Analysis of quantum transport mechanisms in nanometarial based memristive devices

Истаживања у оквиру докторске дисертације имају за циљ да пруже допринос дубљем разумевању физичких механизама присутних код мемристора, с обзиром да у стручној литератури и даље постоје отворена питања везана за кључни процес који индукује мемристивни ефекат у материјалу. Као функционални материјал за меморије на бази промене валенце, на ком се испитује мемристивни ефекат, одабран је титанијум диоксид јер се већ показао као добар кандидат за резистивно-прекидачке меморије. Експериментални резултати показују ефекат квантизације проводности за ТiО2 мемристоре, што захтева развијање и примену модела балистичког транспорта за описивање електричних карактериристика узорка.Istaživanja u okviru doktorske disertacije imaju za cilj da pruže doprinos dubljem razumevanju fizičkih mehanizama prisutnih kod memristora, s obzirom da u stručnoj literaturi i dalje postoje otvorena pitanja vezana za ključni proces koji indukuje memristivni efekat u materijalu. Kao funkcionalni materijal za memorije na bazi promene valence, na kom se ispituje memristivni efekat, odabran je titanijum dioksid jer se već pokazao kao dobar kandidat za rezistivno-prekidačke memorije. Eksperimentalni rezultati pokazuju efekat kvantizacije provodnosti za TiO2 memristore, što zahteva razvijanje i primenu modela balističkog transporta za opisivanje električnih karakteriristika uzorka.Research topics in this PhD thesis aims to provide contribution in deeper understanding of physical mechanisms which drives resistive-switching mechanism in memristors, as existing literature provides open questions for key mechanism processes which influences memristive effect in materials. In order to test response of Valance Change Memories, TiO2 nanomaterial was used as the functional layer, as this material was already shown suitable for these applications. Measured results show conductance quantization effect for TiO2 based memristors, which requiers ballistic transport model for interpretation of electrical response of the device

Allelopathic influence of the extracts of weed species Abutilon theophrasti Med. and Xanthium strumarium L. on the crops of soybean and maize

