Publications by authors named "Anwar Ul-Hamid"

17 Publications

  • Page 1 of 1

Development of Multi-concentration Cu:Ag Bimetallic Nanoparticles as a Promising Bactericidal for Antibiotic-Resistant Bacteria as Evaluated with Molecular Docking Study.

Nanoscale Res Lett 2021 May 22;16(1):91. Epub 2021 May 22.

Department of Chemistry, Quaid-I-Azam University, Islamabad, 45320, Pakistan.

The present study is concerned with evaluating the influence of various concentrations of Ag within Cu:Ag bimetallic nanoparticles developed for use as a promising anti-bacterial agent against antibiotic-resistant bacteria. Here, Cu:Ag bimetallic nanoparticles with various concentration ratios (2.5, 5.0, 7.5, and 10 wt%) of Ag in fixed amount of Cu labeled as 1:0.025, 1:0.050, 1:0.075, and 1:0.1 were synthesized using co-precipitation method with ammonium hydroxide and deionized water as solvent, polyvinyl pyrrolidone as a capping agent, and sodium borohydride and ascorbic acid as reducing agents. These formulated products were characterized through a variety of techniques. XRD confirmed phase purity and detected the presence of distinct fcc structures belonging to Cu and Ag phases. FTIR spectroscopy confirmed the presence of vibrational modes corresponding to various functional groups and recorded characteristic peak emanating from the bimetallic. UV-visible spectroscopy revealed reduction in band gap with increasing Ag content. SEM and HR-TEM micrographs revealed spherical morphology of Ag-doped Cu bimetallic with small and large scale agglomerations. The samples exhibited varying dimensions and interlayer spacing. Bactericidal action of synthesized Cu:Ag bimetallic NPs depicted statistically significant (P < 0.05) inhibition zones recorded for various concentrations of Ag dopant against Staphylococcus aureus (S. aureus), Escherichia coli (E. coli), and Acinetobacter baumannii (A. baumannii) ranging from (0.85-2.8 mm), (0.55-1.95 mm) and (0.65-1.85 mm), respectively. Broadly, Cu:Ag bimetallic NPs were found to be more potent against gram-positive compared with gram-negative. Molecular docking study of Ag-Cu bimetallic NPs was performed against β-lactamase which is a key enzyme of cell wall biosynthetic pathway from both S. aureus (Binding score: - 4.981 kcal/mol) and A. bauminnii (Binding score: - 4.013 kcal/mol). Similarly, binding interaction analysis against FabI belonging to fatty acid biosynthetic pathway from A. bauminnii (Binding score: - 3.385 kcal/mol) and S. aureus (Binding score: - 3.012 kcal/mol) along with FabH from E. coli (Binding score: - 4.372 kcal/mol) was undertaken. These theoretical computations indicate Cu-Ag bimetallic NPs as possible inhibitor of selected enzymes. It is suggested that exploring in vitro inhibition potential of these materials may open new avenues for antibiotic discovery.
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http://dx.doi.org/10.1186/s11671-021-03547-6DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC8141091PMC
May 2021

Impact of Bi Doping into Boron Nitride Nanosheets on Electronic and Optical Properties Using Theoretical Calculations and Experiments.

Nanoscale Res Lett 2021 May 12;16(1):82. Epub 2021 May 12.

Department of Physics, College of Science, King Faisal University, P.O. Box 400, Al-Ahsa, 31982, Saudi Arabia.

In the present work, boron nitride (BN) nanosheets were prepared through bulk BN liquid phase exfoliation while various wt. ratios (2.5, 5, 7.5 and 10) of bismuth (Bi) were incorporated as dopant using hydrothermal technique. Our findings exhibit that the optical investigation showed absorption spectra in near UV region. Density functional theory calculations indicate that Bi doping has led to various modifications in the electronic structures of BN nanosheet by inducing new localized gap states around the Fermi level. It was found that bandgap energy decrease with the increase of Bi dopant concentrations. Therefore, in analysis of the calculated absorption spectra, a redshift has been observed in the absorption edges, which is consistent with the experimental observation. Additionally, host and Bi-doped BN nanosheets were assessed for their catalytic and antibacterial potential. Catalytic activity of doped free and doped BN nanosheets was evaluated by assessing their performance in dye reduction/degradation process. Bactericidal activity of Bi-doped BN nanosheets resulted in enhanced efficiency measured at 0-33.8% and 43.4-60% against S. aureus and 0-38.8% and 50.5-85.8% against E. coli, respectively. Furthermore, In silico molecular docking predictions were in good agreement with in-vitro bactericidal activity. Bi-doped BN nanosheets showed good binding score against DHFR of E. coli (- 11.971 kcal/mol) and S. aureus (- 8.526 kcal/mol) while binding score for DNA gyrase from E. coli (- 6.782 kcal/mol) and S. aureus (- 7.819 kcal/mol) suggested these selected enzymes as possible target.
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http://dx.doi.org/10.1186/s11671-021-03542-xDOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC8116421PMC
May 2021

