dps) when transplanted with exogeneous BAT. Transcriptional analysis revealed transplanted BAT modulates FAP signaling early in regeneration likely via crosstalk with immune cells. However, this conferred no long-term benefit as muscle mass and function were not improved at 28 dps. To eliminate the confounding effects of endogenous BAT, we transplanted BAT in the "BAT-free" uncoupling protein-1 diphtheria toxin fragment A (UCP1-DTA) mouse and here found improved muscle contractile function, but not mass at 28 dps. Interestingly, the transplanted BAT increased fatty infiltration in all experimental groups, implying modulation of FAP adipogenesis during regeneration. Thus, we conclude that transplanted BAT modulates FAP signaling early in regeneration, but does not grant long-term benefits.

Mechanistic investigation of methanol-to-olefins conversion catalyzed by H-ZSM-5 zeolite: a DFT study.

CONTEXT: The mechanisms for the formation of the first C - C bond and lower olefins on methanol to olefins (MTO) conversion on H-ZSM-5 had been focused in dispute. In this paper, density functional theory has been used to study the reaction mechanisms of methanol to olefins on ZSM-5. The configurations of reactants, intermediates, products and transition state of the numerous reactions involved in such a process have been optimized, as well as the elementary reactions related to these configurations were determined by the calculation of corresponding activation energy barriers and reaction heats. Here, two different kinds of the mechanisms were proposed for the formation of dimethyl ether (DME), one involving an associative interaction of two methanol molecules with the zeolite Brønsted acid sites and the other occurring via a surface methoxy species and a methanol molecule. A critical intermediate of the methoxy methyl cation was theoretically verified by the reaction of the methoxy species and dimethyl ether. Besides, it was found that the first intermediates containing a C - C bond were 1,2-dimethoxyethane and 2-methoxy-ethanolare, in which the former was formed from methoxy species with dimethyl ether and the latter was formed from methanol by onium ions((CH3)2O+CH2CH2OCH3), respectively. For the whole reaction mechanism, the results in this paper indicated that the ethene formation is more favorable than propylene formation due to the low activation energy barrier for ethene formation (123.49 vs. 162.09 kJ.mol-1). From these calculations, it would be concluded that ethene is the first alkene product that induces the occurrence of the hydrocarbon pool mechanism. METHODS: All the periodic density function theory (DFT) calculations were performed by the Vienna Ab Initio Simulation package (VASP). The interaction between nucleus and valence electron was described using the pseudopotentials found in the projector augmented wave (PAW) method. PBE-D3 was used in the whole DFT calculations and CI-NEB was used to locate transition state.

Ultrafine Nanoclusters Unlocked 3d-4f Electronic Ladders for Efficient Electrocatalytic Water Oxidation.

The vast extensional planes of two-dimensional (2D) nanomaterials are recognized as desirable ground for electrocatalytic reactions. However, they tend to exhibit catalytic inertia due to their surface-ordered coordination configurations. Herein, an in situ autoxidation strategy enables high-density grafting of ultrafine CeO2 nanoclusters on 2D Co(OH)2. Affluent active units were activated at the inert interface of Co(OH)2 via the formation of Co-O-Ce units. The optimized catalyst exhibits oxygen evolution reaction activity with an overpotential of 83 mV lower than that of Co(OH)2 at 10 mA cm-2. The cascade orbital coupling between Co (3d) and Ce (4f) in Co-O-Ce units drives electron transfer by unlocking a "d-f electron ladder". Meanwhile, the bond-order theorem analyses and the d-band center show that the occupancy of Co-3d-eg is optimized to balance the adsorption-desorption process of active sites to the key reaction intermediate *OOH, thereby making it easier to release oxygen. This work will drive the development of wider area electron modulation methods and provide guidance for the surface engineering of 2D nanomaterials.

Dry Reforming of Methane on Ni/LaZrO2 Catalyst under External Electric Fields: A Combined First-Principles and Microkinetic Modeling Study.

