Facile One-Step Pyrolysis of ZnO/Biochar Nanocomposite for Highly Efficient Removal of Methylene Blue Dye from Aqueous Solution.

In this work, we developed a facile one-step pyrolysis method for preparing porous ZnO/biochar nanocomposites (ZBCs) with a large surface area to enhance the removal efficiency of dye from aqueous solution. Peanut shells were pyrolyzed under oxygen-limited conditions with a molten salt ZnCl2, which played the roles of the activating agent and precursor for the formation of nanoparticles. The effects of the mass ratio between the molten salt ZnCl2 and peanut shells as well as pyrolysis temperature on the formation of ZBCs were investigated. Characterization results revealed that the as-synthesized ZBCs exhibited a highly porous structure with a specific surface area of 832.12 m2/g, suggesting a good adsorbent for efficient removal of methylene blue (MB). The maximum adsorption capacity of ZBCs on MB was 826.44 mg/g, which surpassed recently reported adsorbents. The formation mechanism of ZnO nanoparticles on the biochar surface was due to ZnCl2 vaporization and reaction with water molecules extracted from the lignocellulosic structures. This study provides a basis for developing a simple and large-scale synthesis method for wastewater with a high adsorption capacity.

Simultaneous precipitation and discharge plasma processing for one-step synthesis of α-Fe2O3-Fe3O4/graphene visible light magnetically separable photocatalysts.

A novel facile combination of precipitation and plasma discharge reaction is successfully employed for one-step synthesis of an α-Fe2O3-Fe3O4 graphene nanocomposite (GFs). The co-existence and anchoring of hematite (α-Fe2O3) and magnetite (Fe3O4) nanoparticles onto a graphene sheet in the as synthesized GFs were verified by results of XRD, Raman, SEM, TEM, and XPS. HRTEM characterization was used for confirming the bonding between α-Fe2O3/Fe3O4 nanoparticles and the graphene sheet. Consequently, GFs shows superior photodegrading performance towards methylene blue (MB), compared to individual α-Fe2O3/Fe3O4 nanoparticles, as a result of band gap narrowing and the electron-hole pair recombination rate reducing. Moreover, GFs allows a good possibility of separating and recycling under an external-magnetic field, suggesting potential in visible-light-promoted photocatalytic applications.

Modulation of Interhemispheric Synchronization and Cortical Activity in Healthy Subjects by High-Definition Theta-Burst Electrical Stimulation.

Background: Various forms of theta-burst stimulation (TBS) such as intermittent TBS (iTBS) and continuous TBS (cTBS) have been introduced as novel facilitation/suppression schemes during repetitive transcranial magnetic stimulation (rTMS), demonstrating a better efficacy than conventional paradigms. Herein, we extended the rTMS-TBS schemes to electrical stimulation of high-definition montage (HD-TBS) and investigated its neural effects on the human brain. Methods: In a within-subject design, fifteen right-handed healthy adults randomly participated in 10 min and 2 mA HD-TBS sessions: unilateral (Uni)-iTBS, bilateral (Bi)-cTBS/iTBS, and sham stimulation over primary motor cortex regions. A 20-channel near-infrared spectroscopy (NIRS) system was covered on the bilateral prefrontal cortex (PFC), sensory motor cortex (SMC), and parietal lobe (PL) for observing cerebral hemodynamic responses in the resting-state and during fast finger-tapping tasks at pre-, during, and poststimulation. Interhemispheric correlation coefficient (IHCC) and wavelet phase coherence (WPCO) from resting-state NIRS and concentration of oxyhemoglobin during fast finger-tapping tasks were explored to reflect the symmetry between the two hemispheres and cortical activity, respectively. Results: The IHCC and WPCO of NIRS data in the SMC region under Bi-cTBS/iTBS showed relatively small values at low-frequency bands III (0.06-0.15 Hz) and IV (0.02-0.06), indicating a significant desynchronization in both time and frequency domains. In addition, the SMC activation induced by fast finger-tapping exercise was significantly greater during Uni-iTBS as well as during and post Bi-cTBS/iTBS sessions. Conclusions: It appears that a 10 min and 2 mA Bi-cTBS/iTBS applied over two hemispheres within the primary motor cortex region could effectively modulate the interhemispheric synchronization and cortical activation in the SMC of healthy subjects. Our study demonstrated that bilateral HD-TBS approaches is an effective noninvasive brain stimulation scheme which could be a novel therapeutic for inducing effects of neuromodulation on various neurological disorders caused by ischemic stroke or traumatic brain injuries.

