Standard vapour mixtures by means of a multi-capillary flow-proportioner

A dynamic method is described for the preparation of standard gaseous mixtures of condensable vapours such as water vapour, gas odorants or hydrocarbons with an accuracy of better than ·5%. The possible concentration range is from a few parts per miliion to saturation level. The method is also suitable for the preparation of multi-vapour mixtures.     

Tailoring the atomic structure of graphene nanoribbons by scanning tunnelling microscope lithography

The practical realization of nanoscale electronics faces two major challenges: the precise engineering of the building blocks and their assembly into functional circuits. In spite of the exceptional electronic properties of carbon nanotubes, only basic demonstration devices have been realized that require time-consuming processes. This is mainly due to a lack of selective growth and reliable assembly processes for nanotubes. However, graphene offers an attractive alternative. Here we report the patterning of graphene nanoribbons and bent junctions with nanometre-precision, well-defined widths and predetermined crystallographic orientations, allowing us to fully engineer their electronic structure using scanning tunnelling microscope lithography. The atomic structure and electronic properties of the ribbons have been investigated by scanning tunnelling microscopy and tunnelling spectroscopy measurements. Opening of confinement gaps up to 0.5 eV, enabling room-temperature operation of graphene nanoribbon-based devices, is reported. This method avoids the difficulties of assembling nanoscale components and may prove useful in the realization of complete integrated circuits, operating as room-temperature ballistic electronic devices.     

Preparation and Characterization of <Emphasis Type="Italic">Camelina sativa</Emphasis> Protein Isolates and Mucilage

Processes for the production of protein isolates from camerlina Camelina sativa were developed by modifying the procedure used for other seeds from the Brassicaceae family, such as rapeseed and mustard. The procedure consisted of defatting the seed followed by alkaline extraction at pH 11, ultra- and diafiltration using a 5-kDa membrane, isolelectric precipitation of the proteins at pH 5 and recovery of the acid soluble protein isolates (SPI) after further filtration and drying. Protein yields as precipitated protein isolate and SPI were 10.7 and 11.4%, containing 67 and 42%, respectively. Due to the high concentration of mucilage in camelina, a water-to-seed ratio of 30 had to be used for protein extraction from the hexane-defatted seed and most of the mucilage had to be removed prior to the defatting process. A rapid mucilage extraction process using water at 55 °C was developed. Camelina mucilage absorbs water and oil. Viscosity measurements of dried and redissolved mucilage showed the highest values at natural pH, and the viscosity increased rapidly above 1% solids concentration. It may be a useful product in the food and pharmaceutical industries.     

Morphology and mechanical properties of layered silicate reinforced natural and polyurethane rubber blends produced by latex compounding

Natural rubber (NR), polyurethane rubber (PUR), and NR/PUR‐based nanocomposites were produced from the related latices by adding a pristine synthetic layered silicate (LS; sodium fluorohectorite) in 10 parts per hundred parts rubber (phr). The dispersion of the LS latices in the composite was studied by X‐ray diffraction (XRD) and transmission electron microscopy (TEM). Further information on the rubber/LS interaction was received from Fourier transform infrared spectroscopy (FTIR) and dynamic mechanical thermal analysis (DMTA). Tensile and tear tests were used to characterize the performance of the rubber nanocomposites. It was found that LS is more compatible and thus better intercalated by PUR than by NR. Further, LS was preferably located in the PUR phase in the blends, which exhibited excellent mechanical properties despite the incompatibility between NR and PUR. Nano‐reinforcement was best reflected in stiffness‐ and strength‐related properties of the rubber composites. © 2004 Wiley Periodicals, Inc. J Appl Polym Sci 92: 543–551, 2004     

The effect of organoclay on the mechanical properties and morphology of injection‐molded polyamide 6/polypropylene nanocomposites

