1,314 research outputs found
Interview with Abd al-Azim Ramadan
No full textهذة المقابة مع الكاتب المؤرخ عبد العظيم رمضان، يتحدث عن التاريخ، الفرق بين التاريخ المعاصر عن الأنواع الأخرى. أجرت المقابلة درية شرف الدينIn this interview, Egyptian historian author Abd al-Azim Ramadan speaks about modern history and its types. The interview was conducted by Dorreya Sharaf al-Din
The emergence of mercantilism as a reaction against Muslim power: some of the evidences from history
No full textIn the early modern period, changing attitude of Medieval Europe towards trade as an outcome of encounter with Muslim scholars and rulers and consequently emergence of 'mercantilism' was a turning point in the history of economic thought. The paper documents evidences which prove that initially mercantilism was a reaction against Muslim powers. In the rise of mercantilism, discovery of the New World is considered a significant factor. The main objective before explorers and pioneers of mercantilism was to strengthen their governments through the acquisition of precious metal to regain the Holy Places, defeat the enemy, check the expanding power of Muslim rivals and spread Christianity. However, later it ended up in an effective economic movement.Mercantilism; History of Economic Thought; Medieval Economic History.
POLIESTERAMIDI ALIFATICHE CONTENENTI BLOCCHI DI POLIDIMETILSILOSSANO SINTETIZZATE PER VIA ENZIMATICA
No full textPolyesteramides containing polydimethylsiloxane blocks are successfully synthesized in bulk at 70 C via a biocatalytic route starting from diethyladipate, 1,8-octanediol and ,-diaminopropyl-polydimethylsiloxane as monomers. The amide/ester ratio of the copolymers with different composition is calculated by means of 1H NMR spectroscopy, and it is in agreement with the molar feed ratio of monomers. The relative amount of amide and ester units along the polymer chain strongly affects the physical aspect of the polyesteramides that change from hard solids, when rich in crystallizable ester units, to soft sticky materials when the silicon-based amide unit is the major component. The copolymers are characterized by TGA, DSC and WAXS analyses
Enzymatic synthesis and solid-state properties of aliphatic polyesteramides with polydimethylsiloxane blocks
No full textThe synthesis of silicone polyesteramides was successfully performed in bulk at 70 °C via a biocatalytic route. Immobilized Candida antartica Lipase B (Novozyme 435, N435) was used as catalyst under mild conditions to perform the polycondensation reaction using various feed mole ratios of diethyladipate (DEA), 1,8-octanediol (OD) and alfa,omega-diaminopropyl-polydimethylsiloxane (Si-NH2). The syntheses of poly(octamethylene adipate), POA, and poly(alfa,omega-diaminopropyl- polydimethylsiloxane adipamide), PSiAA, were also performed by N435 catalysis in order to compare their properties with those of silicone polyesteramides. The microstructures of all polymers were studied by 1H NMR spectroscopy, and calculated amide/ester ratios were in agreement with the monomer feed mole ratio. Thermal stability of the polyesteramides, evaluated by TGA both in nitrogen and in air, increases with polydimethylsiloxane adipamide content (up to 50mol%). The relative amount of amide and ester units along the polymer chain strongly affects the physical aspect of the polyesteramides. High content of octamethylene adipate units leads to hard solid materials containing a well developed high melting POA-type crystal phase, whose melting temperature changes with composition. When polydimethylsiloxane adipamide is the major component, the material acquires a sticky appearance
Environmens study for determentation the concentration and origin of Hydrocarbon in sediment cores of Al-Azim
No full textThe present study appear the concentration, source and origin of petroleum hydrocarbons in sediment core of two station of Hor Al- Azim at Hor Al – Huwaiza ,total hydrocarbon measurement by spectroflurometer were in these sediment cores. Higher concentration (20.5 μg/g) dry weight at depthe (0-5) cm in Azim (I) while lower conceatrations (1.5) μg/g dry weight at depth (100-105) cm, in Al-Azim (II) higher conceantration was (17.52) μg/g at (0-5) cm depth and lower concentration (1.73) μg/g at depth (80 -85) cm .The higher percentage for total organic carbon (TOC%) appear in Al-Azim (I) (3.52)% at depth (0-5) cm while lower percentage were (0.15)% at depth (90-95) cm . In Al-Azim (II) higher percentage were (4.2)% at depth (0-5) while lower percentage (0.72)% at depth (80-85) cm and we well do to analysis grain size at the sediment were mainly muddy silt with low sand in addition to ports sheel from mollusca shell and disintegrate vegetation for both of the tow core
Book review: the reflective teacher - case studies of action research
No full textThe author, Neeraja Raghavan, has for several years now pursued her passion for education and has done extensive work in teaching children and in teacher education. In this, her latest, book, she has systematically captured all the experiences and learnings that emerged during the five months (August-December 2013) of action research taken up by eight teachers and the Principal of Azim Premji School in Dineshpur, Uttarakhand. As principal investigator, she anchored this action research project, which was facilitated by members from Azim Premji Foundation
From CO2 to CH4 via biological methanation
No full textThe leitmotif of this Ph.D. thesis is represented by carbon dioxide (CO2) recycling via biological production of methane (CH4).
