Ascorbic Acid-Assisted Eco-friendly Synthesis of NiCo<Subscript>2</Subscript>O<Subscript>4</Subscript> Nanoparticles as an Anode Material for High-Performance Lithium-Ion Batteries

We have synthesized NiCo₂O₄ nanoparticles (NCO NPs) using an ascorbic acid-assisted co-precipitation method for the first time. When NCO NPs are used as an anode material for lithium-ion batteries, the cell exhibits superior lithium storage properties, such as high capacity (700 mA h g^?1 after 300 cycles at 200 mA g^?1), excellent rate capabilities (applied current density range 100–1200 mA g^?1), and impressive cycling stability (at 1200 mA g^?1 up to 650 cycles). The enhanced electrochemical properties of NCO NPs are due to the nanometer dimensions which not only offers a smooth charge-transport pathway and short diffusion paths of the lithium ions but also adequate spaces for volume expansion during Li storage. Hence, this eco-friendly synthesis approach will provide a new strategy for the synthesis of various nanostructured metal oxide compounds, for energy conversion and storage systems applications.     

Recycling of Bakery Waste as an Alternative Carbon Source for Rhamnolipid Biosurfactant Production

Production of a rhamnolipid biosurfactant (RBS) using discarded mixed bakery waste (BW) employing bacterial strain Pseudomonas aeruginosa strain PG1 (identified by 16 s rDNA sequencing) was investigated for bioconversion of the food waste. Dry and powder form BW was supplemented with mineral salt media (MSM) as a sole carbon source for production of RBS. RBS production was measured based on the drop collapse assay and surface tension (ST) reduction of the culture media. Production of RBS in the culture media was enhanced by optimizing the carbon source (BW) concentration and the proper nitrogen source along with the pH of the MSM. Under optimized culture conditions, 11.56 g L⁻¹ day⁻¹ crude biosurfactant (BS) was achieved. The RBS had the ability to reduce the ST of the optimized MSM from 72.0 to 25.8 mN m⁻¹ during culture, where the critical micelle concentration (CMC) of the biosurfactant was found to be 100 mg L⁻¹. Liquid Chromatography Mass Spectroscopy (LC-MS), Fourier Transform Infrared spectroscopy (FTIR), and scanning electron microscopy (SEM)–energy dispersive X-ray spectroscopy (EDS) analyses of the purified BS confirmed that it is of rhamnolipid in nature and it is made up of both monorhamnolipid and dirhamnolipid congeners. Furthermore, the RBS did not express any cytotoxic effect on the cell line of mouse L292 fibroblastic cell indicating the biosafety nature of the high-value biomolecule.     

Removal of toxic metal Cr(VI) from aqueous solutions using sawdust as adsorbent: Equilibrium, kinetics and regeneration studies

In the present study, a low-cost adsorbent is developed from the naturally and abundantly available sawdust which is biodegradable. The removal capacity of Cr(VI) from aqueous solutions and from the synthetically prepared industrial effluent of electroplating and tannery industries is obtained. The batch experiments are carried out to investigate the effect of the significant process parameters such as initial pH, change in pH during adsorption, contact time, adsorbent amount, and the initial Cr(VI) concentration. The maximum adsorption of Cr(VI) on sawdust is obtained at an initial pH value of 1. The value of pH increases with increase in contact time and initial Cr(VI) concentration. The equilibrium data for the adsorption of Cr(VI) on sawdust is tested with various adsorption isotherm models such as Langmuir, Freundlich, Redlich–Peterson, Koble–Corrigan, Tempkin, Dubinin–Radushkevich and Generalized equation. The Langmuir isotherm model is found to be the most suitable one for the Cr(VI) adsorption using sawdust and the maximum adsorption capacity obtained is 41.5 mg g⁻¹ at a pH value of 1. The adsorption process follows the second-order kinetics and the corresponding rate constants are obtained. Desorption of Cr(VI) from sawdust using acid and base treatment exhibited a higher desorption efficiency by more than 95%. A feasible solution is proposed, for the disposal of the contaminant (acid and base solutions) containing high concentration of Cr(VI) obtained during the desorption process. The interference of other ions which are generally present in the electroplating and tannery industrial effluent streams on the Cr(VI) removal is investigated.     

