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•Importance of fluorescent materials in fingerprint, and anti-counterfeiting.•Significance of surface/substrate in fingermark detection.•Current applied methods for identification of ...latent fingermarks.•Future challenges in enlargement of fluorescent base nanomaterials in detection of fingermarks, and anti-counterfeiting.
This review summarized the applied techniques and applied nanomaterials (NMs) for the progress of latent fingerprints (LFPs) images on several surfaces. Used numerous types of NMs and their benefits along with their quality of the LFPs images on the porous and non-porous substrates. Several conventional techniques used for the examining of FPs pictures such as physical (powder dusting), chemical (cyanoacrylate, ninhydrin, AgNO3, fluorescent dye, etc.), and instrumental (gas chromatography, Raman scattering, Fourier transform infrared, etc.) have been discussed and gradually compromised their disadvantage in the current forensic science demand such as high contrast, good visualization, high sensitivity & selectivity, minimized auto-fluorescent, and low toxicity. The benefits and experimental results conducted by the researchers on various kinds of metal, metal oxides, plasmonic NPs, fluorescent NPs (conjugated polymer NPs, quantum dots(QDs), nonmetallic NPs, mesoporous silica NPs, and lanthanide (Ln3+) NPs, etc.) for the expansion of LFPs images on dissimilar surfaces. Despite the use of NPs in forensic sciences for the detection of LFPs pictures, the main emphasis is on luminescent Ln3+-NPs/ upconversion (UC) NPs. These luminescent Ln3+NPs/ UCNPs can produce more contrast, high visible, highly sensitive, selective, long-life decay imaging pictures of LFPs on different substrates (porous and non-porous) with minimized toxicity, which is lacking in most of the traditional fluorescent NMs. Therefore, this review provides a comprehensive a systematic overview of current trends on LFPs imaging development in forensic sciences. Currently, more studies are required to develop the most efficient, high-performance, surface-functionalized, highly biocompatible, and nontoxic Ln3+ NPs/ UCNPs for the recognition of LFPs images on different surfaces.
Abstract
The microstructural, optical and photocatalytic properties of undoped and 5% Zn doped CeO
2
nanocrystals (NCs) have been explored through various analytical techniques, viz. powder x-ray ...diffraction (PXRD), x-ray photoelectron spectroscopy (XPS), transmission electron microscopy (TEM), UV-visible, Raman and photoluminescence (PL) spectroscopy. XRD data analysis revealed face centred cubic (FCC) crystal symmetry of the samples with average crystallite size in the range of 19–24 nm. XPS results confirmed that the Zn ions exist in +2 states and successfully incorporated into the CeO
2
matrix. Internal structure and morphology observed by TEM exhibited almost uniform cubical shape of the particles of average size ~20–26 nm. The enegy bandgap of undoped and Zn doped CeO
2
NCs had a direct transition of 3.46 eV and 3.57 eV respectively as estimated by the optical absorption data. The increase in the bandgap revealed blue shift of absorption edge due to the quantum confinement effects. The NCs exhibited an inherent luminescence emission peak at ~408 nm in PL spectra. Improvement in the photocatalytic activity was observed for Zn incorporated sample attributed to the enhanced light absorption or/and fall in charge recombination rate between CeO
2
and Zn.
In this article, pure and silver (Ag) loaded tungsten oxide (WO3) nanoparticles have been produced by a simple and cost effective hydrothermal method. The crystal morphology and structure properties ...of the fabricated pure WO3 and Ag (4 and 8 wt%) loaded WO3 nanoparticles have been determined by X-ray diffraction, transmission electron microscopy, micro-Raman spectroscopy and Fourier transform infrared spectroscopy. Both crystallographic (X-ray diffraction and Raman spectra) data indicated the monoclinic structure of prepared samples. Transmission electron microscopic analysis showed that pure and silver loaded tungsten oxide nanoparticles have spherically shaped morphology with average size 25–35 nm which found to be in fair agreement with the average crystallite sizes 28–34 nm as estimated from Scherrer's equation. UV–visible absorption spectra revealed that the optical energy band gap of Ag loaded WO3 nanoparticles decreased with increasing the Ag content. The photocatalytic activity of WO3 with different Ag concentration was evaluated by the photocatalytic degradation of methylene blue under irradiation with visible light; and it exhibited significant enhancement in photocatalytic activity of Ag loaded WO3 as compared to pure WO3. In this way, it acts as a very efficient photocatalyst employable for degradation of toxic dyes and chemicals usually present in textile effluents. In addition, the diffusion coefficient of WO3 increases considerably with Ag loading, which is favourable for its application in energy storage devices.
•A high degradation rate of 92.5% in 120 min is achieved under UV light irradiation.•Ag-WO3 nanoparticles exhibit superior photocatalytic activity than bare WO3.•The material exhibit excellent electrochemical performance in three electrolytes.•Ag loaded WO3 nanoparticles can be employed for energy storage devices.
