5.4 W, 2.35†µm cascaded Raman fiber laser pumped by dissipative soliton resonance-like pulses.

We present a nonlinear amplifying loop mirror-based mode-locked fiber laser. By adjusting the pump power, the proposed laser exhibits a dissipative soliton resonance (DSR)-like pulse operation with a maximum pulse width of 150 ns. Subsequently, a three-stage Tm3+-doped fiber amplifier is implemented using a single-mode double-cladding Tm3+-doped fiber to increase the DSR-like pulse output power to 52.5 W, achieving a pump slope efficiency of 47.1% in the main amplifier. A 25 m first-order Raman-gain fiber (UHNA7) is pumped by a DSR-like pulse, and 16.3 W of pure 2.135 µm first-order Raman light with a spectral purity of 73.4% is obtained. Finally, 5.4 W of 2.35 µm second-order Raman light with a spectral purity of 66% is obtained using a 10 m 98% germania-core fiber as a second-order Raman-gain fiber cascaded after UHNA7 fiber. To the best of our knowledge, this is the highest output power ever obtained from a 2.3 µm laser.

Compact and efficient high-power mid-infrared supercontinuum fiber laser source based on a noise-like pulse and germania fiber.

Here, we demonstrate a compact and efficient high-power mid-infrared supercontinuum (MIR-SC) laser source based on a tunable noise-like pulse (NLP) fiber laser system and a short section of single-mode germania-core fiber (GCF). The NLP all-polarization-maintaining fiber laser system can deliver the maximum output power of ∼30.6 W and a broadband spectrum (∼1.8-2.7 µm) with a compact single-stage fiber amplifier. By directly pumping only ∼6.5 cm-long GCF with a core diameter of ∼3.5 µm, a MIR-SC (spectral coverage of ∼1.5-3.3 µm) with a maximum power of ∼25.2 W and a power conversion efficiency ∼81.2% is obtained, which represent the highest power and efficiency in any single-mode GCF-based MIR-SCs, to the best of our knowledge. Our study contributes to the high-power MIR-SC laser source with compact all-fiber configuration, and will prompt its practical applications.

A Degradable Tribotronic Transistor for Self-Destructing Intelligent Package e-Labels.

Recently, discarded electronic products have caused serious environmental pollution and information security issues, which have attracted widespread attention. Here, a degradable tribotronic transistor (DTT) for self-destructing intelligent package e-labels has been developed, integrated by a triboelectric nanogenerator and a protonic field-effect transistor with sodium alginate as a dielectric layer. The triboelectric potential generated by external contact electrification is used as the gate voltage of the organic field-effect transistor, which regulates carrier transport through proton migration/accumulation. The DTT has successfully demonstrated its output characteristics with a high sensitivity of 0.336 mm-1 and a resolution of over 100 µm. Moreover, the DTT can be dissolved in water within 3 min and completely degraded in soil within 12 days, demonstrating its excellent degradation characteristics, which may contribute to environmental protection. Finally, an intelligent package e-label based on the modulation of the DTT is demonstrated, which can display information about the package by a human touch. The e-label will automatically fail due to the degradation of the DTT over time, achieving the purpose of information confidentiality. This work has not only presented a degradable tribotronic transistor for package e-labels but also exhibited bright prospects in military security, information hiding, logistics privacy, and personal affairs.

Over 3.8 W, 3.4†µm picosecond mid-infrared parametric conversion based on a simplified one-to-many scheme.

In this paper, we demonstrate a simplified one-to-many scheme for efficient mid-infrared (MIR) parametric conversion. Such a scheme is based on a continuous wave (CW) single longitudinal mode master oscillator power-amplifier (MOPA) fiber system as the signal source and a picosecond pulsed MOPA fiber system, exhibiting multiple longitudinal modes, as the pump source. The signal and pump beams are combined and co-coupled into a piece of 50-mm long 5% MgO-doped PPLN crystal for the parametric conversion. As high as ∼3.82 W average power at a central idler wavelength of ∼3.4 µm is achieved when the launched pump and signal powers are ∼41.73 and ∼11.45 W, respectively. Above some threshold value, the delivered idler power shows a roll-over effect against the signal power and saturation-like effect against the pump power. Consequently, the highest conversion efficiency is observed at such a threshold pump power. To the best of our knowledge, our result represents the highest average power produced from any single-pass parametric conversion source with >3 µm idler wavelength feeding with a CW signal. Moreover, our proposed scheme can simplify the design of parametric conversion system significantly and meanwhile make the system more robust in applications. This is attributed to two main aspects. Firstly, the scheme's one-to-many feature can reduce wavelength sensitivity remarkably in the realization of quasi-phase-matching. Secondly, for moderate power requirement it does not always require a high peak power synchronized pulsed signal source; a CW one can be an alternative, thereby making the system free from complex time synchronization and the related time jitter.

