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On the basis of the Lewis acid-catalyzed Friedel-Crafts alkylation between 1-acyl-2-arylcyclopropanecarboxylate esters and electron-rich phenols, a Sc(OTf)3 catalyzed cascade [4 + 2]-annulation reaction was developed for the direct synthesis of polysubstituted dihydronaphthols from phenols. In this reaction, the structure of products is dominated by the directing effect of the substituent groups on phenols. Meanwhile, a one-pot Friedel-Crafts alkylation/oxidative cyclization reaction was also developed for the synthesis of spiro-fused 2,5-cyclohexadienones. [ABSTRACT FROM AUTHOR]

In this paper, the molecular structures of five kinds of original natural rubber (NR) samples produced by different coagulation methods and from different regions(within six months) were studied using a pyrolysis (at 550 °C) gas chromatography/mass spectrometry (py-GC/MS) technique. The result showed that the similar molecular structures of the major degradation products, monomers (2-methyl-1,3-butadiene and 1,3-pentadiene) along with dimers of a large number of 1-methyl-4-(1-methylethenyl)cyclohexenes (limonenes) and small amounts of tran limonenes, were all found in three original NR samples, SMR20 and STR20 made all by natural coagulation, and MC-SCR5 coagulated rapidly by microorganisms. Also, the relative productivity (57.48%-59.27%) of the monomers are similar. But the some differences of the molecular structures, the monomers which included 1,4-pentadiene, 3-methyl-1,2-butadiene and 2-pentyne along with more tran limonenes dimers were exhibited in two original NR samples, GSR-RSS3 coagulated by new technology and HN-SCR5 by acetic acid, their relative productivities (61.22% and 65%) have also more differences, as compared with that of the bio-coagulated natural rubbers. Conbine our previous and current works, a conclusion can be obtained that the rubber - productions of origin is not the main factor affecting the molecular structures of natural rubber, but the coagulation processing. [ABSTRACT FROM AUTHOR]

The outbreak of COVID-19 has created a huge challenge to global health systems. Experience in fighting the epidemic shows that the development of a rapid and sensitive POCT diagnostic platform for SARS-CoV-2 that can be deployed in situ is crucial to contain the outbreak. Here, we have developed a portable microdroplet detection platform that integrated temperature controller and micro-stirring for high-throughput and ultrafast COVID-19 diagnosis. Such a device uses a p-n junction (PN junction) as the temperature controller to adjust the temperature in a single microdroplet independently and precisely, ensuring the amplification of reverse transcription loop-mediated isothermal amplification (RT-LAMP). Meanwhile, the platform incorporates an ultrasonic micro-stirring unit, greatly increasing the interaction between RT-LAMP molecules and accelerating the amplification. The results show good linearity over a wide linear range (1 to 105 copies/μL) and low LOD (0.48 copy/μL). Our method reports in only 6.1 min for high-viral load samples, and combines with sample preparation, the total detection process could be done within 30 min. Such a portable and fully integrated microdroplet molecular diagnostic platform is a promising tool for point-of-care diagnosis of COVID-19 and other infectious diseases in resource-limited settings. [Display omitted] • A portable microdroplet array integrated platform for SARS-CoV-2 detection. • The temperature of each microdroplet can be independently and precisely controlled. • Ultrasound-induced microstreaming can enhance the RT-LAMP reaction. • The method presents a low LOD with 0.48 copy/μL and detection time in only 6.1 min. • Such fully integrated device holds promise for rapid and sensitive detection in clinical diagnosis. [ABSTRACT FROM AUTHOR]

The search for efficient and selective routes for the synthesis of chiral aminocyclopropane derivatives is of great interest and importance as these structures are important components of biologically active natural products and pharmaceuticals. We herein report the enantioselective intermolecular hydroamination of substituted cyclopropenes with various amines catalyzed by chiral half-sandwich rare-earth-metal complexes. This method constitutes a 100 % atom-efficient route for the synthesis of a variety of chiral α-aminocyclopropane derivatives in high yields (up to 96 %) and excellent stereoselectivity (up to >20:1 d.r. and 99 % ee) under mild reaction conditions (25 °C). [ABSTRACT FROM AUTHOR]

The search for efficient and selective routes for the synthesis of chiral aminocyclopropane derivatives is of great interest and importance as these structures are important components of biologically active natural products and pharmaceuticals. We herein report the enantioselective intermolecular hydroamination of substituted cyclopropenes with various amines catalyzed by chiral half-sandwich rare-earth-metal complexes. This method constitutes a 100 % atom-efficient route for the synthesis of a variety of chiral α-aminocyclopropane derivatives in high yields (up to 96 %) and excellent stereoselectivity (up to >20:1 d.r. and 99 % ee) under mild reaction conditions (25 °C). [ABSTRACT FROM AUTHOR]

A novel helical tube reactor (HTR) consisting of a pre-mixer and a helical tube was designed for mixing and reaction process intensification. The pre-mixer was used to adjust and change the premixing behavior between the involved reactants, which eventually determines the environment for micromixing. Two types of pre-mixers, co-current flow pre-mixer (CCM) and cross-flow pre-mixer (CRM), were employed and their mixing performance was studied by computational fluid dynamics (CFD) simulations. Results revealed that the CRM has better mixing performance than the CCM, suggesting that the predicted micromixing efficiency of the HTR consisting of the CRM (CRM-HTR) may be better than that comprising the CCM (CCM-HTR). Furthermore, the iodide–iodate reaction system was used separately to characterize the micromixing efficiency of the HTR comprising the different types of pre-mixers, and the results are in agreement with those of CFD which predicted better micromixing performance in the CRM-HTR than the CCM-HTR. Additionally, the effects of feed position and initial dispersion size of acid solution, volumetric flow ratio, and viscosity on micromixing efficiency of the CRM-HTR were investigated. A comparison between the CRM-HTR and a straight tube reactor (CRM-TR) with a length equivalent to that of the CRM-HTR revealed that CRM-HTR has better micromixing efficiency. Moreover, the effects of curvature ratio and number of turns on micromixing efficiency of the CRM-HTR were also conducted. The results demonstrated that the curvature ratio had an important influence on the micromixing. This work shows that the novel CRM-HTR has great potential for chemical reaction process intensification. [ABSTRACT FROM AUTHOR]

We propose a facile, inexpensive and scalable inkjet-printing method to fabricate patterned lubricant-infused surfaces as the ultra-slippery platform for surface microfluidics, and demonstrate typical planar droplet manipulations. Micrometer patterns were printed on scotch tapes by a home-use inkjet printer to form a template with patterned adhesion contrast. Closely packed monolayer of microbeads was assembled driven by the water surface tension and selectively adhered on the unprinted tape. Then poly(dimethylsiloxane) (PDMS) was cast against the microbead template to form a bowl-like surface, and ultra-slippery PDMS surface was achieved after spin coating lubricant oil. Its interface characterization, sliding performances and long-time stability which are critical for surface microfluidic applications were evaluated and analyzed. Finally the patterned ultra-slippery PDMS was employed as the surface microfluidic platform, and droplet transportation, mixing, trapping and releasing functions have been enabled by very simple and facile driving methods such as pneumatic and gravity driving, which pave a new way for potential flexible and low-cost applications of surface microfluidics. [ABSTRACT FROM AUTHOR]

