The quantitative label-free detection of neurotransmitters provides critical clues in understanding neurological functions or disorders. However, the identification of neurotransmitters remains ...challenging for surface-enhanced Raman spectroscopy (SERS) due to the presence of noise. Here, we report spread spectrum SERS (ss-SERS) detection for the rapid quantification of neurotransmitters at the attomolar level by encoding excited light and decoding SERS signals with peak autocorrelation and near-zero cross-correlation. Compared to conventional SERS measurements, the experimental result of ss-SERS shows an exceptional improvement in the signal-to-noise ratio of more than three orders of magnitude, thus achieving a high temporal resolution of over one hundred times. The ss-SERS measurement further allows the attomolar SERS detection of dopamine, serotonin, acetylcholine, γ-aminobutyric acid, and glutamate without Raman reporters. This approach opens up opportunities not only for investigating the early diagnostics of neurological disorders or highly sensitive biomedical SERS applications but also for developing low-cost spectroscopic biosensing applications.
A two-dimensional layered Sb2Se3-based amorphous composite (a–Sb2Se3/C) is synthesized using a simple solid-state ball-milling process, and its potential for Li- and Na-ion batteries is evaluated. Ex ...situ extended X-ray absorption fine structure analyses clearly indicate the electrochemical reaction mechanisms of Sb2Se3 and a–Sb2Se3/C as anodes for Li- and Na-ion batteries. During Li- and Na-insertion, the Sb2Se3 and a–Sb2Se3/C electrodes are converted into the final phases of Li3Sb/Na3Sb and Li2Se/Na2Se, respectively. During Li- and Na-extraction, the Li3Sb/Na3Sb and Li2Se/Na2Se in the Sb2Se3 electrode are converted into Sb and Se, showing a non-recovery reaction, whereas a recovery to the original Sb2Se3 in the a–Sb2Se3/C electrode occurs after full Li and Na extraction. Owing to the interesting conversion/recovery reaction, the a–Sb2Se3/C electrode exhibits excellent electrochemical performance, such as high reversible capacities (Li-ion battery: 662 mAh g−1; Na-ion battery: 407 mAh g−1), a long cycle life with highly reversible capacities (Li-ion battery: 662 mAh g−1 and 1,205 mAh cm−3, respectively, after 100th cycle; Na-ion battery: 378 mAh g−1 and 688 mAh cm−3, respectively, after 50th cycle), and high rate capabilities (Li-ion battery: 623 mAh g−1 and 1,133 mAh cm−3 at 3C; Na-ion battery: 270 mAh g−1 and 492 mAh cm−3 at 2C).
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•A layered Sb2Se3 and its amorphous Sb2Se3/C composite is synthesized simply.•The reaction mechanisms during Li- and Na-insertion/extraction is demonstrated.•The Sb2Se3 had conversion/non-recovery reactions during Li- and Na-reactions.•The Sb2Se3/C had conversion/full-recovery reactions during Li- and Na-reactions.•The amorphous Sb2Se3/C exhibited excellent electrochemical performances.
Biomarkers in tear fluid have attracted much interest in daily healthcare sensing and monitoring. Recently, surface-enhanced Raman scattering (SERS) has enabled highly sensitive label-free detection ...of small molecules. However, a highly stable straightforward tear assay with superior sensitivity is still under development in tear collection and analysis. Here we report a plasmonic Schirmer strip for on-demand, rapid, and simple identification of biomarkers in human tears. The diagnostic strip features gold nanoislands directly and evenly formed on the top surface of cellulose fibers, which maintain a hygroscopic nature for an efficient collection of tear production as well as provide plasmonic enhancement in SERS signals for identification of tear molecules. The uric acid in human tears was quantitatively detected at physiological levels (25–150 μM) by using SERS. The experimental results also clearly reveal a strong linear correlation between uric acid level in both human tears and blood for gouty arthritis diagnosis. This functional paper strip enables noninvasive diagnosis of disease-related biomarkers and healthcare monitoring using human tears.
