Sastav sterolne smese algi jadranskog mora Ulva lactuca, Codium dichotomum, Cystoseira adriatica i Fucus virsoides

The sterol composition of two green algae and two brown algae from the South Adriatic was determined. In the green alga Ulva lactuca, the principal sterols, were cholesterol and isofucosterol. In the brown alga Cystoseira adriatica, the main sterols were cholesterol and stigmast-5-en-3 beta-ol, while the characteristic sterol of the brown algae, fucosterol, was found only in low concentration. The sterol fractions of the green alga Codium dichotomum and the brown alga Fucus virsoides contained practically only one sterol each, comprising more than 90 % of the total sterols (clerosterol in the former and fucoserol in the latter).Određen je sastav sterolne smese dve zelene i dve mrke alge iz južnog Jadrana. U zelenoj algi Ulva lactuca glavni steroli su holesterol i izofukosterol. U mrkoj algi Cystoseira adriatica glavni steroli su holesterol i stigmast-5-en-3ß-ol, dok je fukosterol, sterol karakterističan za mrke alge, nađen samo u maloj količini. Sterolne smese zelene alge Codium dichotomum i mrke alge Fucus virsoides sastoje se praktično samo od po jednog sterola, klerosterola u prvoj i fukosterola u drugoj, koji sačinjavaju više od 90 % sterolnih frakcija

Metoda za određivanje uticaja DC struje na električne karakteristike SMD induktora

Prilikom proticanja DC (Direct Current) struje kroz induktor namenjen za površinsku montažu (SMD induktor), dolazi do namagnetisanja jezgra što dovodi do smanjivanja njegove induktivnosti i impedanse. Uočeno je da je ovo smanjivanje naročito izraženo kada vrednost DC struje koja protiče kroz induktor premašuje onu vrednost struje za koju proizvođač garantuje ispravan rad komponente. Zato je neophodno ispitati i predvideti stepen degradacije električnih karakteristika, kao i zavisnost gubitaka jezgra na promenu temperature tela testiranog induktora. Prikazana merna metoda predstavlja postupak ispitivanja uticaja DC struje na električne karakteristike induktora namenjenih za površinsku montažu. Analiza je bazirana na modelu induktora koji je prikazan kao dvokrajni model induktorske komponente. Za proračun električnih karakteristika induktora (induktivnost, otpornost, Q-faktor, realni i imaginarni deo impedanse) ekstrahovanih i izmerenih S-parametara primenom vektorskog analizatora mreže, korišćen je in-house softverski alat IndCalc

Chemical and biological properties of verapamil labeled with technetium-99m: A potential myocardial imaging agents

On the base of property to enter into myocardial cells as a calcium channel blocker, verapamil was labeled with technetium-99m in order to investigate the possibility to obtain new radiopharmaceutical for myocardial imaging. The conditions of labeling verapamil with technetium-99m for different ammounts of stannous(II) ion, mannitol, cystein and pH range 2.5-3.5 were examined. Investigation of radiochemical purity ( GT 95%) and biodistribution of (9)9mTc-verapamil in rats showed that it was stable during 2 hours after labeling. Accumulation of Tc-99m-verapamil in heart was 1.2% and in liver 9.4%, 5 minutes after injection. Biodistribution of Tc-99m-verapamil in rats in conditions of stress, pharmacologically caused by dipiridamol, showed that the elimination of Tc-99m-verapamil from the heart was slower related to the control group. In the group of rats previously treated with isoproterenol uptake of Tc-99m-verapamil in heart was lower related to the control group (0.7% versus 1.0%) 5 minutes after injection. Lipophilicity of (9)9mTc-verapamil was examined by determination of partition coefficient (log P = 0.62) and protein binding (79%). Imaging studies on dogs provided relatively good myocardial images with partially overlap of activity in the lung and liver

Influence of DC Bias on the Electrical Characteristics of SMD Inductors

As the dc bias flows through a ferrite chip surface mount device (SMD) inductor, it tends to premagnetize the core and reduce its inductance and impedance. It is observed that this drop is especially emphasized when the dc current exceeds the safety limit given by the manufacturer. Therefore, it is necessary to investigate and predict the degree of electrical characteristics degradation as well as the dependence of the core losses on core temperature. In this paper, a measurement technique for the investigation of the influence of dc bias on the electrical characteristics of SMD inductors (i.e., inductance, resistance, Q factor, and real and imaginary part of impedance) for printed circuit board applications is presented. Analysis is based on the model of the SMD inductor, which can be presented as a two-port equivalent circuit with intrinsic and extrinsic parameters. For calculation of the parameters of the SMD inductor, extracted from measured S-parameters using vector network analyzer, the in-house software tool IndCalc was used

Synthesis of nanostructured chitin-hematite composites under extreme biomimetic conditions

Chitin of poriferan origin is a unique and thermostable biological material. It also represents an example of a renewable materials source due to the high regeneration ability of Aplysina sponges under marine ranching conditions. Chitinous scaffolds isolated from the skeleton of the marine sponge Aplysina aerophoba were used as a template for the in vitro formation of Fe2O3 under conditions (pH similar to 1.5, 90 degrees C) which are extreme for biological materials. Novel chitin-Fe2O3 three dimensional composites, which have been prepared for the first time using hydrothermal synthesis, were thoroughly characterized using numerous analytical methods including Raman spectroscopy, XPS, XRD, electron diffraction and HR-TEM. We demonstrate the growth of uniform Fe2O3 nanocrystals into the nanostructured chitin substrate and propose a possible mechanism of chitin-hematite interactions. Moreover, we show that composites made of sponge chitin-Fe2O3 hybrid materials with active carbon can be successfully used as electrode materials for electrochemical capacitors