Mechanical Properties and Friction Dynamics of Organogels Solidified with Rice Paraffin.

Raw materials suitable for a sustainable society have attracted interest in the cosmetics industry. We focused on rice bran as a sustainable material and evaluated the gelation behavior of paraffin extracted from rice bran (rice paraffin) against liquid paraffin, squalane, jojoba oil, and silicone oil. In addition, the frictional properties of the prepared organogel on an artificial skin surface were evaluated using a sinusoidal motion friction evaluation system. Rice paraffin solidified all oils even at the lowest wax concentration of 5 wt%. The hardness and kinetic friction coefficient µ k increased with an increase in the wax composition. The hardness and µ k of organogels solidified with rice paraffin were smaller than those of gels solidified with petroleum-derived paraffin. These differences are caused by the smaller carbon amount of rice paraffin. The friction parameters depended on the type of oil: the µ k of RLG composed of rice and liquid paraffin was greater than that of the other three oils (R, L, and G denote rice paraffin, liquid paraffin, and gel, respectively). These findings promote the development of lipsticks and cleansing gels consisting of sustainable development goal-responsive raw materials.

Controlling reaction selectivity for sugar fatty acid ester synthesis by using resins with different basicities.

A strongly basic ion-exchange resin catalyst was reported to exhibit a high catalytic activity in transesterification to produce a bio-based surfactant, sugar ester under mild condition. However, the side-reactions to decompose the reactant and the product were found to occur. This study was aimed to improve the selectivity of sugar ester synthesis by newly focusing on the basicity of the resin. A weakly basic resin (Diaion WA20) with a lower mass transfer resistance suppressed the decompositions while maintaining synthesis rate. Controlling molar ratio of the reactants in the intraparticle reaction field also increased the reaction selectivity, 72.1% and product yield, 57.5%. Both values were drastically increased compared to the reported values with the strongly basic resin (selectivity 50.9%, yield 14.3%). This is the first knowledge to show a high catalytic activity of weakly basic resin. These results suggest that a more efficient continuous production process would be possible.

Control of molecular weight distribution in synthesis of poly(2-hydroxyethyl methacrylate) using ultrasonic irradiation.

Poly(2-hydroxyethyl methacrylate) (PHEMA) was synthesized using ultrasonic irradiation without any chemical initiator. The effect of the ultrasonic power intensity on the time course of the conversion to polymer, the number average molecular weight, and the polydispersity were investigated in order to synthesize a polymer with a low molecular weight distribution (i.e., low polydispersity). The conversion to polymer increased with time. A higher ultrasonic power intensity resulted in a faster reaction rate. The number average molecular weight increased during the early stage of the reaction and then gradually decreased with time. A higher ultrasonic intensity resulted in a faster degradation rate of the polymer. The polydispersity decreased with time. This was because the degradation rate of a polymer with a higher molecular weight was faster than that of a polymer with a lower molecular weight. A polydispersity below 1.3 was obtained under ultrasonic irradiation. By changing the ultrasonic power intensity during the reaction, the number average molecular weight can be controlled while maintaining low polydispersity. When the ultrasonic irradiation was halted, the reactions stopped and the number average molecular weight and polydispersity did not change. On the basis of the experimental results, a kinetic model for synthesis of PHEMA under ultrasonic irradiation was constructed considering both polymerization and polymer degradation. The kinetic model was in good agreement with the experimental results for the time courses of the conversion to polymer, the number average molecular weight, and the polydispersity for various ultrasonic power intensities.

A kinetic model for flavonoid production in tea cell culture.

As one of the strategies for efficient production of a metabolite from cell cultures, a kinetic model is very useful tool to predict productivity under various culture conditions. In this study, we propose a kinetic model for flavonoid production in tea cell culture based on the cell life cycle and expression of PAL, the gene encoding phenylalanine ammonia-lyase (PAL)-the key enzyme in flavonoid biosynthesis. The flavonoid production rate was considered to be related to the amount of active PAL. Synthesis of PAL was modelled based on a general gene expression/translation mechanism, including the transcription of DNA encoding PAL into mRNA and the translation of PAL mRNA into the PAL protein. The transcription of DNA was assumed to be promoted at high light intensity and suppressed by a feedback regulatory mechanism at high flavonoid concentrations. In the model, mRNA and PAL were considered to self-decompose and to be lost by cell rupture. The model constants were estimated by fitting the experimental results obtained from tea cell cultures under various light intensities. The model accurately described the kinetic behaviors of dry and fresh cell concentrations, glucose concentration, cell viability, PAL specific activity, and flavonoid content under a wide range of light intensities. The model simulated flavonoid productivity per medium under various culture conditions. Therefore, this model will be useful to predict optimum culture conditions for maximum flavonoid productivity in cultured tea cells.

