Investigation into the dirhodium-catalyzed hydroformylation of 1-alkenes and preparation of a novel tetraphosphine ligand

The reaction of the tetraphosphine ligand rac-et,ph-P4 (et,ph-P4 = PEt2CH2CH2(Ph)PCH2P(Ph)CH2CH2PEt2) with 2 equiv. of [Rh(nbd)2]+ (nbd = norbornadiene) generates [rac-Rh2(nbd)2(et,ph-P4)]2+, which is the precursor to a highly active and regioselective hydroformylation catalyst system. The “key” catalyst species generated under H2/CO pressure has been proposed to be the dihydrido complex [rac-Rh2H2(ì-CO)2(et,ph-P4)]2+, and represents one of the most dramatic example of homobimetallic cooperativity in homogeneous catalysis. The addition of even small amounts of PPh3 to this dirhodium tetraphosphine catalyst causes a dramatic drop in the aldehyde linear-to-branched regioselectivity (25:1 to 3:1) in acetone solvent (90 oC, 6.1 bar, 1-hexene). Catalytic results are presented for differing amounts of added PPh3, along with comparisons to the monometallic Rh catalyst family, HRh(CO)x(PPh3)y (x = 1-3; y = 3 – x), generated from PPh3 and Rh(acac)(CO)2 (acac = acetylactonate). The results point to the extremely effective inhibition of the regioselective bimetallic hydroformylation mechanism and the formation of an inefficient monometallic catalyst cycle, but not fragmentation to generate free HRh(CO)(PPh3)2 catalyst. The deactivation of the dirhodium catalyst by CO has been previously demonstrated, and in situ NMR spectroscopic studies have indicated that facile fragmentation is occurring at 90 oC under H2/CO pressure, but also at 25 oC, albeit at a slower rate, which can lead to complete catalyst deactivation. We are trying to address this problem through the design of a novel, far more strongly chelating tetraphosphine ligand rac-et,ph-P4-Ph (et,ph-P4-Ph = PEt2(o-C6H4)P(Ph)CH2(Ph)P(o-C6H4)PEt2). Extensive experimentation has been conducted toward the preparation of this ligand via various synthetic routes centered around sequential deprotonation/alkylation reactions, Grignard-mediated substitutions, aromatic nucleophilic substitutions, and palladium-catalyzed phosphorus-carbon coupling reactions. While these synthetic strategies have given some encouraging results, the new tetraphosphine ligand has been successfully prepared via the rather simple and efficient Grignard-mediated phosphorus-carbon coupling reaction of ClP(Ph)CH2(Ph)PCl with PEt2(o-C6H4)MgBr. The nature of the ligand has been confirmed and characterized by single crystal X-ray crystallography as the nickel complex meso-Ni2Cl4(et,ph-P4-Ph)

Simultaneous Determination of 3-mercaptopyruvate and Cobinamide in Plasma by Liquid Chromatography–tandem Mass Spectrometry

The current suite of Food and Drug Administration (FDA) approved antidotes (i.e., sodium nitrite, sodium thiosulfate, and hydroxocobalamin) are effective for treating cyanide poisoning, but individually, each antidote has major limitations (e.g., large effective dosage or delayed onset of action). To mitigate these limitations, next-generation cyanide antidotes are being investigated, including 3-mercaptopyruvate (3-MP) and cobinamide (Cbi). Analytical methods capable of detecting these therapeutics individually and simultaneously (for combination therapy) are essential for the development of 3-MP and Cbi as potential cyanide antidotes. Therefore, a liquid chromatography–tandem mass-spectrometry method for the simultaneous analysis of 3-MP and Cbi was developed. Sample preparation of 3-MP consisted of spiking plasma with an internal standard (13C3-3-MP), precipitation of plasma proteins, and derivatizing 3-MP with monobromobimane to produce 3-mercaptopyruvate-bimane. Preparation of Cbi involved denaturing plasma proteins with simultaneous addition of excess cyanide to convert each Cbi species to dicyanocobinamide (Cbi(CN)2). The limits of detection for 3-MP and Cbi were 0.5 μM and 0.2 μM, respectively. The linear ranges were 2–500 μM for 3-MP and 0.5–50 μM for Cbi. The accuracy and precision for 3-MP were 100 ± 9% and \u3c8.3% relative standard deviation (RSD), respectively. For Cbi(CN)2, the accuracy was 100 ± 13% and the precision was \u3c9.5% RSD. The method presented here was used to determine 3-MP and Cbi from treated animals and may ultimately facilitate FDA approval of these antidotes for treatment of cyanide poisoning

Optimasi Portofolio Resiko Menggunakan Model Markowitz MVO Dikaitkan dengan Keterbatasan Manusia dalam Memprediksi Masa Depan dalam Perspektif Al-Qur`an

