Modification of WS2 thin film properties using high dose gamma irradiation.

The tunability of the Transition Metal Dichalcogenide (TMD) properties has gained attention from numerous researchers due to their wide application in various fields including quantum technology. In the present work, WS2 has been deposited on fluorine doped tin oxide (FTO) substrate and its properties have been studied systematically. These samples were irradiated using gamma radiation for various doses, and the effect on structural, morphological, optical and electrical properties has been reported. The crystallinity of the material is observed to be decreased, and the results are well supported by X-ray diffraction, Raman spectroscopy techniques. The increase in grain boundaries has been supported by the agglomeration observed in the scanning electron microscopy micrographs. The XPS results of WS2 after gamma irradiation show evolution of oxygen, carbon, C=O, W-O and SO42- peaks, confirming the addition of impurities and formation of point defect. The gamma irradiation creates point defects, and their density increases considerably with increasing gamma dosage. These defects crucially altered the structural, optical and electrical properties of the material. The reduction in the optical band gap with increased gamma irradiation is evident from the absorption spectra and respective Tauc plots. The I-V graphs show a 1000-fold increase in the saturation current after 100 kGy gamma irradiation dose. This work has explored the gamma irradiation effect on the WS2 and suggests substantial modification in the material and enhancement in electrical properties. .

Probing Effect of 6 MeV Electron Beam Irradiation on Haemoglobin Protein Using Spectroscopic Techniques.

In this work, we study the effect of 6 MeV electron beam irradiation on the physicochemical properties of lyophilized Human Haemoglobin A (HbA). Electron beams generated from Race Track Microtron accelerator with energy 6 MeV were used to irradiate HbA at fluences of 5 × 1014 e-/cm2 and 10 × 1014 e-/cm2. Pristine and electron beam irradiated HbA were characterized using UV-visible and Fourier transform infrared spectroscopy (FTIR) spectroscopy. The interfacial tension of the aqueous solutions of HbA are also analysed by pendant drop method. Absorbance intensity, % transmittance and interfacial tension decrease with fluence. The peak position of the Soret band (λsoret = 404 nm) remains unaffected by the fluences. FTIR spectroscopy confirms the changes in the secondary structure of the haemoglobin. In the amide band I, the percentage of α-helix reduced from 8% to 1%, and an increase in ß-sheet (19% to 29%) and ß helix (6.3% to 15%) is observed. Interfacial tension decreases from 46.0 mN/m and 44.0 mN/m with increase in irradiation dose. These finding provides realistic guideline for biological cells exposure to electron beam radiation doses.

Improved photocatalytic activity of TiO2 nanoparticles through nitrogen and phosphorus co-doped carbon quantum dots: an experimental and theoretical study.

In this work, we develop a photocatalyst wherein nitrogen and phosphorus co-doped carbon quantum dots are scaffolded onto TiO2 nanoparticles (NPCQD/TiO2), denoted as NPCT hereafter. The developed NPCT photocatalyst exhibits an enhanced visible light photocatalytic hydrogen production of 533 µmol h-1 g-1 compared to nitrogen doped CQD/TiO2 (478 µmol h-1 g-1), phosphorus doped CQD/TiO2 (451 µmol h-1 g-1) and pure CQD/TiO2 (427 µmol h-1 g-1) photocatalysts. The enhanced photocatalytic activity of the NPCT photocatalyst is attributed to the excellent synergy between NPCQDs and TiO2 nanoparticles, which results in the creation of virtual energy levels, a decrease in work function and suppressed recombination rates, thereby increasing the lifetime of photogenerated electrons. A detailed mechanism is proposed for the enhancement in visible light hydrogen production by the NPCT photocatalyst from the experimental results, Mott-Schottky plots and ultraviolet photoelectron spectroscopy results. Further, first-principles density functional theory (DFT) simulations are carried out which predict the decrease in the work function and band gap, and the increase in the density of states of NPCT as the factors responsible for the observed enhancement in visible light photocatalytic hydrogen production.

Activity measurement of mixed complex radionuclide like 152Eu with different methods.

152Eu has been standardized by three independent 4π ß-γ coincidence counting systems with beta detectors as proportional counter, plastic scintillator and liquid scintillator along with the CIEMAT/NIST method. The average activity concentration by primary methods was linked to key comparison reference value (KCRV) by comparing it with that of 4π γ ionization chamber (GIC) whose calibration factor was determined from the KCRV (BIPM.RI(II)-K1.Eu-152 and CCRI(II)-K2.Eu-152) and deviates from GIC by ± 0.16% indicating good agreement within standard uncertainties.

Investigation of thermoluminescence and photoluminescence properties of Tb3+, Eu3+, and Dy3+ doped NaYF4 phosphors for dosimetric applications.

