E. Borisova, Tsanislava Genova, A. Khorovodov, A. Terskov, M. Kanevsky, A. Gisbrecht, L. Avramov, O. Semyachkina-Glushkovskaya
In the recent study delta-ALA/PpIX is used as fluorescent marker for tumor detection in stomach, small intestine and colon. 5-ALA was administered per os two hours before measurements at dose 20 mg/kg weight. Twenty laboratorial rats with developed neoplasia in gastrointestinal tract were used. Three of them formed control group - without application of exogenous 5-ALA/PpIX, as a contrast fluorescent marker. Their spectral properties were evaluated and used for correction of endogenous sources of fluorescence from stomach and intestine lesions detected. Macroscopic fluorescence spectroscopy parameters of gastrointestinal tissues of the other 17 animals, which were sensitized with 5- ALA?PpIX, were obtained on excitation at 405 nm. Excitation and emission light was delivered by fiberoptic probe 6+1 to the organs investigated in vivo during open surgery procedure on the laboratorial animals used. The fluorescence detected from tumor sites has very complex spectral origins. It consists of autofluorescence, fluorescence from exogenous fluorophores and re-absorption from the chromophores accumulated in the tissue investigated. Spectral features observed during endoscopic investigations could be distinct as the next regions: 450-630 nm region, where tissue autofluorescence is observed; 630-710 nm region, where fluorescence of PpIX is clearly pronounced; 530-580 nm region, where minima in the autofluorescence signal are observed, related to re-absorption of oxy-hemoglobin in this spectral area. The contrast achieved in normal vs. neoplastic gastrointestinal tissues was evaluated. Influence of endogenous 5-ALA/PpIX accumulation was taken into account; as well the role of inflammatory processes on the PpIX distribution and accumulation into the body was evaluated. Dimensionless ratio R=I635/I560 is evaluated as highly informative one for development of a simple algorithm for differentiation, which could has high diagnostic accuracy for evaluation of tumor vs. inflammatory vs. normal mucosa, using 1-D spectral results. Very good correlation between fluorescence data and histology examination of the lesions investigated was achieved as well.
{"title":"Stomach and intestine neoplasia fluorescence detection using 5-ALA/PpIX photosensitization","authors":"E. Borisova, Tsanislava Genova, A. Khorovodov, A. Terskov, M. Kanevsky, A. Gisbrecht, L. Avramov, O. Semyachkina-Glushkovskaya","doi":"10.1117/12.2516338","DOIUrl":"https://doi.org/10.1117/12.2516338","url":null,"abstract":"In the recent study delta-ALA/PpIX is used as fluorescent marker for tumor detection in stomach, small intestine and colon. 5-ALA was administered per os two hours before measurements at dose 20 mg/kg weight. Twenty laboratorial rats with developed neoplasia in gastrointestinal tract were used. Three of them formed control group - without application of exogenous 5-ALA/PpIX, as a contrast fluorescent marker. Their spectral properties were evaluated and used for correction of endogenous sources of fluorescence from stomach and intestine lesions detected. Macroscopic fluorescence spectroscopy parameters of gastrointestinal tissues of the other 17 animals, which were sensitized with 5- ALA?PpIX, were obtained on excitation at 405 nm. Excitation and emission light was delivered by fiberoptic probe 6+1 to the organs investigated in vivo during open surgery procedure on the laboratorial animals used. The fluorescence detected from tumor sites has very complex spectral origins. It consists of autofluorescence, fluorescence from exogenous fluorophores and re-absorption from the chromophores accumulated in the tissue investigated. Spectral features observed during endoscopic investigations could be distinct as the next regions: 450-630 nm region, where tissue autofluorescence is observed; 630-710 nm region, where fluorescence of PpIX is clearly pronounced; 530-580 nm region, where minima in the autofluorescence signal are observed, related to re-absorption of oxy-hemoglobin in this spectral area. The contrast achieved in normal vs. neoplastic gastrointestinal tissues was evaluated. Influence of endogenous 5-ALA/PpIX accumulation was taken into account; as well the role of inflammatory processes on the PpIX distribution and accumulation into the body was evaluated. Dimensionless ratio R=I635/I560 is evaluated as highly informative one for development of a simple algorithm for differentiation, which could has high diagnostic accuracy for evaluation of tumor vs. inflammatory vs. normal mucosa, using 1-D spectral results. Very good correlation between fluorescence data and histology examination of the lesions investigated was achieved as well.","PeriodicalId":355156,"journal":{"name":"International School on Quantum Electronics: Laser Physics and Applications","volume":"57 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2019-01-29","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"129743644","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
I. Agranovich, A. Khorovodov, M. Kanevsky, Tsanislava Genova-Hristova, A. Gisbrecht, I. Angelov, V. Mantareva, N. Navolokin, O. Semyachkina-Glushkovskaya, E. Borisova
