Reverse Gradient Research Articles

Detection of doping peptides and basic drugs in equine urine using liquid chromatography-mass spectrometry.

The abuse of prohibited agents including peptides and basic small-molecule drugs is an area of great concern in horseracing due to their high potential to act as doping agents. These compound classes include agents such as growth hormone-releasing peptides, peptide analgesics, beta-2-adrenergic receptor agonists, and quaternary ammonium drugs that can be challenging to detect and regulate because of their chemical properties and potential rapid elimination following administration. The use of highly sensitive and selective analytical techniques such as liquid chromatography-mass spectrometry (LC-MS) is necessary to provide coverage of these substances and their potential metabolites. This study describes the development and validation of methodology capable of the detection of over 50 different peptide-based doping agents, related secretagogues, quaternary ammonium drugs, and other challenging small molecules in equine urine following solid-phase extraction using a mixed mode weak cation exchange sorbent. Following sample extraction, the compounds were analyzed using LC-MS with chromatographic separation via a reverse phase gradient and detection via selective reaction monitoring following introduction to a triple-stage quadrupole mass spectrometer using positive mode electrospray ionization. Validation parameters including limits of detection and quantitation, accuracy, precision, linear range, recovery, stability, and matrix effects were determined. Briefly, the limits of detection for most compounds were in the sub-ng/mL ranges with adequate precision and accuracy sufficient for an initial testing procedure. Stability studies indicated that most compounds were sufficiently stable to allow for effective screening using conditions commonly utilized in drug testing laboratories.

Integrated transcriptomics and metabolomics analyses provide insights into the mechanisms of capitulum architecture in Argyranthemum frutescens (Asteraceae)

The capitulum is a crucial Asteraceae innovation; however, the molecular mechanisms of its development remain elusive. Here, we performed transcriptome and metabolome analyses to explore the molecular mechanisms underlying floret development of Argyranthemum frutescens, whose capitula produce ray (R), disk (D) and trans (T) florets. Up-regulated differentially expressed genes (DEGs) related to cutin, suberine and wax biosynthesis, fatty acid elongation and lipid accumulation were significantly enriched in T. DEGs in the tryptophan metabolism pathway were up-regulated in R, and DEGs in the abscisic acid synthesis pathway were up-regulated in D. Auxin and abscisic acid occurred as a reverse distribution gradient in the three floret types. TCP, WOX transcription factors and ABCE genes were identified and analyzed. Our results suggest that cutin, suberine and wax biosynthesis regulates the formation of petal cuticle by upregulating the content of lipids in T, thereby improving the reproductive efficiency of A. frutescens. Auxin and abscisic acid co-regulate floret development in a concentration dependent manner in A. frutescens, and expression of flower development genes was strongly correlated with the IAA content. These results enable a comprehensive understanding of the molecular mechanisms of capitulum formation in A. frutescens and increase our understanding of capitulum diversity in Asteraceae.

Pressure-driven electrokinetic energy conversion in conical nanochannels with ion concentration polarization

Electrokinetic energy conversion (EEC) in nanochannels subject to a large pressure gradient (or difference) is affected appreciably by the ion concentration polarization (ICP). The current literature only addresses the ICP effects on EEC in nanochannels with uniform cross-sections, such as cylindrical nanochannels. Here, we adopt a numerical approach which couples the Poisson, Nernst–Planck, and Navier–Stokes equations to perform a detailed analysis of the pressure-driven EEC in nanochannels with varying cross-sections (i.e., conical nanochannels) under the ICP effect. The results reveal that two pressure gradients of the same magnitude but opposite directions can produce regulation effects on the EEC and ICP: under large values of the pressure gradient and surface charge density, a forward pressure gradient (e.g., the pressure gradient driving the fluid flow from the tip to the base of the nanochannel) leads to more nonlinear current-voltage (I-V) curves than a reverse pressure gradient (e.g., the pressure gradient driving the fluid flow from the base to the tip of the nanochannel); however, a forward pressure gradient produces weaker ICP than a reverse pressure gradient. These two opposite regulation behaviors suggest that the nonlinearity of I-V curves and the ICP is negatively interrelated, in contrast to the case of cylindrical nanochannels. Moreover, increasing nanochannel conicity enhances the nonlinearity of I-V curves but weakens the ICP effects, further confirming the negative interrelationship between the ICP and nonlinear I-V curves. This study clarifies the interrelationship between ICP and nonlinear I-V curves and is of practical significance for EEC device design and operation.

