Application of extraction chromatographic techniques for separation and purification of emerging radiometals ^44/47Sc and ^64/67Cu

Vyas, Chirag K.,Park, Jeong Hoon,Yang, Seung Dae Korean Society of Radiopharmaceuticals and Molecul 2016 Journal of radiopharmaceuticals and molecular prob Vol.2 No.2

Considerably increasing interest in using the theranostic isotopes/ isotope pairs of radiometals like $^{44/47}Sc$ and $^{64/67}Cu$ for diagnosis and/or therapeutic applications in the nuclear medicine procedures necessitates its reliable production and supply. Separation and purification of no-carrier-added (NCA) isotopes from macro quantitates of the irradiated target matrix along with other impurities is a cardinal procedure amongst several other steps involved in its production. Multitudinous methods including but not limited to liquid-liquid (solvent) extraction, extraction chromatography (EXC), ion exchange, electrodeposition and sublimation are routinely applied either solitarily or in combination for the separation and purification of radioisotopes depending on their production routes, radioisotope of interest and impurities involved. However, application of EXC though has shown promises towards the numerous separation techniques have not received much attention as far as its application prospects in the field of nuclear medicine are concerned. Advances in the recent past for application of the EXC resins in separation and purification of the several medically important radioisotopes at ultra-high purity have shown promising behavior with respect to their operation simplicity, acidic and radiolytic stability, separation efficiencies and speedy procedures with the enhanced and excellent extraction abilities. In this mini review we will be talking about the recent developments in the application and the use of EXC techniques for the separation and purification of $^{44/47}Sc$ and $^{64/67}Cu$ for medical applications. Furthermore, we will also discuss the scientific and practical aspects of EXC in the view of separation of the NCA trace amount of radionuclides.

A novel approach for preferential recovery of Sr from (Sr, Th)O₂

Vyas, C.K.,Joshirao, P.M.,Shukla, R.,Tyagi, A.K.,Manchanda, V.K. Elsevier Scientific Pub. Co 2012 Journal of hazardous materials Vol.241 No.-

Quantitative leaching of Sr from homogeneous and calcined (Th,Sr) O<SUB>2</SUB> in dilute perchloric acid medium suggests the possibility of reducing the hazardousness of discharged nuclear fuel by separation of <SUP>90</SUP>Sr, a prominent fission product at dissolution stage itself rather than the conventional approach of its recovery from high level nuclear waste. Apart from mitigating the radiotoxicity of the nuclear waste, recovered <SUP>90</SUP>Sr can be employed as a compact heat source and as parent radionuclide for <SUP>90</SUP>Y (used in therapy radiopharmaceuticals), provided it can be made available at desired high purity. Leaching behavior of few other fission products was also investigated to quantify their contamination in leached Sr. Feasibility of employing extraction chromatography using Sr selective resin was explored in perchloric acid medium. In this context, the distribution coefficients of <SUP>85</SUP>Sr(II), Th (IV), Zr(IV), Y(III), Pd(II) as well as <SUP>152</SUP>Eu(III) and <SUP>137</SUP>Cs (I) were determined under varying nitric acid/perchloric acid concentration and under varying loading conditions of metal ions. Perchloric acid medium appears better than nitric acid medium for preferential leaching of Sr from (Th,Sr)O<SUB>2</SUB> as well as for uptake of Sr by Sr selective chromatographic resin.

