An X-band compact rectangular waveguide TE10-circular waveguide TE01 mode converter.

This paper proposed an X-band compact efficient rectangular waveguide TE10-circular waveguide TE01 mode converter and conducted its structure design, theoretical analysis, numerical simulation, and experimental research. This mode converter is composed of a rectangular waveguide TE10-TE20 mode converter and a rectangular waveguide TE20-circular waveguide TE01 mode converter. In the design of the rectangular waveguide TE20-circular waveguide TE01 mode converter, a rectangular waveguide step is used to counteract the microwave reflection due to the discontinuity of the rectangular-circular waveguide connection, and two choke slots are involved to suppress the TE21 mode in the circular waveguide by cutting off the axial component of its surface current on the waveguide wall, so as to improve the TE01 mode conversion efficiency. The simulation results show that the reflection coefficient of the mode converter is less than 5% and the TE01 mode conversion efficiency is about 98.4% at the operation frequency of 9.3 GHz. The bandwidth with a transmission coefficient greater than 98% is about 200 MHz. The back-to-back experimental system is demonstrated, and the experimental results show that the measured TE01 mode conversion efficiency is about 98.2%, which is consistent with the simulation result.

Electroplating wastewater treatment by in-situ formation of organic anions and inorganic anions intercalated layered double hydroxides.

The electroplating wastewater containing various metal ions was treated by adding sodium dodecyl benzene sulfonate (SDBS) and regulating pH value, and the resulting precipitates were characterized by X-ray diffraction (XRD). The results showed that organic anions intercalated layered double hydroxides (OLDHs) and inorganic anions intercalated layered double hydroxides (ILDHs) were in-situ formed to remove heavy metals during the treatment process. In order to reveal the formation mechanism of the precipitates, SDB- intercalated Ni-Fe OLDHs, NO3- intercalated Ni-Fe ILDHs and Fe3+-DBS complexes were synthsized by co-precipitation at various pH values for comparison. These samples were characterized by XRD, Fourier Transform infrared (FTIR), element analysis as well as the aqueous residual concentrations of Ni2+ and Fe3+ were detected. The results showed that OLDHs with good crystal structures can be formed as pH≤7, while ILDHs began to form at pH = 8. When pH < 7, complexes of Fe3+ and organic anions with the ordered layered structure were formed firstly, and then with increase in pH value, Ni2+ inserted into the solid complex and the OLDHs began to form. However, Ni-Fe ILDHs were not formed when pH ≤ 7. The Ksp (Solubility Product Constant) of OLDHs was calculated to be 3.24 × 10-19 and that of ILDHs was 2.98 × 10-18 at pH = 8, which suggested that OLDHs might be easier to form than ILDHs. The formation process of ILDHs and OLDHs were also simulated through MINTEQ software, and the simulation output verified that OLDHs could be easier to form than ILDHs at pH ≤ 7. Information from this study provides a theoretical basis for effective in-situ formation of OLDHs in wastewater treatment.

Adsorption characteristics of assembled and unassembled Ni/Cr layered double hydroxides towards methyl orange.

The lamella aggregation state of layered double hydroxides (LDHs) may affect their sorption capacity for organic compounds. The dried LDH samples (Ni/Cr LDH-FA-D and Ni/Cr LDH-H2O-D) and the undried samples (Ni/Cr LDH-FA-W and Ni/Cr LDH-H2O-W) were flexibly prepared by a co-precipitation method in formamide (FA) and water, respectively. The results of X-ray diffraction (XRD) and transmission electron microscope (TEM) showed that the undried LDHs were unassembled, which had no the stacking layers but had a pseudohexagonal nanosheet lamella structure. And the unassembled LDH layers can be assembled again during the dry process. Ni/Cr LDH-FA-W and Ni/Cr LDH-H2O-W showed much greater adsorption capacities towards methyl orange (MO) than Ni/Cr LDH-FA-D and Ni/Cr LDH-H2O-D, as well as shorter time to reach equilibrium. The maximum adsorption capacity of MO could be calculated to 806 mg/g and 740 mg/g for Ni/Cr LDH-FA-W and Ni/Cr LDH-H2O-W by Langmuir-type simulation. The greater adsorption capacities of unassembled LDH could be attributed to the loosen structure and much more exposed adsorption sites. It could be concluded that unassembled LDHs were an effective and conducive preparation pathway for the exploration of the adsorption sites of LDHs.

