Overriding Intrinsic Reactivity in Aliphatic C−H Oxidation: Preferential C3/C4 Oxidation of Aliphatic Ammonium Substrates

The site-selective C−H oxidation of unactivated positions in aliphatic ammonium chains poses a tremendous synthetic challenge, for which a solution has not yet been found. Here, we report the preferential oxidation of the strongly deactivated C3/C4 positions of aliphatic ammonium substrates by employing a novel supramolecular catalyst. This chimeric catalyst was synthesized by linking the well-explored catalytic moiety Fe(pdp) to an alkyl ammonium binding molecular tweezer. The results highlight the vast potential of overriding the intrinsic reactivity in chemical reactions by guiding catalysis using supramolecular host structures that enable a precise orientation of the substrates

Non-linear behavior of Al-contacted pure amorphous boron (PureB) devices at low temperatures

Deposition of pure amorphous boron (PureB) layers on n-type Si results in p+n-like devices even in cases where B in-diffusion during the deposition is not expected. It is suspected that such behavior is due to the formation of an interfacial hole layer (IHL) between the PureB and Si. To further investigate physical mechanisms governing conduction of holes across the PureB/Si interface and through the IHL, electrical measurements were performed from room temperature down to cryogenic temperatures as low as 100 K. In this paper, current-voltage (I-V) measurements are made on structures where the PureB connects to p-type Si regions. One set of devices comprises ring-shaped structures designed for measuring the conductance through the IHL. In these structures, the PureB layer is deposited in rings that are contacted at the inner and outer perimeter with Al. Another set of samples includes devices where the PureB layer was deposited on p-type bulk Si. At room temperature, a close to linear change of current with voltage was seen irrespective of the PureB layer thickness and post-deposition processing. Lowering the operating temperature led to an increasingly non-linear I-V characteristics. Plausible explanations for the non-linear behavior are considered and discussed in the paper

Decoherence due to contacts in ballistic nanostructures

The active region of a ballistic nanostructure is an open quantum-mechanical system, whose nonunitary evolution (decoherence) towards a nonequilibrium steady state is determined by carrier injection from the contacts. The purpose of this paper is to provide a simple theoretical description of the contact-induced decoherence in ballistic nanostructures, which is established within the framework of the open systems theory. The active region's evolution in the presence of contacts is generally non-Markovian. However, if the contacts' energy relaxation due to electron-electron scattering is sufficiently fast, then the contacts can be considered memoryless on timescales coarsened over their energy relaxation time, and the evolution of the current-limiting active region can be considered Markovian. Therefore, we first derive a general Markovian map in the presence of a memoryless environment, by coarse-graining the exact short-time non-Markovian dynamics of an abstract open system over the environment memory-loss time, and we give the requirements for the validity of this map. We then introduce a model contact-active region interaction that describes carrier injection from the contacts for a generic two-terminal ballistic nanostructure. Starting from this model interaction and using the Markovian dynamics derived by coarse-graining over the effective memory-loss time of the contacts, we derive the formulas for the nonequilibrium steady-state distribution functions of the forward and backward propagating states in the nanostructure's active region. On the example of a double-barrier tunneling structure, the present approach yields an I-V curve with all the prominent resonant features. The relationship to the Landauer-B\"{u}ttiker formalism is also discussed, as well as the inclusion of scattering.Comment: Published versio

Fake news and critical thinking in information evaluation

In the post-truth era we are constantly bombarded with “news” which is fabricated, distorted, and massaged information, published with the intention to deceive and mislead others. Such “news” has come to be known as “fake news”. The influence of fake news can have profound socio-political and cultural effects when translated into action. The ability to distinguish between real facts, fabricated stories, rumours, propaganda, or opinions is of paramount importance. The rapid proliferation of information through social media is now the norm. In this paper we consider the challenge of preparing students, in developing skills for recognising mis-information, dis-information and mal-information. We argue that critical thinking for evaluating information should now be considered a basic literacy, equally important to literacy itself, as well as information and information technology literacies. In this paper we revisit Bloom’s taxonomy of cognitive skills and represent what a learner can achieve at each level. We customise the traditional moral and ethical concepts suggested by the US Content Subcommittee of the ImpactCS Steering Committee to flag the ethical concerns over mis-information, dis-information and mal-information. We report on current levels of awareness and practices at the authors’ five higher education institutions, and reveal varying levels of awareness of the significance of critical literacy and different practices in each location. The paper concludes with an outline of future work

Bilateral papillitis and unilateral focal chorioretinitis as the presenting features of syphilis.

BACKGROUND: Syphilis is a multisystem bacterial infection caused by Treponema pallidum. The incidence of infection in the United States has risen by more than 75% since the year 2000, when it was at a low of 2.1 per 100,000 people. Ocular involvement may occur in any stage of infection and may present in a variety of ways, with posterior uveitis being the most common manifestation. We report a case of ocular syphilis infection with an unusual presentation of bilateral non-granulomatous panuveitis with papillitis and unilateral focal chorioretinitis. FINDINGS: This is a retrospective case report with literature review. A 39-year-old Caucasian female presented with a 2-week history of bilateral ocular flashes and left eye pain. Dilated fundus examination revealed mild optic disc edema in both eyes, the right eye more than the left. In the left eye, there was an area of retinal elevation and whitening involving the peripheral retina. Fluorescein angiography, B-scan ultrasonography, and ocular coherence tomography were performed, and laboratory tests were ordered based on the clinical presentation. After rapid plasma reagin (RPR) and fluorescent treponemal antibody absorption (FTA-Abs) were positive, syphilitic uveitis was confirmed, and the patient was admitted for a 14-day course of high-dose intravenous penicillin G. CONCLUSIONS: The first signs and symptoms of syphilis may be ocular, which can lead to a diagnostic challenge. A high index of suspicion is the key for early diagnosis of ocular syphilis. Prompt treatment with intravenous penicillin G is highly effective in resolving the infection

EC11-101 Spring Seed Guide

Welcome to the 2011 Spring Seed Guide. Corn, soybean, sorghum, and alfalfa are included in this seed guide. This circular is a progress report of variety trials conducted by personnel of the Agronomy Department, West Central, and Northeast Extension Centers, and their associated agricultural laboratories and the associates of the University of Wyoming at SAREC