Efficient Interface Research Articles

A hardware accelerator for IEEE 802.15.4 Time-Slotted Channel Hopping transceiver

Time-Slotted Channel Hopping (TSCH), an operational mode of the IEEE 802.15.4e standard, imposes a high workload on the embedded processor, mainly due to its precise timing. The limited embedded processor of an edge device cannot satisfy the considerable memory footprint and computational complexity caused by functions that need precise timing in the protocol stack. Moving such duties to hardware seems to be a viable path towards offloading the processor and releasing its resource to be used for running firmware related to the implementation of the upper layers of the protocol stack as well as the application. In this work, a TSCH protocol hardware accelerator is designed and integrated within the digital baseband processor of an IEEE 802.15.4 transceiver. The whole system is implemented targeting the TSMC 65 nm technology. The designed TSCH accelerator has an efficient interface and is totally configurable by the software. It efficiently controls the transceiver, frees up embedded processor cycles, and reduces the interrupt callback to the processor. Therefore, the TSCH hardware accelerator makes it possible to use a cheaper embedded processor or to operate the processor on a lower clock speed which results in lower power consumption. The power analysis of the implemented system shows that, in the minimal setting of the TSCH accelerator, only 0.1% is added to the power consumption of the digital baseband processor. The power overhead increases to 5.6% for supporting three parallel slotframes which is a widely used TSCH setting in multi-hop networks. In return, the embedded processor is relaxed of processing TSCH timing related interrupts that are required for software-based TSCH implementation.

Transmission characteristics of femtosecond laser pulses in a polymer waveguide.

Femtosecond lasers have been widely employed in scientific and industrial applications, including the study of material properties, fabrication of structures on the sub-micrometer scale, surgical and medical treatment, etc. In these applications, the ultrafast laser is implemented either in free space or via an optical fiber-based channel. To investigate the light-matter interaction on a chip-based dimension, laser pulses with extremely high peak power need to be injected into an integrated optical waveguide. This requires the waveguide to be transparent and linear at this power, but also capable of providing a highly efficient and reliable interface for fiber-chip coupling. Contrary to the common belief that polymer materials may suffer from stability issues, we show that a polymer waveguide fabricated under simple and low-cost technology using only commercial materials can indeed transmit femtosecond laser pulses with similar characteristics as low-power continuous-wave laser. The coupling efficiency with a lensed fiber is ∼76% per facet. The pulse broadening effect in the polymer waveguide is also well fitted by the material and waveguide dispersion without nonlinear behavior. This study paves the way for developing a low-cost, highly efficient, polymer-based waveguide platform for the investigation of ultrafast phenomena on a chip.

Sequential generation of multiphoton entanglement with a Rydberg superatom

Multiqubit entanglement is an indispensable resource for quantum information science. In particular, the entanglement of photons is of conceptual interest due to its implications in measurement-based quantum computing, communication, and metrology. The traditional way of spontaneous parametric down-conversion already demonstrates entanglement of up to a dozen photons but is hindered by its probabilistic nature. Here, we experimentally demonstrate an efficient approach for multi-photon generation with a Rydberg superatom, a mesoscopic atomic ensemble under Rydberg blockade. Using it as an efficient single-photon interface, we iterate the photon creation process that gives rise to a train of temporal photonic modes entangled in photon number degree. We detect the multiphoton entanglement via converting the photon number degree to a time-bin degree. Photon correlations verify entanglement up to 12 modes. The efficiency scaling factor for adding one photon is 0.27, surpassing previous results, and can be increased significantly without fundamental limitations.

Efficient catalytic degradation of alkanes in soil by a novel heterogeneous Fenton catalyst of functionalized magnetic biochar.