Cavity-birefringence-based manipulation of long-duration optical pulses in a passively mode-locked fiber laser with large normal dispersion.

Optical pulse manipulation in the large normal dispersion regime through intracavity birefringence management is demonstrated experimentally in an erbium-doped fiber (EDF) laser, for the first time to the best of our knowledge. The EDF laser is passively mode-locked based on a nonlinear amplifying loop mirror (NALM) in a figure-of-eight (f-8) configuration. Different lengths of the same type of polarization-maintaining fiber (PMF) are incorporated into the NALM to vary the net cavity birefringence. For each length of PMF, various polarization states and pump powers were tested and compared to achieve a pulse duration tuning range as large as possible. For comparison, these polarization states and pump powers were also studied by incorporating the PMF into the unidirectional loop of the f-8 cavity. Our results reveal some new features for the management of cavity birefringence that can enable long-duration pulse manipulation in the large normal dispersion regime.

Self-Powered Wireless Temperature and Vibration Monitoring System by Weak Vibrational Energy for Industrial Internet of Things.

Developing self-powered smart wireless sensor networks by harvesting industrial environmental weak vibration energy remains a challenge and an impending need for enabling the widespread rollout of the industrial internet of things (IIoT). This work reports a self-powered wireless temperature and vibration monitoring system (WTVMS) based on a vibrational triboelectric nanogenerator (V-TENG) and a piezoelectric nanogenerator (PENG) for weak vibration energy collection and information sensing. Therein, the V-TENG can scavenge weak vibration energy down to 80 µm to power the system through a power management module, while the PENG is able to supply the frequency signal to the system by a comparison circuit. In an industrial vibration environment where the vibration frequency and amplitude are 20 Hz and 100 µm, respectively, the WTVMS can upload temperature and frequency information on the equipment to the cloud in combination with the narrowband IoT technology to realize real-time information monitoring. Furthermore, the WTVMS can work continuously for more than 2 months, during which the V-TENG can operate up to 100 million cycles, achieving ultrahigh stability and durability. By integrating weak vibration energy harvesting and active sensing technology, the WTVMS can be used for real-time online monitoring and early fault diagnosis of vibration equipment, which has great application prospects in industrial production, machinery manufacturing, traffic transportation, and intelligent IIoT.

Near-Zero Quiescent Power Sound Wake-Up and Identification System Based on a Triboelectric Nanogenerator.

Sound monitoring has been widely used in the field of the Internet of Things (IoT), in which the sensors are mainly powered by batteries with high power consumption and limited life. Here, a near-zero quiescent power sound wake-up and identification system based on a triboelectric nanogenerator (TENG) is proposed, in which the sound TENG (S-TENG) is used for ambient sound energy harvesting and system activation. Once the sound intensity is higher than 65 dB, the converted and stored electric energy by the S-TENG can wake up the system within 0.5 s. By integrating a deep learning technique, the system is used for identifying sound sources, such as drilling, child playing, dog barking, and street music. In the active mode, the sound signals are recorded by a microelectromechanical systems (MEMS) microphone and then sent to a remote computer for sound recognition through a wireless transmitter within 2.8 s. In the standby mode, the ambient sound is not enough to wake up the system, and the quiescent power consumption is only 55 nW. This work provides a triboelectric sensor-based ultralow quiescent power sound wake-up system, which has shown excellent application prospects in smart homes, unmanned monitoring, and the Internet of Things.

Separation and structural elucidation of a novel vardenafil analogue as an adulterant in a natural health care dietary supplement.

A novel vardenafil analogue was identified in dietary supplement as an adulterant in herbal formulations. The structure of this analogue was elucidated using HRMS, NMR after extraction from the pulverized powder. It was named morphardenafil as a morpholine ring has replaced the N-ethyl piperazine ring in vardenafil. A tablet of this dietary supplement contained about 50 mg of unspecified morphardenafil, which is 2.5 - 20-times the prescriptive dosage of Levetra, the commercial formulation of the vardenafil monohydrochloride salt in the market and probably places unwary consumers at risk for potentially serious adverse effects or drug-drug interaction (DDI).

A Flexible Tribotronic Artificial Synapse with Bioinspired Neurosensory Behavior.

