ДЕСОРПЦИЈА НА β-КАРОТЕН ОД БЕНТОНИТСКИ АТСОРБЕНТ ВО УСЛОВИ НА МИКРОБРАНОВА ИРАДИЈАЦИЈА

The desorption behavior of β-carotene from a bentonite adsorbent under microwave irradiation in isopropanol was studied as a function of temperature and different initial loading concentrations. A first-order, two-component, three-parameter model described the desorption kinetics with a coefficient of de-termination R2 > 0.9932, and the β-carotene desorption process under microwave irradiation was con-trolled by both rapid and slow desorption. The activation energies of β-carotene desorption for the rapid and slow desorption processes were 19.61 and 53.04 kJ mol-1, respectively. It was observed that the de-sorption equilibrium data fitted well to both the Freundlich and Langmuir isotherms. The data obtained from the desorption-isotherm model were used to determine the thermodynamic parameters. The positive value of free energy indicates the non-spontaneity of β-carotene desorption. The change in entropy rela-tive to the enthalpy of desorption reveals that the reaction is physical in nature.Десорпциското однесување на β-каротенот од бентонитски атсорбент беше истражувано во услови на микробранова ирадијација како функција на температурата и различни концентрации на полнењето. Кинтетички двокомпонентен модел од прв ред со три параметри ја опишува десорпциската кинетика со коефицинет на корелација R 2 > 0.9932. Десорпцискиот процес на βкаротенот во услови на микробранова ирадијација е контролиран и со брза и со бавна десорпција. Активациските енергии на десорпцијата на β-каротенот за брзата и за бавната десорпција соодветно изнесуваат 19,61 kJ mol–1 и 53,04 kJ mol–1 . Забележано е дека десорпциската рамнотежа добро се вклопува во изотермите на Freundlich и на Langmuir. Добиените податоци на моделот на десорпциската изотерма се употребени за определување на термодинамички параметри. Позитивната вредност на слободната енергија укажува на неспонтаност на десорпцијата на βкаротенот. Промената на ентропијата во однос на енталпијата укажува дека десопцијата по природа е физичка

Faktorijalni i ortogonalno centralno kompozitni plan eksperimenta kiselinske aktivacije smektita

The purpose of this study was to determine the effective operating parameters and the optimum operating conditions of an acid activation process within the framework of improvement of the process. Full two-level factorial and orthogonal central composite design methods were used successively. The examined parameters were the main and interaction effects of temperature, leaching time, acid normality, solid-to-liquid ratio and stirring rate. The selected process response was the leaching yield of the MgO content because Mg is the element most readily removed from the octahedral sheet, which affects the tendency for activation. Statistical regression analysis and analysis of variance were applied to the experimental data to develop a predictive model, which revealed that temperature, leaching time and acid normality exert the strongest influence on the specific surface area of smectite, whilst the solid-to-liquid ratio and the stirring rate have a secondary effect. Furthermore, the highest leaching yield of MgO was found to be 41.86 %, which is responsible for the increase in the specific surface area of up to 221 m2 g-1.Svrha ovog rada bila je određivanje efektivnih procesnih parametara i optimalnih procesnih uslova kiselinske aktivacije smektita iz Srbije. Uspešno su korišćene dve metode matematičkog modelovanja: pun faktorijalni i ortogonalni centralni kompozitni plan eksperimenta. Pri optimalnom planiranju eksperimenta istovremeno se menjaju svi parametri koji utiču na proces, što nam omogućava određivanje njihovog međusobnog uticaja i smanjenje ukupnog broja eksperimenata. Tokom planiranja eksperimenata razmatran je uticaj sledećih relevantnih parametara: temperature, vremena aktivacije, koncentracije kiseline, odnosa tečno/čvrsto i broja obrtaja mešalice, na stepen izdvajanja magnezijum-oksida. Rezultati optimizacije parametara kiselinske aktivacije smektita, na bazi statističkih planova eksperimenta, pokazali su da koncentracija kiseline, temperatura i vreme aktivacije imaju najjači uticaj na promenu specifične površine smektita, dok odnos tečno/čvrsto i broj obrtaja mešalice imaju sekundarni efekat. Maksimalni stepen izdvajanja magnezijum-oksida od 41,86 % uzrokuje i najveći porast specifične površine do 221 m2 g-1

