Showing papers by "Yu Huang published in 2014"
TL;DR: A three-dimensional holey graphene framework with a hierarchical porous structure as a high-performance binder-free supercapacitor electrode that can deliver gravimetric and volumetric energy densities approaching those of lead acid batteries is reported.
Abstract: Carbon-based materials are promising supercapacitor electrodes, but suffer from limited energy densities. Here, the authors report a holey graphene framework with hierarchical porous structures and fully accessible surface areas, leading to high energy densities comparable to lead-acid batteries.
1,156 citations
TL;DR: An important advance in the development of layered semiconductor heterostructures, an essential step towards achieving functional electronics and optoelectronics.
Abstract: Two-dimensional layered semiconductors such as MoS₂ and WSe₂ have attracted considerable interest in recent times. Exploring the full potential of these layered materials requires precise spatial modulation of their chemical composition and electronic properties to create well-defined heterostructures. Here, we report the growth of compositionally modulated MoS₂-MoSe₂ and WS₂-WSe₂ lateral heterostructures by in situ modulation of the vapour-phase reactants during growth of these two-dimensional crystals. Raman and photoluminescence mapping studies demonstrate that the resulting heterostructure nanosheets exhibit clear structural and optical modulation. Transmission electron microscopy and elemental mapping studies reveal a single crystalline structure with opposite modulation of sulphur and selenium distributions across the heterostructure interface. Electrical transport studies demonstrate that the WSe₂-WS₂ heterojunctions form lateral p-n diodes and photodiodes, and can be used to create complementary inverters with high voltage gain. Our study is an important advance in the development of layered semiconductor heterostructures, an essential step towards achieving functional electronics and optoelectronics.
1,043 citations
TL;DR: In this article, an atomically thin and sharp heterojunction p-n diode can be created by vertically stacking p-type monolayer tungsten diselenide (WSe2) and n-type few-layer molybdenum disulfide (MoS2).
Abstract: The p-n diodes represent the most fundamental device building blocks for diverse optoelectronic functions, but are difficult to achieve in atomically thin transition metal dichalcogenides (TMDs) due to the challenges in selectively doping them into p- or n-type semiconductors. Here, we demonstrate that an atomically thin and sharp heterojunction p-n diode can be created by vertically stacking p-type monolayer tungsten diselenide (WSe2) and n-type few-layer molybdenum disulfide (MoS2). Electrical measurements of the vertically staked WSe2/MoS2 heterojunctions reveal excellent current rectification behavior with an ideality factor of 1.2. Photocurrent mapping shows rapid photoresponse over the entire overlapping region with a highest external quantum efficiency up to 12%. Electroluminescence studies show prominent band edge excitonic emission and strikingly enhanced hot-electron luminescence. A systematic investigation shows distinct layer-number dependent emission characteristics and reveals important insight about the origin of hot-electron luminescence and the nature of electron-orbital interaction in TMDs. We believe that these atomically thin heterojunction p-n diodes represent an interesting system for probing the fundamental electro-optical properties in TMDs and can open up a new pathway to novel optoelectronic devices such as atomically thin photodetectors, photovoltaics, as well as spin- and valley-polarized light emitting diodes, on-chip lasers.
812 citations
TL;DR: This study demonstrates the potential of two-dimensional layered semiconductors for high-speed flexible electronics by showing that logic inverters or radio frequency amplifiers can be formed by integrating multiple MoS2 transistors on quartz or flexible substrates with voltage gain in the gigahertz regime.
Abstract: Molybdenum disulfide holds great potential for advanced flexible electronic devices. Here, using a transferred gate technique, the authors fabricate molybdenum disulfide-based transistors with optimized device geometry and contact, improving device speed and demonstrating gigahertz circuits with voltage gain.
411 citations
TL;DR: This result shows the interplay between thermal and electrical interactions at the highly reactive nanocontacts and highlights the control of the nanoscale reaction as a simple and effective way of turning individual metallic nanowires into a highly conductive interconnected nanowire network.
