In this article, a new synthesis method for generalized multi‐band filters has been proposed. Different from the traditional frequency transformation method, which transforms a low‐pass prototype ...into a multi‐band filter, multiple low‐pass prototypes have been transformed into a multi‐band filter. This study introduces the idea of transforming more than two lowpass prototypes into a filter, called multi‐prototype transformation. It divides the multi‐band filter to be synthesized into different segments each of which corresponds to a low‐pass prototype. After frequency transformation, these segments are combined together to get the final transfer function. The multi‐band filter synthesized by this method can have different orders, bandwidths or return losses in different passbands. Prescribed transmission zeros can also be realized. The return loss adjustment, segment boundary estimation and equal‐ripple realization of this method are further explained in theory. To verify this method, an asymmetric quad‐band filter is synthesized as an example and a symmetric triple‐band filter is synthesized, designed, fabricated and measured. The obtained results show good agreement with the simulation.
Soil salinity and drought are the two most common and frequently co-occurring abiotic stresses constraining crop growth and productivity. Greenhouse pot experiments were conducted to investigate the ...tolerance potential and mechanisms of Tibetan wild barley genotypes (XZ5, drought-tolerant; XZ16, salinity/aluminum tolerant) during anthesis compared with salinity-tolerant cv CM72 in response to separate and combined stresses (D+S) of drought (4% soil moisture, D) and salinity (S). Under salinity stress alone, plants had higher Na(+) concentrations in leaves than in roots and stems. Importantly, XZ5 and XZ16 had substantially increased leaf K(+) concentrations; XZ16 was more efficient in restricting Na(+) loading in leaf and maintained a lower leaf Na(+)/K(+) ratio. Moreover, a significant decrease in cell membrane stability index (CMSI) and an increase in malondialdehyde (MDA) were accompanied by a dramatic decrease in total biomass under D+S treatment. We demonstrated that glycine-betaine and soluble sugars increased significantly in XZ5 and XZ16 under all stress conditions, along with increases in protease activity and soluble protein contents. Significant increases were seen in reduced ascorbate (ASA) and reduced glutathione (GSH) contents, and in activities of H(+)K(+)-, Na(+)K(+)-, Ca(++)Mg(++)-, total- ATPase, and antioxidant enzymes under D+S treatment in XZ5 and XZ16 compared to CM72. Compared with control, all stress treatments significantly reduced grain yield and 1000-grain weight; however, XZ5 and XZ16 were less affected than CM72. Our results suggest that high tolerance to D+S stress in XZ5 and XZ16 is closely related to the lower Na(+)/K(+) ratio, and enhanced glycine-betaine and soluble protein and sugar contents, improved protease, ATPase activities and antioxidative capacity for scavenging reactive oxygen species during anthesis. These results may provide novel insight into the potential responses associated with increasing D+S stress in wild barley genotypes.
This study developed a framework to evaluate, in the context of COVID-19, the performance of an OVRWCHT (online 360° virtual reality world cultural heritage tourism) system created by the authors for ...the purpose of heritage interpretation and presentation. The research framework was based on the seven main principles of the ICOMOS Charter for the Interpretation and Presentation of Cultural Heritage Sites, and evaluation criteria were established for each. This framework was used to evaluate an OVRWCHT for the Hailongtun Tusi World Heritage Site in Guizhou Province, China. Data were mainly based on 1,062 questionnaires and analyses of the developed system. The findings indicated that, whether in terms of user experience or the interpretation of the UNESCO criterion “outstanding universal value,” Stakeholders agreed that OVRWCHT has played a positive role in heritage interpretation. Yet, more data support is needed to improve both technology and theory – especially the transferability of OVRWCHT to countries other than China. Based on the findings, it is suggested that the International Council on Monuments and Sites should continue to issue charters on how emerging technologies can support heritage site interpretation and presentation.
