Synthesis and characterization of p-n junction ternary mixed oxides for photocatalytic coprocessing of CO2 and H2O

In the present paper, we report the synthesis and characterization of both binary (Cu2 O, Fe2 O3, and In2 O3 ) and ternary (Cu2 O-Fe2 O3 and Cu2 O-In2 O3 ) transition metal mixed-oxides that may find application as photocatalysts for solar driven CO2 conversion into energy rich species. Two different preparation techniques (High Energy Milling (HEM) and Co-Precipitation (CP)) are compared and materials properties are studied by means of a variety of characterization and analytical techniques UV-Visible Diffuse Reflectance Spectroscopy (UV-VIS DRS), X-ray Photoelectron Spectroscopy (XPS), X-Ray Diffraction (XRD), Transmission Electron Microscopy (TEM), and Energy Dispersive X-Ray spectrometry (EDX). Appropriate data elaboration methods are used to extract materials bandgap for Cu2 O@Fe2 O3 and Cu2 O@In2 O3 prepared by HEM and CP, and foresee whether the newly prepared semiconductor mixed oxides pairs are useful for application in CO2-H2 O coprocessing. The experimental results show that the synthetic technique influences the photoactivity of the materials that can correctly be foreseen on the basis of bandgap experimentally derived. Of the mixed oxides prepared and described in this work, only Cu2 O@In2 O3 shows positive results in CO2-H2 O photo-co-processing. Preliminary results show that the composition and synthetic methodologies of mixed-oxides, the reactor geometry, the way of dispersing the photocatalyst sample, play a key role in the light driven reaction of CO2 –H2 O. This work is a rare case of full characterization of photo-materials, using UV-Visible DRS, XPS, XRD, TEM, EDX for the surface and bulk analytical characterization. Surface composition may not be the same of the bulk composition and plays a key role in photocatalysts behavior. We show that a full material knowledge is necessary for the correct forecast of their photocatalytic behavior, inferred from experimentally determined bandgaps

Opto‐Electronic Characterization of Photocatalysts Based on p,n‐Junction Ternary and Quaternary Mixed Oxides Semiconductors (Cu2O‐In2O3 and Cu2O‐In2O3‐TiO2)

Semiconductor materials are the basis of electronic devices employed in the communication and media industry. In the present work, we report the synthesis and characterization of mixed metal oxides (MOs) as p,n‐junction photocatalysts, and demonstrate the correlation between the preparation technique and the properties of the materials. Solid‐state UV-visible diffuse reflectance spectroscopy (UV‐VIS DRS) allowed for the determination of the light absorption properties and the optical energy gap. X‐ray photoelectron spectroscopy (XPS) allowed for the determination of the surface speciation and composition and for the determination of the valence band edge. The opto‐electronic behavior was evaluated measuring the photocurrent generated after absorption of chopped visible light in a 3‐electrode cell. Scanning electron microscopy (SEM) measurements allowed for auxiliary characterization of size and morphology, showing the formation of composites for the ternary Cu2O‐In2O3 p,n‐mixed oxide, and even more for the quaternary Cu2O‐In2O3‐TiO2 MO. Light absorption spectra and photocurrent‐time curves mainly depend upon the composition of MOs, while the optical energy gap and defective absorption tail are closely related to the preparation methodology, time and thermal treatment. Qualitative electronic band structures of semiconductors are also presented

NO/H2S "crosstalk" Reactions. The Role of Thionitrites (SNO-) and Perthionitrites (SSNO-)