Abstract: Solution-processed metallic nanowire thin film is a promising candidate to replace traditional indium tin oxide as the next-generation transparent and flexible electrode. To date however, the performance of these electrodes is limited by the high contact resistance between contacting nanowires; so improving the point contacts between these nanowires remains a major challenge. Existing methods for reducing the contact resistance require either a high processing power, long treatment time, or the addition of chemical reagents, which could lead to increased manufacturing cost and damage the underlying substrate or device. Here, a nanoscale point reaction process is introduced as a fast and low-power-consumption way to improve the electrical contact properties between metallic nanowires. This is achieved via current-assisted localized joule heating accompanied by electromigration. Localized joule heating effectively targets the high-resistance contact points between nanowires, leading to the automatic removal...
348 citations
TL;DR: In this paper, the first chemical vapor deposition growth of single and few-layer MoSe2 nanosheets was reported, which can be directly grown on the 300 nm SiO2/Si substrates.
Abstract: The synthesis of two-dimensional (2D) layered materials with controllable thickness is of considerable interest for diverse applications. Here we report the first chemical vapor deposition growth of single- and few-layer MoSe2 nanosheets. By using Se and MoO3 as the chemical vapor supply, we demonstrate that highly crystalline MoSe2 can be directly grown on the 300 nm SiO2/Si substrates to form optically distinguishable single- and multi-layer nanosheets, typically in triangular shaped domains with edge lengths around 30 μm, which can merge into continuous thin films upon further growth. Micro-Raman spectroscopy and imaging was used to probe the thickness-dependent vibrational properties. Photoluminescence spectroscopy demonstrates that MoSe2 monolayers exhibit strong near band edge emission at 1.55 eV, while bilayers or multi-layers exhibit much weaker emission, indicating of the transition to a direct band gap semiconductor as the thickness is reduced to a monolayer.
338 citations
TL;DR: In this article, a facile one-pot strategy was proposed to synthesize highly dispersive PtNi octahedra directly on various carbon materials without using any bulky capping agents.
Abstract: Bimetallic PtNi nanocrystals represent an emerging class of newly discovered electrocatalysts which are expected to exhibit exciting oxygen reduction reaction (ORR) activity. Colloidal syntheses have been proven to be suitable for controlling PtNi nanocrystals with well-defined morphologies and tunable compositions with the use of capping agents or ligands. However, these colloidal PtNi nanocrystals have inherent limitations associated with the ligand-covered surfaces, which not only limit the free access of surface active sites but also hinder electron transport between the catalyst and the support, leading to deteriorated ORR performance. Herein, we report a facile one-pot strategy to synthesize highly dispersive PtNi octahedra directly on various carbon materials without using any bulky capping agents, which enhances the surface exposure of the PtNi octahedra and their catalytic activity over ORR while largely reduces the preparation costs. The obtained octahedral PtNi/C catalysts have high ORR activities of 2.53 mA cm−2 and 1.62 A mgPt−1 at 0.9 V versus RHE, which are far better than those of commercial Pt/C catalysts (0.131 mA cm−2 and 0.092 A mgPt−1, all the ORR measurements were performed at room temperature in O2-purged 0.1 M HClO4 solutions at a sweep rate of 10 mV s−1). This strategy has been extended to fabricate trimetallic PtNiCo octahedra on carbon black with further enhanced activities up to 3.88 mA cm−2 and 2.33 A mgPt−1 at 0.9 V versus RHE. The octahedral PtNiCo/C catalyst is also more stable than the commercial Pt/C under the ORR conditions and shows small activity change after 6000 potential sweeps. The work demonstrates that the carbon-supported Pt-based materials reported herein are promising material candidates with enhanced performances for practical electrocatalytic applications.
165 citations
TL;DR: The literature on modern biological theories of ageing and role of dietary antioxidants in ageing as well as underlying mechanisms by which antioxidants can prolong the lifespan with focus on fruit flies as an model are brief.
Abstract: Interest in relationship between diet and ageing is growing Research has shown that dietary calorie restriction and some antioxidants extend lifespan in various ageing models On the one hand, oxygen is essential to aerobic organisms because it is a final electron acceptor in mitochondria On the other hand, oxygen is harmful because it can continuously generate reactive oxygen species (ROS), which are believed to be the factors causing ageing of an organism To remove these ROS in cells, aerobic organisms possess an antioxidant defense system which consists of a series of enzymes, namely, superoxide dismutase (SOD), catalase (CAT), glutathione peroxidase (GPx), and glutathione reductase (GR) In addition, dietary antioxidants including ascorbic acid, vitamin A, vitamin C, α-tocopherol, and plant flavonoids are also able to scavenge ROS in cells and therefore theoretically can extend the lifespan of organisms In this connection, various antioxidants including tea catechins, theaflavins, apple polyphenols, black rice anthocyanins, and blueberry polyphenols have been shown to be capable of extending the lifespan of fruit flies The purpose of this review is to brief the literature on modern biological theories of ageing and role of dietary antioxidants in ageing as well as underlying mechanisms by which antioxidants can prolong the lifespan with focus on fruit flies as an model
157 citations
TL;DR: Metformin restores endothelial function through inhibiting ER stress and oxidative stress and increasing NO bioavailability on activation of AMPK/PPAR&dgr; pathway in obese diabetic mice.