This paper is intended to propose the numerical methodology in optimizing the cusp gun for a 70-kV, 1-A W-band gyrotron traveling wave amplifier working at the second-harmonic TE21 mode. Two numerical methods using the simulated annealing algorithm (SAA) and genetic algorithm (GA) are adopted to perform the gun optimization. Classical electron optics software EGUN is employed to compute the beam trajectories. Maintaining the velocity ratio around 1.6, the axial velocity spreads optimized by SAA and GA are 1.44% and 0.33%, respectively, which means a great improvement compared with the manually optimized value of 2.78%. An analysis of the impact of parametric fluctuation on beam quality indicates that this cusp gun can be stably operated within a reasonable parameter scope. This paper will help to enhance the efficiency of electron gun design for gyrotron devices. [ABSTRACT FROM AUTHOR]

Starch/poly(vinyl alcohol) (PVA) films with the addition of 10 wt% CaCl2 and various content of glycerol were prepared. The effect of glycerol on the crystalline, thermal, and tensile properties of CaCl2-doped starch/PVA films was studied by X-ray diffraction, thermogravimetric analysis (TGA), and tensile testing, respectively. The effect of glycerol on the miscibility of CaCl2-doped starch/PVA films was studied by scanning electron microscopy. The CaCl2-doped starch/PVA film became more homogeneous after the addition of glycerol. The addition of glycerol would increase the crystallinity of CaCl2-doped starch/PVA film. With the addition of 10 wt% glycerol and 10 wt% CaCl2, the starch/PVA film showed the highest degree of crystallinity. The TGA results show that the thermal stability of CaCl2-doped starch/PVA film increased after the addition of glycerol. The toughness of CaCl2-doped starch/PVA films was enhanced with the addition of glycerol. The starch/PVA film with the addition of 10 wt% CaCl2 and 20 wt% glycerol showed the tensile strength of 17 MPa and the elongation at break of 428%. Moreover, the water sorption of CaCl2-doped starch/PVA film decreased after the addition of glycerol at the low and intermediate relative humidity of 33 and 54%. [ABSTRACT FROM AUTHOR]

Catalyst activity and selectivity of the multiphase catalytic reactions may be strongly reduced by mass transfer limitations. A rotating packed bed (RPB) reactor can intensify the mass transfer process by 1–3 orders magnitude compared to the traditional reactors, which has great potential for catalytic reactions. The first step of the RPB reactor applied to catalytic reactions is to prepare a monolithic catalyst with excellent mechanical strength. This work selected the structured nickel foam packing as the catalyst substrate and then deposited palladium on the surface of the porous nickel foam packing. The above monolithic catalyst was then characterized by FESEM, EDS, TEM, XRD, ICP, and 3D-CT. In order to know the coating adhesivity, the monolithic catalyst was tested by the ultrasonic vibration in an ultrasonicator tank and scouring experiments in a RPB reactor. Hydrogenation of α-methylstyrene was employed to test its catalytic performance. [ABSTRACT FROM AUTHOR]

In this paper, a novel triode-type magnetron injection gun (MIG) with three emitters designed for gyrotron traveling wave amplifiers has been presented. This MIG can be operated in Ku/Ka/Q single band or Ku-Ka/Ka-Q dual band. The optimization of the MIG is accomplished by a multiobjective genetic algorithm method. It is anticipated that this MIG possesses an axial velocity spread of <5% in all the operating frequency bands. The results of sensitivity study show that this MIG can work stably within reasonable parametric windows. Velocity spreads considering cathode surface roughness and initial thermal temperature are analyzed. Cathode configuration with heat insulation chambers is introduced to cut off the thermal flow among the emitters. Thermal analysis has been performed. [ABSTRACT FROM AUTHOR]

The impacts of climate change on forest net biomass change are poorly understood but critical for predicting forest's contribution to the global carbon cycle. Recent studies show climate change-associated net biomass declines in mature forest plots. The representativeness of these plots for regional forests, however, remains uncertain because we lack an assessment of whether climate change impacts differ with forest age. Using data from plots of varying ages from 17 to 210 years, monitored from 1958 to 2011 in western Canada, we found that climate change has little effect on net biomass change in forests ≤ 40 years of age due to increased growth offsetting increased mortality, but has led to large decreases in older forests due to increased mortality accompanying little growth gain. Our analysis highlights the need to incorporate forest age profiles in examining past and projecting future forest responses to climate change. [ABSTRACT FROM AUTHOR]

Plant-specific remorin genes have been identified in angiosperms, gymnosperms, ferns, and mosses. Several remorin genes are highly conserved in plant genomes, and their basic characteristics have been determined. Remorins have multiple biological functions, including in antibacterial defense, signal transduction, damage repair, and resistance to environmental stresses. In the present study, a full-length cDNA clone of the StREMa4 remorin gene was isolated from Ralstonia solanacearum-infected potato ( Solanum tuberosum L.) cultivar 'ED13' plants through the rapid amplification of cDNA ends. Sequence analyses revealed that StREMa4 comprised 803 bp, including a 591 bp open reading frame that encoded a protein consisting of 197 amino acids. The StREMa4 protein was highly homologous to remorins from potato and other Solanaceae species. Real-time PCR analyses revealed that in addition to being up-regulated by Ralstonia solanacearum, StREMa4 expression was induced by exogenous hormones (i.e., salicylic acid, methyl jasmonate, and abscisic acid), with some differences in the expression patterns. Tissue localization analyses indicated that StREMa4 expression was tissue-specific, occurring primarily in the phloem of stem and leaf tissues. [ABSTRACT FROM AUTHOR]

