Pub Date : 2023-09-15DOI: 10.59277/romrepphys.2023.75.705
A. TOLEA, C. GRECU, I.A. MOLDOVAN, V.E. TOADER
"In the absence of earthquakes, seismic stations continuously record the Earth's vibrations, called ambient seismic noise (ASN). The main concern regarding the ASN records is improving the seismic data quality using different tools developed especially for this purpose. Power Spectral Densities (PSD) and their corresponding Probability Density Functions (PDF) are tools used to evaluate the station performance and reveal the noise level at the station’s site. For high frequencies (>1 Hz), the noise sources are from cultural activities and show diurnal variation, while for low frequencies (<1 Hz), the noise is generated by natural sources and shows seasonal variation. In this study, we analyzed the vertical components of the Bucovina array seismic network (BURAR) to characterize the noise levels at the stations and investigate noise variations in space and time. We computed four-year spectrograms for some elements of the array that revealed an increase of ASN in the 2–5 Hz frequency range during the warmer seasons, contrary to the colder months. On the other hand, at lower frequencies (0.5–1 Hz), the power of seismic noise increases during the year’s colder months. We examined the relationship between noise levels and weather parameters (e.g., wind speed) for the station where the seismic sensor is collocated, with a weather station. We observed that an increase in wind speed leads to an increase in the noise level at high frequencies (> 2 Hz)."
{"title":"Seismic noise analysis in the microseismic and high-frequency domain at the BURAR seismic stations","authors":"A. TOLEA, C. GRECU, I.A. MOLDOVAN, V.E. TOADER","doi":"10.59277/romrepphys.2023.75.705","DOIUrl":"https://doi.org/10.59277/romrepphys.2023.75.705","url":null,"abstract":"\"In the absence of earthquakes, seismic stations continuously record the Earth's vibrations, called ambient seismic noise (ASN). The main concern regarding the ASN records is improving the seismic data quality using different tools developed especially for this purpose. Power Spectral Densities (PSD) and their corresponding Probability Density Functions (PDF) are tools used to evaluate the station performance and reveal the noise level at the station’s site. For high frequencies (>1 Hz), the noise sources are from cultural activities and show diurnal variation, while for low frequencies (<1 Hz), the noise is generated by natural sources and shows seasonal variation. In this study, we analyzed the vertical components of the Bucovina array seismic network (BURAR) to characterize the noise levels at the stations and investigate noise variations in space and time. We computed four-year spectrograms for some elements of the array that revealed an increase of ASN in the 2–5 Hz frequency range during the warmer seasons, contrary to the colder months. On the other hand, at lower frequencies (0.5–1 Hz), the power of seismic noise increases during the year’s colder months. We examined the relationship between noise levels and weather parameters (e.g., wind speed) for the station where the seismic sensor is collocated, with a weather station. We observed that an increase in wind speed leads to an increase in the noise level at high frequencies (> 2 Hz).\"","PeriodicalId":49588,"journal":{"name":"Romanian Reports in Physics","volume":"43 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2023-09-15","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"135486606","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"物理与天体物理","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2023-09-15DOI: 10.59277/romrepphys.2023.75.604
M.-E. BARBINTA-PATRASCU, C. NICHITA, S. ANTOHE
"This study reports an interesting idea to convert aqueous extracts of invasive terrestrial plants [Johnsongrass (Sorghum halepense L.) and Knotgrass (Polygonum aviculare L.)] into valuable silver nanoparticles (AgNPs), and used them against aquatic weeds (Cladophora). The phyto-generated AgNPs presented nano scaled dimension (estimated by DLS), and good antioxidant activities (evaluated by chemiluminescence technique). UV-Vis absorption spectroscopy confirmed the AgNPs phyto-development. The total polyphenols (TPC) and total flavonoid (TFC) contents of the aqueous herbal extracts and of AgNPs phyto-generated from them, revealed the major contribution of polyphenols and flavonoids to phyto-reduction of silver ions, and also, they are responsible for the antioxidant properties of the obtained samples. The bio impact of the prepared AgNPs against Cladophora depends on the AgNPs dose, and the time exposure. These findings could be useful in for various biomedical, agronomic, and biotechnological applications."
