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Liver cirrhosis is a major cause of death worldwide. Cirrhosis develops after a long asymptomatic period of fibrosis progression, with the diagnosis frequently occurring late, when major complications or cancer develop. Few reliable tools exist for timely identification of individuals at risk of cirrhosis to allow for early intervention. We aimed to develop a novel score to identify individuals at risk for future liver-related outcomes. more...

El objetivo del estudio fue establecer posible relación entre los tratamientos con mitomicina-C (MMC) y bacilo de Calmette-Guérin (BCG) y la afectación en la calidad de vida.

El objetivo del estudio fue establecer los factores que se relacionan de forma independiente con el desarrollo de resistencia a la castración (RC) a medio plazo en el cáncer de próstata (CP).

El objetivo fue comprobar si las clasificaciones ecográficas de la Society for Fetal Urology(SFU) y la Urinary Tract Dilatationn classification(UTD) para la dilatación del tracto urinario postnatal eran capaces de predecir la necesidad de tratamiento quirúrgico o la resolución espontánea de la dilatación. more...

El objetivo fue estudiar la relación entre la determinación cuantitativa de ARNm (hTERT) en pacientes con tumor vesical, antecedentes de tumor vesical y en sujetos sin antecedentes de esta neoplasia. more...

Background/Objectives:Growing evidence implicates neuroinflammation in the pathogenesis of diet-induced obesity and cognitive dysfunction in rodent models. Obesity is associated with reduced white matter integrity and cognitive decline. Circulating lipopolysaccharide binding protein (LBP) concentration is known to be increased in patients with obesity. Here, we aimed to evaluate whether circulating LBP is associated longitudinally with white matter structure and cognitive performance according to obesity status.Subjects/Methods:This longitudinal study analyzed circulating LBP (ELISA), DTI-metrics (axial diffusivity (L1), fractional anisotropy (FA) and radial diffusivity (RD)) in specific regions of the white matter of 24 consecutive middle-aged obese subjects (13 women) and 20 healthy volunteers (10 women) at baseline and two years later. Digit Span Test (DST) was used as a measure of working memory/short-term verbal memory.Results:Circulating LBP concentration was associated with FA and L1 values of several white matter regions both at baseline and follow-up. The associations remained significant after controlling for age, BMI, fat mass and plasma high sensitivity C-reactive protein. Importantly, the increase in LBP over time impacted negatively on FA and L1 values and on DST performance.Conclusions:Circulating LBP associates with brain white matter integrity and working memory/short-term verbal memory in both obese and non-obese subjects. more...

El objetivo ha sido mostrar la satisfacción y adherencia al tratamiento en disfunción eréctil (DE) a medio y largo plazo.

En la literatura publicada queda demostrado que el uso del PSA es incorrecto en ocasiones, solicitando este marcador en varones muy jóvenes o muy ancianos, y repitiendo determinaciones en cortos periodos de tiempo. El objetivo principal de este trabajo ha sido describir la utilización del PSA en la práctica diaria por parte de los médicos de atención primaria de nuestra área, tratando aspectos como la importancia de la edad de los pacientes, el valor en el cribado del cáncer de próstata, o las creencias subjetivas sobre su utilidad. Como objetivo secundario se ha comparado el uso y las creencias entre los médicos que dicen conocer bien el PSA y los que no. more...

