5,082 research outputs found

    Scaling behavior of a one-dimensional correlated disordered electronic System

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    A one-dimensional diagonal tight binding electronic system with correlated disorder is investigated. The correlation of the random potential is exponentially decaying with distance and its correlation length diverges as the concentration of "wrong sign" approaches to 1 or 0. The correlated random number sequence can be generated easily with a binary sequence similar to that of a one-dimensional spin glass system. The localization length (LL) and the integrated density of states (IDOS) for long chains are computed. A comparison with numerical results is made with the recently developed scaling technique results. The Coherent Potential Approximation (CPA) is also adopted to obtain scaling functions for both the LL and the IDOS. We confirmed that the scaling functions show a crossover near the band edge and establish their relation to the concentration. For concentrations near to 0 or 1 (longer correlation length case), the scaling behavior is followed only for a very limited range of the potential strengths.Comment: will appear in PR

    Reclamation of malachite green-bearing wastewater using desert date seed shell: adsorption isotherms, desorption and reusability studies

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    A low-cost activated carbon adsorbent was prepared from desert date seed shell (DDSS) and utilized for the removal of hazardous malachite green (MG) from aqueous solution using batch mode technique. Different isotherm models were applied to acquire the theoretical data of MG adsorption onto the adsobent at variable initial concentration of 100-1000 mg dm-3. Based on the coefficient of determination (R2), isotherm models exhibit the following sequence: Freundlich > Langmuir > Redlich-Peterson > Temkin > Jovanovic > Harkin- Jura > Elovich > Dubinin-Radushkevic. The maximum monolayer capacity of the adsorbent was found to be 312.5 mg g-1 at 303 K. The mean free energy value (0.91 kJ mol-1) obtained from D-R isotherm suggests that the adsorption process follows physisorption mechanism. Desorption studies for reusability revealed that acetic acid offered the best recovery (52.09%) and the process follow pseudo-second-order kinetics. The conducted reusability test revealed the decline of the adsorbent performance from 96.5% MG removal down to 70.5% MG removal after 5 successive adsorption/desorption cycles.Keywords: Activated Carbon, Desorption, Isotherms, Malachite Green, Reusabilit

    Effect of GeoGebra Computer Package on Performance in Concept Integral Calculus among Colleges of Education Students in Borno State

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    This study investigated the effect of the GeoGebra computer package on performance in concept integral calculus among colleges of education students in Borno State. The study was guided by three objectives, research questions, and corresponding hypotheses, respectively. The population of the study was made up of 478 mathematics students in the department of mathematics from the two (2) colleges of education in Borno State during the 2021/2022 academic session. Purposive sampling techniques were used to select one college of education. Thus, gave a sample size of sixty (60) students. A quasi-experimental design specifically, pre-test, post-test, and non-randomized control group was used for this study. The instruments used for data collection is Integral Performance Test Items (IPTIs) developed by the researcher and validated by three experts. The reliability coefficient of the instrument was 0.81 using the Cronbach alpha reliability test. In answering research questions descriptive statistics of mean, standard deviation and mean difference was used and t-test was used to test the null hypotheses. Findings revealed that the GeoGebra computer application package has significant effects on the performance of students taught integral calculus when compared with students exposed to the Lecture teaching method. Moreover, male students perform better than female students taught concept integral calculus using the GeoGebra computer package. The study recommends that teachers and students should be encouraged to explore the GeoGebra computer application package in solving problems related to integral calculus

    Gender equality under sharia law in Bangladeshi court practice in the light of CEDAW

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    https://www.ester.ee/record=b536142

    Removal of crystal violet from aqueous solution using desert date (Balanites aegyptiaca) seed shell

