Extraction and determination of organosulfur compounds in water samples by using homogeneous liquid-liquid micro-extraction via flotation assistance-gas chromatography-flame ionization detection

A new method was developed for the preconcentration and determination of organosulfur compounds (OSCs) in water samples using homogeneous liquid-liquid microextraction via flotation assistance (HLLME-FA) and gas chromatography (GC) with flame ionization detection (FID). Toluene at microliter volume level and acetone were used as an extraction and a homogeneous solvent, respectively. In this research, a special extraction cell was designed to facilitate collection of the low-density solvent extraction. No centrifugation was required in this procedure. Using air flotation, extraction solvent was collected at the conical part of the designed cell. The effects of the different variables on the efficiency of the extraction such as kind and the volume of extraction and homogeneous solvents, ionic strength and extraction time were studied and optimized. Under the optimum conditions, linearity of the method were in the range from 0.25 to 200 µg L-1 with limit of detections (LODs) (S/N = 3) were in the range from 0.05 to 0.4 µg L-1. HLLME-FA is a fast, simple and efficient method for the determination of organic sulfur compounds in aquatic samples. KEY WORDS: Homogeneous liquid-liquid microextraction, Flotation assistance, Organosulfur compounds, Gas chromatography, Water samples Bull. Chem. Soc. Ethiop. 2014, 28(2), 195-204DOI: http://dx.doi.org/10.4314/bcse.v28i2.

Photocatalytic degradation of crystal violet by thiourea-doped TiO2 thin film fixed bed photoreactors under visible irradiation: Optimisation using central composite designs and kinetics studies by multivariate curve resolution

In this study, optimisation of the photocatalytic behaviour of crystal violet (CV) by thiourea (Tu)-codoped TiO2 thin film in fixed bed photoreactor was investigated by central composite designs (CCDs). The effective variables were pH, the concentration of CV dye, flow rate and reaction time. The results of the CCD model showed a good agreement with experimental results, with R2 = 0.9680 (p < 0.0001) and maximum degradation efficiency was obtained at the optimum conditions: dye concentration 8.5 mg/L, pH 9, flow rate 6 mL/min and reaction time 80 min. Subsequently, three absorbing chemical compounds presented in the degradation reaction were obtained by using singular value decomposition (SVD) method and evolving factor analysis (EFA). Then a multivariate curve resolution with alternating least squares (MCR-ALS) was performed to achieve the concentration and spectral profiles for each component. Finally, a hard modelling method was applied to determine the kinetic constants of distinct reactions occurred in the photocatalytic degradation process. The reaction rate constants were calculated for the first and second steps as k1 = 0.08327 (SD = ±0.0015) /min and k2 = 0.045 (SD = ±0.0006)/min, respectively.               KEY WORDS: TiO2 thin film, Photocatalytic degradation, Central composite designs, Multivariate curve resolution, Kinetic studying Bull. Chem. Soc. Ethiop. 2017, 31(3), 383-396.DOI: http://dx.doi.org/10.4314/bcse.v31i3.

Saliva Secretion and Efficacy of Helicobacter Pylori Eradication in Peptic Ulcer Patients

Objective: It has been noted that the presence of Helicobacter pylori (H. pylori)in the oral cavity may affect the outcome of eradication therapy. This condition is associated with the recurrence of gastric infection. The optimum secretion of salivapromotes oral health consequently influencing H. pylori eradication. The purpose of this study was to investigate the relation between salivary secretion and the efficacy of H. pylori eradication from the stomach.Materials and Methods: Forty five patients with gastric H. pylori infection were enrolled in this study. Diagnosis of H. pylori infection was confirmed by endoscopy,biopsy, urease test and histological examination. Salivary secretion of all participants was determined under standard condition before the beginning of antibacterial treatment. Then the patients were treated with a 14-day course anti-H. pylori regimen consisting of amoxicillin, omeprazole, metronidazole and bismuth. The efficacy of eradication therapy was evaluated 4 weeks after the end of the treatment course. Mann-Whitney U test was used to analyze the variables.Results: The median of salivary secretion among successful and unsuccessful H. pylori eradication groups was 0.48 ml/min and 0.24 ml/min, respectively (p=0.005).Conclusion: Although the type of drug regimens is challenging, the efficacy of H. pylori eradication from the stomach might be reduced by lower salivary secretion

