Tertiary Amides as Directing Groups for Enantioselective C-H Amination using Ion-Paired Rhodium Complexes.

Enantioselective C-H amination at a benzylic methylene is a vital disconnection towards chiral benzylamines. Here we disclose that butyric and valeric acid-derived tertiary amides can undergo highly enantioselective benzylic amination using an achiral anionic Rh complex that is ion-paired with a Cinchona alkaloid-derived chiral cation. A broad scope of compounds can be aminated encompassing numerous arene substitutions, amides, and two different chain lengths. Excellent tolerance of ortho substituents was observed, which has not been achieved before in asymmetric intermolecular C-H amination with Rh. We speculate that the tertiary amide group of the substrate engages in hydrogen bonding interactions directly with the chiral cation, enabling a high level of organisation at the transition state for C-H amination. This is in contrast with our previous work where a substrate bearing a hydrogen bond donor was required. Control experiments led to the discovery that methyl ethers also function as proficient directing groups under the optimised conditions, potentially also acting as hydrogen bond acceptors. This finding has the promise to dramatically expand the applicability of our ion-paired chiral catalysts.

The evolution of hydrated lime-based cementitious waste forms during leach testing leading to enhanced technetium retention.

The interaction between radionuclides and cementitious material phases is crucial in the prediction of the long-term disposal behavior of cementitious waste forms. This work focuses on the behavior of technetium-99 (Tc) within a hydrated-lime based waste form developed as a candidate to immobilize high-sulphate containing liquid wastes known to inhibit cement solidification when using a fly ash based formulation. In leach testing, the hydrated-lime based formulation demonstrated improvement in Tc retention over a fly ash containing formulation beginning after 14 d leaching. The mineralogical evolution of the hydrated-lime samples during leach testing showed a decrease in portlandite content and reduction capacity at the onset of the Tc retention improvement. Leach testing upwards of 400 days showed the improved Tc retention was sustained. Samples cured for different lengths of time (28 days vs 60 days) confirmed that the improved Tc retention and mineralogic change was caused by cement - leachant interactions and not the sample curing time. The Tc observed diffusivities in the hydrated-lime samples are amongst the lowest measured in a cement waste form tested for development at the US Department of Energy Hanford site, leading to a possible pathway to improved cement conditioning where contaminants can be retained for long disposal times.

Enantioselective Intermolecular C-H Amination Directed by a Chiral Cation.

The enantioselective amination of C(sp3)-H bonds is a powerful synthetic transformation yet highly challenging to achieve in an intermolecular sense. We have developed a family of anionic variants of the best-in-class catalyst for Rh-catalyzed C-H amination, Rh2(esp)2, with which we have associated chiral cations derived from quaternized cinchona alkaloids. These ion-paired catalysts enable high levels of enantioselectivity to be achieved in the benzylic C-H amination of substrates bearing pendant hydroxyl groups. Additionally, the quinoline of the chiral cation appears to engage in axial ligation to the rhodium complex, providing improved yields of product versus Rh2(esp)2 and highlighting the dual role that the cation is playing. These results underline the potential of using chiral cations to control enantioselectivity in challenging transition-metal-catalyzed transformations.

Para-Selective C-H Borylation of Common Arene Building Blocks Enabled by Ion-Pairing with a Bulky Countercation.

The selective functionalization of C-H bonds at the arene para position is highly challenging using transition metal catalysis. Iridium-catalyzed borylation has emerged as a leading technique for arene functionalization, but there are only a handful of strategies for para-selective borylation, which operate on specific substrate classes and use bespoke ligands or catalysts. We describe a remarkably general protocol which results in para-selectivity on some of the most common arene building blocks (anilines, benzylamines, phenols, benzyl alcohols) and uses standard borylation ligands. Our strategy hinges upon the facile conversion of the substrates into sulfate or sulfamate salts, wherein the anionic arene component is paired with a tetrabutylammonium cation. We hypothesize that the bulk of this cation disfavors meta-C-H borylation, thereby promoting the challenging para-selective reaction.

Performance of the Fluidized Bed Steam Reforming product under hydraulically unsaturated conditions.

