Highly crystalline bilayer electron transport layer for efficient conjugated polymer solar cells

Cheng Xu,Matthew Wright,Naveen Kumar Elumalai,Arafat Mahmud,Dian Wang,Mushfika Baishakhi Upama,Faiazul Haque,Ashraf Uddin 한국물리학회 2018 Current Applied Physics Vol.18 No.5

Solution processed solar cells are a promising renewable energy technology due to the low fabrication costs. The most commonly used electron transport layer for solution processed organic solar cells is ZnO. However, sol-gel derived ZnO is amorphous, which limits interfacial charge transport. In this study, we demonstrate a ZnO bilayer, composed of a nanoparticle ZnO and sol-gel derived ZnO layer, as the electron transport layer in polymer solar cells incorporating the novel polymer poly [(5,6-difluoro-2,1,3-benzothiadiazol-4,7-diyl)-alt-(3,3‴-di (2-octyldodecyl)-2,2′; 5′,2″; 5″,2‴-quaterthiophen-5,5‴-diyl)] (PffBT4T-2OD). Compared with the single layer sol-gel ZnO, the bilayer displayed enhanced crystallinity. Consequently, the interfacial transport from the active layer was improved, as evidenced by dark J-V and PL spectroscopy measurements. Solar cells incorporating this bilayer ZnO layer achieved PCE values exceeding 10%, a relative improvement of 25% compared to the sol-gel ZnO devices.

A MIXED CORE FOR SUPERCRITICAL WATER-COOLED REACTORS

Cheng, Xu,Liu, Xiao-Jing,Yang, Yan-Hua Korean Nuclear Society 2008 Nuclear Engineering and Technology Vol.40 No.2

In this paper, a new reactor core design is proposed on the basis of a mixed core concept consisting of a thermal zone and a fast zone. The geometric structure of the fuel assembly of the thermal zone is similar to that of a conventional thermal supercritical water-cooled reactor(SCWR) core with two fuel pin rows between the moderator channels. In spite of the counter-current flow mode, the co-current flow mode is used to simplify the design of the reactor core and the fuel assembly. The water temperature at the exit of the thermal zone is much lower than the water temperature at the outlet of the pressure vessel. This lower temperature reduces the maximum cladding temperature of the thermal zone. Furthermore, due to the high velocity of the fast zone, a wider lattice can be used in the fuel assembly and the nonuniformity of the local heat transfer can be minimized. This mixed core, which combines the merits of some existing thermal SCWR cores and fast SCWR cores, is proposed for further detailed analysis.

THE PRESSURE OF THE SHEAR LAYER BOUNDING REVERSE FLOW REGION ON EXTERNAL EXCITATION

Cheng Xu,Ming de Zhou,Shi Ying Zhang 대한기계학회 1992 International Conference on Fluid Machinery Vol.1 No.1

A Secure and Efficient Message Authentication Scheme for Vehicular Networks based on LTE-V

( Cheng Xu ),( Xiaohong Huang ),( Maode Ma ),( Hong Bao ) 한국인터넷정보학회 2018 KSII Transactions on Internet and Information Syst Vol.12 No.6

Vehicular networks play an important role in current intelligent transportation networks and have gained much attention from academia and industry. Vehicular networks can be enhanced by Long Term Evolution-Vehicle (LTE-V) technology, which has been defined in a series of standards by the 3rd Generation Partnership Project (3GPP). LTE-V technology is a systematic and integrated V2X solution. To guarantee secure LTE-V communication, security and privacy issues must be addressed before the network is deployed. The present study aims to improve the security functionality of vehicular LTE networks by proposing an efficient and secure ID-based message authentication scheme for vehicular networks, named the ESMAV. We demonstrate its ability to simultaneously support both mutual authentication and privacy protection. In addition, the ESMAV exhibit better performance in terms of overhead computation, communication cost, and security functions, which includes privacy preservation and non-frameability.