 Kroz opšte, istorijske i okvire naučnih istraživanja, prvenstveno laboratorijskih ogleda, dat je presek nastanka, razvoja, današnjeg stanja i budućeg potencijala fenomena zvanog alelopatija. Potencijal alelohemikalija nameće potrebu analize biljaka jakog alelopatskog delovanja, identifikacije alelohemikalija, proučavanje njihovog mehanizma delovanja i njihove primene u biljnoj proizvodnji. Alelopatija se može odvojiti od ostalih mehanizama u okviru biljne zajednice jer je štetan efekat rezultat oslobađanja alelohemikalija i po tome se razlikuje od kompeticije. Alelopatija se smatra jednom od osnova održive poljoprivrede i zato je prioritetno područje istraživanja u razvijenim zemljama sveta. Cilj ovog istraživanja je bio da se utvrdi alelopatski uticaj ekstrakta korovskih vrsta Abutilon theophrasti Med. i Xanthium strumarium L. na inicijalni rast klijanca soje i kukuruza, kao i koncentracija ekstrakta ispitivanih korovskih vrsta koje imaju negativan uticaj na klijanje semena soje i kukuruza u laboratorijskim uslovima. U poljskim uslovima je cilj bio da se utvrdi koncentracija ispitivanih ekstrakata korovskih vrsta koja imaju negativan uticaj na prinos test biljaka, kao i da se odredi približna ocena broja individua po m2 sa potencijalnim negativnim uticajem na klijanje, nicanje i prinos useva soje i kukuruza. Ekstrakti korovske vrste A. theophrasti pripremljeni sa različitim rastvaračima su potvrdili značajno alelopatsko delovanje na procenat klijavosti soje i kukuruza. Etila-acetatni ekstrakt je izazvao najveći procenat klijavosti soje u najvećoj primenjenoj koncentraciji. Stimulativni efekat na dužinu podzemnog i nadzemnog dela klijanca soje su ispoljili tretmani sa vodenim i heksanolnim ekstraktom. Kod semena kukuruza, primena etil acetatnog ekstrakta A. theophrasti je dovela do najnižeg procenta klijavosti što ukazuje na inhibitoran alelopatski uticaj istog, zatim metanolni, dok su ostala tri ekstrakta (vodeni, heksanolni i butanolni) takođe potvrdili inhibitaran uticaj u sličnim procentima klijavosti. Dužina podzemnog i nadzemnog dela klijanca za sve primenjene ekstrakte je potvrdila alelopatsko delovanje ekstrakata. Najveći inhibitorni efekat je bio kod etil acetatnog ekstrakta na dužinu podzemnog i nadzemnog dela klijanca semena kukuruza. Primena ekstrakta korovske vrste X. strumarium je takođe potvrdila alelopatski uticaj na klijavost semena soje i kukuruza, kao i na dužinu nadzemnog i podzemnog dela klijanca. Izraziti inhibitorni efekat je konstatovan kod vodenog i metanolnog ekstrakta u sve četiri primenjene koncentracije ekstrakta. Kod heksanolnog ekstrakta u tri veće primenjene koncentracije (0,04-0,01g/ml) klijavost soje je bila ujednačena. Takođe, kod ovog ekstrakta je utvrđeno stimulativno delovanje na dužinu podzemnog dela klijanca soje, dok je na dužina nadzemnog dela pokazala izrazit inhibitorni efekat primenjenih koncentracija. Etil acetatni ekstrakt korovske vrste X. strumarium izazvao je klijavost soje od 100% u koncentraciji od 0,04 i 0,02 g/ml, dok je uz primenu dve niže koncentracije utvrđen manji procenat klijavosti. Međutim, dužina podzemnog dela klijanca je uz primenu koncentracije od 0,04 g/ml pokazala izrazit inhibitorni efekat, a primenom nižih koncentracija utvrđen je stimulativni efekat na dužinu podzemnog dela klijanca. Primena etil acetatnog ekstrakta je pokazala izrazit inhibitorni efekat u sve četiri primenjene koncentracije na dužinu nadzemnog dela klijanca soje. Ekstrakti korovske vrste X. strumarium su potvrdili alelopatsko delovanje na seme kukuruza u laboratorijskim uslovima. Najmanji procenat klijavosti su dala semena tretirana metanolnim ekstraktom, dok su najveću procentualnu klijavost imala semena tretirana heksanolnim ekstraktima. Priemena metanolnog i heksanolnog ekstrakta su pokazala inhibitoran efekat u svim primenjim koncentracijama na dužinu podzemnog i nadzemnog dela klijanca kukuruza. Kod primene najmanje koncentracije heksanolnog ekstrakta je utvrđen stimulativan efekat na dužina podzemnog dela klijanca kukuruza. Ogledi u poljskim uslovima su potvrdili rezultate dobijene u laboratorijskim uslovima. Usev soje tretiran vodenim ekstraktima korovske vrste A. theophrasti je umanjio prinos od 37,96-63,50%, dok je prinos kukuruza umanjen za 13,68-39,47%. Metanolni ekstrakt je takođe imao značajan alelopatski uticaj i smanjio je prinos za 21,05-37,37% kod useva kukuruza dok je kod soje procenat smanjenja prinosa bio za 42,34-60,58%. Prinos useva soje tretiran vodenim ekstraktima korovske vrste X. strumarium je smanjen za 40,88-45,26%, a prinos useva kukuruza je smanjen za 10,53-30,26% srazmerno primenjenim koncentracijama ekstrakta. Metanolni ekstrakt je smanjio visinu prinosa biljke za 20,26-36,32% kod useva kukuruza dok je kod useva soje procenat smanjenja prinosa bio za 48,91-56,20%.Aphenomenon called allelopathy has been examined and explained through general, historical and scientific