•8% Ag/ZnO has a positive displacement of 590 mV compared with floral ZnO when the current density is 2.5 mA/cm2 for ORR.•Citric acid is effective in controlling the morphology of zinc ...oxide.•Flower-like zinc oxide with good dispersion was successfully synthesized.
ZnO is one of the third generation semiconductors and has excellent photoelectric properties. In the paper, floral ZnO and Ag/ZnO were synthesized by hydrothermal method. The effect of sample morphology and silver doping was studied on catalytic performance. X-ray diffraction (XRD) results show that the synthesized ZnO and Ag/ZnO are of pure and high crystallinity. 8% Ag/ZnO has the best catalytic activity for oxygen reduction reaction (ORR) and has a positive displacement of 590 mV compared with floral ZnO when the current density is 2.5 mA/cm2.
ABSTRACT
In our work, we analyse 5 × 104 single pulses from the recycled pulsar PSR J2222−0137 in one of its scintillation maxima observed by the Five-hundred-meter Aperture Spherical radio Telescope ...(FAST). PSR J2222−0137 is one of the nearest and best studies of binary pulsars and a unique laboratory for testing gravitational theories. We report single pulses’ energy distribution and polarization from the pulsar’s main-pulse region. The single-pulse energy follows the lognormal distribution. We resolve a steep polarization swing, but at the current time resolution ($64\ \mu {\rm s}$), we find no evidence for the orthogonal jump in the main-pulse region, as has been suspected. We find a potential sub-pulse drifting period of $P_{3} \sim 3.5 P$. We analyse the jitter noise from different integrated numbers of pulses and find that its σj is $270\pm {9}\ {\rm ns}$ for 1-h integration at 1.25 GHz. This result is useful for optimizing future timing campaigns with FAST or other radio telescopes.
Abstract Parkinson's disease (PD) is a progressive neurological disorder that is often associated with various gastrointestinal (GI) symptoms. The link between the alteration of dopaminergic system ...and the symptoms of the GI tract in PD is complicated. To determine the changes in the dopaminergic system in the GI tract in PD, two kinds of rodent PD models were used in the present study. One was 6-hydroxydopamine (6-OHDA) -treated rats in which 6-OHDA was microinjected in the bilateral substantia nigra (SN). The other was 1-methyl-4-phenyl-1,2,3,6-tetrahydropyridine (MPTP) -treated mice in which MPTP was injected intraperitoneally. Immunofluorescence, reverse transcription (RT)-real time polymerase chain reaction (PCR) and Western blot were used to evaluate and compare the levels of mRNA and protein expression of tyrosine hydroxylase (TH) and dopamine transporter (DAT) in the GI tract between normal and rodent PD models, as well as between 6-OHDA-treated rats and MPTP-treated mice. The results indicated that TH- and DAT-positive cells were widely distributed in the GI tract. There were significant differences in TH and DAT expression in the GI tract between normal and PD models, as well as between 6-OHDA-treated rats and MPTP-treated mice. The protein levels of TH and DAT in the GI tract were significantly increased in 6-OHDA-treated rats, but the protein level of TH was significantly decreased in MPTP-treated mice. In addition, there was visible atrophy of gastric epithelial parietal cells in MPTP-treated mice, although the protein level of DAT was not significantly changed. The different alterations of dopaminergic system in the GI tract of the two kinds of PD models might underline the differences in GI symptoms in PD patients and might be correlated with the disease severity and disease process affecting the GI tract.
Newly qualified radiographers often find working in the operating theatre (OT) challenging and intimidating. These perceptions, which inhibit confidence, may hinder their effectiveness in ...interprofessional teamwork, which may in turn adversely affect patient outcomes. A collaborative education programme was designed, building upon the foundations of competency-based education (CBE) and simulation-based mastery learning (SBML) to examine its potential in mitigating these perceptions. The objective of this research was to assess participants’ experience and level of competency after attending the curated collaborative educational programme.
The programme was developed based on the Analysis, Design, Development, Implementation, and Evaluation (ADDIE) model and comprises two teaching and learning phases: educational session and simulation. A collaborative approach was undertaken to develop an assessment checklist for the interprofessional simulation. Requirements for the simulation, such as scenario design, information and storyboard, task trainer, logistics, and learners' briefing, debrief, and feedback, were identified and assembled. The radiographers’ performance was recorded using a practical skills assessment checklist and a theory assessment.
