Papers by Muhammad Abdullah Riaz
Crystals, 2022
Nanotechnology has received a lot of attention from the scientific community because of the great... more Nanotechnology has received a lot of attention from the scientific community because of the greater surface-to-volume ratio of nanomaterials, which phenomenally increases their efficacy in practical applications. Among the various synthesis techniques, the biogenic or green synthesis of nanomaterials shows advantages over other techniques such as physical, chemical, etc. This study reports the biogenic synthesis of silver nanoparticles (AgNPs) using aqueous bark extract of Aesculus indica. The as-synthesized NPs were characterized by UV–visible, FT-IR, XRD, and SEM, and then tested for their antioxidant and antimicrobial potency. We have identified phenols, flavonoids, tannins, saponins, and carbohydrates in the bark extract of A. indica. The extract-loaded-AgNPs showed the highest inhibition for Staphylococcus aureus (28.0 mm), Pseudomonas aeruginosa (17.66 mm), Escherichia coli (14.33 mm), Acetobacter serratia (14.00 mm), and Klebsiella pneumoniae (12.33 mm). The methanolic bark e...
Mathematics, 2022
Flow of a liquid in an enclosure with heat transfer has drawn special focus of researchers due to... more Flow of a liquid in an enclosure with heat transfer has drawn special focus of researchers due to the abundant thermal engineering applications. So, the aim of present communication is to explore thermal characteristics of natural convective power-law liquid flow in a square enclosure rooted with a T-shaped fin. The formulation of the problem is executed in the form of partial differential expressions by incorporating the rheological relation of the power-law fluid. The lower wall of the enclosure along with the fin is uniformly heated and vertical walls are prescribed with cold temperature. For effective heat transfer within the cavity the upper boundary is considered thermally insulated. A finite element based commercial software known as COMSOL is used for simulations and discretization of differential equations and is executed incorporating a weak formulation. Domain discretization is performed by dividing it into triangular and rectangular elements at different refinement level...
Cellular and Molecular Biology, 2021
In current study, Maize (Zea mays L.) husk leave extracts were appraised for biological activitie... more In current study, Maize (Zea mays L.) husk leave extracts were appraised for biological activities such as cytotoxicity, antidiabetic, antioxidant and antimicrobial. Maceration was performed to collect various fractions of husk leave extracts using a pool of solvents i.e., n-hexane, chloroform, ethyl acetate, butanol and methanol. Antioxidant potential was measured by 1,1-diphenyl-2-picrylhydrazyl (DPPH) scavenging, reducing power and linoleic acid oxidation assay, using butylated hydroxy toluene (BHT) as a positive control. Total phenolic and flavonoid contents were found to be 18.47-425.11 mg/100 g GAE and 5.83-16.72 mg/100 g CE, respectively. The DPPH scavenging assay was exhibited in the range of 76.36 to 88.53%. The percentage inhibition in linoleic acid oxidation was found from 10.16 to 79.51%. Significant antimicrobial activity was demonstrated by husk leaf extracts against bacterial strains and fungal strains using disc diffusion and minimum inhibitory concentration (MIC) me...
Complex oxide materials are special in their ability to show highly diverse electronic properties... more Complex oxide materials are special in their ability to show highly diverse electronic properties and go through many different phase transitions, including ferromagnetic, ferroelectric, metal-to-insulator and superconducting. Furthermore, the similarity of crystal structures makes it possible to stack in epitaxial heterostructures layers possessing different functional properties and interacting with each other through electric or magnetic fields, charge transfer, exchange bias, strain, etc, opening the way to the design of almost unlimited multifunctional device concepts. In this context, this thesis is devoted to the transport characterization of transition metal oxides (TMOs) under the external perturbation of a photon field, with special attention dedicated to two quite outstanding cases, that are: i) Pr1-xCaxMnO3 (PCMO), a narrow band manganite showing an insulating behaviour across it’s whole phase diagram, and ii) polar-non polar oxide interfaces, where the formation of a hi...
