• Title/Summary/Keyword: PA6

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Cold Plasma Treatment Effects on the Physicochemical and Biodegradable Properties of a Corn Biomass-containing Polyester Film (옥수수 바이오매스를 함유한 폴리에스터 필름의 물리 화학적 특성과 생분해 특성에 대한 콜드 플라즈마 처리의 영향)

  • Song, Ah Young;Oh, Yoon Ah;Oh, Se Jun;Min, Sea Cheol
    • Korean Journal of Food Science and Technology
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    • v.47 no.2
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    • pp.224-232
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    • 2015
  • The effects of cold plasma (CP) treatments on the physicochemical and biodegradable properties of a corn biomass-containing polyester (CBPE) film were studied. The CBPE film was treated with CP generated by $N_2$, $O_2$, He, Ar, or dry air at 400-900 W and 667 Pa for 10-40 min. The glass transition temperature of the CBPE film ($-30.2--28.6^{\circ}C$) was not affected by the CP treatment, while the elastic modulus and water vapor permeability decreased (p<0.05). The ink printability was improved by the treatment and the improved printability was maintained during storage for 56 days at room temperature. Roughness of the film increased after treatments and the level of roughness appeared to increase during storage. Heat and microbial biodegradability of the CBPE film was improved by the air-CP treatment (p<0.05). These results have demonstrated the potential of applying CP treatments to improve the flexibility, printability, and biodegradability of CBPE films.

RGD-Conjugated Chitosan-Pluronic Hydrogels as a Cell Supported Scaffold for Articular Cartilage Regeneration

  • Park, Kyung-Min;Joung, Yoon-Ki;Park, Ki-Dong;Lee, Sang-Young;Lee, Myung-Chul
    • Macromolecular Research
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    • v.16 no.6
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    • pp.517-523
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    • 2008
  • A RGD (Arg-Gly-Asp) conjugated chitosan hydrogel was used as a cell-supporting scaffold for articular cartilage regeneration. Thermosensitive chitosan-Pluronic (CP) has potential biomedical applications on account of its biocompatibility and injectability. A RGD-conjugated CP (RGD-CP) copolymer was prepared by coupling the carboxyl group in the peptide with the residual amine group in the CP copolymer. The chemical structure of RGD-CP was characterized by $^1H$ NMR and FT IR. The concentration of conjugated RGD was quantified by amino acid analysis (AAA) and rheology of the RGD-CP hydrogel was investigated. The amount of bound RGD was $0.135{\mu}g$ per 1 mg of CP copolymer. The viscoelastic parameters of RGD-CP hydrogel showed thermo-sensitivity and suitable mechanical strength at body temperature for cell scaffolds (a> 100 kPa storage modulus). The viability of the bovine chondrocyte and the amount of synthesized glycosaminoglycans (GAGs) on the RGD-CP hydrogels were evaluated together with the alginate hydrogels as a control over a 14 day period. Both results showed that the RGD-CP hydrogel was superior to the alginate hydrogel. These results show that conjugating RGD to CP hydro gels improves cell viability and proliferation, including extra cellular matrix (ECM) expression. Therefore, RGD conjugated CP hydrogels are quite suitable for a chondrocyte culture and have potential applications to the tissue engineering of articular cartilage tissue.

Investigation of Characteristics of Passive Heat Removal System Based on the Assembled Heat Transfer Tube

  • Wu, Xiangcheng;Yan, Changqi;Meng, Zhaoming;Chen, Kailun;Song, Shaochuang;Yang, Zonghao;Yu, Jie
    • Nuclear Engineering and Technology
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    • v.48 no.6
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    • pp.1321-1329
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    • 2016
  • To get an insight into the operating characteristics of the passive residual heat removal system of molten salt reactors, a two-phase natural circulation test facility was constructed. The system consists of a boiling loop absorbing the heat from the drain tank, a condensing loop consuming the heat, and a steam drum. A steady-state experiment was carried out, in which the thimble temperature ranged from $450^{\circ}C$ to $700^{\circ}C$ and the system pressure was controlled at levels below 150 kPa. When reaching a steady state, the system was operated under saturated conditions. Some important parameters, including heat power, system resistance, and water level in the steam drum and water tank were investigated. The experimental results showed that the natural circulation system is feasible in removing the decay heat, even though some fluctuations may occur in the operation. The uneven temperature distribution in the water tank may be inevitable because convection occurs on the outside of the condensing tube besides boiling with decreasing the decay power. The instabilities in the natural circulation loop are sensitive to heat flux and system resistance rather than the water level in the steam drum and water tank. RELAP5 code shows reasonable results compared with experimental data.

