Formation of Aluminum-Doped Zinc Oxide Nanocrystals via the Benzylamine Route at Low Reaction Kinetics

The influence of essential process parameters on the adjustability of specific process and particulate properties of aluminum‐doped zinc oxide (AZO) nanocrystals during synthesis via the benzylamine route at low reaction kinetics is demonstrated by enabling time‐resolved access of the selected measurement technique. It is shown that the validity of the pseudo‐first‐order process kinetics could be extended to the minimum operable reaction kinetics. On the other hand, the impacts of the process temperature and the initial precursor concentration on both the process kinetics and the particle morphology are discussed. The obtained data provide a versatile tool for precise process control by adjusting defined application‐specific particle properties of AZO during synthesis

Microwave photon-mediated interactions between semiconductor qubits

The realization of a coherent interface between distant charge or spin qubits in semiconductor quantum dots is an open challenge for quantum information processing. Here we demonstrate both resonant and non-resonant photon-mediated coherent interactions between double quantum dot charge qubits separated by several tens of micrometers. We present clear spectroscopic evidence of the collective enhancement of the resonant coupling of two qubits. With both qubits detuned from the resonator we observe exchange coupling between the qubits mediated by virtual photons. In both instances pronounced bright and dark states governed by the symmetry of the qubit-field interaction are found. Our observations are in excellent quantitative agreement with master-equation simulations. The extracted two-qubit coupling strengths significantly exceed the linewidths of the combined resonator-qubit system. This indicates that this approach is viable for creating photon-mediated two-qubit gates in quantum dot based systems.Comment: 14 pages, 10 figures and 6 table

Adapting TDMA arbitration for measurement-based probabilistic timing analysis

Critical Real-Time Embedded Systems require functional and timing validation to prove that they will perform their functionalities correctly and in time. For timing validation, a bound to the Worst-Case Execution Time (WCET) for each task is derived and passed as an input to the scheduling algorithm to ensure that tasks execute timely. Bounds to WCET can be derived with deterministic timing analysis (DTA) and probabilistic timing analysis (PTA), each of which relies upon certain predictability properties coming from the hardware/software platform beneath. In particular, specific hardware designs are needed for both DTA and PTA, which challenges their adoption by hardware vendors. This paper makes a step towards reconciling the hardware needs of DTA and PTA timing analyses to increase the likelihood of those hardware designs to be adopted by hardware vendors. In particular, we show how Time Division Multiple Access (TDMA), which has been regarded as one of the main DTA-compliant arbitration policies, can be used in the context of PTA and, in particular, of the industrially-friendly Measurement-Based PTA (MBPTA). We show how the execution time measurements taken as input for MBPTA need to be padded to obtain reliable and tight WCET estimates on top of TDMA-arbitrated hardware resources with no further hardware support. Our results show that TDMA delivers tighter WCET estimates than MBPTA-friendly arbitration policies, whereas MBPTA-friendly policies provide higher average performance. Thus, the best policy to choose depends on the particular needs of the end user.The research leading to these results has been funded by the EU FP7 under grant agreement no. 611085 (PROXIMA) and 287519 (parMERASA). This work has also been partially supported by the Spanish Ministry of Economy and Competitiveness (MINECO) under grant TIN2015-65316-P and the HiPEAC Network of Excellence. Miloˇs Pani´c is funded by the Spanish Ministry of Education under the FPU grant FPU12/05966. Jaume Abella has been partially supported by the MINECO under Ramon y Cajal postdoctoral fellowship number RYC-2013-14717.Peer ReviewedPostprint (author's final draft

Competitive Adsorption of H2O and SO2 on Catalytic Platinum Surfaces: a Density Functional Theory Study

Platinum has been widely used as the catalyst of choice for the production of hydrogen in the hybrid sulphur (HyS) cycle. In this cycle, water (H2O) and  sulphur dioxide (SO2) react to form sulphuric acid and hydrogen. However, the surface reactivity of platinum towards H2O and SO2 is not yet fully  understood, especially considering the competitive adsorption that may occur on the surface. In this study, we have carried out density functional theory  calculations with long-range dispersion corrections [DFT-D3-(BJ)] to investigate the competitive effect of both H2O and SO2 on the Pt (001), (011) and (111)  surfaces. Comparing the adsorption of a single H2O molecule on the various Pt surfaces, it was found that the lowest adsorption energy (Eads =  –1.758 eV) was obtained for the dissociative adsorption of H2O on the (001) surface, followed by the molecular adsorption on the (011) surface (Eads =  –0.699 eV) and (111) surface (Eads = –0.464 eV). For the molecular SO2 adsorption, the trend was similar, with the lowest adsorption energy (Eads = –2.471  eV) obtained on the (001) surface, followed by the (011) surface (Eads = –2.390 eV) and (111) surface (Eads = –1.852 eV). During competitive adsorption by  H2O and SO2, the SO2 molecule will therefore preferentially adsorb onto the Pt surface. If the concentration of SO2 increases, self-reaction between two  neighbouring SO2 molecules may occur, leading to the formation of sulphur monoxide (SO) and -trioxide (SO3) on the surface, which could lead to  sulphur poisoning of the Pt catalytic surfac