Twelve radiographers participated and showed improvement in their self-rating of learning objectives before and after the programme. The median (interquartile range) score achieved in the theory assessment, out of a possible of 11, was 9.00 (7.75–9.50). The median (interquartile range) score achieved in the simulation component, out of a possible of 16, was 15.00 (14.00–15.00). There was statistically significant difference in self-perceived performance in all learning objective domains.
The findings from the programme were promising. The use of simulation and an assessment checklist proved to be useful learning tools in preparing newly qualified radiographers for work in the OT.
Assessment checklists are valuable tools that should be considered to facilitate teaching and learning. The use of interprofessional simulation activities can support radiographers in developing knowledge, professional skills, and clinical competency. It should be conducted in a timely manner to facilitate the introduction to role understanding and effective communication.
To explore the associations between picky eating behaviour and pre-schoolers' growth and development. Corresponding potential mechanisms, such as nutrient and food subgroup intake, as well as ...micronutrients in the blood, will be considered.
Picky eating behaviour was present if it was reported by parents. From various areas of China, 937 healthy children of 3-7 years old were recruited using a multi-stage stratified cluster sampling method. Children and their mothers' socio-demographic information and children's anthropometry, intelligence, blood samples, one 24-hour dietary intake record and food frequency questionnaire were collected. Z-scores and intelligence tests were used to evaluate growth and development (cognitive development). Multilevel models were employed to verify the associations between picky eating behaviour and growth and development.
The prevalence of picky eating as reported by parents was 54% in pre-schoolers. Compared with the non-picky eaters, weight for age in picky eaters was 0.14 z-score (95% CI: -0.25, -0.02; p = 0.017) lower while no significant difference was found in intelligence (p > 0.05). Picky eating behaviour lasting over two years was associated with lower weight for age, as was nit-picking meat (the prevalence from parents' perception was 23% in picky eaters) (p < 0.05). Picky eaters consumed fewer cereals, vegetables, and fish (p < 0.05), and had a lower dietary intake of protein, dietary fibre, iron, and zinc (p < 0.05). There were no differences in the concentrations of essential minerals in whole blood (p > 0.05).
Picky eating behaviour is reported by parents in half of the Chinese pre-schoolers, which is negatively associated with growth (weight for age). Lower protein and dietary fibre as well as lower iron and zinc intakes were associated with picky eating as were lower intakes of vegetables, fish and cereals.
Celotno besedilo
Dostopno za:
DOBA, IZUM, KILJ, NUK, PILJ, PNG, SAZU, SIK, UILJ, UKNU, UL, UM, UPUK
Abstract
We report on the pulse-to-pulse energy distribution and longitude-resolved modulation properties of PSR J1631+1252 discovered by the Five-hundred-meter Aperture Spherical radio Telescope. ...Our analysis made use of the data acquired at 1250 MHz from the follow-up timing observations that lasted over a year. PSR J1631+1252 has a rotational period of ∼0.310 s, and a dispersion measure of ∼32.73 pc cm
−3
. The energy distribution is well described by a lognormal distribution, the parameters of which do not vary with time. We show that large modulation occurs across the bridge emission of the pulse profile, with sporadic bright bursts at the leading emission region. The fluctuation spectral analysis reveals the existence of subpulse drifting in the leading component with vertical spacing between the drift bands of 3.28 ± 0.08 pulse periods between consecutive drift bands. Possible physical mechanisms for subpulse drifting are discussed.
A micro scale Timoshenko beam is developed for the piezoelectricity with flexoelectricity and surface effects. By virtue of the variational principle and Hamilton’s principle, the governing equations ...and related boundary conditions are obtained. As the shear strain is involved for the Timoshenko beam, the flexoelectric effect induced by the shear strain gradient is considered to make the new model more general. Based on this new Timoshenko beam model, the static bending and free vibration problems of a simply supported piezoelectric nanobeam with uniform load applied are solved respectively. The numerical results reveal that both the flexoelectricity and surface effects have remarkable influence on the deformations of the beam. Only flexoelectricity considered may cause a big difference between the theoretical prediction and the experiment results. The shear strain gradient also has considerable effect on the electromechanical response of static bending problem. Moreover, the change of surface properties not only directly affects the static bending but also significantly changes the natural frequency of the beam. This study provides a guideline for the analysis of piezoelectric nanobeam, and also is helpful to understand how the material characteristics affect the electromechanical response of nanobeam.
