•A dual-flip-angle blipped multi-gradient-echo (DFA-mGRE) sequence with a stack-of-stars (SOS) trajectory was developed to accelerate the acquisition for fast simultaneous three-dimensional (3D) ...multiparametric mapping of whole brain myelin water fraction (MWF), T1, proton density (PD), R2*, magnetic susceptibility (QSM), and B1 transmit field (B1+).•A novel joint-sparsity-constrained multicomponent T2*-T1 spectrum estimation (JMSE) algorithm was proposed to improve the quantification of MWF by correcting for the T1 saturation effect and B1+/B1− inhomogeneities.•By integrating the DFA-mGRE SOS sequence, the JMSE algorithm, the tissue-prior-based B1+ estimation algorithm, and the subspace-based reconstruction, our technique can provide robust multiparametric mapping of 3D whole brain MWF, T1, PD, R2*, QSM, and B1+ with a two-minute scan.
A new MRI technique is presented for three-dimensional fast simultaneous whole brain mapping of myelin water fraction (MWF), T1, proton density (PD), R2*, magnetic susceptibility (QSM), and B1 transmit field (B1+). Phantom and human (N = 9) datasets were acquired using a dual-flip-angle blipped multi-gradient-echo (DFA-mGRE) sequence with a stack-of-stars (SOS) trajectory. Images were reconstructed using a subspace-based algorithm with a locally low-rank constraint. A novel joint-sparsity-constrained multicomponent T2*-T1 spectrum estimation (JMSE) algorithm is proposed to correct for the T1 saturation effect and B1+/B1− inhomogeneities in the quantification of MWF. A tissue-prior-based B1+ estimation algorithm was adapted for B1 correction in the mapping of T1 and PD. In the phantom study, measurements obtained at an acceleration factor (R) of 12 using prospectively under-sampled SOS showed good consistency (R2 > 0.997) with Cartesian reference for R2*/T1app/M0app. In the in vivo study, results of retrospectively under-sampled SOS with R = 6, 12, 18, showed good quality (structure similarity index measure > 0.95) compared with those of fully-sampled SOS. Besides, results of prospectively under-sampled SOS with R = 12 showed good consistency (intraclass correlation coefficient > 0.91) with Cartesian reference for T1/PD/B1+/MWF/QSM/R2*, and good reproducibility (coefficient of variation < 7.0 %) in the test-retest analysis for T1/PD/B1+/MWF/R2*. This study has demonstrated the feasibility of simultaneous whole brain multiparametric mapping with a two-minute scan using the DFA-mGRE SOS sequence, which may overcome a major obstacle for neurological applications of multiparametric MRI.
Contamination of the marine environment following the accident in the Fukushima Dai-ichi nuclear power plant represented the most important artificial radioactive release flux into the sea ever ...known. The radioactive marine pollution came from atmospheric fallout onto the ocean, direct release of contaminated water from the plant and transport of radioactive pollution from leaching through contaminated soil. In the immediate vicinity of the plant (less than 500 m), the seawater concentrations reached 68 000 Bq.L−1 for 134Cs and 137Cs, and exceeded 100 000 Bq.L−1 for 131I in early April. Due to the accidental context of the releases, it is difficult to estimate the total amount of radionuclides introduced into seawater from data obtained in the plant. An evaluation is proposed here, based on measurements performed in seawater for monitoring purposes. Quantities of 137Cs in seawater in a 50-km area around the plant were calculated from interpolation of seawater measurements. The environmental halftime of seawater in this area is deduced from the time-evolution of these quantities. This halftime appeared constant at about 7 days for 137Cs. These data allowed estimation of the amount of principal marine inputs and their evolution in time: a total of 27 PBq (12 PBq–41 PBq) of 137Cs was estimated up to July 18. Even though this main release may be followed by residual inputs from the plant, river runoff and leakage from deposited sediments, it represents the principal source-term that must be accounted for future studies of the consequences of the accident on marine systems. The 137Cs from Fukushima will remain detectable for several years throughout the North Pacific, and 137Cs/134Cs ratio will be a tracer for future studies.
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► Fukushima Dai-ichi accident is the most important artificial radioactive release flux into the sea. ► Quantities of 137Cs in seawater are deduced from individual measurements. ► Local concentrations in seawater diminish regularly by a factor of two in seven days. ► Total amount of direct releases of 137Cs estimated is 27 PBq (12 PBq–41 PBq). ► Time-evolution of release fluxes is drawn.
One of the few electronic attack techniques that can deceive radars in angle is cross-eye jamming, which mimics the naturally-occurring phenomenon glint. The extreme tolerance requirements of ...cross-eye jamming mean that a retrodirective implementation is required, but published measurements of cross-eye jamming either ignore the retrodirective implementation or only simulate it. The implementation of a retrodirective cross-eye jammer and its testing against a monopulse radar are described. A procedure for calibrating the jammer is outlined and is shown to be effective by achieving large angular errors. The measured results agree well with the extended analysis of cross-eye jamming and confirm that the implemented jammer is retrodirective. Specifically, the ability of a cross-eye jammer to generate an indicated angle that never becomes zero, thereby potentially breaking a tracking lock, is confirmed.
