Karakterisasi Film Tipis Cu-c60/mgo Akibat Penuaan(ageing)dengan Teknik Hamburan Raman

KARAKTERISASI FILM TIPIS Cu-C60/MgO AKIBAT PENUAAN(AGEING)DENGAN TEKNIK HAMBURAN RAMAN. Film tipis campuran antara Cu dan C60 telah dianalisis dengan menggunakan spektroskopi Raman. Campuran secara atomik dideposit pada substrat Mg(001). Pengujian topografi dengan mikroskop optik menunjukkan bahwa warna film di sebagian besar sisi luar adalah coklat muda dan berubah menjadi coklat tua pada bagian tengah film. Terjadinya Perubahan warna dapat diatributkan dengan baberapa jenis interaksi kimia antara Cu-Cu, Cu-C60, C60-C60 dan Perubahan alotrop molekul C60. Dari analisis spektroskopik Raman dapat disimpulkan bahwa ciri spektrum secara kuat berkorelasi dengan variasi warna yang bergantung pada daerah pengamatan. Pada tepi filmdengan warna coklat terang (ditunjukkan pada daerah 2 dan 3) atom-atom Cu berinteraksi secara kimia dengan fullerene (Cu-C60). Pada iteraksi ini terjadi pergeseran puncak kira-kira 6 cm-1dari puncak pristine C60 yang diamati untuk puncak-puncak Ag(2) dan Hg(8). Pada pusat film dengan warna coklat gelap (ditunjukkan pada daerah 3, daerah 4 dan daerah 5) terlihat sebagai puncak baru yanang secara tipikal seperti puncak D dan G yang secara umum berkaitan dengan formasi disordered graphite melalui konversi kimia dari C60 dibawah pengaruh oksidasi

Pengaruh Iluminasi Laser Pada Film Campuran Emas-fullerene (Auc60) Dalam Analisis Spectroskopi Raman

PENGARUH ILUMINASI LASER PADA FILM CAMPURAN EMAS-FULLERENE (AUC60) DALAM ANALISIS SPECTROSKOPI RAMAN. Analisis Raman secara rinci pada campuran antara emas danfullerene (C60) telah dilakukan dengan cara mengubah intensitas laser secara sistematik untuk mempelajari pengaruh agitasi termal pada campuran. Analisis pergeseran Raman menunjukkan bahwa Perubahan secara sistematik daya laser menyebabkan pergeseran dan penyempitan puncak Raman. Kenaikan daya laser dari 0,5 miliwatt ke 3 miliwatt akan menyebabkan pergeseran-penurunan frekuensi Raman. Besarnya pergeseran frekuensi Raman kira-kira 2 cm" dan 5,4 cm", masing-masing untuk mode Ag(2) dan Hg(8). Penurunan pergeseran yang diamati berkaitan dengan beberapa macam interaksi antara atom Au dan molekul C60, seperti Au dan C60 ,,softly bound'' yang peka pada suhu sehingga kemungkinan terjadi difusi Au dalam campuran, Nano-kristal Au menunjukkan sifat kimia yang bergantung ukuran (tergantung jumlah atom Au) dan hal penting dari nano-Au adalah kemungkinan penggunaan untuk penandaan DNA, dan posisi-sensitif spektroskopi Raman memberikan kita kesempatan untuk menganalisis reaksi bio-kimia dalam ruang topologi. Kenaikan daya iluminasi menyebabkan pergeseran frekswensi teramati. Iluminasi 0,5 miliwatt dipilih sebagai satu kondisi moderat

Fundamentos de la aplicación de películas delgadas de dióxido de vanadio como posibles componentes de ventanas inteligentes

In this paper, the research on the vanadium dioxide thin film, which can be used as intelligent windows, is reviewed, including the basic properties of V2, energy band structure, model of electronic energy and the origin of metal-to-insulator transition (MIT). Finally, the problems existing in the research and the possibility of application for VO2, as an intelligent thermochromic window are briefly discussed.En este artículo se revisan las investigaciones realizadas en películas delgadas de dióxido de vanadio que pueden ser usadas en componentes de ventanas inteligentes, incluyendo las propiedades básicas del VO2, tales como su estructura de bandas, modelo energético de tipo electrónico y el origen del fenómeno de la transición: metal-aislador (MIT en la literatura inglesa) que constituye la base de las aplicaciones de estas películas. Finalmente, los problemas que hay en la investigación actual de este tipo de películas, así como sus posibles aplicaciones en ventanas inteligentes de tipo termocrómico, se discuten brevemente

