A low temperature Co-fired ceramic-based dielectrophoretic device for manipulating micro and nanostructure materials.

A dielectophoretic (DEP) device fabricated by a conventional low temperature co-fired ceramic (LTCC) process, for manipulating micro and nanostructure materials, such as spherical polystyrene microspheres, titanium dioxide (TiO2) nanotubes, and silver (Ag) nanowires, is described. To generate a non-uniform electric field, a castellated electrode configuration was applied to the LTCC-based DEP device using a screen printing method. The actual motions of the micro and nanostructure materials under both a positive and a negative DEP force were observed in detail and the findings compared with numerical simulation data for the electric field distribution. The performance of the LTCC-based DEP device for separating and trapping was evaluated and potential applications are discussed.

Variations of electron flux and microbial community in air-cathode microbial fuel cells fed with different substrates.

Microbial fuel cells (MFCs) can convert chemical energy to electricity using microbes as catalysts and a variety of organic wastewaters as substrates. However, electron loss occurs when fermentable substrates are used because fermentation bacteria and methanogens are involved in electron flow from the substrates to electricity. In this study, MFCs using glucose (G-MFC), propionate (P-MFC), butyrate (B-MFC), acetate (A-MFC), and a mix (M-MFC, glucose:propionate:butyrate:acetate = 1:1:1:1) were operated in batch mode. The metabolites and microbial communities were analyzed. The current was the largest electron sink in M-, G-, B-, and A-MFCs; the initial chemical oxygen demands (COD(ini)) involved in current production were 60.1% for M-MFC, 52.7% for G-MFC, 56.1% for B-MFC, and 68.3% for A-MFC. Most of the glucose was converted to propionate (40.6% of COD(ini)) and acetate (21.4% of COD(ini)) through lactate (80.3% of COD(ini)) and butyrate (6.1% of COD(ini)). However, an unknown source (62.0% of COD(ini)) and the current (34.5% of COD(ini)) were the largest and second-largest electron sinks in P-MFC. Methane gas was only detected at levels of more than 10% in G- and M-MFCs, meaning that electrochemically active bacteria (EAB) could out-compete acetoclastic methanogens. The microbial communities were different for fermentable and non-fermentable substrate-fed MFCs. Probably, bacteria related to Lactococcus spp. found in G-MFCs with fermentable substrates would be involved in both fermentation and electricity generation. Acinetobacter-like species, and Rhodobacter-like species detected in all the MFCs would be involved in oxidation of organic compounds and electricity generation.

Giant Magnetic Heat Induction of Magnesium-Doped γ-Fe2 O3 Superparamagnetic Nanoparticles for Completely Killing Tumors.

Magnetic fluid hyperthermia has been recently considered as a Renaissance of cancer treatment modality due to its remarkably low side effects and high treatment efficacy compared to conventional chemotheraphy or radiotheraphy. However, insufficient AC induction heating power at a biological safe range of AC magnetic field (Happl ·fappl < 3.0-5.0 × 109 A m-1 s-1 ), and highly required biocompatibility of superparamagnetic nanoparticle (SPNP) hyperthermia agents are still remained as critical challenges for successful clinical hyperthermia applications. Here, newly developed highly biocompatible magnesium shallow doped γ-Fe2 O3 (Mg0.13 -γFe2 O3 ) SPNPs with exceptionally high intrinsic loss power (ILP) in a range of 14 nH m2 kg-1 , which is an ≈100 times higher than that of commercial Fe3 O4 (Feridex, ILP = 0.15 nH m2 kg-1 ) at Happl ·fappl = 1.23 × 109 A m-1 s-1 are reported. The significantly enhanced heat induction characteristics of Mg0.13 -γFe2 O3 are primarily due to the dramatically enhanced out-of-phase magnetic susceptibility and magnetically tailored AC/DC magnetic softness resulted from the systematically controlled Mg2+ cations distribution and concentrations in octahedral site Fe vacancies of γ-Fe2 O3 instead of well-known Fe3 O4 SPNPs. In vitro and in vivo magnetic hyperthermia studies using Mg0.13 -γFe2 O3 nanofluids are conducted to estimate bioavailability and biofeasibility. Mg0.13 -γFe2 O3 nanofluids show promising hyperthermia effects to completely kill the tumors.

Effects of Recovery Time during Magnetic Nanofluid Hyperthermia on the Induction Behavior and Efficiency of Heat Shock Proteins 72.

In this study, we investigated the effects of recovery time during magnetic nanofluid hyperthermia (MNFH) on the cell death rate and the heat shock proteins 72 (HSP72) induction behavior in retinal ganglion cells (RGCs-5) to provide a possible solution for highly efficient ocular neuroprotection. The recovery time and the heat duration time during MNFH were systematically controlled by changing the duty cycle of alternating current (AC) magnetic field during MNFH. It was clearly observed that the cell death rate and the HSP72 induction rate had a strong dependence on the recovery time and the optimizated recovery time resulted in maximizing the induction efficiency of HSP72. Controlling the recovery time during MNFH affects not only the cell death rate but also HSP72 induction rate. The cell death rate after MNFH was dramatically decreased by increasing the recovery time during MNFH. However, it was also found that the HSP72 induction rate was slightly decreased by increasing the recovery time. These results indicate that applying the appropriate or optimized recovery time during MNFH can improve the induction efficiency of HSP72 by minimizing the cell death caused by cytotoxic effects of heat.

