Solving nonlinear reaction–diffusion problem in electrostatic interaction with reaction-generated pH change on the kinetics of immobilized enzyme systems using Taylor series method

A mathematical model of electrostatic interaction with reaction-generated pH change on the kinetics of immobilized enzyme is discussed. The model involves the coupled system of non-linear reaction–diffusion equations of substrate and hydrogen ion. The non-linear term in this model is related to the Michaelis–Menten reaction of the substrate and non-Michaelis–Menten kinetics of hydrogen ion. The approximate analytical expression of concentration of substrate and hydrogen ion has been derived by solving the non-linear reactions using Taylor’s series method. Reaction rate and effectiveness factor are also reported. A comparison between the analytical approximation and numerical solution is also presented. The effects of external mass transfer coefficient and the electrostatic potential on the overall reaction rate were also discussed.

     

Investigations of gold nanoparticles-mediated carbon nanotube reinforced hydroxyapatite composite for bone regenerations

An excellent combination of biomaterials permits prompt features and high-throughput investigations in various fields, particularly in the biomedical applications. This article investigates the bone regeneration ability and compatibility of the Gold (Au) Nanoparticles (NPs) medicated carbon nanotube reinforced hydroxyapatite (HAP) composite. The morphologies of the synthesized Au NPs, HAP and HAP/CNT, and HAP/CNT-Au composites vary suggestively with modifying the components and the final composite showing as bone mimic extracellular matrix morphology. The structure, phase, and composition of the as-synthesized HAP were studied by FTIR, XRD, EDAX, and TEM techniques. The materials' biocompatibility was investigated in the Stimulated Body Fluid (SBF) solution, which resulted in the composite having good biocompatibility, bioactivity nature and hydroxyapatite layer formed on the composite surface. The composite shows good viability with Adipose Tissue-derived Stem Cells (ADSC) to cell growth and cell proliferation in the biological evaluation. It represented the composites having a good ability for cell formation development. Since the HAP/CNT-Au composite are useful in medicinal applications such as orthopedic and orthodontic repair/regenerations after the evaluations of animal and clinical investigations.     

L-Proline catalyzed three component synthesis of pyrano[2,3-c]pyrazole-5-carbonitrile derivatives and in vitro antimalarial evaluation

An efficient one-pot synthesis of 6-amino-4-(2-chloroquinolin-3-yl)-3-methyl-2, 4-dihydro-pyrano[2,3-c]pyrazole-5-carbonitrile derivatives (4a–f)(5a–f) by three component reactions of 2-chloroquinolin-3-carbaldehyde derivatives, malanonitrile, and 3-methyl pyrazolin-5-one derivatives catalyzed by L-proline in ethanol medium under mild conditions is established. The synthesized compounds were evaluated for antimalarial activity and the LC₅₀/LC₉₀ values were described. Compounds 4d, 5d, and 5f exhibits good antimalarial activity when compared to other pyrano[2,3-c]pyrazole scaffolds.     

Smartphone based bacterial detection using biofunctionalized fluorescent nanoparticles

We are describing immunochromatographic test strips with smart phone-based fluorescence readout. They are intended for use in the detection of the foodborne bacterial pathogens Salmonella spp. and Escherichia coli O157. Silica nanoparticles (SiNPs) were doped with FITC and Ru(bpy), conjugated to the respective antibodies, and then used in a conventional lateral flow immunoassay (LFIA). Fluorescence was recorded by inserting the nitrocellulose strip into a smart phone-based fluorimeter consisting of a light weight (40 g) optical module containing an LED light source, a fluorescence filter set and a lens attached to the integrated camera of the cell phone in order to acquire high-resolution fluorescence images. The images were analysed by exploiting the quick image processing application of the cell phone and enable the detection of pathogens within few minutes. This LFIA is capable of detecting pathogens in concentrations as low as 10⁵ cfu mL⁻¹ directly from test samples without pre-enrichment. The detection is one order of magnitude better compared to gold nanoparticle-based LFIAs under similar condition. The successful combination of fluorescent nanoparticle-based pathogen detection by LFIAs with a smart phone-based detection platform has resulted in a portable device with improved diagnosis features and having potential application in diagnostics and environmental monitoring.