Novel yaw effector of a flying wing aircraft based on reverse dual synthetic jets

For achieving the nice stealth performance and aerodynamic maneuverability of a Flying Wing Aircraft (FWA), a novel yaw effector based on Reverse Dual Synthetic Jets (RDSJ) was proposed without the movement of rudders. Effects on aerodynamic characteristics of a small-sweep FWA and control mechanism were investigated by numerical simulations. Finally, reverse dual synthetic jet actuators were integrated into a real FWA and flight tests were firstly carried out. Numerical results show that RDSJ could make drag coefficient increase and weaken lift coefficient, which generate a yawing moment and a rolling moment in the same direction, realizing control of heading attitudes, but strong coupling with the pitching moment occurs at large angles of attack. For control mechanism, RDSJ could produce two reverse synthetic jets out of phases, improve the reverse pressure gradient and hence form alternate recirculation zones or even early large-area separation, which cause the rise of pressures before exits and the dip of pressures behind exits, achieving improvement of drag and the yawing moment. The results of flight tests support that RDSJ could realize control of heading attitudes without deflections of rudders during the cruise stage and achieve the maximal yaw angular velocity of 10.12(°)/s, verifying the feasibility of this novel yaw effector.

The Aerodynamic Interaction Effects between the Rotor and Fuselage on the Drag Performance of a Civil Helicopter in Forward Flight

The aerodynamic interaction between the rotor and fuselage is an important consideration in relation to the drag performance prediction of helicopters. In this paper, based on dynamic patched-grid technology coupled with a three-dimensional N–S equation solver, a numerical study of the aerodynamic interaction effects between the rotor and fuselage on the aerodynamic performance and flow field of the fuselage of a light civil helicopter is carried out under the forward flight condition. The deterioration of the drag performance and the evolution of the flow field structure caused by the rotation of the blades are illustrated. Due to the aerodynamic interaction, the drag of the fuselage is increased by 124.1% while the cycle of drag fluctuation is observed in one full revolution of the rotor with a change in amplitude of ±20%. The comparative results between the rotor-off and rotor-on cases show that the aerodynamic interaction effects between the rotor and fuselage on the drag performance are mainly reflected in the influence of the backward-developing rotor wake on the flow field of the rear part of the fuselage. An additional afterbody vortices system is induced, leading to a large reverse pressure gradient on the rear surface of the helicopter, which contributes to an increase in the pressure drag.

Structural characterization and in silico toxicity prediction of degradation impurities of roxadustat

Roxadustat is the first drug approved for anemia due to chronic kidney disease. Drug degradation profile is very crucial for assessing the quality and safety of the drug substances and their formulations. Forced degradation studies are conducted for quick prediction of drug degradation products. Forced degradation of roxadustat was carried out as per ICH guidelines, and nine degradation products (DPs) were observed. These DPs (DP-1 to DP-9) were separated using the reverse phase HPLC gradient method with an XBridge column (250 mm × 4.6 mm, 5 µm). The mobile phase consisted of 0.1% formic acid (solvent A) and acetonitrile (solvent B) at a flow rate of 1.0 ml/min. The chemical structures of all the DPs were proposed by using LC-Q-TOF/MS. DP-4 and DP-5, the two major degradation impurities, were isolated, and NMR was used to confirm their chemical structures. Based on our experiments, the roxadustat was found stable to thermal degradation in solid state and oxidative conditions. However, it was unstable in acidic, basic, and photolytic conditions. A very remarkable observation was made about DP-4 impurity. DP-4 was generated as a common degradation impurity in alkaline hydrolysis, neutral hydrolysis as well as photolysis conditions. DP-4 has a similar molecular mass to roxadustat but is structurally different. DP-4 is chemically, (1a-methyl-6-oxo-3-phenoxy-1,1a,6,6a-tetrahydroindeno [1,2-b] aziridine-6a-carbonyl) glycine. In silico toxicity study was conducted using Dereck software to gain the best knowledge of the drug and its degradation products towards carcinogenicity, mutagenicity, teratogenicity, and skin sensitivity. A further study using molecular docking confirmed the potential interaction of DPs with proteins responsible for toxicity. DP-4 shows a toxicity alert due to the presence of aziridine moiety.

