Effects of polymer surface energy on morphology and properties of silver nanowire fabricated via nanoimprint and E-beam evaporation

Zhao, Zhi-Jun,Hwang, Soon Hyoung,Jeon, Sohee,Jung, Joo-Yun,Lee, Jihye,Choi, Dae-Geun,Choi, Jun-Hyuk,Park, Sang-Hu,Jeong, Jun-Ho Elsevier 2017 APPLIED SURFACE SCIENCE - Vol.420 No.-

<P><B>Abstract</B></P> <P>In this paper, we demonstrate that use of different nanoimprint resins as a polymer pattern has a significant effect on the morphology of silver (Ag) nanowires deposited via an E-beam evaporator. RM-311 and Ormo-stamp resins are chosen as a polymer pattern to form a line with dimensions of width (100nm)×space (100nm)×height (120nm) by using nanoimprint lithography (NIL). Their contact angles are then measured to evaluate their surface energies. In order to compare the properties of the Ag nanowires deposited on the various polymer patterns with different surface energies, hydrophobic surface treatment of the polymer pattern surface is implemented using self-assembled monolayers. In addition, gold and aluminum nanowires are fabricated for comparison with the Ag nanowires, with the differences in the nanowire morphologies being determined by the different atomic properties. The monocrystalline and polycrystalline structures of the various Ag nanowire formations are observed using transmission electron microscopy. In addition, the melting temperatures and optical properties of four kinds of Ag nanowire morphologies deposited on various polymer patterns are evaluated using a hot plate and an ultraviolet-visible (UV–vis) spectrometer, respectively. The results indicate that the morphology of the Ag nanowire determines the melting temperature and the transmission. We believe that these findings will greatly aid the development of NIL, along with physical evaporation and chemical deposition techniques, and will be widely employed in optics, biology, and surface wettability applications.</P> <P><B>Highlights</B></P> <P> <UL> <LI> Ag nanowires with various morphologies deposited on polymer patterns with different surface energies were fabricated via nanoimprint and e-beam evaporation. </LI> <LI> The formation mechanism behind the different morphologies of the Ag nanowires deposited on the polymer patterns with different surface energies was explained and confirmed. </LI> <LI> The morphologies of Ag nanowires have an important effect on their transmission and melting temperature. </LI> </UL> </P> <P><B>Graphical abstract</B></P> <P>[DISPLAY OMISSION]</P>

Modulation of Drug Resistance in Ovarian Cancer Cells by Inhibition of Protein Kinase C-alpha (PKC-α) with Small Interference RNA (siRNA) Agents

Zhao, Li-Jun,Xu, Heng,Qu, Jun-Wei,Zhao, Wan-Zhou,Zhao, Yi-Bing,Wang, Jin-Hua Asian Pacific Journal of Cancer Prevention 2012 Asian Pacific journal of cancer prevention Vol.13 No.8

Objective: To determine whether silence of $PKC-{\alpha}$ expression by small interference RNA (siRNA) might regulate MDR1 expression and reverse chemoresistance of ovarian cancer. Methods: We measured gene and protein expression of MDR1 and $PKC-{\alpha}$ in ovarian cancer cells and assessed their correlation with cell drug resistance. We also examined whether blocking $PKC-{\alpha}$ by RNA interference (RNAi) affected MDR1 expression and reversed drug resistance in drug sensitivity tests. Results: The drug resistance cell lines, OV1228/DDP and OV1228/Taxol, had higher gene and protein expression of MDR1 and $PKC-{\alpha}$ than their counterpart sensitive cell line, OV1228. SiRNA depressed $PKC-{\alpha}$ gene protein expression, as well as MDR1 and protein expression and improved the drug sensitivity in OV1228/DDP and OV1228/Taxol cells. Conclusion: These results indicated that decreasing $PKC-{\alpha}$ expression with siRNA might be an effective method to improve drug sensitivity in drug resistant cells with elevated levels of $PKC-{\alpha}$ and MDR1. A new siRNA-based therapeutic strategy targeting $PKC-{\alpha}$ gene could be designed to overcome the chemoresistance of ovarian cancer.

