Muhammad Ishaq

Synthesis, characterization, and application of Au–Ag alloy nanoparticles for the sensing of an environmental toxin, pyrene

AbstractnBimetallic alloy nanoparticles (NPs) of two coinage metals, Au and Ag, were successfully synthesized by a co-precipitation method. These NPs were prepared by a chemical method involving the reduction of HAuCl4 and AgNO3 in an aqueous solution of 2xa0% hydrazine as a reducing agent, iso-octane as a co-precipitator, cetyl trimethyl ammonium bromide as a capping agent, and deionized water as a solvent. The newly synthesized bimetallic alloy NPs were characterized by electronic absorption spectroscopy. The NPs were further characterized by scanning electron microscopy, transmission electron microscopy (TEM), and energy-dispersive spectroscopy. TEM evidenced the formation of NPs with a diameter ranging from 25 to 35xa0nm. For the development of electrochemical sensor, glassy carbon electrode (GCE) was modified with potentiodynamic polymerization of pyrrole, called polypyrrole (PPy). PPy was over-oxidized in order to increase its sensitivity toward polyaromatic hydrocarbons. The electrode was further modified with Au–Ag bimetallic alloy NPs. The fabricated GCE was successfully applied to detect an environmental toxin, pyrene. The electrochemical behavior of pyrene at the composite electrode (PPyox/Au–Ag NPs/GCE) was optimized by changing the atomic ratio of Au and Ag in Au–Ag bimetallic alloy NPs. At the Au and Ag ratio of 1:3, pyrene was detected with a detection limit of 0.1xa0µM.

Antimicrobial activities of Conyzolide and Conyzoflavone from Conyza canadensis

Antibacterial and antifungal activities of the two isolated compounds from Conyza canadensis have been reported in the current study. The two isolated compounds i.e. Conyzolide (1) and Conyzoflavone (2) were tested against six bacterial and five fungal strains, employing hole diffusion and macrodilution methods. Both the compounds showed significant activities against the tested pathogens with special reference to E. coli, P. aeruginosa, S. aureus, Trichophytom longifusus, C. albicans, and C. glaberata. Conyzolide revealed comparatively better antibacterial activity against E. coli (minimum inhibitory concentration (MIC): 25 µg/mL) in comparison to Conyzoflavone. However, in case of antifungal activities, Conyzoflavone exhibited superior antifungal activity against C. albicans (MIC: 10 µg/mL) as compared to Conyzolide.

Spectroscopic Analysis of Au-Cu Alloy Nanoparticles of Various Compositions Synthesized by a Chemical Reduction Method

Au-Cu alloy nanoparticles were synthesized by a chemical reduction method. Five samples having different compositions of Au and Cu (Au-Cu 3u2009:u20091, Au-Cu 2u2009:u20091, Au-Cu 1u2009:u20091, Au-Cu 1u2009:u20092, and Au-Cu 1u2009:u20093) were prepared. The newly synthesized nanoparticles were characterized by electronic absorption, fluorescence, and X-ray diffraction spectroscopy (XRD). These alloy nanoparticles were also analyzed by SEM and TEM. The particle size was determined by SEM and TEM and calculated by Debye Scherrer’s equation as well. The results revealed that the average diameter of nanoparticles gets lowered from 80 to 65u2009nm as the amount of Cu is increased in alloy nanoparticles. Some physical properties were found to change with change in molar composition of Au and Cu. Most of the properties showed optimum values for Au-Cu alloy nanoparticles of 1u2009:u20093. Cu in Au-Cu alloy caused decrease in the intensity of the emission peak and acted as a quencher. The fluorescence data was utilized for the evaluation of number of binding sites, total number of atoms in alloy nanoparticle, binding constant, and free energy of binding while morphology was deduced from SEM and TEM.

Enrichment, spatial distribution of potential ecological and human health risk assessment via toxic metals in soil and surface water ingestion in the vicinity of Sewakht mines, district Chitral, Northern Pakistan

This study focuses on enrichment, spatial distribution, potential ecological risk index (PERI) and human health risk of various toxic metals taken via soil and surface water in the vicinity of Sewakht mines, Pakistan. The samples of soils (nu202f=u202f54) of different fields and surface water (nu202f=u202f38) were analyzed for toxic metals including cadmium (Cd), cobalt (Co), chromium (Cr), copper (Cu), iron (Fe), manganese (Mn), lead (Pb), nickel (Ni), zinc (Zn) and molybdenum (Mo). Soil pollution level was evaluated using pollution indices including geo-accumulation index (Igeo), contamination factor (CF), degree of contamination (CD), enrichment factor (EF) and PERI. CF showed moderate contamination of soil with Cd, Co, Fe and Mo, while Igeo values indicated moderate accumulation of Cu. For Cd, EF>u202f1.5 was found in agricultural soils of the study area. PERI findings presented a very high ecological risk (PERI >u202f380) at two sites (4%), considerable ecological risk at four sites (7.4%). Non-carcinogenic risk from exposure to Fe in soil was higher than limit (HI >u202f1) for both children and adults. Moreover, carcinogenic risk postured by soil contaminants i.e. Cd, Cr, Co and Ni in children was higher than their limits (except Pb), while in adults only Co posed higher risk of cancer than the limit (10-4) through soil exposure. Non-carcinogenic risks in children due to Cd, Co, Mo via surface water intake were higher than their safe limits (HQ >u202f1), while in adults the risk order was Cr >u202fCd >u202fCu >u202fPb >u202fCo >u202fMo. Moreover, carcinogenic risk exposure due to Co >u202fCd >u202fCr >u202fNi from surface water (except Pb) was higher than the tolerable limit (1u202f×u202f10-4) both for children and adults. However, Pb concentrations in both soil and surface water exposure were not likely to cause cancer risk in the local population.

