Green emitting rare earth Gd2O3:Tb3+ nanoparticles for rapid imaging of latent fingerprint.

A series of green emitting Gd2O3:Tb3+ (Tb: 0%-10% mol) nanoparticles (NP) were synthesized using the hydrothermal method, then characterized and evaluated for latent fingerprint visualization. X-ray diffraction study (XRD) revealed a cubic structure of the nanoparticles and the total incorporation of the terbium in the Gd2O3 matrix. Field Emission-Scanning Electron Microscopy (FESEM), Energy Dispersive x-ray Spectrometry (EDX) and Transmission Electron Microscopy (TEM) were used to study the morphology and the elementary composition of the NP. Photoluminescence (PL) studies showed strong green emission around 540 nm due to the transition 5D4 â†’ 7F5. The luminescence color of the synthesized NP was characterized by the CIE 1931 chromaticity diagram. The potential use of the NP powders for the visualization of latent fingerprint under UV irradiation was assessed on various substrates. The latent fingerprint images revealed by the Gd2O3:Tb3+ NP powders are clear enough to extract and analyze reliable fingerprint features. The fingerprint quality was evaluated using three fingerprint quality assessment metrics and by extracting and measuring the visibility of the minutiae. The experimental results show very good quality images of the latent fingerprint acquired using the Gd2O3:Tb3+ NP and yield good minutiae extraction.

Functional Sr0.5Ba0.5Sm0.02Fe11.98O4/x(Ni0.8Zn0.2Fe2O4) Hard-Soft Ferrite Nanocomposites: Structure, Magnetic and Microwave Properties.

This paper reports the correlation between the composition of the functional Sr0.5Ba0.5Sm0.02Fe11.98O19/x(Ni0.8Zn0.2Fe2O4) hard-soft nanocomposites (SrBaSmFe/x(NiZnFe) NCs), where 0.0 ≤ x ≤ 3.0, and their structural features, magnetic, and microwave properties. SrBaSmFe/x(NiZnFe) hard/soft ferrite NCs are produced using the one-pot citrate combustion method. According to the XRD analysis, all samples showed the co-existence of both SrBaSmFe and NiZnFe phases in different ratios. Magnetic properties are measured in a wide range of magnetic fields and temperatures (10 and 300 K) and correlated well with the composition of the investigated samples. The microwave properties (frequency dispersions of the magnetic permeability, and electrical permittivity) are discussed by using the co-axial method in the frequency range of 0.7-18 GHz. Non-linear dependences of the main microwave features were observed with varying of composition. The microwave behavior correlated well with the composite theory. These results could be used in practice for developing antenna materials.

Laser Induced Anchoring of Nickel Oxide Nanoparticles on Polymeric Graphitic Carbon Nitride Sheets Using Pulsed Laser Ablation for Efficient Water Splitting under Visible Light.

A visible-light-active nickel oxide-graphitic carbon nitride (NiO@g-CN) hetero-structured nanocomposite was synthesized for the first time by pulsed laser ablation in liquid and used as a photoanode material in photoelectrochemical water-splitting reaction with a solar simulator. It was found that the photoelectrochemical performance of PLAL synthesized NiO@g-CN nanocomposite as photoanode, compared to g-CN as photoanode showed fourfold enhancements in photocurrent density under visible light. FT-IR, XRD, FE-SEM, and EDX consistently showed the proper anchoring of nano-sized NiO on g-CN. UV-DRS and the band gap estimation showed the narrowing down of the band gap energy and consequent enhancement in the visible-light absorption, whereas photoluminescence spectroscopy confirmed the reduction of the recombination of photo-excited electron hole pairs as a result of the anchoring of NiO on g-CN. The photoelectrochemical performance of g-CN and the NiO@g-CN nanocomposite photoanodes was compared by linear sweep voltammetry (LSV), Chronoamperometry (I-t), and Electrochemical Impedance Spectroscopy (EIS). All of these results of the characterization studies account for the observed fourfold enhancement of photocurrent density of NiO@g-CN nanocomposite as photoanode in the photoelectrochemical reaction.

Synthesis of Gd2O3:Eu nanoplatelets for MRI and fluorescence imaging.

We synthesized Gd2O3 and Gd2O3 doped by europium (Eu) (2% to 10%) nanoplatelets using the polyol chemical method. The synthesized nanoplatelets were characterized by X-ray diffraction (XRD), FESEM, TEM, and EDX techniques. The optical properties of the synthesized nanoplatelets were investigated by photoluminescence spectroscopy. We also studied the magnetic resonance imaging (MRI) contrast enhancement of T1 relaxivity using 3 T MRI. The XRD for Gd2O3 revealed a cubic crystalline structure. The XRD of Gd2O3:Eu(3+) nanoplatelets were highly consistent with Gd2O3 indicating the total incorporation of the Eu(3+) ions in the Gd2O3 matrix. The Eu doping of Gd2O3 produced red luminescence around 612 nm corresponding to the radiative transitions from the Eu-excited state (5)D0 to the (7)F2. The photoluminescence was maximal at 5% Eu doping concentration. The stimulated CIE chromaticity coordinates were also calculated. Judd-Ofelt analysis was used to obtain the radiative properties of the sample from the emission spectra. The MRI contrast enhancement due to Gd2O3 was compared to DOTAREM commercial contrast agent at similar concentration of gadolinium oxide and provided similar contrast enhancement. The incorporation of Eu, however, decreased the MRI contrast due to replacement of gadolinium by Eu.

Determination of trace metals using laser induced breakdown spectroscopy in insoluble organic materials obtained from pyrolysis of plastics waste.

Laser induced breakdown spectroscopy (LIBS) was applied for the detection of trace elements in non-degradable part of plastics known as insoluble organic material, obtained from thermal and catalytic degradation of plastics. LIBS signal intensity for each metal measured in the test sample was unique and different. The capability of this technique is demonstrated by analyzing various trace metals present inside plastics and also compared with ICP results. The metal concentration (ppm) measured with LIBS and verified by ICP for Ag (901), Al (522), Fe (231), Co (628), V (275), Ni (558), Pb (325), Mn (167) and Cd (378) are higher than permissible safe limits.

Identification of different type of polymers in plastics waste.

The main goal of this work was to develop and test advanced techniques for the instant identification of different type of polymers in post-consumer plastics. In order to accomplish this task, infrared (IR), X-ray diffraction (XRD), differential scanning calorimetric (DSC) and laser induced breakdown spectroscopic (LIBS) techniques were applied. The following six model plastics were identified in this study. Low-density polyethylene (LDPE), High-density polyethylene (HDPE), Polypropylenes (PP), Polystyrene (PS), Polyethylene terephthalate (PET) and Polyvinyl chloride (PVC) along with few randomly selected plastics waste such as water bottle and cap, water cups, yogurt container and coke bottle were studied. IR has shown the fingerprinting of polymer types present in plastics waste. The XRD analysis helps to provide characteristic spectral lines whose intensities vary with the type of each constituent polymer. The DSC method provided the different crystalline melting temperature, glass transition, and onset temperature for the peaks and the percent crystallinity data single out different polymers. The ratio of LIBS signals intensities of carbon and hydrogen atoms were employed for the finger printing of the different family of plastics. The combined use of IR, XRD, DSC and LIBS techniques yielded very useful and effective results for plastic waste management.