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The wake structure of an incompressible, conducting, viscous fluid past an electrically insulating sphere affected by a transverse magnetic field is investigated numerically over flow regimes including steady and unsteady laminar flows at Reynolds numbers up to 300. For a steady axisymmetric flow affected by a transverse magnetic field, the wake structure is deemed to be a double plane symmetric state. For a periodic flow, unsteady vortex shedding is first suppressed and transitions to a steady plane symmetric state and then to a double plane symmetric pattern. Wake structures in the range
without a magnetic field have a symmetry plane. An angle
exists between the orientation of this symmetry plane and the imposed transverse magnetic field. For a given transverse magnetic field, the final wake structure is found to be independent of the initial flow configuration with a different angle
. However, the orientation of the symmetry plane tends to be perpendicular to the magnetic field, which implies that the transverse magnetic field can control the orientation of the wake structure of a free-moving sphere and change the direction of its horizontal motion by a field–wake–trajectory control mechanism. An interesting ‘reversion phenomenon’ is found, where the wake structure of the sphere at a higher Reynolds number and a certain magnetic interaction parameter (
) corresponds to a lower Reynolds number with a lower
value. Furthermore, the drag coefficient is proportional to
for weak magnetic fields or to
for strong magnetic fields, where the threshold value between these two regimes is approximately
When the Galileo number is below the first bifurcation, the instability and transition of a vertical ascension or the fall of a free sphere affected by a vertical magnetic field are investigated numerically. A compact model is used to explain that the magnetic field can destabilize the fluid–solid system. When the interaction parameter exceeds a critical value, the sphere trajectory is transitioned from a steady vertical trajectory to a steady oblique one. Furthermore, the trajectory will remain vertical at a sufficiently large magnetic field because of a double effect of the magnetic field on the fluid–solid system. Under the influence of an external vertical magnetic field, four wake patterns at the rear of the sphere are found and the physical behaviour of the free sphere is independent of the density ratio. The wake or trajectory of the free sphere is only determined by the Galileo number
and the interaction parameter
. A close relationship between the streamwise vorticity and the sphere motion is found. An interesting ‘agglomeration phenomenon’ is also found, which shows that the vertical velocities are agglomerated into a point for a certain magnetic field regardless of the Galileo number and satisfy a scaling law
. The principal results of the present work are summarized in a map of regimes in the
The wake structure and transition process of an incompressible viscous fluid flow past a sphere affected by an imposed streamwise magnetic field are investigated numerically over flow regimes that include steady and unsteady laminar flows at Reynolds numbers up to 300. For cases without a magnetic field, a subregion with the existence of a limit cycle is found in the range
. The point of division is between
. For cases with a streamwise magnetic field, five wake patterns are the steady axisymmetric wake with an attached separation bubble, the steady plane symmetric wake with a small spiral dismissed, the steady plane symmetric wake with a limit cycle, the steady plane symmetric wake with a small spiral fed by the upstream fluid and the unsteady plane symmetric wake with a wave-like oscillation or vortex shedding. Under the influence of an imposed streamwise magnetic field, the wake will be transitioned to various patterns. An interesting ‘reversion phenomenon’, which describes the topological structure behind a sphere with a higher Reynolds number and a certain interaction parameter which corresponds to a lower Reynolds number case with a certain interaction parameter or a much lower Reynolds number case without a magnetic field, is also found. The principal results of the present work are summarized in a map of regimes in the
This is a case-control study to investigate the prevalence, characteristics, and risk factors of pain in patients with Parkinson's disease (PD).
A total of 200 PD patients from eastern China were enrolled in our study. Accordingly, 200 healthy elderly adults were recruited as controls. The characteristics of pain were collected by using the Visual Analog Scale, Brief Pain Inventory (BPI), SF-36 Bodily Pain Scale, Unified Parkinson's Disease Rating Scale, Hoehn–Yahr Scale (H-Y), Hamilton Depression Scale, and Leeds Assessment of Neuropathic Symptoms and Signs.
Of the 200 PD patients, pain was complained by 106 patients (53%). According to the SF-36 Bodily Pain Scale, pain morbidity in PD patients was significantly higher than in the control group. The average pain during last 24 h measured by the BPI was 2.67. About 76% of PD patients were found to have one pain type, 21.7% were having two pain types, and 1.9% had three pain types. Further, 69.8% of these patients were presented with musculoskeletal pain, 4.7% with dystonic pain, 22.6% with radicular-neuropathic pain, 20.8% with central neuropathic pain, and 9.4% with akathisia pain. The onset age and depression were the most significant predictors of pain in PD patients (p < 0.05). However, there was no significant association between pain and gender, age, disease duration, or severity of the disease. Only 5.7% of PD patients with pain received treatment in this study.