frameworks of scientific researches, first of all laboratory experiments, providing data on its cross-section of origin, development, current condition and future potential. It is possible to distinguish allelopathy from other mechanisms of plant community since its harmful effect appears as a result of the release of allelochemicals. For this reason it is also different from its competition. Allelopathy is considered to be one of the bases of sustainable agriculture, thus becoming a priority field of study in developed countries. The aim of this research was to determine the allelopathic influence of the extract of weed species A. theophrasti and X.strumarium on the initial growth of soybean and maize germs, as well as to determine the concentration of extracts of the examined weed species that have a negative impact on the germination of soybean and maize in laboratory conditions. Within field conditions, the aim of the research was to determine the concentration of the examined extracts of weed species that have a negative impact on the yield of test plants, as well as to determine the number of the examined weed plants per m2 that have a negative impact on germination, emergence and yield of soybean and maize. The extracts of weed species A. theophrasti prepared with different solutions confirmed the existence of significant allelopathic influence on the percentage of germination of soybean and maize. Ethyl-acetate extract applied in the highest possible concentration caused the highest percentage of soybean germination. Treatments with water and hexanol extracts had a stimulating effect on the length of the underground and over-ground part of soybean germs. Ethyl-acetate extract of weed species A. theophrasti caused the lowest percentage of germination of maize. In other words, it confirmed the strong allelopathic influence of the extract. Methanol extract was next on the list, while the last three extracts (water, hexanol and butanol) also confirmed the similar percentage of germination under allelopathic influence. The length of the underground and over-ground part of germs for all the applied extracts confirmed their allelopathic influence. Ethyl-acetate extract had the highest inhibitory effect on the length of the underground and over-ground part of maize. The application of the extracts of weed species X. strumarium also confirmed the allelopathic influence on the germination of soybean and maize as well as on the underground and over-ground part of the seed germs. Water and methanol extracts had a highly inhibitory effect in all four applied concentrations. Hexan extract in three applied concentrations of larger amount (0,04-0,01 g/ml) caused equal germination of soybean. Also, it is determined that this extract has stimulating influence on the length of the underground part of soybean, while the same concentration had the significant inhibitory effect on the length of the over-ground part. Ethyl-acetate extract of weed species X. stumarium in concentration of 0,04 and 0,02 g/ml caused 100% of soybean germination, while two concentrations with the lower amount of extract caused a smaller percentage of germination. However, concentration of 0,04 g/ml had a strong inhibitory effect on the length of the underground part of germs, while smaller concentrations had a stimulating effect on the length of the underground part of germs. The length of the over-ground part of germs showed a strong inhibitory effect of all four applied concentrations. The extracts of weed species X. strumarium confirmed the allelopathic influence on maize in laboratory conditions. The seeds treated by methanol extract resulted in the lowest percentage of germination, while the seeds treated by hexanol extracts had the highest percentage of germination. The length of the underground and over-ground part of the germ of maize also confirmed the significant inhibitory influence. Application of the smallest concentration of hexanol extract had a stimulating effect on the length of the underground part of germs, confirmed by high germination of seeds treated by that concentration. Experiments done in field conditions confirmed the results obtained in laboratory conditions. Soybean treated by water extract of weed species A. theophrasti resulted in reduced yield in the amounts of 37,96-63,50%, while maize yield was reduced in the amount of 13,68-39,47%. Methanol extract also had a significant allelopathic influence, reducing yield from 21,05-37,37% in corn crops, while in soybean crops the percentage of reduced yield was from 42,34-60,58%. Yield of soybean treated by water extracts of weed species X. strumarium was reduced in the amounts of 40,88-45,26%, while yield of maize went down in the amount of 10,53-30,26% pro rata to applied concentrations of extracts. Methanol extract reduced the amount of plant yield from 20,26-36,32% in maize, while the percentag

