Chlorine-resistant membrane for reverse osmosis. II. Preparation of chlorine-resistant polyamide composite membranes

Polyethylenetrimesamide (PET), poly(trimesoyl piperazine) (PTP), and poly(m-phenylenetrimesamide) (PMT) were fabricated into thin film composite to evaluate the membrane performance and resistance to oxidative chlorine. The salt rejection of these membrane increased in the following order: PTP<PET<PMT. The degree of performance deterioration of the membrane after the exposure to aq hypochlorous acid was in the following order: PMT>PET>PTP. The reaction behavior of these polyamide membranes with hypochlorous acid could be properly predicted by that of corresponding polyamide powder. Thus, polyethylenetrimesamide has proved to be one of the potential chlorine-resistant reverse osmosis membrane possessing excellent rejection to monosaccharides, amino acids, phenolics, and other solutes having a molar volume larger than 80 cm³/mol.     

微波辐射法合成聚左旋乳酸及其性能表征

采用自制的辛酸亚锡(Sn(Oct)2)有机溶剂为催化剂,以微波辐射为热源,在低温减压条件下引发左旋丙交酯(LLA)开环聚合,快速高效地合成性能良好的高分子量左旋聚乳酸(PLLA).开展了PLLA的微波辐射合成工艺及相关基础研究.在催化剂用量为0.26%、辐射温度100℃、反应真空度为500 Pa和辐射时间70 min时得到产物黏均分子量高达17.2 ×104.并运用DSC、IR、1H-NMR、13C-NMR和偏光显微镜等分析手段对PLLA进行表征.结果显示产物纯净,性能良好.     

Adaptation to climate change and conservation of biodiversity using green infrastructure

In recent years, we have experienced mega‐flood disasters in Japan due to climate change. In the last century, we have been building disaster prevention infrastructure (artificial levees and dams, referred to as “grey infrastructure”) to protect human lives and assets from floods, but these hard protective measures will not function against mega‐floods. Moreover, in a drastically depopulating society such as that in Japan, farmland abandonment prevails, and it will be more difficult to maintain grey infrastructure with a limited tax income. In this study, we propose the introduction of green infrastructure (GI) as an adaptation strategy for climate change. If we can use abandoned farmlands as GI, they may function to reduce disaster risks and provide habitats for various organisms that are adapted to wetland environments. First, we present a conceptual framework for disaster prevention using a hybrid of GI and conventional grey infrastructure. In this combination, the fundamental GI, composed of forests and wetlands in the catchment (GI‐1) and additional multilevel GIs such as flood control basins that function when floodwater exceeds the planning level (GI‐2) are introduced. We evaluated the flood attenuation function (GI‐1) of the Kushiro Wetland using a hydrological model and developed a methodology for selecting suitable locations of GI‐2, considering flood risk, biodiversity and the distribution of abandoned farmlands, which represent social and economic costs. The results indicated that the Kushiro Wetland acts as a large natural reservoir that attenuates the hydrological peak discharge during floods and suitable locations for introducing GI‐2 are concentrated in floodplain areas developing in the downstream reaches of large rivers. Finally, we discussed the network structure of GI‐1 as a hub and GI‐2 as a dispersal site for conservation of the Red‐crowned Crane, one of the symbolic species of Japan.     

Effect of a skid on the accuracy of measuring surface roughness

The vertical movement of the skid caused by surface irregularities introduces some error into the measured value of surface roughness parameters. A theoretical and experimental investigation into the negative effect of the skid on measuring accuracy is reported.The effect of the skid for unidirectional surface roughness is greater than that for non-directional surface roughness. The effect increases with increase in the tip radius of the skid. The influence of the distance between the skid and the stylus on the effect of the skid is small and an electrical high pass filter reduces the effect.     

Impact of precursor solution concentration to form superparamagnetic MgFe2O4 nanospheres by ultrasonic spray pyrolysis technique for magnetic thermotherapy

The superparamagnetic magnesium ferrite (MgFe₂O₄) dense nanospheres are synthesized by ultrasonic spray pyrolysis (USP) method from different concentrations of the initial precursor solution. The effect of precursor solution concentration on the particle’s size, morphology, and superparamagnetic behavior has been investigated. XRD results confirm that studied precursor concentration (0.06, 0.12 and 0.24 M) exhibited single phase cubic structure. The mean crystallites size (called as primary particles) of 0.06, 0.12 and 0.24 M samples are 9.6, 11.5, 11.0 nm, respectively but the entire nanosphere’s diameter (called as secondary particles) increases from 206 to 340 nm with increasing precursor concentration. TEM analysis also reveals that nanospheres consist of densely aggregated crystallites of spherical shape and smooth surface. The value of polydispersity index (PDI) shows narrower size distribution for lower concentration. Magnetic properties indicate the superparamagnetic nature for all samples. Herein, the appropriate induction heat generation rate with better morphology was obtained for 0.06 M concentration. Ion release in the aqueous solution of the composition (about 95% for Mg; 99% for Fe) indicating better stability has been confirmed by ICP-OES test. In this approach, as-synthesized nanospheres are suitable for using as a heating agent in magnetic thermotherapy application.     