Advances in Difference Equations, 2021
In this paper a new approach is taken to find the exact solutions for generalized unsteady magnet... more In this paper a new approach is taken to find the exact solutions for generalized unsteady magnetohydrodynamic transport of a rate-type fluid near an unbounded upright plate and is analyzed for ramped wall temperature and velocity with constant concentration. The vertical plate is suspended in a porous medium and encounters radiation effects. Solutions based on special functions are obtained using an integral transform for an unsteady MHD Maxwell fluid in the presence of ramped velocity, temperature and constant concentration. The relations for Nusselt number and skin-friction coefficient are efficiently computed to precisely estimate the rate of heat transfer at the boundary and the shear stress. Results are also discussed in detail and demonstrated graphically using software to comprehensively analyze the dynamics of the proposed problem, and the physical impact of several system parameters, such as magnetic field M, Prandtl number Pr, the relaxation time λ, dimensionless time τ, ...
International Journal of Environmental Research and Public Health, 2020
Tannery wastewater mainly comes from leather industries. It has high organic load, high salinity,... more Tannery wastewater mainly comes from leather industries. It has high organic load, high salinity, and many other pollutants, including chromium (Cr). Tannery wastewater is generally used for crop irrigation in some areas of Pakistan and worldwide, due to the low availability of good quality of irrigation water. As tannery wastewater has many nutrients in it, its lower concentration benefits the plant growth, but at a higher concentration, it damages the plants. Chromium in tannery wastewater accumulates in plants, and causes stress at physiological and biochemical levels. In recent times, the role of micronutrient-amino acid chelated compounds has been found to be helpful in reducing abiotic stress in plants. In our present study, we used lysine chelated zinc (Zn-lys) as foliar application on maize (Zea mays L.), growing in different concentrations of tannery wastewater. Zinc (Zn) is required by plants for growth, and lysine is an essential amino acid. Maize plants were grown in tan...
Critical reviews in microbiology, Jan 8, 2015
Aflatoxin M1 (AFM1) in milk is among the most carcinogenic compounds, relatively high levels bein... more Aflatoxin M1 (AFM1) in milk is among the most carcinogenic compounds, relatively high levels being consumed, especially by the most vulnerable age groups, i.e. infants and the elderly. Reports on its prevalence are constantly being received from various parts of the world compelling nations to establish their own standard limits for AFM1. Global review of the literature indicates the existence of methods of partial decontamination of AFM1, however; evidence based studies do not suggest that any single strategy as a coherent and complete solution to the issue. Microbial decontamination of AFM1 has emerged as the most suitable method up to now but the stability of toxin-microbial cell complexes still remains questionable. This review discusses the chemical nature, established maximum permissible limits and prevalence of AFM1 in various countries from 2009 to 2014. Moreover, the possible mechanisms for AFM1 reduction mainly the microbial decontamination and the stability and bioaccessi...
International Journal of Molecular Sciences, 2012
The present study was conducted to examine various biological activities of a methanol extract of... more The present study was conducted to examine various biological activities of a methanol extract of Agave attenuata leaves. GC-MS analysis of the n-hexane fraction from the extract revealed the presence of 31 compounds, with mono-2-ethylhexyl phthalate (11.37%), 1,2-benzenedicarboxylic acid (6.33%), n-docosane (6.30%) and eicosane (6.02%) as the major components. The leaves contained appreciable levels of total phenolic contents (10.541-39.35 GAE, mg/100 g) and total flavonoid contents (43.35-304.8 CE, mg/100 g). The extract and some of its fractions showed moderate antimicrobial effects. Leaves extract and fractions also exhibited a good antioxidant potential when measured by DPPH radical scavenging activity and inhibition of lipid peroxidation assays. The hemolytic effect of the plant was found to be in a range of 1.01%-2.64%. From the present study it is concluded that this plant could be used as a source of natural antioxidants and functional food nutraceutical applications.