Macrophages Promote Coal Tar Pitch Extract-induced Tumorigenesis of BEAS-2B Cells and Tumor Metastasis in Nude Mice Mediated by AP-1

Zhang, Peng,Jin, Yue-Fei,Zhang, Qiao,Wu, Yi-Ming,Wu, Wei-Dong,Yao, Wu,Wu, Yong-Jun,Li, Zhi-Tao,Zhao, Yong,Liu, Yu,Feng, Fei-Fei Asian Pacific Journal of Cancer Prevention 2014 Asian Pacific journal of cancer prevention Vol.15 No.12

Background: We sought to evaluate the role of tumor associated macrophages (TAMs) on the promotion of coal tar pitch extract (CTPE)-induced tumorigenesis of human bronchial epithelial cells (BEAS-2B) and tumor metastasis in nude mice, and related mechanisms. Materials and Methods: BEAS-2B cells were first treated with 2.4 mg/mL CTPE for 72 hours. After removal of CTPE, the cells were continuously cultured and passaged using trypsin-EDTA. THP-1 cells were used as macrophage-like cells. BEAS-2B cells under different conditions (n=6/group) were injected into the back necks of nude mice, and alterations of tumor xenograft growth, indicative of tumorigenicity, and tumor metastasis were determined. Pathological changes (tumor nests and microvascular lesions) of HE-stained tumor tissues were also evaluated. The expression of AP-1(c-Jun) in xenografts and metastatic tumors was determined using immunohistochemistry. Results: Tumor size and weight in nude mice transplanted with the mixture of CTPE-induced passage 30 BEAS-2B and THP-1 cells (2:1) were increased compared to those from the CTPE-treated BEAS-2B cells at passage 30 alone at different observation time points. Tumor metastasis to lymph nodes and liver was only detected after transplantation of a mixture the two kinds of cells. The numbers of tumor nests and microvascular lesions, and the expression levels of AP-1 (c-Jun) in tumors from the mixture of two kinds of cells were increased apparently in contrast to those in tumor from the CTPE-treated BEAS-2B cells of passage 30 alone. In addition, there was positive correlation between AP-1 (c-Jun) expression level and the number of microvascular lesions, or between AP-1 (c-Jun) expression level and tumor metastasis in these two groups. Conclusions: TAMs not only facilitate tumorigenesis transformation of CTPE-induced BEAS-2B cells, but also promote tumor growth, angiogenesis and metastasis in nude mice in vivo, which may be mediated by AP-1.

Influence of latitude wind pressure distribution on the responses of hyperbolodial cooling tower shell

Jun-Feng Zhang,Yao-Jun Ge,Lin Zhao 한국풍공학회 2013 Wind and Structures, An International Journal (WAS Vol.16 No.6

Interference effects are of considerable concern for group hyperboloidal cooling towers, but evaluation methods and results are different from each other because of the insufficient understanding on the structure behavior. Therefore, the mechanical performance of hyperboloidal cooling tower shell under wind loads was illustrated according to some basic properties drawn from horizontal rings and cantilever beams. The hyperboloidal cooling tower shell can be regarded as the coupling of horizontal rings and meridian cantilever beams, and this perception is beneficial for understanding the mechanical performance under wind loads. Afterwards, the mean external latitude wind pressure distribution, CP(θ), was artificially adjusted to pursue the relationship between different CP(θ) and wind-induced responses. It was found that the maximum responses in hyperboloidal cooling tower shell are primarily dominated by the non-uniformity of CP(θ) but not the local pressure amplitude CP or overall resistance/drag coefficient CD. In all the internal forces, the maximum amplitude of meridian axial tension shows remarkable sensitivity to the variation of CP(θ) and it’s also the controlling force in structure design, so it was selected as an indicator to evaluate the influence of CP(θ) on responses. Based on its sensitivity to different adjustment parameters of CP(θ), an comprehensive response influence factor, RIF, was deduced to assess the meridian axial tension for arbitrary CP(θ).

Effect of substrate reflecting conditions on the curing of UV curable resin layers on aluminum and the formation of surface wavy structures

Zhao, Zhi-Jun,Yang, Jeong-Ho,Li, Xin,Park, Sang-Hu Elsevier 2016 Materials letters Vol.164 No.-

<P><B>Abstract</B></P> <P>We have investigated the formation of surface wavy structures (wrinkles) depending on the diverse surface conditions of a substrate, and now report the effect of various levels of reflection of incident ultraviolet (UV)-light. UV-curable resin layers with a thickness of 0.15mm were coated on three different surface conditions; transparent glass, fine and rough surface aluminum plate, to compare the formation of wrinkles on each surface. Short irradiations of UV-light for 10, 15, 20, 25 and 30s were exposed, resulting in the weak to full polymerization of the skin of a resin layer, respectively. The wavy structures were formed during thermal curing under room temperature after the short exposure of UV-light. The difference in reflection conditions resulting from the various surface roughnesses of the substrates led to changes in the amounts of polymerization, and the distribution of polymerization intensity through the layer thickness. Due to these different mechanisms, wrinkling shapes were quite distinguished. Through this work, we observed that controllable producing an approximately 33% maximum difference in the line width of wrinkles by using different substrate surface conditions.</P> <P><B>Highlights</B></P> <P> <UL> <LI> The effect of a substrate reflection condition was investigated for diverse generation of surface wrinkles. </LI> <LI> It was studied that the fundamental mechanism on formation of wrinkles by weak-polymerization and thermal curing process. </LI> <LI> Irregular line-shapes of wrinkles with a range of 62–92μm in line width were fabricated by using the effect of substrate reflection conditions. </LI> <LI> Contact angle was varied depending on wrinkle shapes from 63° to 76°. </LI> </UL> </P>