Background/Objective:Many controversies regarding the association of liver miRNAs with obesity and nonalcoholic fatty liver diseases (NAFLD) call for additional validations. This study sought to investigate variations in genes and hepatic miRNAs in a sample of obese patients with or without NAFLD and human hepatocytes (HH).Subjects/Methods:A total of 60 non-consecutive obese women following bariatric surgery were recruited. Subjects were classified as NAFLD (n=17), borderline (n=24) and controls (n=19) with normal enzymatic profile, liver histology and ultrasound assessments. Profiling of 744 miRNAs was performed in 8 obese women with no sign of hepatic disease and 11 NAFLD patients. Additional validation and expression of genes related to de novo fatty acid (FA) biosynthesis, uptake, transport and β-oxidation; glucose metabolism, and inflammation was tested in the extended sample. Induction of NAFLD-related genes and miRNAs was examined in HepG2 cells and primary HH treated with palmitic acid (PA), a combination of palmitate and oleic acid, or high glucose, and insulin (HG) mimicking insulin resistance in NAFLD.Results:In the discovery sample, 14 miRNAs were associated with NAFLD. Analyses in the extended sample confirmed decreased miR-139-5p, miR-30b-5p, miR-122-5p and miR-422a, and increased miR-146b-5p in obese subjects with NAFLD. Multiple linear regression analyses disclosed that NAFLD contributed independently to explain miR-139-5p (P=0.005), miR-30b-5p (P=0.005), miR-122-5p (P=0.021), miR-422a (P=0.007) and miR-146a (P=0.033) expression variance after controlling for confounders. Decreased miR-122-5p in liver was associated with impaired FA usage. Expression of inflammatory and macrophage-related genes was opposite to decreased miR-30b-5p, miR-139-5p and miR-422a, whereas increased miR-146b-5p was associated with FABP4 and decreased glucose metabolism and FA mobilization. In partial agreement, PA (but not HG) led to decreased miR-139-5p, miR-30b-5p, miR-422a and miR-146a in vitro, in parallel with increased lipogenesis and FA transport, decreased glucose metabolism and diminished FA oxidation.Conclusion:This study confirms decreased liver glucose and lipid metabolism but increased FA biosynthesis coupled with changes in five unique miRNAs in obese patients with NAFLD. more...

Comparar los resultados de eficacia y seguridad del láser tulio 150W frente a láser verde 120W en el tratamiento de la hiperplasia benigna de próstata a corto plazo (12 meses de la cirugía).

Two experiments were conducted to examine the influence of protein and virginiamycin (VM) supplementation on feedlot growth performance, digestion, and metabolizable AA (MAA) supply of calf-fed Holstein steers. Growth performance and dietary energetics were evaluated in 120 Holstein steers (127 ± 9 kg). During the initial 112-d feeding period, a steam-flaked corn-based diet was balanced to meet either 100% (MAB) or 87% (UREA) of MAA requirements. Diets were supplemented with or without 22.5 mg/kg VM in a 2 × 2 factorial arrangement. Subsequently (d 112 to 308), all steers received the UREA diet with or without VM. During the initial 112-d, MAB increased ADG, G:F, and dietary NE (P< 0.01). Thereafter, when all steers received the UREA diet, ADG, G:F, and dietary NE were not different (P> 0.10) across initial supplementation treatments. Overall (d 1 to 308), MAB did not affect ADG (P> 0.10) but enhanced G:F efficiency (P= 0.03) and dietary NE (P= 0.05). During the initial 112-d period and through the remainder of the experiment, VM increased G:F (P< 0.01) and dietary NE (P< 0.01). Four Holstein steers (146 ± 4 kg) with cannulas in the rumen and proximal duodenum were used in a 4 × 4 Latin square design to evaluate initial 112-d treatment effects on digestive function. There were no treatment effects (P> 0.10) on ruminal digestion of OM, NDF, starch, microbial efficiency, or total tract digestion of OM and NDF. The MAB increased indispensable AA flow to the small intestine (P< 0.01) and total tract digestion of N (P< 0.01) and starch (P= 0.04). Observed AA supply to small intestine was in agreement with expected supply (r2= 0.96). Virginiamycin decreased (P= 0.04) nonammonia N flow to the small intestine and did not affect (P> 0.10) total tract N digestion. Extrapolating from AA supplies in the metabolism study, MAB satisfied indispensable AA requirements during the initial 112-d period, whereas the UREA diet met 73.5% and 79.2% of methionine and lysine requirements, respectively. During the subsequent periods (d 112 to 308) indispensable AA supplies exceeded theoretical requirements. We conclude that enhancements in energy utilization when diets are balanced to meet MAA requirements of calf-fed Holstein steers during the initial 112-d feedlot period remain appreciable throughout time on feed. Virginiamycin enhanced efficiency of energy utilization throughout the feedlot growing-finishing period. more...

