Carbon Aerogel-Supported Nickel and Iron for Gasification Gas Cleaning. Part I: Ammonia Adsorption

Biomass gasification is a promising way to obtain green energy, but the gas composition makes it unsuitable for use in traditional technologies (i.e., IC engine). Gas purification over nickel and/or iron catalysts is an attractive alternative. Cellulose-based carbon aerogels (CAGs) have shown suitable physical chemical properties for use as catalyst supports. In this work, nickel and iron catalysts are supported on CAG made from cellulose microfibers. Microfibers were impregnated with (NH4)(2)SO4 to increase the mass yield. Carbonization was evaluated at different heating rates, maximum temperatures, and dwell times to generate CAGs. Resulting chars were characterized by N-2 adsorption, X-ray diffraction (XRD), and Raman spectroscopy. The CAG with better properties (specific surface, pore size, thermal resistance) was impregnated with the metal precursor salt via incipient wetness and treated with H-2. Catalysts were characterized by transmission electron microscopy (TEM), XRD, N-2 adsorption, and inductively coupled plasma optical emission spectrometry (ICP-OES). Ammonia adsorption was studied over CAG and catalysts to estimate the thermodynamic parameters. The impregnation with ((NH4)(2)SO4 improves thermal resistance of the char obtained from carbonization. The catalysts exhibit higher adsorption capacity than CAG (without metal), indicating chemical interaction between ammonia and metals. The metal-ammonia interaction is stronger on Fe than on Ni catalyst, which is consistent with reported theoretical calculations

Melanocortin receptor accessory proteins in adrenal disease and obesity.

Melanocortin receptor accessory proteins (MRAPs) are regulators of the melanocortin receptor family. MRAP is an essential accessory factor for the functional expression of the MC2R/ACTH receptor. The importance of MRAP in adrenal gland physiology is demonstrated by the clinical condition familial glucocorticoid deficiency type 2. The role of its paralog melanocortin-2-receptor accessory protein 2 (MRAP2), which is predominantly expressed in the hypothalamus including the paraventricular nucleus, has recently been linked to mammalian obesity. Whole body deletion and targeted brain specific deletion of the Mrap2 gene result in severe obesity in mice. Interestingly, Mrap2 complete knockout (KO) mice have increased body weight without detectable changes to food intake or energy expenditure. Rare heterozygous variants of MRAP2 have been found in humans with severe, early-onset obesity. In vitro data have shown that Mrap2 interaction with the melanocortin-4-receptor (Mc4r) affects receptor signaling. However, the mechanism by which Mrap2 regulates body weight in vivo is not fully understood and differences between the phenotypes of Mrap2 and Mc4r KO mice may point toward Mc4r independent mechanisms

Replication Exercise for "Does basic energy access generate socioeconomic benefits? A field experiment with off-grid solar power in India"

Replication exercise using data from https://dataverse.harvard.edu/dataset.xhtml?persistentId=doi:10.7910/DVN/QXKPH

Carbon Aerogel-Supported Nickel and Iron for Gasification Gas Cleaning. Part I: Ammonia Adsorption

Biomass gasification is a promising way to obtain “green energy”, but the gas composition makes it unsuitable for use in traditional technologies (i.e., IC engine). Gas purification over nickel and/or iron catalysts is an attractive alternative. Cellulose-based carbon aerogels (CAGs) have shown suitable physical chemical properties for use as catalyst supports. In this work, nickel and iron catalysts are supported on CAG made from cellulose microfibers. Microfibers were impregnated with (NH4)2SO4 to increase the mass yield. Carbonization was evaluated at different heating rates, maximum temperatures, and dwell times to generate CAGs. Resulting chars were characterized by N2 adsorption, X-ray diffraction (XRD), and Raman spectroscopy. The CAG with better properties (specific surface, pore size, thermal resistance) was impregnated with the metal precursor salt via incipient wetness and treated with H2. Catalysts were characterized by transmission electron microscopy (TEM), XRD, N2 adsorption, and inductively coupled plasma optical emission spectrometry (ICP-OES). Ammonia adsorption was studied over CAG and catalysts to estimate the thermodynamic parameters. The impregnation with ((NH4)2SO4 improves thermal resistance of the char obtained from carbonization. The catalysts exhibit higher adsorption capacity than CAG (without metal), indicating chemical interaction between ammonia and metals. The metal-ammonia interaction is stronger on Fe than on Ni catalyst, which is consistent with reported theoretical calculations

Chemical Reactivity Probes for Assessing Abiotic Natural Attenuation by Reducing Iron Minerals

