Derivative spectrophotometric determination of trace lead in alloys and biological samples after separation and preconcentration with the ion pair of 2-(5-bromo-2-pyridylazo)-5-diethylaminophenol and ammonium tetraphenylborate on microcrystalline

Lead is quantitatively retained on 2-(5-bromo-2-pyridylazo)-5-diethylaminophenol-ammonium tetraphenylborate with microcrystalline naphthalene or by a column method in the pH range 4.0–6.0 from a large volume of aqueous solutions of various samples. After filtration, the solid mass consisting of the lead complex and naphthalene was dissolved with 5 mL of dimethylformamide and the metal was determined by third derivative spectrophotometry. Lead complex can alternatively be quantitatively adsorbed on ammonium tetraphenylborate-naphthalene adsorbent packed in a column and determined similarly. About 0.2 mg of lead can be concentrated in a column from 300 mL of aqueous sample, where its concentration is as low as 0.7 ng/mL. The interference of a large number of anions and cations has been studied and the optimized conditions developed have been utilized for the trace determination of lead in various samples. KEY WORDS: Trace lead determination, Derivative spectrophotometry, 2-(5-Bromo-2-pyridylazo)-5-diethylamminophenol, Ammonium tetraphenylborate, Naphthalene  Bull. Chem. Soc. Ethiop. 2003, 17(2), 129-138.

Flame Atomic Absorption Spectrometric Determination of Trace Lead after Solid-Liquid Extraction and Preconcentration Using 1-(2-Pyridylazo)-2-naphthol

An atomic absorption spectrometric method for the determination of trace amounts of lead after adsorption of its 1-(2-pyridylazo)-2-naphthol (PAN) complex on microcrystalline naphthalene has been developed. This complex was adsorbed on microcrystalline naphthalene in the pH range 8.4–11.5 from large volumes of aqueous solutions of various alloys and biological samples. After filtration, the solid mass consisting of the complex and naphthalene was dissolved with 5 ml of dimethylformamide and the metal was determined by flame atomic absorption spectrometry. Lead was alternatively quantitatively adsorbed on [1-(2-pyridylazo)-2-naphthol]- naphthalene adsorbent packed in a column and determined similarly. In this case, 0.5 µg of lead was concentrated in a column from 500 ml of aqueous sample, where its concentration was as low as 1.0 ng ml–1. Eight replicate determinations of 4.0 µg ml–1 of lead gave a mean absorbance of 0.200 with a relative standard deviation of 1.5 %. The sensitivity for 1 % absorption was 88 ng ml–1. The interference of a large number of anions and cations was studied and the optimized conditions developed were utilized for the trace determination of lead in various standard samples

Comparison of Ardabil people's utilization of national media and satellite networks in receiving news

Virtual social networks nowadays play a very important role in getting and receiving daily news. Therefore, it is necessary to know the extent and reasons for users to use this tool and compare it with other media. Therefore, it is essential to know the extent and reasons for users to utilize this tool and compare it with other media. This study aimed to investigate the comparison of the use of Ardebil people from social networks and other media in receiving the news. In this descriptive-inferential study 400 Ardabil people were randomly selected. The validity and reliability of the questionnaire developed by the researcher were obtained and completed by the participants. The data were then analyzed using SPSS software. Research findings show that participants prefer to gain news from social networks to other media and most of them think that using social media has been able to reduce the utilization of other media. The findings show that the use of social media in news coverage has somewhat reduced the amount of time spent watching television and satellite. The reasons for this media shift in news acquisition include the social networking content attractiveness in the indicators of accuracy and transparency, the speed of dissemination, the neutrality of news, the latest visual reports, the visual and auditory attractions, the attention to quality of programs, attention to Respondents cited low censorship, addressing issues of interest to audiences, using news images, and using expert view of other media as sources of news. The participants also believed that social networks have a low level of censorship and news silence. Since the national media should be the most important medium in getting the news to a community, as an emerging media social networks have been able to take deep root in human life. These networks have positive features, but on the other hand, they have problems that need special attention.

Fourth Derivative Spectrophotometric Determination of Trace Silver after Preconcentration with the Ion Pair of 2-Nitroso-1-naphthol-4-sulfonic Acid and Tetradecyldimethylbenzylammonium Chloride by Microcrystalline Naphthalene or Column Method

