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هدف البحث الحالي الى معرفة العلاقة بين قوة تشتيت البدائل في أسئلة الاختيار من متعدد في مادة الفيزياء وصدق الاختبار وثباته وتأتي أهمية هذا البحث وسط اغفال متزايد من الكثيرين للضوابط الفنية والمنهجية في اعداد وتقنين الاختبارات التحصيلية وعدم التقيد بضرورة اجراء المعالجات التحليلية لفقرات اختبارات الاختيار من متعدد. شمل البحث الحالي (105) طالباً من طلاب الصف الاول المتوسط في ثانوية المتميزين للعام الدراسي 2017-2018 ،وتمثلت أدوات البحث في اختبار الاختيار من متعدد الذي بلغ عدد فقراته (18) فقرة، وقام الباحث بتطبيق البحث الحالي على عينة البحث خلال الكورس الاول والثاني للعام الدراسي 2017-2018وعلى النحو الاتي: استخراج معاملات الصعوبة وتمييز الفقرات ، وقوة تشتيت البدائل ، والانحراف المعياري للدرجات ، ومعامل ثبات الاختبار. وفي ضوء نتائج البحث الحالي توصل البحث الحالي الى النتائج الاتية : ان صياغة الفقرات لاسئلة الاختيار من متعدد له تأثير على معاملات تمييزها وصعوبتها, وفي ضوء نتائج البحث الحالي يوصي الباحث بضرورة التقيد بالتعليمات المتوافرة في الادب التربوي التي تتضمن الشروط العلمية لتصميم أسئلة الاختيار من متعدد لكي يتم تجنب الكثير من نقاط الضعف وأهمها التخمين.

Nowadays, circuit breakers (CBs) condition monitoring is essential due to the importance of the performance of these critical elements in the stability of the power grid against various faults. Exposure of the interruption chamber including main and arc contacts to high voltages along with the lack of access complicates the online condition monitoring of the CBs. Measuring the resistance of the contacts, the amount of current and the energy passing through the CB during the operation are common methods for CB condition monitoring. In this paper, a new approach is proposed based on frequency analysis to detect defects related to the non-connection of the fixed and moving parts of the main and arc contacts. It can distinguish defects from each other with proper accuracy.

Gold nanoparticles (AuNP) were deposited on the surface of multiwalled carbon nanotubes (MWCNT) by in-situ thermal decomposition of gold acetate under solvent and reducing agent free conditions to obtain a nanohybrid of AuNP-MWCNT. A glassy carbon electrode (GCE) was then modified with the nanohybrid and used for amperometric determination of hydrazine. The modified GCE showed an improved electrocatalytic effect towards hydrazine oxidation at a working potential of about 0.30 V (vs Ag|AgCl,KClsat). The calibration plot for hydrazine is linear in two concentration ranges, viz. from 0.1–100 μM and 0.2–1 mM. The respective sensitivities are 4.98 and 4.00 μA μM−1cm−2, and the limit of detection (at S/N = 3) is about 30 nM.

Adaptive water governance systems are underpinned by enhanced social learning capacity of the society of actors to understand and adapt to changes properly. Thus, as a first step, it is crucial to assess the learning capacity of water actors in different levels, as human components of a socio-ecological system (SES), to know how to improve the water resources system adaptive capacity. Aiming at practicing assessment of learning capacity in a society of water actors, the present paper focuses on local water users, one the society of farmers using the groundwater resource in Rafsanjan Plain and the other one the society of farmers in Lakes Tashk-Bakhtegan Basin, both situated in the southern Iran. A methodological framework was developed and adopted to assess the learning capacity of water users corresponding to both the process of learning (represented by social justice, perception of interdependency, mutual trust, and interaction among all stakeholders) and the learning outcomes (including width, direction, depth and orientation of learning). The required data were collected using semi-structured interviews. The results showed how the responses of the local water users are affected by the mechanisms which are rooted in the social memory, technology, path dependency, and the degree of access to water. Although most of the researchers have addressed the social learning to have positive and constructive outcomes, the results of this research revealed the process of social learning resulted in neutral and destructive outcomes among water users in the study areas. Assessment of learning capacity in the water associated societies, using the methodological framework developed in this research, can help set off removing learning barriers and enhancing the socio-ecological system adaptive capacity.