In this paper, we propose a novel interference alignment (IA) technique for an in-band full-duplex (IBFD) multiple-input multiple-output (MIMO) cellular network where a base station (BS) and user ...equipment (UE) are equipped with multiple antennas, and the local channel state information (CSI) is available at all nodes. Considering a practical IBFD MIMO cellular network, it is assumed that only the BS operates with full-duplex (FD) communication while UE operate in half-duplex (HD) mode. These IBFD networks introduce a new type of interference called cross-link interference (CLI), in which uplink UE affects downlink UE. The proposed IA technique consists of two symmetric IA schemes according to the number of antennas in the uplink and downlink UE, and both schemes effectively mitigate CLI in the IBFD MIMO network. It is worth noting that both IA schemes are adaptively applicable according to the network's quality-of-service (QoS) requirements, such as uplink and downlink traffic demands. Furthermore, we theoretically characterize and prove the achievable sum-degrees-of-freedom (DoF) of the proposed IA technique. Simulation results show that the proposed IA technique significantly improves the sum rate performance compared to conventional HD communications (multi-user MIMO) while achieving the same achievable DoF as the interference-free IBFD MIMO network.
To design a high-performance sodium-ion battery anode, binary zinc phosphides (ZnP2 and Zn3P2) were synthesized by a facile solid-state heat treatment process, and their Na storage characteristics ...were evaluated. The Na reactivity of ZnP2 was better than that of Zn3P2. Therefore, a C-modified ZnP2-based composite (ZnP2-C) was fabricated to achieve better electrochemical performance. To investigate the electrochemical reaction mechanism of ZnP2-C during sodiation/desodiation, various ex situ analytical techniques were employed. During sodiation, ZnP2 in the composite was transformed into NaZn13 and Na3P phases, exhibiting a one-step conversion reaction. Conversely, Zn and P in NaZn13 and Na3P, respectively, were fully recombined to the original ZnP2 phase during desodiation. Owing to the one-step conversion/recombination of ZnP2 in the composite during cycling, the ZnP2-C showed high electrochemical performance with a highly reversible capacity of 883 mA h g–1 after 130 cycles with no capacity deterioration and a fast C-rate capability of 500 mA h g–1 at 1 C and 350 mA h g–1 at 3 C.
This work reports a facile wafer-level fabrication for nanogap-rich gold nanoislands for highly sensitive surface enhanced Raman scattering (SERS) by repeating solid-state thermal dewetting of thin ...gold film. The method provides enlarged gold nanoislands with small gap spacing, which increase the number of electromagnetic hotspots and thus enhance the extinction intensity as well as the tunability for plasmon resonance wavelength. The plasmonic nanoislands from repeated dewetting substantially increase SERS enhancement factor over one order-of-magnitude higher than those from a single-step dewetting process and they allow ultrasensitive SERS detection of a neurotransmitter with extremely low Raman activity. This simple method provides many opportunities for engineering plasmonics for ultrasensitive detection and highly efficient photon collection.
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This study investigated the characteristics of biochars derived using various pine tree residues and pyrolysis temperatures and evaluated their Cd adsorption behaviors. The ...characteristics of pine tree residue biochars (PRBs) were dominantly affected by the pyrolysis temperature, and the optimum pyrolysis temperature for Cd adsorption was 600 °C. The adsorption of Cd by PRBs was divided into two stages: rapid adsorption on the initial boundary layer and slow adsorption by intraparticle diffusion. The Cd adsorption characteristics of all the PRBs were well described by pseudo-second-order and Langmuir isotherm models, and the maximum adsorption capacity was the highest in pine bark biochar (85.8 mg/g). The amounts of the cations released from the mixed pine tree residue biochars (M-PRBs) during Cd adsorption were increased, while the amount of phosphate released was decreased, indicating that exchangeable cations and phosphate on the biochar affected the Cd adsorption. In particular, the amount of Cd removed by the exchangeable cations corresponds to 23.6% of the total adsorption amount. Spectroscopic analyses using FTIR showed that the Cd adsorption on M-PRB was associated with functional groups such as CC, COH and COOH. Overall, the use of biochars derived from pine tree residue as an adsorbent is considered to be effective for both the treatment of wastewater containing heavy metals and the recycling of forest residues.
