Polyethylene oxide (PEO) complexed with molecular iodine (
I
2
) forming PEO/
I
2
complex composites stand‐free films were investigated using dielectric relaxation, X-ray photoelectron spectroscopy ...(XPS), UV–Vis spectrophotometry, structural and morphological techniques. Scanning electron microscopy was used to monitor the variation in the surface morphology and the related roughness. 2D Energy-dispersive X-ray spectroscopy (EDX) measurements enabled to observe the distribution of iodine on the film surface. High resolution XPS measurements were used to define the iodine anion types and the metallic iodine existence, as well as the relevant concentrations based on the binding energies. The dielectric relaxation measurements were carried out over the frequency range from 0.1 to 10
7
Hz and temperature range from 155 to 330 K. Dielectric loss (ε′′) curves were fitted to the Havriliak–Negami (HN) model for one and/or two relaxation peaks (α and β), with and without the electrical conductivity contribution term, in order to deduce the relaxation time (τ) and the dielectric strengths (Δ
ε
), in addition to the electrical conductivities (
σ
). The temperature-dependent data of β- and σ- relaxations follow the law of Arrhenius thermal activation indicating the presence of typical glass-forming polymers. Δ
ε
of α-relaxation obeys the curvature pattern of Vogel-Tammann-Fulcher (VTF) thermal activation law. The electrical conductivity of the system increases 6000 folds by doping PEO with 5 wt% of iodine at the same temperature (293 K).
A theoretical investigation of the electronic structure and the magnetic and thermoelectric (TE) properties of KCrS, KCrSe, and KCrTe half‐Heusler alloys is studied. The most stable ...structural−magnetic configuration is identified, taking into consideration three types of possible atomic arrangements. The results indicate that KCrZ (Z = S, Se, Te) alloys are completely spin‐polarized half‐metallic ferromagnets in their ground state. Band structure calculations demonstrate that all compounds exhibit large bandgaps in the localized minority spin channel with a significant magnetic moment and high spin polarization (100%). The temperature dependence of the TE properties, such as the Seebeck coefficient and the electrical and thermal conductivity coefficients, is discussed and investigated using the semi‐local Boltzmann transport theory in the temperature range 250–1000 K. The quasiharmonic model is implemented to investigate and analyze the thermal parameters. In particular, thermal expansion coefficient, thermal conductivity, Debye temperature, specific heat capacity at constant volume, and entropy of the three novel half‐Heusler alloys are calculated and interpreted.
The KCrZ (Z = S, Se, and Te) show a strong half‐metallic behavior with a large magnetic moment of 5 μB. The electronic properties show that these alloys behave as metals in majority direction, whereas in minority directions, they behave as semiconductors. The obtained thermoelectric modulus indicates that KCrZ (Z = S, Se, and Te) half‐Heusler alloys are potential candidates for many thermoelectric applications.
This work studies the impact of positioning nickel nanoparticles (Ni‐NPs) on the surface of doped (P84‐PEO) nanocomposite films by using an ultra‐uniform magnetic field as a model for positioning ...magnetic NPs inside a polymeric matrix. This process is used to achieve desired and adjustable optoelectronic properties and to obtain new optical and electrical characteristics. P84‐PEO copolymer doped with Ni‐NPs exposed to a 450 mT magnetic field during the preparation give rise to a momentous increase in surface roughness, surface reactivity, and modified optical parameters, besides forming Ni oxides on the surface. Based on X‐ray photoelectron spectroscopy experiments, substantial extra shifts occurred in the binding energies of photo‐excited electrons from the O1s and C1s core levels. Additionally, the deconvoluted O1s spectra displays an additional photoelectron peak at 530.0 eV, most likely attributed to oxidized Ni‐NPs at the surface. Moreover, optical and structural properties were studied using UV–Vis and PL spectroscopy and X‐ray diffraction.
The ac‐impedance of bulk‐like films of pure polyethylene oxide (PEO) polymer was measured as a function of frequency f in the range 0.1 to 107 Hz at various constant temperatures T (155 − 330 K). The ...as‐measured data were analyzed by electric permittivity and modulus formalisms to unveil which dielectric and conductive relaxation processes were responsible for their relaxation behavior below/above glass transition temperature Tg of pure PEO polymer. At T > Tg, none of the α‐, β‐, or γ‐relaxations could be inferred for studied pure PEO films from frequency variation of measured imaginary part ε′′(f, T) of complex dielectric permittivity
ε~fT, as low‐frequency losses masked real dielectric contribution to the measured ε′′(f, T) at low frequencies and high temperatures. However, at T < Tg, a broad, relaxation process has been observed in the high‐frequency part of their isothermal ε′′(f, T) − f spectra, which can be related to the β‐ or γ‐dielectric relaxation process. Nonlinear regressions of the measured ε′′(f, T) − f data for T < Tg yielded moral fits to a simple addition of a Havriliak‐Negami function, and a Bergman‐loss Kohlrausch‐Williams‐Watts‐type function, with the relaxation time τmax(T) obtained from Havriliak‐Negami‐fitting parameters, was found to follow a thermally activated Arrhenius‐like relaxation behavior. Conversely, representation of the imaginary part M′′(f, T > Tg) − f spectra of complex electric modulus
M~f=1/ε~f was found to depict 2 overlapped relaxation processes, which were detached well by a nonlinear regression of a simple superposition of 2 different M′′(f) expressions having the form of the universal Bergman loss function, where it was found that the relaxation time is also thermally activated.
