Modification of poly(vinyl alcohol) membranes using sulfur-succinic acid and its application to pervaporation separation of water–alcohol mixtures

For the purposes of the water-selective membrane material development for pervaporation separation, we crosslinked poly(vinyl alcohol) (PVA) with sulfur-succinic acid (SSA), which contains —SO₃OH, by heat treatment and investigated the effect of the crosslinking density on the separation of water–alcohol mixtures by pervaporation technique. The crosslinking reaction between PVA and SSA was characterized through Fourier transform infrared spectroscopy and differential scanning calorimetry tests by varying the amount of the crosslinking agent, the reaction temperature, and the swelling measurements of each pure component. The separation performance of the water–methanol mixture is not good due to the existence of sulfonic acid, hydrophilic group, in the crosslinking agent. However, for the water–ethanol mixture, the flux of 0.291 kg/m²h and the separation factor of 171 were obtained at 70°C when PVA-crosslinked membrane containing 7 wt % SSA was used. The same membrane also showed flux of 0.206 kg/m²h and a separation factor of 1969 at the same operating temperature. © 1998 John Wiley & Sons, Inc. J Appl Polym Sci 68: 1717–1723, 1998     

Nickel supported on low-rank coal for steam reforming of ethyl acetate

Ethyl acetate is a volatile organic compound (VOC) that has emerged as a major environmental pollutant and also one of representative components of bio-oil. In this study, mostly metallic Ni particles (size: <10 nm) were finely dispersed on low-rank coal (LRC) by the ion-exchange process. Catalytic steam reforming of ethyl acetate (EA) was performed over Ni supported on Eco LRC (Ni/Eco) to reduce EA emissions and simultaneously produce H₂. EA reforming over 17.7 wt% Ni/Eco at 400 °C results in H₂ yield of 70%–80%; this is comparable to that achieved with reforming over commercial Ni/Al₂O₃. Advantageously, metallic Ni particles are dominant over Ni oxides on LRC, and therefore, the pre-reduction step routinely required for an alumina-supported catalyst can be skipped. Furthermore, deactivation by coking is slower with Ni/Eco than with Ni/Al₂O₃ during long-term operation, probably because of the smaller particle size and preferential adsorption on the coal support.     

Properties of Poly(lactide)-Coated Paperboard for the Use of 1-Way Paper Cup

ABSTRACT:  Poly(lactide)-coated paperboards were prepared by a solution coating method, and the effect of coating to improve properties of paperboard used for the manufacturing of 1-way paper cups was tested. Surface of PLA-coated paperboards was smooth and shiny like PE-coated paperboard, and the coating weight and thickness increased linearly with increasing PLA concentration of coating solution. Tensile strength (TS) and elongation at break (E) of the paperboard also increased after PLA coating. Water vapor barrier or water-resistant properties tested, such as water vapor permeability (WVP), water absorptiveness (WA), and contact angle (CA) of water drop, indicated that water resistance of the paperboard was improved through surface coating with PLA. The increase in water resistance of PLA-coated paperboards was mainly due to the hydrophobicity of PLA and the improvement of water barrier properties increased depending on the PLA concentration. In addition, PLA-coated paperboard showed strong heat sealing property when coated with more than 1 w/v% of PLA. Wet strength of PLA-coated (3, w/v%) paperboard was comparable to or greater than that of PE-coated paperboard. All the test results indicated that the PLA-coated paperboard can be exploited for the manufacturing of 1-way paper cups as an alternative to the PE-coated paperboard.     

