| 1. |
- Bashir, Amna, et al.
(författare)
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Cu-doped nickel oxide interface layer with nanoscale thickness for efficient and highly stable printable carbon-based perovskite solar cell
- 2019
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Ingår i: Solar Energy. - : PERGAMON-ELSEVIER SCIENCE LTD. - 0038-092X .- 1471-1257. ; 182, s. 225-236
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Tidskriftsartikel (refereegranskat)abstract
- The power conversion efficiency (PCE) of hole conductor free carbon-based perovskite solar cells (PSCs) is restricted by the poor charge extraction and recombination losses at the carbon-perovskite interface. For the first time we successfully demonstrated incorporation of thin layer of copper doped nickel oxide (Cu:NiOx) nanoparticles in carbon-based PSCs, which helps in improving the performance of these solar devices. Cu:NiOx nanoparticles have been synthesized by a facile chemical method, and processed into a paste for screen printing. Extensive X-ray Absorption Spectroscopy (XAS) analysis elucidates the co-ordination of Cu in a NiOx matrix and indicates the presence of around 5.4% Cu in the sample. We fabricated a monolithic perovskite module on a 100 cm(2) glass substrate (active area of 70 cm(2)) with a thin Cu:NiOx layer (80 nm), where the champion device shows an appreciated power conversion efficiency of 12.1% under an AM 1.5G illumination. To the best of our knowledge, this is the highest reported efficiency for such a large area perovskite solar device. I-V scans show that the introduction of Cu:NiOx mesoporous scaffold increases the photocurrent, and yields fill factor (FF) values exceeding 57% due to the better interface and increased hole extraction efficiency. Electrochemical Impedance Spectroscopy (EIS) results reinforce the above results by showing the reduction in recombination resistance (R-rec) of the PSCs that incorporates Cu:NiOx interlayer. The perovskite solar modules with a Cu:NiOx layer are stable for more than 4500 h in an ambient environment (25 degrees C and 65% RH), with PCE degradation of less than 5% of the initial value.
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| 2. |
- Hafeez, Abdul, et al.
(författare)
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Synthesis, Crystal Structures, and Spectroscopic Characterization of Bis-aldehyde Monomers and Their Electrically Conductive Pristine Polyazomethines
- 2019
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Ingår i: Polymers. - : MDPI. - 2073-4360. ; 11:9
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Tidskriftsartikel (refereegranskat)abstract
- Bis-aldehyde monomers 4-(4′-formyl-phenoxy)benzaldehyde (3a), 3-methoxy-4-(4′-formyl-phenoxy)benzaldehyde (3b), and 3-ethoxy-4-(4′-formyl-phenoxy)benzaldehyde (3c) were synthesized by etherification of 4-fluorobenzaldehyde (1) with 4-hydroxybenzaldehyde (2a), 3-methoxy-4-hydroxybenzaldehyde (2b), and 3-ethoxy-4-hydroxybenzaldehyde (2c), respectively. Each monomer was polymerized with p-phenylenediamine and 4,4′-diaminodiphenyl ether to yield six poly(azomethine)s. Single crystal X-ray diffraction structures of 3b and 3c were determined. The structural characterization of the monomers and poly(azomethine)s was performed by FT-IR and NMR spectroscopic techniques and elemental analysis. Physicochemical properties of polymers were investigated by powder X-ray diffraction, thermogravimetric analysis (TGA), viscometry, UV–vis, spectroscopy and photoluminescence. These polymers were subjected to electrical conductivity measurements by the four-probe method, and their conductivities were found to be in the range 4.0 × 10−5 to 6.4 × 10−5 Scm−1, which was significantly higher than the values reported so far.
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| 3. |
- Kanwal, Sehrish, et al.
