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1.
Braz. J. Biol. ; 83: 1-5, 2023. mapas, tab
Artigo em Inglês | VETINDEX, VETINDEX | ID: vti-765542

RESUMO

This study estimated the length–weight relationships of 16 fish species occurring close to the shores of sandy beaches along the lower Negro River basin, Brazilian Amazon. The specimens were captured for one day each month, in October to November 2016, early in the morning and early evening, using trawl net (20 m length and 3.5 m height, 5 mm mesh between opposite knots). Measurements were taken for standard length (SL 0.1 cm precision) and total weight (TW 0.01 g precision). The parameters a and b of the equation WT = a.LTb were estimated. The a values ranged from 0.0018 to 0.0226 and b values ranged from 2.5271 to 3.3244. This study also provides new data on of maximum lengths for six species, Amazonsprattus scintilla, Brycon pesu, Moenkhausia megalops, Pachyurus paucirastrus, Reganella depressa and Trachydoras microstomus, and new reports of the LWRs parameters of 15 fish species.(AU)


Este estudo estimou as relações comprimento-peso de 16 espécies de peixes que ocorrem às margens de praias arenosas ao longo da bacia do baixo Rio Negro, Amazônia brasileira. As espécies foram capturadas durante um dia de cada mês, de outubro a novembro de 2016, no início da manhã e no início da noite, usando rede de cerco (20 m de comprimento e 3,5 m de altura, 5 malha mm entre nós opostos). As medidas foram feitas para comprimento padrão (SL - precisão de 0,1 cm) e peso total (TW - precisão de 0,01 g). Os parâmetros a e b da equação WT = a.LTb foram estimados. Os valores de a variaram de 0,0018 a 0,0226 e os valores de b variaram de 2,5271 a 3,3244. Este estudo também fornece novos dados sobre comprimentos máximos para seis espécies, Amazonsprattus scintilla, Brycon pesu, Moenkhausia megalops, Pachyurus paucirastrus, Reganella depressa e Trachydoras microstomus, e novos reportes dos parâmetros da LWRs de 15 espécies de peixes.(AU)


Assuntos
Animais , Peixes/anatomia & histologia , Peixes/crescimento & desenvolvimento
2.
Braz. j. biol ; 83: e250003, 2023. tab, graf
Artigo em Inglês | MEDLINE, LILACS, VETINDEX | ID: biblio-1339392

RESUMO

Abstract This study estimated the length-weight relationships of 16 fish species occurring close to the shores of sandy beaches along the lower Negro River basin, Brazilian Amazon. The specimens were captured for one day each month, in October to November 2016, early in the morning and early evening, using trawl net (20 m taken for standard length (SL - 0.1 cm precision) and total weight (TW - 0.01 g precision). The parameters a and b of the equation WT = a.LTb were estimated. The a values ranged from 0.0018 to 0.0226 and b values ranged from 2.5271 to 3.3244. This study also provides new data on of maximum lengths for six species, Amazonsprattus scintilla, Brycon pesu, Moenkhausia megalops, Pachyurus paucirastrus, Reganella depressa and Trachydoras microstomus, and new reports of the LWRs parameters of 15 fish species.


Resumo Este estudo estimou as relações comprimento-peso de 16 espécies de peixes que ocorrem às margens de praias arenosas ao longo da bacia do baixo Rio Negro, Amazônia brasileira. As espécies foram capturadas durante um dia de cada mês, de outubro a novembro de 2016, no início da manhã e no início da noite, usando rede de cerco (20 m de comprimento e 3,5 m de altura, 5 malha mm entre nós opostos). As medidas foram feitas para comprimento padrão (SL - precisão de 0,1 cm) e peso total (TW - precisão de 0,01 g). Os parâmetros a e b da equação WT = a.LTb foram estimados. Os valores de a variaram de 0,0018 a 0,0226 e os valores de b variaram de 2,5271 a 3,3244. Este estudo também fornece novos dados sobre comprimentos máximos para seis espécies, Amazonsprattus scintilla, Brycon pesu, Moenkhausia megalops, Pachyurus paucirastrus, Reganella depressa e Trachydoras microstomus, e novos reportes dos parâmetros da LWRs de 15 espécies de peixes.


Assuntos
Animais , Perciformes , Caraciformes , Characidae , Brasil , Rios
3.
Phys Chem Chem Phys ; 24(4): 2209-2218, 2022 Jan 26.
Artigo em Inglês | MEDLINE | ID: mdl-35013741

RESUMO

Exploration of new half-metallic materials for spintronic applications has drawn great attention from researchers. In this work, we investigate the structural, electronic, and magnetic properties of the NaMgO3 perovskite in the bulk and (001) surface conformations. The results show the half-metallic nature of bulk NaMgO3 generated by insulator spin-up channels with a large band gap of 6.08 eV and metallic spin-down channels. A total magnetic moment of 3 (µB) is obtained, which is produced mainly by O atoms with a local magnetic moment of 0.94 (µB). Once the bulk is cleaved along the (001) direction, atomic relaxation takes place to reach an equilibrium, where all constituent atoms exhibit an inward movement. Interestingly, the half-metallicity is retained from the bulk to the (001) surface conformation. The effects of slab termination and thickness on the surface energy, stability, band edges, spin-up energy gaps, and magnetic anisotropy will be also analyzed in detail. The results presented herein introduce the NaMgO3 perovskite as a promising half-metallic material to generate spin current in spintronic devices.