Aqueous zinc‐ion batteries possess great potential in stationary energy storage devices. Nevertheless, the occurrence of zinc dendrite growth and hydrogen evolution reaction severely hinders the ...utilization efficiency and service life of zinc‐metal anodes. Herein, an in situ etching strategy is proposed to construct an interfacial layer with porous structure on the surface of zinc foil under the assistance of tartaric acid (denoted as TA@Zn). The optimized anode surface is beneficial to not only achieve uniform Zn deposition behavior due to the low nucleation overpotential, but also enhance the interfacial reaction kinetics due to the reduced activation energy barrier. As expected, the TA@Zn‐based symmetric cell delivers small voltage hysteresis and superior stability for 5000 h at the current density of 1 mA cm−2. Moreover, the TA@Zn|NH4V4O10 cell also exhibits high specific capacity and long‐term cycling stability.
Artificial interfacial layers with porous structures are constructed on the surface of Zn foil via an etching treatment with tartaric acid and they endow TA@Zn with low nucleation overpotential and low activation energy, thereby enabling uniform Zn2+ deposition behavior and enhancing interfacial reaction kinetics.
The functionalized multi-walled carbon nanotubes (MWNTs) with amino groups were prepared after such steps as oxidation, the addition of carboxyalkyl radicals, acylation and amidation. Besides ...oxidated-MWNTs/epoxy nanocomposites, amino-functionalized MWNTs/epoxy nanocomposites, in which MWNTs with amino groups acted as a curing agent and covalently attached into the epoxy matrix, were fabricated. Subsequently, the effects of MWNT content on the mechanical and thermal properties for the two systems were investigated. It is found that both the tensile strength and impact strength enhance with the increase of MWNT addition, and the most significant improvement of the tensile strength (+51%) and especially impact strength (+93%) is obtained with amine-treated MWNTs at an 1.5
wt.% content. Moreover, the thermal stability of the nanocomposites also distinctly improves. The improvement of the properties of the amine-treated MWNTs system is more remarkable than those of o-MWNTs system. The reasons for these changes were discussed.
A novel ultra-wideband (UWB) bandpass filter with sharp rejection and a narrow notched band is presented. This filter is designed using a multiple-mode resonator (MMR) which consists of a ring ...resonator and a stepped-impedance stub. The MMR has six resonance frequencies and three transmission zeros (TZs). All three TZs are close to the resonance frequencies, thus creating sharp roll-off and narrow notched bands. Different passband bandwidths and notched bands can be obtained by tuning the stepped-impedance admittance ratios. The simulated and measured results demonstrate that this simple bandpass filter has 97.3 and 30.6 dB/GHz attenuation slope at the lower and upper transition bands, respectively. The 3 dB notched band is from 5.6 to 5.8 GHz with 10.3 dB insertion loss at 5.7 GHz.
The meandering channel deposit of the upper member of Neogene Guantao Formation in Shengli Chengdao extra-shallow sea oilfield is characterized by rapid change in sedimentary facies. In addition, ...affected by surface tides and sea water reverberation, the double sensor seismic data processed by conventional methods has low signal-to-noise ratio and low resolution, and thus cannot meet the needs of seismic description and oil-bearing fluid identification of thin reservoirs less than 10 meters thick in this area. The two-step high resolution frequency bandwidth expanding processing technology was used to improve the signal-to-noise ratio and resolution of the seismic data, as a result, the dominant frequency of the seismic data was enhanced from 30 Hz to 50 Hz, and the sand body thickness resolution was enhanced from 10 m to 6 m. On the basis of fine layer control by seismic data, three types of seismic facies models, floodplain, natural levee and point bar, were defined, and the intelligent horizon-facies controlled recognition technology was worked out, which had a prediction error of reservoir thickness of less than 1.5 m. Clearly, the description accuracy of meandering channel sand bodies has been improved. The probability semi-quantitative oiliness identification method of fluid by prestack multi-parameters has been worked out by integrating Poisson's ratio, fluid factor, product of Lame parameter and density, and other prestack elastic parameters, and the method has a coincidence rate of fluid identification of more than 90%, providing solid technical support for the exploration and development of thin reservoirs in Shengli Chengdao extra-shallow sea oilfield, which is expected to provide reference for the exploration and development of similar oilfields in China.
