Search

The efficient dispersion of carbon nanotubes in a given polymer matrix remains an open challenge. Unless addressed, the full potential of carbon nanotubes towards influencing electronic properties of a composite is far from being well understood. Although several reports are available in an open forum that addresses this challenge using various strategies, a mechanistic insight is still lacking. Herein, we have conjugated different electron-rich species with multi-walled carbon nanotubes. We systematically studied their properties by fluorescence lifetime measurements using time-correlated single-photon counting and by density functional theory. Although such conjugations vary with the electronic structure of the electron-rich species, theoretical and computational modeling sheds more light on the actual orientation of such conjugation. Taken together, the fluorescence lifetime and the type of conjugation allowed us to gain mechanistic insight into this conjugation, which further influenced several key properties of the composites. Herein, we attempted to understand these factors influencing the electrical conductivity, and electromagnetic (EM) shielding efficiency in the composite. With the addition of aminoanthracene, which established a T-shaped conjugation with multiwall carbon nanotubes (2 wt%), a remarkable -25 dB shielding effectiveness was achieved with 87% absorption for a shielding material of just 1 mm thick. The actual shielding mechanism, effect of the electronic structure, and the co-relation with the fluorescence lifetime opens new avenues in designing composite-based EM shielding materials.

Lightweight and easy to fabricate and integrate microwave absorbers are in great demand both in commercial space as well as in stealth applications given the surge in the use of wireless communication. In the past decade, research on designing polymer nanocomposite based microwave absorbers containing magnetic and conducting nanoparticles has swollen significantly; however, a clear mechanistic insight on the usage of semiconductors is far away. Herein, the potential of ``wool-ball''-like hollow semiconductor (CuS, copper sulfide) structures is explored for microwave absorption, and a mechanistic insight is proposed based on the experimental evidence. The facile synthesis approach, unique morphological structure, and optical properties make this semiconductor (CuS) quite attractive for the proposed application. In addition, the systematic analysis reveals that this material has the potential to replace the conventional conducting or magnetic nanoparticles, due to its favorable skin depth and microwave attenuation capability through dielectric heating and polarization loss. Polyvinylidene fluoride (PVDF) composites containing hollow CuS structures exhibited shielding effectiveness of 44 dB at 18 GHz, of which 86% of the incident radiation was attenuated by absorption. Further, thermal dissipation ability of this composite and its correlation with real-time microwave exposure through time-temperature response have offered new avenues in the design of microwave absorbers.

The manuscript deals with the sorption of Am(III) and Eu(III) from pH medium using chitosan functionalized with dendrimer like polyamidoamine (PAMAM) polymers up to third generation. The PAMAM polymers were introduced into chitosan by two step processes and were characterized by various instrumental techniques like FTIR, XRD, TG-DTA. The sorption process was highly pH dependent for both Am(III) and Eu(III) with increasing trend for higher pH of the solution. Kinetics of equilibration was found to be fast with equilibrium attained in 10 min for both the metal ions. Pseudo 2nd order kinetics mechanism was found to be followed for both Am(III) and Eu(III). The sorption process of Eu(III) was found to fit the Langmuir isotherm model with maximum sorption capacity of 6.01 mg/g. There was no effect on the generation of PAMAM Dendron on the efficiency, kinetics or sorption capacity for Am(III) as well as Eu(III). The synthesized different generation of PAMAM functionalized chitosan is a promising material for removal of actinides and lanthanides from waste water solution.

An increase in news articles on various communication platforms or social media has resulted in higher possibilities of spread of non-factual or fake information. The overall volume and veracity of news makes it even more impossible to manually fact check each data and label them as true or false. Under such circumstances, we propose a belief index generator model that quantifies the belief to be associated with any random information making use of text analytic proximity measures. In the initial feature engineering, we use a modified TF-IDF algorithm. Post generation of word embeddings, various distance measures have been proposed and compared as possible belief scores. The analysis has been carried out using 50K research articles on CoVid-19 to validate truths and The CoronaVirusFacts/DatosCoronaVirus Alliance Database to validate falsities in random CoVid related information.