4.
Spectrochim Acta A Mol Biomol Spectrosc ; 266: 120434, 2022 Feb 05.
Artigo em Inglês | MEDLINE | ID: mdl-34624817

RESUMO

The luminescent properties of tryptophan in solvents less polar than water, such as acetone, and non-polar ones, such as cyclohexane, are experimentally studied and compared with theoretical calculations using time-dependent density functional theory (TD-DFT) methods. Since tryptophan may present different configurations and charge distributions, the most stable conformer is analyzed for both solvents, including its neutral and zwitterionic forms. To perform the simulation two clusters are proposed with the Zpt conformer in acetone: [Formula: see text] and [Formula: see text] , and four clusters with the Nag+ conformer in cyclohexane: (Trp)1-(C6H12), (Trp)2-(C6H12), (Trp)3-(C6H12) and (Trp)4-(C6H12), in order to conveniently emulate the concentration in each solvent by reducing the distance between adjacent tryptophan molecules as the concentration increases, since there is no control over the volume parameter. In each case, the UV-vis absorption is computed and compared with the experimental excitation spectra; the results show a good agreement. This calculation allows a more detailed analysis of the experimental results based on the properties of the molecular orbitals involved in electronic transitions. In the present work, a strong effect of the solvent acetone on tryptophan is observed; for this solvent, a charge transfer from the solute to solvent happens. This behavior does not occur with water (polar solvent) or cyclohexane (non-polar solvent). Finally, experimental spectroscopic data of Trp in cyclohexane are explained through the hydrogen bonds between amino acid molecules present in the fluorescent states. In this case, the theoretical and experimental results are compared and also show good agreement.


Assuntos
Acetona , Triptofano , Cicloexanos , Ligação de Hidrogênio , Solventes
5.
Braz J Biol ; 83: e250003, 2021.
Artigo em Inglês | MEDLINE | ID: mdl-34669803

RESUMO

This study estimated the length-weight relationships of 16 fish species occurring close to the shores of sandy beaches along the lower Negro River basin, Brazilian Amazon. The specimens were captured for one day each month, in October to November 2016, early in the morning and early evening, using trawl net (20 m taken for standard length (SL - 0.1 cm precision) and total weight (TW - 0.01 g precision). The parameters a and b of the equation WT = a.LTb were estimated. The a values ranged from 0.0018 to 0.0226 and b values ranged from 2.5271 to 3.3244. This study also provides new data on of maximum lengths for six species, Amazonsprattus scintilla, Brycon pesu, Moenkhausia megalops, Pachyurus paucirastrus, Reganella depressa and Trachydoras microstomus, and new reports of the LWRs parameters of 15 fish species.


Assuntos
Characidae , Caraciformes , Perciformes , Animais , Brasil , Rios
6.
J Phys Condens Matter ; 33(32)2021 Jun 24.
Artigo em Inglês | MEDLINE | ID: mdl-34082415

RESUMO

In practice, modifying the fundamental properties of low-dimensional materials should be realized before incorporating them into nanoscale devices. In this paper, we systematically investigate the nitrogen (N) doping and oxygen vacancy (OV) effects on the electronic and magnetic properties of the beryllium oxide (BeO) monolayer using first-principles calculations. Pristine BeO single layer is a non-magnetic insulator with an indirectK-Γ gap of 5.300 eV. N doping induces a magnetic semiconductor nature, where the spin-up and spin-down band gaps depend on the dopant concentration and N-N separation. Creating one OV leads to the energy gap reduction of 31.06% with no spin-polarization, which is due to the abundant 2p electrons of the Be atoms nearest the OV site. The further increase to two OVs and varying the OV-OV distance affect the band gap values, however the spin independence is retained. The magnetic semiconducting behavior is also obtained by the simultaneous N doping and OV presence. Calculations reveal significant magnetization of the BeO@1N, BeO@2N-n, BeO@NOV-nsystems, which is produced mainly by the spin-up N-2p state. Except for the BeO@NOV-1 and BeO@NOV-2, whose magnetic properties are created by the spin-up 2p state of the Be atoms closest to the OV site. The variation of the N-N and N-OV distances keeps the ferromagnetic ordering in the BeO@2N and BeO@NOV layers. Results presented herein may propose efficient methods to artificially modify the physical properties of BeO monolayer, leading to the formation of novel two-dimensional (2D) materials for optoelectronic and spintronic applications.

7.
ACS Omega ; 6(23): 14824-14837, 2021 Jun 15.
Artigo em Inglês | MEDLINE | ID: mdl-34151064

RESUMO

Based on density functional theory (DFT) and the semiempirical method PM7, we analyze the encapsulation process of polluting gases and/or their adsorption on different sites, viz., on the inner wall, the outer wall, and on the boron nitride (BN) nanotube ends, with chirality (7,7) armchair. DFT calculations are performed using the Perdew-Burke-Ernzerhof (PBE) functional and the M06-2X method through the 6-31G(d) divided valence orbitals as an atomic basis. Various geometrical configurations were optimized by minimizing the total energy for all analyzed systems, including the calculation of vibrational frequencies, which were assumed to be of a nonmagnetic nature, and where the total charge was kept neutral. Results are interpreted in terms of adsorption energy and electronic force, as well as on the analysis of quantum molecular descriptors for all systems considered. The study of six molecules, namely, CCl4, CS2, CO2, CH4, C4H10, and C6H12, in gas phase is addressed. Our results show that C4H10, C6H12, and CCl4 are chemisorbed on the inner surfaces (encapsulation) and on the nanotube ends. In contrast, the other molecules CS2, CO2, and CH4 show weak interaction with the nanotube surface, leading thereby to physisorption. Our findings thus suggest that this kind of polluting gases can be transported within nanotubes by encapsulation.