Preparation and Properties of the Fast-Curing γ-Ray-Shielding Materials Based on Polyurethane

  • Ni, Minxuan;Tang, Xiaobin;Chai, Hao;Zhang, Yun;Chen, Tuo;Chen, Da
    • Nuclear Engineering and Technology
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    • v.48 no.6
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    • pp.1396-1403
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    • 2016
  • In this study, fast-curing shielding materials were prepared with a two-component polyurethane matrix and a filler material of PbO through a one-step, laboratory-scale method. With an increase in the filler content, viscosity increased. However, the two components showed a small difference. Curing time decreased as the filler content increased. The minimum tack-free time of 27 s was obtained at a filler content of 70 wt%. Tensile strength and compressive strength initially increased and then decreased as the filler content increased. Even when the filler content reached 60 wt%, mechanical properties were still greater than those of the matrix. Cohesional strength decreased as the filler content increased. However, cohesional strength was still greater than 100 kPa at a filler content of 60 wt%. The ${\gamma}$-ray-shielding properties increased with the increase in the filler content, and composite thickness could be increased to improve the shielding performance when the energy of ${\gamma}$-rays was high. When the filler content was 60 wt%, the composite showed excellent comprehensive properties.

Surgical Treatment of Double Outlet Left Ventricle (양대동맥 좌심실기시증의 수술요법)

  • No, Jun-Ryang;Kim, Eung-Jung
    • Journal of Chest Surgery
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    • v.18 no.4
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    • pp.635-642
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    • 1985
  • Double outlet left ventricle [DOLV] is a rare cardiac anomaly in which both great arteries arise entirely, or predominantly above the morphologically left ventricle. About 100 cases of DOLV have been reported in the literatures by 1984. We have experienced eight cases of DOLV at Seoul National University Hospital during the period from October 1981 to July 1905. Ages of the patients were ranged from 12 months to 24 years old, and chief complaints on admission were frequent URI and DOE in 5 cases and cyanosis in other 3 cases. In all eight patients, Cardiac catheterization and cineangiography were performed but pre-operative diagnoses were incorrect except one case [VSD in 2 cases, DORV in 2cases, c-TGA in 2 cases and TOF in one case] We have performed total corrective surgery in seven patients. In case I, patch closure of VSD aligning aorta and pulmonary artery with LV, ligation of proximal pulmonary artery and the use of external valved conduit from RV to PA have been employed. In other 6 cases, intraventricular repair using boomerang shaped Dacron patch with correction of associated anomalies were employed. In remaining one patient who had coexistent PDA and coarctation of aorta, we have performed coarctoplasty and PDA ligation initially and the patient is waiting for subsequent total corrective procedure. In seven patients whom we have performed total corrective surgery, there is one hospital mortality due to right heart failure and one complication of complete heart block necessitating permanent pacemaker implantation. All survivors are doing well in follow up period of 9 months to 4 years. To our knowledge, this is the first report of surgical experiences for DOLV in the Korean literature.

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A Development of an Insole Type Local Shear Measurement Transducer and Measurements of Local Plantar Shear Force During Gait (인솔형 국부 전단센서의 개발 및 보행 시 발바닥의 국부 전단력 측정)

