We consider a spacetime with a distortion of a vertical line into a vertical spiral, thus, we analyse non-relativistic effects on the interaction of a point charge with a uniform magnetic field in ...this spacetime background. In addition, we consider the topological defect spacetime with an internal flux. Then, we analyse the Aharonov-Bohm effect for bound states in the non-relativistic limit by confining the point charge to a hard-wall confining potential, two cylindrical surfaces with rigid walls and a cylindrical surface.
We propose an approach considering the nonextensive effects in the context of the Verlinde theory in order to address an extended cosmological model in the context of viscous dark energy. ...Specifically, this model leads to a tiny perturbation in the dynamics of the expansion of the universe through the generalized Friedmann equations so-called the extended ΛCDM model. From the observational test standpoint, we make a Bayesian analysis of the models of bulk viscosity for dark energy which follows the Eckart theory of bulk viscosity. These models are investigated through the context of both models ΛCDM and extended ΛCDM. The Bayesian analysis is performed using the data of CMB Distance priors, Baryon Acoustic Oscillations Measurements, Cosmic Chronometers, and SNe Ia distance measurements.
The role of scalar current coupling along surfaces Barone, F. A.; Borges, L. H. C.; Flores-Hidalgo, G. ...
European physical journal. C, Particles and fields,
03/2024, Letnik:
84, Številka:
3
Journal Article
Recenzirano
Odprti dostop
In this paper we propose a coupling between the complex scalar field and an external Dirac delta-like planar potential. The coupling is achieved through the Klein–Gordon current normal to the plane ...where the potential is concentrated. The results are obtained exactly and exhibit many peculiarities. We show that a complex scalar charge does not interact with the potential, but the potential modifies the interaction between two scalar charges if they are placed on opposite sides of the planar potential. When the coupling constant between the potential and the field goes to infinity, the classical field solutions satisfy a kind of MIT boundary conditions along the plane where the potential is concentrated.
Celotno besedilo
Dostopno za:
DOBA, IZUM, KILJ, NUK, PILJ, PNG, SAZU, SIK, UILJ, UKNU, UL, UM, UPUK
Given the rapid increase of species with a sequenced genome, the need to identify orthologous genes between them has emerged as a central bioinformatics task. Many different methods exist for ...orthology detection, which makes it difficult to decide which one to choose for a particular application. Here, we review the latest developments and issues in the orthology field, and summarize the most recent results reported at the third 'Quest for Orthologs' meeting. We focus on community efforts such as the adoption of reference proteomes, standard file formats and benchmarking. Progress in these areas is good, and they are already beneficial to both orthology consumers and providers. However, a major current issue is that the massive increase in complete proteomes poses computational challenges to many of the ortholog database providers, as most orthology inference algorithms scale at least quadratically with the number of proteomes. The Quest for Orthologs consortium is an open community with a number of working groups that join efforts to enhance various aspects of orthology analysis, such as defining standard formats and datasets, documenting community resources and benchmarking.
All such materials are available at http://questfororthologs.org.
The use of surface texturing on the rake face of a tool can modify the tribological phenomena present at the chip-tool interface. Many different wear mechanisms, including abrasive wear, occur at the ...tool during machining. The presence of hard phases in the workpiece material, as well as hard particles removed from the tool, can generate abrasive wear on the tool surfaces. The objective of this work is to study the abrasive wear resistance of micro-textured tools in comparison to conventional (commercial) cutting tools. Square cemented carbide inserts containing a three-layered coating (TiCN–Al2O3–TiN) were textured using two different linear patterns, perpendicular and parallel to the direction of the chip movement. Microabrasion and machining tests on both textured and commercial tools were carried out. Turning tests were carried out for ABNT/AISI 1050 steel under severe cutting conditions with overhead application of cutting fluid. In order to simulate the abrasive wear mechanism that can occur on the tool surface, a free ball microabrasion test was used under a suspension of silicon carbide particles and distilled water. The abrasive wear mechanisms were observed using SEM. The micro-scale abrasive wear resistance of laser micro-textured cement carbide tools was compared to untextured tools. For the turning tests, texturing increased the tool life, which was determined when the wear at the tool flank achieved a specified value. On the other hand, for the microabrasion tests, laser texturing resulted in a pronounced increase in the coating wear rate. This fact was connected to the decrease of coating hardness caused by laser texturing. Therefore, the increase of tool life in the turning tests was not related to a reduction of abrasive wear on the tool flank. Probably, it was caused by other tribological conditions that were not represented in microabrasion tests, for example: the presence of cutting fluid in the environment and elevated contact temperatures.
