[en] The effects of gasoline and ethanol addition on the spray and atomization characteristics of diesel spray from a common rail injection system, was investigated in a constant volume chamber at different ambient and injection pressures. The fuel spray evolution process was recorded with high spatial and time resolution and the corresponding spray tip penetration (STP), the cone angle were extracted. The results show that increased gasoline proportion in the test blends causes decreased STP and increased spray cone angle. Additionally, the microscopic spray characteristics such as the local average droplet diameter and statistical size distributions were measured by particle/droplet image analysis (PDIA) technique. As gasoline blending ratio increases, significantly smaller droplet size was observed which indicates that the spray breakup and atomization processes were promoted. Further adding ethanol slightly increased the droplet size, but it is still much smaller than the droplet size of neat diesel spray. Moreover, the local droplet size increases along the radial direction but the local droplet volume fraction and normalized droplet number density decreases, indicating a reduced fuel concentration along the radial direction. Along the axial direction, the droplet size, the local droplet volume fraction and the normalized droplet number density were almost constant. - Highlights: • The increased gasoline fraction in diesel/gasoline blends leads to decreased spray tip penetration. • Gasoline blending significantly reduces the average droplet size while further addition of ethanol slightly decreases the droplet size. • Along the radial direction the droplet size increases, but the number density decreases.

[en] Pseudocapacitors have been experimentally studied for many years in electric energy storage. However, first principles understanding of the pseudocapacitive behavior is still not satisfactory due to the complexity involved in modeling electrochemistry. In this paper, we applied joint density functional theory (JDFT) to simulate the pseudocapacitive behavior of RuO₂, a prototypical material, in a model electrolyte. We obtained from JDFT a capacitive curve which showed a redox peak position comparable to that in the experimental cyclic voltammetry (CV) curve. We found that the experimental turning point from double-layer to pseudocapacitive charge storage at low scan rates could be explained by the hydrogen adsorption at low coverage. As the electrode voltage becomes more negative, H coverage increases and causes the surface-structure change, leading to bended –OH bonds at the on-top oxygen atoms and large capacitance. This H coverage-dependent capacitance can explain the high pseudocapacitance of hydrous RuO₂. Our work here provides a first principles understanding of the pseudocapacitance for RuO₂ in particular and for transition-metal oxides in general. (paper)

[en] The excitation source is one of the critical items that determine the electromagnetic fields in a reverberation chamber (RC). In order to optimize the electromagnetic fields performance, a new method of exciting RC with two antennas is proposed based on theoretical analysis. The full 3D simulation of RC is carried out by the finite difference time domain (FDTD) method on two excitation conditions of one antenna and two antennas. The broadband response of RC is obtained by fast Fourier transformation (FFT) after only one simulation. Numerical data show that the field uniformity in the test space is improved on the condition of two transmitting antennas while the normalized electric fields decreased slightly compared to the one antenna condition. It is straightforward to recognize that two antennas excitation can reduce the demands on power amplifier as the total input power is split among the two antennas, and consequently the cost of electromagnetic compatibility (EMC) test in large-scale RC can be reduced.

[en] Printed circuit boards (PCBs) contain many toxic substances as well as valuable metals, e.g., lead (Pb) and tin (Sn). In this study, a novel technology, named supergravity, was used to separate different mass ratios of Pb and Sn from Pb–Sn alloys in PCBs. In a supergravity field, the liquid metal phase can permeate from solid particles. Hence, temperatures of 200, 280, and 400°C were chosen to separate Pb and Sn from PCBs. The results depicted that gravity coefficient only affected the recovery rates of Pb and Sn, whereas it had little effect on the mass ratios of Pb and Sn in the obtained alloys. With an increase in gravity coefficient, the recovery values of Pb and Sn in each step of the separation process increased. In the single-step separation process, the mass ratios of Pb and Sn in Pb–Sn alloys were 0.55, 0.40, and 0.64 at 200, 280, and 400°C, respectively. In the two-step separation process, the mass ratios were 0.12 and 0.55 at 280 and 400°C, respectively. Further, the mass ratio was observed to be 0.76 at 400°C in the three-step separation process. This process provides an innovative approach to the recycling mechanism of Pb and Sn from PCBs.