Thylakoid membranes (TMs) are uniquely suited for photosynthesis owing to their distinctive structure and composition. Substantial efforts have been directed towards use of isolated photosynthetic reaction centers (PRCs) for solar energy harvesting, however, few studies investigate the communication between whole TMs and electrode surfaces, due to their complex structure. Here we report on a promising approach to generate photosynthesis-derived bioelectricity upon illumination of TMs wired with an osmium-redox-polymer modified graphite electrode, and generate a photocurrent density of 42.4 μA cm(-2) .

In the present work, platinum and palladium nanoparticles (PtNPs and PdNPs) were decorated on the surface of multi-walled carbon nanotubes (MWCNTs) by a simple thermal decomposition method. The prepared nanohybrids, PtNPs-MWCNTs and PdNPs-MWCNTs, were cast on the surface of spectrographic graphite electrodes and then Phanerochaete chrysosporium cellobiose dehydrogenase (PcCDH) was adsorbed on the modified layer. Direct electron transfer between PcCDH and the nanostructured modified electrodes was studied using flow injection amperometry and cyclic voltammetry. The maximum current responses (Imax) and the apparent Michaelis-Menten constants (K) for the different PcCDH modified electrodes were calculated by fitting the data to the Michaelis-Menten equation and compared. The sensitivity towards lactose was 3.07 and 3.28 μA mM(-1) at the PcCDH/PtNPs-MWCNTs/SPGE and PcCDH/PdNPs-MWCNTs/SPGE electrodes, respectively, which were higher than those measured at the PcCDH/MWCNTs/SPGE (2.60 μA mM(-1)) and PcCDH/SPGE (0.92 μA mM(-1)). The modified electrodes were additionally tested as bioanodes for biofuel cell applications.

In order to study the yield and growth indix of potato under water deficit, an experiment was conducted with line-source sprinkler irrigation in Khorasan Razavi Agricultural and Natural Resource Research Center. Water deficit levels were included, at 0.75m from line-source (control), at 3.75m from line source (very mild deficit), at 6.75m from line-source (mild deficit), at 9.75m from line-source (severe deficit), at 12.75m from line source (very severe deficit).The yield were 26.47, 22.3, 17.31, 9.88 and 2.04 ton per hectare in control, very mild, mild, sever and very sever deficit respectively. Water deficit had very effects on root, shoot and tuber dry matter, total dry matter (TDM), relative growth rate (RGR), crop growth rate (CGR), leaf area index (LAI), leaf area duration (LAD), and net assimilation rate (NAR). The maximum LAD (478) was in control in 1600 GDD and maximum RGR was calculated between 0.004 and 0.005 g/g GDD in water deficit. In sever and very sever deficit, maximum CGR showed very soon (1300 and 1200 GDD respectively).

Palladium nanoparticles decorated multiwalled carbon nanotubes (PdNPs-MWCNTs) were synthesized and simply cast on the surface of a glassy carbon electrode (GCE) to prepare an amperometric sensor. The fabricated sensor (PdNPs-MWCNTs/GCE) showed excellent electrocatalytic activity towards NADH and H2O2 oxidation and H2O2 reduction. A fast, linear and highly sensitive response was observed for NADH in the concentration range between 0.1 and 200 μM with a detection limit (S/N = 3) of 32 nM. Also, the sensor exhibited fast and sensitive responses (< 2 s) towards H2O2. The sensitivity and detection limit for H2O2 at the operating potential of + 0.35 V were 167 nA μM− 1 cm− 2 and 1.2 μM, respectively and better than those obtained at the operating potential of − 0.25 V (68 nA μM− 1 cm− 2 and 14 μM). Moreover, further modification of the proposed sensor by glucose oxidase led to the fabrication of a glucose biosensor with satisfactory performance.

