Silicone elastomers filled with rare earth oxides

Silicones which possess, amongst others, remarkable mechanical properties, thermal stability over a wide range of temperatures and processability, and rare earth oxides(REO), known for their unique optic, magnetic and catalytic properties can be coupled into multifunctional composite materials(SREOs). In addition, the intrinsic hydrophobicity of REO and polysiloxanes makes them easily compatible without the need for surface treatments of the former. Thus, europium oxide (Eu2O3), gadolinium oxide (Gd2O3) and dysprosium oxide (Dy2O3)in amounts of 20 pph are incorporated as fillers into silicone matrices, followed by processing mixture as thin films and crosslinking at room temperature. The analysis of the obtained films reveals the changes induced by these fillers in the thermal, mechanical, dielectric and optical properties, as well as the hydrophobicity of the silicones. The luminescence properties of S-REO composites were investigated by fluorescence spectra and lifetime - resolved measurements with a multiemission peaks from blue to greenish register. The thermogravimetrical analysis indicates an increasing of thermal stability of the composites that contain REO, compared to pure silicone. As expected, the dielectric permittivity significantly increased due to nature of the fillers, while the dielectric loss values are relatively low for all samples, indicating a minimal conversion of electrical energy in the form of heat within bulk composites. The presence of rare earth oxides into the silicone matrix facilitates the motions of long-range charge carriers through the network resulting in higher values of conductivity of the composite films. The stress-strain measurements revealed the reinforcing effect of the rare earth metal oxides on a silicone matrix, leading to a significant increase of Young modulus. The known hydrophobicity of silicones is further enhanced by the presence of REO

Biological activity of silicone-based membranes with functionalized silsesquioxanes : characterization and perspectives for environmental applications

A series of three silsesquioxanes (containing either the original organic function (SH) (silsesquioxane 2, SH_SS), a derivatized one (NH3Cl) (silsesquioxane 1, A_SS) or completely chloro derivative (silsesquioxane 3, Cl_SS)) were obtained by acid hydrolysis of the three organo-trialkoxysilane (3-aminopropyltriethoxysilane, 3-mercaptopropyltrimethoxysilane and 3-cyanopropyltriethoxysilane). The biological compatibility was tested for the three composite films. The values of water vapors sorption capacities increase in the following order: P_Cl_SS < P_SH_SS<P_A_SS. Depending on the silsesquioxane type, an increasing of the dielectric constant value up to 4.5 as compared with the value for the silicone matrix was obtained. The bactericidal performance in environmental applications of the newly blends with specific microarchitecture, controlled porosity and higher hydrophobicity, is measured by its ability to maintain the balance between the biological selectivity and membranes functionalization as disinfection materials

Green Accounting in Romania - a Vision to European Integration

The paper debates solutions, points of view and a commune language for Green Accounting. The main purposes of our research are the following: 1.Define the object of Green Accounting 2.Scope 3.Theory and specific practices 4.Disclosure and financial analysis 5.Romanian experience in Green Accounting. How to define Green Accounting? Is Green Accounting a part of Environmental Accounting? How to ensure the balance between business interests and envinronmental protection? Are environmental goals based on Total Quality Management? How to design for Environment? This are some questions proposed to be discused in this paper.

An update: Prevalence of rabies in animalsbetween 2010 and 2017in north-eastern Romania

In order to obtain an overview of the situation of rabies positive cases, but also to establish a true prevalence of the disease among domestic and wild animals, an epidemiological survey was conducted in the north east of the country, targeting the 8 counties of Moldova region,over a period of eight years, between 2010 and 2017. A total of 2306 brain samples coming from animals with suspicion of rabies were received at the laboratories, from which 851 (36,90 %) were represented by domestic animals and 1455 (63,10 %) by wild animals. Following the implementation of the referenced techniques in rabies diagnosis, out of 2306tested samples, 492 (21,36%) were confirmed positive and 1814 negative (78,66%). Out of 1455 samples coming from wild animals, 303 (20,82 %) were confirmed positive, with a total prevalence of 21,32 %, while in the case of domestic animals out of 851 samples, 189 were positive, with a total prevalence of 22,20 %

Ceramic Nanofiltration Membrane Fouling: Application of Mathematical Modelling to the Use of Excitation Emission Matrix Spectroscopy