[en] Highlights: • New low temperature ignition delay times of MCH/ethanol blends were provided. . • H₂O₂ chemistry determines the threshold of ignition for binary fuels. • A generalized effect of ethanol blending on NTC behavior was found. -- Abstract: New ignition delay times (IDTs) of binary methylcyclohexane (MCH)/ethanol fuels were provided by using a rapid compression machine. Results show that MCH exhibits typical negative temperature coefficient (NTC) regime bounded by two turnover temperatures (T_upper and T_lower). As the ethanol blending ratio increases, IDTs increase, NTC regime shrinks and shifts to the lower temperature. Measured data are then used to validate the most updated kinetic model (Bissoonauth et al. Proc Combust Inst 2018), which well captures the IDT and NTC behavior dependence on the ethanol blending ratio. The kinetic reason for the experimentally observed ignition behavior is that ethanol addition reduces the low temperature heat release and slows down the temperature rise and H₂O₂ decomposition pathway activation. The mole fraction of ROO and QOOH decrease rapidly due to the reduction of MCH initial concentration, and the NTC behavior becomes less apparent consequently. Further comparison among the ignition behavior of the different binary fuels have been conducted to access the effect of ethanol addition on different structure fuels. Results indicate a generalized effect of ethanol addition and the kinetic reason is that the presence of ethanol just simply reduces the hydrocarbon concentration without fuel-to-fuel interactions.

[en] Highlights: • Characteristics of MPs in rainwater pipes with different land function are studied. • Commercial and residential areas emitted higher MPs than campuses and highway areas. • Residential and commercial areas hold the most fiber and film MPs, respectively. • Urban rainwater pipelines are a way for land-based MPs to enter freshwater. Urban rainwater runoff is considered to be an important way to transport microplastics into the freshwater. By analyzing the microplastics in rainwater pipelines in different land function areas in Hongshan District (Wuhan, China), the preliminary results of microplastics abundance and characteristics in rainwater pipelines and rainwater pipeline sediments were obtained. The microplastics abundance in water samples was 2.75 ± 0.76 to 19.04 ± 2.96 items/L, the abundance of microplastics in the sediment was 6.00 ± 1.63 to 27.33 ± 4.64 items/100 g. The highest abundance among the samples was in the business district and the lowest in the campus. The microplastics in water samples and sediment samples were mainly fragments, accounting for 44.7% and 57.1%, respectively. The proportion of particle size <1 mm was 75.0% and above. The color of microplastics was diversified, and colored particles occupied over 60.0%. The types of polymers detected were mainly polyethylene, polypropylene and polyester, which were related to the types of polymers widely used in life. This study shows that urban rainwater pipelines is one of the ways for land-based microplastics to migrate to freshwater, and the accumulation of microplastics in stormwater pipe sediments might be an important contributor to microplastics in freshwater area.

[en] Highlights: ► The conductive network formation by electric field in both the PC/MWNTs and PC/MWNTs-COOH composites were investigated by the dynamic percolation measurement. ► At the percolation time and the formation activation energy of conductive network for MWNTs filled composites decreased greatly as compared to those of the MWNTs-COOH filled composites. ► The dynamic percolation measurement method could be recommended to investigate the zero-shear-rate viscosity at the different temperatures. - Abstract: Using polycarbonate (PC) as a matrix, and multi-wall carbon nanotubes (MWNTs) and acid-treated MWNTs (MWNTs-COOH) as fillers, PC/MWNTs and PC/MWNTs-COOH conductive composites were prepared, respectively. The conductive network formation induced by electric field in both the PC/MWNTs and PC/MWNTs-COOH composites were investigated by the dynamic percolation measurement. It was found that the electrical resistivity–time curves showed a certain self-similarity under various electric fields, i.e., the electrical resistivity decreased sharply as the percolation time (t_p) was reached. And the dynamic percolation time was shorten with the increase of the electric field intensity for both MWNTs and MWNTs-COOH filled PC composites. However, the percolation time and the formation activation energy of conductive network under electric field for MWNTs filled composites decreased greatly as compared to those of the MWNTs-COOH filled composites. These results indicated that the interaction between MWNTs and PC molecules played an important role in the conductive network formation under the electric field. Furthermore, the t_p values under the electric field for PC/MWNTs and PC/MWNTs-COOH composites were successfully predicted by a modified thermodynamic percolation model. And this dynamic percolation measurement method could be recommended to investigate the zero-shear-rate viscosity at the different temperatures.

