Preconcentration of Co, Ni, Cd and Zn on naphthalene–2,4,6-trimorpholino-1,3,5-triazin adsorbent and flame atomic absorption determination

A preconcentration method was developed for the determination of trace amounts of Co, Ni, Cd and Zn by atomic absorption spectrometry. The method is based on the retention of the metal cations by naphthalene–2,4,6-trimorpholino-1,3,5-triazin adsorbent in a column. The adsorbed metals were then eluted from the column with hydrochloric acid and the Co, Ni, Cd and Zn were determined by flame atomic absorption spectrometry. The optimal extraction and elution conditions were studied. The effects of diverse ions on the preconcentration were also investigated. A preconcentration factor of 250 for Co(II), Ni(II) and Zn(II), and 400 for Cd(II) can easily be achieved. Calibration graphs were obtained and the detection limits of the method for Co(II), Ni(II), Cd(II) and Zn(II) were 0.51, 0.49, 0.17 and 0.10 ng mL-1, respectively. The relative standard deviations (RSD) of 0.37–2.31 % for Co, 0.37–3.73 % for Ni, 2.20–2.40 % for Cd and 1.50–2.56 % for Zn were obtained. The method was also used for the simultaneous preconcentration of these elements and the method was successfully applied to their preconcentration and determination. The method was applied to the determination of Co, Ni, Cd and Zn in several real samples

Tribromoisocyanuric Acid/NaNO2: a New Reagent for Mononitration of Phenols under Mild and Heterogeneous Conditions

Nitrophenols can be obtained via direct nitration of phenols with tribromoisocyanuric acid,NaNO2 and wet SiO2 at room temperature in good to high yields.KEYWORDS: Tribromoisocyanuric acid, nitrophenols, heterogeneous conditions, sodium nitrite, nitration of phenols

Osjetljivo kinetičko-spektrofotometrijsko odre|ivanje SbIII temeljeno na njegovu inhibitornome djelovanju na reakciju dekoloriranja indikatora

A method for rapid and accurate determination of trace quantities of SbIII was developed based on its inhibitory effect on the decolorizing reaction of methyl orange in the presence of bromate and bromide ions in acidic media. Decolorization of methyl orange by the reaction products was used to monitor the reaction spectrophotometrically at 525 nm. The method allows determination of antimony in the range 10–5000 μg dm–3. The relative standard deviation for ten determinations of 500 μg dm–3 antimony is 1.21 % and the detection limit of the method is 8.0 μg dm–3. The method is applied to the determination of antimony in natural water samples.Razvijena je metoda za brzo i precizno određivanje tragova SbIII temeljena na inhibitornome djelovanju na reakciju dekoloriranja metil oranža uz bromate i bromidne ione u kiselom mediju. Upotrebljeno je dekoloriranje metil oranža s reakcijskim produktima za praćenje reakcije spektrofotometrijski kod 525 nm. Predložena metoda dopušta određivanje antimona u koncentracijama od 10 do 5000 μg dm–3. Relativna standardna devijacija za deset određivanja uzoraka od 500 μg dm–3 bila je 1.21%, a granica osjetljivosti metode bila je 8.0 μg dm–3. Metoda je uporabljena za određivanje antimona u uzorcima prirodnih voda

INVESTIGATING THE RELATIONSHIP BETWEEN CORPORATE GOVERNANCE RANKING AND EARNINGS MANAGEMENT IN COMPANIES LISTED IN TEHRAN STOCK EXCHANGE

