High entropy alloys have attracted much interest over the last 16 years due to their promising an unusual properties in different fields that offer many new possible application. Additionally, ...additive manufacturing has drawn attention due to its versatility and flexibility ahead of a new material challenge, being a suitable technology for the development of metallic materials. Moreover, high entropy alloys have demonstrated that many gaps exist in the literature on its physical metallurgy, and in this sense, additive manufacturing could be a feasible technology for solving many of these challenges. In this review paper the newest literature on this topic is condensed into three different aspects: the different additive manufacturing technologies employed to process high entropy alloys, the influence of the processing conditions and composition on the expected structure and microstructure and information about the mechanical and corrosion behavior of these alloys.
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•Development of high-entropy alloys by powder metallurgy route, using “commodity” powders.•It can be replaced fully prealloyed powders (not available in the market) by commodity ...powders mixing.•High entropy alloys can be easily developed, being obtained full FCC phase.•The amounts of mixing can be predicted by different proposed parameters.
One of the main drawbacks of the powder metallurgy route for High-Entropy Alloys (HEAs) is the unavailability of fully pre-alloyed powders in the market. Using commodity powders (commercial Ni, Fe and Co base fully pre-alloyed powders, fully available in large quantities and at competitive prices) to produce HEAs presents a completely new and competitive scenario for obtaining viable alloys for high-performance applications.
High-entropy alloys (HEAs) have attracted a great deal of interest over the last 14 years. One reason for this level of interest is related to these alloys breaking the alloying principles that have ...been applied for many centuries. Thus, HEAs usually possess a single phase (contrary to expectations according to the composition of the alloy) and exhibit a high level of performance in different properties related to many developing areas in industry. Despite this significant interest, most HEAs have been developed via ingot metallurgy. More recently, powder metallurgy (PM) has appeared as an interesting alternative for further developing this family of alloys to possibly widen the field of nanostructures in HEAs and improve some capabilities of these alloys. In this paper, PM methods applied to HEAs are reviewed, and some possible ways to develop the use of powders as raw materials are introduced.
The catechol oxidase activity of three copper/bicompartmental
salen
derivatives has been studied. One mononuclear, CuL (
1
), one homometallic, Cu
2
L(NO
3
)
2
(
2
), and one heterometallic, ...CuMnL(NO
3
)
2
(
3
) complexes were obtained using the ligand H
2
L =
N
,
N
′-bis(3-methoxysalicylidene)-1,3-propanediamine through different synthetic methods (electrochemical, chemical and solid state reaction). The structural data indicate that the metal ion disposition models the active site of
type-3
copper enzymes, such as catechol oxidase. In this way, their ability to act as functional models of the enzyme has been spectrophotometrically determined by monitorization of the oxidation of 3,5-di-
tert
-butylcatechol (3,5-DTBC) to 3,5-di-
tert
-butyl-
o
-benzoquinone (3,5-DTBQ). All the complexes show significant catalytic activity with ratio constants (
k
obs
) lying in the range (223–294) × 10
–4
min
−1
. A thorough kinetic study was carried out for complexes
2
and
3
, since they show structural similarities with the catechol oxidase enzyme. The greatest catalytic activity was found for the homonuclear dicopper compound (
2
) with a turnover value (
k
cat
) of (3.89 ± 0.05) × 10
6
h
−1
, which it is the higher reported to date, comparable to the enzyme itself (8.25 × 10
6
h
−1
).
Graphic abstract
Background
Histamine H3 receptors are mainly expressed on CNS neurons, particularly along the nociceptive pathways. The potential involvement of these receptors in pain processing has been suggested ...using H3 receptor inverse agonists.
Methods
The antinociceptive effect of S 38093, a novel inverse agonist of H3 receptors, has been evaluated in several neuropathic pain models in rat and compared with those of gabapentin and pregabalin.
Results
While S 38093 did not change vocalization thresholds to paw pressure in healthy rats, it exhibited a significant antihyperalgesic effect in the Streptozocin‐induced diabetic (STZ) neuropathy model after acute and chronic administration and, in the chronic constriction injury (CCI) model only after chronic administration, submitted to the paw‐pressure test. Acute S 38093 administration at all doses tested displayed a significant cold antiallodynic effect in a model of acute or repeated administration of oxaliplatin‐induced neuropathy submitted to cold tail immersion, cold allodynia being the main side effect of oxaliplatin in patients. The effect of S 38093 increased following chronic administration (i.e. twice a day during 5 days) in the CCI and STZ models except in the oxaliplatin models where its effect was already maximal from the first administration The kinetics and size of effect of S 38093 were similar to gabapentin and/or pregabalin. Finally, the antinociceptive effect of S 38093 could be partially mediated by α2 adrenoreceptors desensitization in the locus coeruleus.
Conclusions
These results highlight the interest of S 38093 to relieve neuropathic pain and warrant clinical trials especially in chemotherapeutic agent‐induced neuropathic pain.