Doping of Mg on ZnO Nanorods Demonstrated Improved Photocatalytic Degradation and Antimicrobial Potential with Molecular Docking Analysis.

Nanoscale Res Lett 2021 May 1;16(1):78. Epub 2021 May 1.

Physics Department, Lahore Garrison University, Lahore, Punjab, 54000, Pakistan.

Various concentrations of Mg-doped ZnO nanorods (NRs) were prepared using co-precipitation technique. The objective of this study was to improve the photocatalytic properties of ZnO. The effect of Mg doping on the structure, phase constitution, functional groups presence, optical properties, elemental composition, surface morphology and microstructure of ZnO was evaluated with XRD, FTIR, UV-Vis spectrophotometer, EDS, and HR-TEM, respectively. Optical absorption spectra obtained from the prepared samples showed evidence of blueshift upon doping. XRD results revealed hexagonal wurtzite phase of nanocomposite with a gradual decrease in crystallite size with Mg addition. PL spectroscopy showed trapping efficiency and migration of charge carriers with electron-hole recombination behavior, while HR-TEM estimated interlayer d-spacing. The presence of chemical bonding, vibration modes and functional groups at the interface of ZnO was revealed by FTIR and Raman spectra. In this study, photocatalytic, sonocatalytic and sonophotocatalytic performance of prepared NRs was systematically investigated by degrading a mixture of methylene blue and ciprofloxacin (MBCF). Experimental results suggested that improved degradation performance was shown by Mg-doped ZnO NRs. We believe that the product synthesized in this study will prove to be a beneficial and promising photocatalyst for wastewater treatment. Conclusively, Mg-doped ZnO exhibited substantial (p < 0.05) efficacy against gram-negative (G-ve) as compared to gram-positive (G+ve) bacteria. In silico molecular docking studies of Mg-doped ZnO NRs against DHFR (binding score: - 7.518 kcal/mol), DHPS (binding score: - 6.973 kcal/mol) and FabH (- 6.548 kcal/mol) of E. coli predicted inhibition of given enzymes as possible mechanism behind their bactericidal activity.
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http://dx.doi.org/10.1186/s11671-021-03537-8DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC8088420PMC
May 2021

Liquid-phase exfoliated MoS nanosheets doped with -type transition metals: a comparative analysis of photocatalytic and antimicrobial potential combined with density functional theory.

Dalton Trans 2021 May;50(19):6598-6619

Department of Physics, College of Science, King Faisal University, P.O. Box 400, Al-Ahsa, 31982, Saudi Arabia.