This work particularly focuses on the physiology of three hydrogenotrophic methanogens, Methanothermobacter marburgensis (M. marburgensis), Methanothermococcus okinawensis (M. okinawensis) and Methanococcus maripaludis S2 (M. maripaludis), that can be used as catalysts for biological methane production (BMP) process. This CO2 recycling method is challenging due to an inefficient transfer rate of molecular hydrogen (H2) from the gas phase to the liquid phase. Thus, the biocatalyst performance is limited by H2 availability in the liquid medium. However, several factors, as strain type and media requirements, operating conditions, and reactor design, can contribute to the success of CO2 conversion to CH4. Understanding the physiology of methanogens is a powerful tool for developing a scalable BMP process. Therefore, a novel study on the role of trace metals in pure cultures of M. okinawensis and M. marburgensis respectively is herein proposed. Experimental method of this study included an in silico analysis, closed batch, and fed-batch cultivations. In silico analysis revealed genomic differences among the transport systems and enzymes related to the methanogenesis pathway of these two methanogens. The importance of Fe as metal cofactor in methanogenesis emerged from the in silico analysis and it has been confirmed by the closed batch and fed-batch experiments. M. okinawensis responded to rising concentrations of trace element (TE) by increasing specific growth rate (μ, h-1) and volumetric productivity of methane (MER, mmolL-1h-1) during closed batch cultivation. Furthermore, M. okinawensis shown growth and CH4 in fed-batch cultivation. On the base of fed-batch cultures results, M. marburgensis was prioritized and applied for CO2-based BMP process optimization. It has been proposed a new feeding strategy based on exponential fed-batch cultivation where different medium-, TE- and sulphide dilution rates combinations, and different CO2/H2 inflow rates corresponded to a defined run. The specific setting of each run produced different responses from M. marburgensis. In this context, a MER of 476 mmol L-1 h-1 and μ of 0.69 h-1 were eventually achieved at highest H2/CO2 gassing rate and ratio. However, if these factors mitigate the limitation due to the H2 mass transfer on one side, they also reduce CH4 purity in the offgas on the other side. The combined effect of increasing TE dilution and H2/CO2 gassing rates positively affected the biomass and biomass concentration. Among trace elements, there are heavy metals whose toxicity is higher than others. Heavy metals can seriously affect the functionality of microorganisms, and therefore compromise their performances as biocatalysts of a bio-based process. Not only metals, but also organic compounds, such as carboxylic acids, can damage cells survival. Thus, the second experimental part of this thesis deals with inhibition studies on pure culture of M. maripaludis in closed batch cultivation. Despite the potential applications of M. maripaludis, the knowledge surrounding this strain runs out of lab-scale studies concerning the physiology and toxicology of heavy metals and VFAs. Therefore, M. maripaludis growth and productivity were tested by using copper (Cu), zinc (Zn), acetate (Ac) and propionic acid (Pr) as potential inhibitors of microbial activity. The culture was totally inhibited at concentration of 30, 70 and 100 mgL-1 of Cu and 0.7 and 1 gL-1 of Zn. However, M. maripaludis shows tolerance to 3, 7 and 10 mgL-1 of Cu with different extent. The addition of 0.3 gL-1 of Zn to the medium, rather promoted the biomass build-up of M. maripaludis and cancelled the effect of Cu when used together in the medium. In this study, it has been supported that the inhibition by Cu is due to a reduced or suppressed activity of the CODH/ACS complex producing acetyl-CoA intermediate. Acetyl-CoA is the precursor of many metabolic subsystems (e.g. lipid, amino acids, nucleotides pathways) and its alteration would interfere with them. While CODH/ACS activity is supported by CO2 and methanogenesis intermediate, the other way to produce