Los cilindros de próstata obtenidos en la biopsia transrectal suelen enviarse en viales separados para su procesamiento anatomopatológico. Aunque es una práctica frecuente, existen trabajos controvertidos sobre su utilidad. more...

A set of six lithic tools, unearthed along 2011 in two karst sites of the Guadalteba County (Málaga, Spain), has been nondestructively investigated by Raman spectroscopy and laboratory x-ray diffraction. From a chemist’s point of view, our goal is to develop a systematic screening protocol for a quick, easy, low cost and nondestructive characterization of archaeological flints based on Raman spectroscopy, x-ray diffraction and Rietveld refinement. In this paper, we firstly made use of Raman spectroscopy to determine, in a semiquantitative way, but with the generic advantage of a faster data acquisition than x-ray diffraction, the surface content of moganite of each lithic tool, from the ratio between the relative intensities of the two Raman-active symmetric stretching vibrations (A1modes) of α-quartz (465 cm−1) and moganite (501 cm−1). The precise bulk quartz/moganite weight content was then accurately quantified by means of high-quality x-ray diffraction, followed by Rietveld refinement. We found a general good correlation between Raman and x-ray data. Nonetheless, as recently reported in the scientific literature by other authors, the vibrational spectroscopic quantification of moganite in silica rocks like flint and chert have to be performed very cautiously, to avoid undesired interferences from other Raman features due to the eventual presence of silanol (SiOH) groups, which could finally lead to an overestimation of the surface moganite concentration. As reported in such a recent article, a useful treatment to reduce the interference from silanol-bands is to heat the samples prior to their Raman analysis at a minimum of 600 ºC (but better at 700 or 800 ºC) for silanol “dehydration”. This, in our opinion, may be for sure a satisfactory procedure when studying flint or chert samples of a “geological origin”. But not of practical use when studying lithic tools which were manufactured by men thousands and thousands of years ago. more...

La afectación de las vesículas seminales en el cáncer de próstata puede afectar al pronóstico y condicionar el tratamiento. El objetivo es conocer si podemos predecir su infiltración en el momento de realizar la biopsia prostática para saber cuándo hay que indicar la biopsia de las mismas. more...

The formation energy and stability of radical anions in a series of 12 phenyl- and 2-thienyl-ended linear, symmetric azomethines and azines were investigated by cyclic voltammetry. Replacing 1,4-phenylene with 2,5-thienylene cores and substitution with cyano or methyl moieties have allowed the lowering of lowest unoccupied molecular orbital energy levels even by 1 eV. Methyl capping stabilizes electron carriers (radical anions) toward dimerization, and the mechanism of such radical anion dimerization has been clarified by cyclic voltammetric kinetic analysis. The results have been compared with optical parameters and supported by density functional theory calculations. more...

Gold nanoparticles capped with cyclopentadithiophene via hexylsulfide bridges have undergone FTIR and Raman analysis, before and after dithiophene oxidative coupling, with the support of DFT calculations. A strong SEIRA effect has revealed an almost parallel disposition of the oligothiophene ring plane in respect to the gold surface, enhanced by polymerization. An unusual SERS enhancement of the oligothiophene ring stretching band has been assigned to coordination of the gold surface of neighboring particles via the thiophene sulfur atoms. more...

