Solid Fraction Determination at the Rigidity Point by Advanced Thermal Analysis

The aim of this work is to determine the Solid Fraction (SF) at the rigidity point (FRP) by applying advanced thermal analysis techniques. The variation of the FRP value is important to explain the solidification behavior and the presence or absence of defects in aluminum alloys. As the final alloy composition plays a key role on obtained properties, the influence of major and minor alloying elements on FRP has been studied. A Taguchi design of experiments and a previously developed calculating method, based on the application of high rank derivatives has been employed to determinate first the rigidity point temperature (RPT) and after the corresponding FRP for AlSi10Mg alloys. A correlation factor of r2 of 0.81 was obtained for FRP calculation formula in function of the alloy composition.

Compounding a High Dielectric Constant Thermoplastic Material for Production of Microwave Photonic Crystals through Additive Manufacturing

Additive Manufacturing techniques allow the production of complex geometries unattainable through other traditional technologies. This advantage lends itself well to rapidly iterate and improve upon the design of microwave photonic devices, which are structures with intricate, repeating features. The issue tackled by this work involves compounding a high-dielectric constant material that can be used to produce 3D topological structures using polymer extrusion-based AM techniques. This material was ABS based, and used barium titanate ceramic as the high-dielectric compound of the composite, and involved the use of a surfactant and a plasticizer to facilitate processing. Initial small amounts of material were compounded using an internal batch mixer, and studied using polymer thermal analysis techniques, such as thermogravimetric analysis, rheometry, and differential scanning calorimetry to determine the proper processing conditions. The production of the material was then scaled-up through the use of a twin-screw extruder system, producing homogeneous pellets. Finally, the thermoplastic composite was used with a screw-based, material extrusion additive manufacturing technique to produce a slab for measuring the dielectric constant of the material, as well as a preliminary 3D photonic crystal. The real part of dielectric constant of the composite was measured to be 12.85 in the range of 10GHz to 12GHz, representing the highest dielectric constant ever demonstrated for a thermoplastic AM composite at microwave frequencies. The dielectric loss tangent was equal to 0.046, representing a low-loss dielectric.

Major Challenges and Recent Advances in Characterizing Biomass Thermochemical Reactions

Thermochemical conversions are pathways for the utilization of biomass to produce a variety of value-added energy and chemical products. For the development of novel thermochemical conversion technologies, an accurate understanding of the reaction performance and kinetics is essential. Given the diversity of the thermal analysis techniques, it is necessary to understand the features and limitations of the reactors, ensuring that the selected thermal analysis reactor meets the specific need for reaction characterization. This paper provides a critical overview of the thermal analysis reactors based on the following perspectives: 1) gas flow conditions in the reactor, 2) particle’s external and internal heat and mass transfer limitations, 3) heating rate, 4) temperature distribution, 5) nascent char production and reaction, 6) liquid feeding and atomization, 7) simultaneous sampling and analyzing of bed materials, and 8) reacting atmosphere change. Finally, prospects and future research directions in the development of thermal analysis techniques are proposed.

Lignosulfonate-Based Polyurethane Adhesives

The feasibility of using lignosulfonate (LS) from acid sulphite pulping of eucalyptus wood as an unmodified polyol in the formulation of polyurethane (PU) adhesives was evaluated. Purified LS was dissolved in water to simulate its concentration in sulphite spent liquor and then reacted with 4,4′-diphenylmethane diisocyanate (pMDI) in the presence or absence of poly(ethylene glycol) with Mw 200 (PEG200) as soft crosslinking segment. The ensuing LS-based PU adhesives were characterized by infrared spectroscopy and thermal analysis techniques. The adhesion strength of new adhesives was assessed using Automated Bonding Evaluation System (ABES) employing wood strips as a testing material. The results showed that the addition of PEG200 contributed positively both to the homogenization of the reaction mixture and better crosslinking of the polymeric network, as well as to the interface interactions and adhesive strength. The latter was comparable to the adhesive strength recorded for a commercial white glue with shear stress values of almost 3 MPa. The optimized LS-based PU adhesive formulation was examined for the curing kinetics following the Kissinger and the Ozawa methods by non-isothermal differential scanning calorimetry, which revealed the curing activation energy of about 70 kJ·mol−1.