  • Jeong Im Sook;Ahn Seung Chan;Yi Jin Bok;Kim Han Sung;Kim Young Ho
    • Journal of the Korean Society for Precision Engineering
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    • v.22 no.6 s.171
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    • pp.213-221
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    • 2005
  • An insole type local shear force measurement system was developed and local shear stresses in the foot were measured during level walking. The shear force transducer based on the magneto-resistive principle, was a rigid 3-layer circular disc. Sensor calibrations with a specially designed calibration device showed that it provided relatively linear sensor outputs. Shear transducers were mounted on the locations of four metatarsal heads and heel in the insole. Sensor outputs were amplified, decorded in the bluetooth transmission part and then transferred to PC. In order to evaluate the developed system, both shear and plantar pressure measurements, synchronized with the three-dimensional motion analysis system, were performed on twelve young healthy male subjects, walking at their comfortable speeds. The maximum peak pressure during gait was 5.00kPa/B.W at the heel. The time when large local shear stresses were acted correlated well with the time of fast COP movements. The anteroposterior shear was dominant near the COP trajectory, but the mediolateral shear was noted away from the COP trajectory. The vector sum of shear stresses revealed a strong correlation with COP movement velocity. The present study will be helpful to select the material and to design of foot orthoses and orthopedic shoes for diabetic neuropathy or Hansen disease.

Effects of Dynamic Exercise Program Using Thera-Band on Craniovertebral Angle in Adults with Forward Head Posture

  • Shin, Hyungsoo;Kim, Kihyun;Jung, Namjin
    • Journal of International Academy of Physical Therapy Research
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    • v.11 no.1
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    • pp.1960-1968
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    • 2020
  • Background: The alignment of the neck and shoulder is important in people with forward head posture. However, previous studies have mainly conducted fragmentary studies on the neck and shoulders, and studies on the combined movement of the neck and shoulders are incomplete. Objective: To investigate the effects of 6 week dynamic exercise program using Thera-band on craniovertebral angle (CVA) in adults with forward head posture. Design: Quasi-experimental study. Methods: The study was conducted on 24 adults with forward head posture and experimented with neck and shoulder exercises and divided them into groups of neck exercises, shoulder exercises, and neck and shoulder exercises to measure CVA values before and after the experiment. The neck exercise program included flexion and extension muscles of the neck and shoulder exercises included dynamic exercise of the upper extremities such as the trapezius muscles and serratus anterior muscle. The CVA results were measured using PA200. Results: Following the interventions, neck exercise group showed significant improvement in CVA (P<.05), but shoulder exercise group and combined exercise group did not show any significant results (P>.05). However, both groups showed some positive results. Significant differences were seen in the comparisons between the three groups (P<.05), and the results of the post-hoc test showed significant differences in neck exercise group and shoulder exercise, neck exercise and combine exercise group. Conclusion: This study suggested that the Thera-band neck exercise is beneficial for foward head posture patients and is expected to be used in clinical trials.

CFD Analysis on the Flow Characteristics of Diffuser/Nozzles for Micro-pumps (마이크로 펌프용 디퓨져/노즐의 유동 특성에 관한 CFD 해석)

  • Kim Donghwan;Han Dong-Seok;Jeong Siyoung;Hur Nahmkeon;Yoon Seok-Jin
    • Korean Journal of Air-Conditioning and Refrigeration Engineering
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    • v.17 no.6
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    • pp.544-551
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    • 2005
  • The flow characteristics have been numerically investigated for various shapes of the diffuser/nozzles which are used for a valveless micro-pump. The important parameters considered in this study are the throat width ($15\~120\mu$m), the taper angle ($3.15\~25.2^{\circ}$), and the diffuser length ( $600\~4,800\mu$m), and the size of the middle chamber ($1\~16mm^2$). To find the optimal values for these parameters, steady state calculations have been performed assuming the constant pressure difference between the inlet and exit of the flow For the taper angle and the throat width, it is found that there exists an optimum at which the net flow rate is the greatest. The optimal taper angle is in the range of $10\~20^{\circ}$ for all the pressure differences; and the throat width indicates an optimal value near $75\mu$m for the case of 35 kPa pressure difference. The net flow rate is also influenced by the size of the middle chamber. With decreasing chamber size, the net flow rate is reduced because of the interference between two streams flowing into the middle chamber. The unsteady pulsating flow characteristics for a micro-pump with a given diffuser/nozzle shape have been also investigated to show the validity of the steady state parametric study.

