Seasonal and spatial variations of heavy metalsin surface sediments collected from the BaoxiangRiver in the Dianchi Watershed, China

To explore potential ecological hazards due to heavy metals in the Dianchi Lake Watershed, a three-stage European Community Bureau of Reference (BCR) sequential extraction procedure was applied to examine the spatial distributions and relative speciation ratios of Zn, Cu, Ni, Pb, and Cr in Baoxiang River sediments during wet and dry seasons. The metal species have similar spatial variations during different seasons. In the upstream reaches of the Baoxiang River, heavy metals reside primarily in the non-extractable residual fraction (72&ndash;90%). In the midstream, the residual fraction (35&ndash;89%) remains dominant, but the extractable fraction increases, featuring especially notable increases in the reducible fraction (5&ndash;40%). Downstream, the Cu, Ni, Pb, and Cr residual fractions remain high (46&ndash;80%) and the extractable fractions increase rapidly; the Zn extractable fraction is quite high (65.5%). Anthropogenic sources drive changes in heavy metal speciation. Changes in the river environment, such as pH and oxidation-reduction potential, also affect speciation. The reducible fraction of heavy metals in Baoxiang River sediments is most sensitive to pH. Potential ecological risk assessments for these five elements indicate that risks from Zn and Pb are mild to moderate in the middle and lower reaches of the river.<br style="line-height: normal; text-align: -webkit-auto; text-size-adjust: auto;" /

Potential of a bed ventilation system in reducing the risk of exposure to contaminants in infectious wards

A proposed bed ventilation system named Hospital Bed Integrated Ventilation Cleansing Unit (HBIVCU) has shown its great potential in reducing the risk of airborne cross-infection. However, the key operating parameters are still unclear, restricting its practical application. This study numerically investigated the performance of the HBIVCU under various operating parameters (supply and exhaust airflow rates increased from 0 L/s to 5 L/s and 0 L/s to 40 L/s, respectively) in a four-bed infectious ward with different background ventilation rates. Both tracer gas CO2, (simulating aerosols smaller than 5 μm) and particles (mean diameter of 80 μm) in the exhaled by one of the patients were considered. Compared to the ward without the HBIVCU, the concentration of CO2 at the bed microenvironment and breathing height of standing and sitting persons are reduced by more than half when the HBIVCU operates with supply and exhaust airflow rates of 5 L/s and 40 L/s, respectively. For this case, the highest draught risk of 13% at the patients’ head region is obtained. Increasing the supply and exhaust airflow rates of the HBIVCU are both helpful for removing the exhaled gaseous contaminants from the room due to increased induction effect of the local bed ventilation flow. The removal efficiency is around twice higher when the HBIVCU is operating at background ventilation at 6 air changes per hour (ACH) when compared to when it is not operating at background ventilation of 12 ACH. Finally, the HBIVCU can efficiently remove the exhaled gaseous contaminants, though it has no discernible effect on the removal of coughing droplets. The HBIVCU has great potential to reduce the risk of cross-infection and save energy by lowering the background ventilation rate

Improved YOLOX-DeepSORT for Multitarget Detection and Tracking of Automated Port RTG

Rubber tire gantry (RTG) plays a pivotal role in facilitating efficient container handling within port operations. Conventional RTG, highly depending on human operations, is inefficient, labor-intensive, and also poses safety issues in adverse environments. This article introduces a multitarget detection and tracking (MTDT) algorithm specifically tailored for automated port RTG operations. The approach seamlessly integrates enhanced YOLOX for object detection and improved DeepSORT for object tracking to enhance the MTDT performance in the complex port settings. In particular, Light-YOLOX, an upgraded version of YOLOX incorporating separable convolution and attention mechanism, is introduced to improve real-time capability and small target detection. Subsequently, OSNet-DeepSORT, an enhanced version of DeepSORT, is proposed to mitigate ID switching challenges arising from unreliable data communication or occlusion in real port scenarios. The effectiveness of the proposed method is validated in various real-life port operations. Ablation studies and comparative experiments against typical MTDT algorithms demonstrate noteworthy enhancements in key performance metrics, encompassing small target detection, tracking accuracy, ID switching frequency, and real-time performance

THEORETICAL MODELING AND TEST SIMULATION RESEARCH OF DOUBLE-LAYER VIBRATION ISOLATION SYSTEM

The theoretical model of double-layer vibration isolation system based on the icebox compressor was built through the four-point parameter method,and got the force transportation-rate pattern,found the finite element simulation model of double-layer vibration isolation,obtained the main mode of the system through mode analysis and the force transportation-rate through dynamic reaction analysis. The force transportation-rate results through theoretical model and finite simulation method and test were compared and analyzed,the results show,the natural frequencies obtained from the theoretical model and simulation model are basically same,the force transportation-rate has the same trend on the whole,the theoretical results and simulated results accord well with the test results in the low frequency between 0 to 150 Hz,when the frequency exceeds 150 Hz,there are some differences between theoretical results,simulation results and test results to some extent

Low velocity impact response and post impact compression behavior of BMI matrix composites