Hexagonal phase sodium yttrium fluoride activated with lanthanide ions; Tb3+, Eu3+ and Dy3+ doped NaYF4 phosphors were synthesized using a simplistic hydrothermal method. The photoluminescence studies demonstrated green, red and blue emission lines corresponding to 5D4 → 7FJ (J = 6, 5, 4, 3), 5D0 → 7FJ (J = 1, 2 and 4) and 4F9/2 to 6HJ (J = 15/2 and 13/2) transitions, which are characteristic of Tb3+, Eu3+ and Dy3+ ions, respectively. The as-synthesized samples were subjected to annealing at varying temperatures from 500 °C to 800 °C primarily for the optimization of the thermoluminescence glow curve. Meanwhile, we studied the influence of thermal annealing treatment on the crystal phase, morphological features, and photoluminescence properties of the phosphors. The spherical-like morphology of NaYF4:Tb3+ phosphor changed to micro block-like structures and the hexagonal phase of NaYF4 transforms into a cubic phase at a higher annealing temperature of ∼800 °C. The photoluminescence emission intensity also varied at different annealing temperatures. The systematic study using different dopants and annealing temperatures was carried out to accomplish efficient thermoluminescence (TL) properties. The most suitable TL dosimetric glow peak was attained for NaYF4:0.5%Tb3+ phosphor, which was annealed at a temperature of 800 °C, located at 194 °C. The NaYF4:Tb3+ phosphor exhibited TL response fairly linear in the dose range from 1 kGy to 25 kGy of gamma radiation. The phosphor showed TL response at higher doses, which stipulates that the NaYF4:Tb3+ is reasonably well suitable for high dose measurements and respective applications. The phosphor exhibited negligible fading and good reproducibility features. Trap-level analysis and experimental determination of activation energy were performed using the Tm-Tstop technique and initial rise method (IRM). The trapping parameters of the TL glow curve, such as activation energy (E), order of kinetics (b), and frequency factor (s) were estimated by Chen's glow peak shape (PS) method and glow curve deconvolution (GCD) method. The trapping parameters obtained using the IRM, PS and GCD methods are in good accordance with each other. Henceforth, along with efficient photoluminescence properties, the NaYF4:Tb3+ phosphor exhibited favorable thermoluminescence dosimetric properties. Consequently, this study provides new opportunities for utilizing these phosphors in the area of radiation dosimetry applications such as environmental and food monitoring, space dosimetry etc.

Establishment and Dissemination of Radiological Standards in the Field of Diagnostic Radiology in India.

BACKGROUND: The increased use of ionizing radiation for diagnostic purpose has resulted in an increase in the world population dose. Patient dosimetry in X-ray diagnostic radiology is required to establish diagnostic reference levels (DRLs) and to assess the average dose received by organs and tissues. International bodies have recommended DRLs to be based on dosimetric quantities. AIM: To cater to the increased requirement for dosimetry in diagnostic radiology, international guidelines are provided to establish and disseminate traceable calibration for dosimeters used in X-ray diagnostic radiology. X-ray diagnostic beams established are standardized using a diagnostic range free-air ionization chamber (DFAIC) (20-150 kV). MATERIALS AND METHODS: Characterization of the DFAIC and determination of the correction factors for the air kerma measurements were evaluated experimentally and by theoretical calculations. RESULTS: The paper details the establishment of 18 diagnostic beam qualities using DFAIC along with the associated uncertainties. The overall uncertainty for the air kerma measurements was within ±0.5% at 1 sigma level. Eight diagnostic range air kerma measurements using DFAIC were compared with the medium energy primary standard FAIC (50-300 kV) maintained in the laboratory. CONCLUSION: The air kerma rates agreed within ±1% and are within the overall standard uncertainty of both the chambers at the time of the comparison. Dissemination to the users in the field of diagnostic radiology in the country has been carried out by calibrating their ionization chambers and solid-state detector-based instruments against the DFAIC. The methodology followed to standardize the beams using DFAIC and calibration of dosimeters is presented in this work.

Standardisation of 133Ba by efficiency extrapolation method and calibration of ionisation chamber.

133Ba has been standardised by direct measurements for the first time in the laboratory using two counting systems: (i) the 4πß (plastic scintillator) -γ coincidence, (ii) the 4πß (proportional counter) -γ coincidence. Furthermore, this standardisation experiment demonstrates the performance and applicability of the recently developed 4πß (plastic scintillator)-γ coincidence system for radionuclides decaying with complex decay schemes as well as for e, X-γ emitters. Additionally, 133Ba solution standards were prepared to calibrate the pressurized 4π γ ionisation chamber and determination of the calibration coefficient. The En score is a statistical indicator of the agreement between two independent estimations. Thus, the performance of the PS system was compared to the result obtained with the PC system using the En score as specified in the ISO13528:2015. The results of measurements are acceptable if En â‰¦ 1.0. An En score of 0.2 was obtained which indicates that, the 133Ba activity concentration obtained by the 4πß (plastic scintillator) -γ coincidence and 4πß (proportional counter) -γ coincidence systems are in agreement. This paper presents the standardisation procedure, the results obtained by the measurements and their comparison.

Development of plastic scintillator based primary standard for activity measurements and its performance evaluation.

