Reverse osmosis rejection by hydrous inorganic precipitate–cellulose composite membrane

Composit membranes were prepared by impregnating hydrous inorganic precipites (Fe and Cr oxides, nickel chromate or molybdate) into a cellulose acetate membrane which serves as a support. In these membranes, the hydrous iron oxide composite membrane showed high reverse osmosis properties. The permeability of the composite membrane did not decline with time, and the rejection of organic solute was not appreciably affected by impregnation. However, the rejection of electrolyte increased with impregnation. The measurements of membrane potential revealed that salt rejection is primarily attributable to the effect of membrane charge, i.e., to ion exclusion effect. In electrolyte solutions of 1:1 and 2:1, the membrane was anion selective; on the other hand, in electrolyte solution of 1:2, the membrane was cation selective. These results are characteristic of impregnated hydrous metal oxide.     

Transient response of cylindrical shells to localized heat sources

An exact analysis of the dynamic problem on the thermal displacements and stresses of cylindrical shells subjected to instantaneous heating is carried out. Equations of motion for cylindrical shells, including the thermal effects, are reduced and solved by using the Fourier and Laplace transformation methods, after obtaining the temperature distribution determined from the nonstationary equation of heat conduction for a shell under a prescribed temperature field. Numerical results are presented for the thermal displacement and stresses due to the time variation together with the quasistatic ones.     

Effect of outliers on forecasting temporally aggregated flow variables

Economic time series are of two types: stock and flows, and may be available at different levels of aggregation (for instance, monthly or quarterly). The economist, in many situations, is interested in forecasting the aggregated observations. The forecast function, in this case, can be based either on the disaggregated series or the aggregated series. The forecasts based on the disaggregated data are at least as efficient, in terms of mean squared forecast errors, as the forecasts based on temporally aggregated observations when the data generating process (DGP) is a known ARIMA process. However, the effect of outliers on both forecast functions is not known. In this paper, we consider the effect of additive and innovation outliers on forecasting aggregated values based on aggregated and disaggregated models when the DGP is a known ARIMA process and the presence of the outliers is ignored. Results when the model is not known and tests applied for the detection of outliers are derived through simulation.     

Modulation of the sensitive temperature range of fluorescent molecular thermometers based on thermoresponsive polymers

Fluorescent molecular thermometers based on polymers showing a temperature-induced phase transition and labeled with polarity-sensitive fluorescent benzofurazans are the most sensitive known. Here we show a simple and effective method for modulating the sensitive temperature ranges of fluorescent molecular thermometers based on such temperature-responsive polymers. 4-N-(2-acryloyloxyethyl)-N-methylamino-7-N,N-dimethylaminosulfonyl-2,1,3-benzoxadiazole was adopted as a polarity-sensitive fluorescent benzofurazan, and nine copolymers of two kinds of acrylamide derivative (N-n-propylacrylamide, N-isopropylacrylamide, and/or N-isopropylmethacrylamide) with a small amount of DBD-AE were obtained. The fluorescence intensities of these copolymers in aqueous solution sharply increased with increasing temperature over a small range (6-7 degrees C). In contrast, these fluorescent molecular thermometers differed from one another in the sensitive temperature range (between 20 and 49 degrees C). Moreover, the sensitive temperature ranges were well related to the acrylamide ratios in feed. In addition, the responses from these fluorescent molecular thermometers to the change in temperature were reversible and exactly repeatable during 10 cycles of heating and cooling (relative standard deviation of the fluorescence intensity, 0.44-1.0%).     

Membranes prepared from keratin–polyacrylonitrile graft copolymers

Graft copolymerization of acrylonitrile onto a soluble wool keratin derivative was studied with the reduced and carboxymethylated low-sulfur protein fraction from wool. Copolymerization was carried out under a variety of conditions with a redox system of (NH₄)₂S₂O₈–Na₂SO₃ in 60% (w/w) aqueous ZnCl₂ solution at 10°C. Monomer conversions higher than 90% were obtained by the stepwise addition of initiator. The graft products were successfully separated into grafted copolymer and homopolyacrylonitrile (PAN) by fractional precipitation or solvent extraction with DMF. Grafted PAN were isolated by acid hydrolysis of the keratin backbone. Characterization of grafted and homo-PAN was carried out by IR spectroscopy, amino acid endgroup analysis, and viscometry. On the basis of the results, effects of polymerization conditions on grafting parameters were discussed. Membranes were prepared from 60% aqueous ZnCl₂ solution by using ice-cold water as the regenerating medium. All the membranes formed from the graft products were transparent. Observation by scanning electron microscopy showed that the surface consisted of rather spherical keratin domains regularly distributed in the PAN matrix. Selective hydrolysis of the keratin domains allowed a new type of porous PAN membrane to be obtained, with the inner walls of the pores being charged with amino acid residues attached to PAN chains as the endgroup.     

High-strength small reinforcement for spliced optical fibre

A high-strength small reinforcement using a nylon and a steel wire has been developed. The size of the reinforcement is 1 mm in diameter and 35 mm in length. An average tensile strength of 5.4 kg has been achieved with negligible loss increase.     

Effect of the size of nuclei on crystallization behavior of Li2O · 2SiO2 glass

Crystallization peak temperature was measured for Li₂O · 2SiO₂ glass with various number densities of nuclei induced by long heat-treatment (405 h) at 460°C. Its crystallization process of Li₂O · 2SiO₂ glass was simulated numerically in order to examine the effect of the initial size of nuclei on crystallization behavior, and the relationship between crystallization peak temperature and the number density of nuclei in the glass was considered. It was found that the effect of nuclei size is not significant when the heat-treatment temperature is lower than 460°C. By considering the effect of nuclei size, number density of nuclus was evaluated by DTA method accurately.     

Imaging of the expansion of femtosecond-laser-produced silicon plasma atoms by off-resonant planar laser-induced fluorescence

Planar laser-induced fluorescence measurements were used to investigate the expansion dynamics of a femtosecond laser-induced plasma. Temporally and spatially resolved measurements were performed to monitor the atoms that were ablated from a silicon target. A dye laser (lambda = 288.16 nm) was used to excite fluorescence signals. The radiation of an off-resonant transition (Si 390.55 nm) was observed at different distances from the target surface. This allowed easy detection of the ablated Si atoms without problems caused by scattered laser light. Abel inversion was applied to obtain the radial distribution of the Si atoms. The atom distribution in the plasma shows some peculiarities, depending on the crater depth.     

Comparative study of depth and lateral distributions of electron excitation between scanning ion and scanning electron microscopes

In order to study the contrast difference between scanning ion microscopes (SIM) and scanning electron microscopes (SEM), the depth and lateral distributions of secondary electrons escaped from surfaces of 17 metals with atomic numbers, Z2, of 4-79 were calculated for bombardment with 30 keV Ga ions and for 10 keV electrons. For both projectiles, the excitation depth generally decreased with increasing Z2, while showing the same periodic change as the secondary-electron yield. However, an opposite trend in Z2 dependence between the Ga ion and electron bombardments was calculated with the lateral distribution of secondary electrons escaped from the surface. Except for low Z2 metals, the lateral distribution, which is much narrower for 30 keV Ga ions than for 10 keV electrons, indicates that the spatial resolution of the secondary-electron images is better for SIM than for SEM, if zero-sized probe beams are assumed. Furthermore, the present calculation reveals important effects of electron excitation by recoiled material atoms and reflected electrons on the lateral distribution, as well as the secondary-electron yield, for the Ga ion and electron bombardments, respectively.