Triboelectric‘electrostatic tweezers'for manipulating droplets on lubricated slippery surfaces prepared by femtosecond laser processing

The use of‘Electrostatic tweezers'is a promising tool for droplet manipulation,but it faces many limitations in manipulating droplets on superhydrophobic surfaces.Here,we achieve noncontact and multifunctional droplet manipulation on Nepenthes-inspired lubricated slippery surfaces via triboelectric electrostatic tweezers(TETs).The TET manipulation of droplets on a slippery surface has many advantages over electrostatic droplet manipulation on a superhydrophobic surface.The electrostatic field induces the redistribution of the charges inside the neutral droplet,which causes the triboelectric charged rod to drive the droplet to move forward under the electrostatic force.Positively or negatively charged droplets can also be driven by TET based on electrostatic attraction and repulsion.TET enables us to manipulate droplets under diverse conditions,including anti-gravity climb,suspended droplets,corrosive liquids,low-surface-tension liquids(e.g.ethanol with a surface tension of 22.3 mN·m^(-1)),different droplet volumes(from 100 nl to 0.5 ml),passing through narrow slits,sliding over damaged areas,on various solid substrates,and even droplets in an enclosed system.Various droplet-related applications,such as motion guidance,motion switching,droplet-based microreactions,surface cleaning,surface defogging,liquid sorting,and cell labeling,can be easily achieved with TETs.

Joint Flexible Duplexing and Power Allocation with Deep Reinforcement Learning in Cell-Free Massive MIMO System

Network-assisted full duplex(NAFD)cellfree(CF)massive MIMO has drawn increasing attention in 6G evolvement.In this paper,we build an NAFD CF system in which the users and access points(APs)can flexibly select their duplex modes to increase the link spectral efficiency.Then we formulate a joint flexible duplexing and power allocation problem to balance the user fairness and system spectral efficiency.We further transform the problem into a probability optimization to accommodate the shortterm communications.In contrast with the instant performance optimization,the probability optimization belongs to a sequential decision making problem,and thus we reformulate it as a Markov Decision Process(MDP).We utilizes deep reinforcement learning(DRL)algorithm to search the solution from a large state-action space,and propose an asynchronous advantage actor-critic(A3C)-based scheme to reduce the chance of converging to the suboptimal policy.Simulation results demonstrate that the A3C-based scheme is superior to the baseline schemes in term of the complexity,accumulated log spectral efficiency,and stability.

QoS-Aware Offloading Based on Communication-Computation Resource Coordination for 6G Edge Intelligence

Driven by the demands of diverse artificial intelligence(AI)-enabled application,Mobile Edge Computing(MEC)is considered one of the key technologies for 6G edge intelligence.In this paper,we consider a serial task model and design a quality of service(QoS)-aware task offloading via communication-computation resource coordination for multi-user MEC systems,which can mitigate the I/O interference brought by resource reuse among virtual machines.Then we construct the system utility measuring QoS based on application latency and user devices’energy consumption.We also propose a heuristic offloading algorithm to maximize the system utility function with the constraints of task priority and I/O interference.Simulation results demonstrate the proposed algorithm’s significant advantages in terms of task completion time,terminal energy consumption and system resource utilization.

Femtosecond laser direct writing of functional stimulus-responsive structures and applications

Diverse natural organisms possess stimulus-responsive structures to adapt to the surrounding environment.Inspired by nature,researchers have developed various smart stimulus-responsive structures with adjustable properties and functions to address the demands of ever-changing application environments that are becoming more intricate.Among many fabrication methods for stimulus-responsive structures,femtosecond laser direct writing(FsLDW)has received increasing attention because of its high precision,simplicity,true three-dimensional machining ability,and wide applicability to almost all materials.This paper systematically outlines state-of-the-art research on stimulus-responsive structures prepared by FsLDW.Based on the introduction of femtosecond laser-matter interaction and mainstream FsLDW-based manufacturing strategies,different stimulating factors that can trigger structural responses of prepared intelligent structures,such as magnetic field,light,temperature,pH,and humidity,are emphatically summarized.Various applications of functional structures with stimuli-responsive dynamic behaviors fabricated by FsLDW,as well as the present obstacles and forthcoming development opportunities,are discussed.

A MmWave Communication Testbed Based on IEEE 802.11ad with Scalable PtMP Configuration

The sub-6 G band is too crowded to accommodate higher data rate, while the millimeter wave(mmWave) bands have abundant spectrum resources and massive MIMO can provide high spectral and energy efficiency. Therefore, the combination of the two,namely mmWave-MIMO system, has attracted intensive research interests. In this paper, we develop a high-speed mmWave-MIMO communication system and conduct exhaustive field tests. The detail of the system design is provided and the key modules of the testbed are analyzed. The testbed exploits high gain of mmWave RF and flexible configuration of embedded system. The validation and field tests show that the developed testbed can provide up to 2.3 Gbps network layer data rate in single channel with low latency and support point-to-multi-point(PtMP) transmission aided by relay. The testbed can be used in future B5 G and 6 G systems to provide high reliability and low latency wireless coverage.

