52 research outputs found
Datasets of Chatterjee et al., ACS Appl. Electron. Mater. 4, 5317 (2022), "Impact of polymer-assisted epitaxial graphene growth on various types of SiC substrates"
No full text<p>Compilation of the datasets used to generate the figures in the following journal publication:</p>
<p>"Impact of polymer-assisted epitaxial graphene growth on various types of SiC substrates"</p>
<p>by Atasi Chatterjee, Mattias Kruskopf, Stefan Wundrack, Peter Hinze, Klaus Pierz, Rainer Stosch, and Hansjoerg Scherer,</p>
<p>ACS Appl. Electron. Mater. 4, 5317 (2022),</p>
<p>DOI: 10.1021/acsaelm.2c00989.</p>This work was supported in part by the Joint Research Project GIQS (18SIB07). This project received funding from the European Metrology programme for Innovation and Research (EMPIR) co-financed by the Participating States and from the European Unions' Horizon 2020 research and innovation programme. Funder ID: 10.13039/100014132, Grant no: 18SIB07 GIQS
Datasets of Yin et al., Adv. Physics Res. 2022
No full textCompilation of the datasets used to generate the figures in the following journal publication:
"Tailoring Permanent Charge Carrier Densities in Epitaxial Graphene on SiC by Functionalization with F4-TCNQ"
by Yefei Yin, Atasi Chatterjee, Davood Momeni, Mattias Kruskopf, Martin Götz, Stefan Wundrack, Frank Hohls, Klaus Pierz, and Hans W. Schumacher,
Adv. Physics Res. 2022,
DOI: 10.1002/apxr.202200015This work was supported in part by the Joint Research Project GIQS (18SIB07). This project received funding from the European Metrology programme for Innovation and Research (EMPIR) co-financed by the Participating States and from the European Unions' Horizon 2020 research and innovation programme. Funder ID: 10.13039/100014132, Grant no: 18SIB07 GIQS
Formation and modification of Ag atomic point contacts
No full textThere is the hope that Molecular electronics would enable the fabrication of ultra-small sized functional molecular circuits. However, since this is currently not easily possible using the conventional Si technology, this branch of nano-technology requires significant understanding of the various physical processes that take place on the atomic scale which are governed by quantum mechanical principles. Quantum mechanics introduces uncertainties in the behaviour and, therefore, the investigation of atomic and molecular junctions is not very straightforward. Many approaches have been developed to fabricate such junctions in a reliable
way, but nevertheless, there still exists a lack of reproducibility amongst measurements. Similarly, along with the increasing miniaturisation demands, not only smaller circuits are desired, but their efficiency and performance also suffers from the increased current densities and local heating. Therefore, while investigating atomic/molecular junctions the approach within this thesis was two-fold: (a) better understanding of the mechanism of electromigration
(EM) within nano-structures and (b) fabrication of reproducible atomic point contacts using EM in ultra-thin Ag structures.
In this thesis, an unique set-up consisting of a 4-tip SEM/STM UHV chamber was used to perform EM measurements on nano-structures. Multiple Ag nano-structures were fabricated on a Si substrate using a two-step lithography process and presence of the in-situ SEM enabled easy navigation from one nano-structure to the other. The tips were used for contacting the structures and a feedback controlled electromigration (FCE) mechanism was used to control the voltage between them during the EM process. Significant effort was devoted on the development and integration of the EM set-up within the 4-tip SEM/STM UHV chamber in
order to establish an in-situ fabrication and characterisation technique of atomic/molecular junctions.
Ag bow-tie shaped structures with a centre width between 100 - 200nm were investigated at lN2 temperatures and the in-situ characterisation of the structures was performed before and after EM. Ultra-thin Ag structures deposited on Si exhibited a granular nature with an average grain size of Ag grains between 30 - 40 nm. Therefore, the smallest constriction consisted of more than one grain, which when subjected to EM, led to a complex structure formation. It was observed from the conductance curves that even though these structures depict conductance quantisation while thinning during EM, they could not be re-used for
repeatable opening and closing of atomic junctions. This observation led to the conclusion that in order to fabricate reproducible atomic junctions, structure widths below the size of one single grain must be used. To reduce the centre widths below 30 nm, focused ion beam (FIB) patterning was employed, to reliably shape the centre constriction to widths below 20 nm. This extra nano-structuring step allowed precise in-situ local control on the morphology of the structures, which served as a step forward in defining the geometry of the atomic junctions and also improved the reproducibility of the EM technique. EM on these structures produced very well defined conductance plateaus which could be re-opened multiple times, suggesting that atomically precise metallic point contacts were generated. Hence, this dissertation addresses one of the very complex issues in molecular electronics i.e.
reproducible fabrication of atomic contacts.