(författare)
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Poly-thiourea formaldehyde based anticorrosion marine coatings on type 304 stainless steel
- 2020
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Ingår i: Journal of Materials Research and Technology. - : Elsevier. - 2238-7854. ; 9:2, s. 2146-2153
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Tidskriftsartikel (refereegranskat)abstract
- In the present study, hexamethylene diisocyanate (HMDI) encapsulated poly-thiourea formaldehyde (PTF) (10 wt%) coating was developed in an epoxy-polyamine matrix and their anticorrosion studies on Type SS304 stainless steel substrate have been conducted using electrochemistry techniques. The compact and hydrophobic shell wall of PTF proved to be a potent shell wall material for HMDI encapsulation. The effect of temperature and pH values was found to be decisive factor in the synthesis of microcapsules. The PTF microcapsules were synthesized in acidic condition with a pH value of 3. Over 90% of the core fraction is retained in water after 21 days immersion. However, core content decreased with increasing temperature. The capsules were characterized by Fourier transform infrared spectroscopy (FTIR), scanning electron microscopy(SEM), thermogravimetric analysis (TGA) and Electrochemical Impedance spectroscopy (EIS). Scanning electron microscopic analysis depicts the uniform morphology of coating with a particle size in the range of 1.08 μm–22.06 μm. The vibrational band at 2271 cm−1 attributed to NCO signal further endorses the successful encapsulation of HMDI into the PTF capsules. Electrochemical testing on steel specifies the appreciable anticorrosion performance of the synthesized poly thiourea formaldehyde (PTF) coating against artificial sea water.
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| 4. |
- Mushtaq, Irrum, et al.
(författare)
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Engineering electroactive and biocompatible tetra(aniline)-based terpolymers with tunable intrinsic antioxidant properties in vivo
- 2020
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Ingår i: Materials science & engineering. C, biomimetic materials, sensors and systems. - : Elsevier. - 0928-4931 .- 1873-0191. ; 108
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Tidskriftsartikel (refereegranskat)abstract
- Under different pathological conditions, high levels of reactive oxygen species (ROS) cause substantial damage to multiple organs. To counter these ROS levels in multiple organs, we have engineered highly potent novel terpolymers. We found that combination of FDA-approved polyethylene glycol, fumaric acid moieties and electroactive tetra(aniline) by varying the content of tetra(aniline) results into a novel drug composition with biologically active tunable intrinsic antioxidant properties. To test tunable intrinsic antioxidative properties of these engineered novel terpolymers, we used alloxan to induce diabetes in rats where ROS generation is known to be higher. The systemic administration of terpolymers to the diabetic rats showed strong electroactive antioxidant behavior which normalized ROS levels, enzymatic antioxidants including superoxide dismutase, catalase, but also reduced glutathione. As a proof-of-principle, we here show TANI based novel drug composition of terpolymers with tunable intrinsic antioxidant effects confirmed in multiple organs.
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| 5. |
- Mushtaq, Irrum, et al.
(författare)
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Ferrocene-Based Terpolyamides and Their PDMS-Containing Block Copolymers: Synthesis and Physical Properties
- 2022
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Ingår i: Polymers. - : MDPI. - 2073-4360. ; 14:23
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Tidskriftsartikel (refereegranskat)abstract
- Aromatic polyamides are well-known as high-performance materials due to their outstanding properties making them useful in a wide range of applications. However, their limited solubility in common organic solvents restricts their processability and becomes a hurdle in their applicability. This study is focused on the synthesis of processable ferrocene-based terpolyamides and their polydimethylsiloxane (PDMS)-containing block copolymers, using low-temperature solution polycondensation methodology. All the synthesized materials were structurally characterized using FTIR and 1H NMR spectroscopic techniques. The ferrocene-based terpolymers and block copolymers were soluble in common organic solvents, while the organic analogs were found only soluble in sulfuric acid. WXRD analysis showed the amorphous nature of the materials, while the SEM analysis exposed the modified surface of the ferrocene-based block copolymers. The structure–property relationship of the materials was further elucidated by their water absorption and thermal behavior. These materials showed low to no water absorption along with their high limiting oxygen index (LOI) values depicting their good flame-retardant behavior. DFT studies also supported the role of various monomers in the polycondensation reaction where the electron pair donation from HOMO of diamine monomer to the LUMO of acyl chloride was predicted, along with the calculation of various other parameters of the representative terpolymers and block copolymers.
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| 6. |
- Mushtaq, Irrum, et al.