The cytochrome P450 (CYP) inhibitor SKF-525A is commonly used to study drug metabolism and toxicity, particularly hepatotoxicity. By using Western blot and immunofluorescence staining, we unexpectedly found that SKF-525A at 2–20 μM caused remarkable accumulation of microtubule-associated protein light chain 3 II (LC3-II) in primary rat hepatocytes at 1, 4 and 24 h, indicating that autophagy was disrupted. SKF-525A showed no effects on chloroquine induced LC3-II accumulation, suggesting that autophagic flux was blocked, which is further supported by the increased level of the p62 protein after SKF-525A treatment. SKF-525A did not affect proteasome activities or gene expression of LC3-II or p62. Immunofluorescence of green fluorescent protein fused lysosomal-associated membrane protein 1 (LAMP1, a specific protein marker for lysosomes) and LC3-II showed that co-localization of these two proteins was partially abolished by SKF-525A, indicating that autophagosome-lysosome fusion was blocked. The other five CYP inhibitors, metyrapone, 1-aminobenzotriazole, alpha-naphthoflavone, ticlopidine, and ketoconazole, showed no effects in parallel experiments. These findings provide novel insights into the mechanisms by which various CYP inhibitors differentially affect a same drug's toxicity in hepatocytes. The data also indicate that SKF-525A is not an ideal chemical inhibitor for probing the relation between CYP mediated metabolism and toxicity in primary hepatocytes. [ABSTRACT FROM AUTHOR]

We correct theorems of Luo (2014) [1] , concerning nonexistence of complete biminimal submanifolds in nonpositive curvature space forms, and Lemma 4.2 in Luo (2014) [1] . [ABSTRACT FROM AUTHOR]

Background: Abundant evidence from epidemiological and clinical studies has proven that diabetes mellitus (DM) is correlated with an increased incidence of dementia and Alzheimer's disease (AD). Insulin resistance is considered to play an important role in the associations between DM and dementia. However, whether insulin sensitizer drugs are effective in preventing dementia still remains unclear. Methods: Electronic searches of PubMed, EMBASE, Google Scholar, and the ISI Web of Science were conducted to identify studies that reported about the associations between insulin sensitizers and the incidence of dementia. The included studies were reviewed, and a meta-analysis was performed using STATA to determine the combined relative risk(RR) forthe incidence of dementia when using insulin sensitizers. Subgroup analysis and meta regression were also conducted. Results: In total, nine comparisons out of six studies were qualified for inclusion, and data from 544,093 participants were evaluated. The results of the meta-analysis revealed a combined RRof 0.78 (95% CI 0.64-0.95, p = 0.015) for the incidence of dementia when using insulin sensitizers. The incidence rate of dementia was reduced with either metformin (RR 0.79, 95% CI 0.62-1.01, p = 0.064) or thiazolidinediones (RR 0.75, 95% CI 0.56-1.00, p = 0.050), both with a marginal trend toward significance. Conclusions: The results indicate that insulin sensitizer drugs might provide protection against incident dementia. Controlled studies with large samples should be conducted to further confirm these conclusions and provide information for clinical strategies. [ABSTRACT FROM AUTHOR]

Sensitive and accurate detection of SARS-CoV-2 methods is meaningful for preventing and controlling the novel coronavirus. The detection techniques supporting portable, onsite, in-time, and online data transfer are urgently needed. Here, we one-click investigated the shape influence of silver nanostructures on SERS performance and their applications in the sensitive detection of SARS-CoV-2. Such investigation is achieved by adjusting multiple parameters (concentration, potential, and time) on the integrated electrochemical array, thus various morphologies (e.g., bulk, dendritic, globular, and spiky) can be one-click synthesized. The SERS performance results indicated that dendritic nanostructures are superior to the other three with an order of magnitude signal enhancement. Such on-electrode dendritic silver substrate also represents high sensitivity (LOD = 7.42 × 10−14 M) and high reproducibility (RSD = 3.67%) toward the SARS-CoV-2 RNA sequence detection. Such approach provides great potentials for rapid diagnosis and prevention of diverse infectious diseases. [Display omitted] • Multiple parameters can be adjusted by one-click on the integrated electrochemical array. • Various morphologies can be synthesized for screening the SERS performance. • The platform can achieve high-throughput and simultaneous SERS sensing. [ABSTRACT FROM AUTHOR]

• The vapor–liquid equilibrium of R1243zf in PEC7 and PEC9 were measured. • The NRTL model was utilized to model the experimental values. • Henry's law constants for the two mixtures were determined and analyzed. Vapor-liquid equilibrium measurements for 3, 3, 3‑trifluoropropene (R1243zf) with pentaerythritol tetraheptanoate (PEC7) and pentaerythritol tetranonanoate (PEC9) were performed using isochoric saturation method over temperatures from 278.15 K to 343.15 K and pressures up to 1.0 MPa. The experimental data were regressed by non-random two liquid (NRTL) activity coefficients model. In addition, the dissolving abilities of different refrigerants (R1243zf, R600a, RE170, R1234ze(E), R152a, R134a, R1234yf) in PEC7 and PEC9 were compared and analyzed. [ABSTRACT FROM AUTHOR]

A hydrodynamic and acoustic mode decomposition method for velocity and pressure based on Helmholtz decomposition and momentum equation is proposed. It is able to decompose the flow variables of velocity and pressure into their vortical, acoustic, and entropic components. The method is verified and validated by a Mach 0.9 turbulent jet flow. The spectral properties of the decomposed hydrodynamic and acoustic components verify that the method successfully separates the two parts. Spectral proper orthogonal decomposition analysis of the decomposed fields clearly identifies the spatial structures of the first three radial orders trapped waves in the potential core and validates the shallow angle noise generation mechanism of spectral leakage for subsonic wavepacket. The present work provides insights into flow–acoustic interaction and aeroacoustic source identification for turbulent jets. [ABSTRACT FROM AUTHOR]

We investigated the effects of 12-week brisk walking on chronotropic response in hypertensive patients aged 40–69. 77 participants in exercise group underwent 12-week brisk walking, while 66 participants in control group received health education. Chronotropic parameters, resting blood pressure, and physical fitness including peak oxygen consumption (VO2peak) were measured. After 12 weeks, the systolic blood pressure (SBP) was decreased (−6.104 mmHg, 95%CI −8.913 to −3.295 mmHg, P<0.0001), while metabolic chronotropic relationship (MCR) slope and VO2peak were increased (0.073, 95%CI 0.001 to 0.145, P=0.046; 1.756 mL/kg/min, 95%CI 0.891 to 2.622 mL/kg/min, P<0.0001) in exercise group compared to baseline. The chronotropic response index (CRI) at 25–75 W load were decreased (−0.210, 95%CI −0.307 to −0.112, P<0.0001; −0.144, 95%CI − 0.204 to −0.083, P<0.0001; −0.078, 95%CI −0.135 to −0.022, P=0.007) in control group after 12 weeks. The relative changes (%Δ) of systolic and diastolic blood pressure were negatively correlated with %ΔVO2peak (r=−0.233, r=−0.187), while %ΔMCR and %ΔCRI at 50–75 W load were positively correlated with %ΔVO2peak after 12 weeks (r=0.330, r=0.282, r =0.370). %ΔSBP was also positively correlated with %ΔMCR (r =−0.213). In conclusion, 12-week brisk walking reduced SBP by improving chronotropic response in hypertensive patients aged 40–69. The enhanced chronotropic response was associated with enhanced cardiorespiratory fitness. [ABSTRACT FROM AUTHOR]