The successful combination of fluorescent nanoparticle-based pathogen detection by lateral flow immunoassay with a smart phone-based detection platform has resulted in a portable device that enables rapid and reliable bacterial detection holding large potential in diagnostics and environmental monitoring

     

The main injector particle production experiment at Fermilab

We describe the physics capabilities and status of the MIPP experiment which concluded its physics data taking run in March 2006. We show some preliminary results from this run and describe plans to upgrade the spectrometer.     

Silicon nanowires for sequence-specific DNA sensing: device fabrication and simulation

Highly sensitive, sequence-specific and label-free DNA sensors were demonstrated by monitoring the electronic conductance of silicon nanowires (SiNWs) with chemically bonded single-stranded (ss) DNA or peptide nucleic acid (PNA) probe molecules. For a 12-mer oligonucleotide, tens of pM of target ss-DNA in solution was recognized when the complementary DNA oligonucleotide probe was attached to the SiNW surfaces. In contrast, ss-DNA samples of ×1000 concentration with a single-base mismatch produce only a weak signal due to nonspecific binding. In order to gain a physical understanding of the change in conductance of the SiNWs with the attachment of the DNA targets and the probes, process and device simulations of the two-dimensional cross sections of the SiNWs were performed. The simulations explained the width dependence of the SiNW conductance and provided understanding to improve the sensor performance. PACS 85.35.-p; 87.83.+a; 07.07.Df     

Selective synthesis of ureas and tetrazoles from amides controlled by experimental conditions using conventional and microwave irradiation

An efficient synthetic procedure has been achieved for selective synthesis of 1,5-disubstituted tetrazoles and diaryl ureas from secondary amides in situ in the presence of NaN₃ and POCl₃ as solvent, both by conventional and microwave methods. The reaction conditions were optimized to yield selectively either tetrazoles or urea derivatives from reasonable to excellent yields. These conversions have been tested and verified with various secondary amide precursors. The synthesized compounds were characterized by ¹H NMR, ¹³C NMR and ESI-MS spectroscopic techniques.     

Antimicrobial flavonoids isolated from Indian medicinal plant Scutellaria oblonga inhibit biofilms formed by common food pathogens

Scutellaria oblonga Benth., a hitherto phytochemically unexplored Indian medicinal folklore plant was extracted with acetone and subjected to chromatography to yield nine flavonoids, for the first time from this plant. Antimicrobial assays were performed against 11 foodborne pathogens, and three molecules (Techtochrysin, Negletein and Quercitin-3-glucoside) depicted significant activity. These molecules were assessed for their rate of antibacterial action using time–kill curves which depicted complete inhibition of most of the bacteria within 12–16 h. The significant biofilm-reducing capability exhibited by these three molecules formed a significant finding of the current study. In most of the experiments, a 90–95% reduction in biofilms was observed. Thus, flavonoids as natural molecules from S. oblonga could be further researched to be used as potent antimicrobial and antibiofilm agents.     

Mathematical modeling and analysis of the molar concentrations of ethanol,acetaldehyde and ethyl acetate inside the catalyst particle

Mathematical modeling of the molar concentrations profile of ethanol, acetaldehyde and ethyl acetate inside the catalyst particle is presented. This kinetic mechanism is based on the system of non-linear reaction diffusion equations. Modified Adomian decomposition method is employed to derive the general analytical expressions of molar concentrations of ethanol, acetaldehyde and ethyl acetate for all possible values of the parameters Φ_i, γ_i and α_i (i = 1, 2, 3). Analytical results are compared with the numerical results, a satisfactory agreement is noted. Valid and invalid region of the solution for all concentrations are provided. These analytical results are useful to understand the behavior of the system.