[en] MXenes (two-dimensional transition-metal carbides and nitrides) are promising materials for capacitive energy storage due to the large chemical space of existing and potential compositions, but only a few of them have been experimentally explored. In this paper, we computationally screen a series of MXene electrodes (M_n+1X_nT_x: M = Sc, Ti, V, Zr, Nb, Mo; X = C, N; T = O, OH; n = 1–3) to simulate their pseudocapacitive performance in the aqueous H₂SO₄ electrolyte. We find that nitride MXenes exhibit better pseudocapacitive performance than carbide MXenes. Especially, Ti₂NT_x is predicted to have a high gravimetric capacitance over a wide voltage window, whereas Zr_n+1N_nT_x MXenes are predicted to possess the best areal capacitive performance. Evaluating the descriptors for the capacitance trends, we find that more positive hydrogen adsorption free energy (weak binding to H) and smaller change of the potential at the point of zero charge after H binding lead to higher capacitance. In conclusion, our work provides helpful guidance to selectively develop high-performance MXene pseudocapacitors and to further screen MXene electrodes.

[en] 

Background

: Accounting for tumor heterogeneity, cancer stem cells (CSC) are involved in tumor metastasis, relapse, and drug resistance. Genes regulating CSC characteristics in lung adenocarcinoma (LUAD) were explored and validated in this study.

Methods

: The mRNA stemness index (mRNAsi) of more than 500 LUAD cases from The Cancer Genome Atlas database were calculated using a one-class logistic regression machine learning algorithm based on the mRNA expression of pluripotent stem cells and their differentiated progeny. mRNAsi-related key genes were identified by weighted correlation network analysis. The expression levels and prognostic roles of key genes were analyzed in Oncomine, PrognoScan, and Kaplan–Meier plotter databases, and validated using data from our center.

Results

: The mRNAsi was significantly higher in LUAD compared with normal lung tissues. LUAD patients of advanced stage exhibited a higher mRNAsi and worse overall survival (OS). Eight key genes were identified: heat shock 70 kDa protein 4 (HSPA4), cell division cycle associated 7 (CDCA7), cell division cycle 20 (CDC20), cyclin-dependent kinase 1 (CDK1), CAP-GLY domain containing linker protein 1 (CLIP1), cyclin B1 (CCNB1), H2A histone family, member X (H2AFX), and Bloom syndrome, RecQ helicase-like (BLM). These genes were differentially expressed in various types of malignancies and validated in the LUAD cases. LUAD patients with low expression of CDC20, CDK1, CCNB1, H2AFX, or BLM had a significantly better OS, whereas OS was reduced for patients with low expression of CLIP1. In addition, the expression of CDCA7 did not significantly impact the OS of LUAD patients. The protein–protein interaction networks evaluated by STRING demonstrated strong relationships between these key genes, which were validated in our cases.

Conclusions

: The mRNAsi was significantly higher in LUAD compared with normal samples. Eight mRNAsi-related key genes were associated with prognosis and the cell cycle, and were strongly correlated with each other and differentially expressed in tumor and normal samples. We provide a new strategy for exploring stemness-related genes in LUAD cases.

[en] Practical communication settings for quantum key distribution (QKD) are very complex, and the number of participants should be tunable. Given these, we propose a tunable multi-party high-capacity QKD protocol based on m-generalized Fibonacci sequences and golden coding, where the number of participants can be adjusted adaptively by joining a new participant and revoking an old participant, combining two participant groups into one group. Meanwhile, we construct golden coding to achieve higher capability and fewer interactive communications.