남아시아 여성 네트워크

Vyas, Anju 淑明女子大學校 亞細亞女性問題硏究所 2001 아시아여성연구 Vol.40 No.-

Radiochemical separation of ⁸⁹Zr: a promising radiolabel for immuno-PET

Vyas, Chirag K.,Park, Jeong Hoon,Yang, Seung Dae Korean Society of Radiopharmaceuticals and Molecul 2016 Journal of radiopharmaceuticals and molecular prob Vol.2 No.1

$^{89}Zr$ with the favorable nuclear decay kinetics and chemical properties is an appealing radiometal for its application in immuno-PET using radiolabeled monoclonal antibodies. Rising demand of ultrahigh purity and high-specific activity $^{89}Zr$ has propelled the radiochemist worldwide to develop an overall efficacious method for its promising separation from the target matrix $^{89}Y$. The requirement of elevated radiochemical purity (${\geq}$ 99.99%) has accelerated the efforts since last two decades to achieve higher decontamination and separation factors of carrier free $^{89}Zr$ over $^{89}Y$ using several suitable separation techniques. However, each of the technique has its own pros and cons which prior to its actual medical application needs to be optimized and thoroughly scrutinized to avoid further complications during radiolabelling of the pharmaceuticals. In this short review article we will specifically consider as well focus on the historical development and the recent advances on the radiochemical separation of $^{89}Zr$ from $^{89}Y$ which will be helpful for the separation scientist involved in this area to understand the existing available means and plan the strategy to investigate and develop the novel techniques to overcome the problems involved in the present methods.

Chitosan-TiO₂ composite: A potential ⁶⁸Ge/⁶⁸Ga generator column material

Vyas, Chirag K.,Lee, Jun Young,Hur, Min Goo,Yang, Seung Dae,Kong, Young Bae,Lee, Eun Je,Park, Jeong Hoon Elsevier 2019 Applied radiation and isotopes Vol.149 No.-

<P><B>Abstract</B></P> <P>A durable and ready to use <SUP>68</SUP>Ge-<SUP>68</SUP>Ga generator column material is required for its routine use in radiopharmaceutical procedures. The present work comprises preliminary studies for development and evaluation of chitosan-TiO<SUB>2</SUB> based microsphere (C-TOM) composite towards its competence as a column material. The batch uptake studies showed higher distribution coefficients for <SUP>68</SUP>Ge vis-à-vis <SUP>68</SUP>Ga in the complete concentration range of HCl examined (0.01–1 mol.L<SUP>−1</SUP>). Furthermore, C-TOM showed enduring physical and chemical stability in 0.01 mol.L<SUP>−1</SUP> HCl with persistent <SUP>68</SUP>Ga elution profiles (>95%) and negligible <SUP>68</SUP>Ge breakthrough (2 × 10<SUP>−4</SUP>%) for the preliminary evaluation period of ∼2 months. Overall, the studies indicated that, <SUP>68</SUP>Ga with high radionuclidic purity (≥99.99%) can be eluted routinely in a small volume (∼1.5 mL) of 0.01 mol.L<SUP>−1</SUP> HCl proving its potentials as a novel solid phase extractant for <SUP>68</SUP>Ge/<SUP>68</SUP>Ge generator system.</P> <P><B>Highlights</B></P> <P> <UL> <LI> Novel approach towards synthesis of chitosan-TiO<SUB>2</SUB> microsphere (C-TOM). </LI> <LI> Superlative physical and chemical stability of C-TOM in 0.01 M HCl. </LI> <LI> Separation of <SUP>68</SUP>Ga from <SUP>68</SUP>Ge with high radionuclidic purity. </LI> <LI> Consistent <SUP>68</SUP>Ga elution profile with low <SUP>68</SUP>Ge breakthrough. </LI> <LI> Possible application of C-TOM as a potential <SUP>68</SUP>Ge/<SUP>68</SUP>Ga generator material. </LI> </UL> </P> <P><B>Graphical abstract</B></P> <P>[DISPLAY OMISSION]</P>

Phosphonates as alternative to tributyl phosphate for the separation of actinides from fission products

Vyas, Chirag K.,Brahmmananda Rao, C. V. S.,Jayalakshmi, S.,Joshirao, Pranav M.,Manchanda, Vijay K. Walter de Gruyter GmbH 2015 RADIOCHIMICA ACTA Vol.103 No.4

