This paper focuses on the interpretation of the natural components presents at different geosites in the Estrela UNESCO Global Geopark and on the analysis of soil erosion dynamics associated with ...trampling events in recent years. Three areas were evaluated: Salgadeiras - Covão da Clareza, Lagoa Seca and Covão do Boi. On there, UAV photogrammetry surveys were applied to obtain orthomosaics and dense clouds that then were used like background at the successive steps of the analysis. The high resolution of the point cloud and orthomosaics allowed us to identify and cartography the geology, hydrography, and vegetation features presents in each place. Besides all trampling sectors were mapped, establishing thus areas potentially vulnerable to environmental degradation because of walk-induced erosion. The analysis presented at this work evidenced an increase in the trampling areas in all the geosites considered, evidencing the potential of this tool like support for future sustainable management of protected areas.This research was supported by the Foundation for Science and Technology (FCT) within the scope of the project Avaliação de sistemas aéreos inteligentes de baixo-custo para mapeamento 3D da superficies of terrene (PTDC/EAM-REM/30475/2014) and by Estrela UNESCO Global Geopark.
Nowadays, the use of self-cleaning surfaces is increasing globally, especially after the COVID-2019 pandemic, and the use of nanoparticles has been shown as a plausible option for this purpose. In ...the present study, Cu-doped SnO2 nanocrystals were successfully synthesized (in the copper content range of 0–30 mol%) using the polymeric precursor method. The structural, morphological, vibrational, and antibacterial activity were carefully studied to unveil the effect of copper ions on the properties of the hosting matrix, aiming at maximizing the usage of Cu-doped SnO2 nanocrystals. The results show fabrication of nanoparticles near their respective exciton Bohr diameter (5.4 nm for SnO2), however, monophasic SnO2 was observed up to 15 mol%. Above this limit, a secondary CuO phase was observed, as shown by the assessed X-ray diffraction (XRD), Fourier transform infrared, and Raman spectroscopy data. Furthermore, the redshift of the primary A1g vibrational mode of SnO2 is successfully described using the phonon-confinement model, demonstrating a good relationship between the Raman correlation length (L) and the crystallite size (⟨D⟩), the latter determined from XRD. Regarding the antibacterial activity, assessed via the disc-diffusion testing method (DDTM) while challenging two bacterial species (S. aureus and E. coli), our results suggest a rapid diffusion of the nanoparticles out of the paper disc, with a synergistic effect credited to the Sn1−xCuxO2–CuO phases contributing to the inhibition of the bacteria growth. Moreover, the DDTM data scales with cell viability, the latter analyzed using the Hill equation, from which both lethal dose 50 (LD50) and benchmark dose (BMD) were extracted.
Background. Trichomoniasis is a sexually transmitted infection that mainly affects women. The diagnosis is made by different methods that identify the presence of Trichomonas vaginalis; therefore, ...sensitivity, specificity, and performance are essential to guarantee an adequate diagnosis. Our study is aimed at comparing three methods for diagnosing trichomoniasis in patients treated at a hospital in Peru during the year 2018. Methods. We designed a cross-sectional study and enrolled women whose vaginal secretion samples were evaluated by direct examination, Papanicolaou staining, and culture in the Diamond medium. Results. We evaluated 134 women with a mean age of 36.6±12.1 years and a beginning of sexual activity of 18.5±3.0 years. We found leukocyte infiltration, fetid odor, and strawberry cervix in 66.4%, 35.1%, and 18.7%. The prevalence of trichomoniasis by the culture method, direct examination, and Papanicolaou was 32.1, 21.6, and 11.2%. The direct examination’s sensitivity, specificity, and diagnostic performance (AUC) were 65.1%, 98.9%, and 82.0%, while for the Pap smear, they were 32.6%, 98.9%, and 65.7%%. Conclusion. The culture of T. vaginalis is the gold standard for diagnosing trichomoniasis; however, direct examination is a fast, specific alternative with good diagnostic performance. The Pap test has low sensitivity and should not be used in settings where the prevalence and risk factors for trichomoniasis are high.
We have designed and tested an automated simple setup for measuring the profile and spot size of a Gaussian laser beam, which exhibits a similar performance to ready-made optical devices, using three ...light sensors. We use a light dependent resistor as a novel instrument in this approach with good accuracy. We provide the setup in detail in order to be reproduced with the current technology at a standard laboratory. Two profiling techniques were implemented: the imaging technique for the CMOS 2D array (webcam) and scanning knife-edge-like technique using a single photodiode and a light dependent resistor. We apply up-to-date devices, such as a Raspberry Pi, for automation. The methods and sensors were compared to determine their accuracy using lasers of two different wavelengths and technologies. We verify that it is possible to use a webcam to determine the profile of a laser with 1% uncertainty on the beam waist, 1.5% error on the waistline position, and less than 3% error in determining the minimum spot radius. We show that it is possible to use a light dependent resistor to estimate the laser spot size with an 11% error. The photodiode measurement is the most stable since it is not affected by the change in laser intensity.
