Demineralisation of whey by a combination of nanofiltration and anion‐exchange treatment: a preliminary study

Demineralisation is an important process for the utilisation of whey in the food industry. Sodium (Na⁺) and potassium (K⁺) ions pass through nanofiltration (NF) membranes in ion pairs with chloride (Cl^?) to maintain electroneutrality, but NF processing can only partially remove these ions from whey, because the total Na and K content of whey generally exceeds the Cl content. In this work, a preliminary study of a new demineralisation method was made. A reconstituted sweet whey powder solution was first treated by Cl‐form anion‐exchange resin to increase the molar ratio of Cl to Na and K from ~0.5 to ~1.0. Subsequently, NF removed >90% of Na and K from the anion‐exchange treated whey compared with <60% from the control whey. This new process could be useful for producing 70% demineralised whey with very low levels of the monovalent ions Na⁺, K⁺ and Cl^?.     

a-Si/mc-Si hybrid solar cell using silicon sheet substrate

A hybrid junction solar cell with amorphous silicon (a-Si) and multicrystalline silicon (mc-Si) was fabricated using a mc-Si sheet substrate, which is produced directly from molten silicon using a novel rotational solidification method. The efficiency of 11.6% was obtained for the hybrid junction cell, while 10.2% for the single junction cell made of a mc-Si sheet substrate, which confirmed that the hybrid structure is effective to improve the solar cell property made of a mc-Si substrate. With introducing light trapping structure, the efficiency was improved to be 12.0%. Moreover, the possibility of Jsc improvement was investigated using the advanced light trapping structure. Jsc of 15.6 mA/cm² was obtained and it was confirmed that the hybrid junction is a promising structure.     

Hyaluronic acid production by recombinant Streptococcus thermophilus

Generally recognized as safe, Streptococcus thermophilus was transformed using a plasmid expressing endogenous hyaluronic acid (HA) synthase genes. A single expression of hyaluronic acid synthase (hasA), uridine diphosphate-glucose dehydrogenase gene (hasB), or pyrophosphorylase gene (glmU) and double expression of hasA and hasB were attempted. A streptococcus-Escherichia coli shuttle vector, pBE31, was successfully transfected in S. thermophilus. The single expression of hasA or hasB allowed S. thermophilus to produce about 0.5-1.0 g/l HA. The strains coexpressing of hasA and hasB showed a markedly increased HA production (1.2g/l) which was six-fold increase compared with the wild-type strain. The maximum cell concentration and specific growth rate of each recombinant strain were lower than those of the wild-type strain; however, the specific production rate was more than 100-fold higher. Galactose concentration decreased in the coexpressing strain after depletion of lactose. The bacterial metabolism would be altered in order to achieve a higher production by changing the intracellular metabolism. The average molecular weight of HA (1.0 × 10(6) Da) was not affected by the expression of hasA and hasB. HA produced from recombinant strain could be an alternative material for medical, cosmetic and food utilization instead of HA from conventional pathogenic streptococci.     

Discrete-time model predictive contouring control for biaxial feed drive systems and experimental verification

In this paper we present a novel algorithm to model predictive contouring control for biaxial feed drive systems. model predictive control (MPC) refers to a class of model-based controllers that uses an explicit process model and tracking error dynamics to predict the future behavior of a plant, making it effective for machine tool feed drive systems that must achieve high-precision motion and are severely affected by friction, cutting force and changes in the workpiece mass. To improve contouring performance, we propose a new performance index in which error components orthogonal to the desired contour curve are given more importance than tracking errors with respect to each feed drive axis. Controller parameters are calculated in real time by solving an optimization problem. The parameters depend on the instantaneous slope of the reference trajectory and thus vary with time for curved reference trajectories, resulting in a time-varying controller. Weighting factors for the error components in orthogonal and tangential directions are used to adjust the error importance in each direction. In addition, to consider the required feed drive energy, the control inputs in both directions are included in the performance index. The effectiveness of the proposed control approach is demonstrated with an experimental biaxial feed drive system for circular and non-circular trajectories. The proposed contouring controller allows the feed drive to follow smooth curves and reduces contouring error.     