A novel kind of lattice-distributed ESTM-fabrics was developed by using polyethersulfone(PES) and U3160.The loading amounts of PES on ESTM-fabrics are 15 g/cm2(ES-15), 25 g/cm2(ES-25), 35 g/cm2(ES-35), respectively. ESTM-fabrics reinforced BMI resin (trademarks: 6421) matrix composites(ESTM-fabric/6421) were prepared through RTM process.Dynamic mechanical thermal analyses(DMTA) and impact resistance as well as residual strength of ESTM-fabric/6421 were studied and the toughened mechanism was analyzed by fluorescence microscope.An untoughened 6421 BMI resin matrix composite (ES-0) reinforced by neat U3160 fabrics was studied to compare performance of composites as well.The results of DMTA show that ES-0 has only one glass transition temperature(Tg) representing pure BMI resin.The toughened composites exhibit two Tg: the relaxation peak appearing at 230-250 ℃ represents toughener PES phase and the relaxation peak appearing at 191-195 ℃ represents BMI phase. The results of low velocity impact testing show that the initial damage threshold load(DTL) is decreased significantly. DTL of toughened composites is far greater than ES-0 sample, which is the same as maximum peak load.With the increase of PES loading in toughened composites, DTL are increased and the projected delaminated areas are decreased.Fluorescence microscopic results of the specimens after low velocity impact show that the major impact failure of ES-0 sample is delamination. The toughened composites exhibit a great deal of interlaminar and intralaminar matrix crack under the impactor as well as more serious ply splitting on the back surface of specimens, which conical damage is less than ES-0 sample.The compression strength after impact(CAI) of ES-0 sample was 144.66 MPa while CAIs of the toughened composites ES-15, ES-25 and ES-35 increased to 205.85 MPa, 265.74 MPa along with 275.14 MPa, respectively. Fluorescence microscopic results of the CAI specimens reveal that ES-0 sample has massive delamination damage without ply splitting. A lot of ply splitting and obvious matrix cracks appear in ES-15 sample.The major impact failure of ES-25 and ES-35 samples is ply shear damage.These damage modes can absorb massive energy that lead to the higher CAI of the toughened composites

Climate Change and Drought Events in the Geochemical Records of the Lacustrine Deposits in the Southeastern Tibetan Plateau.

Lacustrine deposits at the margin of the southeastern Tibetan Plateau (SETP) are sensitive indicators for the evolution of the southwest Asian monsoon (SWAM) during the Quaternary. Thus, they can provide insight into the Quaternary climatic history and their relationship with global climatic changes. The results of the geochemical analysis of the Xiaozhongdian Basin section at the SETP suggest that SiO2 had the highest content of the major elements followed by Al2O3. The order of the abundance of the major elements was generally as follows: SiO2>Al2O3>Fe2O3>CaO>MgO>K2O>TiO2>Na2O>MnO2. The geochemical proxies, such as chemical index of alteration (CIA), the index of compositional variability (ICV) and (CaO+K2O+Na2O)/Al2O3, indicate the weak chemical weathering and the aridification of the margin of the SETP during the Heinrich events. In addition, the aridification of the SETP during the Heinrich events may be closely related to the cold signals transmitted from the high latitudes of the North Atlantic to the TP, and the effect caused the cooling effect to be very strong on the TP as a result of the upper-level westerly jet stream and then reduced the suction action associated with the SWAM, thus accelerating the drying rate of Xiaozhongdian Basin, which was amplifying the degree of drought in Heinrich events

DLm6Am: A Deep-Learning-Based Tool for Identifying N6,2&prime;-O-Dimethyladenosine Sites in RNA Sequences

N6,2&prime;-O-dimethyladenosine (m6Am) is a post-transcriptional modification that may be associated with regulatory roles in the control of cellular functions. Therefore, it is crucial to accurately identify transcriptome-wide m6Am sites to understand underlying m6Am-dependent mRNA regulation mechanisms and biological functions. Here, we used three sequence-based feature-encoding schemes, including one-hot, nucleotide chemical property (NCP), and nucleotide density (ND), to represent RNA sequence samples. Additionally, we proposed an ensemble deep learning framework, named DLm6Am, to identify m6Am sites. DLm6Am consists of three similar base classifiers, each of which contains a multi-head attention module, an embedding module with two parallel deep learning sub-modules, a convolutional neural network (CNN) and a Bi-directional long short-term memory (BiLSTM), and a prediction module. To demonstrate the superior performance of our model&rsquo;s architecture, we compared multiple model frameworks with our method by analyzing the training data and independent testing data. Additionally, we compared our model with the existing state-of-the-art computational methods, m6AmPred and MultiRM. The accuracy (ACC) for the DLm6Am model was improved by 6.45% and 8.42% compared to that of m6AmPred and MultiRM on independent testing data, respectively, while the area under receiver operating characteristic curve (AUROC) for the DLm6Am model was increased by 4.28% and 5.75%, respectively. All the results indicate that DLm6Am achieved the best prediction performance in terms of ACC, Matthews correlation coefficient (MCC), AUROC, and the area under precision and recall curves (AUPR). To further assess the generalization performance of our proposed model, we implemented chromosome-level leave-out cross-validation, and found that the obtained AUROC values were greater than 0.83, indicating that our proposed method is robust and can accurately predict m6Am sites

Research and Application Progress of Silicone Rubber Materials in Aviation

The research progress of heat resistance, cold resistance, electrical conductivity and damping properties of aviation silicone rubber were reviewed in this article. The heat resistance properties of silicone rubber can be enhanced by changing the molecular structure (main chain, end-group, side chain and molecular weight) of the gum and adding special heat-resistance filler. The cold resistance of aviation silicone rubber can be enhanced by adjusting the side chain molecular structure of the gum and the content of different gum chain. The electrical conductivity of silicone rubber can be improved by optimizing, blending and dispersing of conductive particles. The damping property of silicone rubber can be improved by designing and synthesizing of high-molecular polysiloxane damping agent. Furthermore, the application of aviation silicone rubber used in high-low temperature seal, electrical conduction and vibration damping technology are also summarized, and the high performance (for example long-term high temperature resistance, ultralow temperature resistance, high electromagnetic shelding, long-term fatigue resistance vibration damping, quasi constant modulus and so on) of special silicone rubber is the future direction of aviation silicone rubber