Dry reforming of methane (DRM) reaction has great potential in reducing the greenhouse effect and solving energy problems. Herein, the DRM reaction mechanism and activity on Ni16/LaZrO2 catalyst under electric fields were comprehensively investigated by combining density functional theory calculations with microkinetic modeling. The results showed that La doping increases the interaction between Ni and ZrO2 by Ni cluster transfer of more electrons. The adsorption strength of species followed the order Ni16/ZrO2 > Ni16/LaZrO2, which is consistent with the results for the d-band center but opposite to the metal-support interaction. The best DRM reaction path on Ni16/LaZrO2 was the CH2-O pathway, which is different from the CH-O pathway on Ni(111) and Ni16/ZrO2. Both positive and negative electric fields of strong and weak metal-support interactions reduced the energy barrier of DRM reaction. Importantly, our results showed that the more dispersed and smaller Ni12/LaZrO2 model by considering the dispersing effect induced by La doping, which displayed very different results from that of Ni16/LaZrO2: reduced the energy barrier for methane decomposition, thereby promoting DRM reaction activity. Microkinetic results showed that the carbon deposition behavior of DRM becomes weaker on Ni16/LaZrO2 due to the suppression of methane decomposition in the presence of La doping compared to Ni16/ZrO2, but the opposite result is obtained on Ni12/LaZrO2. The order of DRM reactivity was Ni16/LaZrO2 < Ni16/ZrO2 < Ni12/LaZrO2, which is consistent with the experiment observations. The conversion of methane and CO2 was higher in positive electric fields than in negative electric fields at low temperatures, but the results were opposite at high temperature. Negative electric fields can improve the carbon deposition resistance of Ni-based catalysts compared to positive electric fields. The degree of rate control analysis showed that CHx* oxidation also plays an important role in the DRM reaction. We envision that this study could provide a deeper understanding for guiding the widespread application of electric field catalysis.

Mechanisms of CH4 activation over oxygen-preadsorbed transition metals by ReaxFF and AIMD simulations.

The chemisorbed oxygen usually promotes the CH bond activation over less active metals like IB group metals but has no effect or even an inhibition effect over more active metals like Pd based on the static electronic structure study. However, the understanding in terms of dynamics knowledge is far from complete. In the present work, methane dissociation on the oxygen-preadsorbed transition metals including Au, Cu, Ni, Pt, and Pd is systemically studied by reactive force field (ReaxFF). The ReaxFF simulation results indicate that CH4 molecules mainly undergo the direct dissociation on Ni, Pt, and Pd surfaces, while undergo the oxygen-assisted dissociation on Au and Cu surfaces. Additionally, the ab initio molecular dynamics (AIMD) simulations with the umbrella sampling are employed to study the free-energy changes of CH4 dissociation, and the results further support the CH4 dissociation pathway during the ReaxFF simulations. The present results based on ReaxFF and AIMD will provide a deeper dynamic understanding of the effects of pre-adsorbed oxygen species on the CH bond activation compared to that of static DFT.

Investigation of the oxygen coverage effect on the direct epoxidation of propylene over copper through DFT calculations.

The direct epoxidation of propylene is one of the most important selective oxidation reactions in industry. The development of high-performance copper-based catalysts is the key to the selective oxidation technology and scientific research of propylene. The mechanism of propylene's partial oxidation catalyzed by Cu(111) under different oxygen coverage conditions was studied using density functional theory calculations and microkinetic modeling. We report here in detail two parallel reaction pathways: dehydrogenation and epoxidation. The transition states and energy distributions of the intermediates and products were calculated. The present results showed that propylene oxide (PO) selectivity was high under low oxygen coverage, and increasing the oxygen coverage would decrease the PO selectivity but increase the PO activity, and there was an inverse relationship between PO selectivity and activity. Increasing oxygen coverage would reduce the energy barrier for the C-O bond formation of C3H5O due to the weaker adsorption strength of C3H5, thus decreasing the PO formation selectivity. On the other hand, increasing oxygen coverage would reduce the energy barrier for the possible reaction steps of propylene epoxidation in general, and thus increasing the catalytic activity. It might be proposed that the active site for propylene epoxidation is the metallic copper or partially oxidized copper in terms of the change of PO formation selectivity with oxygen coverage.