Clinical evaluation of single or joint of golgi protein 73 and alpha-fetoprotein in hepatocellular carcinoma diagnosing

Objective: The aim of the present study was to further evaluate the clinical value of single or joint of golgi protein 73 (GP73) and alphafetoprotein (AFP) in diagnosis of hepatocellular (HCC). Methods: One hundred and eighteen, 94 and 47 serum samples from the patients with HCC, chronic liver disease (CLD) and liver cirrhosis (LC) were collected, respectively. Serum levels of AFP and GP73 were assayed with commercial kit according to the manufacturer's instructions. Results: Patients with HCC had higher serum concentration of AFP than that of the patients with CLD (P < 0.01), but was similar to that of the patients with LC. Serum GP73 levels in the patients with CLD or LC were significantly lower than that in the patients from HCC group (P < 0.01). Among 118 HCC patients, the positive rate of GP73 and AFP was 80.5% and 48.3%, respectively (P < 0.001). The ROC curve analysis showed that the AUC value of GP73 was higher than that of serum AFP. Moreover, the sensitivity and the accuracy of GP73 were 77.1% and 82.6%, respectively, which were greater more than that of AFP at 90% specificity (28.8% and 59.8%, respectively). The AUC, the sensitivity and the accuracy of GP73 in combination of AFP (AFP/GP73) were 0.855, 78.0% and 83.0%, respectively, which were similar to that of GP73 alone but were much higher than that of the single marker AFP. Conclusion: For HCC diagnosing, GP73 was more sensitive and specific than AFP. The diagnostic value of AFP/GP73 was similar to GP73 but was much higher than AFP.

Evaluation of bacterial contamination on three different surfaces within domestic refrigerators

The objectives of this study were to analyze the number of microorganisms,fungal composition and the correlation between bacterial enrichment and air quality on three internal surfaces(the inner wall,shelf,and basket)of domestic refrigerators.The results showed that the inner wall had a significantly lower number of coliforms(P<0.05),and the range was 0.2−2.5 log MPN cm^(-2).The total bacterial counts and psychrophilic bacterial counts on three internal surfaces in the same refrigerator tended to be consistent.Moreover,the inner wall owned a simpler bacterial community structure.At the genus level of fungi,the dominant flora of both the inner wall and shelf were Saccharomyces spp.and Candida spp.,while Saccharomyces spp.,Candida spp.and Fistulina spp.took superiority in the basket.Specifically,Shannon index and Simpson index,which represent the bacterial community diversity,were the lowest on the wall,and six bacterial species on the inner wall had relative abundance higher than 0.5%of the total operational taxonomic units(OTUs),while for the shelf and basket,there were 12 and 11 bacterial species respectively.Also,there was a significant negative correlation in the basket between the chao1 index and PM2.5.This study could provide guidance for the sanitation and recommend adequate packaging of foods stored in refrigerators.

Carbon capture in power sector of China towards carbon neutrality and its comparison to renewable power

CO_(2)capture from coal power plants is an important and necessary solution to realizing carbon neutrality in China,but ccs demonstration deployment in power sector is far behind expectations.Hence,the reduction potential of energy consumption and cost for CcS and its competitiveness to renewable powers are very important to make roadmaps and policies toward carbon neutrality.Unlike the popular recognition that capturing CO_(2)from flue gases is technically and commercially mature,this paper notes that it has been proved to be technically feasible but far beyond technology maturity and high energy penalty leads to its immaturity and therefore causes high cost.Additionally,the potential energy penalty reduction of capture is investigated thermodynamically,and future CO_(2)avoidance cost is predicted and compared to renewable power(solar PV and onshore wind power).Results show that energy penalty for CO_(2)capture can be reduced by 48%-57%.When installation capacity reaches a similar scale to that of solar PV in China(250 GW),CO_(2)capture cost in coal power plants can be reduced from the current 28-40 USs/ton to 10-20 USs/ton,and efficiency upgrade contributes to 67%-75%in cost reduction for high coal price conditions.In China,CO_(2)capture in coal power plants can be cost competitive with solar PV and onshore wind power.But it is worth noting that the importance and share of CCS role in CO_(2)emission reduction is decreasing since renewable power is already well deployed and there is still a lack of large-scale CO_(2)capture demonstrations in China.Innovative capture technologies with low energy penalties need to be developed to promote Ccs.Results in this work can provide informative references for making roadmaps and policies regarding CO_(2)emission reductions that contribute towards carbon neutrality.

