Nondestructive determination of water and protein in surimi by near-infrared spectroscopy

Nondestructive near-infrared spectroscopy (NIRS) between 400 and 1100 nm regions was employed directly on surimi using a surface interactance fibre optic accessory, to investigate the potential of NIRS as a fast method to determine water and protein contents. The reason why NIRS is well suited when assessing the presence of water or protein is due to the specificity of O–H and N–H bindings. At 980 nm only one broad peak in the original spectra can be seen due to the absorption of water since it contained nearly 80% of surimi. Predictive equations were developed using partial least squares (PLS) regression where excellent predictions for protein and water are noticed. Regression coefficients are higher than 0.98, errors are small and RPD value for protein is well over 8 and that for water is very close to it which can be used for any analytical purpose.     

A new microcellular foam injection‐molding technology using non‐supercritical fluid physical blowing agents

A new foam injection‐molding technology was developed to produce microcellular foams without using supercritical fluid (SCF) pump units. In this technology, physical blowing agents (PBA), such as nitrogen (N₂) and carbon dioxide (CO₂), do not need to be brought to their SCF state. PBAs are delivered directly from their gas cylinders into the molten polymer through an injector valve, which can be controlled by a specially designed screw configuration and operation sequence. The excess PBA is discharged from the molten polymer through a venting vessel. Alternatively, additional PBA is introduced through the venting vessel when the polymer is not saturated with PBA. The amount of gas delivered into the molten polymer is controlled by the gas dosing time of the injector valve, the secondary reducing pressure of the gas cylinder and the outlet (back) pressure of the venting vessel. Microcellular polypropylene foams were prepared using the developed foam injection‐molding technology with 2–6 MPa CO₂ or 2–8 MPa N₂. High expansion foams with an average cell size of less than 25 μm were prepared. The developed technology dispels arguments for the necessity to pressurize N₂ or CO₂ to the SCF to prepare microcellular foams. POLYM. ENG. SCI., 57:105–113, 2017. © 2016 Society of Plastics Engineers     

Tangent Stiffness Equations for Laterally Distributed Loaded Members

Tangent stiffness equations for a beam-column, which is subjected to either uniformly or sinusoidally distributed lateral loads, are presented. The equations have been derived by differentiating the slope-deflection equations under axial forces for a member. Thus, the tangent stiffness equations take into consideration axial forces, bowing effect, and laterally distributed loads. As a numerical example, elastic buckling behavior of parallel chord latticed beams with laterally distributed loads is investigated to compare the results obtained from the present method with those from the conventional matrix method in which the distributed loads are considered as a series of concentrated loads at additional intermediate nodes of a member. Furthermore, buckling tests were carried out to confirm the equations derived as well as to clarify the buckling behavior of space frame structures. In conclusion, it can be said that the new equations can provide a good efficient way of estimating the equilibrium paths and buckling loads. They can also lead to a significant savings in core storage and computing time required for the analysis of space frame structures.     

Improved antifouling of anion-exchange membrane by polydopamine coating in electrodialysis process

The fouling, in particular the organic fouling of anion exchange membranes (AEMs), is a serious problem in electrodialysis (ED). In this paper, we attempted to improve the antifouling potential of AEM by surface modification with polydopamine (PDA). The antifouling potential was evaluated by the transition time, i.e. the time elapsed before fouling took place, using sodium dodecyl benzene sulfonate (SDBS) as a model foulant. The negative surface charge density, hydrophilicity and roughness of the membrane surface were increased with increasing dopamine concentration in the modification solution. The increases in negative surface charge density and hydrophilicity increased the antifouling potential, while the increase in surface roughness decreased the antifouling potential. Consequently, the optimum modification condition was the immersion into a 0.1 kg/m³ dopamine aqueous solution at pH 8.8 for 24 h. Under this condition, the antifouling potential of AEM was sufficiently improved. It was shown by theoretical analysis of the fouling data that the surface modification with PDA prevented the adsorption of SDBS micelles and improved the antifouling potential. Furthermore, it was experimentally confirmed that the modified membrane was highly stable.     