In this study, sodium dodecyl sulfate (SDS) functionalized magnetic biochar (SDS-Fe@BC) was successfully prepared. Compared to other traditional heterogeneous Fenton catalysts, more total petroleum hydrocarbons (TPH) (3499.40mgkg-1) was adsorbed from soil to the surface of SDS-Fe@BC through hydrophobic interaction between alkyls in alkanes and SDS-Fe@BC, which formed an efficient interface oxidation system. In SDS-Fe@BC-mediated heterogeneous Fenton system, 10,191.41mgkg-1 (88.10%) TPH was degraded in the presence of 400mM H2O2, which was 1.38-5.67 folds than that of H2O2 alone, Fe2+, zero valent iron (ZVI), Fe3O4, pristine biochar (BC), and Fe@BC. Moreover, all individual alkanes were efficiently degraded (>75%), and the higher the initial amount of individual alkane, the more the degradative amount in the SDS-Fe@BC/H2O2 system. Additionally, TPH degradation was highly related to the mass ratio of SDS/Fe@BC, H2O2 concentration, SDS-Fe@BC dosage, and initial pH in the SDS-Fe@BC/H2O2 system, and the optimal values were 1:5, 400mM, 50mgg-1, and pH 7, respectively. Radical quenching experiments revealed that hydroxyl radicals (•OH) generated on the surface of SDS-Fe@BC was the dominated reactive oxidative species (ROS) responsible for alkanes degradation. After five cycles, SDS-Fe@BC still remained a high catalytic activity for alkanes degradation (73.21%), showing its excellent reusability. This study proved that the SDS-Fe@BC can be used as a potential heterogeneous Fenton catalyst for petroleum-contaminated soil remediation.

Stiffness Graded Electroactive Artificial Muscle

AbstractIn nature, hydrostatic, endo‐ and exo‐skeletons are widely observed, and provide essential rigidity and anchoring points for the application of muscular forces. The efficient interface between a hard skeleton and soft muscle in biology is made possible by a complex hierarchy of structures and composite materials, extending from the nano‐ to the meso‐scale. In contrast, artificial constructs that aim to bridge this hard‐soft interface are prone to failure due to local discontinuities and concentrations in stress and strain which lead to material ruptures, delamination, and tearing. In this article, the concept of a stiffness‐graded electroactive material is proposed which emulates the soft‐rigid interface in the nature biological systems and provides both electromechanical activity and the smooth stiffness gradient needed to bridge these two extreme states. This is achieved by programming the diffusion of a rigid filler material (polyvinyl chloride) in a liquid plasticizer (diisodecyl adipate). It is shown that the resulting stiffness gradient can match that of biological tissues such as smooth and skeletal muscles, and that the distal rigid region can be drilled and bonded and significant loads can be safely applied. Additionally, the resulting composite shows electroactive capability through graded anodophilic actuation characteristics. This protocol can be extended to numerous morphologies such as vertical or radial gradients depending on the deployment of two precursor ingredients. Finally, example applications including surface morphing and motion generation are demonstrated. The embodied stiffness gradient and electroactivity make this concept suitable for the development of bio‐integrating and wearable artificial muscles systems and more effective soft robots.

Intuitive, Efficient and Ergonomic Tele-Nursing Robot Interfaces: Design Evaluation and Evolution

Tele-nursing robots provide a safe approach for patient-caring in quarantine areas. For effective nurse–robot collaboration, ergonomic teleoperation and intuitive interfaces with low physical and cognitive workload must be developed. We propose a framework to evaluate the control interfaces to iteratively develop an intuitive, efficient, and ergonomic teleoperation interface. The framework is a hierarchical procedure that incorporates general to specific assessment and its role in design evolution. We first present pre-defined objective and subjective metrics used to evaluate three representative contemporary teleoperation interfaces. The results indicate that teleoperation via human motion mapping outperforms the gamepad and stylus interfaces. The tradeoff with using motion mapping as a teleoperation interface is the non-trivial physical fatigue. To understand the impact of heavy physical demand during motion mapping teleoperation, we propose an objective assessment of physical workload in teleoperation using electromyography. We find that physical fatigue happens in the actions that involve precise manipulation and steady posture maintenance. We further implemented teleoperation assistance in the form of shared autonomy to eliminate the fatigue-causing component in robot teleoperation via motion mapping. The experimental results show that the autonomous feature effectively reduces the physical effort while improving the efficiency and accuracy of the teleoperation interface.