The electrochemical behavior of ion-exchange cu-alumina

The aim of this study was to investigate the response of different alumina types modified by cooper. Two alumina oxyhydrates with different water content, 3mol H2O/ mol Al2O3 (gibbsite) 0.6 mol H2O/ mol Al2O3 (α,γ-alumina phase), were used in this study. Copper modified alumina samples were prepared by ion exchange with a solution of CuSO4*5H2O. Cu-alumina samples were dried at at 110 o C overnight. The obtained samples were used as modifiers of the carbon paste electrode. Their electrochemical response toward ferricyanide/ferrocyanide redox probe was evaluated by cyclic voltammetry and correlated with the type of alumina and the amount of copper in impregnated alumina. The possibility of the application of Cu-alumina as an electrochemical sensor was tested

Flat band potentials and photocatalytic activities of alumina/zirconia composite ceramics

Coupled oxide ceramic materials possess attractive properties, such as high surface areas, tunable pore size and shapes, various crystal structures, and a multitude of compositions, which endow them with potential applications in various areas of science and technology. Among these, porous zirconia-based ceramic materials, which can be considered as semiconductors with high band gap energy of ~5eV, have been the subject of intense research because of the potential new extensive use in photocatalytical degradation of organic pollutants. In the scope of this study mesoporous coupled alumina/zirconia composites were synthesized via the sol-gel method, followed by heat treatment at 500°C, for 5h. The XRD pattern of composites has shown that the addition of zirconia disrupts the crystallinity of alumina. The composites with higher zirconia content are characterized by peaks of the tetragonal zirconia phase. On the basis of the calculated flat band potentials from Mott-Schottky plots and optical band gaps, the conduction and valence band potentials were estimated for the composite semiconductors. Photocatalytic activity of synthesized samples in the process of degradation of trichlorophenol was obtained and correlated with band potentials and optical properties.X Serbian Ceramic Society Conference - Advanced Ceramics and Application : new frontiers in multifunctional material science and processing : program and the book of abstracts; September 26-27, 2022; Belgrad

Microinvasive cervical cancer in pregnancy

Cervical cancer is the most frequently diagnosed malignant disease in pregnancy. The clinical symptoms are scarce or none. The diagnosis is made primarily with a cervical smear, as well as a colposcopic examination and directed cervical biopsy. The treatment of cervical cancer depends on the stage of the disease, the gestation period, and a patient’s wish to carry a pregnancy to term. The illustrated case is of a patient who with the diagnosed presence of microinvasive squamous cell cancer, due to cervical biopsy, in the 1st trimester of pregnancy. In the 2nd trimester, diagnostic conization was performed in order to exclude the presence of the invasive disease. The definite histopathologic findings indicated the presence of cancer in situ. The conization margins were negative and thus the patient was successfully cured. The patient had a cesarean birth in the 36th week of pregnancy and she gave birth to an alive female newborn. Women are given the chance to have cervical cancer diagnosed and treated in the early stages of pregnancy owing to the introduction of a cervical smear in the modern protocol of antenatal protection

Flat band and photocatalytic activities of alumina/zirconia composite ceramics

In the scope of this study mesoporous coupled alumina/zirconia composites were synthesized via the sol-gel method, followed by heat treatment at 500°C, for 5h. The XRD pattern of composites has shown that the addition of zirconia disrupts the crystallinity of alumina. The composites with higher zirconia content are characterized by peaks of the tetragonal zirconia phase. On the basis of the calculated flat band potentials from Mott-Schottky plots and optical band gaps, the conduction and valence band potentials were estimated for the composite semiconductors. Photocatalytic activity of synthesized samples in the process of degradation of trichlorophenol was obtained and correlated with band potentials and optical properties

Application of Ni(II)-alumina Composites for Electrocatalytic Reduction of 4-nitrophenol

Nickel-alumina composites with various content of nickel were synthetized by sol-gel method. The characterization of samples was performed by diffuse reflectance spectroscopy and electrochemical impedance spectroscopy using the Mott-Schottky analysis. Glassy carbon electrode modified by synthesized composites was investigated for reduction of 4-nitrophenol. Modification of glassy carbon electrode with composite sample led to the strong apparent electrocatalysis. Principal component analysis was used to establish correlation between structural, textural and electrochemical data of investigated composites

IDIOPATHIC SCOLIOSIS FROM PSYCHOPATHOLOGICAL AND MIND-BODY MEDICINE PERSPECTIVES

Idiopathic scoliosis, defined as a three-dimensional spine and trunk deformity, which appears in otherwise healthy subjects, exhibits complex relations with various forms of personal well-being and psychopathology. Most research studies have documented a higher proportion of psychological disturbances (e.g., self-criticism, negative body image, low self-esteem) and mental disorders (e.g., anxiety and depressive disorders, personality disorders) among idiopathc scoliosis patients compared to healthy controls. In addition, there are some reports, although more systematic research is warranted, on the role of mental health and personality traits in relation to the adherence to conservative treatment. Given the increasing role of surgical treatment in the management of scoliosis, as well as several reports on negative psychological outcomes of such interventions, there is a growing need for ongoing screening and mental health care in this population. It seems this also holds true for non-operative treatments, particularly bracing therapy. One should keep in mind that these scoliosis-psychopathology relations are deduced from a limited number of empirical studies, usually conducted on small sample sizes, suggesting the need for further large-scale investigations, preferrably those with longitudinal research designs. Understanding the complex interplay between personality/psychopathology and spinal deformities within the framework of personalized mind-body medicine, should help clinicians tailor more individualized and specific treatments and predict therapeutic outcomes in this clinical population