An increase in the scientific literature related to COVID19 makes searching for scientific information a challenging task. In this paper, we present the implementation of a semantic search engine targeted at COVID19 research articles. The algorithm uses a modified Term Frequency-Inverse Document Frequency (TFIDF) features and cosine similarity with ontology maps for semantic search. The implementation includes sentiment analysis, keyword extraction, keyword-based search, phrase extraction, textual belief indication, and text summary. The system is lightweight and can be deployed as a standalone system on mobile devices. The analysis reported in the work is based on data from 50k research articles related to COVID19 research. The tool also assists the researchers to upload their own text or documents for performing analysis. The comparisons with state of the art algorithms such as BERT and Word2Vec indicate improved performance.

Solar cookers working at intermediate temperature (120–240 ˚C) promise faster propagation of solar cooking technology as they offer a range of cooking options with reduced cooking time. As the thermal losses in such cases would be relatively high, it is pertinent to develop an appropriate rating technique. This paper attempts to identify and investigate the suitable test loads that enable the selection/rating of different designs of solar cookers at intermediate temperatures. Thus, two different working fluids have been used as the tests loads. Two different designs of solar cookers have been tested to serve the purpose using Cooker Opto-Thermal Ratio (COR) as a thermal performance parameter (TPP). The experimental results show that the use of proposed test loads yields approximately identical value of TPP for a specified design of solar cooker at intermediate temperature and enables its rating/grading at such temperatures. The impact of design change at an intermediate temperature on the TPP has been assessed by changing the radiative characteristics of the cooking pot surface to validate the proposal. It is observed that in the case of concentrating solar cooker the design change has a large impact on the TPP value and accordingly the maximum achievable cooking temperature and reference time show substantial improvement. However, in a box type cooker, the impact of design change is seen to be insignificant.

A surge in the usage of electronic devices has led to a new kind of problem; electromagnetic (EM) interference. In a quest toward providing effective shielding, which offers design flexibility, lightweight, and ease to integrate and embed, the right combination of materials needs to be synthesized and dispersed in a polymer matrix to design composites that can shield EM radiation. However, selection of nanoparticles from a vast library is quite challenging and, hence, this study attempts to provide a physical insight into the mechanism of shielding in polymer nanocomposites containing a conducting phase (here multi-walled carbon nanotubes, MWCNTs) and a magnetic phase here inverse-spinel ferrites, MFe2O4 (M = Fe, Co, Ni)]. We adopted a biphasic co-continuous blend (consisting of polycarbonate and polyvinylidene fluoride) as the matrix to incorporate the conducting and the magnetic phases. MWENTs, which offer interconnected conductive fence, and ferrites, which provide magnetic dipoles that couple with incoming EM radiation, can absorb the incoming EM radiation. The detailed mechanistic insight regarding absorption of EM radiation reveals that high saturation magnetization, high consolidated loss, better impedance matching, higher attenuation constant, high hysteresis loss, and comparable eddy current loss help Fe3O4, compared to the other ferrites employed here, to effectively shield the EM wave in the X and Ku band frequency through absorption. In addition, better impedance matching, low skin depth, and enhanced dielectric and/or interfacial polarization losses because of pi-electrons in MWCNTs suggest a synergistic effect from both the phases. As a result, -31 dB shielding effectiveness is observed in the case of Fe2O4 and MWCNTs, which is 19% higher when compared with CoFe2O4 + MWCNT-containing blends and 24% higher when compared with NiFe2O4 + MWCNT-containing blends. Interestingly, when the nanoparticles are forced to localize in different components of the blends, the overall shielding efficiency enhances further because of their higher consolidated loss parameters. Hence, the mechanistic insight provided in this paper will help guide researchers working in this field from both academic and industry perspectives.