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    The feasibility of utilizing desert date seed shell (DDSS) as an alternative low-cost adsorbent for the removal of hazardous crystal violet (CV) dye from aqueous solution was investigated. The prepared adsorbent was characterized by Fourier transform infrared (FTIR) spectroscopy (Cary 630; Agilent Technologies) and scanning electron microscopy (PRO: X: Phenonm World 800-07334). The influence of operational parameters such as contact time, adsorbent dosage, pH, and temperature were studied using batch mode technique. The obtained results showed that 60 min contact time, 0.4g adsorbent dose, solution pH of 8 and 60 oC temperature resulted in maximum CV removal. The equilibrium data fitted very well to Freundlich model (R 2 = 0.9983) and the KF and 1/n values were found to be 31.21 dm3g -1 and 0.828 respectively. The maximum adsorption capacity of DDSS for CV as determined by Langmuir isotherm is 294.12 mg g -1at 303K. Kinetic analysis revealed that the pseudo second order was the best model (R 2 = 0.9999) for the description of CV uptake with the experimental value of qe 20.3575 mg g -1 being closer to the calculated value of the qe 20.3651 mg g -1 . Thermodynamic studies revealed a negative value for ∆G o (-11.07 kJ mol -1 ) and a positive value for ∆H o (33.75 kJ mol -1 ) and ∆S o (134.9 J mol -1 K-1  ). These indicated the  spontaneous and endothermic nature of the adsorption process. Keywords: Adsorption, Desert date seed shell, Crystal violet, Batch  mode, Modelin

    Kompetensi Pedagogik Guru Dalam Meningkatkan Motivasi Belajar Siswa Pada SMPN 3 Ingin Jaya Kabupaten Aceh Besar

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    : This study aimed to determine the teacher's pedagogical competence in lesson planning, learning process, and in improving students' motivation. To achieve these objectives, this study used descriptive qualitative approach. Data were collected through interview, observation, and documentation. The procedures of data analysis were data reduction data display and data verification. The subjects of this study were the principal, vice-principals and teachers. The results showed that: (1) the teachers' pedagogical competence in lesson planning was done by preparing a lesson plan draft, but some teachers did not bring the lesson plan during the learning process so that the learning objectives were not maximally achieved; (2) the teachers' pedagogical competence in the learning process was done by comprehending and solidifying the understanding on a number of learning materials contained in textbooks. Whereas in the learning process, there were for classroom management and undisciplined use of time: and (3) the teachers' pedagogical competence in improving student motivation was done by providing opportunities for students to be actively involved in the use of information and coomunication technology facilities in the achievementof learning goals, communicating effectively with learners, and conducting reflectieve action to improve the quality of learning

    An Overview of Some Hydrological Models in Water Resources Engineering Systems

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    Researches in hydrological modelling are aimed to the understanding of the behavior of hydrologic systems in an attempt to make better predictions and to address the major challenges in water resources systems. Hydrological modelling concept is concerned with the relationship of water, climate, soil and land use. Hydrological models are classified either as: conceptual or physical, lumped or distributed, deterministic or stochastic. Hydrological models are the main tools that hydrologist use with different purposes such as water resources management, storm water management, reservoir system analysis, flood prediction, climate change assessment and among others. Many hydrological models have been developed for different purposes. The methodology for using hydrological models include: definition of the problem and specifying the objectives, studying the data available, specifying the economic and social constraints, choosing a particular class of hydrological models, selecting a particular type of model from the given class, calibrating and validating the model, evaluating the performance of the model, and finally using the model for the specified purpose. Some recently developed, frequently used, and powerful hydrological models including WEAP, SWMM, HEC-HMS, HEC-RAS, and HEC-ResSim were herein assessed taking into cognizance their applications in solving challenges in water resources engineering systems

    Effects of Crushed and Powdered Brick Particles on Lightweight Papercrete

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    This paper studied a light weight paper and mortar composite called papercrete which was produced using brick particles as aggregate and as pozzolan. Papercrete samples were produced with crushed brick particles to completely substitute sand as fine aggregate and labelled Sample BAP. Another set of samples were produced using crushed brick particles as aggregate and powdered brick particles as pozzolan to partially replace 10% of the cement content. These were labelled Sample BCP. Additional samples labelled Sample SP were produced with sand as aggregate and with no cement replacement to serve as controls. Initially, an X-ray diffraction analysis was performed on powdered brick particles to assess their chemical composition in line with ASTM 618. A total of 135 test samples were cast and tested for density, water absorption, compressive strength and tensile strength at 14 and 28 days. Similarly, samples were subjected to thermal conductivity and fire reaction tests. The results show an increase in density, compressive and tensile strength of Samples BAP and BCP over Sample SP. Additionally, all samples recorded low thermal conduction and a good reaction to fire as none of the samples ignited when subjected to fire. However, all samples had high water absorption values. It was concluded that using crushed and powdered brick particles to produce papercrete increases its density and strength and can be used as aggregate and pozzolan in producing papercrete
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