MoS2 nanosheets were developed by undertaking the liquid-phase exfoliation of bulk counterparts. In order to enhance its photocatalytic properties, the host material was doped with p-type transition metals (i.e., Ag, Co, Bi, and Zr). The hydrothermal technique was used to produce samples doped with 7.5 wt% transition metals (TM). X-ray diffraction detected the existence of 2H-phase by mirroring its reflection at 2θ ∼ 14°, while the peak distribution revealed the degree of exfoliation in samples. Low PL intensities indicated a lower recombination of electron-hole pairs, as corroborated by a high degree of photocatalytic action. Raman analysis was undertaken to identify molecular vibrations. The A1g mode in Raman spectra consistently showed a blueshift in all samples and the E12g mode was only slightly affected, which is evidence of the p-type doping in the MoS2 nanosheets. In the XPS spectrum, two characteristic peaks of Mo 3d appeared at 229.87 and 233.03 eV assigned to Mo-3d5/2 and Mo-3d3/2, respectively. Furthermore, a microstructural examination with HR-TEM and FESEM divulged a thin-layered structure of MoS2 consisting of flat, gently curved or twisted nanosheets. Diverse morphologies were observed with a non-uniform distribution of the dopant. Photocatalytic action of the TM-doped products effectively degraded methylene blue (MB) concentrations of up to 94 percent (for Ag-MoS2). The synergistic effect of doped MoS2 nanosheets against S. aureus in comparison to E. coli bacteria was also evaluated. The efficacy % age improved from (0-31.7%) and (23.5-55.2%) against E. coli, and (0-34.2%) and (8.3-69.23%) against S. aureus. Moreover, results from first principles calculations indicate that substitutional doping of TM atoms is indeed advantageous. Theoretical calculations confirmed that doping with Ag, Co, Bi, and Zr leads to a decrease in the band gap to a certain degree, in which the conduction band edge shifts toward lower energy, while the valence band shifts closer to the high energy end. It can be concluded that Ag, Co, and Bi impurities can lead to beneficial p-type doping in MoS2 monolayered structures. With regards to doping with Zr, the acceptor levels are formed above the edge of the valence band, revealing an introduction of the p-type character.
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http://dx.doi.org/10.1039/d1dt00236hDOI Listing
May 2021

Synthesis, microstructural characterization and nanoindentation of Zr, Zr-nitride and Zr-carbonitride coatings deposited using magnetron sputtering.

Authors:
Anwar Ul-Hamid

J Adv Res 2021 Mar 25;29:107-119. Epub 2020 Nov 25.

Center for Engineering Research, Research Institute, King Fahd University of Petroleum & Minerals, Dhahran 31261, Saudi Arabia.

Introduction: Hard coatings are primarily based on carbides, nitrides and carbonitrides of transition metal elements such as W, Ti, Zr, etc. Zr-based hard coatings show good resistance to wear, erosion, and corrosion as well as exhibit high hardness, high temperature stability, and biocompatibility, making them suitable candidates for tribological, biomedical, and electrical applications.

Objectives: The present study aims to synthesize uniform and adherent hard Zr-based coatings that demonstrate sound mechanical integrity.

Methods: Stainless steel (SS316) samples were coated with single layers of Zr, Zr-nitride, and Zr-carbonitride using magnetron sputter deposition technique. Deposition conditions were controlled to produce each coating with two different thickness i.e., 2 and 3 μm. Calotest was employed to confirm coatings thickness. Scanning electron microscope fitted with energy dispersive x-ray spectrometer was used to ascertain the morphology and elemental constitution of coatings. Cross-sectional samples were examined to ascertain coatings thickness and adhesion. X-ray diffractometer was employed for structural analysis. Instrumented nanoindentation hardness and elastic modulus were determined with nanoindenter. Ratio of nanohardness to elastic modulus was evaluated to observe the effect of coatings thickness on tribological behavior.

Results: Three coating compositions were produced namely hcp-Zr, fcc-ZrN and fcc-ZrCN. The highest hardness and elastic modulus were shown by ZrN coatings while pure Zr coatings showed the lowest values.

Conclusion: All coating compositions were found to be relatively uniform, continuous and adherent with no evidence of decohesion at the coating-substrate interface. Coatings produced in this study are thought to be suitable for tribological applications.
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http://dx.doi.org/10.1016/j.jare.2020.11.010DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC8020350PMC
March 2021

On the Use of OPEFB-Derived Microcrystalline Cellulose and Nano-Bentonite for Development of Thermoplastic Starch Hybrid Bio-Composites with Improved Performance.

Polymers (Basel) 2021 Mar 15;13(6). Epub 2021 Mar 15.

Core Research Facilities, King Fahd University of Petroleum & Minerals, Dhahran 31261, Saudi Arabia.

