Functionalized gold nanoparticle enhanced nanorod hyperbolic metamaterial biosensor for highly sensitive detection of carcinoembryonic antigen.

Hyperbolic metamaterial (HMM) biosensors based on metals have superior performance in comparison with conventional plasmonic biosensors in the detection of low concentrations of molecules. In this study, a nanorod HMM (NHMM) biosensor based on refractive index changes for carcinoembryonic antigen (CEA) detection is developed using secondary antibody modified gold nanoparticle (AuNP-Ab2) nanocomposites as signal amplification element for the first time. Numerical analysis based on finite element method is conducted to simulate the perturbation of the electric field of bulk plasmon polariton (BPP) supported by a NHMM in the presence of a AuNP. The simulation reveals an enhancement of the localized electric field, which arises from the resonant coupling of BPP to the localized surface plasmon resonance supported by AuNPs and is beneficial for the detection of changes of the refractive index. Furthermore, the AuNP-Ab2 nanocomposites-based NHMM (AuNP/Ab2-NHMM) biosensor enables CEA detection in the visible and near-infrared regions simultaneously. The highly sensitive detection of CEA with a wide linear range of 1-500 ng/mL is achieved in the near-infrared region. The detectable concentration of the AuNP/Ab2-NHMM biosensor has a 50-fold decrease in comparison with a NHMM biosensor. A low detection limit of 0.25 ng/mL (1.25 pM) is estimated when considering a noise level of 0.05 nm as the minimum detectable wavelength shift. The proposed method achieves high sensitivity and good reproducibility for CEA detection, which makes it a novel and viable approach for biomedical research and early clinical diagnostics.

Mode-locked fiber laser based on a small-period long-period fiber grating inscribed by femtosecond laser.

We demonstrate stable mode-locked pulses in an erbium-doped fiber laser (EDFL) using a femtosecond laser-inscribed small-period long-period grating (SP-LPG). The SP-LPG has a period of 25 µm and a length of 2.5 mm. The polarization dependent loss (PDL) of the SP-LPG reaches 20 dB at the wavelength of 1556 nm and 25 dB at the wavelength of 1607 nm, which is sufficient to trigger the mode-locking mechanism. In addition, a mode-locked fiber laser (MLFL) based on the SP-LPG has been demonstrated to generate 1.58-ps pulses at 1577 nm with a bandwidth of 4 nm and a repetition rate of 1.54 MHz. The signal-to-noise ratio (SNR) of 50 dB shows the high stability of this system. This work indicates various potential applications of the SP-LPG in ultra-fast laser technologies due to its simple fabrication, compact structure, and high damage threshold.

Long-Period Fiber Grating Sensors for Chemical and Biomedical Applications.

Optical fiber biosensors (OFBS) are being increasingly proposed due to their intrinsic advantages over conventional sensors, including their compactness, potential remote control and immunity to electromagnetic interference. This review systematically introduces the advances of OFBS based on long-period fiber gratings (LPFGs) for chemical and biomedical applications from the perspective of design and functionalization. The sensitivity of such a sensor can be enhanced by designing the device working at or near the dispersion turning point, or working around the mode transition, or their combination. In addition, several common functionalization methods are summarized in detail, such as the covalent immobilization of 3-aminopropyltriethoxysilane (APTES) silanization and graphene oxide (GO) functionalization, and the noncovalent immobilization of the layer-by-layer assembly method. Moreover, reflective LPFG-based sensors with different configurations have also been introduced. This work aims to provide a comprehensive understanding of LPFG-based biosensors and to suggest some future directions for exploration.

The Effect of Electrolytic Jet Orientation on Machining Characteristics in Jet Electrochemical Machining.

