Synthesis of 3,4-Bis(benzylidene)cyclobutenes

The syntheses of several derivatives of 3,4-bis(benzylidene)cyclobutene are reported. Previously unknown 1,2-dibromo-3,4-bis(benzylidene)cyclobutene was obtained through in situ generation of 1,6-diphenyl-3,4-dibromo-1,2,4,5-tetraene followed by electrocyclic ring closure. Ensuing reduction and metal-catalyzed cross-coupling provided additional derivatives. The effects of ring strain on the geometry and electronics of these derivatives were examined by X-ray crystallography and ¹H NMR spectroscopy, respectively.National Science Foundation (U.S.)United States. Army Research OfficeMassachusetts Institute of Technology. Institute for Soldier Nanotechnologie

Quantum Information Processing with Trapped Ion Chains

Trapped atomic ion systems are currently the most advanced platform for quantum information processing. Their long coherence times, pristine state initialization and detection, and precisely controllable and versatile interactions make them excellent quantum systems for experiments in quantum computation and quantum simulation. One of the more promising schemes for quantum computing consists of performing single and multi-qubit quantum gates on qubits in a linear ion crystal. Some of the key challenges of scaling such a system are the individual addressing of arbitrary subsets of ions and controlling the growing complexity of motional mode interactions as the number of qubits increases or when the gates are performed faster. Traditional entangling quantum gates between ion qubits use laser pulses to couple the qubit states to the collective motion of the crystal, thereby generating a spin-spin interaction that can produce entanglement between selected qubits. The intrinsic limitations on the performance of gates using this method can be alleviated by applying optimally shaped pulses instead of pulses with constant amplitude. This thesis explains the theory behind this pulse shaping scheme and how it is implemented on a chain of Yb ions held in a linear radiofrequency `Paul' trap. Several experiments demonstrate the technique in chains of two, three, and five ions using various types of pulse shapes. A tightly focused individual addressing beam allows us to apply the entangling gates to a target pair of ions, and technical issues related to such tight focusing are discussed. Other advantages to the pulse shaping scheme include a robustness against detuning errors and the possibility of suppressing undesirable coupling due to optical spillover on neighboring ions. Combined with ion shuttling, we harness these features to perform sequential gates to different qubit pairs in order to create genuine tripartite entangled states and demonstrate the programmable quantum information processing capability of our system

The Synthesis of Azaperylene-9,10-dicarboximides

The syntheses of two azaperylene 9,10-dicarboximides are presented. 1-Aza- and 1,6-diazaperylene 9,10-dicarboximides containing a 2,6-diisopropylphenyl substituent at the N-imide position were synthesized in two steps starting from naphthalene and isoquinoline derivatives

Paper_A Comparative Evaluation of Portable X-Ray Fluorescence (pXRF) Analysis on Fly Ash

As coal-fired fossil plants are retiring and lower volumes of Coal Combustion Products (CCPs) are being produced, the generators of Coal Combustion Residual (CCR) producers across the nation are focused on harvesting landfilled and ponded coal ash to maintain the supply for beneficial use markets such as those volumes needed by the concrete mixing industry. To aid in the development of more efficient harvesting strategies, research performed in the emerging Geomaterials Testing and Research Laboratory (GTRL) at the University of Tennessee at Chattanooga College of Engineering and Computer Science and the College of Biology, Geology, and Environmental Science (UTC – CECS & BGE) in collaboration with the Tennessee Valley Authority (TVA). The first of such research effort is to evaluate the potential use of portable X-Ray Fluorescence (pXRF) instrumentation, criteria, and methods to perform quantitative chemical composition analysis as an effective tool and technique for the characterization of CCRs to assess their potential use as CCPs. This report documents the progress towards using such highly mobile XRF instrumentation, as we determined the time for analyses and investigated calibration criteria that are specific to fly ash materials’ unique chemical composition. Here we present the correlation of data obtained by a pXRF to previously analyzed Inductively Coupled Plasma – Optical Emission Spectrometry (ICP-OES) data using the default (non-calibrated) settings of the pXRF and a fly ash calibration. We also demonstrate the repeatability of the pXRF on a sample of fly ash to further support the application of the instrument. The efforts within this study amount to a proof-of-concept worthy to continue testing the pXRF as an instrument to facilitate analysis on large quantities of in-situ CCRs that is fit for the purpose of determining potentially harvestable materials for beneficial use (CCPs)

Standing in the Shadows of Obesity: The Local Food Environment and Obesity in Detroit