In our study aluminium–phthalocyanine (AlPc) compounds were applied for exogenous fluorescent diagnostics of adenocarcinoma of stomach in laboratorial animals (male adult rats (n=50)) after application of an experimental model of adenocarcinoma formation with metastasis. The neoplastic lesions were developed under the influence of social stress, as well as chemical stress using nitrosamines during 9 months period of application. Significant fluorescence signal in the region of 670-700 nm was observed in the neoplastic lesions, which absent in the normal mucosa investigated, related to the fluorescence of accumulated in the tumour area phthalocyanines. Autofluorescence background covered region at 450-650 nm with a maximum of 480-520 nm and consists mainly of protein cross-links and co-enzymes - NADH and flavin signals. Endogenous porphyrins fluorescence was also observed in the lesions with a maximum at 630-640 nm. Other organs (liver, small bowel, lungs) were also investigated for a presence of metastases. Histology examination of the lesions was used as a “gold standard” for comparison of the spectral data. Visually, a presence of accumulation sites of AlPc in a form of bright pink patches after excitation at 405 nm was observed, vs. healthy tissue, which remained blue-violet due to autofluorescence signal. Thus allow to use the AlPc fluorescence discrimination not only in spectroscopic mode of detection, but for imaging of the lesions investigated, which is more preferable in the case of clinical applications during endoscopic observations in humans.
{"title":"Detection of stress-induced gastrointestinal lesions using Al-phythalocynanines in experimental animals","authors":"I. Agranovich, A. Khorovodov, M. Kanevsky, Tsanislava Genova-Hristova, A. Gisbrecht, I. Angelov, V. Mantareva, N. Navolokin, O. Semyachkina-Glushkovskaya, E. Borisova","doi":"10.1117/12.2516336","DOIUrl":"https://doi.org/10.1117/12.2516336","url":null,"abstract":"In our study aluminium–phthalocyanine (AlPc) compounds were applied for exogenous fluorescent diagnostics of adenocarcinoma of stomach in laboratorial animals (male adult rats (n=50)) after application of an experimental model of adenocarcinoma formation with metastasis. The neoplastic lesions were developed under the influence of social stress, as well as chemical stress using nitrosamines during 9 months period of application. Significant fluorescence signal in the region of 670-700 nm was observed in the neoplastic lesions, which absent in the normal mucosa investigated, related to the fluorescence of accumulated in the tumour area phthalocyanines. Autofluorescence background covered region at 450-650 nm with a maximum of 480-520 nm and consists mainly of protein cross-links and co-enzymes - NADH and flavin signals. Endogenous porphyrins fluorescence was also observed in the lesions with a maximum at 630-640 nm. Other organs (liver, small bowel, lungs) were also investigated for a presence of metastases. Histology examination of the lesions was used as a “gold standard” for comparison of the spectral data. Visually, a presence of accumulation sites of AlPc in a form of bright pink patches after excitation at 405 nm was observed, vs. healthy tissue, which remained blue-violet due to autofluorescence signal. Thus allow to use the AlPc fluorescence discrimination not only in spectroscopic mode of detection, but for imaging of the lesions investigated, which is more preferable in the case of clinical applications during endoscopic observations in humans.","PeriodicalId":355156,"journal":{"name":"International School on Quantum Electronics: Laser Physics and Applications","volume":"1 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2019-01-29","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"129760486","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
R. Nikov, N. Nedyalkov, A. Dikovska, D. Karashanova
The paper presents results on nanosecond laser ablation of ZnO nanostructures immersed in a liquid. The nanostructured ZnO samples were prepared in two steps. In the first one, a thin catalyst Au layer was deposited on the glass substrate by standard on-axis pulsed laser deposition (PLD) technique. In the next step, using again the PLD method, ZnO was deposited on the Au layer and thus the nanostructured ZnO samples were produced. The as-prepared samples were then immersed in double distilled water and irradiated by nanosecond laser pulses delivered by a Nd: YAG laser system at λ = 532 nm. Two different configurations of irradiation – against the structure and through the glass substrate – were used in the ablation in liquid experiments. The influence of the laser fluence for each of the ablation configurations used on the size, shape and optical properties of the obtained colloidal nanostructures was investigated. It was established optimal processing conditions, allowing transfer of the ZnO nanostructures from the substrate into the liquid medium. The nanostructures shape and size distribution were evaluated by means of transmission electron microscopy. Selected area electron diffraction was employed for chemical phase identification of the produced nanostructures. The colloids obtained were investigated by optical transmission spectroscopy in the near UV and in the visible region.