Uticaj termičkog tretmana na mikro-strukturu alumine sa dodatkom PEG-a i La3+ dobijene sol-gel postupkom

Active porous alumina was prepared via a sol-gel method and subjected to thermal treatment in the temperature range 500 - 1200°C. The effect of calcinations temperature, polyethylen glycol combined with La3+, added to the boehmite sol, on activated alumina surface area, pore size, pore distribution and surface fractal dimension was studied. The N2 adsorption/desorption analyses of samples was performed to determine the adsorption isotherms, hysteresis and the textural properties. The adding of La3+ to boehmite sol inhibits the surface area loss of produced aluminas during its calcinations at high temperatures. Thermal treatment of La3+-doped alumina samples at temperature from 500 to 1200°C causes a considerable decrease of its specific surface area from 280 to 65 m2g-1, pore volume from 0,44 to 0,27 cm3g-1, increase of its pore size data from 3 to 6 nm and increase of its surface fractal dimension form 2,068 to 2,192. From behavior of surface fractal dimension of doped alumina samples can be concluded that there is no phase transformation to α-Al2O3 in all temperature range, i.e. addition of lanthanum to boehmite sol in atomic ratio of 0,03 La3+/Al3+ can raise phase transformation temperature to α-Al2O3 above 1200°C. .Aktivni porozni aluminijumoksid, dobijen sol - gel metodom, je termički obrađen na povišenim temperaturama u intervalu od 500 do 1200°C. Ispitivan je uticaj temperature termičke obrade i dodatka polietilen glikola (PEG) i La3+-jona na specifičnu površinu, zapreminu pora i prečnik pora, kao i fraktalnu dimenziju površine aktiviranog aluminijum-oksida. Na osnovu podataka iz adsorpciono-desorpcionih izotermi azota određen je tip pora i izračunate su vrednosti osnovnih parametara teksturalnih svojstava uzoraka. Porast temperature termičke obrade prouzrokovao je smanjenje specifične površine sa 280 na 65 m2g-1, zapremine pora sa 0,45 na 0,27 cm3g-1, porast preovlađujućeg prečnika pora od 3 do 6 nm i porast fraktalne dimenzije površine od 2,068 do 2,192. Na osnovu dobijenih rezultata rendgenostrukturne analize može se zaključiti da u ispitivanom temperaturnom intervalu ne dolazi do fazne transformacije u α-Al2O3 i da dodatak lantana u odnosu 0,03 molLa3+/ molAl3+ pomera faznu transformaciju aktiviranog aluminijum-oksida u α-Al2O3 iznad 1200°C.

Application of Zirconia/Alumina composite oxide ceramics as photocatalysts for removal of 2,4,6-trichlorophenol from water

The mesoporous zirconia/alumina composites were synthesized via a sol–gel method, followed by heat treatment at 500 ◦C for 5 h. The effect of the ZrO2/Al2O3 ratio on the structural and textural properties of the obtained composites was explored. Sorption analysis has confirmed that all samples have a mesoporous structure whose parameters (SBET, Vp and Dmax) strongly depend on the ZrO2/Al2O3 ratio. The XRD pattern of composites has shown that the addition of zirconia disrupts the crystallinity of alumina. The composites with higher zirconia content (50% ZrO2 and 67% ZrO2 ) are characterized by peaks related only to the zirconia phase. UV/Vis diffuse reflection spectra of all samples revealed that composites have more intensive absorption compared to pure oxides for wavelengths larger than 250 nm and similar band gaps. Photoluminescence measurements showed presence of defects in all samples, which are responsible for photocatalytic activity. All samples showed significant adsorption/photocatalytic efficacy for the removal/degradation of 2,4,6 -trichlorophenol (TCP). Results obtained using HPLC and TOC techniques showed that between 70 and 80% of the initial TCP concentration was removed/degraded after 4 h of illumination. These results were corelated with flat, conduction and valence band potentials of synthesized pure and binary oxides, calculated using Mott–Schottky plots