A fluorescent, Hg2+ selective sensor, based on a Rhodamine 6G and methionine conjugate (RGM) has been devised and synthesized. The compound was well characterized by analytical techniques like 1H NMR, ESI–MS, FTIR, UV–vis absorption and fluorescence spectroscopy. The spectroscopic studies revealed that RGM displays a high selectivity and sensitivity towards Hg2+ in presence of several other interfering metal ions in Tris-HCl buffer (10 mM, pH 7.04) containing CH3CN/H2O (1:1, v/v) by forming a 1:1 complex with Hg2+. The complexation of the probe RGM with Hg2+ was also confirmed by ESI–MS and FTIR spectra. The detection limit of the probe RGM for Hg2+ was found to be 2.63 × 10−8 M. The ligand RGM and RGM-Hg2+ complex structures have been also established through theoretical studies. Moreover, the RGM-Hg2+ complex was reversible in the presence of sulphide anions and thus RGM-Hg2+ complex could also be used as an efficient sensor for S2− ions. The probe RGM was successfully applied for the detection of Hg2+ in water samples, biological cells as well as in strip test.

Removal of actinides (trivalent, tetravalent and hexavalent) from nitric acid medium was studied using solid-liquid extraction technique employing polymeric encapsulated beads (PEBs) using an indigenously synthesized, unexplored novel monoamide, N,N′-bis(2-ethyl hexyl) α-hydroxy acetamide (BEHGA). The PEBs were synthesized by phase inversion technique. The structure and morphology of the synthesized PEBs were evaluated by employing various characterization techniques like FT-IR, TGA and SEM. The well characterized PEBs were studied for its Am(III), Pu(IV) and U(VI) sorption behavior from nitric acid medium. Kinetics studies showed that the sorption is fast with equilibrium being reached within 60 min of equilibration. The sorption mechanism follows pseudo-second-order mechanism with intraparticle diffusion playing an important role. Langmuir isotherm model was found to best describe the sorption isotherm. The maximum Am(III) sorption capacity of the PEBs was found to be 8.45 mg/g (experimental) and 8.43 mg/g (Langmuir). Back extraction was possible using 0.5 M HNO3. Stability of the PEBs was found to be quite good with no significant structural deformation or leaching out of the extractant in 4.0 M HNO3 solution for at least up to 8 days.

An unexplored novel monoamide N,N′-bis(2-ethyl hexyl) α-hydroxy acetamide (BEHGA) was used as a carrier for transport of Am(III), Eu(III), Pu(IV/VI) and U(VI) from HNO3 medium across a supported liquid membrane (SLM). Various parameters were investigated to obtain the optimum transport conditions. Transport rates followed the trend Pu(IV)>Am(III)≥Eu(III)>U(VI)> Pu(VI). The effects of macro concentrations of U(VI) and Nd(III) on the transport rate of Am(III) were studied. The diffusion coefficient value for the Am(III)-BEHGA system in HNO3 medium was found to be ~1.8×10−6 cm2/s. The standard deviation of the results obtained from transport experiments by this extractant was found to be ±5%. The membrane was found to be highly selective for actinides and lanthanides with respect to different fission products.

A new simple 3-in-1 multi-response thiosemicarbazone-based chemosensor has been synthesized and characterized. The probe not only exhibited high sensitivity towards the most familiar and abundant group 12 metal ions, viz., Zn2+, Cd2+ and Hg2+, in MeCN–H2O (1 : 1, v/v) medium but also can efficiently distinguish them through significant changes in their absorption and emission spectral behavior. The selectivity response was found to follow the order Hg2+, Cd2+, Zn2+ due to the different degrees of stability of their respective complexes, which was further established by TDDFT calculations and interference studies. The binding affinities of the probe towards these metal ions were investigated by absorption, fluorescence emission, fluorescence lifetime, mass spectral and 1H NMR spectral measurements. The effects of solvent polarity on the probe molecule were also examined. Due to the observation of different binding affinities and the ensuing significant changes in absorbance at different wavelengths by a combination of different inputs, L can be judiciously applied for the construction of some basic logic gates (AND, OR, NOT, IMPLICATION and INHIBIT).