{"title":"Laser-assisted preparation of complex colloidal nanostructures by nanosecond ablation in liquid","authors":"R. Nikov, N. Nedyalkov, A. Dikovska, D. Karashanova","doi":"10.1117/12.2516648","DOIUrl":"https://doi.org/10.1117/12.2516648","url":null,"abstract":"The paper presents results on nanosecond laser ablation of ZnO nanostructures immersed in a liquid. The nanostructured ZnO samples were prepared in two steps. In the first one, a thin catalyst Au layer was deposited on the glass substrate by standard on-axis pulsed laser deposition (PLD) technique. In the next step, using again the PLD method, ZnO was deposited on the Au layer and thus the nanostructured ZnO samples were produced. The as-prepared samples were then immersed in double distilled water and irradiated by nanosecond laser pulses delivered by a Nd: YAG laser system at λ = 532 nm. Two different configurations of irradiation – against the structure and through the glass substrate – were used in the ablation in liquid experiments. The influence of the laser fluence for each of the ablation configurations used on the size, shape and optical properties of the obtained colloidal nanostructures was investigated. It was established optimal processing conditions, allowing transfer of the ZnO nanostructures from the substrate into the liquid medium. The nanostructures shape and size distribution were evaluated by means of transmission electron microscopy. Selected area electron diffraction was employed for chemical phase identification of the produced nanostructures. The colloids obtained were investigated by optical transmission spectroscopy in the near UV and in the visible region.","PeriodicalId":355156,"journal":{"name":"International School on Quantum Electronics: Laser Physics and Applications","volume":"6 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2019-01-29","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"122349299","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
We report on lidar detection and characterization of Saharan dust in the atmosphere above Sofia, Bulgaria, during the months of February in the years 2017 and 2018. Presented are results of aerosol measurements performed by using twochannel lidar based on a frequency-doubled pulsed Nd:YAG laser emitting at 1064 nm and 532 nm. We studied and characterized optical, geometrical, and dynamical properties of the registered aerosol fields. Vertical profiles of the atmospheric backscatter coefficient and color-coded diagrams in height-time coordinates based on range-corrected lidar signals are obtained in order to analyze the aerosol/dust layer density distribution and dynamics. Based on the retrieved backscatter profiles at the two lidar wavelengths, the corresponding vertical profiles of the backscatter-related Ǻngström exponents were calculated in order to characterize qualitatively the dominant particle-size fractions in the aerosol/dust layers observed. The lidar results obtained were combined with air-transport modelling and forecasting data in order to derive conclusions concerning the aerosol’s origin and type. It is shown that on the days of lidar observations meteorological conditions in Sofia region, as well as the vertical structure and aerosol composition of the near surface atmospheric layers, have been significantly influenced by the Saharan dust intrusions. Analyzing the aerosol Ångström exponent, an anomalous height distribution of the dust particle size fractions is ascertained and discussed. The results obtained confirm the tendency of increasing frequency of transporting considerable amounts of warm air masses from North Africa to Europe during the winter, indicating seasonal deviations in the air-intercontinental circulation systems. They also illustrate the potential of using lidar approaches to help monitor ongoing processes of local, regional, and global climate changes.
