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Non-terminal myelocystoceles are commonly found in the cervical or thoracic spinal region. Their sac can rarely be associated with tumor. A rare case of an infant with a lumbosacral non-terminal myelocystocele and accompanying mature teratoma is reported in whom the tumor was attached to the placode not as a part of the sac.

Hepatocellular carcinoma (HCC) is one of the most prevalent cancers worldwide, which has a high mortality rate and poor treatment outcomes with yet unknown molecular basis. It seems that gene expression plays a pivotal role in the pathogenesis of the disease. Circular RNAs (circRNAs) can interact with microRNAs (miRNAs) to regulate gene expression in various malignancies by acting as competitive endogenous RNAs (ceRNAs). However, the potential pathogenesis roles of the ceRNA network among circRNA/miRNA/mRNA in HCC are unclear. In this study, first, the HCC circRNA expression data were obtained from three Gene Expression Omnibus microarray datasets (GSE164803, GSE94508, GSE97332), and the differentially expressed circRNAs (DECs) were identified using R limma package. Also, the liver hepatocellular carcinoma (LIHC) miRNA and mRNA sequence data were retrieved from TCGA, and differentially expressed miRNAs (DEMIs) and mRNAs (DEGs) were determined using the R DESeq2 package. Second, CSCD website was used to uncover the binding sites of miRNAs on DECs. The DECs' potential target miRNAs were revealed by conducting an intersection between predicted miRNAs from CSCD and downregulated DEMIs. Third, some related genes were uncovered by intersecting targeted genes predicted by miRWalk and targetscan online tools with upregulated DEGs. The ceRNA network was then built using the Cytoscape software. The functional enrichment and the overall survival time of these potential targeted genes were analyzed, and a PPI network was constructed in the STRING database. Network visualization was performed by Cytoscape, and ten hub genes were detected using the CytoHubba plugin tool. Four DECs (hsa_circ_0000520, hsa_circ_0008616, hsa_circ_0070934, hsa_circ_0004315) were obtained and six miRNAs (hsa-miR-542-5p, hsa-miR-326, hsa-miR-511-5p, hsa-miR-195-5p, hsa-miR-214-3p, and hsa-miR-424-5p) which are regulated by the above DECs were identified. Then 543 overlapped genes regulated by six miRNAs mentioned above were predicted. Functional enrichment analysis showed that these genes are mostly associated with cancer regulation functions. Ten hub genes (TTK،AURKB, KIF20A، KIF23، CEP55، CDC6، DTL، NCAPG، CENPF، PLK4) have been screened from the PPI network of the 204 survival-related genes. KIF20A, NCAPG, TTK, PLK4, and CDC6 were selected for the highest significant p-values. In the end, a circRNA-miRNA-mRNA regulatory axis was established for five final selected hub genes. This study implies the potential pathogenesis of the obtained network and proposes that the two DECs (has_circ_0070934 and has_circ_0004315) may be important prognostic factor for HCC.

Recently, the cytotoxic properties of galvanically coupled Ti-Mg particles have been shown in different cells. This cytotoxic effect has been attributed mainly to Mg due to its tendency to undergo activation when coupled with Ti, forming a galvanic cell consisting of an anode (Mg) and a cathode (Ti). However, the role of the Ti cathode has been ignored in explaining the cytotoxic effect of Ti-Mg particles due to its high resistance to corrosion. In this work, the role of titanium (Ti) in the cytotoxic mechanism of galvanically coupled Ti-Mg particles was examined. A model galvanic cell (MGC) was prepared to simulate the Mg-Ti particles. The electrochemical reactivity of the Ti sample and the pH change in it due to galvanic coupling with Mg were investigated using scanning electrochemical microscopy (SECM). It was observed that the Ti surface changed from passive to electrochemically active when coupled with Mg. Furthermore, after only 15 min of galvanic coupling with Mg, the pH in the electrolyte volume adjacent to the Ti surface increased to an alkaline pH value. The effects of the galvanic coupling of Ti and Mg, as well as those of the alkaline pH environment, on the viability of Hs27 fibroblast cells were investigated. It was shown that the viability of Hs27 cells significantly diminished when Mg and Ti were galvanically coupled compared to when the two metals were electrically disconnected. Thus, although Ti usually exhibited high corrosion resistance when exposed to physiological environments, an electrochemically active surface was observed when galvanically coupled with Mg, and this surface may participate in electron transfer reactions with chemical species in the neighboring environment; this participation resulted in the increased pH values above its surface and enhanced generation of reactive oxygen species. These features contributed to the development of cytotoxic effects by galvanically coupled Ti-Mg particles.

