Effect of milling and annealing on microstructural, electrical and magnetic properties of electrodeposited Ni-11.3fe-1.4W alloy

A nanostructured Ni-11.3Fe-1.4W alloy deposit was obtained from an ammonium citrate bath at a current density of 600 mAcm -2. XRD analysis shows that the deposit contains an amorphous matrix having embedded nanocrystals of the FCC phase of the solid solution of Fe and W in Ni with the average crystal grain size of 8.8 nm. The deposit has a high internal microstrain value and a high minimum density of chaotically distributed dislocations. The effect of milling and annealing of the Ni-11.3Fe-1.4W alloy on electrical and magnetic properties was studied. Structural changes in the alloy take place during both annealing and milling. Upon deposition, the alloy was heated to 420 °C. Heating resulted in structural relaxation which induced a decrease in electrical resistivity and an increase in magnetic permeability of the alloy. Further heating of the alloy at temperatures higher than 420 °C led to crystallization which caused a reduction in both electrical resistivity and magnetic permeability. The milling of the alloy for up to 12 hours caused a certain degree of structural relaxation and crystallization of the alloy. The increase in crystal grain size up to 11 nm and the partial structural relaxation induced a decrease in electrical resistivity and an increase in magnetic permeability of the alloy. Heating the powders obtained by milling at 420 °C led to complete structural relaxation, reduced electrical resistivity, and increased magnetic permeability. During heating of the powders obtained by milling at temperatures above 420 °C, crystallization and a significant increase in crystal grain size occurred, leading to a reduction in both electrical resistivity and magnetic permeability. The best magnetic properties were exhibited by the alloys milled for 12 hours and annealed thereafter at 420 °C. In these alloys, crystal grains were found to have an optimum size, and complete relaxation took place, resulting in a maximum increase in magnetic permeability

Modification of poly(methyl methacrylate) denture base materilas with diesters of itaconic acid

Cilj ovog rada je ispitivanje mogućnosti modifikacije komercijalnih dvokomponentnih sistema za dobijanje materijala za bazu proteza dodavanjem estara itakonske kiseline u tečnu komponentu sistema, radi dobijanja materijala većeg stepena biokompatibilnosti. U prvom delu ovog rada izvršena je karakterizacija tri sistema za dobijanje baza proteze (Biocryl, Poli Hot i Futura Basic Hot) i ispitan je uticaj veličine zrna i raspodele veličina zrna čvrste komponente sistema koja se sastoji od PMMA praha. Komercijalni sistem za bazu proteza se sastoji od čvrste i tečne komponente. Tečna komponenta sadrži monomer metil metakrilat i umreživač nejčešće etilenglikol-dimetakrilat (EGDM) dok se čvrsta komponenta sastoji od praha PMMA i inicijatora, najčešće dibenzoil peroksida (DBO). Proteze sa dobijaju mešanjem čvrste i tečne komponente u odnosu 2:1 i polimerizacijom pri odabranom temperaturnom režimu. Ispitan je uticaj veličine zrna i raspodele veličina zrna čvrste komponente sistema na apsorpciju vode i mehaničke karakteristike gotovog proizvoda radi određivanja najpovoljnijeg komercijalnog sistema. Kao optimalni komercijalni sistem pokazao se Byocril koji poseduje najužu raspodelu veličina zrna čvrste komponente i srednju prečnik zrna od 55 μm. U drugom delu ovog rada izvršena je modifikacija komercijalnog sistema za bazu proteza dimetil itakonatom, dibutil itakonatom i ditetrahidrofurfuril itakonatom (2,5 - 10 masenih % itakonata). Ispitan je uticaj tipa i količine itakonata na: apsorpciju tečnosti (voda i smeša etanol/voda), količinu zaostalog monomera, termičke, dinamičko-mehaničke i mehaničke karakteristike (tvrdoća, žilavost, napon pri kidanju) sintetisanih materijala. Takođe je ispitan i uticaj ubrzanog starenja na mehanička svojstva sintetisanih materijala. Utvrđeno je da dodatak itakonata u sastav komercijalnih sistema za dobijanje baze proteza značajno smanjuje količinu zaostalog metil metakrilata što materijal čini niže toksičnim i biokompatibilnijim. Kao najoptimalniji uzorak pokazao se materijal modifikovan sa 2,5 masena % dimetil itakonata. Činjenica II da za dobijanje itakonske kiseline nije potrebno koristiti petrohemijske izvore sirovina predstavlja veliku prednost u odnosu na akrilnu i metakrilnu kiselinu i njihove derivate.The aim of this work is to examine the possibility of modification of commercial denture base materials with itaconic acid esters, in order to obtain a higher degree of material biokompatibility. In the first part of this work characterization of three commercial materials was carried out. The effect of bead size and bead size distribution of prepolymer powder onto water absorption and mechanical characteristics of the end product in order to determine the optimal commercial material for the further course of study. The Byocril that has the narrowest bead size distribution and mean bead diameter of 55 μm is found to be the optimal commercial material. In the second part of this work modification of commercial PMMA denture base material with dimethyl itaconate, di-n-butyl itaconate and ditetrahydrofurfuryl itaconate (2.5 to 10 wt%) was carried out. The effect of the itaconate content on the absorption of fluids (water and a mixture of ethanol/water), the residual monomer content, thermal, dynamic-mechanical and mechanical properties (hardness, toughness, stress at break) was investigated. The effect of the accelerated aging on the mechanical properties of synthesized materials was also investigated. It was found that the addition of itaconate in the denture base materials formulation significantly reduces the amount of residual methyl methacrylate, which makes the material less toxic. The optimal sample was found to be the material modified with 2.5 wt% of dimethyl itaconate. In the third part of this work, the influence of isothermal microwave polymerization on the applicative properties of denture base materials was investigated. It was found that the samples synthesized under isothermal microwave field have better application properties compared to the samples synthesized by conventional polymerization