8.
Neotrop Entomol ; 50(1): 100-113, 2021 Feb.
Artigo em Inglês | MEDLINE | ID: mdl-33398854

RESUMO

The susceptibility of 1st to 4th instars of Bemisia tabaci (Gennadius, 1989) (Hemiptera: Aleyrodidae) to three isolates of Cordyceps sp. (Hypocreales: Cordycipitaceae) was evaluated in screenhouse experiments under variable temperatures and moisture conditions. No differences in susceptibility to the Cordyceps sp. isolates were observed among 1st, 2nd, and 3rd instar nymphs with respect to median lethal time (LT50) values. Confirmed mortalities ranged from 63.7 to 87.8% when the isolates were tested at 5 × 107 conidia mL-1. The 4th instar was the least susceptible to the fungal isolates (≤ 36.6% mortality). However, 60.0 to 99.5% of the adults that emerged from 4th instar nymphs previously treated with the fungus succumbed to the infection. Temperature was more detrimental to Cordyceps sp. virulence towards B. tabaci nymphs than relative humidity (RH). At similar RH, median LT50 for 1st instar (9.4 days) was higher than for 3rd instar (5.3 days) when the fungus was tested at 5 × 107 conidia mL-1; minimal temperatures of ≥ 12.6°C compared to ≥ 17.0°C were registered for experiments with 1st and 3rd instars, respectively. However, temperatures ≥ 35°C for 4 to 6 h daily did not affect the efficacy of the fungus against nymphs. Cordyceps sp. showed high virulence to all life stages of B. tabaci at relatively low RH, and an ability to grow extensively over the leaf surface and to produce high amounts of conidia on infected hosts. These attributes certainly boost its potential as an important pest control component of B. tabaci biotype B, especially for management of populations resistant to synthetic insecticides.


Assuntos
Cordyceps/patogenicidade , Hemípteros/microbiologia , Ninfa/microbiologia , Animais , Brasil , Umidade , Controle Biológico de Vetores , Temperatura
9.
RSC Adv ; 11(56): 35614-35623, 2021 Oct 28.
Artigo em Inglês | MEDLINE | ID: mdl-35493147

RESUMO

Since the successful synthesis of the MoSSe monolayer, two-dimensional (2D) Janus materials have attracted huge attention from researchers. In this work, the MoSO monolayer with tunable electronic and magnetic properties is comprehensively investigated using first-principles calculations based on density functional theory (DFT). The pristine MoSO single layer is an indirect gap semiconductor with energy gap of 1.02(1.64) eV as predicted by the PBE(HSE06) functional. This gap feature can be efficiently modified by applying external strain presenting a decrease in its value upon switching the strain from compressive to tensile. In addition, the effects of vacancies and doping at Mo, S, and O sites on the electronic structure and magnetic properties are examined. Results reveal that Mo vacancies, and Al and Ga doping yield magnetic semiconductor 2D materials, where both spin states are semiconductors with significant spin-polarization at the vicinity of the Fermi level. In contrast, single S and O vacancies induce a considerable gap reduction of 52.89% and 58.78%, respectively. Doping the MoSO single layer with F and Cl at both S and O sites will form half-metallic 2D materials, whose band structures are generated by a metallic spin-up state and direct gap semiconductor spin-down state. Consequently, MoV, MoAl, MoGa, SF, SCl, OF, and OCl are magnetic systems, and the magnetism is produced mainly by the Mo transition metal that exhibits either ferromagnetic or antiferromagnetic coupling. Our work may suggest the MoSO Janus monolayer as a prospective candidate for optoelectronic applications, as well as proposing an efficient approach to functionalize it to be employed in optoelectronic and spintronic devices.

10.
J Mol Graph Model ; 100: 107642, 2020 11.
Artigo em Inglês | MEDLINE | ID: mdl-32688130

RESUMO

It is known that high spin-polarization and magnetism can be found even in materials with neither transition metals nor rare earths. In this paper, we report results of the structural design, electronic structure, magnetic and optical properties of new equiatomic quaternary Heusler (EQH) KCaBX (X = S and Se) compounds. Electron exchangecorrelation interactions are described by the Wu-Cohen (WC) functional and Tran-Blaha modified Becke-Johnson exchange (mBJ) potential. Ferromagnetic ordering is stable for the cubic structure of space group F43 m in which the K, Ca, B and X atoms are located at 4c, 4d, 4a and 4b Wyckoff positions, respectively. Quaternaries at hand exhibit a perfect spin-polarization around the Fermi level, which is a result of the half-metallicity with metallic spin-up channel and semiconductor spin-dn channel. The ferromagnetic half-metallic and spin-flip band gaps are 2.648(2.470) and 0.673(0.526), respectively, for KCaBS(KCaBSe). Both studied compounds have a total magnetic moment of 2.000 µB. Additionally, the strain effect on the electronic and magnetic properties is also examined. Finally, the optical properties of the KCaBX alloys are investigated for energies up to 25 eV. Optical spectra show the metallic behavior at extremely low energies and semiconductor nature at higher energies. Interestingly, KCaBS and KCaBSe exhibit prospective absorption properties with a quite large absorption coefficient in the ultraviolet regime.