{"title":"Innovative strategy based on green nanotechnology for elimination and reduction of aquatic weeds","authors":"M.-E. BARBINTA-PATRASCU, C. NICHITA, S. ANTOHE","doi":"10.59277/romrepphys.2023.75.604","DOIUrl":"https://doi.org/10.59277/romrepphys.2023.75.604","url":null,"abstract":"\"This study reports an interesting idea to convert aqueous extracts of invasive terrestrial plants [Johnsongrass (Sorghum halepense L.) and Knotgrass (Polygonum aviculare L.)] into valuable silver nanoparticles (AgNPs), and used them against aquatic weeds (Cladophora). The phyto-generated AgNPs presented nano scaled dimension (estimated by DLS), and good antioxidant activities (evaluated by chemiluminescence technique). UV-Vis absorption spectroscopy confirmed the AgNPs phyto-development. The total polyphenols (TPC) and total flavonoid (TFC) contents of the aqueous herbal extracts and of AgNPs phyto-generated from them, revealed the major contribution of polyphenols and flavonoids to phyto-reduction of silver ions, and also, they are responsible for the antioxidant properties of the obtained samples. The bio impact of the prepared AgNPs against Cladophora depends on the AgNPs dose, and the time exposure. These findings could be useful in for various biomedical, agronomic, and biotechnological applications.\"","PeriodicalId":49588,"journal":{"name":"Romanian Reports in Physics","volume":"44 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2023-09-15","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"135486608","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"物理与天体物理","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2023-09-15DOI: 10.59277/romrepphys.2023.75.408
I.R. ANDREI, S. SIMION, F. GAROI, M. BULINSKI, M.L. PASCU
"We report secure data transmission performed using chaotic lasers with different external cavity geometries and applying the chaotic masking method based on subcarrier and phase modulations of the chaotic optical carrier. Two semiconductor lasers with similar multimode emission spectra and self-optical feedback provided, respectively, by ring and linear external cavities, were optically coupled and chaotically synchronized into a master – slave scheme. The transmitted message frequency modulates the radio frequency signal which modulates in phase the master chaotic carrier. Based on the robustness of the used encryption method and the synchronization characteristics of the two lasers, the decryption is conducted by the simple radio frequency spectrum monitoring of the slave emission."
{"title":"Optical cryptographic communications with non-identical chaotic laser systems","authors":"I.R. ANDREI, S. SIMION, F. GAROI, M. BULINSKI, M.L. PASCU","doi":"10.59277/romrepphys.2023.75.408","DOIUrl":"https://doi.org/10.59277/romrepphys.2023.75.408","url":null,"abstract":"\"We report secure data transmission performed using chaotic lasers with different external cavity geometries and applying the chaotic masking method based on subcarrier and phase modulations of the chaotic optical carrier. Two semiconductor lasers with similar multimode emission spectra and self-optical feedback provided, respectively, by ring and linear external cavities, were optically coupled and chaotically synchronized into a master – slave scheme. The transmitted message frequency modulates the radio frequency signal which modulates in phase the master chaotic carrier. Based on the robustness of the used encryption method and the synchronization characteristics of the two lasers, the decryption is conducted by the simple radio frequency spectrum monitoring of the slave emission.\"","PeriodicalId":49588,"journal":{"name":"Romanian Reports in Physics","volume":"2013 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2023-09-15","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"135486442","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"物理与天体物理","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2023-09-15DOI: 10.59277/romrepphys.2023.75.909
ADRIANA RADU, DANIELA STOICA, M. V. POPESCU, C. BERLIC, CRISTINA MIRON, V. BARNA
"Capillarity phenomena appear due to different molecular forces acting between fluid molecules located at the interface with either another fluid or a solid. The macroscopic description of the phenomenon can be done in terms of surface tension. In this paper, we determined the surface tension coefficient of aqueous solution of potassium permanganate by means of Jurin's law and also made diameter measurements and capillary ascents on images by using ImageJ software. Furthermore, we studied the capillary phenomena between two parallel and non- parallel plates. In the case of non-parallel plates, employing a special plugin of the ImageJ software, we determined the equation of the rectangular hyperbola drawn by the surface of liquid rising between plates. These experiments can be performed at elementary level and, additionally, used as a stimulus to discover more advanced topics."
{"title":"The study of capillarity phenomena by means of ImageJ software","authors":"ADRIANA RADU, DANIELA STOICA, M. V. POPESCU, C. BERLIC, CRISTINA MIRON, V. BARNA","doi":"10.59277/romrepphys.2023.75.909","DOIUrl":"https://doi.org/10.59277/romrepphys.2023.75.909","url":null,"abstract":"\"Capillarity phenomena appear due to different molecular forces acting between fluid molecules located at the interface with either another fluid or a solid. The macroscopic description of the phenomenon can be done in terms of surface tension. In this paper, we determined the surface tension coefficient of aqueous solution of potassium permanganate by means of Jurin's law and also made diameter measurements and capillary ascents on images by using ImageJ software. Furthermore, we studied the capillary phenomena between two parallel and non- parallel plates. In the case of non-parallel plates, employing a special plugin of the ImageJ software, we determined the equation of the rectangular hyperbola drawn by the surface of liquid rising between plates. These experiments can be performed at elementary level and, additionally, used as a stimulus to discover more advanced topics.\"","PeriodicalId":49588,"journal":{"name":"Romanian Reports in Physics","volume":"58 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2023-09-15","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"135486601","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"物理与天体物理","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
C Aştefănoaei, D Creangă, E Pretegiani, L M Optican, A Rufa
Saccadic eye movements of a normal subject were assessed through semi-quantitative analysis algorithms based on linear and non-linear test application in order to highlight the dynamics type characterizing saccadic neural system behavior. These movements were recorded during a simple visually-guided saccade test and one with a cognitive load involving button pressing to show a decision. Following the application of specific computational tests, chaotic dynamical trend dominancy was mostly revealed with some differences between the two saccade recording conditions: auto-correlation time was increased from 170 to 240 by cognitive task superposition and the Hurst exponent was enhanced from 0.52 to 0.76, denoting more persistence in the dynamics of saccadic system during increased neural activity related to cognitive task.