Electron Paramagnetic Resonance, and Thermoluminiscence Mechanism In Radiation Shielding Cr2O3 - Ba(La)2SiO6 Glasses

The research on Cr2O3 doped SiO2 glasses is well known for advanced dielectrics. However, there are many other valuable properties associated with Cr2O3 inclusive various glasses. In this view, the current research aimed to develop the radiation shielding, elastically rich, and the EPR based Cr2O3 doped Ba(La)2SiO6 glass resource. Electron paramagnetic resonance, radiation shielding, and elastic studies have been employed to investigate the advanced characteristics. Structural characterization suggests glassy behavior with the Cr2O3 undoped glass. Whereas the other involved with Cr2O3 mol% shown with the ceramic behavior. The glass transition phenomena and forming abilities are studied with the help of differential thermal analysis techniques. Elastic studies have been done with the limit on the glasses, which suggests the glasses are flexible for elastic use. The electron paramagnetic resonance reports suggest high order of dipole-dipole super-exchange interaction and rhombohedral distortion within the glasses. Furthermore, we have tested the glasses for radiation shielding properties. The values of mass attenuation coefficient, radiation protection efficiency, mean free path, and energy absorption build-up factor of the glasses are measured and compared with values obtained with the help of standard photon shielding and dosimetry software. The studies indicate that the glasses developed are capable of radiation shielding. Upon 50 kGy, γ - irradiation, the thermoluminescence properties of the glasses are reported. The results found to be interesting, and reveal the resource developed are thermoluminescent at low activation energies. Furthermore, we have tested, the glasses for radiation shielding properties. Moreover, to introduce the detailed correlation between electron paramagnetic resonance, and thermoluminescence phenomenon, we have annealed the glasses under 0 to 300 oC temperature and upon the 0 to 50 kGy, γ - irradiation dose level. The electron paramagnetic resonance and thermoluminescence properties obtained for the glasses are highly correlative.

Identification test of elements remaining in the barrel after firing, using Differential Scanning Calorimetry

The issue of elements remaining in the barrel after firing is crucial both for the safe use of munition, and its reliability. These elements maybe categorized as being part of a metal case or a projectile (for example, fragments of broken connectors between a metal band and a projectile), or those associated with a propelling charge (like unburnt propellant grains). Both groups are undesirable and reflect the ammunition improper work. During own shooting tests of a 120 mm mortar ammunition the problem of unburnt elements remaining in the barrel occurred. The collected material was tested using one of the thermal analysis techniques - Differential Scanning Calorimetry - to characterize and to identify the tested sample.

Obtaining and Preliminary Characterization of Some Polyethylene Composites with Nickel-Silver Ferrite Filler

Samples of LDPE (low-density polyethylene) and LDPE-PANSA (low-density polyethylene -4-Amino-3-hydroxy- 1-naphthalenesulfonic acid) copolymer with Ag0.5�Ni0.5�Fe2O4 powder (as a filler) composites were developed. Following the preliminary characterizations on the thermooxidability (by thermal analysis techniques), the dielectric behavior (by dielectric spectroscopy technique), the mechanical behavior, etc. it was found that the developed materials do not show significant changes after 240 h exposure to 150 mW / m2 UV. The addition of 3wt% PANSA in LDPE has the effect of increasing the mechanical performance of polymer composites with Ag0.5�Ni0.5�Fe2O4 filler. The addition of 15 wt% ferritic powder leads to significant increases in dielectric losses (by about 100% in the case of pure LDPE and about 185% of the LDPE copolymer with 3 wt% PANSA) and to the increase of the real component of the relative permittivity (by about 34.4 % in LPDE, respectively about 36.4% in LPDE copolymer / 3% wt PANSA). Dielectric behavior of the investigated materials indicates that the effect of Ag0.5�Ni0.5�Fe2O4 powder in LDPE and of copolimer LDPE with 3 wt% PANSA consists in the increasing of the shielding efficiency of electromagnetic waves - the maximum effect being recorded in the case of the composite material with the content: LDPE 84.5 wt%, 2.5 wt% / PANSA and 13% wt% Ag0.5�Ni0.5�Fe2O4.