TURKISH JOURNAL OF MEDICAL SCIENCES, 2014
Introduction Rubus fruticosus L. (Rosaceae) grows wild in northern areas of Pakistan like Malakan... more Introduction Rubus fruticosus L. (Rosaceae) grows wild in northern areas of Pakistan like Malakand, Kotli, Chitral, Mansehra, and Dir (1-6). It is well known by local people due to its nutritional and medicinal importance. The fruit is commonly known as berry or blackberry. The fruit is edible and used for preparing jams and jellies (7). A tea is prepared from the dried leaves (8) of the plant while salad is prepared from its young shoots (9). All parts of the plant are associated with diverse pharmacological activities. The leaves are believed to possess diuretic, carminative, and antidiabetic properties and are used to cure diarrhea, cough, fever, hemorrhoids, and cystitis (10). A decoction of the leaves is useful as a gargle in treating thrush, mouth ulcers, and gum inflammations (8,11-12). The leaves are also used to treat skin and gastrointestinal tract infections and for healing of wounds (13-15). Leaves are used to manage digestive disorders of calves and piglets (16). A decoction of root bark is used in diarrhea and dysentery. The root bark and the leaves are strongly astringent, depurative, tonic, and vulnerary. The plant has reported antiinflammatory action and antiviral activity, and it forms part of a herbal deodorant composition against allyl methyl monosulfide (17-19). Various bioactive constituents, like triterpenes, sterols, glycosides, and anthocyanins (20-22), have been isolated from the plant. The plant also contains phytoestrogen, fatty acid, tocols, flavonoids, carotenoids, and rare earth elements (23-27). Previously, psychoactive synthetic drugs were recognized as most effective in the management of central nervous system (CNS)-related disorders. However, their continuous and indiscriminate use has led to various side effects affecting the endocrine, autonomic, allergic, hematopoietic, and neurological systems of the human body. Thus, scientists are searching for new therapeutic agents with minimum side effects and maximum potency from medicinal plants, which are believed to be safe and cost-effective, and there is an increasing trend of screening botanicals for neuropharmacological effects. Neuropharmacological screening includes various activities like anxiolytic activity assessed by open field, head dip test, cage cross and rearing test, muscle relaxing activity via traction test, and antidepressant activity via forced swimming test. Anxiety affects one-eighth of the population worldwide and has become an important research area in the field of psychopharmacology (28). It is well known that the sedative effect of drugs on the CNS can be evaluated by the measurement of spontaneous motor activity in laboratory animal models. Aim: To investigate methanol extracts of various parts of Rubus fruticosus L. (Rosaceae) for various neuropharmacological activities, such as anxiolytic, muscle relaxant, antidepressant, and sedative activities. Materials and methods: The extracts were administered to albino mice orally at doses of 100, 300, and 500 mg/kg. The antidepressant activity was determined by using the forced swimming test, while line crossing in a special box was used for assessment of locomotor activity. Results: All extracts were found to be anxiolytic in nature, while no muscle relaxing activity or sedative effect was observed. The order of central nervous system (CNS) depressant effect for various parts of R. fruticosus was fruit > root > leaves > stem. Conclusion: Our results indicate that methanolic extract of various parts of R. fruticosus possess anxiolytic and CNS depressant effects but do not possess significant sedative or muscle relaxing potential.
International Journal of Molecular Sciences, 2012
The present study was conducted to examine various biological activities of a methanol extract of... more The present study was conducted to examine various biological activities of a methanol extract of Agave attenuata leaves. GC-MS analysis of the n-hexane fraction from the extract revealed the presence of 31 compounds, with mono-2-ethylhexyl phthalate (11.37%), 1,2-benzenedicarboxylic acid (6.33%), n-docosane (6.30%) and eicosane (6.02%) as the major components. The leaves contained appreciable levels of total phenolic contents (10.541-39.35 GAE, mg/100 g) and total flavonoid contents (43.35-304.8 CE, mg/100 g). The extract and some of its fractions showed moderate antimicrobial effects. Leaves extract and fractions also exhibited a good antioxidant potential when measured by DPPH radical scavenging activity and inhibition of lipid peroxidation assays. The hemolytic effect of the plant was found to be in a range of 1.01%-2.64%. From the present study it is concluded that this plant could be used as a source of natural antioxidants and functional food nutraceutical applications.
Sensors, 2009
ZnO nanotubes and nanorods grown on gold thin film were used to create pH sensor devices. The dev... more ZnO nanotubes and nanorods grown on gold thin film were used to create pH sensor devices. The developed ZnO nanotube and nanorod pH sensors display good reproducibility, repeatability and long-term stability and exhibit a pH-dependent electrochemical potential difference versus an Ag/AgCl reference electrode over a large dynamic pH range. We found the ZnO nanotubes provide sensitivity as high as twice that of the ZnO nanorods, which can be ascribed to the fact that small dimensional ZnO nanotubes have a higher level of surface and subsurface oxygen vacancies and provide a larger effective surface area with higher surface-to-volume ratio as compared to ZnO nanorods, thus affording the ZnO nanotube pH sensor a higher sensitivity. Experimental results indicate ZnO nanotubes can be used in pH sensor applications with improved performance. Moreover, the ZnO nanotube arrays may find potential application as a novel material for measurements of intracellular biochemical species within single living cells.