Synergistic Interaction of MoS2 Nanoflakes on La2Zr2O7 Nanofibers for Improving Photoelectrochemical Nitrogen Reduction.

Ammonia is a suitable hydrogen carrier with each molecule accounting for up to 17.65% of hydrogen by mass. Among various potential ammonia production methods, we adopt the photoelectrochemical (PEC) technique, which uses solar energy as well as electricity to efficiently synthesize ammonia under ambient conditions. In this article, we report MoS2@La2Zr2O7 heterostructures designed by incorporating two-dimensional (2D)-MoS2 nanoflakes on La2Zr2O7 nanofibers (MoS2@LZO) as photoelectrocatalysts. The MoS2@LZO heterostructures are synthesized by a facile hydrothermal route with electrospun La2Zr2O7 nanofibers and Mo precursors. The MoS2@LZO heterostructures work synergistically to amend the drawbacks of the individual MoS2 electrocatalysts. In addition, the harmonious activity of the mixed phase of pyrochlore/defect fluorite-structured La2Zr2O7 nanofibers generates an interface that aids in increased electrocatalytic activity by enriching oxygen vacancies in the system. The MoS2@LZO electrocatalyst exhibits an enhanced Faradaic efficiency and ammonia yield of approximately 2.25% and 10.4 μg h-1 cm-2, respectively, compared to their corresponding pristine samples. Therefore, the mechanism of improving the PEC ammonia production performance by coupling oxygen-vacant sites to the 2D-semiconductor-based electrocatalysts has been achieved. This work provides a facile strategy to improve the activity of PEC catalysts by designing an efficient heterostructure interface for PEC applications.

Bioinspired structural silicone rubber composites with high thermal conductivity based on vertically aligned hybrid filler film

To improve the capability of thermal management of thermal conductive silicone rubber (SR) composites, a novel strategy to prepare SR composites with vertically aligned graphene/silicon carbide crystal whisker (SiC) hybrid film was proposed inspired by the typical architecture of the annual rings of trees. Frist of all, a SR/graphene-SiC bilayer film was prepared through drying SR solution and aqueous filler dispersion in turn. Then the bilayer film was rolled and subsequently cured to form SR composite. Poly(ethylene glycol) grafted poly(methylhydrosiloxane-co-dimethylsiloxane) was newly synthesized and used to enhance the interfacial interaction between SR and filler film. The bioinspired structural graphene/SiC/SR composite exhibited a very high thermal conductivity of 6.72 W/(m·K). The composite was determined to be an efficient thermal interface material to reduce the working temperature of light emitting diode, clearly showing the excellent thermal management capability of the obtained SR composites.

Oxaspiro Indiculides from Old Woman Octopus Cistopus indicus as Dual Inhibitors of Inducible Cyclooxygenase and Lipoxygenase.

The organic extract of the old woman octopus Cistopus indicus (Octopodidae), ubiquitous in the Central and South Indo-Pacific to the tropical Indian Ocean, was chromatographically fractionated over a reverse-phase adsorbent to yield two oxygenated spiro heterocyclic compounds, named indiculides A and B. Their structures were elucidated by using comprehensive spectroscopic methods. The radical scavenging potential displayed by indiculide A (IC50 ∼1.2 mM) besides attenuating the cyclooxygenase isoforms (COX-1/COX-2; IC50 3.36/3.02 μM) showed considerably superior activities when equated to those showed by indiculide B (IC50 3.45/3.22 μM). The inhibition property of indiculide A against 5-LOX (IC50 2.57 μM) was significantly greater than that of the standard 5-LOX inhibitor zileuton (IC50 3.70 μM, p<0.05). A greater selectivity index (anti-COX-1/anti-COX-2, 1.11) was perceived for indiculide A than that demonstrated by indiculide B (1.07) and anti-inflammatory drug diclofenac (0.96). Structure bio-activity relation study of indiculide A disclosed proportionality to the electronic properties besides permissible hydrophobicity-lipophilicity equilibrium, which could result in its efficient interface with the active site of inflammatory enzyme causing promising anti-inflammatory potential. Larger hydrogen bond networks of indiculide A on account of the more electronic-rich centers in conjunction with reduced docking factors reinforced its noteworthy attenuation potential against 5-LOX. The in vitro bioactivity assessment and in silico docking results were further validated by the superior drug-like characteristics of indiculide A (drug-likeness score, 0.21) than B analog, and therefore, the former metabolite could be a potential anti-inflammatory lead.

