Motivated by the recent successful synthesis of the layered platinum mineral jacutingaite (Pt
2
HgSe
3
), we have studied the optoelectronic, mechanical, and thermoelectric properties of graphene ...hetero-multilayer on Pt
2
HgSe
3
monolayer (PHS) heterostructures (LG/PHS) by using first-principles calculations. PHS is a topological insulator with a band gap of about 160 meV with fully relativistic calculations; when graphene layers are stacked on PHS, a narrow band gap of ∼10-15 meV opens. In the presence of gate-voltage and out-of plane strain,
i.e.
pressure, the electronic properties are modified; the Dirac-cone of graphene can be shifted upwards (downward) to a lower (higher) binding energy. The absorption spectrum shows two peaks, which are located around 216 nm (5.74 eV) and protracted to 490 nm (2.53 eV), indicating that PHS could absorb more visible light. Increasing the number of graphene layers on PHS has a positive impact on the UV-vis light absorption and gives a clear red-shift with enhanced absorption intensity. To investigate the electronic performance of the heterostructure, the electrical conductance and thermopower of a device composed of graphene layers and PHS is examined by a combination of DFT and Green function formalism. The number of graphene layers can significantly tune the thermopower and electrical conductance. This analysis reveals that the heterostructures not only significantly affect the electronic properties, but they can also be used as an efficient way to modulate the optic and thermoelectric properties.
We have studied the optoelectronic, mechanical, and thermoelectric properties of graphene hetero-multilayer on Pt
2
HgSe
3
monolayer (PHS) heterostructures (LG/PHS) by using first-principles calculations.
In this paper, the sensing properties of WO3:TeO2 thin films deposited by spray pyrolysis using the oxide precursors with three different molar percentages of WO3 (0.15 M): TeO2 (0.05 M), WO3 ...(0.1 M): TeO2 (0.1 M) and, WO3 (0.05 M): TeO2 (0.15 M) are studied for before and after annealing at T = 773 K. The CO2 gas sensing properties of the WO3: TeO2 thin films at different molar percentages were investigated and experimental results showed that the sensing response of thin films strongly depends on the structure, morphology, and energy gap. The sensing response of thin films in terms of CO2 concentration for all compounds before and after annealing is linear and also the gradient of the curves increases after annealing. These changes in WO3 (0.15 M): TeO2 (0.05 M) are significant compared to other samples. Influences of TeO2 on the structures and morphology of the binary compounds of WO3: TeO2 thin films were investigated. X-ray diffraction results show that after annealing at T = 773 K, the WO2.92, TeO2, and H2Te2O6 phases were formed. FE-SEM images show that annealing at T = 773 K plays an important role in the morphology of the WO3: TeO2 thin films. The UV–Vis spectroscopy results showed that the bandgap of thin films decreases after annealing at T = 773 K.
•In this paper, the effect of TeO2 concentration, on sensing properties of WO3:TeO2 thin films are studied.•The effect of TeO2 concentration, structure, and energy gap on sensing properties for before and after annealing at T=773 K is studied.•The sensing response of WO3:TeO2 thin films to CO2 gas for before and after annealing at T = 773 K is quasi-linear.
•Study of structural properties and J-V voltametric cyclic of MoTe2 binary thin films.•The structural phase transition from MoO3-TeO2 to 2H-MoTe2 has been investigated.•Electrochromic properties of ...MoO3 - TeO2 thin films have been studied.•J-V cyclic, for MoO3 (0.05 M) -TeO2 (0.15 M) has higher area than other compounds.
The structural phase transition and ionic exchange in two-dimensional transition metals oxides have very important effect on their physical properties. The MoO3-TeO2 binary compounds can be used to improve these properties. In binary compounds, this exchange occurs easily due to the formation of an oxygen vacancy. In this paper, the MoO3 - TeO2 binary compounds thin films have been deposited by spray pyrolysis technique at Ts = 400 °C and structural phase transition from MoO3-TeO2 to 2H-MoTe2 has been investigated. The molar concentration of MoO3 - TeO2 in initial solution was changed at molar ratios (a) MoO3 (0.05 M) - TeO2 (0.15 M), (b) MoO3 (0.1 M) -TeO2 (0.1 M) and (c) MoO3 (0.15 M) - TeO2 (0.05 M). The structural and electrochromic properties of MoO3 - TeO2 thin films have been studied before and after annealing at T = 500 °C. The X-ray diffraction results of the films showed that, before annealing, the amorphous phase and after annealing at T = 500 °C, the MoO2, Te2O5, H6TeO6 and MoTe2 phases were formed. The FE-SEM images after annealing showed that, the morphology of films including nanoparticles which are almost uniformly distributed, is polygon structures. The electrochromic results showed that higher number of particles and holes in the surface of the electrochromic layers lead to the higher charge exchange rate and then the coloration. Also, in the hysteresis curve of J-V voltametric cyclic, MoO3-TeO2 compound with molar concentration of (a) MoO3 (0.05 M) - TeO2 (0.15 M) has higher area than other compounds and the diffusion coefficient of this sample has been studied before and after annealing at T = 500 °C.