Gold nanocrystals in a toluene solution were aggregated by several thiophene and pyrrole oligomers as shown by surface plasmon (SP) spectroscopy and TEM analysis. The rate of aggregation can be controlled by varying the oligomer type and concentration. Two distinct regimes of aggregation kinetics are observed:  (1) at low oligomer concentrations, aggregation is slow and dependent on the gold nanocrystal concentration with production of a SP band at ca. 700 nm and (2) at high oligomer concentrations, aggregation is very fast and produces a SP band at ca. 570 nm. The results suggest that, in general, at high oligomer concentrations, the linker molecules form more dense layers via perpendicular orientation toward the metal plane, whereas a parallel orientation is obtained at low concentrations. TEM analysis indicates in the high concentration regime that there is formation of spherical or dendritic superclusters depending on the aggregating oligomer. FTIR analysis of the terthiophene and dipyrrole gold aggregates has shown the presence of adsorbed ligand molecules with surface enhancements of some bands, giving features particular to parallel and perpendicular coordination, respectively. more...

Abstract: Let G be a discrete subgroup of PU(2,1); G acts on $$P^2_\mathbb C$$ preserving the unit ball $$\mathbf H^2 _{\mathbb C}$$, equipped with the Bergman metric. Let $$L(G) \subset S^3 = \partial \mathbf H^2 _{\mathbb C}$$ be the limit set of G in the sense of Chen–Greenberg, and let$$\Lambda(G) \subset P^2_{\mathbb C}$$ be the limit set of the G-action on$$P^2_{\mathbb C}$$ in the sense of Kulkarni. We prove that L(G) = Λ(G) ∩ S 3 and Λ(G) is the union of all complex projective lines in $$P^2_\mathbb C$$ which are tangent to S 3 at a point in L(G). more...

A series of quinoidal oligothiophenes have been investigated by means of solid‐state Fourier‐transform (FT)‐Raman and electron spin resonance (ESR) spectroscopies complemented with density functional theory calculations. FT‐Raman spectra recorded as a function of temperature show that, upon laser irradiation, the molecules undergo a reversible structural evolution from a quinoid‐type pattern at low temperature to an aromatic‐type pattern at high temperature. Moreover, ESR spectra show that a portion of these compounds exists in a biradical state at room temperature. These seemingly disconnected findings and others, such as conformational isomerism, are consistently explained by the consideration of biradical species associated with the presence of low‐lying triplet electronic states. In addition to the well‐established versatility of quinoidal oligothiophenes regarding ambipolar electrical actuation in field‐effect transistors, the exhibition of dual electrical and magnetic behavior leads to the prospect of new materials that have tunable electrical, optical, and magnetic properties. more...

Sol-gel titania was phosphated in two different ways: i) “in situ” phosphation using phosphoric acid as hydrolysis catalyst in the titanium butoxide gelling system, and ii) gelling with nitric acid and impregnation with ammonium phosphate solution. In calcined samples at 600°C a positive effect on the specific surface area for the “in situ” phosphated sample was found. X-ray diffraction patterns showed that the presence of phosphates ions stabilized the anatase phase. FTIR-pyridine adsorption identified only Lewis acid sites in phosphated samples. In the isopropanol decomposition for “in situ” phosphated titania, the activity was six times higher than that obtained for titania phosphated by impregnation, showing strong acidity for the in situ phosphated TiO2catalyst.Sol-gel titania was phosphated in two different ways: i) “in situ” phosphation using phosphoric acid as hydrolysis catalyst in the titanium butoxide gelling system, and ii) gelling with nitric acid and impregnation with ammonium phosphate solution. In calcined samples at 600°C a positive effect on the specific surface area for the “in situ” phosphated sample was found. X-ray diffraction patterns showed that the presence of phosphates ions stabilized the anatase phase. FTIR-pyridine adsorption identified only Lewis acid sites in phosphated samples. In the isopropanol decomposition for “in situ” phosphated titania, the activity was six times higher than that obtained for titania phosphated by impregnation, showing strong acidity for the in situ phosphated TiO2catalyst. more...

