Showing papers by "Yasir Jamil published in 2021"

Study of structural, optical and electrical properties of La3+ doped Mg0.25 Ni0.15 Cu0.25 Co0.35 Fe2-x Lax O4 spinel ferrites

Abstract: Lanthanum substituted Mg–Ni–Cu–Co ferrite nanoparticles prepared through the Sol-Gel method were studied using different methods such as XRD, FTIR, UV-VIS, SEM, Raman, LCR, EDX and IV to evaluate the structural, optical and electrical properties. The single-phase cubic spinel structure of the prepared samples was confirmed from X-ray diffraction analysis. The FT-IR spectra indicated two absorption bands, ν1 and ν2 that represent the complex Fe3+–O2− at A-site (tetrahedral) and B-site (octahedral) vibration. The optical band gap decreased from 2.48eV to 1.53eV observed by UV–Vis, and matched with the electrical resistivity measurements. Variation in the lattice parameters from XRD, the absorption band (octahedral) from FTIR, the optical energy band gap from the UV–vis data and the DC resistivity demonstrated change in structural, optical and electric properties of Mg–Ni–Cu–Co ferrites nanoparticles due to the addition of the rare earth element La3+. Both the dielectric losses and dielectric constant of the prepared samples decreased due to the La3+ ions doping, and A.C conductivity increased with increasing the value of frequency from 8 Hz to 8 M Hz. The variation in Raman peaks reveals that Raman shift varied due to the La3+ addition. EDX data confirmed the stoichiometric calculations of La3+ions substituted into Mg–Ni–Cu–Co ferrite nanoparticles.

Fabrication of visible light active Mn-doped Bi2WO6-GO/MoS2 heterostructure for enhanced photocatalytic degradation of methylene blue

Abstract: The increase in environmental pollution has led to an increased investigation in the development of novel ternary photocatalytic systems for remediation. These photocatalytic systems exhibit superior photocatalytic action for the removal of pollutants because of their visible light active bandgaps. A highly effective visible light active ternary heterojunction was fabricated using a hydrothermal method assisted by ultrasonication. Herein, we report the in situ hydrothermal synthesis of Mn-doped Bi2WO6-GO/ MoS2 photocatalyst, efficiently exhibiting greater photocatalytic activity for the wastewater treatment under solar light. The binary metal sulphide (MoS2) used as a co-catalyst, acted as an electron collector and graphene oxide (GO) as a support material for interfacial electron transfer to and from bismuth tungstate and MoS2. The as-prepared samples were characterized using SEM-EDX, FT-IR, XRD, XPS, BET, PL, and UV–Vis techniques. The bandgap of the novel photocatalyst was found in the visible region (2.2 eV) which helped in suppressing photoinduced electron-hole pairs recombination. The ternary Mn-doped Bi2WO6-GO/MoS2 showed 99% methylene blue removal after 60 minutes of sunlight irradiation at the optimum conditions of pH 8, catalyst dose 50 mg/100ml, and initial MB concentration of 10ppm under sunlight irradiation. The doped ternary heterostructure has proved to be an effective sunlight-active photocatalyst that can be reused without substantial loss in photocatalytic efficiency.

Quantitative Determination of the Effects of He–Ne Laser Irradiation on Seed Thermodynamics, Germination Attributes and Metabolites of Safflower (Carthamus tinctorius L.) in Relation with the Activities of Germination Enzymes

Abstract: The present investigation was undertaken to assess the effects of different doses (100, 300, and 500 mJ) of low power He–Ne laser (632.8 nm) irradiation on seed germination and thermodynamics attributes and activities of potential germinating enzymes in relation with changes in seed metabolites. He–Ne laser seed irradiation increased the amylase (Amy), protease (Pro) and glucosidase (Gluco) activities, with a significant improvement in seed thermodynamics and seed germination attributes. A fast increase was found in free fatty acids (FFA), free amino acids (FAA), chlorophyll (Chl), carotenoids (Car), total soluble sugars (TSS) and reducing sugars (RS) in laser treated seeds in parallel with fast decline in seed oil contents and total soluble proteins (TSP). Significant positive correlations were recorded in laser-induced enhanced seed energy levels, germination, activities of germination enzymes with levels of FAA, FFA, Chl, TSS and RS, but a negative correlation with the levels of TSP and oil. In conclusion, the seed treatment with 100 and 300 mJ He–Ne laser was more effective to improve the seed germination potential associated with an improvement in seed energy levels due to increased activities of germination enzymes due to the speedy breakdown of seed reserves to simple metabolites as building blocks.