Polymer blending is a typical and conventional approach for integrating the excellent physical/chemical properties of individual polymer components. Specifically, the mechanical toughness and strength of polyamide-6 (PA6)/polyketone (PK) blend are substantially enhanced compared to either PA6 or PK individual component. Nevertheless, there are few atomic-level insights into such mechanical property enhancement. In this study, solid-state nuclear magnetic resonance (NMR) is utilized as a main tool to understand the molecular origin of the mechanical enhancement of PA6/PK blends. The proton relaxation times are used to evaluate the miscibility and domain sizes in PA6/PK blends, and to determine the crystallinity of each component, where both conventional DSC and WAXD experiments fail because of similar crystallization/melting behaviors of PA6 and PK components. 2D 1H–13C WISE (wideline separation) and HETCOR (heteronuclear correlation) solid-state NMR spectroscopy were performed to further reveal the nano-heterogeneous structures and hydrogen bonding interactions in PA6/PK blend. With further combination with FTIR and SEM results, the previous characteristic morphological model for elucidating the toughening mechanism for PA6/PK blends is refuted, and it is proposed that the superior performance of PA6/PK blend is resulted from the synergistic effects of enhanced interfacial adhesion and interconnected interphase percolated in the bulk PA6/PK blends via hydrogen bonds. We envisage the detailed molecular level insights provided by solid-state NMR spectroscopy could assist in the bottom-up design of high performance polymer blend materials. [Display omitted] • The locations of hydrogen bonding between PA6 and PK are precisely determined. • The strength of hydrogen bonding interactions is semi-quantitatively characterized. • A complementary approach for studying crystallization of polymer blends is provided. • Insights into the toughening mechanism via solid-state NMR techniques are obtained. [ABSTRACT FROM AUTHOR]

Rapid detection and accurate analysis of trace samples is an important prerequisite for precision medicine. Here we integrated capillary with ultrasound to induce biomarkers enrichment in nanoliter samples, and developed a nanoliter sample enrichment analysis method for ultra-trace miRNA biosensing. The interaction between ultrasonic field and capillary provides a gradient ultrasound field, which is essential for the aggregation of functionalized microspheres along with the enrichment of specific biomarkers. The results indicated that the enrichment of the biomarkers effectively enhanced the fluorescence intensity, and the limit of detection reaches 7.8✕10−12 M in 100 nL. Such integrated device can realize ultrasonic enrichment and visual analysis of target samples, and provides a new idea for rapid and highly sensitive detection of ultra-trace biomarkers in clinical diagnosis. • A nanoliter sample enrichment detection method for ultra-trace miRNA biosensing. • Integrated capillary with ultrasound enables capture and enrichment of specific trace biomarkers. • Such integrated device provides a new idea for rapid and highly sensitive detection in clinical diagnosis. [ABSTRACT FROM AUTHOR]

Chemical investigation on the fruits of Vitex rotundifolia Linnaeus f. Afforded 19 compounds, including three diterpenoids (1 - 3), two iridoids (4 and 5), three xanthones (6 – 8), an alkaloid (9), seven lignans (10 – 16), and three sesquilignans (17 – 19). The structures of these compounds were established via spectroscopic analysis and comparison of their NMR data with the literature. Compounds 1 , 6 – 9 , 11 – 18 were isolated from V. rotundifolia for the first time. The chemotaxonomic significance of these isolated compounds was summarized herein. • Nineteen compounds were obtained from the fruits of Vitex rotundifolia. • Compounds 1 , 6 – 9 , 11 – 18 were isolated from V. rotundifolia for the first time. • The chemotaxonomic significance of the isolated compounds was summarized. [ABSTRACT FROM AUTHOR]

La 1–x Sr x MnO 3 perovskite oxides are promising electrocatalysts for Li O 2 batteries because of their excellent intrinsic catalytic activity for oxygen reduction reaction (ORR). However, the relatively inert catalytic activity for oxygen evolution reaction (OER) suppresses their practical applications in Li O 2 battery. Here, nanoscale NiCo 2 O 4 (NCO) layer with high OER catalytic activity has been homogenously incorporated into the surface of La 0.8 Sr 0.2 MnO 3 (LSM) nanorods to form a core-shell structure. In this typical structure, the ORR mainly occurred on the LSM core, while the OER mainly occurred on the nanoscale NCO shell, and structure damage of catalysts coming from gas evolution can be greatly avoided. The synergy of high catalytic activity and core–shell structure results in the Li O 2 battery with good rate capability and excellent cycle stability, which sustains 80 cycles without capacity attenuation at a high current density of 200 mA g −1 . [ABSTRACT FROM AUTHOR]

In this paper, we propose a novel and robust local image descriptor to resolve the problem of complex illumination variations on low-level feature matching. Many classic local feature descriptors are invariant to linear illumination or monotonous intensity shift, but cannot handle more complex nonlinear illumination changes, which often occur due to the different time of exposure, the viewing direction, different types of light-surface interactions and other varying brightness changes. The presented descriptor that extracts the histograms of oriented gradients and Uniform Symmetric-Local Binary Pattern (US-LBP) features for each feature point neighborhood in the scale space. Extensive experiments show that the proposed descriptor outperforms many state-of-the-art descriptors such as SIFT, ORB, SURF and FREAK under the problem of local image matching, especially demonstrating the effectiveness of our method under complex illumination changes. [ABSTRACT FROM AUTHOR]

Most surgery scheduling is done 1 day in advance. Caused by lack of overall planning, this scheduling scheme often results in unbalanced occupancy time of the operating rooms. So we put forward a rolling horizon mixed integer programming model for the scheduling. Rolling horizon scheduling refers to a scheduling scheme in which cyclic surgical requests are taken into account. Surgical requests are updated daily. The completed surgeries are eliminated, and new surgeries are added to the scheduling list. Considering day-to-day demand for surgery, we develop a non-rolling scheduling model (NRSM) and a rolling horizon scheduling model (RSM). By comparing the two, we find that the quality of surgery scheduling is significantly influenced by the variation in demand from day to day. A rolling horizon scheduling will enable a more flexible planning of the pool of surgeries that have not been scheduled into this main blocks, and hence minimize the idle time of operating rooms. The strategy of the RSM helps balance the occupancy time among operating rooms. Using surgical data from five departments of the West China Hospital (WCH), we generate surgical demands randomly to compare the NRSM and the RSM. The results show the operating rooms' average utilization rate using RSM is significantly higher than when applying NRSM. [ABSTRACT FROM AUTHOR]