Ultrasonic transducers facilitate noninvasive biomedical imaging and therapeutic applications. Optoacoustic generation using nanoplasmonic structures provides a technical solution for highly ...efficient broadband ultrasonic transducer. However, bulky and high-cost nanosecond lasers as conventional excitation sources hinder a compact configuration of transducer.
Here, we report a plasmon-enhanced optoacoustic transducer (PEAT) for broadband ultrasound generation, featuring an overdriven pulsed laser diode (LD) and an Ecoflex thin film. The PEAT module consists of an LD, a collimating lens, a focusing lens, and an Ecoflex-coated 3D nanoplasmonic substrate (NPS).
The LD is overdriven above its nominal current and precisely modulated to achieve nanosecond pulsed beam with high optical peak power. The focused laser beam is injected on the NPS with high-density electromagnetic hotspots, which allows for the efficient plasmonic photothermal effect. The thermal expansion of Ecoflex finally generates broadband ultrasound.
The overdriven pulsed LD achieves a maximum optical peak power of 40 W, exceeding the average optical power of 3 W. The
thick Ecoflex-coated NPS exhibits an eightfold optoacoustic enhancement with a fractional
bandwidth higher than 160% and a peak frequency of 2.5 MHz. In addition, the optoacoustic amplitude is precisely controlled by the optical peak power or the laser pulse width. The PEAT-integrated microfluidic chip clearly demonstrates acoustic atomization by generating aerosol droplets at the air-liquid interface.
Plasmon-enhanced optoacoustic generation using PEAT can provide an approach for compact and on-demand biomedical applications, such as ultrasound imaging and lab-on-a-chip technologies.
Phytohormones are central to plant growth and development. Despite the advancement in our knowledge of hormone signaling, downstream targets, and their interactions upon hormones action remain ...largely fragmented, especially at the protein and metabolite levels. With an aim to get new insight into the effects of two hormones, ethylene (ET) and abscisic acid (ABA), this study utilizes an integrated proteomics and metabolomics approach to investigate their individual and combined (ABA+ET) signaling in soybean leaves. Targeting low‐abundance proteins, our previously established protamine sulfate precipitation method was applied, followed by label‐free quantification of identified proteins. A total of 4129 unique protein groups including 1083 differentially modulated in one (individual) or other (combined) treatments were discerned. Functional annotation of the identified proteins showed an increased abundance of proteins related to the flavonoid and isoflavonoid biosynthesis and MAPK signaling pathway in response to ET treatment. HPLC analysis showed an accumulation of isoflavones (genistin, daidzein, and genistein) upon ET treatment, in agreement with the proteomics results. A metabolome analysis assigned 79 metabolites and further confirmed the accumulation of flavonoids and isoflavonoids in response to ET. A potential cross‐talk between ET and MAPK signaling, leading to the accumulation of flavonoids and isoflavonoids in soybean leaves is suggested.
The papain-like protease (PLpro), which controls replication of the severe acute respiratory syndrome coronavirus (SARS-CoV), has been identified as a potential drug target for the treatment of SARS. ...An intensive hunt for effective anti-SARS drugs has been undertaken by screening for natural product inhibitors that target SARS-CoV PLpro. In this study, diarylheptanoids 1-9 were isolated from Alnus japonica, and the inhibitory activities of these compounds against PLpro were determined. Of the isolated diarylheptanoids, hirsutenone (2) showed the most potent PLpro inhibitory activity, with an inhibitory concentration (IC50) value of 4.1 µM. Structure-activity analysis showed that catechol and α,β-unsaturated carbonyl moiety in the molecule were the key requirement for SARS-CoV cysteine protease inhibition.
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