Single-Layer Hexagonal Boron Nitride Nanopores as High-Performance Ionic Gradient Power Generators.

Atomically thin two-dimensional (2D) materials have emerged as promising candidates for efficient energy harvesting from ionic gradients. However, the exploration of robust 2D atomically thin nanopore membranes, which hold sufficient ionic selectivity and high ion permeability, remains challenging. Here, the single-layer hexagonal boron nitride (hBN) nanopores are demonstrated as various high-performance ion-gradient nanopower harvesters. Benefiting from the ultrathin atomic thickness and large surface charge (also a large Dukhin number), the hBN nanopore can realize fast proton transport while maintaining excellent cation selectivity even in highly acidic environments. Therefore, a single hBN nanopore achieves the pure osmosis-driven proton-gradient power up to ≈3 nW under 1000-fold ionic gradient. In addition, the robustness of hBN membranes in extreme pH conditions allows the ionic gradient power generation from acid-base neutralization. Utilizing 1 m HCl/KOH, the generated power can be promoted to an extraordinarily high level of ≈4.5 nW, over one magnitude higher than all existing ionic gradient power generators. The synergistic effects of ultrathin thickness, large surface charge, and excellent chemical inertness of 2D single-layer hBN render it a promising membrane candidate for harvesting ionic gradient powers, even under extreme pH conditions.

Spin-Polarized Photocatalytic CO2 Reduction of Mn-Doped Perovskite Nanoplates.

"Spin" has been recently reported as an important degree of electronic freedom to improve the performance of electrocatalysts and photocatalysts. This work demonstrates the manipulations of spin-polarized electrons in CsPbBr3 halide perovskite nanoplates (NPLs) to boost the photocatalytic CO2 reduction reaction (CO2RR) efficiencies by doping manganese cations (Mn2+) and applying an external magnetic field. Mn-doped CsPbBr3 (Mn-CsPbBr3) NPLs exhibit an outstanding photocatalytic CO2RR compared to pristine CsPbBr3 NPLs due to creating spin-polarized electrons after Mn doping. Notably, the photocatalytic CO2RR of Mn-CsPbBr3 NPLs is significantly enhanced by applying an external magnetic field. Mn-CsPbBr3 NPLs exhibit 5.7 times improved performance of photocatalytic CO2RR under a magnetic field of 300 mT with a permanent magnet compared to pristine CsPbBr3 NPLs. The corresponding mechanism is systematically investigated by magnetic circular dichroism spectroscopy, ultrafast transient absorption spectroscopy, and density functional theory simulation. The origin of enhanced photocatalytic CO2RR efficiencies of Mn-CsPbBr3 NPLs is due to the increased number of spin-polarized photoexcited carriers by synergistic doping of the magnetic elements and applying a magnetic field, resulting in prolonged carrier lifetime and suppressed charge recombination. Our result shows that manipulating spin-polarized electrons in photocatalytic semiconductors provides an effective strategy to boost photocatalytic CO2RR efficiencies.

Electrocatalytic Reduction of NO3- to Ultrapure Ammonia on {200} Facet Dominant Cu Nanodendrites with High Conversion Faradaic Efficiency.

Nitrate (NO3-) reduction reaction (NtRR) is considered as a green alternative method for the conventional method of NH3 synthesis (Haber-Bosch process), which is known as a high energy consuming and large CO2 emitting process. Herein, the copper nanodendrites (Cu NDs) grown along with the {200} facet as an efficient NtRR catalyst have been successfully fabricated and investigated. It exhibited high Faradaic efficiency of 97% at low potential (-0.3 V vs RHE). Furthermore, the 15NO3- isotope labeling method was utilized to confirm the formation of NH3. Both experimental and theoretical studies showed that NtRR on the Cu metal nanostructure is a facet dependent process. Dissociation of NO bonding is supposed to be the rate-determining step as NtRR is a spontaneously reductive and protonation process for all the different facets of Cu. Density functional theory (DFT) calculations revealed that Cu{200} and Cu{220} offer lower activation energy for dissociation of NO compared to that of Cu{111}.

Exploring the Active Site of the Antibacterial Target MraY by Modified Tunicamycins.

The alarming growth of antibiotic resistance that is currently ongoing is a serious threat to human health. One of the most promising novel antibiotic targets is MraY (phospho-MurNAc-pentapeptide-transferase), an essential enzyme in bacterial cell wall synthesis. Through recent advances in biochemical research, there is now structural information available for MraY, and for its human homologue GPT (GlcNAc-1-P-transferase), that opens up exciting possibilities for structure-based drug design. The antibiotic compound tunicamycin is a natural product inhibitor of MraY that is also toxic to eukaryotes through its binding to GPT. In this work, we have used tunicamycin and modified versions of tunicamycin as tool compounds to explore the active site of MraY and to gain further insight into what determines inhibitor potency. We have investigated tunicamycin variants where the following motifs have been modified: the length and branching of the tunicamycin fatty acyl chain, the saturation of the fatty acyl chain, the 6″-hydroxyl group of the GlcNAc ring, and the ring structure of the uracil motif. The compounds are analyzed in terms of how potently they bind to MraY, inhibit the activity of the enzyme, and affect the protein thermal stability. Finally, we rationalize these results in the context of the protein structures of MraY and GPT.