Abstract: Objective—5′ Adenosine monophosphate–activated protein kinase (AMPK) interacts with peroxisome proliferator–activated receptor δ (PPARδ) to induce gene expression synergistically, whereas the activation of AMPK inhibits endoplasmic reticulum (ER) stress. Whether the vascular benefits of antidiabetic drug metformin (AMPK activator) in diabetes mellitus and obesity is mediated by PPARδ remains unknown. We aim to investigate whether PPARδ is crucial for metformin in ameliorating ER stress and endothelial dysfunction induced by high-fat diet. Approach and Results—Acetylcholine-induced endothelium-dependent relaxation in aortae was measured on wire myograph. ER stress markers were determined by Western blotting. Superoxide production in mouse aortae and NO generation in mouse aortic endothelial cells were assessed by fluorescence imaging. Endothelium-dependent relaxation was impaired and ER stress markers and superoxide level were elevated in aortae from high-fat diet–induced obese mice compared with lean mice...
156 citations
TL;DR: A new design of highly flexible vertical TFTs (VTFTs) with superior electrical performance and mechanical robustness is reported, using the graphene as a work-function tunable contact for amorphous indium gallium zinc oxide (IGZO) thin film.
Abstract: Flexible thin-film transistors (TFTs) are of central importance for diverse electronic and particularly macroelectronic applications. The current TFTs using organic or inorganic thin film semiconductors are usually limited by either poor electrical performance or insufficient mechanical flexibility. Here, we report a new design of highly flexible vertical TFTs (VTFTs) with superior electrical performance and mechanical robustness. By using the graphene as a work-function tunable contact for amorphous indium gallium zinc oxide (IGZO) thin film, the vertical current flow across the graphene–IGZO junction can be effectively modulated by an external gate potential to enable VTFTs with a highest on–off ratio exceeding 105. The unique vertical transistor architecture can readily enable ultrashort channel devices with very high delivering current and exceptional mechanical flexibility. With large area graphene and IGZO thin film available, our strategy is intrinsically scalable for large scale integration of VTF...
138 citations
TL;DR: In this article, the first demonstration of an atomically thin and atomically sharp heterojunction p-n diode by vertically stacking p-type monolayer tungsten diselenide (WSe2) and n-type few-layer molybdenum disulfide (MoS2) was reported.
Abstract: The p-n diodes represent the most fundamental device building block for diverse optoelectronic functions, but are difficult to achieve in atomically thin transition metal dichalcogenides (TMDs) due to the inability to selectively dope them into p- or n-type semiconductors. Here we report the first demonstration of an atomically thin and atomically sharp heterojunction p-n diode by vertically stacking p-type monolayer tungsten diselenide (WSe2) and n-type few-layer molybdenum disulfide (MoS2). Electrical measurement demonstrates excellent diode characteristics with well-defined current rectification behaviour and an ideality factor of 1.2. Photocurrent mapping shows fast photoresponse over the entire overlapping region with a highest external quantum efficiency up to 12 %. Electroluminescence studies show prominent band edge excitonic emission and strikingly enhanced hot electron luminescence. A systematic investigation shows distinct layer-number dependent emission characteristics and reveals important insight about the origin of hot-electron luminescence and the nature of electron-orbital interaction in TMDs. We believe that these atomically thin heterojunction p-n diodes represent an interesting system for probing the fundamental electro-optical properties in TMDs, and can open up a new pathway to novel optoelectronic devices such as atomically thin photodetectors, photovoltaics, as well as spin-/valley-polarized light emitting diodes and on-chip lasers.