Thermoplastic starch (TPS) hybrid bio-composite films containing microcrystalline cellulose (C) and nano-bentonite (B) as hybrid fillers were studied to replace the conventional non-degradable plastic in packaging applications. Raw oil palm empty fruit bunch (OPEFB) was subjected to chemical treatment and acid hydrolysis to obtain C filler. B filler was ultra-sonicated for better dispersion in the TPS films to improve the filler-matrix interactions. The morphology and structure of fillers were characterized by scanning electron microscope (SEM), Fourier transform infrared spectroscopy (FTIR) and X-ray diffraction (XRD). TPS hybrid bio-composite films were produced by the casting method with different ratios of B and C fillers. The best ratio of B/C was determined through the data of the tensile test. FTIR analysis proved the molecular interactions between the TPS and the hybrid fillers due to the presence of polar groups in their structure. XRD analysis confirmed the intercalation of the TPS chains between the B inter-platelets as a result of well-developed interactions between the TPS and hybrid fillers. SEM images suggested that more plastic deformation occurred in the fractured surface of the TPS hybrid bio-composite film due to the higher degree of stretching after being subjected to tensile loading. Overall, the results indicate that incorporating the hybrid B/C fillers could tremendously improve the mechanical properties of the films. The best ratio of B/C in the TPS was found to be 4:1, in which the tensile strength (8.52MPa), Young's modulus (42.0 MPa), elongation at break (116.4%) and tensile toughness of the film were increased by 92%, 146%, 156% and 338%, respectively. The significantly improved strength, modulus, flexibility and toughness of the film indicate the benefits of using the hybrid fillers, since these features are useful for the development of sustainable flexible packaging film.
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http://dx.doi.org/10.3390/polym13060897DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC8000011PMC
March 2021

Synthesis and Characterization of Fe-TiO Nanomaterial: Performance Evaluation for RB5 Decolorization and In Vitro Antibacterial Studies.

Nanomaterials (Basel) 2021 Feb 9;11(2). Epub 2021 Feb 9.

Department of Environmental Sciences, Abbottabad Campus, COMSATS University Islamabad, Abbottabad 22060, Pakistan.

A photocatalytic system for decolorization of double azo reactive black 5 (RB5) dye and water disinfection of was developed. Sol gel method was employed for the synthesis of Fe-TiO photocatalysts and were characterized using thermogravimetric analysis (TGA), Fourier transform infrared spectroscopy (FTIR), X-ray diffraction (XRD), scanning electron microscopy (SEM) coupled with energy dispersive X-ray analysis (EDX), transmission electron microscopy (TEM), diffuse reflectance spectroscopy (DRS) and Brunauer-Emmett-Teller (BET) analysis. Results showed that photocatalytic efficiency was greatly influenced by 0.1 weight percent iron loading and 300 °C calcination temperature. The optimized reaction parameters were found to be the ambient temperature, working solution pH 6.2 and 1 mg g dose to completely decolorize RB5. The isotherm studies showed that RB5 adsorption by Fe-TiO followed the Langmuir isotherm with maximum adsorption capacity of 42.7 mg g and K 0.0079 L mg. Under illumination, the modified photocatalytic material had higher decolorization efficiency as compared to unmodified photocatalyst. Kinetic studies of the modified material under visible light irradiation indicated the reaction followed the pseudo-first-order kinetics. The illumination reaction followed the Langmuir-Hinshelwood (L-H) model as the rate of dye decolorization increased with an incremental increase in dye concentration. The L-H constant K was 1.5542 mg L∙h while K was found 0.1317 L mg. The best photocatalyst showed prominent percent reduction of in 120 min. Finally, 0.1Fe-TiO-300 could be an efficient photocatalyst and can provide a composite solution for RB5 decolorization and bacterial strain inhibition.
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http://dx.doi.org/10.3390/nano11020436DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC7915575PMC
February 2021

Photocatalytic, Bactericidal and Molecular Docking Analysis of Annealed Tin Oxide Nanostructures.

Nanoscale Res Lett 2021 Feb 10;16(1):33. Epub 2021 Feb 10.

Physics Department, Lahore Garrison University, Lahore, 54000, Pakistan.

