Short Nylon-6 Fibre/Rubber-Toughened Polystyrene Composites

The thesis describes studies on development of short Nylon-6 fibre composites based on rubber-toughened polystyrene (PS). Toughening was done using natural rubber (NR), styrene-butadiene rubber (SBR) and whole tyre reclaim (WTR). The composites were prepared by melt mixing in an internal mixer at 170 oC. It was found that the optimum blend ratio was 85/15 for PS/NR, 90/10 for PS/SBR and 90/22 for PS/WTR blends. The effect of dynamic vulcanisation on 85/15 PS/NR and 90/10 PS/SBR blends using dicumyl peroxide (DCP) at various concentrations were also studied. The dynamic crosslinking improved the tensile properties, flexural properties, impact strength and dynamic mechanical properties of both the blends. The effect of unmodified and resorcinol formaldehyde latex (RFL)-coated short Nylon-6 fibres on the mechanical properties, morphology and dynamic mechanical properties of 85/15 PS/NR, 90/10 PS/SBR and 90/22 PS/WTR blends were studied. Fibre loading was varied from 0 to 3 wt.%. For 85/15 PS/NR blend, there was a significant enhancement in tensile properties, flexural properties and impact strength with 1 wt.% of both unmodified and RFL-coated fibres. Dynamic mechanical analysis revealed that the storage modulus at room temperature was maximum at 1 wt.% fiber loading for both composites. The surface functionality of the fiber was improved by giving alkali treatment. Maleic anhydride-grafted-polystyrene (MA-g-PS) was prepared and used as a compatibiliser. The effect of MA-g-PS on the composites was investigated with respect to mechanical properties, morphology and dynamic mechanical properties. The compatibiliser loading was varied from 0 to 2 wt.%. The properties were enhanced significantly in the case of treated and untreated fibre composites at a compatibiliser loading of 0.75 wt.%. SEM analysis confirmed better bonding between the fibre and the matrix. Dynamic mechanical studies showed that the storage modulus at room temperature improved for treated fibre composites in the presence of compatibiliser. In the case of 90/10 PS/SBR composites, the addition of short Nylon-6 fibres at 1 wt.% loading improved the tensile modulus, flexural properties and impact strength while the tensile strength was marginally reduced. The surface treated fibers along with compatibiliser at 0.5 wt.% improved the tensile properties, flexural properties and impact strength. DMA reveale that the storage modulus at room temperature was better for composites containing untreated fibre and the compatibiliser. In the case of 90/22 PS/WTR blends, 1 wt.% unmodified fibre and 0.5 wt.% RFL-coated fibres improved tensile modulus, flexural properties and impact strength. Tensile strength was improved marginally. The surface treatment of Nylon fibre and the addition of compatibiliser at 0.5 wt.% enhanced the tensile properties, flexural properties and impact strength. The dynamic mechanical analysis showed that the storage modulus at room temperature was better for untreated fibre composites in conjunction with the compatibiliser. The thermal stability of PS/NR was studied by TGA. Thermal stability of the blends improved with dynamic vulcanisation and with the incorporation of RFL-coated Nylon fibres. The untreated and partially hydrolyzed fibre composites in conjunction with the compatibiliser enhanced the thermal stability. Kinetic studies showed that the degradation of the blends and the composites followed first order kinetics.

Studies on Catalysis by Titania

Scientists throughout the world are in search of a better methodology to reduce the use of environmentally hazardous chemicals common in industries .A significant contribution in this field is given by different redox catalysts in oxidation reactions. The oxidation of organic substrates represents one of the most important industrial chemical reactions, explaining the significant efforts invested in the research and development of new heterogeneous catalysts with increased activities and selectivities in these type reactions[l-4|. Hence liquid phase reactions like epoxidation of cylcohexene and hydroxylation of phenol were carried out with a new outlook in the challenge using CeO2/TiO;; and CuO/TiO2 catalysts denoted as TiO2-Ce as TiO2-Cu respectively in this work. Also different wt% of metals incorporated titania catalysts like 3, 6, 9 wt% CeO2/TiO; and CuO/TiO;were subjected to the present study .The interaction between metal oxides and the oxide supports have attracted much attention because of the wide applications of supported metal oxide systems[7,8]. It is well known that supported oxides of transition metals are widely used as catalysts for various reactions. Titania as well its metal modified catalysts systems afford high activity and selectivity in the liquid phase epoxidation of cyclohexene[9]. Cyclohexene epoxide is obtained as the major product during the reaction with small amounts of allylic substitution products.This chapter gives an idea about the liquid phase oxidation reactions like epoxidation of cylcohexene and hydroxylation of phenol in which many industrially important products are formed. Here discusses about the redox properties of the ceria and copper incorporated titania catalysts.The epoxidation of cyclohcxene is carried out efficiently over the prepared systems with the selective formation of cyclohexane epoxide. This reaction hints that it might be possible to create cleaner nylon chemistry. The total acidity of the prepared systems plays an important role in determining the catalytic activity in the dehydrogenation of cyclohexane and cyclohexene. The total acidity of the prepared systems plays an important role in determining the catalytic activity in the dehydrogenation of cyclohexane and cyclohexene.