Comparative theoretical study of CO2 activation on clean and potassium-preadsorbed low index surfaces of transition metals.

CONTEXT: The efficient catalysis of CO2 adsorption and activation presents a formidable challenge due to its pronounced thermodynamic stability and kinetic inertia. Previous experiments have left gaps in understanding the promotional effects and underlying mechanism of potassium. In this study, we systematically investigate CO2 adsorption and activation on clean and potassium-preadsorbed low index surfaces of transition metals. Theoretical results reveal a substantial augmentation in CO2 binding strength when potassium is introduced, concomitant with a general reduction in activation energies. Notably, linear correlations are significant on close-packed metal surfaces without and with potassium additive. Through a comprehensive analysis encompassing geometric parameters, electronic structures, and energy decomposition, we discern the physical underpinnings of the potassium effect. This enhancement is primarily ascribed to direct electron transfer and dipole-dipole interactions. Furthermore, we scrutinize the impact of an external electric field, demonstrating that the application of a negative electric field accelerates CO2 activation, mirroring the effects observed with potassium. METHODS: All the periodic density function theory (DFT) calculations were performed by the Vienna Ab Initio Simulation package (VASP). The interaction between nucleus and valence electron was described using the pseudopotentials found in the projector augmented wave method (PAW). Throughout the entire work, the Bayesian error estimation functional (BEEF) was used.

M supported on Al-defective Al2-δO3 (M = Fe, Co, Ni, Cu, Ag, Au) as catalysts for acetylene semi-hydrogenation: a theoretical perspective.

Semi-hydrogenation of acetylene is of great importance for both industry and academia. High prices and limited supplements of noble metals leave room for developing base metal catalysts. Experiments revealed the atomically dispersed Cu supported by Al2O3 with excellent long-term stability and high ethylene selectivity, but the physical nature has rarely been investigated theoretically. DFT calculations and microkinetic modeling revealed that the surface OH species could stabilize Cu1/Al2-δO3 and enhance its catalytic performance. The selectivity of ethylene formation decreases with increasing copper clusters (e.g., Cu1/Al2-δO3> Cu4/Al2-δO3> Cu8/Al2-δO3), meaning that the atomically dispersed copper may be a potential candidate for acetylene semi-hydrogenation. The structures of a series of single site catalysts M1/Al2-δO3 (M = Fe, Co, Ni, Ag, Au) are similar to that of Cu1/Al2-δO3, but their performances in catalyzing acetylene semi-hydrogenation are different. M1/Al2-δO3 (M = Ag, Au) shows higher selectivity than Cu1/Al2-δO3, while M1/Al2-δO3 (M = Fe, Co, Ni) demonstrates a higher turnover frequency (TOF) of ethylene than Cu1/Al2-δO3. Moreover, our results indicate that the Ni1-Cu1/Al2-δO3 alloy shows both high activity and ethylene selectivity. The present results show a compensation between the reactivity and the selectivity, suggesting that alloys of VIIIB metals with IB metals like Ni1-Cu1/Al2-δO3 may be efficient candidate catalysts in acetylene selective hydrogenation.

Theoretical insight into the promotion effect of potassium additive on the water-gas shift reaction over low-coordinated Au catalysts.

