Surface Reconstruction,Oxidation Mechanism,and Stability of Cd3As2

Cadmium arsenide (Cd₃As₂) has recently attracted considerable interest for the presence of 3D massless Dirac fermions with ultrahigh mobility and magnetoresistance. However, its surface properties are currently largely unexplored both theoretically and experimentally, due to the very large unit cell and the challenging growth of single‐crystal samples, respectively. Here, by combining ab initio calculations with surface‐science spectroscopic experiments, the presence of a surface reconstruction is unveiled in centimeter‐scale (112)‐oriented Cd₃As₂ single‐crystal foils produced by the self‐selecting vapor growth. Outermost Cd atoms descend into the As‐sublayer with a subsequent self‐passivation of the dangling bonds with As atoms, forming the triangle lattice previously imaged by scanning tunneling microscopy. Moreover, the oxidation mechanism of this reconstructed surface, dominated by the formation of As? O? Cd bonds, is revealed. Interestingly, it is found that the band structure of the reconstructed surface of Cd₃As₂ is quite robust against surface oxidation. Both computational and experimental findings point to a successful exploitation in technology of Cd₃As₂ single crystals.     

KIND‐DAMA: A modular middleware for Kinect‐like device data management

In the last decades, we have witnessed a growing interest toward touchless gestural user interfaces. Among other reasons, this is due to the large availability of different low‐cost gesture acquisition hardware (the so‐called “Kinect‐like devices”). As a consequence, there is a growing need for solutions that allow to easily integrate such devices within actual systems. In this paper, we present KIND‐DAMA, an open and modular middleware that helps in the development of interactive applications based on gestural input. We first review the existing middlewares for gestural data management. Then, we describe the proposed architecture and compare its features against the existing similar solutions we found in the literature. Finally, we present a set of studies and use cases that show the effectiveness of our proposal in some possible real‐world scenarios.     

Chemical modification and structural rearrangements of polyketone‐based polymer membrane

Alternating polyketones constitute a very interesting class of polymers, which can be modified for the preparation of functional polymers. The chemical modification of polyketone using 1,2‐diaminopropane was used to prepare a conductive membrane. This paper is focused on the synthesis and structural rearrangements of polyamine for preparing anion‐exchange membranes by the solvent casting technique. According to the Paal‐Knorr mechanism, 1,4‐dicarbonyl of polyketone reacts with 1,2‐diaminopropane to form a pyrrole ring along the polyketone backbone. In addition, the so‐modified polyamines can undergo structural rearrangements to form N‐substituted pyrrole crosslinked with dihydropyridine units. The conversion degree and the N content are quite low. The pathway reactions have been proposed on the basis of ¹H‐NMR, ultraviolet–visible, and Fourier transform infrared results. Scanning electron microscopy, differential scanning calorimetry, and X‐ray diffraction techniques were used to study the morphological, thermal, and structural characteristics of the modified polyketone, as well as the correspondoing membrane. The experimental results indicated that the membrane is a potential candidate for energy conversion technology. © 2017 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2017 , 134, 45485.     

Influence of precuring on high pressure steam hydration of tricalcium silicate

Samples of C₃s, hydrated at room temperature for 0, 2, 4, 8 and 24 hours, were steam cured at 130, 160 and 190°C for 5, 15 and 24 hours, in order to assess the influence of preliminary curing on autoclave hydration. The room temperature curing duration affects the autoclave hydration of C₃S, mainly at low temperatures. The types and relative amounts of the obtained products are also markedly affected by the preliminary treatment.     