Studies on seed pathology and seedling diseases of some important indigenous tree species of kerala

In forestry, availability of healthy seeds is an important factor in raising planting stock. Initial seed health and storage conditions are the major factors governing the germinability of seeds. Like seeds of agricultural and horticultural crops, forest tree seeds are also liable to be affected by micro-organisms during storage, which affects the germination, and reduces the viability. Further introduction of seed-borne diseases into newly sown crops/areas on account of using unhealthy seeds is also not ruled out. Availability of healthy stock of seedlings is intrinsic for raising plantations and to meet this requirement elimination of nursery diseases by appropriate chemicals is of prime imortance. As exotic tree species may become susceptible to various native pathogens, it is generally considered better to select indigenous tree species for large scale plantations as they are well adapted to local environment. However, before taking up large scale afforestation progranme involving any indigenous tree species, it is essential to have knowledge about seed disorders and seedling diseases and their management. with a View to select appropriate tree species with fewer seed disorders and seedling disease problems for use in further plantation programme, four indigenous tree species such as Albizia odoratissima (L.f) Benth., Lagerstroemia microcazpa Wt., Pterocazpus marsupiwn Roxb. and Xylia xylocarpa (Roxb.) Taub. were evaluated to meet the above parameters

Development of plant tissue culture of Plumbago rosea Linn. for enhanced production of secondary metabolites

P rosea syn. Indica belong to the family of plumbaginaceae, is an important medicinal plant, cultivated widely in India. The roots of these plant are generally used for medicinal purposes mainly as diuretic, germicidal, vessicant, and abortifacient. It is also used for anaemia, diarrhea, leprosy and common wart. The bark of the root contains orange yellow pigment named plumbagin, a crystalline substance, belongs to the class of naphthoquinone. Its chemical structure is 5-hydroxy 2-methyl 1,4naphthoquinone. Apart from P rosea, P zeylanica, P europea, Drosera and Drosophyllum also contains plumbagin. The most exploited source of plumbagin is, of course, P. rosea roots. The roots contain O.9mg/ g D.Wt. of plumbagin in the roots. These plants grow very slowly and the roots suitable for plumbagin extraction can be obtained only after several years of growth. The productivity of the plant is also rather poor. The focus of the present study was to develop alternative strategies to obtain plumbagin. The tissue culture of P rosea for micropropagation has been studied

Biogeochemistry of the shelf sediments of south eastern Arabian sea: Effect on benthic bacterial heterotrophs

The composition and variability of heterotrophic bacteria along the shelf sediments of south west coast of India and its relationship with the sediment biogeochemistry was investigated. The bacterial abundance ranged from 1.12 x 103 – 1.88 x 106 CFU g-1 dry wt. of sediment. The population showed significant positive correlation with silt (r = 0.529, p< 0.05), organic carbon (OC) (r = 0.679, p< 0.05), total nitrogen (TN) (r = 0.638, p< 0.05), total protein (TPRT) (r = 0.615, p< 0.05) and total carbohydrate (TCHO) (r = 0.675, p< 0.05) and significant negative correlation with sand (r = -0.488, p< 0.05). Community was mainly composed of Bacillus, Alteromonas, Vibrio, Coryneforms, Micrococcus, Planococcus, Staphylococcus, Moraxella, Alcaligenes, Enterobacteriaceae, Pseudomonas, Acinetobacter, Flavobacterium and Aeromonas. BIOENV analysis explained the best possible environmental parameters i.e., carbohydrate, total nitrogen, temperature, pH and sand at 50m depth and organic matter, BPC, protein, lipid and temperature at 200m depth controlling the distribution pattern of heterotrophic bacterial population in shelf sediments. The Principal Component Analysis (PCA) of the environmental variables showed that the first and second principal component accounted for 65% and 30.6% of the data variance respectively. Canonical Correspondence Analysis (CCA) revealed a strong correspondence between bacterial distribution and environmental variables in the study area. Moreover, non-metric MDS (Multidimensional Scaling) analysis demarcated the northern and southern latitudes of the study area based on the bioavailable organic matter