Regardless of its location, our electronic equipment does not always escape the threats of electromagnetic interference (EMI). Unrestrained radio and microwave radiation from communication devices, broadcasting stations, power lines and other electric equipment constantly bombards us and our precise circuitry equipment. Although its effects on human beings have not yet been directly demonstrated, our electronic gadgets are not that fortunate. A plethora of research work has already been published in the search for a perfect shielding material. Studies in the last decade reveal that dielectric ceramics, magnetic oxides/ferrites/particles, semiconductors, metal particles/foams, intrinsically conducting polymers, conducting carbon black/fibers/nanotubes and other carbon derivatives such as graphene etc. have been widely researched. The particles are either embedded in a wax medium or in a thermoplastic matrix to design an effective shield. To this end, polymer-based nanocomposites have been much discussed owing to their technology-matching properties, light weight, ease of fabrication and adaption, lack of corrosion, and design flexibility. However, the high dosage of nanofillers needed to meet the requirements of an effective shield mars their utility in many respects. Although bi-phasic polymer blends have been researched from different perspectives, utilizing them as a template for microwave shielding is currently drawing enormous interest compared with single-polymer-based nanocomposites. This review highlights the stepwise advancement of bi-phasic polymer blends towards EMI shielding applications. We in this manner endeavor to provide a necessary overview and point out the direction in which future research will keep on thriving as this new class of material emerges as an effective EMI shield.

Considerable attention has been given in recent years towards the development of electromagnetic interference (EMI) shielding materials. In spite of the fact that leading polymer composites containing different magnetic and dielectric nanofillers have been used broadly, nevertheless, the impact of inorganic semiconducting nanomaterials has not been utilized fully. Herein, we have designed hollow ZnS nanospheres doped reduced graphene oxide sheets (rGO) via template-free, one-pot hydrothermal synthesis process and fabricated nanocomposites with poly(vinylidene fluoride), PVDF as matrix. Three dimensional conducting network of rGO sheets along with high interacting surface area with heterogeneous dielectrics led to a very high total shielding effectiveness (-40 dB) with 93% absorption. The underlying mechanism, supported by skin-depth estimation and attenuation constant, is discussed in detail. This study opens new avenues in the field of EMI shielding materials as inorganic semiconductors show promising results in contrast to traditional materials involving conducting, dielectric and magnetic nanoparticles embedded polymer nanocomposites.

To minimize electromagnetic (EM) pollution, two key parameters, namely, intrinsic wave impedance matching and intense absorption of incoming EM radiation, must satisfy the utmost requirements. To target these requirements, soft conducting composites consisting of binary blends of polycarbonate (PC) and poly(vinylidene fluoride) (PVDF) were designed with doped multiwalled carbon nanotubes (MWCNTs) and a three-dimensional cross-linked graphene oxide (GO) framework doped with ferrite nanoparticles. The doping of alpha-MnO2 onto the MWCNTs ensured intrinsic wave impedance matching in addition to providing conducting pathways, and the ferrite-doped cross-linked GO facilitated the enhanced attenuation of the incoming EM radiation. This unique combination of magnetodielectric coupling led to a very high electromagnetic shielding efficiency (SE) of -37 dB at 18 GHz, dominated by absorption-driven shielding. The promising results from the composites further motivated us to rationally stack individual composites into a multilayer architecture following an absorption-multiple reflection-absorption pathway. This resulted in an impressive SE of -57 dB for a thin shield of 0.9-mm thickness. Such a high SE indicates >99.999% attenuation of the incoming EM radiation, which, together with the improvement in structural properties, validates the potential of these materials in terms of applications in cost-effective and tunable solutions.

