Nanofluids for energetics: effect of stabilization on the critical heat flux at boiling

Investigation of aqueous nanofluids synthesized for the first time based on the natural alumosilicate attapulgite showed their high efficiency as heat-transfer agents and the ability to provide a more than twofold increase of the critical heat flux (CHF) as compared to that of the base liquid (pure water). It is shown that insignificant additives of sodium pyrophosphate, which produce disaggregation of nanoparticles and stabilization of attapulgite-containing nanofluids, significantly improve their thermal properties and heatexchange parameters. Several mechanisms are proposed for interpretation of the observed CHF growth. It is established that the use of attapulgite nanofluids not only allows higher CHF to be reached as compared to that of pure water, but also eliminates sudden onset of the boiling crisis.     

Texture anisotropy technique in brain degenerative diseases

Structural alterations anisotropy-based measured for different areas for the most common types of dementia diseases could be a biomarker of brain impairment. The current work aims to assess whether texture anisotropy can discriminate both healthy versus Alzheimer’s and Pick’s patients based on regional evaluation while maintaining high predictive power. The investigated area is reduced from the whole-brain surface to three major lobes (i.e., frontal, temporal and parietal). A predictive model was proposed to associate a disease with a specific area in the brain based on the anisotropy values. Simultaneous analysis of 1680 measurements from 105 brain magnetic resonance images acquired as T2w and PD sequences was performed to establish the significance of the model. The cerebral calcinosis disease has been used as artificial ground truth. The association based on textural anisotropy between targeted diseases and control patients was performed by using Pearson’s correlation coefficients. A new proposed consistency index investigated the texture anisotropy relevance for all image’s types and all analyzed classes and regions. The validation study is based on area under the receiver-operating characteristic curve that depicted the overall diagnostic performance of the texture anisotropy in each region. The proposed model demonstrated that texture anisotropy is accurate solution in diagnosis of Alzheimer’s and Pick’s diseases when the investigated area is reduced to major lobes, with sensitivity >90% and specificity >80%.

     

Nucleation and Expansion During Extrusion and Microwave Heating of Cereal Foods

Expansion of biopolymer matrices is the basis for the production of a wide variety of cereal foods. A limited number of manufacturing processes provide practical solutions for the development of an impressive variety of expanded products, just by changing process variables. It is therefore essential that the mechanisms involved in expansion are well known and controlled. This paper summarizes the knowledge of nucleation and expansion in extruded and microwaved products available to date. The effect of processing conditions and properties of the biopolymeric matrix on nucleation and expansion are discussed. Moisture content enables the glassy polymeric matrix to turn into rubbery state at process temperatures, which allows superheated steam bubbles to form at nuclei and then expand, expansion being governed by the biaxial extensional viscosity of the matrix. Nucleation and expansion theories are presented along with quantitative data that support them.     

Structure formation of alkylammonium montmorillonites in organic media

Using adsorption, X-ray diffraction (XRD), rheological, electrokinetic, dielectric and calorimetric measurements, the mechanism for the gel formation of the alkylammonium derivatives of the Pyzhevsky montmorillonite (Ukraine) (OM) in organic liquids of different polarity was investigated. The influence of modification, type of the organic cations, length of the alkyl chain, type of organic liquid and polar additive as well as traces of water on the swelling volume, enthalpy of immersion, zeta potential and the Bingham yield stress of the organo-gels were evaluated.There exists a certain correlation between the swelling volume, the ability for gel formation and the basal spacing of OM (d₀₀₁), which depends on the size of the intercalated cation. Thermodynamical analysis indicates that the degree of swelling and the gel strength are determined by the energy of the layer cohesion, energy of the solvation, the electrostatic repulsion and entropy effects.The thickening of OM dispersions and gel formation is optimal when the surface coverage by alkylammonium ions reaches θ=0.85–1.0. The lyophilicity and zeta potential are then high but not too strong to cause complete peptization.The linear increase of rheological parameters of the organo-gels in benzene, toluene, p-xylene, o-xylene, chlorobenzene, benzonitrile and nitrobenzene is related to the increase of the polarization of the liquid molecules and the transition from positive to negative ζ-potentials and the enthalpy of immersion.The effect of protonic and aprotonic compounds on the rheological, electrokinetic and thermodynamic properties of the hydrocarbon gels of octadecyl benzyldimethylammonium montmorillonite was also studied. For homologue alcohols, this influence decreases with the increase of chain length, corresponding to the decrease of the adsorption and the dielectric permittivity (). The influence of the aprotonic compounds on the rheological properties and on the enthalpy of immersion does not correlate with , but this influence is larger when the polarization and electron donor ability of the polar molecules are higher.The maximal gel formation of the hydrocarbon-OM dispersions requires a certain amount of water, which corresponds to a monomolecular coverage of the polar surface centers. This effect is explained by the strong orientation of the adsorbed water molecules, which creates giant dipole moments on the particles and H-bonds between the particles.     

