This work presents an analytical methodology for the development of pipeline fitting welding modes, including the calculation of welding cooling rates and the assessment of steel response to the ...thermal cycle of welding processes. As a result, an optimal range of cooling rates ensuring the formation of a metal structure with the required mechanical properties in the heat-affected zone of the seam was determined.
•We investigated the temperature dependence of Tb3+ ions in the PAA:YAP structure.•The quenching mechanism depends on the terbium concentration.•We propose the physical model to describe obtained ...results.
Terbium doped YAlO3 composites were fabricated by the co-precipitation method in a porous anodic alumina (PAA) films grown on silicon at three different Tb concentrations: 0.23, 0.87 and 2.11at.%. To investigate the emission thermal quenching for all samples, we measured the emission spectra as a function of temperature in the range from 10 up to 500K at 266 and 488nm excitation wavelengths. Based on obtained results we proposed the physical model explaining the mechanism of Tb3+ emission quenching in YAlO3 composites deposited into PAA film.
The transmission spectra of films of strontium titanate up to 200 nm thick produced on quartz glass substrates by the sol-gel method were investigated in the region of 200–1100 nm. The sol was ...prepared from strontium acetate, titanium tetraisopropoxide, acetic acid, and ethylene glycol monomethyl ether. The strontium titanate films were formed by successive deposition of five layers with intermediate drying of each layer and final heat treatment at temperatures in the range of 500–700
o
C. From analysis of the transmission spectra it was established that the obtained films are characterized by a wide forbidden band decreasing from 4.46 to 3.84 eV in the transition from x-ray amorphous films to crystalline films with refractive index of 1.996 (λ = 620 nm) due to the high packing density of up to 81.5% of that for monocrystalline strontium titanate.
The photoluminescence properties of a composite material prepared by the introduction of the nanosized phosphor Zn
2
SiO
4
:Mn
2+
into porous anodic alumina have been investigated. Scanning electron ...microscopy studies have revealed that Zn
2
SiO
4
:Mn
2+
particles are uniformly distributed in 70% of the volume of the pore channels. The samples exhibit an intense luminescence in the range of 2.3–3.0 eV, which corresponds to the emission of different types of
F
centers in alumina. After the formation of Zn
2
SiO
4
:Mn
2+
nanoparticles in the pores, an intense photoluminescence band is observed at 2.4 eV due to the
4
T
1
–
6
A
1
electronic transition within the 3
d
shell of the Mn
2+
activator ion. It has been found that the maximum of the photoluminescence of Zn
2
SiO
4
:Mn
2+
xerogel nanoparticles located in the porous matrix is shifted to higher energies, and the luminescence decay time decreases significantly.
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► We successfully introduced Tb+3 ions into (Ba0,6Sr0,3Ca0,1)TiO3 and observed its strong green emission. ► Excitation mechanism of Tb+3 has been explained. ► Superparaelectric ...behavior of (Ba0,6Sr0,3Ca0,1)TiO3:Tb matrix has been observed.
The present paper discusses the optical and electrical properties of (Ba0,6Sr0,3Ca0,1)TiO3 (BSCT) doped with Tb3+ ions and deposited onto nano-porous anodic alumina using sol–gel method. Photoluminescence (PL), PL time-decay and total photoluminescence excitation spectroscopy data obtained from the structure xerogel/porous anodic alumina are compared with the data obtained for Tb in porous anodic alumina deposited by immersion. It has been shown that the most efficient excitation channel of Tb ions in BSCT xerogel is 4f8→5d14f7 transition at 270nm associated with 5d1 low-spin states. In consequence, strong emission band at 545nm corresponding to 5D4→7F5 transition characterized by the decay constant of 2ms has been observed for the samples annealed at above 750°C. This emission significantly and continuously decreases when the temperature is increased from 10 up to 300K without any abrupt change. This result correlates with the lack of ferroelectric phase transition and appearance of superparaelectric behavior of BSCT matrix observed with electrical measurements.