The effect of structural changes during sintering on the electric and magnetic traits of the Ni96.7Mo3.3 alloy nanostructured powder

Ni96.7Mo3.3 powder was electrochemically obtained. An X-ray diffraction analysis determined that the powder consisted of a 20% amorphous and 80% crystalline phase. The crystalline phase consisted of a nanocrystalline solid nickel and molybdenum solution with a face-centred cubic (FCC) lattice with a high density of chaotically distributed dislocations and high microstrain value. The scanning electronic microscopy (SEM) showed that two particle structures were formed: larger cauliflower-like particles and smaller dendriteshaped ones. The thermal stability of the alloy was examined by differential scanning calorimetry (DSC) and by measuring the temperature dependence of the electrical resistivity and magnetic permeability. Structural powder relaxation was carried out in the temperature range of 450 K to 560 K causing considerable changes in the electrical resistivity and magnetic permeability. Upon structural relaxation, the magnetic permeability of the cooled alloy was about 80% higher than the magnetic permeability of the fresh powder. The crystallisation of the amorphous portion of the powder and crystalline grain increase occurred in the 630 K to 900 K temperature interval. Upon crystallisation of the amorphous phase and crystalline grain increase, the powder had about 50% lower magnetic permeability than the fresh powder and 3.6 times lower permeability than the powder where only structural relaxation took place

Supplementary data for article : Panic, V. V.; Seslija, S. I.; Popovic, I. G.; Spasojevic, V. D.; Popovic, A. R.; Nikolic, V. B.; Spasojevic, P. M. Simple One-Pot Synthesis of Fully Biobased Unsaturated Polyester Resins Based on Itaconic Acid. Biomacromolecules 2017, 18 (12), 3881–3891. https://doi.org/10.1021/acs.biomac.7b00840

Supporting information for: [https://doi.org/10.1021/acs.biomac.7b00840]Related to published version: [http://cherry.chem.bg.ac.rs/handle/123456789/2568]Related to accepted version: [http://cherry.chem.bg.ac.rs/handle/123456789/3058

The influence of structural changes on electrical and magnetic characteristics of amorphous powder of the nixmoy alloy

