Carbon nanotubes have many material properties that make them attractive for applications. In the context of nanoelectronics, interest has focused on single-walled carbon nanotubes (SWNTs) because ...slight changes in tube diameter and wrapping angle, defined by the chirality indices (n, m), will shift their electrical conductivity from one characteristic of a metallic state to one characteristic of a semiconducting state, and will also change the bandgap. However, this structure-function relationship can be fully exploited only with structurally pure SWNTs. Solution-based separation methods yield tubes within a narrow structure range, but the ultimate goal of producing just one type of SWNT by controlling its structure during growth has proved to be a considerable challenge over the last two decades. Such efforts aim to optimize the composition or shape of the catalyst particles that are used in the chemical vapour deposition synthesis process to decompose the carbon feedstock and influence SWNT nucleation and growth. This approach resulted in the highest reported proportion, 55 per cent, of single-chirality SWNTs in an as-grown sample. Here we show that SWNTs of a single chirality, (12, 6), can be produced directly with an abundance higher than 92 per cent when using tungsten-based bimetallic alloy nanocrystals as catalysts. These, unlike other catalysts used so far, have such high melting points that they maintain their crystalline structure during the chemical vapour deposition process. This feature seems crucial because experiment and simulation both suggest that the highly selective growth of (12, 6) SWNTs is the result of a good structural match between the carbon atom arrangement around the nanotube circumference and the arrangement of the catalytically active atoms in one of the planes of the nanocrystal catalyst. We anticipate that using high-melting-point alloy nanocrystals with optimized structures as catalysts paves the way for total chirality control in SWNT growth and will thus promote the development of SWNT applications.
Aim: Previously, we found that diabetes-related liver dysfunction is due to activation of the 5-HT2A receptor (5-HT2AR) and increased synthesis and degradation of 5-HT. Here, we investigated the role ...of 5-HT in the development of atherosclerosis. Methods: The study was conducted using high-fat diet-fed male ApoE−/− mice, THP-1 cell-derived macrophages, and HUVECs. Protein expression and biochemical indexes were determined by Western blotting and quantitative analysis kit, respectively. The following staining methods were used: oil red O staining (showing atherosclerotic plaques and intracellular lipid droplets), immunohistochemistry (showing the expression of 5-HT2AR, 5-HT synthase, and CD68 in the aortic wall), and fluorescent probe staining (showing intracellular ROS). Results: In addition to improving hepatic steatosis, insulin resistance, and dyslipidemia, co-treatment with a 5-HT synthesis inhibitor and a 5-HT2AR antagonist significantly suppressed the formation of atherosclerotic plaques and macrophage infiltration in the aorta of ApoE−/− mice in a synergistic manner. Macrophages and HUVECs exposed to oxLDL or palmitic acid in vitro showed that activated 5-HT2AR regulated TG synthesis and oxLDL uptake by activating PKCε, resulting in formation of lipid droplets and even foam cells; ROS production was due to the increase of both intracellular 5-HT synthesis and mitochondrial MAO-A-catalyzed 5-HT degradation, which leads to the activation of NF-κB and the release of the inflammatory cytokines TNF-α and IL-1β from macrophages and HUVECs as well as MCP-1 release from HUVECs. Conclusion: Similar to hepatic steatosis, the pathogenesis of lipid-induced atherosclerosis is associated with activation of intracellular 5-HT2AR, 5-HT synthesis, and 5-HT degradation.
In the area of synthetic aperture radar (SAR), the ultra-high resolution is always a continuous pursuit for researchers. To realize ultra-high resolution, microwave photonics (MWP) technology is an ...excellent solution since it has advantages of low transmission loss, ultra-wide bandwidth (UWB), etc. However, with the improvement of resolution, new problems arise as the impact of more systematical errors becomes non-negligible. For example, the synchronization error between the transmit channel and the mixing channel, unknown system delay during signal reception, and fluctuation of frequency for UWB signals. These factors will bring degradation of the focusing quality of SAR images together with the motion errors and the trajectory measurement errors, not only cause residual range cell migration (RCM) and azimuth phase error (APE), but also higher-order phase error along the range frequency dimension. In this paper, we discuss the adverse influence of the above factors and give a detailed analysis of the 2-D phase error of the coarse focused image processed by range migration algorithm (RMA). Then, to compensate for the above unknown systematical errors, a 2-D autofocus method is proposed and the effectiveness is validated by experiments on both simulated and real data.