Solid-phase extraction followed by dispersive liquid-liquid microextraction for the sensitive determination of ecstasy compounds and amphetamines in biological samples

A novel approach for the determination of ecstasy and amphetamines (3,4-methylenedioxymethylamphetamine (MDMA, Ecstasy), 3,4-methylenedioxyamphetamine (MDA), 3,4-methylenedioxyethylamphetamine (MDEA) and 3,4-methylenedioxypropylamphetamine (MDPA)) in biological samples is presented. The analytes were extracted from the matrix and transferred to a small volume of a high density, water insoluble solvent using solid-phase extraction (SPE) followed by dispersive liquid-liquid microextraction (DLLME). This combination not only resulted in a high enrichment factor, but also it could be used in complex matrices (biological samples). Some important extraction parameters, such as sample solution flow rate, sample pH, type and volume of extraction and disperser solvents as well as the salt addition, were studied and optimized. Under the optimized conditions, the calibration graphs were linear in the range of 0.5-500 µg L-1 and 1.0-500 µg L-1 with detection limits in the range of 0.1-0.3 µg L-1 and 0.2-0.7 µg L-1 in urine and plasma samples, respectively. The results showed that SPE-DLLME is a suitable method for the determination of ecstasy components and amphetamines in biological and water samples. KEY WORDS: Dispersive liquid-liquid microextraction, Solid-phase extraction, Ecstasy compounds, Amphetamines, Gas chromatography, Biological samples Bull. Chem. Soc. Ethiop. 2014, 28(3), 339-348.DOI: http://dx.doi.org/10.4314/bcse.v28i3.

Application of Ultrasound-assisted Emulsification Microextraction followed by Gas Chromatography for Determination of Oxadiazon in Water and Soil Samples

In this study, a simple and efficient ultrasound-assisted emulsification microextraction (USAEME) method combined with gas chromatography (GC) was developed for the preconcentration and determination of oxadiazon in water and soil samples. In this method, fine droplets of toluene were formedand dispersed in the sample with the help of ultrasonic waves which accelerated the formation of a fine cloudy solution without using disperser solvents. Several factors influencing the extraction efficiency, such as the nature and volume of organic solvent, extraction temperature, ionic strength and centrifugation time, were investigated and optimized. Using optimum extraction conditions a detection limit of 0.1 μg L–1 and a good linearity in a calibration range of 0.25–250 μg L–1 were achieved for the analyte in a river water sample. This proposed method was successfully applied to the analysis of oxadiazon in water and soil samples.KEYWORDS Utrasound-assisted emulsification microextraction, oxadiazon, gas chromatography, water samples, soil samples

Optimal chirality enhances long-range fluctuation-induced interactions in active fluids

Understanding how chiral active particles -- which self-propel and self-rotate -- interact with each other is crucial to uncover how chiral active matter self-organizes into dynamic structures and patterns. Long-range fluctuation-induced (FI) forces in nonequilibrium steady states of active matter systems can be considerably strong and govern structure formation in interplay with other interactions. However, the impact of chirality on FI forces is not understood to date. We study effective forces between intruders immersed in chiral active fluids with tunable chirality and find that the influence of chirality on the FI force nontrivially depends on the elongation of active particles. By increasing the ratio between self-rotation and self-propulsion, the FI force monotonically decreases for fully circular active objects, as the active bath structure gradually changes from rotating flocks and vortices to localized spinners. Contrarily, a nonmonotonic behavior is observed upon increasing the chirality of rodlike active objects: There exists an optimal chiral angle which maximizes the magnitude and range of the FI interaction. We obtain the phase diagram of transition between attractive and repulsive forces in the space of chirality, propulsion, and separation between intruders. By measuring the collision statistics between active particles and intruders at different chirality and separation, we establish a direct link between the FI force and the average collision number and demonstrate how the balance of collisions around the intruders varies with chirality and separation. Our results provide new insights into an interplay between activity, chirality, and self assembly.Comment: 8 pages, 5 figure