TURKISH JOURNAL OF MEDICAL SCIENCES, 2014
Introduction Rubus fruticosus L. (Rosaceae) grows wild in northern areas of Pakistan like Malakan... more Introduction Rubus fruticosus L. (Rosaceae) grows wild in northern areas of Pakistan like Malakand, Kotli, Chitral, Mansehra, and Dir (1-6). It is well known by local people due to its nutritional and medicinal importance. The fruit is commonly known as berry or blackberry. The fruit is edible and used for preparing jams and jellies (7). A tea is prepared from the dried leaves (8) of the plant while salad is prepared from its young shoots (9). All parts of the plant are associated with diverse pharmacological activities. The leaves are believed to possess diuretic, carminative, and antidiabetic properties and are used to cure diarrhea, cough, fever, hemorrhoids, and cystitis (10). A decoction of the leaves is useful as a gargle in treating thrush, mouth ulcers, and gum inflammations (8,11-12). The leaves are also used to treat skin and gastrointestinal tract infections and for healing of wounds (13-15). Leaves are used to manage digestive disorders of calves and piglets (16). A decoction of root bark is used in diarrhea and dysentery. The root bark and the leaves are strongly astringent, depurative, tonic, and vulnerary. The plant has reported antiinflammatory action and antiviral activity, and it forms part of a herbal deodorant composition against allyl methyl monosulfide (17-19). Various bioactive constituents, like triterpenes, sterols, glycosides, and anthocyanins (20-22), have been isolated from the plant. The plant also contains phytoestrogen, fatty acid, tocols, flavonoids, carotenoids, and rare earth elements (23-27). Previously, psychoactive synthetic drugs were recognized as most effective in the management of central nervous system (CNS)-related disorders. However, their continuous and indiscriminate use has led to various side effects affecting the endocrine, autonomic, allergic, hematopoietic, and neurological systems of the human body. Thus, scientists are searching for new therapeutic agents with minimum side effects and maximum potency from medicinal plants, which are believed to be safe and cost-effective, and there is an increasing trend of screening botanicals for neuropharmacological effects. Neuropharmacological screening includes various activities like anxiolytic activity assessed by open field, head dip test, cage cross and rearing test, muscle relaxing activity via traction test, and antidepressant activity via forced swimming test. Anxiety affects one-eighth of the population worldwide and has become an important research area in the field of psychopharmacology (28). It is well known that the sedative effect of drugs on the CNS can be evaluated by the measurement of spontaneous motor activity in laboratory animal models. Aim: To investigate methanol extracts of various parts of Rubus fruticosus L. (Rosaceae) for various neuropharmacological activities, such as anxiolytic, muscle relaxant, antidepressant, and sedative activities. Materials and methods: The extracts were administered to albino mice orally at doses of 100, 300, and 500 mg/kg. The antidepressant activity was determined by using the forced swimming test, while line crossing in a special box was used for assessment of locomotor activity. Results: All extracts were found to be anxiolytic in nature, while no muscle relaxing activity or sedative effect was observed. The order of central nervous system (CNS) depressant effect for various parts of R. fruticosus was fruit > root > leaves > stem. Conclusion: Our results indicate that methanolic extract of various parts of R. fruticosus possess anxiolytic and CNS depressant effects but do not possess significant sedative or muscle relaxing potential.
Quality and Reliability Engineering International, 2012
For an improved monitoring of process parameters, it is generally desirable to have ef?cient desi... more For an improved monitoring of process parameters, it is generally desirable to have ef?cient designs of control charting structures. The addition of Shewhart control limits to the cumulative sum (CUSUM) control chart is a simple monitoring scheme sensitive to wide range of mean shifts. To improve the detection ability of the combined Shewhart-CUSUM control chart to off-target processes, we developed the scheme using ranked set sampling instead of the traditional simple random sampling. We investigated the run length properties of the Shewhart-CUSUM with ranked set samples and compared their performance with certain established control charts. It is revealed that the proposed schemes offer better protection against different types of mean shifts than the existing counterparts including classical Shewhart, classical CUSUM, classical combined Shewhart-CUSUM, adaptive CUSUM, double CUSUM, three simultaneous CUSUM, combined Shewhart-weighted CUSUM, runs rules-based CUSUM and the mixed exponentially weighted moving average-CUSUM. Applications on real data sets are also given to demonstrate the implementation simplicity of the proposed schemes.