Much of the literature examining associations between local food environments and obesity fail to consider whether or not respondents actually utilise the food stores around them. Drawing on survey data, this study examines the relationships between the neighbourhood food environment, mobility and obesity among residents from the lower eastside neighbourhoods of Detroit, Michigan. Certain dimensions of the local food environment are found to contribute to obesity, but these dimensions occur at different scales. Residents who rely on their immediate neighbourhood food environment have a higher likelihood of being obese than residents who do not utilise the stores around them. At a broader level, lower eastside Detroit residents with a greater concentration of fast food establishments around them have a higher possibility of being obese than residents with fewer fast food restaurants around them. The salience of the fast food environment warrants additional attention in terms of public health interventions.Peer Reviewedhttps://deepblue.lib.umich.edu/bitstream/2027.42/139092/1/tesg12227.pdfhttps://deepblue.lib.umich.edu/bitstream/2027.42/139092/2/tesg12227_am.pd

Functional phases and angular momentum characteristics of Tkatchev and Kovacs

Understanding the technical requirements and underlying biomechanics of complex release and re-grasp skills on high bar allows coaches and scientists to develop safe and effective training programmes. The aim of this study was to examine the differences in the functional phases between the Tkatchev and Kovacs skills and to explain how the angular momentum demands are addressed. Images of 18 gymnasts performing 10 Tkatchevs and 8 Kovacs at the Olympic Games were recorded (50 Hz), digitised and reconstructed (3D Direct Linear Transformation). Orientation of the functional phase action, defined by the rapid flexion to extension of the shoulders and extension to flexion of the hips as the performer passed through the lower vertical, along with shoulder and hip angular kinematics, angular momentum and key release parameters (body angle, mass centre velocity and angular momentum about the mass centre and bar) were compared between skills. Expected differences in the release parameters of angle, angular momentum and velocity were observed and the specific mechanical requirement of each skill were highlighted. Whilst there were no differences in joint kinematics, hip and shoulder functional phase were significantly earlier in the circle for the Tkatchev. These findings highlight the importance of the orientation of the functional phase in the preceding giant swing and provide coaches with further understanding of the critical timing in this key phase

Beyond megadrought and collapse in the Northern Levant: The chronology of Tell Tayinat and two historical inflection episodes, around 4.2ka BP, and following 3.2ka BP

There has been considerable focus on the main, expansionary, and inter-regionally linked or ‘globalising’ periods in Old World pre- and proto-history, with a focus on identifying, analyzing and dating collapse at the close of these pivotal periods. The end of the Early Bronze Age in the late third millennium BCE and a subsequent ‘intermediate’ or transitional period before the Middle Bronze Age (~2200–1900 BCE), and the end of the Late Bronze Age in the late second millennium BCE and the ensuing period of transformation during the Early Iron Age (~1200–900 BCE), are key examples. Among other issues, climate change is regularly invoked as a cause or factor in both cases. Recent considerations of “collapse” have emphasized the unpredictability and variability of responses during such periods of reorganization and transformation. Yet, a gap in scholarly attention remains in documenting the responses observed at important sites during these ‘transformative’ periods in the Old World region. Tell Tayinat in southeastern Turkey, as a major archaeological site occupied during these two major ‘in between’ periods of transformation, offers a unique case for comparing and contrasting differing responses to change. To enable scholarly assessment of associations between the local trajectory of the site and broader regional narratives, an essential preliminary need is a secure, resolved timeframe for the site. Here we report a large set of radiocarbon data and incorporate the stratigraphic sequence using Bayesian chronological modelling to create a refined timeframe for Tell Tayinat and a secure basis for analysis of the site with respect to its broader regional context and climate history

Photoluminescent Energy Transfer from Poly(phenyleneethynylene)s to Near-Infrared Emitting Fluorophores

Photoluminescent energy transfer was investigated in conjugated polymer-fluorophore blended thin films. A pentiptycene-containing poly(phenyleneethynylene) was used as the energy donor, and 13 fluorophores were used as energy acceptors. The efficiency of energy transfer was measured by monitoring both the quenching of the polymer emission and the enhancement of the fluorophore emission. Near-infrared emitting squaraines and terrylenes were identified as excellent energy acceptors. These results, where a new fluorescent signal occurs in the near-infrared region on a completely dark background, offer substantial possibilities for designing highly sensitive turn-on sensors.National Institute of General Medical Sciences (U.S.) (F32GM086044)Massachusetts Institute of Technology. Institute for Soldier Nanotechnologies (DAAD-19-02-0002