• Archives of Pharmacal Research
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• v.24 no.4
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• pp.323-326
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• 2001

Previous studies have demonstrated that CW252053, a quinazoline antifolate, exhibits potent inhibitory activity against thymidylate synthase (TS) as well as cytotoxic activity against tumor cell lines in vitro. In this studys, we evaluated the in vivo antitumor efficacy of CW252053 in the mouse tumor model. Female B6D2F$_1$ mice were injected with LY3.7. 2C TK-/- (thymidine kinase deficient mouse Iymphoma) cells into the gastrocnemius muscle. Then, CW252053 was administered twice daily by intraperitoneal injection for 10 days, and tumor growth was monitored daily by leg diameter measurement. All animals in the vehicle, 5-FU, and low dose (30mgmg/kg CW252053 treated groups died between days 12 and 23 because of the tumor burden. In contrast, dosing with 60 mg/kg of CW252053 produced a cure rat against tumor growth of 37.5% and a survival rate of 50%. Even more significantly, a higher dose of CW252053 (120 mg/kg) elicited both a 100% cure rate and a 100% survival rate at the termination of the study, confirming that this compound has very potent in vivo antitumor activity against tumor growth. During the experimental period of this study no signs of toxicity were observed even at the high CW252053 dosage rate of 120 mg/kg.

• Composites Research
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• v.30 no.2
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• pp.116-125
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• 2017

The purpose of this study is to develop silicon carbide fiber showing an excellent mechanical properties under highly oxidative conditions at high temperature. Polycarbosilane(PCS) as a preceramic precursor was used for making the SiC fiber. PCS fiber was taken by melt spinning method followed by melting the PCS at $300{\sim}350^{\circ}C$ in N2 gas. The Curing of PCS fiber was carried out in air oxygen chamber, prior to high temperature pyrolysis. Degree of cure was calculated by characteristic peak's ratio of Si-H to $Si-CH_3$ in FT-IR spectra before and after curing of PCS fiber. The properties of SiC fiber was affected greatly by the degree of cure. The SiC fiber produced by controlling fiber tension during heat treatment showed good properties. The SiC fiber exposed to $1000^{\circ}C$ at air from 1 min. up to maximum 50 hrs showed around 60% reduction in tensile strength. We found that large amount of carbon content on the fiber surface after long-term exposure has resulted in lower tensile strength.

• Journal of Nutrition and Health
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• v.34 no.2
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• pp.222-229
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• 2001

This study describes the application of the stages of change construct to fat intake by examining the associations of the stages of change with nutritional status and beliefs on health behavior. Data were obtained from apparently healthy 596 adults(326 females and 270 males) residing in large cities. Stages of change assessed by an algorithms based on 6 items were designed each subject into one of the 5 stages: precontemplation(PC), contemplation(CO), preparation(PR), action(AC) and maintenance(MA). Beliefs on health behavior were assessed by self efficacy as well as 4 belief scales from the Locus of Illness Control(LIC) developed using factor analysis such as internal disease cure and prevention and external disease cure and prevention. Energy and fat intakes were measured by a 39 item short form food frequency questionnaire. Regarding the 5 stages of change, MA stage comprised the largest group(37.9%), followed by Ac(30.7%), PC(11.4%), CO(10.4%) and PR(9.6%). Subjects who were females, older or healthier were more likely to belong to either AC or MA. Stage assignment of individuals was corroborated by their nutritional variables. Those in PC had the most energy and fat and those in MA ate the least for females. BMI was higher in PR than any other stages for both males and females. Those in PC were distinctive in that they were more externally oriented in terms of health control showing higher scores on external disease prevention(for males) and external disease cure(for females), and lower score on internal disease cure. On the other hand, those in MA received the highest scores on internal disease prevention and self efficacy, which suggested that they were more internally oriented. Canonical discriminant function analysis indicated that the 5 stages were importantly discriminated by BMI, self efficacy, internal disease prevention and external disease prevention for males and by fat intake, self efficacy and external disease cure variables for females. The results of our study confirm differences in stages of change in fat intake in terms of nutritional status and beliefs on heath behavior and indicate the need for taking these phases of change into account in nutrition advice. (Korean J Nutrition 34(2) : 222-229, 2001)

• Journal of Korea Technical Association of The Pulp and Paper Industry
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• v.38 no.2 s.115
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• pp.9-15
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• 2006

Neutral sizing is required for linerboard to solve the troubles in strength and process caused by recycled raw materials. AKD sizing efficiency can be influenced by process condition like white water quality, fines retention and so on. Therefore, this study was aimed to evaluate sizing performance of general and fast cure type AKDs using process water obtained from linerboard mill. To evaluate effect of process water quality on AKD sizing, white water was diluted with tap water at the different dilution ratios and UKP slurry was sized using the prepared water. Also, effects of inorganic and organic ion material on sizing were examined. When white water was used for stock forming, UKP sheet showed very low sizing degree. Sizing degree of sheet was increased with increase of dilution ratio because water quality was improved. Especially anionic organic material had a greater influence on AKD sizing than inorganic material. When white water quality was deteriorated, fast cure type AKD showed superior sizing performance to general type AKD.