The study of lithium ion de-insertion/insertion in LiMn2O4 and determination of kinetic parameters in aqueous Li2SO4 solution using electrochemical impedance spectroscopy

In this work, we report a basic study on the mechanism of lithium ion de-insertion/insertion process from/into LiMn₂O₄ cathode material in aqueous Li₂SO₄ solution using electrochemical impedance spectroscopy (EIS). An equivalent circuit distinguishing the kinetic parameters of lithium ion de-insertion/insertion is used to simulate the experimental impedance data. The fitting results are in good agreement with the experimental results and the parameters of the kinetic process of Li⁺ de-insertion and insertion in LiMn₂O₄ at different potentials during charge and discharge are obtained using the same circuit. The results indicate that the de-insertion/insertion behavior of lithium ions at LiMn₂O₄ cathode in Li₂SO₄ aqueous solution is similar to that reported in the organic electrolytes. The charge transfer resistance (R_ct), warburg resistance, double layer capacitance and chemical diffusion coefficient (DLi+) vary with potentials during de-insertion/insertion processes. R_ct is lowest at the CV peak potentials and the important kinetic parameter, DLi+ exhibits two distinct minima at potentials corresponding to CV peaks during de-insertion–insertion and it was found to be between 10⁻⁸ and 10⁻¹⁰ cm² s⁻¹during lithium de-insertion/insertion processes.     

Synthesis of Nanocrystalline Lanthanum Strontium Manganite Powder by the Urea–Formaldehyde Polymer Gel Combustion Route

Nanocrystalline lanthanum strontium manganite (LSM) powder has been synthesized by combustion of a transparent gel obtained by the polymerization of methylol urea and urea in a solution containing La³⁺, Sr²⁺, and Mn²⁺ (LSM ions). Chemistry of the transparent urea–formaldehyde (UF) polymer gel formation and structure of the gel have been proposed such that the LSM ions act in between the growing UF polymer chains by interacting through NH, OH, and CO groups by co-ordination and prevent polymer self-assembly through inter-chain hydrogen bonding as evidenced from infrared spectrum. Thermally stable structures formed by the decomposition of UF polymer below 300°C undergo combustion in the presence of nitrate oxidant in a temperature range from 350°–450°C. A perovskite LSM phase has been formed by self-sustained combustion of the dried gel initiated with little kerosene. The powder obtained after deagglomeration and calcination at 600°C for 2 h has a D ₅₀ value of 0.19 μm, and the particles are aggregates of crystallites 10–25 nm in size.     

Spectroscopic and photoluminescence properties of Dy-doped lead tungsten tellurite glasses for laser materials

Lead tungsten tellurite (LTT) glasses doped with different Dy³⁺ ion concentrations have been prepared and characterized through optical absorption, photoluminescence and decay measurements. The glassy nature of the LTT host has been confirmed through the XRD measurements. The three phenomelogical intensity parameters Ω_λ (λ = 2, 4, 6) have been determined from the absorption spectral intensities using the Judd-Ofelt (J-O) theory. The hypersensitivity of ⁶H_15/2 → ⁶F_11/2 transition based on the magnitude of Ω₂ parameter has also been discussed. By using the J-O intensity parameters several radiative properties such as spontaneous transition probabilities (A_R), fluorescence branching ratios (β_R) and radiative lifetimes (τ_R) have been determined. The effect of Dy³⁺ ion concentration on the emission intensities of ⁴F_9/2 → ⁶H_J′ (J′ = 15/2, 13/2, 11/2 and 9/2) transitions has also been reported.     

