Physiological and biochemical aspects of propagation in endemic species Micromeria pulegium (Rochel) Benth. and Micromeria croatica (Pers.) Schoot in vitro

aromatičnih biljaka koje se koriste u tradicionalnoj medicini, hortikulturi, hemijskoj, prehrambenoj i kozmetičkoj industriji. Retke, endemične i/ili ugrožene vrste familije Lamiaceae predstavljaju poseban izazov za proučavanje, prevashodno u cilju očuvanja specijskog diverziteta i njihovih populacija u prirodi, ali i zato što su izvor važnih bioaktivnih molekula raznovrsnog dejstva (antimikrobna, antvirusna, fungicidna, antioksidantna, citotoksična, alelohemijska, insekticidna aktivnost, itd.) i potencijalno široke primene. Usled izrazite heterogenosti, predstavnici roda Micromeria su bili često predmet taksonomskih diskusija. Pripadnike sekcije Pseudomelissa gde spada i М. pulegium, nakon molekularno genetičkih analiza hloroplastne DNK, Brauchler (2005) premešta u rod Clinopodium. Ipak, u ovoj tezi je primenjen tradicionalni taksonomski koncept, predložen od strane Harley-a i sar. (2004), koji podržava homogenost roda Micromeria, pri čemu je sect. Pseudomelissa njegova sastavna jedinica. U skladu sa primenjenim sistemom dve istraživane vrste su klasifikovane u idividualne sekcije roda: Micromeria sect. Micromeria (M. croatica), odnosno Micromeria sect. Pseudomelissa (M. pulegium). Micromeria pulegium predstavlja endemičnu vrstu Južnih Karpata u Rumuniji, sa enklavom u istočnoj Srbiji, a Micromeria croatica balkansku endemičnu vrstu čiji se areal vezuje pre svega za planinski venac Dinarida. Njihove prirodne populacije imaju mali broj jedinki i nastanjuju staništa koja su pod negativnim uticajem antropogenih faktora. Imajući u vidu značaj roda Micromeria, kao i činjenicu da su pomenute vrste retke i ugrožene, javila se potreba da se one gaje zarad očuvanja i istraživanja bez pritiska na prirodne populacije i bez remećenja prirodnog genofonda. Iz pomenutih razloga obe vrste roda Micromeria uvedene su kulturu biljnih tkiva in vitro. U ovoj disertaciji vršeno je ispitivanje efekata regulatora rastenja na morfogenezu i produkciju etarskih ulja endemičnih vrsta M. pulegium i M. croatica in vitro...Plants from Lamiaceae family are prominent representatives of the edible, medicinal or aromatic herbs used in traditional medicine, horticulture, chemical, cosmetic and food industry. The rare, endemic and/or threatened species from family Lamiaceae pose a special challenge for studying, primarily in order to preserve species diversity and their populations in the wild, but also as they are source material for important bioactive molecules with diverse activity (antimicrobial, antiviral, fungicidal, antioxidant, cytotoxic, allelochemical, insecticidal and other types of activity) and potential broad spectrum of use. Due to the pronounced heterogeneity, representatives of genus Micromeria used to be a common topic of taxonomic discussions. After the molecular-genetic analyses of chloroplast DNA, Brauchler (2005) has transferred the representatives of section Pseudomelissa, which includes М. pulegium, into the genus Clinopodium. However, this thesis is using the traditional taxonomic concept suggested by Harley et al. (2004), supporting the homogeneity of genus Micromeria, where sect. Pseudomelissa remains its integral unit. According to this system the two studied species were classified within the individual sections of the genus: Micromeria sect. Micromeria (M. croatica) and Micromeria sect. Pseudomelissa (M. pulegium). Micromeria pulegium represents an endemic species of Southern Carpathians in Romania, with an enclave in Eastern Serbia, while Micromeria croatica is an endemic Balkan species primarily connected with the mountain chain of Dinarides. Their natural populations are characterized by a small number of individuals inhabiting habitats under the negative influence of anthropogenic factors. Due to the importance of genus Micromeria and the fact that these two species are rare and threatened, a need arose to grow them in captivity so they may be preserved and studied without additional pressure on natural populations and without disturbance of the natural gene pool. For these reasons both species of genus Micromeria were introduced in plant tissue culture in vitro..

