9 research outputs found
Measurement of alpha particle range in CR-39 detector using nuclear track profiles
No full textAlpha particle is very dangerous inside the human body, so the study of its interaction parameters for alpha is very important. The Solid-State Nuclear track detector (SSNTD) CR39 can be used to study the different parameters for alpha. In this research, the bulk etch rate (VB) measured by using two different methods. The results showed that the measured of VB values by the Lmax method is very close to the values measured by the weight method. The average value of VB by Lmax method and weight method were 1.26 ± 0.02 μm h−1 - 1.28 ± 0.13 μm h−1 respectively. Also, the results for the range of alpha particles changed from 13.21 ± 0.05 μm for alpha energy 3 MeV to 34.58 ± 0.19 μm for alpha energy 5.48 MeV. The measurement of alpha particles range by the Lmax method for all energies of alpha were very closes to the theoretical range of values. The Lmax method is useful for determining all the different parameters of the path
Environmental impacts of waste produced from processing of different uraniferous rock samples
No full textRadon exhalation rates from five studied laboratory waste samples resulted from five different sedimentary rock types named sandy dolostone, siltstone –two samples-, marly claystone and black shale were measured using ‘‘Sealed Can technique”. These rates were found to vary between 0.005 and 0.015 Bq m−2 h−1. A positive correlation was found between the radon exhalation rates and the radium activities. The emanation coefficients were calculated for these laboratory waste samples which varied between 0.0004 and 0.0007 according to the physical and chemical characterize of the wastes. These results are partially in accordance with autonite acid leached tailings on laboratory scale (USA). These results led us to pay attention about the effect and impact of these wastes on the environment
Pediatric Osteosarcoma of Extremities: A 15-year Experience From a Tertiary Care Cancer Center in Upper Egypt
No full textUnravelling Syria's Entho-Sectarian Politics
No full textGoaded by the regional repercussions of the Syrian crisis sectarian tensions are emerging as the key threat to Middle Eastern and Syrian stability. Sectarianism has had a big impact on politics in Syria, it is implicated in the maintenance of authoritarianism, and sectarian dynamics are escalating the intensity of the uprising against the Assad regime. Prior to the civil war communal bonds between regime members and minority sect insecurity were key to the survival of the regime. Political power and control was maintained through fear and this was not just fear of the powerful security forces but also fear of sectarian conflict with the regime highlighting the risk of sectarian conflict, minority persecution and instability should the regime fall. As a result many supported or tolerated the Assads out of fear of the alternative.
This thesis aims to analyse the extent and the manner in which political players in Syria have used religious narratives and manipulated sectarian identities in their pursuit of power. It concludes that sectarian tactics have been intensified within the Syrian uprising by both the regime and within the opposition. Religious narratives for mobilising support have become widespread and an emphasis on dangers from the ‘other’ is prevalent. Given Middle Eastern history of intolerance towards other religious and ethnic groups this emphasis on confessional narratives is intensifying the dangers of sectarian violence within the civil war and creating rifts that will be hard to heal.
The use of religious narratives for political goals is a feature of the religious and political landscape and this is analysed through the lens of Ethnic Conflict Theory. With radical Islam heavily featuring narratives that emphasise opposition to other, an entitlement to dominate and an admiration of religious warrior characteristics alongside the cultural importance of nested communal groups, Islam has served as a readymade construct for mobilising sectarian groups against political foes.
However although many sectarian narratives refer heavily to history the current confessional tensions relate specifically to the present. With Middle Eastern autocratic regimes under threat due to the Arab Spring many groups perceive that political power is up for grabs and are finding it expedient – and religiously justifiable - to mobilise through the established channels of confessional loyalties and networks particularly along Sunni versus Shia lines. Plus given the importance of religion to the region it is a clear front runner as justification for political and/or armed action.
Advances in communications technology, specifically social media, and the breakdown of regime authority has allowed for voices to be heard from within an autocratic state that had otherwise been silenced, thus providing an unprecedented opportunity to analyse sectarian politics within a civil war
The social and ritual contextualisation of Ancient Egyptian hair and hairstyles from the Protodynastic to the end of the Old Kingdom
No full textHair, the most malleable part of the human body, lends itself to the most varied forms of
impermanent modifications. The resulting hairstyles convey social practices and norms,
and may be regarded as part of the “representation of self” and an integral element in
the maintenance and structuring of society. In this thesis, a systematic and quantative
investigation has been undertaken of the structural relationships between variations in
hairstyles and principal changes in social organisation in ancient Egypt from the
Protodynastic to the end of the Old Kingdom (3,350-2,181 BC), a period that witnessed
the rise, consolidation and eventually breakdown of centralised authority.
The results reveal that hairstyles were linked to the identity of individuals and
social groups, such as men, women, children and the elderly. Hairstyles were used as a
means of displaying status. After experimentation with a broad spectrum of hairstyles
during the Protodynastic and early Dynasty I, an institutionalised canon for hairstyles
was established, coinciding with the creation of administrative institutions. These
codified hairstyles continued to serve as the norms for identifying members of the
administration or signs of authority. By the end of the Old Kingdom, the hairstyles of
the elite had been adopted by the lower officials of the increased bureaucracy and
provincial elites as representations of their newly acquired power and status.