EFFECT OF COAL ASH ON THE MORPHOLOGICAL, THERMAL AND MECHANICAL PROPERTIES OF POLY(METHYL METHACRYLATE)

ABSTRACT Composite materials of Coal ash/ Poly(Methyl Methacrylate) (ash/PMMA) were prepared/synthesized and their properties were studied by scanning electron microscopy (SEM), polarized optical microscopy (POM), differential scanning calorimetry (DSC), thermogravimetric analyzer (TGA) and universal testing machine (UTM). The morphological study presented that the ash particles were well dispersed and embedded within the PMMA matrix. The DSC thermograms showed that the melting temperature (T m ) of pure PMMA is about 166 o C which was shifted towards lower temperature when ash were incorporated in the polymer matrix. The mechanical properties of the ash/PMMA composites were enhanced up to an optimum level (ash 3 wt %) and then decreased at higher incorporation of large quantity of filler. The TGA thermograms indicated that the thermal stability of the ash/PMMA composite was enhance significantly than pure PMMA. Key words: Coal ash, PMMA, SEM, TGA INTRODUCTION Polymer composites reinforced with fillers/reinforced materials have paid significant attention due to the unique physical, mechanical, thermal and electrical properties of the reinforced materials. Extensive research is going on the polymer/reinforcing composite materials, in which they incorporated various kinds of fillers like carbon fiber, graphite, carbon nanotubes, nanoclay, etc. into the polymer matrix. The various properties such as electrical, mechanical, and thermal stability of the polymer improved significantly by incorporation of small amount of reinforcing materials. Xiang et al.

Pyrazinium thioacetate capped gold nanoparticles as Fe(III) sensor and Fe(III) marked anti-proliferating agent in human neuroblastoma cells

Gold nanoparticles (AuNPs) stabilized by new cationic 1‑(3‑(acetylthio)propyl)pyrazin‑1‑ium ligand (PPTA) were synthesized. AuNPs stabilized by PPTA (PPTA-AuNPs) were found to be spherical and polydispersed with the average size of 60u202fnm. Human neuroblastoma (SHSY-5Y) cells permeability of PPTA-AuNPs was found to be a key feature to study the intracellular quenching of Fe(III) proliferative activity. In vitro MTT assay revealed non-cytotoxicity of PPTA and PPTA-AuNPs at 100u202fμM concentration, while treatment of 100u202fμM of Fe(III) with SHSY-5Y cells resulted into higher cells viability. Contrary, a mixture of 1:1 Fe(III) with PPTA-AuNPs showed no change in the viability of cells at same concentration which suggests the intracellular complexation and recognition of Fe(III) by PPTA-AuNPs. AFM morphological analysis of SHSY-5Y cells also supported the MTT assay results, and it is safe to conclude that PPTA-AuNPs can be used as Fe(III) probes in living cells. In addition, Fe(III) caused a significant decrease in the absorbance of surface plasmon resonance (SPR) band of PPTA-AuNPs in a wide range of concentration and pH, with limit of detection 4.3u202fμM. Moreover, the specific response of PPTA-AuNPs towards Fe(III) was unaffected by the interference of other metals and components of real samples of tap water.

Microfacies and diagenetic studies of the early Eocene Sakesar Limestone, Potwar Plateau, Pakistan: approach of reservoir evaluation using outcrop analogue

The early Eocene Sakesar Limestone of the Salt Range has been investigated in detail for microfacies analysis, depositional modeling, diagenesis and reservoir characterization. This research work was comprised of two outcrop sections, i.e., Nilawahan Gorge Section (NGS) and Katas Temple Sections (KTS) of the Sakesar Limestone, central and eastern Salt Range, Potwar Plateau. This work is mainly concentrated on investigating and evaluating the reservoir quality through depositional and diagenetic fabrics. The depositional, diagenetic and deformational processes are controlling factors of porosity and permeability distribution. On the basis of relative estimated ratio of allochemical constituents and micrite, five microfacies have been recognized. These microfacies are: Benthonic Foraminiferal wackestone, Foraminiferal-Algal wackestone–packstone, Miliolidal-Algal wackestone–packstone, Nummulitic-Assilina Packstone and Alveolina-Algal packstone. On the basis of relative abundance of biota, their associations and the presence of micritic matrix in various microfacies, the Sakesar Limestone is interpreted to be deposited in the proximal inner ramp to middle ramp settings. The Sakesar Limestone is largely affected and modified by various diagenetic events which have destroyed primary nature of reservoir and developed it as prolific secondary reservoir. The paragenetic sequence includes micritization, cementation, dissolution, neomorphism, nodularity, silicification, mechanical compaction, stylolitization, fractures and veins formation. The identified porosity types include intraparticle, intercrystalline, moldic, cavernous and fracture. The visually estimated average micro porosities of the Sakesar Limestone vary between 0.5 and 2.1% in the NGS and KTS. The core plug porosity and permeability of outcrop samples vary between 0.9 and 2.9%. The relation of core plug porosity and permeability has moderate positive correlation coefficient. The fractures and dissolution on microscopic and macroscopic level are the dominant factors that enhance the reservoir potentiality of the Sakesar Limestone.

