Millimeter-scale ultrathin suspended metasurface integrated high-finesse optomechanical cavity.

A typical optomechanical system is a cavity with one movable mirror and one fixed mirror. However, this configuration has been considered incapable of integrating sensitive mechanical elements while maintaining high cavity finesse. Although the membrane-in-the-middle solution seems to be able to overcome this contradiction, it introduces additional components that will lead to unexpected insertion loss, resulting in reduced cavity quality. Here we propose a Fabry-Perot optomechanical cavity composed of an ultrathin suspended Si3N4 metasurface and a fixed Bragg grating mirror, with a measured finesse up to 1100. Transmission loss of this cavity is very low as the reflectivity of this suspended metasurface tends to unity around 1550 nm. Meanwhile, the metasurface has a millimeter-scale transverse dimension and a thickness of only 110 nm, which guarantees a sensitive mechanical response and low cavity diffraction loss. Our metasurface-based high-finesse optomechanical cavity has a compact structure, which facilitates the development of quantum and integrated optomechanical devices.

Estimation of Personal Environment Via Fingertip Microbiome and Mobile Phone Surfaces.

BACKGROUND: Fingerprints can serve to identify individuals, but fingerprint quality may be deteriorated, even to the point of eliminating fingerprints, due to the external environment. OBJECTIVE: Poor fingerprint quality cannot be effectively used to identify individuals; hence, the need for other methods. MATERIALS AND METHODS: We investigated the utility of bacterial communities and the only microorganisms present in the sample to identify internal and external factors in individuals. Samples included eight participants' fingerprints and their mobile phone surfaces. Bacterial DNA in the samples was sequenced using next-generation sequencing to target the V3-V4 region in the 16S ribosomal RNA gene. The QIIME program was used to perform a taxonomic assignment and alpha diversity and beta diversity analyses based on the sequence data. RESULTS: Until now, personal identification has only relied on microbial communities. However, this study identified microbial differences according to Korean mobile phones, fingertips, or gender, and confirmed the possibility of characterization of samples when it was difficult to identify individuals by the microbial community. The biodiversity and composition of individual bacterial communities were affected by internal and external environments. Bacteria from individuals and mobile phones were shared due to contact between mobile phone surfaces and fingertips. Of the eight Koreans, six of the fingertips and mobile phone samples matched each other for personal identification. CONCLUSIONS: This study confirmed that the bacteria from an individual could be matched with the contact object and could be used as forensic evidence. Such bacterial profiling of individuals may confer forensic evidence and serve as a basis for improving the accuracy of forensic verification.

Tetrakis(4-sulfonatophenyl)porphyrin-directed assembly of gold nanocrystals: tailoring the plasmon coupling through controllable gap distances.

It is known that universality and controllability over nanocrystal orientation must be accomplished to facilitate the potential applications of metal nanocrystals in the areas of photonics, electronics, and optics. The facile fabrication of linear chains of Au nanorods and bifurcated junctions of nanorods/nanospheres is achieved via the crosslinking of H-type tetrakis(4-sulfonatophenyl)porphyrin aggregates in solution. The tuning of the plasmon coupling between the Au nanocrystals is demonstrated by varying the porphyrin concentration and thus the interparticle gap distances. Finite-difference time-domain calculations show that the red shift of the plasmon band exhibits a nearly exponential decay with increasing interparticle gap distances, thus giving rise to a "plasmon ruler equation." The gap distances determined according to this equation agree well with the experimental observations and further confirm the porphyrin-directed assembly process. The interaction mechanism between the Au nanorods and porphyrins is further investigated by a biological procedure using the dark-field light scattering technique.

Wound Healing Effect of Nonthermal Atmospheric Pressure Plasma Jet on a Rat Burn Wound Model: A Preliminary Study.

Worldwide, an estimated 6 million patients seek medical attention for burns annually. Various treatment methods and materials have been investigated and developed to enhance burn wound healing. Recently, a new technology, plasma medicine, has emerged to offer new solutions in wound care. As the development of plasma medicine has shown benefit in wound healing, we aimed to assess the effects of plasma medicine on burn wounds. To investigate the effectiveness of a nonthermal atmospheric pressure plasma jet (NAPPJ) for burn wound treatment on a brass comb burn wound rat model. Burn wounds were made by applying a preheated brass comb (100°C) for 2 minutes, which resulted in four full-thickness burn wounds separated by three interspaces. Interspaces were exposed to NAPPJ treatment for 2 minutes and morphological changes and neutrophil infiltration were monitored at 0, 4, and 7 days post-wounding. The percentage of necrotic interspace was higher in the control group than in the plasma-treated group (51.8 ± 20.5% vs 31.5 ± 19.0%, P < .001). Moreover, the exposure of interspace to NAPPJ greatly reduced the number of infiltrating neutrophils. In addition, the percentage of interspace that underwent full-thickness necrosis in the plasma-treated group was smaller than that in the control group (28% vs 67%). NAPPJ exposure on interspaces has a positive effect on burn wounds leading to wound healing by reducing burn injury progression.

Visual colorimetric detection of berberine hydrochloride with silver nanoparticles.

A visual colorimetric method for the detection of berberine hydrochloride was proposed in this contribution based on the color change caused by the aggregation of silver nanoparticles (AgNps). It was found that citrate-capped AgNps dispersed in water owing to the electrostatic repulsion from each other by the negative charged surface, presenting a bright yellow color. However, the presence of positively charged berberine could induce the aggregation of citrate-capped AgNps, resulting in color change from yellow to green and even to blue depending on the concentration of berberine. Under the optimum condition investigated with UV-vis absorption and light scattering technique, berberine hydrochloride from 0.05 micromol l(-1) to 0.4 micromol l(-1) could be visually detected based on the color alteration of the AgNps suspension.

End-to-end assembly of gold nanorods by means of oligonucleotide-mercury(II) molecular recognition.

We report a novel, simple, highly selective and versatile approach for the end-to-end assembly of gold nanorods (GNRs) by means of the specific molecular recognition between thymine-rich (T-rich) oligonucleotides and mercury(II).

A visual detection of hydrogen peroxide on the basis of Fenton reaction with gold nanoparticles.

Nowadays, hydrogen peroxide (H(2)O(2)) has attracted more and more attentions in biochemical fields owing to its important role in biological systems. In this contribution, we propose a novel assay for the detection of H(2)O(2) based on the cleavage of ssDNA on gold nanoparticles (AuNPs). It was known that AuNPs could be stable in the presence of single-stranded DNA (ssDNA) which prevents the salt-induced aggregation of AuNPs in solution owing to the electrostatic repulsion. However, hydroxyl radical (HO*) generated from Fenton reaction could cleave the ssDNA and induce the aggregation of AuNPs. Therefore, color change from red to blue owing to the plasmon resonance absorption (PRA) of AuNPs can be observed by the naked eyes and enhancement of plasmon resonance light scattering could be measured with a common spectrofluorometer. The values of A(650)/A(520) of the PRA band were found to be linearly proportional to the concentration of H(2)O(2) in the range of 2.0 x 10(-7) to 8.0 x 10(-6) mol L(-1) with the limit of determination (LOD) being 40 nmol L(-1) (S/N=3), and thus the content of H(2)O(2) in rat encephalon extraction could be successfully detected with the recovery in the range of 98-103%.

Controllable preparation of metal nanoparticle/carbon nanotube hybrids as efficient dark field light scattering agents for cell imaging.

We report a novel strategy to fabricate metal nanoparticle/carbon nanotube hybrids with unique plasmon properties as well as biocompatibility and further apply them as efficient dark field light scattering agents for cancer cell imaging.