This study explores the impact of spring subsurface soil temperature (SUBT) anomaly in the western U.S. on North American summer precipitation, mainly southeastern U.S., and possible mechanisms using ...a regional climate Eta model and a general circulation model (GCM). The GCM produces the lateral boundary condition (LBC) for the Eta model. Two initial SUBT conditions (one cold and another warm) on May 1st were assigned for the GCM runs and the corresponding Eta runs. The results suggest that antecedent May 1st warm initial SUBT in the western U.S. contributes positive June precipitation over the southern U.S. and less precipitation to the north, consistent with the observed anomalies between a year with a warm spring and a year with a cold spring in the western U.S. The anomalous cyclone induced by the surface heating due to SUBT anomaly propagated eastward through Rossby waves in westerly mean flow. In addition, the steering flow also contributed to the dissipation of perturbation in the northeastern U.S. and its enhancement in southeastern U.S. However, these results were obtained only when the Eta model run was driven by the corresponding GCM run. When the same reanalysis data were applied for both (cold and warm initial SUBT) Eta runs' LBCs, the precipitation anomalies could not be properly produced, indicating the intimate dependence of the regional climate sensitivity downscaling on the imposed global climate forcing, especially when the impact was through wave propagation in the large‐scale atmospheric flow.
Key Points
Spring subsurface soil temperature in western U.S. contributes to June rain
Anomalous cyclone induced by subsurface heating propagates through Rossby wave
Eta model run must be driven by corresponding GCM run
Abstract
We report on the variation in the single-pulse emission from PSR J1900+4221 (CRAFTS 19C10) observed at frequency centered at 1.25 GHz using the Five-hundred-meter Aperture Spherical radio ...Telescope. The integrated pulse profile shows two distinct components, referred to here as the leading and trailing components, with the latter component also containing a third weak component. The single-pulse sequence reveals different emissions demonstrating as nulling, regular, and bright pulses, each with a particular abundance and duration distribution. There also exists pulses that follow a log-normal distribution suggesting the possibility of another emission, in which the pulsar is radiating weakly. Changes in the profile shape are seen across different emissions. We examine the emission variations in the leading and trailing components collectively and separately, and find moderate correlation between the two components. The inclination angle is estimated to be about 7° based on pulse-width, and we discuss that nulling in this pulsar does not seem to show correlation with age and rotation period.
Rapid and non-destructive assessment of water status is essential to enhance crop performance. This study aimed to evaluate photosynthetic performance and to monitor water status in cotton under ...field conditions. A two-year experiment was conducted with three irrigation regimes to measure the following parameters: photochemical reflectance index (PRI), structural independent pigment index (SIPI), water index (WI), solar-induced fluorescence (SIF; retrieved from reflectance by using Fraunhofer line-depth method), gas exchange, and chlorophyll fluorescence (CF). The results showed that PRI decreased > 30 % in moderate drought (MD) and >50 % in severe drought (SD), compared with control. PRI was found to be positively correlated with net photosynthetic rate (P
N
), stomatal conductance, transpiration rate, actual quantum yield of photosystem II photochemistry (Φ
PSII
), but a negatively correlated with nonphotochemical quenching (NPQ). Solar-induced fluorescence around 761 nm (SIF
761
) had significant correlations with P
N
, Φ
PSII
, and NPQ, but not with maximal quantum yield of PS II photochemistry (F
v
/F
m
). The relationship between PRI and P
N
was stronger at the beginning of water stress (
R
2
= 0.86) than for the all stress stages (
R
2
= 0.54), indicating that PRI could be more effective for assessing P
N
of cotton at early water stress. PRI was better correlated with relative water content and photosynthetic parameters than SIPI and WI and so it could also be a good indicator to evaluate cotton water status.
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