For ultra-high-resolution (UHR) squint spotlight airborne synthetic aperture radar (SAR), the severe range-azimuth coupling caused by squint mode and the spatial and frequency dependence of the ...motion error brought by ultra-wide bandwidth both make it difficult to obtain satisfactory imaging results. Although some autofocus methods for squint airborne SAR have been presented in the published literature, their practical applicability in UHR situations remains limited. In this article, a new 2D wavenumber domain autofocus method combined with the Omega-K algorithm dedicated to UHR squint spotlight airborne SAR is proposed. First, we analyze the dependence of range envelope shift error (RESE) and range defocus on the squint angle and then propose a new spectrum modification strategy, after which the spectrum transforms into a quasi-side-looking one. The accuracy of estimation and compensation can be improved significantly in this way. Then, the 2D phase error can be calculated with the 1D estimated error by the mapping relationship, and after that the 2D compensation is performed in the wavenumber domain. Furthermore, the image-blocking technique and range-dependent motion error compensation method are embedded to accommodate the spatial-variant motion error for UHR cases. Simulations are carried out to verify the effectiveness of the proposed method.
A novel technique to generate a frequency-doubled millimeter-wave (mm-W) vector signal that is immune to fiber chromatic-dispersion-induced power fading and free from interband beating interferences ...(IBBIs) based on a bi-directional use of a polarization modulator (PolM) in a Sagnac loop is proposed and experimentally demonstrated. The fundamental concept of the proposed approach is to use a PolM that is incorporated in a Sagnac loop at which a light wave is modulated by an intermediate-frequency vector signal along one direction and with no modulation along the opposite direction due to the traveling-wave nature of the PolM. The combination of the modulated and un-modulated signals at a photodetector will generate an mm-W signal that is immune to the fiber chromatic-dispersion-induced power fading and free from the IBBIs. The generation of a 100 and a 500 MSym/s 16-QAM signal at 31.5 GHz and the transmission of the signals over a 25-km single-mode fiber are evaluated. An error-free transmission of the 100 MSym/s signal and the transmission of the 500 MSym/s signal with a bit-error-rate below the forward error correction threshold of 3.8 × 10 -3 are achieved.
Multiple sclerosis (MS) is a chronic illness involving the central nervous system (CNS) that is characterised by inflammation, demyelination, and degenerative changes. Dalfampridine is one of the ...available treatments for MS symptoms and comorbidities. This meta-analysis aimed to assess the safety and benefits of dalfampridine versus placebo in MS by summarising data deriving from previously published clinical randomised controlled studies (RCTs).
A total of 9 RCTs were included in this meta-analysis, involving 1691 participants. There were significant differences between dalfampridine and placebo in terms of decreased 12-item Multiple Sclerosis Walking Scale score (weighted mean difference WMD = - 3.68, 95% confidence interval CI - 5.55, - 1.80, p = 0.0001), improved response to the timed 25-foot walk test (relative risk RR = 2.57, 95% CI 1.04, 6.33, p = 0.04), increased 6-min walk test (WMD = 18.40, 95% CI 1.30, 35.51, p = 0.03), increased 9-Hole Peg Test score (WMD = 1.33, 95% CI 0.60, 2.05, p = 0.0004), and increased Symbol Digit Modalities Test score (WMD = 4.47, 95% CI 3.91, 5.02, p < 0.00001). Significant differences in the incidence of side effects were also observed (RR = 1.12, 95% CI 1.04, 1.21, p = 0.002).
Dalfampridine exerts positive effects on walking ability, finger dexterity, and cognitive function. Treatment should be administered under the guidance of a physician or pharmacist given the higher incidence of adverse events.
A photonic deramp receiver based on a photonic mixer for dual-band linear frequency-modulated continuous wave radar is proposed. In the receiver, a novel modulation scheme is developed, employing a ...dual polarization quadrature phase shift keying modulator which contains four sub-Mach-Zehnder modulators (sub-MZMs). The echoes and reference signal of the first band are modulated to light waves on a pair of peak-biased sub-MZMs for tracking, while the echoes and reference signal of the second band are modulated on the other pair of null-biased sub-MZMs for imaging. An experimental system, operating in C-band and Ku-band with a bandwidth of 850 and 3600 MHz, respectively, is demonstrated and evaluated via a series of inverse synthetic aperture radar imaging tests. The results verify the idea of the dual-band radar receiver, which provides a solution for receiving dual-band echo signals with a single hardware platform.