Comparative Analysis of Different Methods for Graphene Nanoribbon Synthesis

Graphene nanoribbons (GNRs) are thin strips of graphene that have captured the interest of scientists due to their unique structure and promising applications in electronics. This paper presents the results of a comparative analysis of morphological properties of graphene nanoribbons synthesized by different methods. Various methods have been reported for graphene nanoribons synthesis. Lithography methods usually include electron-beam (e-beam) lithography, atomic force microscopy (AFM) lithography, and scanning tunnelling microscopy (STM) lithography. Sonochemical and chemical methods exist as well, namely chemical vapour deposition (CVD) and anisotropic etching. Graphene nanoribbons can also be fabricated from unzipping carbon nanotubes (CNTs). We propose a new highly efficient method for graphene nanoribbons production by gamma irradiation of graphene dispersed in cyclopentanone (CPO). Surface morphology of graphene nanoribbons was visualized with atomic force and transmission electron microscopy. It was determined that dimensions of graphene nanoribbons are inversely proportional to applied gamma irradiation dose. It was established that the narrowest nanoribbons were 10-20 nm wide and 1 nm high with regular and smooth edges. In comparison to other synthesis methods, dimensions of graphene nanoribbons synthesized by gamma irradiation are slightly larger, but the yield of nanoribbons is much higher. Fourier transform infrared spectroscopy was used for structural analysis of graphene nanoribbons. Results of photoluminescence spectroscopy revealed for the first time that synthesized nanoribbons showed photoluminescence in the blue region of visible light in contrast to graphene nanoribbons synthesized by other methods. Based on disclosed facts, we believe that our synthesis method has good prospects for potential future mass production of graphene nanoribbons with uniform size, as well as for future investigations of carbon nanomaterials for applications in optoelectronics and biological labeling

Physiological and biochemical aspects of propagation in endemic species Micromeria pulegium (Rochel) Benth. and Micromeria croatica (Pers.) Schoot in vitro

