Visco-Elastic Properties of Semi-Solid Alloys

Oscillation and creep experiments have been performed with Semi-Solid Material (SSM) AlSi7 with 35% solid fraction to investigate the early visco-elastic properties after shearing of the material in a Searle Rheometer. The preparation of the SSM has been done in situ using a standard procedure to guarantee for all experiments the same initial properties of the material. First, oscillation experiments at low amplitude allowed to study the evolution of material structure with time. Subsequently, creep experiments have been performed changing the resting period based on previous results. Creep experiments are characterized by exposing the material to a sudden increase of shear stress. The resolution in time has been 0.01 seconds, which allows observing the dynamics of the development of visco-elastic properties.The material exhibits viscoelastic properties that are becoming more pronounced with longer resting time. This is in accordance with previous experiments where the ratio between elastic and viscous properties increases with increasing resting time. The development of the elastic properties follows the increase of the yield stress due to the creation of an internal structure of the material, which starts immediately after stopping shearing. The investigation of the short-term response of SSM can be particularly relevant for industrial practice, where material deformation during die filling is very fast and the material flow does not take place in steady-state condition.

Temperature and entropy in molecular system

The irreversibility, temperature, and entropy are identified for an atomic system of solid material. Thermodynamics second law is automatically satisfied in the time evolution of molecular dynamics (MD). The irreversibility caused by an atom spontaneously moves from a non-stable equilibrium position to a stable equilibrium position. The process is dynamic in nature associated with the conversion of potential energy to kinetic energy and the dissipation of kinetic energy to the entire system. The forward process is less sensitive to small variation of boundary condition than reverse process, causing the time symmetry to break. Different methods to define temperature in molecular system are revisited with paradox examples. It is seen that the temperature can only be rigorously defined on an atom knowing its time history of velocity vector. The velocity vector of an atom is the summation of the mechanical part and the thermal part, the mechanical velocity is related to the global motion (translation, rotation, acceleration, vibration, etc.), the thermal velocity is related to temperature and is assumed to follow the identical random Gaussian distribution for all of its [Formula: see text], [Formula: see text] and [Formula: see text] component. The [Formula: see text]-velocity (same for [Formula: see text] or [Formula: see text]) versus time obtained from MD simulation is treated as a signal (mechanical motion) corrupted with random Gaussian distribution noise (thermal motion). The noise is separated from signal with wavelet filter and used as the randomness measurement. The temperature is thus defined as the variance of the thermal velocity multiply the atom mass and divided by Boltzmann constant. The new definition is equivalent to the Nose–Hover thermostat for a stationary system. For system with macroscopic acceleration, rotation, vibration, etc., the new definition can predict the same temperature as the stationary system, while Nose–Hover thermostat predicts a much higher temperature. It is seen that the new definition of temperature is not influenced by the global motion, i.e., translation, rotation, acceleration, vibration, etc., of the system. The Gibbs entropy is calculated for each atom by knowing normal distribution as the probability density function. The relationship between entropy and temperature is established for solid material.

Characterisation of Microplastics from the Effluent of a Municipal Wastewater Treatment Plant and from its Natural Receptor

Results obtained from the characterization of three water samples (one representing the effluent of a municipal treatment plant and the two others representing surface water from the Jiu River/Romania, upstream and downstream of the effluent discharge point) are presented in this study in terms of microplastic content. The water samples were processed by successively passing them through a series of filters with the following dimensions: 5 mm, 0.5 mm (500 im), 0.1 mm (100 im) and then through some microfiltration membranes (MF) type EZ-Pak Membrane Filters (Merk-Millipore) made of a mixture of cellulose esters, with an average pore diameter of 0.45�m. In order to highlight the microplastics in the water samples, their analysis was performed as well as the solid material retained on the microfiltration membranes, by scanning electron microscopy (SEM) using a SEM Quanta FEG 250/Thermo Fischer Scientific. The results obtained highlighted the existence of microplastics in all the analyzed samples, in the known forms presented in the specialized literature: irregular planes, fibers and spheres. Their dimensions are variable, ranging between 3.2 �m and 119.5 �m for irregular plane microplastics and between 3 �m and 15 �m for spherical microplastics. The dimensions of microplastics in the form of fibers are also in the range of tens of �m and cannot be established exactly because in most cases they appear in the form of conglomerates. The treatment plant�s microplastic effluents content led to the modification of the physical-chemical indicators of the water in their natural receptor. Thus, the content of organic matter and total suspended matter in the downstream water compared to the effluent discharge point is higher than in the upstream water. The analysis of microplastics by SEM allows only their highlighting and their geometry, being a first step in the study of the pollution induced by such materials.

Particle Characterisation of Traditional Homeopathically Manufactured Medicine Cuprum metallicum and Controls

Background: Homeopathy is highly controversial. The main reason for this is its use of very highly dilute medicines (high homeopathic potencies, HHP), diluted beyond the Avogadro/Loschmidt limit. Research using several different methods has demonstrated the presence of particles, including nanoparticles of source material, in HHPs. This study aims to verify the results of a previous publication that detected the presence of particles in all dilutions. Methods: We used the Nano Tracking Analyzer (NTA) to examine dilutions of a commonly used homeopathic medicine, an insoluble metal, Cuprum metallicum, for the presence of particles. The homeopathic medicines tested were specially prepared according to the European pharmacopoeia standards. We compared the homeopathic dilutions/dynamizations with simple dilutions and controls including a soluble medicine. Results: We observed the presence of solid material in all preparations including HHPs (except for pure water). The measurements showed significant differences in particle sizes distribution between homeopathic manufacturing lines and controls. Conclusion: Homeopathic medicines do contain material with a specific size distribution even in HHPs diluted beyond the Avogadro/Loschmidt limit. This specificity can be attributed to the manufacturing and potentization process. This material demonstrates that the step-by-step process (dynamized or not) does not match the theoretical expectations in a dilution process. The starting material and dilution/dynamization method influences the nature and concentration of these NPs.

