2,212 research outputs found
Functionalized organoboron polymers and supramolecular structures of pentafluorophenylcopper:
No full textThis thesis is divided into four different parts. The first three chapters discuss the development of synthetic routes to new boron containing polymers for their potential use as supported borane reagents (Ch. 1.) and photoluminescent materials (Ch. 2. and Ch. 3.). The last chapter (Ch. 4.) discusses the formation of supramolecular structures of pentafluorophenylcopper upon complexation with pyridine nucleophiles and electron rich aromatic π-systems. The individual research projects are briefly summarized in the following.
Ch. 1. The functionalization of synthetic polymers with organoborane moieties has been extensively studied for applications as supported catalysts, sensors, stimuli responsive polymers, flame retardants, preceramic materials, and as intermediates for the preparation of other functional organic polymers. A polystyrene derivative in which the para-positions of the phenyl rings are selectively functionalized with BH2 moieties (PS-BH2) has been prepared from poly(4-trimethylsilyl styrene). The polymer was successfully isolated in the form of its polymeric acid-base complexes PS-BH2•D (D = tBuPy, PPh2Me). The selective and nearly quantitative placement of the BH2 functionalities was confirmed by multinuclear NMR spectroscopy and IR spectroscopy. Their thermal properties were studied by differential scanning calorimetry and thermogravimetric analysis.
Ch. 2. Boron containing water soluble polymers could find a variety of applications as polyelectrolytes, for anion recognition in aqueous media and in various biological fields. We have previously shown that polystyrene based side chain functionalized triarylborane polymers can be employed as sensors for the recognition of cyanide and fluoride in organic media. Here we have persued the synthesis of polystyrene that bears Lewis acidic boron centers and dimethylamino-functionalized mesityl groups in the side chain. Attachment of these mesityl groups to the boron center has been realized by the use of boron-silicon exchange, followed by the replacement of the bromine on boron by suitable Grignard reagents. The polymers and model compounds show interesting photophysical properties and have the potential to be applied for anion sensing in aqueous media.
Ch. 3. Main chain organoboron conjugated polymers have been established as an important class of materials due to their unusual optoelectronic properties. This behavior arises as a result of overlap between the empty p-orbital on boron and the conjugated π-system. The hydroboration polymerization and in situ Grignard synthesis have been employed for the preparation of such polymers. Here we have synthesized boron-functionalized distyryl monomers, which can be polymerized via ADMET polymerization. All monomers and ADMET products were characterized by multinuclear NMR spectroscopy. Moderate to high molecular weights in the range of 5,000-10,000 have been obtained. Photophysical data show that polymer emits in the blue-green region.
Ch. 4. Treatment of organocopper species with strongly coordinating ligands is known to lead to break-down of the aggregated structures. One such example is the 1:1 complex of pentafluorophenylcopper with pyridine. The monomeric pyridine adduct shows an intriguing supramolecular structure governed by cuprophilic interactions. This complex was also found to display strong blue luminescence in the solid state at room temperature. To further examine the structural and photophysical properties of this new class of complexes, the pentafluorophenylcopper tetramer was treated with different substituted pyridine ligands. The coordination of these ligands to copper was confirmed by 1H, 19F, 13C NMR spectroscopy, x-ray crystallography and elemental analysis.
Treatment of pentafluorophenylcopper with π-bases such as bithiophene, naphthalene anthracene or pyrene lead to novel luminescent supramolecular structures that feature the intact organocopper aggregate as the building block. Formation of bis-adducts with two equivalents of arenes was realized and the formation of sandwich-like structures of the intact tetramer and the corresponding arene was observed via single crystal x-ray analyses. Interestingly, the 1:1 complexes form extended binary stacks in the solid state, where the intact tetramer alternates with the arene.Ph.D.Includes bibliographical referencesby Ami P. Dosh
Correspondence related to article "Statins for primary prevention: what is the regulator's role?" by Jefferson et al. 2020
No full textPDFs of emails between the author team (Jefferson, Demasi, and Doshi) and EU national competent authorities, as described in their article Jefferson et al. "Statins for primary prevention: what is the regulator’s role?" https://doi.org/10.1136/bmjebm-2019-11132
In conversation with… Balkrishna Doshi
No full textIndian architect Balkrishna Doshi, 2018 Pritzker Prize, has recently turned 92, remaining in full and enthusiastic dedication to his architectural vocation and his family. José María Lozano Velasco, UPV architectural project Professor, had the opportunity to meet him at Sangath– his studio in Ahmedabad– last August, to share common concerns and learn from this architectural master, though he eschews being given such titles. Right when the second opportunity to get to know his work in detail had just concluded –this time at the Architekmuseum der TUM, part of Munich’s Pinakothek der Moderne art museum– through the splendid exhibition called Architecture for the people produced by the VITRA museum of Weil am Rhein, the author’s first-hand reflections in his own voice are enlightening for better comprehension of his work.
It is well-known the invaluable collaboration that Doshi maintained with the great master Le Corbusier in the conception and execution of Chandigarh, in addition to the essential participation of our architect on the Campus of the Indian Institute of Management in Ahmedabad of Louis Khan. It is also interesting to study the influence of both his first works as well as to observe his evolution towards the magic of Amdavad ni Gufa or his deep concern for low-cost housing, which in the district of Aranya, Indore, becomes a reality.
