Separation of humic acid with nanofiltration polyamide composite membranes

Humic acid, a natural organic matter, was separated with a polyamide (PA) composite membrane with a molecular weight cutoff (MWCO) of 500 g/mol. The PA composite membrane was prepared by the interfacial polymerization of piperazine and trimesoyl chloride on a polysulfone support with an MWCO of about 30,000 g/mol. The separation conditions through the membrane were varied, and factors affecting the permeation performance of the membranes, such as the concentration, pH, and storage time of the humic acid solutions, were studied. The surface chemistry of the membrane changed dynamically as a function of the operating time during the permeation tests, and the size and ζ potential of the colloid of humic acid solutions under different conditions were characterized with a ζ potentiometer. © 2002 Wiley Periodicals, Inc. J Appl Polym Sci 86: 2847–2853, 2002     

Raney Ni catalysts derived from different alloy precursors Part II. CO and CO2 methanation activity

Catalytic activity, in conjunction with reaction mechanism, was studied in the methanation of CO and CO₂ on three Raney Ni catalysts derived from different Ni-Al alloys using different leaching conditions. Main products were CH₄ and CO₂ in CO methanation, and CH₄ and CO in CO₂ methanation. Any other hydrocarbon products were not observed. Over all catalysts, CO methanation showed lower selectivity to methane and higher activation energy than CO₂ methanation. The catalyst derived from alloy having higher Ni content using more severe leaching conditions, namely higher reaction temperature and longer extraction time, showed higher specific activity and higher selectivity to methane both in CO and CO₂ methanation. In CO and CO₂ methanation on Raney Ni catalyst, catalytic activity was seen to have close relation with the activity to dissociate CO This paper was presented at the 2004 Korea/Japan/Taiwan Chemical Engineering Conference held at Busan, Korea between November 3 and 4,2004.     

Carbon nanotubes based on anodic aluminum oxide nano-template

The effect of reaction gas and catalyst on the growth of carbon nanotubes (CNTs) in the anodic aluminum oxide (AAO) nano-template was investigated. A mechanism of CNT growth was proposed, which involves the competitive catalytic carbon deposition between on the Co catalyst particles electrodeposited at the bottom of the pores and on the AAO template itself. Presence of H₂ in the reacting gas mixture significantly affected the morphology and the wall structure of synthesized CNTs: CNTs of high crystallinity grew out of pores with H₂ while no CNTs overgrew in the absence of H₂. CNT synthesis by CO disproportionation showed a lower growth rate and a higher degree of ordering than those grown by C₂H₂ pyrolysis. The unified mechanism of CNT growth on AAO template is also proposed.     

Electrical/pH responsive properties of poly(2‐acrylamido‐2‐methylpropane sulfonic acid)/hyaluronic acid hydrogels

Poly(2‐acrylamido‐2‐methylpropane sulfonic acid) (PAMPS)/hyaluronic acid (HA) interpenetrating polymer network (IPN) hydrogels have been prepared by using the sequential‐IPN method. The IPN hydrogels exhibited swelling behavior in solutions at various pHs, in NaCl solutions, and under electrical DC stimulation. The IPN hydrogels were highly swollen in water, but lost much of their water capacity when transferred to solutions having a high ionic strength. The IPN hydrogels showed a significant responsive deswelling in an applied electric field. This behavior indicates the potential application of IPN hydrogels as biomaterials. © 2004 Wiley Periodicals, Inc. J Appl Polym Sci 92: 1731–1736, 2004     

少量乙醇对L沸石合成的影响

以白炭黑和偏铝酸钾为原料,添加少量乙醇合成L沸石.产物用XRD和SEM进行表征.系统研究了晶化时间、晶化温度、合成原料配比等参数对产物纯度和结晶度的影响.发现在合成体系中添加少量乙醇有利于合成纯度高、粒径较大、结晶度较高的L沸石.优化的晶化温度是130～150℃,更高的温度容易生成杂晶.延长晶化时间、提高硅铝比有利于提高产品的结晶度,但提高合成的碱度则使产品结晶度降低.     

Development of small robot using piezoelectric benders

Abstract

In this paper, a piezoelectric small robot was proposed and experimented. The piezoelectric bender of the actuator was composed of trapezoid ceramics which were attached on both surfaces of the elastic body. And an X-shaped structure was composed of four piezoelectric ceramic benders. When AC voltages which have different duty ratio were applied to the four benders, the motion of straight line according to a stick slip of the bender tips was obtained. A FEA simulation was used to analyze the motion of straight line. The output characteristics of the prototype actuator which was fabricated based on the analysis data were measured.     

Design of an ambulatory piezoelectric actuator which has T-shape stator

Abstract

T-shaped ambulatory piezoelectric actuator which can be used for various purposes such as lifesaving and environmental monitoring was proposed. The actuator consists of eight piezoelectric benders, t-shaped stator, and four legs, and it is very simple in structure and has the advantages of being easily manufactured and downsizing. It is also driven by four legs and can be moved forward and backward. The piezoelectric bender was composed of a carbon body and a ceramic plate. Vibration motions of the piezoelectric benders in x and z axes were transfer to the legs and the elliptical displacements at the ends of the legs were obtained by combination of the phase difference of 90 degrees. Characteristics of the actuators were simulated by finite element analysis, and the optimized prototype actuator was fabricated and experimented.     

Crack-tip constraints of through-wall cracked pipes and its similarity to curved wide plates

In the present study, the effects of pipe geometries, material properties and loading conditions on crack-tip constraints of pipes with circumferential Through-wall crack (TWC) were investigated via systematic 3-dimensional (3-D) Finite element (FE) analyses. The crack-tip constraints were quantified by Q-stress, and to characterize the elastic-plastic strain hardening material behavior, Ramberg-Osgood (R-O) material was employed. Based on the FE results, it was observed that crack-tip constraints of pipes with TWC were dependent on crack length and thickness of pipe, however, the effects of each variables decreased as either thickness of pipe becomes thinner or crack length becomes longer. Moreover, the effects loading modes on Q-stresses for thin-walled pipes with TWC are negligible. Finally, the present Q-stresses of pipes were compared with those of Curved wide plate (CWP) in tension to address the similarity of crack-tip constraints between pipe and CWP, which could be used to produce the CWP to measure the fracture toughness of pipes accurately.     

Detection of Foot‐and‐Mouth Disease Virus Using a Polydiacetylene Immunosensor on Solid‐Liquid Phase

The rapid detection of foot‐and‐mouth disease virus (FMDV) is vital for the prevention of foot‐and‐mouth disease outbreaks. In this study, a polyvinylidene difluoride (PVDF)‐supported polydiacetylene (PDA) immunosensor is developed to detect FMDV, in which a polyclonal antibody against the FMDV VP1 antigen is conjugated as a specific virus‐binding module without a linker. First, a liposome‐based immunosensor is generated for the FMDV VP1 protein in the form of photopolymerized PDA colloids. Then, the VP1‐specific PDA immunosensors are modified onto PVDF strip to enable the rapid and portable detection of FMDV. Detailed analyses are performed using ultraviolet‐visible spectroscopy, dynamic light scattering, transmission electron microscopy, and scanning electron microscopy. A blue‐to‐red color transition is observed in the presence of FMDV particles, indicating the potential applications of FMDV‐specific PDA immunosensors for use in solid‐phase detection as well as via liquid‐phase liposome platforms. Thus, this work provides a rapid and simple detection for FMDV.