Elemental Analysis of Kohl Using Laser Ablation and Atomic Absorption Spectroscopy (AAS) techniques

Abstract: We report the spectroscopic studies of the Kohl plasma produced in air at atmospheric pressure by Laser Induced Breakdown Spectroscopy (LIBS) and Atomic Absorption Spectroscopy (AAS) techniques. The plasma has been produce using Q-switched Nd:YAG laser at Second Harmonic Generation SHG (532 nm), with laser irradiance of 4 × 1010 W/cm2, 10 Hz repetition rate and 5ns pulse duration. From the spectroscopic analysis of the registered spectrum, we have detected the presence of Pb, C, Ca, Cr, Fe, Ba, Zn, Hg, Na and H. The electron temperature has been determined from the intensity ratio of the two transition lines of Pb– I, 368.34 nm and 373.99 nm, whereas the electron number density has been estimated from the Stark broadening profile of the H α line at 656.28 nm. It has been noticed that the maximum value of the electron temperature and electron number density at the initial stage of the plasma. The electron temperature varies as (15500–11600) K and the number density varies as (2.06 × 1017–3.62 × 1016) cm−3 with the delay time of (1-6) μs.

Synthesis of Ag/Co nanoparticles by dual pulsed laser ablation for synergistic photothermal study

Abstract: Magneto-plasmonic nanoparticles have gained increasing interest, especially for the synergistic response study of hyperthermia applications. However, some challenges, including the synthesis process, dose optimization of laser, and magnetic field strength besides its frequency, need significant attention. Herein, we prepared magneto-plasmonic Ag/Co nanomaterials for photothermal performance evaluation using dual-beam of the Q-switched Nd:YAG 1064 nm pulsed laser ablation in distilled water, which can avoid any additive, contaminations, complicated route, and multiple purifications processes as they may occur in chemical synthesis processes. Properties, morphologies, and compositions of synthesized nanomaterials were studied, and results suggested that the main constituents of NPs were Ag/Co. The detailed theoretical calculation of the photothermal performance of nanofluid is described, along with an experimental study of nanofluid and the water as a reference medium using NIR 808 nm laser. The overall results suggest that the higher temperatures for Ag/Co nanofluid compared with water alone were recorded as 16.5 °C, 20.9 °C, 24.7 °C, 24.5 °C, 27.7 °C, and 30.2 °C during 808 nm laser irradiation operating at different corresponding powers, respectively. The possible reason for the higher temperature profiles and the rapid temperature rise of nanofluid than water alone is the localized surface plasmon effects of nanoparticles. These results evidence that silver and cobalt nanomaterials composite structures could significantly increase hyperthermia based on an effective and simple synthesis approach.

Rapid elemental analysis of human teeth using laser induced breakdown spectroscopy

