2,332 research outputs found
Complex DNA Nanostructures from Oligonucleotide Ensembles
The first synthetic DNA nanostructures were created by self-assembly of a small number of oligonucleotides. Introduction of the DNA origami method provided a new paradigm for designing and creating two- and three-dimensional DNA nanostructures by folding a large single-stranded DNA and ‘stapling’ it together with a library of oligonucleotides. Despite its power and wide-ranging implementation, the DNA origami technique suffers from some limitations. Foremost among these is the limited number of useful single-stranded scaffolds of biological origin. This report describes a new approach to creating large DNA nanostructures exclusively from synthetic oligonucleotides. The essence of this approach is to replace the single-stranded scaffold in DNA origami with a library of oligonucleotides termed “scaples” (scaffold staples). Scaples eliminate the need for scaffolds of biological origin and create new opportunities for producing larger and more diverse DNA nanostructures as well as simultaneous assembly of distinct structures in a “single-pot” reaction
Synthesis of neutral nickel catalysts for ethylene polymerization – the influence of ligand size on catalyst stability
A facile synthesis of nickel salicylaldimine complexes with labile dissociating ligands is described. In addition to producing highly active ethylene polymerization catalysts, important insights into the effect of ligand size on catalyst stability and information on the mechanism of polymerization are provided
A Programmable True Random Number Generator Using Commercial Quantum Computers
Random number generators (RNG) are essential elements in many cryptographic
systems. True random number generators (TRNG) rely upon sources of randomness
from natural processes such as those arising from quantum mechanics phenomena.
We demonstrate that a quantum computer can serve as a high-quality, weakly
random source for a generalized user-defined probability mass function (PMF).
Specifically, QC measurement implements the process of variate sampling
according to a user-specified PMF resulting in a word comprised of electronic
bits that can then be processed by an extractor function to address
inaccuracies due to non-ideal quantum gate operations and other system biases.
We introduce an automated and flexible method for implementing a TRNG as a
programmed quantum circuit that executes on commercially-available, gate-model
quantum computers. The user specifies the desired word size as the number of
qubits and a definition of the desired PMF. Based upon the user specification
of the PMF, our compilation tool automatically synthesizes the desired TRNG as
a structural OpenQASM file containing native gate operations that are optimized
to reduce the circuit's quantum depth. The resulting TRNG provides multiple
bits of randomness for each execution/measurement cycle; thus, the number of
random bits produced in each execution is limited only by the size of the QC.
We provide experimental results to illustrate the viability of this approach.Comment: 15 pages, 7 figures, SPIE Defense + Commercial Sensing: Quantum
Information Science, Sensing, and Computation X
Automated Synthesis of Quantum Subcircuits
The quantum computer has become contemporary reality, with the first
two-qubit machine of mere decades ago transforming into cloud-accessible
devices with tens, hundreds, or--in a few cases--even thousands of qubits.
While such hardware is noisy and still relatively small, the increasing number
of operable qubits raises another challenge: how to develop the now-sizeable
quantum circuits executable on these machines. Preparing circuits manually for
specifications of any meaningful size is at best tedious and at worst
impossible, creating a need for automation. This article describes an automated
quantum-software toolkit for synthesis, compilation, and optimization, which
transforms classically-specified, irreversible functions to both
technology-independent and technology-dependent quantum circuits. We also
describe and analyze the toolkit's application to three situations--quantum
read-only memories, quantum random number generators, and quantum oracles--and
illustrate the toolkit's start-to-finish features from the input of classical
functions to the output of quantum circuits ready-to-run on commercial
hardware. Furthermore, we illustrate how the toolkit enables research beyond
circuit synthesis, including comparison of synthesis and optimization methods
and deeper understanding of even well-studied quantum algorithms. As quantum
hardware continues to develop, such quantum circuit toolkits will play a
critical role in realizing its potential.Comment: 49 pages, 25 figures, 20 table
The Effects of a High Fat Meal on Blood Flow Regulation during Arm Exercise
A diet high in saturated fats results in endothelial dysfunction and can lead to atherosclerosis, a precursor to cardiovascular disease. Exercise training is a potent stimulus though to mitigate the negative effects of a high saturated fat diet; however, it is unclear how high-saturated fat meal (HSFM) consumption impacts blood flow regulation during a single exercise session.
PURPOSE: This study sought to examine the impact of a single HSFM on peripheral vascular function during an acute upper limb exercise bout.
METHODS: Ten young healthy individuals completed two sessions of progressive handgrip exercise. Subjects either consumed a HSFM (0.84 g of fat/kg of body weight) 4 hours prior or remained fasted before the exercise bout. Progressive rhythmic handgrip exercise (6kg, 12kg, 18kg) was performed for 3 minutes per stage at rate of 1 Hz. The brachial artery (BA) diameter and blood velocity was obtained using Doppler Ultrasound (GE Logiq e) and BA blood flow was calculated with these values.
RESULTS: BA blood flow and flow mediated dilation (normalized for shear rate) during the handgrip exercise significant increased from baseline in all workloads, but no differences were revealed in response to the HSFM consumption.
CONCLUSION: Progressive handgrip exercise augmented BA blood flow and flow mediated dilation in both testing days; however, there was no significant differences following the HSFM consumption. This suggests that upper limb blood flow regulation during exercise is unaltered by a high fat meal in young healthy individuals.https://scholarscompass.vcu.edu/gradposters/1060/thumbnail.jp
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