The redox chemistry of H2S with NO and other oxidants containing the NO group is discussed on a mechanistic basis because of the expanding interest in their biological relevance, with an eye open to the chemical differences of H2S and thiols RSH. We focus on the properties of two "crosstalk" intermediates, SNO- (thionitrite) and SSNO- (perthionitrite, nitrosodisulfide) based in the largely controversial status on their identity and chemistry in aqueous/nonaqueous media, en route to the final products N2O, NO2 -, NH2OH/NH3, and S8. Thionitrous acid, generated either in the direct reaction of NO + H2S or through the transnitrosation of RSNO's (nitrosothiols) with H2S at pH 7.4, is best described as a mixture of rapidly interconverting isomers, {(H)SNO}. It is reactive in different competitive modes, with a half-life of a few seconds at pH 7.4 for homolytic cleavage of the N-S bond, and could be deprotonated at pH values of up to ca. 10, giving SNO-, a less reactive species than {(H)SNO}. The latter mixture can also react with HS-, giving HNO and HS2 - (hydrogen disulfide), a S0(sulfane)-transfer reagent toward {(H)SNO}, leading to SSNO-, a moderately stable species that slowly decomposes in aqueous sulfide-containing solutions in the minute-hour time scale, depending on [O2]. The previous characterization of HSNO/SNO- and SSNO- is critically discussed based on the available chemical and spectroscopic evidence (mass spectrometry, UV-vis, 15N NMR, Fourier transform infrared), together with computational studies including quantum mechanics/molecular mechanics molecular dynamics simulations that provide a structural and UV-vis description of the solvatochromic properties of cis-SSNO- acting as an electron donor in water, alcohols, and aprotic acceptor solvents. In this way, SSNO- is confirmed as the elusive "yellow intermediate" (I412) emerging in the aqueous crosstalk reactions, in contrast with its assignment to polysulfides, HSn -. The analysis extends to the coordination abilities of {(H)SNO}, SNO-, and SSNO- into heme and nonheme iron centers, providing a basis for best unraveling their putative specific signaling roles.Fil: Marcolongo, Juan Pablo. Consejo Nacional de Investigaciones Científicas y Técnicas. Oficina de Coordinación Administrativa Ciudad Universitaria. Instituto de Química, Física de los Materiales, Medioambiente y Energía. Universidad de Buenos Aires. Facultad de Ciencias Exactas y Naturales. Instituto de Química, Física de los Materiales, Medioambiente y Energía; ArgentinaFil: Venâncio, Mateus F.. Universidade Federal de Minas Gerais; BrasilFil: Rocha, Willian R.. Universidade Federal de Minas Gerais; BrasilFil: Doctorovich, Fabio. Consejo Nacional de Investigaciones Científicas y Técnicas. Oficina de Coordinación Administrativa Ciudad Universitaria. Instituto de Química, Física de los Materiales, Medioambiente y Energía. Universidad de Buenos Aires. Facultad de Ciencias Exactas y Naturales. Instituto de Química, Física de los Materiales, Medioambiente y Energía; ArgentinaFil: Olabe Iparraguirre, Jose Antonio. Consejo Nacional de Investigaciones Científicas y Técnicas. Oficina de Coordinación Administrativa Ciudad Universitaria. Instituto de Química, Física de los Materiales, Medioambiente y Energía. Universidad de Buenos Aires. Facultad de Ciencias Exactas y Naturales. Instituto de Química, Física de los Materiales, Medioambiente y Energía; Argentin

Anabolic effects and inhibition of interleukin 6 production induced by neridronate on human osteoblasts

Bisphosphonates (BPs) are pharmacological compounds widely used in the treatment of a variety of bone-related diseases, particularly where the bone-turnover is skewed in favour of osteolysis. The mechanisms by which BPs reduce bone-resorption directly acting on osteoclasts (OCs) are now largely clarified even at molecular level. The researches concerning the BPs effects on osteoblasts (OBs) have instead shown variable results. Objectives: We have investigated the efficacy of neridronate (NER), an amino-BP, as anabolic agent on human OBs. Moreover, we have tried to verify if NER is able to negatively modulate the production of IL-6 on OBs stimulated or not by the pro-inflammatory cytokine Il-1b. Methods: We have tested if different concentrations of NER (from 10-11M to 10-3M), added to primary human OB cultures, could affect the cells number, the endogenous cellular alkaline phosphatase (ALP) activity, the collagen I (COLI) synthesis, the formation of mineralized nodules and the IL-6 production. Our experimental approach was performed testing a wide range of NER concentrations because, under physiological conditions, OBs seems to be exposed to variable and transient levels of the drug. Results: Our results show that NER doesn't negatively affect in vitro the viability, proliferation and cellular activity of human OBs, even after 20 days of exposure to concentrations ²10-5 M (therapeutic dose). In addition, NER seems to enhance the differentiation of cultured OBs in mature bone-forming cells. A maximum increase of COL-I synthesis (+25% after 4 days; p<0.05), ALP activity (+50% after 10 days; p<0.01) and mineralized nodules (+48% after 20 days; p<0.05) was observed in cultures treated with NER 10-8M. A maximal reduction of IL-6 secretion (-24% on IL-1b stimulated cultures and -29% on unstimulated cultures) was observed for NER 10-9 M. Conclusions: These results encourage the use of neridronate in therapy of demineralizing metabolic bone disorders

