39 research outputs found
Nanoindentation of Za-27 Alloy Based Nanocomposites Reinforced with Al2O3 Particles
Nanoindentation has been widely used for material mechanical characterization. In this study, nanocompozite of ZA-27 alloy matrix reinforced with different volume fractions of nanometric Al2O3 ceramic particles ranging from 0 to 5 %, were produces using compocasting technique. Nanoindentation tests were performed using Berkovich three sided diamond pyramid, with maximum load of 100 mN and maximum load holding time of 15 s. Indentation imprints were investigated using optical and atomic force microscopy (AFM). Average particle size was 20-30 nm. Nanoindentation tests showed that nanocomposites have higher values of hardness and lower values of elastic modulus in comparison to the ZA-27 matrix alloy. Obtained results have different values in comparison to the theoretical investigations
Biohidrogelovi poli(metakrilne kiseline): bubrenje i kontrolisano otpuŔtanje kofeina
Modern society are faced with lot of challenges in the treatment of many diseases, especiallywith serious ones such as cancer. Safer and more efficient treatment of the cancer patients are maingoals which researchers are aiming. One of the good approaches can be drug delivery systems.Still, a lot of anticancer drugs are poorly water-soluble and their encapsulation and controlled releasecan be quite challenging. Present study is focused to improve drug delivery system based onhydrophilic poly(methacrylic acid) and amphiphilic casein with encapsulated poorly water-solublecaffeine, which has been developed through our previous research. The hydrogels with 1.6mol% ofcrosslinker and 100% of neutralization degree of methacrylic acid are synthetized (PMAC-100N-4M). The swelling process of the PMAC-100N-4M hydrogels and caffeine release are analyzed intwo environments which simulate human stomach and intestines. It is also investigated how thechange in the encapsulated caffeine weight and the addition of liposomes with encapsulated caffeine,affect swelling degree of the PMAC-100N-4M hydrogels and release of caffeine. The resultsshow that controlled release of caffeine is improved, therefore overall therapy can be enhanced.Savremeno druÅ”tvo je suoÄeno sa mnogim izazovima u tretamanu raznih bolesti, naroÄito ozbiljnih oboljenja kao Å”to je rak. Glavni ciljevi nauÄnika su da se postigne bezbednija i efikasnija terapija pacijenata koji se leÄe od raka. Jedan od dobrih naÄina da se to postigne su sistemi za dostavu lekova. Ipak, mnogi antikancerogeni lekovi su slabovodorastvorni, pa bi veliki izazov mogao da bude inakpsulacija i njihovo kontorlisano otpuÅ”tanje iz sistema za dostavu lekova. Cilj ovog rada je da se unapredi sistem za dostavu lekova na bazi hidrofilne poli(metakrilne kiseline) i amfifilnog kazeina sa inkapsuliarnim slabo vodorastvornim kofeinom, koji je razvijen tokom naÅ”eg prethodnog istraživanja. U ovom radu sintetisani su hidrogelovi sa 1,6mol% umreživaÄa i 100% neutralisanom metakrilnom kiselinom (PMAC-100N-4M). Procesi bubrenja PMAC-100N-4M hidrogelova i kontrolisanog otpuÅ”tanja kofeina su ispitivani u dve sredine koje simuliraju želudac i tanko crevo Äoveka. TakoÄe je ispitano kako promena koliÄine inkapsuliranog kofeina i dodatak lipozomne suspenzije sa inkapsuliranim kofeinom utiÄe na procese bubrenja PMAC-100N-4M hidorgelova i otpuÅ”tanje kofeina. Rezultati pokazuju da je proces kontrolisanog otpuÅ”tanje kofeina unapreÄen, a samim tim je moguÄe unaprediti i celokupnu terapiju
UltrazvuÄna ekstrakcija pektina iz otpadne jabuÄne kaÅ”e primenom eutektiÄkih rastvaraÄa na bazi holin hlorida
Pectin and pectin derived oligosaccharides can be obtained from waste apple pomace(biomass). Traditional method for pectin extraction involves use of diluted mineral acids atelevated temperatures, with yields of about 10 to 15%. As an alternative to conventionalmethods, the use of eutectic solvents is increasing because of their superior propertieswhen it comes to targeted extraction of certain components from biomass. The aim of thispaper is ultrasound assisted extraction of pectin from waste apple pomace using cholinechloride based eutectic solvents and lactic acid. Properties of extracted products wereexamined using FTIR spectroscopy and differential scanning calorimetry.Pektin i pektinski oligosaharidi mogu se dobiti iz otpadne jabuÄne kaÅ”e. Ovaj prirodni polimer ima Å”iroku primenu u industriji. Tradicionalna metoda za ekstrakciju pektina podrazumeva tretman razblaženim mineralnim kiselinama na poviÅ”enoj temperaturi, pri Äemu se prinosi ostvaruju od oko 10 do 15%. Kao alternativa tradicionalnim rastvaraÄima sve ÄeÅ”Äe se koriste i eutektiÄki rastvaraÄi, koje odlikuju daleko superiornija svojstva kada je reÄ o ciljanoj ekstrakciji odreÄenih komponenti iz biomase. Cilj ovog rada je ultrazvuÄna ekstrakcija pektina primenom eutektiÄkih rastvaraÄa na bazi holin hlorida i mleÄne kiseline. Svojstva ekstrahovanog proizvoda ispitana su primenom FTIR spektroskopije i diferencijalne skenirajuÄe kalorimetrije