Lithiation-induced fracture of silicon nanowires observed by in-situ scanning electron microscopy.

Silicon is expected to be a useful anode material in lithium ion batteries for future energy storage applications, because of its high theoretical charge storage density of Li+ ions. However, volume expansion due to lithiation fractures the Si anode material, leading to poor cycle stability of battery operation. The approaches to overcome the problem include using Si nanowires to relieve the stress induced by volume expansion and coating a protective layer on the Si anode to prevent delamination. In this study, we use in-situ scanning electron microscopy to monitor the morphological changes of 90 nm thick pristine Si nanowires and the Si nanowires coated with amorphous TiO2, respectively, during electrochemical lithiation. The results of in-situ observation show that both kinds of Si nanowires exhibit a larger thickness after 10 h lithiation and suffer fracture after 25 h. It is also found that the TiO2 layer is not strong enough to prevent Si nanowires from fracture. Since the TiO2 layer can not be elastically deformed, this surface shell fractures earlier in the lithiation process than pristine Si nanowires. Transformation of the crystalline Si nanowires to an amorphous phase and lithium composition detected in the nanowires support that the observed fracture indeed results from lithiation.

Gait Characteristics of Staircase Walking of Old and Young Adults under Dual Task Situation / 中国康复理论与实践

Objective:To compare the biomechanical characteristics and cognitive task performance of the young and the old adults as ascending and descending staircase. Methods:From March to April, 2018, 25 volunteers, including twelve old persons aged (71.54±3.25) and 13 young persons aged (22.24±1.56), were tested with continuous minus seven as sitting (pre-test), walking up and down stairs, walking up and down stairs with continuous minus seven and continuous minus seven as sitting again (post-test). Results:The performance of continuous minus seven was better as walking up stairs and post-test than pre-test in the old persons, and it was better as both up and down stairs, as well as post-test than pre-test in the young persons. As walking up stairs, the main effects of both age (F > 5.037,P < 0.05) and task (F > 6.122,P < 0.05) were significant in walking time, step length, frequency and speed; while walking down stairs, the main effects of both age (F > 17.252,P < 0.01) and task (F > 6.274,P < 0.05) were significant in walking time, step frequency and speed. Conclusion:People would alter the focus on cognitive tasks according to the difficulty of the action. The old adults would be more conservative in the action as upstair during the dual task, and would pay less attention to cognitive task additionally as downstair.

Effects of hypoxia and vibration training on bone metabolism and insulin sensitivity in type 2 diabetic osteoporosis rats / 中国组织工程研究

BACKGROUND: Hypoxia program to alleviate type 2 diabetes insulin resistance has been recommended, but this program is still questioned because of the risk of osteoporosis caused by hypoxia in patients with diabetes. OBJECTIVE: To investigate the effect of vibration training on bone mineral density, bone structural mechanics, bone metabolism and insulin sensitivity in type 2 diabetic osteoporosis rats under hypoxia environment. METHODS: Ninety clean Sprague-Dawley rats were randomly divided into two groups, and subjected to high-fat diet (n=60), or normal diet (n=30), for 8 weeks. High-fat rats were given the injection of streptozotocin to establish the rat model of type 2 diabetic osteoporosis. The control rats were subdivided into normoxia control and hypoxia control groups; the model rats were subdivided into hypoxia modeling group, hypoxia modeling vibration group, normoxia modeling group, normoxia modeling vibration group. Hypoxia and vibration program was performed by hypoxia tank and vibration platform (PowerPlate?) for 12 weeks. Glucose metabolism, insulin sensitivity, bone metabolism and bone mineral density and modeling were detected at 4 weeks after modeling and 12 weeks after vibration training. RESULTS AND CONCLUSION: At 12 weeks after intervention, the fast insulin level, fast blood glucose, and homeostasis model assessment of insulin resistance in the hypoxia modeling vibration group were significantly superior to those in the hypoxia modeling, normoxia modeling, and normoxia modeling vibration groups (P < 0.05). The bone mineral density, maximum stress, maximum load, breaking load and elastic modulus in the normoxia modeling vibration and hypoxia modeling vibration groups were significantly lower than those in the normoxia control and hypoxia control groups (P < 0.05). After vibration training, all indexes were significantly increased (P < 0.05). These results suggest that hypoxic environment can promote the insulin sensitivity, improve glucose and lipid metabolism in type 2 diabetic rats, but can lead to a decrease in bone mineral density and increase bone resorption. Vibration training not only can significantly enhance the insulin sensitivity, but also can avoid the decreased bone mineral density, bone metabolism disorder, and biomechanical properties induced by hypoxia.

Advances in BET bromodomain protein inhibitors / 中国药科大学学报

@#Recognizing acetyl-lysine of histone is a key process of epigenetic regulation that is mediated by a protein module called bromodomain(BRD). The bromodomain inhibitors of the bromodomains and extra-terminal(BET)family have shown great potential in anti-inflammatory and antiproliferative effects. Through a review of diseases and structures about BET bromodomain, different kinds of inhibitors were analyzed and their structure-activity relationships were summarized. Herenin, the recent advances reported are reviewed for discovering more excellent small molecule inhibitors.