Abstract Joint stock companies play a major role in the economy and their success depends on willingness of investors and creditors to invest in these companies. Managers' tendency to apply earnings management and abusing it which leads to providing false information can seriously destroy the trust of shareholders and cause thousands of shareholders to be harmed and run away from the stock market. Hence, due to the importance of keeping shareholders, the present paper seeks ways based on which financiers are assured that they will get good returns on their investment in the company. Shareholders play an essential role in the system of corporate governance, because they are the suppliers of companies' capital and maintaining their trust is of utmost importance. Among the principles of corporate governance whose impact on earnings management is investigated by the present study, it can be pointed to institutional ownership of major shareholders and the ratio of non-executive directors to total directors. In this study, discretionary accruals using the modified Jones model has been applied as an index for determining earnings management. In this regard, the information of 98 companies during 2005-2011 has been used. To rate the mechanisms of corporate governance, TOPSIS ranking method which is one of the MCDM approaches has been used. After ranking, companies were divided into two groups including high-rank and low-rank companies. According to the results of this study, less earnings management is observed in companies with high rates of corporate governance; namely, the lower the rate of corporate governance is, the higher the earnings management will be. In the companies with high-rate corporate governance, due to the increased managerial control (earnings management) and transparency of financial information, the trust of shareholders and the amount of investment increase

A sensitive method for electrochemical determination of molybdenum (VI) in plant foodstuff samples using Ni0.5Zn0.5Fe2O4 nanocomposite modified carbon paste electrode

In the present study, a new chemically modified carbon paste electrode (CPE) is constructed for rapid, accurate, simple, highly sensitive, and selective determination of Mo (VI) using differential pulse voltammetry. The electrode was prepared using magnetic nickel zinc ferrite nanocomposite (Ni0.5Zn0.5Fe2O4), as the modifier in CPE (Ni0.5Zn0.5Fe2O4/CPE). Mo (VI) was determined after preconcentration at the surface of the modified electrode at -0.7 V vs. Ag/AgCl. Under the optimal conditions, the linear dynamic range and limit of detection were 0.005-1.00 and 0.003 µgmL-1, respectively. Ten successive measurements of 0.06 and 0.70 µg mL-1 of Mo (VI) ions showed the relative standard deviation of 3.20 and 1.98 %, respectively. The reproducibility and stability of the electrode response were also studied. Investigation of the effects of different cations and anions on the determination of Mo (VI) indicated that the electrode is highly selective. Furthermore, the present method was applied to the determination of Mo (VI) in several plant foodstuff samples with satisfactory results

Aerosol assisted synthesis of a pH responsive curcumin anticancer drug nanocarrier using chitosan and alginate natural polymers

In recent years, several nanocarrier synthesis methods have been developed. In cancer therapy, the use of smart nanocarriers is of interest. Smart nanocarriers respond to their environment and can release their cargo in a controlled manner under the action of internal or external stimuli. In this work, we report on the development of an aerosol-assisted method for the synthesis of curcumin-loaded chitosan/alginate-based polymeric nanocarrier (CurNCs). A custom-fabricated multi-nebulizer system was utilized for the synthesis of CurNCs. The developed system comprises three main parts a sprayer, an electric heater tunnel, and a collector. Curcumin and chitosan solutions were sprayed using a pneumatic multinebulizer into the electric heater tunnel to form chitosan-curcumin assemblies. Then, the aerosol was guided into the collector solution containing sodium alginate and tri-poly phosphate aqueous solution for further cross-linkage. The synthesized CurNCs were characterized using TEM, DLS, and FTIR techniques. The TEM size of the nanoparticles was 8.62 ± 2.25 nm. The release experiments revealed that the nanocarrier is sensitive to the environment pH as more curcumin is released at acidic pH values (as is the case for cancerous tissues) compared to physiological pH. The curcumin content of the nanocarrier was 77.27 mg g−1 with a drug loading efficiency of 62%. The in-vitro cytotoxicity of the synthesized nanocarrier was evaluated against the MCF7 breast cancer cell line. The IC50 concentrations for CurNCs and curcumin were obtained as 14.86 and 16.45 mg mL−1, respectively. The results showed that while the empty nanocarrier shows non-significant cytotoxicity, the CurNCs impact the cell culture and cause prolonged cell deaths. Overall, pH-responsive curcumin polymeric nanocarrier was synthesized using a custom fabricated aerosol-based method. The method enabled fast and feasible synthesis of the nanocarrier with high efficiency.This work has been supported by grants from the Bu-Ali Sina University Research Council and the Centre of Excellence in Development of Environmentally Friendly Methods for Chemical Synthesis (CEDEFMCS) which are gratefully acknowledged