CONTEXT: How to elucidate the effect of alkali metal promoters on gold-catalyzed water-gas shift reaction intrinsically remains a challenging, because that the complex synergy effects such as strong metal-support interactions, interfacial effects, and charge transfer of supported metal catalysts makes people difficulty in the understanding the alkali promotion phenomenon in nature. Herein, we report a systematically study of whole water-gas shift reaction mechanism on pure and the K-modified defected-Au(211) (i.e., by removing one surface Au atom from perfect Au(211) and make one model with the Au-Au coordination number is six) by using the microkinetic modeling based on first principles. Our results indicate that the presence of K can increase the adsorption ability of oxygen-containing species via the attractive coulomb interaction, has no significant effect on the adsorption of H species, but inhibits the adsorption of CO due to the steric effect. K promoter stabilizes the water adsorption by ~0.3 eV, which results in one order increasing of whole reaction rate. Interestingly, the strong promotion effect of the K can be assigned to the significant direct space interaction between K and the adsorbate H2O* through the inducted electric field, which can be further confirmed by the posed negative electric field on the unpromoted D-Au(211). Microkinetic modeling results revealed that the carboxyl mechanism is the most likely to occur, redox mechanism is the next one, and the formate mechanism is the least likely to occur. For different kinds of alkali metal additives, the adsorption strength of water molecules gradually weakens from Li to Cs, but Na shows the best promoter behavior at the low temperature. By considering the effect of K contents on the reactivity of water-gas shift reaction, we found that the K with the medium coverage (~0.2~0.3 ML) has the strongest promoting effect. It is expected that the conclusion of this work can be extended to other WGSR catalytic systems like Cu(or Pt). METHODS: All calculations were performed by using the plane-wave based periodic method implemented in Vienna ab initio simulation package (VASP, version 5.4.4), where the ionic cores are described by the projector augmented wave (PAW) method. The exchange and correlation energies were computed using the Perdew, Burke and Ernzerhof functional with the vdw correction (PBE-D3). The transition states (TSs) were searched using the climbing image nudged elastic band (CI-NEB) method. Some electronic structure properties like work function was predicated by the DS-PAW software. Microkinetic simulation was carried out using MKMCXX software.

Multilayered Molybdate Microflowers Fabricated by One-Pot Reaction for Efficient Water Splitting.

The development of high-performance, low-cost and rapid-production bifunctional electrocatalysts towards overall water splitting still poses huge challenges. Herein, the authors utilize a facile hydrothermal method to synthesize a novel structure of Co-doped ammonium lanthanum molybdate on Ni foams (Co-ALMO@NF) as self-supported electrocatalysts. Owing to large active surfaces, lattice defect and conductive channel for rapid charge transport, Co-ALMO@NF exhibits good electrocatalytic performances which requires only 349/341 mV to achieve a high current density of 600 mA cm-2 for hydrogen evolution reaction (HER) and oxygen evolution reaction (OER), respectively. Besides, a low cell voltage of 1.52 V is required to reach the current density of 10 mA cm-2 in alkaline medium along with an excellent long-term stability for two-electrode configurations. Density functional theory calculations are performed to reveal the reaction mechanism on Co-ALMO@NF, which shows that the Mo site is the most favorable ones for HER, while the introduction of Co is beneficial to reduce the adsorption intensity on the surface of Co-ALMO@NF, thus accelerating OER process. This work highlighted the importance of the structural design for self-supporting electrocatalysts.

Leptin mediates the regulation of muscle mass and strength by adipose tissue.

Adipose tissue secretes numerous cytokines (termed 'adipokines') that have known or hypothesized actions on skeletal muscle. The majority of adipokines have been implicated in the pathological link between excess adipose and muscle insulin resistance, but approximately half also have documented in vitro effects on myogenesis and/or hypertrophy. This complexity suggests a potential dual role for adipokines in the regulation of muscle mass in homeostasis and the development of pathology. In this study, we used lipodystrophic 'fat-free' mice to demonstrate that adipose tissue is indeed necessary for the development of normal muscle mass and strength. Fat-free mice had significantly reduced mass (∼15%) and peak contractile tension (∼20%) of fast-twitch muscles, a slowing of contractile dynamics and decreased cross-sectional area of fast twitch fibres compared to wild-type littermates. These deficits in mass and contractile tension were fully rescued by reconstitution of ∼10% of normal adipose mass, indicating that this phenotype is the direct consequence of absent adipose. We then showed that the rescue is solely mediated by the adipokine leptin, as similar reconstitution of adipose from leptin-knockout mice fails to rescue mass or strength. Together, these data indicate that the development of muscle mass and strength in wild-type mice is dependent on adipose-secreted leptin. This finding extends our current understanding of the multiple roles of adipokines in physiology as well as disease pathophysiology to include a critical role for the adipokine leptin in muscle homeostasis. KEY POINTS: Adipose-derived cytokines (adipokines) have long been implicated in the pathogenesis of insulin resistance in obesity but likely have other under-appreciated roles in muscle physiology. Here we use a fat-free mouse to show that adipose tissue is necessary for the normal development of muscle mass and strength. Through add-back of genetically modified adipose tissue we show that leptin is the key adipokine mediating this regulation. This expands our understanding of leptin's role in adipose-muscle signalling to include development and homeostasis and adds the surprising finding that leptin is the sole mediator of the maintenance of muscle mass and strength by adipose tissue.