Investigation on turbulent heat transfer to lead–bismuth eutectic flows in circular tubes for nuclear applications

Cheng, Xu,Tak, Nam-il Elsevier 2006 Nuclear engineering and design Vol.236 No.4

<P><B>Abstract</B></P><P>Since many years, the Forschungszentrum Karlsruhe has been working on the research and development of an accelerator driven sub-critical system (ADS) cooled by lead–bismuth eutectic (LBE). Although various numerical tools for thermal hydraulics have been established at the Forschungszentrum Karlsruhe, reliably validated physical models related to turbulent heat transfer in LBE flows are still missing. Especially, physical models on heat transfer and turbulent Prandtl number have to be re-evaluated in LBE conditions to improve the reliability of numerical tools. In the present paper, review and assessment of the existing physical models are made. Computational fluid dynamics (CFD) analysis is carried out for circular tube geometries. Based on the assessment of the existing models and the CFD results achieved, recommendations are made on correlations of heat transfer and turbulent Prandtl number for numerical applications to LBE flows.</P>

Neutropenia during the First Cycle of Induction Chemotherapy Is Prognostic for Poor Survival in Locoregionally Advanced Nasopharyngeal Carcinoma: A Real-World Study in an Endemic Area

Cheng Xu,Shi-Ping Yang,Yuan Zhang,Ling-Long Tang,Guan-Qun Zhou,Xu Liu,Yan-Ping Mao,Rui Guo,Wen-Fei Li,Lei Chen,Ai-Hua Lin,Ying Sun,Jun Ma 대한암학회 2018 Cancer Research and Treatment Vol.50 No.3

Purpose The purpose of this study was to investigate the effect of neutropenia during the first cycle of induction chemotherapy (IC-1) on survival in locoregionally advanced nasopharyngeal carcinoma (LANPC). Materials and Methods Eligible patients (n=545) with LANPC receiving IC+concurrent chemoradiotherapy were included. Based on nadir neutrophil after IC-1, all patients were categorized into three groups: no/grade 1-2/grade 3-4 neutropenia. Five-year overall survival (OS) and disease-free survival (DFS) were compared between groups and subgroups stratified by IC regimen. We also explored the occurrence of IC-1–induced myelosuppression events and the minimal value of post-treatment neutrophil-to-lymphocyte ratio (post-NLRmin). Univariate/multivariate analyses were performed to investigate the effect of IC-1–induced neutropenia, timing of neutropenia, number of myelosuppression events, and high post-NLRmin on OS/DFS. Results Grade 1-2/grade 3-4 neutropenia were associated with poorer OS/DFS than no neutropenia (all p < 0.05); OS/DFS were not significantly different between patients experiencing grade 1-2 vs. 3-4 neutropenia. Neutropenia had no significant effect on OS/DFS in patients receiving docetaxel–cisplatin–5-fluorouracil (TPF). Grade 1-2 (grade 3-4) neutropenia negatively influenced OS/DFS in patients receiving cisplatin–5-fluorouracil (PF) (PF and docetaxel– cisplatin [TP]; all p < 0.05). Neutropenia, two/three myelosuppression events, and high post-NLRmin ( 1.33) was most frequent on days 5-10, second and third week of IC-1, respectively. After adjustment for covariates, IC-1–induced neutropenia, two/three myelosuppression events, and post-NLRmin  1.33 were validated as negative predictors of OS/DFS (all p < 0.05); timing of neutropenia had no significant effect. Conclusion Occurrence of neutropenia, number of myelosuppression events, and high post-NLRmin during PF/TP IC-1 have prognostic value for poor survival in LANPC.

Clinical Applications of CT Myocardial Perfusion Imaging

Cheng Xu,Yan Yi,Yining Wang 아시아심장혈관영상의학회 2020 Cardiovascular Imaging Asia Vol.4 No.4

With the continuous development of CT technology, myocardial CT perfusion imaging (CTP) has exhibited great advantages and been shown to have incremental value over coronary CT angiography, providing functional evaluation of coronary artery disease (CAD). Comprehensive assessment of CAD using cardiac CT has become feasible. This article introduces the preliminary clinical experience and advances with CTP and briefly reviews the feasibility verification, diagnostic performance, clinical strategy optimization and prognostic evaluation of CTP.