06 May 2014
TL;DR: The analysis of real SRAM PUFs reveals critical conditions on which to select stable SRAM cells for PUF at low-cost and develops a bit selection procedure that produces very stable bits for the PUF generated ID/key.
Abstract: Physically Unclonable Functions (PUFs) are impacted by environmental variations and aging which can reduce their acceptance in identification and authentication applications. Prior approaches to improve PUF reliability include bit analysis across environmental conditions, better design, and post-processing error correction, but these are of high cost in terms of test time and design overheads, making them unsuitable for high volume production. In this paper, we aim to address this issue for SRAM PUFs with novel bit analysis and bit selection algorithms. Our analysis of real SRAM PUFs reveals (i) critical conditions on which to select stable SRAM cells for PUF at low-cost (ii) unexplored spatial correlation between stable bits, i.e., cells that are the most stable tend to be surrounded by stable cells determined during enrollment. We develop a bit selection procedure around these observations that produces very stable bits for the PUF generated ID/key. Experimental data from real SRAM PUFs show that our approaches can effectively reduce number of errors in PUF IDs/keys with fewer enrollment steps.
TL;DR: In this paper, an improved asymmetric least squares (IAsLS) method has been proposed for the baseline correction of Raman spectra, which is initiated by the raw spectrum baseline, and this baseline can be estimated using a polynomial fitting method.
Abstract: Baseline shifts exist in many types of Raman spectrometers. Acquired spectra normally contain the desired signals as well as undesirable elements such as background noise. In this paper, an improved asymmetric least squares (IAsLS) method has been proposed for the baseline correction of Raman spectra. The baseline correction algorithm is initiated by the raw spectrum baseline, and this baseline can be estimated using a polynomial fitting method. For the simulated Raman spectra, the performance of the proposed algorithm was evaluated and compared with the asymmetric least squares (AsLS) method and Jiang's method. The results showed that it is improved by sixteen fold and nine fold respectively. This proposed IAsLS method was successfully applied to practical Raman spectral data and the results in the paper indicate that the baseline of Raman spectra can be automatically subtracted.
TL;DR: The present review discusses its roles in diabetes and associated cardiovascular complications, with emphasis on the different outcomes mediated by the two modes of IL‐6 signalling and the value of developing therapeutic strategies to specifically target the deleterious trans‐signalling ofIL‐6.
Abstract: IL-6 is a pleiotropic cytokine that participates in normal functions of the immune system, haematopoiesis, metabolism, as well as in the pathogenesis of metabolic and cardiovascular diseases. Both pro- and anti-inflammatory roles of IL-6 have been described, which are distinguished by different cascades of signalling transduction, namely classic and trans-signalling. The present review summarizes the basic principles of IL-6 signalling and discusses its roles in diabetes and associated cardiovascular complications, with emphasis on the different outcomes mediated by the two modes of IL-6 signalling and the value of developing therapeutic strategies to specifically target the deleterious trans-signalling of IL-6.
TL;DR: The design of ultrafine wavy nanowires (WNWs) with a high density of accessible structural defects/grain boundaries as highly active catalytic hot spots are reported and the concept of defect engineering in WNWs for improved catalytic performance is general and can be readily extended to other similar systems, including palladium and iridium W NWs.
Abstract: Structural defects/grain boundaries in metallic materials can exhibit unusual chemical reactivity and play important roles in catalysis. Bulk polycrystalline materials possess many structural defects, which is, however, usually inaccessible to solution reactants and hardly useful for practical catalytic reactions. Typical metallic nanocrystals usually exhibit well-defined crystalline structure with few defects/grain boundaries. Here, we report the design of ultrafine wavy nanowires (WNWs) with a high density of accessible structural defects/grain boundaries as highly active catalytic hot spots. We show that rhodium WNWs can be readily synthesized with controllable number of structural defects and demonstrate the number of structural defects can fundamentally determine their catalytic activity in selective oxidation of benzyl alcohol by O2, with the catalytic activity increasing with the number of structural defects. X-ray photoelectron spectroscopy (XPS) and cyclic voltammograms (CVs) studies demonstrate ...
TL;DR: The first heteromeric TRP channels composed of subunits from 3 different TRP subfamilies are identified, mediates the flow‐induced Ca2+ increase in native vascular endothelial cells and contributes to the ion permeation pore of the channels.