© 2018 Elsevier B.V. Bismuth-oxychloride-multiwalled carbon nanotube composite material was applied as surface modifier of glassy carbon electrode (BiOCl-MWCNT/GCE) for rapid and reliable trace level determination of Zn(II) in selected foodstuffs. The method development encompasses the optimization of electrode preparation including the transmission electron microscopic study of the modifier suspension, selection of the supporting electrolyte pH, the adjustment of the operation parameters of the SW-ASV measurements and the investigation of matrix effects. By the BiOCl-MWCNT/GCE recorded calibration curve showed an excellent linearity towards Zn reoxidation peak intensity in the concentration range from 2.50 to 80.0 μg L−1 with the calculated LOD of 0.75 μg L−1 which was associated with 120 s accumulation time and accumulation potential −1.40 V vs SCE in acetate buffer pH 4.5. A satisfactory repeatability expressed as relative standard deviation of 4.8% was obtained in the case of 10.0 μg L−1 Zn(II) in model solution. The Zn(II) reoxidation signal from BiOCl-MWCNT/GCE received by the optimized SW-ASV method was compared with those recorded with bare, classical bismuth-film, multiwalled carbon nanotubes and by in situ made advanced bismuth-film-MWCNTs working electrodes. The applicability of the proposed BiOCl-MWCNT/GCE based method was corroborated via measuring the target analyte in two nutrition related real samples: in a dietary supplement and in a brewer's yeast sample. Comparative flame atomic absorption spectrometric measurements verified the obtained results in the case of yeast sample.

An electroanalytical study for possible simultaneous detection of three naturally occurring isomers of vitamin E (α, γ, and δ-tocopherol) was performed. This research includes several optimization steps, such as selection of electrode material, composition of working medium, selection of electrochemical technique, and parameters of square-wave voltammetry (SWV), to reach a well-defined recognition of peaks. A glassy carbon electrode, 99.9% acetonitrile containing 0.1 mol L−1 lithium perchlorate, SWV at the potential step of 1 mV, potential amplitude of 25 mV, and frequency of 25 Hz were decided as the most suitable working conditions. Nevertheless, the corresponding anodic peaks were not sufficiently separated due to their overlapping. Thus, four standard evaluation methods (polynomial or linear baseline, zero base, and deconvolution) were compared, and the last-mentioned method was chosen as optimum. Similar linear ranges from 3.0 × 10−6 to 1.0 × 10−5 mol L−1 were obtained for α, γ, and δ-tocopherol, characterized by determination coefficient of 0.998, 0.985, and 0.994, quantification limits of 11.28, 2.70, and 3.67 × 10−6 mol L−1 and detection limits of 3.72, 0.89, and 1.21 × 10−6 mol L−1, respectively. A recovery from 72.0 to 128.5% for different concetration ratios of tocopherols has been achieved. This recovery range is in the accordance with values reported for liquid chromatography. Byla provedena elektroanalytická studie pro možnou simultální detekci tří přirozeně se vyskytujících izomerů vitaminu E (α, γ a δ-tokoferol). Tento výzkum zahrnuje několik optimalizačních kroků, jako je výběr materiálu elektrody, složení pracovního média, výběr elektrochemické techniky a parametry square-wave voltametrie (SWV), aby se dosáhlo dobře definovaného rozpoznávání píků. Jako nejvhodnější pracovní podmínky byla zvolena elektroda ze skelného uhlíku, 99,9% acetonitril obsahující 0,1 mol L -1 chloristan lithný, SWV v potenciálním kroku 1 mV, potenciální amplituda 25 mV a frekvence 25 Hz. Nicméně odpovídající anodické píky nebyly dostatečně odděleny kvůli jejich překrývání. Byly tedy porovnány čtyři standardní metody hodnocení (polynomiální nebo lineární základní linie, nulová báze a dekonvoluce) a jako optimální byla vybrána posledně uvedená metoda. Podobné lineární rozsahy od 3,0 × 10−6 do 1,0 × 10−5 mol L − 1 byly získány pro α, γ a δ-tokoferol, charakterizované koeficientem stanovení 0,998, 0,985 a 0,994, limity kvantifikace 11,28, 2,70, a 3,67 × 10−6 mol L − 1 a detekční limity 3,72, 0,89, respektive 1,21 × 10−6 mol L − 1. Bylo dosaženo návratnosti od 72,0 do 128,5% pro různé koncentrační poměry tokoferolů. Toto rozmezí návratnosti je v souladu s hodnotami uváděnými pro kapalinovou chromatografii.