PLoS ONE, 2014
Peat forming Sphagnum mosses are able to prevent the dominance of vascular plants under ombrotrop... more Peat forming Sphagnum mosses are able to prevent the dominance of vascular plants under ombrotrophic conditions by efficiently scavenging atmospherically deposited nitrogen (N). N-uptake kinetics of these mosses are therefore expected to play a key role in differential N availability, plant competition, and carbon sequestration in Sphagnum peatlands. The interacting effects of rain N concentration and exposure time on moss N-uptake rates are, however, poorly understood. We investigated the effects of N-concentration (1, 5, 10, 50, 100, 500 mM), N-form (15 N-ammonium or nitrate) and exposure time (0.5, 2, 72 h) on uptake kinetics for Sphagnum magellanicum from a pristine bog in Patagonia (Argentina) and from a Dutch bog exposed to decades of N-pollution. Uptake rates for ammonium were higher than for nitrate, and N-binding at adsorption sites was negligible. During the first 0.5 h, N-uptake followed saturation kinetics revealing a high affinity (K m 3.5-6.5 mM). Ammonium was taken up 8 times faster than nitrate, whereas over 72 hours this was only 2 times. Uptake rates decreased drastically with increasing exposure times, which implies that many short-term Nuptake experiments in literature may well have overestimated long-term uptake rates and ecosystem retention. Sphagnum from the polluted site (i.e. long-term N exposure) showed lower uptake rates than mosses from the pristine site, indicating an adaptive response. Sphagnum therefore appears to be highly efficient in using short N pulses (e.g. rainfall in pristine areas). This strategy has important ecological and evolutionary implications: at high N input rates, the risk of N-toxicity seems to be reduced by lower uptake rates of Sphagnum, at the expense of its long-term filter capacity and related competitive advantage over vascular plants. As shown by our conceptual model, interacting effects of N-deposition and climate change (changes in rainfall) will seriously alter the functioning of Sphagnum peatlands.
PLoS ONE, 2014
Hepatitis C virus (HCV) infection is an alarming and growing threat to public health. The present... more Hepatitis C virus (HCV) infection is an alarming and growing threat to public health. The present treatment gives limited efficacy and is poorly tolerated, recommending the urgent medical demand for novel therapeutics. NS3/4A protease is a significant emerging target for the treatment of HCV infection. This work reports the complex-based pharmacophore modeling to find out the important pharmacophoric features essential for the inhibition of both protease and helicase activity of NS3/4A protein of HCV. A seven featured pharmacophore model of HCV NS3/4A protease was developed from the crystal structure of NS3/4A protease in complex with a macrocyclic inhibitor interacting with both protease and helicase sites residues via MOE pharmacophore constructing tool. It consists of four hydrogen bond acceptors (Acc), one hydrophobic (Hyd), one for lone pair or active hydrogen (Atom L) and a heavy atom feature (Atom Q). The generated pharmacophore model was validated by a test database of seventy known inhibitors containing 55 active and 15 inactive/ least active compounds. The validated pharmacophore model was used to virtually screen the ChemBridge database. As a result of screening 1009 hits were retrieved and were subjected to filtering by Lipinski's rule of five on the basis of which 786 hits were selected for further assessment using molecular docking studies. Finally, 15 hits of different scaffolds having interactions with important active site residues were predicted as lead candidates. These candidates having unique scaffolds have a strong likelihood to act as further starting points in the development of novel and potent NS3/4A protease inhibitors.
