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au:SINGH, R. K.

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Evaluation of inhibitory activity, purification and X-ray crystallography of Alpha-Amylase inhibitor from Phaseolus vulgaris cultivars of Uttarakhand, India
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Singh, R.

; Dobriyal, A. K.

; Singh, R. D.

; Ríos-Escalante, P. De los

Brazilian Journal of Biology

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2024, Volume 84 elocation e253180

Abstract: Pt En | Text: Pt En | PDF: Pt | PDF: En

Resumo O presente trabalho é fundamentado na análise da atividade inibitória do inibidor da alfa-amilase em cultivares selecionadas de Phaseolus vulgaris, de Uttarakhand. Quinze amostras foram avaliadas quanto à atividade inibitória do inibidor da alfa-amilase. Variações significativas foram encontradas em diferentes cultivares. O extrato bruto do inibidor da alfa-amilase da amostra PUR (Purola) apresentou atividade inibitória máxima (70,2 ± 0,84). O extrato bruto de todas as cultivares apresentou variações consideráveis na atividade inibitória na temperatura de 20ºC a 100ºC. Com base na atividade inibitória e no perfil de estabilidade ao calor, o inibidor da alfa-amilase foi purificado do cultivar PUR. O inibidor purificado mostrou-se estável mesmo a 90ºC, com uma atividade inibitória de 97,20 ± 0,09. O peso molecular do inibidor purificado em Native PAGE (eletroforese em gel de poliacrilamida) foi de 31kd, consistindo em duas subunidades de 17kd e 14kd em SDS-PAGE.

Abstract The present work is based on analysis of inhibitory activity of alpha-amylase inhibitor in selected cultivars of Phaseolus vulgaris of Uttarakhand. Fifteen samples were assessed for inhibitory activity of alpha-amylase inhibitor. Significant variations were found in different cultivars. Crude extract of alpha-amylase inhibitor from sample PUR (Purola) have shown maximum inhibitory activity (70.2 ± 0.84). Crude extract of all the cultivars have shown considerable variations in inhibitory activity in the temperature ranging from 20ºC to 100ºC. Based on inhibitory activity and heat stability profile, the alpha amylase inhibitor was purified from PUR cultivar. The purified inhibitor was found to be stable even at 90ºC with an inhibitory activity of 97.20 ±0.09. The molecular weight of purified inhibitor on Native PAGE (Polyacrylamide gel electrophoresis) was found to be 31kd, consisting of two subunits of 17kd and 14kd on SDS-PAGE.

https://doi.org/10.1590/1519-6984.253180

A Novel Leaf Extract of Sorghum Vulgare as an Eco-friendly Corrosion Inhibitor for Mild Steel Corrosion in 0.5 M H 2 SO 4
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Sharma, S.

; Sharma, M.

; Dheer, N.

; Ujjain, S. K.

; Ahuja, P.

; Singh, G.

; Kanojia, R.

Portugaliae Electrochimica Acta

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aug 2023, Volume 41 N. 4 Pages 273 - 287

Abstract: En | Text: En | PDF: En

Abstract MS effective corrosion inhibition by SVLE has been investigated using electrochemical methods. Tafel polarization measurements suggested that the reaction at the anode occurred with MS dissolution, due to the strong medium aggressiveness, but SVLE addition led to a corrosion IE(%) of 93.6%, at 298 K. SVLE IE(%) still was 86% at an elevated T of 328 K, which was also confirmed by SEM observations that revealed a protective adsorbed film formed by the inhibitor onto the MS surface.

https://doi.org/10.4152/pea.2023410402

Modeling and performance optimization of starch-based biocomposite films using response surface methodology
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Mittal, M.

; Chaudhary, R.

; Phutela, K.

; Airon, M.

; Singh, R.C.