4πß-γ coincidence technique is a powerful tool and widely recognised method to determine the absolute activity concentration of radioactive solutions. A new plastic scintillator based coincidence system has been developed and established as a primary standard for radioactivity measurements. The performance of the system was evaluated by the standardisation of 60Co radioactive solution due to its simple decay scheme. The activity concentration results obtained by the new system were compared with the existing proportional counter and liquid scintillation based 4πß-γ coincidence systems. This paper discusses the design details of the new system and its performance evaluation.

Synthesis, Characterization and Anti-Biofilm Efficacy of Polypyrrole-Zinc Oxide Composites.

A nanocomposite of Polypyrrole (PPy) and zinc oxide (ZnO), termed as PPy-ZnO, was synthesized by two step route. In the first step, synthesis of PPy was carried out by chemical oxidative route. In the second step, the PPy-ZnO nanocomposite was synthesized under hydrothermal conditions. The as-synthesized PPy-ZnO nanocomposites were characterized using X-ray Diffraction (XRD), scanning electron microscopy (SEM), Fourier Transform Infra-red (FTIR) and Ultra violetvisible (UV-vis) spectroscopy to reveal the phase, morphology, chemical and optical properties. The physical and chemical characterizations confirmed presence of both PPy and ZnO phases in the nanocomposite. In the present work, antimicrobial activity of the PPy-ZnO nanocomposite against human pathogen Y. lipolytica has been investigated. Attempts have been made to reveal the influence of PPy percentage on the antimicrobial activity. Interestingly, all PPy-ZnO nanocomposites, irrespective of PPy percentage, showed 90 to 95% inhibited growth of Yarrowia lipolytica. The results obtained herein imply the potential of PPy-ZnO biofilm in inhibiting the growth of Y. lipolytica and thus preventing infections caused due to Y. lipolytica in humans.

Synthesis, characterization and in vitro study of biocompatible cinnamaldehyde functionalized magnetite nanoparticles (CPGF Nps) for hyperthermia and drug delivery applications in breast cancer.

Cinnamaldehyde, the bioactive component of the spice cinnamon, and its derivatives have been shown to possess anti-cancer activity against various cancer cell lines. However, its hydrophobic nature invites attention for efficient drug delivery systems that would enhance the bioavailability of cinnamaldehyde without affecting its bioactivity. Here, we report the synthesis of stable aqueous suspension of cinnamaldehyde tagged Fe3O4 nanoparticles capped with glycine and pluronic polymer (CPGF NPs) for their potential application in drug delivery and hyperthermia in breast cancer. The monodispersed superparamagnetic NPs had an average particulate size of ∼ 20 nm. TGA data revealed the drug payload of ∼ 18%. Compared to the free cinnamaldehyde, CPGF NPs reduced the viability of breast cancer cell lines, MCF7 and MDAMB231, at lower doses of cinnamaldehyde suggesting its increased bioavailability and in turn its therapeutic efficacy in the cells. Interestingly, the NPs were non-toxic to the non-cancerous HEK293 and MCF10A cell lines compared to the free cinnamaldehyde. The novelty of CPGF nanoparticulate system was that it could induce cytotoxicity in both ER/PR positive/Her2 negative (MCF7) and ER/PR negative/Her2 negative (MDAMB231) breast cancer cells, the latter being insensitive to most of the chemotherapeutic drugs. The NPs decreased the growth of the breast cancer cells in a dose-dependent manner and altered their migration through reduction in MMP-2 expression. CPGF NPs also decreased the expression of VEGF, an important oncomarker of tumor angiogenesis. They induced apoptosis in breast cancer cells through loss of mitochondrial membrane potential and activation of caspase-3. Interestingly, upon exposure to the radiofrequency waves, the NPs heated up to 41.6 °C within 1 min, suggesting their promise as a magnetic hyperthermia agent. All these findings indicate that CPGF NPs prove to be potential nano-chemotherapeutic agents in breast cancer.

Characterization of biocompatible NiCo2O4 nanoparticles for applications in hyperthermia and drug delivery.

Monodispersed, superparamagnetic nickel cobaltite (NCO) nanoparticles were functionalized using mercaptopropionic acid (MPA). MPA conjugates with NCO forming a metal-carboxylate linkage, with the MPA-MPA interaction occurring via formation of disulfide bonds, leaving another carboxyl end free for additional conjugation. The cytotoxicity studies on NCO-MPA show cell viability of ∼100% up to a dosage of 40 µg/mL on SiHa, MCF7, and B16F10 cell lines, and on mouse primary fibroblasts. Time-dependent cell viability studies done for a duration of 72 hours showed the cell lines' viability up to 80% for dosages as high as 80 µg/mL. Negligible leaching (<5 ppm) of ionic Co or Ni was noted into the delivery medium. Upon subjecting the NCO-MPA dispersion (0.1 mg/mL) to radiofrequency absorption, the nanoparticles were heated to 75°C within 2 minutes, suggesting its promise as a magnetic hyperthermia agent. Furthermore, the amino acid lysine and the drug cephalexin were successfully adducted to the NCO system, suggesting its potential for drug delivery. FROM THE CLINICAL EDITOR: NCO-MPA nanopartciles were found to be promising magnetic hyperthermia agents, suggesting potential future clinical applications.