The preparation of NiCo2O4 nanoboulders and their application in the electrochemical detection of ofloxacin drug

A sensitive electroactive platform relies directly upon the efficient and conductive interface. This work offers a simple and effective method for synthesizing NiCo2O4 using CTAB surfactant, suited for trace-level antibiotic detection. The route realized the controlled growth of tiny NiCo2O4 nanoboulders with an exposed interface. A comparative evaluation of the bimetallic nanostructures with their pristine compositional counterparts, i.e., NiO and Co3O4, supports its superior electrochemical characteristics based on the synergism of strong redox activity and conductivity from the bimetallic components. The NiCo2O4 nanoboulders exhibited strong electrochemical activity when configured as electrode material for detecting ofloxacin (OFL), a common antibiotic. The sensor exhibited excellent working linearity in a low-concentration range of 0.01–5 ​μM with a detection limit of 1 ​× ​10−3 ​μM for OFL. The kinetics of the NiCo2O4 further supported the electrocatalytic oxidation of OFL to be diffusion controlled with an estimated diffusion coefficient of 2.03310−6 ​cm2 ​s−1. Moreover, the constructed sensor is applicable for detecting OFL from environmental samples, reflecting its workability in complex real-environment.

In-situ constructing cobalt incorporated nitrogen-doped carbon/CdS heterojunction with efficient interfacial charge transfer for photocatalytic hydrogen evolution

Designing an efficient heterojunction interface is an effective way to promote the electrons' transfer and improve the photocatalytic H2 evolution performance. In this work, a novel hollow hybrid system of Co@NC/CdS has been fabricated and constructed. CdS nanospheres are anchored on the hollow-structured cobalt incorporated nitrogen-doped carbon (Co@NC) through a one-pot in-situ chemical deposition approach, forming an intimate interface and establishing an excellent channel to improve the electrons transfer and charge carriers separation between CdS and Co@NC cocatalyst, which immensely promotes the photocatalytic activity. The rate of photocatalytic H2 evolution over hollow structured Co@NC/CdS heterojunction can be achieved 8.2 mmol g−1 h−1, which is about 45 times of pristine CdS nanospheres. The photocatalytic H2 evolution mechanism has been investigated by the techniques of photoluminescence (PL) spectra, photocurrent-time (i-t) curves, electrochemical impedance spectroscopy (EIS) etc. This work aims to provide a new way in developing of high-performance advanced 3D heterojunction for photocatalytic hydrogen evolution.

Low-loss fiber grating coupler on thin film lithium niobate platform

A grating coupler with a high coupling efficiency and low back reflections is designed and demonstrated on the thin film lithium niobate platform, which facilitates an efficient interface between a lithium niobate ridge waveguide and a standard single mode fiber. The excellent performances of the present grating coupler are enabled by a cavity-assisted grating structure and a top metal mirror, even though a uniform grating is adopted as the diffractive element. Experimentally, a coupling loss of −0.89 dB at 1552 nm is demonstrated with a 1-dB bandwidth of 45 nm. Low back reflections of &amp;lt;−16.5 dB to the waveguide and &amp;lt;−13.7 dB to the fiber are also achieved from 1536 to 1579 nm.

Graphene Substrates Promote the Differentiation of Inner Ear Lgr5+ Progenitor Cells Into Hair Cells.