aromatičnih biljaka koje se koriste u tradicionalnoj medicini, hortikulturi, hemijskoj, prehrambenoj i kozmetičkoj industriji. Retke, endemične i/ili ugrožene vrste familije Lamiaceae predstavljaju poseban izazov za proučavanje, prevashodno u cilju očuvanja specijskog diverziteta i njihovih populacija u prirodi, ali i zato što su izvor važnih bioaktivnih molekula raznovrsnog dejstva (antimikrobna, antvirusna, fungicidna, antioksidantna, citotoksična, alelohemijska, insekticidna aktivnost, itd.) i potencijalno široke primene. Usled izrazite heterogenosti, predstavnici roda Micromeria su bili često predmet taksonomskih diskusija. Pripadnike sekcije Pseudomelissa gde spada i М. pulegium, nakon molekularno genetičkih analiza hloroplastne DNK, Brauchler (2005) premešta u rod Clinopodium. Ipak, u ovoj tezi je primenjen tradicionalni taksonomski koncept, predložen od strane Harley-a i sar. (2004), koji podržava homogenost roda Micromeria, pri čemu je sect. Pseudomelissa njegova sastavna jedinica. U skladu sa primenjenim sistemom dve istraživane vrste su klasifikovane u idividualne sekcije roda: Micromeria sect. Micromeria (M. croatica), odnosno Micromeria sect. Pseudomelissa (M. pulegium). Micromeria pulegium predstavlja endemičnu vrstu Južnih Karpata u Rumuniji, sa enklavom u istočnoj Srbiji, a Micromeria croatica balkansku endemičnu vrstu čiji se areal vezuje pre svega za planinski venac Dinarida. Njihove prirodne populacije imaju mali broj jedinki i nastanjuju staništa koja su pod negativnim uticajem antropogenih faktora. Imajući u vidu značaj roda Micromeria, kao i činjenicu da su pomenute vrste retke i ugrožene, javila se potreba da se one gaje zarad očuvanja i istraživanja bez pritiska na prirodne populacije i bez remećenja prirodnog genofonda. Iz pomenutih razloga obe vrste roda Micromeria uvedene su kulturu biljnih tkiva in vitro. U ovoj disertaciji vršeno je ispitivanje efekata regulatora rastenja na morfogenezu i produkciju etarskih ulja endemičnih vrsta M. pulegium i M. croatica in vitro...Plants from Lamiaceae family are prominent representatives of the edible, medicinal or aromatic herbs used in traditional medicine, horticulture, chemical, cosmetic and food industry. The rare, endemic and/or threatened species from family Lamiaceae pose a special challenge for studying, primarily in order to preserve species diversity and their populations in the wild, but also as they are source material for important bioactive molecules with diverse activity (antimicrobial, antiviral, fungicidal, antioxidant, cytotoxic, allelochemical, insecticidal and other types of activity) and potential broad spectrum of use. Due to the pronounced heterogeneity, representatives of genus Micromeria used to be a common topic of taxonomic discussions. After the molecular-genetic analyses of chloroplast DNA, Brauchler (2005) has transferred the representatives of section Pseudomelissa, which includes М. pulegium, into the genus Clinopodium. However, this thesis is using the traditional taxonomic concept suggested by Harley et al. (2004), supporting the homogeneity of genus Micromeria, where sect. Pseudomelissa remains its integral unit. According to this system the two studied species were classified within the individual sections of the genus: Micromeria sect. Micromeria (M. croatica) and Micromeria sect. Pseudomelissa (M. pulegium). Micromeria pulegium represents an endemic species of Southern Carpathians in Romania, with an enclave in Eastern Serbia, while Micromeria croatica is an endemic Balkan species primarily connected with the mountain chain of Dinarides. Their natural populations are characterized by a small number of individuals inhabiting habitats under the negative influence of anthropogenic factors. Due to the importance of genus Micromeria and the fact that these two species are rare and threatened, a need arose to grow them in captivity so they may be preserved and studied without additional pressure on natural populations and without disturbance of the natural gene pool. For these reasons both species of genus Micromeria were introduced in plant tissue culture in vitro..

Raman spectroscopy of graphene nanoribbons synthesized by longitudinal unzipping of multiwall carbon nanotubes

Graphene nanoribbons (GNRs) were synthesized by longitudinal unzipping of multiwall carbon nanotubes (MWCNTs), and changes in Raman spectra were followed. Transmission electron microscopy was used to investigate the longitudinal opening of carbon nanotubes. Height and height profiles of GNRs are observed by atomic force microscopy. Considering that GNRs are carbon-based material, we conducted a detailed Raman spectroscopy study of this new material. Raman measurements were performed at three different laser excitational lines: 532, 633 and 785 nm. We noticed a considerable increase in the ratio between D and G bands compared to the same parameter for MWCNTs. The contribution of the edge structure is much higher in GNRs than in the structure of pristine MWCNTs, which is a main reason for the high increase in structural disorder. It was also noticed that the intensity of the 2D band was significantly lower compared to the same band in the Raman spectra of pristine MWCNTs.4th International School and Conference on Photonics, Aug 26-30, 2013, Belgrade, Serbi

Gamma ray assisted fabrication of fluorescent oligographene nanoribbons

In this paper, facile low cost method for production of oligographene nanoribbons is presented. Nanoribbons are produced by gamma ray assisted cutting of oligographene dispersed in cyclopentanone. Width and height of the smallest nanoribbons are 30 and 1 nm, respectively. Due to the presence of a small number of defects introduced by gamma irradiation, nanoribbons are photoluminescent in the UV and blue region of the visible spectrum. (c) 2012 Elsevier Ltd. All rights reserved

Rapid thermal annealing of nickel-carbon nanowires for graphene nanoribbons formation