Electroactive adducts, comprising 3α,6α–mannan attached to the six-valent osmium complex with N,N,N´,N?-tetramethylenediamine (simply denoted, Man- Os (VI) tmen) was immobilized on the surface of graphite electrodes via a simple adsorption route and then covered with poly(sodium-4 styrene sulfonate) (PSS). Cyclic voltammograms of modified electrodes GE/Man-Os (VI) tmen showed a clear and well-resolved anodic peak for 1 mM of dopamine DA, ascorbate AA, and urate UA at the potential range of -50 to +350 mV vs. Ag|AgCl|(KClsat.) the sensor GE/Man-Os (VI) tmen/PSS was successfully used for sensitive and selective determination of DA in the presence of an excess concentration of AA and UA, 5 mM and 0.5 mM respectively, using differential pulse voltammetry. Under optimized conditions, the peak current densities were linear from 0.1 nM to 20 μM of DA with a sensitivity of 358 μA μΜ-1 and a detection limit LOD (3SD/slope) of 2.8 nM. Further modifying of the sensor using multiwall carbon nanotubes decorated with gold nanoparticles (AuNPs-MWCNTs) led to substantial improvement in its analytical characteristics. The linear response of the electrode modified GE/ AuNPs-MWCNT/Man-Os (VI) tmen to DA was spanned from 1 pM to 40 μM with a high sensitivity of 624.49 μA μΜ-1 and a LOD (3SD/slope) of 0.17 pM.

Copper(II) complexes of a series of tripodal ligands containing two phenolate moieties and NO2X (X = S or O donor ligands) coordination sphere were synthesized: N,N-bis(3,5-di-tert-butyl-2-hydroxybenzyl)-2-(aminomethyl) furan, N,N-bis(3,5-di-tert-butyl-2-hydroxybenzyl)-2-(methoxyethylamine) and newly synthesized N,N-bis(3,5-di-tert-butyl-2-hydroxybenzyl)-2-(aminomethyl) thiophene H2L have been used. The ligands H2L yielded three binuclear [L2 Cu 2 II ] complexes, which have been characterized by X-ray crystallography, UV–Vis and magnetic susceptibility measurements. The phenolate moieties of the copper complexes were electrochemically oxidized to phenoxyl radicals. The ferro- and antiferromagnetic exchange coupling of two copper centers of these complexes have been investigated by magnetic susceptibility (2–290 K) measurements. A weaker antiferromagnetic coupling is found in copper complex with methoxy arm, and a weaker ferromagnetic coupling has been observed in two other complexes with furan and thiophene arms, compared to other phenoxo-bridged dicopper(II) complexes. The weak exchange coupling constants (J) of these complexes, when compared to the literature values, is most likely attributed to the smaller Cu⋯Cu distance and Cu–O(Ph)–Cu angle.

A glassy carbon electrode modified with palladium nanoparticles decorated multiwalled carbon nanotubes (GCE/nanoPd-MWCNTs) was fabricated. Incorporation of palladium nanoparticles onto the carbon nantube surface by thermal decomposition of palladium acetate led to the fabrication of a sensor with a significant decrease in hydrazine electrooxidation potential. The sensor exhibited low detection limits, high sensitivity and selectivity, rapid response, and good stability toward hydrazine detection.

A robust and stable film comprising n-octylpyridinum hexafluorophosphate ([C8Py][PF6]) and 1:12 phosphomolybdic acid (PMo12) was prepared on glassy carbon electrodes modified with multiwall carbon nanotubes (GCE/MWCNTs) by dip-coating. The cyclic voltammograms of the GCE/MWCNTs/[C8Py][PF6]-PMo12 showed three well-defined pairs of redox peaks due to the PMo12 system. The surface coverage for the immobilized PMo12 and the average values of the electron transfer rate constant for three pairs of redox peaks were evaluated. The GCE/MWCNTs/[C8Py][PF6]-PMo12 showed great electrocatalytic activity towards the reduction of H2O2 and iodate. The kinetic parameters of the catalytic reduction of hydrogen peroxide and iodate at the electrode surface and analytical features of the sensor for amperometric determination of hydrogen peroxide and iodate were evaluated. (C) 2010 Elsevier Ltd. All rights reserved. (Less)

Prussian blue nanoparticles (PBNPs) were immobilized on the surface of a graphite electrode (GE) through a simple adsorption route and then the modified surface was covered with a layer of Nafion. The electrochemical behavior of the resulting sensor was investigated using cyclic voltammetry and chronoamperometry. The sensor showed good electrocatalytic activity toward hydrogen peroxide reduction, and it was successfully used for the amperometric detection of H2O2. The calibration curve for hydrogen peroxide determination was linear over 2.1 x 10(-6) to 1.4 x 10(-4) M mol L-1 with a detection limit (S/N = 3) of 1.0 x 10(-6) mol L-1. Additionally, further modification of the proposed sensor with glucose oxidase led to the fabrication of a glucose biosensor that showed a good performance for determination of glucose. (c) 2010 Elsevier B.V. All rights reserved. (Less)