In the original publication [...]

At the cellular level, DNA repair mechanisms are crucial in maintaining both genomic integrity and stability. DNA damage appears to be a central culprit in tumor onset and progression. Cyclin-dependent kinases (CDKs) and their regulatory partners coordinate the cell cycle progression. Aberrant CDK activity has been linked to a variety of cancers through deregulation of cell-cycle control. Besides DNA damaging agents and chromosome instability (CIN), disruptions in the levels of cell cycle regulators including cyclin-dependent kinase inhibitors (CDKIs) would result in unscheduled proliferation and cell division. The INK4 and Cip/Kip (CDK interacting protein/kinase inhibitor protein) family of CDKI proteins are involved in cell cycle regulation, transcription regulation, apoptosis, and cell migration. A thorough understanding of how these CDKIs regulate the DNA damage response through multiple signaling pathways may provide an opportunity to design efficient treatment strategies to inhibit carcinogenesis.

In this article, construction of amperometric sensor(s) based on screen-printed carbon electrodes covered by thin layers of two types of carbon nanomaterials serving as amplifiers, and containing [Cu(bipy)2Cl]Cl∙5H2O complex is reported. Their performance and biomimetic activity towards two selected neurotransmitters (dopamine and serotonin) was studied mainly using flow injection analysis (FIA). The important parameters of FIA such as working potential, flow rate, and pH were optimized. The mechanism of the catalytic activity is explained and experimentally confirmed. It reveals that presence of hydrogen peroxide plays a crucial role which leads to answer the title question: can presented complex really be considered as a tyrosinase biomimetic catalyst or only as a redox mediator? V tomto článku je popsána konstrukce amperometrických senzorů založených na sítotiskových uhlíkových elektrodách pokrytých tenkými vrstvami dvou typů uhlíkových nanomateriálů sloužících jako zesilovače a obsahujících komplex [Cu (bipy) 2Cl] Cl ∙ 5H2O. Jejich výkon a biomimetická aktivita vůči dvěma vybraným neurotransmiterům (dopaminu a serotoninu) byla studována hlavně pomocí průtokové injekční analýzy (FIA). Byly optimalizovány důležité parametry FIA, jako je pracovní potenciál, průtok a pH. Mechanismus katalytické aktivity je vysvětlen a experimentálně potvrzen. Ukazálo se, že přítomnost peroxidu vodíku hraje zásadní roli, která vede k zodpovězení otázky v titulku: lze skutečně prezentovaný komplex považovat za biomimetický katalyzátor tyrosinázy nebo pouze za redoxní mediátor?

