A comparative study of CO adsorption on flat, stepped and kinked Au surfaces using density functional theory

Our ab initio calculations of CO adsorption energies on low miller index (111), (100), stepped (211), and kinked (532) gold surfaces show a strong dependence on local coordination with a reduction in Au atom coordination leading to higher binding energies. We find trends in adsorption energies to be similar to those reported in experiments and calculations for other metal surfaces. The (532) surface provides insights into these trends because of the availability of a large number of kink sites which naturally have the lowest coordination (6). We also find that, for all surfaces, an increase in CO coverage triggers a decrease in the adsorption energy. Changes in the work-function upon CO adsorption, as well as the frequencies of the CO vibrational modes are calculated, and their coverage dependence is reported.Comment: 18 pages, 4 figure

Design of a Uranium Dioxide Spheroidization System

The plasma spheroidization system (PSS) is the first process in the development of tungsten-uranium dioxide (W-UO2) fuel cermets. The PSS process improves particle spherocity and surface morphology for coating by chemical vapor deposition (CVD) process. Angular fully dense particles melt in an argon-hydrogen plasma jet at between 32-36 kW, and become spherical due to surface tension. Surrogate CeO2 powder was used in place of UO2 for system and process parameter development. Particles range in size from 100 - 50 microns in diameter. Student s t-test and hypothesis testing of two proportions statistical methods were applied to characterize and compare the spherocity of pre and post process powders. Particle spherocity was determined by irregularity parameter. Processed powders show great than 800% increase in the number of spherical particles over the stock powder with the mean spherocity only mildly improved. It is recommended that powders be processed two-three times in order to reach the desired spherocity, and that process parameters be optimized for a more narrow particles size range. Keywords: spherocity, spheroidization, plasma, uranium-dioxide, cermet, nuclear, propulsio

Caractérisation hydrogéochimique des eaux souterraines du complexe aquifère Morsott-Laouinet (Région Nord de Tébessa, Sud-Est algérien)

L’analyse des eaux souterraines de l’aquifère superficiel Plio-Quaternaire, pose à nouveau la question de l’importance des faciès gypso-salifères dans la région de Morsott-Laouinet au Nord de Tébessa dans le Sud Est algérien. Ces faciès sont représentés par des affleurements triasiques en surface et par la présence d’un substratum marno-salifère en profondeur. Les analyses chimiques de la totalité des puits de la région le confirment.La salinité des eaux est très variable et généralement élevée. La  conductivité électrique de l’eau oscille entre 1154 μS cm-1 et 23800 μS cm-1 avec une concentration élevée d’amont en aval dans le sens de l’écoulement qui se fait du Sud vers le Nord. Les faciès chimiques extrêmes sont le bicarbonaté calcique et le chloruré sodique avec une prédominance de ce dernier. Les teneurs en chlorures et en sodium pouvant atteindre localement les valeurs respectives de 8145 mg l-1 et 3988 mg L-1. La comparaison de la teneur en chlorures avec le reste des éléments majeurs et le strontium, montre que la salinité des eaux souterraines de la plaine de Morsott-Laouinet possède deux origines possibles : la dissolution-précipitation de la roche aquifère et du substratum et l’échange de base entre le sodium et les éléments qui lui sont semblables.Mots-clés : Trias, aquifère, salinité, saturation, Morsott-Laouinet

Structure, Dynamics and Themodynamics of a metal chiral surface: Cu(532)

The structure, vibrational dynamics and thermodynamics of a chiral surface, Cu(532), has been calculated using a local approach and the harmonic approximation, with interatomic potentials based on the embedded atom method. The relaxation of atomic positions to the optimum configuration results in a complex relaxation pattern with strong contractions in the bond length of atoms near the kink and the step site and an equivalently large expansion near the least under-coordinated surface atoms. The low coordination of the atoms on the surface affects substantially the vibrational dynamics and thermodynamics of this system. The local vibrational density of states show a deviation from the bulk behavior that persist down to the 10th layer resulting in a substantial contribution of the vibrational entropy to the excess free energy amounting to about 90 meV per unit cell at 300K

Understanding the nursing process

Support staff work closely with their patients and members of the multidisciplinary team to deliver high-quality care. Often this care will have been planned by a nurse using ‘the nursing process’. It is therefore important for the support worker to understand how the patient has been assessed and that the care they are providing has been planned. Within this article, the author will be discussing the nursing process, explaining the different stages and how these are used to deliver quality care. Relevant sections of The Code of Conduct for Healthcare Support Workers and Adult Social Care Workers in England (Skills for Care and Skills for Health, 2013) will be highlighted. Support workers have a clear and important role in making sure the nursing process is successful and patients receive the best quality care

Self-healing by Diels-Alder cycloaddition in advanced functional polymers: A review

The ability of artificial materials to be healed efficiently, mimicking the living organisms, exhibits a great deal of potential advantages that can revolutionise the operation and maintenance of materials used in various applications. Such self-healable smart materials have been extensively researched in the last few decades, leading to the development of different physical and chemical synthesis approaches. Among these methods, chemical techniques based on reversible cycloadditions or disulfide bonding provide obvious advantages in terms of repeatability, which holds prime importance in determining the commerciality of the healing approach. This review compiles the recent advances in the field of self-healing polymers where the healing ability is introduced by reversible cycloaddition reactions while focusing mainly on the Diels-Alder (DA) reaction. DA is a [4 + 2] cycloaddition reaction where diene and dienophile pairs are used to fabricate thermally reversible crosslinked networks. These covalent bonds provide the necessary reversibility to the healing matrix and impart the desired strength to the polymeric material. There is a considerable body of recent literature where DA bonding has been employed either on its own or along with other healing mechanisms to impart self-healing to polymers. However, lack of a systematic review discussing these works makes it difficult for a beginner to cope with advancements in this field. Most early studies have focused on the healing stimuli and efficiency of healing in polymers but with this review, we would like to explore the healing thermodynamics governing the rupture–repair process in DA polymers along with the use of advanced spectroscopic techniques to study them and their applicability in thermosets, epoxy resins, biopolymers, and polymer nanocomposites. Novel applications for such advanced functional polymers, multifunctional healable polymers, and the outlook for future research, opportunities and challenges in the area are also discussed

Discrete wavelet transform based freezing of gait detection in Parkinson's disease

Wearable on body sensors have been employed in many applications including ambulatory monitoring and pervasive computing systems. In this work, a wearable assistant has been created for people suffering from Parkinson’s disease (PD), specifically with the Freezing of Gait (FoG) symptom. Wearable accelerometers were placed on the person’s body and used for movement measure. When FoG is detected, a rhythmic audio signal was given from the wearable assistant to motivate the wearer to continue walking. Long term monitoring results in collecting huge amounts of complex raw data; therefore, data analysis becomes impractical or infeasible resulting in the need for data reduction. In the present study, Discrete Wavelet Transform (DWT) has been used to extract the main features inherent in the key movement indicators for FoG detection. The discrimination capacities of these features were assessed using, i) Support Vector Machine (SVM) using a linear kernel function, and ii) Artificial Neural Network (ANN) with a two-layer feed-forward with hidden layer of 20 neurons that trained with conjugate gradient back- propagation. Using these two different machine learning techniques, we were capable of detecting FoG with an accuracy of 87.50% and 93.8%, respectively. Additionally, the comparison between the extracted features from DWT coefficients with those using Fast Fourier Transform (FFT) established accuracies of 93.8% and 81.3%, respectively. Finally, the discriminative features extracted from DWT yield to a robust multidimensional classification model compared to models in the literature based on a single feature. The work presented paves the way for reliable, real-time wearable sensors to aid people with PD