Mint powder assisted synthesis of CQDs/BiOCl with tunable OVs and improved photocatalytic property

Chengxu Lai,Junbo Zhong,Jiufu Chen,Yongbing Zhu 한국공업화학회 2023 Journal of Industrial and Engineering Chemistry Vol.128 No.-

Development of advanced technologies for the removal of perfluorooctanoic acid (PFOA) from waterbodyhas been a challenge because of the persistent, widely distributed and potentially toxic nature of PFOA inthe aquatic environment as well as the high binding energy of C-F bond, therefore, it is difficult to removePFOA by routine heating, ultraviolet radiation and biological degradation. In this study, BiOCl-based photocatalystscontaining carbon quantum dots (CQDs) with visible light reactivity were prepared by ahydrothermal approach using mint powder (MNP) as raw material for CQDs. The prepared samples exhibitself-assembled three dimensions (3D) flower-like microspheres with adjustable oxygen vacancies(OVs). The experimental results show that the activity of BiOCl modified with CQDs is significantlyincreased compared to that of the reference BiOCl. When the mass ratio of MNP/BiOCl is 2%, the 2%CQDs/BiOCl photocatalyst shows a three-fold enhancement in degradation activity toward destructionof rhodamine (RhB) compared with the reference BiOCl under visible light irradiation. Additionally,degradation activity of 2% CQDs/BiOCl catalyst toward decontamination of PFOA under UV light irradiationalso increases. This presentation offers a robust strategy for the synthesis of significantly efficientphotocatalysts for detoxification of the organic pollutants.

Enhanced dynamic performance of twisted and coiled soft actuators using graphene coating

Piao, Chengxu,Jang, Hoyoung,Lim, TaeGyeong,Kim, Hyeongkeun,Choi, Hyouk Ryeol,Hao, Yufeng,Suk, Ji Won Elsevier Science Ltd 2019 Composites Part B, Engineering Vol.178 No.-

<P><B>Abstract</B></P> <P>Twisted and coiled actuators (TCAs) composed of fishing lines or sewing threads are one of the most promising artificial muscles because of their high specific power, large stroke, and low fabrication cost. Since the TCA can be thermally actuated, the thermal properties of the actuator determine its actuation performance. Here, graphene materials with high thermal conductivity and low thermal mass were used as coating materials on nylon TCA surfaces to enhance the dynamic responses of the TCA. Large-area monolayer graphene and porous graphene foam were wrapped on the TCA surface and provided a reduction of the actuation cycle times by 10.1 and 17.8%, respectively. Furthermore, high-quality multi-layer graphene flakes were spray-coated on the surface of the TCA, showing a dramatic decrease in the cycle time by 30.9%. The enhanced heat transfer due to the graphene flake coating also increased the maximum strain of the TCA over 3 times under a duty cycle of a pulsed current input. This demonstrates an alternative way to improve the dynamic performance of the TCA using a simple coating method.</P>

탄소나노튜브 복합재를 이용한 고분자 액추에이터의 냉각 개선

박성욱 ( Chengxu Piao ),석지원 ( Ji Won Suk ) 한국복합재료학회 2017 Composites research Vol.30 No.2

낚싯줄이나 재봉실을 꼬아서 만드는 코일형 고분자 액추에이터는 열을 가하거나 냉각하면 수축하거나 늘어나면서 작동을 하게 된다. 따라서, 코일형 고분자 액추에이터의 동작 속도는 가열 및 냉각 속도에 매우 민감하게 되는 문제가 있다. 코일형 고분자 액추에이터의 동작 속도를 개선하기 위해서, 폴리디메틸실록산 복합재를 액추에이터에 코팅하였다. 폴리디메틸실록산에 다중벽 탄소나노튜브를 혼합함으로써, 액추에이터의 동작 속도를 약 13% 개선하였다. Coiled polymer actuators fabricated by twisting polymer fishing lines or sewing threads respond to heating and cooling with their contraction and relaxation. However, their actuation speed is highly dependent on the heating and cooling rates. In order to improve the actuation speed, the coiled polymer actuator was coated with polydimethylsiloxane composites. The introduction of multi-walled carbon nanotubes into the polydimethylsiloxane improved the actuation speed by about 13%.