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Research Express@NCKU Volume 28 Issue 8 - March 13, 2015 [ http://research.ncku.edu.tw/re/articles/e/20150313/1.html ]

Synergistic Effect of Dual Interfacial Modifications with Room-Temperature-Grown Epitaxial ZnO and Adsorbed Indoline Dye for ZnO Nanorod Array/P3HT Hybrid Solar Cell

Dian-Wei Chen, Ting-Chung Wang, Wen-Pin Liao, Jih-Jen Wu*

Department of Chemical Engineering, National Cheng Kung University

wujj@mail.ncku.edu.tw

ACS Appl. Mater. Interfaces, Vol. 5, No.17, 8359–8365, 2013

A synergistic effect of the dual interfacile modifications on the photovoltaic performances

of the ZnO nanorod (NR)/poly (3-hexylthiophere) (P3HT) hybrid solar cells is observed in this study. The ZnO NR arrays are modified with room-temperature (RT) grown epitaxial ZnO shells and D149 dye molecules prior to the P3HT infiltration. The epitaxial interface between RT-grown ZnO shell and ZnO NR, and the chemical compatibility of D149 and P3HT as well as the elevated conduction band edge of the RT-grown ZnO/D149-modified ZnO NR array construct the superior interfacial morphology and energetic in the RT-grown ZnO/D149-modified ZnO NR/P3HT hybrid solar cell. The open-circuit voltage and fill factor are considerable improved through the RT-grown ZnO and D149 modifications in sequence on the ZnO NR array, which brings about a 2-fold enhancement of the efficiency of the ZnO NR/P3HT solar cell.

Figure 1 (a) HRTEM image of the epitaxial RT-grown ZnO shell formed on the ZnO NR. (b) J−V curves of the ZnO NR/P3HT solar cells with and without interfacile modification. (c) Energy diagram of dual interfacile modified ZnO NR/P3HT hybrid.

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Research Express@NCKU Volume 28 Issue 8 - March 13, 2015 [ http://research.ncku.edu.tw/re/articles/e/20150313/2.html ]

Micro-sublimation separation of boron in rock samples for isotopic measurement by MC-ICPMS

Ju-lien Pi1, Chen-Feng You1,2,* , Chuan-Hsiung Chung2

1 Department of Earth Sciences, National Cheng Kung University, Tainan 70101, Taiwan. 2 Earth Dynamic System Research Center, National Cheng Kung University, Tainan 70101, Taiwan

cfy20@mail.ncku.edu.tw

J. Anal. At. Spectrom., 2014,29, 861-867

The material recycling and redistribution in subduction zones is of research interest

because the subduction process, which includes slabs dehydration/metamorphism and arcs forming, is the major way that crusts back to the mantle. Boron was regarded as an excellent tracer for studying crust-mantle interaction in subduction zones, for its great discrepancy both in concentrations and isotopic ratios in these two reservoirs1,2. Besides boron is fluid-mobile3 in the slab dehydration/metamorphism process and incompatible1 during partial-melting of arc magmas. The boron isotopes in rock were not easily measurable because it is rather volatile in acid digestion process and contamination may bias isotope values. Until latest two decades, the reliable acid digestion method has been developed4 and laboratory environment generally improved. But the conventional boron separation by using multi-steps ion-exchange is still of labor-consuming. For the analytical techniques, the MC-ICPMS measurement for boron isotopes was developed and is as precise as TIMS but much faster. In this study an efficient microsublimation technique is developed to separation boron from rock solution for isotopes measurement by MC-ICPMS. Microsublimation was reported capable of separating boron from organic-rich solution5 and from Na, Ca-rich solution6. This study evaluated it for rock samples. Our experiments show that proper NaCl doing into the rock solution makes boron separation successful by microsublimation. The experimental procure is shown in Fig 1. Nine international rock standards were examined and the result shows consistency between our measurements and the literature values (Fig 2). The evaluation of our developed technique show that there was still minor quantity of Si in rock solution not separable by microsublimation and make possible error of <0.8‰ in the MC-ICPMS measurement. This technique is readily applicable on geochemistry studies for rocks > 5 ppm boron and potentially for low-boron rock and complex-matrices aqueous. This study developed an efficient low-blank microsublimation method of rock boron separation for MC-ICPMS isotopes measurement.

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Fig 1. The simplified work-flow of this study. From rock digestion, NaCl doping, microsublimation to boron isotopes measurement by MC-ICPMS.

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Fig 2. The comparison of the boron isotopes results of international rock standards by this study and literature

values.