Although initially the majority of the men had their hair cut short, modifications
of short hair and the adoption of mid- and shoulder-length hair became progressively
common. The use of certain hairstyles was restricted to the higher social offices, with
longer hair being emblematic of power and divinity. Women, by contrast, initially had
long hair with greater variety occurring by Dynasty I and a more restricted array from
Dynasty II onwards. However, long hair was predominant among women of all social
statuses in all periods. Long hair may have thus been related to the perception of women
as mothers (responsible for childbirth and nursing), and hence their perceived role as
directly linked with procreation and fecundity. Although the adoption of the tripartite by
high officials was related to this ‘generative’ aspect of feminine hairstyles, it was
primarily in imitation of the God Osiris and his regenerative powers
Polyurethane urea modified with a derivative of castor oil with elastomeric applications
No full textfotografías, graficas, tablasLa incorporación de compuestos poliméricos biobasados han adquirido mucha importancia y relevancia en la actualidad, debido a que permiten la reducción de los compuestos que tiene como origen el petróleo mediante la inclusión de nuevas fuentes renovables en su producción.
En este trabajo se obtuvo un derivado del aceite de ricino mediante la transesterificación del aceite con el fin de reducir la funcionalidad hidroxilo y poder obtener un producto lineal para la elaboración de un elastómero de poliuretano urea (PUU). En la síntesis se utilizó aceite de ricino con dietilenglicol en exceso y KOH como catalizador. El producto obtenido fue separado y caracterizado por resonancia magnética nuclear (RMN), espectroscopia de infrarrojo por transformada de Fourier (FTIR), análisis termogravimétrico (TGA) y número hidroxilo, obteniéndose como bandas características para el ricinoleato (REG) el -OH en 1050 cm-1 del grupo hidroxilo primario y los picos 3.6 y 4.1 ppm correspondientes al –CH2 adyacente a un carbono secundario y al CH2-C-C=O-, respectivamente. El producto obtenido presentó una temperatura de degradación de 165ºC y un valor hidroxilo de 328 mg KOH/g.
Posteriormente, se formuló y obtuvo un poliuretano urea biobasado (PUUR) con un segmento duro (%HS) de 40% a partir del derivado de aceite de ricino con una adición de ricinoleato de etilenglicol (REG) de 1.6% molar, una temperatura de 90ºC, catalizador DABCO y utilizando la técnica por solvente en dos pasos con un 32% de sólidos disueltos de igual forma se sintetizó un PUU estándar a las mismas condiciones con el fin de establecer las variaciones del producto biobasado. Estos productos fueron caracterizados
X Poliuretano Urea Modificado con un Derivado de Aceite de Ricino con
Aplicaciones Elastoméricas
por RMN, FTIR, TGA, DSC y finalmente, por un ensayo de tracción para evaluar las características mecánicas de los productos. A través de la RMN se estableció que el producto REG se incorporó a la estructura a través del protón en la ubicación de 5.40 ppm (–CH) que corresponde a la insaturación del REG. Adicionalmente, se observó un cambio en el módulo de tracción del PUUR aumentando un 29% y reduciendo la elongación en un 82% con respecto al PUU estándar sintetizado, además se presenta también una reducción en 17 ºC en su estabilidad térmica, una reducción de la cristalización fría y un aumento en la temperatura de fusión del producto final con respecto al PUU estándar.
Estos resultados son importantes, ya que se pudo sintetizar un producto biobasado mediante la modificación del aceite de ricino, y se pudo establecer los efectos ocasionados por el uso de este tipo de productos renovables en las propiedades finales de los poliuretanos urea lineales, adicionalmente se establecieron los procesos de síntesis y purificación de cada una de las etapas del proceso para la producción de un polímero de ingeniería como es el PUU con un derivado de fuente renovable (Texto tomado de la fuente)The incorporation of biobased polymeric compounds has acquired great importance and relevance today, because they allow the reduction of compounds that have petroleum origin by including new renewable sources in their production.
In this work, a derivative of castor oil was obtained by means of transesterification of the oil in order to reduce the hydroxyl functionality and to obtain a linear product for the elaboration of a polyurethane urea elastomer. In the synthesis, castor oil was obtained with excess diethylene glycol and KOH as catalyst. The obtained product was separated and characterized by nuclear magnetic resonance (NMR), Fourier transform infrared spectroscopy (FTIR), thermogravimetric analysis (TGA) and hydroxyl number, obtaining as characteristic bands for ricinoleate (REG) the -OH in 1050 cm-1 of the primary hydroxyl group and the 3.6 and 4.1 ppm peaks corresponding to –CH2 adjacent to a secondary carbon and to CH2-C-C=O-, respectively. The product obtained had a degradation temperature of 165°C and a hydroxyl value of 328 mg KOH/g.
Subsequently, a biobased polyurethane urea (PUUR) with a hard segment (%HS) of 40% was formulated and obtained from the castor oil derivative with an addition of ethylene glycol ricinoleate (REG) of 1.6% molar, a temperature of 90ºC, DABCO catalyst and using the solvent technique in two steps with 32% dissolved solids, in the same way, a standard PUU was synthesized under the same conditions in order to establish the variations of the biobased product. These products were characterized by NMR, FTIR, TGA, DSC and finally, by a tensile test to evaluate the mechanical characteristics of the products. Through NMR it was established that the REG product was incorporated into the structure through
the proton at the location of 5.40 ppm (–CH) which corresponds to the unsaturation of the REG. In addition, a change in the traction modulus of the PUUR was lost, increasing by 29% and elongation was reduced by 82% with respect to the synthesized standard PUU, in addition there is also a reduction of 17 ºC in its thermal stability, a reduction in the cold crystallization and an increase in the melting temperature of the final product with respect to standard PUU.
These results are important, since it was possible to synthesize a biobased product by modifying castor oil, and it was possible to establish the effects caused by the use of this type of renewable products on the final properties of linear urea polyurethanes, additionally it suffers the synthesis and purification processes of each of the stages of the process for the production of an engineering polymer such as PUU with derivatives from renewable sources.MaestríaMagíster en Ingeniería - Ingeniería QuímicaPolímeros y Materiales CompuestosQuímica Y Procesos.Sede Manizale
