20 research outputs found
Transient dynamics of a superconducting nonlinear oscillator
We investigate the transient dynamics of a lumped-element oscillator based on
a dc superconducting quantum interference device (SQUID). The SQUID is shunted
with a capacitor forming a nonlinear oscillator with resonance frequency in the
range of several GHz. The resonance frequency is varied by tuning the Josephson
inductance of the SQUID with on-chip flux lines. We report measurements of
decaying oscillations in the time domain following a brief excitation with a
microwave pulse. The nonlinearity of the SQUID oscillator is probed by
observing the ringdown response for different excitation amplitudes while the
SQUID potential is varied by adjusting the flux bias. Simulations are performed
on a model circuit by numerically solving the corresponding Langevin equations
incorporating the SQUID potential at the experimental temperature and using
parameters obtained from separate measurements characterizing the SQUID
oscillator. Simulations are in good agreement with the experimental
observations of the ringdowns as a function of applied magnetic flux and pulse
amplitude. We observe a crossover between the occurrence of ringdowns close to
resonance and adiabatic following at larger detuning from the resonance. We
also discuss the occurrence of phase jumps at large amplitude drive. Finally,
we briefly outline prospects for a readout scheme for superconducting flux
qubits based on the discrimination between ringdown signals for different
levels of magnetic flux coupled to the SQUID.Comment: 15 pages, 9 figure
Microstrip superconducting quantum interference device amplifiers with submicron Josephson junctions: enhanced gain at gigahertz frequencies
We present measurements of an amplifier based on a dc superconducting quantum
interference device (SQUID) with submicron Al-AlOx-Al Josephson junctions. The
small junction size reduces their self-capacitance and allows for the use of
relatively large resistive shunts while maintaining nonhysteretic operation.
This leads to an enhancement of the SQUID transfer function compared to SQUIDs
with micron-scale junctions. The device layout is modified from that of a
conventional SQUID to allow for coupling signals into the amplifier with a
substantial mutual inductance for a relatively short microstrip coil.
Measurements at 310 mK exhibit gain of 32 dB at 1.55 GHz.Comment: Version with high resolution figures at:
http://physics.syr.edu/~bplourde/bltp-publications.ht
Ultrasound attenuation and a P-B-T phase diagram of superfluid 3He in 98% aerogel
Longitudinal sound attenuation measurements in superfluid 3He in 98% aerogel
were conducted at pressures between 14 and 33 bar and in magnetic fields up to
4.44 kG. The temperature dependence of the ultrasound attenuation in the A-like
phase was determined for the entire superfluid region exploiting the field
induced meta-stable A-like phase at the highest field. In the lower field, the
A-B transition in aerogel was identified by a smooth jump in attenuation on
both cooling and warming. Based on the transitions observed on warming, a phase
diagram as a function of pressure (P), temperature (T) and magnetic field (B)
is constructed. We find that the A-B phase boundary in aerogel recedes in a
drastically different manner than in bulk in response to an increasing magnetic
field. The implications of the observed phase diagram are discussed.Comment: 9 pages, 13 figures, accepted to PR
An update on Cention N: An aesthetic direct bulk-fill restorative material
The demand for aesthetic restorative materials has increased in recent years. Glass ionomer cements (GIC), their modifications, and various composite restorative materials have been developed as direct tooth-coloured restorative materials. However, none of these materials can be compared to the properties of amalgam restorative materials. Recently, a new direct tooth-coloured, bulk-fill, and aesthetic restorative material, Cention N, was developed. This material is easy to handle and has properties similar to those of type-IX GIC. This article provides an update on the composition and properties of Cention N restorative material
Microstrip Superconducting Quantum Interference Device Amplifiers with Submicron Josephson Junctions: Enhanced Gain at Gigahertz Frequencies