Improved photocarrier separation in Ga/Fe gradient (Ga, Fe)2O3 thin films

Metal oxides are promising photoanode materials for photoelectrochemical reactions due to their chemical stability and low-cost synthesis. However, their high photocarrier recombination rate limits their commercial applications. One strategy to promote photocarrier separation efficiency in metal oxides is building an inner electric field through band engineering techniques. In this study, a gradient band structure was prepared in (Ga, Fe)2O3 thin films on F:SnO2 (FTO) coated glass substrate by varying the Ga/Fe ratio. The performance of the gradient photoanode was evaluated by measuring its photocatalytic activity with photocurrent. The forward gradient photoanode, with increasing Ga/Fe ratio from bottom substrate to photoanode surface, exhibited a higher photocurrent density (0.44 mA/cm2 at 1.23 V vs reversible hydrogen electrode (RHE) under AM 1.5G illumination) compared to the reverse gradient photoanode with decreasing the Ga/Fe ratio in the same situation. The forward gradient band structure, which facilitates photocarrier separation and transportation, was believed to play a dominant role in improving the photocatalytic performance. This work demonstrates an effective strategy to improve photocarrier separation and photocatalytic performance of metal oxide photocatalysts through band engineering.

Biomimetic Liquid Metal Mechatronic Devices

AbstractPerceiving mechanical stimuli and converting them into bioelectric signals to complete sensing information transmission and computation is a fundamental mechanism for survival and evolution of natural animals. This leads to a variety of intelligent behaviors, such as processing, learning, judgment, feedback, and so on when tackling complex and changeable environmental challenges. Until now, the realization of a bionic system to mimic the above activities has long been an important goal which is mainly based on the integration of distributed functional units, lacking the coordination between functional units and the whole systems. Herein, based on the mechano‐electronic coupling effect of liquid metals and by following the basic principle of perception and transduction of piezo proteins, a biomimetic functional liquid metal mechatronic device is proposed with the switching behavior via establishing the reversible charge gradient. Owing to flexible features of liquid metals, this all‐soft mechatronic device exhibits excellent compliance with the whole system. Based on electrochemical characteristics of liquid metals, the passive intelligent device demonstrates versatile behaviors, such as self‐energy supply, encoding, computation, sensing, information identification, communicating, and controlling functions etc. which can only possibly be achieved by living animals. This work opens a new strategy for developing intelligent mechatronic systems.

Neurogenic timing of the inferior olive subdivisions is related to the olivocerebellar projection topography

The olivocerebellar projection is organized into an intricate topographical connection from the inferior olive (IO) subdivisions to the longitudinally-striped compartments of cerebellar Purkinje Cells (PCs), to play an essential role in cerebellar coordination and learning. However, the central mechanisms for forming topography need to be clarified. IO neurons and PCs are generated during overlapping periods of a few days in embryonic development. Therefore, we examined whether their neurogenic timing is specifically involved in the olivocerebellar topographic projection relationship. First, we mapped neurogenic timing in the entire IO by using the neurogenic-tagging system of neurog2-CreER (G2A) mice and specific labeling of IO neurons with FoxP2. IO subdivisions were classified into three groups depending on their neurogenic timing range. Then, we examined the relationships in the neurogenic-timing gradient between IO neurons and PCs by labeling topographic olivocerebellar projection patterns and PC neurogenic timing. Early, intermediate, and late groups of IO subdivisions projected to late, intermediate, and early groups of the cortical compartments, respectively, except for a few particular areas. The results indicated that the olivocerebellar topographic relationship is essentially arranged according to the reverse neurogenic-timing gradients of the origin and target.

