This letter reports a GaN vertical fin power field-effect-transistor structure with submicron fin-shaped channels on bulk GaN substrates. In this vertical transistor design only n-GaN layers are ...needed, while no material regrowth or p-GaN layer is required. A combined dry/wet etch was used to get smooth fin vertical sidewalls. The fabricated transistor demonstrated a threshold voltage of 1 V and specific on resistance of 0.36 mΩcm 2 . By proper electric field engineering, 800 V blocking voltage was achieved at a gate bias of 0 V.
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•Lemon seed residue was utilized as a raw material for CNCs extraction.•CNCs were isolated using acid hydrolysis, APS oxidation and TEMPO oxidation.•Extraction method can influence ...the structure and properties of CNCs.•CNCs by acid hydrolysis and APS oxidation can stabilize Pickering emulsions better.
In this study, the lemon (Citrus limon) seeds as typical agricultural processing wastes were utilized to extract cellulose nanocrystals (CNCs) by sulfuric acid hydrolysis (S-LSCNC), ammonium persulfate oxidation (A-LSCNC) and TEMPO oxidation (T-LSCNC). The properties of CNCs were comparatively investigated by Fourier transform infrared spectroscopy (FTIR), X-ray photoelectron spectroscopy (XPS), X-ray diffraction (XRD), thermogravimetric analysis (TG), and atomic force microscope (AFM), and the application in Pickering emulsions was also preliminarily studied. The results showed that all CNCs maintained cellulose Iβ structure and had a good dispersion regardless of extraction methods. Differently, T-LSCNC had a higher yield, larger size and lower CrI than A-LSCNC and S-LSCNC. Comparatively, A-LSCNC showed the highest CrI and S-LSCNC showed the lowest size. For the application of Pickering emulsions, S-LSCNC and A-LSCNC showed a better ability as Pickering stabilizers than T-LSCNC. This study is beneficial for developing the potential utilization of CNCs from lemon by-products.
The cellulose nanocrystals (LSCNC) and nanofibrils (LSCNF) from lemon seeds were isolated, characterized and used to co-stabilize Pickering emulsions under different LSCNC/LSCNF ratio. The ratio of ...LSCNC and LSCNF obviously influenced the appearance and microstructure of emulsions. At a fixed total nanocellulose concentration (1 wt%), the LSCNC/LSCNF stabilized emulsions showed a gradual worsening performance with the increase of LSCNF proportion. However, at a fixed LSCNC concentration (0.5 wt%), as LSCNF addition increased from 0 wt% to 1 wt%, the droplet sizes of emulsions gradually decreased, and the viscoelasticity and stability of emulsions increased correspondingly. The obtained emulsions displayed a good pH and ionic strength stability. Notably, introducing LSCNF made LSCNC stabilize emulsions even at low ionic strength (<20 mM). LSCNC can tightly cover the surface of oil droplets, while LSCNF can not only cover the surface of adjacent droplets as a stabilizer, but also form intensive bridging network structure and acted as a thicker to form depletion stabilization, thus achieving the regulation of the emulsion properties. This co-stabilization effect of LSCNC/LSCNF stabilized emulsion depends on the concentration and ratio of LSCNC/LSCNF. These results enrich the approach and theory of nanocellulose in Pickering emulsions application, and also promote the high-value utilization of agricultural by-products.
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•Lemon seed cellulose nanocrystals (LSCNC) and nanofibrils (LSCNF) were isolated.•Pickering emulsions co-stabilized by LSCNC/LSCNF were investigated.•Properties of emulsions can be adjusted by the co-stabilization effect.•LSCNF endowed the emulsions with improved stability at low pH or ionic strength.•LSCNF induced bridging network structure and depletion stabilization of emulsion.
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•Surface coordination chemistry of N-heterocyclic carbenes on metal nanomaterials are reviewed.•Synthesis, characterization and application of N-heterocyclic carbene coordinated metal ...nanoparticles are summarized.•Atomically precise metal nanoclusters as a model system for understanding carbene-metal interface is highlighted.•Future research directions of the area are proposed.
N-heterocyclic carbenes (NHCs) represent one of the most important organic ligands in coordination chemistry, and have been recently attracting increasing attention in nanoscience. This review aims to provide an overview on recent research advances on the use of NHCs as stabilizing agents and functionality modifiers for metal nanoparticles (NPs) and nanoclusters (NCs). The review begins with the general introduction of NHCs and the initial discovery of NHC ligation on metal NPs. With the development of several effective strategies to decorate metal NPs with NHCs, the research enthusiasm for NHC-stabilized metal NPs has been expanded. NHCs on heterogeneous metal nanocatalysts help to modify the electronic and steric properties of the catalysts and thus improve their catalytic performances including reactivity, selectivity, stability and recyclability. For example, NHC-ligated gold NPs has been demonstrated to possess remarkably enhanced stability that cannot be achieved by other ligand systems. Moreover, significant progress has been made in the synthesis of atomically precise NHC-stabilized metal NCs and their crystallographic structure analysis, providing the unprecedented opportunity in understanding the carbene-metal interface at the atomic level. At the end of the review, personal perspectives on the further development of this embryonic while promising field is discussed.