Jet electrochemical machining (Jet-ECM) is a significant prospective electrochemical machining process for the fabrication of micro-sized features. Traditionally and normally, the Jet-ECM process is carried out with its electrolytic jet being vertically impinged downstream against the workpiece. Therefore, other jet orientations, including a vertically upstream orientation and a horizontal orientation, have rarely been adopted. In this study, three jet orientations were applied to electrolytic jet machining, and the effect of jet orientations on machining characteristics was systemically investigated. Horizontal jet orientation is of great benefit in achieving accurate micro-sized features with excellent surface quality with either a static jet or a scanning jet for the Jet-ECM. On the other hand, the Jet-ECM with a horizontal jet orientation has a smaller material removal rate (MMR) than the ones with vertical jet orientations, which have almost the same MMR. It was found that an enhancement of machining localization and a reduction of MMR for horizontal jet electrochemical machining primarily results from an improvement of the mass-transfer field. The horizontal orientation of the jet is beneficial for the Jet-ECM processes to improve machining accuracy.

Novel fabrication of hollow and spinous NiCo2S4 nanotubes templated by natural silk for all-solid-state asymmetric supercapacitors.

Recently, ternary cobalt nickel sulfide, performing as the promising electrode material for supercapacitors has obtained great interests. Herein, the hollow and spinous NiCo2S4 nanotubes are designed and prepared through a simple hydrothermal reaction using the natural silk as the template. The spinous Ni-Co precursors are grown on the natural silk through a facile hydrothermal strategy and the hollow structure is obtained by decomposing the silk via hydrothermal sulfurization. After the calcination treatment, the hollow and spinous NiCo2S4 nanotubes are applied as the electrode material and exhibit better electrochemical performance than the solely vulcanized samples. In addition, owing to the unique hollow and spinous structure of NiCo2S4 nanotubes, the supercapacitor electrode material shows good specific capacitance (630 F g-1 at 1 A g-1), low internal resistance Rs (0.68 Ω) and high capacitance retention (91% after 3000 cycles) at 10 A g-1. Furthermore, an all-solid-state asymmetric supercapacitor is self-assembled with the SC400 composite and exhibits an energy density of 52.34 Wh kg-1 at the power density of 2206.37 W kg-1. Additionally, a blue LED indicator can be powered by connecting two ASCs in series. The prepared hollow and spinous NiCo2S4 nanotubes with excellent electrochemical properties can envision promising applications in energy storage devices and nanotechnology.

Fabrication of Cobaltosic Oxide Nanoparticle-Doped 3 D MXene/Graphene Hybrid Porous Aerogels for All-Solid-State Supercapacitors.

MXenes are a new family of 2 D transition metal carbides and nitrides, which have attracted enormous attention in electrochemical energy storage, sensing technology, and catalysis owing to their good conductivity, high specific surface area, and excellent electrochemical properties. In this work, a series of Co3 O4 -doped 3 D MXene/RGO hybrid porous aerogels is designed and prepared through a facile in situ reduction and thermal annealing process, in which the reduced graphene oxide (RGO) conductive network can electrically link the separated Co3 O4 -MXene composite nanosheets, leading to enhanced electronic conductivity. It is found that upon using the Co3 O4 -MXene/RGO hybrid porous aerogel prepared with a mass ratio of Co3 O4 -MXene/RGO of 3:1 (CMR31) as an electrode for a supercapacitor, a superior specific capacitance of 345 F g-1 at the current density of 1 A g-1 is achieved, which is significantly higher than those of Ti3 C2 Tx MXene, RGO, and MXene/RGO electrodes. In addition, a high capacitance retention (85 % of the initial capacitance after 10 000 cycles at a high current density of 3 A g-1 ) and a low internal resistance Rs (0.44 Ω) can be achieved. An all-solid-state asymmetric supercapacitor (ASC) device is assembled using CMR31, and it has the ability to light up a blue LED indicator for 5 min if four ASCs are connected in series. Therefore, these novel Co3 O4 -MXene/RGO hybrid porous aerogels have potential practical applications in high-energy storage devices.

A versatile signal-enhanced ECL sensing platform based on molecular imprinting technique via PET-RAFT cross-linking polymerization using bifunctional ruthenium complex as both catalyst and sensing probes.