acetyl-CoA is based on the acetate:CoA ligase. The relevance and the tolerance to rising concentrations of Ac and Pr was also investigated and quantified via HPLC analysis. Concentration of 5 and 10 mgL-1 of acetate did not inhibit nor growth neither productivity. Interestingly, the deprivation of acetate not only impacted on the growth rate but also on methanogenesis in M. maripaludis. In absence of Ac, the same concentrations of Pr caused a slow-down of the growth, while productivity was not touched. This study sheds light on the individual and combined impact of Cu, Zn, acetate and propionic acid on the metabolism of M. maripaludis. Furthermore, an attempt to define a possible mechanism which regulates specific acetate capture is provided in this study and the relevance of acetate:CoA ligase respect to CODH/ACS complex for acetyl-CoA synthesis is herein discussed. The information collected in this study are essential to improve the process efficiency of CO2 conversion to CH4 and extend the knowledge on the physiology of certain compounds. The tendency of these methanogens to adapt to adverse conditions, most of the time, offers the possibility to improve the engineering aspects of a limited process toward an unlimited one. Moreover, as a future activity, this thesis proposed the use of a 10-bar pressure bioreactor which has been projected in the frame of the Ph.D. research with a view to improving the success of biological CH4 production
Contract Teachers in India: Recent trends and current status
No full textThis study is conducted by ERU Consultants Private Limited, New Delhi with support from Azim Premji University. The analysis and opinions expressed in this publication are those of the author(s) and may not represent the view of the Azim Premji University. This publication may be reproduced by any method without fee for teaching or nonprofit purposes. The publication shall not be used for commercial purposes. Rights are reserved under Creative Common Licence. Any derivative works shall also be protected under the same license. Rights are reserved under Creative Common Licence: Attribution + Non-Commercial + Share Alike. For copying in any other circumstances, or for re-use in other publications, or for translation or adaptation, prior written permission must be obtained from the publisher
Visual scene recognition with biologically relevant generative models
No full textThis research focuses on developing visual object categorization methodologies that are based on machine learning techniques and biologically inspired generative models of visual scene recognition. Modelling the statistical variability in visual patterns, in the space of features extracted from them by an appropriate low level signal processing technique, is an important matter of investigation for both humans and machines. To study this problem, we have examined in detail two recent probabilistic models of vision: a simple multivariate Gaussian model as suggested by (Karklin & Lewicki, 2009) and a restricted Boltzmann machine (RBM) proposed by (Hinton, 2002). Both the models have been widely used for visual object classification and scene analysis tasks before. This research highlights that these models on their own are not plausible enough to perform the classification task, and suggests Fisher kernel as a means of inducing discrimination into these models for classification power. Our empirical results on standard benchmark data sets reveal that the classification performance of these generative models could be significantly boosted near to the state of the art performance, by drawing a Fisher kernel from compact generative models that computes the data labels in a fraction of total computation time. We compare the proposed technique with other distance based and kernel based classifiers to show how computationally efficient the Fisher kernels are. To the best of our knowledge, Fisher kernel has not been drawn from the RBM before, so the work presented in the thesis is novel in terms of its idea and application to vision problem
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