Reference:

1. T. Ishikawa and E. Nakamura, Nature, 1994, 370, 205–208.2. J. Hoefs, in Stable isotope geochemistry, Springer-Verlag, Berlin Heidelberg, 5th edn, 2004, ch. 2, pp. 45–

48.3. G. E. Bebout, J. G. Ryan and W. P. Leeman, Geochim. Cosmochim. Acta, 1993, 51, 2227–2237.4. E. Nakamura, T. Ishikawa, J. L. Birck and C. J. All´egre, Chem. Geol., 1992, 94, 193–204.5. B. S. Wang, C. F. You, K. F. Huang, S. F. Wu, S. K. Aggarwal, C. H. Chung and P. Y. Lin, Talanta, 2010,

82, 1378-1384.6. J. Gaillarde, D. Lemarchand, C. Göpel and G. Manhès, Geostand. Newsl., 2001, 25, 67-75.

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Research Express@NCKU Volume 28 Issue 8 - March 13, 2015 [ http://research.ncku.edu.tw/re/articles/e/20150313/3.html ]

Characterization of Aging-associated Cardiac Diastolic Dysfunction

Wei-Ting Chang1, Jung San Chen2, Yung-Kung Hung2, Jer-Nan. Juang2, Ping-Yen Liu1,3,*

1 Division of Cardiology, Internal Medicine, National Cheng Kung University Hospital, Tainan, Taiwan 2 Department of Engineering Science, National Cheng Kung University, Tainan, Taiwan 3 Institute of Clinical Medicine, National Cheng Kung University, Tainan, Taiwan

larry@mail.ncku.edu.tw

PLOS one, May 28, 2014, DOI: 10.1371/journal.pone.0097455

Herein we proposed a material and mathematical model for myocardium stiffness based

on the concept of linear correlation between e/e’ and wedge pressure. Diastolic dysfunction is a common clinical manifestation in heart failure of geriatric patients [1][2] . With background variable like age, a reliable parameter to predict stiffness of myocardium and its relaxation under similar end-diastolic pressure remains developing[3]. The clinical and echocardiographic characteristics of younger and older populations

A total of 919 patients (male gender: 52.6 % (484/919)) were enrolled in this analysis. Compared with younger population, the elderly (>65 years of age) had more prevalence of hypertension, diabetes mellitus and coronary artery disease. Echocardiographic parameters to describe left ventricular function were measured accordingly (Fig.1). In contrast to left ventricular systolic ejection fraction, which was within the normal range in all subjects (LVEF 68.2 ± 8.4 vs. 70.0 ± 6.7, p = 0.09), the averaged early diastolic velocity of mitral annulus in tissue Doppler was significantly attenuated in the elders (e’ 0.09 ± 0.02 vs. 0.08 ± 0.02, p = 0.02), corresponding to the higher estimated wedge (e/e’) pressure (7.76 ± 2.44 vs. 8.35 ± 2.64, p = 0.02).

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Figure 1. The measured echocardiographic parameters; IVSd: intraventricular septal width in diastole, LVIDd: left ventricular Internal dimension in diastole, LVPWd: left ventricualr posterior wall width in diastole and LVIDs: left ventricular Internal dimension in systole.

The relationship between E value and echocardiographic intra-ventricular pressure in younger and older populations

The E value (Young’s modulus) was calculated to describe the tensile elasticity of the myocardium according to the cylinder mathematic model (Fig.2).

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Figure 2. The model of the cylinder in gross and cross section.

Our results showed that, even under the same intra-ventricular filling pressure, the E value was significantly higher in the geriatric subjects, especially with higher e/e’ value (>9) (Fig.3A). By regression analysis, an exponential correlation between age and E value could be summarized to delineate the soaring of E value in older ages (Fig. 3B)

Figure 3.A The relationship between e/e’ and E value in various age group. B. the exponential correlation between age vs. E value in the regression analysis.

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The relationship between the E value and echocardiographic wall thickness in younger and older populations

In our mathematical model, positive associations between IVSd vs. E value were displayed, along with the increasing e/e' (Fig. 4). The result also indicated that in the same LV wall width, the higher intra-ventricular pressure correlated to the higher E value.

Figure 4. In the mathematical model, the positive association between IVSd vs. E value in low, moderate and high e/e' value. LVPWd= left ventricular posterior wall width in diastole.

We conclude that our material and mathematical geometric model successfully described the myocardial stiffer character in aging hearts under higher intra-ventricular pressures. Individual differences, especially in healthy status, will be validated its future application in detecting diastolic heart failure.

Reference

1. Javed Butler AK VG, Rhonda Belue, Nicolas Rodondi, Melissa Garcia, Douglas C. Bauer, Suzanne Satterfield, Andrew L. Smith, Viola. “Incident heart failure prediction in the elderly : The health abc heart failure score.” Circ Heart Fail 1: 125-133 (2008).

2. Owan TE HD, Herges RM, Jacobsen SJ, Roger VL, Redfield MM. “Trends in prevalence and outcome of heart failure with preserved ejection fraction.” N Engl J Med 355: 251–259 (2006).