Numerical investigation of aerodynamic characteristics of a flying wing aircraft controlled by reverse dual synthetic jets

In this work, to explore the control potential of reverse dual synthetic jets (RDSJs) in a flying wing aircraft (FWA), reverse dual synthetic jet actuators (RDSJAs) are integrated into a FWA with a hybrid flow mode of rollers and streamers. The aerodynamic characteristics and control mechanism are investigated using numerical simulations. The results show that the aerodynamic loads follow a nonlinear trend, and the overall process can be divided into three stages with an increasing angle of attack (AOA). In the first stage (AOA = 0°–8°), the RDSJs can improve the reverse pressure gradients and form alternate recirculation zones or even a large-area separation. The pressure rises before and falls after the exits, causing an increase in Cd and a drop in CL. The decrease in the leading-edge suction and the pressure envelope area results in a further increase with the increasing AOA, resulting in a reduction in ΔCL and an improvement in ΔCd. In the second stage (AOA = 8°–24°), the energy of the RDSJs is too low to form a strong disturbance over the leeward surface, and the promotion of favorable pressure gradients along the lower surface can weaken the control effects of the RDSJAs, causing a decrease in the narrowing degree of the pressure envelope. The leading-edge vortex (LEV) is weakened, and ΔCL increases as Cd experiences a drop. In the third stage (AOA = 24°–32°), the RDSJs interact with the larger separation and are capable of accelerating the flow over the wing section, elevating the longitudinal velocity of the LEV through entrainments and improving the strength and stability of the LEV. The accelerated flow creates negative pressures behind RDSJAs, causing a further reduction in the decrement of the pressure envelope area. An enhancement of CL and Cd appears under the influence of the above factors.

Experimental study on the combustion process of a kerosene-fueled scramjet with strut injection

The ground combustion test was used to study the effects of kerosene fuel on the start-up ignition and flame stabilization of a scramjet with reverse strut injection. The test analyzed the changes of flow field wave system and flame propagation law under various working conditions after pilot hydrogen was injected into the combustor. The results showed that when hydrogen was injected into the combustor, it started to combust in only 0.0128 s. The heat released by combustion led to the generation of reverse pressure gradient, which made the wave system move forward and concentrate near the backward step. In the case of hydrogen self-ignition, the entire flow field remained stable combustion. At t = 0.07 s, kerosene was gradually injected into scramjet and ignited by pilot flame. The pressure at the monitoring point increased rapidly from 0.064 MPa to 0.135 MPa, and severe combustion occurred in the cavity. The flame began to propagate from the shear layer to the low-speed recirculation zone. Subsequently, the pressure of the monitoring point was reduced to 0.121 MPa, and the combustion flame continuously passed from the cavity downstream. When the hydrogen was removed, the pressure was reduced to 0.09 MPa, and the flame in the cavity was relatively weakened. However, the rapid ignition condition of kerosene could still be achieved, and the combustion flame continued to generate. After fuel began to be gradually removed, kerosene could not maintain continuous flame combustion due to the reduction of injection volume. The combustor changed between ignition and flameout, showing periodic oscillation with a period of 4.8 ms.

Large eddy simulation of shock wave/turbulent boundary layer interaction under incipient and fully separated conditions

Large eddy simulations of shock wave/turbulent boundary layer interaction on a compression ramp at the Mach number M a ∞ = 5 and Reynolds number R e ∞ = 14 000 are performed to investigate the impact of the incipient and fully separated conditions on the development of the flow field. The quasi-dynamic subgrid-scale kinetic energy equation model, which combines the benefits of the gradient model with the eddy-viscosity model, has been applied. Compared with the previous experimental and numerical results, the simulation was validated. The flow structures, turbulence properties, vortex structures, and low-frequency unsteadiness are all investigated. The flow field of the incipient separation is attached and rarely impacted by shock. An evident separation bubble and localized high wall temperatures in fully separated flow are caused by the separation shock's significant reverse pressure gradient. The Reynolds stress components exhibit significant amplification in both cases, and the peak outward shifts from the near-wall region to the center of the free shear layer. Turbulent kinetic energy terms were analyzed, and the two scenarios show a significant difference. The power spectral density of the wall pressure fluctuations shows that the low-frequency motion of the incipient separation is not apparent relative to the fully separated flow.

