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Can prosthetic limbs made too quickly cause kidney damage?: a pilot study

  • Petrofsky, Jerrold S.;Browne, Mary;Jamshidi, Mahyar;Libo-on, Anthony;Lee, Haneul
    • Physical Therapy Rehabilitation Science
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    • v.3 no.2
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    • pp.119-124
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    • 2014
  • Objective: The use of chemicals for building prosthetic sockets present the possibility of being hazardous and unsafe due to off-gassing. The purpose of the present study was to investigate if freshly made materials used in prosthetic sockets causes off-gassing that would penetrate the skin and cause damage to the kidneys or blood. Design: Cross-sectional study. Methods: In this research, the off-gassing effects during the initial curing process of styrene monomer, vinyl ester resin, epoxy methacrylate resin, benzene-1, 3-dimethaneamine, trimethylhexanedlamine, and paratertiarybutylphenol were analyzed. Acid detection strips were placed inside newly fabricated mock-prosthetic sockets and left overnight in a closed environment to find out if acid was present in the invisible fumes. The plastic was worn by 9 subjects and urinalysis was made after 48 hours to test for any kidney or blood toxicity of the resins. Results: After wearing the plastic cuff for 48 hours, the ratio of protein to creatinine in the urine was raised to an abnormal level in five out of nine subjects. Four out of the nine subjects showed normal protein to creatinine ratios after wearing the device. The results showed that damage to the kidney occurred from wearing the resins after curing in half of the subjects. Conclusions: It is very important to conduct patient intakes which includes the assessment of renal function. Off-gassing in vented chambers may be needed to protect both prosthetists and patients.

Simulation for Injection Molding of Insulation Spacers for Gas-Insulated Switches Using Thermosetting Epoxy Resin (열경화성 에폭시를 이용한 가스 절연 개폐기용 절연 스페이서의 사출 성형 최적화 시뮬레이션)

  • Bae, Jaesung;Lee, Wonchang;Jee, Hongsub;Hong, Byungyou;Lee, Jaehyeong
    • Journal of the Korean Institute of Electrical and Electronic Material Engineers
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    • v.34 no.6
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    • pp.426-432
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    • 2021
  • Injection molding is used in many industrial fields such as home appliances, vehicle parts, and electronic device parts because various resins can be molded, leading to mass production of complex shapes. Generally, the empirical prediction method is used to set the initial processing conditions of injection molding. However, this approach requires a lot of cost and its presented solution is not accurate. In this paper, injection molding was simulated through the MoldflowTM in order to manufacture the spacer for gas insulated switch. Through the simulation, the flow of the resin with respect to the diameter of the inlet was analyzed. It was found that the process was possible at a higher resin temperature as the diameter of the inlet increased. In addition, through thermal analysis during injection of the resin, it was confirmed that a stagnation phenomenon occurred at the insert portion during injection molding, and the temperature of the resin was higher than that of the mold. As in this paper, if the spacer is manufactured by optimizing the injection hole and the temperature of the injection process based on simulation, it is expected that the spacer can be manufactured with high productivity.

Multi-stage Compression Molding Technology of Fast Curing CF/Epoxy Prepreg (속경화용 탄소섬유/에폭시 프리프레그의 다단 압축 성형기술)

  • Kwak, Seong-Hun;Mun, Ji-Hun;Hong, Sang-Hwui;Kwon, Soon-Deok;Kim, Byung-Ha;Kim, Tae-Yong
    • Composites Research
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    • v.34 no.5
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    • pp.269-276
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    • 2021
  • PCM (Prepreg Compression Molding) process is a high-speed molding technology that can manufacture high-quality CFRP (Carbon Fiber Reinforced Plastic) parts. Compared to the autoclave process, it generates less waste and can significantly reduce cycle time, so various studies are being conducted in the aerospace and automobile industries. In this study, in order to improve the quality of the PCM process, a molding method was developed to increase the compression pressure of the press step by step according to the curing behavior of the prepreg. It was confirmed that this multi-stage compression molding technology is a good means to produce high-quality CFRP products and shorten cycle times. And, the laminated prepreg at room temperature was immediately put into the mold and preheated and molded at the same time, so that it could be molded without a separate preheating process. In addition, as a result of applying the same process conditions optimized for flat plate molding to three-dimensional shapes, a product similar to a flat plate in appearance could be made without the process of establishing process conditions.