1 : 12 Phosphomolybdic acid (PMo12) and graphite powder were homogeneously dispersed into an n-octylpyridinum hexafluorophosphate base carbon ionic liquid electrode (CILE). The cyclic voltammograms of the PMo12 modified CILE showed three well-defined pairs of redox peaks due to the PMo12 system. Formal potentials and electrochemical characteristics including electron transfer rate constant and transfer coefficient were evaluated. Additionally, PMo12 modified CILE exhibited good electrocatalytic activity toward iodate reduction. The kinetic of catalytic reduction of iodate on PMo12 modified CILE was investigated in detail. The modified electrode was used for amperometric determination of iodate in commercial table salt.

[PFeW11O39]4− (PFeW11) supported on the surface of 3-aminopropyl(triethoxy)silane modified silica gel was synthesized and used as a bulk modifier to fabricate a renewable three-dimensional chemically modified electrode. The electrochemical behavior of the modified electrode was investigated. Cyclic voltammetry studies showed that the PFeW11 on the electrode surface sustained the same electrochemical properties as that of the PFeW11 in solution. The preparation of chemically modified electrode is simple and quiet reproducible using inexpensive material. The modified electrode had high electrocatalytic activity toward H2O2 reduction and it was successfully applied as an electrochemical detector to monitor H2O2 in flow injection analysis (FIA). The electrocatalytic peak current was found to be linear with the H2O2 concentration in the range 10–200 μmol L−1 with a correlation coefficient of 0.998 and a detection limit (3σ) of 7.4 μmol L−1 H2O2. The electrode has the remarkable advantage of surface renewal owing to bulk modification, as well as simple preparation, good mechanical and chemical stability and reproducibility.

α-PW 12 O 40 3− (PW 12 ) supported on the surface of silica gel derivatized by 3-aminopropyl(triethoxy)silane (devoted briefly as SiNH 3 PW 12 ) was synthesized and used as bulk modifier to fabricate a renewable three-dimensional chemically modified electrode. The electrochemical behavior of the modified electrode was characterized by cyclic voltammetry. There is an ionic bonding character between PW 12 and the surface amino groups of modified silica, which greatly improves the stability of SiNH 3 PW 12 -modified carbon paste electrode due to insolubility of silica gel in water. The SiNH 3 PW 12 bulk-modified carbon paste electrode not only maintains the electrochemical activity of PW 12 , but also exhibits remarkable advantages of renewability, as well as simple preparation and inexpensive material. The modified electrode offers an excellent and stable electrocatalytic response for the reduction of IO 3 − and hydrogen peroxide. The SiNH 3 PW 12 -CPE is successfully applied as an electrochemical detector to monitor IO 3 − in flow injection analysis (FIA). The catalytic peak current was found to be linear with the IO 3 − concentration in the range 5 × 10 −6 to 1 × 10 −3 mol L −1 . The detection limit of the proposed method was found to be 3.1 × 10 −6 mol L −1 for IO 3 − determination.

In vitro microtuber production of potato ( Solanum tuberosum L.) cvs. Sante and Savalan were studied on solid Murashige and Skoog (MS) basal medium applying different plant growth regulators 2,4-dichlorophenoxyacetic acid and benzylamino purine (2,4-D and BAP) and photoperiods. Cultures were exposed to 16, 8 and 16 h+utter darkness photoperiodic regimes. The experimental design, complete randomized with three replications was applied. The results indicate that the effect of cultivar, hormone and photoperiod significantly had influence on whole traits. Sante cultivar had higher productivity than Savalan for whole measured traits. The results of mean comparison for photoperiod show that highest productivity for whole traits is gained by this treatment 16 h photoperiod+ utter darkness (P 3 ). In this experiment by using the combination of 2,4-D (2.26 μM) and BAP (22.19 μM), microtubers number, diameter and weight was increased. In this study, the highest number for microtuber in Sante cultivar with hormone 2,4-D and photoperiod P 3 is 9.47 which this high number for Savalan cultivar is gained by using the combination of two plant growth regulators and same photoperiod. Keywords: Tissue culture, potato, microtuber, photoperiod, hormone

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