Fe-lnduced Electronic Transfer and Structural Evolution of Lotus Pod-Like CoNiFeP_(x)@P,N-C Heterostructure for Sustainable Oxygen Evolution

Transition metal phosphides with metallic properties are a promising candidate for electrocatalytic water oxidation,and developing highly active and stable metal phosphide-based oxygen evolution reaction catalysts is still challenging.Herein,we present a facile ion exchange and phosphating processes to transform intestine-like CoNiP_(x)@P,N-C into lotus pod-like CoNiFeP_(x)@P,N-C heterostructure in which numerous P,N-codoped carboncoated CoNiFeP_(x)nanoparticles tightly anchors on the 2D carbon matrix.Meanwhile,the as-prepared CoNiFeP_(x)@P,N-C enables a core-shell structure,high specific surface area,and hierarchical pore structure,which present abundant heterointerfaces and fully exposed active sites.Notably,the incorporation of Fe can also induce electron transfer in CoNiP_(x)@P,IM-C,thereby promoting the oxygen evolution reaction.Consequently,CoNiFeP_(x)@P,IM-C delivers a low overpotential of 278 mV(vs RHE)at a current density of10 mA cm^(-1)and inherits excellent long-term stability with no observable current density decay after 30 h of chronoamperometry test.This work not only highlights heteroatom induction to tune the electronic structure but also provides a facile approach for developing advanced and stable oxygen evolution reaction electrocatalysts with abundant heterointerfaces.

An Analytical Study of Variable Preamble Length-Based Broadcasting Scheme for WSNs

In this paper, we present a detailed analytical study of previously proposed variable preamble length-based broadcasting scheme for wireless sensor networks (WSNs). Analytical results show that in dense wireless sensor networks, broadcasting a packet with a small size preamble can significantly improve the energy conservation on already limited battery powered sensor nodes. For fairer comparison with variable preamble length-based broadcasting scheme, a comprehensive analytical study for an existing probability-based broadcasting scheme is also presented. Analytically calculated results show that variable preamble length-based broadcasting scheme is more energy-efficient than the probability-based broadcasting scheme.

Elevated brain temperature under severe heat exposure impairs cortical motor activity and executive function

Background:Excessive heat exposure can lead to hyperthermia in humans,which impairs physical performance and disrupts cognitive function.While heat is a known physiological stressor,it is unclear how severe heat stress affects brain physiology and function.Methods:Eleven healthy participants were subjected to heat stress from prolonged exercise or warm water immersion until their rectal temperatures(T_(re))attained 39.5℃,inducing exertional or passive hyperthermia,respectively.In a separate trial,blended ice was ingested before and during exercise as a cooling strategy.Data were compared to a control condition with seated rest(normothermic).Brain temperature(T_(br)),cerebral perfusion,and task-based brain activity were assessed using magnetic resonance imaging techniques.Results:T_(br)in motor cortex was found to be tightly regulated at rest(37.3℃±0.4℃(mean±SD))despite fluctuations in T_(re).With the development of hyperthermia,T_(br)increases and dovetails with the rising T_(re).Bilateral motor cortical activity was suppressed during high-intensity plantarflexion tasks,implying a reduced central motor drive in hyperthermic participants(T_(re)=38.5℃±0.1℃).Global gray matter perfusion and regional perfusion in sensorimotor cortex were reduced with passive hyperthermia.Executive function was poorer under a passive hyperthermic state,and this could relate to compromised visual processing as indicated by the reduced activation of left lateral-occipital cortex.Conversely,ingestion of blended ice before and during exercise alleviated the rise in both T_(re)and T_(bc)and mitigated heat-related neural perturbations.Conclusion:Severe heat exposure elevates T_(br),disrupts motor cortical activity and executive function,and this can lead to impairment of physical and cognitive performance.

Location-Based Routing Protocols for Wireless Sensor Networks: A Survey

Recently, location-based routings in wireless sensor networks (WSNs) are attracting a lot of interest in the research community, especially because of its scalability. In location-based routing, the network size is scalable without increasing the signalling overhead as routing decisions are inherently localized. Here, each node is aware of its position in the network through some positioning device like GPS and uses this information in the routing mechanism. In this paper, we first discuss the basics of WSNs including the architecture of the network, energy consumption for the components of a typical sensor node, and draw a detailed picture of classification of location-based routing protocols. Then, we present a systematic and comprehensive taxonomy of location-based routing protocols, mostly for sensor networks. All the schemes are subsequently discussed in depth. Finally, we conclude the paper with some insights on potential research directions for location-based routing in WSNs.