Natural Dyeing of Cationic-modified New Rayon (cocell) Fabric - Gallnut- (양이온화 뉴레이온(코셀) 직물의 천연염색에 관한 연구 - 오배자를 중심으로 -)

  • Kim, Ha-Yeon;Lee, Shin-Hee
    • Fashion & Textile Research Journal
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    • v.21 no.3
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    • pp.356-362
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    • 2019
  • This study investigated the substantivity of anionic dyes for cationic-modified new rayon (cocell) fabric treated with cationic agent (CA), 3-(Chloro-2-hydroxypropyl)-trimethylammonium chloride (CA). We also investigate the dyeability of cationic-modified new rayon fabric after dyeing with gallut. CA was converted in an aqueous solution of sodium hydroxide into epoxypropyl trimethylammonium chloride. Treating with this epoxy reagent modified the hydroxyl groups of the new rayon fabric into the trimethylammonium group through ether linkage. The introduction of new cationic sites into new rayon fabric by pretreating with cationic agent improved the substantivity of the Gallnut dye with the new rayon dyebath. The degree of the cationization of cationic-modified new rayon and cotton fabric was evaluated by nitrogen (N) content. This study extracted the colorant of gallnut with hot water at $90^{\circ}C$ and 120 min. Cationic-modified new rayon fabric dyed with extracted solution from gallnut according to concentration of gallnut, dyeing temperature, dyeing time and concentration of cationic agent. Dyeability (K/S) was obtained by CCM observation after dyeing with gallut solution. In addition, fastness to washing and light were also investigated. The degree of crystallinity of new rayon and cotton fabric were 42.15% and 54.94%, respectively. N (%) content of cationic-modified new rayon was higher than the cationic-modified cotton. Dyeability (K/S) increased significantly with the increasing concentration of CA and gallut.

Surface Modification of Nano Silica Prepared by Sol-gel Process and Subsequent Application towards Gas-barrier Films (졸-겔 공정으로 제조한 나노 실리카의 표면개질 및 가스차단성 필름으로의 응용)

  • Jang, Hyo Jun;Chang, Mi Jung;Nam, Kwang Hyun;Chung, Dae-won
    • Applied Chemistry for Engineering
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    • v.30 no.1
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    • pp.68-73
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    • 2019
  • We prepared hydrophobic silica particles by a sol-gel process from tetraethyl orthosilicate (TEOS), followed by coupling the reaction with octyltrimethoxysilane (OTMS) or hexadecyltrimethoxysilane (HDTMS) under various reaction conditions. We confirmed the extent of silica surface modification with organic compounds by SEM-EDS, thermogravimetry and elemental analysis. The silica particles obtained after the hydrolysis reaction of TEOS in ethanol at $50^{\circ}C$ for 24 h and the coupling reaction with OTMS for 2 h at the same temperature displayed the optimum performance in terms of the dispersity in an organic solvent and the surface roughness of films composited with epoxy resins. The oxygen permeability of the composite film with modified-silica was 12% lower than that of using the film without modified-silica.

Evaluation of Adhesion Performance of High-Fireproofing Alumino-silicate Inorganic Mortar (알루미노 실리케이트계 고내화성 모르타르의 부착성능 평가)

  • Cho, Hyeon-Seo;Lee, Gun-Cheol
    • Journal of the Korea Institute of Building Construction
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    • v.18 no.6
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    • pp.569-576
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    • 2018
  • In modern society, a huge number of the buildings have been constructed with RC structure. RC structures have many structural instabilities due to earthquake, typhoon, construction fault, design phase errors. Therefore, many reinforcement methods are being implemented to solve this problem. In the reinforcement method, the organic epoxy adhesive used in the FRP reinforcing method is abruptly damaged when exposed to high temperature, which is directly connected to the fall of the reinforcing material. Therefore, the present study was conducted to develop inorganic refractory mortar with a certain level of adhesion ability to reduce the heat transferred to FRP reinforcement when exposed to high temperatures. As a result of the test, it showed high adhesion strength at room temperature condition with the inclusion of EVA resin, and showed no performance deterioration up to about $300^{\circ}C$ even under heating conditions. Also, it was confirmed that the backside temperature was lower as the thickness increased, and converged to a constant temperature of about $780^{\circ}C$ after 2 hours of heating.

Small-Scale Wind Energy Harvester Using PZT Based Piezoelectric Ceramic Fiber Composite Array (PZT계 압전 세라믹 파이버 어레이 복합체를 이용한 미소 풍력 에너지 하베스터)

  • Lee, Min-Seon;Na, Yong-Hyeon;Park, Jin-Woo;Jeong, Young-Hun
    • Journal of the Korean Institute of Electrical and Electronic Material Engineers
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    • v.32 no.5
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    • pp.418-425
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    • 2019
  • A piezoelectric ceramic fiber composite (PCFC) was successfully fabricated using $0.69Pb(Zr_{0.47}Ti_{0.53})O_3-0.31[Pb(Zn_{0.4}Ni_{0.6})_{1/3}Nb_{2/3}]O_3$ (PZT-PZNN) for use in small-scale wind energy harvesters. The PCFC was formed using an epoxy matrix material and an array of Ag/Pd-coated PZT-PZNN piezo-ceramic fibers sandwiched by Cu interdigitated electrode patterned polyethylene terephthalate film. The energy harvesting performance was evaluated in a custom-made wind tunnel while varying the wind speed and resistive load with two types of flutter wind energy harvesters. One had a five-PCFC array vertically clamped with a supporting acrylic rod while the other used the same structure but with a five-PCFC cantilever array. Stainless steel (thickness: $50{\mu}m$) was attached onto one side of the PCFC to form the PZT-PZNN cantilever. The output power, in general, increased with an increase in the wind speed from 2 m/s to 10 m/s for both energy harvesters. The highest output power of $15.1{\mu}W$ at $14k{\Omega}$ was obtained at a wind speed of 10 m/s for the flutter wind energy harvester with the PZT-PZNN cantilever array. The results presented here reveal the strong potential for wind energy harvester applications to supply sustainable power to various IoT micro-devices.