Functional nanomaterial embedded lightweight polymer composites have drawn considerable attention across wide ranges of industrial applications. In addition to telecommunication and aerospace utilities, microwave absorbing materials must possess interesting properties that ensure excellent performance, from mechanical features to functionalities. Although conducting polymer composites containing magnetic nanofillers have been utilised widely, choosing the fillers from the library of nanoparticles and their effective dispersion inside the matrix may limit their usage in terms of performance, stability and durability. In order to overcome this bottleneck, herein we explored a facile bottom-up synthetic procedure to fabricate different shapes (spherical, cubic, cluster and flower, for example) and size-controlled Fe3O4 nanoparticles, and showed the effect of shape anisotropy and size on the above properties in a model polycarbonate (PC)/polyvinylidene difluoride (PVDF) blend with multiwalled carbon nanotubes as conducting nanofillers. The superior performance in terms of microwave attenuation and mechanical properties was reported for spherically shaped Fe3O4 nanomaterials. The excellent dispersibility of small-sized nanospheres was instrumental in the improved consolidated loss tangent values, attenuation constant, and impedance matching and skin depth, synergistically resulting in a shielding efficiency of −38 dB at 18 GHz.

A novel fluorophore–spacer–receptor has been designed with hydrazono methyl phenol as the receptor, anthracene as the fluorophore and imine (CN) groups as the spacer. This newly designed fluorophoric system has a receptor that can bind with ferrites and a fluorophore core that can conjugate non-covalently with multiwalled carbon nanotubes (MWNTs) via π–π conjugation. The hybrid nanoparticles were thoroughly characterized using Raman, UV-vis and fluorescence spectroscopy. This unique hybrid is further explored as a novel material to screen electromagnetic (EM) radiation. By precisely localizing these hybrids in a given phase of an immiscible co-continuous blend, unique microstructures can be constructed. Herein, blends of polyvinylidene fluoride (PVDF) and polycarbonate (PC) were chosen as a model system. The hybrid nanoparticles were selectively localized in the PVDF phase owing to its higher polarity and were systematically characterized by electron microscopic and solution–dissolution techniques. The hybrid nanoparticles that were designed to shield from the incident EM radiation resulted in >99.99% attenuation, dominated mostly by absorption. This non-covalent approach of conjugating MWNTs with ferrites, aided by the fluorophoric system, was noted to be a more effective way to improve the properties (both bulk electrical conductivity and structural) than direct physical mixing/covalent conjugation approaches. In order to further enhance the shielding effectiveness (SE), a layer-by-layer architecture was constructed essentially with outer layers containing PC/PVDF blends with a MWNT–ferrite hybrid and the inner layers consisting of PC/PVDF blends with only MWNTs. An ultra-thin shield of 0.90 mm showed >99.9999% attenuation suggesting new pathways for designing lightweight, flexible EMI shielding materials.