A novel β-xylosidase from Anoxybacillus sp. 3M towards an improved agro-industrial residues saccharification

ABSTRACT: An intracellular β-xylosidase (AbXyl), fromthe thermoalkaline Anoxybacillus sp. 3M,was purified and characterized. The homodimeric enzyme (140 kDa) was optimally active at 65 °C and pH 5.5, exhibited half life of 10 h at 60 °C, 78 and 88% residual activity after 24 h, at pH 4.5 and 8.0, respectively. Fe2+, Cu2+, Al3+, Ag+ and Hg2+inhibited the enzyme; the activity was moderately stimulated by SDS and not influenced by β-mercaptoethanol. In the presence of p-nitrophenyl-β-D-xylopyranoside, AbXyl exhibited Km of 0.19 mM, Kcat of 453.29 s−1, KcatKm−1 of 2322 s−1mMandwas moderately influenced by xylose (Ki 21.25mM). The enzyme hydrolyzed xylo-oligomers into xylose and catalyzed transxylosilation reactions also in presence of alcohols as acceptors, producing xylo-oligosaccharides and alkyl-xylosides. Finally AbXyl was applied towards a statistically optimized process of brewery's spent grain bioconversion, highlighting the important role of this biocatalyst in reaching high yields of fermentable sugars.info:eu-repo/semantics/publishedVersio

Conformational change of the catalytic subunit of glucose-6-phosphatase in rat liver during the fetal-to-neonatal transition

The glucose-6-phosphatase system was investigated in fetal rat liver microsomal vesicles. Several observations indicate that the orientation of the catalytic subunit is different in the fetal liver in comparison with the adult form: (i) the phosphohydrolase activity was not latent using glucose- 6-phosphate as substrate, and in the case of other phosphoesters it was less latent; (ii) the intravesicular accumulation of glucose upon glucose-6- phosphate hydrolysis was lower; (iii) the size of the intravesicular glucose- 6-phosphate pool was independent of the glucose-6-phosphatase activities; (iv) antibody against the loop containing the proposed catalytic site of the enzyme inhibited the phosphohydrolase activity in fetal but not in adult rat liver microsomes. Glucose-6-phosphate, phosphate, and glucose uptake could be detected by both light scattering and/or rapid filtration method in fetal liver microsomes; however, the intravesicular glucose-6-phosphate and glucose accessible spaces were proportionally smaller than in adult rat liver microsomes. These data demonstrate that the components of the glucose-6- phosphatase system are already present, although to a lower extent, in fetal liver, but they are functionally uncoupled by the extravesicular orientation of the catalytic subunit

Lissencephaly-pachygyria and cerebellar hypoplasia in a calf.

ABSTRACT: A case of lissencephaly-pachygyria and cerebellar hypoplasia diagnosed in a Charolais x Tabapuã calf is described. The calf presented since birth, clinical signs characterized by apathy, prolonged recumbency, tremors of the head and neck, ataxia, hypermetria, difficulty walking, blindness and swelling of the joints of the four limbs. Due to the unfavorable prognosis, the animal was euthanized and necropsied at 34 days of age. At necropsy, a rudimentary development of the brain folds (gyri) and grooves (sulci) was observed, and the cerebellum was hypoplastic. The cut surface of the brain exhibited thickening of the gray matter (pachygyria) in the frontal, parietal, temporal and occipital cortices and narrowing of the white matter. In the organs of the thoracic and abdominal cavities, no significant lesions were observed. Histologically, cerebral cortex was thick and exhibited neuronal disorganization of the gray matter. The cerebellum had a thin molecular layer, and neuronal disorganization with ectopia of the Purkinje neurons in the region of the granular and molecular layers. There were no bacterial growths in cultures of joint swabs. This was the only case on the property, which suggests that this malformation, which has not previously been described in cattle, was a sporadic case, and it was not possible to determine its cause. Neurological lesions and clinical sings presented here should be considered in the differential diagnosis of congenital diseases of the central nervous systems of cattle