Furthermore, CO molecule(s) were adsorbed on these point contacts. Being one of the very simple asymmetric molecules, CO served as a good candidate to understand the role of chemisorption on such junctions. Time-resolved current measurements showed bi-stabilities that were dependent on bias voltages. Conductance could be reproducibly changed between two states just by changing the operating voltage suggesting even the simplest molecular junction possesses the capability to function as switches, or memory devices. In the present
case, the exact mechanism behind this behaviour has not been completely comprehended, but few possibilities have been outlined. Hence, this thesis also provides intriguing results on electrical properties of chemisorbed Ag atomic contacts
Computer Game-Based Learning and Pedagogical Contexts: Initial Findings from a Field Study
No full textEF24, a Curcumin Analogue Inhibits the Migration and Invasion of Highly Metastatic Breast Cancer Cells
No full textIn 2011, American Cancer Society reported that about 230,000 women were diagnosed with breast cancer in the US, and among them 40,000 died. This disease targets women of all ages and races, and although survival rates have increased recently, it is still a huge problem that influences the lives of millions of people. In case of non-metastatic breast cancers, patients are usually responsive to various treatments, but in patients with metastatic breast cancer the current medications are not fully effective. The goal of the current study is to evaluate the efficacy of a newly synthesized anti-cancer agent, EF-24, on metastatic breast cancer cells. To accomplish this, we have selected two breast cancer cell lines e.g., MDA-MB-231 and LM 2-4. While MDA-MB-231 cells were derived from patient with highly metastatic breast cancer, LM 2-4 cells were lung cancer cells metastasized by MDA-MB-231. The effectiveness of EF 24 was compared with various anti-carcinogens such as eicosapantaenoic acid (EPA found in fish oil), cisplatin (a common chemotherapeutic drug), ICI (fulvestrant, an estrogen receptor antagonist) MBCD (methyl-b-cyclodestrin, an inhibitor that binds to cholesterol), AACOCF3 (arachidonoyl-trifluoroketone, a cytoplasmic phospholipase A2 inhibitor) and NS-398 (anti-inflammatory drug). It was observed that among all the inhibitors, EF24 was most effective in arresting the migration and invasion of MDA-MB-231 and LM 2-4 with an inhibition of about ~65% for MDA-MB-231 and ~85% for LM 2-4. These results suggest that EF-24 should be considered as a new potential drug to treat patients with aggressive breast cancers
ECOTHEOLOGY ISLAM: TEOLOGI KONSTRUKTIF ATASI KRISIS LINGKUNGAN
No full textAbstract: The earth inhabited by human now is facing global environmental crisis. To respond to and tackle the crisis, a new awareness to explore the principles of religion has emerged today, which was then called ecotheology, an integral environmental insight based on ethical-theological as well as ethical-anthropological dimensions. This paper is aimed at, on the one hand, exposing principles of Islamic ecotheology that are able to be guiding principles in managing the nature, and on the other hand, comparing them with the principles of modern environmental ethics of the environmentalist/ eco-thinkers. The author argues that there are three principles of Islamic ecotheology that are relevant as the basis of ethical management of nature now days, namely the principle of taw╪id (unity of all creation), the principle of āmanah-khalīfah (trustworthiness-moral leadership), and ākhirah (responsibility).Abstrak: Bumi yang dihuni manusia sekarang ini tengah dilanda krisis lingkungan yang besifat global. Untuk merespons krisis itu, dewasa ini telah muncul kesadaran baru dalam menanggulangi krisis itu dengan menggali prinsip-prinsip agama, yang kemudian disebut ecotheology, yaitu wawasan lingkungan yang integral dan berdimensi etis-theologis dan etis-antropologis. Tulisan ini bertujuan untuk, di satu sisi, memapar prinsip-prinsip ecotheology Islam yang dapat dijadikan sebagai guiding principles dalam pengelolaan alam, dan di sisi lain, mengomparasikan prinsip-prinsip itu dengan etika lingkungan modern dari para environmentalist/eco-thinker. Penulis berpendapat bahwa ada tiga prinsip ecotheologi Islam yang relevan sebagai basis etis pengelolaan alam dewasa ini, yaitu prinsip taw╪īd (kesatuan seluruh makhluk), prinsip amānah-khalīfah (kejujuran-kepemimpinan), dan ākhirah (tanggung jawab). </p
High repetition rate gain-switched 1.94 mu m fiber laser pumped by 1.56 mu m dissipative soliton resonance fiber laser
No full textA dissipative soliton resonance (DSR) mode-locked Er:Yb fiber laser has been used to pump a thulium fiber laser to generate gain-switched pulses at high repetition rates. Here 412 ns long DSR pulses with a center wavelength of around 1.56 mu m at a repetition rate of 410 kHz have been fed to a thulium fiber laser, resulting in generation of gain-switched pulses at 1.94 mu m. The minimum pulse width achieved was 256 ns with an average power of 4.6 W at 66% slope efficiency. Gain-switched pulses at 520 kHz and 750 kHz were generated through changing the pump pulse repetition rate by modifying the DSR cavity. To the best of our knowledge, this is the first demonstration of a high repetition rate gain-switched thulium fiber laser pumped by a DSR mode-locked fiber laser. As DSR pulses can be generated with high seed average power and energy independent of the operating wavelength regime as well as mode-locking technique, the proposed method can be applied to generate gain-switched pulses at high repetition rates and various wavelengths without the need of any optical or electrical modulators. (C) 2017 Optical Society of America
Diverse mode of operation of an all-normal-dispersion mode-locked fiber laser employing two nonlinear loop mirrors
No full textPhosphonoxins III: Synthesis of α-Aminophosphonate Analogs of Antifungal Polyoxins with Anti-<i>Giardia</i> Activity
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