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Global climate change and freshwater scarcity have become two major environmental issues that constrain the sustainable development of the world economy. Climate warming caused by increasing atmospheric CO2 concentration can change global/regional rainfall patterns, leading to uneven global seasonal precipitation distribution and frequent regional extreme drought events, resulting in a drastic reduction of available water resources during the critical crop reproduction period, thus causing many important food-producing regions to face severe water deficiency problems. Understanding the potential processes and mechanisms of crops in response to elevated CO2 concentration and temperature under soil water deficiency may further shed lights on the potential risks of climate change on the primary productivity and grain yield of agriculture. We examined the effects of elevated CO2 concentration (e[CO2]) and temperature (experimental warming) on plant biomass and leaf area, stomatal morphology and distribution, leaf gas exchange and mesophyll anatomy, rubisco activity and gene expression level of winter wheat grown at soil water deficiency with environmental growth chambers. We found that e[CO2] × water × warming sharply reduced plant biomass by 57% and leaf photosynthesis (Pn) 50%, although elevated [CO2] could alleviated the stress from water × warming at the amount of gene expression in RbcL3 (128%) and RbcS2 (215%). At ambient [CO2], the combined stress of warming and water deficiency resulted in a significant decrease in biomass (52%), leaf area (50%), Pn (71%), and Gs (90%) of winter wheat. Furthermore, the total nonstructural carbohydrates were accumulated 10% and 27% and increased Rd by 127% and 99% when subjected to water × warming and e[CO2] × water × warming. These results suggest that water × warming may cause irreversible damage in winter wheat and thus the effect of “CO2 fertilization effect” may be overestimated by the current process-based ecological model.

Objectives: Candidemia has become one of the leading causes of healthcare-associated bloodstream infection, particularly in the intensive care unit. The management of candidemia remains challenging. We reassessed the protective effectiveness of a comprehensive care bundle on the management of candidemia and the effects of compliance with each element on the outcomes of patients. Methods: This network meta-analysis was conducted using the frequentist method. The participants included adult patients both infected with candidemia and who received bundle care. The primary outcome was the all-cause mortality among the patients included. Results: Studies in which a care bundle was created for patients with candidemia were identified, and 5 eligible studies with 5,808 participants were enrolled for further analysis. The random-effects model of the overall odds ratio (OR) revealed a significant reduction in the risk of all-cause mortality compared with that of the controls (OR, 0.599; 95% CI, 0.378–0.949; P = .025), as well as a reduction in the risk of developing persistent candidemia compared with the controls (OR, 0.483; 95% CI, 0.245–0.952; P = .008). In addition, no single element reached a protective effectiveness to improve the clinical outcome. Conclusions: This meta-analysis demonstrated that the combination of core elements in the care bundle resulted in protective effects, in that the all-cause mortality rates and incidence rates were effectively reduced among patients with persistent candidemia.

The radial oscillation of an intense relativistic electron beam possesses two main features of the spatial period and the radial oscillation amplitude in a low-magnetic-field foil-less diode, and the large radial oscillation extremely limits the beam–wave conversion efficiency and stability of a high-power microwave device. Thus, the formation mechanism of the radial oscillation is analyzed in detail. The results show that the radial oscillation of an electron beam consists of a great number of electrons with different Larmor radii and guiding centers, and the large radial oscillation is mainly caused by the strong radial electric field and the directional difference between the electric field and the magnetic field in the anode–cathode gap. A low diode voltage or a proper large anode radius is beneficial to improve the beam quality. Considering that cathode plasmas have a dominant effect on the spatial distribution of electrons, the explosive emission model was improved with cathode plasmas, and the consistency between simulation and experimental results becomes better.

The emission uniformity of an annular knife-edged cathode in a coaxial diode with a focusing electrode and operating in a low macro electric field has been investigated. It was found that the emission uniformity deteriorated as the cathode width increased from 0.5 mm to 2.0 mm. To improve the emission uniformity, a grooved graphite cathode was prepared by a laser micro-etching treatment. Experimental results demonstrated that the emission threshold for the grooved cathode may be reduced and thus the delay in explosive emission can be decreased. Visual inspection of photographs of the cathode plasmas operating under different guiding magnetic fields (GMFs) was used to confirm improvements in emission uniformity. Even under a low GMF of 0.21 T, good emission uniformity was realized.

