Search

Abstract:  Currently, around 50% (~178 million) of all Americans are missing at least 1 tooth, with 12% (~40 million) of Americans missing all of their teeth. Dental implants are a common solution to this issue; titanium is the leading material of choice. Zirconia ceramic dental implants are a suitable replacement for titanium, but are often criticized for their brittleness. By developing a tantalum functional gradient coating, we hope to increase the viability of zirconia ceramic materials for dental implants. Two sets of material were chosen to test the proprietary BruxZir tantalum ion solution: yttria stabilized zirconia (3Y-TZP) and alumina toughened zirconia (ATZ). Solutions with varying concentrations of 0%, 10%, 15%, and 30% weight percent tantalum were prepared, and the ceramic samples were coated and sintered. Each sample was analyzed through various characterization methods, including SEM, EDS, XRD, nanoindentation, and Raman spectroscopy to observe how the solution impacted each sample’s microstructure and mechanical properties. Although our results are still in progress, we found evidence of an inverse relationship between tantalum concentration and grain size.

Passive daytime radiative cooling that could provide sub-ambient cooling emerges as a promising technology to reduce household energy consumption. Nonetheless, prevailing studies are predominantly focused on surface cooling, often overlooking its adaptability to enclosed spaces with active cooling technologies. Here we present a multilayer radiative cooling film (J-MRC) with Janus optical properties in the mid-infrared region, consisting of the nanoporous polyethylene films, the polyethylene oxide film, and silver nanowires. The top side of the J-MRC functions as a conventional radiative cooling material to supply sub-ambient surface cooling, while the bottom side with low mid-infrared emissivity transfers limited heat via thermal radiation to the low-temperature enclosures. Our experiments validate that the J-MRC possesses an enhanced space cooling performance in comparison to the conventional radiative cooling film. This work provides a valuable design concept for radiative cooling materials, thereby expanding their practical scenarios and contributing to reduce the carbon emission.

High-precision detection of electric charge is critical for physical, chemical, and biological measurements. Nanophotonic optomechanical system confines the optical field at the nanoscale and enables a strong interaction between optical cavity and mechanical resonator. Its high optical quality factor cavity and strong optomechanical coupling are promising for precision sensing applications. Here an integrated optomechanical electrometer is proposed for the electric charge sensing using a zipper cavity with a suspended photonic crystal nanobeam (PCN) acting as a movable mechanical resonator. As the electrostatic force arising from the electric voltage to be measured interacts with the mechanical motion of the movable PCN and modulates its resonance through electrostatic stiffening effect, optomechanical coupling transduces the mechanical motion to the optical field with enhanced sensitivity. The resonance shift of the mechanical resonator can be monitored to detect the electric voltage with a sensitivity of 0.007 Hz/mV2$\mathrm{Hz}/\mathrm{m}{\mathrm{V}}^{2}$. Moreover, the sensing performance can be further enhanced with the operation of the optomechanical electrometer in the self-sustained oscillation above threshold power. Owing to the narrow-linewidth of detector radio frequency (RF) spectrum with a large peak-to-noise floor ratio (up to 73.5 dB), the enhanced electrical sensitivity of 0.014 Hz/mV2$\mathrm{Hz}/\mathrm{m}{\mathrm{V}}^{2}$ is achieved with a high resolution of 1.37 mV2Hz−1/2$1.37\,\mathrm{m}{\mathrm{V}}^{2}\mathrm{H}{\mathrm{z}}^{-1/2}$. A theoretical minimal detectable electrostatic charge is calculated as 1.33×10−2 eHz−1/2$1.33{\times}{10}^{-2}\,\mathrm{eH}{\mathrm{z}}^{-1/2}$ by converting the measured electric voltage versus RF shift to an approximatively linear relationship. This on-chip optomechanical electrometry scheme provides a powerful solution to the ultrasensitive determination of charged nanoparticles in biological and chemical applications.

Medicago truncatula is a key model plant for studying legume plants, particularly alfalfa (Medicago sativa), due to its well-defined genetic background. Plant-specific GASA (Gibberellic Acid Stimulated Arabidopsis) genes play various roles in plant growth and development, abiotic stress, and hormone responses. However, limited information is available on GASA research in Medicago. In this study, 26 MtGASAs were identified and analyzed for its structure, evolution, and expressions. Sequence alignments and phylogeny revealed that 26 MtGASAs containing conserved GASA domains were classified into three clades. The chromosomal locations and gene synteny revealed segmental and tandem repetition evolution. Analysis of cis-regulatory elements indicates that family members likely influence various hormone signaling pathways and stress-related mechanisms. Moreover, the RNA-seq and qRT-PCR analyses revealed that 26 MtGASAs were extensively involved in abiotic stresses and hormone responses. Notably, seven MtGASA genes (MtGASA1, 10, 12, 17, 23, 25 and 26) were all dramatically activated by NaCl and Mannitol treatments, and four MtGASAs (MtGASA7, 10, 23 and 24) were significant activated by GA3, PBZ, ABA, and MeJA treatments. Collectively, this study is the first to identify and describe GASA genes in Medicago on a genome-wide scale. The results establish a basis for functional characterization, showing that these proteins are essential in responding to various abiotic stresses and hormonal signals. [ABSTRACT FROM AUTHOR]