Abstract: Transient receptor potential (TRP) channels, a superfamily of ion channels, can be divided into 7 subfamilies, including TRPV, TRPC, TRPP, and 4 others. Functional TRP channels are tetrameric complexes consisting of 4 pore-forming subunits. The purpose of this study was to explore the heteromerization of TRP subunits crossing different TRP subfamilies. Two-step coimmunoprecipitation (co-IP) and fluorescence resonance energy transfer (FRET) were used to determine the interaction of the different TRP subunits. Patch-clamp and cytosolic Ca2+ measurements were used to determine the functional role of the ion channels in flow conditions. The analysis demonstrated the formation of a heteromeric TRPV4-C1-P2 complex in primary cultured rat mesenteric artery endothelial cells (MAECs) and HEK293 cells that were cotransfected with TRPV4, TRPC1, and TRPP2. In functional experiments, pore-dead mutants for each of these 3 TRP isoforms nearly abolished the flow-induced cation currents and Ca2+ increase, suggesting that all 3 TRPs contribute to the ion permeation pore of the channels. We identified the first heteromeric TRP channels composed of subunits from 3 different TRP subfamilies. Functionally, this heteromeric TRPV4-C1-P2 channel mediates the flow-induced Ca2+ increase in native vascular endothelial cells.—Du, J., Ma, X., Shen, B., Huang, Y., Birnbaumer, L., Yao, X. TRPV4, TRPC1, and TRPP2 assemble to form a flow-sensitive heteromeric channel.
TL;DR: The design of a graphene-haemin-glucose oxidase conjugate as a tandem catalyst, in which graphene functions as a unique support to integrate molecular catalyst haemin and enzymatic catalyst glucose oxidase for biomimetic generation of antithrombotic species, is reported.
Abstract: Enzymatic mimics, capable of catalysing cascading reactions under physiological conditions, can be formed from integrating multiple components. Here, the authors report a graphene–haemin–glucose oxidase system capable of biomimetic generation of antithrombotic species from abundant glucose and L-arginine.
TL;DR: This study systematically evaluated the cellular uptake behaviour and cytotoxicity of Au nanorods with various surface coatings, including organic cetyltrimethylammonium bromide, poly(sodium 4-styrenesulfonate) (PSS), and poly(ethylene glycol) (PEG), and inorganic mesoporous silica (mSiO2), dense silica, and titanium dioxide (TiO2).
Abstract: With the development of Au nanorods for a number of biomedical applications, understanding their cellular responses has become increasingly important. In this study, we systematically evaluated the cellular uptake behaviour and cytotoxicity of Au nanorods with various surface coatings, including organic cetyltrimethylammonium bromide (CTAB), poly(sodium 4-styrenesulfonate) (PSS), and poly(ethylene glycol) (PEG), and inorganic mesoporous silica (mSiO2), dense silica (dSiO2), and titanium dioxide (TiO2). The cellular behaviour of Au nanorods was found to be highly dependent on both the surface coating and the cell type. CTAB-, PSS-, and mSiO2-coated Au nanorods exhibit notable cytotoxicity, while PEG-, dSiO2-, and TiO2-coated Au nanorods do not induce cell injury. Optical imaging studies indicated that the cell type plays a preferential role in Au nanorod cellular uptake. Higher cellular uptake of Au nanorods was seen in U-87 MG, PC-3, MDA-MB-231, and RAW 264.7 cells, as opposed to HepG2 and HT-29 cells. In addition, Au nanorod cellular uptake is also highly affected by serum protein binding to the surface coating. mSiO2-, dSiO2-, and TiO2-coated Au nanorods show significantly higher cellular uptake than PSS- and PEG-coated ones, which results in a better photothermal ablation effect for Au nanorods with the inorganic surface coatings. Our study provides valuable insights into the effects of the surface modification on the biocompatibility, cellular uptake, as well as biomedical functions of Au nanorods.
TL;DR: In this article, the authors proposed a numerically efficient NURBS interpolation scheme which consists of two stages namely preprocessing and interpolating, where the parameter interval is split into several blocks at breakpoints and an iterative numerical quadrature method is applied for each block.