A klystron-like relativistic backward-wave oscillator (KL-RBWO) with transverse electron beam confinement and waveguide reflection, which works well under a magnetic-field strength below that of the cyclotron resonance, is proposed. For this device operating with a low magnetic field, effective suppression of the transverse velocity of electron beams is introduced by a local electric field near the tube head, to promote modulation uniformity of electron beams. Part of the reflected microwave from the output waveguide provides feedback enhancement to the extractor, which strengthens the local standing-wave field. Owing to a stronger electric field that can interact with the electron beam in the extractor and a higher growth of fundamental harmonic current, the efficiency of the KL-RBWO is increased to 40% when guided by a magnetic field of 0.32 T, compared with that of 30% using conventional structures.

In order to systematically study the stress correction method and hot deformation behavior of F92 stainless steel, the hot compression test was performed using a Gleeble-3500 (DSI USA, Connecticut, CT, USA) at strain rates of 0.01–10 s−1 and deformation temperatures of 750–1150 °C. First, to obtain the truest stress values from the original data, we adopted two stress correction models that did not affect each other, and the order of the two correction models was also different. Second, the adiabatic-friction-corrected stress was used as the input value of the AR model to predict the high-temperature flow behavior of F92 steel. Third, the optimal hot working parameters of F92 steel were determined via modeling and microstructure characterization. The results were as follows: The final correction values for both models were smaller than those from the original data. The stress deviation corrected by model 1 reached a maximum value of 59 MPa at 750 °C and 10 s−1. After establishing the Arrhenius (AR) model, it was determined that the accuracy of stress correction model 2 was stronger than that of model 1. Additionally, the corrected stress improved the predictive power of the AR model. The hot working range of F92 steel falls within a deformation temperature of 850 °C to 1050 °C and strain rate of 0.1 s−1 to 1 s−1. Finally, the AR model was used to describe the high-temperature flow behavior of F92 steel.

The fabrication method of grooves on the surface of alumina and their influence on the surface flashover characteristics of the alumina insulator were studied in this paper. To prepare grooves with a regular surface structure, the UV laser was applied to carve grooves on the surface of alumina ceramic, and dilute hydrochloric acid was used to corrode and remove the residual materials produced in the laser carving process. By adjusting the laser parameters, periodic grooves were prepared on the surface of a cylindrical alumina insulator with a groove depth of 60 µm and a groove width of approximately 50 µm on the laser spinning carving platform. Then, alumina insulators with different periods were prepared, and their vacuum surface flashover voltages were tested on a short pulsed high-voltage test platform. The test results indicated that the flashover voltages of the alumina insulators with laser carved periodic grooves were increased over 200%, and the improvement did not change much with the groove periods. A further study of the groove parameters showed that several grooves fabricated on the cathode end of the insulators were able to improve the flashover voltage of the alumina insulator to the voltage-withstand level of the fully grooved insulators.

We found that the electron drift length, L1, between a diode area and a resonant reflector in a relativistic backward wave oscillator operating at a low guiding magnetic field has a periodical influence on device power, which is a special characteristic due to periodical transverse motions of electron beams. In this paper, electron motion characteristics under both TM02 and TM01 fields are investigated using single-particle simulation, and the result shows that the condition of beam expansion is dependent on the beam state that spatially meets the TM02 standing-wave field. A larger beam expansion will lead to a larger axial energy spread in the modulation area, which is unfavorable for efficient beam-wave interaction. Furthermore, rapid transverse expansion of electron beams can be observed under a TM01 travelling-wave field, which is the main cause for the obvious decline in the current collected by the collector as the output power reaches saturation.

A novel coaxial relativistic Cerenkov generator (CRCG) operating in quasi-transverse electromagnetic mode is proposed for generating Ku-band high-power microwave radiation. It is found that using a cathode with a shielding electrode can decrease the diffusing electric field in the diode, thereby allowing a CRCG with the proposed diode structure to operate in a low guiding magnetic field. Taking advantage of the two-sectional slow wave structure, the output power and conversion efficiency are improved. Furthermore, a simple optimization rule is proposed for the length of the drift cavity and is verified by numerical simulation. In a particle-in-cell simulation, when the diode voltage and beam current are 550 kV and 4.2 kA, respectively, the microwave with an output power of 1 GW at 15.3 GHz is achieved in a guiding magnetic field of 0.35 T, yielding a conversion efficiency of 43%.

