Two dimensional gradient-index beam shapers fabricated using ultrafast laser inscription.

In this paper gradient-index beam shapers are fabricated using the ultrafast laser inscription method. This method enables the fabrication of two-dimensional refractive index profiles inside silica glass, resulting in highly robust and compact beam shapers. The magnitude of this refractive index change can be tailored by adjusting the laser pulse energy, enabling arbitrary two-dimensional refractive index profiles to be manufactured. The process is then demonstrated by fabricating planar waveguides with quadratic index profiles that predictably resize Gaussian beams. Then a more complex two-dimensional refractive index profile is fabricated to transform an input Gaussian beam into a super-Gaussian (flat-top) beam.

Synthesize optimization, characterization, and application of ZIF-8 adsorbent for elimination of olive oil from aqueous solution.

In view of the importance of water quality and environmental aspect, zeolitic imidazolate framework-8 (ZIF-8) adsorbent was synthesized via a solvothermal approach for oil removal from water. Response surface methodology-central composite design approach (RSM-CCD) using a statistical software (Design expert, version 8.0.6) was employed to identify the influence of three independent variables of ZIF-8 synthesis procedure including ligand/salt molar ratio, solvent/salt molar ratio, and synthesis temperature on the oil adsorption capacity and yield of adsorbent as RSM responses. The optimum conditions for preparing ZIF-8 were found as follows: ligand/salt molar ratio of 10.4, solvent/salt ratio of 702.7, and temperature of 52.9 °C, which resulted in 1120 mg/g of olive oil uptake and 43% of ZIF-8 yield. Morphological and structural properties of the prepared adsorbent were characterized by N2 adsorption-desorption, XRD, FE-SEM, and FTIR analyses. Batch equilibrium adsorption experiments were conducted under varied system parameters expected to affect the ZIF-8 adsorption capacity including oil concentration, ZIF-8 dosage, contact time, and temperature. The isotherm and kinetic of olive oil adsorption onto ZIF-8 followed the Freundlich and pseudo-first-order models, respectively. The evaluation of thermodynamic parameters demonstrated that olive oil adsorption onto optimized ZIF-8 was spontaneous and exothermic in nature. In addition, the used ZIF-8 can be recovered effectively using a simple ethanol-washing method. Based on experimental results, the ZIF-8 prepared in this study can be successfully used in oil/water emulsion separation.

Facile decoding of quantitative signatures from magnetic nanowire arrays.

Magnetic nanoparticles have been proposed as contact-free minimal-background nanobarcodes, and yet it has been difficult to rapidly and reliably decode them in an assembly. Here, high aspect ratio nanoparticles, or magnetic nanowires (MNWs), are characterized using first-order reversal curves (FORC) to investigate quantitative decoding. We have synthesized four types of nanowires (differing in diameter) that might be used for barcoding, and identified four possible "signature" functions that might be used to quickly distinguish them. To test this, we have measured the signatures of several combination samples containing two or four different MNW types, and fit them to linear combinations of the individual type signatures to determine the volume ratios of the types. We find that the signature which determines the ratios most accurately involves only the slope of each FORC at its reversal field, which requires only 2-4 data points per FORC curve, reducing the measurement time by a factor of 10 to 50 compared to measuring the full FORC.

Effects of perlite and caustic soda on microorganism activities of leachate in a sequence batch reactor.

The purpose of this article is to evaluate the effect of adsorbents and alkali pre-treatment on microorganism activities of activated sludge (AS) for the treatment of landfill leachate (LFL). The chemical oxygen demand (COD) and BOD5/COD ratio of LFL used in this research were 10,500 and 0.68, respectively. In order to survey the role of porous absorbent, perlite was employed as an alternative with low porosity and was compared to powdered activated carbon (PAC), which has been most widely used in the treatment process. As a result, the COD removal efficiency increased from 32% to 47.7% when alkali LFL was loaded to the sequence batch reactors (SBRs) at the optimum conditions of the biological process. Also, at the same condition, both SBRs containing PAC and perlite showed COD removals of over 81% and 72%, respectively. The specific oxygen uptake rate (SOUR) showed that alkali pre-treatment reduces the toxicity effect of heavy metals on microorganism activities. The adsorption capacity (the uptake of COD) was analyzed by Langmuir and Freundlich isotherm models. Further, the kinetic study of COD adsorption during the treatment process demonstrated that the alkali pre-treatment of LFL proceeded faster and was intensified by the presence of adsorbents.