Evaluating interhemispheric synchronization and cortical activity in acute stroke patients using optical hemodynamic oscillations.

Objective.An understanding of functional interhemispheric asymmetry in ischemic stroke patients is a crucial factor in the designs of efficient programs for post-stroke rehabilitation. This study evaluates interhemispheric synchronization and cortical activities in acute stroke patients with various degrees of severity and at different post-stroke stages.Approach.Twenty-three patients were recruited to participate in the experiments, including resting-state and speed finger-tapping tasks at week-1 and week-3 post-stroke. Multichannel near-infrared spectroscopy (NIRS) was used to measure the changes in hemodynamics in the bilateral prefrontal cortex (PFC), the supplementary motor area (SMA), and the sensorimotor cortex (SMC). The interhemispheric correlation coefficient (IHCC) measuring the synchronized activities in time and the wavelet phase coherence (WPCO) measuring the phasic activity in time-frequency were used to reflect the symmetry between the two hemispheres within a region. The changes in oxyhemoglobin during the finger-tapping tasks were used to present cortical activation.Main results.IHCC and WPCO values in the severe-stroke were significantly lower than those in the minor-stroke at low frequency bands during week-3 post-stroke. Cortical activation in all regions in the affected hemisphere was significantly lower than that in the unaffected hemisphere in the moderate-severe stroke measured in week-1, however, the SMC activation on the affected hemisphere was significantly enhanced in week-3 post-stroke.Significance.In this study, non-invasive NIRS was used to observe dynamic synchronization in the resting-state based on the IHCC and WPCO results as well as hemodynamic changes in a motor task in acute stroke patients. The findings suggest that NIRS could be used as a tool for early stroke assessment and evaluation of the efficacy of post-stroke rehabilitation.

Multifunctional applications for waste zinc-carbon battery to synthesize carbon dots and symmetrical solid-state supercapacitors.

In this study, we provide a simple and green approach to recycle waste zinc carbon batteries for making carbon dots and porous carbon material. The carbon dots are easily synthesized by one green step, the hydrothermal treatment of a carbon rod in a mixture of DI water and pure ethanol to obtain a blue fluorescence under UV light, which can be used directly as a fluorescence ink. The as-prepared carbon dot process give typical dots with a uniform diameter from 3 to 8 nm with a strong slight blue fluorescent. The porous carbon material is also recycled from carbon powder in a waste battery via one green step annealing process without any chemical activation and with a hierarchically porous structure. This porous carbon material is demonstrated as an electrode for symmetrical solid state supercapacitors (SSCs) in a sandwich structure: porous carbon/PVA-KOH/porous carbon. The SSCs using recycled porous carbon electrodes exhibit a good energy density of 4.58 W h kg-1 at a power density of 375 W kg-1 and 97.6% retention after 2000 cycles. The facile one green step of hydrothermal and also that of calcination provide a promising strategy to recycle waste zinc carbon batteries, which transfers the excellent applications.

Designing and pilot testing a novel high-definition transcranial burst electrostimulation device for neurorehabilitation.

Objective.Non-invasive brain stimulation has been promoted to facilitate neuromodulation in treating neurological diseases. Recently, high-definition (HD) transcranial electrical stimulation and a novel electrical waveform combining a direct current (DC) and theta burst stimulation (TBS)-like protocol were proposed and demonstrated high potential to enhance neuroplastic effects in a more-efficient manner. In this study, we designed a novel HD transcranial burst electrostimulation device and to preliminarily examined its therapeutic potential in neurorehabilitation.Approach.A prototype of the transcranial burst electrostimulation device was developed, which can flexibly output a waveform that combined a DC and TBS-like protocol and can equally distribute the current into 4 × 1 HD electrical stimulation by automatic impedance adjustments. The safety and accuracy of the device were then validated in a series ofin vitroexperiments. Finally, a pilot clinical trial was conducted to assess its clinical safety and therapeutic potential on upper-extremity rehabilitation in six patients with chronic stroke, where patients received either active or sham HD transcranial burst electrostimulation combined with occupational therapy three times per week for four weeks.Main results.The prototype was tested, and it was found to comply with all safety requirements. The output parameters were accurate and met the clinical study needs. The pilot clinical study demonstrated that the active HD transcranial burst electrostimulation group had greater improvement in voluntary motor function and coordination of the upper extremity than the sham control group. Additionally, no severe adverse events were noted, but slight skin redness under the stimulus electrode immediately after stimulation was seen.Conclusions.The results demonstrated the feasibility of incorporating the HD electrical DC and TBS-like protocol in our device; and the novel neuromodulatory device produced positive neurorehabilitation outcomes in a safe fashion, which could be the basis for the future clinical implementation for treating neurological diseases.Trial registration:ClinicalTrials.gov Identifier: NCT04278105. Registered on 20 February 2020.