Abstract: Parametric interpolation for Non-Uniform Rational B-Spline (NURBS) curve has become more important than ever before in the control of CNC machine tools. An effective NURBS interpolator not only can obtain accurate contour trajectories, but also have smooth dynamics performance. This paper proposes a numerically efficient NURBS interpolation scheme which consists of two stages namely preprocessing and interpolating. In the stage of pre-processing, the parameter interval is split into several blocks at breakpoints and an iterative numerical quadrature method is applied for each block. By means of the iterative quadrature method, the initial parameter intervals of each block are divided into several subintervals according to the arc length approximation error. Meanwhile, the curvature of each knot and the cubic polynomial coefficients of each subinterval are obtained. Then the critical points with large curvature of each block are found from the candidate points and the tolerated speed of each critical point is calculated according to the constraints of chord error and centripetal acceleration. Hence, the feedrate scheduling based on the S-shaped acceleration profile for each block can be preplanned via the approximate arc length of each subinterval, the tolerated speed of each critical point and kinematics characteristics such as acceleration/deceleration and jerk limits of the machine tools. In the stage of interpolating, the parameter of the next interpolation point can be calculated directly using the cumulative arc length and the cubic polynomial coefficients of each subinterval. Finally, a series of numerical simulations and real machining experiments are conducted, and the simulation and experimental results have showed the good performance of the proposed NURBS interpolator both in efficiency and accuracy.
TL;DR: It is elucidate for the first time that UCP2 serves as an important signal molecule in endothelial protection conferred by GLP-1-related agents and could be a useful target in treating hypertension-related vascular events.
Abstract: Aims: Although uncoupling protein 2 (UCP2) negatively regulates intracellular reactive oxygen species (ROS) production and protects vascular function, its participation in vascular benefits of drugs used to treat cardiometabolic diseases is largely unknown. This study investigated whether UCP2 and associated oxidative stress reduction contribute to the improvement of endothelial function by a dipeptidyl peptidase-4 inhibitor, sitagliptin, in hypertension. Results: Pharmacological inhibition of cyclooxygenase-2 (COX-2) but not COX-1 prevented endothelial dysfunction, and ROS scavengers reduced COX-2 mRNA and protein expression in spontaneously hypertensive rats (SHR) renal arteries. Angiotensin II (Ang II) evoked endothelium-dependent contractions (EDCs) in C57BL/6 and UCP2 knockout (UCP2KO) mouse aortae. Chronic sitagliptin administration attenuated EDCs in SHR arteries and Ang II-infused C57BL/6 mouse aortae and eliminated ROS overproduction in SHR arteries, which were reversed by glucagon-like ...
TL;DR: 2D colloidal nanoplates of layered materials can be synthesized with well-controlled thickness and lateral dimension and can be used for the assembly of highly uniform continuous thin films with a full surface coverage and an excellent room temperature carrier mobility approaching that of chemical vapor deposition grown materials.
Abstract: Low-temperature solution-processed electronic materials on plastic substrates are of considerable interest for flexible electronics. Solution dispersible inorganic nanostructures (e.g., zero-dimensional (0D) quantum dots or one-dimensional (1D) nanowires) have emerged as interesting ink materials for low-temperature solution processing of electronic thin films on flexible substrates, but usually with limited performance due to the large number of grain boundaries (0D) or incomplete surface coverage (1D). Here, we report two-dimensional (2D) colloidal nanoplates of layered materials as a new ink material for solution assembly of high-performance electronic thin films. The 2D colloidal nanoplates exhibit few dangling bonds and represent an ideal geometry for the assembly of highly uniform continuous thin films with greatly reduced grain boundaries dictated by large-area conformal plane-plane contact with atomically flat/clean interfaces. It can therefore promise efficient charge transport across neighboring nanoplates and throughout the entire thin film to enable unprecedented electronic performance. We show that Bi2Se3 and Bi2Te3 nanoplates can be synthesized with well-controlled thickness (6-15 nm) and lateral dimension (0.5-3 μm) and can be used for the assembly of highly uniform continuous thin films with a full surface coverage and an excellent room temperature carrier mobility >100 cm(2)·V(-1)·s(-1), approaching that of chemical vapor deposition grown materials. Our study demonstrates a general strategy to using 2D nanoplates as a unique building block for the construction of high-performance electronic thin films on plastic substrates for future flexible electronics and optoelectronics.
TL;DR: In this article, seasonal and diurnal variations of carbonyl compounds were investigated in roadside (MK), urban (TW), and suburban (UST) environments in Hong Kong.