Several candidates for supplemental low-activity waste (LAW) immobilization at the Hanford site in Washington State, USA are being considered. One waste sequestering technology considered is Fluidized Bed Steam Reforming (FBSR). The granular product resulting from the FBSR process is composed primarily of an insoluble sodium aluminosilicate matrix with the dominant phases being feldspathoid minerals with a 1:1:1 molar ratio of Na, Al and Si. To demonstrate the durability of the product, which can be disposed of at the unsaturated Integrated Disposal Facility (IDF) at Hanford, a series of tests has been performed using the Pressurized Unsaturated Flow (PUF) system, which allows for the accelerated weathering of the solid materials. The system maintains hydraulically unsaturated conditions, thus mimicking the open-flow and transport properties that will be present at the IDF. Two materials were tested using the system: 1) the FBSR granular product and 2) the FBSR granular product encapsulated in a geopolymer to form a monolith. Results of the experiments show a trend of relatively constant effluent concentration of Na, Si, Al, and Cs as a function of time from both materials. The elements I and Re show a steady release throughout the yearlong test from the granular material but their concentrations seem to be increasing at one year from the monolith material. This result suggests that these two elements may be present in the sodalite cage structure rather than in the predominant nepheline phase because their release occurs at a different rate compared to nepheline phase. Also, these elements to not seem to reprecipitate when released from the starting material. Calculated one-year release rates for Si are on the order of 10(-6) g/(m(2) d) for the granular material and 10(-5) g/(m(2) d) for the monolith material while Re release is seen to be two orders of magnitude higher than Si release rates. SEM imaging and XRD analysis show how the alteration of the two materials is dependent on their depth in the column. This phenomenom is a result of depth-dependent solution concentrations giving rise chemical environments that may be supersaturated with respect to a number of mineral phases.

C. elegans PAT-9 is a nuclear zinc finger protein critical for the assembly of muscle attachments.

BACKGROUND: Caenorhabditis elegans sarcomeres have been studied extensively utilizing both forward and reverse genetic techniques to provide insight into muscle development and the mechanisms behind muscle contraction. A previous genetic screen investigating early muscle development produced 13 independent mutant genes exhibiting a Pat (paralyzed and arrested elongation at the two-fold length of embryonic development) muscle phenotype. This study reports the identification and characterization of one of those genes, pat-9. RESULTS: Positional cloning, reverse genetics, and plasmid rescue experiments were used to identify the predicted C. elegans gene T27B1.2 (recently named ztf-19) as the pat-9 gene. Analysis of pat-9 showed it is expressed early in development and within body wall muscle lineages, consistent with a role in muscle development and producing a Pat phenotype. However, unlike most of the other known Pat gene family members, which encode structural components of muscle attachment sites, PAT-9 is an exclusively nuclear protein. Analysis of the predicted PAT-9 amino acid sequence identified one putative nuclear localization domain and three C2H2 zinc finger domains. Both immunocytochemistry and PAT-9::GFP fusion expression confirm that PAT-9 is primarily a nuclear protein and chromatin immunoprecipitation (ChIP) experiments showed that PAT-9 is present on certain gene promoters. CONCLUSIONS: We have shown that the T27B1.2 gene is pat-9. Considering the Pat-9 mutant phenotype shows severely disrupted muscle attachment sites despite PAT-9 being a nuclear zinc finger protein and not a structural component of muscle attachment sites, we propose that PAT-9 likely functions in the regulation of gene expression for some necessary structural or regulatory component(s) of the muscle attachment sites.

Uranium phases in contaminated sediments below Hanford's U tank farm.

Macroscopic and spectroscopic investigations (XAFS, XRF, and TRLIF) on Hanford contaminated vadose zone sediments from the U-tank farm showed that U(VI) exists as different surface phases as a function of depth below ground surface (bgs). Secondary precipitates of U(VI) silicate precipitates (boltwoodite and uranophane) were present dominantly in shallow-depth sediments (15-16 m bgs), while adsorbed U(VI) phases and polynuclear U(VI) surface precipitates were considered to dominate in intermediate-depth sediments (20-25 m bgs). Only natural uranium was observed in the deeper sediments (> 28 m bgs) with no signs of contact with tank wastes containing Hanford-derived U(VI). Across all depths, most of the U(VI) was preferentially associated with the silt and clay size fractions of sediments. Strong correlation between U(VI) and Ca was found in the shallow-depth sediments, especially for the precipitated U(VI) silicates. Because U(VI) silicate precipitates dominate in the shallow-depth sediments, the released U(VI) concentration by macroscopic (bi)carbonate leaching resulted from both desorption and dissolution processes. Having different U(VI) surface phases in the Hanford contaminated sediments indicates that the U(VI) release mechanism could be complicated and that detailed characterization of the sediments using several different methods would be needed to estimate U(VI) fate and transport correctly in the vadose zone.

Rapid frequency-domain FLIM spinning disk confocal microscope: lifetime resolution, image improvement and wavelet analysis.

A spinning disk confocal attachment is added to a full-field real-time frequency-domain fluorescence lifetime-resolved imaging microscope (FLIM). This provides confocal 3-D imaging while retaining all the characteristics of the normal 2-D FLIM. The spinning disk arrangement allows us to retain the speed of the normal 2-D full field FLIM while gaining true 3-D resolution. We also introduce the use of wavelet image transformations into the FLIM analysis. Wavelets prove useful for selecting objects according to their morphology, denoising and background subtraction. The performance of the instrument and the analysis routines are tested with quantitative physical samples and examples are presented with complex biological samples.