The ideal treatment for sensory hearing loss is to regenerate inner ear hair cells (HCs) through stem cell therapy, thereby restoring the function and structure of the cochlea. Previous studies have found that Lgr5+ supporting cells (SCs) in the inner ear can regenerate HCs, thus being considered inner ear progenitor cells. In addition to traditional biochemical factors, physical factors such as electrical conductivity also play a crucial role in the regulation of stem cell proliferation and differentiation. In this study, the graphene substrates were used to culture Lgr5+ progenitor cells and investigated their regulatory effects on cells. It was demonstrated that the graphene substrates displayed great cytocompatibility for Lgr5+ progenitors and promoted their sphere-forming ability. Moreover, more Myosin7a+ cells were found on the graphene substrates compared with tissue culture polystyrene (TCPS). These results suggest that graphene is an efficient interface that can promote the differentiation of Lgr5+ progenitors into HCs, which is great significance for its future application in combination with Lgr5+ cells to regenerate HCs in the inner ear.

Efficient interface engineering on the NiO/FeCo2O4 electrode for boosting photo-assisted supercapacitor performance

Photo-assisted energy storage devices provide an appropriate way to recognize the utilization of the unlimited solar energy. Herein, we construct the photoresponsive heterogeneous interfaces between NiO and FeCo2O4 to improve the performance for photo-assisted supercapacitor. As expected, the NiO/FeCo2O4 electrodes exhibit ultrahigh energy storage capacity of 7933 F g−1 at 1 A g−1 irradiating by simulated sunlight. In addition, a NiO/FeCo2O4//AC asymmetric supercapacitor is assembled, whose energy density is enhanced from 35.6 Wh kg−1 to 61.9 Wh kg−1 at the power density of 1.5 kW kg−1 under light. Combining with density functional theory (DFT) calculations, it is discovered that the photo-generated electrons would transfer from NiO to FeCo2O4, and then inject into the external circuit. Meanwhile, the photo-generated holes participate the charging process. This work provides a theoretical basis for effectively building heterogeneous interfaces to storage the abundant solar energy.

Interfacial modification between glass fiber and polypropylene using a novel waterborne amphiphilic sizing agent

High performance structural applications of utilizing glass fiber (GF) reinforced polypropylene (PP) composites are normally hindered by the notoriously weak interfacial bonding between GF and PP resulting from their chemical inertness and the great mismatch in surface energies of both raw materials. Tremendous efforts have been made on the development of fiber sizing agents for interfacial modifications of GF-PP composites, since a viable sizing agent can directly build robust and efficient coupling interface between GF and PP, enabling effective stress transfer between fiber and matrix. Herein, this paper reports an interfacial modification methodology of using a novel amphiphilic sizing agent that is a polyacrylate-based waterborne coating synthesized strategically following a one-step reversible addition-fragmentation chain-transfer (RAFT)-mediated polymerization-induced self-assemble (PISA) approach. Specifically, after the proposed sizing treatment the surface energy of the sized GF surface decreases from 74.51 mJ·m−2 (of the typical pristine GF surface) to 56.43 mJ·m−2, approaching to 30.2 mJ·m−2 (of the raw PP) and enabling strong possibility of facilitating GF-PP interfacial compatibility. Additionally, the GF-PP interfacial shear strength (IFSS) evaluated by single-fiber fragmentation tests increases from 8.34 MPa (for bare GF) and 11.14 MPa (for commercial GF) to 17.62 MPa for the sized GF. Notably, a series of the sized short GF/PP composite coupons were fabricated and demonstrates promoted tensile and flexural properties, validating the effectiveness and scalability of the proposed GF/PP interfacial treatment. We believe that this amphiphilic polyacrylate-based sizing agent can serve as an effective GF-PP interfacial modifier, offering great potential for practical applications of developing high performance GF-PP composites.

Enabling research capacity strengthening within a consortium context: a qualitative study

IntroductionWe explore how health research consortia may be better structured to support research capacity strengthening (RCS) outcomes. The primary research questions include: in what ways do consortium members perceive that...