Tumor targeting and imaging using cyclic RGD-PEGylated gold nanoparticle probes with directly conjugated iodine-125

Radioactive iodine-labeled, cyclic RGD-PEGylated gold nanoparticle (AuNP) probes are designed and synthesized for targeting cancer cells and imaging tumor sites. These iodine-125-labeled cRGD-PEG-AuNP probes are stable in various conditions including a range of pHs and high salt and temperature conditions. These probes can target selectively and be taken up by tumor cells via integrin αvβ3-receptor-mediated endocytosis with no cytotoxicity. The probes show a significant increase in the avidity of αvβ3 integrin compared to the corresponding free cRGD peptides. In-vivo SPECT/CT imaging results show that the iodine-125-labeled cRGD-PEG-AuNP probes can target the tumor site as soon as 10 min after injection, and also that cyclic RGD peptides are needed for efficient and long-term in-vivo monitoring. The results suggest that the probes circulate through the whole body, including renal filtration, and are excretable. These promising results show that radioactive-iodine-labeled gold nanoprobes have potential for highly specific and sensitive tumor imaging or for use as angiogenesis-targeted SPECT/CT imaging probes.     

Micro-hole fabrication by mechanical punching process

In the present investigation, micro-hole punching was studied, and the standard punching condition was scaled down to produce 25 μm size holes. For this, a micro punching press was designed and assembled, meeting requirements of process accuracy for 25 μm size holes. Tungsten carbide tooling sets were designed and fabricated by micro machining techniques. Three different size holes of 100, 50, and 25 μm in diameter were punched successfully on thin metallic foils such as brass and stainless steel of 100, 50, and 25 μm in thickness, respectively. Punched holes were examined in terms of surface qualities and results were analyzed in connection with shear fracture behavior. The results in this paper show that the mechanical punching process is promising to produce high quality holes even in the micro scale application.     

Adaptive time-delay command shaping filter for flexible manipulator control

We introduce a new formulation of the time-delay command shaping filter using a commuted shaping order approach, which leads to the development of a simple and effective adaptive command shaping technique for both single- and multi-mode cases. The authors derived the conditions that the time-delay command shaping filter should satisfy to suppress the residual vibration. From the conditions, they calculated the minimum number of command shaping filter terms required to completely cancel the residual vibrations as a function of the number of elastic modes to be canceled. Using this new formula they also prove that the time-delay value is not a function of the system parameters and can be chosen freely even for multiple elastic modes. Making use of this freedom in choosing the time delay, the authors propose a direct adaptation of the time-delay command shaper for both single and multi-mode systems. Finally, the simulation and experimental results of the adaptation are included to show the effectiveness of the direct adaptive command shaping approach.     

Pervaporation separation of pentane–alcohol mixtures using nylon 6–polyacrylic acid (PAA) ionically crosslinked membranes. II. Experimental data and theoretical interpretation

Novel ionically cross-linked blended membranes of nylon 6 and poly(acrylic acid) (PAA) were studied for the pervaporation separation of the binary organic mixture of pentane and methanol. Membranes of composition 25 wt % PAA were used after cross-linking. The experimental data obtained from the pervaporation runs were compared with the theoretical values of the individual permeabilities for binary mixtures predicted by the modified Fels and Huang model. This new model is based on an extension of the free volume theory and the introduction of Flory–Huggins thermodynamics for the calculations of the binary interaction parameters and the diffusion coefficients. The calculated values of permeabilities obtained from this modified model were reasonably close to the experimental values.     

Preparation and characterization of PVDF/silica hybrid membranes containing sulfonic acid groups

Organic–inorganic hybrid membranes of poly(vinylidene fluoride)‐cohexafluoropropylene (PVDF‐HFP) and silica composites containing sulfonic acid groups were prepared via in situ polymerization of tetraethoxysilane (TEOS) and sulfosuccinic acid (SSA) using the sol‐gel process. The membranes containing more sulfonic acid groups showed a higher vapor sorption and greater swelling behavior. The bound and free water content of the membrane is proportional to the SSA concentration. However, the hybrid membranes without SSA do not have free water. The ion conductivity of the membranes is proportional to the SSA concentration. Silica content in the hybrid membrane without SSA had great effect on their mechanical properties. Tensile modulus and yield stress increased and yield strain and elongation at break decreased with increased silica content. However, in the case of the hybrid membrane containing SSA modulus, yield stress decreased and yield strain and elongation at break increased with increased silica content due to the weak interactions between the hydrophobic polymer chain and the hydrophilic group of SSA. © 2004 Wiley Periodicals, Inc. J Appl Polym Sci 93: 209–218, 2004