Gender plays no role in student ability to perform on computer-based examinations.

BACKGROUND: To see if there is a difference in performance when students switch from traditional paper-and-pencil examinations to computer-based examinations, and to determine whether there are gender differences in student performance in these two examination formats. METHODS: This study involved first year medical students at the University of Illinois at Urbana-Champaign over three Academic Years 2002-03/2003-04 and 2003-05. Comparisons of student performance by overall class and gender were made. Specific comparisons within courses that utilized both the paper-and-pencil and computer formats were analyzed. RESULTS: Overall performance scores for students among the various Academic Years revealed no differences between exams given in the traditional pen-and-paper and computer formats. Further, when we looked specifically for gender differences in performance between these two testing formats, we found none. CONCLUSION: The format for examinations in the courses analyzed does not affect student performance. We find no evidence for gender differences in performance on exams on pen-and-paper or computer-based exams.

Sarcomere assembly in C. elegans muscle.

Sarcomeres within body wall muscle in C. elegans include attachments to the sarcolemma that are remarkably similar in structure to vertebrate adhesion complexes. Crucial early steps in muscle sarcomere assembly, a highly orchestrated affair involving many proteins, involve the assembly of these sarcomere attachments. The steps involved in initiating the correct placement of these attachments and other sarcomere substructures are poorly understood. Using mutants in C. elegans we are attempting to dissect the various steps in this process. We review what has been discovered to date and present a model of sarcomere assembly that initiates at the plasma membrane and involves proteins within muscle, the hypodermis and within the extracellular matrix.

C. elegans PAT-6/actopaxin plays a critical role in the assembly of integrin adhesion complexes in vivo.

BACKGROUND: The novel focal adhesion protein actopaxin includes tandem unconventional calponin homology (CH) domains and a less well-conserved N-terminal stretch. Dominant-negative studies have implicated actopaxin in focal adhesion formation. RESULTS: PAT-6/actopaxin, the sole actopaxin homolog in C. elegans, is located in body wall muscle attachments that are in vivo homologs of focal adhesions. We show using pat-6 protein null alleles that PAT-6/actopaxin has critical nonredundant roles during attachment maturation. It is required to recruit UNC-89 and myofilaments to newly forming attachments, and also to reposition the attachments so that they form the highly ordered array of dense body and M line attachments that are characteristic of mature muscle cells. PAT-6/actopaxin is not required for the deposition of UNC-52/perlecan in the basal lamina, nor for the initiation of attachment assembly, including the clustering of integrin into foci and the recruitment of attachment proteins PAT-4/ILK, UNC-112, and DEB-1/vinculin from the cytosol. PAT-6/actopaxin, PAT-4/ILK, and UNC-112 are each required for the same steps during attachment assembly in vivo, consistent with the notion that they work together in multiprotein complex. Supporting this idea, PAT-4/ILK can simultaneously bind to PAT-6/actopaxin and UNC-112, forming a ternary complex, in yeast three-hybrid assays. Finally, we show that both calponin homology domains are required for PAT-6/actopaxin's critical functions during attachment assembly in vivo. CONCLUSIONS: We show directly by loss-of-function genetics that PAT-6/actopaxin plays essential roles during the maturation of integrin-mediated muscle attachments in vivo.

C. elegans PAT-4/ILK functions as an adaptor protein within integrin adhesion complexes.

BACKGROUND: Mammalian integrin-linked kinase (ILK) was identified in a yeast two-hybrid screen for proteins binding the integrin beta(1) subunit cytoplasmic domain. ILK has been implicated in integrin-mediated signaling and is also an adaptor within integrin-associated cytoskeletal complexes. RESULTS: We identified the C. elegans pat-4 gene in previous genetic screens for mutants unable to assemble integrin-mediated muscle cell attachments. Here, we report that pat-4 encodes the sole C. elegans homolog of ILK. In pat-4 null mutants, embryonic muscle cells form integrin foci, but the subsequent recruitment of vinculin and UNC-89 as well as actin and myosin filaments to these in vivo focal adhesion analogs is blocked. Conversely, PAT-4/ILK requires the ECM component UNC-52/perlecan, the transmembrane protein integrin, and the novel cytoplasmic attachment protein UNC-112 to be properly recruited to nascent attachments. Transgenically expressed "kinase-dead" ILK fully rescues pat-4 loss-of-function mutants. We also identify UNC-112 as a new binding partner for ILK. CONCLUSIONS: Our data strengthens the emerging view that ILK functions primarily as an adaptor protein within integrin adhesion complexes and identifies UNC-112 as a new ILK binding partner.