Nanocomposites containing a thermoplastic blend and organophilic layered clay (organoclay) were produced by melt compounding. The blend composition was kept constant [polyamide 6 (PA6) 70 wt % + polypropylene (PP) 30 wt %], whereas the organoclay content was varied between 0 and 10 wt %. The mechanical properties of the nanocomposites were determined on injection‐molded specimens in both tensile and flexural loading. Highest strength values were observed at an organoclay content of 4 wt % for the blends. The flexural strength was superior to the tensile one, which was traced to the effect of the molding‐induced skin‐core structure. Increasing organoclay amount resulted in severe material embrittlement reflected in a drop of both strength and strain values. The morphology of the nanocomposites was studied by scanning electron microscopy (SEM), transmission electron microscopy (TEM), energy‐dispersion X‐ray analysis (EDX), and X‐ray diffraction (XRD). It was established that the organoclay is well dispersed (exfoliated) and preferentially embedded in the PA6 phase. Further, the exfoliation degree of the organoclay decreased with increasing organoclay content. © 2003 Wiley Periodicals, Inc. J Appl Polym Sci 91: 175–189, 2004     

MnxCr0.3Fe0.5Co0.2Ni0.5Al0.3 high entropy alloys for magnetocaloric refrigeration near room temperature

High entropy alloys (HEAs) based on transition metals display rich magnetic characteristics,however attempts on their application in energy efficient technologies remain scarce.Here,we explore the magne-tocaloric application for a series ofMnxCr0.3 Fe0.5Co0.2Ni0.5Al0.3 (0.8 ＜ x ＜ 1.1) HEAs by integrated theoretical and experimental methods.Both theory and experiment indicate the designed HEAs have the Curie tem-perature close to room temperature and is tunable with Mn concentration.A non-monotonic evolution is observed for both the entropy change and the relative cooling power with changing Mn concentration.The underlying atomic mechanism is found to primarily emerge from the complex impact of Mn on mag-netism.Advanced magnetocaloric properties can be achieved by tuning Mn concentration in combination with controlling structural phase stability for the designed HEAs.     

Focus area extraction by blind deconvolution for defining regions of interest

We present an automatic focus area estimation method, working with a single image without a priori information about the image, the camera, or the scene. It produces relative focus maps by localized blind deconvolution and a new residual error-based classification. Evaluation and comparison is performed and applicability is shown through image indexing     

Constrained quadratic errors-in-variables fitting

We propose an estimation method to fit conics and quadrics to data in the context of errors-in-variables where the fit is subject to constraints. The proposed algorithm is based on algebraic distance minimization and consists of solving a few generalized eigenvalue (or singular value) problems and is not iterative. Nonetheless, the algorithm produces accurate estimates, close to those obtained with maximum likelihood, while the constraints are also guaranteed to be satisfied. Important special cases, fitting ellipses, hyperbolas, parabolas, and ellipsoids to noisy data are discussed.     

Continuous manufacturing: Is the process mean stationary?

The statistical framework to systematically detect mean stationarity in the context of continuous manufacturing is described in this article. The methods presented in this article use econometric and financial time‐series analysis concepts in the form of unit‐root and stationarity hypothesis tests. The tests under discussion are the augmented Dickey‐Fuller, Philips‐Perron, Leybourne‐McCabe, and Kwiatkowski‐Phillips‐Schmidt‐Shin. These hypothesis tests are evaluated on data generated by a focused‐beam reflectance measurement sensor implemented on‐line in a continuous plug‐flow crystallizer. This contribution has shown that the hypothesis tests can be used to detect steady‐state conditions on‐line in a plug‐flow crystallizer. Furthermore, this econometric framework can be used as a mean stationarity “certificate” of collected samples to document that the process was mean stationary during the sampling. The statistical framework described in this article can be applied to any continuously operated unit operation or sensor measurement. © 2018 American Institute of Chemical Engineers AIChE J, 64: 2426–2437, 2018     

Secure and reliable clustering in wireless sensor networks: A critical survey

In the past few years, research interest has been increased towards wireless sensor networks (WSNs) and their application in both the military and civil domains. To support scalability in WSNs and increase network lifetime, nodes are often grouped into disjoint clusters. However, secure and reliable clustering, which is critical in WSNs deployed in hostile environments, has gained modest attention so far or has been limited only to fault tolerance. In this paper, we review the state-of-the-art of clustering protocols in WSNs with special emphasis on security and reliability issues. First, we define a taxonomy of security and reliability for cluster head election and clustering in WSNs. Then, we describe and analyze the most relevant secure and reliable clustering protocols. Finally, we propose countermeasures against typical attacks and show how they improve the discussed protocols.