Analyzing soil seed bank of invasive species in soil in nature protected area

The aim of this research was to determinate the number from invasive weed seeds in two protected areas. Soil sampling was carried out in north of Serbia Landscape of Outstanding Features Nature Park ‘’Palić’’and Nature Reserve ‘’Ludaško jezero’’. The depth at which samples were taken in each location was 0-10 cm. Weed seed bank from these two areas contained seeds of: Lolium multiflorum, Amaranthus retroflexus, Celtis occidentalis, Galinsoga parviflora, Vicia articulata, Setaria italica, Datura stramonium, Asclepias syriaca, Matricaria discoidea, Portulacae olaraceae, Veronica persica, Iva xanthifolia and Echinochloa crus-galli. Amaranthus retroflexus, Celtis occidentalis, Portulaca oleracea and Setaria italic were determinated in very large numbers at each protected location. The sampling of soil was done at two locations, with a probe of the same volume. Identifying the seeds and determining their quantity was carried out with microscopes and determiners

Modeling and Design of Passive Components for Flexible Electronics

In this paper, electromagnetic modeling of capacitors and inductors for printed electronic circuits is studied. Capacitors are successfully modeled by two-dimensional finite element software. Capacitive sensor for chemical detection is proposed and tested in water. Inductors are modeled by the integrating through the currents and obtained results have been compared with 3D finite element method. A capacitive sensor and an inductor on flexible substrate were fabricated. Simulation results have been validated through measurements

A Compact Inductive Position Sensor Made by Inkjet Printing Technology on a Flexible Substrate

This paper describes the design, simulation and fabrication of an inductive angular position sensor on a flexible substrate. The sensor is composed of meandering silver coils printed on a flexible substrate (Kapton film) using inkjet technology. The flexibility enables that after printing in the plane, the coils could be rolled and put inside each other. By changing the angular position of the internal coil (rotor) related to the external one (stator), the mutual inductance is changed and consequently the impedance. It is possible to determine the angular position from the measured real and imaginary part of the impedance, in our case in the frequency range from 1 MHz to 10 MHz. Experimental results were compared with simulation results obtained by in-house developed software tool, and very good agreement has been achieved. Thanks to the simple design and fabrication, smaller package space requirements and weight, the presented sensor represents a cost-effective alternative to the other sensors currently used in series production applications

Allelopathic properties of hemp

Allelopathic effects of different plant allelochemicals have become the focus of studies that aim to determine new pesticidal compounds. Plant extracts with different chemical compositions can be obtained using different methods of extraction, whereas studies dealing with allelopathic properties use biotests to obtain fast and precise results. Such studies were undertaken after noticing the allelopathic effects of industrial hemp (Cannabis sativa L.) on the surrounding crops. Trials that involve the application of hemp extracts obtained by different methods resulted in determining the hemp allelopathic effects on Stellaria media (L.)Scop., Beta vulgaris ssp. vulgaris var. vulgaris, Lupinus albus L., corn (Zea mays L.), Cyperus rotundus L., Matricaria recutita L., Lepidium sativum L., lettuce (Lactuca sativa L.), rapeseed (Brassica napus L.), wheat (Triticum aestivum L.), rye (Secale cereal M. Bieb.), Ambrosia artemisiifolia L., Chenopodium album L., and Sorghum halepense L

The influence xanthium strumarium l. extracts on maize yield

In several years lasting period occur great numbers of harmful organisms that cause decrease in crops yield. The most frequently occurring weed species cause great damages in agricultural crops, with potential yield loss of 34% [5]. They compete with the crops for water, space, light and nutrients and are hosts to insects and pathogens [8]. During 2014 allelopathic influence of Xanthium strumarium L. on maize yield (Zea mays L.) was studied in field conditions. Beside water extract from plant dry weight of the studied weed species, extract of methanol was also used in different concentrations. Concentrations of 0.04, 0.02, 0.01 and 0.004 g of the plant dry weight per 1 ml of solution were used. The required material was made from weed species picked up in 3-4 leaves phenophases. The reduced maize yield was established in fields in which water extracts, as well as methanol extracts were used. In comparison to untreated control variants, the reduced yield of 10.53-30.3% was established in treatments in which water extracts were applied. In relation to control plots, methanol treatments reduced yield for 20.26-36.32%

Allelopathic effect of Xanthium strumarium L. and Abuthilon theophrasti Med. extracts on germination of maize and soybean seed