Challenges and optimization strategies in medical imaging service delivery during COVID-19

In coronavirus disease 2019(COVID-19),medical imaging plays an essential role in the diagnosis,management and disease progression surveillance.Chest radiography and computed tomography are commonly used imaging techniques globally during this pandemic.As the pandemic continues to unfold,many healthcare systems worldwide struggle to balance the heavy strain due to overwhelming demand for healthcare resources.Changes are required across the entire healthcare system and medical imaging departments are no exception.The COVID-19 pandemic had a devastating impact on medical imaging practices.It is now time to pay further attention to the profound challenges of COVID-19 on medical imaging services and develop effective strategies to get ahead of the crisis.Additionally,preparation for operations and survival in the post-pandemic future are necessary considerations.This review aims to comprehensively examine the challenges and optimization of delivering medical imaging services in relation to the current COVID-19 global pandemic,including the role of medical imaging during these challenging times and potential future directions post-COVID-19.

Microbe-derived carbon materials for electrical energy storage and conversion

Microbes are microscopic living organisms that surround us which include bacteria, archaea, most protozoa, and some fungi and algae. In recent years, microbes have been explored as novel precursors to synthesize carbon-based（nano）materials and as substrates or templates to produce carbon-containing（nano）composites. Being greener and more affordable, microbe-derived carbons（MDCs） offer good potential for energy applications. In this review, we describe the unique advantages of MDCs and outline the common procedures to prepare them. We also extensively discuss the energy applications of MDCs including their use as electrodes in supercapacitors and lithium-ion batteries, and as electrocatalysts for processes such as oxygen reduction, oxygen evolution, and hydrogen evolution reactions which are essential for fuel cell and water electrochemical splitting cells. Based on the literature trend and our group＇s expertise, we propose potential research directions for developing new types of MDCs. This review, therefore, provides the state-of-the-art of a new energy chemistry concept. We expect to stimulate future research on the applications of MDCs that may address energy and environmental challenges that our societies are facing.

Burnout syndrome and anxiety among healthcare workers during global pandemics:An umbrella review

BACKGROUND Burnout syndrome and anxiety are two mental health symptoms experienced by healthcare workers(HCWs)that can be exacerbated during pandemics due to increased job demands and the global health workforce crisis.AIM To provide a comprehensive review and summary of evidence on burnout and anxiety in HCWs during previous global pandemics.METHODS A systematic search on electronic databases such as PubMed Central and MEDLINE was conducted to identify high-quality systematic review studies that reported on the prevalence of burnout and/or anxiety in HCWs during any previous global pandemic.RESULTS Twenty-four high quality systematic review articles were found to be suitable for inclusion.Twenty articles focused merely on Coronavirus disease 2019,while four articles examined multiple pandemics.Burnout was examined in nine articles,while anxiety was examined in the remaining 21 articles.Female HCWs and nurses were identified to be at a higher risk of developing burnout and anxiety during pandemic.We also observed a variation in the prevalence of burnouts and anxiety across different studies due to different mental health instruments were used in different studies.CONCLUSION Nurses and females HCWs had a high prevalence of burnout syndrome and anxiety during pandemic.More emphasis and attention should be paid to safeguarding the psychological well-being of these at-risk populations in the future pandemics.

VEGO:A novel design towards customizable and adjustable head-mounted display for VR

Background Virtual Reality(VR)technologies have advanced fast and have been applied to a wide spectrum of sectors in the past few years.VR can provide an immersive experience to users by generating virtual images and displaying the virtual images to the user with a head-mounted display(HMD)which is a primary component of VR.Normally,an HMD contains a list of hardware components,e.g.,housing pack,micro LCD display,microcontroller,optical lens,etc.Settings of VR HMD to accommodate the user's inter-pupil distance(IPD)and the user's eye focus power are important for the user's experience with VR.Methods Although various methods have been developed towards IPD and focus adjustments for VR HMD,the increased cost and complexity impede the possibility for users who wish to assemble their own VR HMD for various purposes,e.g.,DIY teaching,etc.In our paper,we present a novel design towards building a customizable and adjustable HMD for VR in a cost-effective manner.Modular design methodology is adopted,and the VR HMD can be easily printed with 3D printers.The design also features adjustable IPD and variable distance between the optical lens and the display.It can help to mitigate the vergence and accommodation conflict issue.Results A prototype of the customizable and adjustable VR HMD has been successfully built up with off-the-shelf components.A VR software program running on Raspberry Pi board has been developed and can be utilized to show the VR effects.A user study with 20 participants is conducted with positive feedback on our novel design.Conclusions Modular design can be successfully applied for building up VR HMD with 3D printing.It helps to promote the wide application of VR at affordable costs while featuring flexibility and adjustability.