The Effect of Glycol Derivatives on the Properties of Bio-Based Unsaturated Polyesters
The scope of the present study was to prepare fully bio-based unsaturated polyester resins (UPRs) with comparable properties to the commercial formulations. The focus was set on the determination of the optimal prepolymer formulation using the same set of diacids (itaconic and succinic acid) and different diols (propylene glycol, isosorbide and neopentyl glycol) or its equimolar mixtures, keeping the fixed molar ratio of 1:1:2.1 in all feed compositions. Instead of commonly used styrene, bio-based dimethyl itaconate was used as a reactive diluent (RD). The rheology of the obtained resins was studied in detail. The effect of the used diol on structural (FTIR), thermal (DSC), thermomechanical (DMA), and mechanical (tensile) properties was explained. The properties of UPRs were found to be highly dependent on the diol used in the prepolymer formulation. The UPR with an equimolar ratio of propylene glycol and neopentyl glycol was shown to be the most promising candidate to compete with the commercial petroleum-based resins
Electrochemical sensors based on pyrophyllite
V Conference of The Serbian Society for Ceramic Materials, 5CSCS-2019, June 11-13, 2019, Belgrade, Serbi
Natural Clay Pyrophyllite Activation with Silver and Composite Characterization
In this work, a hybrid pyrophyllite/AgNPs system was designed by mechanochemical activation of pyrophyllite, Al2Si4O 10(OH) 2. Tuning this systemās properties is especially important in terms of possible biomedical applications. The reaction was triggered by adding 2, 5, and 10wt% of silver in the form of AgNO3, indicating green synthesis of AgNPs. Thereby, the grinding time was adjusted from 20 to 320 minutes. The collected samples were analyzed by FTIR, XRD, SEM with EDX, TGA, DTA and PSD. The FTIR spectra of the pyrophyllite/AgNPs system showed the disappearance of some bands characteristic of pyrophyllite itself due to breaking of some bonds during the grinding, and the appearance of some new bands. SEM-EDS analysis confirmed that pyrophyllite structure changed during the mechanochemical treatment, indicating a homogeneous distribution of silver along the analyzed surface. PSD analysis showed that the average particle size distribution is approximately the same for all samples, despite the different wt% of silver. While XRD patterns of samples with 2 and 5 wt% of AgNO 3 did not show reflections originating from silver, the peak at 38.16Ė of the pyrophyllite sample milled for 20 minutes with 10 wt% of silver could be assigned to silver in the metal form. DTA curves of pyrophyllite/AgNO 3 samples milled for 20, 80 or 320 min had similar shapes for different silver content added. TGA curves of pyrophyllite/AgNO 3 samples milled for 20 min with 2, 5, and 10 wt% of silver showed a total weight loss of about 10% while for samples milled for 320 min reduced weight loss was observed due to the agglomeration of particles.Published in Bulletin of the Chemists and Technologistsof Bosnia and Herzegovina as Special Issue (2024)
Evaluation of Watson-like Integrals for Hyper bcc Antiferromagnetic Lattice
Watson-like integrals for a d-dimensional bcc antiferromagnetic lattice
I_d(\eta) and J_d(\eta) and another two similar integrals are evaluated in an
exact way in terms of generalized hypergeometric functions. A simple formula
connecting Id and Jd+1 is given along with the differential equations for
I_d(\eta) and J_d(\eta). An application of I_d and J_d in the theory of the
Heisenberg antiferromagnet is discussed, together with possible generalizations
to non-integer values of d. Corresponding integrals for sc lattices are also
briefly reviewed.Comment: 13 pages, 2 figures, Accepted for publication in Journal of Physics
A: Mathematical & Theoretical 201
Search for Dark Matter with CRESST
The search for direct interactions of dark matter particles remains one of
the most pressing challenges of contemporary experimental physics. A variety of
different approaches is required to probe the available parameter space and to
meet the technological challenges. Here, we review the experimental efforts
towards the detection of direct dark matter interactions using scintillating
crystals at cryogenic temperatures. We outline the ideas behind these detectors
and describe the principles of their operation. Recent developments are
summarized and various results from the search for rare processes are
presented. In the search for direct dark matter interactions, the CRESST-II
experiment delivers competitive limits, with a sensitivity below 5x10^(-7) pb
on the coherent WIMP-nucleon cross section.Comment: Accepted for publication in New Journal of Physics. 25 pages, 18
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