Introducing a new method of retinoscopy for refraction of infants and young children: The �Mirza� tele lens retinoscopy

Purpose: This study aimed to evaluate the refractive error of the uncooperative infants and children with the new method of retinoscopy called the tele-lens (�Mirza�) retinoscopy. Methods: In the �Mirza� tele-lens retinoscopy, the examiner placed the trial lenses in 1/3 distance between the tested eye person and peephole of the retinoscope (22.2 cm far from the spectacle plane). First, the optical calculations were done to find the correction factors for this new method of retinoscopy. Second, the dry standard and �Mirza� tele-lens retinoscopy were performed in 78 eyes from 39 children aged 7�12 years with good cooperation and next, the procedure was repeated using cyclopentolate drops and then the results of the two methods were compared, and at the end, the dry �Mirza� tele-lens retinoscopy was done in the 60 eyes of 31 uncooperative infants with a mean age of 21.85 ± 8.79 months for evaluating the feasibility of the �Mirza� tele-lens retinoscopy procedure. The intraclass correlation coefficient (ICC) and Bland�Altman plot for assessment of agreement between the findings of two retinoscopic methods in dry and cyclo conditions were used. Results: The comparison between the dry standard and �Mirza� tele-lens retinoscopic results with means of 1.39 ± 1.43 and1.36 ± 1.39, respectively were not statistically significant (p > 0.05). Besides, comparing the mean cycloplegic results of two methods (standard vs. �Mirza� tele-lens), the difference was not statistically significant (2.37 ± 1.44 vs. 2.41 ± 1.37) (p > 0.05). Moreover, Two-way repeated measures ANOVA revealed no significant retinoscopy method � use of drops interaction (P = 0.103) in comparing two methods of the standard and �Mirza� tele-lens retinoscopy. ICC results indicated high agreement between two methods in both dry (ICC = 0.993) and cyclo (ICC = 0.989) conditions. Conclusions: The �Mirza� tele-lens retinoscopy method can be performed with satisfactory results in infants and children who do not cooperate for the standard procedure of measuring the refractive errors. © 2020 Spanish General Council of Optometr

Comparison of quadruple and triple Furazolidone containing regimens on eradication of helicobacter pylori

Background: The effectiveness of classic standard triple therapy regimen of helicobacter pylori (H. pylori) eradication has decreased to unacceptably low levels, largely related to development of resistance to metronidazole and clarithromycin. Thus successful eradication of H. pylori infections remains challenging. Therefore alternative treatments with superior effectiveness and safety should be designed and appropriately tested in all areas depending on the native resistance patterns. Furazolidone has been used successfully in eradication regimens previously and regimens containing furazolidone may be an ideal regimen. Methods: H. pylori infected patients with proven gastric or duodenal ulcers and /or gastric or duodenal erosions at Imam Khomeini Hospital in Sari/Northern Iran, were randomly allocated into three groups: group A (OABF) with furazolidone (F) (200 mg bid.), group B (OABM-F) metronidazole (M) (500 mg bid.) for the first five days, followed by furazolidone (F) (200 mg bid.) for the second five days and group C (OAF) with furazolidone (F) (200 mg tid.). Omeprazole (O) (20 mg bid.) and amoxicillin (A) (1000 mg bid.) were given in all groups; bismuth (B) (240 mg bid.) was prescribed in groups A&B. Duration of all eradication regimens were ten days. Eight weeks after treatment, a 14C-urea breath test was performed for evaluation of H. pylori eradication. Results: A total of 372 patients were enrolled in three groups randomly (124 patients in each group); 120 (97) patients in group A (OABF), 120 (97) in group B (OABM-F) and 116 (93) in group C (OAF) completed the study. The intention-to-treat eradication rates were 83.7 (95 CI= 77.3-90.4), 79.8 (95 CI= 72.6-87), and 84.6 (95 CI= 78.2-91.1) and per-protocol eradication rates were 86.6 (95 CI= 80.5-92.8), 82.5 (95 CI= 75.6-89.4), and 90.5 (95 CI= 85.1-95.9) for groups OABF, OABM-F, and OAF, respectively. No statistical significant differences were found in case of severe drug adverse effects between the above mentioned three groups (p> 0.05). The most common side effects, namely nausea and fever, occurred in all groups, but more frequently in group C (OAF) (p< 0.05). Conclusion: In developing countries such as Iran, furazolidone-based regimens can substitute clarithromycinbased regimens for H. pylori eradication because of a very low level of resistance, low cost and high effectiveness. Considering per-protocol eradication rate of ten days OAF regimen, and the acceptable limit of ninety percent, we recommend this regimen in developing countries such as Iran to be substituted of classic standard triple therapy. In order to minimize rare serious adverse effects, one week high dose OAF regimen should be taken into consideration in other studies