In this paper, we study an X-band klystron-like relativistic backward wave oscillator (RBWO) with a pre-modulation cavity, modulation ridge, drift tube in the slow wave structure (SWS) and extraction cavity in both theoretical and experiment. PIC simulations show that the conversion efficiency can be up to 62% with output power of 3.0 GW. In experiment, when the diode voltage is 660 kV, and the diode current is 6.4 kA, the output power is 1.9 GW, and the conversion efficiency is 45%(±5%). And we find that the conversion efficiency mainly suffers from the breakdown in the extraction cavity and the plasma from the cylindrical collector. To suppress the breakdown and plasma effect, the breakdown electric field threshold in RF structures(especially in the extraction cavity) had better be larger than 700 kV/cm. Moreover, the distance between the position where the electrons are collected and the end of extraction cavity should be larger than 20 mm in case of the cylindrical collector.

Gentamicin (GM) was discovered in 1963 and was introduced into parenteral usage in 1971. Since then, GM has been widely used in medicinal applications. The Food and Drug Administration of the United States approved the routine prescription of GM to treat the following infectious disorders: infection due to Klebsiella pneumoniae, Escherichia coli, Serratia marcescens, Citrobacter spp., Enterobacteriaceae spp., Pseudomonas spp.; Staphylococcus infectious disease; bacterial meningitis; bacterial sepsis of newborns; bacterial septicemia; infection of the eye, bone, skin and/or subcutaneous tissue; infective endocarditis; peritoneal dialysis–associated peritonitis due to Pseudomonas and other gram-negative organisms; peritonitis due to gastrointestinal tract infections; respiratory tract infections; and urinary tract infectious disease. GM is an old antibiotic and is used widely beyond its FDA-labeled indications as follows: actinomycotic infection; Staphylococcus saprophyticus bacteremia with pyelonephritis; appendicitis; cystic fibrosis; diverticulitis; adjunct regimen for febrile neutropenia; female genital infection; uterine infection; postnatal infection; necrotizing enterocolitis in fetus or newborn; osteomyelitis; pelvic inflammatory disease; plague; gonorrhea; tularemia; prophylaxis of post-cholecystectomy infection, transrectal prostate biopsy, and post–tympanostomy-related infection; malignant otitis externa; and intratympanically or transtympanically for Ménière's disease. GM is also used in combination regimens, such as with beta-lactam antibiotics to treat mixed infection and with bacteriophage to treat Staphylococcus aureus infections. It is also added to medical materials, such as GM-loaded cement spacers for osteomyelitis and prosthetic joint–associated infections. Overall, there are many medicinal applications for GM. To reduce the development of GM-resistant bacteria and to maintain its effectiveness, GM should be used only to treat or prevent infections that are proven or strongly suspected as being caused by susceptible bacteria. In the future, we believe that GM will be used more widely in combination therapy and applied to medical materials for clinical applications. A definitive, appropriately powered study of this antibiotic and its clinical applications is now required, especially in terms of its effectiveness, safety, and cost.

This paper presents an approach that greatly enhances both the output power and the conversion efficiency of the coaxial relativistic backward wave oscillator (CRBWO) by using coaxial dual annular cathodes, which increases the diode current rather than the diode voltage. The reasons for the maladjustment of CRBWO under a high diode voltage are analyzed theoretically. It is found that by optimization of the diode structure, the shielding effect of the space charge of the outer beams on the inner cathode can be alleviated effectively and dual annular beams with the same kinetic energy can be explosively emitted in parallel. The coaxial reflector can enhance the conversion efficiency by improving the premodulation of the beams. The electron dump on the inner conductor ensures that the electron beams continue to provide kinetic energy to the microwave output until they vanish. Particle-in-cell (PIC) simulation results show that generation can be enhanced up to an output power level of 3.63 GW and conversion efficiency of 45% at 8.97 GHz under a diode voltage of 659 kV and current of 12.27 kA. The conversion efficiency remains above 40% and the output frequency variation is less than 100 MHz over a voltage range of more than 150 kV. Also, the application of the coaxial dual annular cathodes means that the diode impedance is matched to that of the transmission line of the accelerators. This impedance matching can effectively eliminate power reflection at the diode, and thus increase the energy efficiency of the entire system.