Abstract
Metal ternary nanoalloys or trimetallic nanoparticles have emerged, in recent years, as novel and relevant materials in different fields due to the synergy of three metals in a single system ...that leads to unique physicochemical properties as compared to mono- and bimetallic nanoparticles. In this study, the influence of composition on the structural and thermodynamic properties of Cu–Ag–Au nanoalloys with 5083 atoms is analyzed using molecular dynamics simulations. Relevant thermodynamic quantities are used to describe the melting and solidification behaviors of three models of Cu–Ag–Au nanoalloys. Our results indicate that the melting temperature presents linear and quadratic dependencies with the composition, i.e. for Cu
33
Ag
67
−
x
Au
x
, Ag
33
Cu
67
−
x
Au
x
, and Au
33
Ag
67
−
x
Cu
x
are
T
m
=
912.6
+
1.9
x
,
T
m
=
882.3
+
2.7
x
, and
T
m
=
1056.6
−
4.9
x
+
0.07
x
2
, respectively. In addition, most Ag atoms segregate to the surface and the Au and Cu atoms are localized in the center of the nanoalloy during the heating process, and this trend is maintained in the cooling process. The solidification temperature does not have an explicit correlation with the composition. Furthermore, the structural analysis of cooled nanoalloys exhibits local FCC and HCP symmetries, and the excess energy shows that Cu
33
Ag
27
Au
40
, Au
33
Ag
17
Cu
50
, and Ag
33
Cu
37
Au
30
are relatively more stable to form nanoalloys. Finally, the possibility of controlling the composition in these metal nanoalloys opens up potential applications in plasmonic, catalysis, and bactericidal (by Ag surface segregation) fields.
This study investigates the fabrication process of copper thin films via thermal evaporation, with precise control over film thickness achieved through
-position adjustment. Analysis of the ...as-fabricated copper films reveals a discernible relationship between grain size (〈
〉) and
-position, characterized by a phenomenological equation〈D〉XRDn(Z)=〈D〉0n1+32rZ2+158rZ4, which is further supported by a growth exponent (
) of 0.41 obtained from the analysis. This value aligns well with findings in the literature concerning the growth of copper films, thus underlining the validity and reliability of our experimental outcomes. The resulting crystallites, ranging in size from 20 to 26 nm, exhibit a resistivity within the range of 3.3-4.6
Ω · cm. Upon thermal annealing at 200 °C, cuprite Cu
O thin films are produced, demonstrating crystallite sizes ranging from ∼9 to ∼24 nm with increasing film thickness. The observed monotonic reduction in Cu
O crystallites relative to film thickness is attributed to a recrystallization process, indicating amorphization when oxygen atoms are introduced, followed by the nucleation and growth of newly formed copper oxide phase. Changes in the optical bandgap of the Cu
O films, ranging from 2.31 to 2.07 eV, are attributed mainly to the quantum confinement effect, particularly important in Cu
O with size close than the Bohr exciton diameter (5 nm) of the Cu
O. Additionally, correlations between refractive index and extinction coefficient with film thickness are observed, notably a linear relationship between refractive index and charge carrier density. Electrical measurements confirm the presence of a p-type semiconductor with carrier concentrations of ∼10
cm
, showing a slight decrease with film thickness. This phenomenon is likely attributed to escalating film roughness, which introduces supplementary scattering mechanisms for charge carriers, leading to a resistivity increase, especially as the roughness approaches or surpasses the mean free path of charge carriers (8.61 nm). Moreover,
calculations on the Cu
O crystalline phase to investigate the impact of hydrostatic strain on its electronic and optical properties was conducted. We believe that our findings provide crucial insights that support the elucidation of the experimental results. Notably, thinner cuprite films exhibit heightened sensitivity to ethanol gas at room temperature, indicating potential for highly responsive gas sensors, particularly for ethanol breath testing, with significant implications for portable device applications.