Risk portfolio on modern finance has become increasingly technical, requiring the use of sophisticated mathematical tools in both research and practice. Since companies cannot insure themselves completely against risk, as human incompetence in predicting the future precisely that written in Al-Quran surah Luqman verse 34, they have to manage it to yield an optimal portfolio. The objective here is to minimize the variance among all portfolios, or alternatively, to maximize expected return among all portfolios that has at least a certain expected return. Furthermore, this study focuses on optimizing risk portfolio so called Markowitz MVO (Mean-Variance Optimization). Some theoretical frameworks for analysis are arithmetic mean, geometric mean, variance, covariance, linear programming, and quadratic programming. Moreover, finding a minimum variance portfolio produces a convex quadratic programming, that is minimizing the objective function ðð¥with constraintsð ð 𥠥 ðandð´ð¥ = ð. The outcome of this research is the solution of optimal risk portofolio in some investments that could be finished smoothly using MATLAB R2007b software together with its graphic analysis

Search for heavy resonances decaying to two Higgs bosons in final states containing four b quarks

A search is presented for narrow heavy resonances X decaying into pairs of Higgs bosons (H) in proton-proton collisions collected by the CMS experiment at the LHC at root s = 8 TeV. The data correspond to an integrated luminosity of 19.7 fb(-1). The search considers HH resonances with masses between 1 and 3 TeV, having final states of two b quark pairs. Each Higgs boson is produced with large momentum, and the hadronization products of the pair of b quarks can usually be reconstructed as single large jets. The background from multijet and t (t) over bar events is significantly reduced by applying requirements related to the flavor of the jet, its mass, and its substructure. The signal would be identified as a peak on top of the dijet invariant mass spectrum of the remaining background events. No evidence is observed for such a signal. Upper limits obtained at 95 confidence level for the product of the production cross section and branching fraction sigma(gg -> X) B(X -> HH -> b (b) over barb (b) over bar) range from 10 to 1.5 fb for the mass of X from 1.15 to 2.0 TeV, significantly extending previous searches. For a warped extra dimension theory with amass scale Lambda(R) = 1 TeV, the data exclude radion scalar masses between 1.15 and 1.55 TeV

Measurement of the top quark mass using charged particles in pp collisions at root s=8 TeV

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Search for supersymmetry in events with one lepton and multiple jets in proton-proton collisions at root s=13 TeV

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Search for anomalous couplings in boosted WW/WZ -> l nu q(q)over-bar production in proton-proton collisions at root s=8TeV

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Development and validation of HERWIG 7 tunes from CMS underlying-event measurements

This paper presents new sets of parameters (“tunes”) for the underlying-event model of the HERWIG7 event generator. These parameters control the description of multiple-parton interactions (MPI) and colour reconnection in HERWIG7, and are obtained from a fit to minimum-bias data collected by the CMS experiment at s=0.9, 7, and 13Te. The tunes are based on the NNPDF 3.1 next-to-next-to-leading-order parton distribution function (PDF) set for the parton shower, and either a leading-order or next-to-next-to-leading-order PDF set for the simulation of MPI and the beam remnants. Predictions utilizing the tunes are produced for event shape observables in electron-positron collisions, and for minimum-bias, inclusive jet, top quark pair, and Z and W boson events in proton-proton collisions, and are compared with data. Each of the new tunes describes the data at a reasonable level, and the tunes using a leading-order PDF for the simulation of MPI provide the best description of the dat

Measurement of nuclear modification factors of gamma(1S)), gamma(2S), and gamma(3S) mesons in PbPb collisions at root s(NN)=5.02 TeV

The cross sections for ϒ(1S), ϒ(2S), and ϒ(3S) production in lead-lead (PbPb) and proton-proton (pp) collisions at √sNN = 5.02 TeV have been measured using the CMS detector at the LHC. The nuclear modification factors, RAA, derived from the PbPb-to-pp ratio of yields for each state, are studied as functions of meson rapidity and transverse momentum, as well as PbPb collision centrality. The yields of all three states are found to be significantly suppressed, and compatible with a sequential ordering of the suppression, RAA(ϒ(1S)) > RAA(ϒ(2S)) > RAA(ϒ(3S)). The suppression of ϒ(1S) is larger than that seen at √sNN = 2.76 TeV, although the two are compatible within uncertainties. The upper limit on the RAA of ϒ(3S) integrated over pT, rapidity and centrality is 0.096 at 95% confidence level, which is the strongest suppression observed for a quarkonium state in heavy ion collisions to date. © 2019 The Author(s). Published by Elsevier B.V. This is an open access article under the CC BY license (http://creativecommons.org/licenses/by/4.0/). Funded by SCOAP3.Peer reviewe