Governing Landscapes for Ecosystem Services: A Participatory Land-Use Scenario Development in the Northwest Montane Region of Vietnam.

Land-use planning is an important policy instrument for governing landscapes to achieve multifunctionality in rural areas. This paper presents a case study conducted in Na Nhan commune in the northwest montane region of Vietnam to assess land-use strategies toward multiple ecosystem services, through integrated land-use planning. The assessment employed the Land-Use Planning for Multiple Ecosystem Services (LUMENS) framework and a number of methods and tools, including land-use mapping, GIS-based land-use change analysis, survey questionnaire, rapid carbon-stock appraisal for different land uses, qualitative ecosystem services assessment, and a backcasting technique. Our findings suggest that a lack of participation and acknowledgement of customary land-use practices inhibit successful implementation of current land-use planning and relevant policies such as payment for forest environmental services and the nationally determined contributions. The study also confirmed the contributions of forests and the land-use sector in achieving national emission reduction targets, especially when local stakeholders are involved early in the planning process. Other findings with important policy implications are: (i) tree-based land uses such as agroforestry are key to securing multiple ecosystem services and are highly relevant to local stakeholders, yet their potentials were not made explicit in current debates at the local level; (ii) local stakeholders are highly aware of the co-benefits of ecosystem services to climate-change mitigation and this should be considered in nationally determined contributions; and (iii) an approach for integrated, participatory land-use planning can help catalyze stakeholder engagement, and hence improve governance in rural landscapes.

Incorporating Indium Selenide Nanosheets into a Polymer/Small Molecule Binary Blend Active Layer Enhances the Long-Term Stability and Performance of Its Organic Photovoltaics.

In this report, we demonstrated that the incorporation of 15 wt % two-dimensional transition-metal dichalcogenide materials indium selenide (In2Se3) nanosheets into a polymer (PM6)/small molecule (Y6) active layer not only increased its light absorption but also enhanced the long-term stability of the PM6/Y6/In2Se3 ternary blend organic photovoltaic (OPV) devices. The power conversion efficiency (PCE) of the device was improved from 15.7 to 16.5% for the corresponding PM6/Y6 binary blend device. Moreover, the PM6/Y6/In2Se3 device retained 80% of its initial PCE after thermal treatment at 100 °C for 600 h; in comparison, the binary blend device retained only 62% of its initial value. This relative enhancement of 29% resulted from the In2Se3 nanosheets retarding or facilitating molecule packing in different orientations that stabilizes the morphology of the active layer. We adopted a modified kinetics model to account for the intrinsic degradation of the OPV; the degradation-facilitated energy for the degradation kinetics of the PCE for the ternary blend device was 5.3 kJ/mol, half of that (11.3 kJ/mol) of the binary blend device, indicating a slower degradation rate occurring for the case of incorporating In2Se3 nanosheets. Therefore, the incorporation of transition metal dichalcogenide nanosheets having tunable band gaps and large asymmetric shape appears to be a new way to improve the long-term stability of devices and realize the practical use of OPVs.

A 0.6-µW Chopper Amplifier Using a Noise-Efficient DC Servo Loop and Squeezed-Inverter Stage for Power-Efficient Biopotential Sensing.

To realize an ultra-low-power and low-noise instrumentation amplifier (IA) for neural and biopotential signal sensing, we investigate two design techniques. The first technique uses a noise-efficient DC servo loop (DSL), which has been shown to be a high noise contributor. The proposed approach offers several advantages: (i) both the electrode offset and the input offset are rejected, (ii) a large capacitor is not needed in the DSL, (iii) by removing the charge dividing effect, the input-referred noise (IRN) is reduced, (iv) the noise from the DSL is further reduced by the gain of the first stage and by the transconductance ratio, and (v) the proposed DSL allows interfacing with a squeezed-inverter (SQI) stage. The proposed technique reduces the noise from the DSL to 12.5% of the overall noise. The second technique is to optimize noise performance using an SQI stage. Because the SQI stage is biased at a saturation limit of 2VDSAT, the bias current can be increased to reduce noise while maintaining low power consumption. The challenge of handling the mismatch in the SQI stage is addressed using a shared common-mode feedback (CMFB) loop, which achieves a common-mode rejection ratio (CMRR) of 105 dB. Using the proposed technique, a capacitively-coupled chopper instrumentation amplifier (CCIA) was fabricated using a 0.18-µm CMOS process. The measured result of the CCIA shows a relatively low noise density of 88 nV/rtHz and an integrated noise of 1.5 µVrms. These results correspond to a favorable noise efficiency factor (NEF) of 5.9 and a power efficiency factor (PEF) of 11.4.

