VOLUME 44, NO6, DEC-2022

A Fast Detection Method for Pesticide Residues by Spectrometry Technique

In this paper, a fast detection method for pesticide residues was proposed, and the qualitative and quantitative detection of the pesticide could be got at once by the method of solution of multiple linear regression equations which were obtained by dual wavelength absorbance and fluorescence spectrometry with least squares method. Moreover, it could detect two kinds of mixed pesticides. Four selected pesticides, aldicarb, fenitrothion, fenvalerate, and chlorothalonil were detected by the method. The results shown that there were good linear relationship in the range of 0.01-1 ppm, and R2 ＞ 0.90. And the method could 100% discriminate the four pesticide residues, the limit of detection was below 8 ppb both single one and mixed one. The recoveries of the pesticides in cabbage samples were observed 92.12%-107.50%. And the recoveries of the mixed pesticides in mineral water samples were observed 86.44%-114.10%. The preliminary study demonstrates that the proposed method has excellent potential application for the safety inspection of food.read more

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Jing Huang, Jincan Lei, Shixian Zhao and Yan Li

Surfactant-Free Facile Synthesis of Nickel Oxalate Monodispersed Particles in Novel Morphologies with Fine Tuning of the Experimental Variables

The surfactant or shape modifier used in the synthesis of monodispersed uniform fine particles affected the performance of the prepared powder in its applications. The present investigation is related to synthesizing colloidal uniform fine particles of nickel oxalate in novel morphologies under an optimized set of reaction conditions without using any surfactant or shape modifier. SEM results revealed that the reactant concentration significantly affected the characteristics of the precipitated solids, which ranged from gel to dispersion of discrete particles. Particles of uniform morphological features were obtained under an optimized set of experimental conditions, i.e., reactant concentration, temperature, aging time, etc. The molar ratio of the precursors affected the particle’s growth mechanism as the spherical morphology of the particles changed to a cubic shape by increasing nickel ion concentration in the recipe at 25 oC. The cubic morphology transformed into toffee shape bigger particles of a 0.5 axial ratio by increasing the reaction medium's thermal energy. The synthesized particles were characterized by various physical techniques, which confirmed the product as the monodispersed pure NiC2O4.2H2O particles.read more

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Khalida Akhtar, Ghazala Irum and Muhammad Gul

Kaolin-Calcium Carbonate-Titanium Dioxide (K-C-T) Composites for Decolourisation of Reactive Dye Effluent

Synthetic dyes in textile effluents cause serious environmental and aquatic life hazards if discharged in water bodies without decolorisation and removal of toxic substances. Efforts have been made to produce composites of Kaolin-CaCO3-TiO2 (K-C-T Composite) using the proportions of 1:1:1, 1:2:1 and 1:1:2 through calcination and assess their potential to remove colour from the effluents of Reactive Black 5 dye. Photocatalytic-composite adsorbent has been characterised for morphological structure, phase determination, band gap and Fourier-transform infrared spectroscopy for colour removal and dye decomposition studies. Studies show a maximum of 82% and 80% colour removal efficiency using 1:1:1 and 1:1:2 proportions of K-C-T composites respectively, calcined at 1000 °C. Surface area of the composite samples, state of titanium dioxide in the composite and band gap of the composite influences the colour removal from the effluent significantly.read more

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S. Tharakeswari, D. Saravanan, Ashwini K Agrawal and Manjeet Jassal

Application of Artificial Neural Network Technique for the Production of Biotoxin from the Locally Isolated Strain of Bacillus thuringiensis Bt. used as Biotoxin against Dengue Vector

In this study. a locally isolated strain of Bacillus thuringiensis that has insecticidal activity against dengue vector (larvae of Aedes aegypti), was cultivated. Different carbon and nitrogen sources were screened for enhanced bacterial growth. The factors affecting Bacillus thuringiensis’s biomass production like concentration of carbon, nitrogen, pH and temperature were optimized by one parameter at a time technique. The optimal levels of the selected parameters were also obtained by using an Artificial Neural Network (ANN). Peptone and molasses were selected as the best nitrogen and carbon sources respectively. The optimal levels obtained for nitrogen, carbon, pH and temperature by using the one parameter at a time technique were 1%, 0.25%, 8, and 37 ℃ respectively with 0.53 mg/mL biomass production. The ANN predicted levels were 1% for nitrogen, 0.25% for carbon, 9 pH and 31 ℃ for temperature with the predicted value of biomass being 0.85 mg/ml. The biomass produced at predicted optimum levels of variables was 0.82 mg/ml, very close to the predicted value of 0.85 mg/ml.read more