Assuntos
Eletrônica , Elementos de Transição , Ligas , Magnetismo , Estudos Prospectivos
11.
Arq. bras. med. vet. zootec. (Online) ; 72(1): 177-190, Jan.-Feb. 2020. tab, graf
Artigo em Português | VETINDEX, VETINDEX | ID: vti-26620

RESUMO

Estudou-se o efeito do hipotireoidismo materno na expressão espaço-temporal de mediadores imunológicos e na população de células natural killers (NK) na decídua e na glândula metrial de ratas durante a gestação. Avaliou-se a detecção imunoistoquímica de interferon γ (IFNγ), do fator inibidor de migração (MIF), da interleucina 15 (IL15), do óxido nítrico sintase induzível (iNOS), a marcação com lectina DBA para evidenciação das células NK uterinas DBA+ e a expressão gênica de Ifnγ e Nos2. O hipotireoidismo aumentou o iNOS aos sete dias, a IL15 e o MIF aos 10 e 12 dias, o IFNγ e o MIF aos 14 DG e a expressão dos transcritos gênicos para iNos aos 12 e 19 dias e para Ifnγ aos 14 DG. O hipotireoidismo reduziu a imunomarcação de MIF e lectina DBA aos sete dias, lectina DBA aos 10 e 14 DG, IFNγ aos 12 dias, e a expressão de Ifnγ aos 10 e 19 DG e de iNOS aos 12, 14 e 19 DG, bem como reduziu seus transcritos gênicos aos 10 e 14 DG. Conclui-se que o hipotireoidismo compromete o perfil imunológico na interface materno-fetal ao longo da gestação, particularmente por reduzir o fator anti-inflamatório iNOS e a população de células uNK DBA+.(AU)


The goal of this study was to evaluate the effect of maternal hypothyroidism on the spatiotemporal expression of immunological mediators and population of Natural Killers cells in decidua and metrial gland of rats. Interferon gamma (IFNγ), migration inhibitory factor (MIF), interleukin 15 (IL15), inducible nitric oxide synthase (iNOS), and DBA-Lectin labeling for evidence of uNK DBA+ cells in decidua and genetic expression of Ifnγ and iNos by real-time RT-PCR were evaluated. Hypothyroidism increased protein expression of iNOS at 7 days, IL15 and MIF at 10 and 12 days, IFNγ and MIF at 14 DG in the decidua and/or metrial gland and the gene transcripts for iNOS at 12 and 19 days and for Inf at 14 DG. In addition, hypothyroidism reduced the protein expression of MIF and DBA-Lectin at 7 days, DBA-Lectin at 10 and 14 DG, IFNγ at 12 days, and the gene transcript to Ifnγ at 10 and 19 DGs. Hypothyroidism also reduced the protein expression of iNOS at 12, 14 and 19 DG and reduced its gene transcripts at 10 and 14 DGs. It is concluded that hypothyroidism compromises the immunology profile at the maternal-fetal interface throughout pregnancy, particularly by reducing the anti-inflammatory factor iNOS and population of uNK DBA+ cells.(AU)


Assuntos
Animais , Feminino , Gravidez , Ratos , Implantação do Embrião , Células Matadoras Naturais , Hipotireoidismo/veterinária , Glândula Metrial
12.
Arq. bras. med. vet. zootec. (Online) ; 72(1): 177-190, Jan.-Feb. 2020. tab, graf
Artigo em Português | LILACS, VETINDEX | ID: biblio-1088927

RESUMO

Estudou-se o efeito do hipotireoidismo materno na expressão espaço-temporal de mediadores imunológicos e na população de células natural killers (NK) na decídua e na glândula metrial de ratas durante a gestação. Avaliou-se a detecção imunoistoquímica de interferon γ (IFNγ), do fator inibidor de migração (MIF), da interleucina 15 (IL15), do óxido nítrico sintase induzível (iNOS), a marcação com lectina DBA para evidenciação das células NK uterinas DBA+ e a expressão gênica de Ifnγ e Nos2. O hipotireoidismo aumentou o iNOS aos sete dias, a IL15 e o MIF aos 10 e 12 dias, o IFNγ e o MIF aos 14 DG e a expressão dos transcritos gênicos para iNos aos 12 e 19 dias e para Ifnγ aos 14 DG. O hipotireoidismo reduziu a imunomarcação de MIF e lectina DBA aos sete dias, lectina DBA aos 10 e 14 DG, IFNγ aos 12 dias, e a expressão de Ifnγ aos 10 e 19 DG e de iNOS aos 12, 14 e 19 DG, bem como reduziu seus transcritos gênicos aos 10 e 14 DG. Conclui-se que o hipotireoidismo compromete o perfil imunológico na interface materno-fetal ao longo da gestação, particularmente por reduzir o fator anti-inflamatório iNOS e a população de células uNK DBA+.(AU)


