Characterization of the earliest intermediate of Fe-N_2 protonation: CW and Pulse EPR detection of an Fe-NNH species and its evolution to Fe-NNH_2^+

Iron diazenido species (Fe(NNH)) have been proposed as the earliest intermediates of catalytic N_2-to-NH_3 conversion (N_2RR) mediated by synthetic iron complexes and relatedly as intermediates of N_2RR by nitrogenase enzymes. However, direct identification of such iron species, either during or independent of catalysis, has proven challenging owing to their high degree of instability. The isolation of more stable silylated diazenido analogues, Fe(NNSiR_3), and also of further downstream intermediates (e.g., Fe(NNH_2)), nonetheless points to Fe(NNH) as the key first intermediate of protonation in synthetic systems. Herein we show that low-temperature protonation of a terminally bound Fe-N_2– species, supported by a bulky trisphosphinoborane ligand (^(Ar)P_3^B), generates an S = 1/2 terminal Fe(NNH) species that can be detected and characterized by continuous-wave (CW) and pulse EPR techniques. The ^1H-hyperfine for ^(Ar)P_3^BFe(NNH) derived from the presented ENDOR studies is diagnostic for the distally bound H atom (a_(iso) = 16.5 MHz). The Fe(NNH) species evolves further to cationic [Fe(NNH_2)]+ in the presence of additional acid, the latter being related to a previously characterized [Fe(NNH_2)]+ intermediate of N2RR mediated by a far less encumbered iron tris(phosphine)borane catalyst. While catalysis is suppressed in the present sterically very crowded system, N_2-to-NH_3 conversion can nevertheless be demonstrated. These observations in sum add support to the idea that Fe(NNH) plays a central role as the earliest intermediate of Fe-mediated N2RR in a synthetic system

Characterization of the earliest intermediate of Fe-N_2 protonation: CW and Pulse EPR detection of an Fe-NNH species and its evolution to Fe-NNH_2^+

Iron diazenido species (Fe(NNH)) have been proposed as the earliest intermediates of catalytic N_2-to-NH_3 conversion (N_2RR) mediated by synthetic iron complexes and relatedly as intermediates of N_2RR by nitrogenase enzymes. However, direct identification of such iron species, either during or independent of catalysis, has proven challenging owing to their high degree of instability. The isolation of more stable silylated diazenido analogues, Fe(NNSiR_3), and also of further downstream intermediates (e.g., Fe(NNH_2)), nonetheless points to Fe(NNH) as the key first intermediate of protonation in synthetic systems. Herein we show that low-temperature protonation of a terminally bound Fe-N_2– species, supported by a bulky trisphosphinoborane ligand (^(Ar)P_3^B), generates an S = 1/2 terminal Fe(NNH) species that can be detected and characterized by continuous-wave (CW) and pulse EPR techniques. The ^1H-hyperfine for ^(Ar)P_3^BFe(NNH) derived from the presented ENDOR studies is diagnostic for the distally bound H atom (a_(iso) = 16.5 MHz). The Fe(NNH) species evolves further to cationic [Fe(NNH_2)]+ in the presence of additional acid, the latter being related to a previously characterized [Fe(NNH_2)]+ intermediate of N2RR mediated by a far less encumbered iron tris(phosphine)borane catalyst. While catalysis is suppressed in the present sterically very crowded system, N_2-to-NH_3 conversion can nevertheless be demonstrated. These observations in sum add support to the idea that Fe(NNH) plays a central role as the earliest intermediate of Fe-mediated N2RR in a synthetic system

Pathological findings in a natural outbreak of aflatoxicosis in dogs

The gross and histopathological lesions of 10 cases in a natural outbreak of aflatoxicosis amongst dogs in the Republic of South Africa are reported. The 10 cases were classified as acute (1 case), subacute (7 cases) and chronic (2 cases) on the basis of the nature, degree and extent of the following histopathological feactures : hepatocellular fatty degeneration, necrosis or regeneration ; proliferation of bile ductules ; accumulation of bile within the canaliculi ; fibroplasia; and, mucoid degeneration, necrosis or segmental atrophy of the larger intrahepatic bile ducts. Fatty degeneration was noted grossly in the Iivers of all 10 cases and bile stasis in 4. Varying degrees of fibrosis were present depending on the stage of the disease. In the 2 chronic cases in which nodular regeneration was also observed fibrosis was pronounced. Other macroscopic findings included icterus, anaemia, ascites, hydrothorax, hydropericardium, anasarca, pulmonary oedema, gastro-enterorrhagia and nephrosis.The articles have been scanned in colour with a HP Scanjet 5590; 600dpi. Adobe Acrobat XI Pro was used to OCR the text and also for the merging and conversion to the final presentation PDF-format.lmchunu2014mn201

