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► La, Nd, Sm and Sr as promoters of Pt/KL catalysts for hydrogenation of citral. ► Lanthanides favor the Pt dispersion and formation of electron-deficient Pt species. ► Lanthanides ...enhance formation of unsaturated alcohols and inhibit that of citronellal. ► Sr difficults the Pt dispersion and promotes formation of electron-rich Pt species. ► Sr improves the formation of geraniol
+
nerol and enhances that of citronellol.
The effect of Sr and some lanthanides (La, Nd, Sm) as promoters of Pt/KL supported catalysts is analyzed in the selective hydrogenation of citral in the liquid phase. Characterization of the catalysts by XRD, N
2 adsorption, H
2 chemisorption, TPD of NH
3, XPS and competitive hydrogenation of benzene/toluene mixtures shows that impregnation of KL zeolite with Sr(NO
3)
2 in aqueous solution, followed by calcination prior to the incorporation of Pt, increases the surface basicity of the zeolite, which hinders the dispersion of Pt and promotes the formation of electron-rich platinum nanoparticles (Pt
δ−). Ion exchange of K
+ by rare earth cations (La
3+, Nd
3+ and Sm
3+) increases the surface acidity of the zeolite and favors the dispersion of Pt, but with preferential location at the external surface of the zeolite. Furthermore, acidity promotes the formation of electron-deficient metal species (Pt
δ+). Catalytic performances for the citral hydrogenation at 323
K and 5
MPa show that strontium addition enhances the hydrogenation activity of Pt, thus favoring the formation of citronellol as main reaction product (
S
=
80%) and increasing the yield to geraniol and nerol. Lanthanides as countercations diminish the overall hydrogenation activity of Pt/KL catalysts, but improve their selectivity towards unsaturated alcohols. Selectivity towards the reaction products is related to the mode and strength of the electronic interactions of the conjugated unsaturated bonds of citral reactant molecules with the metal surface species Pt
0, Pt
δ+ or Pt
δ− on the zeolite.
A series of catalysts comprising well-distributed Pd nanoparticles incorporated on silylated SiO
2
were fabricated by the wet impregnation method and investigated in the selective hydrogenation of ...paracetamol to 4-acetamidocyclohexanone. The catalysts calcined at different temperatures were characterized by TG, FT-IR, N
2
physisorption, TPR and XPS. The results showed that organic modification led to a catalyst surface composed of stable Si-(CH
3
)
3
species even after calcination at 300 °C. Also, changes occurred in the size and electronic properties of the Pd particles through the different amounts of grafted groups on the SiO
2
support. The mode of adsorption of the paracetamol molecule was influenced by the quite bulky organic groups on the support, resulting in a significant improvement in selectivity towards 4-acetamidocyclohexanone and preventing full hydrogenation to some extent. The best result was obtained on the silylated Pd catalyst calcined at 500 °C, with 64.9% selectivity to keto at the paracetamol conversion of 60.5%, while the non-silylated SiO
2
supported Pd catalyst gave 4-acetamidocyclohexanone selectivity of 29.1% at 53.8% conversion.
The decomposition of Pd-H species influences the hydrogenation activity and a positive effect on the selectivity of keto has been identified as due to the steric hindrances of the sily groups on the support.
The interaction of organic chemicals with the surface of carbon nanotubes (CNTs) has been studied by immersion calorimetry revealing new information about the unique CNT surface structures. The ...curvature of the graphene sheets of in the CNTs increases the adsorption strength of aromatic compounds compared to flat graphite surfaces. For a given CNT, the adsorption affinity of a non-polar aromatic molecule correlated poorly with the CNT hydrophobicity. Comparison of the immersion enthalpies that evolved when the solids were immersed in organic chemicals reveals the formation of π–π stacking interactions, H-bonds or electron–accepting interactions depending on the CNT surfaces and on the immersion substrate. The number of oxygen groups on CNTs seems to modify the electron density of their surfaces and therefore the interaction mechanism with the adsorbates.
