Search

Photosynthetic and metabolomic performance of Euglena gracilis was examined and compared under autotrophic and mixotrophic conditions. Autotrophic protozoa (AP) obtained greater biomass (about 33% higher) than the mixotrophic protozoa (MP) after 12 days of growth. AP maintained steady photosynthesis, while MP showed a remarkable decrease in photosynthetic efficiency and dropped to an extremely low level at day 12. In MP, low light absorption and photosynthetic electron transport efficiency, and high energy dissipation were reflected by the chlorophyll (chl a) fluorescence (OJIP) of the protozoa. The values of ΨO, ΦEo, and ETO/RC of MP decreased to extremely low levels, to 1/15, 1/46, and 1/9 those of AP, respectively, while DIO/RC increased to approximately 16 times that of AP. A total of 137 metabolites were showed significant differences between AP and MP. AP accumulated more monosaccharide, lipids, and alkaloids, while MP produced more amino acids, peptides, and long-chain fatty acids including poly-unsaturated fatty acids. The top nine most important enriched pathways obtained from KEGG mapping were related to ABC transporters, biosynthesis of amino acids, purine metabolism, and carbohydrate metabolism. There were significant differences between AP and MP in photosynthetic activity, metabolites, and metabolic pathways. This work presented useful information for the production of high value bioproducts in E. gracilis cultured under different nutritional conditions. [ABSTRACT FROM AUTHOR]

The anaerobic digestion (AD) of food waste (FW) was augmented with ammonia-tolerant anaerobic sludge (ATAS). Different inoculum substrate ratios (ISR) under an initial ammonia stress of 4220 mg N/L were investigated. Results showed that the average specific methane production (SMP) of FW in the ATAS system increased by 36% compared with that in un-acclimated anaerobic sludge. SMP with ISR of 1:2.5 increased by approximately 6 times. Volatile fatty acids (VFAs) accumulation and sharp pH decline were not detected. These results revealed the high performance of ATAS in simultaneously relieving ammonia and acid stress. This improvement was attributed to multiple factors. ATAS had high ammonia tolerance and ability in conversion of acetate into methane. The equilibrium of NH3/NH4+, CO2/H2CO3/HCO3−, and CxHyCOOH/CxHyCOO− could promote VFAs and ammonia ionization, reduce the levels of free VFAs and ammonia, neutralize pH, and thus enhance the system's buffering capacity to be less susceptible to fluctuations. These results demonstrated that employing ATAS in improving AD performance and resilience from acid and ammonia inhibition is feasible and effective. [ABSTRACT FROM AUTHOR]

We introduce a new two-step method to fabricate silver-silicon gratings that can excite surface plasmons efficiently. The grating structure was firstly created on a flat silicon substrate by single-pulse nanosecond laser interference lithography. Next, a silver layer of 50 nm was evaporated on the silicon substrate. With proper laser energy, a silver-silicon grating with a period of 1120 nm and depth of 18 nm was successfully fabricated. This grating can produce high-quality surface plasmon resonance (SPR) peaks at various incident angles. Moreover, a SPR sensor was experimentally demonstrated based on the silver-silicon grating, which had high sensitivity of 961.5 nm/RIU and figure of merit of 60. Our method is an efficient way to fabricate periodically nanostructured metals at high speed and low cost. [ABSTRACT FROM AUTHOR]

Micro- and nanometallic structures that exhibit extraordinary optical transmission (EOT) have attracted much attention for their potential applications in photonic devices. However, most existing reports have only discussed EOT at one specific wavelength, which limits its use in multi-wavelength applications. Here, we experimentally demonstrate EOT at multiple wavelengths through an asymmetric corrugated thin silver film due to simultaneous excitation of multiple plasmonic resonances at both interfaces. A unique method that applies single-pulse nanosecond laser interference lithography is introduced to produce the silver grating, which shows high quality over large area. At oblique incidence, each EOT peak is observed to split into two peaks oppositely shifted towards higher and lower frequencies. At some specific angles of incidence, overlap of these shifted peaks gives rise to distorted transmission spectra. Our method may find applications involving multiple wavelengths such as multi-wavelength bandpass filters, anti-Stokes Raman scattering spectroscopy, enhanced four-wave mixing, and so on. [ABSTRACT FROM AUTHOR]

