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The bandwidth adaptation factor (BAF), which is calculated as BW • (λ L - λ H): (d • f r), is a crucial evaluation parameter for designing ultrathin broadband absorbers. In this paper, a high BAF absorber is designed by utilizing an impedance frequency selective surface (FSS), which includes a six pinnacles FSS, a La-doped mullite ceramic dielectric layer and a metal backplane. The optimal numbers of pinnacled FSS is determined through comparison and optimization, and the power monitor results indicate that the main loss modes are electrical and ohmic loss. Subsequently, the impedance analysis reveals that the favourable absorption performance is attributed to good impedance matching and high loss coefficient. Furthermore, the observation of the current distribution on the surface confirms that the primary loss appears at the pinnacles. The proposed absorber has below −10 dB reflectivity in 12.26–18.00 GHz. Meanwhile, the BAF is 3.36 and the thickness is only 0.061 λ L (1.5 mm). The measured results are in good agreement with the simulation results, demonstrating an excellent BAF characteristic. [ABSTRACT FROM AUTHOR]

In this paper, Er3+ doped TeO 2 -ZnF 2 -BaF 2 -KF-Ta 2 O 5 tellurite glasses with low hydroxyl content (∼0.03 × 10−19 cm−3) were investigated employing both glass composition and glass melting process optimization. The Raman spectra and physical properties were characterized to analyze the structure of the glasses. Under the pumping of 980 nm LD laser, intense up-conversion fluorescence at 1.5 and 2.7 μm of samples and their lifetimes were detected and analyzed, and the related transition mechanisms with gradient-varying Er3+ doping concentrations were discussed. The maximum absorption and emission cross section at 2.7 μm was calculated to be 6.4 × 10−21 cm2 and 6.8 × 10−21 cm2, correspondingly, which were higher than those of traditional tellurite glasses. Using the calculated and measured spectroscopic parameters of bulk tellurite glass, a dual-wavelength pumping model was established to verify the feasibility of mid-infrared laser output in similar tellurite glass fiber. Experimental results support the assertion that the Er3+ doped tellurite glasses hold promise as a candidate laser gain medium for mid-infrared fiber laser systems. [ABSTRACT FROM AUTHOR]

Abstract In this paper, BaAl 11 O 16 N (BAON) based oxynitride phosphors have been synthesized via the employment of the flux method and Eu2+/Mn2+ co-doped technique. The effects of different fluxes on phase formation of the phosphor have been investigated. It has been found that BaF 2 is the best flux to prepare BAON as it can decrease the pure phase-forming temperature (∼1550 °C) than the normal solid state synthesis (∼1700 °C). It also gives the best luminescence quantum efficiency. The crystallinity, morphology and grain size of the phosphor can be improved when more BaF 2 flux has been added. The photoluminescence (PL) spectra and decay curves for Eu2+/Mn2+co-doped BAON phosphors reveal that an efficient energy transfer (ET) from Eu2+ to Mn2+ takes place in the BAON host. The corresponding ET efficiencies and mechanisms are evaluated and the critical distance (R c) is calculated in terms of the experimental data and analysis. The emission colors of the co-doped phosphors can be tuned from blue to green by simply varying the doping concentrations of Mn2+. White light-emitting diodes (WLEDs) are fabricated by coating the as-prepared samples on a near ultraviolet (n- UV) LED chip to explore the real application potentials. The excellent performance of this WLEDs verifies that the co-doped phosphor can be used as an efficient green component. Graphical abstract Image 1 Highlights • A simple flux fusion routine for synthesizing BaAl 11 O 16 N:Eu2+,Mn2+ oxynitride phosphors. • Energy transfer between Eu2+ and Mn2+ takes a place in the BaAl 11 O 16 N host. • The WLEDs based on the as-prepared phosphors presents excellent warm white light performance. [ABSTRACT FROM AUTHOR]