All-optical driven soft crawler with complexmotion capabilities

The emergence of millimeter-scale soft actuators has signifi-cantly expanded the potential applications in areas such as search and rescue,drug delivery,and human assistance,due to their high flexibility.Despite these advancements,achieving precise control over the intricate movements of soft crawlers poses a significant challenge.In this study,we have developed an all-optical approach that enables manipulation of propul-sive forces by simultaneously modifying the magnitude and direction of friction forces,thereby enabling complex motions of soft actuators.Importantly,the approach is not constrained by specific actuator shapes,and theoretically,any elongated photothermal actuator can be employed.The actuator was designed with an isosceles trapezoid shape,featuring a top width of 2mm,a bottom width of 4 mm,and a length of 8 mm.Through our,manipulation approach,we showcase a proof-of-concept for complex soft robotic motions,including crawling(achieving speeds of up to 2.25 body lengths per minute),turning,avoiding obstacles,handling and trans-ferring objects approximately twice its own weight,and navi-gating narrow spaces along programmed paths.Our results showcasethis all-optical manipulationapproach as a promising,yet unexplored tool for the precision and wireless control for the development of advanced soft actuators.

OCT4’s role and mechanism underlying oral squamous cell carcinoma

Oral squamous cell carcinoma(OSCC),a common malignancy of the head and neck,ranks sixth worldwide in terms of cancers with the most negative impact,owing to tumor relapse rates,cervical lymphnode metastasis,and the lack of an efficacious systemic therapy.Its prognosis is poor,and its mortality rate is high.Octamer-binding transcription factor 4(OCT4)is a member of the Pit-Oct-Unc(POU)family and is a key reprogramming factor that produces a marked effect in preserving the pluripotency and self-renewal state of embryonic stem cells(ESCs).According to recent studies,OCT4 participates in retaining the survival of OSCC cancer stem cells(CSCs),which has far-reaching implications for the occurrence,recurrence,metastasis,and prognosis of oral carcinogenesis.Therefore,we summarize the structure,subtypes,and function of OCT4 as well as its role in the occurrence,progression,and prognosis of OSCC.

Rapid fabrication of reconfigurable helical microswimmers with environmentally adaptive locomotion

Artificial helical microswimmers with shape-morphing capacities and adaptive locomotion have great potential for precision medicine and noninvasive surgery.However,current reconfigurable helical microswimmers are hampered by their low-throughput fabrication and limited adaptive locomotion.Here,a rotary holographic processing strategy(a helical femtosecond laser beam)is proposed to produce stimuli-responsive helical microswimmers(<100μm)rapidly(<1 s).This method allows for the easy one-step fabrication of various microswimmers with controllable sizes and diverse bioinspired morphologies,including spirulina-,Escherichia-,sperm-,and Trypanosoma-like shapes.Owing to their shape-morphing capability,the helical microswimmers undergo a dynamic transition between tumbling and corkscrewing motions under a constant rotating magnetic field.By exploiting adaptive locomotion,helical microswimmers can navigate complex terrain and achieve targeted drug delivery.Hence,these microswimmers hold considerable promise for diverse precision treatments and biomedical applications.

Three-dimensional chiral microstructures fabricated by structured optical vortices in isotropic material

Optical vortices,a type of structured beam with helical phase wavefronts and‘doughnut’-shaped intensity distributions,have been used to fabricate chiral structures in metals and spiral patterns in anisotropic polarization-dependent azobenzene polymers.However,in isotropic polymers,the fabricated microstructures are typically confined to non-chiral cylindrical geometry due to the two-dimensional‘doughnut’-shaped intensity profile of the optical vortices.Here we develop a powerful strategy to realize chiral microstructures in isotropic material by coaxial interference of a vortex beam and a plane wave,which produces threedimensional(3D)spiral optical fields.These coaxial interference beams are generated by designing contrivable holograms consisting of an azimuthal phase and an equiphase loaded on a liquid-crystal spatial light modulator.In isotropic polymers,3D chiral microstructures are achieved under illumination using coaxial interference femtosecond laser beams with their chirality controlled by the topological charge.Our further investigation reveals that the spiral lobes and chirality are caused by interfering patterns and helical phase wavefronts,respectively.This technique is simple,stable and easy to perform,and it offers broad applications in optical tweezers,optical communications and fast metamaterial fabrication.

Quasi-phase-matching-division multiplexing holography in a three-dimensional nonlinear photonic crystal

Nonlinear holography has recently emerged as a novel tool to reconstruct the encoded information at a new wavelength,which has important applications in optical display and optical encryption.However,this scheme still struggles with low conversion efficiency and ineffective multiplexing.In this work,we demonstrate a quasi-phasematching(QPM)-division multiplexing holography in a three-dimensional(3D)nonlinear photonic crystal(NPC).3D NPC works as a nonlinear hologram,in which multiple images are distributed into different Ewald spheres in reciprocal space.The reciprocal vectors locating in a given Ewald sphere are capable of fulfilling the complete QPM conditions for the high-efficiency reconstruction of the target image at the second-harmonic(SH)wave.One can easily switch the reconstructed SH images by changing the QPM condition.The multiplexing capacity is scalable with the period number of 3D NPC.Our work provides a promising strategy to achieve highly efficient nonlinear multiplexing holography for high-security and high-density storage of optical information.