Invasive Coronary Angiography (ICA) images are considered the gold standard for assessing the state of the coronary arteries. Deep learning classification methods are widely used and well-developed ...in different areas where medical imaging evaluation has an essential impact due to the development of computer-aided diagnosis systems that can support physicians in their clinical procedures. In this paper, a new performance analysis of deep learning methods for binary ICA classification with different lesion degrees is reported. To reach this goal, an annotated dataset of ICA images containing the ground truth, the location of lesions, and seven possible severity degrees ranging between 0% and 100% was employed. The ICA images were divided into "lesion" or "non-lesion" patches. We aim to study how binary classification performance is affected by the different lesion degrees considered in the positive class. Therefore, five Convolutional Neural Network architectures - DenseNet-201, MobileNet-V2, NasNet-Mobile, ResNet-18, and ResNet-50 - were trained with different input images where different lesion degree ranges were gradually incorporated until considering the seven lesion degrees. Besides, four types of experiments with and without data augmentation were designed, whose F-measure and Area Under Curve (AUC) were computed. Reported results achieved an F-measure and AUC of 92.7% and 98.1%, respectively. However, lesion classification is highly affected by the degree of the lesion intended to be classified, with 15% less accuracy when < 99% lesion patches are present.
The purpose of this study was to investigate the mechanisms underlying sex differences in the role of spinal α6-subunit containing GABAA (α6GABAA) receptors in rats with neuropathic pain. Intrathecal ...2,5-dihydro-7-methoxy-2-(4-methoxyphenyl)-3H-pyrazolo 4,3-c quinoline-3-one (PZ-II-029, positive allosteric modulator of α6GABAA receptors) reduced tactile allodynia in female but not in male rats with neuropathic pain. PZ-II-029 was also more effective in females than males in inflammatory and nociplastic pain. Ovariectomy abated the antiallodynic effect of PZ-II-029 in neuropathic rats, whereas 17β-estradiol or 4,4′,4''-(4-propyl-1H-pyrazole-1,3,5-triyl) trisphenol (PPT), estradiol receptor-α agonist, restored the effect of PZ-II-029 in ovariectomized rats. Blockade of estradiol receptor-α, using MPP (1,3-bis(4-hydroxyphenyl)-4-methyl-5-4-(2-piperidinylethoxy) phenol-1H-pyrazole dihydrochloride), prevented the effect of 17β-estradiol on PZ-II-029-induced antiallodynia in ovariectomized neuropathic females. Nerve injury reduced α6GABAA receptor protein expression at the dorsal root ganglia (DRG) and spinal cord of intact and ovariectomized female rats. In this last group, reconstitution with 17β-estradiol fully restored its expression in DRG and spinal cord. In male rats, nerve injury reduced α6GABAA receptor protein expression only at the spinal cord. Nerve injury enhanced estradiol receptor-α protein expression at the DRG in intact non-ovariectomized rats. However, ovariectomy decreased estradiol receptor-α protein expression at the DRG. In the spinal cord there were no changes in estradiol receptor-α protein expression. 17β-estradiol restored estradiol receptor-α protein expression at the DRG and increased it at the spinal cord of neuropathic rats. These data suggest that 17β-estradiol modulates the expression and function of the α6GABAA receptor through its interaction with estradiol receptor-α in female rats.
Graphene oxide and multiwall carbon nanotubes (CNTs) were chemically modified by treatment with urea and subsequent annealing at different temperatures. These materials were used as supports for gold ...nanoparticles and the resulting samples have been applied as catalysts in the 1,3-butadiene partial hydrogenation reaction. The supports and catalysts were exhaustively characterized. It was shown that urea treatments modified the graphene surfaces and the morphology of CNTs, in both cases with incorporation of significant amounts of different nitrogen surface groups. The presence of these groups on few layered graphene or on CNT surfaces modifies the gold precipitation-deposition process during catalyst preparation, giving place to different amounts of incorporated gold on the various supports. The obtained catalytic results suggested that the partial hydrogenation requires limited availability of hydrogen, and for this the migration through adsorbed species between the metal and support to initiate the hydrogenation, probably by a spillover mechanism, seems to be a required step. In general intramolecular selectivity is structure-sensitive meanwhile catalytic activity is not structure-sensitive, as evidenced when the gold nanoparticle sizes are decreased.
GO and multiwall CNTs were modified by treatment with urea and annealing at different temperatures incorporating N adatoms. AuGO and AuCNT catalysts were prepared and their activity depended on the Au NP size and the characteristics of the support.