Influence of Li Addition on the Microstructures and Mechanical Properties of Mg–Li Alloys

Jun Zhao,Jie Fu,Bin Jiang,Aitao Tang,Haoran Sheng,Tianhao Yang,Guangsheng Huang,Dingfei Zhang,Fusheng Pan 대한금속·재료학회 2021 METALS AND MATERIALS International Vol.27 No.6

In this study, Mg-xLi (x = 0, 1, 2, 3 and 5 wt%) alloys have been extruded to examine the role of Li content on microstructuresand tensile properties. The results revealed that Li addition increased the grain size and led to the formation of the transversedirection (TD)-split texture. These were mainly attributed to the promoted DRX process and the increased activity of prismatic⟨a⟩ slip during extrusion. Tensile tests revealed that the elongation of Mg-5Li sheet reached ~ 22.4% along the ED. Moreover, it exhibited a higher elongation of ~ 27.3%, three times than pure Mg, along the TD. During tension along the ED,with increasing Li content, more prismatic ⟨a⟩ slip and preferable intergranular strain coordination ability to accommodatethe plastic strain, leading to the enhanced room-temperature ductility. In contrast, more basal ⟨a⟩ slips and extension twinswere also activated along the TD, which further contributed to the enhanced ductility. Therefore, the ductility of Mg sheetsat room temperature gradually improved with Li addition due to the combining effects of basal ⟨a⟩ slip, prismatic ⟨a⟩ slip,extension twin and preferable intergranular strain coordination ability.

Effects of stiffening rings on the dynamic properties of hyperboloidal cooling towers

Jun-Feng Zhang,Huai Chen,Yao-Jun Ge,Lin Zhao,Shi-Tang Ke 국제구조공학회 2014 Structural Engineering and Mechanics, An Int'l Jou Vol.49 No.5

As hyperboloidal cooling towers (HCTs) growing larger and slender, they become more sensitive to gust wind. To improve the dynamic properties of HCTs and to improve the wind resistance capability, stiffening rings have been studied and applied. Although there have been some findings, the influence mechanism of stiffening rings on the dynamic properties is still not fully understood. Based on some fundamental perceptions on the dynamic properties of HCTs and free ring structures, a concept named “participation degree” of stiffening rings was proposed and the influence mechanism on the dynamic properties was illustrated. The “participation degree” is determined by the modal deform amplitude and latitude wave number of stiffening rings. Larger modal deform amplitude and more latitude waves can both result in higher participation degree and more improvement to eigenfrequencies. Also, this concept can explain and associate the pre-existing independent findings.

Adhesive-Layer-Free and Double-Faced Nanotransfer Lithography for a Flexible Large-Area MetaSurface Hologram

Zhao, Zhi-Jun,Hwang, Soon Hyoung,Kang, Hyeok-Joong,Jeon, Sohee,Bok, Moonjeong,Ahn, Sunggyun,Im, DaJeong,Hahn, Joonku,Kim, Hwi,Jeong, Jun-Ho American Chemical Society 2020 ACS APPLIED MATERIALS & INTERFACES Vol.12 No.1

<P>Herein, we develop an adhesive-free double-faced nanotransfer lithography (ADNT) technique based on the surface deformation of flexible substrates under the conditions of temperature and pressure control and thus address the challenge of realizing the mass production of large-area nanodevices in the fields of optics, metasurfaces, and holograms. During ADNT, which is conducted on a flexible polymer substrate above its glass transition temperature in the absence of adhesive materials and chemical bonding agents, nanostructures from the polymer stamp are attached to the deformed polymer substrate. Various silicon masters are employed to prove our method applicable to arbitrary nanopatterns, and diverse Ag and Au nanostructures are deposited on polymer molds to demonstrate the wide scope of useable metals. Finally, ADNT is used to (i) produce a flexible large-area hologram on the defect-free poly(methyl methacrylate) (PMMA) film and (ii) fabricate a metasurface hologram and a color filter on the front and back surfaces of the PMMA film, respectively, to realize dual functionality. Thus, it is concluded that the use of ADNT can decrease the fabrication time and cost of high-density nanodevices and facilitate their commercialization.</P> [FIG OMISSION]</BR>