The development of multifunctional nanoparticles has attracted increasing attention. The versatility of nanoparticles largely depends on their physiochemical properties (especially size). However, ...the optimized size range may be different for the bioapplications of each function associated with multifunctional nanoparticles. It is important to investigate every optimized size range to ascertain which size enables the best function of the nanoparticles before deciding their final size. In this work, we synthesized a series of monodisperse Fe3O4 nanoparticles with identical surface properties ranging in size from 60 to 310 nm and systematically investigated their biobehavior and application. Our data indicate that compared to their large counterparts, small Fe3O4 nanoparticles exhibited greater cellular internalization and deeper penetration into multicellular spheroids, thus enabling a higher photothermal ablation efficacy in vitro. Interestingly, larger Fe3O4 nanoparticles showed greater accumulation in tumors, thereby inducing more efficient tumor growth inhibition. In addition, 120 nm may be the optimal diameter of Fe3O4 nanoparticles for magnetic resonance imaging and photoacoustic tomography in vitro. However, more efficient in vivo imaging mediated by Fe3O4 nanoparticles will predominantly depend on their high accumulation. Our work presents a different appropriate size range for each biofunction of Fe3O4 nanoparticles, which could be a valuable reference for future nanoparticle design.
Background
Recovery after colonic surgery is invariably delayed by disturbed gut motility. It is commonly assumed that colonic motility becomes quiescent after surgery, but this hypothesis has not ...been evaluated rigorously. This study quantified colonic motility through the early postoperative period using high‐resolution colonic manometry.
Methods
Fibre‐optic colonic manometry was performed continuously before, during and after surgery in the left colon and rectum of patients undergoing right hemicolectomy, and in healthy controls. Motor events were characterized by pattern, frequency, direction, velocity, amplitude and distance propagated.
Results
Eight patients undergoing hemicolectomy and nine healthy controls were included in the study. Colonic motility became markedly hyperactive in all operated patients, consistently dominated by cyclic motor patterns. Onset of cyclic motor patterns began to a minor extent before operation, occurring with increasing intensity nearer the time of surgery; the mean(s.d.) active duration was 12(7) per cent over 3 h before operation and 43(17) per cent within 1 h before surgery (P = 0.024); in fasted controls it was 2(4) per cent (P < 0·001). After surgery, cyclic motor patterns increased markedly in extent and intensity, becoming nearly continuous (active duration 94(13) per cent; P < 0·001), with peak frequency 2–4 cycles per min in the sigmoid colon. This postoperative cyclic pattern was substantially more prominent than in non‐operative controls, including in the fed state (active duration 27(20) per cent; P < 0·001), and also showed higher antegrade velocity (P < 0·001).
Conclusion
Distal gut motility becomes markedly hyperactive with colonic surgery, dominated by cyclic motor patterns. This hyperactivity likely represents a novel pathophysiological aspect of the surgical stress response. Hyperactive motility may contribute to gut dysfunction after surgery, potentially offering a new therapeutic target to enhance recovery.
May contribute to gut dysfunction
Optical spin angular momenta in a confined electromagnetic field exhibit a remarkable difference with their free space counterparts; in particular, the optical transverse spin that is locked with the ...energy propagating direction lays the foundation for many intriguing physical effects such as unidirectional transportation, quantum spin Hall effects, photonic Skyrmions,
etc
. In order to investigate the underlying physics behind the spin-orbit interactions as well as to develop the optical spin-based applications, it is crucial to uncover the spin texture in a confined field, yet it faces challenges due to their chiral and near-field vectorial features. Here, we propose a scanning imaging technique which can map the near-field distributions of the optical spin angular momenta with an achiral dielectric nanosphere. The spin angular momentum component normal to the interface can be uncovered experimentally by employing the proposed scanning imaging technique and the three-dimensional spin vector can be reconstructed theoretically with the experimental results. The experiment is demonstrated on the example of surface plasmon polaritons excited with various vector vortex beams under a tight-focusing configuration, where the spin-orbit interaction emerges clearly. The proposed method, which can be utilized to reconstruct the photonic Skyrmion and other photonic topological structures, is straightforward and of high precision, and hence it is expected to be valuable for the study of near-field spin optics and topological photonics.
An optical spin-resolved scanning imaging technique was proposed by which the normal to the interface spin component of surface plasmon polaritons can be mapped and the three-dimensional spin vector can be reconstructed with the experimental result.
