The hard physics of soft muons: novel measurement of the top-quark mass and differential cross-sections of top-quark pair production using the ATLAS detector at the LHC

The mass of the top quark is measured in lepton+jets top-quark pair events with an experimental technique exploits the semileptonic decay of $b$ hadrons. An invariant mass is constructed between the lepton from the $W$-boson decay and a soft muon originating from a $b$-hadron decay. A binned-template likelihood fit is performed to the invariant mass distribution yielding the most precise \ATLAS measured value of the top-quark mass of $m_t = 174.44 \pm 0.76\,\textrm{(stat+syst)}\, \textrm{GeV}$. Measurements of differential cross-sections of top-quark pair production are performed as a function of several observables related to the decay of the $W$ boson and $b$ hadron. These measured cross-sections are compared to various predictions

Tris(2,4,6-trifluorophenyl)borane: an efficient hydroboration catalyst

The metal-free catalyst tris(2,4,6-trifluorophenyl)borane has demonstrated its extensive applications in the 1,2-hydroboration of numerous unsaturated reagents, namely alkynes, aldehydes and imines, consisting of a wide array of electron-withdrawing and donating functionalities. A range of over 50 borylated products are reported, with many reactions proceeding with low catalyst loading under ambient conditions. These pinacol boronate esters, in the case of aldehydes and imines, can be readily hydrolyzed to leave the respective alcohol and amine, whereas alkynyl substrates result in vinyl boranes. This is of great synthetic use to the organic chemist

Enantioselective main group catalysis: modern catalysts for organic transformations

This review highlights a number of recent developments in the field of main group enantioselective catalysis. Many essential transformations can be effected catalytically such as hydrosilylation, hydroamination and hydrogenation reactions, amongst others, in an asymmetric fashion using earth abundant s- and p-block elements such as calcium, strontium, boron and aluminum. Recent work in this area has shown that these systems are not only active in catalysis but may also have the potential to compete with transition metal based systems with the reduced cost and toxicity sometimes associated with main group chemistry

Soybean inoculation studies

The results of the soybean inoculation studies reported in this bulletin were obtained under field conditions, and the experiments extended over a period of three years. These studies included the testing of different ways of applying inoculated soil to soybean seeds as well as to the soil, and also the testing of a number of commercial cultures, secured from different sources, on the inoculation of soybeans. Data have also been reported which show the relative efficiencies of soil from different sources, pure cultures of soybean bacteria, and different commercial cultures on the inoculation of different varieties of soybeans. The effects of inoculation, lime and lime and superphosphate, on the percentage of nitrogen in soybean plants have also been noted. In some cases the experiments were repeated for two or three years, and the results obtained each year agreed remarkably well

Hard versus soft reactivity of Lewis acidic boranes

This work outlines the use of Lewis acidic boranes in a variety of different reactions, mainly in the activation of unsaturated substrates such as allenes, alkynes, ketones, aldehydes and imines. The activation of allenes toward frustrated Lewis pairs showed that a formal 1,4-addition product prevails, trapping the product as the zwitterionic s-cis diene species. Conversely, reacting these same substrates with B(C6F5)3 alone allows two distinct reactive pathways; either σ-activation to yield the scarcely observed 1,2- carboboration product or π-activation followed by dealkylation to generate the γ-lactone. Following this second activation mode, the reaction between propargyl esters, amides, carbamates and carbonates with a variety of homo- and hetero-leptic boranes as well as borocations promotes the 5-exo-dig cyclisation which, depending on the substrate, was either isolated as the oxazolium or dioxaborinine heterocycle. In addition, utilising the Lewis acid PhBCl2 in this reaction interestingly produces the hitherto unreported 1,3-haloboration of alkynes. B(C6F5)3 was also shown to be hugely successful in a number of other ring closing reactions, specifically the 6-endo-dig cyclisation of alkynyl ester derivatives to form various pyrones, isocoumarins and pyryliums. Of particular interest is the development of a new methodology for catalytic carbon-carbon bond formation through alkyl group transfer. In this case, benzyl, α-methylbenzyl and benzhydryl functionalised alkynyl esters underwent the expected cyclisation using catalytic B(C6F5)3 to form the lactone however, 1,5-migration occurs from oxygen to carbon to generate the corresponding γ-functionalised pyrones and isocoumarins. Finally, a diverse array of reduction chemistry was performed by attenuating the Lewis acidity at boron to specialise its function in catalysis. Other work focused on the exploitation of novel processing technologies to improve conventional batch-type main group reactivity via continuous-flow chemistry. Additionally, biologically inspired dihydropyridines were used in the formation of thermally stable borohydrides as well as elemental hydrogen surrogates in boron mediated transfer hydrogenation pathway

Engage Stakeholders in Program Evaluation: Throw Them a Party!

A data party is an engaging way to involve stakeholders in program evaluation. We explain the use of a data party for engaging 4-H program stakeholders (e.g., staff and volunteers) in data interpretation and helping them understand, embrace, and use program evaluation information to make data-driven decisions about their programs. We present two tools that can be used for presenting data in a clear and meaningful way: data place mats and gallery walks. We also provide information on the process we used, our lessons learned, and the utility of data parties in Extension programming

Reactions of biologically inspired hydride sources with B(C6F5)3

The combination of 1-benzyl-1,4-dihydropyridines with the strong Lewis acid, B(C6F5)3, generates a stable pyridinium borohydride species in high yields (94%) in as little as 10 min. This use of biologically inspired hydride sources further builds on the recent work of new hydride donors in the formation of borohydrides. When functionalizing the dihydropyridine with an amide or carboxylic acid moiety, a disproportionation reaction composed of a series of protonation/reduction steps is observed upon the addition of B(C6F5)3. As a result, one equivalent of dihydropyridine undergoes net hydrogenation, whereas the other is dehydrogenated yielding the pyridinium counterpart in a transfer hydrogenation-type mechanism

BUMC Annual Report

Annual report of the Boston University Medical Center