•178 LAB isolates were obtained from the intestine of healthy Channa argus and five potential isolates (W1, W24, C11, L1, L19) were selected for their high cholesterol removal capacity and ...antibacterial activity.•W24 and L19 isolates were able to survive in acidic and alkaline conditions, and have exhibited higher tolerance to bile salt, high surface hydrophobicity, high auto-aggregation property.•W24 and L19 were identified as Enterococcus faecalis (Genbank: MT102745.1) and Lactococcus lactis (Genbank: MT102746.1) on basis of their biochemical characteristics and 16S rRNA aequencing, and the biosafety assay confirmed that the two promising isolates were not pathogenic to C. argus.
The use of lactic acid bacteria (LAB) is a strategy employed to improve aquatic animal health status and to prevent aquaculture diseases. In the present study, two potential LAB were isolated from the intestines of Channa argus (C. argus) towards the assessment of their probiotic potential. Based on the preliminary screening on 178 isolates obtained from the intestines of C. argus, only ten LAB isolates were selected by using LAB selective media (MRS-CHOL medium) for their high cholesterol removal capacity. Five potential LAB isolates (W1, W24, C11, L1 and L19) were all had high inhibitory effects on a variety of aquatic pathogenic bacteria and all able to survive in acidic and alkaline conditions, higher tolerance to bile salt, high surface hydrophobicity, high auto-aggregation property and they were found to tolerate in in pepsin and trypsin solution environmental condition. Based on the presently observed biological characteristics, it is concluded that the W24 and L19 isolates were more effective than the W1, C11 and L1 isolates. Two potential LAB strains, W24 and L19 were identified as Enterococcus faecalis (Genbank: MT102745.1) and Lactococcus lactis (Genbank: MT102746.1) respectively by 16S rRNA sequencing. The identification of physiological and biochemical properties results showed that the W24 and L19 isolates could ferment a variety of sugars, which was in line with the characteristics of LAB. The two potential LAB isolates (W24 and L19) were susceptible to the vast majorityantibiotics and were all respectively exhibited γ-haemolysis (i.e. no haemolysis) activity. The biosafety assay confirmed that the two potential LAB isolates were not pathogenic to the host fish. Therefore, the E. faecalis W24 and L. lactis L19 may be a promising candidate for the development of functional micro-ecological feed. This study has provided insight into how optimal LAB should be isolated and screened from the intestines of C. argus.
A novel technique to transport a microwave signal over an optical fiber based on phase-modulation and coherent in-phase (I) and quadrature-phase (Q) demodulation with an extended transmission ...distance is proposed and experimentally demonstrated. In the transmitter, a Sagnac loop incorporating a phase modulator (PM) is used to generate two orthogonally polarized optical signals with one being phase modulated and the other with no modulation that acts as a remote optical reference signal. The orthogonally polarized optical signals are transmitted over a single-mode fiber (SMF) to a polarization and phase diversity coherent receiver, and are coherently detected with a free-running optical local oscillator at the receiver. Since the phase-modulated and the reference signals are transmitted over the same SMF, the optical phases are correlated, and the original signal can be recovered based on a digital signal processing algorithm. The proposed technique is experimentally evaluated. Compared with a phase-modulated coherent I/Q demodulated link without using an optical phase correlated reference signal, the transmission distance is extended from 50 m to 10 km, while providing a link gain and a spurious-free dynamic range (SFDR) of -9.5 dB and 115.8 dB · Hz 2/3 , respectively.
A novel technique to generate a microwave vector signal based on a bidirectional use of a polarization modulator (PolM) and a phase modulator (PM) in a Sagnac loop is proposed and experimentally ...demonstrated. The I/Q data streams of a vector signal are mixed with a microwave carrier and then applied to the PolM and the PM, respectively. A microwave vector signal is generated by combining two microwave signals with one obtained by beating the optical carrier and the +1 st order sideband of a phase-modulated signal and the other obtained by beating the optical carrier and the +1 st order sideband of an intensity-modulated signal. A quadrature phase is introduced due to the inherent π/2 phase shift between the optical carrier and the +1 st order sideband of the phase-modulated signal. The generation of a 4.5 GHz microwave signal at 625 Msym/s with quadrature phase-shift-keying (QPSK) modulation and the transmission of the signal over a 25-km single-mode fiber are evaluated. An error-free transmission is achieved at a received optical power of 6 dBm. By incorporating I/ Q imbalance compensation, an error-free transmission is achieved at a lower received power of 2 dBm.
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