We cannot preclude the studies of colleagues and friends such as William Curtis or Kenneth Frampton who, with more authority than us, have addressed the matter.
This article is the result of the compiled knowledge and consideration given to the large part of the work plus the enriching conversation with its author. However, its approach is different as we have intended to investigate those reasons that made the first Doshi period be known as “Tradition and Modernity”, using the most magical (or mythical, as he likes to refer to them) and main tool to transmit them: the drawing (and the coloured drawing).
This article includes literal or adapted transcripts from some passages of the meeting and have been contextualized for more better readability
Effable Nature in Unheard Stories : Tishani Doshi\u27s Poetics of Discovery
No full textThis article aims to study the multiple nature metaphors used in Tishani Doshi’s poetry to convey messages of understanding and epiphany. Born in 1975 in Madras (now Chennai), Doshi is an Indian author and academic who has gained indisputable reputation as a novelist and poet, with other cultural and artistic interests like dancing and writing journal articles. She is especially devoted to narrating the urges of contemporary human existence, and to defending class, gender, and racial rights violated by capitalist patriarchal anthropocentrism, all while embracing the aesthetic beauty of artistic creation as a weapon to change the world. Therefore, in her writings, Doshi makes use of subtle environmental elements (with an emphasis on animal and vegetal metaphors) to be able to speak about the ineffability of being, without discarding ideological urges and liminal tensions. Thus, Doshi pushes to the limit the essence of poetry in a self-quest to discover essential truths and cultural nuances. Hers is therefore a poetics of revelations, darkened by the oxide patina of everyday conventions and stereotypes, that needs to be polished and moulded in the hands of bards
Digital image processing and its application to compton gamma ray camera
No full textThe use of gamma ray imaging devices in Nuclear Medicine has been well i established` in the past two decades. The development of the devices in the past has illustrated that their performance cannot be improved beyond a certain limit without sacrificing efficiency considerably. Recently, a new device, Compton gamma ray camera, has been proposed which would overcome the basic limitation of the existing devices by removing the collimator used for focussing the gamma rays. Preliminary investigations have shown that the Compton camera would have high resolution and efficiency.In this thesis a detailed investigation of the Compton camera images is presented and the application of digital image processing techniques to the camera images is considered.'A priori` image processing techniques have been used to define contributions in the image plane and estimation techniques are used to form images. A detailed comparison of the image formation methods based on the results obtained by a Monte Carlo simulation of -the camera is presented. A mathematical model of the image formation process is derived for the camera and shown: to be similar to that -for -many linear imaging devices. This fact is used' in developing 'a posteriori' image processing techniques which can be applied to any images formed by linear imagingdevices_ The carers images' are used as an example to illustrate theImage restoration filters are derived by using a novel concept of roll-off filters. It is shown that it is only necessary to design a low-pass filter which satisfies certain resolution and noise requirements. Quantitative resolution measures like the second moment of the filter response and integral error.. are used to derive roll-off filters. Various exact and approximate solutions satisfying the constraints are derived and their performance compared with the minimum mean squared filters and other commonly used filters. It is shown that the new filters allow greater flexibility in controlling the resolution and the output noise. The problem of implementing and realizing the filters non-recursively using two-dimensional data windows is considered. New data windows are proposed and their properties compared with those of the commonly used windows. Results of applying the filters before and after, windowing are evaluated in detail.performance of restoration filters.</p
The continued silencing of Gayatri Spivak’s subaltern: A critique of the elite nexus of NGOs, academia and corporations
No full textBy drawing from Gayatri Spivak’s works on the subaltern, we argue that marginalized people are still suffering from silencing. Silencing occurs due to the powerful coalition of elite NGOs, academia, and corporations that perpetuate neocolonial mechanisms in developing countries. This condition pushes the subaltern out of the public sphere and deprives them of opportunities to live a dignified life. Moreover, we posit that the current Western-centric neocolonial policies and practices utilized by these elite actors are worsening the pre-existing socio-economic inequalities of the subaltern. Henceforth, we must scrutinize and challenge the dominance of the elite nexuses so that violations of the subaltern’s rights and dignities end, and their voices are recognized in policies and practices that currently affect them negatively. However, to start the decolonization process, the necessary perspectives should be adopted and the groundworks put in place by elite actors, rather than elites waiting for the subaltern to resist neocolonialization all the time. By changing the old habits of neocolonialization, elite actors must genuinely work with the subaltern, on the terms of the subaltern, and with the consent of the subaltern, to create conditions and possibilities for freedom for oppressed and marginalized people around the globe
Supplementary Tables -Supplemental material for Utilization and in-hospital outcomes associated with atherectomy in the treatment of peripheral vascular disease: An observational analysis from the National Inpatient Sample
No full textSupplemental material, Supplementary Tables for Utilization and in-hospital outcomes associated with atherectomy in the treatment of peripheral vascular disease: An observational analysis from the National Inpatient Sample by Rajkumar Doshi, Evan Shlofmitz and Perwaiz Meraj in Vascular</p
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