Pain is frequent and disabling, independent of demographic and clinical variables, and is significantly more common in PD patients.
Few studies have explored the relationship between dietary patterns and the risk of gestational diabetes mellitus (GDM). Evidence from non-Western areas is particularly lacking. In the present study, we aimed to examine the associations between dietary patterns and the risk of GDM in a Chinese population. A total of 3063 pregnant Chinese women from an ongoing prospective cohort study were included. Data on dietary intake were collected using a FFQ at 24–27 weeks of gestation. GDM was diagnosed using a 75 g, 2 h oral glucose tolerance test. Dietary patterns were determined by principal components factor analysis. A log-binomial regression model was used to examine the associations between dietary pattern and the risk of GDM. The analysis identified four dietary patterns: vegetable pattern; protein-rich pattern; prudent pattern; sweets and seafood pattern. Multivariate analysis showed that the highest tertile of the vegetable pattern was associated with a decreased risk of GDM (relative risk (RR) 0·79, 95 % CI 0·64, 0·97), compared with the lowest tertile, whereas the highest tertile of the sweets and seafood pattern was associated with an increased risk of GDM (RR 1·23, 95 % CI 1·02, 1·49). No significant association was found for either the protein-rich or the prudent pattern. The protective effect of a high vegetable pattern score was more evident among women who had a family history of diabetes (P for interaction = 0·022). These findings suggest that the vegetable pattern was associated with a decreased risk of GDM, while the sweets and seafood pattern was associated with an increased risk of GDM. These findings may be useful in dietary counselling during pregnancy.
Plant height is important for crop yield improvement. In this study, a dwarf mutant, Gmdwarf1, was screened from a γ-ray-treated soybean population. Compared with the wild type, the mutant exhibited later germination, smaller and darker green leaves, and less-elongated shoots. Genome-wide transcriptome detection through RNA-seq analysis revealed that not only gibberellin-related genes but many other genes involved in hormone biosynthetic pathways were also significantly influenced in the mutant. We presumed that Gmdwarf1 might play essential roles in the plant hormone pathways. Future functional analysis of this dwarf mutant would help us to understand the underlying mechanisms and be beneficial for improving soybean yield.
Trichogrammatoidea bactrae Nagaraja (Hymenoptera: Trichogrammatidae) is an important natural enemy of many species of lepidopterous pests. The effects of heat stress temperature (33, 36, and 39 °C), duration of exposure (2, 4, 6, and 8 h), and developmental stage during exposure (embryo-first instar larvae, second instar larvae, prepupae, and pupae) on the development and reproduction of parasitoid T. bactrae were investigated in the laboratory. When exposed to 39 °C for 8 h during pupal stage, only 19.90% adults emerged from host eggs, and more than 14% were deformed (wings were folded or incomplete). Parasitoid females exposed to 39 °C for 8 h as prepupae only lived for 1.45 days and parasitized about 23.5 host eggs. Moreover, life-table parameters of T. bactrae were also influenced by exposure to heat stress temperatures during each preimaginal developmental stage. Based on these results, we propose that T. bactrae is susceptible to high temperatures, especially at 39 °C. Thus, this parasitoid may be more effectively controlling lepidopterous pests during cooler weather conditions.
This paper presents numerical simulations to study the heating of a solid target under a proton beam pulse interaction. The target is heated by the proton beam pulse with particle energy Eb, intensity N and focal radius rb of transverse Gaussian distribution, with a fixed pulse time 10 ps. The dynamics of target and beam ions are described by a classical hydrodynamic model and the target electrons are described by the quantum hydrodynamic model. Numerical simulations are carried out by employing the two dimensional flux-corrected transport methods. The target is heated to 0.5−5 eV, therefore, warm dense matter is created in the heated target region on a picosecond time scale.
Two-dimensional particle-in-cell simulations are performed to investigate the propagation of low energy continuous ion beams through background plasmas. It is shown that the continuous ion beam can be modulated into periodic short beam pulses by the induced wakefield, which can be adopted as a method to produce ultrashort ion beam pulses. Furthermore, the transport of the continuous ion beam in plasma with density gradient in the beam propagation direction is proposed and an enhanced longitudinal compression by density gradient is found due to the phase lock of ion pulses in the focusing regions of wakefield and reduced heating of plasma electrons.