In order to enhance the efficiency of confocal gyrotron traveling-wave tubes (gyro-TWTs), this paper is intended to present a novel triode-type magnetron injection gun for a 140-GHz 2-kW confocal gyro-TWT. This novel gun, which has a pair of sectorial emitters, is expected to obtain an axial velocity spread of 7.83% and a velocity ratio of 1.01 with an anode voltage of 35 kV and a beam current of 2.4 A. The design procedure has been given in detail. Computer simulations have been carried out using 3-D electromagnetic code computer simulation technology particle tracing. The sensitivity analysis has been performed to study the parametric dependence of modulating anode voltage, accelerating anode voltage, and cathode magnetic field on beam qualities. Results show that this novel gun can be operated stably within a certain parametric scope. [ABSTRACT FROM AUTHOR]

Canonical correlation analysis (CCA) has proven an effective tool for two-view dimension reduction due to its profound theoretical foundation and success in practical applications. In respect of multi-view learning, however, it is limited by its capability of only handling data represented by two-view features, while in many real-world applications, the number of views is frequently many more. Although the ad hoc way of simultaneously exploring all possible pairs of features can numerically deal with multi-view data, it ignores the high order statistics (correlation information) which can only be discovered by simultaneously exploring all features. Therefore, in this work, we develop tensor CCA (TCCA) which straightforwardly yet naturally generalizes CCA to handle the data of an arbitrary number of views by analyzing the covariance tensor of the different views. TCCA aims to directly maximize the canonical correlation of multiple (more than two) views. Crucially, we prove that the main problem of multi-view canonical correlation maximization is equivalent to finding the best rank-$1$ approximation of the data covariance tensor, which can be solved efficiently using the well-known alternating least squares (ALS) algorithm. As a consequence, the high order correlation information contained in the different views is explored and thus a more reliable common subspace shared by all features can be obtained. In addition, a non-linear extension of TCCA is presented. Experiments on various challenge tasks, including large scale biometric structure prediction, internet advertisement classification, and web image annotation, demonstrate the effectiveness of the proposed method [ABSTRACT FROM PUBLISHER]

Temporal increases of tree mortality have been observed in regions where global warming has decreased long-term water availability and/or induced droughts. However, temporal decreases in water availability are not a global phenomenon. Understanding how water deficit-free forests respond to the recent effects of climate change is paramount towards a full appreciation of the impacts of climate change on global forests. Here, we reveal temporally increasing tree mortality across all study species over the last three decades in the central boreal forests of Canada, where long-term water availability has increased without apparent climate change-associated drought. In addition, we find that the effects of conspecific tree-to-tree competition have intensified temporally as a mechanism for the increased mortality of shade-intolerant tree species. Our results suggest that the consequences of climate change on tree mortality are more profound than previously thought. [ABSTRACT FROM AUTHOR]

Biomass change of the world's forests is critical to the global carbon cycle. Despite storing nearly half of global forest carbon, the boreal biome of diverse forest types and ages is a poorly understood component of the carbon cycle. Using data from 871 permanent plots in the western boreal forest of Canada, we examined net annual aboveground biomass change (Δ AGB) of four major forest types between 1958 and 2011. We found that Δ AGB was higher for deciduous broadleaf ( DEC) (1.44 Mg ha−1 year−1, 95% Bayesian confidence interval ( CI), 1.22-1.68) and early-successional coniferous forests ( ESC) (1.42, CI, 1.30-1.56) than mixed forests ( MIX) (0.80, CI, 0.50-1.11) and late-successional coniferous ( LSC) forests (0.62, CI, 0.39-0.88). Δ AGB declined with forest age as well as calendar year. After accounting for the effects of forest age, Δ AGB declined by 0.035, 0.021, 0.032 and 0.069 Mg ha−1 year−1 per calendar year in DEC, ESC, MIX and LSC forests, respectively. The Δ AGB declines resulted from increased tree mortality and reduced growth in all forest types except DEC, in which a large biomass loss from mortality was accompanied with a small increase in growth. With every degree of annual temperature increase, Δ AGB decreased by 1.00, 0.20, 0.55 and 1.07 Mg ha−1 year−1 in DEC, ESC, MIX and LSC forests, respectively. With every cm decrease of annual climatic moisture availability, Δ AGB decreased 0.030, 0.045 and 0.17 Mg ha−1 year−1 in ESC, MIX and LSC forests, but changed little in DEC forests. Our results suggest that persistent warming and decreasing water availability have profound negative effects on forest biomass in the boreal forests of western Canada. Furthermore, our results indicate that forest responses to climate change are strongly dependent on forest composition with late-successional coniferous forests being most vulnerable to climate changes in terms of aboveground biomass. [ABSTRACT FROM AUTHOR]

This paper is intended to present the optimal design of a triode type magnetron injection gun (MIG) for a 300 kW, 30 A gyrotron traveling wave tube (gyro-TWT), which is operated at Q band fundamental TE 01 mode. Based on the analysis of velocity ratio (VR) distribution along the emission strip (ES), a further optimization of cathode geometry on the basis of a preliminary optimized gun is performed, and a new cathode structure is proposed. Compared with initial optimal parameters, the new structure demonstrates a decline of transverse velocity spread (TVS) from 3.66% to 0.57% and longitudinal velocity spread (LVS) from 4.11% to 0.72%, while VR is maintained at 1.05. The achieved overall LVS reaches as low as 3.44% when considering cathode surface roughness and thermal temperature effect. The sensitivity study has been carried out by changing the gun parameters like anode voltage, beam current, and cathode magnetic field to ensure the practical operation stability. [ABSTRACT FROM AUTHOR]

The purpose of this work was to develop a thermal oxidation technique to improve the wear resistance of titanium alloy for the application of biomedical field. It was found that rutile TiO 2 film was formed on the surface of titanium alloy after thermal oxidation at 700 °C in a gas mixture of nitrogen with 40% oxygen by volume ratio. The nanohardness of TiO 2 film was 21.11 GPa, 299.1% higher than that of titanium alloy. The biotribological test revealed that thermal oxidized titanium alloy exhibited low friction coefficient and high wear resistance, which indicated that the thermal oxidized titanium alloy could be a potential candidate for artificial joints. [ABSTRACT FROM AUTHOR]

The magnetron injection gun (MIG) is an important component in the gyro-traveling wave tube (gyro-TWT). The electron velocity spread induced to the mismatch of the electric and magnetic fields influences the performance of gyro-TWT. To improve electron beam quality, we designed a modulating anode with curved geometry. And the multi-objective genetic algorithm was employed to optimize the curved geometry. An electron beam with a velocity ratio of 1.05 and low transverse velocity spread of 0.31% in a MIG for a Q-band gyro-TWT is obtained. Compared with the previous design with a transverse velocity spread of 1.17%, the electron beam performance got improved. And the thermal analysis and parametric sensitivity were done. The curved MIG can stably provide an electron beam with a transverse spread lower than 0.8%. [ABSTRACT FROM AUTHOR]

