CIMAP

Uppal Kalan, India
Uppal Kalan, India
SEARCH FILTERS
Time filter
Source Type

Nazabal V.,CNRS Chemistry Institute of Rennes | Poulain M.,CNRS Chemistry Institute of Rennes | Olivier M.,CNRS Chemistry Institute of Rennes | Pirasteh P.,CNRS Chemistry Institute of Rennes | And 6 more authors.
Journal of Fluorine Chemistry | Year: 2012

This paper present some recent developments on fluoride and oxyfluoride glasses, including glass composition, basic characterizations, technology and prospects, especially the development of rare earth doped fluoride glass channel waveguides for applications requiring integrated optical components. New Heavy Metal Fluoride Glasses compositions have been investigated namely manganese-rich fluorozirconates and strontium fluorohafnates. Numerous fluorophosphate glasses have also been obtained by the incorporation of NaPO 3 and Na 2PO 3F in the unstable MnF 2-BaF 2 and NbO 2F-BaF 2 binary glasses. NMR and electrical conductivity measurements were conducted on these glasses. Rare earth-doped channeled planar waveguides were made from the rare earth doped ZBLA (57%ZrF 4- 34%BaF 2-(5 - x)%LaF 3-4%AlF 3-x%REF 3) glass by ionic exchange using optical lithography. The spectroscopic properties of Pr 3+ doped ZBLA planar waveguides were investigated by comparison to bulk samples. For Er 3+/Ce 3+ doped ZBLA channeled waveguide low background losses (0.3 dB/cm) and net gain in excess of 1 dB/cm at 1.5 μm were obtained for incident pump powers higher than 200 mW. © 2011 Elsevier B.V. All rights reserved.


Miro S.,CEA Saclay Nuclear Research Center | Costantini J.M.,CEA Saclay Nuclear Research Center | Bardeau J.F.,University of Maine, France | Chateigner D.,CNRS Crystallography and Material Science Laboratory | And 2 more authors.
Journal of Raman Spectroscopy | Year: 2011

Raman spectroscopy was used to study the radiation damage of fluorapatite single crystals and sinters. Krypton and iodine ion irradiations were performed at high energies (∼1 MeV amu-1) for fluences ranging between 1 × 1011 and 5 × 1013 cm-2. Evolution of the symmetric stretching mode of the PO4 3- tetrahedral building blocks (strongest Raman mode observed at 965 cm-1) versus ion fluence was investigated. After irradiation, this peak decreases in intensity and a second broader peak appears at lower wavenumber. The well-resolved peak has been assigned to the crystalline phase, and the broader one to the amorphous phase. The integrated intensity ratios of these two peaks versus fluence are in good agreement with the damage fractions determined by X-ray diffraction (XRD). Fits of the amorphous fraction versus fluence show that the amorphization mechanisms is dominated by a single-impact process for iodine ions and by a double-impact process for krypton ions in the case of single crystals and sinters. For both irradiations, complete amorphization could not be obtained. The amorphous fraction saturates at a maximum value of 88% for sinters and 72% for single crystals. This is attributed to a recrystallization effect which is more important in single crystals than in sinters. For both types of samples, the crystalline peak shifts slightly to a lower wavenumber with fluence, and then shifts back to its initial value for an amorphous fraction larger than 60%. This feature is attributed to a stress relaxation, as shown in the XRD data, which is accompanied by a decrease of the crystalline peak full-width at half-maximum. © 2011 John Wiley & Sons, Ltd.


Olivier M.,CNRS Chemistry Institute of Rennes | Pirasteh P.,CNRS Chemistry Institute of Rennes | Doualan J.-L.,CIMAP | Camy P.,CIMAP | And 3 more authors.
Optical Materials | Year: 2011

Praseodymium doped Fluoride glasses were studied in order to fabricate compact solid state laser sources emitting in the visible range for lighting application and for quantum information processing. The objective of this study is focused on red, green and orange emissions. ZBLA bulk glasses (57%ZrF 4 - 34%BaF2 - (5 - x)%LaF3 - 4%AlF3 - x%PrF3) have been synthesized under dry argon atmosphere. Physicochemical and optical properties such as density, glass transition temperature, composition, transmission and refractive index have been investigated. Spectroscopic studies have been performed to optimize the rare earth doping level in order to reach the best compromise respecting a good optical quality, a highest lifetime and efficient emission intensity at 635, 605 and 520 nm. Spectroscopic measurements have been carried out on bulk samples with Pr3+ concentrations ranging from 0.1 to 3 mol% and first characterizations of ion exchanged Pr: ZBLA waveguides are reported. © 2011 Elsevier B.V. All rights reserved.