Molecularly imprinted technique (MIT) has proven to be a significant tool in the analyzing area in virtue of its obvious advantages such as specific recognition, favorable stability to high temperature and higher sensitivity. Electrochemiluminescence (ECL) technology has also been receiving enormous attention as a powerful tool in sensing fields. However, sensors based on the combination of MIT and ECL technologies have seldom been reported yet. Herein, we find that Ru(bpy)32+ cannot only work as an efficient catalyst for photo-induced electron transfer-reversible addition-fragmentation chain transfer (PET-RAFT) polymerization, but also as a sensing probe for ECL sensor. Based on this, we successfully construct ECL sensors via the combination of MIT and ECL techniques. In details, poly(methacrylic acid) (PMAA) and cross-linked PMAA were synthesized first via a well-controlled PET-RAFT polymerization using Ru(bpy)32+ as catalyst under illumination of visible light with a wavelength of 460 nm, as confirmed by 1H NMR and gel permeation chromatography (GPC). Then, negatively-charged Au nanoparticles (AuNPs) with average sizes of 20 nm were prepared and modified with Ru(bpy)32+ via electrostatic incorporation. MIPs were prepared on the surface of AuNPs using melamine (MEL) as the template via PET-RAFT controlled cross-linking polymerization. The MIPs modified AuNPs (AuNPs-MIPs) were then fixed on the surface of working electrode with Nafion to achieve a solid-state ECL sensing platform employing Ru(bpy)32+ as the ECL probes. The as-prepared sensor showed a wide detection range of 5.0 × 10-13 - 5.0 × 10-6 mol/L and a low detection limit of 1.0 × 10-13 mol/L (S/N ≥ 3) was reached in the detection of MEL. Moreover, further tests for analyzing MEL structural analogues proved that the constructed ECL sensing platform could be utilized to detect various substances via specific recognitions.

A high current pulsed power generator CQ-3-MMAF with co-axial cable transmitting energy for material dynamics experiments.

A high current pulsed power generator CQ-3-MMAF (Multi-Modules Assembly Facility, MMAF) was developed for material dynamics experiments under ramp wave and shock loadings at the Institute of Fluid Physics (IFP), which can deliver 3 MA peak current to a strip-line load. The rise time of the current is 470 ns (10%-90%). Different from the previous CQ-4 at IFP, the CQ-3-MMAF energy is transmitted by hundreds of co-axial high voltage cables with a low impedance of 18.6 mΩ and low loss, and then hundreds of cables are reduced and converted to tens of cables into a vacuum chamber by a cable connector, and connected with a pair of parallel metallic plates insulated by Kapton films. It is composed of 32 capacitor and switch modules in parallel. The electrical parameters in short circuit are with a capacitance of 19.2 µF, an inductance of 11.7 nH, a resistance of 4.3 mΩ, and working charging voltage of 60 kV-90 kV. It can be run safely and stable when charged from 60 kV to 90 kV. The vacuum of loading chamber can be up to 10(-2) Pa, and the current waveforms can be shaped by discharging in time sequences of four groups of capacitor and switch modules. CQ-3-MMAF is an adaptive machine with lower maintenance because of its modularization design. The COMSOL Multi-physics® code is used to optimize the structure of some key components and calculate their structural inductance for designs, such as gas switches and cable connectors. Some ramp wave loading experiments were conducted to check and examine the performances of CQ-3-MMAF. Two copper flyer plates were accelerated to about 3.5 km/s in one shot when the working voltage was charged to 70 kV. The velocity histories agree very well. The dynamic experiments of some polymer bonded explosives and phase transition of tin under ramp wave loadings were also conducted. The experimental data show that CQ-3-MMAF can be used to do material dynamics experiments in high rate and low cost shots. Based on this design concept, the peak current of new generators can be increased to 5-6 MA and about 100 GPa ramp stress can be produced on the metallic samples for high pressure physics, and a conceptual design of CQ-5-MMAF was given.