Thermal evolution of defects in as-grown and electron-irradiated ZnO studied by positron annihilation

Vacancy-type defects in as-grown ZnO single crystals have been identified using positron annihilation spectroscopy. The grown-in defects are supposed to be zinc vacancy (VZn)-related defects, and can be easily removed by annealing above 600 °C. VZn-related defects are also introduced in ZnO when subjected to 3 MeV electron irradiation with a dose of 5.5×1018 cm−2. Most of these irradiation-induced VZn are annealed at temperatures below 200 °C through recombination with the close interstitials. However, after annealing at around 400 °C, secondary defects are generated. A detailed analysis of the Doppler broadening measurements indicates that the irradiation introduced defects and the annealing induced secondary defects belong to different species. It is also found that positron trapping by these two defects has different temperature dependences. The probable candidates for the secondary defects are tentatively discussed in combination with Raman scattering studies. After annealing at 700 °C, all the vacancy defects are annealed out. Cathodoluminescence measurements show that VZn is not related to the visible emission at 2.3 eV in ZnO, but would rather act as nonradiative recombination centers

Microvoid formation in hydrogen-implanted ZnO probed by a slow positron beam

ZnO crystals were implanted with 20–80 keV hydrogen ions up to a total dose of 4.4×1015 cm−2. Positron lifetime and Doppler broadening of annihilation radiation measurements show introduction of zinc vacancy-related defects after implantation. These vacancies are found to be filled with hydrogen atoms. After isochronal annealing at 200–500 °C, the vacancies agglomerate into hydrogen bubbles. Further annealing at 600–700 °C causes release of hydrogen out of the bubbles, leaving a large amount of microvoids. These microvoids are annealed out at high temperature of 1000 °C. Raman spectroscopy for the implanted sample shows the enhancement of vibration modes at about 575 cm−1, which indicates introduction of oxygen vacancies. These oxygen vacancies disappear at temperatures of 600–700 °C, which is supposed to contribute to the hydrogen bubble formation. Cathodoluminescence measurements reveal that hydrogen ions also passivate deep level emission centers before their release from the sample, leading to the improvement of the UV emission

Rutherford Backscattering Investigation of the Corrosion of Borosilicate Glass

The RBS spectra from Frit 21 borosilicate glasses doped with 5 wt % UO/sub 2/, SrO, or Cs/sub 2/O show that: during the initial stages of leaching (0 to 3 h) there is a substantial (300 to 500%) enhancement in the concentration of U, Sr, Ca, and Ti in the outer surface layer and that this enhancement is accompanied by a large depletion of Na, Si, and Cs; and upon further leaching under static conditions (24 h) the leached surface layer composition is indistinguishable from the unleached surface. Other borosilicate glasses such as PNL 76-68 may eventually show the same behavior if the final equilibrium pH value is greater than 9. The technique of Rutherford backscattering depth profile analysis can be a powerful tool for investigating the initial stages of glass corrosion

Propiedades ópticas de películas de dióxido de vanadio como recubrimiento termocrómico en ventanas

The optical properties of vanadium dioxide (VO2) thin film have been studied for the potential application of intelligent windows. The results show that VO2 film deposited on sapphire substrates exhibits good thermochromic effects, its IR transmittance changes 60% before and after phase transition, and has less thickness dependence than UV transmittance. Doping can significantly reduce transition temperature, such as to 30°C for 1.5% Mo doped VO2.Se han investigado las propiedades ópticas del dióxido de vanadio (VO2) aplicado como películas delgadas para posibles aplicaciones en ventanas inteligentes. Cuando el VO2 se deposita sobre sustratos de zafiro da lugar a efectos termocrómicos considerables; así, su transmitancia en el infrarrojo cambia en un 60 % después de la transición de fase del dióxido de vanadio, teniendo una dependencia menor con el espesor que la transmitancia en el ultravioleta. El efecto de aditivos sobre estas películas de dioxido de vanadio da lugar a una disminución de la temperatura de dicha transición responsable del efecto termocrómico, de manera que se produce a 30°C con el 1,5 % de adición de Mo