Parkinson's disease (PD), which is the second most common neurodegenerative disorder after Alzheimer's disease, is firstly defined after James Parkinson's report. It carries motor symptoms such as ...resting tremor, bradykinesia and rigidity of skeletal muscle and freezing of gait. Furthermore, non-motor symptoms such as cognitive and behavioral problems, besides sensory impairments are seen in the patients. However, they may also suffer from sleep disorders or autonomic dysfunction. Although there are some medications in order to symptomatic management, but unfortunately, scientist could not have found exact approaches to cure this disease. Hence, producing a model which can express the most pathophysiologic and behavioral aspects of the disease is a desire. In this paper, we aimed to describe the different models of Parkinson's disease in brief.
The dissolution kinetics of silica-containing minerals in aggregates influences strongly the process of ASR in concrete. In this paper, the effect of different ions on the dissolution rates of SiO2 ...(amorphous and quartz) and feldspars at high pH values was studied by following the increase of silicon concentrations in dissolution experiments and with a novel approach of measuring the evolution of scratches of polished surfaces. The second method avoided the problem of precipitation in some systems, such as the formation of C-S-H when calcium was present and lithium silicates in the presence of lithium. At high pH values, lithium, calcium and sulfate increased the dissolution rates of silica and feldspars, while iron, magnesium and additional NaCl, KCl or CsCl showed no significant effect. In contrast, aluminium slowed down significantly the dissolution rates of quartz, amorphous silica and Na and K-feldspar at for all temperatures studies: 20, 40 and 60 °C.
In this paper, molybdenum disulfide (MoS
2
) thin films were deposited using an initial solution of molybdenum trioxide (MoO
3
) and thiourea (SC(NH
2
)
2
) on glass substrate with various mole ...concentrations by spray pyrolysis. The films were deposited in two steps (a) S/ Mo mole concentration ratio (x) varied at values of 0, 1, 2, 3, 5 and 10 at substrate temperature of
T
s
= 400ºC and (b) under post sulfurization process in the presence of argon gas at an annealing temperature of
T
a
= 450ºC. We applied x-ray diffraction (XRD), scanning electron microscopy (SEM), and ultraviolet-visible (UV-Vis) spectra for characterization of the MoS
2
thin films in terms of morphology, crystal structure and optical properties. The effect of S/Mo mole concentration ratio and post sulfurization processes on the structural conversion, morphology, x-ray diffraction and optical properties of these films have been studied. In non-sulfurization conditions it is found that the films are polycrystalline with a MoO
3
single phase and in post sulfurization conditions have hexagonal crystal structure corresponding to MoS
2
phase with preferred orientation along the (002) plane. The intensity of peaks increased with sulfurization and increase of mole concentration. The morphology of films obtained by scanning electron microscopy (SEM) appears as bar-shaped nano-grains. The average grain size increases with increasing mole concentration of S, in solution. Optical transparency of films changed in the range of 20% to 50% and 20% to 5%, in the visible region before and after sulfurization, respectively. The energy band gap (
E
g
) of films hardly depends to post sulfurization process, band gap decreased from 3.2 eV to 1.2 eV.
Quantum speed limit and entanglement of a two-spin Heisenberg
XYZ
system in an inhomogeneous external magnetic field are investigated. The physical system studied is the excess electron spin in two ...adjacent quantum dots. The influences of magnetic field inhomogeneity as well as spin–orbit coupling are studied. Moreover, the spin interaction with surrounding magnetic environment is investigated as a non-Markovian process. The spin–orbit interaction provides two important features: the formation of entanglement when two qubits are initially in a separated state and the degradation and rebirth of the entanglement.