Surface pressure induced charge transfer between fullerene and tetrathiafulvalene derivative in Langmuir-Blodgett films

Structures and electronic states of a 1:1 mixture of bis-tetrathiafulvalene annulated macrocycle (1) and C60 in Langmuir films at the air-water interface and Langmuir-Blodgett (LB) films on solid substrates were examined. Compression of the Langmuir films induced for the first time a phase transition from a weakly interacting state without charge transfer (CT) to a neutral CT state. The scanning force microscope images of LB films transferred onto mica by a single withdrawal showed quite different spatial patterns depending on the CT states. When deposited at around 1 mNm(-1), a domain structure with 3 nm height was obtained, which corresponded to the state without CT interaction. Contrastingly, once the CT interaction was induced by applying surface pressure, a network structure was observed with a height of 6 nm. The CT band, whose transition moment was almost parallel to the substrate surface, was observed at 11.5 x 10(3) cm(-1) in the polarized UV-VIS-NIR spectra of the films deposited at 9 mNm(-1). The phase transition was irreversible, although the surface pressure-area isotherm showed a reversible behavior below 9 mNm(-1). The morphology and electronic state of the film was controllable merely by changing the surface pressure at the air-water interface.     

Characterization of methyl‐substituted polyamides used for reverse osmosis membranes by positron annihilation lifetime spectroscopy and MD simulation

Three kinds of polyamides were synthesized from three diamines and 1,3,5‐benzenetricarbonyl trichloride (TMC). The diamines used were m‐phenylene diamine, N‐methyl‐m‐phenylenediamine, and N,N′‐dimethyl‐m‐phenylenediamine. The average free volume sizes of the polyamides were measured by positron annihilation lifetime spectroscopy (PALS), and the free volume fractions were evaluated by molecular dynamics (MD) simulations. The methyl substitution on amino groups of diamines brought about an increase in interstitial space of molecular chains of the polyamides. In addition, reverse osmosis (RO) membranes were prepared by interfacial polymerization from the three diamines and TMC. The increase in the degree of methyl‐substitution of diamines led to increased chlorine resistance and decreased salt rejections of the polyamide RO membranes. Thus, the methyl‐substitution of diamines significantly influenced membrane performance. The vacancy sizes and fractional volumes in polyamides evaluated by PALS measurement and MD simulation were well correlated with salt rejection of polyamide RO membranes. © 2009 Wiley Periodicals, Inc. J Appl Polym Sci, 2009     

Fouling reduction of a poly(ether sulfone) hollow‐fiber membrane with a hydrophilic surfactant prepared via non‐solvent‐induced phase separation

Membrane fouling is still a crucial problem, especially in applications for water treatment. When fouling takes place on membrane surfaces, it causes flux decline, leading to an increase in production cost due to increased energy demand. The selection of the right membrane material and a special treatment of the membrane are required to avoid membrane fouling. This article reports the fouling resistance of a poly(ether sulfone) (PES) hollow‐fiber membrane modified with hydrophilic surfactant Tetronic 1307. Experiments on several methods of fouling were carried out to investigate the effect of the addition of nonionic surfactant Tetronic 1307 on membrane fouling. The effectiveness of a chemical agent [sodium hypochlorite (NaClO)] in the reduction of bovine serum albumin (BSA) deposition on the membrane surface was also evaluated. Permeation results showed that the fouling of a PES blend membrane with Tetronic 1307 was lower than that of the original PES membrane in the case of BSA filtration. A treatment with a 100 ppm NaClO solution was capable of removing BSA cake formation and effective at improving the relative permeability. The permeability of a PES blend membrane with Tetronic 1307 was almost 2 times higher than the original permeability when the membrane was treated with a 100 ppm NaClO solution because both BSA and Tetronic 1307 could be decomposed. © 2008 Wiley Periodicals, Inc. J Appl Polym Sci, 2009     