Analysis of variations in annual energy production based on types of suction side erosion at the blade tip of a wind turbine using numerical simulation

ABSTRACT Wind turbine blades are prone to damage by airborne particulate matter; hence, periodic blade inspection is necessary for maintenance. However, quantitative data on wind turbine performance reduction due to erosion are lacking. Herein, erosion conditions were classified into four levels based on the erosion area in long-term operated wind turbine blades. Transient three-dimensional computational fluid dynamics analysis was performed by applying the suction side erosion shape to the tip airfoil of the National Renewable Energy Laboratory’s 5 MW blade. In the early stage, irregular erosion of the airfoil’s leading edge resulted in the development of a reverse pressure gradient inside the boundary layer and a larger recirculation area of the trailing edge. Thus, the lift coefficient of the airfoil decreased by up to 30%, whereas the drag coefficient increased by over 100%. The wind turbine output curve calculated using aeroelastic software showed that the worst erosion condition decreased output by 2.54%. Annual energy production had declined by up to 2% based on the annual average wind speed; therefore, immediately repairing erosion can minimize the loss of energy production.

Control mechanism of a vortex control baffle for the horseshoe vortex around the sail of a DARPA SUBOFF model

The horseshoe vortex generated in the attached part of a submarine could aggravate the vibration and noise of the submarine. The control mechanism of a vortex control baffle for the horseshoe vortex around the sail of a DARPA SUBOFF model is explored by the large eddy simulation (LES) model in this work. The variations of the distributions for streamwise vorticity, Q criterion and pressures are analyzed deeply. It is found that the arrangement of the vortex control baffle can interfere with the development process of horseshoe vortex. Due to the presence of the baffle, a strong reverse pressure gradient around the baffle would take place. Then a series of vortices are generated to weaken the intensity of the horseshoe vortex in the process of propagation and achieve the purpose of controlling the horseshoe vortex. The development characteristics of these vortices are discussed in detail. It is noted that the new induced vortex and the horseshoe vortex have opposite propagation direction, which would lead to the gradually decreasing intensity of the horseshoe vortex in the development process.

Coinfection rates of avian blood parasites increase with latitude in parapatric host species.

Animals are frequently coinfected with multiple parasites concurrently, and advances in our sampling of these complex intra-host parasite communities have revealed important ecological impacts on their hosts. However, the spatial distributions and environmental determinants of parasite coinfection remain infrequently studied. Here, we investigated the drivers of haemosporidian blood parasite coinfection in the Bicknell's thrush (Catharus bicknelli) and grey-cheeked thrush (Catharus minimus), parapatric sister species that occur across a broad latitudinal range in northern North America. Using 298 samples from across the distributions of these species, we found high overall infection (86%) and coinfection (41%) rates within host populations. Coinfection rates within populations were highly variable across sampling sites, ranging from 7 to 75%. Latitude was a more important predictor of coinfection frequency than host species identity, with coinfections becoming more abundant at higher latitudes. The 2 host species exhibited similar parasite faunas, and an analysis of the co-occurrence patterns among haemosporidians showed that host species identity was largely not a factor in structuring which parasites were found within coinfections. To our knowledge, this is the first study to illustrate a reverse latitudinal gradient in coinfection frequency in a eukaryotic parasite system. Further work is necessary to determine whether vector ecology or some other factor is the primary proximate driver of this pattern.