This paper presents numerical simulations to study the heating of a two-dimensional (2D) solid target under an ion cluster interaction. 2D quantum hydrodynamic (QHD) model is employed for the heating of solid target to warm dense matter on a picosecond time scale. A Gaussian cluster is used to uniformly heat the solid target to a temperature of several eV. The density and temperature of the target are calculated by a full self-consistent treatment of the QHD formalisms and the Poisson's equation. The technique described in this paper provides a method for creating uniformly heated strongly coupled plasma states.
We use a two-dimensional particle-in-cell simulation to investigate the dynamic polarization and stopping power for an ion beam propagating through a two-component plasma, which is simultaneously irradiated by a strong laser pulse. Compared to the laser-free case, we observe a reduction in the instantaneous stopping power that initially follows the shape of the laser pulse and becomes particularly large as the laser frequency approaches the plasma electron frequency. We attribute this large reduction in the ion stopping power to an increase in plasma temperature due to the energy absorbed in the plasma from the laser pulse through the process of wave heating. In addition, dynamic polarization of the plasma by the ion is found to be strongly modulated by the laser field.
Medicago sativa is an excellent pasture legume, but it is very sensitive to aluminium (Al) toxicity. To better understand the mechanism of M. sativa sensitivity to Al, a forward suppression subtractive hybridization (SSH) cDNA library for an Al-sensitive cultivar, M. sativa L. cv. Yumu No. 1 (YM1), under 5 μm Al stress over a 24 h period was constructed to analyse changes in its gene expression in response to Al stress. Sequence analysis for the SSH cDNA library generated 291 high-quantity expression sequence tags (ESTs). Of these, 229 were known as functional ESTs, 137 of which have already been reported as Al response genes, whereas the other 92 were potentially novel Al-associated genes. The up-regulation of known Al resistance-associated genes encoding the transcription factor sensitive to proton rhizotoxicity 1 (STOP1) and malate transporter MsALMT1 (Al-activated malate transporter) as well as genes for antioxidant enzymes was observed. Reverse transcription polymerase chain reaction analysis validated the reliability of the SSH data and confirmed the up-regulated expression of STOP1 and MsALMT1 under 5 μm Al stress. The analysis of physiological changes indicated that hydrogen peroxide (H2O2) and malondialdehyde levels were elevated rapidly under 5 μm Al stress, suggesting that severe oxidative stress occurred in the YM1 roots. The up-regulation of antioxidant-related genes might be an important protective mechanism for YM1 in response to the oxidative stress induced by 5 μm Al toxicity. Al-induced malate exudation was increased drastically during the early period after Al treatment, which might have been due to the up-regulation and function of MsALMT and STOP1. However, malate exudation from the YM1 roots declined quickly during the subsequent period, and a gradual decrease in malate content was simultaneously observed in the YM1 roots. This result is in agreement with the observation that organic acid metabolism-associated enzymes such as phosphoenolpyruvate carboxylase, citrate synthase and malate dehydrogenase were not present in the SSH library. This might be a major reason for the YM1 sensitivity to Al.
Effects of the indent depth, the distance between the indent and the grain boundary, grain sizes, and crystallographic orientations on the microhardness of annealed coarse-grained polycrystalline α-brass were investigated using a Vickers indenter with indents much smaller than the α-brass grains (ranging from 80 μm to 550 μm). It is found that the microhardness of α-brass crystals shows a strong dependence on the indentation depth when it is smaller than 5 μm and a very weak dependence on both the distance between the indent and the grain boundary and the grain size when the indentation depth is about 5 μm and more. No significant dependence of the microhardness on the crystallographic orientations was observed in the fourteen grains of different orientations studied in this investigation.
The existing interpretations of indentation test data (either theoretical or numerical approaches) have been largely based on isotropic plasticity models of polycrystalline materials while most of the metallic thin films widely used in many microelectronic and MEMS applications are strongly textured with a few grains or only a single grain running through the thickness of the films. The multicrystalline nature of the thin films on correlating their indentation and tensile properties is the focus of our investigation. Using multicrystalline aluminum and copper alloy thin sheets as model material systems, both tensile tests and indentation tests were performed and the testing results were compared based on a 3D crystal plasticity finite element analysis. The correlation between the indentation data and the tensile test data (at an effective or equivalent strain) is critically examined for these two multicrystalline materials.
