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Ejaz, Ammara,Jeon, Seungwon Elsevier 2017 ELECTROCHIMICA ACTA Vol.245 No.-
<P><B>Abstract</B></P> <P>Highly stable electrochemical sensor based on strong π- π interactions between GO and XDA was fabricated for simultaneous as well as for individual detection of paracetamol (PCT) and ascorbic acid (AA). The oxidation potential of PCT and AA was greatly resolved with the decoration of Mn<SUB>2</SUB>O<SUB>3</SUB> nanospheres. We believe that, presence of metal oxide on the surface of GO-XDA will offer higher electrochemical performance with its large surface area and fast electron transfer ability. Therefore, a comparative study was executed in the presence and absence of Mn<SUB>2</SUB>O<SUB>3</SUB> nanospheres on the surface of GO-XDA. The GO-XDA-Mn<SUB>2</SUB>O<SUB>3</SUB> modified electrode showed electrocatalytic oxidation of PCT in a very wide linear range of 1×10<SUP>−6</SUP>–1×10<SUP>−3</SUP> M with limit of detection (LOD) and sensitivity of 5.6×10<SUP>−8</SUP> M, 527.04μAmM<SUP>−1</SUP>cm<SUP>−2</SUP> respectively and AA with 1×10<SUP>−5</SUP> –8×10<SUP>−3</SUP> M linear range, LOD and sensitivity of 6.0×10<SUP>−7</SUP> M, 655.74μAmM<SUP>−1</SUP>cm<SUP>−2</SUP> respectively. Furthermore, astonishing stability was found when GO-XDA-Mn<SUB>2</SUB>O<SUB>3</SUB> nanocomposite was stored for over a week. The proposed sensor displayed incredible selectivity, sensitivity and excellent recovery results for real samples with appreciable consistency and precision suggesting practical utility of the GO-XDA-Mn<SUB>2</SUB>O<SUB>3</SUB> as an effective and reliable electrochemical sensor for simultaneous as well as individual determination of PCT and AA.</P> <P><B>Highlights</B></P> <P> <UL> <LI> π–π interaction of graphene oxide (GO) with 1,4-xylenediamine (XDA) was studied. </LI> <LI> The synergistic effect of the Mn<SUB>2</SUB>O<SUB>3</SUB> nanospheres with GO-XDA was electrochemically studied in the detection of Paracetamol (PCT) and ascorbic acid (AA). </LI> <LI> The GO-XDA-Mn<SUB>2</SUB>O<SUB>3</SUB> accurately detected PCT and AA with LOD of 5.6×10<SUP>−8</SUP> M and 6.0×10<SUP>−7</SUP> M respectively. </LI> <LI> The GO-XDA-Mn<SUB>2</SUB>O<SUB>3</SUB> selectively detected PCT and AA simultaneously in the presence of DA, 5-HT and Glu with peak separation of 240mV. </LI> </UL> </P> <P><B>Graphical abstract</B></P> <P>[DISPLAY OMISSION]</P>
Ejaz Syeda Rabia,Khan Muhammad Azhar,Gulbadan Shagufta,Akhtar Majid Niaz,Ahmad Mukhtar,Hussain Altaf,Islam Misbah ul 한국세라믹학회 2022 한국세라믹학회지 Vol.59 No.4
Co 2+ and Cr 3+ -substituted SrBaCu Fe 28- y O 46 X-type hexaferrite with x = y = 0, 0.1 to 0.5 (step = 0.1) were prepared Co Cr 2- x x y through auto-combustion sol–gel method and sintered at 1250 °C for 5 h which was found from thermal analysis. The thermal investigation, phase detection, spectral, magnetic, and dielectric characteristics of the prepared composition were investigated by TGA, XRD, FTIR, VSM, and dielectric measurement. XRD patterns of the entire composition confi rmed the development of a single phase of X-type structure. The enhancement in the lattice parameters and cell volume was observed by varying the Co–Cr concentration, attributed to the larger ionic radii substitution. FTIR\spectra of all samples exhibit two absorption peaks in the wavenumber range of 500–550 cm −1 and 418–425 cm −1 that confi rm the formation of hexaferrite. The dielectric properties have been inspected based on frequency and substitution variation in the sample. The dielectric constant exhibits the increasing trend with the Co–Cr ratio. The enhancement in Ac conductivity was also found by increased substitution ions. Single semi-circles were examined in Nyquist plots, attributed to the contribution of the grain boundaries. Detailed magnetic parameters such as saturation magnetization, remanence, squareness ratio, coercivity, and magneto-crystalline anisotropy constant were measured. By the increase in Co–Cr substitution the increased of saturation magnetization ( Ms ) from 61.12 emu/g to 64.89 emu/g, the remanence ( Mr ) from 27.43 emu/g to 30.71 emu/g, and coercivity ( H c ) from 1654.56 Oe to 1863.54 Oe was found. Therefore, the synthesized SrBaCu 2 X-type hexagonal ferrites with the appropriate amount of Co–Cr substitution are suitable candidates for microwave devices and valuable in longitudinal recording media.