Significance
S 38093, a new H3 antagonist/inverse agonist, displays antiallodynic and antihyperalgesic effect in neuropathic pain, especially in oxaliplatin‐induced neuropathy after chronic administration. This effect of S 38093 in neuropathic pain could be partly mediated by α2 receptors desensitization in the locus coeruleus.
The structures of five fluorinated benzimidazoles and one intermediate (an open double amide) have been determined by X-ray crystallography. In the analysis of these heterocycles, particular ...attention has been paid to N–H···H hydrogen bonds and to fluorine–fluorine intermolecular contacts. Thus, one of the shortest F···F distances ever reported, 2.596(3) Å, has been observed in 4,5,6,7-tetrafluoro-1H-benzimidazole-2(3H)-one. The 13C, 15N, and 19F solid-state NMR data for all benzimidazoles are also given.
A Co-based superalloy, Co-9Al-9W (at%), was processed by mechanical alloying by high-energy milling of elemental powders and consolidated by field assisted hot pressing (FAHP). The milled powder ...particles mainly consist of undissolved bcc-W as well as WC and an Al and W rich fcc-γ Co solid solution. After consolidation and heat treatment a fine grained microstructure with a high fraction of carbides and a γ/γ′ microstructure was obtained. The compressive yield strength at room temperature was found to be 45% higher than that of previously reported results for Co-based superalloys. A similar level of strength was found at 700 °C. These extraordinary properties can be explained due to the multitude of hardening mechanisms that sintered Co-based superalloys possess: γ′ precipitation, carbide formation and the ultra-fine γ-grain size promoted by the fast consolidation technique.
Nine 3,5-dihydro-4H-pyrido2,3-b1,4diazepin-4-ones (17–25), some of which contain fluoro-substituents, have been regiospecifically prepared by reaction of 2,3-diaminopyridines with ethyl ...aroylacetates. In two cases, open intermediates have been isolated and these are related to the reaction pathway. The X-ray crystal structure of 1-methyl-4-phenyl-3,5-dihydro-4H-pyrido2,3-b1,4diazepin-4-one (23) has been solved (formula, C15H13N3O; crystal system, monoclinic; space group, C2/c). This is an asymmetric unit constituted by a single nonplanar molecule and its conformational enantiomer due to the presence of the seven-membered diazepin-2-one moiety, which introduces a certain degree of torsion in the adjacent pyridine ring. The 1H, 13C, 15N, and 19F NMR spectra were obtained and the chemical shifts, together with those of the previously published 1,3-dihydro-2H-benzob1,4diazepin-2-ones (1–16), i.e., a total of 544 values, were successfully compared with the chemical shifts calculated at the gauge invariant atomic orbital (GIAO)/Becke, three-parameter, Lee–Yang–Parr (B3LYP)/6-311++G(d,p) level. The seven-membered ring inversion barrier in 5-benzyl-2-phenyl-3,5-dihydro-4H-pyrido2,3-b1,4diazepin-4-one (25) was determined and, in conjunction with the data from the literature, compared with the B3LYP/6-311++G(d,p) computed values. This allowed the determination of several structural effects. The rotation about the exocyclic N1–CR bond was also calculated and its dynamic properties were discussed.
Carbonaceous nanostructures such as carbon nanotubes, graphene and transparent carbon-based thin films are envisioned to be part of the next generation of electronic devices, mechanical structures, ...and energy-storage systems. To synthesize these nanostructures on a large scale by chemical vapor deposition, large-area, flexible substrates are needed. Here, we studied the role of a metallic foil, stainless steel, as a self-catalytic substrate for carbon nanostructure synthesis. As a result, vertically aligned carbon nanotubes and amorphous carbon thin films were simultaneously obtained. We further showed that the evolution of the stainless steel foil during the different steps of the process played a critical role in carbon nanotubes and carbon thin film growth. A better understanding of how the growth of these carbon nanostructures is affected by stainless steel evolution under chemical vapor deposition conditions will enable the synthesis of hybrid carbon nanotubes/amorphous carbon nanostructures and pave the way to scale-up of their low-cost production.
A new Zn(II)/Eu(III) compound with the N,N′-ethylenebis(5-carboxysalicylideneamino) ligand (H4Salendc) has been synthesised and its photophysical behaviour studied. This species, ...Zn(Salendc)Eu(CH3COO)(DMSO)·xH2O·0.5CH3CN (x = 3.5–4), has been characterised by XRD, XEDS and SEM and HTEM microscopies. Experimental results suggest the formation of a one-dimensional polymeric compound. The compound behaves as a luminescent material in the solid state. Moreover, it exhibits acidochromic properties upon the addition of a few drops of HCl and in the presence of its vapours. The emission intensity of the bands attributed to the Eu(III) ion can be also modulated by the temperature and by the presence of water, so that this species is a good candidate for its use as a luminescent acid, temperature and water sensor.
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•A novel luminescent Zn(II)/Eu(III) polymer complex has been synthesised.•The polymer morphology, analysed by TEM, suggests the formation of Zn/Eu chains.•The rupture of the polymer chains originates dramatic changes in the emission.•Coordination of DMSO molecules seems to be essential for the luminescence behaviour.•The compound exhibits reversible thermo- and acidochromic properties.
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