The magnetic and conductive properties of a series of quinoidal oligothiophenes, that is, bis(dicyanomethylene)oligothiophenes (TnCN4, n = 2−4), have been investigated in the solid state and (for magnetic analysis) in solution, and the results have been compared with those from density functional theory (DFT) calculations. Solution electron spin resonance (ESR) spectra of radical cations and anions are characterized by hyperfine structures due to coupling with nitrogen and thiophene hydrogen atoms. Neutral solutions are ESR active, indicating a significant presence of diradical species with no hyperfine structure. ESR spectra of powder samples at room temperature give a concentration of radical species up to 1 mol % (T3CN4), that is, 0.5% of the compound exists in a diradical state. The percentage decreases dramatically from T3CN4 to T2CN4, as a result of the decreased number of aromatic rings. The diradical concentration increases with temperature according to activation energies which are higher for the shorter members and in very good agreement with DFT calculations. Tetrahexyl-substituted T4CN4 is redox conducting at the neutral-polaron mixed oxidation level with a maximum conductivity of 0.03 S cm-1, about two orders of magnitude higher in comparison with an aromatic tetrahexyl-substituted octathiophene. more...

This paper presents a Java-3D-based software library for modelling industrial robot arms and programming simulation and tele-operation environments. Its main features are its portability, since it is developed with Java, its simplicity in defining different robots and including them in the final application, as well as its collision detection management. The library has been applied to the development of a simulation and tele-operation system, focused on the training of Robotics, which is also briefly described here. more...

Sol-gel titania was sulfated by using sulfuric acid as hydrolysis catalyst, or by impregnating with ammonium sulfate fresh samples prepared with nitric acid or ammonium hydroxide as hydrolysis catalyst. Samples were characterized with X-ray powder diffraction, infrared spectroscopy, thermogravimetry and atomic absorption spectroscopy. Sulfate ions were found anchored to brookite and anatase phases, because they have short O—O atomic bond lengths slightly larger than the largest O—O bond length of sulfate ion. Since the shortest O—O atomic bond in anatase is smaller than the one in brookite, the sulfate ions are then less deformed when they are anchored to anatase, and consequently more stable. Therefore when the sample temperature is raised, the brookite with sulfate ions was transformed mainly to anatase and not into rutile, which is the most probably transformation when these ions are not involved. Sulfate ions also hindered anatase and brookite crystallite growing and stabilized the crystalline structure of anatase. When the sulfate ions are lost the crystalline anatase phase is transformed into rutile, leaving a large number of vacancies that favored atom diffusion and consequently the growing of rutile crystallites. The crystalline evolution of the samples as a function of the annealing temperature is almost independent of the sulfating method. more...

The type of anion (fluoride, chloride, and sulfate) used in the synthesis cation exchange process of the FSM-16 mesoporous material modified its thermal stability. Compared with chloride and sulfate anions, the presence of fluoride anions gave rise to an increase of the wall thickness, which explains the higher thermal stability of this material. The fluoride anions also promote the formation of a more hydrophobic solid. The hydroxyl groups of this material, with a lesser population density than that present on the solids obtained with chloride and sulfate anions, were more active in H−D isotopic exchange with deuterium at 573 K. more...

The in situ electronic absorption and Fourier transform Raman scattering spectra recorded during the electrochemical oxidation of two α,α‘-end-capped 4-[bis(4-methylphenyl)amino]phenyl oligothiophenes with three and four thiophene rings are reported. We have characterized a radical cation and a dication species in the trimer and up to a radical trication in the tetramer. The electronic and the Raman spectra have been interpreted and assigned with the final goal of obtaining structural information about the contribution of the bis(4-methylphenyl)amino groups, the innermost phenyl rings, and the central thienyl chain length to the stabilization of the electrochemically induced charged defects. The experimental data have been supported by theoretical calculations in the framework of the density functional theory. The charged defects can be viewed as models of hole carriers or photoexcitons in real devices. more...

Zirconium (IV)-n-butoxide and tungstophosphoric acid (WP) were co-gelled at pH 3, 5 and 7 with HCl acid, C2H4O2acid and NH4OH, respectively. Pyridine adsorption bands at 1610 and 1442 cm−1corresponding to Lewis acidic sites were observed by FTIR spectroscopy. Acidity determined by ammonia thermodesorption shows values around 1100 μmol of NH3/g, which correspond to solids showing super acidity. It was found that the incorporation of WP to gelling zirconia delay the formation of tetragonal zirconia. Raman spectroscopy shows the stabilization of the Keggin structure on zirconia thermally treated at 400°C. more...