Qualitative study of the learning and studying process of resident physicians in China.

BACKGROUND: Clinical medical education is essential in physician training. This study developed recommendations for medical residency course design on the basis of the perspectives of learners in China and how they interact with their environment. The central research topic was the professional development and learning process of residents, including the obstacles that hinder and factors that promote their learning, their views on existing teaching methods, interaction between teachers and medical teams, and suggestions for designing future residency training programs. METHODS: This study had a qualitative research design. Interviews were conducted between July and October 2019 with 17 specialist residents and 12 assistant general practitioner residents from the department of education of the hospital. The participants were recruited from Qingyuan People's Hospital in Guangdong Province, China. The interview outlines focused on the following four themes: clinical learning experiences and reflections on learning, experience of interaction with patients, experience of working with other medical personnel, and future learning directions. RESULTS: To overcome challenges in clinical learning, the residents mainly learned from their teachers and focused specifically on their own experiences. Regarding teaching methods and designs in clinical medicine, the residents preferred large-group, small-group, and bedside teaching and reported that bedside teaching enables the resolution of clinical problems, initiates self-learning, and improves diagnostic thinking. They disliked teachers with low teaching motivation or who were reluctant to interact with them and favored teachers who had strong teaching skills and respect for their students. CONCLUSIONS: The residents suggested that clinical and active learning must be the main learning method for developing general medical competencies. Residency training must be conducted in an environment that facilitates residents' learning and meaningful learning activities. The interdependent symbiotic relationships in the education ecosystem can serve as a reference for designing residency courses.

Harnessing adipose stem cell diversity in regenerative medicine.

Since the first isolation of mesenchymal stem cells from lipoaspirate in the early 2000s, adipose tissue has been a darling of regenerative medicine. It is abundant, easy to access, and contains high concentrations of stem cells (ADSCs) exhibiting multipotency, proregenerative paracrine signaling, and immunomodulation-a winning combination for stem cell-based therapeutics. While basic science, preclinical and clinical findings back up the translational potential of ADSCs, the vast majority of these used cells from a single location-subcutaneous abdominal fat. New data highlight incredible diversity in the adipose morphology and function in different anatomical locations or depots. Even in isolation, ADSCs retain a memory of this diversity, suggesting that the optimal adipose source material for ADSC isolation may be application specific. This review discusses our current understanding of the heterogeneity in the adipose organ, how that heterogeneity translates into depot-specific ADSC characteristics, and how atypical ADSC populations might be harnessed for regenerative medicine applications. While our understanding of the breadth of ADSC heterogeneity is still in its infancy, clear trends are emerging for application-specific sourcing to improve regenerative outcomes.

Electric Field Stimulation for the Functional Assessment of Isolated Dorsal Root Ganglion Neuron Excitability.

Genetically encoded calcium indicators have proven useful for characterizing dorsal root ganglion neuron excitability in vivo. Challenges persist in achieving high spatial-temporal resolutions in vivo, however, due to deep tissue imaging and motion artifacts that may be limiting technical factors in obtaining measurements. Here we report an ex vivo imaging method, using a peripheral neuron-specific Advillin-GCaMP mouse line and electric field stimulation of dorsal root ganglion tissues, to assess the sensitivity of neurons en bloc. The described method rapidly characterizes Ca2+ activity in hundreds of dorsal root ganglion neurons (221 ± 64 per dorsal root ganglion) with minimal perturbation to the in situ soma environment. We further validate the method for use as a drug screening platform with the voltage-gated sodium channel inhibitor, tetrodotoxin. Drug treatment led to decreased evoked Ca2+ activity; half-maximal response voltage (EV50) increased from 13.4 V in untreated tissues to 21.2, 23.3, 51.5 (p < 0.05), and 60.6 V (p < 0.05) at 0.01, 0.1, 1, and 10 µM doses, respectively. This technique may help improve an understanding of neural signaling while retaining tissue structural organization and serves as a tool for the rapid ex vivo recording and assessment of neural activity.

