Pre-fermentation of waste as a strategy to enhance the performance of single chambered microbial fuel cell (MFC)

Functional role of pre-fermentation of food waste (PFW) was studied to enhance the performance of single chambered microbial fuel cell (MFC) (mediatorless; non-catalyzed graphite electrodes; open-air cathode). Significant improvement in power output was noticed after pre-treatment (391 mV; 530 mA/m²) compared to unfermented waste (275 mV; 361 mA/m²). MFC performance was found to depend on applied organic load and nature of substrate in terms of power generation and substrate degradation. The pre-fermentation of waste facilitated lowering of activation losses and in turn increased the bio-electrochemical activity of biocatalyst, leading to an effective MFC performance. Fuel cell behavior with respect to polarization, anode potential and bio-electrochemical behavior also supported the performance of MFC with PFW. PFW operation showed higher catalytic current in voltammograms with fine catalytic peaks supporting the positive role of pre-fermentation in discharging electrons effectively. VFA and pH profiles also correlated well with power generation and substrate degradation pattern.     

Effect of ionic strength, cation exchanger and inoculum age on the performance of Microbial Fuel Cells

Power generation in Microbial fuel cells (MFCs) is a function of various physico-chemical as well as biological parameters. In this study, we have examined the effect of ionic strength, cation exchanger and inoculum age on power generation in a mediator MFC with methylene blue as electron mediator using Enterobacter cloacae IIT-BT08. The effect of ionic strength was studied using NaCl in the anode chamber of a two chambered salt-bridge MFC at concentrations of 5 mM, 10 mM and 15 mM. Maximum power density of 12.8 mW/m² was observed when 10 mM NaCl was used. Corresponding current density was noted to be 35.5 mA/m². Effect of cation exchanger was observed by replacing salt-bridge with a proton exchange membrane of equal surface area. When the salt-bridge was replaced by a proton exchange membrane, a 3-fold increase in the power density was observed. Power density and current density of 37.8 mW/m² and 110.3 mA/m² respectively were detected. The influence of the pre-inoculum on the MFC was studied using E. cloacae IIT-BT08 grown for 12, 14, 16 and 18 h. It was observed that 16 h grown culture when inoculated in the anode chamber gave the maximum power output. Power density and current density of 68 mW/m² and 168 mA/m² respectively were obtained. We demonstrate from these results that both physico-chemical as well as biological parameters need to be optimized for improving the power generation in MFCs.     

Fabrication and Characterization of MWCNT Filled Hybrid Natural Fiber Composites

Hybrid composites are fabricated by the combination of two or more fibers using a single matrix. It can be fabricated either with all of its constituents as natural fibers or with one or more constituents belonging to artificial fiber. The stacking sequence of the fibers in a hybrid composite can be altered resulting in a varying mechanical properties. In the present study the MWCNT filled banana-jute-flax fiber reinforced composites are investigated for its mechanical behavior by varying the stacking sequence of the fiber layers and weight % of Multi-Walled Carbon Nano Tube (MWCNT). A Modified resin was prepared by adding MWCNT in the epoxy resin using ultrasonic probe sonicator and a hybrid composite is fabricated with it by using compression moulding processes. The mechanical properties are evaluated as per the ASTM standards. The incorporating of MWCNT and the stacking sequence of fiber layers shows the greater impact on the mechanical properties. The composites of jute fibers at the extremities (JBFBFBFJ) exhibiting the enhancement of tensile, compressive and hardness properties than the flax fiber at the extremities (FBJBJBJF) and it could be used in various automobile applications. Microstructure of the samples are investigated by Scanning Electron Microscope (SEM)with Energy dispersive X-ray (EDS). The results indicate that increasing the weight % of MWCNT and varying the stacking sequence of fibers improves the mechanical properties of hybrid natural fiber composites.     

