Effects of Cycling Conditions of Active Material From Discharged Ni Positive Plates Studied by Inelastic Neutron Scattering Spectroscopy

The objectives of this presentation are: identify atomic-level signatures of electrochemical activity of the active material on the Ni positive plates of Ni-H2 batteries, relate finding to cycling conditions and histories, and develop INS spectroscopy as a non-destructive testing technique for the evaluation of Ni-positive plates of Ni-H2 batteries

Nanostructured carbide catalysts for the hydrogen economy

The above quote, taken from the executive summary of the Report from the US DOE Basic Energy Sciences Workshop held August 6–8, 2007,[1] places in context the research carried out at the University of California, Santa Barbara, which is reported in this document. The enormous impact of heterogeneous catalysis is exemplified by the Haber process for the synthesis of ammonia, which consumes a few % of the world’s energy supply and natural gas, and feeds as many as a third of the world’s population. While there have been numerous advances in understanding the process,[2] culminating in the awarding of the Nobel Prize to Gerhard Ertl in 2007, it is interesting to note that the catalysts themselves have changed very little since they were discovered heuristically in the the early part of the 20th century. The thesis of this report is that modern materials chemistry, with all the empirical knowledge of solid state chemistry, combined with cutting edge structural tools, can help develop and better heterogeneous catalysis. The first part of this report describes research in the area of early transition metal carbides (notably of Mo and W), potentially useful catalysts for water gas shift (WGS) and related reactions of use to the hydrogen economy. Although these carbides have been known to be catalytically useful since the 1970s,[3] further use of these relatively inexpensive materials have been plagued by issues of low surface areas and ill-defined, and often unreactive surfaces, in conjunction with deactivation. We have employed for the first time, a combination of constant-wavelength and time-of-flight neutron scattering, including a total scattering analysis of the latter data, to better understand what happens in these materials, in a manner that for the first time, reveals surface graphitic carbon in these materials in a quantitative manner. Problems of preparation, surface stability, and irreversible reactivity have become manifest in this class of materials that discourage us from pursuing these materials further

Vibrational dynamics of crystalline L-alanine

The authors report a new, complete vibrational analysis of L-alanine and L-alanine-d{sub 4} which utilizes IINS intensities in addition to frequency information. The use of both isotopomers resulted in a self-consistent force field for and assignment of the molecular vibrations in L-alanine. Some details of the calculation as well as a comparison of calculated and observed IINS spectra are presented. The study clarifies a number of important issues on the vibrational dynamics of this molecule and presents a self-consistent force field for the molecular vibrations in crystalline L-alanine

Multiparametric immune profiling in HPV- oral squamous cell cancer.

Evaluation of T lymphocyte frequency provides prognostic information for patients with oral squamous cell cancer (OSCC). However, the effect of simultaneously evaluating T cell frequency and assessing suppressive elements and defects in antigen-processing machinery (APM) has not been clarified. Simultaneous characterization of CD3+, CD8+, FoxP3+, CD163+, and PD-L1+ cells using multispectral imaging was performed on sections from 119 patients with HPV- OSCC. Expression of β2-microglobulin, MHC class I heavy chain, and large multifunctional peptidase 10 was quantified, and all data were correlated with patient outcome. We found that, consistent with previous reports, high numbers of CD8+ T cells at the invasive margin correlated significantly with prolonged overall survival (OS), while the number of FoxP3+ or PD-L1+ cells did not. Compiling the number of FoxP3+ or PD-L1+ cells within 30 μm of CD8+ T cells identified a significant association with a high number of suppressive elements close to CD8+ T cells and reduced OS. Integrating this information into a cumulative suppression index (CSI) increased correlation with OS. Incorporating tumor expression levels of APM components with CSI further improved prognostic power. This multiparametric immune profiling may be useful for stratifying patients with OSCC for clinical trials

Investigating an Airborne Tularemia Outbreak, Germany

Infectious aerosols can contribute to the transmission of tularemia during processing of dead hares

From inelastic neutron scattering to structural information. A two-dimensional parametrized model to study metal-(H₂) interaction

International audienceA two-dimensional dynamical parametrized model is derived to study the M-(H-2) interaction in transition-metal molecular hydrogen complexes. The parameters have been adjusted to reproduce the observed inelastic neutron scattering transitions through a least-squares fit procedure. The vibrational levels are obtained by solving the nuclear Schrodinger equation in a discrete variable representation. From this procedure, structural information such as the barrier to rotation of the Hz ligand and the H-H distance have been obtained. The accuracy of the model is tested on four systems with M-(H2) interactions of different nature. The resulting H-H bond distances are in very good agreement with neutron diffraction structures where available

Hydrogen Storage Materials with Binding Intermediate between Physisorption and Chemisorption: Final Report

Hydrogen storage systems based on the readily reversible adsorption of H{sub 2} in porous materials have a number of very attractive properties with the potential to provide superior performance among candidate materials currently being investigated were it not for the fact that the interaction of H{sub 2} with the host material is too weak to permit viable operation at room temperature. Our study has delineated in quantitative detail the structural elements which we believe to be the essential ingredients for the future synthesis of porous materials, where guest-host interactions are intermediate between those found in the carbons and the metal hydrides, i.e. between physisorption and chemisorption, which will result in H{sub 2} binding energies required for room temperature operation. The ability to produce porous materials with much improved hydrogen binding energies depends critically on detailed molecular level analysis of hydrogen binding in such materials. However, characterization of H{sub 2} sorption is almost exclusively carried by thermodynamic measurements, which give average properties for all the sites occupied by H{sub 2} molecules at a particular loading. We have therefore extensively utilized the most powerful of the few molecular level experimental probes available to probe the interactions of hydrogen with porous materials, namely inelastic neutron scattering (INS) spectroscopy of the hindered rotations of the hydrogen molecules adsorbed at various sites, which in turn can be interpreted in a very direct way in by computational studies. This technique can relate spectral signatures of various H{sub 2} molecules adsorbed at binding sites with different degrees of interaction. In the course of this project we have synthesized a rather large number of entirely new hybrid materials, which include structural modifications for improved interactions with adsorbed hydrogen. The results of our systematic studies on many porous materials provide detailed information on the effects on hydrogen binding from framework modifications, including charged frameworks and extraframework cations, from reduction in pore sizes, functionalization of the organic linking group, and most importantly, that of the various types of metal sites. We provided a clear demonstration that metal sites are most effective if the metal is highly undercoordinated, open and completely accessible to the H{sub 2} molecule, a condition which is not currently met in MOFs with intra-framework metals. The results obtained from this project therefore will give detailed direction to efforts in the synthesis of new materials that can reach the goal of a practical sorption based hydrogen storage material