A comparative study was carried out using magnetic nanoparticles (MNPs) for the fabrication of non-enzymatic sensors for the continuous and rapid detection and monitoring of H2O2. Various MNPs, differing in terms of their synthesis procedure and modification, were synthesized and characterized by different techniques. The electrochemical catalytic activity of the synthesized MNPs toward the reduction in H2O2 was investigated by cyclic voltammetry. The naked MNPs showed the highest catalytic activity among all the synthesized MNPs. The biosensor based on the naked MNPs was then applied in the determination of H2O2 using chronoamperometry. The parameters such as the applied cathodic potential and the amount of MNPs on the developed biosensor were optimized. Moreover, the analytical figures of merit, including reproducibility (RSD = 6.14%), sensitivity (m = 0.0676 &micro, A &micro, M&minus, 1), limit of detection (LOD) = 27.02 &micro, mol L&minus, 1, and limit of quantification (LOQ) = 89.26 &micro, 1 of the developed biosensor indicate satisfactory analysis. Finally, MNPs were successfully utilized for the determination of H2O2 in milk.

The electrochemical redox behavior of three trinuclear Ni(II) complexes [Ni3(abb)3(H2O)3(µ-ttc)](ClO4)3 (1), [Ni3(tebb)3(H2O)3(µ-ttc)](ClO4)3·H2O (2), and [Ni3(pmdien)3(µ-ttc)](ClO4)3 (3), where abb = 1-(1H-benzimidazol-2-yl)-N-(1H-benzimidazol-2-ylmethyl)methan-amine, ttcH3 = trithiocyanuric acid, tebb = 2-[2-[2-(1H-benzimidazol-2-yl)ethylsulfanyl]ethyl]-1H-benzimidazole, and pmdien = N,N,N′,N″,N″-pentamethyldiethylenetriamine is reported. Cyclic voltammetry (CV) was applied for the study of the electrochemical behavior of these compounds. The results confirmed the presence of ttc and nickel in oxidation state +2 in the synthesized complexes. Moreover, the antibacterial properties and cytotoxic activity of complex 3 was investigated. All the complexes show antibacterial activity against Staphylococcus aureus and Escherichia coli to different extents. The cytotoxic activity of complex 3 and ttcNa3 were studied on G-361, HOS, K-562, and MCF7 cancer cell lines. It was found out that complex 3 possesses the cytotoxic activity against the tested cell lines, whereas ttcNa3 did not show any cytotoxic activity.

The neutralization of milk whey after the electrodialysis (ED) is usually carried out by direct addition of NaOH or KOH solution. However, the addition of these solutions results in an increase in total solids and ash content of the whey sample. In this work, electrodialysis with the bipolar membrane (EDBM) was examined to neutralize the desalinated whey after ED. First, ED was used to desalinate the nanofiltrated whey (NFW). Three milk whey samples differing in demineralization rate in ED were subjected to the EDBM. Two configurations of EDBM were applied to increase the pH of the milk whey samples. When the samples which had been demineralized first with conventional ED, were submitted in EDBM the pH increased to the desired values. However, the pH of NFW sample only increased to the values less than 6. The changes in pH, total solids, ash content, and minerals profile of various samples after EDBM were investigated. It was figured out that the increase in pH was not accompanied by any significant increase in total solids and ash content of the samples. The mechanisms of ion transport during EDBM for either cations or anions were investigated. The cations were mainly transported by diffusion in developed configurations of EDBM while anions were transported either with diffusion or migration depending on the type of milk whey sample. With increasing the demineralization rate of the whey in ED the diffusional transport of species in EDBM reduces due to the decrease in ion content of the whey. Two configurations of EDBM were compared in terms of fouling on the BM surface, electrodialysis capacity, and energy consumption.

Nanozymes (NZs) are nanomaterials that mimic enzyme-like catalytic activity. They have attracted substantial attention due to their inherent physicochemical properties for use as promising alternatives to natural enzymes (NEs) in a variety of research fields. Particularly, in biosensing and bioassays, NZs have opened a new horizon to eliminate the intrinsic limitations of NEs, including their denaturation at extreme pH values and temperatures, poor reusability and recyclability, and high production costs. Moreover, the catalytic activity of NZs can be modulated in the preparation step by following an appropriate synthesis strategy. This review aims to gain insight into the potential substitution of NEs by NZs in biosensing and bioassays while considering both the pros and cons.