The goal of this study was to evaluate the effect of maternal hypothyroidism on the spatiotemporal expression of immunological mediators and population of Natural Killers cells in decidua and metrial gland of rats. Interferon gamma (IFNγ), migration inhibitory factor (MIF), interleukin 15 (IL15), inducible nitric oxide synthase (iNOS), and DBA-Lectin labeling for evidence of uNK DBA+ cells in decidua and genetic expression of Ifnγ and iNos by real-time RT-PCR were evaluated. Hypothyroidism increased protein expression of iNOS at 7 days, IL15 and MIF at 10 and 12 days, IFNγ and MIF at 14 DG in the decidua and/or metrial gland and the gene transcripts for iNOS at 12 and 19 days and for Inf at 14 DG. In addition, hypothyroidism reduced the protein expression of MIF and DBA-Lectin at 7 days, DBA-Lectin at 10 and 14 DG, IFNγ at 12 days, and the gene transcript to Ifnγ at 10 and 19 DGs. Hypothyroidism also reduced the protein expression of iNOS at 12, 14 and 19 DG and reduced its gene transcripts at 10 and 14 DGs. It is concluded that hypothyroidism compromises the immunology profile at the maternal-fetal interface throughout pregnancy, particularly by reducing the anti-inflammatory factor iNOS and population of uNK DBA+ cells.(AU)


Assuntos
Animais , Feminino , Gravidez , Ratos , Implantação do Embrião , Células Matadoras Naturais , Hipotireoidismo/veterinária , Glândula Metrial
13.
Lasers Med Sci ; 35(4): 777-788, 2020 Jun.
Artigo em Inglês | MEDLINE | ID: mdl-31768691

RESUMO

To date, there is no compilation of evidence-based information associating photobiomodulation effect and salivary glands. This systematic review aims to assess photobiomodulation effect of low intensity laser on salivary glands in the presence of systemic diseases. MEDLINE databases were searched in duplicate through December 2018. In vivo studies and clinical trials were included if photobiomodulation was performed in salivary glands of animal (rat or mice) or human in the presence of systemic disease. The methodological quality was assessed in duplicate using the modified Newcastle-Ottawa scale (NOS). Search strategy identified 483 potentially eligible articles, and 449 were included. The Boolean search naturally leads to a high amount of works the majority of which were excluded because the analysis of the title and abstract demonstrated it was not focusing on PBM. Only 34 studies were selected for the full-text analysis, of which 5 were excluded due to non-use of photobiomodulation, 4 due to lack of control group, 2 because they were studies of cell cultures and 1 because they did not have the total of animals used. Thus, 21 papers were included for the critical evaluation of the impact of photobiomodulation on the major salivary glands; the studies used rats (n = 10) and humans (n = 11). Although studies reported an increase in the salivary rate, decrease in pain, and increase in quality of life after the PBM, the lack of standards for the application of light and reporting of the parameters, make it hard to reproduce the results. This topic is still in need for further research.


Assuntos
Terapia com Luz de Baixa Intensidade , Glândulas Salivares/efeitos da radiação , Animais , Ensaios Clínicos como Assunto , Humanos , Camundongos , Dor/radioterapia , Qualidade de Vida , Ratos
14.
RSC Adv ; 10(43): 25609-25617, 2020 Jul 03.
Artigo em Inglês | MEDLINE | ID: mdl-35518578

RESUMO

In this work, a new equiatomic quaternary Heusler (EQH) compound, MnVZrP, is predicted using first principles calculations. Simulations show the good stability of the material, suggesting experimental realization. Results show that MnVZrP is a magnetic semiconductor material, exhibiting semiconductor characteristics in both spin channels, however, with strong spin-polarization. Electronic band gaps of 0.97 and 0.47 eV are obtained in the spin-up and spin-dn states, respectively. Mainly the d-d coupling regulates the electronic band structure around the Fermi level. Strain effects on the electronic properties of the proposed compound are also investigated. Simulations give the total magnetic moment of 3 µ B satisfying the Slate-Pauling rule. The main magnetic contributions are given by the Mn and V constituents. The results presented here suggest the promising applicability of EQH MnVZrP as a spin-filter. Additionally, the elastic property calculations indicate the mechanical stability and elastic anisotropy. The work may be useful in the magnetic Heusler alloys field, introducing a new member to the small group of magnetic semiconductor EQH compounds for spin-filter applications.

15.
RSC Adv ; 10(66): 40411-40420, 2020 Nov 02.
Artigo em Inglês | MEDLINE | ID: mdl-35520824

RESUMO

In this paper, we present a detailed investigation of the structural, electronic, and optical properties of pristine, nitrogenated, and fluorinated MgO monolayers using ab initio calculations. The two dimensional (2D) material stability is confirmed by the phonon dispersion curves and binding energies. Full functionalization causes notable changes in the monolayer structure and slightly reduces the chemical stability. The simulations predict that the MgO single layer is an indirect semiconductor with an energy gap of 3.481 (4.693) eV as determined by the GGA-PBE (HSE06) functional. The electronic structure of the MgO monolayer exhibits high sensitivity to chemical functionalization. Specifically, nitrogenation induces metallization of the MgO monolayer, while an indirect-direct band gap transition and band gap reduction of 81.34 (59.96)% are achieved by means of fluorination. Consequently, the functionalized single layers display strong optical absorption in the infrared and visible regimes. The results suggest that full nitrogenation and fluorination may be a quite effective approach to enhance the optoelectronic properties of the MgO monolayer for application in nano-devices.