Angiogenesis is a requirement for the sustained growth and proliferation of solid tumors, and the development of new compounds that induce a sustained inhibition of the proangiogenic signaling ...generated by tumor hypoxia still remains as an important unmet need. In this work, we describe a new antiangiogenic compound (22) that inhibits proangiogenic signaling under hypoxic conditions in breast cancer cells. Compound 22 blocks the MAPK pathway, impairs cellular migration under hypoxic conditions, and regulates a set of genes related to angiogenesis. These responses are mediated by HIF-1α, since the effects of compound 22 mostly disappear when its expression is knocked-down. Furthermore, administration of compound 22 in a xenograft model of breast cancer produced tumor growth reductions ranging from 46 to 55% in 38% of the treated animals without causing any toxic side effects. Importantly, in the responding tumors, a significant reduction in the number of blood vessels was observed, further supporting the mechanism of action of the compound. These findings provide a rationale for the development of new antiangiogenic compounds that could eventually lead to new drugs suitable for the treatment of some types of tumors either alone or in combination with other agents.
The Gamma-aminobutyric acid type A receptor (GABA-A receptor) is affected by ethanol concentrations equivalent to those reached during social drinking. At these concentrations, ethanol usually causes ...impairment in reaction and motor times in most, but not all, individuals.
To study the effect of GABA-A receptor variability in motor and reaction times, and the effect of low ethanol doses.
Two hundred and fifty healthy subjects received one single dose of 0.5 g/Kg ethanol
. Reaction and motor times were determined before ethanol challenge (basal), and when participants reached peak ethanol concentrations. We analyzed all common missense polymorphisms described in the 19 genes coding for the GABA-A receptor subunits by using TaqMan probes.
The
rs4454083 T/C polymorphisms were related to motor times, with individuals carrying the C/C genotype having faster motor times, both, at basal and at peak ethanol concentrations. The
rs2229940 T/T genotype was associated to faster reaction times and with lower ethanol effects, determined as the difference between basal reaction time and reaction time at peak concentrations. All these associations remained significant after correction for multiple comparisons. No significant associations were observed for the common missense SNPs
rs12910925,
rs211035,
rs1139916,
rs1063310,
rs3810651,
rs12200969 or rs1186902,
rs282129, and
rs832032.
This study provides novel information supporting a role of missense GABA-A receptor polymorphisms in reaction time, motor time and effects of low ethanol doses
.
Formic acid, a major product of biomass processing, is regarded as a potential liquid carrier for hydrogen storage and delivery. The catalytic dehydrogenation of FA to generate hydrogen using ...heterogeneous catalysts is of great interest. Ni based catalysts supported on silica were synthesized by incipient wet impregnation. The effect of doping with an alkaline earth metal (calcium) was studied, and the solids were tested in the formic acid decomposition reaction to produce hydrogen. The catalysts were characterized by X-ray diffraction (XRD), X-ray photoelectron spectroscopy (XPS), temperature-programmed reduction (TPR), Fourier transform infrared spectroscopy (FTIR), transmission electron microscopy (TEM), and programmed temperature surface reaction (TPSR). The catalyst doped with 19.3 wt.% of Ca showed 100% conversion of formic acid at 160 °C, with a 92% of selectivity to hydrogen. In addition, all the tested materials were promising for their application, since they showed catalytic behaviors (conversion and selectivity to hydrogen) comparable to those of noble metals reported in the literature.
► Enthalpies of CO adsorption on Ru/carbon catalysts ex-RuCl3 are diminished. ► Oxygen groups at activated carbon surfaces do not modified the Ru surface sites. ► Homogeneity of surface site ...distributions is higher for Ru-CNTs than for Ru-HSAG. ► A possible poisoning effect of Cl species over Ru surface sites has been detected.
Chemisorption of CO combined with microcalorimetry has been applied to study the nature, number and adsorption strength distribution of surface sites exposed by carbon-supported Ru catalysts. A comparative analysis of the CO chemisorption on different Ru catalysts, prepared using two different metal precursors, RuCl3·xH2O and Ru(NO)(NO3)3, has been carried out. An activated carbon and the corresponding derivative where oxygen surface groups were incorporated, as well as carbon nanotubes and a high surface area graphite, were used as catalytic supports. Based on previous temperature programmed reduction studies, all the catalysts were reduced under hydrogen flow at 523K or at 573K. The CO adsorption differential enthalpy profiles show that Ru(NO)(NO3)3 precursor produces more homogeneous surface site distribution in the Ru nanocrystals, in comparison with those prepared from RuCl3, as well as higher values of enthalpies in the medium range of coverage. As a possible explanation for this effect, residual chloride species remaining after reduction treatment in the ex-chloride catalysts, that can be anchored to the Ru nanoparticles weakening the CO adsorption, have been considered. This behavior occurs for the three studied carbon supports. On the other hand, the oxygen surface groups incorporated on the activated carbon seem not to modify the CO adsorption properties of the catalysts, independently of the precursor employed.
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