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Zinc Oxide (ZnO) has been shown to exhibit semiconducting and piezoelectric dual properties. This has led to a large commercial demand on ZnO for optoelectronics that operate at the blue-ultraviolet regions. Consequently, varying techniques have been devised to create different nanostructures of ZnO. Here, the single step synthesis of ZnO nanostructures was performed on Si(100) substrates with a thin ZnO seed-layer. A modified chemical vapor deposition (CVD) method was developed to accomplish the structure formation. Sb doping of the structures in the gas phase was performed to study its effects on structure and optoelectronic properties. Different structures were realized including nanofilaments, nanoparticles, microflowers, nanorods, nanotubes, and nanocolumns. Only nanorods/columns, and nanotubes are shown in this work. Morphology was examined using scanning electron microscopy (SEM). Energy-dispersive X-ray spectroscopy (EDS) and X-ray powder diffraction (XRD) were used for structural studies. Optoelectronic properties were explored using room-temperature photoluminescence (PL) spectroscopy. PL data show the relative decrease in the number of defects and increase in crystal quality upon increasing reaction time. Significant structural effects were also observed upon doping. Some structural defects might be attributed to the diffusion of Sb ions into the lattices of ZnO, replacement of Zn by Sb, and ionic radii difference. These stacking faults are most likely the reason behind the dominance and broadening of DLE peak.
Presenting a field-defining overview of one of the most appliable linguistic theories available today, this Handbook surveys the key issues in the study of systemic functional linguistics (SFL), covering an impressive range of theoretical perspectives. Written by some of the world's foremost SFL scholars, including M. A. K. Halliday, the founder of SFL theory, the handbook covers topics ranging from the theory behind the model, discourse analysis within SFL, applied SFL, to SFL in relation to other subfields of linguistics such as intonation, typology, clinical linguistics and education. Chapters include discussion on the possible future directions in which research might be conducted and issues that can be further investigated and resolved. Readers will be inspired to pursue the challenges raised within the volume, both theoretically and practically.
The objective of this research was to evaluate producers’ perspectives of four key precision agriculture technologies (variable rate fertilizer application, precision soil sampling, guidance and autosteer, and yield monitoring) in terms of the benefits they provide to their farms (increased yield, reduced production costs, and increased convenience) using a best-worst scaling choice experiment. Results indicate that farmers’ perceptions of the benefits derived from various precision agriculture technologies are heterogeneous. To better understand farmers’ adoption decisions, or lack thereof, it is important to first understand their perceptions of the benefits precision agriculture technologies provide.
This paper studies the transition to three-dimensional flow in the wake of a cylinder immersed in a free stream, where the cylinder is externally forced to continuously rotate about its axis and to linearly oscillate in the streamwise direction. Floquet stability analysis is used to assess the stability of the nominal two-dimensional flows at a Reynolds number
and rotation rate
to three-dimensional perturbations, as a function of the amplitude and frequency of the linear oscillations. Two modes of instability are found, distinguished by their spatial structure, temporal behaviour and apparent mechanism. The first mode has a shorter wavelength in the spanwise direction and appears to be linked to a centrifugal instability in the layer of fluid near the rotating body. The second mode has a longer wavelength and is linked to an instability of the vortex cores in the wake that is subharmonic, leading to a period doubling. Either mode can be stable while the other is unstable, depending primarily on the frequency of the oscillation of the cylinder. This indicates that either mode can control the transition to a three-dimensional flow. The results are compared to the fully three-dimensional simulation results of a rotating cylinder elastically mounted and free to oscillate in the streamwise direction from Bourguet & Lo Jacono (J. Fluid Mech., vol. 781, 2015, pp. 127–165), and appear to be able to explain the surprising switching of the observed spanwise wavelength in that flow as a change in the dominant mode, and therefore mechanism, of instability.
Many studies have identified changes in the brain associated with obsessive–compulsive disorder (OCD), but few have examined the relationship between genetic determinants of OCD and brain variation.
We present the first genome-wide investigation of overlapping genetic risk for OCD and genetic influences on subcortical brain structures.
Using single nucleotide polymorphism effect concordance analysis, we measured genetic overlap between the first genome-wide association study (GWAS) of OCD (1465 participants with OCD, 5557 controls) and recent GWASs of eight subcortical brain volumes (13 171 participants).
We found evidence of significant positive concordance between OCD risk variants and variants associated with greater nucleus accumbens and putamen volumes. When conditioning OCD risk variants on brain volume, variants influencing putamen, amygdala and thalamus volumes were associated with risk for OCD.
These results are consistent with current OCD neurocircuitry models. Further evidence will clarify the relationship between putamen volume and OCD risk, and the roles of the detected variants in this disorder.
Declaration of interest
The authors have declared that no competing interests exist.
Studies examining productive syntax have used varying elicitation methods and have tended to focus on either young children or adolescents/adults, so we lack an account of syntactic development throughout middle childhood. We describe here the results of an analysis of clause complexity in narratives produced by 354 speakers aged from four years to adulthood using the Expressive, Receptive, and Recall of Narrative Instrument (ERRNI). We show that the number of clauses per utterance increased steadily through this age range. However, the distribution of clause types depended on which of two stories was narrated, even though both stories were designed to have a similar story structure. In addition, clausal complexity was remarkably similar regardless of whether the speaker described a narrative from pictures, or whether the same narrative was recalled from memory. Finally, our findings with the youngest children showed that the task of generating a narrative from pictures may underestimate syntactic competence in those aged below five years.
The idea that the churches became agents of empire through their missionary activity is very popular, but it is too simple. Established Churches, such as those of England and Scotland, could certainly be used by government, usually willingly; so could the Roman Catholic Church in the empires of other countries. But the position of the smaller churches, usually with no settler community behind them, was different. This study examines the effects of the Chilembwe Rising of 1915 on the British Churches of Christ mission in Nyasaland (modern Malawi). What is empire? The Colonial Office and the local administration might view a situation in different ways. Their decisions could thus divide native Christians from the UK, and even cause division in the UK church itself, as well as strengthening divisions on the mission field between different churches. Thus, even in the churches, imperial actions could foster the African desire for independence of empire.