Electrodynamics theory tells that EM waves are generated from accelerated charged particles. Conventional radiators such as antennas are understood to emit waves because of the current's distribution and accumulation in the capacitor, where electrons are accelerated. In MEMS mechanisms, charges can be accelerated by the mechanical motion, which suggests that an MEMS structure can also be a radiator. The electrodynamics to theoretically analyse the EM wave radiation from MEMS is used. During the electrostatic nonlinear pull‐in instability MEMS, where the electrostatic gap has become narrower than the 2/3 of the initial gap, the distributed charges are accelerated at a very high rate so as to generate significant power radiation in the form of EM waves. The MEMS's mechanical accelerations are analysed to calculate the transient radiations in both spatial and frequency domains. [ABSTRACT FROM AUTHOR]

• Release and perception of odorants in grilled eel during chewing were monitored. • External standard method can be used to quantify key odorants during chewing. • Two cycles/s was a great chewing frequency for eating. • The aroma perception during eating grilled eel was divided into three stages. The release mechanism of odorants in the oral cavity during consumption directly affects sensory attributes, consumers' preferences, and ultimately purchase intent. Targets was set to monitor in real-time the key odorants released from grilled eel during mastication via an atmospheric pressure chemical ionization mass spectrometry (APCI-MS) connected with a nose interface. The release and perception of odorants during mastication were divided into three distinct phases. Dimethyl sulfide was the main odorant in the first stage. The release and perception of fishy aromas were predominant in the middle and last stages of mastication contributed by trimethylamine, 1-penten-3-ol, and 2-methyl-1-butanol. Chewing behavior experiments suggested that extending the chewing period to >20 s and having a chewing frequency of 2 cycles/s could enhance the aroma delivery of grilled eel and optimize the consumer experience. Consequently, the results explained the relationship between aroma release and the optimal chewing behavior for grilled eel consumption. [ABSTRACT FROM AUTHOR]

The chemistry of the metal-organic frameworks (MOFs) coating may affect the biological functionality of the encapsulated biomacromolecules in harsh environment. Enzymes encapsulated in hydrophilic MAF-7 can retain high activity in harsh environment. We conducted this study to prepare a non-invasive wearable uircase@MAF-7-based electrochemical sensor that can achieve accurate and sensitive detection of UA levels in sweat by integrating a flexible microfluidic chip and wireless electronic readout device. The flexible microfluidic chip enabled an easy and effective collection of sweat samples. MAF-7 protected enzyme activity by encapsulating uricase. The uricase@MAF-7-based electrochemical sensor enabled the highly sensitive detection of UA in the concentration range of 2 μM–70 μM with a detection limit of as low as 0.34 μM. Additionally, we evaluated the utility of the sensor for monitoring UA levels in real sweat samples by means of a high purine dietary challenge. This personalized wearable sweat sensing device has a potential to be used for monitoring disease-related metabolites in daily life. [Display omitted] • The flexible microfluidic chip enabled an easy and effective collection of sweat. • We embedded uricase into hydrophilic MAF-7 using the one-pot strategy. • This wearable sweat sensing device can monitor disease-related metabolites. [ABSTRACT FROM AUTHOR]

Recently, increasing evidence suggests that reef-building corals exposed to elevated suspended solids (SS) are largely structured by changes in underwater light availability (ULA). However, there are few direct and quantitative observations in situ support for this hypothesis; in particular, the contribution of SS to the diffuse attenuation coefficient of the photosynthetically active radiation (K d-PAR) variations is not yet fully understood. Here, we investigated the variations in ULA, the structure of coral assemblages, and the concentration and composition of SS on the Luhuitou fringing reef, Sanya, China. Light attenuation was rapid (K d-PAR : 0.60 ± 0.39 m-1) resulting in a shallow euphotic depth (Z eu-PAR) (<11 m). Benthic PAR showed significant positive correlations with branching and corymbose corals (e.g. Acropora spp.), while massive and encrusting species (e.g. Porites spp.) dominated the coral communities and showed no significant correlations with PAR. These results indicate that the depth range available for coral growth is shallow and the tolerance to low-light stress differs among coral species. Notably, K d-PAR showed no significant correlations with the grain size fractions of SS, whereas significant positive correlations were found with its organic fraction content, demonstrating that the light attenuation of SS is mainly regulated by particulate organic matter (POM). Intriguingly, our isotopic evidence revealed that POM concentration contributed the most to changes in K d-PAR , with its source being slightly less important. Combined, our results highlight ULA regulated by POM is an important factor in contributing to changes in coral assemblages on inshore turbid reefs, and reducing the input of terrestrial materials, especially POM, is an effective measure to alleviate the low-light stress on sensitive coral species. [Display omitted] • Light attenuation was rapid resulting in a shallow euphotic depth (<11 m). • The structure of coral assemblages is largely determined by the light availability. • Underwater light availability is mainly regulated by particulate organic matter (POM). • Differences in the source of POM plays an influential, but not major, role in reducing light. • Reduction of terrestrial materials, especially POM, may alleviate the low-light conditions effectively. [ABSTRACT FROM AUTHOR]

In a charge-coupled device-based visual tracking system (VTS), the control bandwidth is restricted by the image sensor's time delay, which hinders a high tracking performance. Compared with the feedback control, a delay-compensation control method called the Smith predictor (SP) could improve the tracking performance by moving the delay outside the closed loop to relax the constraint on the controller. However, the performance improvement is limited because delay still exists in the system, resulting in a deviation between input and output. In addition, in the previous VTS with SP, the controller was commonly adjusted based on experience, which would easily lead to an overly conservative design. To solve these problems, an enhanced Smith predictor (ESP) by Kalman filter prediction is introduced, and the controller design criteria based on control stability is quantitatively analyzed. Based on the typical SP, an additional Kalman filter is added to the forward path to predict the current position based on the past position information, which further eliminates the effect of the delay. Then, according to the small gain theorem, the design principle of the controller when there is a model mismatch is given to release the control performance as much as possible. Experimental results confirm that the proposed ESP method has a stronger error suppression characteristic in a low frequency when compared with the SP method. [ABSTRACT FROM AUTHOR]

Background: Achondroplasia is a congenital skeletal system malformation caused by missense variant of FGFR3 gene with an incidence of 1 per 20,000–30,000 newborns, which is an autosomal dominant inheritance disease. Despite similar imaging features, the homozygous achondroplasia is absolutely lethal due to thoracic stenosis, whereas heterozygous achondroplasia does not lead to fetal death. Case presentation: A fetus with progressive rhizomelic short limbs and overt narrow chest was detected by prenatal ultrasound in the second trimester. Gene sequencing results of amniotic fluid sample indicated a rare missense variant NM_000142.4: c.1123G > T(p.Gly375Cys), leading to a glycine to cysteine substitution. Re-sequencing confirmed that it was a heterozygous variant, and thoracic stenosis was then confirmed in the corpse by radiological examination. Conclusions: We identified a heterozygous variant of the FGFR3 gene as the rare pathogenic variant of severe achondroplasia in a fetus. Heterozygous variants of p.Gly375Cys may have a severe phenotype similar to homozygote. It's crucial to combine prenatal ultrasound with genetic examination to differentiate heterozygous from homozygous achondroplasia. The p.Gly375Cys variant of FGFR3 gene may serve as a vital target for the diagnosis of severe achondroplasia. [ABSTRACT FROM AUTHOR]