TL;DR: This study investigated the mechanisms underlying the vascular benefits of ginsenoside Rb3 (Rb3) in hypertension by studying its application in cardiovascular conditions in Oriental countries.
Abstract: Background and Purpose
Panax ginseng is commonly used to treat cardiovascular conditions in Oriental countries. This study investigated the mechanisms underlying the vascular benefits of ginsenoside Rb3 (Rb3) in hypertension.
Experimental Approach
Rings of renal arteries were prepared from spontaneously hypertensive rats (SHRs) and normotensive Wistar-Kyoto (WKY) rats and were cultured ex vivo for 8 h. Contractile responses of the rings were assessed with myograph techniques. Expression of NADPH oxidases was assessed by Western blotting and immunohistochemistry. Reactive oxygen species (ROS) were measured using dihydroethidium fluorescence imaging and production of NO was determined using the fluorescent NO indicator DAF-FM diacetate in human umbilical vein endothelial cells.
Key Results
Ex vivo treatment with Rb3 concentration-dependently augmented endothelium-dependent relaxations, suppressed endothelium-dependent contractions and reduced ROS production and expressions of NOX-2, NOX-4 and p67phox in arterial rings from SHR. Rb3 treatment also normalized angiotensin II (Ang II)-stimulated elevation in ROS and expression of NOX-2 and NOX-4 in arterial rings from WKY rats. Rb3 inhibited Ang II-induced reduction of NO production and phosphorylation of endothelial NOS in cultures of human umbilical vein endothelial cells. Rb3 also inhibited oxidative stress in renal arterial rings from hypertensive patients or in Ang II-treated arterial rings from normotensive subjects.
Conclusion and Implications
Ex vivo Rb3 treatment restored impaired endothelial function in arterial rings from hypertensives by reversing over-expression of NADPH oxidases and over-production of ROS, and improved NO bioavailability. Our findings suggest that medicinal plants containing Rb3 could decrease oxidative stress and protect endothelial function in hypertension.
TL;DR: Mechanistic investigations of high density twin formation induced by specific peptides in platinum (Pt) NC growth are reported, on the basis of which principles that can serve as guidelines for the rational design of molecular surfactants to introduce high yield twinning in noble metal NC syntheses are derived.
Abstract: Controlling the morphology of nanocrystals (NCs) is of paramount importance for both fundamental studies and practical applications. The morphology of NCs is determined by the seed structure and the following facet growth. While means for directing facet formation in NC growth have been extensively studied, rational strategies for the production of NCs bearing structure defects in seeds have been much less explored. Here, we report mechanistic investigations of high density twin formation induced by specific peptides in platinum (Pt) NC growth, on the basis of which we derive principles that can serve as guidelines for the rational design of molecular surfactants to introduce high yield twinning in noble metal NC syntheses. Two synergistic factors are identified in producing twinned Pt NCs with the peptide: (1) the altered reduction kinetics and crystal growth pathway as a result of the complex formation between the histidine residue on the peptide and Pt ions, and (2) the preferential stabilization of {1...
TL;DR: An explicit photochemical model is used--Master Chemical Mechanism (MCM) model--to dissect PAN formation and identify principal precursors, by analyzing measurements made in Beijing in summer 2008 and finding PAN production was sensitive to both NOx and VOCs.
TL;DR: In this article, a total suspended particulate (TSP) sample was collected hourly in Xi'an, an inland megacity of China near the Loess Plateau, during a dust storm event of 2013 (9 March 18:00−12 March 10:00 LT), along with a size-resolved aerosol sampling and an online measurement of PM2.5.
Abstract: . A total suspended particulate (TSP) sample was collected hourly in Xi'an, an inland megacity of China near the Loess Plateau, during a dust storm event of 2013 (9 March 18:00−12 March 10:00 LT), along with a size-resolved aerosol sampling and an online measurement of PM2.5. The TSP and size-resolved samples were determined for elemental carbon (EC), organic carbon (OC), water-soluble organic carbon (WSOC) and nitrogen (WSON), inorganic ions and elements to investigate chemistry evolution of dust particles. Hourly concentrations of Cl−, NO3−, SO42−, Na+ and Ca2+ in the TSP samples reached up to 34, 12, 180, 72 and 28 μg m−3, respectively, when dust peak arrived over Xi'an. Chemical compositions of the TSP samples showed that during the whole observation period NH4+ and NO3− were linearly correlated with each other (r2=0.76) with a molar ratio of 1 : 1, while SO42− and Cl− were well correlated with Na+, Ca2+, Mg2+ and K+ (r2 > 0.85). Size distributions of NH4+ and NO3− presented a same pattern, which dominated in the coarse mode (> 2.1 μm) during the event and predominated in the fine mode (
TL;DR: It was concluded that beneficial modification of the lipoprotein profile by dietary GSE was mediated by enhancing excretion of fecal cholesterol and bile acids via up- regulation of hepatic CYP7A1 and down-regulation of mRNA of intestinal NPC1L1, ACAT2, and MTP.
