1,721,037 research outputs found
Retention and stability of molybdenum in alkali and acid-activated geopolymer waste forms
No full textGeopolymers (GP) are emerging as sustainable, low-carbon emitting alternatives to traditional cementitious materials. Due to their versatility, scalability, and reduced environmental footprint, they are increasingly studied as engineered barriers for immobilizing radionuclides. This study evaluates molybdenum (Mo) retention and chemical durability in alkali-activated (AAM) and acid-activated (SAP) GP waste forms. Mo-loaded AAM and SAP matrices (0-8 wt%) were synthesized and analyzed for their chemical durability and leaching resistance. SAP exhibited superior Mo retention, thermal stability, and reduced leaching due to a robust silica-aluminophosphate network. Both materials met waste acceptance criteria, highlighting their potential for enhanced Mo immobilization and long-term stability in nuclear waste management
Effective Sequestering of Cobalt, Copper and Nickel Using Ethylenediaminetetraacetic Acid Modified Mesoporous Silica
No full textEthylenediaminetetraacetic acid functionalized mesoporous silica (EDTA-SBA-15) has been synthesized for effective sequestering of corrosion products from nuclear power reactor coolant. Mesoporous structure, long-range-order, and functional group loading were evaluated by N2 adsorption/desorption, small-angle X-ray scattering (SAXS), high resolution transmission electron microscopy (HRTEM) and Fourier transform infrared spectroscopy (FTIR) techniques. Results showed a proportional relationship between functional group loading and adsorption capacity. Adsorption strictly followed pseudo second order reaction and removed the corrosion metals rapidly within 20 minutes. The adsorption capacity, calculated on the basis of Langmuir model, was 1.33 mmol/g, 1.44 mmol/g, and 1.40 mmol/g for Co(II), Ni(II) and Cu(II) respectively; which is higher than other EDTA based adsorbents. Moreover, EDTA-SBA-15 revealed excellent stability against gamma irradiation, and in concentrated acidic media, which makes it practicable to apply for radioactive decontamination in nuclear facilities
Ultra-Low Temperature Sintering and Characterization of Silicon-Substituted Calcium Hydroxyapatite
No full textMechanistic insights into molybdenum immobilization within geopolymer waste form
No full textMolybdenum (Mo) tends to form highly mobile, non-sorbing complex redox species, which complicates its immobilization and encapsulation in cement and glass matrices. This study explores the potential of incorporating Mo into an alternative green cementitious material known as geopolymer (GP). By employing X-ray diffraction (XRD), Fourier transform infrared spectroscopy (FTIR), X-ray photoelectron spectroscopy (XPS), morphological analysis, and nitrogen adsorption-desorption techniques, we obtained comprehensive insights into the chemical behavior of Mo and its impact on the morphology and structure of the GP matrix. XRD and TGA analysis demonstrated that increasing Mo content significantly enhances the crystallinity and thermal stability of the GP matrix, attributed to Mo field effects. High-resolution SEM, TEM, and EDS mapping revealed the structural encapsulation of Mo-rich cavities within the GP waste form. A decrease in leaching rates with higher Mo content, alongside reduced pore volume and pore size, underscores the material's chemical durability. Postleaching characterizations confirmed that the GP retains excellent structural strength with minimal changes in mesoporosity and surface area. This resilience highlights the effectiveness of GPs in immobilizing non-sorbing species like MoO32- , making them ideal for long-term waste management.