Nowadays, the use of self-cleaning surfaces is increasing globally, especially after the COVID-2019 pandemic, and the use of nanoparticles has been shown as a plausible option for this purpose. In ...the present study, Cu-doped SnO
2
nanocrystals were successfully synthesized (in the copper content range of 0–30 mol%) using the polymeric precursor method. The structural, morphological, vibrational, and antibacterial activity were carefully studied to unveil the effect of copper ions on the properties of the hosting matrix, aiming at maximizing the usage of Cu-doped SnO
2
nanocrystals. The results show fabrication of nanoparticles near their respective exciton Bohr diameter (5.4 nm for SnO
2
), however, monophasic SnO
2
was observed up to 15 mol%. Above this limit, a secondary CuO phase was observed, as shown by the assessed X-ray diffraction (XRD), Fourier transform infrared, and Raman spectroscopy data. Furthermore, the redshift of the primary A
1g
vibrational mode of SnO
2
is successfully described using the phonon-confinement model, demonstrating a good relationship between the Raman correlation length (
L
) and the crystallite size (〈
D
〉), the latter determined from XRD. Regarding the antibacterial activity, assessed
via
the disc-diffusion testing method (DDTM) while challenging two bacterial species (
S. aureus
and
E. coli
), our results suggest a rapid diffusion of the nanoparticles out of the paper disc, with a synergistic effect credited to the Sn
1−
x
Cu
x
O
2
–CuO phases contributing to the inhibition of the bacteria growth. Moreover, the DDTM data scales with cell viability, the latter analyzed using the Hill equation, from which both lethal dose 50 (LD50) and benchmark dose (BMD) were extracted.
The LAGO (Large Aperture GRB Observatory) in Peru Tueros-Cuadros, E.; Otiniano, L.; Chirinos, J. ...
Proceedings of the International Astronomical Union,
10/2011, Letnik:
7, Številka:
S286
Journal Article
Recenzirano
Odprti dostop
The Large Aperture GRBs Observatory is a continental-wide observatory devised to detect high energy (around 100 GeV) component of Gamma Ray Bursts (GRBs), by using the single particle technique in ...arrays of Water Cherenkov Detectors (WCDs) at high mountain sites of Argentina, Bolivia, Colombia, Guatemala, Mexico, Venezuela and Peru. Details of the instalation and operation of the detectors in Marcapomacocha in Peru at 4550 m.a.s.l. are given. The detector calibration method will also be shown.
Nowadays, the use of self-cleaning surfaces is increasing globally, especially after the COVID-2019 pandemic, and the use of nanoparticles has been shown as a plausible option for this purpose. In ...the present study, Cu-doped SnO
2
nanocrystals were successfully synthesized (in the copper content range of 0-30 mol%) using the polymeric precursor method. The structural, morphological, vibrational, and antibacterial activity were carefully studied to unveil the effect of copper ions on the properties of the hosting matrix, aiming at maximizing the usage of Cu-doped SnO
2
nanocrystals. The results show fabrication of nanoparticles near their respective exciton Bohr diameter (5.4 nm for SnO
2
), however, monophasic SnO
2
was observed up to 15 mol%. Above this limit, a secondary CuO phase was observed, as shown by the assessed X-ray diffraction (XRD), Fourier transform infrared, and Raman spectroscopy data. Furthermore, the redshift of the primary A
1g
vibrational mode of SnO
2
is successfully described using the phonon-confinement model, demonstrating a good relationship between the Raman correlation length (
L
) and the crystallite size (〈
D
〉), the latter determined from XRD. Regarding the antibacterial activity, assessed
via
the disc-diffusion testing method (DDTM) while challenging two bacterial species (
S. aureus
and
E. coli
), our results suggest a rapid diffusion of the nanoparticles out of the paper disc, with a synergistic effect credited to the Sn
1−
x
Cu
x
O
2
-CuO phases contributing to the inhibition of the bacteria growth. Moreover, the DDTM data scales with cell viability, the latter analyzed using the Hill equation, from which both lethal dose 50 (LD50) and benchmark dose (BMD) were extracted.
Tuning the physical properties of Cu-doped SnO
2
NPs to potential use as self-cleaning surfaces.
We analyze the performance of an Omnivision OV5647 CMOS image sensor (5 Mp) for measuring the radiation emitted from Sr90 and Cs137 sources. Our experimental arrangement includes a Raspberry Pi 3 ...mini-computer for data taking, processed with Python and OpenCV libraries. We specify the camera settings to be sensitive to detecting electrons and photons. We also implement a detailed Geant4 simulation of the CMOS sensor and the radioactive sources. This simulation connects the deposited energy in the pixel matrix by the electrons and photons from the radioactive sources and the ADC counts. Our measurements are expressed through the cluster size, the maximum ADC signal per cluster, and the variation of the clusters with different distances. We find a good agreement between the data and the Geant4 simulation for all these observables. Furthermore, we can reproduce the correlation between the cluster size and the maximum ADC per cluster.
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