(författare)
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Tunable Self-Assembled Nanostructures of Electroactive PEGylated Tetra(Aniline) Based ABA Triblock Structures in Aqueous Medium
- 2019
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Ingår i: Frontiers in Chemistry. - : Frontiers Media S.A.. - 2296-2646. ; 7, s. 1-10
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Tidskriftsartikel (refereegranskat)abstract
- PEGylated tetra(aniline) ABA triblock structure PEG-TANI-PEG (2) consisting of tetra(aniline) (TANI) and polyethylene glycol (PEG) was synthesized by coupling the tosylated-PEG to boc-protected NH2/NH2 TANI (1) through a simple nucleophilic substitution reaction. Deprotection of 2 resulted in a leucoemeraldine base state of TANI (2-LEB), which was oxidized to stable emeraldine base (2-EB) state. 2-EB was doped with 1 M HCl to emeraldine salt (2-ES) state. FTIR, 1H and 13C NMR and UV-Vis-NIR spectroscopy, and MS (ESI) was used for structural characterization. The synthesized triblock structure exhibited good electroactivity as confirmed by CV and UV-Vis-NIR spectroscopy. Self-assembling of the triblock structure in aqueous medium was assessed by DLS, TEM, and SEM. Spherical aggregates were observed with variable sizes depicting the effect of concentration and oxidation of 2-LEB. Further, the aggregates showed acid/base sensitivity as evaluated by doping and dedoping of 2-EB with 1 M HCl and 1 M NH4OH, respectively. Future applications in drug delivery and sensors are envisaged for such tunable self-assembled nanostructures in aqueous media.
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| 7. |
- Nazir, Uzma, et al.
(författare)
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Biferrocenyl Schiff bases as efficient corrosion inhibitors for an aluminium alloy in HCl solution : a combined experimental and theoretical study
- 2020
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Ingår i: RSC Advances. - : Royal Society of Chemistry. - 2046-2069. ; 10:13, s. 7585-7599
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Tidskriftsartikel (refereegranskat)abstract
- The corrosion inhibitive capabilities of some ferrocene-based Schiff bases on aluminium alloy AA2219-T6 in acidic medium were investigated using Tafel polarization, electrochemical impedance spectroscopy (EIS), weight loss measurement, FT-IR spectroscopy and scanning electron microscopic (SEM) techniques. The influence of molecular configuration on the corrosion inhibition behavior has been explored by quantum chemical calculation. Ferrocenyl Schiff bases 4,4′-((((ethane-1,2-diylbis(oxy))bis(4,1-phenylene))bis(methaneylylidene))bis(azaneylylidene))bisferrocene (Fcua), 4,4′-((((ethane-1,2-diylbis(oxy))bis(2-methoxy-1,4-phenylene))bis(methaneylylidene))bis(azaneylylidene))bisferrocene (Fcub) and 4,4′-((((ethane-1,2-diylbis(oxy))bis(2-ethoxy-1,4-phenylene))bis(methaneylylidene))bis(azaneylylidene))bisferrocene (Fcuc) have been synthesized and characterized by FT-IR, 1H and 13C NMR spectroscopic studies. These compounds showed a substantial corrosion inhibition against aluminium alloy in 0.1 M of HCl at 298 K. Fcub and Fcuc showed better anticorrosion efficiency as compared with Fcua due to the electron donating methoxy and ethoxy group substitutions, respectively. Polarization curves also indicated that the studied biferrocenyl Schiff bases were mixed type anticorrosive materials. The inhibition of the aluminium alloy surface by biferrocenyl Schiff bases was evidenced through scanning electron microscopy (SEM) studies. Semi-empirical quantum mechanical studies revealed a correlation between corrosion inhibition efficiency and structural functionalities.
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| 8. |
- Nazir, Uzma, et al.