{"title":"Unusual wintertime transport of Saharan dust to Sofia, Bulgaria, detected by lidar","authors":"A. Deleva, Z. Peshev, L. Vulkova, T. Dreischuh","doi":"10.1117/12.2516540","DOIUrl":"https://doi.org/10.1117/12.2516540","url":null,"abstract":"We report on lidar detection and characterization of Saharan dust in the atmosphere above Sofia, Bulgaria, during the months of February in the years 2017 and 2018. Presented are results of aerosol measurements performed by using twochannel lidar based on a frequency-doubled pulsed Nd:YAG laser emitting at 1064 nm and 532 nm. We studied and characterized optical, geometrical, and dynamical properties of the registered aerosol fields. Vertical profiles of the atmospheric backscatter coefficient and color-coded diagrams in height-time coordinates based on range-corrected lidar signals are obtained in order to analyze the aerosol/dust layer density distribution and dynamics. Based on the retrieved backscatter profiles at the two lidar wavelengths, the corresponding vertical profiles of the backscatter-related Ǻngström exponents were calculated in order to characterize qualitatively the dominant particle-size fractions in the aerosol/dust layers observed. The lidar results obtained were combined with air-transport modelling and forecasting data in order to derive conclusions concerning the aerosol’s origin and type. It is shown that on the days of lidar observations meteorological conditions in Sofia region, as well as the vertical structure and aerosol composition of the near surface atmospheric layers, have been significantly influenced by the Saharan dust intrusions. Analyzing the aerosol Ångström exponent, an anomalous height distribution of the dust particle size fractions is ascertained and discussed. The results obtained confirm the tendency of increasing frequency of transporting considerable amounts of warm air masses from North Africa to Europe during the winter, indicating seasonal deviations in the air-intercontinental circulation systems. They also illustrate the potential of using lidar approaches to help monitor ongoing processes of local, regional, and global climate changes.","PeriodicalId":355156,"journal":{"name":"International School on Quantum Electronics: Laser Physics and Applications","volume":"14 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2019-01-29","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"122440989","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
I. Avramova, A. Dikovska, E. Valcheva, P. Terziiska, J. Mladenoff, L. Tzonev, S. Kolev, T. Milenov
Carbon exists in the form of many allotropes: zero-dimensional sp2 fullerenes, the two- dimensional (2D) sp2 honeycomb lattice of graphene (parent to graphite and carbon nanotubes), or three-dimensional (3D) sp3 crystals - diamond and lonsdaleite. Carbon can also exist in the form of carbine, a one dimensional (1D) infinite chain of sp1-hybridized carbon atoms. Each of them has notably different electronic and mechanical properties. Accordingly, it is highly important to correctly identify the hybridization state of carbon for the industrial application of these materials. It is well known that the phase ratio of sp2 and sp3 hybridized carbon is distinguishable by X-ray Photoelectron Spectroscopy (XPS) and especially by analysis of C1s lines. Here we report on a thorough XPS study of thin carbon films deposited by pulsed laser deposition (PLD). The studied films consist of a mix of carbon phases deposited on SiO2/(001)Si substrates. The obtained XPS results allows the optimization of PLD process parameters in order to synthesize single to few layered defected graphene/ graphene-like films.