Strength Characterisation of Composite Securement Device in the Vehicle by FE Analysis (유한요소해석을 통한 차량내 복합재 휠체어 고정구의 구조 강도 특성 평가)

  • Ham, Seok-Woo;Yang, Dong-Gyu;Son, Seung-Neo;Eo, Hyo-Kyoung;Kim, Gyeong-Seok;Cheon, Seong S.
    • Composites Research
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    • v.32 no.4
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    • pp.171-176
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    • 2019
  • In this paper, the strength of the composite securement device was characterised by FE analysis. Preliminary frontal crash analysis for the vehicle, equipped with the conventional steel securement device, was carried out according to the ISO 10542 for special transportation to obtain loading data, which were applied to securement device during crash. The securement device consists of block, guide and rail and the weight fraction of rail was the highest among them, therefore, it is desirable to reduce weight of rail by applying carbon/epoxy composite. Also, it was found that 27% of lightweight effect was obtained by hybrid rail that bottom part was replaced by a composite compared to the conventional rail, i.e., made of SAPH 440, without sacrificing the structural strength.

Results of Delamination Tests of FRP- and Steel-Plate-Reinforced Larix Composite Timber

  • LEE, In-Hwan;SONG, Yo-Jin;SONG, Da-Bin;HONG, Soon-Il
    • Journal of the Korean Wood Science and Technology
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    • v.47 no.5
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    • pp.655-662
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    • 2019
  • This study evaluated the multi-bonding performances of timbers as well as those of reinforcement and timber to obtain data for preparing guidelines regarding the use of timbers as large structural members. For the multi-bonding performances of timbers, four types of bonding surfaces were prepared according to the pith position. For the bonding performances of FRP (fiber-reinforced plastic)/steel plate and timber, a total of 11 types of specimens were produced for the selection of the appropriate adhesive. The bonding performances of the produced specimens were evaluated through a water soaking delamination test, a water boiling delamination test, and a block shear strength test. The test results showed that the bonding strength of the bonding surface according to the pith position was highest in the specimen for which the two sections with the pith at the center of the cross-section on timber and between the bonding surfaces (the tangential and radial sections were mixed) were bonded. Furthermore, the specimens for which the section (radial section) with the pith on the bonding surface of the timber was bonded showed a high delamination percentage. The results of the block shear strength test showed that the bonding section did not have a significant effect on the shear strength, and that the measured wood failure percentage was higher than the KS standard value. The PVAc adhesive showed the highest bonding strength between larix timber and GFRP (glass FRP). Furthermore, the epoxy and polyurethane adhesives showed good bonding strength for CFRP (carbon FRP) and structure steel, respectively.

Effects of NaCl Concentration and Solution Temperature on the Galvanic Corrosion Between CFRP and A516Gr.55 Carbon Steel

  • Hur, Seung Young;Kim, Ki Tae;Kim, Young Sik
    • Corrosion Science and Technology
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    • v.18 no.4
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    • pp.129-137
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    • 2019
  • CFRP (Carbon Fiber Reinforced Plastics) is composed of carbon fiber and plastic resin, and is approximately 20 - 50% lighter than metallic materials. CFRP has a low density, higher specific stiffness, specific strength, and high corrosion resistance. Because of these excellent properties, which meet various regulation conditions needed in the industrial fields, CFRP has been widely used in many industries including aviation and ship building. However, CFRP reveals water absorption in water immersion or high humidity environments, and water absorption occurs in an epoxy not carbon fiber, and can be facilitated by higher temperature. Since these properties can induce volume expansion inside CFRP and change the internal stress state and degrade the chemical bond between the fiber and the matrix, the mechanical properties including bond strength may be lowered. This study focused on the effects of NaCl concentration (0.01 - 1% NaCl) and solution temperature ($30-75^{\circ}C$) on the galvanic corrosion between CFRP and A516Gr.55 carbon steel. When NaCl concentration increases 10 times, corrosion rate of a specimen was not affected, but that of galvanic coupled carbon steel increased by 46.9% average. However, when solution temperature increases $10^{\circ}C$, average corrosion rate increased approximately 22%, regardless of single or galvanic coupled specimen.