We propose a plasmonic structure based on the metal-insulator-metal waveguide with the side-coupled isosceles trapezoid cavities. Both of the structures based on the side-coupled trapezoid cavities separated or connected with waveguides can realize the plasmon-induced transparency (PIT). By adjusting the structure parameters, the off-to-on PIT response can be tunably achieved. The coupled mode theory (CMT) method is used to study the PIT phenomenon and explain the transmission characteristics. This work may provide a potential way for designing highly integrated photonic devices. [ABSTRACT FROM AUTHOR]

Electron shuttles extensively exist in various environments. Some kinds of organic substances can be applied by microorganisms to produce electrons, and then the electrons can be transferred to other substances or microorganisms through electron shuttles, resulting in coexistence and interaction of diverse species of microbes. In this review, the functional mechanisms of extracellular electron transfer mediated by different electron shuttles are described. And different subtypes as well as the application of electron shuttles in microbial degradation of pollutants, microbial electricity, and the promotion of energy generation are also discussed. Summary results show that extracellular electron transfer is based on the electrogenesis microorganism with the structure of cytochromes or pili. Materials were usually used in long-distance electron transfer because of their widespread presence and abundance. Therefore, the review is beneficial to perceive the pathways of extracellular electron transfer mediated by electron shuttles and explore the contribution of different electron shuttles in extracellular electron transfer. [ABSTRACT FROM AUTHOR]

We theoretically explore the appearances and characteristics of Fano resonances in novel-designed nanobelt cluster, which shows strong modulation depths, and the Fano dips can be tailored independently. The underlying physical mechanisms contributing to Fano resonances are discussed with the electric field enhancement and charge distributions. The results demonstrate that dark-mode excitation is not a necessary condition for the existence of Fano resonances in the nanobelt cluster. The lineshape of the scattering spectra can be regulated effectively by adjusting the geometrical parameters. The effect of the incident illumination polarization orientation is also numerically investigated, indicating that Fano resonances can be completely switched off when the nanobelt cluster is induced by 90°. Moreover, multiple Fano resonances would occur as the number of the nanobelt is increased, which is explained by a physical mechanism based on temporal coupled-mode theory. [ABSTRACT FROM AUTHOR]

In this work, light-extraction enhancement induced by localized surface plasmons (LSPs) on asymmetrical design of metallic nanoparticles (NPs) for AlGaN deep-ultraviolet (UV) light-emitting diodes (LEDs) is investigated numerically. The systems under study consist of Al NPs with varying diameter separated by a nano-gap, and the symmetrical dimer NPs with different geometrical parameters are studied for reference. We have demonstrated that tunable plasmonic NPs and spectral response can be controlled by varying the size of the nanoparticles and nano-gaps. It is found that the enhancement of the electric field and the peak position are subject to geometrical characteristics of the NP components in different manners for symmetrical and asymmetrical systems, respectively. High enhancement ratio for UV wavelength can be obtained by tuning parameters of asymmetrical system, which is potential for improving the performance of deep-UV LEDs. [ABSTRACT FROM AUTHOR]

Polycyclic aromatic hydrocarbon (PAH) and nitrated PAH (NPAH) products are toxic. Thus, determination of their concentrations is of great interest to researchers of soil and water pollution control. In this work, soil samples, surface water samples, and groundwater samples were collected, and the concentrations of 16 priority PAHs and 15 NPAHs were determined using an HPLC-ultraviolet detector. Results showed that the total PAH concentrations ranged within 489.69-1,670.11 ng/g (average = 905.89 ng/g) in soil samples, 4.00-23.4 μg/l (average = 9.84 μg/l) in surface water samples, and 2.14-22.3 μg/l (average = 8.37 μg/l) in groundwater samples. The NPAH concentrations were one to two orders of magnitude lower than the PAH concentrations and ranged within 22.72-128.70 ng/g (average = 63.88 ng/g) in soil samples. 2-Nitropyrene and 6-nitrochrysene were the most abundant compounds, accounting for about 14.3 and 26.5 %, respectively. Source analysis revealed that most PAHs originated from coal combustion around the study area, whereas NPAH studies suggested that the primary emission of gasoline engines and daytime OH reactions were the dominant sources of these compounds. [ABSTRACT FROM AUTHOR]