Abdur Rahman Khan

Bioactive behavior of silicon substituted calcium phosphate based bioceramics for bone regeneration.

Bone graft substitutes are widely used for bone regeneration and repair in defect sites resulting from aging, disease, trauma, or accident. With invariably increasing clinical demands, there is an urgent need to produce artificial materials, which are readily available and are capable of fast and guided skeletal repair. Calcium phosphate based bioactive ceramics are extensively utilized in bone regeneration and repair applications. Silicon is often utilized as a substituent or a dopant in these bioceramics, since it significantly enhances the ultimate properties of conventional biomaterials such as surface chemical structure, mechanical strength, bioactivity, biocompatibility, etc. This article presents an overview of the silicon substituted bioceramics, which have emerged as efficient bone replacement and bone regeneration materials. Thus, the role of silicon in enhancing the biological performance and bone forming capabilities of conventional calcium phosphate based bioceramics is identified and reviewed.

Efficient Photocatalytic Degradation of Norfloxacin in Aqueous Media by Hydrothermally Synthesized Immobilized TiO2/Ti Films with Exposed {001} Facets

In this study, a novel immobilized TiO2/Ti film with exposed {001} facets was prepared via a facile one-pot hydrothermal route for the degradation of norfloxacin from aqueous media. The effects of various hydrothermal conditions (i.e., solution pH, hydrothermal time (HT) and HF concentration) on the growth of {001} faceted TiO2/Ti film were investigated. The maximum photocatalytic performance of {001} faceted TiO2/Ti film was observed when prepared at pH 2.62, HT of 3 h and at HF concentration of 0.02 M. The as-prepared {001} faceted TiO2/Ti films were fully characterized by field-emission scanning electron microscope (FE-SEM), X-ray diffraction (XRD), high resolution transmission electron microscope (HR-TEM), and X-ray photoelectron spectroscopy (XPS). More importantly, the as-prepared {001} faceted TiO2/Ti film exhibited excellent photocatalytic performance toward degradation of norfloxacin in various water matrices (Milli-Q water, tap water, river water and synthetic wastewater). The individual influence of various anions (SO42-, HCO3-, NO3-, Cl-) and cations (K+, Ca2+, Mg2+, Cu2+, Na+, Fe3+) usually present in the real water samples on the photocatalytic performance of as-prepared TiO2/Ti film with exposed {001} facet was investigated. The mechanistic studies revealed that •OH is mainly involved in the photocatalytic degradation of norfloxacin by {001} faceted TiO2/Ti film. In addition, norfloxacin degradation byproducts were investigated, on the basis of which degradation schemes were proposed.

Acidogenic Fermentation: Utilization of Wasted Sludge as a Carbon Source in the Denitrification Process

Laboratory scale batch experiments were conducted at 20°C to investigate the acidogenic fermentation for the conversion of wasted sludge into short chain fatty acids (SCFA) to be utilized as a carbon source in the denitrification process. Hydraulic retention time (HRT), volatile solid (VS) loading rate and pH were studied as these are the important parameters governing the production of volatile fatty acids (VFA). Four different phases were investigated by varying these parameters. HRT was varied from 2.7 to 8.2 days whereas VS loading rate was varied from 1.2 to 3.6 g d−1. VFA production decreased with the increase in HRT above 2.7 days. 538.37±19.39 mg VFAproduced l−1. d−1 (0.176±0.010 mg VFAproduced mg−1 VSfeed) was found as the maximum value of VFA at 2.7 days. The present results based on wasted sludge showed that almost 0.0483±0.0016 mg VFA (as COD mg−1 initial COD) and about 5 % of soluble COD production were achieved, which are slightly less than the results reported for primary sludges. The rates of VFA production increased with the increase in VS, however, opposite results were obtained when pH was increased in the reactor. SCFA/FA ratios during fermentation were found in the range of 67-73 %. The specific denitrification rates (SDNR) of methanol (2.20±0.44mg NO3-N g−1 MLVSS · h−1) and the fermenter supernatant (2.00±0.45 mg NO3-N g−1 MLVSS · h−1) were found to be comparable. Fermenter supernatant, therefore, has the potential to be utilized as a carbon source. However, the results need to be investigated further on a larger scale to ascertain their validity.