In situ tailoring the morphology of In(OH)(3) nanostructures via surfactants during anodization and their transformation into In2O3 nanoparticles
No full textThe present work reports the effect of various surfactants on the morphology of In(OH)(3) nanostructures prepared via anodization. In-sheets were anodized in an environmentally benign electrolyte containing a small quantity of CTAB, CTAC, and PDDA surfactants at room temperature. The produced nanostructures were characterized using XRD, HRTEM, SAED, and EDAX. The morphology of indium hydroxide (In(OH)(3)) nanostructures was successfully tailored in situ with the help of surfactants in 1 M KCl aqueous electrolyte. XRD results confirmed the formation of In(OH)(3) and indium oxyhydroxide (InOOH) nanostructures in the pristine form which were transformed into single-phase cubic In2O3 nanoparticles (NPs) after calcination. HRTEM analyses showed that the morphology and size of the In(OH)(3) nanostructures can be tuned to form nanorods, nanosheets and nanostrips using different surfactants. The results revealed that CTAC and PDDA surfactants have a profound effect on the morphology of In(OH)(3) nanostructure compared to CTAB due to the higher concentration of Cl- ion. The possible mechanism of surfactants effect on the morphology is proposed. Furthermore, annealing converted the In(OH)(3) nanostructures into spherical In2O3 NPs with uniform and homogeneous size. We anticipate that the morphology of other metal-oxides nanostructure can be tuned using this simple, facile and rapid technique. In2O3 NPs prepared without and with CTAB surfactant were further explored for the non-enzymatic detection of hydrogen peroxide (H2O2). Electrochemical measurements showed enhanced electrocatalytic performance with fast electron transfer (similar to 2s) between the redox centers of H2O2 and electrode surface. The In2O3 NPs prepared using CTAB/Au electrode exhibited about 4-fold increase in sensitivity compared to the bare Au electrode. The biosensor also demonstrated good reproducibility, higher selectivity, and increased shelf life.
اقبال ساجد کی شاعری کا موضوعاتی مطالعہ
No full text"Iqbal Sajid belongs to the modern ghazal poets but he did not get the position he deserved. A true reflection of the image of human emotions seems to be dancing in his words. The emotions he presented in his poetry reflect individuality as well as collective anguish. Iqbal Sajid was a sensitive and loving person. His speech is not only his tragedy but also the tragedy of thousands of people who cannot fulfill even the most basic desires of life. He has portrayed the exploiting class in a very favorable manner. He wanted to eliminate the class consciousness among the people so that he did not become a part of this system but always raised his voice against it. Iqbal Sajid could not end this system of economic injustices, but he fell into eternal sleep by realizing his own and burning the candle of his share, but his speech is like the radiant light of the sun for next generation and everyone will utilize according to one,s ability.
Going Beyond Counting First Authors in Author Co-citation Analysis
Get PDFThe present study examines one of the fundamental aspects of author co-citation analysis (ACA) - the way co-citation
counts are defined. Co-citation counting provides the data on which all subsequent statistical analyses and mappings
are based, and we compare ACA results based on two different types of co-citation counting - the traditional type that
only counts the first one among a cited work's authors on the one hand and a non-traditional type that takes into
account the first 5 authors of a cited work on the other hand. Results indicate that the picture produced through this non-traditional author co-citation counting contains more coherent author groups and is therefore considerably clearer. However, this picture represents fewer specialties in the research field being studied than that produced through the traditional first-author co-citation counting when the same number of top-ranked authors is selected and analyzed. Reasons for these effects are discussed
Variations on the Author
Get PDF“Variations on the Author” discusses two of Eduardo Coutinho’s recent films (Um Dia na Vida, from 2010, and Últimas Conversas, posthumously released in 2015) and their contribution to the general question of documentary authorship. The director’s filmography is characterized by a consistent yet self-effacing form of authorial self-inscription: Coutinho often features as an interviewer that rather than express opinions propels discourses; an interviewer that is good at listening. This mode of self-inscription characterizes him as an author who is not expressive but who is nonetheless markedly present on the screen. In Um Dia na Vida, however, Coutinho is completely absent form the image, while Últimas Conversas, on the contrary, includes a confessional prologue that moves the director from the margins to the center of his films. This article examines the ways in which these works stand out in the filmography of a director who offers new insights into the notion of cinematic authorship
- …