As key components of artificial afferent nervous systems, synaptic devices can mimic the physiological synaptic behaviors, which have attracted extensive attentions. Here, a flexible tribotronic artificial synapse (TAS) with bioinspired neurosensory behavior is developed. The triboelectric potential generated by the external contact electrification is used as the ion-gel-gate voltage of the organic thin film transistor, which can tune the carriers transport through the migration/accumulation of ions. The TAS successfully demonstrates a series of synaptic behaviors by external stimuli, such as excitatory postsynaptic current, paired-pulse facilitation, and the hierarchical memory process from sensory memory to short-term memory and long-term memory. Moreover, the synaptic behaviors remained stable under the strain condition with a bending radius of 20 mm, and the TAS still exhibits excellent durability after 1000 bending cycles. Finally, Pavlovian conditioning has been successfully mimicked by applying force and vibration as food and bell, respectively. This work demonstrates a bioinspired flexible artificial synapse that will help to facilitate the development of artificial afferent nervous systems, which is great significance to the practical application of artificial limbs, robotics, and bionics in future.

Multi-scale simulation of proton diffusion in dislocation cores in BaZrO3.

Dislocations are important for their effects on the chemical, electrical, magnetic, and transport properties of oxide materials, especially for electrochemical devices such as solid fuel cells and resistive memories, but these effects are still under-studied at the atomic level. We have developed a quantum mechanical/molecular mechanical (QM/MM)-based multiscale simulation program to reveal the diffusion properties of protons on 〈100〉 edge dislocations in BaZrO3 perovskite oxide. We find that the large free space and the presence of hydrogen bonds in the dislocation core structure lead to significant trapping of protons. The diffusion properties of protons in dislocation cores were investigated, and no evidence of pipeline diffusion was found from the calculated migration energy barriers, which not only did not accelerate ion diffusion but rather decreases the conductivity of ions. The proton diffusion properties of Y-doped BaZrO3 (BZY), with a dislocation core structure (BZY-D) and with a grain boundary structure (BZY-GB) were also compared. In all three structures, local lattice deformation occupies an essential part in the proton transfer and rotation processes. The change in bond order is calculated and it is found that the interaction with oxygen and Zr ions during proton transfer and rotation controls the energy barrier for local lattice deformation of the O-B-O motion, which affects the proton diffusion in the structure. Our study provides insight into proton diffusion in dislocations in terms of mechanical behavior, elucidates the origin of the energy barrier associated with proton diffusion in dislocations, and provides guidance for the preparation and application of proton conductors.

Self-Powered and Autonomous Vibrational Wake-Up System Based on Triboelectric Nanogenerators and MEMS Switch.

With the extensive application of wireless sensing nodes, the demand for sustainable energy in unattended environments is increasing. Here, we report a self-powered and autonomous vibrational wake-up system (SAVWS) based on triboelectric nanogenerators and micro-electromechanical system (MEMS) switches. The energy triboelectric nanogenerator (E-TENG) harvests vibration energy to power the wireless transmitter through a MEMS switch. The signal triboelectric nanogenerator (S-TENG) controls the state of the MEMS switch as a self-powered accelerometer and shows good linearity in the acceleration range of 1-4.5 m/s2 at 30 Hz with a sensitivity of about 14.6 V/(m/s2). When the acceleration increases, the S-TENG turns on the MEMS switch, and the wireless transmitter transmits an alarm signal with the energy from E-TENG, using only 0.64 mJ. Using TENGs simultaneously as an energy source and a sensor, the SAVWS provides a self-powered vibration monitoring solution for unattended environments and shows extensive applications and great promise in smart factories, autonomous driving, and the Internet of Things.

Triboelectric Nanogenerators as Active Tactile Stimulators for Multifunctional Sensing and Artificial Synapses.

The wearable tactile sensors have attracted great attention in the fields of intelligent robots, healthcare monitors and human-machine interactions. To create active tactile sensors that can directly generate electrical signals in response to stimuli from the surrounding environment is of great significance. Triboelectric nanogenerators (TENGs) have the advantages of high sensitivity, fast response speed and low cost that can convert any type of mechanical motion in the surrounding environment into electrical signals, which provides an effective strategy to design the self-powered active tactile sensors. Here, an overview of the development in TENGs as tactile stimulators for multifunctional sensing and artificial synapses is systematically introduced. Firstly, the applications of TENGs as tactile stimulators in pressure, temperature, proximity sensing, and object recognition are introduced in detail. Then, the research progress of TENGs as tactile stimulators for artificial synapses is emphatically introduced, which is mainly reflected in the electrolyte-gate synaptic transistors, optoelectronic synaptic transistors, floating-gate synaptic transistors, reduced graphene oxides-based artificial synapse, and integrated circuit-based artificial synapse and nervous systems. Finally, the challenges of TENGs as tactile stimulators for multifunctional sensing and artificial synapses in practical applications are summarized, and the future development prospects are expected.