Study on the fluorination of dysprosium oxide by ammonium bifluoride for the preparation of dysprosium fluoride

In this report, dysprosium fluoride (DyF3) - a material for the preparation of dysprosium (Dy) metal was prepared by the fluorination of dysprosium oxide (Dy2O3) by ammonium bifluoride (NH4HF2) reagent. The effect of reaction time and temperature on the formation of dysprosium fluoride salt has been studied. The phase composition and crystal structure of the obtained products were analysed by X-ray diffraction (XRD). Thermal analysis techniques were applied to determine the temperature range of the fluorination. Scanning electron microscopy with energy dispersive spectroscopy (SEM/EDS) was used for external morphology observation and chemical elemental composition analysis. The results showed that the high purity phase of DyF3 was formed at the conditions: reaction time and temperature of >1 h and >350oC, respectively. The product is available for the preparation of Dy metal by metallothermic reduction.

Chimeric Stimuli-Responsive Liposomes as Nanocarriers for the Delivery of the Anti-Glioma Agent TRAM-34

Nanocarriers are delivery platforms of drugs, peptides, nucleic acids and other therapeutic molecules that are indicated for severe human diseases. Gliomas are the most frequent type of brain tumor, with glioblastoma being the most common and malignant type. The current state of glioma treatment requires innovative approaches that will lead to efficient and safe therapies. Advanced nanosystems and stimuli-responsive materials are available and well-studied technologies that may contribute to this effort. The present study deals with the development of functional chimeric nanocarriers composed of a phospholipid and a diblock copolymer, for the incorporation, delivery and pH-responsive release of the antiglioma agent TRAM-34 inside glioblastoma cells. Nanocarrier analysis included light scattering, protein incubation and electron microscopy, and fluorescence anisotropy and thermal analysis techniques were also applied. Biological assays were carried out in order to evaluate the nanocarrier nanotoxicity in vitro and in vivo, as well as to evaluate antiglioma activity. The nanosystems were able to successfully manifest functional properties under pH conditions, and their biocompatibility and cellular internalization were also evident. The chimeric nanoplatforms presented herein have shown promise for biomedical applications so far and should be further studied in terms of their ability to deliver TRAM-34 and other therapeutic molecules to glioblastoma cells.

The Cytotoxicity, DNA Fragmentation, and Decreasing Velocity Induced by Chromium (III) Oxide on Rainbow Trout Spermatozoa

The present study aimed to determine the cytotoxicity of Chromium (III) oxide micro particles (Cr2O3-Ps) in rainbow trout (Oncorhynchus mykiss) spermatozoa. Firstly, Cr2O3-Ps were synthesized and structurally characterized the surface, morphological for particle size and thermal properties. In addition, its structural and elemental purity was determined using EDX spectrum and elemental maps. Structural purity, thermal properties, and stability of Cr2O3-Ps were also examined in detail by performing thermal analysis techniques. The cytotoxicity of structurally defined Cr2O3-Ps was measured by the observation of velocities, antioxidant activities, and DNA damages in spermatozoa after exposure in vitro. The straight line velocity (VSL), the curvilinear velocity (VCL), and the angular path velocity (VAP) of spermatozoa decreased after exposure to Cr2O3-Ps. While the superoxide dismutase (SOD) and the catalase (CAT) decreased, the lipid peroxidation increased in a dose-dependent manner. However, the total glutathione (tGSH) did not affect in this period. DNA damages was also determined in spermatozoa using Comet assay. According to DNA in tail (%) data, DNA damages have been detected with gradually increasing concentrations of Cr2O3-Ps. Furthermore, all of class types related to DNA fragmentation has been observed between 50 µg/L and 500 µg/L concentrations of Cr2O3-Ps exposed to rainbow trout spermatozoa. At the end of this study, we determined that the effective concentrations (EC50) were 76.67 µg/L for VSL and 87.77 µg/L for VCL. Finally, these results about Cr2O3-Ps may say to be major risk concentrations over 70 µg/L for fish reproduction in aquatic environments.