An experimental investigation was carried out to study the crack initiation and growth in a single-edge notched NiTi shape memory alloy sheet under tension. It is observed that a crack initiated at the tip of a V-shape notch before the peak axial load was reached and it grew steadily across the width of the NiTi sheet until final fracture. In-plane crack-tip deformation fields at various stages of the crack growth were measured based on an image correlation technique and the crack-tip opening displacement (CTOD) and crack-tip opening angle (CTOA) were subsequently determined. The fracture surface of the NiTi sheet was dimpled based on scanning electron microscopy examinations.
A novel photochromic complex composed of Keggin-type tungstophosphate acid (PW12) and polyacrylamide (PAM) was prepared. Atomic force microscopy (AFM), thermogravimetric study, Fourier transform infrared spectra (FTIR), ultraviolet–visiblea bsorption spectra (UV-VIS), and electron resonance spectra (ESR) were used to investigate the surface topography, composition, and photochromic behavior and mechanism of the film. Under UV irradiation, the film was reduced photochemically to yield a blue species. AFM images indicated that surface topography of the polymer matrix changed after adding PW12. FTIR results showed that the Keggin geometry of PW12 was still preserved inside the matrix, and a charge-transfer bridge was built between PW12 and PAM by hydrogen bonding. The characteristic signal of W (V) and the formation of a radical signal in ESR spectra indicated that PAM was a hydrogen donor and the photoreduced process was in accordance with the radical mechanism.The diffusion of oxygen in the polymeric network plays an important role in the reversibility of photochromism.
The heterogeneous photocatalytic oxidation of rhodamine B in aqueous solution containing pure or zinc (iron)-doped titania films has been studied. N-deethylation of rhodamine B was accelerated by iron(III) and zinc(II) doping as compared with pure titania film. It is shown that improvement of electron transfer from dye molecules to the film may be responsible for the high N-deethylation rate for iron-doped (0.5 mol%) film, while for zinc-doped (20 mol%) film, high surface roughness may be the main reason. In addition, both iron and zinc doping brought a new shallow trap to the intragap meaning that the surface defects had increased after doping; this is a possible reason doped films present relative low photoreactivity to catalyze the direct degradation of dye molecules.
A series of photochromic sol-gel films are prepared through entrapping tungsten heteropolyoxometallates (PW12O403−, SiW12O404−) and molybdenum heteropolyoxometallate (PMo12O403−) into a kind of inorganic–organic matrix cohydrolyzed from tetraethylorthosilicate and 3-aminopropyltriethoxysilane. The films show reversible photochromicity. Irradiated with ultraviolet light, the transparent films change from colorless to blue. Then, bleaching occurs when the films are in contact with air or O2 in the dark. The Keggin-type polyanions interact with R–NH3+ cations strongly, and thus disperse uniformly in the sol-gel matrix, as proved by Fourier transform infrared spectra and x-ray diffraction. The molybdenum heteropolyoxometallate sol-gel film has higher photochromic efficiency and much slower bleaching than its counterparts of tungsten heteropolyoxometallate. A charge-transfer model which is supported by electron spin resonance and related literature [T. Yamase, Chem. Rev. 98, 307, (1998)] is put forth to explain the above experimental results.
TiO2 nanocrystals were prepared by a photo-assisted sol-gel process in which tetrabutoxide titanate was hydrolyzed in acidic medium under ultraviolet irradiation. X-ray diffraction and Raman spectra showed that the as-prepared TiO2 particles without further annealing were well-crystallized anatase. Such TiO2 particles were easily immobilized on dacron cloth and showed very high photocatalytic activity. In contrast, TiO2 particles were ill crystallized and showed lower activity when no light was introduced under otherwise equal conditions.
Radar, aerial netting and ground sampling were used to study the autumn migration of Nilaparvata lugens (Stål) in Jiangsu Province in east central China. Emigration of macropterous adults increased from late August until late September as the main rice crop matured and was harvested. In early and mid September, the resulting windborne migrations carried the planthoppers mainly towards the west, although the migration directions ranged (within the western sector) from south to north. By late September, however, displacements were predominantly to the south-west on the then prevailing north-east monsoon winds: migration was particularly rapid when the north-easterlies were reinforced by typhoons. Although in late September such movements to more southerly latitudes are essential for the survival of the planthoppers' progeny, we found no definite evidence for preferential emigration on winds blowing towards the south. There were, however, indications that when winds towards the north occurred, the duration of migratory flight was curtailed. Irrespective of any possible preference for migration on northerlies, a large proportion of the N. lugens population would normally be carried in an adaptive southwards direction, because the advent of the north-east monsoon occurs at a time when the number of flight-ready planthoppers approaches its peak.
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