Visual Assessment of Factors Affecting Reverse Pressure Gradients in Liners Using a Simulated Milking Device

Highlights In a simulated milking device, liner internal diameter, pulsation setting, and vent location all affect backflow. Junction point internal diameter affects backflow more than other factors. Vent location has no effect on backflow if the liner internal diameter is large. Backflow is strong with simultaneous pulsation, regardless of other factors. Abstract. The backflow of milk resulting from reverse pressure gradients in liners can cause mastitis. In this study, we hypothesized that liner internal diameter, vent location, and pulsation setting can induce backflow. We therefore attempted to clarify the mechanism of backflow using a flow simulated device. We visually analyzed the effects on backflow of the liner junction point (JP) (i.e., the border from the liner to the short milk tube), the liner inlet point (IP) (i.e., a distance of 63 mm from the end of the short milk tube), vent location, and pulsation setting, using high-speed video recordings of water flow in clear silicone liners at seven flow rates (1.0, 1.5, 2.0, 2.5, 3.0, 3.5, and 4.0 kg min-1/quarter). The actual flow rate was approximately half of the flow meter set value due to the effect of the pulsation closing phase (C+D phase) on quarter level. The results showed that the degree of backflow in liners increased considerably with an increase in flow rate and a decrease in liner internal diameter. The degree of backflow was affected considerably more by JP internal diameter than by IP internal diameter, pulsation setting, or vent location. The degree of backflow was not affected significantly by short milk tube vents and mouthpiece vents when JP internal diameter was larger. However, the degree of backflow was very strong when simultaneous pulsation was used, even at low flow rates. The findings showed that the JP internal diameter should be >13.0 mm, IP internal diameter should be >11.0 mm, the pulsation rate should be 60 pulses/min, and the pulsation ratio should be 60:40 when the alternative pulsation setting is used. This information might be useful for preventing intramammary gland infection. Keywords: Liner internal diameter, Pulsation setting, Reverse pressure gradients, Simulated milking device, Vent location.

Electrical Impedance Tomography Image Reconstruction With Attention-Based Deep Convolutional Neural Network

Electrical impedance tomography (EIT) is a promising functional and structural imaging method in process tomography. However, due to the ’soft-field’ nature and the high dependence on the prior information, it often suffers serious artifacts in quantitative analysis. Most recently, EIT image quality has improved significantly because of the state-of-the-art deep learning-based models in the aspect of solving the inverse problem, especially fully convolutional networks (FCN) and V-Net variants. Despite their success, these deep convolutional networks (CNNs) have two limitations: (1) The long-range information transition is frequently lost and the reverse gradient often disappears in deep CNNs; (2) Some novel skip connections, such as residual and dense connections, often occupy substantial computational resources. To overcome these two limitations, we propose V <sup xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">2</sup> A-Net, a new neural architecture based on redesigned feature transited connections by the terms of (1) A pre-reconstructor based on the iterative Newton-Raphson method, which maps the nonlinear function between the measurements and the initial images, (2) Dual cascaded V-Net are combined, which play the role of an encoder and a decoder, respectively, (3) A new parallel attention mechanism via channel attention and coordinate attention to learn the conductivity distributions and boundary-shaped feature separately, and (4) the light-weight skip connections reduce the computational resources (or accelerate the inference speed) of EIT imaging. The V <sup xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">2</sup> A-Net is evaluated by using the multi-phase flow industrial applications, and the results demonstrate that (1) V <sup xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">2</sup> A-Net has better performance in shape reconstruction with sharp ’corner’, (2) V <sup xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">2</sup> A-Net could reconstruct the model accurately where it has some low-contrast conductivity distributions, (3) V <sup xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">2</sup> A-Net enhances the quality of interfaces with the stratified flow, and (4) the pruned V <sup xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">2</sup> A-Net achieves significant speedup compared with the VDD-Net or V <sup xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">2</sup> DNet. The analyses show that the average relative error is 0.05, the average correlation coefficient is 0.92, the average structural similarity is 0.92 on the testing datasets. In addition, the average relative cover ratio is 0.97 and the average relative contrast ratio is 0.98 on the testing datasets.

National trends in incidence and geographic distribution of melanoma and keratinocyte carcinoma in the Russian Federation.