Topography control has been applied as strategy to improve the efficiency of lubricated systems by introducing specific textures to the surface. Surface texturing can significantly affect the ...lubrication regime, improving the system's efficiency and reducing wear of moving parts. The present work shows the effects of different topographies produced by electrochemical texturing on lubrication regime, and its effects on the wear resistance of the textured surfaces. The lubrication regime was described using the ratio of the lubricant film thickness by the rms roughness of the surfaces (λ parameter). The tests used a block-on-ring tribometer. Samples and rings were made of AISI 1045 steel and SAE 4620, respectively. Lubrication regimes ranged from mixed to boundary for normal loads of 216.9 N and 315 N, respectively. The effect of texture position (inlet and outlet) and relative orientation of the texture patterns were studied. The rotation speed was fixed in 1500 rpm. The lubricant temperature was monitored during the tests. In the case of boundary lubrication, partially textured surfaces and fully textured surfaces presented a reduction in the friction coefficient of 23% and of 9.4%, respectively, when compared to a reference smooth surface. The friction coefficient reduced 12.6% when texture was positioned in the inlet and 23% when positioned in the outlet, when compared to the smooth surface. Moreover, total texturing reduced the wear rate by 15.2%. Linear relationships between wear volume and λ parameter, as well as between friction coefficient and curvature radius were found, confirming a strong relationship between lubrication regime, wear rates and real contact area (given by the curvature radius of the wear tracks).
•Electrochemically textured surfaces were tested on block-on-ring lubricated test.•Surface texturing affects the lubrication regime improving the system's efficiency.•Friction coefficient reduced up to 23% when texture position was in the sample outlet.•Totally textured samples presented wear volume 15.2% lower than smooth samples.•A linear relationship between wear volume, λ parameter and curvature radius was found.
To synthesize novel more potent trypanocidal and leishmanicidal agents.
Hantzsch's synthetic strategy was used to synthesize 1,3-thiazole-4-carboxylates and their
-benzylated derivatives.
28 new ...thiazole-carboxylates and their
-benzylated derivatives were established to test their trypanocidal and leishmanicidal activities. From both series, compounds
,
,
,
and
exhibited a better or comparable trypanocidal profile to benznidazole. Among all tested compounds,
was found to be the most potent and was better than benznidazole.
Further variation of substituents around 1,3-thiazole-4-carboxylates and or hydrazinyl moiety may assist in establishing better and more potent trypanocidal and leishmanicidal agents.
We study the effect of Co co-doping on the optical properties of Mn-doped ZnTe nanocrystals (NCs) embedded in a glass matrix. Optical absorption (OA) and crystal field theory strongly indicated the ...substitutional incorporation of Co
2+
ions into these semiconducting NCs as well as the characteristic transitions of these ions in the visible and near infrared spectral region. Transmission electron microscopy (TEM) images revealed an invariant NC lattice parameter with the incorporation of Mn
2+
and Co
2+
ions. The same was confirmed by X-ray diffraction (XRD). The photoluminescence (PL) spectra showed that the characteristic emission bands of Co
2+
ions (
E
1Co
2+
and
E
2Co
2+
) are intense and evident at low temperatures. Indeed, Raman spectra showed that the dependence of luminescence intensity on temperature is due to the electron-phonon interaction that arises from multiphonon relaxation processes. The redshifts in the PL spectra from green to orange with the incorporation of Mn
2+
ions into ZnTe NCs, and in the near infrared with increasing Co-concentration, result from sp-d exchange interactions associated with the increase in Mn
2+
and Co
2+
ions in tetrahedral sites of ZnTe NCs, which may be very interesting for applications in luminescent devices. These observations provide strong evidence that higher Co-concentrations inhibit the incorporation of Mn
2+
into ZnTe NCs, suggesting that there may be competition between Co
2+
and Mn
2+
ions substituting Zn
2+
ions and, furthermore, that these ions replace zinc vacancies (V
Zn
) in these NCs.