Sulfide as an alternative electron donor to glucose for power generation in mediator-less microbial fuel cell.

The objective of this study was to investigate the power generation in a dual-chamber microbial fuel cell (MFC). As one of the effective parameters, glucose concentration was studied in the range of 100-1000 mg/L. At the optimum concentration of 500 mg/L of glucose, maximum power generation was 186 mW/m2. As an alternative, sulfide was used as an electron donor and maximum power output was 401 mW/m2 at the concentration of 100 mg/L; which was more than twice of power produced using glucose. Moreover, sulfide removal efficiencies of 70%, 66%, 60%, and 64% were obtained when initial sulfide concentrations of 10, 20, 80, and 100 mg/L were used, respectively.

Electricity generation through degradation of organic matters in medicinal herbs wastewater using bio-electro-Fenton system.

In the present study, the potential application of the bio-electro-Fenton (BEF) process for the treatment of medicinal herbs wastewater in a mediator-less microbial fuel cell (MFC) system is investigated. This process is operated in a dual-chamber MFC with anaerobic seed sludge as biocatalyst in an anode chamber under conditions of neutral pH, an aerobic cathode chamber equipped with a Fe@Fe2O3/graphite composite cathode and a Nafion membrane as a separator. The performance of the MFC is determined in three different mixed liquor suspended solids (MLSS) loadings, Nafions (112, 115) and a salt bridge in an air-cathode BEF process, in terms of power generation, chemical oxygen demand (COD) removal efficiency, columbic and energy efficiencies. Under optimal conditions, the batch experiment results show that the cathode chamber of the BEF reactor, equipped with Nafion 112 and inoculated with seed sludge at 3000 mg L(-1) MLSS concentration, produces the maximum power density of 49.76 mW m(-2), 0.56 mg L(-1) and 29 mol L(-1) of H2O2 and Fe(2+), respectively. Under these conditions, the MFC achieves COD removal 78.05% in the anaerobic anode chamber and 84.02% as a result of aerobic processes from the air-cathode BEF chamber, whilst the maximum voltage εcb and εE values are 600 mV, 4.09% and 1.37%, respectively.

Power production and wastewater treatment simultaneously by dual-chamber microbial fuel cell technique.

Microbial fuel cell (MFC) is a novel technology that is able to convert the chemical energy of organic and inorganic substrates to electrical energy directly. The use of fossil fuels and recent energy crisis bring increasing attention to this technology. Besides electricity generation, wastewater treatment is another application of MFCs. Sulfide is a hazardous ion that is common in wastes. In this article, dual-chamber MFC was fabricated and a mixed culture of microorganisms was used as an active biocatalyst in an anaerobic anodic chamber to convert substrate to electricity. The obtained experimental results indicate that this MFC can successfully alter sulfide to elementary sulfur and power generation. The initial concentration of sulfide in wastewater was 1.5 g L(-1) , and it was removed after 10 days of MFC operation. Maximum produced power and current density were 48.68 mW⋅m(-2) and 231.47 mA⋅m(-2) , respectively. Besides, the influences of a biocathode were investigated and accordingly the data obtained for power and current density were increased to 372.27 mW⋅m(-2) and 1,665.15 mA⋅m(-2) , respectively.

Thionine increases electricity generation from microbial fuel cell using Saccharomyces cerevisiae and exoelectrogenic mixed culture.

Microbial fuel cells (MFCs) have been shown to be capable of clean energy production through the oxidation of biodegradable organic waste using various bacterial species as biocatalysts. In this study we found Saccharomyces cerevisiae, previously known electrochemcially inactive or less active species, can be acclimated with an electron mediator thionine for electrogenic biofilm formation in MFC, and electricity production is improved with facilitation of electron transfer. Power generation of MFC was also significantly increased by thionine with both aerated and non-aerated cathode. With electrochemically active biofilm enriched with swine wastewater, MFC power increased more significantly by addition of thionine. The optimum mediator concentration was 500 mM of thionine with S. cerevisae in MFC with the maximum voltage and current generation in the microbial fuel cell were 420 mV and 700 mA/m(2), respectively. Cyclic voltametry shows that thionine improves oxidizing and reducing capability in both pure culture and acclimated biofilm as compared to non-mediated cell. The results obtained indicated that thionine has great potential to enhance power generation from unmediated yeast or electrochemically active biofilm in MFC.