Dual feature selection and rebalancing strategy using metaheuristic optimization algorithms in X-ray image datasets

Multimedia Tools and Applications - The imbalance and multi-dimension are two common problems in the medical image datasets, which affect the performances of the image processing procedures. The...     

The Effect of Nanofluids on the Heat-Transfer Capacity of Miniature Thermosyphons for Electronics Cooling

Technical Physics Letters - Stable nanofluids based on DG-100 grade carbon black and carbon nanotubes have been prepared, and their influence on the maximum heat-transfer capacity and thermal...     

Effect of spectral range in surface inactivation of Listeria innocua using broad-spectrum pulsed light

Pulsed light (PL) treatment is an alternative to traditional thermal treatment that has the potential to achieve several log-cycle reductions in the concentration of microorganisms. One issue that is still debated is related to what specifically causes cell death after PL treatments. The main objective of this work was to elucidate which portions of the PL range are responsible for bacterial inactivation. Stainless steel coupons with controlled surface properties were inoculated with a known concentration of Listeria innocua in the stationary growth phase and treated with 1 to 12 pulses of light at a pulse rate of 3 pulses per s and a pulse width of 360 micros. The effects of the full spectrum (lambda = 180 to 1,100 nm) were compared with the effects obtained when only certain regions of UV, visible, and near-infrared light were used. The effectiveness of the treatments was determined in parallel by the standard plate count and most-probable-number techniques. At a fluence of about 6 J/cm(2), the full-spectrum PL treatment resulted in a 4.08-log reduction of L. innocua on a Mill finish surface, the removal of lambda < 200 nm diminished the reduction to only 1.64 log, and total elimination of UV light resulted in no lethal effects on L. innocua. Overwhelmingly, the portions of the PL spectrum responsible for bacterial death are the UV-B and UV-C spectral ranges (X < 300 nm), with some death taking place during exposure to UV-A radiation (300 < lambda < 400 nm) and no observable death upon exposure to visible and near-infrared light (lambda > 400 nm). This work provides additional supporting evidence that cell death in PL treatment is due to exposure to UV light. Additionally, it was shown that even a minor modification of the light path or the UV light spectrum in PL treatments can have a significant negative impact on the treatment intensity and effectiveness.     

Atom devices based on single dopants in silicon nanostructures

Silicon field-effect transistors have now reached gate lengths of only a few tens of nanometers, containing a countable number of dopants in the channel. Such technological trend brought us to a research stage on devices working with one or a few dopant atoms. In this work, we review our most recent studies on key atom devices with fundamental structures of silicon-on-insulator MOSFETs, such as single-dopant transistors, preliminary memory devices, single-electron turnstile devices and photonic devices, in which electron tunneling mediated by single dopant atoms is the essential transport mechanism. Furthermore, observation of individual dopant potential in the channel by Kelvin probe force microscopy is also presented. These results may pave the way for the development of a new device technology, i.e., single-dopant atom electronics.