Olivier M.,CNRS Chemistry Institute of Rennes | Doualan J.-L.,CIMAP | Nazabal V.,CNRS Chemistry Institute of Rennes | Camy P.,CIMAP | Adam J.-L.,CNRS Chemistry Institute of Rennes
Journal of the Optical Society of America B: Optical Physics | Year: 2013

Visible transitions in the blue, green, and red of Pr3+ions are of interest for laser applications. A description of spectroscopic properties of this rare earth ion in Zr-Ba-La-Al (ZBLA) fluorozirconate glass matrix is presented, using an original approach. Magnetic-dipole and electric-dipole contributions are calculated, in the context of the Judd-Ofelt theory, to determine the ω (t=2, 4, 6) parameters, lifetime, and branching ratios of 3P0 emitting level. Influence of overlapping transitions and sensitized transitions are discussed, as well as the use of the standard or normalized method. Branching ratios are measured using an experimental method and compared to theoretical ones. The influence of higher energy and thermally populated 3P1 and 1I6 levels on the 3P0 lifetime is also studied. Considering this influence, a good agreement is found between theoretical and experimental 3P0 lifetimes. Finally, emission cross sections are calculated for the visible transitions, using either the reciprocity method or the Füchtbauer-Ladenburg formula, for different calculated Judd-Ofelt parameters, highlighting the ability of Pr3-doped ZBLA to be used as a laser material. © 2013 Optical Society of America.


Miro S.,CEA Saclay Nuclear Research Center | Costantini J.M.,CEA Saclay Nuclear Research Center | Haussy J.,CEA DAM Ile-de-France | Chateigner D.,CNRS Crystallography and Material Science Laboratory | Balanzat E.,CIMAP
Journal of Nuclear Materials | Year: 2012

We have studied the damage induced in fluorapatite (Ca 10(PO 4) 6F 2) sinters after 70-MeV Kr, 120 MeV I and 163-MeV Au ion irradiations at room temperature. On the basis of X-ray powder diffraction data we conclude that fluorapatite is not completely amorphized due to ion-induced recrystallization. This recrystallization of the amorphous phase is greatly enhanced for Au ions with a high electronic stopping power. We also have used the 3He(d, p) 4He nuclear reaction to study the migration of implanted 3-MeV 3He ions after swift heavy ion irradiations. The proton yield curves versus deuteron energy for irradiated samples exhibit two bumps for high fluences. These excitation curves are deconvoluted by using a computer code based on a two-diffusion equation model of helium atoms in two accumulation zones. Optimizations of the model parameters give access to the diffusion coefficients and helium depth profiles in the two zones. This yields two broad peaks in the helium depth profiles, the first one is near the end-of-range region and the second one is shifted at about half way between the surface and the first peak. This shift is interpreted as a Radiation-Enhanced Diffusion (RED) effect which is found to increase with fluence for Kr ions, and with electronic stopping power from Kr to Au ions. © 2012 Elsevier B.V. All rights reserved.