The fabrication of thin multilayer polymer nanocomposite films and their judicious arrangement in a sandwich structure to attenuate incoming electromagnetic (EM) radiation, mostly by absorption, is discussed herein. Two key properties (reasonably high conductivity, with high dielectric loss and magnetic permeability) were targeted here by using multiwall nanotubes (MWCNTs) and BaTiO3/Fe3O4 (BT/Fe) co-doped graphene oxide (GO) sheets to design soft functional nanocomposites using bi-component blends of PC (polycarbonate) and PVDF (polyvinylidene fluoride). High dielectric loss and magnetic permeability were achieved by uniformly distributing BT and Fe nanoparticles on the huge specific surface area provided by the GO sheets. The MWCNTs were non-covalently modified to exfoliate the nanotubes and to get a well-connected structure of the blend components. The MWCNTs were thoroughly characterized by TEM, UV-vis, fluorescence emission, Raman and TGA. This surface modification of the MWCNTs also helps with their specific localization in the continuous bi-component blends. BT and Fe were co-doped onto the GO sheets by a well-designed step-by-step synthesis protocol, and the product can facilitate the absorption of incoming EM radiation. This hybrid structure was thoroughly characterized by various microscopic and spectroscopic techniques. By following a sequential mixing protocol, the BT/Fe co-doped GO sheets can be specifically localized in the PC components of the blends while the MWCNTs localize in the PVDF phase through a process driven by thermodynamics. This provides excellent heterogeneous boundaries with multiple scattering within the engineered nanostructures, in addition to retaining the conducting network and the associated dielectric loss properties. The resultant local field variation of such boundaries and the presence of highly lossy materials readily enhance the EM attenuation coefficient. The bulk compositions exhibited a high shielding effectiveness (SE) of −35 dB at 18 GHz (>85% absorption), and when rationally stacked into a multilayer architecture with absorption–multiple reflection–absorption pathways, the SE was further enhanced to −46 dB for a thin shield of 0.9 mm thickness. Such a high SE indicates >99.99% attenuation of the incoming EM radiation. This new-generation EM suppressor, distinguished by its multifunctionality and tunable dielectric and magnetic properties, hence offers an amendable, cost-effective replacement to existing solutions.

Steady state fluorescence spectroscopic technique has been used to investigate the aggregation of coal derived asphaltene (CDA) sourced from Lodna Coke Plant situated at Dhanbad, India. The emission spectra of CDA provide information regarding the various stages of onset of aggregation in carbon tetrachloride medium. Almost similar results have also been inferred from the analysis of corresponding excitation spectra. It has been observed that the onset of aggregation of CDA occurs at concentration beyond a concentration of 10 mg L−1. Studies indicate the formation of a trimer at this concentration range. The association constant (K) for the trimer formation has also been evaluated from the spectroscopic data.

Both petroleum and coal derived asphaltene finds important place on the present research areas of hydrocarbon based liquid and solid fuels. It has earned a name of ‘unwanted’ fame for its deleterious impacts arising mainly due to its self aggregational phenomenon. Over the period of time the asphaltene aggregation has been seriously investigated worldwide even at the molecular scale. Besides several methods, the spectroscopic findings (UV Vis and Fluorescence), in this regard, contribute to substantial meaningful data. The major spectroscopic researches on the aggregation of asphaltene over the last ten years have been reviewed in this present study. A brief discussion on the asphaltene molecular structure and molecular weight also comes as a prelude. Asphaltenes derived from both petroleum and coal have been considered.

The multifaceted photodynamics of a simple azine based organic functional molecule namely 2-((Z)-((E)-(pyren-1-ylmethylene)hydrazono)methyl)quinolin-8-ol (PHQ) emphasizing its brilliant fluorescence emission redemption properties in aggregation state (AIEE) have been primarily explored through absorption and steady state emission techniques. The governing role of photo-induced electron transfer (PET) rates and active intramolecular motions of non-interacting PHQ monomers at lower water fraction comprising mixed solvent systems have been identified to be the prime reasons for non-radiative annihilation of photoexcited states. The transition from weakly emissive to highly emissive state has been substantiated through elaborate study using time-resolved photoluminescence (TRPL), fluorescence quantum yield and variation of external control experiments. In the current study, the increased rotational relaxation time of aggregated hydrosol, responsible for AIEE, is investigated using time-resolved anisotropy measurement (TRAM) of different PHQ microenvironments, which is unprecedented to the best of our knowledge in AIEE research. Interestingly, the high-angle annular dark field-scanning transmission electron microscopy (HAADF-STEM) image shows one dimensionally grown molecular entity of a single nano-sheet like structure of PHQ, which is a unique observation. The average particle size of PHQ aggregates is also increased from 84.5 nm to 814 nm corresponding to 10% and 90% fw (water volume %) system respectively. The energy-dispersive X-ray spectroscopy (EDX) has also been employed, for the first time in AIEE research, which reveals a gradual increase in the amount of carbon within the aggregated microstructure with addition of water. The present molecular system PHQ, being a molecular rotor system, provides future prospect for probing local microenvironmental viscosities within biological systems.