Longitudinal performance of senescence accelerated mouse prone-strain 8 (SAMP8) mice in an olfactory-visual water maze challenge

© 2018 Lam, Takechi, Albrecht, D’Alonzo, Graneri, Hackett, Coulson, Fimognari, Nesbit and Mamo. Morris water maze (MWM) is widely used to assess cognitive deficits in pre-clinical rodent models. Latency time to reach escape platform is frequently reported, but may be confounded by deficits in visual acuity, or differences in locomotor activity. This study compared performance of Senescence Accelerated Mouse Prone-Strain 8 (SAMP8) and control Senescence Accelerated Mouse Resistant-Strain 1 (SAMR1) mice in classical MWM, relative to performance in a newly developed olfactory-visual maze testing protocol. Performance indicated as the escape time to rescue platform for classical MWM testing showed that SAMP8 mice as young as 6 weeks of age did poorly relative to age-matched SAMR1 mice. The olfactory-visual maze challenge described better discriminated SAMP8 vs. SAMR1 mice than classical MWM testing, based on latency time measures. Consideration of the distance traveled rather than latency time in the classical MWM found no treatment effects between SAMP8 and SAMR1 at 40 weeks of age and the olfactory-visual measures of performance confirmed the classical MWM findings. Longitudinal (repeat) assessment of SAMP8 and SAMR1 performance at 6, 20, 30, and 40 weeks of age in the olfactory-visual testing protocol showed no age-associated deficits in SAMP8 mice to the last age end-point indicated. Collectively, the results from this study suggest the olfactory-visual testing protocol may be advantageous compared to classical MWM as it avoids potential confounders of visual impairment in some strains of mice and indeed, may offer insight into cognitive and behavioral deficits that develop with advanced age in the widely used SAMP8 murine model

Quantitative assessment of the conjunctival microcirculation using a smartphone and slit-lamp biomicroscope

Purpose: The conjunctival microcirculation is a readily-accessible vascular bed for quantitative haemodynamic assessment and has been studied previously using a digital charge-coupled device (CCD). Smartphone video imaging of the conjunctiva, and haemodynamic parameter quantification, represents a novel approach. We report the feasibility of smartphone video acquisition and subsequent haemodynamic measure quantification via semi-automated means. Methods: Using an Apple iPhone 6 s and a Topcon SL-D4 slit-lamp biomicroscope, we obtained videos of the conjunctival microcirculation in 4 fields of view per patient, for 17 low cardiovascular risk patients. After image registration and processing, we quantified the diameter, mean axial velocity, mean blood volume flow, and wall shear rate for each vessel studied. Vessels were grouped into quartiles based on their diameter i.e. group 1 (&lt;11 μm), 2 (11–16 μm), 3 (16–22 μm) and 4 (&gt;22 μm). Results: From the 17 healthy controls (mean QRISK3 6.6%), we obtained quantifiable haemodynamics from 626 vessel segments. The mean diameter of microvessels, across all sites, was 21.1μm (range 5.8–58 μm). Mean axial velocity was 0.50mm/s (range 0.11–1mm/s) and there was a modestly positive correlation (r 0.322) seen with increasing diameter, best appreciated when comparing group 4 to the remaining groups (p &lt; .0001). Blood volume flow (mean 145.61pl/s, range 7.05–1178.81pl/s) was strongly correlated with increasing diameter (r 0.943, p &lt; .0001) and wall shear rate (mean 157.31 s − 1, range 37.37–841.66 s − 1) negatively correlated with increasing diameter (r − 0.703, p &lt; .0001). Conclusions: We, for the first time, report the successful assessment and quantification of the conjunctival microcirculatory haemodynamics using a smartphone-based system. </p

E–H Bond Activations and Hydrosilylation Catalysis with Iron and Cobalt Metalloboranes

