Fracture Toughness Improvement of Poly(lactic acid) with Silicon Carbide Whiskers

Shan-Shan Yao,Qing-Qing Pang,Rui Song,Fan-Long Jin,박수진 한국고분자학회 2016 Macromolecular Research Vol.24 No.11

Luminescent characteristics of Sr2ZnSi2O7 : Eu3+ phosphor for ultraviolet light emitting diodes

Shan-shan Yao,Li-hong Xue,You-wei Yan,Yuan-yuan Li,Mi-fang Yan 한양대학교 세라믹연구소 2010 Journal of Ceramic Processing Research Vol.11 No.6

Red-emitting phosphors Sr2-xZnSi2O7 : Eux 3+ was prepared by a combustion-assisted synthesis method and an efficient red emission under near-ultraviolet (UV) was observed. The luminescence, crystallinity, and particle sizes were investigated using luminescence spectrometry, X-ray diffractometry, and field scanning electron microscopy. The emission spectrum shows that the most intense peak is located at 614 nm, which corresponds to the 5D0→ 7F2 transition of Eu3+. The phosphor has two main excitation peaks located at 394 and 465 nm, which match the emission of UV and blue light-emitting diodes, respectively.

Recent advances in carbon-fiber-reinforced thermoplastic composites: A review

Yao, Shan-Shan,Jin, Fan-Long,Rhee, Kyong Yop,Hui, David,Park, Soo-Jin Elsevier 2018 Composites Part B, Engineering Vol.142 No.-

<P><B>Abstract</B></P> <P>Carbon fibers (CFs) have high specific tensile strength, high modulus, and outstanding wear resistance, and are widely used for the reinforcement of advanced composite materials. CF-reinforced thermoplastic composites have received much attention because of their easy processability and recycling convenience compared with thermosetting composites. Surface treatment of CFs is generally employed to increase the surface functional groups and interfacial adhesion between the CFs and the surrounding polymer matrix. In this review, we explore recent advances in the surface treatment of CFs and preparation of CF/thermoplastic composites. The thermal, mechanical, and electrical properties of the composites are also discussed.</P>

Fracture toughness enhancement of epoxy resin reinforced with graphene nanoplatelets and carbon nanotubes

Shan-Shan Yao,Chun-Liu Ma,Fan-Long Jin,박수진 한국화학공학회 2020 Korean Journal of Chemical Engineering Vol.37 No.11

Graphene nanoplatelets (GNPs)/silane-coupling-agent-treated GNPs (KH- GNPs) and hydroxyl multi-walled carbon nanotubes (MWCNTs-OH) were added as reinforcing agents to an epoxy matrix, diglycidylether of bisphenol- A (DGEBA), to improve the fracture toughness of DGEBA. The influence of the MWCNT-OH fraction on the thermal and flexural properties, fracture toughness, and morphology of the DGEBA/GNP/MWCNT-OH and DGEBA/ KH-GNP/MWCNT-OH nanocomposites was investigated. The results indicate that the fracture toughness of the DGEBA/KH-GNP/MWCNT-OH nanocomposites increased from 1.09 to 1.46MPa·m1/2, which is 33.9% greater than that of pristine DGEBA. Analysis of the fracture surfaces of the nanocomposites showed a rough morphology with numerous tortuous and river-like structures. In addition, the MWCNTs-OH were slightly pulled out or broken in the epoxy matrix during the fracture toughness tests.

Concentration quenching of Eu^2+ in Ba_2Mg(BO_3)_2: Eu^2+ phosphor

Shan-shan Yao,Li-hong Xue,You-wei Yan 한국물리학회 2011 Current Applied Physics Vol.11 No.3

The red emitting phosphor Ba_2Mg(BO_3)_2: Eu^2+ is prepared by the combustion-assisted method. An efficient red emission under conditions ranging from ultraviolet to visible light is observed. The emission spectrum shows a single intensive band centered at 610 nm, which correspond to the 4f^65d^1 → 4f^7transition of Eu^2+. The critical quenching concentration of Eu^2+ in Ba_2Mg(BO_3)_2: Eu^2+ phosphor is about 0.05 mol. The corresponding concentration quenching mechanism is verified to be a dipole―dipole interaction. The value of the critical transfer distance is calculated as 17.32 Å, which is in good agreement with the value (18 Å) derived from the experimental data.

The Media Literacy of Residents in Southwestern China During the COVID-19 Epidemic

Shan He(Shan He),Lili Yao(Lili Yao),Xingyu Zhao(Xingyu Zhao),Weiwei Liu(Weiwei Liu) 아시아사회과학학회 2023 International Science Research Vol.3 No.2

Objective To measure residents’ abilities to acquire, analyze and evaluate information on media in southwestern China and to explore its predictive factors. Methods The convenience sampling method was used. A web-based questionnaire survey was conducted among 774 residents during the Spring Festival in 2020. Results Young, highly educated, unmarried, high-income, and urban residents preferred to seek and acquire information about COVID-19 epidemic through new media channels. Elderly residents tended to obtain information through television. Residents with low educational background and rural residents were more dependent on community information media. To analyze residents’ abilities in the judgement of 15 statements about COVID-19, residents with a master’s degree or above (OR = 2.755, [95% CI 1.160-6.542]) had better media literacy in identifying false health information released on social networking. Rural residents (OR = 0.609, [95% CI 0.433-0.855]) had lower media literacy. The total score decreased by 2.6% for every one-year increase of age. Conclusion Residents’ abilities to acquire, analyze and evaluate information were affected by their demographic characteristics in southwestern China. The authorities and local communities should develop different approaches of information dissemination, with the help of traditional and new media. It is important to improve the level of residents' media literacy, in order to achieve better effect in information dissemination and reception.