Molecules, 2013
A series of various novel 4-arylthiophene-2-carbaldehyde compounds were synthesized in moderate t... more A series of various novel 4-arylthiophene-2-carbaldehyde compounds were synthesized in moderate to excellent yields via Suzuki-Miyaura cross-coupling with different arylboronic pinacol esters/acids. The synthesized products were screened for their antibacterial, haemolytic, antiurease, and nitric oxide (NO) scavenging capabilities and interestingly, almost all products turned out to have good activities. 3-(5-Formylthiophene-3-yl)-5-(trifloromethyl)benzonitrile (2d) revealed excellent antibacterial activity, showing an IC 50 value of 29.7 µg/mL against Pseudomonas aeruginosa, compared to the standard drug streptomycin with an IC 50 value 35.2 µg/mL and was also found to be the best NO scavenger, with an IC 50 value of 45.6 µg/mL. Moreover, 4-(3-chloro-4-fluorophenyl)thiophene-2-carbaldehyde (2i) exhibited a superior haemolytic action and an outstanding urease inhibition, showing an IC 50 value of 27.1 µg/mL.
Molecules, 2012
The antimicrobial, antioxidant and cytotoxic properties of Mazus goodenifolius (Hornem.) Pennell ... more The antimicrobial, antioxidant and cytotoxic properties of Mazus goodenifolius (Hornem.) Pennell essential oil, methanol extract and some solvent-extracted subfractions of the latter were appraised. A qualitative, quantitative analysis of the classes of phytochemicals in the various fractions and GC-MS analysis of the essential oil was carried out. The activity of the plant extract and various subfractions against selected bacterial (Pasturella multocida, Escherichia coli, Bacillus subtilis and Staphylococcus aureus) and fungal strains (Aspergillus niger, Aspergillus flavus, Alternaria alternata and Rhizopus solani) was evaluated. The antioxidant activity was assayed using the DPPH radical scavenging and % inhibition of linoleic acid peroxidation tests. In the DPPH radical scavenging test the IC 50 values ranged from 7.21 to 91.79 µg/mL, and in the latter the range of % peroxidation inhibition was 35.42-93.48%. Protective effects of the absolute methanol extract, which had the highest content of phenolics and flavonoids, against H 2 O 2 induced oxidative damage in plasmid pBR322 DNA was also evaluated, and it was found to offer some protection at the highest tested dose (1,000 µg/mL). Finally the cytotoxicity of the plant extract, fractions and essential oil was analyzed by examining haemolytic
Journal of Enzyme Inhibition and Medicinal Chemistry, 2006
Phytochemical investigations on the chloroform and ethyl acetate soluble fractions of the roots o... more Phytochemical investigations on the chloroform and ethyl acetate soluble fractions of the roots of the Daphne oleoids led to the isolation of the coumarin glycosides 1-6. Compound 5 with IC 50 values 22.05 and 26.30 mM repectively, was found to be the most active of these compounds when screened against Bacillus pasteurii and jack bean urease enzymes in a concentrationdependent fashion.
International Journal of Food Science & Technology, 2010
Antioxidant and antimicrobial activity of the ethyl acetate and water subfractions of methanolic ... more Antioxidant and antimicrobial activity of the ethyl acetate and water subfractions of methanolic extracts of three Spanish onion varieties were assayed. Flavonoids were mainly present in ethyl acetate subfraction being 34.92 ± 0.75, 7.95 ± 0.16, 0.38 ± 0.01 lmol of rutin eq. g)1 D.W. and its antioxidant capacity was 74.86 ± 1.77, 24.59 ± 0.67, 4.55 ± 0.44 lmol Trolox g)1 D.W. of Grano de Oro, Fuentes de Ebro and Calc¸ot de Valls varieties, respectively. The antimicrobial activity of flavonol standards and onion extracts was evaluated against some food spoiler microorganisms. Quercetin and kaempferol were inhibitory against gram positive bacteria such as Bacillus cereus, Staphylococcus aureus, Microcroccus luteus and Listeria monocytogenes. Gram negative bacteria Escherichia coli and Pseudomonas aeruginosa were less sensible to the antimicrobial effect of both flavonol standards and Candida albicans was totally resistant. Among the onion extracts tested only ethyl acetate subfraction showed antimicrobial inhibition.
Control Engineering Practice, 2005
A novel approach to the problem of robust state estimation in the presence of model uncertainty a... more A novel approach to the problem of robust state estimation in the presence of model uncertainty as well as plant disturbance and sensor noise is considered. Two new observer structures are discussed and shown to have certain advantages over the classical state space observer when studying robustness issues. The results are used to design an observer for a real industrial boiler system.
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Papers by Muhammad Abdullah Riaz