Am(III) is one of the most hazardous radionuclide present in nuclear fuel cycle. A new conformationally constrained diamide, ( N , N , N ′, N ′-tetra-2-ethylhexyl)7-oxabicyclo[2.2.1]heptane-2,3-dicarboxamide (OBDA) was studied for Am(III) transport from HNO 3 medium across a Supported Liquid Membrane. Transport rate was observed to be significantly fast with ∼95% transport of Am(III) within 1 h using 0.1 M OBDA in the presence of 15% isodecyl alcohol (IDA)/ n -dodecane as carrier. The mechanism of transport was investigated by studying various parameters like feed HNO 3 /NaNO 3 concentration, OBDA concentration in the membrane, membrane pore size, membrane thickness etc. From these studies, the mechanism of transport was found to be diffusion controlled with diffusion co-efficient value of 5.1 × 10 −6 cm 2 /s. The membrane was found to be highly selective for tri- and tetra-valent actinides, and trivalent lanthanides. OBDA based membrane was found to be stable for at least for ten consecutive cycles of operation.

By fluorescence spectroscopy it has been established that coal derived asphaltene (CDA) forms aggregates in CCl4 medium. The new feature of this compound is that even before aggregate formation it can incorporate water molecules and the critical aggregation concentration (CAC) in nonaqueous medium increases with increase in ω (= water:CDA mole ratio). The fluorescence spectroscopic determination of the equilibrium constant (K) of the molecular complex of [60] fullerenes with CDA in carbon tetrachloride medium has revealed that K increases on addition of microquantities of water. This observation has been rationalized by assuming that the nitrogenatoms at one end of CDA molecules attach themselves to the water micropool and thus producing a different conformation with a wider distance at the other end. This pre-organization further facilitates inclusion. By utilizing fluorescence variation of [60]fullerene/CDA complex in CCl4 as continuous medium with change in ω a critical ω (=5) has been found. The forma...

Coal-derived asphaltene (CDA) has been shown to form electron donor–acceptor-type molecular complexes with electron acceptor such as 2,5-cyclohexadiene-1,4-diylidene also known as tetracyanoquinodimethane (TCNQ) in homogeneous medium of carbon tetrachloride and heterogeneous medium of aqueous SDS. This has been investigated both by UV-Vis and fluorescence spectrophotometric method. The Charge transfer (CT) absorption peaks have been detected by difference spectral method and the wavelengths of the CT peaks are close in both the medium. The formation constants (K) have been determined using the Benesi–Hildebrand equation. The magnitudes of K are in the order of 103 L mol−1 that are comparable to some supramolecular or inclusion complexes. The study reveals the presence of π-donor (i.e., aromatic) type of compounds in CDA molecule. It also supports the view that CDA molecules exist in solution forming micellar aggregate, in the cavities of which the TCNQ molecules are included. The remarkable increase (thre...

Novel Solvent Impregnated Resin (SIR) material was prepared by impregnating a trialkyl phosphine oxide functionalized ionic liquid (IL) into an inert polymeric material XAD-7. A series of SIR materials were prepared by varying the IL quantity. Sorption of both U(VI) and Pu(IV) were found to increase with increasing IL concentration in SIR up to an optimum IL concentration of 435 mg g−1 of SIR beyond which no effect of IL concentration was observed. A change of mechanism of sorption for U(VI) by SIR was observed in comparison to solvent extraction. The dependency of U(VI) sorption with nitric acid concentration showed a reverse trend compared to solvent extraction studies while for Pu(IV) the trend remained same as observed with solvent extraction. Sorption of both the radionuclides was found to follow pseudo second order mechanism and Langmuir adsorption isotherm. Distribution co-efficient measurements on IL impregnated SIR showed highly selective sorption of U(VI) and Pu(IV) over other trivalent f-elements and fission products from nitric acid medium.