Abstract: Laser induced breakdown spectroscopy has now become a promising tool for quick analysis and characterization of broad range of physical and biological samples. In this study we have reported elemental analysis of the human teeth using laser induced breakdown spectroscopy technique. The fundamental (λ = 1064 nm) and the second harmonic generation (λ = 532 nm) of Nd: YAG laser were used to ablate the samples of human teeth in air at atmospheric pressure. In the recorded spectrum of the teeth plasma we detected the Hydrogen (H), Carbon (C), Oxygen (O) and Nitrogen (N) as well as trace amount of Calcium (Ca), Iron (Fe), Mg (Magnesium), Sulfur (S), Zinc (Zn) and Ni (Nickel) elements. Also Chromium (Cr) from transition [3d4(5D) 4s4p (1P0) (y5 D02) → 3d144s2 (a5D3] at wavelength 300.5 nm. From the spectroscopic analysis of the transition lines of the calcium we measured the electron temperature using the intensity ratio of the transition lines [3p64s4d (3D3) → 3p64s4p (3P02)] at 445.4 nm and 3p64s3s (3S1) → 3p64s4p(3P02) at 616.2 nm. The intensities ratios CaII/CaI and MgII/MgI were used for quantitative determination of hardness. and the electron number density was measured from Stark broadening of transition [3p64s4d (3D3) → 3p64s4p (3P02)] at 422.6 nm under the assumption of local thermodynamic equilibrium. The density of calcium and phosphorous, which are the main matrix of teeth was thus estimated from intensity ratios and electron number density and compared with standard values.

Biotransformation and toxicity evaluation of functionalized manganese doped iron oxide nanoparticles.

Abstract: Safe inorganic nanomaterials are tremendously used for diagnosis and therapies. However, essential processing in the microbiological environment changed the physical properties and in situ degradability, which is evaluated meticulously. In this research article, bare, Polyethylene glycol, and citrate coated manganese doped iron oxide nanoparticles are synthesized through the coprecipitation route. Structural, magnetic, optical, and morphological analyses are performed through different characterization tools. X-ray diffraction confirmed the formation of single-phase FeMnO3 with a crystallite size of 48.91 nm. Vibrating sample magnetometer analysis confirmed the formation of soft ferromagnetic behavior of bare and coated nanoparticles (NPs). Scanning electron microscopy and transmission electron microscopy confirmed the formation of spherical shaped nanoparticles. Single-dose in vivo acute toxicity testing is performed through the intraperitoneal route of administration on groups of healthy albino rats. Elevated enzyme levels of kidney and liver are observed at day 1 but a transient decrease is observed at later stages. Through optical follow-up, degradation effects are studied by adding prepared NPs in lysosomal like medium. Finally, metabolization of degraded products based on manganese/iron ions is studied by adding apoferritin into a lysosome like solution. These studies showed partial storage of manganese ions from NPs, while no substantial transfer is observed in the case of manganese salt.

Graphene Functionalized PLA Nanocomposites and Their Biomedical Applications

Abstract: Nanocomposites have been emerged a major class of materials mainly due to providing multifunctional properties in a single system. Graphene is a 2-dimensional carbon-based material and has applications in many fields due to their extraordinary properties. Polylactic acid (PLA) is a biopolymer with huge scope in the biomedical field and especially in bio-engineering but has limitations due to low crystallization and week thermal and mechanical properties. Recently, Graphene-PLA based nanocomposites are investigated to overcome constraints faced by PLA polymer materials, especially for biomedical engineering. These nanocomposites have improved crystallization of PLA polymers and also enhanced mechanical strength of the polymer required for preparing different artificial organs such as tissues, bones etc. In this book chapter, a brief discussion is made on PLA and graphene, then synthesis methods for graphene composites and their functionalization on the graphene surface. Finally, biomedical applications of Graphene functionalized PLA nanocomposites have been discussed.

Synthesis, Characterization, and Study of Thermal Response of Cu-Doped Fe3O4 Nanoparticles