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Farzana Bashir, Yumna Sadef, Iqra Nadeem, Romana Shahzadi, Rubina Nelofer and Muhammad Tariq

Reduction Reactions of CO2 on Rutile TiO2 (110) Nanosheet via Coordination Activation

Based on the previous coordination catalysis theory, the active site on the surface of transition metal oxides can activate the CO2 molecule. Ultrathin two-dimensional (2D) rutile TiO2 nanosheet with (110) crystal face as the main exposed surface has many active sites of Ti3+ and O vacancy, which have some synergistic effects to greatly reduce the dissociation energy of CO2. Following previous assumptions, four possible reduction processes of CO2 on rutile TiO2 (110) surface were systematically assessed by density functional theory (DFT) simulations. The reduction reactions of CO2 along I faces difficultly in proceeding due to the relatively weak interaction between CO2 and the active surface. Additionally, along III, the adsorption configuration of CO2 in the pristine state has huge distinctions with the model that suggests that the defined route is unlikely to occur on the rutile TiO2 (110) surface. However, through carefully comparing the energy differences as well as transition state searching, the reduction reaction along II has a high probability of finishing and finally generating HCOOH on the surface owing to the minimal energy differences and low activation barrier. Furthermore, the reduction reaction of CO2 to CH4 guided along IV is predicted to more easily take place with the assistance of O vacancy on the active surface. The synergistic action among Ti3+ site, O vacancy, and H+ can aid in fixing molecular CO2 by breaking the strong bond of C=O in CO2 and generating different fuels via coordination activation. This work will not only provide strong theoretical support to previous assumptions but can also lighten the routes to explore more active catalysis towards the reduction of CO2.read more

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Xuemei Yang and Xiaohua Wang

Electrochemical Sensing of Luteolin from Straw Pyrolysis Carbon Prepared by Molten Salt Carbonization

In order to well use waste biomass and realise the quantitative analysis of luteolin, the sorghum straw from the old broom was used to prepare biomass carbon material (CMS-PCSS) through the molten salt carbonization. Then the CMS-PCSS was characterised by scanning electron microscopy (SEM), transmission electron microscopy (TEM), X-ray diffraction (XRD), X-ray photoelectron spectroscopy (XPS) Raman spectra (Raman), and N2 sorption analysis. In addition, the electrochemical performance of the CMS-PCSS based sensors was examined by electrochemical impedance spectroscopy (EIS) and cyclic voltammetry (CV). Under the first-rank experimental conditions, the electrochemical sensor established with this material performed well in the quantitative analysis and actual sample detection of luteolin, the detection range of luteolin was 0.05~10.0 μmol/L, and the actual achievable minimum detection limit was 0.019 μmol/L.read more

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Youluan Lu, Xinwei Mu, Yaopeng Liu, Zhen Shi, Yin Zheng, Wensheng Huang and Fangming Lou

Synthesis, Spectroscopic Characterization, and Anticancer Activity of Metal Complexes with a Novel Schiff Base Ligand from B-Diketone Derivatives

A new series complexes of Ni(II), Mn(II), Co(III), Cu(II), Cr(II), Zn(II), Zr(IV), Cd(II), and La(III) prepared by the reaction of the metal salt with a new Schiff base ligand. This Schiff base obtained by the condensation of p-phenylenediamine, 4-chlorobenzaldehyde, and acetyl acetone. The confirmation of the ligand and its metal complexes were characterized by multiple techniques such as, elemental analyses, magnetic susceptibility studies, FTIR 1H, 13C-NMR, XRD, molar conductance, UV-vis spectral analyses, and thermal analyses. The conductivity measurements of the complexes in DMF solutions indicated that the prepared complexes are nonelectrolytes. From the spectral data, an octahedral geometry was suggested for all complexes. The metal complex [(L)2Zr(Cl)2].3H2O showed the highest antifungal activity. The complexes [(L)(HL)Co(Cl)2].3H2O, and [(L)2Cd(H2O)2] showed antibacterial activities higher than the other complexes. All complexes are exhibited potent fungicides and bactericides than the ligand. Complex [(L)2Cd(H2O)2] exhibited considerable cytotoxicity against PC-3, SKOV3, and HeLa cells. The ligand C18H17N2OCl (HL) showed strong toxicity towards PC-3, HeLa cells, and moderate toxicity against SKOV3 cells.read more