• Applied Chemistry for Engineering
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• v.16 no.6
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• pp.842-847
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• 2005

Virgin NBR and recycled NBR particles, which were pulverized from NBR scraps by high temperature shear-crushing technique, were blended with different mixing ratio. The effects of the recycled NBR content on the cure characteristics and physical properties of these blends were investigated and resistance properties of these blends to heat and various fluids were also studied. The study of cure characteristics showed that the viscosity increased but the scorch time decreased. The physical properties of rubber blends were improved with the addition of the recycled NBR for heat resistance and various fluid tests.

• Elastomers and Composites
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• v.54 no.2
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• pp.97-104
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• 2019

Emulsion styrene-butadiene rubber silica wet masterbatch (ESBR silica WMB) technology was studied to develop highly filled and highly dispersed silica compounds, involving the preparation of a composite by co-coagulating the modified silica and the rubber latex in a liquid phase. Previous studies have shown that when manufacturing ESBR silica WMB/Butadiene silica dry masterbatch (BR silica DMB) blend compounds, preparing BR silica dry masterbatch and mixing it with ESBR silica WMB gave excellent results. However, WMB still has the problem of lower crosslink density due to residual surfactants. Therefore, in this study, tetrabenzylthiuram disulfide (TBzTD) was added instead of diphenyl guanidine (DPG) in the ESBR silica WMB/BR silica DMB blend compounds and sulfur/CBS contents were increased to evaluate their cure characteristics, crosslink densities, mechanical properties, and dynamic viscoelastic properties. TBzTD was found to be more effective in increasing the crosslink density and to produce superior properties compared to DPG. In addition, with increasing sulfur/CBS contents, mechanical properties and rolling resistance were enhanced due to high crosslink density, but the abrasion resistance was not significantly changed because of the toughness.

• Proceedings of the Materials Research Society of Korea Conference
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• 1994.11a
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• pp.179-179
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• 1994

• The Journal of Advanced Prosthodontics
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• v.12 no.4
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• pp.189-196
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• 2020

PURPOSE. The aim of the present study was to investigate the effects of surface treatments on the bond strengths between polymer-containing restorative materials and two dual-cure resin cements. MATERIALS AND METHODS. In the present study, rectangular samples prepared from Lava Ultimate (LU) and Vita Enamic (VE) blocks were used. The specimen surfaces were treated using CoJet sandblasting, 50 ㎛ Al₂O₃ sandblasting, % 9 HF (hydrofluoric) acid, ER,Cr:YSGG laser treatment, and Z-Prime. Dual-cure resin cements (TheraCem and 3M RelyX U 200) were applied on each specimen's treated surface. A micro-tensile device was used to evaluate shear bond strength. Statistical analysis was performed using the SAS 9.4v3. RESULTS. While the bond strength using TheraCem with LU or VE was not statistically significant (P=.164), the bond strength using U200 with VE was statistically significant (P=.006). In the TheraCem applied VE groups, Z-Prime and HF acid were statistically different from CoJet, Laser, and Sandblast groups. In comparison of TheraCem used LU group, there was a statistically significant difference between HF acid and other surface treatments. CONCLUSION. The bonding performance between the restorative materials and cements were material type-dependent and surface treatment had a large effect on the bond strength. Within the limitations of the study, the use of both U200 and TheraCem may be suggested if Z-prime was applied to intaglio surfaces of VE. The cementation of LU using TheraCem is suitable after HF acid conditioning of the restoration surfaces.

• Composites Research
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• v.21 no.1
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• pp.16-21
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• 2008

The cure behavior of epoxy resin with a conventional amide-type hardener(HD) was investigated in the presence of castor oil(CO), cashew nut shell liquid(CNSL) and CNSL-formaldehyde resin(CFR) by using a dynamic differential scanning calorimetry(DSC). The activation energy of curing reaction was also calculated based on the non-isothermal DSC thermograms at various heating rates. An one-stage curing was noted in the case of epoxy resin filled with CO, while the epoxy resin with CNSL and CFR showed a two-stage curing process. A competitive cure reaction was noted for the epoxy resin/CNSL(or CFR)/HD blends. In the absence of HD, the CFR showed lower values of curing enthalpy than that of CNSL. The activation energy of epoxy resin curing increased with increasing the CNSL and CFR loading.

• Elastomers and Composites
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• v.46 no.2
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• pp.144-151
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• 2011

Intermittent CSR testing was used to investigate the degradation of a hydrogenated NBR(HNBR) O-rings, and also the prediction of its life-time. The cure system of HNBR O-ring was controlled as sulfur cure and peroxide cure system. An intermittent CSR jig was designed taking into consideration the O-ring's environment under use. The testing allowed observation of the effects of friction, heat loss, and stress relaxation by the Mullins effect. Degradation of O-rings by thermal aging was observed between 100 and $120^{\circ}C$. In the temperature range of $100-120^{\circ}C$, O-rings showed linear degradation behavior and satisfied the Arrhenius relationship. The activation energy of HNBR-S was about 70.6 kJ/mol. From Arrhenius plots, predicted life-times of HNBR-S O-ring were 31.1 years and 33.7 years for 50% and 40% failure conditions, respectively. In case of HNBR-P, the activation energy was about 72.1kJ/mol, and predicted life-times were 34.0 years and 36.5 years for 50% and 40% failure conditions, respectively. The peroxide cure system showed slower degradation rate and higher activation energy than the sulfur cure system.