Synthesis of star polymer by means of the living polymerization of [(o-trifluoromethyl)phenyl]acetylene using a MoOCl4-based catalyst and the linking method

A star polymer was synthesized by addition of 1,4-diethynyl-2,5-dimethylbenzene as linking agent (30 °C, 24 h) after living polymerization of [(o-trifluoromethyl)phenyl]acetylene (o-CF₃PA) with MoOCl₄-n-Bu₄Sn-EtOH catalyst (in anisole, 30 °C, 20 min; [Mo]=10 mM, [P^∗]/[Mo]=40%, [o-CF₃PA]₀=200 mM). The M_n values of the living and star polymers were 8.1×10³ and 5.3×10⁴, respectively, according to gel permeation chromatography, while these values determined by multi-angle laser light scattering (MALLS) were 7.8×10³ and 2.5×10⁵. The M_w/M_n and arm number of the star polymer were 1.04 and 29, respectively, according to MALLS. The molecular weight and arm number of star polymer increased with increasing linking agent concentration and polymerization temperature.     

An experimental study on the evaporation of freely falling droplet under high temperature and high pressure gas stream

An experimental apparatuses and measuring system have been made to obtain characteristics connected with evaporation, ignition delay, combustion of a freely falling liquid fuel droplet in high temperature and high pressure gas stream. In this study some systematic experiments were performed to test the utility of the system. The newly devised apparatus was ensured reliability and utility from the tentative experimental results.     

Optimal energy efficiency routing strategy based on community in mobile social network

An optimal energy efficiency routing strategy based on community was proposed,which minimized the network energy consumption under the given delay constraint.Firstly the expected energy consumption and delay of message delivery in the connected network were obtained through Markov chain.Then the comprehensive cost function for delivering message from source node to destination node was designed,which was combined with energy consumption and delay.Thus,the optimization function to comprehensive cost of relay node delivering message was obtained,and further the reward function of relay node was gotten.Finally the optimal expected reward of optimal relay node was achieved using the optimal stopping theory,so as to realize the optimal energy efficiency routing strategy.In simulations,the average energy consumption,the average delay and the average delivery ratio of routing optimization strategy were compared with those of other routing strategies in related literatures.The results show that the strategy proposed has smaller average energy consumption,shorter average delay and higher average delivery ratio,gaining better energy consumption optimization effect.     

Combined γ-ray irradiation-activated sludge treatment of humic acid solution from landfill leachate

Humic acid, which is a typical microbially refractory organic substance, was extracted from a landfill leachate. The humic acid solution (COD = 367 mg 1⁻¹; TOC = 293 mg 1⁻¹; BOD = 27 mg 1⁻¹) was applied to a batch scale activated sludge treatment after the modification of its biodegradability by γ-ray irradiation. The BOD increased to 64 mg 1⁻¹ by irradiation of 15 kGy (1.5 Mrad), while the COD and TOC decreased to 231 and 230 mg 1⁻¹, respectively. When the irradiated sample was treated with an activated sludge, the BOD decreased rapidly in 2–3 h to about 15 mg 1⁻¹ which was a similar value as the unirradiated sample was treated. The elimination efficiency of TOC by the sludge treatment was approximately equal to that obtained by irradiation of 15 kGy. These facts suggest a utility of applying microbial processes after radiation treatment of microbially refractory wastewaters.     

Effect of probe arrangement on reproducibility of images by near-infrared topography evaluated by a virtual head phantom

The effect of the probe arrangement on the reproducibility of topographic images of the concentration changes in oxygenated hemoglobin and deoxygenated hemoglobin is evaluated by a virtual head phantom. A virtual head phantom consists of five types of tissue the 3D structure of which is based on a magnetic resonance imaging scan of an adult head. Localized and broadened brain activation is assumed in a virtual head phantom. The topographic images are obtained from the reflectance detected by the standard probe arrangement and the double-density probe arrangement. The uneven thickness of the superficial layer, which cannot be evaluated by the previous slab model, affects the distribution of measured activation in the topographic image, and this reduces the position reproducibility of near-infrared (NIR) topography with the standard probe arrangement. The overlapping measurements by the double-density probe arrangement can improve the reproducibility of the image obtained by NIR topography.