An integrated approach for machine-learning-based system identification of dynamical systems under control:application towards the model predictive control of a highly nonlinear reactor system

Advanced model-based control strategies,e.g.,model predictive control,can offer superior control of key process variables for multiple-input multiple-output systems.The quality of the system model is critical to controller performance and should adequately describe the process dynamics across its operating range while remaining amenable to fast optimization.This work articulates an integrated system identification procedure for deriving black-box nonlinear continuous-time multiple-input multiple-output system models for nonlinear model predictive control.To showcase this approach,five candidate models for polynomial and interaction features of both output and manipulated variables were trained on simulated data and integrated into a nonlinear model predictive controller for a highly nonlinear continuous stirred tank reactor system.This procedure successfully identified system models that enabled effective control in both servo and regulator problems across wider operating ranges.These controllers also had reasonable per-iteration times of ca.0.1 s.This demonstration of how such system models could be identified for nonlinear model predictive control without prior knowledge of system dynamics opens further possibilities for direct data-driven methodologies for model-based control which,in the face of process uncertainties or modelling limitations,allow rapid and stable control over wider operating ranges.

Power enhancement of pontoon-type wave energy convertor via hydroelastic response and variable power take-off system

Wave energy has gained its popularity in recent decades due to the vast amount of untapped wave energy resources.There are numerous types of wave energy convertor(WEC)being proposed and to be economically viable,various means to enhance the power generation from WECs have been studied and investigated.In this paper,a novel pontoon-type WEC,which is formed by multiple plate-like modules connected by hinges,are considered.The power enhancement of this pontoon-type WEC is achieved by allowing certain level of structural deformation and by utilizing a series of optimal variable power take-off(PTO)system.The wave energy is converted into useful electricity by attaching the PTO systems on the hinge connectors such that the mechanical movements of the hinges could produce electricity.In this paper,various structural rigidity of the interconnected modules are considered by changing the material Young’s modulus in order to investigate its impact on the power enhancement.In addition,the genetic algorithm optimization scheme is utilized to seek for the optimal PTO damping in the variable PTO system.It is observed that under certain condition,the flexible pontoon-type WEC with lesser connection joints is more effective in generating energy as compared to its rigid counterpart with higher connection joints.It is also found that the variable PTO system is able to generate greater energy as compared to the PTO system with constant/uniform PTO damping.

Data learning and expert judgment in a Bayesian belief network for aiding human reliability assessment in offshore decommissioning risk assessment

Decommissioning of offshore facilities involve changing risk profiles at different decommissioning phases.Bayesian Belief Networks(BBN)are used as part of the proposed risk assessment method to capture the multiple interactions of a decommissioning activity.The BBN is structured from the data learning of an accident database and a modification of the BBN nodes to incorporate human reliability and barrier performance modelling.The analysis covers one case study of one area of decommissioning operations by extrapolating well workover data to well plugging and abandonment.Initial analysis from well workover data,of a 5-node BBN provided insights on two different levels of severity of an accident,the’Accident’and’Incident’level,and on its respective profiles of the initiating events and the investigation-reported human causes.The initial results demonstrate that the data learnt from the database can be used to structure the BBN,give insights on how human reliability pertaining to well activities can be modelled,and that the relative frequencies from the count analysis can act as initial data input for the proposed nodes.It is also proposed that the integrated treatment of various sources of information(database and expert judgement)through a BBN model can support the risk assessment of a dynamic situation such as offshore decommissioning.

Energy-efficient control of nanosatellites during distributed region formation flying

In this paper, we present an energy-efficient method for distributed region formation flying of nanosatellites. The proposed framework consists of two concurrent sub-schemes that include estimation and formation. In the estimation sub-scheme, unlike the existing methods on satellite formation flying, that assume the availability of the reference orbital elements to all followers, here, a distributed estimator is developed so that the follower nanosatellites estimate the position of the leader in its orbital slot. In the formation sub-scheme, we consider a region formation strategy which is an efficient method in dealing with the formation of a large number of nanosatellites. We propose an optimal region following formation method based on the receding horizon control （RHC） using the estimated reference orbital elements. Subsequently, an algorithm is presented to solve the proposed energy-efficient formation flying method. Finally, the simulation result is presented that illustrates the purposed method improves the power consumption for each nanosatellite with respect to the existing non-optimal region formation flying controllers.