Virtual reality (VR) technology can promote sustainable consumption and pro-environmental behaviour. However, few studies have examined the psychological mechanisms that promote sustainable purchase intention from the perspective of VR education. Based on the self-determined motivation theory and VR attributes, this study proposes and empirically examines the underlying mechanism of VR customer knowledge education on sustainable purchase intention. The results show that VR customer knowledge education has a positive effect on customers’ sustainable product knowledge levels, and subsequently, on sustainable purchase intention through the two mediators of knowledge richness and usefulness. Additionally, customers’ intrinsic (versus extrinsic) learning motivation leads to a higher sustainable knowledge enhancement effect. Nonetheless, this effect is moderated by customers’ prior sustainable knowledge; customers with low (versus high) prior sustainable knowledge are more susceptible to the effects of VR customer knowledge education. [ABSTRACT FROM AUTHOR]

Global climate change and freshwater scarcity have become two major environmental issues that constrain the sustainable development of the world economy. Climate warming caused by increasing atmospheric CO2 concentration can change global/regional rainfall patterns, leading to uneven global seasonal precipitation distribution and frequent regional extreme drought events, resulting in a drastic reduction of available water resources during the critical crop reproduction period, thus causing many important food-producing regions to face severe water deficiency problems. Understanding the potential processes and mechanisms of crops in response to elevated CO2 concentration and temperature under soil water deficiency may further shed lights on the potential risks of climate change on the primary productivity and grain yield of agriculture. We examined the effects of elevated CO2 concentration (e[CO2]) and temperature (experimental warming) on plant biomass and leaf area, stomatal morphology and distribution, leaf gas exchange and mesophyll anatomy, rubisco activity and gene expression level of winter wheat grown at soil water deficiency with environmental growth chambers. We found that e[CO2] x water x warming sharply reduced plant biomass by 57% and leaf photosynthesis (Pn) 50%, although elevated [CO2] could alleviated the stress from water x warming at the amount of gene expression in RbcL3 (128%) and RbcS2 (215%). At ambient [CO2], the combined stress of warming and water deficiency resulted in a significant decrease in biomass (52%), leaf area (50%), Pn (71%), and Gs (90%) of winter wheat. Furthermore, the total nonstructural carbohydrates were accumulated 10% and 27% and increased Rd by 127% and 99% when subjected to water x warming and e[CO2] x water x warming. These results suggest that water x warming may cause irreversible damage in winter wheat and thus the effect of "CO2 fertilization effect" may be overestimated by the current process-based ecological model. [ABSTRACT FROM AUTHOR]

As one of the potential high-power microwave devices on the level of gigawatts, relativistic klystron amplifier (RKA) can be used for power combination to further improve the radiation microwave power. Because of self-excited oscillation of the intense relativistic electron beam, the frequency and phase characteristics of general relativistic klystron devices are independent with the driven microwave pulse. In order to obtain frequency and phase locking, a method of improving the input power is put forward to inhibit these parasitic oscillations. This paper reports a particle-in-cell simulation study of the RKA's characteristics under the condition of strong power feeding. By making use of the 500-keV 6-kA electron beam, the simulation results show that strong input power can inhibit the parasitical oscillations in cavity and modulate the beam very well with only one cavity. About 5.4-kA modulation current and a microwave with power of 1.4 GW, bandwidth of 5%, and efficiency of 50% are obtained. The new amplifier driven by the strong input power proves to be a potential device to attain high amplitude stability, high efficiency, high spectral purity, wide bandwidth, and low level of phase and amplitude noise. Index Terms--High-power microwave (HPM), particle-in-cell (PIC) simulation, phase locking, relativistic klystron.

The linear and nonlinear theory of a plasma-filled relativistic Cerenkov generator with coaxial slow-wave structure (SWS) is developed. Linear analysis includes the space-charge limiting current, dispersion relations, dispersion curves, and coupling impedance. In nonlinear theory, the electron beam space-charge effect, nonsynchronous interaction, and complex reflection coefficients of the electromagnetic wave at the boundaries of the SWS are taken into account. With the assumption of quasi steady state, the self-consistent equations are numerically calculated using the fourth-order Runga-Kutta method. The effects of the relative phase between inner and outer corrugations, phase and amplitude of the complex reflection coefficient at the boundaries of the SWS, and plasma density on device efficiency are discussed. Efficiencies of up to 37% without plasma and about 50% with plasma density of [n.sub.p] = 3-7 x [10.sup.11] [cm.sup.- 3] are obtained. Index Terms--Cerenkov radiation, coaxial slow-wave structure (SWS), dispersion curves, high-power microwave (HPM), nonlinear theory, plasma fill.