Role of Glomerular Proteoglycans in IgA Nephropathy

Mesangial matrix expansion is a prominent feature of the most common form of glomerulonephritis, IgA nephropathy (IgAN). To find molecular markers and improve the understanding of the disease, the gene and protein expression of proteoglycans were investigated in biopsies from IgAN patients and correlated to clinical and morphological data. We collected and microdissected renal biopsies from IgAN patients (n = 19) and from healthy kidney donors (n = 14). Patients were followed for an average time of 4 years and blood pressure was according to target guidelines. Distinct patterns of gene expression were seen in glomerular and tubulo-interstitial cells. Three of the proteoglycans investigated were found to be of special interest and upregulated in glomeruli: perlecan, decorin and biglycan. Perlecan gene expression negatively correlated to albumin excretion and progress of the disease. Abundant decorin protein expression was found in sclerotic glomeruli, but not in unaffected glomeruli from IgAN patients or in controls. Transforming growth factor beta (TGF-β), known to interact with perlecan, decorin and biglycan, were upregulated both on gene and protein level in the glomeruli. This study provides further insight into the molecular mechanisms involved in mesangial matrix expansion in IgAN. We conclude that perlecan is a possible prognostic marker for patients with IgAN. In addition, the up-regulation of biglycan and decorin, as well as TGF-β itself, indicate that regulation of TGF-β, and other profibrotic markers plays a role in IgAN pathology

Aspects of reducing agent and role of amine species in the reduction of NO over H-ZSM-5 in oxygen excess

In this study the selective catalytic reduction (SCR) of NO has been investigated over H-ZSM-5 with three different reducing agents. Comparison of the reaction mechanisms using propane, ammonia and isopropylamine has been performed using in situ DRIFTS step-response experiments. The same type of surface NH species, likely organic amines, is formed in the presence of either propane or isopropylamine as reducing agent. For NH3, on the other hand, NH4+ is the dominating NH surface species during reaction. Furthermore, in the case of propane, the nature of the NOx-source, i.e. NO or NO2, is crucial for the reaction. With NO2. the reaction likely proceeds fast via direct reduction, while for NO, oxidation to NO2 is required initially. in either case NH species play a vital role in the SCR reaction and organic amines are possible key-intermediates in the SCR with saturated hydrocarbons over H-ZSM-5

Diffuse Reflectance Infrared Fourier Transform Study of NOx Adsorption on CGO10 Impregnated with K2O or BaO

In the present work diffuse reflectance infrared Fourier transform (DRIFT) spectroscopy is applied to study the adsorption of NOx at 300-500 degrees C in different atmospheres on gadolinium-doped ceria (CGO), an important material in electrodes investigated for electrochemical NO removal. Furthermore, the effect on the NOx adsorption when adding K2O or BaO to the CGO is investigated. The DRIFT study shows mainly the presence of nitrate species at 500 degrees C, whereas at lower temperature a diversity of adsorbed NO species exists on the CGO. The presence of O-2 is shown to have a strong effect on the adsorption of NO, but no effect on the adsorption of NO2. Addition of K2O and BaO dramatically affects the NOx adsorption and the results also show that the adsorbed NOx species are mobile and capable of changing adsorption state in the investigated temperature range

Selective catalytic reduction of NOx with methanol over supported silver catalysts

Methanol is a potential renewable fuel for the transport sector and is thus interesting to study as reducing agent for NOx in hydrocarbon assisted selective catalytic reduction (HC SCR). The effect of catalyst composition on the lean NOx reduction during methanol SCR conditions was investigated. In particular silver supported on alumina and ZSM-5 were in focus and parameters that can improve the NOx reduction performance, i.e. the C/N molar ratio and the addition of hydrogen, were specifically studied. Five catalysts were prepared (H ZSM 5, Ag/H ZSM 5, Pd/Ag/H ZSM-5, γ-Al2O3 and Ag-Al2O3) and compared in flow reactor experiments. The Ag-Al2O3 (2 wt% Ag, sol-gel) sample was found to give higher NOx reduction compared to the other tested samples, where important factors are suggested to be the support material, the preparation method and the Ag loading. The NOx reduction over Ag Al2O3 with methanol is proposed to proceed by adsorbed nitrates or nitrites (or gas phase NO2) reacting with adsorbed acetate or formaldehyde like species forming adsorbed R NO2 or R ONO, with subsequent conversion into NCO, -CN, R-NH2 or NH3, with final desorption of N2 and COx (or HCHO). The addition of hydrogen and an increase of the supplied methanol concentration resulted in an increased NOx reduction mainly over the Ag-Al2O3 sample, where the addition of hydrogen also extended the active temperature interval towards lower temperatures. Another effect of the addition of hydrogen was formation of more oxidized carbon containing reaction products. The Ag-Al2O3 catalyst prepared by the sol-gel method, including freeze-drying of the formed gel, is concluded to be the most promising candidate of the tested catalysts for methanol-SCR

Characterization of the active species in the silver/alumina system for lean NOx reduction with methanol

Low-temperature activity and selectivity for lean NOx reduction over silver/alumina is strongly dependent on the composition of surface silver species. This motivates the present investigation of the role of the supported silver species for the lean NOx reduction with methanol. The catalyst samples, with different composition of silver species, are characterized by temperature programmed desorption of ammonia (NH3-TPD), temperature programmed reduction with hydrogen (H-2-TPR) and temperature programmed desorption with NO (NO-TPD) in oxygen excess. The small differences in acidity do not significantly influence the lean NOx reduction with methanol. However, comparison of results from H-2-TPR experiments with previous characterization by UV-vis spectroscopy shows that fairly small silver species are reduced by hydrogen, possibly small silver clusters. These small silver species are likely, in addition to others, involved in the lean NOx reduction reactions. NO-TPD experiments, in the presence of oxygen and hydrogen, reveal a shift in temperature for one of the desorption peaks from the different samples. This peak is likely related to the shift in temperature for NOx reduction during methanol-SCR conditions for the compared samples. (C) 2016 Elsevier B.V. All rights reserved

High-resolution core-level spectroscopy study of the ultrathin aluminum oxide film on NiAl(110)

We have studied the ultrathin aluminum oxide film on NiAl(110) by a combination of high-resolution core-level spectroscopy and density functional theory calculations. Energy-dependent core-level data from the O 1s and Al 2p levels allows for a distinction between oxygen and aluminum atoms residing at the surface or inside the aluminum oxide film. A comparison to calculated core-level binding energies from the recent model by Kresse et al. [Science 308, 1440 (2005)] reveals good agreement with experiment, and the complex spectroscopic signature of the thin Al oxide on NiAl(110) can be explained. Our assignment of a shifted component in the O 1s spectra to oxygen atoms at the surface with a particular Al and oxygen coordination may have implications for the interpretation of photoelectron-diffraction experiments from similar ultrathin aluminum oxide films