STABILITY FOR IMPOSING ABSORBING BOUNDARY CONDITIONS IN THE FINITE ELEMENT SIMULATION OF ACOUSTIC WAVE PROPAGATION＊

It is well-known that artificial boundary conditions are crucial for the efficient and accurate computations of wavefields on unbounded domains. In this paper, we investigate stability analysis for the wave equation coupled with the first and the second order absorbing boundary conditions. The computational scheme is also developed. The approach allows the absorbing boundary conditions to be naturally imposed, which makes it easier for us to construct high order schemes for the absorbing boundary conditions. A thirdorder Lagrange finite element method with mass lumping is applied to obtain the spatial discretization of the wave equation. The resulting scheme is stable and is very efficient since no matrix inversion is needed at each time step. Moreover, we have shown both abstract and explicit conditional stability results for the fully-discrete schemes. The results are helpful for designing computational parameters in computations. Numerical computations are illustrated to show the efficiency and accuracy of our method. In particular, essentially no boundary reflection is seen at the artificial boundaries.

Enhanced blue-light excited cyan-emitting persistent luminescence of BaLu_(2)Al_(2)Ga_(2)SiO_(12)∶Ce3+,Bi3+phosphors for AC-LEDs via defect modulation

Alternating current light-emitting diodes(AC-LEDs)have received significant attention from both academia and industry due to their remarkable benefits of more compact volume,cheaper manufacturing cost,greater energy usage efficiency,and longer service life.One of the most significant challenges for AC-LEDs is the flicker effect,which is mainly caused by the unavoidable 5-20 ms dimming time.Aiming to reduce the flicker effect,we designed a series of excellent blue-light excited cyan-emitting persistent luminescence(PersL)phosphors BaLu_(2)Al_(2)Ga_(2)SiO_(12)∶Ce^(3+),Bi^(3+)via defect engineering of co-doping Bi^(3+).Interestingly,we found that co-doping Bi^(3+)not only effectively enhanced the PersL intensity,but also regulated the PersL lifetime of this phosphors.As the Bi^(3+)co-doping concentration increases to 0.01,the T80 value(the time when the PersL intensity decreases to 80%of the initial intensity)increases from 0.24 to 19.61 ms,which proves to be effective in compensating the flicker effect of AC-LEDs.A new method of generating white light emission during the dimming time through adding the blue-light excited cyan PersL phosphor to the original orange-red PersL phosphor was proposed and an AC-LED lamp with a decreased percent flicker of 48.15%was fabricated,which is significantly better than the other currently reported AC-LED devices based on PersL phosphors.These results demonstrate that BaLu_(2)Al_(2)Ga_(2)SiO_(12):Ce^(3+),Bi^(3+)might be an attractive material for low-flicker AC-LEDs.

Multilayered skyscraper microchipsfabricated by hybrid “all-in-one”femtosecond laser processing

Multilayered microfluidic channels integrated with functional microcomponents are the general trend of future biochips,which is similar to the history of Si-integrated circuits from the planer to the three-dimensional(3D)configuration,since they offer miniaturization while increasing the integration degree and diversifying the applications in the reaction,catalysis,and cell cultures.In this paper,an optimized hybrid processing technology is proposed to create true multilayered microchips,by which“all-in-one”3D microchips can be fabricated with a successive procedure of 3D glass micromachining by femtosecond-laser-assisted wet etching(FLAE)and the integration of microcomponents into the fabricated microchannels by two-photon polymerization(TPP).To create the multilayered microchannels at different depths in glass substrates(the top layer was embedded at 200μm below the surface,and the underlying layers were constructed with a 200-μm spacing)with high uniformity and quality,the laser power density(13~16.9 TW/cm^(2))was optimized to fabricate different layers.To simultaneously complete the etching of each layer,which is also important to ensure the high uniformity,the control layers(nonlaser exposed regions)were prepared at the upper ends of the longitudinal channels.Solvents with different dyes were used to verify that each layer was isolated from the others.The high-quality integration was ensured by quantitatively investigating the experimental conditions in TPP,including the prebaking time(18~40 h),laser power density(2.52~3.36 TW/cm2)and developing time(0.8~4 h),all of which were optimized for each channel formed at different depths.Finally,the eightlayered microfluidic channels integrated with polymer microstructures were successfully fabricated to demonstrate the unique capability of this hybrid technique.