Titanium (Ti)-added tin-58 wt% bismuth (Sn58Bi) solder alloys were synthesized in this study. The microstructural evolution and mechanical property change of the eutectic Sn58Bi and Ti added Sn58Bi ...alloys were studied before and after thermal aging. Ti added Sn58Bi alloys exhibit a considerably refined microstructure compared with the eutectic Sn58Bi alloy because of the presence of the Ti2Sn3 and Ti6Sn5 intermetallic compounds (IMCs). The formation history of these Ti-Sn IMCs was studied based on a thermodynamic calculation. After thermal aging, the yield strength (YS) and ultimate tensile strength (UTS) of the eutectic Sn58Bi decreased, while the Ti added Sn58Bi alloys maintained the highest YS and UTS. Notably, the superior elongation of 0.5 wt% Ti added sample compared with that of the eutectic Sn58Bi alloy was obtained after 1008 h aging. The fracture morphology of the Ti added Sn58Bi alloys almost unchanged during aging due to the stable microstructure. In addition, the electrical resistivities of the eutectic Sn58Bi were tested, while the resistivities decreased in the Ti added Sn58Bi alloys at room temperature.
•The undoped and Fe-doped TiO2 nanoparticles were synthesized by sol-gel route.•The Fe-doped TiO2 nanoparticles exhibited high photocatalytic activity.•A method for evaluating the electrochemical ...performance is proposed.•Room temperature paramagnetic behaviour was observed.•The reduction of band gap from 3.31 eV to 3.10 eV was obtained.
In this work, undoped and iron doped titania nanoparticles (Fe:TiO2 NPs) were successfully prepared by sol-gel route with two different Fe concentration (5 and 10 mol.%). The effects of Fe doping into TiO2 were thoroughly investigated by XRD, TEM, HRTEM, XPS, FTIR, Raman, UV–Visible spectroscopy and VSM. The obtained nanoparticles have narrow size distribution 41–49 nm and were recognized as anatase TiO2 structure with no signature of Fe cluster or iron oxides as analyzed by X-ray diffraction and Raman. The optical band gap of undoped and iron doped TiO2 NPs is red shifted with respect to the incorporation of iron content. Room temperature M-H loops revealed that all the samples showed a significant paramagnetic behaviour. The enhanced photocatalytic performance was observed for iron doped titania nanoparticles compared with pure TiO2 NPs in respect of methylene blue dye degradation in aqueous suspension under visible light illumination.
Currently, chemotherapy is an important method for the treatment of various cancers. Nevertheless, it has many limitations, such as poor tumour selectivity and multi-drug resistance. It is necessary ...to improve this treatment method by incorporating a targeted drug delivery system aimed to reduce side effects and drug resistance. The present work aims to develop pH-sensitive nanocarriers containing magnetic mesoporous silica nanoparticles (MMSNs) coated with pH-responsive polymers for tumour-targeted drug delivery via the folate receptor. 2-Diethyl amino ethyl methacrylate (DEAEMA) was successfully grafted on MMSNs via surface initiated ARGET atom transfer radical polymerization (ATRP), with an average particle size of 180 nm. The end groups of poly (2-(diethylamino)ethyl methacrylate) (PDEAEMA) brushes were converted to amines, followed by a covalent bond with folic acid (FA) as a targeting agent. FA conjugated to the nanoparticle surface was confirmed by X-ray photoelectron spectroscopy (XPS). pH-Responsive behavior of PDEAEMA brushes was investigated by Dynamic Light Scattering (DLS). The nanoparticles average diameters ranged from ca. 350 nm in basic media to ca. 650 in acidic solution. Multifunctional pH-sensitive magnetic mesoporous nanoparticles were loaded with an anti-cancer drug (Doxorubicin) to investigate their capacity and long-circulation time. In a cumulative release pattern, doxorubicin (DOX) release from nano-systems was ca. 20% when the particle exposed to acidic media, compared to ca. 5% in basic media. The nano-systems have excellent biocompatibility and are minimally toxic when exposed to MCF-7, and -MCF-7 ADR cells.