Correction: Enhanced thermal conductivity of carbon fibers/silanized graphene/epoxy matrix composites

Yao Shan-Shan,이슬이,Li Hai-Long,Jin Fan-Long,박수진 한국탄소학회 2024 Carbon Letters Vol.34 No.3

This study aimed to fabricate composites with high thermal conductivity using diglycidyl ether of bisphenol-A (DGEBA), incorporating carbon fiber cloth (CFC) and graphene as reinforcing agents. Notably, the dispersion of graphene within the DGEBA matrix was enhanced through surface modification via a silane coupling agent. The effects of CFC and graphene addition on the impact strength, thermal conductivity, and morphology of the composites were examined. The experimental results showed that the incorporation of 6 wt% CFC resulted in a substantial (16-fold) increase in impact strength. Furthermore, the introduction of 6 wt% CFCs along with 20 wt% graphene led to a remarkable enhancement in thermal conductivity to 5.7 W/(m K), which was approximately 22 and 4 times higher than the intrinsic thermal conductivities of pristine DGEBA and the CFC/DGEBA composite, respectively. The increased impact strength is ascribed to the incorporation of CFC and silane-modified graphene. Additionally, the gradual increase in thermal conductivity can be attributed to the enhanced interaction between the acidic silane-modified graphene and the basic epoxy–amine hardener within the system studied.

Thermal and mechanical properties of poly(latic acid) reinforced with silanized basalt scales

Shan-Shan Yao,Ming-Zhan Gao,Zhao-Yang Feng,Fan-Long Jin,박수진 한국화학공학회 2022 Korean Journal of Chemical Engineering Vol.39 No.7

Biodegradable poly(lactic acid) (PLA)-based composites were prepared using PLA and basalt scale (BS) viaa solution-blending method. BS surfaces were treated using a silane coupling agent, and their surface properties werecharacterized by high-resolution scanning electron microscopy, energy-dispersive X-ray spectrometry, and X-ray photoelectronspectrometry. Moreover, the influence of BS content on the thermal properties, flexural properties, impactstrength, and morphology of the PLA/silane-coupling-agent-treated BS (KH-BS) composites was analyzed. The thermalstability of the composites significantly increased due to the addition of KH-BS. Impact strength tests showed thatthe impact strength of the PLA/KH-BS composite with 4 wt% KH-BS was 3.14 kJ/m2, which is 51% higher than that ofpristine PLA (2.07 kJ/m2). The analysis of the fracture surfaces of the composites after the impact strength tests revealeda rough morphology with numerous river-like micro-cracks. The study results demonstrate that the addition of KH-BSsignificantly improves the thermal stability and impact strength of PLA/KH-BS composites.

Refolding and Purification of Recombinant Human Interferon-g Expressed as Inclusion Bodies in Escherichia coli Using Size Exclusion Chromatography

Shan-Jing Yao,Yi-Xin Guan,Hai-Xue Pan,Yong-Gui Gao,Man-Gi Cho 한국생물공학회 2005 Biotechnology and Bioprocess Engineering Vol.10 No.2

A size exclusion chromatography (SEC) process, in the presence of denaturant in the refolding buffer was developed to refold recombinant human interferon- (rhIFN-) at a high concentration. The rhIFN- was overexpressed in E. coli, resulting in the formation of inactive inclusion bodies (IBs). The IBs were first solubilized in 8 M urea as the denaturant, and then the refolding process performed by decreasing the urea concentration on the SEC column to suppress protein aggregation. The effects of the urea concentration, protein loading mode and column height during the refolding step were investigated. The combination of the buffer-exchange effect of SEC and a moderate urea concentration in the refolding buffer resulted in an efficient route for producing correctly folded rhIFN-, with protein recovery of 67.1% and specific activity up to 1.2 107 IU/mg.

Separation of Nattokinase from Bacillus subtilis Fermentation Broth by Expanded Bed Adsorption with Mixed-mode Adsorbent

Shan-Jing Yao,Miao-Hua Lu,Dong-Qiang Lin,Yuan-Chun Wu,Jun-Xian Yun,Le-He Mei 한국생물공학회 2005 Biotechnology and Bioprocess Engineering Vol.10 No.2

Mixed-mode hydrophobic/ionic matrices exhibit a salt-tolerant property for adsorbing target protein from high-ionic strength feedstock, which allows the application of undiluted feedstock via an expanded bed process. In the present work, a new type of mixed-mode adsorbent designed for expanded bed adsorption, Fastline PRO, was challenged for the capture of nattokinase from the high ionic fermentation broth of Bacillus subtilis. Two important factors, pH and ion concentration, were investigated with regard to the performance of nattokinase adsorption. Under initial fermentation broth conditions (pH 6.6 and conductivity of 10 mS/cm) the adsorption capacity of nattokinase with Fastline PRO was high, with a maximum capacity of 5,350 U/mL adsorbent. The elution behaviors were investigated using packed bed adsorption experiments, which demonstrated that the effective desorption of nattokinase could be achieved by effecting a pH of 9.5. The biomass pulse response experiments were carried out in order to evaluate the biomass/adsorbent interactions between Bacillus subtilis cells and Fastline PRO, and to demonstrate a stable expanded bed in the feedstock containing Bacillus subtilis cells. Finally, an EBA process, utilizing mixed-mode Fastline PRO adsorbent, was optimized to capture nattokinase directly from the fermentation broth. The purification factor reached 12.3, thereby demonstrating the advantages of the mixed-mode EBA in enzyme separation.