Aluminum (Al) toxicity is a major limiting factor for plant production in acid soils. Wild barley germplasm is rich in genetic diversity and may provide elite genes for crop Al tolerance improvement. ...The hydroponic-experiments were performed to compare proteomic and transcriptional characteristics of two contrasting Tibetan wild barley genotypes Al- resistant/tolerant XZ16 and Al-sensitive XZ61 as well as Al-resistant cv. Dayton. Results showed that XZ16 had less Al uptake and translocation than XZ61 and Dayton under Al stress. Thirty-five Al-tolerance/resistance-associated proteins were identified and categorized mainly in metabolism, energy, cell growth/division, protein biosynthesis, protein destination/storage, transporter, signal transduction, disease/defense, etc. Among them, 30 were mapped on barley genome, with 16 proteins being exclusively up-regulated by Al stress in XZ16, including 4 proteins (S-adenosylmethionine-synthase 3, ATP synthase beta subunit, triosephosphate isomerase, Bp2A) specifically expressed in XZ16 but not Dayton. The findings highlighted the significance of specific-proteins associated with Al tolerance, and verified Tibetan wild barley as a novel genetic resource for Al tolerance.
Treating MWCNTs with an acidic solution (concentrated H2SO4/HNO3; 3:1) and subsequently with succinic acid peroxide leads to MWCNTs functionalized with carboxyl groups on their sidewalls (or ...surfaces). These MWCNT‐COOH were converted to MWCNT‐COCl and further to MWCNT‐NH2. The PU was covalently coated onto the sidewalls (or surfaces) of the MWCNT by in situ polymerization of TDI under ultrasound in the presence of MWCNT‐NH2. The results show that PU is chemically tethered to the MWCNT sidewalls (or surfaces) via the ∼HNCONH∼ linkage, with a thickness in the range of approximately 2 to 5 nm, and the amount of grafted PU is about 34 wt.‐%.
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•Double cross-linking poly(ionic liquid)-based electrolyte is prepared by dual polymerization method.•Benefiting from ionic liquid, PIL-PEI1 shows high flame-retardant.•Double ...cross-linking network endows lithium dendrite-resistant for PIL-PEI1 electrolyte.•The package using liquid-free PIL-PEI1 as electrolyte can work in emergency situation.
Liquid leakage and lithium dendrite growth are common safety hazards of lithium-ion batteries, and the application of quasi-solid electrolytes are considered to be the most promising material for inhibiting the safety problems. Herein, a new type of bi-functional ionic liquid is synthesized and polymerized into double cross-linked poly(ionic liquid) electrolyte (denoted as PIL-PEI) by dual cross-linking method ring-opening polymerization network: epoxy groups in 1-vinyl-3-epoxypropylimidazolium bis(trifluoromethanesulfonyl)imide (VEIM-TFSI) cross-linked with amino-groups in poly(ethylene imine) (PEI), radical cross-linking network: VEIM-TFSI cross-linked with poly(ethylene glycol) diacrylate (PEGDA). The Double cross-linked network of PIL-PEI reveals satisfactory flexibility, thermal stability and remarkable electrochemical performances (room-temperature ionic conductivity, 1.03 × 10−3 S cm−1 and lithium-ion transference number, 0.47). Furthermore, the compact network of PIL-PEI enables the formation of a strong solid electrolyte interface (SEI) layer on the lithium metal leading to the inhibition of lithium dendrite growth. As results, the batteries electrochemical performances, such as high charge/discharge capacity (165.6 mAh g−1), robust rate behavior (5.0C for 94 mAh g−1) and long-term lifespan (97.8% coulomb efficiency after 200 cycles) are significantly improved after assembled by LiFePO4-based cells equipping PIL-PEI as electrolyte. The soft package cell assembled with PIL-PEI is able to successfully light up the LED light and keep illuminating under varying hazardous situations such as bending and cutting, indicating that the PIL-PEI will have potential application value in highly secure flexible electronic devices.
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