The present work describes the synthesis of Ag-CoFe2O4/rGO nanocomposite as a photocatalyst through the hydrothermal process by the attachment of silver and cobalt ferrite (CoFe2O4) nanoparticles on ...the surface of reduced graphene oxide. The effect of Ag and reduced graphene oxide (rGO) on the structure, optical, magnetic, photocatalytic, and electrochemical performance of the CoFe2O4 is systematically explored through various analytical techniques. The analyses of the observed outcomes reveal that the graphene sheets are exfoliated and decorated with well-dispersed Ag and CoFe2O4 nanoparticles. UV–vis spectra indicate a gradual shift in the absorption edge toward the higher wavelength with the addition of Ag ions, which signifies variation in the energy gap of the samples. Photoluminescence results divulge that graphene can decline the electron–hole recombination rate and improve the photocatalytic activity of the Ag-CoFe2O4/rGO nanocomposite. In this context, the Ag-CoFe2O4/rGO sample presents good catalytic activity as compared to the CoFe2O4 and Ag-CoFe2O4 photocatalysts for the degradation of methylene blue (MB) dye and suggests that the rGO plays a vital role in the Ag-CoFe2O4/rGO nanocomposite. The deterioration rate of the samples is found to be in the order of CoFe2O4(78.03%) < Ag-CoFe2O4(83.04%) < Ag-CoFe2O4/rGO(93.25%) in 100 min for MB dye, respectively, under visible-light irradiation. The room-temperature ferromagnetic behavior of the samples is confirmed by the M–H hysteresis loop measurements. Overall, the Ag-CoFe2O4/rGO nanocomposite promises to be a strong magnetic photocatalyst for contaminated wastewater treatment. The electrochemical performance of all of the samples was examined by the cyclic voltammetry (CV) that exhibits a superior rate performance and cycle stability of the Ag-CoFe2O4/rGO nanocomposite as compared to the other samples.
In the present study, undoped and Mn-doped ZnO nanoparticles with different Mn concentrations (4 and 6 at.%) have been prepared by polymeric precursor method. The effects of Mn content on the ...structural, optical, and magnetic properties of these nanoparticles were investigated in detail. Room temperature X-ray diffraction (XRD) data revealed hexagonal wurtzite structure of the samples and no other secondary phase has been noticed. The microstructural analysis confirms that the particles of Mn:ZnO are spherical in shape with size ranging between 32 and 45 nm as calculated by Scherrer’s equation and transmission electron microscopy (TEM) images. UV–visible absorption spectroscopy measurements affirm a blue-shift in the band gap with increasing Mn doping in ZnO. The hysteresis loops (M–H) exhibit ferromagnetic behaviour of all samples at room temperature. Temperature-dependent resistivity measurements show semiconducting nature of the samples and reduction in the resistivity on Mn substitution.
Visual inspection through image processing of welding and shot-peened surfaces is necessary to overcome equipment limitations, avoid measurement errors, and accelerate processing to gain certain ...surface properties such as surface roughness. Therefore, it is important to design an algorithm to quantify surface properties, which enables us to overcome the aforementioned limitations. In this study, a proposed systematic algorithm is utilized to generate and compare the surface roughness of Tungsten Inert Gas (TIG) welded aluminum 6061-T6 alloy treated by two levels of shot-peening, high-intensity and low-intensity. This project is industrial in nature, and the proposed solution was originally requested by local industry to overcome equipment capabilities and limitations. In particular, surface roughness measurements are usually only possible on flat surfaces but not on other areas treated by shot-peening after welding, as in the heat-affected zone and weld beads. Therefore, those critical areas are outside of the measurement limitations. Using the proposed technique, the surface roughness measurements were possible to obtain for weld beads, high-intensity and low-intensity shot-peened surfaces. In addition, a 3D surface topography was generated and dimple size distributions were calculated for the three tested scenarios: control sample (TIG-welded only), high-intensity shot-peened, and low-intensity shot-peened TIG-welded Al6065-T6 samples. Finally, cross-sectional hardness profiles were measured for the three scenarios; in all scenarios, lower hardness measurements were obtained compared to the base metal alloy in the heat-affected zone and in the weld beads even after shot-peening treatments.
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In this report, a parametric study was carried out on the single walled carbon nanotubes (SWCNTs) based Cu2O/SWCNTs nanocomposite. The SWCNTs were synthesized via plasma enhanced ...chemical vapour deposition (PECVD) process and nanocomposite through RF sputtering technique. The prepared samples have been characterized through Fourier transform infrared (FTIR) spectroscopy, x-ray diffractometry (XRD), electron microscopy (SEM/HRTEM), energy dispersive x-ray (EDX) spectroscopy, x-ray photoelectron spectroscopy (XPS) and Raman scattering techniques for the detailed structural information. The analysis of XRD data affirms the amorphous nature of the nanotubes and crystalline phase of the Cu2O sample. HRTEM micrographs reveal dispersion of Cu2O nanoparticles of an average size of ∼3.2 nm onto the surface of SWCNTs. The optical properties were studied through UV–vis spectroscopy. Using Tauc’s relation, band gap was estimated and found to be 2.7 and 2.51 eV for Cu2O and Cu2O/SWCNTs nanocomposite respectively. The photocatalytic activity of the nanoparticles and nanocomposite was explored by the photodegradation of methylene blue solution under visible light irradiation. Field dependent magnetization exhibits ferromagnetic nature of both the samples at room temperature that opens a new window for the future electronic devices based on carbon nanotubes.
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