Magnetic and optical properties of MgAl2O4-(Ni0.5Zn0.5)Fe2O4 thin films prepared by pulsed laser deposition

Thin films composed of MgAl₂O₄ and (Ni_0.5Zn_0.5)Fe₂O₄ ([MA(100-x)-NZFx] films) were grown on fused SiO₂ substrates by pulsed laser deposition. X-ray diffraction measurements revealed that the films were polycrystalline, and that their lattice constant varied linearly with composition, indicating the formation of a solid solution. The film with x=60 was paramagnetic and those with x ≥ 70 were ferromagnetic. The films had a transparency above 75% in the visible range, but the transparency decreased with the x value. The optical band gaps were 2.95, 2.55, 2.30 and 1.89 eV for x=20, 40, 60, 80 and 100, respectively. The Faraday rotation angle increased with x in the visible range, and the film with x=70 exhibited a value of 2000 degrees cm^-1 at 570 nm, which is comparable to the rotation angle of Y₃Fe₅O₁₂. Owing to their high transparency, which extends into the visible range, the [MA(100-x)-NZFx] films can be used in novel magneto-optical devices.     

Design and Prototyping of Micro Centrifugal Compressor

In order to establish the design methodology of ultra micro centrifugal compressor, which is the most important component of ultra micro gas turbine unit, a 10 times of the final target size model was designed, prototyped and tested. The problems to be solved for downsizing were examined and 2-dimensional impeller was chosen as the first model due to its productivity. The conventional ID prediction method, CFD and the inverse design were attempted. The prototyped compressor was driven by using a turbocharger and the performance characteristics were measured.     

A macrocyclic ligand 5,14-dihydro-6,15-dimethyl-8,17-diphenyldibenzo-[b,i][1,4,8,11]tetraazacyclotetradecine and its nickel(II) complex: Syntheses, reaction mechanism and structures

The template reaction of o-phenylenediamine, 1-benzoylacetone and nickelous acetate tetrahydrate results in two structure isomers, 6,17-dimethyl-8,15-diphenyldibenzo[b,i][1,4,8,11]tetraazacyclotetradecinatonickel (II) (2) and 6,15-dimethyl-8,17-diphenyldibenzo[b,i][1,4,8,11]tetraazacyclotetradecinatonickel (II) (4). However, the latter has been neglected in the previous research because of its low yield in the template reaction. The mechanism of this template reaction is discussed. Though the steric hindrance between the phenyl ring and the benzo ring in 2 is greater than that in 4, the intermediate of the former shows better structural stability than that of the latter, leading to obviously higher final yield of 2 compared with that of 4. n-Butyl alcohol is used artfully to separate the crude product of the template reaction into almost pure 2 and a mixture of 2 and 4 in a mole ratio of 1:5. The free base of 2, 5,14-dihydro-6,17-dimethyl-8,15-diphenyldibenzo[b,i][1,4,8,11]tetraazacyclotetradecine (1), can be synthesized by demetalization of 2 with gaseous HCl. The same treatment to the mixture of 2 and 4 in a mole ratio of 1:5 leads to the free base of 4, 5,14-dihydro-6,15-dimethyl-8,17-diphenyldibenzo[b,i][1,4,8,11]tetraazacyclotetradecine (3). The neglected macrocyclic compounds 3 and 4 have been characterized unambiguously and their single-crystal structures have also been determined by X-ray diffraction analysis for the first time.     

Investigation of dielectric breakdown characteristics of double‐break vacuum interrupter and dielectric breakdown probability distribution in vacuum interrupter

To investigate the reliability of equipment of vacuum insulation, a study was carried out to clarify breakdown probability distributions in a vacuum gap. Further, a double‐break vacuum circuit breaker was investigated for breakdown probability distribution. The test results show that the breakdown probability distribution of the vacuum gap can be represented by a Weibull distribution using a location parameter, which shows the voltage that permits a zero breakdown probability. The location parameter obtained from Weibull plot depends on electrode area. The shape parameter obtained from Weibull plot of vacuum gap was 10 to 14, and was constant irrespective of the nonuniform field factor. The breakdown probability distribution after no‐load switching can be represented by Weibull distribution using a location parameter. The shape parameter after no‐load switching was 6 to 8.5, and was constant irrespective of the gap length. This indicates that the scatter of the breakdown voltage was increased by no‐load switching. If the vacuum circuit breaker uses a double break, the breakdown probability at low voltage becomes lower than the single‐break probability. Although the potential distribution is a concern in the double‐break vacuum circuit breaker, its insulation reliability is better than that of the single‐break vacuum interrupter even if the bias of the vacuum interrupter's sharing voltage is taken into account. © 2011 Wiley Periodicals, Inc. Electr Eng Jpn, 175(2): 13–20, 2011; Published online in Wiley Online Library ( wileyonlinelibrary.com ). DOI 10.1002/eej.21060