A study was undertaken to assess variation in antioxidant, antimicrobial and phytochemical properties of thirteen Moringa oleifera cultivars obtained from different locations across the globe. ...Standard antioxidant methods including the DPPH scavenging, ferric reducing power (FRAP) and β-carotene-linoleic acid model were used to evaluate the activity. Variation in the antioxidant activity was observed, with TOT4951 from Thailand being the most active, with activity five times higher than that of ascorbic acid (reference compound). A different trend was observed for the activity in the FRAP and β-carotene-linoleic acid assays. Antimicrobial activity was tested against Gram-positive (Staphylococcus aureus) and Gram-negative (Klebsiella pneumoniae) strains using the microdilution method. Acetone extracts of all cultivars exhibited good antibacterial activity against K. pneumoniae (MIC values of 0.78 mg/mL). The remaining extracts exhibited weak activity against the two microorganisms. For the antifungal activity, all the extracts exhibited low activity. Variations were observed in the total phenolic and flavonoid contents. Cultivars TOT5169 (Thailand) and SH (South Africa) exhibited highest amounts of total phenolic compounds while TOT5028 (Thailand) exhibited the lowest amounts of five times lower than the highest. The information offer an understanding on variations between cultivars from different geographical locations and is important in the search for antioxidant supplementation and anti-ageing products.
Growing evidence suggests that miR-29a has an important role in regulating tumourigenesis and development of various types of cancer. However, the role and the underlying mechanism of miR-29a in ...colorectal cancer (CRC) remain largely unknown.
MiR-29a targeted gene was identified by the luciferase assay and western blot. MiR-29a function was analysed by invasion assays and the orthotopic transplantation mouse model. The miR-29a pathway was assayed by real-time PCR, western blot and chip analysis.
KLF4 was identified as a direct target gene of miR-29a. MiR-29a promoted CRC cell invasion, which was blocked by re-expression of KLF4. In addition, MMP2 was identified as a novel direct target of KLF4. Both miR-29a overexpression and KLF4 knockdown promoted MMP2 expression but inhibited E-cadherin expression. Furthermore, clinical data indicated that both miR-29a high expression and KLF4 mRNA low expression were associated with metastasis and poor prognosis in CRC patients, and KLF4 protein expression was inversely correlated with MMP2 but positively correlated with E-cad protein expression.
Increased expression of miR-29a promoted CRC metastasis by regulating MMP2/E-cad through direct targeting KLF4, which highlights the potential of the miR-29a inhibitor as a novel agent against CRC metastasis.
Recent advances in semiconductor technology have paved the way for ultra-fast switching capabilities. This increase in switching speed enhances efficiency, power density, and frequency but also ...increases overvoltage oscillations at the switching node. Existing methods that effectively suppress this overvoltage include slower switching and minimisation of inductance, but unfortunately, these methods become very difficult to implement as the switching speed increases. A new oscillation suppression method, Zero Overvoltage Switching (ZOS), has previously been developed in which the overvoltage is suppressed very effectively by increasing both the switching speed and inductance, contrary to mainstream expectation. This is the only oscillation suppression method that becomes more effective as the switching speed increases and is not constrained by the minimisation of inductance, yet this method has not gained widespread recognition. This is expected because Zero Overvoltage Switching is not explained within the context of existing knowledge, and the argument for implementing it is difficult in the very narrow window where the advantages outweigh the effort. This research develops a generalised fundamental model to better understand Zero Overvoltage Switching by describing the mechanics of fast and slow switching events. The model is also able to provide insights that lead to methods to apply Zero Overvoltage Switching over a broader range of voltages and currents.
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The inferior cycling performance caused by large volume variation is the main problem that restricts the application of cobalt selenides in lithium-ion batteries. Herein, we ...synthesize raspberry-like Co-ethylene glycol precursor. It is further selenized into the hierarchical hollow superstructure CoSe2/CoSe bird nests that are assembled by the hollow nanosphere units of CoSe2 and CoSe nanocrystalline. CoSe2/CoSe bird nests achieve excellent cycling performance, high reversible capacity and satisfactory rate capability (1361 mAh/g at 1 A/g after 1000 cycles, 579 mAh/g at 2 A/g after 2000 cycles, 315 mAh/g at 5 A/g after 1000 cycles). Electrochemical kinetics analyses and ex-situ material characterization reveal that the surface capacitive behavior controls the electrochemical reaction, and the composite has low reaction impedance, fast and stable Li+ diffusion, and superior structural stability. The superior lithium storage performance is attributed to the unique superstructure bird nest. Large specific surface area, abundant hierarchical pores and the opening mouth result in high electrochemical activity, which induces high reversible capacity. The small hollow nanosphere units, the sufficiently thick hierarchical porous superstructure shell and the large hollow interior bring about the strong synergistic effect to improve cycling performance. The intimately coupling of CoSe2/CoSe nanocrystalline and the hollow nanosphere units guarantees high conductivity. This work has greatly enriched the understanding of structure design of high-performance cobalt selenide anodes.
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