Large temperature changes may cause degradation in physical and mechanical properties of rocks. This degradation can be influenced by heating-cooling procedure. In this study, it is proposed to ...investigate the influence of cooling method after heating to high temperature on the degradation of physical and mechanical properties of granite. For this purpose, two different cooling procedures are considered, the rapid cold water cooling and the slow step-by-step cooling. Two groups of granite samples are first heated to a desired temperature ranging from 25 °C to 900 °C, and then cooled respectively by using these two methods. The porosity and ultrasonic velocity of the thermally treated samples are measured. Uniaxial and triaxial compression tests are also performed to evaluate the elastic properties and compression strength. It is found that for both groups of samples, the thermal treatment induces the porosity increase, the wave velocity decrease and the modification of elastic modulus and compression strength. But the modification of mechanical properties is clearly influenced by the thermal treatment procedure.
Herba Cistanche, known as Rou Cong Rong in Chinese, is a very valuable Chinese herbal medicine that has been recorded in the Chinese Pharmacopoeia. Rou Cong Rong has been extensively used in clinical ...practice in traditional herbal formulations and has also been widely used as a health food supplement for a long time in Asian countries such as China and Japan. There are many bioactive compounds in Rou Cong Rong, the most important of which are phenylethanoid glycosides. This article summarizes the up-to-date information regarding the phytochemistry, pharmacology, processing, toxicity and safety of Rou Cong Rong to reveal its pharmacodynamic basis and potential therapeutic effects, which could be of great value for its use in future research.
Mobile robotic machining is a feasible mode of manufacturing large-scaled and complex-shaped workpieces, where point stabilization is executed by the mobile robot for arriving at the machining ...station. Localization accuracy, avoidance of environment obstacle, and reliability of the motion path are the key points that should be concerned during the robotic machining scene. However, the fixed-point control usually leads to discontinuous motion for nonholonomic mobile robots; thereby, oscillation and jerks easily occurring in the unsmooth movement. To cope with this phenomenon, a novel Bézier smooth subline constraint nonlinear model predictive control is presented, where point control problem is addressed in high quality by converting it into a dynamic tracking control problem. Specifically, the smoothness of the moving trajectory is constrained by Bézier smooth subline and optimized through the minimum variation curves principle. Then, an error-based dynamic model predictive tracking controller is designed to guarantee the motion accuracy. As a result, the nonholonomic mobile robot can reach the desired position reliably by following the elaborately designed trajectory. Compared with traditional point stabilization approaches, in this article, our method is featured by subline constraint; thereby, exhibiting smooth and excellent moving states with the collision-free property. Furthermore, high positioning accuracy can be guaranteed through precise dynamic control. The feasibility and superiority of the proposed method are demonstrated through contrast simulations and real experiments.
•Alcalase and collagenase degraded collagen type I completely, other enzymes only to some extent.•Pretreatment by boiling for 5min improved the hydrolysis with most enzymes.•A high pressure treatment ...at 600MPa improved hydrolysis and ACE-inhibition with Alcalase and collagenase.•Alcalase hydrolysates showed the highest DH and ACE-inhibition.•New potential ACE-inhibitory peptides released by Alcalase were identified.
Bovine collagen was pre-treated (boiled or high pressure (HP)-treated) and then hydrolysed by 6 proteases. The degree of hydrolysis (DH) and the angiotensin-converting enzyme (ACE)-inhibitory activity of hydrolysates were measured. All enzymes used were able to partly degrade collagen and release ACE-inhibitory peptides. The highest ACE-inhibitory activity was obtained with Alcalase. Pretreatment significantly influenced the DH and ACE-inhibition. For most enzymes, boiling for 5min resulted in a significantly higher DH and ACE-inhibitory activity. With Alcalase and collagenase, hydrolysis and release of ACE-inhibitory peptides occurred without any pretreatment, but HP-treatment significantly improved the DH and ACE-inhibitory activity. HP did not markedly affect the hydrolysis with the other enzymes. The major peptides obtained with Alcalase were identified; all were released from the triple helix structure of collagen. Many of these peptides had C-terminal sequences similar to known ACE-inhibitory peptides. The present results suggest that collagen-rich food materials are good substrates for the release of potent ACE-inhibitory peptides, when proper pre-treatment and enzymatic treatment is applied.
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