Remote Oxidative Activation of a [Cp*Rh] Monohydride

Half-sandwich rhodium monohydrides are often proposed as intermediates in catalysis, but little is known regarding the redox-induced reactivity accessible to these species. Here, the κ2-bis-diphenylphosphinoferrocene (dppf) ligand has been used to explore the reactivity that can be induced when a [Cp*Rh] monohydride undergoes remote (dppf-centered) oxidation by 1e–. Chemical and electrochemical studies showed that one-electron redox chemistry is accessible to Cp*Rh(dppf), including a unique quasi-reversible RhII/I process at –0.96 V vs. ferrocenium/ferrocene (Fc+/0). This redox manifold was confirmed by isolation of an uncommon Rh(II) species that was characterized by EPR spectroscopy. Protonation of Cp*Rh(dppf) with anilinium triflate yielded an isolable and inert monohydride, and this species was found to undergo a quasireversible electrochemical oxidation at +0.41 V vs Fc+/0 that corresponds to iron-centered oxidation in the dppf backbone. Thermochemical analysis predicts that this dppf-centered oxidation drives a dramatic increase in acidity of the Rh–H moiety by 23 pKa units, a reactivity pattern confirmed by in situ 1H NMR studies. Taken together, these results show that remote oxidation can effectively induce M–H activation and suggest that ligand-centered redox activity could be an attractive feature for design of new systems relying on hydride intermediates.

Design and Implementation of AGU based FFT Pipeline Architecture

Present it is most needful task to get various applications with parallel computations by using a Fast Fourier Transform (FFT) and the derived outputs should be in regular format. This can be achieved by using an advanced technique called Multipath delay commutator (MDC) Pipelining FFT processor and this processor will be capable to perform the computation of a different data streams at a time. In this paper the design and implementation of AGU based Pipelined FFT architecture is done Caluclation of a butterfly is done within 2 cycles by the instructions proposed. A Data Processing Unit (DPU) is employed in this pipeline architecture and supports the instructions & an FFT Adress Generation Unit (FAGU) caluclates butterfly input & output data adresses automatically. The DPU proposed sysyem requires less area compared to commericial DSP chips. Futhermore, the proposed FAGU reduces the number of FFT computation cycles. The FFT design architecture will have real data paths. With various FFT sizes, different radix & various parallesim levels, the FFT can be mapped to the pipeline architecture. The most attractive feature of the pipelined FFT architecture is it consists of bit reversal operation so it requires little number of registers and better throughput.

Analysis of the optical properties of the silvery spots on the wings of the Gulf Fritillary, Dione vanillae

The ventral face of the wings of the butterfly Dione vanillae is covered with bright and shiny silvery spots. These areas contain densely packed ground- and coverscales with a bright metallic appearance reflecting more than 50% of light uniformly over the visible range. Our analysis shows that this optically attractive feature is caused by the inner microstructure of the scales located in these areas. Electron microscopy of cross sections through the scales shows that upper and lower lamina, supporting trabeculae, and topping ridges can be approximated by a ‘circus tent’-like geometry. By simulating its optical properties, we show that a moderate disorder of this geometry is important for the uniform reflection of light resulting in the silvery appearance.

In defence of explanatory realism

Explanatory realism is the view that explanations work by providing information about relations of productive determination such as causation or grounding. The view has gained considerable popularity in the last decades, especially in the context of metaphysical debates about non-causal explanation. What makes the view particularly attractive is that it fits nicely with the idea that not all explanations are causal whilst avoiding an implausible pluralism about explanation. Another attractive feature of the view is that it allows explanation to be a partially epistemic, context-dependent phenomenon. In spite of its attractiveness, explanatory realism has recently been subject to criticism. In particular, Taylor (Philos Stud 175(1):197–219, 2018). has presented four types of explanation that the view allegedly cannot account for. This paper defends explanatory realism against Taylor’s challenges. We will show that Taylor’s counterexamples are either explanations that turn out to provide information about entities standing in productive determination relations or that they are not genuine explanations in the first place.

Adaptive operator extrapolation method

This paper is devoted to the study of nоvel algorithm with Bregman projection for solving variational inequalities in Hilbert space. Proposed algorithm is an adaptive version of the operator extrapolation method, where the used rule for updating the step size does not require knowledge of Lipschitz constants and the calculation of operator values at additional points. An attractive feature of the algorithm is only one computation at the iterative step of the Bregman projection onto the feasible set.