Four types of bipolar membranes (BMs) with different structural properties were subjected to various electrochemical methods including current-voltage curve, (CVC) chronopotentiometry, and impedance spectroscopy, to be characterized in terms of selectivity, energy consumption and the water splitting capability. Then the bipolar membranes were used in two kinds of electrodialysis modules, lab scale and pilot unit, for acid and base production. The produced acid and base were analyzed to calculate the product purity, energy consumption and current efficiency of each bipolar membrane electrodialysis (BMED). The results obtained with electrodialysis coincided with those of electrochemical methods, indicating that even though the electrochemical methods are rather fast and easy to perform, they are quite reliable. Furthermore the impact of structural properties of each BM on its efficiency was investigated. It was figured out that the reinforcing of a heterogeneous BM improves its properties while the increase in the ion exchange resin content on each layer of the heterogeneous BMs was not resulted in any significant enhancement of BM properties. The investigated homogenous membrane showed higher selectivity and less energy consumption compared to the heterogeneous BMs.

The possibility of alkali recovery from a high alkaline solution as a model for mercerization wastewater by electrodialysis (ED) was examined. ED with feed and bleed configuration was used in which the diluate chamber conductivity was kept at a given value by dosing an alkaline solution. The effect of the diluate chamber’s concentration on the efficiency of the ED was investigated. It was found out that the efficiency of the ED was just slightly affected by changing the concentration of the solution in diluate chamber. The calculated values of current efficiency in ED process were about 60%. Since the ion exchange membranes, particularly the anion exchange ones are suspected to be damaged in high alkaline media, their properties including electrochemical resistivity, apparent permselectivity, FT-IR spectrum, and the current-voltage characteristics were investigated. The results confirmed that the membranes possess a promising chemical stability since their properties were not affected by the alkaline media. Hence, the obtained results show that the electrodialysis is an appropriate method for alkaline recovery.

Electrodialysis (ED) is frequently used in the desalination of whey. However, the fouling onto the membrane surface decreases the electrodialysis efficiency. Pulsed Electrodialysis Reversal (PER), in which short pulses of reverse polarity are applied, is expected to decrease the fouling onto membrane surface during ED. Three (PER) regimes were applied in the desalination of acid whey (pH ≤ 5) to study their effects on the membrane fouling and the ED efficiency. The PER regimes were compared to the conventional ED as the control. For each regime, two consecutive runs were performed without any cleaning step in-between to intensify the fouling. After the second run, the membranes were subjected to the Scanning electron microscope (SEM) imaging and contact angle measurement to investigate the fouling on the membrane surface in different regimes. The ED parameters in the case of conventional ED were almost the same in the first and the second runs. However, the parameters related to the ED efficiency including ED capacity, ash transfer, and ED time, were deteriorated when the PER regimes were applied. The contact angle values indicated that the fouling on the diluate side of anion exchange membranes was more intensified in conventional ED compared to the PER regimes. The SEM images also showed that the fouling on the diluate side of both cation and anion exchange membranes under PER regimes was reduced in respect to the conventional ED. However, the back transfer to the diluate compartment when the reverse pulse was applied is dominant and lowers the ED efficiency slightly when the PER is applied.

Perfluorinated sulfonic acid (PFSA) polymer membranes are widely used as ion-conducting electrolytes in energy-conversion devices. The development of novel hybrid materials containing inorganic dopants offers the route towards optimization of the performance of the PFSA membranes. In this work, the effect of ultrasonic (US) treatment of the PFSA solutions in the presence of SiO2 nanoparticles on the characteristics of the cast hybrid Nafion+SiO2 membranes was studied for the first time. Upon ultrasonication of polymer solutions, the length of macromolecules is reduced, and the number of sulfo groups decreases. When polymer solutions are ultrasonicated in the presence of SiO2, they experience additional crosslinking due to the interaction of SiO2 with sulfo groups of the PFSA polymer. As a result, up to 20% of -SO3H groups appears to be excluded from the ion-exchange process, and the temperature corresponding to destabilization of ionic clusters is reduced. When a hydrophilic dopant is incorporated within pores, the overall water uptake of the hybrid membranes increases, and their proton conductivity is improved. Maximum conductivity (78.6 mS/cm) at 40°С in the contact with water is observed for the Nafion+1 wt% SiO2 membrane cast from polymer solutions upon the ultrasonication for 10 min. The membranes preserve their high conductivity at low relative humidity (4.1 mS/cm at 30°С, 30% RH), and this value is 1.7 times higher than that of the pristine Nafion membrane. Hydrogen permeability of the hybrid Nafion+SiO2 membranes appears to be lower than that of the Nafion membranes by 15%. Hence, US-assisted dispersion of dopant nanoparticles in the PFSA solutions allows preparation of hybrid membranes with improved transport characteristics.