Simplified Impedance Model for Adhesively Bonded Piezo-Impedance Transducers

The electromechanical impedance technique employs surface-bonded lead zirconate titanate piezoelectric ceramic patches as impedance transducers for structural health monitoring and nondestructive evaluation. The patches are bonded to the monitored structures using finitely thick adhesive bond layer, which introduces shear lag effect, thus invariably influencing the electromechanical admittance signatures. This paper presents a new simplified impedance model to incorporate shear lag effect into electromechanical admittance formulations, both one-dimensional and two-dimensional. This provides a closed-form analytical solution of the inverse problem, i.e. to derive the true structural impedance from the measured conductance and susceptance signatures, thus an improvement over the existing models. The influence of various parameters (associated with the bond layer) on admittance signatures is investigated using the proposed model and the results compared with existing models. The results show that the new model, which is far simpler than the existing models, models the shear lag phenomenon reasonably well besides providing direct solution of a complex inverse problem.     

Influence of Sorption Intensity on Solute Mobility in a Fractured Formation

Diffusive mass transfer between fracture and matrix accompanied with sorption significantly influences the efficiency of natural attenuation in hard rocks. While these processes have extensively been studied in a fractured formation, limited information exists on the sorption nonlinearity. For this purpose, a numerical model is developed that couples matrix diffusion and nonlinear sorption at the scale of a single fracture using the dual-porosity concept. The study is limited to a constant continuous solute source boundary condition. The influence of both favorable and unfavorable sorption intensities on solute mobility is investigated using the method of spatial moments. The differing capacities of available sorption sites between fracture surfaces at the fracture-matrix interface and the solid grain surfaces within the rock matrix result in a slower migration of solutes along the fracture, and a larger amount of diffusive mass transfer away from the high permeability fracture.     

Systemic inflammatory load in humans is suppressed by consumption of two formulations of dried,encapsulated juice concentrate

Chronic inflammation contributes to an increased risk for developing chronic conditions such as cardiovascular disease, diabetes, and cancer. A high “inflammatory load” is defined as elevated inflammation markers in blood or other tissues. We evaluated several markers of systemic inflammation from healthy adults and tested the hypothesis that two formulations of encapsulated fruit and vegetable juice powder concentrate with added berry powders (FVB) or without (FV) could impact markers of inflammatory load. Using a double‐blind, placebo‐controlled approach, 117 subjects were randomly assigned to receive placebo, FV, or FVB capsules. Blood was drawn at baseline and after 60 d of capsule consumption. We measured inflammatory markers (high sensitivity C‐Reactive Protein, Monocyte Chemotactic Protein‐1, Macrophage Inflammatory Protein 1‐β, and Regulated upon Activation, Normal T cell Expressed and Secreted), superoxide dismutase, and micronutrients (β‐carotene, vitamin C, and vitamin E). Results showed Monocyte Chemotactic Protein‐1, Macrophage Inflammatory Protein 1‐β, and RANTES levels were significantly reduced and superoxide dismutase and micronutrient levels were significantly increased in subjects consuming both FV and FVB, relative to placebo. Data suggest a potential health benefit by consuming either formulation of the encapsulated juice concentrates through their anti‐inflammatory properties.     

Statistical analysis of the fracture strengths of aluminum alloy–alumina (Al<Subscript>2</Subscript>O<Subscript>3</Subscript>) particulate composites

The mechanics of composite materials and their “fracture behaviors” are relatively complex phenomena to analyze and establish due to their inconsistent process stability and reliability, combined with production and related processing problems. In this work, an attempt has been made to statistically analyze the tensile behavior of metal matrix composites. Composites of aluminum alloy containing 5–20% volume fraction of Al₂O₃ particles of 15 μm size were prepared by adding alumina particles to a vigorously agitated semi-solid aluminum alloy. Prior to this, alumina particles were subjected to preheating at 800 °C for 5 h. Particles were then added to the aluminum alloy and further heated to 850 °C by using a mixer in a nitrogen medium. A total of 20 tension tests were performed for each volume fraction according to ASTM Standards B557 and using these test data, the initial estimators for an empirical model were obtained. Using this empirical model, the reliability of the composite characteristics in terms of its tensile strength was assessed. Another significant implication of the present study is proving the ability and utility of the Weibull statistical distribution for describing the experimentally measured data on the tensile strength of metal matrix composites, in a more appropriate manner.