Lattice-Based Logarithmic-Size Non-Interactive Deniable Ring Signatures

Deniable ring signature can be regarded as group signature without group manager, in which a singer is capable of singing a message anonymously, but, if necessary, each ring member is allowed to confirm or disavowal its involvement in the signature via an interactive mechanism between the ring member and the verifier. This attractive feature makes the deniable ring signature find many applications in the real world. In this work, we propose an efficient scheme with signature size logarithmic to the cardinality of the ring. From a high level, we adapt Libert et al.’s zero-knowledge argument system (Eurocrypt 2016) to allow the prover to convince the verifier that its witness satisfies an additional condition. Then, using the Fait-Shamir transformation, we get a non-interactive deniable ring signature scheme that satisfies the anonymity, traceability, and non-frameability under the small integer solution assumption in the random oracle model.

Responsivity and Noise Equivalent Power of a Single Cold-Electron Bolometer

We have developed a single-pixel capacitively coupled Cold-Electron Bolometer (CEB) and characterized it in the current-biased regime. The most attractive feature of the CEB is effective electron self-cooling of the absorber, which leads to a lower bolometer noise and higher dynamic range. The bolometer responsivity was measured by determining the voltage response to an applied power through the absorber from a heating current, modulated at frequencies from 35 Hz to 2 kHz. The optimum responsivity of 1.5 × 1010 V/W was measured at a modulation frequency of 35 Hz. The noise equivalent power (NEP) was subsequently obtained from the estimated bolometer noise voltage with respect to the measured bolometer responsivity. The NEP of better 2 × 10−18 W/Hz1/2 was obtained for modulation frequencies greater than 100 Hz. The background power and the bolometer time constant were also estimated from the experimental results. The photon-noise-limited operation of CEB will dominate for a signal power of 10 fW and higher at frequency 80 GHz and higher.

Simple and Fast Generalized - M (GM) Estimator and Its Application to Real Data Set

It is now evident that some robust methods such as MM-estimator do not address the concept of bounded influence function, which means that their estimates still be affected by outliers in the X directions or high leverage points (HLPs), even though they have high efficiency and high breakdown point (BDP). The Generalized M(GM) estimator, such as the GM6 estimator is put forward with the main aim of making a bound for the influence of HLPs by some weight function. The limitation of GM6 is that it gives lower weight to both bad leverage points (BLPs) and good leverage points (GLPs) which make its efficiency decreases when more GLPs are present in a data set. Moreover, the GM6 takes longer computational time. In this paper, we develop a new version of GM-estimator which is based on simple and fast algorithm. The attractive feature of this method is that it only downs weights BLPs and vertical outliers (VOs) and increases its efficiency. The merit of our proposed GM estimator is studied by simulation study and well-known aircraft data set.

Plasmonic Coupler and Multiplexer/Demultiplexer Based on Nano-Groove-Arrays

A novel plasmonic unidirectional coupler and its extension to a multiplexer/demultiplexer are proposed and simulated. The proposed structure can be etched adjacent to metal-insulator-metal (MIM) waveguides which can result in considerable reduction in footprint of optical signal processing systems. Simulated results show very good agreement with design. Extinction ratio (ER) of more than 11 dB was achieved for both the coupler as well as the multiplexer/demultiplexer. Crosstalk as well as full width at half maximum (FWHM) was also highly acceptable for the multiplexer/demultiplexer. The proposed structures have an additional attractive feature of being amenable to integration with other relevant functionalities as demonstrated in the results.

The Stabilizing Effect of Pre-Equilibria: A Trifluoromethyl Complex as CF2 Reservoir in Catalytic Olefin Difluorocarbenation

A new, efficient, catalytic difluorocarbenation of olefins to give 1,1-difluorocyclopropanes is presented. The catalyst, an organobismuth complex, uses TMSCF₃ as a stoichiometric difluorocarbene source. We demonstrate both the viability and robustness of this reaction over a wide range of alkenes and alkynes, including electron-poor alkenes, to generate the corresponding 1,1-difluorocyclopropanes and 1,1-difluorocyclopropenes. Ease of catalyst recovery from the reaction mixture is another attractive feature of this method. In depth experimental and theoretical studies showed that the key difluorocarbene-generating step proceeds through a bismuth non-redox synchronous mechanism generating a highly reactive free CF₂ in an endergonic pre-equilibrium. It is the reversibility when generating the difluorocarbene that accounts for the high selectivity, while minimizing CF₂-recombination side-reactions.