Improvement of capacitance value as the electrode of an electrochemical capacitor by mixing starch with guanidine phosphate

Starch or starch mixed with phosphoric acid, guanidine carbonate, or guanidine phosphate is heat-treated for use as an electrode in an electrochemical capacitor. In the case of starch, the capacitance value is low (31.2 F g⁻¹ at 50 mA g⁻¹). However, the capacitance value significantly increases with the addition of guanidine phosphate, which can act as a flame-retardant (124.1F g⁻¹ at 50 mA g⁻¹). The method used in this study, which involves mixing with a flame-retardant by immersion, should be a promising candidate for improving of the capacitance value of starch-derived carbon.     

Long-term performance of high-reflectivity exterior panels

Paint performance was assessed over time with respect to surface contamination and degradation of reflectivity through environmental exposure tests. Test panels were coated with high-reflectivity or conventional paints. One set of test panels was coated with high-reflectivity paint on site or in-factory at the manufacturing stage by a newly developed heat curing paint method. Following environmental exposure, this heat curing paint method was evaluated for its long-term performance in thermal conditioning, and durability, as well as for possible performance enhancement with the addition of a photocatalyst. Solar reflectivity of the panels was degraded by exposure to ultraviolet light, adhesion of airborne contaminants, and exposure to high temperatures and precipitation. Newly developed high-reflectivity heat curing paint was just as durable as conventional heat curing paint. In addition, panels coated with a photocatalyst in-factory achieved a high level of solar reflectivity for a longer period compared to panels coated with conventional paint in-factory and high-reflectivity paint on site.     

Estimation Method for Liquidus Temperature of Lead-Free Solder Using Differential Scanning Calorimetry Profiles

It is usually complicated to analyze the liquidus temperature of lead-free solder, because unlike Sn-Pb eutectic solder, supercooling easily occurs during the cooling process of lead-free solder, and common lead-free solders contain only a small fraction of a primary phase. In order to determine the melting temperature range of lead-free solder easily, an estimation method using differential scanning calorimetry (DSC) profiles is proposed. The purpose of this study is to show the applicability of the newly proposed DSC-based approach. DSC profiles using several heating rates were measured and analyzed. As a result, it was found that the extrapolated onset temperature, the peak temperature, and the extrapolated end temperature of the endothermic peak were proportional to the square root of the DSC heating rate. For lower heating rate, the temperature–axis intercept of the relationship between the square root of the heating rate and the peak temperature can be regarded as the liquidus temperature under equilibrium conditions with better accuracy. For higher heating rate, the temperature–axis intercept of the relationship between the square root of the heating rate and the extrapolated end temperature can be approximately estimated as the liquidus temperature of noneutectic lead-free solder under equilibrium conditions.     

Production of bacterial endoglucanase from pretreated oil palm empty fruit bunch by bacillus pumilus EB3

In this study, endoglucanase was produced from oil palm empty fruit bunch (OPEFB) by a locally isolated aerobic bacterium, Bacillus pumilus EB3. The effects of the fermentation parameters such as initial pH, temperature, and nitrogen source on the endoglucanase production were studied using carboxymethyl cellulose (CMC) as the carbon source. Endoglucanase from B. pumilus EB3 was maximally secreted at 37 degrees C, initial pH 7.0 with 10 g/l of CMC as carbon source, and 2 g/l of yeast extract as organic nitrogen source. The activity recorded during the fermentation was 0.076 U/ml. The productivity of the enzyme increased twofold when 2 g/l of yeast extract was used as the organic nitrogen supplement as compared to the non-supplemented medium. An interesting finding from this study is that pretreated OPEFB medium showed comparable results to CMC medium in terms of enzyme production with an activity of 0.063 U/ml. As OPEFB is an abundant solid waste at palm oil mills, it has the potential of acting as a substrate in cellulase production.     