Ni filled flexible multi-walled carbon nanotube–polystyrene composite films as efficient microwave absorbers

In this letter, we report flexible, non corrosive, and light weight nickel nanoparticle@multi-walled carbon nanotube–polystyrene (Ni@MWCNT/PS) composite films as microwave absorbing material in the frequency range of S band (2-4 GHz). Dielectric permittivity and magnetic permeability of composites having 0.5 and 1.5 wt. % filler amount were measured using the cavity perturbation technique. Reflection loss maxima of 33 dB (at 2.7 GHz) and 24 dB (at 2.7 GHz) were achieved for 0.5 and 1.5 wt. % Ni@MWCNT/PS composite films of 6 and 4 mm thickness, respectively, suggesting that low concentrations of filler provide significant electromagnetic interference shielding

Classification of Mammograms and DW T based Detection of Microcalcification

Cancer treatment is most effective when it is detected early and the progress in treatment will be closely related to the ability to reduce the proportion of misses in the cancer detection task. The effectiveness of algorithms for detecting cancers can be greatly increased if these algorithms work synergistically with those for characterizing normal mammograms. This research work combines computerized image analysis techniques and neural networks to separate out some fraction of the normal mammograms with extremely high reliability, based on normal tissue identification and removal. The presence of clustered microcalcifications is one of the most important and sometimes the only sign of cancer on a mammogram. 60% to 70% of non-palpable breast carcinoma demonstrates microcalcifications on mammograms [44], [45], [46].WT based techniques are applied on the remaining mammograms, those are obviously abnormal, to detect possible microcalcifications. The goal of this work is to improve the detection performance and throughput of screening-mammography, thus providing a ‘second opinion ‘ to the radiologists. The state-of- the- art DWT computation algorithms are not suitable for practical applications with memory and delay constraints, as it is not a block transfonn. Hence in this work, the development of a Block DWT (BDWT) computational structure having low processing memory requirement has also been taken up.

Mn2þ-induced room-temperature ferromagnetism and spin-glass behavior in hydrothermally grown Mn-doped ZnO nanorods

The magnetic properties of Mn-doped ZnO (ZnO:Mn) nanorods grown by hydrothermal process at a temperature of 200 8C and a growth time of 3 h have been studied. The samples were characterized by using powder X-ray diffraction with Rietveld refinement, scanning electron microscopy, energy-dispersive X-ray analysis and SQUID magnetometry. Mn (3 wt%) and (5 wt%)-doped ZnO samples exhibit paramagnetic and ferromagnetic behavior, respectively, at room temperature. The spin-glass behavior is observed from the samples with respect to the decrease of temperature. At 10 K, both samples exhibit a hysteresis loop with relatively low coercivity. The room-temperature ferromagnetism in 5 wt% Mn-doped ZnO nanorods is attributed to the increase in the specific area of grain boundaries, interaction between dopant Mn2þ ions substituted at Zn2þ site and the interaction between Mn2þ ions and Zn2þ ions from the ZnO host lattice

Studies on Advanced Oxidation Processes for the Removal of Acetamiprid from Wastewater