10 µJ noise-like pulse generated from all fiberized Tm-doped fiber oscillator and amplifier.

Herein, we presented a high energy noise-like (NL) pulse Tm-doped fiber laser (TDFL) system. Relying on the nonlinear amplifying loop mirror (NALM), stable noise-like pulses with coherence spike width of ∼317 fs and envelope width of ∼4.2 ns were obtained from an all polarization-maintaining fiberized oscillator at central wavelength of ∼1946.4 nm with 3 dB bandwidth of ∼24.9 nm. After the amplification in an all-fiberized TDF amplifier system, the maximum average output power of ∼32.8 W and pulse energy of ∼10.1 µJ were obtained, which represents the highest pulse energy of NL pulse at ∼2 µm, to the best of our knowledge. We believe that the high energy NL pulse source has the potential application in mid-infrared supercontinuum generation.

Over 10 W linearly polarized supercontinuum directly produced in an erbium-doped fiber MOPA seeded with stretched soliton.

We experimentally achieve over 10 W linearly polarized supercontinuum (SC) generation in a polarization-maintaining (PM) erbium-doped fiber (EDF) master oscillator power-amplifier (MOPA). The house-built PM seeding EDF laser can deliver ∼209fs soliton around ∼1563.7nm, which is then stretched to >15ps using a long piece of normal-dispersion fiber. The wideband spectrum of the ultrashort seeding soliton facilitates the further spectral broadening with nonlinear effects. The soliton stretching decelerates the peak power increase, thus facilitating higher amplified average power. After several stages of pre-amplification, the stretched soliton is fed into the main amplifier constructed with PM large mode area fibers. The output average power is finally amplified to ∼11.51W. The corresponding spectrum spans from ∼1450 to ∼2200nm, indicating that SC is formed due to the induced strong nonlinear effects. The polarization extinction ratio at the output reaches over 18 dB. The PM characteristic potentially enhances the system's resistance to environmental disturbances and eliminates instabilities relating to polarization-mode coupling. Our result represents, so far, the highest SC power directly produced in an EDF MOPA, to the best of our knowledge, especially in a linearly polarized manner. This also suggests a scheme for powerful SC generation that employs direct laser diode pumping and duration-managed pulse seeding.

Rehabilitation of patients with COVID-19.

INTRODUCTION: In 2020, due to severe acute respiratory syndrome coronavirus-2 (SARS-CoV-2), coronavirus disease (COVID-19) has become a pandemic. As of 11 August 2020, the cumulative number of confirmed cases worldwide had reached 19 million, with 700,000 reported deaths, indicating this pandemic's significant global impact. AREAS COVERED: We reviewed the application of rehabilitation therapy in the clinical treatment of COVID-19 patients. A systematic search was performed using PubMed, Springer, CNKI, and Wanfang Data of database up to 1 August 2020. The search terms included the English terms and their Chinese equivalents: 'COVID-19,' 'ARDS,' 'rehabilitation,' 'critically ill patients,' 'physiotherapy,' 'respiratory rehabilitation,' 'traditional Chinese medicine,' and 'psychotherapy.' EXPERT OPINION: Rehabilitation research concerning patients with COVID-19 remains ongoing. Rehabilitation guidance for such patients with COVID-19 is based on previous experience. However, as different patients have differing degrees of dysfunction, personalized plans need to be designed according to the patients' age, sex, lifestyle, hobbies, occupation, and physical conditions. The rapid development of remote devices that can monitor patients' real-time physical conditions post-discharge may encourage better adherence to rehabilitation training.

Intrinsically Stretchable Organic-Tribotronic-Transistor for Tactile Sensing.

Stretchable electronics are of great significance for the development of the next-generation smart interactive systems. Here, we propose an intrinsically stretchable organic tribotronic transistor (SOTT) without a top gate electrode, which is composed of a stretchable substrate, silver nanowire electrodes, semiconductor blends, and a nonpolar elastomer dielectric. The drain-source current of the SOTT can be modulated by external contact electrification with the dielectric layer. Under 0-50% stretching both parallel and perpendicular to the channel directions, the SOTT retains great output performance. After being stretched to 50% for thousands of cycles, the SOTT can survive with excellent stability. Moreover, the SOTT can be conformably attached to the human hand, which can be used for tactile signal perception in human-machine interaction and for controlling smart home devices and robots. This work has realized a stretchable tribotronic transistor as the tactile sensor for smart interaction, which has extended the application of tribotronics in the human-machine interface, wearable electronics, and robotics.