An exciting challenge in transition metal catalyst design is to explore whether earth-abundant base metals such as Fe, Co, and Ni can mediate two-electron reductive transformations that their precious metal counterparts (e.g., Ru, Rh, Ir, and Pd) are better known to catalyze. Organometallic metalloboranes are an interesting design concept in this regard because they can serve as organometallic frustrated Lewis pairs. To build on prior studies with nickel metalloboranes featuring the DPB and ^(Ph)DPB^(Mes) ligands in the context of H_2 and silane activation and catalysis (DPB = bis(o-diisopropylphosphinophenyl)phenylborane, ^(Ph)DPB^(Mes) = bis(o-diphenylphosphinophenyl)mesitylborane), we now explore the reactivity of iron, [(DPB)Fe]_2(N_2), 1, and cobalt, (DPB)Co(N_2), 2, metalloboranes toward a series of substrates with E–H bonds (E = O, S, C, N) including phenol, thiophenol, benzo[h]quinoline, and 8-aminoquinoline. In addition to displaying high stoichiometric E–H bond activation reactivity, complexes 1 and 2 prove to be more active catalysts for the hydrosilylation of ketones and aldehydes with diphenylsilane relative to (^(Ph)DPB^(Mes))Ni. Indeed, 2 appears to be the most active homogeneous cobalt catalyst reported to date for the hydrosilylation of acetophenone under the conditions studied

A multidisciplinary systematic review of the use of diagrams as a means of collecting data from research subjects: application, benefits and recommendations

BACKGROUND: In research, diagrams are most commonly used in the analysis of data and visual presentation of results. However there has been a substantial growth in the use of diagrams in earlier stages of the research process to collect data. Despite this growth, guidance on this technique is often isolated within disciplines. METHODS: A multidisciplinary systematic review was performed, which included 13 traditional healthcare and non-health-focused indexes, non-indexed searches and contacting experts in the field. English-language articles that used diagrams as a data collection tool and reflected on the process were included in the review, with no restriction on publication date. RESULTS: The search identified 2690 documents, of which 80 were included in the final analysis. The choice to use diagrams for data collection is often determined by requirements of the research topic, such as the need to understand research subjects' knowledge or cognitive structure, to overcome cultural and linguistic differences, or to understand highly complex subject matter. How diagrams were used for data collection varied by the degrees of instruction for, and freedom in, diagram creation, the number of diagrams created or edited and the use of diagrams in conjunction with other data collection methods. Depending on how data collection is structured, a variety of options for qualitative and quantitative analysis are available to the researcher. The review identified a number of benefits to using diagrams in data collection, including the ease with which the method can be adapted to complement other data collection methods and its ability to focus discussion. However it is clear that the benefits and challenges of diagramming depend on the nature of its application and the type of diagrams used. DISCUSSION/CONCLUSION: The results of this multidisciplinary systematic review examine the application of diagrams in data collection and the methods for analyzing the unique datasets elicited. Three recommendations are presented. Firstly, the diagrammatic approach should be chosen based on the type of data needed. Secondly, appropriate instructions will depend on the approach chosen. And thirdly, the final results should present examples of original or recreated diagrams. This review also highlighted the need for a standardized terminology of the method and a supporting theoretical framework

Subject-specific computer simulation model for determining elbow loading in one-handed tennis backhand groundstrokes

This article was published in the journal Sports Biomechanics [© Taylor and Francis] and the definitive version is available from; http://www.tandfonline.com/doi/abs/10.1080/14763141.2011.629306.A subject-specific angle-driven computer model of a tennis player, combined with a forward dynamics, equipment-specific computer model of tennis ball–racket impacts, was developed to determine the effect of ball–racket impacts on loading at the elbow for one-handed backhand groundstrokes. Matching subject-specific computer simulations of a typical topspin/slice one-handed backhand groundstroke performed by an elite tennis player were done with root mean square differences between performance and matching simulations of < 0.5°over a 50 ms period starting from ball impact. Simulation results suggest that for similar ball–racket impact conditions, the difference in elbow loading for a topspin and slice one-handed backhand groundstroke is relatively small. In this study, the relatively small differences in elbow loading may be due to comparable angle–time histories at the wrist and elbow joints with the major kinematic differences occurring at the shoulder. Using a subject-specific angle-driven computer model combined with a forward dynamics, equipment-specific computer model of tennis ball–racket impacts allows peak internal loading, net impulse, and shock due to ball–racket impact to be calculated which would not otherwise be possible without impractical invasive techniques. This study provides a basis for further investigation of the factors that may increase elbow loading during tennis strokes

Di-&amp;#956;-bromido-bis[benzyl(diethyl ether)magnesium]

The title benzyl Grignard reagent, [Mg2Br2(C7H7)2(C4H10O)2], was obtained by reaction of benzyl bromide with magnesium in diethyl ether, followed by crystallization from toluene. The asymmetric unit comprises one half-molecule, the structural dimeric unit being generated by inversion symmetry with an Mg...Mg distance of 3.469&amp;#8197;(2)&amp;#8197;&amp;#197;. The Mg(II) atom exhibits a distorted tetrahedral coordination geometry. The crystal packing is defined by van der Waals interactions only