This work presents the effect of driven nickel nanoparticles (NiNPs) towards the surface of (PS‐PANI)/NiNPs nanocomposite upon the application of a uniform magnetic field. The purpose is to obtain ...distinguishable optoelectronic and electrical properties. This process increases the surface roughness and its reactivity, and enables the tuning of the optical and electrical properties. Based on the results from X‐ray photoelectron and Fourier‐transform infrared spectroscopies, the magnetically‐driven NiNPs to the surface are oxidized, forming NiONPs and NiOHNPs. This oxidation effect transforms the surface from a hydrophilic to a hydrophobic state. In addition, the optical bandgap energy decreases from 4.04 to 3.77 eV, and the electrical conductivity increases from 12.77 μS/cm to 57.80 μS/cm and 77.52 μS/cm, for 50 and 100 mT magnetic fields, respectively, which is attributed to the well‐dispersed magnetic nanoparticles in the PS‐PANI polymer matrix, resulting in a high homogeneous nanocomposite film.
•The total magnetic moment of all investigated compounds is obtained to be 2 µB.•The mechanical stability test performed on the computed elastic constants Cij demonstrate that investigated compounds ...are mechanically stable.•The GGA (GGA+U) and mBJ-GGA (mBJ-GGA+U) approximations are used for the calculation of electronic properties in the most stable phase B1.•These materials could be useful for spintronic application.
We report ab-initio calculation of the structural, magnetic, elastic, and electronic properties of the PrX (X = P, As and Bi). The structural stability and phase transition of PrX (X = P, As, Bi) compounds in (NaCl-type), (CsCl-type), (Zinc blende-type), WC-Bh (Hexagonal) and L10 (Tetragonal) structures in ferromagnetic state are investigated using the augmented plane wave plus local orbital (APW + lo) method within GGA + U, and mBJ-GGA + U approximations. Careful inspection of electronic properties indicates that most of the compounds exhibit half-metallic behavior. The total magnetic moment of all investigated compounds is obtained to be 2 µB. The mechanical stability test performed on the computed elastic constants Cij demonstrate that investigated compounds are mechanically stable. To elucidate chemical stability, chemical bonds are investigated and found to be mainly characterized by an ionic-covalent mixture. Moreover, elastic anisotropy of all compounds is calculated. Subsequently.
The as-measured room-temperature normal-incidence transmittance–wavelength (
T
exp
(
λ
) −
λ
) spectra of undoped amorphous selenium (
a
-Se) films, which were thermally deposited onto glass slides, ...exhibit well-resolved interference-fringe maxima and minima
λ
>
λ
c
(≈630 nm), below which they fall rather sharply to zero transmittance. In the transparency and weak absorption region, the maxima transmittance is close to the substrate transmission, implying good uniformity of the
a
-Se films. The geometric thicknesses of the films and the spectral dependency of their optical constants
n
(
λ
) and
κ
(
λ
) were retrieved by analyzing the
T
exp
(
λ
) −
λ
spectra by the PUMA method, based on the full
T
(
λ
)-formula for air-supported {uniform thin film/thick transparent substrate}-stacks, without the need for dispersion relations in prior and regardless of the number of interference fringes. The
n
(
λ
) −
λ
data of the transparency and weak absorption regions were found to fit the Wemple–DiDomenico and modified Sellmeier dispersion relations. The
ω
-dependency of the absorption coefficient
α
(
ω
) in the absorption-edge region has been analyzed in view of various interband transition models and was found to be nearly described by the linear power-law relation
α
ħ
ω
∝
ħ
ω
-
E
g
, with
E
g
≈ 2.2 eV over a broad spectral range.