Effects of maltodextrin on physicochemical properties of freeze-dried avocado powder

The effect of maltodextrin on the moisture sorption isotherm, glass transition temperature (Tg), and degree of caking of freeze-dried avocado samples at room temperature (25°C) was investigated. The incorporation of maltodextrin reduced the water sorption capacity of the powder due to its less hygroscopic nature. Parameters derived from the Guggenheim, Anderson, and de Boer (GAB) model describing the properties of absorbed water are discussed. The water absorption isotherm possessed the characteristic sigmoid-shaped type II isotherm curves and the model gave the best fit over the whole range of aw tested. The differential scanning calorimetric method was used to measure the Tg of freeze-dried avocado samples. Increasing the water content decreased the Tg, and Tg was increased with increasing maltodextrin content. Increased maltodextrin content to solid material in the freeze-dried sample was associated with less sensitivity to caking as evidenced by Tg values. In addition, increased maltodextrin content in the powders caused brighter, less yellowish, and more greenish coloration and protected color change including browning index. The antioxidant capacity was significantly decreased with increasing maltodextrin content. Thus, the effect of maltodextrin concentration on physicochemical properties was a promising way to preserve the physical property and chemical compounds in freezedried avocado powder.

Detect Environment Pollution by GIS for Some Regions in Baghdad City

The present study aims at assessing the status of heavy metals such as nickel, cadmium and lead to pollute some areas of Baghdad city. In this study the spectral absorption device and the program ArcGIS 10.2 will using. The soil samples were taken from five different locations in Baghdad, including Ameriya, Kadhimiya, Palestine Street, Jadiriyah and Taji for the 5cm depth layer on both sides of the road. This work on soil samples has been completed in two :phases 1 - Preparation of samples: For the purpose of converting solid material into a extract containing elements in the form of single ions can be estimated by the device 2-Determination of elements: Samples prepared to the device for the purpose of estimating their concentration in PPM units using the Atomic Absorption Spectrometer. The findings of this study can be summarized as follows: 1-The results showed that nickel concentrations ranged from 0.0336-0.1512 ppm where the lowest value of nickel was found in Kadhimiya by 0.0336 and the highest value was found in Ameriya with a value of 0.1512 and it is considered to be a non-polluting nickel in these areas because it did not exceed the critical limit 1.3 ppm. Which was explained by GIS using the map of Baghdad and determine the area studied. The results were distributed by the interpolation method using ArcGIS 10.2 program, it was noticed that there are high pollutant values in an area considered agricultural according to the classification of human settlements, which is the Jadiriyah area, where Lead (Pb) element showed a strange behaviour by its presence in high values in Jadiriyah, where its source is unknown. A future research will be prepared to study the sources of these pollutants for treatment.

Precipitation of Solid Waste in Olive Mill Wastewater by Coagulation using Calcium Carbonate (CaCO3)

This study aimed to use a chemical coagulant to treat Olive Mill Wastewater (OMW) in such a way as to improve and expedite the process of precipitating the solid waste material present in the wastewater. This process is of extreme importance in harvesting the solid material that can be used as domestic or industrial fuel material and as a supplement to animal feed. The chemical coagulant used in this study was calcium carbonate (CaCO3). The effect of the addition of this coagulant on some physical properties of olive mill wastewater (OMW) such as pH, electrical conductance (EC), the precipitated amount of the total suspended solids (TSS), and the higher heating value (HHV) of the precipitated solids was studied. It was found that small amounts of CaCO3 need to be added to affect the operation. The study results showed that the optimum value to be used was around three wt/wt %.

A dilatant, two-layer debris flow model validated by flow density measurements at the Swiss illgraben test site

We propose a dilatant, two-layer debris flow model validated by full-scale density/saturation measurements obtained from the Swiss Illgraben test site. Like many existing models, we suppose the debris flow consists of a matrix of solid particles (rocks and boulders) that is surrounded by muddy fluid. However, we split the muddy fluid into two fractions. One part, the inter-granular fluid, is bonded to the solid matrix and fills the void space between the solid particles. The combination of solid material and inter-granular fluid forms the first layer of the debris flow. The second part of the muddy fluid is not bonded to the solid matrix and can move independently from the first layer. This free fluid forms the second layer of the debris flow. During flow the rocky particulate material is sheared which induces dilatant motions that change the location of the center-of-mass of the solid. The degree of solid shearing, as well as the amount of muddy fluid and of solid particles, leads to different flow compositions including debris flow fronts consisting of predominantly solid material, or watery debris flow tails. De-watering and the formation of muddy fluid washes can occur when the solid material deposits in the runout zone. After validating the model on two theoretical case studies, we show that the proposed model is able to capture the streamwise evolution of debris flow density in time and space for real debris flow events.

Investigation of the surface overhanging elements of parts manufactured by the SLM

The work considers the task of modelling the mode of thermal action on the system of solid material and one aluminium granule. To improve the properties of synthesized parts and decrease porosity of the surface overhanging elements optimal processing parameters were calculated. The paper shows the result of modeling and predict surface roughness and porosity with four parameters pair of scanning speed and laser power.