Abstract: Iron oxide nanoparticles (IONPs) have great importance due to their use in many biomedical applications such as contrast agents in MRI, repairing of tissues, detoxification of biological fluids, cell separation, drug delivery, immunoassay, and magnetic hyperthermia. One of the interesting properties of IONPs is to produce heat in the presence of an applied alternating magnetic field (AMF), the basic principle of magnetic hyperthermia. Here, we seek synthetic reproducibility and to optimize Fe3O4 NPs to use in magnetic hyperthermia applications. We compared the thermal efficiency of Fe3O4 NPs after doping with copper. Using co-precipitation methodology, pure and Cu-doped Fe3O4 NPs were synthesized at five different concentrations (2%, 4%, 5%, 8%, and 10%). X-ray diffraction (XRD) and scanning electron microscopy (SEM) have been used to study the crystal structure and surface morphology of nanomaterials. Fourier-transform infrared (FTIR) spectroscopy, Raman spectroscopy, and UV–visible spectroscopy were used to investigate the functional group, vibrational and optical properties of NPs. The thermal response of doped and undoped Fe3O4 NPs was studied by using high-frequency electromagnet driver for hyperthermia applications (HFEDHA) at 53 kHz frequency and 270 Oe magnetic field strength. To check the effects of suspension medium and variation of NP concentration in the sample on heat response and on specific absorption rate (SAR) values, the hyperthermia studies have been investigated in three biological mediums water, glycerol, and agar at four different NP concentrations 2%, 5%, 7%, and 10%. Our results show that at 2% concentration of copper in Fe3O4 NPs gave better results in all three mediums. However, they showed greater heat response and the highest SAR value in water than glycerol and agar. Further, at the lower concentration on NPs showed better thermal efficiency than higher concentrations.

Optical Emission Spectroscopy of Nickel-Substituted Cobalt–Zinc Ferrite

Abstract: Nanoparticles of NixZn0.5−xCo0.5Fe2O4 (x = 0, 0.1, 0.2, 0.3, 0.4, 0.5) were synthesized by co-precipitation method. Samples were characterized by X-ray diffraction and laser-induced breakdown spectroscopy. The XRD patterns of ferrites demonstrate the evidence of spinel cubic structure. Calculations show that the particle size increases and lattice parameter decreases by increasing nickel concentration. The emission characteristics of plasma generated by a Q-switched Nd:YAG laser operating at its fundamental harmonic (1064 nm) are investigated for all the six samples. Plasma temperature is calculated by Boltzmann plot method. The plasma temperature is found to decrease by decreasing laser energy and as the nickel concentration increases and zinc concentration decreases.

Quantitative Measurements of Ablative Laser Propulsion Parameters of Metal Foils Using Pulsed Nd:YAG Laser

Abstract: Recoil momentum due to ablated products in the laser ablation process is the dominant source of thrust generation. The total momentum comprises the laser-supported shock wave in background gas and the momentum due to material flow. Based on experimental studies, the dependence of laser ablation propulsion parameters of metal foils has been investigated in atmospheric air. A Q-switched Nd:YAG laser operating at fundamental (1064 nm) and second harmonics (532 nm) is used to irradiate the target. Each sample's ablation is performed over a range of laser fluence values (106 to 107 J/cm2), which is achieved by varying the incoming laser energy per pulse and adjusting the focused beam spot diameter. The results obtained from these studies showed that the laser ablation propulsion parameters are influenced by laser parameters. Moreover, the target properties also plays significant role in calculating propulsion parameters which vary with wavelength. The highest Cm is obtained for Cu irradiated with 2.2 × 10–4 Ns/J laser pulse using fundamental harmonics at low laser fluence up to 1.5 × 106 J/cm2while at the highest fluence Fe gives higher Cm 1.810–4 Ns/J because of the difference in the physical properties of metal foils. As expected, changing the energy per pulse of the laser also affects the laser ablation propulsion efficiency. The Isp for Fe is highest for both harmonics i-e 41,675 s and 3490 s, respectively. The reason behind this is that the optical properties of Fe vary by changing wavelength. Such higher Isp is required for long-range missions, so Fe proved to be the best propellant.

A Study on Thermal Response of Nanoparticles in External Magnetic Field

Abstract: Hyperthermia has become an important area of research for cancer treatment throughout the world. Choosing appropriate magnetic nanoparticles for specific performance at the cancerous site of the body is a major problem. In this research work, iron oxide nanoparticles were synthesized using laser ablation and Ag@α‑Fe2O3 and γ-Fe2O3 nanoparticles using chemical methods. The size and shape of synthesized nanoparticles were characterized by transmission electron microscopy (TEM) and scanning electron microscopy (SEM). These nanoparticles were then exposed to the alternating magnetic field in a fluid medium in a calorimeter. The heat generated by nanoparticles in the response to the applied magnetic field due through Neel relaxation and through Brown relaxation effects was measured using an array of the k-type thermometer. Their thermal responses in AC magnetic field to time regarding their types were studied. γ-Fe2O3 produced more heat, sufficient enough to kill the cancer cells selectively.