A DFT study of Ruthenium fcc nano-dots: size-dependent induced magnetic moments

Many areas of electronics, engineering and manufacturing rely on ferromagnetic materials, including iron, nickel and cobalt. Very few other materials have an innate magnetic moment rather than induced magnetic properties, which are more common. However, in a previous study of ruthenium nanoparticles, the smallest nano-dots showed significant magnetic moments. Furthermore, ruthenium nanoparticles with a face-centred cubic (fcc) packing structure exhibit high catalytic activity towards several reactions and such catalysts are of special interest for the electrocatalytic production of hydrogen. Previous calculations have shown that the energy per atom resembles that of the bulk energy per atom when the surface-to-bulk ratio < 1, but in its smallest form, nano-dots exhibit a range of other properties. Therefore, in this study, we have carried out calculations based on the density functional theory (DFT) with long-range dispersion corrections DFT-D3 and DFT-D3-(BJ) to systematically investigate the magnetic moments of two different morphologies and various sizes of Ru nano-dots in the fcc phase. To confirm the results obtained by the plane-wave DFT methodologies, additional atom-centred DFT calculations were carried out on the smallest nano-dots to establish accurate spin-splitting energetics. Surprisingly, we found that in most cases, the high spin electronic structures had the most favourable energies and were hence the most stable

Creating and maintaining a commercially viable executive coaching practice in South Africa

Background: The executive coaching industry is growing internationally and in South Africa. As is typical of small businesses, many struggle to survive. Factors contributing to small business success have been researched, but research in the context of the executive coaching industry in South Africa is sparse. Aim: The aim of this study was to investigate the factors that contribute to creating and maintaining a commercially viable executive coaching practice by examining executive coaching businesses through the lens of a standard business model template consisting of value network, value architecture, value proposition and value finance dimensions. Method: A qualitative methodology was followed to gather data from executive coaches in South Africa. Data from two focus groups (eight participants) and four semi-structured interviews were analysed using deductive content analysis to ascertain the nature of executive coaching practices in terms of a standard business model template. Results: The most significant factors contributing to a successful executive coaching business include forming alliances, leveraging previous experience, employing multiple income streams and evolving as business owner. Significant factors that present challenges include the lack of a business strategy, finding clients and underestimating earnings potential. These findings could assist aspiring and established executive coaches to plan and structure their coaching business. Executive coach training providers could incorporate these findings into their curricula to prepare new coaches for the realities of running a coaching business. Conclusion: Empirical evidence of factors that contribute to successful executive coaching businesses may help guide coaches to a more realistic view of the profession, in the process contributing to the maturing of the growing executive coaching industry in South Africa

Observational Constraints on Interstellar Grain Alignment

We present new multicolor photo-polarimetry of stars behind the Southern Coalsack. Analyzed together with multiband polarization data from the literature, probing the Chamaeleon I, Musca, rho Opiuchus, R CrA and Taurus clouds, we show that the wavelength of maximum polarization (lambda_max) is linearly correlated with the radiation environment of the grains. Using Far-Infrared emission data, we show that the large scatter seen in previous studies of lambda_max as a function of A_V is primarily due to line of sight effects causing some A_V measurements to not be a good tracer of the extinction (radiation field strength) seen by the grains being probed. The derived slopes in lambda_max vs. A_V, for the individual clouds, are consistent with a common value, while the zero intercepts scale with the average values of the ratios of total-to-selective extinction (R_V) for the individual clouds. Within each cloud we do not find direct correlations between lambda_max and R_V. The positive slope in consistent with recent developments in theory and indicating alignment driven by the radiation field. The present data cannot conclusively differentiate between direct radiative torques and alignment driven by H_2 formation. However, the small values of lambda_max(A_V=0), seen in several clouds, suggest a role for the latter, at least at the cloud surfaces. The scatter in the lambda_max vs. A_V relation is found to be associated with the characteristics of the embedded Young Stellar Objects (YSO) in the clouds. We propose that this is partially due to locally increased plasma damping of the grain rotation caused by X-rays from the YSOs.Comment: Accepted for publication in the Astrophysical Journa