Nanosized tin oxide was fabricated with a simple and cost-effective precipitation technique and was analyzed by performing x-ray powder diffraction (XRD), Fourier-transform infrared (FT-IR) spectroscopy, high-resolution transmission electron (HR-TEM) microscopy, energy-dispersive x-ray (EDX) and UV-Vis spectroscopy. The XRD results revealed that tin oxide particles possessed typical orthorhombic structure and exhibited improved crystallinity with annealing. Calcination at 250 °C produced predominantly orthorhombic SnO which transformed to SnO at higher temperatures of 500 and 750 °C. HRTEM and FESEM images showed existence of agglomeration within the particles of tin oxide. The absorption was found to increase up to a certain annealing temperature followed by a decrease, which was recorded via UV-Vis spectroscopy. The effect of annealing temperature on dye decomposition behavior of synthesized photocatalysts was studied. It was noted that annealing temperature affects the size of synthesized particles, band gap width and photoactivity of tin oxide. The sample prepared at 500 °C followed first-order kinetics and exhibited maximum photocatalytic reactivity toward methylene blue. The experimental results obtained from the present study indicate that SnO is a promising and beneficial catalyst to remove contaminants from wastewater and environment. The antimicrobial evaluation of SnO annealed at 500 °C against selected targets such as E. coli and S. aureus depicted significant inhibition zones in comparison with 250 and 750 °C samples. Furthermore, molecular docking predictions of SnO nanoparticles (NPs) were performed against active pocket of β-lactamase and DNA gyrase enzyme belonging to cell wall and nucleic acid biosynthetic pathway, respectively. The fabricated NPs showed good binding score against β-lactamase of both E. coli (- 5.71 kcal/mol) and S. aureus (- 11.83 kcal/mol) alongside DNA gyrase (- 9.57 kcal/mol; E. coli and - 8.61 kcal/mol; S. aureus). These in silico predictions suggested SnO NPs as potential inhibitors for selected protein targets and will facilitate to have a clear understanding of their mechanism of action that may contribute toward new antibiotics discovery.
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http://dx.doi.org/10.1186/s11671-021-03495-1DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC7876220PMC
February 2021

Silver Decorated 2D Nanosheets of GO and MoS2 serve as Nanocatalyst for Water Treatment and Antimicrobial Applications as ascertained with Molecular Docking Evaluation.

Nanotechnology 2021 Feb 8. Epub 2021 Feb 8.

Physics, Government College University Lahore, Katchery Road, Lahore, Punjab, 54000, PAKISTAN.

Two-dimensional (2D) nanosheets doped with silver nanoparticles (AgNPs) have found significant antibacterial applications in industry. In this work, synthesis of graphene oxide (GO) and reduced graphene oxide (rGO) was realized through a modified Hummers route. Different concentrations (5 & 10 wt.%) of Ag were doped in MoS2 and rGO using a hydrothermal approach. Synthesized Ag-MoS2 and Ag-rGO were evaluated through XRD that confirmed the hexagonal structure of MoS2 along with the transformation of GO to Ag-rGO as indicated by a shift in XRD peaks. FTIR confirmed the presence of Mo-O bonding vibrations, and S=O functional groups present in the prepared samples. Morphological information of GO and formation of MoS2 nanopetals were verified through FESEM, while spherical morphology, interlayer spacing, and homogeneous distribution of AgNPs were scrutinized through HR-TEM. Raman analysis was employed to probe any evidence regarding defect densities of GO. Optical properties of GO, MoS2, Ag-rGO, and Ag-MoS2 were visualized through UV-Vis & PL spectroscopy. Prepared products were employed as nanocatalysts to purify industrial wastewater, while degradation of undoped and doped samples was inspected using UV-Vis spectroscopy. Experimental results revealed that the photocatalytic response of Ag-rGO and Ag-MoS2 enhanced upon doping. Besides, the nanocatalyst (Ag-MoS2 & Ag-rGO) exhibited an excellent antibacterial activity towards S. aureus gram positive (G+) and E. coli gram negative (G-). To rationalize biocidal mechanism of Ag-doped MoS2 NPs and Ag-rGO, in silico molecular docking study was employed for two enzymes (i.e. β-lactamase & ddlB) from cell wall biosynthetic pathway and FabI from fatty acid biosynthetic pathway belonging to S. aureus. The present study provides evidence for the development of cost-effective and environmental-friendly products that could receive favorable recommendation for use in industrial and biomedical applications.
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http://dx.doi.org/10.1088/1361-6528/abe43cDOI Listing
February 2021

Improving the Tensile and Tear Properties of Thermoplastic Starch/Dolomite Biocomposite Film through Sonication Process.

Polymers (Basel) 2021 Jan 15;13(2). Epub 2021 Jan 15.

Faculty of Chemical Engineering Technology, Universiti Malaysia Perlis (UniMAP), Arau 02600, Malaysia.