DroidEcho:an in-depth dissection of malicious behaviors in Android applications

A precise representation for attacks can benefit the detection of malware in both accuracy and efficiency.However,it is still far from expectation to describe attacks precisely on the Android platform.In addition,new features on Android,such as communication mechanisms,introduce new challenges and difficulties for attack detection.In this paper,we propose abstract attack models to precisely capture the semantics of various Android attacks,which include the corresponding targets,involved behaviors as well as their execution dependency.Meanwhile,we construct a novel graph-based model called the inter-component communication graph(ICCG)to describe the internal control flows and inter-component communications of applications.The models take into account more communication channel with a maximized preservation of their program logics.With the guidance of the attack models,we propose a static searching approach to detect attacks hidden in ICCG.To reduce false positive rate,we introduce an additional dynamic confirmation step to check whether the detected attacks are false alarms.Experiments show that DROIDECHO can detect attacks in both benchmark and real-world applications effectively and efficiently with a precision of 89.5%.

Ternary nanoparticle complex of ciprofloxacin exhibiting sustained release at gastric pH prepared by co-complexation with polyanions and an ionic amphiphile

Poor bioavailability of the broad spectrum antibiotic ciprofloxacin (CIP) is caused by its narrow absorption window in the stomach. With the aim of prolonging the gastric reside nee time of CIP, we prepared a ternary nano particle complex (nan oplex) of CIP by co-complexation w ith polya nions (sodium dextran sulfate (DXT)) and an anionic amphiphile (sodium dodecyl sulfate (SDS)). We investigated the effect of the charge ratio of DXT to SDS on the size, zeta potential, CIP payload, and CIP utilization rate of the CIP-DXTSDS nanoplex and its dissolution characteristics in simulated gastrointestinal fluids. Fourier transform infrared spectroscopy, powder X-ray diffraction, and differential scanning calorimetry analyses showed that the ternary nanoplex was made up of amorphous C1P-DXT and crystalline CIP-SDS complexes. The size of the CIP-DXT-SDS nanoplex prepared at a >90% CIP utilization rate was 110-290 nm and it had a zeta potential of -16-39 mV, and CIP payload of 47-62%, depending on the charge ratio. At gastric pH, the CIP-DXT-SDS nanoplex prepared with a DXT:SDS charge ratio lower than 80:20 exhibited prolonged CIP release (60% dissolution after 8 h) compared with native CIP (100% dissolution after 1 h) and a binary CIP-DXT nanoplex (80% dissolution after 5 h), which was attributed to its lower solubility. The sustained release characteristics of the CIP-DXT-SDS nanoplex were comparable to those of existing CIP gastrorete ntive formulations.

Synthesizing molecularly imprinted polymer beads for the purification of vitamin E

Molecularly imprinted polymer(MIP)beads imprinted with vitamin E(V_(E))were synthesized via a two-step swelling polymerization method,using methacrylic acid(MAA)and other functional monomers together with polystyrene(PS)microspheres as the substrate.In initial trials,different functional monomers were assessed,along with a variety of solvents and imprinting ratios.The MIP_(MAA) sample exhibited the highest performance and was characterized and also assessed with regard to V_(E) adsorption under various experimental conditions.This material exhibited reasonably good sphericity,porosity and stability,along with an excellent adsorption capacity of 46 mg/g.This was much higher than the value for the corresponding non-imprinted polymer made with the same monomer,and 20%higher than that for an acrylamide-based MIP synthesized using a precipitation polymerization method.The core-shell structured MIP_(MAA) also demonstrated fast adsorption kinetics,a low pressure drop and good reusability in fixed bed experiments.The V_(E) adsorption equilibrium,selectivity,kinetics,thermodynamics and regeneration capacity of this material were also examined and are reported herein.

Finite element analysis of tibio-femoral contact mechanics of a customised knee spacer

With one-third of patients having osteoarthritis predominantly in one compartment of the knee,unicompartmental knee spacers have been introduced as a less invasive alternative to total knee replacement.However,patients with the knee spacer implanted were seen to have persistent pain,resulting in high revision rates.A static finite element model of the knee and its interaction with a knee spacer implant at full extension and 90°flexion was used to investigate the tibio-femoral contact mechanics of the knee joint after a knee spacer surgery.Three different knee spacer designs(contoured,flat and C-shaped)were modelled and prescribed with cobalt-chrome,ultra-high molecular polyethylene and polyurethane material properties.The results suggested that a softer spacer is generally preferred as this helps in the conformity of knee spacer to the condyle,effectively distributing the load subjected to the implant.Flat spacers that result in high stresses resulting from lower contact areas should be avoided.