Effects of vitamin C on function of different subtypes of glycine receptors / 中国药理学通报

Aim To investigate the effects of vitamin C (VC) on glycine receptor (GlyR) subtypes. Methods The HEK-293T cells were transfected with plasmids expressing different subtypes of GlyR. Then the cells were incubated with different concentrations of VC. The EC2 concentration of glycine-activated currents were recorded by patch clamp before or after incubation of VC. The effects of the sodium-dependent vitamin C transporter-type 2 ( SVCT2 ) inhibitor sulfinpyrazone on VC induced potentiation of GlyRs were also examined. The method of amino acid point mutation was used to explore the critical site for interaction between VC and GlyR. Results Ascorbic acid dose-dependently increased the currents mediated by GlyRal and GlyRa3, with a3 subunits being the most sensitive to VC. Ascorbic acid had no significant effect on the current mediated by the al subunit of GlyRs. Cell incubation with sulfinpyrazone did not affect the VC induced potentiation of GlyR function. The mutation of Ser296 at the third transmembrane domain of a3 GlyR significantly reduced the potentiation of VC on GlyR func-tion. Conclusions Ascorbic acid can enhance the function of GlyR al and a3 subunits, but not a2 sub- unit. Such enhancement is not likely to be an effect oc- curing inside cells. The Ser296 of GlyR plays a key role in the VC induced enhancement of GlyR function.

First-principles theoretical study on dry reforming of methane over perfect and boron-vacancy-containing h-BN sheet-supported Ni catalysts.

The entire reaction mechanism of the dry reforming of methane (DRM) as well as the competition processes over perfect and boron-vacancy-containing h-BN sheet-supported Ni-catalysts (labeled Ni2/h-BN and Ni2/h-BN-B-D) was studied by density functional theory calculations in the present work. Our calculation results show that B-defected h-BN strongly binds to the Ni2 active sites (i.e., shows a strong metal-support interaction (SMSI) character) due to the better electron transfer between Ni2 sites and the support. It was found that CH4 is easier to activate than molecular CO2. The activation of CO2 occurs on the surface of Ni2/h-BN through a direct route, whereas it is prone to follow a hydrogen-assisted path for Ni2/h-BN-B-D via the COOH* intermediate, and the results show that the oxidant O* is easily formed on the surface of Ni2/h-BN-B-D. It was also found that O* is the main oxidant agent for CHx* intermediates through the CH3-O oxidation mechanism. The reaction kinetic analysis indicated that the reverse water gas shift reaction (RWGS) is much more favorable than DRM (1.30 vs. 1.72 eV) over the Ni2/h-BN system, whereas the RWGS and DRM are comparable on Ni2/h-BN-B-D (1.77 vs. 1.66 eV), suggesting a high DRM activity on Ni2/h-BN-B-D. Moreover, neither methane cracking nor a Boudouard reaction to form C* species is thermodynamically and kinetically unfavorable over Ni2/h-BN-B-D; hence, Ni2/h-BN-B-D has strong resistance to carbon deposition. Compared to Ni(111), both Ni2/h-BN-B-D and Ni2/h-BN show strong resistance to carbon deposition. Our results provide a further mechanistic understanding of the DRM over an Ni-based catalyst through the SMSI characteristic and the SMSI favors strong resistance to carbon deposition.

Eliminating senescent chondrogenic progenitor cells enhances chondrogenesis under intermittent hydrostatic pressure for the treatment of OA.