Emergence of tissue polarization from synergy of intracellular and extracellular auxin signaling

Here, we provide a novel mechanistic framework for cell polarization during auxin-driven plant development that combines intracellular auxin signaling for regulation of expression of PINFORMED (PIN) auxin efflux transporters and the theoretical assumption of extracellular auxin signaling for regulation of PIN subcellular dynamics.The competitive utilization of auxin signaling component in the apoplast might account for the elusive mechanism for cell-to-cell communication for tissue polarization.Computer model simulations faithfully and robustly recapitulate experimentally observed patterns of tissue polarity and asymmetric auxin distribution during formation and regeneration of vascular systems, and during the competitive regulation of shoot branching by apical dominance.Our model generated new predictions that could be experimentally validated, highlighting a mechanistically conceivable explanation for the PIN polarization and canalization of the auxin flow in plants

Conformal invariance: from Weyl to SO(2,d)

The present work deals with two different but subtilely related kinds of conformal mappings: Weyl rescaling in $d>2$ dimensional spaces and SO(2,d) transformations. We express how the difference between the two can be compensated by diffeomorphic transformations. This is well known in the framework of String Theory but in the particular case of $d=2$ spaces. Indeed, the Polyakov formalism describes world-sheets in terms of two-dimensional conformal field theory. On the other hand, B. Zumino had shown that a classical four-dimensional Weyl-invariant field theory restricted to live in Minkowski space leads to an SO(2,4)-invariant field theory. We extend Zumino's result to relate Weyl and SO(2,d) symmetries in arbitrary conformally flat spaces (CFS). This allows us to assert that a classical $SO(2,d)$-invariant field does not distinguish, at least locally, between two different $d$-dimensional CFSs.Comment: 5 pages, no figures. There are slight modifications to match with the published versio

Imatinib and Nilotinib Reverse Multidrug Resistance in Cancer Cells by Inhibiting the Efflux Activity of the MRP7 (ABCC10)

One of the major mechanisms that could produce resistance to antineoplastic drugs in cancer cells is the ATP binding cassette (ABC) transporters. The ABC transporters can significantly decrease the intracellular concentration of antineoplastic drugs by increasing their efflux, thereby lowering the cytotoxic activity of antineoplastic drugs. One of these transporters, the multiple resistant protein 7 (MRP7, ABCC10), has recently been shown to produce resistance to antineoplastic drugs by increasing the efflux of paclitaxel. In this study, we examined the effects of BCR-Abl tyrosine kinase inhibitors imatinib, nilotinib and dasatinib on the activity and expression of MRP7 in HEK293 cells transfected with MRP7, designated HEK-MRP7-2.We report for the first time that imatinib and nilotinib reversed MRP7-mediated multidrug resistance. Our MTT assay results indicated that MRP7 expression in HEK-MRP7-2 cells was not significantly altered by incubation with 5 microM of imatinib or nilotinib for up to 72 hours. In addition, imatinib and nilotinib (1-5 microM) produced a significant concentration-dependent reversal of MRP7-mediated multidrug resistance by enhancing the sensitivity of HEK-MRP7-2 cells to paclitaxel and vincristine. Imatinib and nilotinib, at 5 microM, significantly increased the accumulation of [(3)H]-paclitaxel in HEK-MRP7-2 cells. The incubation of the HEK-MRP7-2 cells with imatinib or nilotinib (5 microM) also significantly inhibited the efflux of paclitaxel.Imatinib and nilotinib reverse MRP7-mediated paclitaxel resistance, most likely due to their inhibition of the efflux of paclitaxel via MRP7. These findings suggest that imatinib or nilotinib, in combination with other antineoplastic drugs, may be useful in the treatment of certain resistant cancers