Pollution of water with pesticides has become a threat to the man, material and environment. The pesticides released to the environment reach the water bodies through run off. Industrial wastewater from pesticide manufacturing industries contains pesticides at higher concentration and hence a major source of water pollution. Pesticides create a lot of health and environmental hazards which include diseases like cancer, liver and kidney disorders, reproductive disorders, fatal death, birth defects etc. Conventional wastewater treatment plants based on biological treatment are not efficient to remove these compounds to the desired level. Most of the pesticides are phyto-toxic i.e., they kill the microorganism responsible for the degradation and are recalcitrant in nature. Advanced oxidation process (AOP) is a class of oxidation techniques where hydroxyl radicals are employed for oxidation of pollutants. AOPs have the ability to totally mineralise the organic pollutants to CO2 and water. Different methods are employed for the generation of hydroxyl radicals in AOP systems. Acetamiprid is a neonicotinoid insecticide widely used to control sucking type insects on crops such as leafy vegetables, citrus fruits, pome fruits, grapes, cotton, ornamental flowers. It is now recommended as a substitute for organophosphorous pesticides. Since its use is increasing, its presence is increasingly found in the environment. It has high water solubility and is not easily biodegradable. It has the potential to pollute surface and ground waters. Here, the use of AOPs for the removal of acetamiprid from wastewater has been investigated. Five methods were selected for the study based on literature survey and preliminary experiments conducted. Fenton process, UV treatment, UV/ H2O2 process, photo-Fenton and photocatalysis using TiO2 were selected for study. Undoped TiO2 and TiO2 doped with Cu and Fe were prepared by sol-gel method. Characterisation of the prepared catalysts was done by X-ray diffraction, scanning electron microscope, differential thermal analysis and thermogravimetric analysis. Influence of major operating parameters on the removal of acetamiprid has been investigated. All the experiments were designed using central compoiste design (CCD) of response surface methodology (RSM). Model equations were developed for Fenton, UV/ H2O2, photo-Fenton and photocatalysis for predicting acetamiprid removal and total organic carbon (TOC) removal for different operating conditions. Quality of the models were analysed by statistical methods. Experimental validations were also done to confirm the quality of the models. Optimum conditions obtained by experiment were verified with that obtained using response optimiser. Fenton Process is the simplest and oldest AOP where hydrogen peroxide and iron are employed for the generation of hydroxyl radicals. Influence of H2O2 and Fe2+ on the acetamiprid removal and TOC removal by Fenton process were investigated and it was found that removal increases with increase in H2O2 and Fe2+ concentration. At an initial concentration of 50 mg/L acetamiprid, 200 mg/L H2O2 and 20 mg/L Fe2+ at pH 3 was found to be optimum for acetamiprid removal. For UV treatment effect of pH was studied and it was found that pH has not much effect on the removal rate. Addition of H2O2 to UV process increased the removal rate because of the hydroxyl radical formation due to photolyis of H2O2. An H2O2 concentration of 110 mg/L at pH 6 was found to be optimum for acetamiprid removal. With photo-Fenton drastic reduction in the treatment time was observed with 10 times reduction in the amount of reagents required. H2O2 concentration of 20 mg/L and Fe2+ concentration of 2 mg/L was found to be optimum at pH 3. With TiO2 photocatalysis improvement in the removal rate was noticed compared to UV treatment. Effect of Cu and Fe doping on the photocatalytic activity under UV light was studied and it was observed that Cu doping enhanced the removal rate slightly while Fe doping has decreased the removal rate. Maximum acetamiprid removal was observed for an optimum catalyst loading of 1000 mg/L and Cu concentration of 1 wt%. It was noticed that mineralisation efficiency of the processes is low compared to acetamiprid removal efficiency. This may be due to the presence of stable intermediate compounds formed during degradation Kinetic studies were conducted for all the treatment processes and it was found that all processes follow pseudo-first order kinetics. Kinetic constants were found out from the experimental data for all the processes and half lives were calculated. The rate of reaction was in the order, photo- Fenton>UV/ H2O2>Fenton> TiO2 photocatalysis>UV. Operating cost was calculated for the processes and it was found that photo-Fenton removes the acetamiprid at lowest operating cost in lesser time. A kinetic model was developed for photo-Fenton process using the elementary reaction data and mass balance equations for the species involved in the process. Variation of acetamiprid concentration with time for different H2O2 and Fe2+ concentration at pH 3 can be found out using this model. The model was validated by comparing the simulated concentration profiles with that obtained from experiments. This study established the viability of the selected AOPs for the removal of acetamiprid from wastewater. Of the studied AOPs photo- Fenton gives the highest removal efficiency with lowest operating cost within shortest time.

Differential effects of insulin signaling on individual carbon fluxes for fatty acid synthesis in brown adipocytes

Considering the major role of insulin signaling on fatty acid synthesis via stimulation of lipogenic enzymes, differential effects of insulin signaling on individual carbon fluxes for fatty acid synthesis have been investigated by comparing the individual lipogenic fluxes in WT and IRS-1 knockout (IRS-1 KO) brown adipocytes. Results from experiments on WT and IRS-1 KO cells incubated with [5-¹³C] glutamine were consistent with the existence of reductive carboxylation pathway. Analysis of isotopomer distribution of nine metabolites related to the lipogenic routes from glucose and glutamine in IRS-1 KO cells using [U-¹³C] glutamine as compared to that in WT cells indicated that flux through reductive carboxylation pathway was diminished while flux through conventional TCA cycle was stimulated due to absence of insulin signaling in IRS-1 KO cells. This observation was confirmed by quantitative estimation of individual lipogenic fluxes in IRS-1 KO cells and their comparison with fluxes in WT cells. Thus, these results suggest that glutamine’s substantial contribution to fatty acid synthesis can be directly manipulated by controlling the flux through reductive carboxylation of alpha-ketoglutarate to citrate using hormone (insulin).