Biosurfactant production by rhodococcus rubra

Abstract The growth of Rhodococcus rubra was studied in shake flasks to examine the conditions for biosurfactant yield. The substrates used were 3.34% Czapek medium (Cz) and Czapek medium supplemented with 0.2% yeast extract (YCz). Serial dilutions were used to determine the critical micelle concentrations (CMC) of the cultures over a 6 day growth cycle. The surface active material produced by the growth of R. rubra had two CMC values, the magnitude of which varied with the length of the growth period. The binding of the biosurfactant was studied in a larger fermentation and the results suggest that the material is not cell bound.

Evaluation of electrical, dielectric and magnetic characteristics of Al–La doped nickel spinel ferrites

The paper reports the effects of lanthanum and aluminum ions, on the structural, electrical and magnetic properties of NiFe2O4 spinel ferrite nanoparticles. The precursors have been synthesized via a hydrothermal route in the presence of ascorbic acid (AA) using urea as a reducing agent and fuel for maintaining the uniform morphology and equal particle size distribution. In order to find out the optimum temperature (1023 K) for the formation of the spinel phase of the doped nickel ferrite, thermogravimetric analysis (TGA) for the un-annealed samples was performed. The X-ray diffraction patterns show that NiFe2−2xAlxLaxO4 have been well crystallized to spinel ferrite crystal structure with the Fd3m space group. The average crystallite size obtained is in the range of 9–19 nm, a size useful for attaining a suitable signal-to-noise ratio in high-density recording media and in electrical devices. In order to render the synthesized samples for diminishing eddy current losses, we were able to enhance the room temperature resistivity through proper selection of dopant used. The dielectric constant and dielectric loss decreased with applied frequency for all the samples showing normal behavior of ferrites. The calculated magnetic parameters such as saturation magnetization (Ms), remanence (Mr) and coercivity (Hc), showed increased values for some Al–La doped samples.

Aspects of the nutrition and the growth of rhodococcus rubra in relation to the formation of stable foams

Abstract The formation of stable foams on activated sludge plants has been associated with specific microbial species, a lowering of the surface tension and the presence of fats and oils in the incoming sewage. This paper examines one of the causative microbes; Rhodococcus rubra; and in particular, how its growth and surface activity changed during fermentations in which the substrates had been supplemented with a range of straight chain alkanes or with the corresponding carboxylic acids. The results showed that the alkane supplements did enhance the growth; the degree of enhancement increasing with chain length. However, no growth was obtained with the lower (< C‐13) acids.

An investigation into the stability of foams related to the activated sludge process.

A pneumatic method was used to measure the foaming potential of activated sludges from three different sewage works. The results were then compared with the foams produced by one of the microbes often associated with the production of stable form, Rhodococcus rubra, and by a crude extract of the biosurfactant produced by R. rubra. The results show that there is a marked similarity between the foams associated with R. rubra and those produced by dispersions of foam solids obtained from a full-scale activated sludge plant and that there appear to be critical values of surface tension, biomass, and biosurfactant for foaming and stability to occur. The results also indicate the potential of the test for assessing the risk of stable foam formation.

Bioassay-Guided Isolation of Sesquiterpene Coumarins from Ferula narthex Bioss: A New Anticancer Agent