In this work, dolomite filler was introduced into thermoplastic starch (TPS) matrix to form TPS-dolomite (TPS-DOL) biocomposites. TPS-DOL biocomposites were prepared at different dolomite loadings (1 wt%, 2 wt%, 3 wt%, 4 wt% and 5 wt%) and by using two different forms of dolomite (pristine (DOL(P) and sonicated dolomite (DOL(U)) via the solvent casting technique. The effects of dolomite loading and sonication process on the mechanical properties of the TPS-DOL biocomposites were analyzed using tensile and tear tests. The chemistry aspect of the TPS-DOL biocomposites was analyzed using Fourier transform infrared spectroscopy (FTIR) and X-Ray Diffraction (XRD) analysis. According to the mechanical data, biocomposites with a high loading of dolomite (4 and 5 wt%) possess greater tensile and tear properties as compared to the biocomposites with a low loading of dolomite (1 and 2 wt%). Furthermore, it is also proved that the TPS-DOL(U) biocomposites have better mechanical properties when compared to the TPS-DOL(P) biocomposites. Reduction in the dolomite particle size upon the sonication process assisted in its dispersion and distribution throughout the TPS matrix. Thus, this led to the improvement of the tensile and tear properties of the biocomposite. Based on the findings, it is proven that the sonication process is a simple yet beneficial technique in the production of the TPS-dolomite biocomposites with improved tensile and tear properties for use as packaging film.
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http://dx.doi.org/10.3390/polym13020274DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC7830891PMC
January 2021

Fabrication and Characterization of Transparent and Scratch-Proof Yttrium/Sialon Thin Films.

Nanomaterials (Basel) 2020 Nov 18;10(11). Epub 2020 Nov 18.

Physics Department, King Fahd University of Petroleum & Minerals, Dhahran 31261, Saudi Arabia.

Transparent and amorphous yttrium (Y)/Sialon thin films were successfully fabricated using pulsed laser deposition (PLD). The thin films were fabricated in three steps. First, Y/Sialon target was synthesized using spark plasma sintering technique at 1500 °C in an inert atmosphere. Second, the surface of the fabricated target was cleaned by grinding and polishing to remove any contamination, such as graphite and characterized. Finally, thin films were grown using PLD in an inert atmosphere at various substrate temperatures (RT to 500 °C). While the X-ray diffractometer (XRD) analysis revealed that the Y/Sialon target has β phase, the XRD of the fabricated films showed no diffraction peaks and thus confirming the amorphous nature of fabricated thin films. XRD analysis displayed that the fabricated thin films were amorphous while the transparency, measured by UV-vis spectroscopy, of the films, decreased with increasing substrate temperature, which was attributed to a change in film thickness with deposition temperature. X-ray photoelectron spectroscopy (XPS) results suggested that the synthesized Y/Sialon thin films are nearly homogenous and contained all target's elements. A scratch test revealed that both 300 and 500 °C coatings possess the tough and robust nature of the film, which can resist much harsh loads and shocks. These results pave the way to fabricate different Sialon doped materials for numerous applications.
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http://dx.doi.org/10.3390/nano10112283DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC7698762PMC
November 2020

Photocatalytic, dye degradation, and bactericidal behavior of Cu-doped ZnO nanorods and their molecular docking analysis.

Dalton Trans 2020 Jun;49(24):8314-8330

Solar Cell Applications Research Lab, Department of Physics, Government College University Lahore, 54000, Punjab, Pakistan.