Copper(II)–Thymine Coordination Polymer Nanoribbons as Potential Oligonucleotide Nanocarriers

This is the peer reviewed version of the following article: Vegas, V. G., Lorca, R., Latorre, A., Hassanein, K., Gómez‐García, C. J., Castillo, O., ... & Amo‐Ochoa, P. (2017). Copper (II)–Thymine Coordination Polymer Nanoribbons as Potential Oligonucleotide Nanocarriers. Angewandte Chemie International Edition, 56(4), 987-991, which has been published in final form at https://doi.org/10.1002/anie.201609031. This article may be used for non-commercial purposes in accordance with Wiley Terms and Conditions for Use of Self-Archived VersionsThe direct reaction between copper nitrate, thymine-1-acetic acid, and 4,4′-bipyridine in water leads to the formation of a blue colloid comprising uniform crystalline nanoribbons (length >1 μm; width ca. 150–185 nm; diameter ca. 15–60 nm) of a coordination polymer. The polymer displays a thymine-based structure freely available for supramolecular interactions. These nanostructures show significant selective interaction with single-stranded oligonucleotides based on adenine. Remarkably, they present low cell toxicity in three cell lines–despite the copper(II) content–and can be used as nanocarriers of oligonucleotides. These results suggest the potential of these types of nanostructures in several biological applicationsFinancial support from the Spanish Ministerio de Economía y Competitividad (MAT2016‐75883‐C2‐2‐P, MAT2016‐77608‐C3‐1‐P, MAT2013‐46502‐C2‐1P/2P, MAT2013‐46753‐C2‐1‐P, MAT2010‐20843‐C02‐01, SAF2014‐56763‐R), Asociación Española Contra el Cáncer, Generalitat Valenciana (PrometeoII/2014/076 and ISIC) and EU (FP6‐029192). R.L. thanks the Chilean Ministry of Education CONICYT (PhD Scholarship: BECA CHILE) for financial suppor

Total sulfur determination in liquid fuels by ICP-OES after oxidation-extraction desulfurization using magnetic graphene oxide

This paper presents a graphene oxide-based magnetic nanocomposite as a catalyst for desulfurization and also as a sorbent for removal of the total sulfur in liquid fuel matrices. The magnetic nanocomposite was prepared by decorating graphene oxide nanosheets with magnetite nanoparticles (MGO). For the desulfurization experiments, an oxidation-extraction procedure was developed using MGO as the catalyst and H2O2 as the oxidant. For the sulfur determination experiments, the oxidized-sulfur compounds were sorbed by magnetic solid phase extraction (MSPE) followed by ICP-OES detection. The magnetic nanocomposite showed high efficiency as did both the catalyst of sulfur compounds oxidation and the adsorbent of the oxidized sulfur compounds. Different parameters which could affect the desulfurization and determination were optimized using a multivariate analysis. The results showed that under the optimum conditions removal efficiencies of over 97% were achievable and the limit of detection of 0.15 mg kg−1 of sulfur was obtained. Finally, the spiked/recovery assays of commercial fuel samples using MSPE-ICP-OES led to recovery values in the range of 94 ± 5% to 101 ± 3%. The results obtained suggest that a powerful alternative has been developed for the desulfurization and total sulfur determination in commercial fuel samples.The authors would like to thank the Spanish Ministry of Science and Innovation (project n. CTQ2011-23968), Generalitat Valenciana (Spain) (project n. PROMETEO/2013/038) for the financial support, and Agilent Technologies Inc. for the loan of the ICP-OES spectrometers. M. Ahmadi would like to thank the Iranian Ministry of Science, Research and Technology for the travel grant