This paper presents a mathematical modeling for a series of experiments in which humic acid (AH) and calcium chloride (CaCl2) were used, in order to visualize the amount of contaminant before and after the nanofiltration (NF) process, using Excitation Emission Matrix Spectroscopy (EEMS). It allows to a better understanding of membrane fouling. The membrane used for these experiments was a NF ceramic membrane made of titanium dioxide (TiO2). For the experimental determinations, a constant amount of 10 mg/L HA and different amounts of CaCl2, respectively 1, 2, 3 and 4 mmol/L were used, considering the working methodology presented in this article. The presence of the amount of contaminant in water was determined using the EEMS method using the FP-8300 Spectrophotometer, after which a spectral analysis was performed. TableCurve 3D software was used to make the mathematical models in order to ensure that the equations obtained had the same shape. The values of the correlation coefficients, corresponding to the generated equations, have values ranging from 0.91 to 0.93. In order to verify the mathematical models thus obtained, graphs of the difference between the surface obtained with the help of the mathematical models and the surface obtained by means of real data were drawn. In conclusion, it turns out that, the largest difference was obtained in the case of samples taken from the feed, with a maximum difference of 31 fluorescence intensity arbitrary units (a.u.), and for the samples taken from the permeate the deference is 14 fluorescence intensity a.u

Bentonite as an active natural filler for silicone leading to piezoelectric-like response material

Raw sodium bentonite (Bent) without preliminary treatments is incorporated as a filler in a silicone matrix, from 5 to 100 parts per hundred (pph), by weight, by simple mixing in solution. The mixtures are processed as films and stabilized by condensation crosslinking at room temperature. Besides being environmentally safe and non-toxic, bentonite is 30 times cheaper than polydimethylsiloxane (PDMS), so the cost price of composites can be reduced by over 40%. Studies on the effects of bentonite addition as filler on the properties of composites reveal that thermal stability is not significantly affected, while an increase in the amount of inorganic residue with an increase of Bent content is recorded. More importantly, the mechanical and dielectric properties are significantly influenced by the Bent content in the PDMS matrix. The Young's modulus increases, while the elongation decreases, indicating a stiffening of the material and a decrease in its elasticity as the Bent load increases. Most notably, the dielectric permittivity increases up to more than five times at 103 Hz by adding 100 pph Bent, while the dielectric losses remain acceptable, especially at high frequencies for all composites. Furthermore, the study of composite films through Piezoresponse Force Microscopy and piezoelectric testing system reveals an outstanding piezoelectric-like response for composites with a high Bent content. The wideangle X-ray diffraction indicates an increase of the crystalline fraction - the main factor that influences the apparent piezoelectric coefficient - with increasing the Bent loa

Green Accounting in Romania - a Vision to European Integration

The paper debates solutions, points of view and a commune language for Green Accounting. The main purposes of our research are the following: 1.Define the object of Green Accounting 2.Scope 3.Theory and specific practices 4.Disclosure and financial analysis 5.Romanian experience in Green Accounting. How to define Green Accounting? Is Green Accounting a part of Environmental Accounting? How to ensure the balance between business interests and envinronmental protection? Are environmental goals based on Total Quality Management? How to design for Environment? This are some questions proposed to be discused in this paper

The tumour volume influence on tumour recurrence and progression-free survival in the case of atypical meningiomas: Our experience on a series of 81 cases

Objective: The objective of our study was to evaluate a possible relation between the volume of atypical meningiomas (AMs) and the risk of tumour recurrence, as well as progression-free survival (PFS). Material and methods: We evaluated 81 patients diagnosed with AMs (WHO grade II meningioma) who have undergone surgery at the "Prof. Dr. N. Oblu" Emergency Clinical Hospital Iasi between January 1, 2010, and December 31, 2019. The recorded data were demographic and imagistic (MRI, contrast-enhanced T1WI). We calculated the tumour volume prior to the surgery and evaluated the tumour recurrence using MRI at 12, 24, 36, 48 and 60 months after the surgery. Results: 50.6% of patients had meningioma volume &lt; 26.4 cm3. Women had larger tumour volumes than men (52.6%). Patients of age ? 60 years old, had tumour volumes ? 26.4 cm3 in 58.5% of cases and meningiomas with volumes ? 26.4 cm3 recurred earlier (p=0.010). Also, patients who had tumour volumes ? 26.4 cm3, had a shorter PFS (40.976 months), compared to patients with tumour volumes &lt; 26.4 cm3, who had better PFS (53.4 months). Conclusions: the tumour volume of AMs ? 26.4 cm3 represents a negative prognostic factor for both early tumour recurrence and reduced PFS