Keratinocyte Carcinomas (KC), including basal cell and cutaneous squamous cell carcinomas, are the most common skin cancers in Fitzpatrick phototype I-III individuals, while melanoma is one of the deadliest skin cancer types. The incidence of both melanoma and KC is increasing in Russia. KCs' incidence increases from north-to-south across the Russian Federation. In contrast, while melanoma's incidence increases from north-to-south in the eastern part of the country, in the west of Russia a reverse latitude gradient trend is noted, where northern more affluent regions of Russia display higher rates of melanoma than the southern jurisdictions. Furthermore, our detailed analysis of incidence by jurisdiction highlights that affluent northern capital cities have higher rates of melanoma than the surrounding regions. The observed melanoma incidence trends in the western portion of Russia are similar to the findings in the western Europe and opposite of the findings in Canada.

Foliar water uptake improves branch water potential and photosynthetic capacity in Calligonum mongolicum

Atmospheric water is among the most important water sources for plants in arid ecosystems and plays an important role in facilitating drought stress survival in plants. However, little is known about the specific physiological benefits of foliar water uptake (FWU) for woody plants inhabiting arid desert areas. The objective of this study was to explore the physiological responses of Calligonum mongolicum to atmospheric water uptake by the assimilating branches, with a special focus on the FWU effect on shoot water status and photosynthesis. To this end, the canopies of natural C. mongolicum plants in a desert region of northwestern China were humidified in a field in-situ misting experiment and a long-term wetting experiment, during which physiological measurements of plant water relations and photosynthetic capacity were performed, alongside the observation of FWU by H218O isotopic tracing. Following the in-situ misting experiment, the water potential of the assimilating branches was significantly higher than that of the secondary branches at midnight, suggesting that FWU resulted in a reverse water potential gradient in C. mongolicum at the branch level. The 18O isotope was markedly enriched in the assimilating branches, secondary branches, and trunk xylem following the foliar uptake of 18O labeled water, indicating that the water uptake from the atmosphere by the assimilating branches could replenish the stem. The relative water content and water potential of the assimilating branches were significantly increased by FWU. The net photosynthetic rate, stomatal conductance, and maximum photochemical efficiency of C. mongolicum plants were markedly increased following the wetting treatment. Our results clearly show that C. mongolicum is capable of FWU, and that the absorbed water could be transported downward through the xylem and improve the branch water status and photosynthetic capacity. These findings provide a new perspective for deepening our understanding of the drought survival mechanism of plants in arid environments.

Influences of trailing-edge synthetic jets on longitudinal aerodynamic characteristics of a flying wing aircraft

For realizing the nice aerodynamic maneuverability of flying wing aircrafts (FWAs), a longitudinal aerodynamic control technology based on circulation control (CC) using trailing-edge synthetic jet actuators was proposed. Influences on longitudinal characteristics of a FWA were investigated. Results show that synthetic jets could improve the lift, drag, and nose-down moment, having potential of flight control at entire area of attack of angles (AOAs). Cl increment dips and then rises with the growth of AOAs, reaching the minimum at AOA of 12°. The maximum percentage of Cl enhancement and ΔCl/Cμ is separately 64.5% and 50.74%, respectively. Before 12°, synthetic jets could narrow the area of “dead zone,” improve flow velocities along the upper surface, and then move the trailing-edge separation point and the leading-edge (LE) stagnation point downward, enhancing the circulation. Moreover, synthetic jets grow rapidly through entrainment of the local flow, leading to the improvement of valid camber and, hence, the increase in Cl. CC efficiency decreases with the augmentation of AOAs, and leading-edge vortex (LEV) is weakened, causing the drop of Cl increment. After 12°, synthetic jets could enhance the longitudinal velocity of LEV and reduce the swirling number, improving the strength and stability of LEV, which results in larger suction near the leading edge. Moreover, the strengthened LEV could promote flow mixing and then weaken reverse pressure gradients along the wing section, thus improving flow velocities and CC efficiency at the wing section. It is above two factors that make Cl increment rise after 12°.