A simple and reproducible electroanalytical sensor using antimony trioxide modified-carbon paste electrode (Sb2O3–CPE) as sensing element was employed for the first time for simultaneous determination of glutathione (GSH) and glutathione disulphide (GSSG). The electrochemical response of Sb2O3–CPE was characterized by cyclic voltammetry and square-wave voltammetry. Scanning electron microscopy (SEM), scanning electrochemical microscopy (SECM) and Raman mapping were used to characterize the morphology and surface modification. A significant enhancement in the peak current response of GSH and GSSG accompanied with a good separation of the peaks were obtained at the modified electrode compared to the bare CPE. GSH and GSSG exhibited well-defined oxidation peaks at +1.08 V and +1.36 V (vs. Ag/AgCl, 3 mol/L) in Britton-Robinson buffer at pH 6.0. Parameters such as used supporting electrolyte and its pH value, amplitude and frequency were optimized for square-wave voltammetric determination. Under optimal conditions, voltammetric responses were linear in the concentration range of 2–200 μmol/L for GSH and GSSG. The limits of detection were 0.34 μmol/L and 0.10 μmol/L for GSH and GSSG, respectively. Moreover, the proposed sensor also showed good reproducibility, stability and selectivity. Finally, the proposed sensor was applied for the simultaneous determination of GSH and GSSG in urine samples with satisfactory results.

Collection, conveyance and discharge of farm drainage water using open channel network is an important task in an agricultural area. Design of an open channel network is based on the total length and conveying capacity of the channel, topography of the area and specific local conditions. Therefore, designing proper channel paths is an effective factor in the optimum network design. In this study, three optimization models have been considered: the modified minimal spanning tree, the shortest path and the out-of-kilter algorithms. The modified minimal spanning tree model for optimization of a farm drainage channel network (FDCN) has been improved to a better algorithm. The algorithm has been applied to optimize a part of the Sansad irrigation network project. Then, the FDCN system of the Jiroft and Roodbar plain was mathematically modeled considering regional constraints and optimized using the presented models. Results showed that the improved modified minimal spanning tree model, gives the shortest channel network length compared to the other three models.

Two multiwalled carbon nanotubes-based composites modified with bismuth and bismuth-oxychloride particles were synthesized and attached to the glassy carbon electrode substrate. The resultant configurations, Bi/MWCNT-GCE and BiOCl/MWNT-GCE, were then characterized with respect to their physicochemical properties and electroanalytical performance in combination with square-wave anodic stripping voltammetry (SWASV). Further, some key experimental conditions and instrumental parameters were optimized; namely: the supporting electrolyte composition, accumulation potential and time, together with the parameters of the SWV-ramp. The respective method with both electrode configurations has then been examined for the trace level determination of Pb(2+) and Cd(2+) ions and the results compared to those obtained with classical bismuth-film modified GCE. The different intensities of analytical signals obtained at the three electrodes for Pb(2+) and Cd(2+) vs. the saturated calomel reference electrode had indicated that the nature of the modifiers and the choice of the supporting electrolyte influenced significantly the corresponding stripping signals. The most promising procedure involved the BiOCl/MWCNT-GCE and the acetate buffer (pH 4.0) offering limits of determination of 4.0 μg L(-1) Cd(2+) and 1.9 μg L(-1) Pb(2+) when accumulating for 120 s at a potential of -1.20 V vs. ref. The BiOCl/MWCNT electrode was tested for the determination of target ions in the pore water of a selected sediment sample and the results agreed well with those obtained by graphite furnace atomic absorption spectrometry.