Pretreatment combining ultrasound and sodium percarbonate under mild conditions for efficient degradation of corn stover.

Ultrasound (US) can be used to disrupt microcrystalline cellulose to give nanofibers via ultrasonic cavitation. Sodium percarbonate (SP), consisting of sodium carbonate and hydrogen peroxide, generates highly reactive radicals, which cause oxidative delignification. Here, we describe a novel pretreatment technique using a combination of US and SP (US-SP) for the efficient saccharification of cellulose and hemicellulose in lignocellulosic corn stover. Although US-SP pretreatment was conducted under mild condition (i.e., at room temperature and atmospheric pressure), the pretreatment greatly increased lignin removal and cellulose digestibility. We also determined the optimum US-SP treatment conditions, such as ultrasonic power output, pretreatment time, pretreatment temperature, and SP concentration for an efficient cellulose saccharification. Moreover, xylose could be effectively recovered from US-SP pretreated biomass without the formation of microbial inhibitor furfural.

Novel simple process for tocopherols selective recovery from vegetable oils by adsorption and desorption with an anion-exchange resin.

A novel and simple low-temperature process was used to recover tocopherols from a deodorizer distillate, which is a by-product of edible oil refining. The process consists of three operations: the esterification of free fatty acids with a cation-exchange resin catalyst, the adsorption of tocopherols onto an anion-exchange resin, and tocopherol desorption from the resin. No degradation of tocopherols occurred during these processes. In the tocopherol-rich fraction, no impurities such as sterols or glycerides were present. These impurities are commonly found in the product of the conventional process. This novel process improves the overall recovery ratio and the mass fraction of the product (75.9% and 51.0wt%) compared with those in the conventional process (50% and 35wt%).

Simultaneous production of high quality biodiesel and glycerin from Jatropha oil using ion-exchange resins as catalysts and adsorbent.

The simultaneous production of high quality biodiesel and glycerin was realized by a bench-scale process using expanded-bed reactors packed with cation- and anion-exchange resins. The mixed-solution of crude Jatropha oil and methanol at a stoichiometric molar ratio was supplied to the process. The free fatty acid as well as triglyceride was completely converted to biodiesel. All by-products were adsorbed on the resin and the effluent from the process was free from them. The effluent fully met the international biodiesel standard specifications without any downstream purification processes except for removing methanol. The glycerin adsorbed on the resin was completely recovered as a transparent methanol solution during regeneration of the resin.

Rigorous kinetic model considering positional specificity of lipase for enzymatic stepwise hydrolysis of triolein in biphasic oil-water system.

A rigorous kinetic model describing the stepwise triglyceride hydrolysis at the oil-water interface, based on the Ping Pong Bi Bi mechanism using suspended lipase having positional specificity, was constructed. The preference of the enzyme to cleave to the ester bonds at the edge and the center of the glycerol backbone of the substrates (tri-, di- or monoglyceride) was incorporated in the model. This model was applied to the experimental results for triolein hydrolysis using suspended Porcine pancreatic lipase (an sn-1,3 specific lipase) and Candida rugosa lipase (a non-specific lipase) in a biphasic oil-water system under various operating conditions. In order to discuss the model's advantages, other models that do not consider the positional specificity of the lipase were also applied to our experimental results. The model considering the positional specificity of the lipase gave results which fit better with the experimental data and described the effect of the initial enzyme concentration, the interfacial area, and the initial concentrations of triolein on the entire process of the stepwise triolein hydrolysis. This model also gives a good representation of the rate for cleaving the respective ester bonds of each substrate by each type of lipase.

Biodiesel production using anionic ion-exchange resin as heterogeneous catalyst.