Vision in the midwater of the open ocean requires animals to perform visual tasks quite unlike those of any other environment. These tasks consist of detecting small, low contrast objects and point ...sources against a relatively dim and uniform background. Deep-sea animals have evolved many extraordinary visual adaptations to perform these tasks. Linking eye anatomy to specific selective pressures, however, is challenging, not least because of the many difficulties of studying deep-sea animals. Computational modelling of vision, based on detailed morphological reconstructions of animal eyes, along with underwater optics, offers a chance to understand the specific visual capabilities of individual visual systems. Prior to the work presented here, comprehensive models for apposition compound eyes in the mesopelagic, the dominant eye form of crustaceans, were lacking. We adapted a model developed for single-lens eyes and used it to examine how different parameters affect the model’s ability to detect point sources and extended objects. This new model also allowed us to examine spatial summation as a means to improve visual performance. Our results identify a trade-off between increased depth range over which eyes function effectively and increased distance at which extended objects can be detected. This trade-off is driven by the size of the ommatidial acceptance angle. We also show that if neighbouring ommatidia have overlapping receptive fields, spatial summation helps with all detection tasks, including the detection of bioluminescent point sources. By applying our model to the apposition compound eyes of
Phronima
, a mesopelagic hyperiid amphipod, we show that the specialisations of the large medial eyes of
Phronima
improve both the detection of point sources and of extended objects. The medial eyes outperformed the lateral eyes at every modelled detection task. We suggest that the small visual field size of
Phronima
’s medial eyes and the strong asymmetry between the medial and lateral eyes reflect
Phronima
’s need for effective vision across a large depth range and its habit of living inside a barrel. The barrel’s narrow aperture limits the usefulness of a large visual field and has allowed a strong asymmetry between the medial and lateral eyes. The model provides a useful tool for future investigations into the visual abilities of apposition compound eyes in the deep sea.
Celotno besedilo
Dostopno za:
DOBA, IZUM, KILJ, NUK, PILJ, PNG, SAZU, SIK, UILJ, UKNU, UL, UM, UPUK
In this work, the extraction of carboxylated nanocrystalline cellulose from oat husk as an agricultural waste was conducted by ammonium persulfate oxidation. This is a one-step and efficient process ...for removal of amorphous regions from cellulosic fibers. The mean size of cellulose nanoparticles is about 30 nm with spherical morphology. The comparison of the infrared spectrum of the nanoparticles of cellulose and the primary oat husk evidences the successful elimination of non-cellulosic structures such as hemicellulose, lignin in nanocellulose sample. The X-ray diffraction patterns show higher degree of crystalline index in nanocellulose (57%) compared to the primary oat husk (38%). The comparison of the onsets of temperature degradation of the samples shows nanocellulose is less thermally stable than oat husk. The hydrophilic surface of the nanocellulose was modified using cetyltrimethylammonium bromide (CTAB) cationic surfactant to improve loading capacity of hydrophobic indomethacin drug which has a low bioavailability and poor solubility in water. In vitro release profile of the indomethacin and drug release mechanism was studied. The results show the 67% of drug is released within 12 h and CTAB modified nanocellulose greatly acts as an indomethacin controlled-release carrier. Study of the in vitro drug release kinetics shows driven mechanism is diffusion-controlled release.
In this paper, the elastic and plastic properties of
2
×
2
and
3
×
3
pristine and transition metal (TM) doped silicene nanosheets are studied using the density functional theory (DFT) calculations. ...Cr, Co, Cu, Mn, Ti, V, Zn and Ni atoms are selected as doping atoms. It is observed that Young’s and bulk moduli of both
2
×
2
and
3
×
3
pristine structures decrease when they are affected by the doping atoms. The highest reduction in the Young’s and bulk moduli of the
2
×
2
nanosheets occurs for the Ni-doped structure, and the same reduction is observed for the Ni- and Cu-doped structures in the
3
×
3
nanosheets. In addition, it is shown that all of the investigated structures have an isotropic behavior, since their Young’s moduli have negligible difference along armchair and zigzag directions. Finally, the loading is further increased to investigate the plastic behavior of nanostructures. The results show that the yield strains of all doped nanosheets decrease under uniaxial and biaxial loadings. The highest reduction in the yield strain of the
2
×
2
nanosheets under biaxial loading is observed for Cu, Zn- and Co-doped nanosheets, and in
3
×
3
nanosheets, the highest reduction happens for the Cu- and Zn-doped nanosheets under the same condition. For the yield strain of the
2
×
2
doped nanosheets under the uniaxial loading, the Cu-doped structure experiences the highest reduction, and the highest reduction for the Mn-doped nanosheet under the same condition is observed in
3
×
3
nanosheets. The findings revealed that how electronic configuration of transition metal atom and its electronegativity difference with silicon atom can control the structural and mechanical properties of the nanosheet.
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