Secondary nanoparticle emissions during diesel particulate trap regeneration

Two nanostructured mixed oxide catalysts (the CoCr₂O₄ spinel and the LiCrO₂ delafossite) have been recently developed for diesel soot combustion. The catalysts have been deposited via in situ combustion synthesis over SiC wallflow trap by CTI (Salindres, F). Bench tests proved that, after soot loading, both the developed traps enable a faster and more complete regeneration at 550 °C than the non-catalysed trap. However, a specific study on the particles distribution after the SiC trap, carried out via SMPS analysis, showed that secondary nanoparticles (<20 nm) are emitted during the regeneration promoted by the highly-active CoCr₂O₄ catalytic trap, as opposed to the LiCrO₂-catalysed and the virgin counter parts. This phenomenon has been investigated vs. the regeneration temperature and some sampling conditions so as to draw preliminary indications on the nature of these undesired particles.     

Low pressure steam hydration of tricalcium silicate

Pastes of C₃S (w/c ratio = 0.5) were steam cured at 25, 40, 60 and 90°C for 1 hour to 30 days. The results obtained have shown that, as the curing temperature rises, the induction period is shortened and the initial rate of hydration of C₃S is increased; at longer curings, on the other hand, such hydration rate is considerably lowered. In order to explain the influence of temperature on the hydration reaction a new hypothesis has been proposed, which takes into account the C/S molar ratio as well as the surface properties of the hydrated silicate.     

Dual representation of spatial rational Pythagorean-hodograph curves

In this paper, the dual representation of spatial parametric curves and its properties are studied. In particular, rational curves have a polynomial dual representation, which turns out to be both theoretically and computationally appropriate to tackle the main goal of the paper: spatial rational Pythagorean-hodograph curves (PH curves). The dual representation of a rational PH curve is generated here by a quaternion polynomial which defines the Euler–Rodrigues frame of a curve. Conditions which imply low degree dual form representation are considered in detail. In particular, a linear quaternion polynomial leads to cubic or reparameterized cubic polynomial PH curves. A quadratic quaternion polynomial generates a wider class of rational PH curves, and perhaps the most useful is the ten-parameter family of cubic rational PH curves, determined here in the closed form.     

Cs–V catalysts for the combustion of diesel particulate

Topics in Catalysis - The soot combustion process, promoted by some promising diesel particulate combustion catalysts based on Cs and V oxides (Cs2O, Cs3VO4, Cs4V2O7, Cs2O · V2O5, CsVO3,...     

CA-based self-organizing environments

The term Ambient Intelligence (AmI) refers to electronic environments that are sensitive and responsive to the presence of people; in this paper, an example of AmI system whose goal is to enhance the experience of pedestrians moving inside the related physical environment will be presented. The environment is endowed with a set of sensors (to perceive humans or other physical entities such as dogs, bicycles, etc.), interacting with a set of actuators (lights). The model for the interaction and action of sensors and actuators is a dissipative multilayered cellular automata, supporting a self-organization of the system as a response to the presence and movements of people inside it. The paper will introduce the model, as well as the results of simulations of its application in a concrete case study.     

Graphical method to select vegetable oils as potential feedstock for biodiesel production

Chemical compositions of 80 vegetable oils were collected from literature and the properties of the obtainable biodiesel (methyl esters) have been predicted by empirical relationships. The purpose has been to check the viability of predicting if a biodiesel could meet the EN 14214 standards knowing only the fatty acid profile (FAP) of the parent oil. Two parameters were used in this investigation: (i) average number of carbon atoms in the fatty acid chains, (ii) average number of double bonds (C?C) per molecule. Two new empirical relationships have been proposed to predict the viscosity and the cetane number of biodiesel from the two parameters. The range of values of the two parameters leading to biodiesel meeting the EN 14214 standard for viscosity, cetane number, iodine value, and cold filter plugging point have been graphically obtained by overlapping the corresponding level surfaces. Practical applications: This work provides biodiesel producers with indications of the quality of biodiesel without the need for analytical testing of the product (indeed, of the product itself). Only the fatty acid profile of the starting vegetable oil is required. The quality of biodiesel can be estimated by using a chart developed in this work, allowing to estimate, e.g. if the biodiesel meets the European standards. The work can be useful to rapidly screen oil seed crops in studies of genetic engineering that require high throughput.