BACKGROUND: Osteoarthritis (OA) is a major cause of limb dysfunction, and distraction arthroplasty which generates intermittent hydrostatic pressure (IHP) is an effective approach for OA treatment. However, the result was not always satisfactory and the reasons remained unresolved. Because aging is recognized as an important risk factor for OA and chondrogenic progenitor cells (CPCs) could acquire senescent phenotype, we made a hypothesis that CPCs senescence could have harmful effect on chondrogenesis and the outcome of distraction arthroplasty could be improved by eliminating senescent CPCs pharmacologically. METHODS: The role of senescent CPCs on distraction arthroplasty was first determined by comparing the cartilage samples from the failure and non-failure patients. Next, the biological behaviors of senescent CPCs were observed in the in vitro cell culture and IHP model. Finally, the beneficial effect of senescent CPCs clearance by senolytic dasatinib and quercetin (DQ) on cartilage regeneration was observed in the in vitro and in vivo IHP model. RESULTS: Larger quantities of senescent CPCs along with increased IL-1 ß secretion were demonstrated in the failure patients of distraction arthroplasty. Senescent CPCs revealed impaired proliferation and chondrogenic capability and also had increased IL-1 ß synthesis, typical of senescence-associated secretory phenotype (SASP). CPCs senescence and SASP formation were mutually dependent in vitro. Greater amounts of senescent CPCs were negatively correlated with IHP-induced chondrogenesis. In contrast, chondrogenesis could be significantly improved by DQ pretreatment which selectively induced senescent CPCs into apoptosis in the in vitro and in vivo IHP model. Mechanistically, senescent CPCs elimination could decrease SASP formation and therefore promote the proliferation and chondrogenic regeneration capacity of the surrounding survived CPCs under IHP stimulation. CONCLUSIONS: Eliminating senescent CPCs by senolytics could decrease SASP formation and improve the result of joint distraction arthroplasty effectively. Our study provided a novel CPCs senescence-based therapeutic target for improving the outcome of OA treatment.

Selective Oxidation of Propylene on Cu2O(111) and Cu2O(110) Surfaces: A Systematically DFT Study.

Density functional theory calculations with a Hubbard U correction were used to investigate the selective oxidation of propylene on Cu2O(111) and Cu2O(110) surfaces, and the mechanism for the selective oxidation of propylene was discussed. On both surfaces, acrolein can be generated by two H-stripping reactions in the allylic hydrogen stripping path, while propylene oxide (PO), propanal, and acetone can be created through the propylene oxametallacycle intermediates in the epoxidation path. Our calculation results indicated that Cu2O has a high crystal plane-controlled phenomenon for the selective oxidation of propylene. It was found that the formations of propanal and acetone are unfavorable kinetically and acrolein is the main product on the (111) surface. On the (110) surface, the activation barrier of acrolein formation is too high to produce and PO becomes the favored product, which is different from the case of the (111) surface. Moreover, energetic span model analysis was carried out to discuss the selective oxidation of propylene on these two surfaces and confirm the above calculations. The present study can help people to design the proper crystal plane catalyst to get the target product of PO with high selectivity and activity in the selective oxidation of propylene.

AKT3 deficiency in M2 macrophages impairs cutaneous wound healing by disrupting tissue remodeling.

AKT signaling and M2 macrophage-guided tissue repair are key factors in cutaneous wound healing. A delay in this process threatens human health worldwide. However, the role of AKT3 in delayed cutaneous wound healing is largely unknown. In this study, histological staining and transcriptomics demonstrated that prolonged tissue remodeling delayed wound healing. This delay was accompanied by defects in AKT3, collagen alpha-1(I) chain (COL1A1), and collagen alpha-1(XI) chain (COL11A1) expression and AKT signaling. The defect in AKT3 expression was M2 macrophage-specific, and decreased AKT3 protein levels were observed in CD68/CD206-positive macrophages from delayed wound tissue. Downregulation of AKT3 in M2 macrophages did not influence cell polarization but impaired collagen organization by inhibiting COL1A1 and COL11A1 expression in human skin fibroblasts (HSFs). Moreover, a co-culture model revealed that the downregulation of AKT3 in the human monocytic cell line (THP-1)-derived M2 macrophages impaired HSF proliferation and migration. Finally, cutaneous wound healing in AKT3-/- mice was much slower than that of AKT3+/+ mice, and F4/80 macrophages from the AKT3-/- mice had an impaired ability to promote wound healing. Thus, the downregulation of AKT3 in M2 macrophages prolonged tissue remodeling and delayed cutaneous wound healing.