(författare)
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Experimental and theoretical insights into the corrosion inhibition activity of novel Schiff bases for aluminum alloy in acidic medium
- 2019
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Ingår i: RSC Advances. - : Royal Society of Chemistry. - 2046-2069. ; 9:62, s. 36455-36470
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Tidskriftsartikel (refereegranskat)abstract
- Three novel Schiff bases, namely N-(4-((4-((phenylimino)methyl)phenoxy)methoxy)benzylidene)benzenamine (UA), N-(3-methoxy-4-((2-methoxy-4-((phenylimino)methyl)phenoxy)methoxy)benzylidene)benzenamine (UB), and N-(3-ethyl-4-((2-ethyl-4-((phenylimino)methyl)phenoxy)methoxy)benzylidene)benzenamine (UC), were synthesized and their structures were elucidated through diverse spectroscopic techniques such as FT-IR, GC-MS, 1H NMR and 13C NMR. The corrosion inhibition effect of these Schiff bases on aluminum alloy AA2219-T6 in acidic medium was explored using weight loss, Tafel polarization, and electrochemical impedance spectroscopy. Theoretical quantum chemical calculations using density functional theory were employed to determine the adsorption site. It was found that inhibition efficiencies increase with an increase in the inhibitor concentration. Tafel plots showed that these Schiff bases function as mixed inhibitors. Adsorption of the Schiff bases on aluminum followed the Langmuir adsorption isotherm and the value of showed a dominant chemical mechanism. FT-IR and SEM techniques were used to investigate the surface morphology. The compounds showed a substantial corrosion inhibition for aluminum alloy in 0.1 M HCl at 298 K. UB and UC exhibited superior anticorrosion efficiency compared to UA originating from the electron-donating methoxy and ethoxy group substitutions, respectively. There was found to be good correlation between molecular structure and inhibition efficiencies.
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| 9. |
- Shah, Faiz Ullah, et al.
(författare)
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Influence of Ferrocene and Transition Metals on the Biological Activities of Schiff Bases
- 2016
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Ingår i: Journal of the Chemical Society of Pakistan. - 0253-5106. ; 38:6, s. 1112-1120
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Tidskriftsartikel (refereegranskat)abstract
- A series of organic and organometallic Schiff bases bearing phenylferrocene and their six transition metal complexes have been prepared and tested for their potential biological applications by using antifungal, antibacterial, antitumor activities, toxicity testing against the brine shrimp and DNA damage analysis. The copper and cobalt complexes of organic Schiff base showed significant antibacterial activity. The antifungal activities tested against six fungal strains revealed that N-(4-hydroxybenzylidene) aniline (A5) had the highest antifungal activity. Most of these compounds showed cytotoxic activity against the brine shrimp. The results of showed that these compounds had significant antitumor activity, up to 97% in the case of N-(4-chlorobenzylidene) aniline (A3). Only two compounds N-(2-hydroxy benzylidene) 4-ferrocenylaniline (F2) and Nickel (II) complex of organic Schiff base (CO2) had DNA damaging activity at 20mg/ml concentration.
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| 10. |
- Shah, Faiz Ullah, et al.
(författare)
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Solid-state 13C, 15N and 29Si NMR characterization of block copolymers with CO2 capture properties
- 2016
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Ingår i: Magnetic Resonance in Chemistry. - : Wiley. - 0749-1581 .- 1097-458X. ; 54:9, s. 734-739
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Tidskriftsartikel (refereegranskat)abstract
- Natural abundance solid-state multinuclear (13C, 15N and 29Si) cross-polarization magic-angle-spinning NMR was used to study structures of three block copolymers based on polyamide and dimethylsiloxane and two polyamides, one of which including ferrocene in its structure. Assignment of most of the resonance lines in 13C, 15N and 29Si cross-polarization magic angle-spinning NMR spectra were suggested. A comparative analysis of 13C isotropic chemical shifts of polyamides with and without ferrocene has revealed a systematic shift towards higher δ -values (de-shielding) explained as the incorporation of paramagnetic ferrocene into the polyamide backbone. In addition, the 13C NMR resonance lines for ferrocene-based polyamide were significantly broadened, because of paramagnetic effects from ferrocene incorporated in the structure of this polyamide polymer. Single resonance lines with chemical shifts ranging from 88.1 to 91.5ppm were observed for 15N sites in all of studied polyamide samples. 29Si chemical shifts were found to be around 22.4ppm in polydimethylsiloxane samples that falls in the range of chemical shifts for alkylsiloxane compounds. The CO2 capture performance of polyamide-dimethylsiloxane-based block copolymers was measured as a function of temperature and pressure. The data revealed that these polymeric materials have potential to uptake CO2 (up to 9.6 cm3 g1) at ambient pressures and in the temperature interval 30–40 °C. Copyright ©2016 John Wiley & Sons, Ltd.
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