Enhanced anthocyanin production from grape callus in an air-lift type bioreactor using a viscous additive-supplemented medium

An N-medium containing carboxymethyl cellulose (CMC) was applied to an air-lift type bioreactor culture of grape (Vitis vinifera cv. Bailey alicant A.) callus, and anthocyanin production was investigated. Grape callus grew well at an air flow rate of 80 ml/min and anthocyanin production was significantly increased in the N-medium, reaching 17 mg/l after 7 d of culture. The anthocyanin content of the N-medium was about two times higher than that of the conventional medium without CMC. The effect of air flow rate was also investigated within the range from 40 to 160 ml/min. A twofold increase in anthocyanin content was obtained at all the air flow rates tested in the N-medium. The distribution of grape callus size obtained after 7 d of the bioreactor culture was investigated. The average callus size was 490 mum which was 1.6 times larger than that obtained in the conventional medium. It was found that large calli with a relatively high anthocyanin pigment content were formed in the bioreactor culture using the N-medium. The fluid dynamics in the bioreactor was also investigated at three points (top, middle and bottom) in the bioreactor by laser doppler velocimetry. The average axial velocity of the circulated medium was 0.4 times lower than that of the conventional medium while their average radial velocities were almost the same (zero). The standard deviation of radial velocity fluctuation in the N-medium was also 0.4 times less than that in the conventional medium. These results suggest that turbulent flow occurred in the bioreactor culture using the conventional medium and the degree of turbulent flow decreased significantly when 0.8% CMC was added to the medium to prepare the N-medium. A change of the flow pattern is considered to be the cause of the decrease in hydrodynamic stress, resulting in enhanced pigment production due to the enlargement of the callus.     

Degradation of cell wall materials from sweetpotato, cassava, and potato by a bacterial protopectinase and terminal sugar analysis of the resulting solubilized products

Cell wall materials (CWMs) from sweetpotato, cassava, and potato starch residues were degraded using a crude enzyme solution from the culture filtrate of a Bacillus sp. isolated from soil, Bacillus sp. M4. This organism has been found to secrete polygalacturonic acid lyase (PGL) and glycan depolymerase activities, especially arabinanase, but cellulase activity was nearly absent. Sugar analysis of the solubilized product after enzyme treatment at pH 7.0 revealed that it is mainly composed of galacturonic acid, galactose, and arabinose, the sugars found commonly in the pectin fraction. This suggested the presence of a protopectinase (PPase) activity in the culture filtrate. The presence of EDTA completely inhibited PGL but PPase activity was almost retained, suggesting that the PGL is not the primary activity responsible for pectin solubilization. The mode of action of the crude enzyme was determined by terminal sugar analysis using HPAEC-PAD after hydrolysis of the reduced products. Results revealed that galactose is the main neutral sugar at the reducing terminal of the products, although rhamnose was also present in the higher molecular weight component. This suggested that at neutral pH, the primary activity in the culture filtrate of Bacillus sp. M4 is a B-type PPase, which attacked the galactan as well as rhamnogalacturonan moieties of the protopectin, resulting in the release of a soluble pectin fraction.     

The effect of surfactant solutions on the growth rate of environmental stress cracking of low-density polyethylene

The growth rate of environmental stress cracking (ESC) of low-density polyethylene (PE) specimens bent and immersed in surfactant solutions has been measured. In the temperature range 25 to 60° C, the values of the growth rate are almost independent of the amount of deformation varying in a narrow range but dependent on it below 25° C. They are changed over a few hundredfold by the changes of temperature and of surfactant solutions. The growth of ESC of PE is assumed to be a stress-assisted thermal activation process. In the temperature range 25 to 60° C, the values of activation enthalpy obtained depend on the surfactants used, but are almost independent of their concentrations. The growth rate was measured under hydrostatic pressure up to 2.25×10⁷ N m^–2 (220 atm). A few of the values of the dilation activation volume were evaluated. The nature of the mixture-like (surfactant and PE) region developed on PE surfaces at crack tips and the increase in the mobility of PE segments there seem to be essential to ESC of PE.     

Surface Friction of Poly(dimethyl Siloxane) Gel and Its Transition Phenomenon

The surface sliding friction of chemically cross-linked poly(dimethyl siloxane) (PDMS) swollen with linear PDMS as an oligomer is investigated. The friction force f increases with the normal pressure P in a power-law relation fP , where the exponent changes in a range of 0-1, depending on the degree of polymerization, N _poly, of the linear PDMS oligomer. When N _poly is in a range of 240-320, a dramatic decrease in friction force is observed at a critical normal pressure, P _c, leading to a very low friction coefficient on the order of 10^–3 at high-pressure ranges. The P _c increases with decreasing network size N _netof the gel and also with increasing polymer length related to N _poly. One possible explanation for this transition phenomenon in friction is that linear PDMS molecules are exuded from the gel network beyond a certain pressure and behave as polymer brushes, which are able to reduce the friction.