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Ahmed N. Alhakimi, Thikra A. Almuhanna. Jawza Sh. Alnawmasi, S. El-Sayed Saeed and Ebtesam H. L. Alhamzi

Biosynthesis of Silver Nanoparticles using Echinacea pallida (Nutt.) Nutt. and Antioxidant Activity Thereof

In this work, silver nanoparticles (Ep-AgNPs) were synthesised using Echinacea pallida (Nutt.) Nutt. The dried leaves of E. pallida were collected and heated at 55 °C in deionized water, and filtered, and the leaf extract was treated with AgNO3 to produce the Ep-AgNPs. The Ep-AgNPs were analyzed by Ultraviolet-visible (UV-Vis), Fourier transform infrared (FTIR), X-ray diffraction (XRD), and scanning electron microscope (SEM). The characteristic hydroxyl gave the peak at 3147 cm-1. In UV-Vis analysis, observation of absorption band at 468 nm proved the achievement of Ep-AgNPs synthesis. SEM analysis presented the spherical shape of nanostructures with an average size of 77.82 nm. The face-centered crystal structure of Ep-AgNPs was revealed by the XRD analysis. The 1,1-diphenyl-2-picryl-hydrazyl radical (DPPH•) scavenging, ferric reducing antioxidant power (FRAP), 2,2'-azino-bis(3-ethylbenzothiazoline-6-sulphonic acid) radical cation (ABTS•+) assays were employed for antioxidant study in which Ep-AgNPs exhibited excellent antioxidant effect. Ep-AgNPs displayed outstanding DPPH• activity (6.34, IC50, µg/ml) compared to the standard BHT (10.78, IC50, µg/ml). The high activity was observed for ABTS•+ and reducing power assays as well. Hence, Ep-AgNPs could be a valuable material for the food and pharmaceutical industry.read more

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Esma Nur Gecer and Ramazan Erenler

Hydrogeochemical Evaluation of Groundwater of SITE Area, Karachi, Pakistan

In Karachi city presence of elevated concentration of various pollutants from natural and anthropogenic sources has caused the acute shortage of safe drinking water. The physicochemical data of different aquifers of Karachi were examined to elucidate the geochemistry and identify natural and anthropogenic processes controlling the quality of groundwater. Twenty four groundwater samples were collected from different localities of SITE area of Karachi. Physical and chemical characteristics of groundwater were determined using standards methods. Minor and trace metals (Fe, Zn, Co, Cu, Ni, Cr) were also determined to know the geochemical conditions of aquifers. Data was interpreted using multivariate statistical analysis. Groundwater of the area is mainly saline and 80 % water samples contain TDS above 500 ppm. Aquifers are dominated by HCO3 and Ca-Cl hydrofacies, which shows impact of seawater intrusion. Lateral distribution of groundwater pollution was investigated using Inverse Distance Weighting (IDW) technique using ArcMap, which indicates displacement of freshwater with seawater. In addition calcite and gypsum dissolution were also played a vital role to increase the salinity of the water. At few places mixing of sewage water and leaching through surface solid waste were also evident. Zinc concentration was high in 88% water samples. Lateral distribution of physicochemical parameters shows great heterogeneity, which indicates influence of local geology and land use pattern.read more

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Aneeq Mahmood Abbasi, Sanober Rafi, Sadaf Naseem and Yusra Rehman

Potential of Polyalthia longifolia Branches as a Biosorbent to Remove Textile Brilliant Yellow Dye from Aqueous Media

This study was conducted to analyze the efficacy of Polyalthia longifolia branches as an effective biosorbent for elimination of textile dye stuff brilliant yellow. Different operating conditions were tested (adsorbent dose, dye concentration, contact time, pH and temperature) to investigate their relationship with adsorption strength of Polyalthia longifolia and subsequently to eliminate toxic color. The absorbent was also characterized by Fourier Transform Infrared (FTIR). Optimum adsorption was observed at pH 6. Model of kinetic explored the adsorption data showing pseudo 2nd order with high correlation coefficient R2 of 0.996. Langmuir model followed well to equilibrium data relative to Freundlich and Temkin models. Thermodynamic property was also observed, where Gibbs free energy, entropy and enthalpy were analyzed. Through Gibbs free energy it was found that absorbent has endothermic nature. Thermodynamic properties have depicted that adsorption process was natural, endothermic and suitable for treatment of toxic dye.read more

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Sitara Anjum, Sana Ashraf, Sajid Rashid Ahmad, Muhammad Salman and Zahra Majid