Nickel and molybdenum alloy powder was electrodeposited on a titanium cathode from a NiSO4⋅7H2O and (NH4)6 Mo7O24⋅4H2O ammonium solution. The desired chemical composition, structure, size and shape of particles in the powder samples were achieved by an appropriate choice of electrolysis parameters (current density, composition and temperature of the solution, cathode material and electrolysis duration). Metal coatings form in the current density range 15 mA cm-2<j<30 mA cm-2. If the current density is greater than 40mA cm-2 then powders form. The chemical composition of powder samples depends on the current density of electrodeposition. The molybdenum content in the powder increases with the increase of current density (in the low current density range), while in the higher current density range the molybdenum content in the alloy decreases with the increase of the current density of deposition. Smaller sized particles form at higher current density. X-ray analysis, differential scanning calorimetric and measurements of the temperature dependence of electric resistance and magnetic permeability of the powder samples were all used to establish a predominantly amorphous structure of the powder samples formed at the current density of j≥70mA cm-2. The crystalline particle content in the powder samples increases with the decrease of the current density of deposition. Powder heating causes structural changes. The process of thermal stabilization of nickel and molybdenum amorphous powders takes place in the temperature interval from 463K to 573K and causes a decrease in electrical resistance and increase in magnetic permeability. The crystallization temperature depends on the value of current density of powder electrodeposition. Powder formed at j=180 mA cm-2 begins to crystallize at 573K, while the powder deposited at j=50 mA cm-2 begins to crystallize at 673K. Crystallization of the powder causes a decrease in electric resistivity and magnetic permeability. The Curie temperature of the crystallized powders is about 10 K higher than the Curie temperature of amorphous powders

The effect of structural changes on magnetic permeability of amorphous powder Ni80Co20

The structural changes of Ni80Co20 amorphous powder were tested during heating. The alloy was obtained by electrolysis from ammonia solution sulfate of cobalt and nickel on the titanium cathode. The differential scanning calorimetry (DSC) method was used to detect that the crystallization process of powder occurred in two stages with crystallization peaks temperatures of the first stage at 690 K and of the second stage at 790 K. The effect of structural relaxation and crystallization of powder on magnetic properties was predicted by measurement of the relative magnetic permeability change in isothermal and nonisothermal conditions. On the basis of the time change of relative magnetic permeability at a defined temperature in the temperature range of the first and second crystallization peak on the thermogram, the kinetics of crystallization was defined. It was predicted, that in the initial time interval, in the range of the first crystallization peak, the rate of crystallization is determined by the rate of nucleation of the amorphous part of the powder. However, in the second time interval, the crystallization rate is determined by the rate of diffusion. In the range of the second peak, in the beginning the rate of crystal growth is determined by activation energy of the atom pass from smaller to bigger crystal grain. In second time interval, the rate of crystal grain growth is determined by the diffusion rate of atoms to the location of integration into bigger crystal grains. For all processes which determine the rate of crystallization in temperature ranges of both crystallization peaks, the Arrhenius temperature dependence of rate for those processes is obtained. The relative magnetic permeability of crystallized powder at 873 K, is smaller for about 30 % than the relative magnetic permeability of fresh powder at room temperature. However, structurally relaxed powder at 573 K has an about 22 % larger magnetic permeability than the same fresh powder at room temperature

Development of new material for the environmental-friendly energy generation processes

The aim of this study was to develop a new material which has high hydrogen storage capacity and hydrogen absorption/desorption rate. This material, which is based on cobalt powder onto which palladium was chemically deposited can be used in environmentally friendly energy generation processes, thus ensuring preventive protection of human health. Hydrogen absorption was investigated using differential scanning calorimetry (DSC) and by measuring hydrogen pressure under isothermal and non-isothermal conditions in a chamber containing either pure cobalt powder either cobalt powder onto which palladium was chemically deposited (Co-0.003 Pd). The mechanism of hydrogen absorption has been described. It was noticed that palladium catalyses hydrogen absorption by dissociating the adsorbed H2 molecules into H atoms more rapidly on its own atoms than on cobalt ones. The catalysis of dissociation of H2 molecules enabled hydrogen absorption into Co-0.003 Pd powder to occur at lower temperatures. The results of this study enable integration of technological and public health investigation in order to ensure preventive protection of human health through enviromental protection

An EPR spin-probe and spin-trap study of the free radicals produced by plant plasma membranes

Plant plasma membranes are known to produce superoxide radicals, while the production of hydroxyl radical is thought to occur only in the cell wall. In this work it was demonstrated using combined spin-trap and spin-probe EPR spectroscopic techniques, that plant plasma membranes do produce superoxide and hydroxyl radicals but by kinetically different mechanisms. The results show that superoxide and hydroxyl radicals can be detected by DMPO spin-trap and that the mechanisms and location of their production call be differentiated using the reduction of spin-probes Tempone and 7-DS. It was shown that the mechanism of production of oxygen reactive species is NADH dependent and diphenylene iodonium inhibited. The kinetics of the reduction of Temponc, combined with scavengers or the absence of NADH indicates that hydroxyl radicals are produced by a mechanism independent of that of superoxide production. It was shown that a combination of the spill-probe and spin-trap technique can be used in free radical studies of biological systems, with a number of advantages inherent to them