{"title":"X-ray photoelectron spectroscopy characterization of amorphous and nanosized thin carbon films","authors":"I. Avramova, A. Dikovska, E. Valcheva, P. Terziiska, J. Mladenoff, L. Tzonev, S. Kolev, T. Milenov","doi":"10.1117/12.2516243","DOIUrl":"https://doi.org/10.1117/12.2516243","url":null,"abstract":"Carbon exists in the form of many allotropes: zero-dimensional sp2 fullerenes, the two- dimensional (2D) sp2 honeycomb lattice of graphene (parent to graphite and carbon nanotubes), or three-dimensional (3D) sp3 crystals - diamond and lonsdaleite. Carbon can also exist in the form of carbine, a one dimensional (1D) infinite chain of sp1-hybridized carbon atoms. Each of them has notably different electronic and mechanical properties. Accordingly, it is highly important to correctly identify the hybridization state of carbon for the industrial application of these materials. It is well known that the phase ratio of sp2 and sp3 hybridized carbon is distinguishable by X-ray Photoelectron Spectroscopy (XPS) and especially by analysis of C1s lines. Here we report on a thorough XPS study of thin carbon films deposited by pulsed laser deposition (PLD). The studied films consist of a mix of carbon phases deposited on SiO2/(001)Si substrates. The obtained XPS results allows the optimization of PLD process parameters in order to synthesize single to few layered defected graphene/ graphene-like films.","PeriodicalId":355156,"journal":{"name":"International School on Quantum Electronics: Laser Physics and Applications","volume":"19 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2019-01-29","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"133755665","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
J. Spigulis, A. Lihachev, V. Lukinsone, M. Osis, I. Oshina
The recent advancements of three laser-based diagnostic technologies developed at the Riga group are briefly reviewed: (i) RGB imaging of cw-laser excited skin autofluorescence intensity and photobleaching rate distributions, (ii) ps-laser excited skin autofluorescence and diffuse reflectance kinetics analysis, (iii) snapshot RGB skin chromophore mapping under triple-laser illumination. These techniques have passed preliminary laboratory and clinical tests which have demonstrated a promising potential for further implementation in portable devices for routine clinical applications. Operation principles, set-up schemes and some clinical results obtained by the above-mentioned techniques are discussed in this paper.
{"title":"Lasers for in-vivo skin diagnostics: some recent developments","authors":"J. Spigulis, A. Lihachev, V. Lukinsone, M. Osis, I. Oshina","doi":"10.1117/12.2516747","DOIUrl":"https://doi.org/10.1117/12.2516747","url":null,"abstract":"The recent advancements of three laser-based diagnostic technologies developed at the Riga group are briefly reviewed: (i) RGB imaging of cw-laser excited skin autofluorescence intensity and photobleaching rate distributions, (ii) ps-laser excited skin autofluorescence and diffuse reflectance kinetics analysis, (iii) snapshot RGB skin chromophore mapping under triple-laser illumination. These techniques have passed preliminary laboratory and clinical tests which have demonstrated a promising potential for further implementation in portable devices for routine clinical applications. Operation principles, set-up schemes and some clinical results obtained by the above-mentioned techniques are discussed in this paper.","PeriodicalId":355156,"journal":{"name":"International School on Quantum Electronics: Laser Physics and Applications","volume":"11 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2019-01-29","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"130363294","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
The foundations of quantum approach to describe of distortion and delay of GPS signal passing through the D and E atmosphere layers are proposed. The problem is reduced to resonant scattering of photons, moving in electromagnetic field produced by the transmitter, on the Rydberg complexes formed in the two-temperature non-equilibrium plasma. The following two processes are considered. First process leads to a forming the creation of additional photons due to stimulated emission and direct increase in the power of the received signal. The second one provides a shift the carrier frequency signal and time delay of its propagation. It happens due to the resonant scattering of Rydberg electron on the ion core and molecule of neutral medium in the intermediate autoionization states due to the non-adiabatic coupling of electronic and nuclear motions. The purpose of our message is to determine the connection of resulting frequency shift and delay time of the satellite signal with the quantum dynamics inside the Rydberg complex consisting of a highly excited molecule and molecule of neutral medium. We note that in one act of resonant photon scattering, the delay time in the intermediate state of the complex is 10-10 s, i.e. they are peculiar traps for the GPS signals. Under normal geomagnetic conditions the total delay time of the signal arriving at the receiver is Δτ ~ 10-7 s. Next factor to be taken into account is the additional background incoherent microwave radiation from Rydberg complexes leading to an increase in the signal/noise ratio.