Manipulation of TiO2 Nanotubes in a Transparent Dielectrophoretic Device.

A DEP device with a transparent oxide thin film electrode was fabricated by a photolithography process and sputtering deposition with indium tin oxide (ITO). In order to form a fine ITO electrode pattern, we manipulated the negative slope using a photoresist by controlling the intensity of the ultra-violet radiation and the exposure time. In this study, the motions of a 1 microm polystyrene sphere and TiO2 nanotube were observed as a function of the applied voltage and the frequency. The findings confirm that TiO2 nanotubes can be manipulated by a p-DEP force and that they can be effectively aligned under conditions of 10 V(p-p) at 750 Hz.

Bacterial community structure in maximum volatile fatty acids production from alginate in acidogenesis.

Alginate as biomass feedstock for bioconversion into volatile fatty acids (VFAs) is limited primarily by the low solubility in water or little utilization as microbial substrate and yet unknown about the microbial community structure for acidogenesis. The bacterial community structure was demonstrated the reflected changes in VFAs profiles in the maximized acidogenic process from alginate. Bacteroides- and Clostridium-related microorganisms were suggested to be mainly responsible for the hydrolysis of alginate and VFAs production, respectively. And the bacterial community shifted corresponded to VFAs producing was statistically demonstrated. A number of features discussed in this research can stimulate further interests on bioconversion of alginate into anaerobic biofuels production.

Evaluation of thermal, ultrasonic and alkali pretreatments on mixed-microalgal biomass to enhance anaerobic methane production.

Anaerobic digestion was regarded as one of the ways to recover energy from mixed-microalgae biomass in this study. After applying thermal-, ultrasonic-, and alkali-pretreatments to raw microalgae biomass to promote the digestion efficiency, a biochemical methane potential was investigated to evaluate the effectiveness of the pre-treatments for the purpose. As the pretreatment intensity increased, the solubilization of the mixed microalgae increased. However, the increased solubilization was not followed proportionally by the increased methane production. The highest methane productivity was achieved by the thermal-pretreatment at 120 °C (405 mL CH4/g-VS), which was 1.2 times higher than that of the non-pretreatment condition (336 mL CH4/g-VS). The net energy analysis revealed that only the pretreatment adjusted to pH 9 yielded a slightly higher energy gains (12.8 kJ/g-VS) than that of non-pretreatment condition (11.9 kJ/g-VS). These findings recommend direct supply of microalgae biomass for anaerobic digestion.

Maximization of volatile fatty acids production from alginate in acidogenesis.

In this study, the response surface methodology (RSM) was applied to determine the optimum fermentative condition of alginate with the respect to the simultaneous effects of alginate concentration and initial pH to maximize the production of total volatile fatty acids (TVFAs) and alcohols. The results showed that the alginate fermentation was significantly affected by initial pH than by alginate concentration and there was no interaction between the two variables. The optimum condition was 6.2g alginate/L and initial pH 7.6 with a maximum TVFAs yield of 37.1%. Acetic acids were the main constituents of the TVFAs mixtures (i.e., 71.9-95.5%), while alcohols (i.e., ethanol, butanol, and propanol) were not detected.

Electricity generation and microbial community in a submerged-exchangeable microbial fuel cell system for low-strength domestic wastewater treatment.

A submerged type microbial fuel cell (MFC) system, which consisted of six readily exchangeable air-cathode MFCs, was evaluated for continuous treatment of low-strength domestic wastewater. When supplied with synthetic wastewater (COD 100 mg/L), the system showed increasing maximum power densities from 191 to 754 mW/m2 as COD loading rates increased (0.20-0.40 kg/m3/day). COD removal efficiencies decreased with increased COD loading rates but the effluent COD concentrations met the relevant effluent quality standard (CODMn 20 mg/L) at all conditions. The system was then operated with domestic wastewater (c.a. 100 mg COD/L) at 0.32 and 0.43 kg/m3/day. The system showed much lower power densities (116-149 mW/m2) at both loading rates, compared to synthetic wastewater. Anodic microbial communities were completely different when the wastewater type was changed. These results suggest that the newly developed MFC system could be applied to treat low-strength domestic wastewater without requiring any additional organic removal stage.

Comparison of nitrogen removal and microbial distribution in wastewater treatment process under different electron donor conditions.

The applicability of modified spent caustic (MSC) as an electron donor for denitrification was evaluated in a lab-scale reactor for the Bardenpho process under various electron donor conditions: (A) no electron donor, (B) methanol, (C) thiosulfate and (D) MSC conditions. TN removal efficiency varied in each condition, 23.1%, 87.8%, 83.7% and 71.7%, respectively. The distribution ratio of nitrifying bacteria and DGGE profile including sulfur-reducing or oxidizing bacteria also varied depending on the conditions. These results indicated that the MSC would be used as an efficient electron donor for denitrification by autotrophic denitrifier in wastewater treatment process.