7,845 research outputs found

    Palladium-Catalyzed Asymmetric Conjugate Addition of Arylboronic Acids to Five-, Six-, and Seven-Membered β-Substituted Cyclic Enones: Enantioselective Construction of All-Carbon Quaternary Stereocenters

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    The first enantioselective Pd-catalyzed construction of all-carbon quaternary stereocenters via 1,4-addition of arylboronic acids to β-substituted cyclic enones is reported. Reaction of a wide range of arylboronic acids and cyclic enones using a catalyst prepared from Pd(OCOCF_3)_2 and a chiral pyridinooxazoline ligand yields enantioenriched products bearing benzylic stereocenters. Notably, this transformation is tolerant to air and moisture, providing a practical and operationally simple method of synthesizing enantioenriched all-carbon quaternary stereocenters

    An Examination of the Relationship Between Ethnic Identity Development, Cognitive Complexity, Differentiation of Self, and Reports of Racial and Ethnic Microaggressions

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    Although individuals may not engage in racism consciously due to social undesirability, they may have biases that manifest in more subtle and unconscious ways. Research has found that people of color experiencing different racial and ethnic microaggressions in their everyday lives are subject to pervasive and negative impacts on their mental health, though little is known about the influence of one’s ethnic identity formation, affective processes, and cognitive processes. A multiple regression analysis was conducted to examine the degree to which ethnic identity development, cognitive complexity, and differentiation of self were associated reported experiences of microaggressions. The analysis indicated that ethnic identity development, cognitive complexity, and differentiation of self was significantly related to reported experiences of microaggressions in African origin (F (11,112)= 4.902, R 2= .325, p = .000) and European Origin (F (11,177)= 3.65, R 2= .170, p =.000) participants. The current study suggests African origin participants who reported more experiences of racial and ethnic microaggressions, engaged in less exploration of their ethnic identity, favored cognitive efforts, and were more tolerance of insolubility. European Origin or White participants who reported more racial and ethnic microaggressions, engaged in less exploration of their ethnic identity and reported a stronger ethnic identity

    Sustainability, stakeholders and business. Editorial

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    Over the past 20 years, there has been an increasing attention on the drivers of value in organizations. Both the strategic management literature and practice have remarked the importance for managers to be aware of the impact of firm activities, products and services on either the external and internal environment and, more generally, on all firm stakeholders. The emergence of the notions of “sustainable development” and “sustainability” reflects a profound change in global thinking, which forces firms to move beyond trade-offs between business and society

    Electrons diffusion and signal noise contributions on electron clusters detection efficiency

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    The Cluster Counting (CC) technique, proposed for dE/dx measurements with the SuperB drift-chamber, could, significantly, improve particle identification by avoiding the fluctuations involved in charge measurements. As the technique is quite sensitive to the detector working conditions and to the front-end chain response, in this note we have investigated the effects on clusters detection efficiency of electron diffusion, preamplifier frequencyresponse and Signal-to-Noise Ratio (SNR) using different algorithms. The evaluation is based on Garfield datasets, generated for a single cell geometry, at different impact points for π /µ/e particles with momenta 120, 140, 160, 180 and 210 MeV. The current waveforms generated by Garfield have been shaped according to the preamplifier response and different amounts of white gaussian noise has been added to the waveforms to simulate different SNRs. Finally an estimation of π /µ/e separation is shown

    A robot-based burr measurement system for the automotive industry

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    Burrs are often difficult to detect and measure because of their intrinsic variability in shape and dimension. No automotive standard had been established about their acceptable dimensions and measurement techniques for sheet steel products. For the automotive industry, even burrs of the size of 100 ÎĽm are perceived as damaging because of their dramatic impact upon panel corrosion resistance and assembly performance. It is critical to measure burrs during panel manufacture in order to control the process. The characterization of the typical burr produced has been carried out employing 3D measurements with a surface profilometer and a SEM. This analysis has shown a typical triangular burr shape and some characteristic dimensions. A contact method and two laser-triangulation systems have been developed. The instrument accuracy was analyzed, based upon a full factorial experimentation over a set of typical panels edges

    Orbital periods of the binary sdB stars PG0940+068 and PG1247+554

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    We have used the radial velocity variations of two sdB stars previously reported to be binaries to establish their orbital periods. They are PG0940+068, (P=8.33d) and PG1247+554 (P=0.599d). The minimum masses of the unseen companions, assuming a mass of 0.5 solar masses for the sdB stars, are 0.090 +/- 0.003 solar masses for PG1247+554 and 0.63 +/- 0.02 solar masses for PG0940+068. The nature of the companions is not constrained further by our data.Comment: 5 pages, 2 figure

    Monte Carlo simulation for radiative kaon decays

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    For high precision measurements of K decays, the presence of radiated photons cannot be neglected. The Monte Carlo simulations must include the radiative corrections in order to compute the correct event counting and efficiency calculations. In this paper we briefly describe a method for simulating such decays.Comment: 11 pages, 1 figur

    Study of the growth parameters involved in synthesizing boron carbide filaments second quarterly report

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    Growth parameters in boron carbide whisker synthesis - molybdenum catalyst, growth chamber geometry, tensile testing assembly, and whisker reinforced composite
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