Qidwai T.,CIMAP | Khan F.,CIMAP | Sharma B.,Allahabad University | Jamal F.,Dr Rml Avadh University
American Journal of Biochemistry and Molecular Biology | Year: 2013

Falciparum malaria is a major global health problem and is third leading cause of death after HIV and tuberculosis. Although, several targets and related drugs are available, yet the parasite evolves a resistance mechanism to most of the existing drugs. Under such circumstances, it is imperative to explore antimalarial drug targets and effective drugs. Malaria is an interesting case of evolutionary selection and several host genetic factors have been selected in response to Plasmodium falciparum infection, such as hemoglobin variants, glucose-6-phosphate dehydrogenase (G6PD) and pyruvate kinase deficiency. Among these G6PD deficiency is one of the most studied host genetic factor that confer resistance to malaria in endemic and non endemic region. We have studied G6PD deficiency in Falciparum malaria patients and ethnically matched controls in non endemic region of 170 blood samples. G6PD deficiency in samples was detected by Fluorescent spot test. The samples were incubated with reaction mixture, spotted and visualized (366 nm) under ultraviolet light. Results indicate that the frequency of % G6PD deficiency is 9.2 in males and 7.14 in females in non endemic region. On the basis of our data and earlier studies, we conclude that G6PD deficiency is more prevalent in those areas where the frequency of malaria infection is high. G6PD is a selective force against the pressure of malaria in endemic regions while in non endemic regions the burden of malaria is seasonal and low which accounts for the deficiency of enzyme in conferring protection against malaria. © 2013 Academic Journals Inc.


Belabbas I.,University of Abderrahmane Mira de Béjaïa | Chen J.,University of Caen Lower Normandy | Nouet G.,CIMAP
Physica Status Solidi (C) Current Topics in Solid State Physics | Year: 2016

We have carried out computer atomistic simulations, based on Density Functional Theory, to investigate energetics and core structure of the undissociated basal screw dislocation in wurtzite GaN. Our calculations enabled us to establish the energetic hierarchy of two stable core configurations. The shuffle core configuration, which is formed by fully coordinated atoms, was demonstrated to be more energetically favorable than the glide configuration, which exhibits sp2-like hybridization. © 2015 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.


Rajeswara Rao B.R.,Central Institute of Medicinal and Aromatic Plants Research Center | Kothari S.K.,Central Institute of Medicinal and Aromatic Plants Research Center | Rajput D.K.,Central Institute of Medicinal and Aromatic Plants Research Center | Patel R.P.,CIMAP | Darokar M.P.,CIMAP
Natural Product Communications | Year: 2011

Biomass, essential oil yield, essential oil composition diversity, and antibacterial and antifungal activities of 14 selections of 4 Ocimum species [Ocimum basilicum L. (selections: T 1-T 10), O. gratissimum L. (selections: T 11-T 12), O. tenuiflorum L.f., syn. O. sanctum L. (selection: T 13) and O. kilimandscharicum Baker ex. Guerke (selection: T 14)] were investigated. O. basilicum selections T 9 (methyl chavicol: 87.0%) and T 10 {(Z)- and (E)-methyl cinnamate: 69.1%} produced higher biomass (67.8 and 56.7 t/ha) and oil (203.4 and 141.7 kg/ha) yields relative to 8 (T 1-T 8) linalool (up to 58.9%), or methyl chavicol (up to 61.8%) rich selections. O. gratissimum selection T 12 (eugenol: 84.1%, 254.6 kg/ha oil yield) was significantly superior to T 11 (62.1% eugenol and 18.4% camphor). O. tenuiflorum (T 13, methyl eugenol: 72.5%) and O. kilimandscharicum (T 14, camphor: 51.7%) produced 171.7 and 96.2 kg/ha essential oil, respectively. The essential oils exhibited broad spectrum antibacterial (against 5 Gram-positive and 7 Gram-negative bacteria) and antifungal (against 10 fungi) activities. The bacterial species Bacillus subtilis, Staphylococcus aureus, Streptococcus mutans, and Enterococcus faecalis, and the fungal species Epidermophyton floccosum, Microsporum gypseum, and Sporothrix schenckii were more sensitive to the essential oils.