16.
J Phys Condens Matter ; 31(8): 085601, 2019 Feb 27.
Artigo em Inglês | MEDLINE | ID: mdl-30537684

RESUMO

In this work two high density functional theory (DFT) correlation methodologies, the so called DFT+U (or GGA+U) implementation and the exact exchange of correlated electrons (EECE), hybrid DFT functional (or one case of hybrid DFT), are tested to determine the mechanical properties of americium-II. For each case, the numeric value of their principal parameter is chosen ([Formula: see text] for the first case and [Formula: see text] for the second one) once the crystalline structure meets all the mechanical stability conditions. The results show that there is a range of values of [Formula: see text] and [Formula: see text] in which both methodologies generate a stable (experimentally correct) non-magnetic ground state, reaching approximately the same numeric value of the set of elastic constants of the cubic structure. However, only for the case of the hybrid functional results it is possible to show how the non-magnetic configuration is energetically favored, as compared to the ferromagnetic configuration. This happens around [Formula: see text], a value in agreement with a previous analysis made under the same methodology for the metal case Am-I. Following a detailed and deep analysis, it is possible to find a close interrelation between the electronic properties of the metal: its distribution of states around the Fermi level, the energy difference between the two possible spin configurations, and the mechanical response of the crystal. Also, it is possible to conclude that the effect of alpha parameter on the [Formula: see text] electrons can be used as a parameter to simulate the presence of an external pressure over the structure. For the comparison, the calculations were performed within the LAPW approximation in DFT as implemented in the WIEN2k code, with a finite deformation method.

17.
Arq. bras. med. vet. zootec. (Online) ; 70(3): 857-872, Maio-Jun. 2018. ilus, tab, graf
Artigo em Português | VETINDEX, VETINDEX | ID: vti-735077

RESUMO

Com o objetivo de estudar o efeito da condroitinase associada às células-tronco mesenquimais na lesão aguda da medula espinhal, utilizaram-se 50 ratos Lewis, distribuídos igualmente nos grupos: controle negativo (CN), tratamento com placebo (PLA), condroitinase (CDN), células-tronco mesenquimais (CTM) e condroitinase mais células-tronco mesenquimais (CDN+CTM). Todos os animais tiveram a medula espinhal exposta por laminectomia, e os grupos PLA, CDT, CTM e CDT+CTM sofreram também trauma medular compressivo. Após sete dias, procedeu-se à reexposição da medula espinhal, quando os grupos PLA e CTM receberam 4µL de líquido cefalorraquidiano artificial via intralesional, e os grupos CDT e CDT+CTM receberam o mesmo líquido contendo 2,2U de condroitinase. Após 14 dias da cirurgia inicial, todos os animais receberam 0,2mL de PBS via endovenosa, contudo, nos grupos CTM e CDT+CTM, esse líquido continha 1x106 CTM. Avaliou-se a capacidade motora até o 28o dia pós-trauma e, posteriormente, as medulas espinhais foram analisadas por RT-PCR, para quantificação da expressão gênica para BDNF, NT-3, VEGF, KDR e PECAM-1, e por imunoistoquímica, para detecção das células-tronco GFP injetadas (anti-GFP), quantificação dos neurônios (anti-NeuN) e da GFAP e vimentina, para avaliação da cicatriz glial. As análises estatísticas foram realizadas com o auxílio do Prism 5 for Windows, com o nível de significância de 5%. Não houve diferença entre os grupos quanto à capacidade motora. O grupo CDT+CTM apresentou maior imunoexpressão de neurônios viáveis do que o placebo. No CTM, houve maior expressão dos fatores neurotróficos BDNF e VEGF. E no CDT, houve menor imunoexpressão de vimentina. Concluiu-se que a associação CDT+CTM favorece a viabilidade neuronal após o trauma, que o tratamento com CTM promove aumento na expressão dos fatores tróficos BDNF e VEGF e que o tratamento com condroitinase é efetivo na redução da cicatriz glial.(AU)


The aim of this work was to study the effect of chondroitinase associated with mesenchymal stem cells in acute spinal cord injury. Therefore, 50 Lewis rats were distributed in the following groups: negative control (NC), treatment with placebo (PLA), chondroitinase (CDT), mesenchymal stem cells (MSC), and chondroitinase associated with mesenchymal stem cells (CDT + MSC). All animals had their spinal cord exposed by laminectomy, and the groups named PLA, CDT, MSC and CDT + MSC also suffered compressive spinal cord trauma. After seven days, the spinal cord was re-exposed, when the PLA and MSCs groups received 4uL of artificial cerebrospinal fluid through the lesion, and the CDT group and CDT + MSC received the same fluid containing 2,2U of chondroitinase. 14 days after the first surgery, all animals received 0.2ml of PBS intravenously; however, the MSC and CDT + MSC groups received the same liquid also containing 1x106 MSCs. The motor skills were evaluated up to 28 days post-injury and, subsequently, the spinal cords were analyzed by RT-PCR for BDNF, NT-3, VEGF, PECAM-1 and KDR gene expression quantification, immunohistochemistry to detect injected stem cells GFP (anti-GFP), to quantify neurons (anti-NeuN), GFAP and detect vimentin in order to evaluate the glial scar. Statistical analyzes were performed by Prism 5 for Windows using a 5% level of significance. There was no difference between groups with regarding motor capacity. The CDT + MSC group showed increased immunoreactivity of viable neurons than placebo. In MSC, there was a greater expression of neurotrophic factors BDNF and VEGF. Also, there was less vimentin immunostaining in group CDT. It was concluded that CDT + MSC association promotes neuronal viability after trauma, in which treatment with MSC promotes increased expression of BDNF and VEGF trophic factors, and also that treatment with chondroitinase is effective in reducing the glial scar.(AU)