In this paper, we present a novel method for graphene nanoribbons formation using nickel nanowires as templates. Modification of electrochemical procedure for nickel nanowires synthesis was introduced by implementing graphene quantum dots as a carbon source. Thus, nickel nanowires with graphene quantum dots were prepared. These wires were exposed to rapid thermal annealing at high temperatures (500 degrees C, 700 degrees C and 800 degrees C). During this process carbon atoms dissolve in metal and precipitate to the nickel surface forming nickel-carbon nanowires. Atomic force microscopy, scanning electron microscopy and Raman spectroscopy were characterization methods used for analysis of changes in nickel-carbon nanowires properties depending on the different annealing temperatures. After etching nickel with nitric acid, graphene nanoribbons with average diameters of 32 nm and average lengths of 4 mu m were obtained. (C) 2016 Elsevier B.V. All rights reserved

Comparison of structural properties of pristine and gamma irradiated single-wall carbon nanotubes: Effects of medium and irradiation dose

A systematic study of the gamma irradiation effects on single wall carbon nanotube (SWCNT) structure was conducted. Nanotubes were exposed to different doses of gamma irradiation in three media. Irradiation was carried out in air, water and aqueous ammonia. Thermogravimetric analysis (TGA), Fourier transform infrared spectroscopy (FTIR), elemental analysis (EA) and Raman spectroscopy confirmed the changes in the SWCNT structure. TGA measurements showed the highest percentage of introduced groups for the SWCNTs irradiated with 100 kGy. FTIR spectroscopy provided evidence for the attachment of hydroxyl, carboxyl and nitrile functional groups to the SWCNT sidewalls. Those groups were confirmed by EA. All irradiated SWCNTs had hydroxyl and carboxyl groups irrelevant to media used for irradiation, but nitrile functional groups were only identified in SWCNTs irradiated in aqueous ammonia. Raman spectroscopy indicated that the degree of disorder in the carbon nanotube structure correlates with the irradiation dose. For the nanotubes irradiated with the dose of 100 kGy, the Raman I-D/I-G ratio was three times higher than for the pristine ones. Atomic force microscopy showed a 50% decrease in nanotube length at a radiation dose of 100 kGy. Scanning and transmission electron microscopies showed significant changes in the morphology and structure of gamma irradiated SWCNTs. (C) 2012 Elsevier Inc. All rights reserved

Graphene quantum dots inhibit T cell-mediated neuroinflammation in rats

We investigated the therapeutic capacity of nano-sized graphene sheets, called graphene quantum dots (GQD), in experimental autoimmune encephalomyelitis (EAE), an animal model of immune-mediated central nervous system (CNS) damage. Intraperitoneally administered GQD (10 mg/kg/day) accumulated in the lymph node and CNS cells of Dark Agouti rats in which EAE was induced by immunization with spinal cord homogenate in complete Freund's adjuvant. GQD significantly reduced clinical signs of EAE when applied throughout the course of the disease (day 0–32), while the protection was less pronounced if the treatment was limited to the induction (day 0–7 post-immunization) or effector (from day 8 onwards) phase of the disease. GQD treatment diminished immune infiltration, demyelination, axonal damage, and apoptotic death in the CNS of EAE animals. GQD also reduced the numbers of interferon-γ-expressing T helper (Th)1 cells, as well as the expression of Th1 transcription factor T-bet and proinflammatory cytokines tumor necrosis factor, interleukin-1, and granulocyte-macrophage colony-stimulating factor in the lymph nodes and CNS immune infitrates. The protective effect of GQD in EAE was associated with the activation of p38 and p42/44 mitogen-activated protein kinases (MAPK) and Akt in the lymph nodes and/or CNS. Finally, GQD protected oligodendrocytes and neurons from T cell-mediated damage in the in vitro conditions. Collectively, these data demonstrate the ability of GQD to gain access to both immune and CNS cells during neuroinflammation, and to alleviate immune-mediated CNS damage by modulating MAPK/Akt signaling and encephalitogenic Th1 immune response. © 2018 Elsevier Lt