Plasmon-Based Label-Free Biosensor Using Gold Nanosphere for Dengue Detection

Abstract: In this study, a novel label-free immunosensor platform is developed to exploit the localized surface plasmon resonance (LSPR) phenomenon. The LSPR solution-based platform is designed by a gold nanospheres probe, functionalized with monoclonal anti-dengue antibody (IgG). Numerical calculations are performed to assess the LSPR extinction spectrum and spatial near electric field distribution around the nanoparticle surface. Important parameters that govern sensor performance, molecular and refractive index sensitivity are evaluated. On the evaluation of the platform as a molecular sensor, the detection of dengue NS1 antigens is presented. The results are consistent with the numerical simulations, which depicts the system’s ability to identify dengue NS1 antigen concentrations as low as 0.07 ± 0.01 µg/mL, along with fosters its potential application in plasmonic sensing.

A Comprehensive Study on Pulsed Nd:YAG Laser Irradiation of Maize Kernels: Measurement of Biophoton Emissions, Metabolite Levels and Thermodynamical Attributes During Germination

Abstract: The present study was conducted to assess the effects of different fluences of Nd:YAG pulsed laser irradiation on the kernel thermodynamic attributes and biophoton emission in relation with the changes in kernel metabolites during kernel germination. Significant changes in kernel internal energy, enthalpy change, entropy generation, entropy generation ratio, entropy flux, entropy flux ratio, and biophoton emission were observed. Lower laser fluences (200, 400 and 600 J/cm2) positively influenced these attributes in association with a rapid increase in kernel chlorophyll (Chl.), carotenoids (Car.), total soluble sugar (TSS), total reducing sugar (TRS), total free amino acids (TFAA) and free fatty acids (FFA) contents as compared to non-treated ones but the opposite was true at higher fluences (800 J/cm2 and above). Correlations and PCA analysis were performed for the studied attributes that showed strong negative correlations of kernel Chl., Car., TSS, TRS, TFAA and FFA with kernel TSP and oil contents that confer the breakdown of kernel reserves and this conversion was faster at low laser fluences. In conclusion, 200 and 400 J/cm2 fluences have been found the most beneficial ones as kernel treatment in maize for better metabolic activities to improve the germination.

Effect of Zn substitution on the structural, magnetic, optical, and electrical properties of low-temperature-synthesized cobalt ferrites

Abstract: Nano-crystalline particles of zinc-doped cobalt ferrite having chemical formula Co1−xZnxFe2O4 (x = 0.01, 0.02, 0.03, 0.04 and 0.05) were successfully synthesized via co-precipitation technique. Phase identification of cobalt-zinc ferrite nanoparticle was performed using x-ray diffraction (XRD). The increased zinc content resulted in phase change, depicted by shifting of peaks to the higher angle in cobalt ferrite samples. The lattice parameter increases with increase in zinc concentrates in accordance to Vegard’s law. The absorbance was measured by ultraviolet visible (UV–vis) spectroscopy. Increase in the band gap energy by increasing zinc ion (Zn2+) concentration has been observed. Absorbance spectrophotometer was utilized to measure the amount of light passing through zinc-concentrated solution. It was observed that absorbance decreased sharply at wavelength of 650 nm, whereas it increases to maximum values when wavelength exceeds 700 nm. Fourier transform infrared (FT-IR) spectra of zinc-doped cobalt ferrite were recorded in the spectral region of 4000–500 cm−1. The morphologies of Co1−xZnxFe2O4 samples were also analyzed using scanning electron microscope (SEM). Particles with identical and significant tendency of forming metallic cluster were observed throughout the samples.