The manuscript presents the results on the sorption of U(VI), Am(III) & Eu(III) from pH medium by a novel amido-amine functionalized multiwalled carbon nanotube (MWCNT). The novel functional group was introduced in the MWCNT by two step processes and characterized by various instrumental techniques like Scanning Electron Microscopy (SEM), Raman and X-ray Photoelectron Spectroscopy (XPS). The sorption process was found to be highly dependent on the pH of the solution with maximum sorption for both 233U, 241Am & 152+154Eu at pH 7.0. Kinetics of sorption was found to be fast with equilibrium reached in ∼15min and the sorption was found to be following pseudo 2nd order kinetics for the radionuclides. The sorption for both 233U and 152+154Eu followed Langmuir sorption model with maximum sorption capacity of 20.66mg/g and 16.1mg/g respectively. This has been explained by DFT calculations which shows that more negative solvation energy of U(VI) compared to Am(III) and Eu(III) and stronger U-MWCNT-AA complex is responsible for higher sorption capacity of U(VI) compared to Am(III) and Eu(III).The synthesized amido-amine functionalized MWCNT is a very promising candidate for removal of actinides and lanthanides from waste water solution with high efficiency.

Liquid Membrane (LM) transport studies of Pu(IV) were investigated in detail using a novel rationally designed conformationally constrained oxatricyclodiamide (OTDA). Detailed parametric investigations were carried out to understand the transport mechanism and to optimize the transport conditions. Efforts were also made to investigate the effect of diluent on the extraction as well as transport of Pu(IV) across the membrane with OTDA. Mass transfer modeling of the transport process was performed and a good agreement between the experimental results and theoretically values was found. The optimized conditions for transport was found to be a PTFE membrane support of 0.45 μm, 4 M HNO3 as feed acidity, 0.1 M OTDA in 30% IDA/n-dodecane as carrier and in the strippant side a mixture of 0.2 M HAN + 0.3 M HNO3. Under the optimized conditions, the permeability co-efficient value was found to be (2.11 ± 0.08) × 10−3 cm/s. Diffusion coefficient value of 1.06 × 10-6 cm2/s was obtained for Pu(IV)-OTDA system.

A new ligand grafted polymeric resin (BenzoDODA SDVB) was synthesized by covalently attaching plutonium selective ligand (BenzoDODA) on to styrene divinyl benzene (SDVB) polymer matrix. BenzoDODA SDVB resin was evaluated for separation and recovery of plutonium(IV) from nitric acid medium. Sorption of Pu(IV) was found to decrease with the increase in nitric acid concentration, with very small sorption above 7.0 M HNO 3 . Sorption kinetics was fast enough to achieve the equilibrium within 60 min of contact where the kinetic data fitted well to pseudo-second-order model. Sorption isotherm data fitted well to Langmuir model suggesting chemical interaction between the BenzoDODA moiety and plutonium(IV) ions. Sorption studies with some of representative radionuclides of high level waste showed that BenzoDODA SDVB is selective and therefore could be a promising solid sorbent for separation and recovery of plutonium. Further, the theoretical calculations done on BenzoDODA SDVB resin suggested Pu(NO 3 ) 4 ·BenzoDODA (1:1) sorbed complex conformed to generally observed square antiprism geometry of the plutonium complexes, with contributions from oxygen atoms of four nitrate ions as well as from four oxygen atoms present in BenzoDODA (two phenolic ether oxygen atoms and two carbonyl oxygen atoms of amidic moiety).

We are developing the first optical frequency standard in India with single ytterbium ion (171Yb+), which is confined and laser cooled in an ion trap. This precision clock experiment needs to be automated for running it reliably and continuously over few days. For this we are developing a computer control systems. Some of its supporting hardware modules have already been designed and tested. In this article we describe scheme of our automation and control system.