Quantitative trait loci analysis of seed oil content and composition of wild and cultivated soybean.

BACKGROUND: Soybean oil is a major source of edible oil, and the domestication of wild soybean has resulted in significant changes in oil content and composition. Extensive efforts have been made to identify genetic loci that are related to soybean oil traits. The objective of this study was to identify quantitative trait loci (QTLs) related to soybean seed oil and compare the fatty acid composition between wild and cultivated soybean. RESULTS: Using the specific-locus amplified fragment sequencing (SLAF-seq) method, a total of 181 recombinant inbred lines (RILs) derived from a cross between wild soybean ZYD00463 (Glycine soja) and cultivated soybean WDD01514 (Glycine max) were genotyped. Finally, a high-density genetic linkage map comprising 11,398 single-nucleotide polymorphism (SNP) markers on 20 linkage groups (LGs) was constructed. Twenty-four stable QTLs for seed oil content and composition were identified by model-based composite interval mapping (CIM) across multiple environments. Among these QTLs, 23 overlapped with or were adjacent to previously reported QTLs. One QTL, qPA10_1 (5.94-9.98 Mb) on Chr. Ten is a novel locus for palmitic acid. In the intervals of stable QTLs, some interesting genes involved in lipid metabolism were detected. CONCLUSIONS: We developed 181 RILs from a cross between wild soybean ZYD00463 and cultivated soybean WDD01514 and constructed a high-density genetic map using the SLAF-seq method. We identified 24 stable QTLs for seed oil content and compositions, which includes qPA10_1 on Chr. 10, a novel locus for palmitic acid. Some interesting genes in the QTL regions were also detected. Our study will provide useful information for scientists to learn about genetic variations in lipid metabolism between wild and cultivated soybean.

Narrow-bandwidth h-shaped pulse generation and evolution in a net normal dispersion thulium-doped fiber laser.

We report on experimental generation and evolution of circumstance-susceptible, narrow-bandwidth, h-shaped pulse in a thulium-doped fiber (TDF) laser. With typical mode-locking technique based on nonlinear amplifying loop mirror, a type of h-shaped pulse is generated in a net normal dispersion regime for the first time to our best knowledge. Different from pulses with similar profiles achieved in typical anomalous dispersion regime, the h-shaped pulse here exhibits extremely narrow spectral bandwidth and meanwhile becomes highly circumstance-susceptible. Not alike the well-preserved h-shaped profile with anomalous dispersion, here the h-shaped pulse can easily evolve into various other pulse patterns with circumstance variations, including peak-depressed profiles, burst-like emission, multiple h-shaped pulses, and even some highly complex temporal cases. Despite that, the h-shaped pulse broadens as the pump power increasing, being a typical pump-related characteristic dominated by the peak-power-clamping effect. Moreover, it is observed that the h-shaped pulse profile can be re-shaped by incorporating a piece of unpumped TDF into the cavity, i.e., introducing some reabsorption. Our results substantiate the experimental revelation of such a type of particular-profile pulse in the normal dispersion regime, demonstrating some new evolution features facilitated by the dispersion-relevant circumstance-susceptibility.

AlphaLISA for detection of staphylococcal enterotoxin B free from interference by protein A.

Staphylococcal enterotoxin B (SEB) is an important enterotoxin which is a major reason for food poisoning and a potential biologic agent. Hence, rapid and accurate detection is very important. An amplified luminescent proximity homogeneous assay (AlphaLISA) for SEB detection was established here. Its performance was evaluated on mock specimen and culture supernatant. Its free from the effect of protein A was compared with ELISA. Results showed that the linear range for SEB detection was 25 pg/mL to 25 ng/mL. The detection limitation is 25 pg/mL in buffer and 50 pg/mL in specimen respectively. There was no cross-reaction with other classical SEs or botulinum toxin. AlphaLISA was also tolerant to the matrix of sample and showed good repeatability. The inter-assay coefficient of variation (CV) and intra-assay CV were<10% for buffer and mock specimens, respectively. Besides AlphaLISA detection was free of the interference of protein A (which is the obstacle for immune-based detection of SEs in Staphylococcus aureus culture supernatants): this feature is very important for food-poisoning confirmation caused by SEB contamination. These data suggest that the AlphaLISA established here is well suited for SEB detection in food samples and S. aureus culture supernatants.