A series of ZrO2–WOx samples was hydrothermally prepared in an autoclave at autogenous pressure in a range of temperatures from 145 to 225 °C for 24 h. The materials were characterized by elemental analysis, X-ray diffraction, nitrogen physisorption and FT-IR spectroscopy of both structure and adsorbed pyridine. The Rietvelt refinement of the X-ray diffraction patterns was also performed. The formation of crystalline products was detected at synthesis temperatures as low as 145 °C. Pure zirconium oxihydroxide gel yielded a mixture of metastable t-ZrO2 (63%) and m-ZrO2 (37%) zirconia phases when treated at 145 °C. When tungsten (15 wt.% as WO3) was added to the synthesis mixture, only an amorphous phase of t-ZrO2 was detected. Both the crystallization of t-ZrO2 phase and the t-ZrO2 to m-ZrO2 phase transformation, caused by hydrothermal treatment, were retarded by the presence of tungsten. In this way a microcrystalline ZrO2–WOx of 309 m2 g−1 was prepared under hydrothermal conditions at 145 °C. The material becomes progressively more crystalline with increasing synthesis temperature. At 225 °C a well-crystallized material (79% of t-ZrO2 and 21% of m-ZrO2 phases) was obtained. Interestingly, the crystallite sizes of both phases were not too different, 15.6 and 13 nm for t-ZrO2 and m-ZrO2 respectively. In all the samples, crystalline phases associated with WOx species were not unambiguously identified by XRD. FT-IR spectroscopy of W-promoted zirconia showed a band at 943 cm−1 not present in non-tungsten-promoted ZrO2, which was attributed to the W&z.dbd;O stretching mode of octahedrally coordinated tungsten species. Since the lattice parameters of the ZrO2 structure were not modified by the presence of tungsten, the WOx species must be highly dispersed and strongly bound to the ZrO2 surface. Post-synthesis calcination treatment at higher temperatures (560, 700 and 800 °C) brought about sintering of these dispersed tungsten species and the formation of a more bulky tungsten oxide species characterized by two FT-IR vibration bands at 970 and 1100 cm−1. more...

A series of ZrO₂–WO_x samples was hydrothermally prepared in an autoclave at autogenous pressure in a range of temperatures from 145 to 225 °C for 24 h. The materials were characterized by elemental analysis, X-ray diffraction, nitrogen physisorption and FT-IR spectroscopy of both structure and adsorbed pyridine. The Rietvelt refinement of the X-ray diffraction patterns was also performed. The formation of crystalline products was detected at synthesis temperatures as low as 145 °C. Pure zirconium oxihydroxide gel yielded a mixture of metastable t-ZrO₂ (63%) and m-ZrO₂ (37%) zirconia phases when treated at 145 °C. When tungsten (15 wt.% as WO₃) was added to the synthesis mixture, only an amorphous phase of t-ZrO₂ was detected. Both the crystallization of t-ZrO₂ phase and the t-ZrO₂ to m-ZrO₂ phase transformation, caused by hydrothermal treatment, were retarded by the presence of tungsten. In this way a microcrystalline ZrO₂–WO_x of 309 m2 g−1 was prepared under hydrothermal conditions at 145 °C. The material becomes progressively more crystalline with increasing synthesis temperature. At 225 °C a well-crystallized material (79% of t-ZrO₂ and 21% of m-ZrO₂ phases) was obtained. Interestingly, the crystallite sizes of both phases were not too different, 15.6 and 13 nm for t-ZrO₂ and m-ZrO₂ respectively. In all the samples, crystalline phases associated with WO_x species were not unambiguously identified by XRD. FT-IR spectroscopy of W-promoted zirconia showed a band at 943 cm−1 not present in non-tungsten-promoted ZrO₂, which was attributed to the W&z.dbd;O stretching mode of octahedrally coordinated tungsten species. Since the lattice parameters of the ZrO₂ structure were not modified by the presence of tungsten, the WO_x species must be highly dispersed and strongly bound to the ZrO₂ surface. Post-synthesis calcination treatment at higher temperatures (560, 700 and 800 °C) brought about sintering of these dispersed tungsten species and the formation of a more bulky tungsten oxide species characterized by two FT-IR vibration bands at 970 and 1100 cm−1. more...