Plasma-Induced Exfoliation Provides Onion-Like Graphene-Surrounded MoS2 Nanosheets for a Highly Efficient Hydrogen Evolution Reaction.

With the goal of obtaining sustainable earth-abundant electrocatalyst materials displaying high performance in the hydrogen evolution reaction (HER), here we propose a facile one-pot plasma-induced electrochemical process for the fabrication of new core-shell structures of ultrathin MoS2 nanosheets engulfed within onion-like graphene nanosheets (OGNs@MoS2). The resultant OGNs@MoS2 structures not only increased the number of active sites of the semiconducting MoS2 nanosheets but also enhanced their conductivity. Our OGNs@MoS2 composites exhibited high HER performance, characterized by a low overpotential of 118 mV at a current density of 10 mA cm-2, a Tafel slope of 73 mV dec-1, and long-time stability of 105 s without degradation; this performance is much better than that of the sheet-like graphene-wrapped MoS2 composite GNs@MoS2 (182 mV, 82 mV dec-1) and is among the best ever reported for composites involving MoS2 and graphene nanosheets prepared through a simple one-batch process and using a low temperature and a short time for the HER. This approach appears to be an effective and simple strategy for tuning the morphologies of composites of graphene and transition metal dichalcogenide materials for a broad range of energy applications.

Adaptive Fuzzy Control With High-Order Barrier Lyapunov Functions for High-Order Uncertain Nonlinear Systems With Full-State Constraints.

This paper focuses on the practical output tracking control for a category of high-order uncertain nonlinear systems with full-state constraints. A high-order tan-type barrier Lyapunov function (BLF) is constructed to handle the full-state constraints of the control systems. By the BLF and combining a backstepping design technique, an adding a power integrator, and a fuzzy control, the proposed approach can control high-order uncertain nonlinear system with full-state constraints. A novel controller is designed to ensure that the tracking errors approach to an arbitrarily small neighborhood of zero, and the constraints on system states are not violated. The numerical example demonstrates effectiveness of the proposed control method.

New Simultaneous Exfoliation and Doping Process for Generating MX2 Nanosheets for Electrocatalytic Hydrogen Evolution Reaction.

Doping nonmetal atoms into layered transition metal dichalcogenide MX2 structures has emerged as a promising strategy for enhancing their catalytic activities for the hydrogen evolution reaction. In this study, we developed a new and efficient one-step approach that involves simultaneous plasma-induced doping and exfoliating of MX2 bulk into nanosheets-such as MoSe2, WSe2, MoS2, and WS2 nanosheets-within a short time and at a low temperature (ca. 80 °C). Specifically, by utilizing active plasma that is generated with an asymmetric electrical field during the electrochemical reaction at the surface of the submerged cathode tip, we are able to achieve doping of nitrogen atoms, from the electrolytes, into the semiconducting 2H-MX2 structures during their exfoliation process from the bulk states, forming N-doped MX2. We selected N-doped MoS2 nanosheets for demonstrating their catalytic hydrogen evolution potential. We modulated the electronic and transport properties of the MoS2 structure with the synergy of nitrogen doping and exfoliating for enhancing their catalytic activity. We found that the nitrogen concentration of 5.2 atom % at N-doped MoS2 nanosheets have an excellent catalytic hydrogen evolution reaction, where a low overpotential of 164 mV at a current density of 10 mA cm-2 and a small Tafel slope of 71 dec mV-1-much lower than those of exfoliated MoS2 nanosheets (207 mV, 82 dec mV-1) and bulk MoS2 (602 mV, 198 dec mV-1)-as well as an extraordinary long-term stability of >25 h in 0.5 M H2SO4 can be achieved.

Nimbandiolactone-21 and nimbandioloxyfuran, two new 28-norlimonoids from the leaves of Azadirachta indica (Meliaceae).

From an EtOAc-soluble fraction of the leaves of Azadirachta indica, two new 28-norlimonoids named nimbandiolactone-21 (1) and nimbandioloxyfuran (2), together with nimbandiolactone-23 (3), were isolated. Their relative structures were elucidated based on NMR spectroscopic interpretation and biosynthetic consideration. Nimbandioloxyfuran (2) and nimbandiolactone-23 (3) showed potent α-glucosidase inhibitory activity, with the IC50 values of 46.2 and 38.7 µM, respectively.