Huber B.A.,CIMAP | Malot C.,CIMAP | Domaracka A.,CIMAP | Solov'yov A.V.,FIAS
Journal of Physics: Conference Series | Year: 2012

The 1st Nano-IBCT Conference entitled "Radiation Damage in Biomolecular Systems: Nanoscale Insights into Ion Beam Cancer Therapy" was held in Caen, France, in October 2011. The Meeting was organised in the framework of the COST Action MP1002 (Nano-IBCT) which was launched in December 2010 (http://fias.uni-frankfurt.de/nano-ibct). This action aims to promote the understanding of mechanisms and processes underlying the radiation damage of biomolecular systems at the molecular and nanoscopic level and to use the findings to improve the strategy of Ion Beam Cancer Therapy. In the hope of achieving this, participants from different disciplines were invited to represent the fields of physics, biology, medicine and chemistry, and also included those from industry and the operators of hadron therapy centres. Ion beam therapy offers the possibility of excellent dose localization for treatment of malignant tumours, minimizing radiation damage in normal healthy tissue, while maximizing cell killing within the tumour. Several ion beam cancer therapy clinical centres are now operating in Europe and elsewhere. However, the full potential of such therapy can only be exploited by better understanding the physical, chemical and biological mechanisms that lead to cell death under ion irradiation. Considering a range of spatio-temporal scales, the proposed action therefore aims to combine the unique experimental and theoretical expertise available within Europe to acquire greater insight at the nanoscopic and molecular level into radiation damage induced by ion impact. Success in this endeavour will be both an important scientific breakthrough and give great impetus to the practical improvement of this innovative therapeutic technique. Ion therapy potentially provides an important advance in cancer therapy and the COST action MP1002 will be very significant in ensuring Europe's leadership in this field, providing the scientific background, required data and mechanistic insight which are indispensable for the optimization of this new therapy. The conference gathered 115 participants originating from 28 countries and addressed a large number of highly relevant aspects concerning ion propagation in biological matter, the production of secondary particles along the ion tracks as electrons, holes and radicals, and their propagation in the biomolecular medium. In particular, the attack of DNA molecules and proteins by electrons and free radicals, the relative importance of direct and indirect damage processes as well as the role of the environment were discussed. Not only were fundamental mechanisms and processes elucidated, but radiobiological scale effects, multi-scale approaches and recent advances in the theoretical description of the underlying complex phenomena were also presented. Aspects linked to the energy deposition (LET), the characteristics of the Bragg peak and new techniques of dosimetry and radiolysis were highlighted. Furthermore, methods for increasing the therapy efficiency by using radio sensitizers and the state-of-the-art of defining precise patient treatment plans, identifying the clinical benefits of this type of therapy, were also addressed. We would like to thank all participants for the lively exchange of ideas and results, thus making this conference a very fruitful event. Furthermore, we appreciate the financial support of the sponsors of this conference, in particular of the COST Action MP1002 financed by ESF. We would also like to express our thanks to all authors of these proceedings, as well as to the reviewers for their time, efforts and recommendations made during the preparation of this volume. Finally, many thanks to U G Huber for a careful proof-read of this manuscript. We look forward to the 2nd Nano-IBCT Conference, which will be held in spring 2013. Caen, 15 March 2012 Bernd A Huber, Christiane Malot, Alicja Domaracka and Andrey V Solov'yov The Editors The PDF also contains details of the Conference Committees and Sponsors and a list of participants.


Belabbas I.,University of Abderrahmane Mira de Béjaïa | Chen J.,University of Caen Lower Normandy | Nouet G.,CIMAP
Computational Materials Science | Year: 2014

We have carried out a complete and consistent study on core configurations of the three types of threading dislocations in wurtzite GaN. Their atomic and local electronic structures were analyzed and systematically compared, at the level of Density Functional Theory. Screw and mixed threading dislocations were found to introduce both deep and shallow gap states, while most of core configurations of the edge dislocation introduce only shallow states. We demonstrated that the existence of an extended one-dimensional metallization, associated with unoccupied gap states, is a specific feature of threading screw dislocations. The extended metallization along with the high dispersion of the energy gap states are at the origin of the experimentally observed high electric conduction along threading screw dislocations in GaN. The presence of nitrogen vacancies in the core of screw dislocations is predicted to enhance their electric conduction. © 2014 Elsevier B.V. All rights reserved.

Loading CIMAP collaborators
Loading CIMAP collaborators