{"title":"Delay of GPS signals in the D and E atmospheric layers: is the quantum theory applicable?","authors":"G. Golubkov, L. Eppelbaum, M. Manzhelii","doi":"10.1117/12.2516758","DOIUrl":"https://doi.org/10.1117/12.2516758","url":null,"abstract":"The foundations of quantum approach to describe of distortion and delay of GPS signal passing through the D and E atmosphere layers are proposed. The problem is reduced to resonant scattering of photons, moving in electromagnetic field produced by the transmitter, on the Rydberg complexes formed in the two-temperature non-equilibrium plasma. The following two processes are considered. First process leads to a forming the creation of additional photons due to stimulated emission and direct increase in the power of the received signal. The second one provides a shift the carrier frequency signal and time delay of its propagation. It happens due to the resonant scattering of Rydberg electron on the ion core and molecule of neutral medium in the intermediate autoionization states due to the non-adiabatic coupling of electronic and nuclear motions. The purpose of our message is to determine the connection of resulting frequency shift and delay time of the satellite signal with the quantum dynamics inside the Rydberg complex consisting of a highly excited molecule and molecule of neutral medium. We note that in one act of resonant photon scattering, the delay time in the intermediate state of the complex is 10-10 s, i.e. they are peculiar traps for the GPS signals. Under normal geomagnetic conditions the total delay time of the signal arriving at the receiver is Δτ ~ 10-7 s. Next factor to be taken into account is the additional background incoherent microwave radiation from Rydberg complexes leading to an increase in the signal/noise ratio.","PeriodicalId":355156,"journal":{"name":"International School on Quantum Electronics: Laser Physics and Applications","volume":"32 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2019-01-29","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"125738296","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
This paper presents a method for fabrication of oriented multicomponent nanowires composed by nanoparticles. The technology is based on nanosecond pulsed laser deposition of mixed target in the presence of an external magnetic field. The targets used for the ablation process consist of Fe2O3 and Ag2O with different ratio between them. The laser ablation is implemented in air at atmospheric pressure by using Nd:YAG laser system operated at 1064 nm. SEM analysis of the surface of the as-deposited samples reveals a presence of micrometric nanowires which are predominantly oriented in the direction of the magnetic field. These nanowires are composed by arranged nanoparticles formed in the plasma plume. The influence is investigated of the Fe2O3/Ag2O ratio in the target on the morphology and optical properties of the structures. Surface plasmon resonance band of Ag nanoparticles was observed in the transmission spectra of the samples with the highest Ag content. The material composition of the samples was identified by EDX and XRD analyzes. The obtained structures can find application in the fields of nanoelectronics, spintronics, magneto-optics and plasmonics.
{"title":"Fabrication of multicomponent nanowires by laser ablation of mixed target in a presence of magnetic field","authors":"R. Nikov, A. Dikovska, N. Nedyalkov, G. Avdeev","doi":"10.1117/12.2516641","DOIUrl":"https://doi.org/10.1117/12.2516641","url":null,"abstract":"This paper presents a method for fabrication of oriented multicomponent nanowires composed by nanoparticles. The technology is based on nanosecond pulsed laser deposition of mixed target in the presence of an external magnetic field. The targets used for the ablation process consist of Fe2O3 and Ag2O with different ratio between them. The laser ablation is implemented in air at atmospheric pressure by using Nd:YAG laser system operated at 1064 nm. SEM analysis of the surface of the as-deposited samples reveals a presence of micrometric nanowires which are predominantly oriented in the direction of the magnetic field. These nanowires are composed by arranged nanoparticles formed in the plasma plume. The influence is investigated of the Fe2O3/Ag2O ratio in the target on the morphology and optical properties of the structures. Surface plasmon resonance band of Ag nanoparticles was observed in the transmission spectra of the samples with the highest Ag content. The material composition of the samples was identified by EDX and XRD analyzes. The obtained structures can find application in the fields of nanoelectronics, spintronics, magneto-optics and plasmonics.","PeriodicalId":355156,"journal":{"name":"International School on Quantum Electronics: Laser Physics and Applications","volume":"28 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2019-01-29","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"128683792","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
I. Ryabtsev, I. Beterov, D. Tretyakov, E. Yakshina, V. Entin, C. Andreeva
We present a brief overview of the current state of the experimental research on the development of the element base of quantum computers with qubits based on single neutral atoms trapped in optical traps. The discussion focuses on the requirements for qubits, peculiarities of single neutral atoms as qubits, methods for the quantum register development and for the implementation of single-qubit quantum logic operations in the laser and microwave fields, and two-qubit operations through the dipole–dipole interaction after a short laser excitation of atoms to the Rydberg states. The results of the experiments on the observation of the interaction of two and three Rydberg atoms by a Förster resonance controlled by dc and radio-frequency electric field are presented.