Silver is quantitatively retained as 2-nitroso-1-naphthol-4-sulfonic acid (nitroso-S) and tetradecyldimethylbenzylammonium (TDBA) ion associated complex on microcrystalline naphthalene in the pH range 9.5-11.0 from large volumes of its aqueous Solutions of various alloys and biological samples. After filtration, the solid mass consisting of metal complex and microcrystalline naphthalene was dissolved in dimethylformamide (DMF) and the metal determined by fourth derivative spectrophotometry. Silver can alternatively be quantitatively adsorbed on (nitroso-S)-(TDBA)-naphthalene adsorbent packed in a column at a flow rate of 1-2 ml min-1 and determined similarly. The calibration curve is linear over the concentration range 0.2-30 pg ml-1 of silver in dimethylformamide solution by measuring the distance d4A/cU4 between (606 nm) and (562 nm) with a correlation coefficient of 0.9994 and relative standard deviation of ±1.1%. The analytical sensitivity is calculated to be 0.198(d4A/dA4)/ pg ml-1 from the slope of the calibration curve. The detection limit is 0.15 pg ml-1 for silver at the minimum instrumental settings (signal to noise ratio = 2). Various parameters such as the effect of pH, volume of aqueous phase and interference of a large number of metal ions on the determination of silver have been studied in detail to optimize the conditions for its determination in various complex samples

المشعرات الحيوية لمخزون المبيض

تتمثل الوظيفة الأساسية للمبيض الأنثوي في إنتاج بويضة ناضجة وقابلة للحياة قادرة على الإخصاب وتطور الجنين اللاحق وتعشيشه. عند الولادة يحتوي المبيض على عدد محدود من البويضات المتاحة لتكوين الجريبات. هذا العدد المحدود من البويضات المتاحة يسمى "مخزون المبيض". إن تحديد مخزون المبيض مهم في تقييم وعلاج العقم. مع تقدم عمر المبيض سينخفض مخزون المبيض. يؤثر العقم على ما يقرب من ٪15 - ٪20 من الأزواج في سن الإنجاب.  المقايسة الحيوية الأكثر شيوعاً لتقييم مخزون المبيض هو قياس الهرمون المنبه للجريبات في اليوم الثالث للدورة. تعتبر المقايسات الحيوية للهرمون المضاد لمولر و الانهيبين-ب من المعايرات التي تكتسب شعبية حيث أنها تزود تحديدا مباشر لحالة المبيض بينما يعتبر عيار الهرمون الحاث للجريبات في اليوم الثالث قياسا غير مباشر.  تفحص هذه المراجعة الأدوات الفيزيائية والمؤشرات الحيوية للهرمونات المستخدمة لتقييم مخزون المبيض

Petrography and Mineral Chemistry of Tourmaline in Molla Taleb Ganitoid, Northeast of Aligudarz (Lorestan Province)

Molla Taleb pegmatites (northeast of Aligudarz) are located in the western part of the metamorphic-igneous Sanandaj-Sirjan Zone (SSZ). Slates and schists along with siliceous veins and veinlet and black Hornfels, as well as metamorphic sandstones are among the oldest deposits of this area. The most important geological event in this area is the development and intrusion of granitoid masses into schists of the Molla Taleb area during the Middle Jurassic. The rocks of the study area are in the range of gabbro, diorite, granodiorite, and granite. Granites are in the range of type-I granites. Most specimens are calc-alkaline and mainly contain peraluminous. Microprobe electron analysis of tourmalines present in pegmatites, tourmaline- aplite-pegmatite veins, nodular tourmalines, and quartz-tourmaline veins shows that all tourmalines are in the Schorl region and the range of alkaline tourmalines. These tourmalines with FeO / FeO + MgO ratios between 0.6 and 0.8 are in the range of magmatic-hydrothermal tourmalines and more than 0.8 in the magmatic range. Therefore, the studied tourmalines are dependent on granite environments and are formed by a hydrothermal fluid of magmatic origin

Petrography and Mineral Chemistry of Tourmaline in Molla Taleb Ganitoid, Northeast of Aligudarz (Lorestan Province)

Molla Taleb pegmatites (northeast of Aligudarz) are located in the western part of the metamorphic-igneous Sanandaj-Sirjan Zone (SSZ). Slates and schists along with siliceous veins and veinlet and black Hornfels, as well as metamorphic sandstones are among the oldest deposits of this area. The most important geological event in this area is the development and intrusion of granitoid masses into schists of the Molla Taleb area during the Middle Jurassic. The rocks of the study area are in the range of gabbro, diorite, granodiorite, and granite. Granites are in the range of type-I granites. Most specimens are calc-alkaline and mainly contain peraluminous. Microprobe electron analysis of tourmalines present in pegmatites, tourmaline- aplite-pegmatite veins, nodular tourmalines, and quartz-tourmaline veins shows that all tourmalines are in the Schorl region and the range of alkaline tourmalines. These tourmalines with FeO / FeO + MgO ratios between 0.6 and 0.8 are in the range of magmatic-hydrothermal tourmalines and more than 0.8 in the magmatic range. Therefore, the studied tourmalines are dependent on granite environments and are formed by a hydrothermal fluid of magmatic origin