Abstract: The present study investigated the cholesterol-lowering activity of gingerol- and shogaol-enriched ginger extract (GSE). Thirty hamsters were divided into three groups and fed the control diet or o...
TL;DR: p300-dependent STAT3 acetylation is necessary for Ang II-induced STAT3 phosphorylation and the consequent pro-fibrotic responses in renal tubular epithelial cells in vitro.
Abstract: To explore the signal transducer and activator of transcription 3 (STAT3) signaling pathway, especially STAT3 acetylation, in angiotensin II (Ang II)-induced pro-fibrotic responses in renal tubular epithelial cells. Rat renal tubular epithelial cell line (NRK-52E) was used. STAT3 acetylation and phosphorylation, as well as the expression of fibronectin, collagen IV and transforming growth factor-β1 (TGF-β1) were examined using Western blotting. The level and localization of STAT3 phosphorylation on Tyr705 were detected with fluorescence immunocytochemistry. The cells were transfected with a plasmid vector carrying p300 gene or siRNA targeting p300 to regulate p300 expression. Overexpression of p300 significantly increased STAT3 acetylation on Lys685, STAT3 phosphorylation on Tyr705, and the expression of TGF-β1, collagen IV and fibronectin in the cells. Treatment of the cells with Ang II (1 μmol/L) significantly increased STAT3 phosphorylation on Tyr705 through JAK2 activation, and dose-dependently increased the expression of fibronectin, collagen IV and TGF-β1. Pretreatment with curcumin, an inhibitor of JAK2 and p300, blocked Ang II-induced effects. Knockdown of p300 significantly decreased STAT3 acetylation on Lys685, and abolished Ang II-stimulated STAT3 phosphorylation on Tyr705, whereas pretreatment of the cells with C646, a selective inhibitor of p300, inhibited Ang II-induced STAT3 nuclear translocation and the expression of TGF-β1, collagen IV and fibronectin. Pretreatment of the cells with AG490, a JAK2 inhibitor, markedly inhibited Ang II-induced STAT3 phosphorylation on Tyr705 and fibronectin expression. p300-dependent STAT3 acetylation is necessary for Ang II-induced STAT3 phosphorylation and the consequent pro-fibrotic responses in renal tubular epithelial cells in vitro.
TL;DR: Novel evidence is provided that palmitate up-regulates COX-2 through NF-κB-dependent mechanism and resultant COx-2-associated oxidative stress impairs endothelium-dependent relaxations in mouse aortas.
TL;DR: In this article, the Gaussian process regression (GPR) was proposed for modeling and predicting the surface roughness in end face milling and the prediction accuracy was nearly about 84.3 %.
Abstract: Surface roughness is a technical requirement for machined products and one of the main product quality specifications. In order to avoid the costly trial-and-error process in machining parameters determination, the Gaussian process regression (GPR) was proposed for modeling and predicting the surface roughness in end face milling. Cutting experiments on C45E4 steel were conducted and the results were used for training and verifying the GPR model. Three parameters, spindle speed, feed rate, and depth of cut were considered; the experiment results showed that depth of cut is the main factor affecting the surface roughness and regression results showed that the GPR model has a good precision in predicting the surface roughness in different cutting conditions. The prediction accuracy was nearly about 84.3 %. Based on the GPR prediction model, 3D-maps of surface roughness under various cutting parameters could be obtained. It is very concise and useful to select the appropriate cutting parameters according to the maps. As experimental results did not conform to the empirical knowledge, frequency spectrums of the tool were analyzed according to the 3D-maps, it was found that tool vibration is also a crucial factor affecting the machined surface quality.