Under complex geostress caused by long-term geological evolution, approximately parallel bedding structures are normally created in rocks due to sedimentation or metamorphism. This type of rock is known as transversely isotropic rock (TIR). Due to the existence of bedding planes, the mechanical properties of TIR are quite different from those of relatively homogeneous rocks. The purpose of this review is to discuss the research progress into the mechanical properties and failure characteristics of TIR and to explore the influence of the bedding structure on the rockburst characteristics of the surrounding rocks. First, the P-wave velocity characteristics of the TIR is summarized, followed by the mechanical properties (e.g., the uniaxial compressive strength, the triaxial compressive strength, and tensile strength) and the related failure characteristics of the TIR. The strength criteria of the TIR under triaxial compression are also summarized in this section. Second, the research progress of the rockburst tests on the TIR is reviewed. Finally, six prospects for the study of the transversely isotropic rock are presented: (1) measuring the Brazilian tensile strength of the TIR; (2) establishing the strength criteria for the TIR; (3) revealing the influence mechanism of the mineral particles between the bedding planes on rock failure from the microscopic point of view; (4) investigating the mechanical properties of the TIR in complex environments; (5) experimentally investigating the rockburst of the TIR under the stress path of "the three-dimensional high stress + internal unloading + dynamic disturbance"; and (6) studying the influence of the bedding angle, thickness, and number on the rockburst proneness of the TIR. Finally, some conclusions are summarized. [ABSTRACT FROM AUTHOR]

This paper investigates the detrimental effect of lizardite surface characteristics on pentlandite flotation. To reduce the effect, two different starch graft copolymers, starch–graft–polyacrylamide (S–g–PAM) and starch–graft–polyacrylic acid (S–g–PAA) were synthesized as depressants for lizardite. The flotation results show that at pH value of 8, where the flotation of lizardite and pentlandite are routinely performed, S–g–PAM and S–g–PAA improve pentlandite recovery efficiently, compared with the traditional depressant carboxymethyl cellulose (CMC). Experimental results demonstrate that S–g–PAM and S–g–PAA disperse the hydrophilic lizardite particles from the pentlandite surface and also flocculate lizardite particles. [ABSTRACT FROM AUTHOR]

To determine the influence of plant density and powdery mildew infection of winter wheat and to predict grain yield, hyperspectral canopy reflectance of winter wheat was measured for two plant densities at Feekes growth stage (GS) 10.5.3, 10.5.4, and 11.1 in the 2009–2010 and 2010–2011 seasons. Reflectance in near infrared (NIR) regions was significantly correlated with disease index at GS 10.5.3, 10.5.4, and 11.1 at two plant densities in both seasons. For the two plant densities, the area of the red edge peak (Σdr680–760 nm), difference vegetation index (DVI), and triangular vegetation index (TVI) were significantly correlated negatively with disease index at three GSs in two seasons. Compared with other parameters Σdr680–760 nm was the most sensitive parameter for detecting powdery mildew. Linear regression models relating mildew severity to Σdr680–760 nm were constructed at three GSs in two seasons for the two plant densities, demonstrating no significant difference in the slope estimates between the two plant densities at three GSs. Σdr680–760 nm was correlated with grain yield at three GSs in two seasons. The accuracies of partial least square regression (PLSR) models were consistently higher than those of models based on Σdr680760 nm for disease index and grain yield. PLSR can, therefore, provide more accurate estimation of disease index of wheat powdery mildew and grain yield using canopy reflectance. [ABSTRACT FROM AUTHOR]

Introduction: The timing of definitive aneurysm treatment (coiling or clipping) in poor-grade (Hunt-Hess IV or V) subarachnoid haemorrhage (SAH) patients has been a controversial topic. The purpose of this retrospective study was to analyse whether ultra-early coiling of ruptured intracranial aneurysms improves the clinical outcomes of poor-grade SAH patients. Methods: The records of patients with aneurysmal SAH who were treated with endovascular coiling were retrieved. The patients were classified into two groups: group A (patients coiled within 24 h of SAH) and group B (patients coiled ≥ 24 h after SAH). For each group, the patient demographics, Fisher grade, aneurysm characteristics and clinical outcomes were recorded. Outcomes were measured at 6 months using the modified Rankin Scale (mRS). Results: Thirty-one patients were coiled within 24 h of SAH (group A), and fourteen patients were coiled ≥24 h after SAH (group B). Groups A and B had similar clinical and angiographic characteristics. The clinical outcomes showed that a total of 58.1 % of the patients (18 of 31) in group A were independent (mRS 0-2) compared with 21.4 % of the patients (3 of 14) in group B ( P = .028). Univariate analysis demonstrated that ultra-early coiling ( P = .028) proved to be an independent predictor of better clinical outcomes (mRS 0-2). Conclusions: Ultra-early (<24 h after SAH) coiling of ruptured aneurysms was associated with improved clinical outcomes compared to coiling at ≥24 h in poor-grade SAH patients. Larger, prospective studies are required to adequately assess the outcome differences between these two groups. [ABSTRACT FROM AUTHOR]

In the biharmonic submanifolds theory there is a generalized Chen’s conjecture which states that biharmonic submanifolds in a Riemannian manifold with non-positive sectional curvature must be minimal. This conjecture turned out false by a counter example of Y.L. Ou and L. Tang in Ou and Tang (2012). However it remains interesting to find out sufficient conditions which guarantee this conjecture to be true. In this note we prove that: 1. Any complete biharmonic submanifold (resp. hypersurface) ( M , g ) in a Riemannian manifold ( N , h ) with non-positive sectional curvature (resp. Ricci curvature) which satisfies an integral condition: for some p ∈ ( 0 , + ∞ ) , ∫ M | H → | p d μ g < + ∞ , where H → is the mean curvature vector field of M ↪ N , must be minimal. This generalizes the recent results due to N. Nakauchi and H. Urakawa in Nakauchi and Urakawa (2013, 2011). 2. Any complete biharmonic submanifold (resp. hypersurface) in a Riemannian manifold of at most polynomial volume growth whose sectional curvature (resp. Ricci curvature) is non-positive must be minimal. 3. Any complete biharmonic submanifold (resp. hypersurface) in a non-positively curved manifold whose sectional curvature (resp. Ricci curvature) is smaller than − ϵ for some ϵ > 0 which satisfies that ∫ B ρ ( x 0 ) | H → | p + 2 d μ g ( p ≥ 0 ) is of at most polynomial growth of ρ , must be minimal. We also consider ε -superbiharmonic submanifolds defined recently in Wheeler (2013) by G. Wheeler and prove similar results for ε -superbiharmonic submanifolds, which generalize the result in Wheeler (2013). [ABSTRACT FROM AUTHOR]