Identification of Twitter Bots Based on an Explainable Machine Learning Framework: The US 2020 Elections Case Study

Twitter is one of the most popular social networks attracting millions of users, while a considerable proportion of online discourse is captured. It provides a simple usage framework with short messages and an efficient application programming interface (API) enabling the research community to study and analyze several aspects of this social network. However, the Twitter usage simplicity can lead to malicious handling by various bots. The malicious handling phenomenon expands in online discourse, especially during the electoral periods, where except the legitimate bots used for dissemination and communication purposes, the goal is to manipulate the public opinion and the electorate towards a certain direction, specific ideology, or political party. This paper focuses on the design of a novel system for identifying Twitter bots based on labeled Twitter data. To this end, a supervised machine learning (ML) framework is adopted using an Extreme Gradient Boosting (XGBoost) algorithm, where the hyper-parameters are tuned via cross-validation. Our study also deploys Shapley Additive Explanations (SHAP) for explaining the ML model predictions by calculating feature importance, using the game theoretic-based Shapley values. Experimental evaluation on distinct Twitter datasets demonstrate the superiority of our approach, in terms of bot detection accuracy, when compared against a recent state-of-the-art Twitter bot detection method.

SEMG-Based Gesture Classifier for a Rehabilitation Glove

Human hand gesture recognition from surface electromyography (sEMG) signals is one of the main paradigms for prosthetic and rehabilitation device control. The accuracy of gesture recognition is correlated with the control mechanism. In this work, a new classifier based on the Bayesian neural network, pattern recognition networks, and layer recurrent network is presented. The online results obtained with this architecture represent a promising solution for hand gesture recognition (98.7% accuracy) in sEMG signal classification. For real time classification performance with rehabilitation devices, a new simple and efficient interface is developed in which users can re-train the classification algorithm with their own sEMG gesture data in a few minutes while enables shape memory alloy-based rehabilitation device connection and control. The position of reference for the rehabilitation device is generated by the algorithm based on the classifier, which is capable of detecting user movement intention in real time. The main aim of this study is to prove that the device control algorithm is adapted to the characteristics and necessities of the user through the proposed classifier with high accuracy in hand gesture recognition.

Quantum frequency conversion with coherent transfer of time-bin encoding

Time-bin encoding of photons offers a robust kind of long-distance quantum communication over lossy channels. The diversity of material nodes in quantum networks operating at natural frequencies requires coherent frequency and wave-form conversion of information-carrying photons to provide an efficient quantum interface with optical fibers and various quantum memories, which has been extensively studied. However, the quantum frequency conversion with transfer of time-bin encoding between single photons of different wavelengths has not yet been explored. In this paper, we present a method for efficiently exchanging time-bin encoding in the conversion process between two photons propagating in cold tripod atoms driven by a strong laser field. The latter is designed to slow down photons and suppress their absorption due to electromagnetically induced transparency. Photons interact parametrically through modified atomic coherence, which is utilized also to achieve equal group velocities of photons. We demonstrate the ability of our model to generate entanglement between distant atoms that equally share the original quantum information stored in the ground-state polarization qubits of both atoms. The proposed method for frequency conversion based on modified atomic coherence is promising because it can simplify the implementation of reliable and high-speed quantum communication protocols based on single-photon entanglement.

Efficient self-powered piezoelectric energy harvesting interface circuit with wide rectified voltage

Synchronized Switching Harvesting on Inductor (SSHI) and Synchronous Electric Charge Extraction (SECE) are two classic interface circuit techniques for Piezoelectric energy harvesting. But the former has high peak output power with narrow rectified voltage range, while the latter has wide rectified voltage range with lower peak output power. This paper presents a self-powered interface circuit for piezoelectric energy harvesting to achieve a good balance between the two. The proposed interface circuit is based on the Series-SSHI (S–SSHI) and SECE. The circuit proposed can harvest energy through S–SSHI and SECE in positive and negative half cycles, respectively. Moreover, the figure of merit (FOM), optimal rectified voltage range (ORVR) and region of interest (SRoI) of simulation and experiment results are discussed. The maximum FOM of the proposed circuit is as high as 2.15, which is 1.68 times that of the SECE, and it can reach 6 times the ORVR of the S–SSHI. SRoI factor of the proposed circuit show that the proposed method has better performance. In addition, the circuit shows a simpler implementation compared with state-of-the-art designs.