The transesterification reactions of triolein with ethanol using various ion-exchange resin catalysts were conducted to produce ethyl oleate as a biodiesel. The anion-exchange resins exhibited much higher catalytic activities than the cation-exchange resin. The anion-exchange resin with a lower cross-linking density and a smaller particle size gave a high reaction rate as well as a high conversion. By combining the three-step regeneration method, the resin could be repeatedly used for the batch transesterification without any loss in the catalytic activity. A continuous transesterification reaction was carried out using an expanded bed reactor packed with the most active resin. The reactor system permitted the continuous production of ethyl oleate with a high conversion.

Kinetics of ultrasonic disinfection of Escherichia coli in the presence of titanium dioxide particles.

The ultrasonic disinfection of Escherichia coli was carried out in the presence of anatase-type TiO2 particles, and the effectiveness of the combination of ultrasonic irradiation with TiO2 addition was verified. The rate constant was determined from the plot of the common logarithm of the survival cell ratio versus the ultrasonic irradiation time using first-order kinetics. In the absence of particles, the rate constant was proportional to the ultrasonic power. When ultrasonic disinfection was carried out in the presence of TiO2 particles, which have a radical generation ability, the rate of disinfection was remarkably faster than that in the absence of TiO2. In the presence of silica particles, which have no radical generation ability, the rate of disinfection was the same as that in the absence of TiO2. These results suggest that the radical generation ability of TiO2 appeared as a result of the ultrasonic irradiation. The effect of the amount of TiO2 on the rate of disinfection was also examined. The rate constant for disinfection in the presence of TiO2 was saturated to a certain value and was represented using the Langmuir-type equation. The proposed model well describes the effects of the ultrasonic power and the amount of TiO2 on the rate constant for disinfection.

Combination of extractive solvent addition and immobilization culture for continuous production of scopoletin by tobacco cells.

Extractive solvent addition was combined with immobilization cultures of Nicotiana tabacum cells to produce scopoletin. Using various solvents, the partition coefficients of scopoletin between the solvent and water phases and the solvent toxicity to the cell viability were investigated. The effect of the solvent addition on cell growth and scopoletin production was elucidated in the suspension cultures. Coconut oil, one of the natural vegetable oils, was selected as the most suitable extractive solvent. The cells were immobilized in the calcium alginate gel bead coated with a cell-free gel film and then the batch cultures with the addition of various volumes of the coconut oil were performed. The total scopoletin production increased with the solvent volume according to the amount of scopoletin transferred from the medium to the solvent. The maximum productivity obtained in the batch immobilization cultures was about 16 times larger than that in the suspension culture without solvent. A continuous production system, in which the fresh solvent was supplied to the culture system and the solvent containing scopoletin was recovered from it, was constructed. The integrated scopoletin production in the effluent oil attained 2.21 mg/gDCW for 30 days at 100 cm(3)/day without cell leakage.

Kinetics of ultrasonic degradation of phenol in the presence of TiO2 particles.

The degradation of phenol by ultrasonic irradiation in the presence of TiO2 was investigated in complete darkness. The effects of amount of TiO2 and the combination of TiO2 addition with gas (air or oxygen) supply on the degradation kinetics of phenol and the formation of the reaction products were examined. The degradation rate of phenol increased with the amount of TiO2. As the dissolved oxygen concentration increased by supplying oxygen, the degradation rate of phenol also increased. A kinetic model for the disappearance of phenol was proposed. The model takes into account the OH radical formation by direct water degradation, indirect degradation by oxygen atom and indirect degradation by TiO2 catalysis. The calculated results explained well the fact that a higher amount of TiO2 and dissolved oxygen concentration gave faster disappearance rate.

Improvement of catechin productivity in suspension cultures of tea callus cells.

In the suspension cultures of tea callus cells, C.sinensis cv. Yabukita, the effects of the culture conditions, such as culture period and light irradiation, on cell growth and catechin production were investigated. The production of flavonoids (catechins + proanthocyanidins) was promoted by inoculating the cells into the fresh medium at the culture period giving the maximum flavonoid content in the cells. The cultivation under light irradiation was repeated several times by inoculating the cells with the maximum flavonoid content. The flavonoid production was significantly increased without inhibiting the cell growth. We obtained the maximum flavonoid production, 1.5 g/dm(3) medium, and the maximum content, 150 mg/(g of dry cell weight (DCW)). The latter value was larger than that in the leaves of the tea plant.