Institute for Physics

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    Item type:Publication,
    SN-38 loading capacity of hydrophobic polymer blend nanoparticles: formulation, optimization and efficacy evaluation
    (Informa UK Limited, 2017-03)
    Dimchevska, Simona
    ;
    Geskovski, Nikola
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    Petruševski, Gjorgji
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    Chacorovska, Marina
    ;
    Popeski-Dimovski, Riste
    One of the most important problems in nanoencapsulation of extremely hydrophobic drugs is poor drug loading due to rapid drug crystallization outside the polymer core. The effort to use nanoprecipitation, as a simple one-step procedure with good reproducibility and FDA approved polymers like Poly(lactic-co-glycolic acid) (PLGA) and Polycaprolactone (PCL), will only potentiate this issue. Considering that drug loading is one of the key defining characteristics, in this study we attempted to examine whether the nanoparticle (NP) core composed of two hydrophobic polymers will provide increased drug loading for 7-Ethyl-10-hydroxy-camptothecin (SN-38), relative to NPs prepared using individual polymers. D-optimal design was applied to optimize PLGA/PCL ratio in the polymer blend and the mode of addition of the amphiphilic copolymer Lutrol®F127 in order to maximize SN-38 loading and obtain NPs with acceptable size for passive tumor targeting. Drug/polymer and polymer/polymer interaction analysis pointed to high degree of compatibility and miscibility among both hydrophobic polymers, providing core configuration with higher drug loading capacity. Toxicity studies outlined the biocompatibility of the blank NPs. Increased in vitro efficacy of drug-loaded NPs compared to the free drug was confirmed by growth inhibition studies using SW-480 cell line. Additionally, the optimized NP formulation showed very promising blood circulation profile with elimination half-time of 7.4 h.
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    Item type:Publication,
    Effect of vegetable fat on the texture, colour and sensory properties of Macedonian white brined cheese
    (Croatian Dairy Union, 2020-12-14)
    Sulejmani, Erhan
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    Beqiri, Lavdrim
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    Popeski-Dimovski, Riste
    <jats:p>This study aimed to investigate the influence of substitution of milk fat with palm fat on the composition, yield and technological quality of White cheese, a Macedonian traditional cheese. In this study, full-fat white brined cheese was used as a control sample (WC), while experimental cheeses were prepared from cow milk with vegetable fat (WV) addition and low-fat cheese (WL), respectively. The cheeses have been analysed for physicochemical (acidity, pH, fat, fat acidity, protein), instrumental texture and colour properties (L, a, b) as well as the sensory properties after 1, 20 and 60 days. WV cheeses showed a significantly (P<0.05) lower degree of pH and higher titratable acidity than the WC and WL cheese samples. Cheese that contained vegetable fat showed lower degrees of lipolysis, as assessed by the acid-degree value and received significantly (P<0.05) better appearance, highest hardness value (5226.98 N) and cheese yield scores compared to other samples.</jats:p>
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    Item type:Publication,
    Tunable high-Q resonator by general impedance converter
    (AIP Publishing, 2021-02-01)
    Mifune, Toshiro
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    Mishonov, Todor M.
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    Serafimov, Nikola S.
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    Dimitrova, Iglika M.
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    Popeski-Dimovski, Riste
    <jats:p>A tunable high-Q resonator is performed in the schematics of the General Impedance Converter (GIC). In the framework of frequency dependent open-loop gain of operational amplifiers, a general formula of the frequency dependence of the impedance of GIC is derived. The explicit formulas for the resonance frequency and Q-factor include as an immanent parameter the crossover frequency of the operational amplifier. Voltage measurements of GIC with a lock-in amplifier perfectly agree with the derived formulas.</jats:p>