Relative permeability and capillary pressure are the primary flow parameters required to model multiphase flow in porous media. Frequently, these properties are estimated on the basis of unsteady state laboratory displacement experiments. Interpretation of the flood process to obtain relative permeability data is performed by application of frontal advance theory. Application of frontal advance theory has a number of limitations. Therefore, the flow rate of injection water to the core must be sufficiently large that capillary effects, particularly at the outlet end of the core, which is called capillary end-effect, are negligible. In some cases, capillary end effects in core flood experiments can significantly influence relative permeabilities and final saturation levels. An automatic numerical method with a parameter estimation technique is proposed for simultaneous determination of relative permeabilities and capillary pressure from the results of a two-phase flow modeling, including capillary end-effec...

The Khesht field was discovered in 1992 and located some 25 km from Kazeron town. One reservoir (Asmari) was found to be hydrocarbon bearing in the field. The discovery well also tested to a production rate of 9,450 barrels of oil per day. Artificial lift method selection is very important. An improper selection of artificial lift can reduce production and increase the operating cost substantially. Once a decision has been made on the type to install on a well, it can be rarely altered whether or not the method selected was and still is the optimal for the existing conditions. The authors present the screening criteria on the different artificial lift techniques and discuss among them to choices suitable technique to apply in the field. A comparison among natural flow, electrical submersible pump, and gas lift will present for the Khesht field only to help in reaching the conclusions to verify the best solution to produce the wells. In this study the production rates are the only factor in determining the...

A nanocomposite based on multiwalled carbon nanotubes (MWCNT) modified with antimony nanoparticles (SbNPs) was synthesized chemically and has been applied to construct an electrode using carbon paste as substrate (SbNP-MWCNT). The developed electrode was applied for the determination of trace heavy metals Pb2+ and Cd2+ by square-wave adsorptive stripping voltammetry. The results were compared with those obtained by related electrode configurations such as Sb-film carbon paste electrode (SbF) and Sb-microsphere-multiwalled carbon nanotube composite carbon paste electrode (Sbmicrosphere-MWCNT) in model solutions. The analytical signals for Pb2+ and Cd2+ decreased in the order ISb-nanoparticle > ISb-film > ISb-microsphere, indicating that the size of the Sb particles on the coating layer influenced the oxidation current signals of Pb and Cd. The detection limits of the analytes were 0.77 μg L−1 and 0.65 μg L−1 for Cd2+ and Pb2+, respectively. The designed electrode was tested for the determination of target ions in wheat flour certified reference material, and the results compared well with those obtained by inductively coupled plasma time-of-flight mass spectrometry, showing satisfactory performance of the composite electrode.

Multiwalled carbon nanotube modified edge plane pyrolytic graphite electrode (MWCNT/EPPGE) was developed and implemented for the determination of antiretroviral drug Abacavir using differential pulse adsorptive stripping voltammetry (DP AdSV). Cyclic voltammogram showed two oxidation peaks located at +0.91 V and +1.10 V on (MWCNT/EPPGE). Dependency of peak potential and peak current on pH was investigated as details. The oxidation potentials affected by the pH indicating protons are involved in the electrochemical oxidation of Abacavir. Mass transport to the electrode surface was found as a combination of diffusion and adsorption which was concluded by studying the potential scan rate dependency of both peak currents. The oxidation mechanism was proposed using the obtained data and discussed. A large enhancement in both of the peak currents was observed with applying an accumulation step presenting the effect of adsorption. Peak currents showed a linear relation upon the Abacavir concentration within a range of 1 × 10−7–2 × 10−5 M with (r = 0.999) for both peak responses. The method was fully validated related with selectivity, sensitivity, precision and accuracy studies. Abacavir was also determined with the proposed method in its pharmaceutical dosage forms and human serum samples. No interferences from the excipients of the dosage form or endogenous substances from biological material were found.