During 2014 allelopathic effects of Xanthium strumarium L. and Abutilon theophrasti Med. extracts to germination and initial development of maize (Zea mays L.), and soybean (Glycine max L.) were studied in laboratory conditions. In addition to the Water extracts out of dry mass of the tested weed species, extracts made by use of hexane, ethyl acetate and methanol in different concentrations were also used. The applied concentrations were 10, 20, 30 and 40 g/l of dry matter made out of weed species in the 3-4 leaf stage of development. Inhibiting effect of water extract from dry matter of X. strumarium and methanol extract from which methanol part was evaporated to maize seed epicotyls and hypocotyls length was established. In comparison to the control, the maximum concentration of 40 g / l of the extract made from Water solution of A. theophrasti showed inhibitory effect on soybean seed epicotyls and hypocotyls length. The applied extracts made out of dry matter of the both of the studied weed species X. strumarium and A. theophrasti reduced maize seed germination for 14.8-26.83% and soybean seed germination for 18.5-35.82%, in comparison to the control in which it was 95% and 92%, respectively. After germination in a climate chamber, epicotyls’ and hypocotyls’ length of maize and soybean seeds was measured three, six and ten days following spraying by extracts

Uticaj ekstrakta Cannabis sativa na aktivnost gvajakol-peroksidaze u listovima Echinochloa crus-galli

Ispitivanje alelopatskih odnosa različitih biljnih ekstrakata na korovske vrste dobija sve veći značaj. Dobijeni rezultati se mogu koristiti za dalja istraživanja i dobijanje novih herbicidnih preparata. Utvrđeni alelopatski odnosi mogu biti značajni i za organizovanje plodoreda ili za zelenišno đubrenje- zaoravanjem useva sa izraženim alelopatskim dejstvom. Cilj istraživanja je bio da se utvrdi alelopatsko dejstvo ekstrakta Cannabis sativa L. (industrijske konoplje) na Echinochloa crus-galli (L.) P. Beauv. (proso korovsko), praćenjem aktivnosti gvajakol peroksidaze u listovima tretiranih biljaka. Rezultati ogleda su ukazali da su tretirane biljke E. crus-galli pretrpele stres nakon tretmana ekstraktom. Ekstrakt C. sativa dobijen procesom klasične ekstrakcije primenjen je u koncentracijama od 100%, 50%, 25% i 10%. Za kontrolnu varijantu su korišćene netretirane biljke. Biljke E. crus-galli su tretirane u početnim fazama rasta u poljskim uslovima

Antioxidant and Antiproliferative Activity of Allium ursinum and Their Associated Microbiota During Simulated in vitro Digestion in the Presence of Food Matrix

In this study, for the first time, the comprehensive analysis of antiproliferative and antioxidant activities of ramson, followed by the analysis of its associated microbiota and health-promoting effects of lactic acid bacteria (LAB), was performed. Ramson (Allium ursinum) is recognized as a medicinal plant with a long history of use in traditional medicine due to its antimicrobial and antioxidant activity. In this study the influence of in vitro gastrointestinal digestion on the cytotoxic activity of A. ursinum extracts against human malignant cell lines was demonstrated. Seven sulfur compounds, the degradation products of thiosulfinates, including diallyl disulfide were shown to inhibit proliferation of malignant cells by inducing accumulation within G2/M phase as well as to induce apoptosis through activation of caspase-3 and mitochondrial signaling pathway. Further, the A. ursinum microbiota, particularly LAB with potential probiotic effects, was analyzed by culture-dependent method and culture-independent method [denaturing gradient gel electrophoresis (DGGE)]. The obtained results revealed that the most abundant genera were Streptococcus, Lactobacillus, and Bacillus. The Lactobacillus genus was mainly represented by L. fermentum. The pulsed-field gel electrophoresis (PFGE) analysis revealed the presence of two PFGE pulsotypes. The probiotic potential of the strain L. fermentum BGSR163 belonging to PFGE pulsotype 1 and the strain L. fermentum BGSR227 belonging to the PFGE pulsotype 2 was characterized. The results revealed that both strains are safe for human use, successfully survive the simulated gastrointestinal conditions, have potential to transiently colonize the gastrointestinal tract (GIT) and have a protective immunomodulatory effect, inducing the production of proinflammatory cytokine IL17 and regulatory cytokine IL10, while decreasing the production of proinflammatory cytokine IFN-gamma. In conclusion, the results of this study suggest that consumption of A. ursinum might have health-promoting properties, including anticancer effects, while L. fermentum strains isolated from A. ursinum leaves could be used as probiotics for human consumption