A Case of Moderate Paraquat Intoxication with Pulse Therapy in the Subacute Stage of Pulmonary Fibrosis (파라쿼트로 발생한 폐 섬유화증에서 pulse therapy로 호전된 환자 1례)

  • Hong, Ki-Hun;Jung, Jin-Hee;Eo, Eun-Kyung
    • Journal of The Korean Society of Clinical Toxicology
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    • v.6 no.2
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    • pp.130-133
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    • 2008
  • In South Korea, attempted suicide by paraquat (PQ) intoxication is fairly common, and is lethal by pulmonary fibrosis and hypoxemia. However, the treatment of PQ poisoning is primarily supportive management. To increase the survival rate associated with PQ intoxication, many treatments have been developed. Here, we treated a case of PQ intoxication with steroid pulse therapy. A 23-year-old man was admitted to the hospital because of PQ intoxication. He drank two mouthfuls of Gramoxon (24% commercial paraquat). His vital signs were stable, but he had a throat infection, and navy blue urine in the sodium dithionite test. Standard treatment, including gastric lavage with activated charcoal was performed, and emergent hemoperfusion with a charcoal filter was initiated 11 h after PQ ingestion. Pharmacotherapy was initiated 18 h after PQ ingestion with the administration of 5 mg dexamethasone. On day 10, chest PA showed pulmonary fibrosis. Therefore, we initiated steroid pulse therapy, with 1g methylprednisolone in 100 mL of D5W administered over 1 h repeated daily for 3 days, and 1 g cyclophosphamide in 100 mL of D5W administered over 1 h daily for 2 days. On day 15, dexamethasone therapy was initiated. On day 30, pulmonary fibrosis was improved. Thus, if pulmonary fibrosis becomes exacerbated after dexamethasone therapy during the subacute stage, pulse therapy with methylprednisolone and cyclophosphamide could be helpful.

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Inhibitors of AKT Signaling Pathway and their Application

  • WONG, Chin Piow
    • Proceedings of the Plant Resources Society of Korea Conference
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    • 2019.04a
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    • pp.33-33
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    • 2019
  • The AKT signaling pathway is a highly regulated cell signaling system that forms a network with other cell signaling pathways. Hence, the AKT signaling pathway mediates several important cellular functions that include cell survival, proliferation, cell migration, and et cetera. Irregularities that led overactive AKT signaling have been linked to many diseases such as cancer and metabolic-associated diseases. Hence, modulating the overactive AKT signaling pathway via inhibitor is a tantalizing prospect for treatment of cancer and metabolic-associated diseases. Two inhibitors of the AKT signaling pathway will be presented in this symposium: 1) Bisleuconothine A (BisA), a bisindole alkaloid that inhibit autophagy and 2) Ceramicine B (CerB), a limonoid that inhibit adipogenesis. The first topic is on a bisindole alkaloid, BisA and its mechanism in inducing autophagosome formation in lung cancer cell line, A549.(1) Since most autophagy inducing agents generally induce apoptosis, we found that BisA does not induce apoptosis even in high dose. BisA up-regulation of LC3 lipidation is achieved through mTOR inactivation. The phosphorylation of PRAS40, a mTOR repressor was suppressed by BisA. This observation suggested that BisA inactivates mTOR via suppression of PRAS40 phosphorylation. Interestingly, the phosphorylation of AKT, an upstream regulator of PRAS40 phosphorylation was also down-regulated by BisA. These findings suggested that Bis-A induces autophagosomes formation by interfering with the AKT-mTOR signaling pathway. The second topic is on CerB and its mechanism in inhibiting adipogenesis in preadipocytes cell line, MC3T3-G2/PA6.(2,3) CerB inhibits the phosphorylation of protein kinase B (AKT) at the Thr308 position but not the Ser473. Consequently, the phosphorylation of FOXO3 which is located downstream of AKT is also inhibited. Considering that FOXO3 is an important regulator of PPARγ which is a key factor in adipogenesis, CerB may inhibit adipogenesis via the AKT-FOXO3 signaling pathway. Taken together, both BisA and CerB highlighted the potential of AKT signaling pathway modulation as an approach to induce autophagy and inhibit the formation of fat cells, respectively.

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