Chemistry, biogenesis, and biological activities of Cinnamomum zeylanicum

The genus Cinnamomum comprises of several hundreds of species, which are distributed in Asia and Australia. Cinnamomum zeylanicum, the source of cinnamon bark and leaf oils, is an indigenous tree of Sri Lanka, although most oil now comes from cultivated areas. C. zeylanicum is an important spice and aromatic crop having wide applications in flavoring, perfumery, beverages, and medicines. Volatile oils from different parts of cinnamon such as leaves, bark, fruits, root bark, flowers, and buds have been isolated by hydro distillation/steam distillation and supercritical fluid extraction. The chemical compositions of the volatile oils have been identified by GC and GC-MS. More than 80 compounds were identified from different parts of cinnamon. The leaf oil has a major component called eugenol. Cinnamaldehyde and camphor have been reported to be the major components of volatile oils from stem bark and root bark, respectively. Trans-cinnamyl acetate was found to be the major compound in fruits, flowers, and fruit stalks. These volatile oils were found to exhibit antioxidant, antimicrobial, and antidiabetic activities. C. zeylanicum bark and fruits were found to contain proanthocyandins with doubly linked bis-flavan-3-ol units in the molecule. The present review provides a coherent presentation of scattered literature on the chemistry, biogenesis, and biological activities of cinnamon.     

Glucosinolates fortification of cruciferous sprouts by sulphur supplementation during cultivation to enhance anti-cancer activity

The cruciferous sprouts, including cabbage (Brassicaoleracea), broccoli (Brassicacapitata) and radish (Raphanussativus), were cultivated with supplementation of sulphur salts. With supplementation of sulphur at 60 kg/ha, a 2–5-fold increases in total glucosinolates contents in the sprouts were observed. The individual glucosinolates whose concentration increased most significantly, included progoitrin, glucoerucin, glucobrassicin, glucohirsutin and 4-methoxybrassicin. The antioxidant properties of these sulphur supplemented sprouts were also higher than that of the normal sprouts due to the increases of phenolic compounds. Consequently, the glucosinolates fortified sprouts had higher anti-proliferative activity against HepG2 human hepatocarcinoma cells than the normal sprouts, as the cell viability decreased by 22–35%. Also in CT26 mouse colorectal cancer cells, the cell viability decrease by 34–59%.     

Synthesis of DBSA-doped Polyaniline by Emulsion Polymerization and PANI/PLA Electrospun Fiber Membrane Conductivity

Polyaniline (PANI) has gained interest due to its reasonably good conductivity, stability, easy preparation, affordability, and redox properties. Aniline monomers, emulsifiers, and dopant DBSA are used for emulsion polymerization in water, using various oxidants. The DBSA-doped polyaniline was extracted via a chloroform solution, and PLA was added directly in the emulsion to form the DBSA-PANI/PLA composite electrospinning solution. The DBSA-PANI/PLA composite nanofiber membrane was prepared via electrospinning. FeCl₃, K₂Cr₂O₇, and ammonium persulfate were used as oxidants in the emulsion polymerization process. The Infrared spectra showed the full characteristic peaks of polyaniline when ammonium persulfate was used as an oxidant. The transmission rate of the characteristic peak became smaller when the ratio of ammonium persulfate/aniline monomer increased from 0.5 to 1, demonstrating the polyaniline content increased. The electrospun nanofibers that were prepared were spindle-shaped fibers and the fiber diameter distribution was wide. The PANI/PLA electrospun fiber membrane conductivity was several orders of magnitude higher than the pure PLA membrane. The PANI/PLA electrospun fiber membrane had the highest conductivity (9.1 × 10^-3 S/cm) when (APS/An) = 1.0. This prepared PANI/PLA nanometer fiber membrane could be used for electromagnetic shielding and could be an effective biomaterial within the engineering of electrically responsive biological tissues and organs.     