The tyrosine kinase inhibitor regorafenib was approved by regulatory agencies for cancer treatment, albeit with strong warnings of severe hepatotoxicity included in the product label. The basis of this toxicity is unknown; one possible mechanism, that of mitochondrial damage, was tested. In isolated rat liver mitochondria, regorafenib directly uncoupled oxidative phosphorylation (OXPHOS) and promoted calcium overload-induced swelling, which were respectively prevented by the recoupler 6-ketocholestanol (KC) and the mitochondrial permeability transition (MPT) pore blocker cyclosporine A (CsA). In primary hepatocytes, regorafenib uncoupled OXPHOS, disrupted mitochondrial inner membrane potential (MMP), and decreased cellular ATP at 1 h, and triggered MPT at 3 h, which was followed by necrosis but not apoptosis at 7 h and 24 h, all of which were abrogated by KC. The combination of the glycolysis enhancer fructose plus the mitochondrial ATPase synthase inhibitor oligomycin A abolished regorafenib induced necrosis at 7 h. This effect was not seen at 24 h nor with the fructose or oligomycin A separately. CsA in combination with trifluoperazine, both MPT blockers, showed similar effects. Two compensatory mechanisms, activation of AMP-activated protein kinase (AMPK) to ameliorate ATP shortage and induction of autophagy to remove dysfunctional mitochondria, were found to be mobilized. Hepatocyte necrosis was enhanced either by the AMPK inhibitor Compound C or the autophagy inhibitor chloroquine, while autophagy inducer rapamycin was strongly cytoprotective. Remarkably, all toxic effects were observed at clinically-relevant concentrations of 2.5–15 μM. These data suggest that uncoupling of OXPHOS and the resulting ATP shortage and MPT induction are the key mechanisms for regorafenib induced hepatocyte injury, and AMPK activation and autophagy induction serve as pro-survival pathways against such toxicity. [ABSTRACT FROM AUTHOR]

A synthetic zeolite, commercially available as permutite was tested for removing radiocobalt from aqueous solutions by sorption. The sorption process was studied as a function of contact time, pH, ionic strength and solid content by batch technique. The results revealed that the process is dependent on the pH and ionic strength under ambient conditions. The kinetic sorption was fitted well by a pseudo-second-order rate equation. The thermodynamic parameters (Δ H, Δ S, Δ G) suggested that sorption behavior of Co(II) is a spontaneous and endothermic process. The study shows that permutite has excellent potential for disposal of wastewaters containing radiocobalt. [ABSTRACT FROM AUTHOR]

End effect is a significant phenomenonin a rotating packed bed(RPB). The mass transfer accomplished in the end zone can be one magnitudehigher than what is achieved in the bulk zone of the packing. In orderto make full use of the end effect, a novel multiliquid-inlet rotatingpacked bed (MLI-RPB) was developed, which artificially created theextra end zones in the bulk zone along the radial direction of therotor. The effective interfacial area (a) and liquid-sidevolumetric mass-transfer coefficient (kLa) of the MLI-RPB were measured using a system ofCO2chemisorption into NaOH solution. Mass-transfer experimentswere also conducted in a traditional RPB with the same size as theMLI-RPB. Compared with the traditional RPB, higher values of aand kLawereobtained in the MLI-RPB, showing a great potential for the industrialapplications. [ABSTRACT FROM AUTHOR]

The effects of a small misalignment of the inner rod in a corrugated coaxial-gyrotron on eigenvalue, resonant frequency, and electronic efficiency, and so forth, are presented. As a practical application, with the electronic velocity spread and cavity wall resistivity being taken into account, the beam–wave interaction of a 170 GHz megawatt corrugated coaxial-gyrotron operating with TE 31,12 mode has been investigated. The results show that the eigenvalue increases slightly when the ratio of misalignment to outer radius D/R increases in the case of small ratio of outer to inner radius C= R/R_{\rm {in}} , but is uniform in the case of large ratio of C$ . The electronic efficiency decrease slightly when $D/R$ increases within the range of 0–0.01. If $D/R$ increases to 0.02, the efficiency decreases seriously to only about 5%. For both cold cavity and hot cavity, the resonator frequency increases with $D/R$ increasing. [ABSTRACT FROM AUTHOR]

As the sources of high-power microwave and terahertz, gyrotrons have important development prospects. However, there are many difficulties to be resolved in study and design of gyrotrons meeting requirements. In this paper, the beam-wave interactions of a 170 GHz megawatt-level corrugated coaxial-gyrotron are studied numerically. In order to attain high efficiency and stable radiation, TE 31,12 mode that lies in a relative sparse spectrum is selected as the operating mode and the beam-wave coupling coefficient, and start oscillation current are calculated by a set of source codes. Taking into account electronic velocity spread, and cavity wall resistivity and basing on single-mode approximation, the optimized design and simulation of beam-wave interaction of a 170 GHz MW corrugated coaxial-gyrotron have be fulfilled. The relationships between the efficiency and magnetic field, voltage, current, and parameters of groove are presented. The results show that voltage and magnetic field have great influences on efficiency, but the current and velocity spread do slightly, so reduce the requirements of electronic gun design. In addition, the optimized geometry parameters can improve efficiency, reduce the impact of velocity spread on efficiency, and achieve around 48.6% electronic efficiency and 1.7 MW output power at 5% velocity spread, and 6.896 × 10 −8 Ω m resistivity. [ABSTRACT FROM AUTHOR]

The self-consistent nonlinear analysis and CST 3D particle-in-cell (PIC) simulation of a W-band gyrotron traveling wave tube (gyro-TWT) are presented in this paper. Both the simulation results of the two codes are excellent agreement with each other. The gyro-TWT loaded with periodic lossy dielectric in the circuit for suppressing potential spurious oscillations. It is driven by a 70kV, 10A gyrating electron beam with velocity ratio of 1.0. PIC simulation results are: the maximum peak output power of 198kW, statured gain of 62.3dB and efficiency of 28.3% at 92.5GHz. Only the operating mode TE is observed in the CST 3D simulation and the potential competing backward wave oscillations are effectively suppressed. The CST simulation also predicts that the device works stably under the condition of the beam current lower than 14A and B /B lower than 1.05. The simulated bandwidth with peak power greater than 100kW is 6.8GHz without axial velocity spread, and 4.1GHz with 6% axial velocity spread. [ABSTRACT FROM AUTHOR]