The effect of alkali niobate addition on the phase stability and dielectric properties of Pb (Zn13 Nb23) O3 based ceramic

While Pb (Zn13 Nb23) O3 -PbTi O3 (PZN-PT) single crystals have shown superior ferroelectric properties, less scientific and technical interests have been placed on PZN-PT polycrystalline ceramics due to their poor thermodynamic stability and the difficult processing conditions. Here, we stabilized the PZN-PT based ceramics by adding alkali niobates such as NaNb O3 (NN) and KNb O3 (KN) and investigated their structure and dielectric properties. Two stabilization mechanisms are suggested in alkali niobate added PZN-PT ceramics, increased tolerance factor and enhanced electronegativity difference. KN stabilized the perovskite structure of PZN-PT based ceramics more effectively than NN. Both PZN-PT-KN and PZN-PT-NN ceramics showed the typical behavior of relaxor ferroelectrics. The temperature of maximum dielectric constant of PZN-PT-NN was slightly higher than that of the PZN-PT-KN, which was explained by the difference in ionic size and B -site ordering. © 2007 American Institute of Physics

Perception and Reaction to Floor Impact Noise in Apartment Buildings: A Qualitative Approach

This study used grounded theory to understand how apartment building residents perceive and react to floor impact noise from upstairs. In-depth interviews with a heterogeneous group of 14 participants were conducted, and the acquired data were analysed to develop a conceptual model for describing perception and reaction to floor impact noise. It was found that floor impact noise had diverse sources, with the majority originating from footsteps. The participants negatively perceived the noise as annoying and disturbing, and sleep disturbance was reported the most frequently. Cognitive and avoidant coping strategies were initially adopted, and complaints were only thereafter registered if the noise persisted. It was also observed that exposure to the noise led to self-reported health problems and concerns. The developed conceptual model highlights potential intervention measures for controlling noise perception and reactions to floor impact noise

Development and Validation of Mechatronic Systems for Image-Guided Needle Interventions and Point-of-Care Breast Cancer Screening with Ultrasound (2D and 3D) and Positron Emission Mammography

The successful intervention of breast cancer relies on effective early detection and definitive diagnosis. While conventional screening mammography has substantially reduced breast cancer-related mortalities, substantial challenges persist in women with dense breasts. Additionally, complex interrelated risk factors and healthcare disparities contribute to breast cancer-related inequities, which restrict accessibility, impose cost constraints, and reduce inclusivity to high-quality healthcare. These limitations predominantly stem from the inadequate sensitivity and clinical utility of currently available approaches in increased-risk populations, including those with dense breasts, underserved and vulnerable populations. This PhD dissertation aims to describe the development and validation of alternative, cost-effective, robust, and high-resolution systems for point-of-care (POC) breast cancer screening and image-guided needle interventions. Specifically, 2D and 3D ultrasound (US) and positron emission mammography (PEM) were employed to improve detection, independent of breast density, in conjunction with mechatronic and automated approaches for accurate image acquisition and precise interventional workflow. First, a mechatronic guidance system for US-guided biopsy under high-resolution PEM localization was developed to improve spatial sampling of early-stage breast cancers. Validation and phantom studies showed accurate needle positioning and 3D spatial sampling under simulated PEM localization. Subsequently, a whole-breast spatially-tracked 3DUS system for point-of-care screening was developed, optimized, and validated within a clinically-relevant workspace and healthy volunteer studies. To improve robust image acquisition and adaptability to diverse patient populations, an alternative, cost-effective, portable, and patient-dedicated 3D automated breast (AB) US system for point-of-care screening was developed. Validation showed accurate geometric reconstruction, feasible clinical workflow, and proof-of-concept utility across healthy volunteers and acquisition conditions. Lastly, an orthogonal acquisition and 3D complementary breast (CB) US generation approach were described and experimentally validated to improve spatial resolution uniformity by recovering poor out-of-plane resolution. These systems developed and described throughout this dissertation show promise as alternative, cost-effective, robust, and high-resolution approaches for improving early detection and definitive diagnosis. Consequently, these contributions may advance breast cancer-related equities and improve outcomes in increased-risk populations and limited-resource settings

CMS endcap RPC gas gap production for upgrade

The CMS experiment will install a RE4 layer of 144 new Resistive Plate Chambers (RPCs) on the existing york YE3 at both endcap regions to trigger high momentum muons from the proton-proton interaction. In this paper, we present the detailed procedures used in the production of new RPC gas gaps adopted in the CMS upgrade. Quality assurance is enforced as ways to maintain the same quality of RPC gas gaps as the existing 432 endcap RPC chambers that have been operational since the beginning of the LHC operation