A surfactant-assisted synthesis method was applied to prepare nanosized ceria particles used as the three-way catalyst supports. The Rietveld refinements of crystalline structures of ceria calcined at various temperatures, together with XRD, FTIR, and TGA techniques, confirm that the surfactant cations are incorporated into the structural network of hydrous cerium oxide during the preparation stage, thus reducing the surface tension and diminishing the shrinkage of the mesoporous channels in the dried materials. The surface area is therefore enhanced but it provokes a significant distortion effect on the structure. It is evidenced by XRD analyses that a well-ordered cubic structure of ceria was formed at a temperature as low as 80 °C. The average crystallite size of ceria is determined by XRD within nanoscale range (i.e., 9−31 nm) when the calcination temperature increases from 80 to 800 °C, which is in good agreement with the data determined by TEM and electron diffraction methods. In addition, cationic defects are present in the crystalline structure of the solids, and the defect concentration in the unit lattice cell decreases as calcination temperature increases. CO chemisorption analysis by FTIR shows that CO may adsorb on Pd/ceria catalyst in different modes:  linear Pd−CO and Ce⁴⁺−CO bonds, bridged Pd(CO)2 bonds, and multibonded Pd2(CO)2 bonds. CO adsorption might lead to CO2 production from CO reacting with lattice oxygen and/or CO disproportionation catalyzed by palladium crystals. The CO oxidzed over the Pd supported catalysts makes it that T50 and T90 for the ceria prepared in the presence of surfactant diminish at 80 °C and 110 °C respectively, which are much lower than the ones prepared without surfactant, mainly due to its defective structure, enhanced surface area, and different CO adsorption behavior. more...

In this paper, we investigate the vibrational properties of a novel family of amorphous molecular materials containing an end-capped oligothiophene backbone of variable length, α,α‘-bis-{4-[bis(4-methylphenyl)amino]phenyl}-oligothiophene, which function as color-tunable emitting materials for organic light-emitting diodes. The advantage of these amorphous oligothiophenes with respect to their crystalline parents is that the fluorescence quantum efficiencies as thin films are quite similar to those commonly found in solution. The thorough analysis of the infrared and Raman spectra of the neutral materials as solids has revealed the uselfulness and selectivity of Raman spectroscopy to determine the efficiency of the π conjugation. Density functional theory B3LYP/3-21G* calculations rendered largely distorted conformations of the 4-[bis(4-methylphenyl)amino]phenyl groups with respect to the thiophene rings least-squares plane, in full accordance with the amorphous nature of the materials. The infrared and Raman spectra of the materials recorded at different temperatures between −170 and +160 °C did not show any substantial change, thus indicating that the materials have a high thermal stability, which has significance for their use as active components in optoelectronic devices. more...

The electronic and the Fourier transform Raman (FT-Raman) spectra of a novel well−barrier−well vinylene-bridged sexithiophene in neutral and in doped states have been recorded. The samples were oxidized chemically, with trifluoroacetic acid or ferric chloride, and electrochemically in dichloromethane solutions. The evolution of the Raman spectral pattern upon oxidation at different anodic potentials has been analyzed for a thin solid film of the material. Experimental observations are explained by the initial generation of a radical cation species followed by the generation of a dication species. A comprehensive assignment of the electronic and Raman spectroscopic features observed in both neutral and oxidized states has been performed on the basis of density functional theory (DFT) calculations. Time-dependent DFT calculations have been performed to calculate the electronic excitation energies. The experimental data and theoretical results give a clear picture of the structure and electronic properties of the charge defects created on this vinylene-bridged sexithiophene. more...