Nanostructures of Cu-doped ZnO (Cu:ZnO) were prepared with the chemical precipitation technique with an aim to enhance the photocatalytic and antibacterial properties of ZnO. Phase constitution, the presence of functional groups, optical properties, elemental composition, surface morphology and microstructure were evaluated using an X-ray diffractometer (XRD), Fourier transform infrared spectroscopy (FTIR), UV-Vis spectrophotometer, energy dispersive X-ray spectroscopy (EDS), field emission scanning electron microscope (FESEM) and high resolution transmission electron microscope (HR-TEM), respectively. Emission spectra were obtained with a photoluminescence (PL) spectroscope whereas interlayer d-spacing was estimated through HR-TEM. ZnO consisted of a hexagonal wurtzite structure. The crystallinity of the sample was observed to increase with increasing doping concentration. The addition of Cu to ZnO served to transform nanoclusters into nanorods as revealed during SEM analysis. Catalytic activity enhanced due to the formation of nanorods, and UV-Vis absorption spectra showed that methylene blue (MB) degraded more efficiently with ZnO nanoclusters compared to the NaBH4 reagent. In addition, the doped NPs showed enhanced bacterial efficiency for G +ve. Finally, a molecular docking study was undertaken to highlight the importance of the binding interactions of the Cu-doped ZnO nanorods with β-lactamase and beta-ketoacyl-acyl carrier protein synthase III (FabH) as possible enzyme targets. This research indicates that Cu-doped Zn nanorods are a highly efficient photocatalyst and can be aptly employed for wastewater treatment and antibacterial applications.
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http://dx.doi.org/10.1039/d0dt01397hDOI Listing
June 2020

Hydrothermal Synthesis of Silver Decorated Reduced Graphene Oxide (rGO) Nanoflakes with Effective Photocatalytic Activity for Wastewater Treatment.

Nanoscale Res Lett 2020 Apr 28;15(1):95. Epub 2020 Apr 28.

Department of Physics, Riphah Institute of Computing and Applied Sciences (RICAS), Riphah International University, 14 Ali Road, Lahore, Pakistan.

Graphene oxide (GO) was obtained through modified hummers method, and reduced graphene oxide (rGO) was acquired by employing heat treatment. Various concentrations (2.5, 5, 7.5, and 10 wt. %) of silver (Ag) were incorporated in GO nanosheets by adopting hydrothermal approach. Synthesized Ag decorated rGO photocatalyst Ag/rGO was characterized using X-ray diffraction (XRD) to determine phase purity and crystal structure. XRD patterns showed the formation of GO to Ag/rGO. Molecular vibration and functional groups were determined through Fourier Transform Infrared spectroscopy (FTIR). Optical properties and a decrease in bandgap with insertion of Ag were confirmed with UV-Visible (Uv-Vis) spectrophotometer and photoluminescence (PL). Electronic properties and disorders in carbon structures were investigated through Raman spectroscopy that revealed the existence of characteristic bands (D and G). Surface morphology of prepared samples was examined with field emission scanning electron microscope (FESEM). Homogeneous distribution, size, and spherical shape of Ag NPs over rGO sheets were further confirmed with the help of high-resolution transmission electron microscope (HR-TEM). Dye degradation of doped and undoped samples was examined through Uv-Vis spectra. Experimental results indicated that photocatalytic activity of [email protected] enhanced with increased doping ratio owing to diminished electron-hole pair recombination. Therefore, it is suggested that [email protected] can be used as a beneficial and superior photocatalyst to clean environment and wastewater.
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http://dx.doi.org/10.1186/s11671-020-03323-yDOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC7188753PMC
April 2020

Isolation and characterization of microcrystalline cellulose from date seeds (Phoenix dactylifera L.).

Int J Biol Macromol 2020 Jul 3;155:730-739. Epub 2020 Apr 3.

Department of Chemical and Process Engineering Technology, Jubail Industrial College, Jubail Industrial City 31961, Saudi Arabia.

This article reports the isolation and characterization of microcrystalline cellulose from date seeds of the date palm tree. The raw ground date seeds (RG-DS) are composed of cellulose matrix wrapped by lignin and hemicellulose as amorphous components. Cellulose was isolated from RG-DS through the following sequence: dewaxing, delignification/(bleaching) and acid hydrolysis. FTIR and Raman analysis for the bleached date seeds (B-DS) revealed the successful removal of the amorphous components from the polymer matrix. The X-ray diffractogram of the obtained (B-DS) exhibited the characteristic peaks of native cellulose (type I), with a crystallinity index (CrI = 62%). An additional acid hydrolysis step was used to convert native cellulose into microcrystalline cellulose (MCC-DS) with higher crystallinity (CrI = 70%). SEM analysis showed that the obtained microcrystals exhibit agglomerated and irregular elongated or semi-spherical shaped morphology. TEM analysis confirmed the semicrystalline nature of the MCC-DS. Thermal analysis showed enhanced thermal stability of MCC-DS. The current study shows the feasibility of using date seeds as a low-price source for obtaining MCC which is envisaged for applications in pharmaceutical and food industries as well as for preparing bionanocomposites with enhanced thermal properties.
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http://dx.doi.org/10.1016/j.ijbiomac.2020.03.255DOI Listing
July 2020

Donor-Pi-Acceptor Fluorene Conjugates, Based on Chalcone and Pyrimidine Derivatives: an Insight into Structure-Property Relationship, Photophysical and Electrochemical Properties.