Abstract In this paper, we studied the gamma photon attenuation properties for different germanate glasses systems with composition Sb 2 O 3 –GeO 2 –SiO 2 –Al 2 O 3 , TeO 2 –WO 3 –GeO 2 , GeO 2 –TeO 2 /SiO 2 –PbO–CaO–Tm 2 O 3 and B 2 O 3 –GeO 2 –Gd 2 O 3 –Eu 2 O 3 –GdF 3 –BaF 2. The mass attenuation coefficients (μ/ρ) for the selected germanate glasses were calculated at different energies (between 0.015 MeV and 15 MeV) using the MCNPX code. The calculated MCNPX μ/ρ values then compared with the WinXCom data to check the accuracy in the results. The results showed that the Sb 2 O 3 replacement by SiO 2 causes a decrease in μ/ρ for Sb 2 O 3 –GeO 2 –SiO 2 –Al 2 O 3 glass system. Also, it is found that for TeO 2 –WO 3 –GeO 2 glass system, μ/ρ decreases as GeO2 content increases from 1 to 20 mol%. While for GeO 2 –TeO 2 /SiO 2 –PbO–CaO–Tm 2 O 3 glass system, the results revealed that the glass samples contain TeO 2 possess higher μ/ρ values than the samples contain SiO 2. For the B 2 O 3 –GeO 2 –Gd 2 O 3 –Eu 2 O 3 –GdF 3 –BaF 2 glasses, we found that the μ/ρ values decrease as BaF 2 is increased from 0 to 15 mol%. Moreover, it is found that 50Sb-0Ge for series 1, TWG0 for series 2, 2G4T for series 3 and X = 0 for series 4 glass samples among the studied glasses have the highest effective atomic number values. On the basis of the results achieved, 50Sb-0Ge, TWG0, 2G4T and X = 0 samples have the best radiation shielding characteristics among the selected glasses. Highlights • Radiation shielding characteristics of different germanate glasses have been investigated. • The μ/ρ for the selected germanate glasses was evaluated by MCNPX simulation code at different energies. • The HVL results for the present germanate glasses suggested that the gamma photons absorption capacity increases as the density of the sample increases. [ABSTRACT FROM AUTHOR]

Aquatic contamination can settle into sediments, where it complexes with organic matter and becomes bioavailable. The resulting bioaccumulation of these contaminants by benthic fauna poses a serious threat due to the potential for trophic transfer. This paper offers an insight into the heterogenous accumulation behavior of different elements, and the consequences for ecological risk. In this study, we present field quantification of sediment-associated bioaccumulation factors (BAF S) in freshwater benthic macroinvertebrates. 17 elements were quantified using ICP-MS in sediment and Asellus aquaticus and Gammarus sp. samples. Previously published reports of contaminant concentrations in freshwater and marine sediments and benthic fauna were likewise analyzed to provide a complementary picture of bioaccumulation across contaminants and taxa. We demonstrate that the BAF S correlates strongly with the thiophilicity of the elemental contaminants, as defined by (Kepp, 2016), for all strata examined. These findings support the hypothesis that thiol-mediated processes, such as that of metallothionein, play a larger role in bioaccumulation than typically afforded. In conclusion, we demonstrate the potential for the thiophilic scale to act as a predictor of accumulation potential. [Display omitted] • Accumulation correlates strongly with thiophilicity across orders and environments. • Results support a thiol-based bioaccumulation process. • Bioavailability of contaminants can be predicted using the thiophilic scale. [ABSTRACT FROM AUTHOR]

• A simultaneous denitrification and biogas desulfurization process (SDBD) was proposed. • 0.9%–1.5% hydrogen sulfide in biogas was completely removed. • More than 85% COD, 98% NH 4 +-N and 81.65% TN was removed from real domestic sewage. • Hydrogen sulfide introduction altered the pathway of nitrate removal. • Economic assessment enables SDBD system to be a promising way in biological N removal. This paper proposed a novel simultaneous denitrification and biogas desulfurization (SDBD) process for domestic sewage treatment and biogas upgrading. The process consisted of an expanded granular sludge bed (EGSB) for integrated autotrophic and heterotrophic denitrification (IAHD) and a biological aerated filter (BAF) for nitrification. The experiments were firstly conducted to investigate the performance of the lab-scale SDBD system with real domestic sewage at various hydraulic retention times (HRT). The system successfully achieved 83.0 ± 1.8% chemical oxygen demand (COD), 96.2 ± 1.8% ammonia (NH 4 +-N) and 67.3 ± 4.1% total nitrogen (TN) removal efficiency without biogas introduction, and the optimal HRT of EGSB and BAF was determined to be 6 h and 4 h, respectively. Then, biogas with three different hydrogen sulfide concentrations (1.5%, 1.2% and 0.9%) was introduced into the system. Almost complete removal of hydrogen sulfide in biogas was achieved in all the tested scenarios and the removal efficiency of COD, NH 4 +-N and TN maintained at around 86.8%, 98.4% and 83.4%, respectively. Microbial community analysis results showed that biogas introduction notably increased the bacterial diversity and particularly enriched the nitrate-reducing, sulfide-oxidizing bacteria, which forms the major contribution to the hydrogen sulfide removal in the system. Finally, we put the SDBD system in the whole treatment system of domestic sewage and discussed its economics. The results indicated that the total operating cost of sewage treatment plant could be saved to 0.59 RMB/m3, which proved SDBD system to be a promising alternative way in biological nitrogen removal and biogas desulfurization. [ABSTRACT FROM AUTHOR]