Assuntos
Animais , Ratos , Condroitina ABC Liase , Ratos/anatomia & histologia , Ratos/lesões , Células-Tronco Mesenquimais/enzimologia
18.
Arq. bras. med. vet. zootec. (Online) ; 70(6): 1877-1886, nov.-dez. 2018. tab, ilus
Artigo em Português | VETINDEX, VETINDEX | ID: vti-21279

RESUMO

Foram avaliados os efeitos tóxicos do metavanadato de sódio (MV), pentóxido de vanádio (PV) e sulfato de oxovanádio (SV), potenciais fármacos antidiabéticos, em embriões e adultos de zebrafish (Danio rerio). Os embriões foram expostos a concentrações de 10-1000µg/mL para avaliação da CL50 96h e seus efeitos teratogênicos. Os adultos foram expostos a 10 e 20µg/mL dos mesmos compostos para se avaliarem alterações comportamentais relacionadas à exposição química e à mortalidade. A CL50 96h foi de 22,48, 53,62 e 74,14µg/mL para MV, SV e PV, respectivamente. Houve 100% de mortalidade nas concentrações de 400-1000µg/mL dos três compostos. Os efeitos teratogênicos mais observados (P<0,05) nos embriões foram edemas de pericárdio e saco vitelínico. Foram constatados, nos animais adultos expostos aos compostos de vanádio, maior batimento opercular e congestão nos arcos branquiais. A exibição dos comportamentos Flutuar e Descansar nos adultos expostos foi significativa (P<0,05), como também a exibição do comportamento Respiração Aérea. Pode-se concluir que a exposição química aos compostos de vanádio causou efeitos tóxicos em embriões e adultos de zebrafish com alta mortalidade. Diante disso, o seu uso como potencial fármaco antidiabético deve ser mais bem estudado em razão do efeito tóxico dessas substâncias.(AU)


The toxic effects of sodium metavanadate (MV), vanadium pentoxide (PV) and oxovanadium sulfate (SV), potential antidiabetic drug, on embryos and adults of zebrafish (Danio rerio) were evaluated. Embryos were exposed to concentrations of 10-1000µg/mL for evaluation of 96-h LC50 and their teratogenic effects. Adults were exposed to 10 and 20µg/mL of the same compounds to evaluate behavioral changes related to chemical exposure and mortality. The 96-h LC50 were 22.48, 53.62, and 74.14µg/mL for MV, SV, and PV, respectively. Mortality of 100% was observed at the concentrations of 400-1000µg/mL of the three compounds. The teratogenic effects most observed (P<0.05) were pericardial and yolk sac edemas. Adult animals exposed to the vanadium compounds had higher opercular beats and congestion in the gill arches. The exhibition of behaviors Floating and Resting in the exposed adults was significant (P<0.05), as well as the Air breathing behavior. Chemical exposure to vanadium compounds caused toxic effects in embryos and adults of zebrafish with high mortality. In conclusion, its use as a potential antidiabetic drug should be better studied due to the toxic effect.(AU)


Assuntos
Animais , Comportamento Animal , Fatores Biológicos/toxicidade , Compostos de Vanádio/toxicidade , Peixes/fisiologia , Pesquisas com Embriões
19.
Arq. bras. med. vet. zootec. (Online) ; 70(3): 857-872, maio-jun. 2018. ilus, tab, graf
Artigo em Português | LILACS, VETINDEX | ID: biblio-911635

RESUMO

Com o objetivo de estudar o efeito da condroitinase associada às células-tronco mesenquimais na lesão aguda da medula espinhal, utilizaram-se 50 ratos Lewis, distribuídos igualmente nos grupos: controle negativo (CN), tratamento com placebo (PLA), condroitinase (CDN), células-tronco mesenquimais (CTM) e condroitinase mais células-tronco mesenquimais (CDN+CTM). Todos os animais tiveram a medula espinhal exposta por laminectomia, e os grupos PLA, CDT, CTM e CDT+CTM sofreram também trauma medular compressivo. Após sete dias, procedeu-se à reexposição da medula espinhal, quando os grupos PLA e CTM receberam 4µL de líquido cefalorraquidiano artificial via intralesional, e os grupos CDT e CDT+CTM receberam o mesmo líquido contendo 2,2U de condroitinase. Após 14 dias da cirurgia inicial, todos os animais receberam 0,2mL de PBS via endovenosa, contudo, nos grupos CTM e CDT+CTM, esse líquido continha 1x106 CTM. Avaliou-se a capacidade motora até o 28o dia pós-trauma e, posteriormente, as medulas espinhais foram analisadas por RT-PCR, para quantificação da expressão gênica para BDNF, NT-3, VEGF, KDR e PECAM-1, e por imunoistoquímica, para detecção das células-tronco GFP injetadas (anti-GFP), quantificação dos neurônios (anti-NeuN) e da GFAP e vimentina, para avaliação da cicatriz glial. As análises estatísticas foram realizadas com o auxílio do Prism 5 for Windows, com o nível de significância de 5%. Não houve diferença entre os grupos quanto à capacidade motora. O grupo CDT+CTM apresentou maior imunoexpressão de neurônios viáveis do que o placebo. No CTM, houve maior expressão dos fatores neurotróficos BDNF e VEGF. E no CDT, houve menor imunoexpressão de vimentina. Concluiu-se que a associação CDT+CTM favorece a viabilidade neuronal após o trauma, que o tratamento com CTM promove aumento na expressão dos fatores tróficos BDNF e VEGF e que o tratamento com condroitinase é efetivo na redução da cicatriz glial.(AU)