Relating petrophysical parameters to petrographic interpretations in carbonates of the Chorgali Formation, Potwar Plateau, Pakistan

An integrated approach was deployed to relate the petrographical and petrophysical parameters of the Chorgali Formation to assess its reservoir potential. The petrographical study of the Chorgali Formation, exposed in Khair-e-Murat Range, disclosed that the original texture and composition are affected by diagenetic events (i.e. micritization, dolomitization, microfractures, stylolitization, compaction, dissolution, neomorphism and cementation). Of these, dissolution, dolomitization and microfractures enhanced reservoir quality, while micritization, compaction, neomorphism and cementation reduced reservoir suitability. Micritization occurred in marine phreatic conditions; dolomitization existed in the marine-meteoric mixing environment; dissolution, neomorphism and cementation took place in meteoric conditions. The mechanical and chemical compaction occurred in a burial diagenetic environment. In addition, the relationship among formation resistivity factor (F), compressional wave velocity (Vp) and porosity (ɸ) was also validated for the Eocene Chorgali Formation of Meyal Oil Field, Potwar Plateau, Pakistan. There is an inverse relationship between ɸ and F, Vp, however, the relation between F and Vp is directly proportional. Such inter-relationships assist in determining and interpreting the geological processes based on petrophysical parameters (ɸ, F and Vp). F and Vp may be high due to cementation, compaction, sealed fractures and lack of deformation in carbonates. On the other hand, F and Vp may be low due to dissolution, dolomitization, vacant fractures, lack of compaction and cementation. Similarly, ɸ is enhanced by processes lowering F and Vp and reduced by processes increasing F and Vp. Hence the diagenetic processes enhancing and reducing the porosity influence the electric and elastic properties of the carbonate rocks.

Synthesis and characterization of iron(III) oxide/polyvinyl chloride/poly(methyl methacrylate) nanocomposites

ABSTRACT Polyvinyl chloride/poly(methyl methacrylate) blended and iron(III) nanoparticle polyvinyl chloride/poly(methyl methacrylate) nanocomposites were prepared by solution casting. The iron(III) oxide nanoparticles were prepared using a sol-gel procedure and their particle size was less than 200 nm. Scanning electron microscopy showed that no phase separation occurred and polyvinyl chloride and poly(methyl methacrylate) were miscible. Scanning electron microscopy also showed that the iron(III) oxide nanoparticles were dispersed well within the polymer blend. Thermogravimetric analysis showed three stages for the thermal degradation for polyvinyl chloride/poly(methyl methacrylate) blend and the iron(III) oxide/polyvinyl chloride/poly(methyl methacrylate). The second degradation was possibly due to dehydrochlorination during the thermal degradation of polyvinyl chloride in the blend system. Young’s modulus of the iron(III) oxide nanoparticle filled nanocomposites was from 1987.7–2471.6 MPa, which was higher than polyvinyl chloride/poly(methyl methacrylate) blend (1955.5 MPa). The stress yield (47.9–51.8 MPa) of the iron(III) oxide nanoparticle composites was higher than pure polyvinyl chloride/poly(methyl methacrylate) (47.0 MPa). The cyclic voltammograms of the pure blend and the nanocomposites were compared.

Monitoring of oxidation behavior in mineral base oil additized with biomass derived antioxidants using FT-IR spectroscopy

This paper reports the artificial oxidation of original and additized mineral base oil (MBO) samples. The additives used were methanolic extracts from rice husk (RHE) and saw dust (SDE). The oxidation was performed at 100 and 200 °C, separately for a time duration of six hours according to the modified IP method. A Fourier Transform Infra Red (FTIR) spectroscopic study was carried out to identify the oxidation products like carboxylic acids/carboxylates, esters, olefins, naphthenes and aromatics in the residual samples. The level of degradation was quantified by measuring the area under carbonyl (CO) or double bond (CC) bands in order to determine the concentration of these compounds using Peak Area Increase (PAI) and Peak Height (PH) methods [ASTM 7214-07]. The results indicate that the MBO withstood oxidation in the presence of the RHE as well as the SDE. Among the two antioxidants used, the antioxidant potential of the RHE was more efficient while that of the SDE was better at 100 as well as at 200 °C.