The flash-evaporation technique was utilized to fabricate undoped 1.35-μm and 1.2-μm thick lead iodide films at substrate temperatures
T
s
=
150
°C and 200°C, respectively. The films were deposited ...onto a coplanar comb-like copper (Cu-) electrode pattern, previously coated on glass substrates to form lateral metal–semiconductor–metal (MSM-) structures. The as-measured
constant
-
temperature
direct-current (dc)-voltage (
I
V
;
T
-
V
) curves of the obtained lateral coplanar Cu-PbI
2
-Cu samples (film plus electrode) displayed remarkable ohmic behavior at all temperatures (
T
=
18
-
90
∘
C
). Their dc electrical resistance
R
dc
(
T
) revealed a single thermally-activated conduction mechanism over the temperature range with activation energy
E
act
≈
0.90
-
0.98
eV
, slightly less than half of room-temperature bandgap energy
E
g
(
≈
2.3
eV
) of undoped 2H-polytype PbI
2
single crystals. The undoped flash-evaporated
PbI
x
thin films were homogeneous and almost stoichiometric (
x
≈
1.87
), in contrast to findings on lead iodide films prepared by other methods, and were highly crystalline hexagonal 2H-polytypic structure with
c
-axis perpendicular to the surface of substrates maintained at
T
s
≳
150
∘
C
. Photoconductivity measurements made on these lateral Cu-PbI
2
-Cu-structures under on–off visible-light illumination reveal a feeble photoresponse for long wavelengths (
λ
>
570
nm
), but a strong response to blue light of photon energy
E
ph
≈
2.73
eV
(
>
E
g
), due to photogenerated electron–hole (e–h) pairs via direct band-to-band electronic transitions. The constant-temperature/dc voltage current–time
I
T
,
V
-
t
curves of the studied lateral PbI
2
MSM-structures at low ambient temperatures (
T
<
50
∘
C
), after cutting off the blue-light illumination, exhibit two trapping mechanisms with different relaxation times. These strongly depend on
V
and
T
, with thermally generated charge carriers in the PbI
2
mask photogenerated (e–h) pairs at higher temperatures.
Spectral dispersions of index of refraction
n
(
λ
)
and extinction coefficient
κ
(
λ
)
of undoped amorphous selenium (
a
-Se) films of three thicknesses (
d
≈ 0.5, 0.75, and 1.0 µm) were evaluated ...by analyzing experimental room-temperature normal-incidence transmittance-wavelength (
T
exp
(
λ
)
-
λ
) data (
λ
= 400–1100 µm) of their
air-supported
{
a
-Se film/thick glass slide}-stacks using Swanepoel’s transmission envelope theory of uniform films. Above a wavelength
λ
c
≈
640
nm
, as-measured
T
exp
(
λ
)
-
λ
spectra display well-resolved maxima and minima, with minor shrinkage in transparent and weak absorption regions (750–1100 nm). Below
λ
c
, a smeared sharp decline of
T
exp
(
λ
)
with decreasing
λ
, signifying strong absorption in
a
-Se films and existence of band-tail localized states. For
λ
>
λ
c
, the
n
(
λ
)
-
λ
data retrieved from algebraic envelope procedures followed a Sellmeier-like dispersion relation, with the best-fit values of high-frequency dielectric constant
ε
∞
≈
4.9
, static index of refraction
n
0
=
n
E
→
0
≈
2.43
, and resonance wavelength
λ
0
≈
490
nm
, which may be assigned to onset of photogeneration in
a
-Se. Urbach-like dependency of absorption coefficient
α
(
h
ν
)
of
a
-Se films on photon energy
h
ν
was realized with an Urbach-tail breadth of 85 meV. All achieved optical parameters were found to be slightly dependent on film thickness. Findings of present algebraic analysis are consistent with reported literature results obtained on the basis of other optical analytical approaches.
O manejo de vias aéreas em contratura de pescoço após queimadura sempre foi um desafio para os anestesiologistas, pois a contratura limita o alinhamento do eixo orofaringolaríngeo devido às ...deformidades funcionais e anatômicas que ocorrem como resultado de contraturas de longa duração.
Paciente do sexo masculino, 35 anos de idade, com contratura do pescoço após queimadura foi programado para liberação da contratura. Como estava com deformidade fixa em flexão no pescoço, não tentamos a laringoscopia convencional e optamos por usar o videolaringoscópio King Vision.
O videolaringoscópio King Vision pode ser usado em situações de via aérea difícil como a contratura de pescoço após queimadura.
Managing the airway of post burn contracture of the neck has always been challenging to anesthesiologists as it limits the alignment of oro‐pharyngo‐laryngeal axes because of functional and anatomical deformities that occur as a result of long standing contractures. Here the role of the King Vision video laryngoscope which is the latest in the series of video laryngoscope has been evaluated for such patients.
A 35 year old male patient with post burn contracture of neck was scheduled for release of the contracture. As the patient had had fixed flexion deformity of the neck we did not attempt the conventional laryngoscopy. Instead we opted for King Vision video laryngoscope.
We therefore conclude that King Vision videolaryngoscope can be used for difficult airway situations like post burn contracture of neck.
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