Terbium doped YAlO sub(3) composites were fabricated by the co-precipitation method in a porous anodic alumina (PAA) films grown on silicon at three different Tb concentrations: 0.23, 0.87 and 2.11 ...at.%. To investigate the emission thermal quenching for all samples, we measured the emission spectra as a function of temperature in the range from 10 up to 500 K at 266 and 488 nm excitation wavelengths. Based on obtained results we proposed the physical model explaining the mechanism of Tb super(3+) emission quenching in YAlO sub(3) composites deposited into PAA film.
Films of titania (TiO
2
) and titania modified with gold nanoparticles (TiO
2
:Au) were synthesized by a sol–gel method on substrates of glass, aluminum, and aluminum with a layer of nanotextured ...aluminum or porous anodic alumina. The photocatalytic activity of the samples was investigated in an aqueous solution of the antibiotic tetracycline hydrochloride (TC). TC decomposition was observed in the presence of all samples as a reduction of the solution optical density in the range below 500 nm. Titania was in the crystalline anatase phase with incorporated spherical gold nanoparticles primarily of sizes 1–10 nm after heat treatment at 400°C. Modification of TiO
2
films with gold nanoparticles on glass or aluminum substrates did not increase the photocatalytic activity of the samples. It was found that complexes of TC with Al
3+
in solution formed only in the presence of gold nanoparticles in the film either in the dark or with UV irradiation.
Yttrium–aluminum composites doped with terbium were synthesized by precipitation on porous anodic alumina fi lms grown on silicon substrates. The fabricated structures demonstrated x-ray-, cathodo-, ...and photoluminescence with characteristic bands of trivalent terbium upon excitation by Cu Kα x-rays of energy 8.86 keV, a 180-keV electron beam, and optical UV radiation, respectively. The terbium luminescence bands increased in intensity as the terbium concentration increased from 0.01 to 0.25 mol%. The intensity of a broad band in the blue spectral region with a maximum at 410 nm that was due to photoluminescence of the porous anodic alumina fi lm increased as the excitation wavelength increased from 260 to 340 nm. Simultaneously, the intensities of luminescence bands in the range 480–650 nm associated with
Tb
3 + 5
D
4 –
7
F
j
(
j
= 3, 4, 5, 6) transitions decreased. The possibility of practical application of the synthesized luminescent structures was discussed.
We show that in graphene epitaxially grown on SiC the Drude absorption is transformed into a strong terahertz plasmonic peak due to natural nanoscale inhomogeneities, such as substrate terraces and ...wrinkles. The excitation of the plasmon modifies dramatically the magneto-optical response and in particular the Faraday rotation. This makes graphene a unique playground for plasmon-controlled magneto-optical phenomena thanks to a cyclotron mass 2 orders of magnitude smaller than in conventional plasmonic materials such as noble metals.
NAC (N-acetyl-L-cysteine) is commonly used to identify and test ROS (reactive oxygen species) inducers, and to inhibit ROS. In the present study, we identified inhibition of proteasome inhibitors as ...a novel activity of NAC. Both NAC and catalase, another known scavenger of ROS, similarly inhibited ROS levels and apoptosis associated with H₂O₂. However, only NAC, and not catalase or another ROS scavenger Trolox, was able to prevent effects linked to proteasome inhibition, such as protein stabilization, apoptosis and accumulation of ubiquitin conjugates. These observations suggest that NAC has a dual activity as an inhibitor of ROS and proteasome inhibitors. Recently, NAC was used as a ROS inhibitor to functionally characterize a novel anticancer compound, piperlongumine, leading to its description as a ROS inducer. In contrast, our own experiments showed that this compound depicts features of proteasome inhibitors including suppression of FOXM1 (Forkhead box protein M1), stabilization of cellular proteins, induction of ROS-independent apoptosis and enhanced accumulation of ubiquitin conjugates. In addition, NAC, but not catalase or Trolox, interfered with the activity of piperlongumine, further supporting that piperlongumine is a proteasome inhibitor. Most importantly, we showed that NAC, but not other ROS scavengers, directly binds to proteasome inhibitors. To our knowledge, NAC is the first known compound that directly interacts with and antagonizes the activity of proteasome inhibitors. Taken together, the findings of the present study suggest that, as a result of the dual nature of NAC, data interpretation might not be straightforward when NAC is utilized as an antioxidant to demonstrate ROS involvement in drug-induced apoptosis.
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