Increasing recognition that abiotic natural attenuation (NA) of chlorinated solvents can be important has created demand for improved methods to characterize the redox properties of the aquifer materials that are responsible for abiotic NA. This study explores one promising approach: using chemical reactivity probes (CRPs) to characterize the thermodynamic and kinetic aspects of contaminant reduction by reducing iron minerals. Assays of thermodynamic CRPs were developed to determine the reduction potentials (<i>E</i>_CRP) of suspended minerals by spectrophotometric determination of equilibrium CRP speciation and calculations using the Nernst equation. <i>E</i>_CRP varied as expected with mineral type, mineral loading, and Fe­(II) concentration. Comparison of <i>E</i>_CRP with reduction potentials measured potentiometrically using a Pt electrode (<i>E</i>_Pt) showed that <i>E</i>_CRP was 100–150 mV more negative than <i>E</i>_Pt. When <i>E</i>_Pt was measured with small additions of CRPs, the systematic difference between <i>E</i>_Pt and <i>E</i>_CRP was eliminated, suggesting that these CRPs are effective mediators of electron transfer between mineral and electrode surfaces. Model contaminants (4-chloronitrobenzene, 2-chloroacetophenone, and carbon tetrachloride) were used as kinetic CRPs. The reduction rate constants of kinetic CRPs correlated well with the <i>E</i>_CRP for mineral suspensions. Using the rate constants compiled from literature for contaminants and relative mineral reduction potentials based on <i>E</i>_CRP measurements, qualitatively consistent trends were obtained, suggesting that CRP-based assays may be useful for estimating abiotic NA rates of contaminants in groundwater

[Fe-Fe] hydrogenase models: Iron(I)-carbonyl clusters coupled to alpha- and para-toluenethiolate ligands

Two linkage isomers composing of diironhexacarbonyl clusters coupled to α and p-toluenethiolate ligands have been usefully prepared in moderate yields. The composition of both compounds, [(μ2-(p-toluenethiolato))2Fe2(CO)6] (1) and [(μ2-(α-toluenethiolato))2Fe2(CO)6] (2), have been determined by elemental analysis and NMR spectroscopy. A tetrairondodecacarbonyl complex, [μ4-S(μ2-(α-toluenethiolato)Fe2(CO)6)2] (3), was isolated from the reaction mixture of 2. The molecular structures of 2 and 3 determined by X-ray diffraction are discussed. An exploration of the influence of the α- and p-toluenethiolate ligands on the electronic and electrochemical properties of the iron-carbonyl units have been accomplished using infrared spectroscopy, UV-Vis spectroscopy and cyclic voltammetry. In the presence of acetic acid, compounds 1, 2 and 3 catalyze the electrochemical generation of molecular hydrogen. The proton reduction overpotentials for compounds 1 and 2 were determined to be 0.76 V and 0.85 V versus Fc/Fc+ respectively in acetonitrile as solvent. Comparatively, compound 1 produces hydrogen at an overpotential 90 mV lower than compound 2

Publisher Correction: Global site-specific neddylation profiling reveals that NEDDylated cofilin regulates actin dynamics (Nature Structural &amp; Molecular Biology, (2020), 27, 2, (210-220), 10.1038/s41594-019-0370-3).

In the version of this article initially published online, in Fig. 6d, the third and fourth bars were incorrectly labeled “DMSO + cytochrome D” and “MLN4924 + cytochrome D,” respectively. They should have been labeled “DMSO + cytochalasin D” and “MLN4924 + cytochalasin D,” respectively. The errors have been corrected in the print, PDF and HTML versions of the article

Global site-specific neddylation profiling reveals that NEDDylated cofilin regulates actin dynamics

Neddylation is the post-translational protein modification most closely related to ubiquitination. Whereas the ubiquitin-like protein NEDD8 is well studied for its role in activating cullin−RING E3 ubiquitin ligases, little is known about other substrates. We developed serial NEDD8-ubiquitin substrate profiling (sNUSP), a method that employs NEDD8 R74K knock-in HEK293 cells, allowing discrimination of endogenous NEDD8- and ubiquitin-modification sites by MS after Lys-C digestion and K-εGG-peptide enrichment. Using sNUSP, we identified 607 neddylation sites dynamically regulated by the neddylation inhibitor MLN4924 and the de-neddylating enzyme NEDP1, implying that many non-cullin proteins are neddylated. Among the candidates, we characterized lysine 112 of the actin regulator cofilin as a novel neddylation event. Global inhibition of neddylation in developing neurons leads to cytoskeletal defects, altered actin dynamics and neurite growth impairments, whereas site-specific neddylation of cofilin at K112 regulates neurite outgrowth, suggesting that cofilin neddylation contributes to the regulation of neuronal actin organization