Estudio logístico en la empresa COMERFRUTAS de Colombia S.A.S para la exportación de pulpa de limón al mercado holandés

El presente documento ofrece una guía logística y análisis financiero para las pequeñas y medianas empresas (PyMES) de Colombia que deseen exportar pulpa de limón al mercado Europeo. Para el desarrollo de este trabajo se ha tomado el caso de la micro empresa COMERFRUTAS de Colombia S.A.S. (productora de pulpa de limón) y se ha realizado un estudio de competitividad de puertos, agentes de carga tanto terrestre como marítimos para dar las bases necesarias de exportación a las PyMES colombianas en un marco legal establecido.

Internacionalización de operadores logísticos casos exitosos: SERVIENTREGA FEDEX DEUTSCHE POST - DHL

Este trabajo muestra la evolución de la internacionalización de las empresas del sector Operadores Logísticos a partir de una muestra suficientemente amplia que permita deducir similitudes dentro de los procesos que llevaron a cabo al realizarlos. Para lograr este objetivo se tomó como muestra representativa las empresas de operadores logísticos en contextos diferentes; específicamente se analizaron las compañías Servientrega, FedEx, Deutsche Post-DHL. Se consideró que estas firmas son ejemplos claros del sector por ser los líderes en sus países y mantener el mercado cautivo a lo largo del tiempo. Gran parte de la relevancia del estudio se desprende de los diferentes entornos en que las empresas desarrollan sus actividades; con lo anterior se quiere decir que no deberían mostrar la misma evolución, el crecimiento y desarrollo de un operador logístico en el caso alemán, ni en el estadounidense y mucho menos en el caso colombiano. Sin embargo, como se demostrará a lo largo de este working paper se pueden hallar procesos similares demostrando que los casos empíricos muestran congruencia con la literatura de teorías de internacionalización. El resultado del estudio es una ruta de exportación a seguir para futuros operadores logísticos. De tal forma, se podría tomar este working paper como una guía de navegación para diferentes empresas nacientes en el sector a lo largo del mundo, toda vez que están por encima de los diferentes ámbitos locales.

Enfoque del paciente con trastornos del sueño

La importancia del sueño y las patologías relacionadas con el mismo son ampliamente reconocidas en el campo de la medicina y la neurología, sin embargo la mayoría de neurólogos dedican muy poco tiempo al estudio de estas entidades y muy raramente durante la valoración de los pacientes se indaga acerca de la presencia de trastornos relacionados con el sueño. Esto es sorprendente si tenemos en cuenta que pasamos casi un tercio de la vida durmiendo, además de la alta incidencia de trastornos de sueño en la población general. A continuación revisaremos los principales trastornos del sueño, su diagnóstico y tratamiento.

La actuación de la República de China (Taiwán) como Estado de Facto en el Sistema Internacional, periodo 1971 - 2011

El presente es un estudio de caso que busca encontrarle significado a la actuación de la República de China (Taiwán) como Estado de Facto en el Sistema Internacional, durante el periodo 1971 – 2011. El estudio se centra en las formas de validación jurídicas que le permiten a Taiwán interactuar con otros actores en el Sistema Internacional.

Sugammadex versus neostigmina en la reversión de la relajación neuromuscular en neurocirugía. Experimento clínico. Reporte preliminar

Existen grupos quirúrgicos específicos donde es mandatorio el uso de relajantes neuromusculares no despolarizantes, como es el caso de los pacientes llevados a procedimiento de neurocirugía; debido a sus características particulares el rocuronio es una buena alternativa para este tipo de procedimientos, ya sea en bolos o en infusión. Sin embargo la relajación residual y los efectos adversos de los medicamentos para revertir la relajación neuromuscular deben tenerse en cuenta en este grupo de pacientes en particular. El presente trabajo busca comparar la reversión de la relajación de infusiones de rocuronio, con Neostigmina mas Atropina vs la reversión con Sugammadex en pacientes llevados a manejo quirúrgico de lesiones supratentoriales por parte del servicio de neurocirugía de la Fundación Cardioinfantil, evaluando complicaciones durante la administración de los medicamentos y 24 horas posoperatorias, así como los tiempos para extubación y salida de salas de cirugía. Estudio con características de experimento prospectivo, aleatorizado, ciego, controlado. En este documento se realiza un reporte preliminar descriptivo de 14 pacientes reclutados hasta la actualidad.