J Fluoresc 2020 Mar 24;30(2):419-426. Epub 2020 Feb 24.

Center of Engineering Research, KFUPM, Dhahran, 31261, Kingdom of Saudi Arabia.

A small set of four new fluorenyl chromophores (5-5a-c) was accomplished by stepwise nucleophilic substitution, Friedel-Crafts acylation, Ullman coupling, aldol condensation and cyclization reactions. The fluorene moiety was substituted at 2,7,9 and 9' positions with diverse groups. The synthesized derivatives were characterized by FTIR, H-NMR and C-NMR spectroscopic techniques. The optical properties were evaluated by by UV-VIS absorption and Fluorescence studies. HOMO and LUMO energy levels were evaluated by electrochemical studies and were found at -5.37-5.83 eV and - 2.47-2.94 eV respectively with band gap energy values 2.88 to 2.91 eV. The band gap energy values suggested that these synthesized molecules can be manipulated in the designing of blue and green OLEDS. Graphical Abstract.
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http://dx.doi.org/10.1007/s10895-020-02516-zDOI Listing
March 2020

The Property Characterization of α-Sialon/Ni Composites Synthesized by Spark Plasma Sintering.

Nanomaterials (Basel) 2019 Nov 25;9(12). Epub 2019 Nov 25.

Department of Mechanical Engineering, Faculty of Engineering & Informatics, University of Bradford, Bradford BD7 1DP, UK.

This study investigates the effect of micron-sized nickel particle additions on the microstructural, thermal, and mechanical property changes of α-sialon ceramic composites. The α-sialon/Ni composites were synthesized with an increasing amount of Ni (10-40 wt.%) using the spark plasma sintering technique and nanosized alpha precursors at a relatively low synthesis temperature of 1500 °C with a holding time of 30 min in each case. The density of the samples increased with the increase in Ni content of up to 15 wt.% and, with the further increase in Ni content, it became almost constant with a slight decrease. Furthermore, thermal conductivity and thermal expansion properties of Ni-sialon composites improved slightly with the inclusion of 10 wt.% Ni. The addition of Ni to α-sialon matrix resulted in a decrease in the hardness of the composites from HV 21.6 to H 16.3, however the presence of Ni as a softer interfacial phase resulted in a substantial increase in the fracture toughness of these composites. Fracture toughness was found to increase by approximately 91% at 40 wt.% Ni addition.
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http://dx.doi.org/10.3390/nano9121682DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC6956311PMC
November 2019

Synthesis, characterization, and water adsorption properties of a novel multi-walled carbon nanotube/MIL-100(Fe) composite.

Dalton Trans 2016 Oct;45(39):15621-15633

Center of Engineering Research, KFUPM, Dhahran 31261, Kingdom of Saudi Arabia.

Conventional small-scale adsorption chillers generally employ silica-gel/water or zeolite/water working pairs given the relatively high level of mesoporosity and water affinity in these adsorbent materials. However, the coefficient of performance (COP) and specific cooling power (SCP) evaluated for the adsorption chiller using these adsorbent/adsorbate pairs cannot be still considered practically feasible in the context of a commercial system. Metal organic frameworks (MOFs) are not only characterized by much higher water adsorption capacities than these materials, but also can be mass-produced using much simpler methods than the template-assisted synthesis routes of most zeolites. However, the low intrinsic thermal conductivity of these materials limits their use as adsorbents in commercial-scale adsorption chillers. In this study, a novel composite composed of multi-walled carbon nanotubes (MWCNTs) incorporated in a MIL-100(Fe) framework has been synthesized using a molecular-level mixing process. The resulting composite, with varying volume fraction of MWCNTs, has been characterized for microstructure, degree of crystallinity, thermal stability, water sorption kinetics and hydrothermal cyclic stability for potential use as an adsorbent in commercial adsorption chillers.
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http://dx.doi.org/10.1039/c6dt02640kDOI Listing
October 2016