The catalytic process of poly-silicate-ferric (PSF) and generation mechanism of hydroxyl radical based on photo-Fenton system.

Poly-silicate-ferric (PSF) was developed as an heterogeneous UV-Fenton catalyst, which was characterized by Fourier transform infrared (FTIR) spectroscopy, X-ray diffraction (XRD), X-ray photoelectron spectroscopy (XPS), X-ray fluorescence (XRF), UV-vis diffuse reflectance spectroscopy (DRS), Brunauer-Emmett-Teller (BET) and scanning electron microscopy (SEM). The catalytic process of PSF and generation mechanism of hydroxyl radical based on photo-Fenton system were studied in detail. In the heterogeneous UV-Fenton system, the kapp value of Orange II degradation was as high as 0.268 min-1, which was 1.5 times compared to that with α-FeOOH as catalyst. As a result, the Orange II decolouration and mineralization rates were as high as 99.9% and 92.5% after 40 min treatment, respectively. Moreover, the hydroxyl radical concentration would increase to a peak value of 13.4 µmol/L at about 15 min. The fundamental cause of the high hydroxyl radical generation lay in the high release ability of iron ions from PSF. The peak concentrations of total iron ions and ferrous ions could increase to 4.53 mg/L and 1.57 mg/L at 20 min and 10 min, respectively. After treatment, the re-adsorption of iron ions on the surface of PSF could avoid the additional pollution caused by iron ions. The results confirmed that PSF was a high activity catalyst for an heterogeneous UV-Fenton system.

Research on pulse compression energy extraction technology based on X-band energy storage switching method.

A high power microwave source based on energy storage switching pulse compression technology can produce a high power microwave pulse with good repeatability and frequency stability for a long time and has a good development prospect. In order to improve the power gain, this paper studies the working characteristics of the energy extraction structure of the X-band energy storage switching pulse compression device. The theoretical analysis results show that the impedance mismatch exists in the traditional energy extraction structure after the pulse compression is transferred to the energy extraction stage and the energy extraction efficiency is not high, which results in the power gain limitation. Therefore, through theoretical calculation and simulation, an improved scheme based on output inductance diaphragm is proposed in this paper. The scheme has high power capacity and can achieve impedance matching without changing the resonant frequency of the energy storage cavity, so as to improve the power gain of the pulse compression device. The high power experimental results show that the power gain of the pulse compression device can be increased from 6.24 times to 7.22 times and the energy extraction efficiency can be increased by 17.5% by placing 17 mm slot spacing inductance diaphragm at 45 mm of the H-T arm of the waveguide, which verifies the feasibility of the improved scheme.

The complete mitochondrial genome of Acrossocheilus yunnanensis (Teleostei: Cypriniformes: Cyprinidae) and its phylogenetic position.

The complete mitochondrial genome of Acrossocheilus yunnanensis was determined in this study. It contained 13 protein-coding genes (PCGs), 22 tRNA, 2 rRNAs, and a control region with the base composition 31.47% A, 27.83% C, 24.65% T, and 16.05% G. Here we compared this newly determined mitogenome with another one from the same species reported before. The variable sites and the genetic distances between the two mitogenomes were 134 bp and 0.8%. Sixty-five variable sites occurred in the PCGs. The results from the phylogenetic analysis showed that the genus Acrossocheilus is not a monophyletic group and Acrossocheilus yunnanensis demonstrates a close relationship with Acrossocheilus monticola.

Complete mitochondrial genome of Sinibotia superciliaris (Teleostei: Cypriniformes, Cobitidae) and its phylogenetic position.

The complete mitochondrial genome of Sinibotia superciliaris was determined in this study. It contained 13 protein-coding genes (PCGs), 22 tRNA, 2 rRNAs, and a control region with the base composition 31.57% A, 27.18% C, 25.52% T, and 15.74% G. Here we compared this newly determined mitogenome with another one from the same species reported before. The variable sites and the genetic distances between the two mitogenomes were 20 bp and 0.1%. 15 variable sites were occurred in the PCGs. The results from the phylogenetic analysis showed that the genus Sinibotia is a monophyletic group and S. superciliaris demonstrate a sister relationship with Sinibotia pulchra.