Campo ambiental midiatizado: a vigilância colaborativa da Amazônia

RESUMO A manifestação do complexo processo de midiatização potencializou-se nas últimas décadas. Nesse cenário, os campos sociais se apropriaram de mecanismos discursivos do campo midiático, o que possibilitou a emergência de um espaço para a reflexão, vigilância e monitoramento de questões globais como os problemas ambientais. O objetivo desse artigo é mostrar como ocorrem imbricações entre os campos midiático e ambiental a partir da intensificação do processo de midiatização através do qual distintos cidadãos constroem o&nbsp;InfoAmazonia, banco de dados sobre as problemáticas da Amazônia. Para tanto, o trabalho se assenta metodologicamente na perspectiva da análise semiológica para identificar o contrato de leitura (VERÓN, 2004) construído pela plataforma. A investigação aponta que este enunciador se caracteriza pela legitimação de um sujeito protagonista, cogestor na vigilância colaborativa da Amazônia. Palavras-chave: midiatização; campo ambiental; contrato de leitura &nbsp; RESUMEN La manifestación del complejo proceso de mediatización se intensifica en las últimas décadas. En este escenario, los mecanismos discursivos del campo de los medios son apropiados por los campos sociales, lo que permitió el surgimento de un espacio de reflexión, vigilancia y rastreo de temas globales como los problemas ambientales. Lo objetivo deste artículo és mostrar cómo se producen solapamientos entre los campos mediático e ambiental gracias a intensificación del proceso de mediatizatión, además analizar y describir el contracto de lectura que emerge del proceso de construcción de&nbsp;InfoAmazonia, base de datos sobre los problemas de la Amazonía. Por lo tanto, el trabajo se basa metodológicamente en la perspectiva semiológica para identificar el contrato de lectura (VERÓN, 2004) de la plataforma. La investigación muestra que este enunciador se caracteriza por la legitimación de un actor protagonista, cogestor en la vigilancia de colaboración de la Amazonia. &nbsp; Palabras clave:&nbsp;mediatización; campo ambiental; contracto de lectura &nbsp; ABSTRACT The manifestation of the complex process of mediatization is leveraged in recent decades. Under this scenario, the social fields appropriated discursive mechanisms of the media field, which allowed the emergence of a space for reflection, surveillance and monitoring of global issues such as environmental problems. This research aims to show how they occur overlaps between the media and environmental fields with the intensification of mediatization, besides analyze and describe the reading agreement emerging from the construction process of InfoAmazonia, a database about the problems of the Amazon. Therefore, the work is methodologically based on semiological perspective to identify the platform reading contract (VERÓN, 2004). Research shows that this annunciator is characterized by the legitimation of a subject protagonist, who helps oversee the collaborative surveillance of the Amazon. &nbsp; Keywords:&nbsp;mediatization; environmental field; reading agreement