The aim of this work was to study the effect of chondroitinase associated with mesenchymal stem cells in acute spinal cord injury. Therefore, 50 Lewis rats were distributed in the following groups: negative control (NC), treatment with placebo (PLA), chondroitinase (CDT), mesenchymal stem cells (MSC), and chondroitinase associated with mesenchymal stem cells (CDT + MSC). All animals had their spinal cord exposed by laminectomy, and the groups named PLA, CDT, MSC and CDT + MSC also suffered compressive spinal cord trauma. After seven days, the spinal cord was re-exposed, when the PLA and MSCs groups received 4uL of artificial cerebrospinal fluid through the lesion, and the CDT group and CDT + MSC received the same fluid containing 2,2U of chondroitinase. 14 days after the first surgery, all animals received 0.2ml of PBS intravenously; however, the MSC and CDT + MSC groups received the same liquid also containing 1x106 MSCs. The motor skills were evaluated up to 28 days post-injury and, subsequently, the spinal cords were analyzed by RT-PCR for BDNF, NT-3, VEGF, PECAM-1 and KDR gene expression quantification, immunohistochemistry to detect injected stem cells GFP (anti-GFP), to quantify neurons (anti-NeuN), GFAP and detect vimentin in order to evaluate the glial scar. Statistical analyzes were performed by Prism 5 for Windows using a 5% level of significance. There was no difference between groups with regarding motor capacity. The CDT + MSC group showed increased immunoreactivity of viable neurons than placebo. In MSC, there was a greater expression of neurotrophic factors BDNF and VEGF. Also, there was less vimentin immunostaining in group CDT. It was concluded that CDT + MSC association promotes neuronal viability after trauma, in which treatment with MSC promotes increased expression of BDNF and VEGF trophic factors, and also that treatment with chondroitinase is effective in reducing the glial scar.(AU)


Assuntos
Animais , Ratos , Condroitina ABC Liase , Ratos/anatomia & histologia , Ratos/lesões , Células-Tronco Mesenquimais/enzimologia
20.
Arq. bras. med. vet. zootec. (Online) ; 70(6): 1877-1886, nov.-dez. 2018. tab, ilus
Artigo em Português | LILACS, VETINDEX | ID: biblio-970638

RESUMO

Foram avaliados os efeitos tóxicos do metavanadato de sódio (MV), pentóxido de vanádio (PV) e sulfato de oxovanádio (SV), potenciais fármacos antidiabéticos, em embriões e adultos de zebrafish (Danio rerio). Os embriões foram expostos a concentrações de 10-1000µg/mL para avaliação da CL50 96h e seus efeitos teratogênicos. Os adultos foram expostos a 10 e 20µg/mL dos mesmos compostos para se avaliarem alterações comportamentais relacionadas à exposição química e à mortalidade. A CL50 96h foi de 22,48, 53,62 e 74,14µg/mL para MV, SV e PV, respectivamente. Houve 100% de mortalidade nas concentrações de 400-1000µg/mL dos três compostos. Os efeitos teratogênicos mais observados (P<0,05) nos embriões foram edemas de pericárdio e saco vitelínico. Foram constatados, nos animais adultos expostos aos compostos de vanádio, maior batimento opercular e congestão nos arcos branquiais. A exibição dos comportamentos Flutuar e Descansar nos adultos expostos foi significativa (P<0,05), como também a exibição do comportamento Respiração Aérea. Pode-se concluir que a exposição química aos compostos de vanádio causou efeitos tóxicos em embriões e adultos de zebrafish com alta mortalidade. Diante disso, o seu uso como potencial fármaco antidiabético deve ser mais bem estudado em razão do efeito tóxico dessas substâncias.(AU)


The toxic effects of sodium metavanadate (MV), vanadium pentoxide (PV) and oxovanadium sulfate (SV), potential antidiabetic drug, on embryos and adults of zebrafish (Danio rerio) were evaluated. Embryos were exposed to concentrations of 10-1000µg/mL for evaluation of 96-h LC50 and their teratogenic effects. Adults were exposed to 10 and 20µg/mL of the same compounds to evaluate behavioral changes related to chemical exposure and mortality. The 96-h LC50 were 22.48, 53.62, and 74.14µg/mL for MV, SV, and PV, respectively. Mortality of 100% was observed at the concentrations of 400-1000µg/mL of the three compounds. The teratogenic effects most observed (P<0.05) were pericardial and yolk sac edemas. Adult animals exposed to the vanadium compounds had higher opercular beats and congestion in the gill arches. The exhibition of behaviors Floating and Resting in the exposed adults was significant (P<0.05), as well as the Air breathing behavior. Chemical exposure to vanadium compounds caused toxic effects in embryos and adults of zebrafish with high mortality. In conclusion, its use as a potential antidiabetic drug should be better studied due to the toxic effect.(AU)


Assuntos
Animais , Comportamento Animal , Fatores Biológicos/toxicidade , Compostos de Vanádio/toxicidade , Peixes/fisiologia , Pesquisas com Embriões
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