We study the effect of Co co-doping on the optical properties of Mn-doped ZnTe nanocrystals (NCs) embedded in a glass matrix.
The present study reports on successful use of surface‐enhanced Raman spectroscopy to investigate itraconazole (ITZ) molecule loaded within poly(lactic‐co‐glycolic acid) (PLGA) nanoparticles (NPs). ...SER spectra were recorded by depositing samples onto a nanostructured silver film, which was fabricated via electrolyte deposition of silver NPs onto silver substrate. Transmission electron microscopy, dynamic light scattering, zeta potential, and Fourier transform infrared spectroscopy were employed to support our analyses. While compared with normal Raman spectrum of ITZ powder, changes observed in the SER spectra of the samples comprising ITZ‐loaded PLGA‐NPs (sample ITZ@PLGA‐NPs) and ITZ mixed with PLGA‐NPs (sample ITZ+PLGA‐NPs) provided insights regarding the interaction between the ITZ molecule and both the silver film's surface and the PLGA‐NPs. We found spectral evidences that free ITZ molecule (sample ITZ+PLGA‐NPs) interacts with the silver film's surface via the nitrogen heterocyclic closest to the ITZ's phenyl rings. In this condition, it was verified that the ITZ molecules are more likely oriented parallel to the silver film's surface. Additionally, the ITZ molecule in the ITZ@PLGA‐NPs sample is not adsorbed onto the silver film's surface likely due to steric hindrance provided by the PLGA template. Nevertheless, the SER spectrum of the ITZ@PLGA‐NPs sample shows the signature of the ITZ molecule (likely via the electromagnetic mechanism) and the PLGA template (via the surface adsorption mechanism). Moreover, the SER spectrum recorded from the ITZ@PLGA‐NPs sample indicates weak interaction between the loaded ITZ and the PLGA template. We anticipate that the pioneering approach herein introduced can be successfully used to investigate a wide variety of bioactive molecules encapsulated within polymeric templates, thus providing a very promising, sensitive, and robust analytical tool not yet explored in this regard.
Loading of itraconazole (ITZ) molecules within poly(lactic‐co‐glycolic acid) (PLGA) nanoparticles was studied by surface‐enhanced Raman spectroscopy. The data showed that despite effective encapsulation of the drug, a weak interaction between the ITZ and the PLGA template takes place. Our findings suggest that while interacting with the silver film's surface, the ITZ's phenyl and the triazole planes are, respectively, parallelly and perpendicularly oriented.
Extended ΛCDM model da Silva, W.J.C.; Gimenes, H.S.; Silva, R.
Astroparticle physics,
February 2019, 2019-02-00, Letnik:
105
Journal Article
Recenzirano
Odprti dostop
In this work we discuss a general approach for the dissipative dark matter considering a nonextensive bulk viscosity and taking into account the role of generalized Friedmann equations. This ...generalized ΛCDM model encompasses a flat universe with a dissipative nonextensive viscous dark matter component, following the Eckart theory of bulk viscosity. In order to compare models and constrain cosmological parameters, we perform Bayesian analysis using one of the most recent observations of Type Ia Supernova, baryon acoustic oscillations, and cosmic microwave background data.
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