The infrared absorption and Raman scattering spectra recorded during the electrochemical oxidation of two sexithiophenes are reported. Using in situ spectroelectrochemical methods five oxidation states, neutral, radical cation, dication, radical trication, and tetracation of an α,α‘-diphenyl sexithiophene, were studied. The experimental spectra are in agreement with the predictions of the effective conjugation coordinate theory and are in good accordance with theoretical density functional theory calculations. more...

In this paper, the vibrational Fourier transform Raman spectra of two sexithiophenes with the end α-positions substituted with n-hexyl or n-thiohexyl groups are studied. We investigate the effects of the different side chains on the intramolecular π-electron delocalization in neutral state and the charged defects generated upon p-doping. Density functional theory and ab initio quantum-chemical calculations are performed on various oligothiophene model compounds as an aid in the interpretation of the experimental data. The analysis of the peculiar Raman features of these π-conjugated systems has been guided by formalism of the effective conjugation coordinate theory. The Raman study of this class of materials is a powerful tool to derive information about the delocalization of π-electrons in the pristine state and the charged species upon doping. more...

The thermal properties of boehmite with a crystallite size between 1 and 27 nm were analyzed by thermogravimetry and differential thermal analysis, and correlated with its crystallography, crystallite morphology, and the atom bond lengths determined by refining its crystalline structure with the Rietveld method. Boehmite's thermal evolution depended on atom bond lengths: the dehydratation temperature was determined by the interaction between an aluminum atom and the oxygen atom of hydroxyl. After dehydratation, the number of hydroxyls in crystals was larger than expected from stoichiometry, because oxygen atoms on crystal surfaces perpendicular to the (020) plane reacted with hydrogen and hydroxyls in environment. The transition temperature from boehmite into γ-alumina was determined by the hydrogen bond in boehmite. The transformation temperature from transitional aluminas into α-Al2O3also varied with boehmite's crystallite size; however, it was not determined by the amount of hydroxyls in transitional aluminas, but probably by the aluminum–oxygen bonds in boehmite. more...

The effect of La2O3on the catalytic properties of PtSn/Al2O3reforming catalysts has been investigated. On catalysts with low La2O3content (1 wt%) FTIR CO adsorption spectra show two absorption bands at 2070 and 2122 cm−1. At higher La2O3content (20 wt%) the band at 2070 cm−1diminishes progressively until it completely disappears, while the band at 2122 cm−1increases and shifts to 2130 cm−1. This band is assigned to CO adsorbed on oxidized Pt. This effect is observed on samples on which PtSn–La2O3multiphase coexists. The presence of Pt in an oxidized state is supported by XPS since Pt2+is present on the catalysts containing Pt/Sn and La2O3. On the other hand, XPS revealed the presence of Sn2+and Sn°. For the n-heptane reaction the selectivity pattern of the PtSn/Al2O3–La catalysts shows total inhibition of the formation of benzene, high olefin content, and low n-C7dehydrocyclization products. more...

The synthesis of monometallic hydrotalcite-like compounds (MHLC) type Co(II)–Co(III) materials was achieved by precipitation of a solution of cobalt nitrate(II) followed by microwave irradiation during the hydrothermal treatment step. The effects of irradiation time, precipitant agent and atmosphere were studied in order to establish the preparation conditions and the stability of these materials. As expected, these materials required careful preparation conditions, mainly a very slow addition of the precursors. NH4OH had to be used as precipitant agent in an air atmosphere. Short microwave irradiation times during the hydrothermal treatment provided a better crystallization of MHLC. The low stability of these compounds (∼200°C) was explained by the presence of several Co-complexes between the layers of the laminar structure. X-ray diffraction (XRD), Fourier transform infrared spectroscopy (FTIR), differential thermal analysis and thermogravimetric analysis (DTA/TGA), and thermoprogrammed oxidation (TPO) were used as characterization techniques. more...