Determination of Bergenin in Different Parts of Bergenia ciliata using a Validated RP-HPLC Method
Ejaz Ali,Khalid Hussain,Nadeem Irfan Bukhari,Najma Arshad,Amjad Hussain,Nasir Abbas,Sohail Arshad,Sajida Parveen,Naureen Shehzadi,Shaista Qamar,Abida Qamar 한국생약학회 2021 Natural Product Sciences Vol.27 No.1
Bergenia ciliata (Family: Saxifragaceae) is a folklore remedy for the treatment of various ailments in Asian countries. Bergenin (1) has been isolated as an active constituent in many studies, however, the amount of bergenin has not been determined in all parts of the plant. A simple RP-HPLC method was developed to determine the amount of bergenin in methanol extracts of leaves, rhizomes and roots of the plant. Separation was achieved on an Agilent Eclipse XDB-C18 column maintained at 25 oC using isocratic solvent system (water: methanol: acetic acid; 62.5:37:0.5 v/v/v) adjusted at pH 2 0 at a flow rate of 1.0 mL/min. and detected at 275 nm. Correlation coefficient (0.9952) showed linearity of concentration (5-200 μg/mL) and response. The values of LOD (0.00947 μg/mL) and LOQ (0.02869 μg/mL) indicated that method was sensitive. The recovery of bergenin was 99.99-100% indicating accuracy of method. The methanol extract of rhizomes contained higher amount of bergenin (19.4%) than roots (9.2%) and leaves (6.9%). It is concluded that methanol extract of rhizomes is a better source of bergenin than other parts of the plant. The findings are useful for standardization of bergenin containing extracts and herbal preparations.
ON LIGHTLIKE HYPERSURFACES OF COSYMPLECTIC SPACE FORM
Ejaz Sabir Lone,Pankaj Pandey Korean Mathematical Society 2023 대한수학회논문집 Vol.38 No.1
The main purpose of this paper is to study the lightlike hypersurface (M, $\overline{g}$) of cosymplectic space form $\overline{M}$(c). In this paper, we computed the Gauss and Codazzi formulae of (M, $\overline{g}$) of cosymplectic manifold ($\overline{M}$, g). We showed that we can't obtain screen semi-invariant lightlike hypersurface (SCI-LH) of $\overline{M}$(c) with parallel second fundamental form h, parallel screen distribution and c ≠ 0. We showed that if second fundamental form h and local second fundamental form B are parallel, then (M, $\overline{g}$) is totally geodesic. Finally we showed that if (M, $\overline{g}$) is umbilical, then cosymplectic manifold ($\overline{M}$, g) is flat.
Ejaz, Ammara,Jeon, Seungwon Pergamon Press 2017 Electrochimica Acta Vol. No.
<P><B>Abstract</B></P> <P>In present work, we prepared nitrogen doped graphene oxide (N-GO) by using 1,3-xylenediamine (XDA) as nitrogen precursor which was further decorated with Co(OH)<SUB>2</SUB> nanoflower. The physiochemical analysis such as X-ray photoelectron spectroscopy and scanning electron microscopy revealed the successful doping of nitrogen on GO and fine dispersion of Co(OH)<SUB>2</SUB> nanoflower on the surface of N-GO. The as prepared N-GO-Co(OH)<SUB>2</SUB> was electrochemically reduced (N-rGO-Co(OH)<SUB>2</SUB>) to precisely adjust its electrochemical properties. The N-rGO-Co(OH)<SUB>2</SUB> was used as a novel electrode modifier for the simultaneous detection of dopamine (DA) and uric acid (UA). From the combined effects of N-doping and excellent electrocatalytic properties of the Co(OH)<SUB>2</SUB> nanoflower, constructed sensor exhibited high electrochemical sensing activity with the wide linear response, limit of detection and limit of quantification of 1.0×10<SUP>−8</SUP> M and 3.0×10<SUP>−8</SUP> M for DA and 1.0×10<SUP>−7</SUP> M and 3.6×10<SUP>−7</SUP> M for UA respectively. The N-rGO-Co(OH)<SUB>2</SUB> nanocomposite showed long-term sensing stability, reproducibility and excellent analytical response in urine for DA and UA detection. Furthermore, N-rGO-Co(OH)<SUB>2</SUB> also revealed remarkable anti-interfering behavior towards other biomolecules including ascorbic acid (AA), serotonin (5-HT) and glucose (Glu). The N-rGO-Co(OH)<SUB>2</SUB> nanocomposite manifests intriguing application potential as the candidate for the application of the electrochemical sensor for simultaneous detection of DA and UA.</P>
Ejaz, A.,Joo, Y.,Jeon, S. Elsevier Sequoia 2017 Sensors and actuators. B Chemical Vol.240 No.-
A simple electrochemical sensor for detecting dopamine was fabricated using 1,4-bis(aminomethyl)benzene (BAMB) and cobalt hydroxide (Co(OH)<SUB>2</SUB>) at graphene oxide (GO) surface using a simple solution-based chemical reduction method. The successful formation of GO-BAMB-Co(OH)<SUB>2</SUB> was confirmed by transmission electron microscopy and X-ray photoelectron spectroscopy, while the electrochemical performance of the material was studied using different techniques, including cyclic voltammetry, differential pulse voltammetry, linear sweep voltammetry, and chronoamperometry in 0.1M PBS at pH 7.4. The GO-BAMB-Co(OH)<SUB>2</SUB>-modified electrode showed an excellent electrochemical response with a broad linear range (3-20 and 25-100μM) and low limit of detection (0.4μM). Furthermore, efficient selective detection of dopamine in the presence of a 10-fold excess concentration of bio-interfering species, such as ascorbic acid and serotonin, was remarkable. The practical feasibility of the sensor was checked using urine samples, which showed appreciable recovery results. The main advantages of this sensor are its simple electrode fabrication procedure, rapid sensing response, remarkable selectivity, repeatability, and stability.