<B>Abstract</B><P>The present work investigates the role of increase in the basicity of organophosphorus extractant (dialkylalkyl phosphonates) on the uptake of actinides and fission products vis-à-vis tributyl phosphate (TBP), currently employed as a universal extractant. Two dialkylalkyl phosphonates viz. dibutylpropyl phosphonate (DBPrP) and dibutylpentyl phosphonate (DBPeP) were synthesized, characterized and evaluated for their solvent extraction behavior towards U(VI), Th(IV), Eu(III) and Tc(VII) in nitric acid medium ranging from 0.01–6 M. It was observed that increasing the basicity of the phosphoryl oxygen enhanced the uptake of the actinides and the distribution coefficient values were significantly larger as compared to TBP. The limiting organic concentration (LOC) value was estimated for Th(IV) for these extractants and compared with the TBP system. The separation factors of actinides with phosphonates over Tc(VII) are distinctly better than that with TBP.</P>

Recovery and purification of Sr(II) in perchloric acid medium

Vyas, Chirag K.,Joshirao, Pranav M.,Tyagi, Avesh K.,Manchanda, Vijay K. Springer-Verlag 2013 Journal of radioanalytical and nuclear chemistry Vol.295 No.3

A quasi-ballistic drain current, charge and capacitance model with positional carrier scattering dependency valid for symmetric DG MOSFETs in nanoscale regime

Vyas R. Murnal,C. Vijaya 나노기술연구협의회 2019 Nano Convergence Vol.6 No.19

This paper presents a physically valid quasi-ballistic drain current model applicable for nanoscale symmetric Double Gate (SDG) MOSFETs. The proposed drain current model includes both diffusive and ballistic transport phenomena. The model considers the important positional carrier scattering dependency effect near the source region described in terms of transmission and reflection co-efficients related to the scattering theory. The significance of carrier transport near the bottleneck source region is illustrated where the carriers diffuse into the channel at a relatively lower velocity before accelerating ballistically. The results obtained demonstrate carrier scattering dependency at the critical layer defined near the low field source region on the drain current characteristics. The proposed model partly evolves from Natori’s ballistic bulk MOSFET model that is modified accordingly to be valid for a symmetric Double Gate MOSFET in the nanoscale regime. Carrier degeneracy and Fermi–Dirac statistics are included in the work so as to justify the complete physicality of the model. The model is further extended and is shown to be continuous in terms of terminal charges and capacitances in all regions of operation. A comparative analysis is also done between the proposed quasi-ballistic model and a hypothetical complete ballistic device.

A Note on Electronic Networking

Anju Vyas Asian pacific women's information network center 1999 APWIN Vol.1 No.-

Efficient routing in multicast mesh by using forwarding nodes and weighted cost function

( Kapila Vyas ),( Ajay Khuteta ),( Amit Chaturvedi ) 한국인터넷정보학회 2019 KSII Transactions on Internet and Information Syst Vol.13 No.12

Multicast Mesh based Mobile Ad-hoc NETworks (MANETs) provide efficient data transmission in energy restraint areas without a fixed infrastructure. In this paper, the authors present an improved version of protocol SLIMMER developed by them earlier, and name it SLIMMER-SN. Most mesh-based protocols suffer from redundancy; however, the proposed protocol controls redundancy through the concept of forwarding nodes. The proposed protocol uses remaining energy of a node to decide its energy efficiency. For measuring stability, a new metric called Stability of Node (SN) has been introduced which depends on transmission range, node density and node velocity. For data transfer, a weighted cost function selects the most energy efficient nodes / most stable nodes or a weighted combination of both. This makes the node selection criteria more dynamic. The protocol works in two steps: (1) calculating SN and (2) using SN value in the weighted cost function for selection of nodes. The study compared the proposed protocol, with other mesh-based protocols PUMA and SLIMMER, based on packet delivery ratio (PDR), throughput, end-to-end delay and average energy consumption under different simulation conditions. Results clearly demonstrate that SLIMMER-SN outperformed both PUMA and SLIMMER.