In vitro inactivation of Escherichia coli O157:H7 in bovine rumen fluid by caprylic acid

The antibacterial effect of caprylic acid (35 and 50 mM) on Escherichia coli O157:H7 and total anaerobic bacteria at 39 degrees C in rumen fluid (pH 5.6 and 6.8) from 12 beef cattle was investigated. The treatments containing caprylic acid at both pHs significantly reduced (P < 0.05) the population of E. coli O157:H7 compared with that in the control samples. At pH 5.6, both levels of caprylic acid killed E. coli O157:H7 rapidly, reducing the pathogen population to undetectable levels at 1 min of incubation (a more than 6.0-log CFU/ml reduction). In buffered rumen fluid at pH 6.8, 50 mM caprylic acid reduced the E. coli O157:H7 population to undetectable levels at 1 min of incubation, whereas 35 mM caprylic acid reduced the pathogen by approximately 3.0 and 5.0 log CFU/ml at 8 and 24 h of incubation, respectively. At both pHs, caprylic acid had a significantly lesser (P < 0.05) and minimal inhibitory effect on the population of total anaerobic bacteria in rumen compared with that on E. coli O157:H7. At 24 h of incubation, caprylic acid (35 and 50 mM) reduced the population of total anaerobic bacteria by approximately 2.0 log CFU/ml at pH 5.6, whereas at pH 6.8, caprylic acid (35 mM) did not have any significant (P > 0.05) inhibitory effect on total bacterial load. Results of this study revealed that caprylic acid was effective in inactivating E. coli O157:H7 in bovine rumen fluid, thereby justifying its potential as a preslaughter dietary supplement for reducing pathogen carriage in cattle.     

Accelerated and environmental weathering studies on polyethylene–starch blend films

Biodegradable polymers are desirable for a variety of applications, such as in packaging, agriculture, and medicine. Polyethylene (PE) blended with starch is already found to be a potential candidate to replace nondegradable thermoplastics in the areas of packaging. Films of polyethylene (PE)–starch blends with and without vegetable oil as a compatibilizer were prepared. The degradation of the films under thermooxidative treatment, ultraviolet light exposure, high temperature, high humidity, and natural ambience (soil burial) were monitored. It is seen that vegetable oil as an additive has a dual role: as a plasticizer, it improves the film quality; as a prooxidant, it accelerates degradation of the film. © 1998 John Wiley & Sons, Inc. J Appl Polym Sci 70: 2251–2257, 1998     

Flow channels/fiber impregnation studies for the process modeling/analysis of complex engineering structures manufactured by resin transfer molding

The success of resin transfer molding (RTM) depends upon the complete wetting of the fiber preform. Effective mold designs and process modifications facilitating the improved impregnation of the preform have direct impact on the successful manufacturing of parts. Race tracking caused by variations in permeabilities around bends, corners in liquid composite molding (LCM) processes such as RTM have been traditionally considered undesirable, while related processes such as vacuum assisted RTM (VARTM) and injection molding have employed flow channels to improve the resin distribution. In this paper, studies on the effect of flow channels are explored for RTM through process simulation studies involving flow analysis of resin, when channels are involved. The flow in channels has been modeled and characterized based on equivalent permeabilities. The flow in the channels is taken to be Darcian as in the fiber preform, and process modeling and simulation tools for RTM have been employed to study the flow and pressure behavior when channels are involved. Simulation studies based on a flat plate indicated that the pressures in the mold are reduced with channels, and have been compared with experimental results and equivalent permeability models. Experimental comparisons validate the reduction in pressures with channels and validate the use of equivalent permeability models. Numerical simulation studies show the positive effect of the channels to improve flow impregnation and reduce the mold pressures. Studies also include geometrically complex parts to demonstrate the positive advantages of flow channels in RTM.     

High temperature thermal expansion characteristics of Ni3Al alloys

The thermal expansion of Ni₃Al alloys with and without ternary additions have been investigated with the aid of a dilatometer. The Ni₃Al alloys were studied over the temperature range 25–1000 °C. The coefficient of thermal expansion of all the aluminides studied in this investigation varies linearly with the temperature. The coefficient of thermal expansion of Ni₃Al is found to show an increase with the decrease in Al content from stoichiometric composition. B and Zr additions decrease the value of Ni₃Al alloys at room temperature while Hf and Ti additions do not alter it significantly.