Theoretical calculation of uncertainty region based on the general size distribution in the preparation of standard reference particles for particle size measurement

In order to confirm the reliability of particle size measurement technique and to prepare standard reference particles for calibrating particle size measurement devices, experimental and theoretical studies have been conducted about the uncertainty region of particle size measurement for the general particle size distribution. A new theoretical equation to calculate fundamental uncertainty region in the case that the maximum and minimum particle sizes are known, is derived based on Tschebyscheff theory. The uncertainty regions calculated based on the proposed method are applied to poly-disperse particles and a picket-fence distribution composed of two kinds of nearly mono-disperse particles.For the poly-disperse particles, the uncertainty region increases with the increase in particle diameter. For the picket-fence distribution composed of two kinds of nearly mono-disperse particles, the uncertainty region increases around the intermediate particle diameters between the two kinds of particles.Numerical simulation of uncertainty region for the picket-fence distribution has also been carried out. The uncertainty region decreases with the increase in sample size or the decrease in geometric standard deviation.     

Acyl moieties modulate the effects of phospholipids on β-carotene uptake by Caco-2 cells

The intestinal absorption of carotenoids is though to be mediated by the carotenoid assembly in mixed micelles, followed by its transfer into the enterocytes and subsequent secretion to the lymph as chylomicron particles. In the present study we investigated the effects of phospholipids and lysophospholipids with diverse fatty acyl moieties on the uptake of β-carotene solubilized in mixed micelles by Caco-2 cells. Compared with phospholipid-free mixed micelles (NoPL), those containing long-chain PC inhibited β-carotene uptake (16∶0, 18∶1-PC≅16∶0, 18∶2-PC<14∶0, 14∶0-PC≅16∶0, 14∶0-PC <16∶0, 16∶0-PC<NoPL). However, mixed micelles containing medium-chain PC enhanced β-carotene uptake (NoPL<8∶0, 8∶0-PC<12∶0, 12∶0-PC<10∶0, 10∶0-PC), and short-chain PC did not affect the uptake. Among the lysophosphatidylcholine (LysoPC) class, a marked increase of β-carotene uptake by medium-to-long-chain LysoPC was observed (NoPL<12∶0-LysoPC<14∶0-LysoPC<18∶1-LysoPC<16∶0-LysoPC), although short-to-medium-chain LysoPC (6∶0-LysoPC to 10∶0-LysoPC) did not affect β-carotene uptake. The long-chain 16∶0,18∶1-PC increased the β-carotene efflux from cells and drastically changed the β-carotene UV-visible absorbance spectrum, compared with those of NoPL micelles. The acyl moieties of long-chain PC may interact with the carotenoid in the micelle interior, shifting the β-carotene partition toward the micellar phase. Medium-chain PC and long-chain LysoPC, which have nearly equivalent hydrophobicities, may enhance β-carotene uptake through their interaction with the cell membrane.     

Molecular dynamics simulation for investigating and assessing reaction conditions between carboxylated polyethersulfone and polyethyleneimine

Recently, nano-filtration membranes are made by the reaction between a reactive functional group on the surface of a tight ultrafiltration membrane and a charged branched polymer. This reaction makes the selective layer of the nanofiltration membrane, which plays an essential role in membrane performance. A molecular dynamics simulation with a reactive force field was used to investigate the reaction of carboxylated polyethersulfone as the functional group of the ultrafiltration membrane with polyethyleneimine. Experimental elucidation of the reaction between the PEI amine and carboxyl groups is challenging, and an MD simulation was thus employed. Furthermore, the simulation results show that the PEI and carboxylated polyethersulfone polymers react with each other in a temperature-dependent manner. While no reaction occurs at 298 K, carboxylated polyethersulfone and PEI begin to react when the temperature is increased from 298 to 323 K. Furthermore, a reversible reaction was observed with a subsequent increase in temperature to 353 K.