Effect of electrodeposition current density on the microstructure and magnetic properties of nickel-cobalt-molybdenum alloy powders

Nanostructured nickel-cobalt-molybdenum alloy powders were electrodeposited from an ammonium sulfate bath. The powders mostly consist of an amorphous phase and a very small amount of nanocrystals with an mean size of less than 3 nm. An increase in deposition current density increases the amorphous phase percentage, the density of chaotically distributed dislocations and internal microstrains in the powders, while decreasing the mean nanocrystal size. The temperature range over which the structural relaxation of the powders deposited at higher current densities occurs is shifted towards lower temperatures. A change in relative magnetic permeability during structural relaxation is higher in powders deposited at higher current densities. Powder crystallization takes place at temperatures above 700oC. The formation of the stable crystal structure causes a decrease in relative magnetic permeability

The prognostic role of androgen receptor in patients with early stage breast cancer: a meta-analysis of clinical and gene expression data

Androgeni receptor je u visokom procentu zastupljen u tkivu karcinoma dojke, gde se može naći i do 70%, ali je njegov značaj do sada nedovoljno ispitivan. Cilj: Želeli smo da ispitamo prognostičku ulogu androgenog receptora u ranom karcinomu dojke (KD). Metrijal i metode: Prognostičku ulogu androgenog receptora (AR) ispitali smo kroz metaanalizu publikovanih kliničkih studija koje su ispitivale uticaj ekspresije AR na preživljavanje bez bolesti (eng. disease free survival-DFS), kao i ukupno preživljavanje (eng. overall survival-OS) kod pacijentkinja sa ranim karcinomom dojke. Koristeći ključne reči na engleskom jeziku "karcinom dojke" i "androgen receptor" pretražili smo dostupne elektronske baze podataka (PubMed, Google school i Cohrane review) kako bismo identifikovali studije koje su odgovarale unapred zadatim kriterijumima. Kvalitativnu procenu studija koje su selektovane za kliničku meta-analizu vršili smo pomoću REMARK kriterijuma. U skopu meta-analize izračunali smo kombinovani indeks rizika (eng.hazard ratio-HR) sa 95% intervalom poverenja (eng. confidence interval-CI) koristeći AR negativne pacijentkinje kao referentnu vrednost. Drugi deo mata-analize se odnosi na podatke dobijene ekpresijom gena (eng. gene-expression) dostupnih kroz setove podataka mikroareja (eng. microarray) pacijentkinja sa KD i poznatim ishodom bolesti. Koristeći PAM50 molekularni klasifikator (eng. molecular classifier) odredili smo molekularne podtipove KD. Ispitivali smo korelaciju AR iRNK sa kliničko-patološkim varijablama, drugim individualnim genima i genskim zapisima (eng. gene signatures) i kliničkim ishodom...Androgen receptor (AR) expression has been observed in about 70% of breast cancer (BC) patients, but its prognostic role is not yet established. Aim: To evaluate prognostic role of androgen receptor in patients with early breast cancer. Methods: To assess the prognostic role of AR in breast cancer we performed a metaanalysis of studies that evaluated the impact of AR on disease free survival (DFS) and/or overall survival (OS) in patients with early stage BC. Eligible studies were identified by systematic review of electronic databases using the MeSH terms "breast neoplasm" and "androgen receptor". Evaluable studies were selected after a qualitative assessment based on the REMARK criteria. We report combined Hazard Ratios (HRs) with 95% confidence intervals (CI) using AR negative patients as a reference. In addition, we conducted an in-silico pooled analysis of publicly available microarray data sets, from patients with early stage BC with known gene expression profiling and clinical outcome. By using PAM50 molecular classifier we assigned patients to molecular subtypes. We explored correlations of AR mRNA levels with clinico-pathological variables, other individual genes and gene signatures and clinical outcome. Results: 22 out of 33 eligible studies for the clinical meta-analysis, including 10.004 patients, were considered as evaluable for the current study after the qualitative assessment..