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3. Yang T CY, Wang Y, et al. “Mathematical modeling of left ventricular dimensional changes in mice during aging. BMC Systems Biology” 6: 1-12 (2012).

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Research Express@NCKU Volume 28 Issue 8 - March 13, 2015 [ http://research.ncku.edu.tw/re/articles/e/20150313/4.html ]

DC plasma chemical vapor deposition of standing multi-layer graphene nanowalls on diamond and silicon

1. Yon-hua Tzenga*, Wai Leong Chena, Chiahao Wua, Jui-Yung Loa, and Chiuan-Yi Lia2. Chia-hao Tua, Waileong Chenb, Hsin-Chiao Fanga, Yon-hua Tzengb* and Chuan-Pu Liua

1. aInstitute of Microelectronics, National Cheng Kung University, Tainan, Taiwan2. aDepartment of Materials Science and Engineering, National Cheng Kung University,

Tainan, Taiwan bInstitute of Microelectronics, National Cheng Kung University, Tainan, Taiwan

tzengyo@mail.ncku.edu.tw

1. Yonhua Tzeng*, Wai Leong Chen, Chiahao Wu, Jui-Yung Lo, and Chiuan-Yi Li, The synthesis of graphene nanowalls on a diamond film on a silicon substrate by direct-current plasma chemical vapor deposition. Carbon 53, pp. 120-129 (2013). (IF:5.87, Rank: 23/241 in Materials Science)

2. Chia-hao Tu, Waileong Chen, Hsin-Chiao Fang, Yonhua Tzeng* and Chuan-Pu Liu*, Heteroepitaxial nucleation and growth of graphene nanowalls on silicon. Carbon 54, pp. 234-240 (2013). (IF:5.87, Rank: 23/241 in Materials Science)

Graphene and diamond both exhibit outstanding physical and chemical properties and

are promising for a wide range of applications from electronics to electrochemical reactions. Thermal chemical vapor deposition of graphene on catalytic substrates such as copper usually results in graphene films lying on the substrates. On the other hand, plasma assisted chemical vapor deposition involves electric fields in the plasma sheath and the directional radical flux, which under proper conditions lead to the growth of standing graphene films. Most of these standing graphene films are multiple-layer graphene with small graphene domains. The thickness of the multi-layer graphene becomes smaller and smaller near the top edge. Under some conditions, one or few layer graphene is formed as the top edge of a standing graphene. We applied Direct-Current Plasma Enhanced Chemical Vapor Deposition (DC-PECVD) to successfully synthesize diamond films on silicon substrates followed by the synthesis of standing graphene nanowalls on the diamond films without breaking the vacuum. Plasma in different gas mixtures of methane and hydrogen assists in the synthesis of diamond and graphene. For the synthesis of diamond, higher concentration of hydrogen and lower concentration of methane are needed. For the synthesis of graphene, lower concentration of hydrogen and higher concentration of methane are needed. Therefore, by properly controlling the plasma chemistry, graphene can be grown on diamond in a continuous process. This work demonstrated the transition from diamond growth to graphene growth. PECVD microcrystalline diamond films on which graphene nanowalls stand provide excellent durability against chemical reactions and corrosion of electrodes made of the graphene on diamond hybrid substrates by the ambient environments [1].

We further investigated the possibility of heteroepitaxial growth of graphene on single crystalline silicon [2]. According to experimental results we believe that single crystal silicon is etched by ion bombardment assisted atomic hydrogen etching to form silicon {1 1 1} oriented nano-facets during the pre-treatment of the silicon crystal. In this process hydrogen plasma preferentially etches the Si (1 0 0) plane. High resolution transmission electron microscope image shows that AA stacked multi-layer graphene nanowalls nucleate on some silicon {1 1 1} nano-facets. Amorphous carbon and some silicon carbide clusters are deposited in the remaining silicon surface. The lattice mismatch between graphene (0 0 2) plane and silicon (1 1 1) plane is small, therefore, it is energy

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favorable for heteroepitaxial growth.

Figure 1. SEM image of standing graphene nanowalls grown on a CVD diamond film.

References:

1. Yonhua Tzeng*, Wai Leong Chen, Chiahao Wu, Jui-Yung Lo, and Chiuan-Yi Li, The synthesis of graphene nanowalls on a diamond film on a silicon substrate by direct-current plasma chemical vapor deposition. Carbon 53, pp. 120-129 (2013). (IF:5.87, Rank: 23/241 in Materials Science)

2. Chia-hao Tu, Waileong Chen, Hsin-Chiao Fang, Yonhua Tzeng* and Chuan-Pu Liu*, Heteroepitaxial nucleation and growth of graphene nanowalls on silicon. Carbon 54, pp. 234-240 (2013). (IF:5.87, Rank: 23/241 in Materials Science)

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