Physical origin of residual thermal stresses in a multilayer ceramic capacitor

The physical origin of the residual stresses developed in the ceramic layer of the active region in a multilayer ceramic capacitor was numerically investigated. The compressive in-plane stress components σ11 and σ22 originate without regard to the presence of the margins but rather from the difference in in-plane thermal shrinkage between ceramic and metal electrode. The out-of-plane stress component σ33 physically originates mainly through the presence of the housing margin; the presence of the lateral margin is a minor source: the more ceramic-rich margins hinder the apparent vertical shrinkage of the active region to yield tensile σ33. © 2007 American Institute of Physics

Effect of amorphous Si quantum-dot size on 1.54 μm luminescence of Er

The role of the size of amorphous silicon quantum dots in the Er luminescence at 1.54 μm was investigated. As the dot size was increased, more Er ions were located near one dot due to its large surface area and more Er ions interacted with other ones. This Er-Er interaction caused a weak photoluminescence intensity, despite the increase in the effective excitation cross section. The critical dot size needed to take advantage of the positive effect on Er luminescence is considered to be about 2.0 nm, below which a small dot is very effective in the efficient luminescence of Er. © 2005 The Electrochemical Society. All rights reserved

First report of Perkinsus honshuensis in the variegated carpet shell clam Ruditapes variegatus in Korea

The recent discovery of Perkinsus honshuensis, a new Perkinsus species infecting Manila clams Ruditapes philippinarum (Sowerby, 1852), in Japan, suggested that, based on proximity, P. honshuensis could also be in Korean waters, where to date, P. olseni was believed to be the only Perkinsus species present. Perkinsus sp. infections consistently occurred among Ruditapes variegatus clams on a pebble beach on Jeju Island, off the south coast of Korea. The typical \u27signet ring\u27 morphology of the parasite was observed in the connective tissue of the digestive gland, and infection intensity was comparatively low (3.3 x 10(3) +/- 1.2 x 10(4) to 1.3 x 10(4) +/- 6.1 x 10(4) cells g(-1) gill weight). Further DNA analyses of internal transcribed spacer (ITS-1, 5.8S and ITS-2) and non-transcribed spacer (NTS) regions of the parasite showed 98.9-99.8 and 98.5-99.5% similarity to those of P. honshuensis from Japan, respectively. Phylogenetic analyses using ITS and NTS sequences indicated that Perkinsus sp. from Jeju formed a highly supported clade with P. honshuensis. This is the first report of P. honshuensis infections in clams in Korean waters and the first report of R. variegatus as a host for that parasite

1000 nm tunable acousto-optic filter based on photonic crystal fiber

Author name used in this publication: W. JinAuthor name used in this publication: J. Ju2007-2008 > Academic research: refereed > Publication in refereed journalVersion of RecordPublishe

Obesity-induced DNA hypermethylation of the adiponectin gene mediates insulin resistance

Adiponectin plays a key role in the regulation of the whole-body energy homeostasis by modulating glucose and lipid metabolism. Although obesity-induced reduction of adiponectin expression is primarily ascribed to a transcriptional regulation failure, the underlying mechanisms are largely undefined. Here we show that DNA hypermethylation of a particular region of the adiponectin promoter suppresses adiponectin expression through epigenetic control and, in turn, exacerbates metabolic diseases in obesity. Obesity-induced, pro-inflammatory cytokines promote DNMT1 expression and its enzymatic activity. Activated DNMT1 selectively methylates and stimulates compact chromatin structure in the adiponectin promoter, impeding adiponectin expression. Suppressing DNMT1 activity with a DNMT inhibitor resulted in the amelioration of obesity-induced glucose intolerance and insulin resistance in an adiponectin-dependent manner. These findings suggest a critical role of adiponectin gene epigenetic control by DNMT1 in governing energy homeostasis, implying that modulating DNMT1 activity represents a new strategy for the treatment of obesity-related diseases.published_or_final_versio

Continuous and reversible tuning of the disorder-driven superconductor-insulator transition in bilayer graphene

The influence of static disorder on a quantum phase transition (QPT) is a fundamental issue in condensed matter physics. As a prototypical example of a disorder-tuned QPT, the superconductor-insulator transition (SIT) has been investigated intensively over the past three decades, but as yet without a general consensus on its nature. A key element is good control of disorder. Here, we present an experimental study of the SIT based on precise in-situ tuning of disorder in dual-gated bilayer graphene proximity-coupled to two superconducting electrodes through electrical and reversible control of the band gap and the charge carrier density. In the presence of a static disorder potential, Andreev-paired carriers formed close to the Fermi level in bilayer graphene constitute a randomly distributed network of proximity-induced superconducting puddles. The landscape of the network was easily tuned by electrical gating to induce percolative clusters at the onset of superconductivity. This is evidenced by scaling behavior consistent with the classical percolation in transport measurements. At lower temperatures, the solely electrical tuning of the disorder-induced landscape enables us to observe, for the first time, a crossover from classical to quantum percolation in a single device, which elucidates how thermal dephasing engages in separating the two regimes.1132Ysciescopu