Biomechanical analysis of the placement of fixation lag screw in different intertrochanteric hip fracture angles

The common surgical method for fracture fixation in the femoral neck and intertrochanteric region is the implantation a dynamic lag screw into the femoral head.However,failure rates of this fixation are high due to a cut-out of the lag screw from the femoral head.It is unclear if the lag screw positions will affect the stabilisation of the intertrochanteric fracture with different fracture angles.This study aimed to examine the influence of lag screw placement in the fixation of hip fractures with different fracture angles in healthy and osteoporotic femurs using three-dimensional finite element analysis.Two screw positions at the centre and inferior-posterior(IP)of the femoral head with three fracture angles(30°,45°,60°)were studied.The results showed that varying fracture angles and the onset of disease(osteoporosis)have influenced the optimal placement of the lag screw.The lag screw in the IP position in the healthy femur with 30°and 45°fracture angles and osteoporotic femur with 30°fracture angle induced lower periprosthetic bone strains.For a healthy femur with 60°fracture angle and osteoporotic bone with 45°and 60°fracture angles,a centralised placement of the lag screw in the femoral neck was preferred.

A chemotaxis model to explain WHIM neutrophil accumulation in the bone marrow of WHIM mouse model

Neutrophils are essential immune cells that defend the host against pathogenic microbial agents.Neutrophils are produced in the bone marrow and are retained there through CXCR4–CXCL12 signaling.However,patients with the Warts,Hypogammaglobulinemia,Infections,and Myelokathexis(WHIM)syndrome are prone to infections due to increased accumulation of neutrophils in the bone marrow leading to low numbers of circulating neutrophils.How neutrophils accumulate in the bone marrow in this condition is poorly understood.To better understand factors involved in neutrophil accumulation in the bone marrow,neutrophils from wildtype and WHIM mouse models were characterized in their response to CXCL12 stimulation.WHIM neutrophils were found to exert stronger traction forces,formed significantly more lamellipodia-type protrusions and migrated with increased speed and displacement upon CXCL12 stimulation as compared to wildtype cells.Migration speed of WHIM neutrophils showed a larger initial increase upon CXCL12 stimulation,which decayed over a longer time period as compared to wildtype cells.We proposed a computational model based on the chemotactic behavior of neutrophils that indicated increased CXCL12 sensitivity and prolonged CXCR4 internalization adaptation time in WHIM neutrophils as being responsible for increased accumulation in the bone marrow.These findings provide a mechanistic understanding of bone marrow neutrophil accumulation in WHIM condition and novel insights into restoring neutrophil regulation in WHIM patients.

Vibration-Damping technology in tennis racquets:Effects on vibration transfer to the arm,muscle fatigue and tennis performance

High vibration transfer from a tennis racquet to the player may cause discomfort,and is hypothesized to influence performance and the onset of muscle fatigue.This study examined a racquet with a novel vibration damping technology(VDT)designed to mitigate frame vibration.Racquet vibration,post-impact vibration transfer to the player,arm electromyographic activity and tennis performance were compared to a non-VDT racquet.Nineteen young adult,competitive tennis players hit forehands and serves until near exhaustion on two days;using one of the two racquets each day.Tri-axial accelerometers mounted to racquet shaft,hand and forearm recorded vibration behaviour.Surface electromyography recorded activity of five arm muscles.In comparison to the non-VDT racquet,the VDT design showed:1)A significantly lower mean normalised acceleration signal energy at the racquet during unfatigued play(-40%)and at near exhaustion(-34%),which corresponded to a 20–25%lower signal energy at the hand.2)Reduced signs of arm muscle fatigue at near exhaustion,which was most pronounced in biceps and wrist extensors.3)Players hit 11%more forehands and placed 40%more hits in the target area at near exhaustion.Conclusion:VDT effectively reduces racquet vibration.Initial evidence indicates that it may delay muscle fatigue,which was associated with increased ball placement accuracy.

Special report on the fourth international conference on countermeasures to urban heat island （4th IC2UHI Conference） in Singapore

Initiated by Prof. Hashem Akbari, international conference on countermeasures to urban heat island （IC2UHI Conference） was first held in Tokyo, Japan in year 2006. Subsequently, it was held in Berkeley, USA and Venice, Italy in year 2009 and 2014 respectively.