[This corrects the article on p. 26 in vol. 7, PMID: 26909039.].The main objective of cancer management with chemotherapy (anticancer drugs) is to kill the neoplastic (cancerous) cell instead of a normal healthy cell. The bioassay-guided isolation of two new sesquiterpene coumarins (compounds 1 and 2) have been carried out from Ferula narthex collected from Chitral, locally known as “Raw.” Anticancer activity of crude and all fractions have been carried out to prevent carcinogenesis by using MTT assay. The n-hexane fraction showed good activity with an IC50 value of 5.434 ± 0.249 μg/mL, followed by crude MeFn extract 7.317 ± 0.535 μg/mL, and CHCl3 fraction 9.613 ± 0.548 μg/mL. Compounds 1 and 2 were isolated from chloroform fraction. Among tested pure compounds, compound 1 showed good anticancer activity with IC50 value of 14.074 ± 0.414 μg/mL. PASS (Prediction of Activity Spectra) analysis of the compound 1 was carried out, in order to predicts their binding probability with anti-cancer target. As a results the compound 1 showed binding probability with human histone acetyltransferase with Pa (probability to be active) value of 0.303. The compound 1 was docked against human histone acetyltransferase (anti-cancer drug target) by using molecular docking simulations. Molecular docking results showed that compound 1 accommodate well in the anti-cancer drug target. Moreover the activity support cancer chemo preventive activity of different compounds isolated from the genus Ferula, in accordance with the previously reported anticancer activities of the genus.

HYDROXYL RADICAL BASED DEGRADATION OF CIPROFLOXACIN IN AQUEOUS SOLUTION

This study reports the degradation of ciprofloxacin (CIP) by means of ionizing radiations. Kinetic studies with aqueous concentrations of 4.6, 10, 15, 17.9 mg/L reveals that degradation of CIP follows pseudo -first order kinetics and the decay constant increased with decrease in initial concentration of CIP. The removal efficiency, represented by G-value, decreased with increasing absorbed dose and increased with higher [CIP] 0 concentration at a given absorbed dose. The effects of bubbling CIP solution with N 2 , N 2 O or air on CIP degradation were also studied. The influence of various radical scavengers like tert -butanol, iso -propanol, HCO 3 - , CO 3 2- , NO 3 - and NO 2 - as radical scavengers in N 2 - saturated solutions of CIP indicated that •OH were more closely associated with the radiolytic decomposition of CIP than other radicals, such as e - aq or •H. The pH value of aqueous media played a crucial role in the degradation of CIP. It was observed that degradation efficiency was higher under acidic condition compared to degradation in natural or alkaline media. F - , CH 3 COO - and HCOO - were formed as a result of CIP degradation that were analyzed by ion-chromatography.

Switchable dispersive liquid–liquid microextraction for lead enrichment: a green alternative to classical extraction techniques

A new, innovative and green switchable dispersive liquid–liquid microextraction (SDLLME) method has been introduced as a preconcentration tool for the removal of the toxic metal lead (Pb) in fresh and waste water samples prior to determination with flame atomic absorption spectrometry. We developed a switchable polarity solvent (SPS) system, based on 1,8-diazabicyclo[5.4.0]undec-7-ene and decanol, which was reversibly switched on and off from heterogeneous biphasic nonpolar hydrophobic phase to homogeneous monophasic polar hydrophilic phase in an aqueous medium through exposure to an anti-solvent trigger (CO2) for a specific interval of time (1–10 min). Then, an SPS of polar microemulsions was switched on from a polar phase through bubbling CO2 followed by switching off to a nonpolar phase by heating in the range of 40–70 °C in the presence of N2 gas. The switching phenomenon of SPS from low polarity to high polarity was confirmed by FTIR spectrophotometry and conductivity measurements. SDLLME was successfully applied as an extracting method for the preconcentration of a hydrophobic chelate of Pb with 1-(2-pyridylazo)-2-naphthol (Pb-PAN) from a real water system. Then hydrophobic-enriched Pb-PAN-SPS was treated with a 1.5 mol L−1 HNO3 and CO2 purge for different time intervals, to switch back to its miscible polar hydrophilic monophasic state. The recovery of SPS was carried out by heating at 55 °C and purging with N2 gas. The SPS was easily recycled up to 12 times with >2% loss of efficiency of the developed method. Under the optimized experimental conditions, the limit of detection and the enhancement factor were determined to be 0.25 μg L−1 and 50, respectively.