{"title":"Rydberg atoms and quantum information","authors":"I. Ryabtsev, I. Beterov, D. Tretyakov, E. Yakshina, V. Entin, C. Andreeva","doi":"10.1117/12.2519368","DOIUrl":"https://doi.org/10.1117/12.2519368","url":null,"abstract":"We present a brief overview of the current state of the experimental research on the development of the element base of quantum computers with qubits based on single neutral atoms trapped in optical traps. The discussion focuses on the requirements for qubits, peculiarities of single neutral atoms as qubits, methods for the quantum register development and for the implementation of single-qubit quantum logic operations in the laser and microwave fields, and two-qubit operations through the dipole–dipole interaction after a short laser excitation of atoms to the Rydberg states. The results of the experiments on the observation of the interaction of two and three Rydberg atoms by a Förster resonance controlled by dc and radio-frequency electric field are presented.","PeriodicalId":355156,"journal":{"name":"International School on Quantum Electronics: Laser Physics and Applications","volume":"12 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2019-01-29","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"125426409","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
D. Ivanov, Tsanislava Genova-Hristova, E. Borisova, L. Nedelchev, D. Nazarova
The implementation of tissue polarimetry in medicine arises mainly for the need of non-invasive and highly sensitive discrimination between healthy and tumor tissues. This fast, relatively cheap method may be useful for better histological diagnostics by the physicians. Although, the most challenging goal is to apply tissue polarimetric optical system for in vivo measurements, initially one have to optimize the optical system using ex vivo histological samples, phantoms and etc. This paper is focused on the polarimetric parameters from lower gastrointestinal tract histological samples, by using polarized light with several wavelengths, namely 444 nm, 488 nm, 514 nm, 594 nm and 635 nm, detected and processed by commercially available polarimeter. Our experimental results reveal the best wavelength choice in favor of 635 nm for all colon samples used. Light with circular polarization was used in the experiments, as found to survive more scattering events, compared to linearly polarized light. Furthermore, circularly polarized light carries additional information about the phase difference between the two orthogonal components of the electric field (Ex and Ey) and in the case of reflection, the incident state of polarization undergoes a ip of its helicity. By this way, a better detection of histological changes in tissues, related to abnormal tissue structure can be made. Furthermore, the multiwavelength, polarimetric analysis may provide better insight for future in vivo implementation and the results from the ex vivo biological samples presented in this study, contribute to better discrimination based on optical measurements, applicable for tumor detection.
{"title":"Multiwavelength polarimetry of gastrointestinal ex vivo tissues for tumor diagnostic improvement","authors":"D. Ivanov, Tsanislava Genova-Hristova, E. Borisova, L. Nedelchev, D. Nazarova","doi":"10.1117/12.2516645","DOIUrl":"https://doi.org/10.1117/12.2516645","url":null,"abstract":"The implementation of tissue polarimetry in medicine arises mainly for the need of non-invasive and highly sensitive discrimination between healthy and tumor tissues. This fast, relatively cheap method may be useful for better histological diagnostics by the physicians. Although, the most challenging goal is to apply tissue polarimetric optical system for in vivo measurements, initially one have to optimize the optical system using ex vivo histological samples, phantoms and etc. This paper is focused on the polarimetric parameters from lower gastrointestinal tract histological samples, by using polarized light with several wavelengths, namely 444 nm, 488 nm, 514 nm, 594 nm and 635 nm, detected and processed by commercially available polarimeter. Our experimental results reveal the best wavelength choice in favor of 635 nm for all colon samples used. Light with circular polarization was used in the experiments, as found to survive more scattering events, compared to linearly polarized light. Furthermore, circularly polarized light carries additional information about the phase difference between the two orthogonal components of the electric field (Ex and Ey) and in the case of reflection, the incident state of polarization undergoes a ip of its helicity. By this way, a better detection of histological changes in tissues, related to abnormal tissue structure can be made. Furthermore, the multiwavelength, polarimetric analysis may provide better insight for future in vivo implementation and the results from the ex vivo biological samples presented in this study, contribute to better discrimination based on optical measurements, applicable for tumor detection.","PeriodicalId":355156,"journal":{"name":"International School on Quantum Electronics: Laser Physics and Applications","volume":"27 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2019-01-29","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"132492375","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
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