{"title":"DYNAMICAL COMPLEXITY ANALYSIS OF SACCADIC EYE MOVEMENTS IN TWO DIFFERENT PSYCHOLOGICAL CONDITIONS.","authors":"C Aştefănoaei, D Creangă, E Pretegiani, L M Optican, A Rufa","doi":"","DOIUrl":"","url":null,"abstract":"<p><p>Saccadic eye movements of a normal subject were assessed through semi-quantitative analysis algorithms based on linear and non-linear test application in order to highlight the dynamics type characterizing saccadic neural system behavior. These movements were recorded during a simple visually-guided saccade test and one with a cognitive load involving button pressing to show a decision. Following the application of specific computational tests, chaotic dynamical trend dominancy was mostly revealed with some differences between the two saccade recording conditions: auto-correlation time was increased from 170 to 240 by cognitive task superposition and the Hurst exponent was enhanced from 0.52 to 0.76, denoting more persistence in the dynamics of saccadic system during increased neural activity related to cognitive task.</p>","PeriodicalId":49588,"journal":{"name":"Romanian Reports in Physics","volume":"66 4","pages":"1038-1055"},"PeriodicalIF":2.7,"publicationDate":"2014-01-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://www.ncbi.nlm.nih.gov/pmc/articles/PMC4331081/pdf/nihms656971.pdf","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"33069278","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"物理与天体物理","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"OA","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
V. Barna, V. Vlad, A. Petris, I. Dancus, T. Bazaru, E. Barna, A. Luca, S. Ferjani, G. Strangi
Random lasing effects in fully disordered systems with organic and inorganic nature have been the subject of extensive studies since the beginning of the past decade. In multiple scattering materials the optical diffusion may induce a phase transition in the photon transport behavior. Beyond a critical scattering level, the system makes a transition into a strongly localized state and light transmission is therefore inhibited. This effect can be used as a photon trapping mechanism to obtain laser action in the presence of a gain medium. In this paper we present the first experimental evidence of random laser action in a dye doped nematic liquid crystal (ZLI-2659) with negative dielectric anisotropy. This material exhibits long-range dielectric tensor fluctuations, favoring the multiple scattering. When exceeding a certain threshold pump power value, the fluorescence curve in the system collapses and distinct sharp peaks emerge above the residual spontaneous emission spectrum. The laser emission has several interesting features - linewidth of the laser peaks is extremely narrow banded (approximately 0.5nm FWHM), very low threshold (30 µJ/mm 2 ), high efficiency (~ 20%). The unforeseen surviving of constructive interference in repeated multiple scattering events of the dye emitted photons provide the necessary optical feedback for lasing in our nematic liquid crystalline system. We analyze the main physical characteristics of these relatively novel phenomena, by also including here the case of various confinement geometries for the active medium. These scientific aspects overlook features of great interest characteristic of laser physics and material science.
{"title":"Efficient random laser effect in a new dye-nematic liquid crystalline composite","authors":"V. Barna, V. Vlad, A. Petris, I. Dancus, T. Bazaru, E. Barna, A. Luca, S. Ferjani, G. Strangi","doi":"10.5072/ZENODO.35094","DOIUrl":"https://doi.org/10.5072/ZENODO.35094","url":null,"abstract":"Random lasing effects in fully disordered systems with organic and inorganic nature have been the subject of extensive studies since the beginning of the past decade. In multiple scattering materials the optical diffusion may induce a phase transition in the photon transport behavior. Beyond a critical scattering level, the system makes a transition into a strongly localized state and light transmission is therefore inhibited. This effect can be used as a photon trapping mechanism to obtain laser action in the presence of a gain medium. In this paper we present the first experimental evidence of random laser action in a dye doped nematic liquid crystal (ZLI-2659) with negative dielectric anisotropy. This material exhibits long-range dielectric tensor fluctuations, favoring the multiple scattering. When exceeding a certain threshold pump power value, the fluorescence curve in the system collapses and distinct sharp peaks emerge above the residual spontaneous emission spectrum. The laser emission has several interesting features - linewidth of the laser peaks is extremely narrow banded (approximately 0.5nm FWHM), very low threshold (30 µJ/mm 2 ), high efficiency (~ 20%). The unforeseen surviving of constructive interference in repeated multiple scattering events of the dye emitted photons provide the necessary optical feedback for lasing in our nematic liquid crystalline system. We analyze the main physical characteristics of these relatively novel phenomena, by also including here the case of various confinement geometries for the active medium. These scientific aspects overlook features of great interest characteristic of laser physics and material science.","PeriodicalId":49588,"journal":{"name":"Romanian Reports in Physics","volume":"62 1","pages":"444-454"},"PeriodicalIF":2.7,"publicationDate":"1900-01-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"70791345","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"物理与天体物理","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
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