An Underwater Target Detection Algorithm Based on Attention Mechanism and Improved YOLOv7

For underwater robots in the process of performing target detection tasks,the color distortion and the uneven quality of underwater images lead to great difficulties in the feature extraction process of the model,which is prone to issues like error detection,omission detection,and poor accuracy.Therefore,this paper proposed the CER-YOLOv7(CBAM-EIOU-RepVGG-YOLOv7)underwater target detection algorithm.To improve the algorithm’s capability to retain valid features from both spatial and channel perspectives during the feature extraction phase,we have added a Convolutional Block Attention Module(CBAM)to the backbone network.The Reparameterization Visual Geometry Group(RepVGG)module is inserted into the backbone to improve the training and inference capabilities.The Efficient Intersection over Union(EIoU)loss is also used as the localization loss function,which reduces the error detection rate and missed detection rate of the algorithm.The experimental results of the CER-YOLOv7 algorithm on the UPRC(Underwater Robot Prototype Competition)dataset show that the mAP(mean Average Precision)score of the algorithm is 86.1%,which is a 2.2%improvement compared to the YOLOv7.The feasibility and validity of the CER-YOLOv7 are proved through ablation and comparison experiments,and it is more suitable for underwater target detection.

Discharge and mass transfer characteristics of atmospheric pressure gas-solid two-phase gliding arc

In this work,a gas-solid two-phase gliding arc discharge(GS-GAD)reactor was built.Gliding arc was formed in the gap between the blade electrodes,and solid powder was deposited on the sieve plate positioned beneath the blade electrodes.A range of experimental parameters,including the inter-electrode spacing,gas flow rate,applied voltage,and the type of the powder,were systematically varied to elucidate the influence of solid powder matter on the dynamics of gliding arc discharge(GAD).The discharge images were captured by ICCD and digital camera to investigate the mass transfer characteristics of GS-GAD,and the electrical parameters,such as the effective values of voltage,current,and discharge power were record to reveal the discharge characteristics of GS-GAD.The results demonstrate that powder undergoes spontaneous movement towards the upper region of the gliding arc due to the influence of electric field force.Increasing the discharge voltage,decreasing relative dielectric constant of the powder and reducing the electrode-to-sieve-plate distance all contribute to a greater involvement of powder in the GAD process,subsequently resulting in an enhanced powder concentration within the GAD region.Additionally,powder located beneath the gliding arc experiences downward resistance caused by the opposing gas flow and arc.Excessive gas flow rate notably hampers the powder concentration within the discharge region,and the velocity of powder motion in the upper part of the GAD region is reduced.Under the condition of electrode-to-sieve-plate distance of 30 mm,gas flow rate of 1.5 L/min,and peak-to-peak voltage of 31 kV,the best combination of arc gliding and powder spark discharge phenomena can be achieved with the addition of Al_(2)O_(3) powder.

Plasma propagation in single-particle packed dielectric barrier discharges:joint effects of particle shape and discharge gap

In this work,a single Al_(2)O_(3) particle packed dielectric barrier discharge(DBD)reactor with adjustable discharge gap is built,and the influences of the particle shape(ball and column)and the residual gap between the top electrode and particle on the electrical and optical characteristics of plasma are studied.Our research confirms that streamer discharge and surface discharge are the two main discharge patterns in the single-particle packed DBD reactor.The strong electric field distortion at the top of the ball or column caused by the dielectric polarization effect is an important reason for the formation of streamer discharge.The length of streamer discharge is proportional to the size of the residual gap,but the number of discharge times of a single voltage cycle shows an opposite trend.Compared to the column,a smooth spherical surface is more conducive to the formation of large and uniform surface discharges.The surface discharge area and the discharge intensity reach a maximum when the gap is equal to the diameter of the ball.All in all,the results of this study will provide important theoretical support for the establishment of the synergistic characteristics of discharge and catalysis in plasma catalysis.

Perspectives of metal-organic framework nanosystem to overcome tumor drug resistance

Cancer is one of the most harmful diseases in the world, which causes huge numbers of deaths every year. Manydrugs have been developed to treat tumors. However, drug resistance usually develops after a period of time,which greatly weakens the therapeutic effect. Tumor drug resistance is characterized by blocking the action ofanticancer drugs, resisting apoptosis and DNA repair, and evading immune recognition. To tackle tumor drugresistance, many engineered drug delivery systems (DDS) have been developed. Metal-organic frameworks(MOFs) are one kind of emerging and promising nanocarriers for DDS with high surface area and abundant activesites that make the functionalization simpler and more efficient. These features enable MOFs to achieveadvantages easily towards other materials. In this review, we highlight the main mechanisms of tumor drugresistance and the characteristics of MOFs. The applications and opportunities of MOF-based DDS to overcometumor drug resistance are also discussed, shedding light on the future development of MOFs to address tumor drugresistance.

DSSylation, a novel protein modification targets proteins induced by oxidative stress, and facilitates their degradation in cells

Timely removal of oxidatively damaged proteins is crit- ical for cells exposed to oxidative stresses; however, cellular mechanism for clearing oxidized proteins is not clear. Our study reveals a novel type of protein modifi- cation that may play a role in targeting oxidized proteins and remove them. In this process, DSS1 （deleted in split hand/split foot 1）, an evolutionally conserved small protein, is conjugated to proteins induced by oxidative stresses in vitro and in vivo, implying oxidized proteins are DSS1 clients. A subsequent ubiquitination targeting DSSl-protein adducts has been observed, suggesting the client proteins are degraded through the ubiquitin- proteasome pathway. The DSS1 attachment to its clients is evidenced to be an enzymatic process modulated by an unidentified ATPase. We name this novel protein modification as DSSylation, in which DSS1 plays as amodifier, whose attachment may render target proteins a signature leading to their subsequent ubiquitination, thereby recruits proteasome to degrade them.