We present measurements of an amplifier based on a dc superconducting quantum interference device (SQUID) with submicron Al-AlOx-Al Josephson junctions. The small junction size reduces their self-capacitance and allows for the use of relatively large resistive shunts while maintaining nonhysteretic operation. This leads to an enhancement of the SQUID transfer function compared to SQUIDs with micron-scale junctions. The device layout is modified from that of a conventional SQUID to allow for coupling signals into the amplifier with a substantial mutual inductance for a relatively short microstrip coil. Measurements at 310 mK exhibit gain of 32 dB at 1.55 GHz
Orbital glass and spin glass states of 3He-A in aerogel
Glass states of superfluid A-like phase of 3He in aerogel induced by random
orientations of aerogel strands are investigated theoretically and
experimentally. In anisotropic aerogel with stretching deformation two glass
phases are observed. Both phases represent the anisotropic glass of the orbital
ferromagnetic vector l -- the orbital glass (OG). The phases differ by the spin
structure: the spin nematic vector d can be either in the ordered spin nematic
(SN) state or in the disordered spin-glass (SG) state. The first phase (OG-SN)
is formed under conventional cooling from normal 3He. The second phase (OG-SG)
is metastable, being obtained by cooling through the superfluid transition
temperature, when large enough resonant continuous radio-frequency excitation
are applied. NMR signature of different phases allows us to measure the
parameter of the global anisotropy of the orbital glass induced by deformation.Comment: 7 pages, 6 figures, Submitted to Pis'ma v ZhETF (JETP Letters
L-Proline as an efficient catalyst for synthesis of N-heterocyclic chalcones as potential antibacterial agents
855-859The condensation of 4-hydroxy-3-acetyl-1H-quinoline-2-one 1 and substitutedbenzaldehydes 2a-i
in DMSO solution at room temperature yields quinolone chalcone derivatives 3a-i. l-Proline
has been found to be an efficient catalyst for this condensation between 1 and 2. Only 5 mol% of the catalyst is necessary to achieve good yields
of the products. Reactions proceed smoothly with variations of the
substituents. 1 itself is
synthesized by the acylation of commercially available methyl anthranilate 4 with acetoacetic ester 5 in refluxing xylene and subsequent
Dieckman intramolcular cyclization of the intermediary 2-methoxycarbonylanilide
6
ELECTROSPUN NANOFIBROUS WOUND DRESSINGS: A REVIEW ON CHITOSAN COMPOSITE NANOFIBERS AS POTENTIAL WOUND DRESSINGS
Advancements in topical wound dressings led to the development of products to protect the wound and facilitate addressing special issues in healing and non-healing wounds. Rapidly growing interest in nanofiber research is leading to the development of potential candidates for wound dressing applications. Electrospinning nanofibers have been considered one of the effective materials in development of scaffolds for tissue engineering applications. Nanofibers mimic the extracellular matrix with their structural similarities, high surface area, and porosity, thereby enabling the effective delivery of antimicrobial agents in the wound milieu. Chitosan, an excellent biopolymer, is offering versatile applications as electrospun nanofibers due to the presence of its inherent properties like nontoxicity, biodegradability, biocompatibility, and antimicrobial nature, as well as its efficiency towards re‐epithelialization and regeneration of the granular layer of the wounds. The current review discusses the design and strategies used in the development of electrospun chitosan nanofibers, as well as the limitations of these strategies. This article provides the most recent information on the fabrication of chitosan composite nanofibrous materials and their applications for wound healing
Simultaneous Wireless Power and Data Transfer in Different Applications
In Modern Era, the demand for wireless technology has surged exponentially, promising enhanced living comfort and safety. Simultaneous Wireless Power and Data Transfer (SWPDT) has emerged as a critical area of study, finding applications in electric vehicles, underwater autonomous vehicles, and biomedical implants. This technology facilitates real-time monitoring while supplying power, eliminating the need for bulky cables and conventional power sources. Hence this paper addresses the state-of-art of SWPDT in different applications This comprehensive review covers various SWPDT implementation methods for applications like electric vehicles, biomedical implants, and autonomous underwater vehicles. Different techniques for implementation of SWPDT using inductive links and its design recommendations