Maxwell equations in matrix form, squaring procedure, separating the variables, and structure of electromagnetic solutions

The Riemann -- Silberstein -- Majorana -- Oppenheimer approach to the Maxwell electrodynamics in vacuum is investigated within the matrix formalism. The matrix form of electrodynamics includes three real 4 \times 4 matrices. Within the squaring procedure we construct four formal solutions of the Maxwell equations on the base of scalar Klein -- Fock -- Gordon solutions. The problem of separating physical electromagnetic waves in the linear space \lambda_{0}\Psi^{0}+\lambda_{1}\Psi^{1}+\lambda_{2}\Psi^{2}+ lambda_{3}\Psi^{3} is investigated, several particular cases, plane waves and cylindrical waves, are considered in detail.Comment: 26 pages 16 International Seminar NCPC, May 19-22, 2009, Minsk, Belaru

The high frequency of spontaneous micronuclei observed in lymphocytes of systemic sclerosis patients: preliminary results.

OBJECTIVE: Aim of the study is to assess the presence of spontaneous chromosome damage in patients affected by limited (lSSc) or diffuse (dSSc) Systemic Slerosis, using the micronucleus (MN) assay.METHODS: We evaluated MN frequency in cultured peripheral lymphocytes of 18 SSc and in a group of 20 healthy controls. Patients were also classified as ACA+, Scl70+, FAN+ according to the presence of the specific anti-nuclear antibodies. We also explored the hypothesis that the extent of cytogenetic alteration might be related to the severity of the pathological condition and/or to the immunological profile.RESULTS: Compared to controls, the patient group as a whole showed significantly higher MN frequencies (10.8+/-4.5 vs. 27.8+/-13.7, p&lt;0.001). No correlation was found between spontaneous chromosome damage and severity of the disease, being MN frequency 33.1+/-17.0 and 19.8+/-2.7 in lSSc and dSSc, respectively. Interestingly, ACA+ subjects displayed the highest MN frequency (36.9+/-15.0), as compared to patients with different antibody pattern (Scl70+, FAN+; 19.7+/-8.2).CONCLUSIONS: Our results confirm the presence of chromosomal damage in circulating lymphocytes of SSc patients and would suggest a key role of antibodies to the centromere in determining the observed cytogenetic anomalies

The high frequency of spontaneous micronuclei observed in lymphocytes of systemic sclerosis patients: preliminary results

Objective: aim of the study is to assess the presence of spontaneous chromosome damage in patients affected by limited (lSSc) or diffuse (dSSc) Systemic Slerosis, using the micronucleus (MN) assay. Methods: we evaluated MN frequency in cultured peripheral lymphocytes of 18 SSc and in a group of 20 healthy controls. Patients were also classified as ACA+, Scl70+, FAN+ according to the presence of the specific anti-nuclear antibodies. We also explored the hypothesis that the extent of cytogenetic alteration might be related to the severity of the pathological condition and/or to the immunological profile. Results: compared to controls, the patient group as a whole showed significantly higher MN frequencies (10.8±4.5 vs. 27.8±13.7, p<0.001). No correlation was found between spontaneous chromosome damage and severity of the disease, being MN frequency 33.1±17.0 and 19.8±2.7 in lSSc and dSSc, respectively. Interestingly, ACA+ subjects displayed the highest MN frequency (36.9±15.0), as compared to patients with different antibody pattern (Scl70+, FAN+; 19.7±8.2). Conclusions: our results confirm the presence of chromosomal damage in circulating lymphocytes of SSc patients and would suggest a key role of antibodies to the centromere in determining the observed cytogenetic anomalies