The Efficacy of Aspirin in Preventing the Recurrence of Colorectal Adenoma: a Renewed Meta-Analysis of Randomized Trials

Zhao, Tai-Yun,Tu, Jing,Wang, Yin,Cheng, Da-Wei,Gao, Xian-Kui,Luo, Hao,Yan, Bi-Chun,Xu, Xiao-Li,Zhang, Hong-Ling,Lu, Xing-Jun,Wang, Yao-Jun Asian Pacific Journal of Cancer Prevention 2016 Asian Pacific journal of cancer prevention Vol.17 No.5

Background: Through search the possible randomized control trials, we make a renewed meta-analysis in order to assess the impact of aspirin in preventing the recurrence of colorectal adenoma. Materials and Methods: The Medicine/PubMed, Embase, Cochrane Central Register of Controlled Trials (CENTRAL), Chinese biomedical literature service system (SinoMed) databases were searched for the related randomized controlled trials until to the April 2016. Three different authors respectively evaluated the quality of studies and extracted data, and we used the STATA software to analyze, investigate heterogeneity between the data, using the fixed-effects model to calculate and merge data. Results: 7 papers were included the renewed meta-analysis, among these studies, two pairs were identified as representing the same study population, with the only difference being the duration of follow-up. Thus there were only five papers included our meta-analysis, and one Chinese paper were also included the work. Results were categorized by the length of follow-up, different kinds of people, varied dose of oral aspirin. The relative of adenoma in patients taking aspirin vs placebo were 0.73 (95% CI 0.55-0.98, P=0.039) with 1 year follow up; 0.84 (95% CI 0.72-0.98, P=0.484) with greater than 1 year follow up; for the advanced adenoma, the RR 0.68 (95% CI 0.49-0.94, P=0.582),for one year; RR=0.75 (95% CI 0.52-1.07, P=0.552) for greater one year. Furthermore the white population could divided into two subgroups according to the different length of follow-up time. When the length of follow-up time less than 3-year, The RR of two subgroups respective were RR=0.86 (95% CI 0.76-0.98, P=0.332), $I^2=0%$, RR=0.68 (95% CI 0.47-0.98, P=0.552), $I^2=64.6%$, But with the extension of follow-up time greater than 2-year, with the white, oral aspirin without considering dose had no efficacy on preventing the recurrence of any adenoma, the RR was 0.86 (95% CI 0.71-1.05, P=0.302), $I^2=16.4%$. Conclusions: This meta-analysis indicated that oral aspirin is associated with a remarkable decrease in the recurrence of any adenoma and advanced adenomas in patients follow-up for 1 year without concerning the dose of aspirin, but with the extension of follow-up time for greater than 1 year, oral aspirin can be effective on preventing the recurrence of any adenoma, but for the advanced adenoma, the result indicated that oral aspirin had no efficacy, According to the inclusion of ethnic groups, we also divided relevant papers into two subgroups as the yellow and white group. Then the follow-up time was less than 3 years, oral aspirin without considering the dose, had an significant efficacy on preventing the recurrence of any adenoma. But with the follow-up greater than 2 years, oral aspirin had no effect in the white.

UV and Visible Electroluminescence From a <tex> $ \hbox{Sn:Ga}_{2}\hbox{O}_{3}/\hbox{n}^{+}\hbox{-Si}$</tex> Heterojunction by Metal–Organic Chemical Vapor Deposition

Jun Liang Zhao,Xiao Wei Sun,Hyukhyun Ryu,Swee Tiam Tan IEEE 2011 IEEE transactions on electron devices Vol.58 No.5

<P>A Sn-doped Ga<SUB>2</SUB>O<SUB>3</SUB> thin film was deposited on a n<SUP>+</SUP>-Si substrate by metal-organic chemical vapor deposition. The Ga<SUB>2</SUB>O<SUB>3</SUB> film was found to be amorphous-like and exhibited n-type conduction with Sn doping. Room-temperature electroluminescence was clearly observed from the Sn:Ga<SUB>2</SUB>O<SUB>3</SUB>/n<SUP>+</SUP> -Si diode, including an ultraviolet (UV) emission at ~ 370 nm, a yellow emission at ~ 580 nm, and a red emission at ~ 680 nm. The UV emission is assigned to the transition from Sn<SUB>Ga</SUB> donor to the <I>V</I><SUB>Ga</SUB> acceptor, whereas the visible emissions were assigned to be related to the dangling bond defects.</P>