Journal of applied research and technology

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2022, Volume 20 N. 4 Pages 430 - 447

Abstract: En | Text: En | PDF: En

Abstract: The primary objective of this study is to optimize the significant parameters (filler type, filler size, and content) for improving the performance of starch-based biocomposite films. The mathematical and statistical tools such as response surface methodology (RSM) and analysis of variance (ANOVA) were employed for modeling and optimization. To verify the different developed models, validation tests were also performed. The results showed that the RSM based central composite design (CCD) is an effective tool to predict the relationship between various input parameters and desired responses. Most of the desirable properties [tensile strength, Young’s modulus, impact strength, water vapor transmission rate (WVTR), and opacity] of starch-based films were improved with the increase of filler content. The optimum values of input and response parameters are: filler content: 8.11 wt.%, filler size: 27.07 µm, filler type: walnut shell, tensile strength: 32.43 MPa, Young’s modulus: 333.338 MPa, elongation at break: 9.90 %, impact strength: 34.12 J/mm, WVTR: 1040.40 g m-2 24 h-1, rate of degradation (ROD): 31.6918 weight loss%/day, transparency 58.60 %transmittance/mm, and solubility 27.06%.

https://doi.org/10.22201/icat.24486736e.2022.20.4.1239

Microbial activity and studies on excavated megalithic micaceous potsherds from Peninsular India
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Singh, M. R.

; Ganaraj, K.

; Sharma, V. M.

Cerâmica

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jun 2021, Volume 67 N. 382 Pages 250 - 260

Abstract: En | Text: En | PDF: En

Abstract The abundantly available mica flakes were added in raw materials to manufacture pottery in Central Peninsular India during the early Iron Age (700-300 BCE) for storage and glittering. The micaceous potsherds from the excavated megalithic site of Nagpur were studied for their composition, manufacturing techniques, microstructural features, microbial colonization, and estimation of firing temperature. The analytical techniques used were micro-XRF, FTIR, XRD, FEG-SEM, mercury porosimetry (MIP), and thermal analysis. The XRF and SEM-EDX data revealed that the potteries were coated with aqueous iron oxide on either surface for red hue and subsequently fired at an estimated temperature of 700-750 °C in a reducing atmosphere as determined by vibrational and mineralogical analysis. The X-ray microscopy and FEG-SEM images showed a grey color sandwich layer representing the original clay composition between iron oxide-coated red surface layers. MIP showed that the fine ware had a high porosity of 21-26% with a void ratio (e) of 0.28-0.36. The loosely adhered mica flakes influenced the strength and stability of the pottery. The 16S rRNA gene sequencing identified the presence of Bacillus velezensis within the round and elongated pits within the potsherds drawing nutrients from minerals.

https://doi.org/10.1590/0366-69132021673823026 205 downloads

Three-dimensional shear-wave quality factor, Qs(f), model for South-Central Gulf of California, Mexico obtained from inversion of broadband data
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Kumar, Sanjay

; Joshi, Anand

; Castro, Raul R.

; Singh, Shri K.

; Singh, Sandeep

Geofísica internacional

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jun 2021, Volume 60 N. 2 Pages 140 - 159

Abstract: En Es | Text: En Es | PDF: En | PDF: Es

Abstract We apply an iterative inversion scheme, initially developed by Hashida and Shimazaki (1984) and later modified by Joshi et al., (2010), to estimate three - dimensional shear - wave quality factor, Qs (f), of south-central Gulf of California, Mexico. An area of 230 km x 288 km in this region is divided into 108 rectangular blocks of different Qs (f). We use 25 well-located earthquakes recorded at three broadband stations of the regional network RESBAN operated by CICESE (Centro de Investigación Científica y de Educación Superior de Ensenada, Baja California) and three Ocean Bottom Seismographs (OBS) of the Sea of Cortez Ocean Bottom Array (SCOOBA) experiment. This dataset permits us to obtain Qs (f) estimates of different blocks using the modified inversion algorithm. Qs (f) is obtained at various frequencies in 0.16 ~8.0 Hz range. We found that the estimated Qs structure correlates with geological and tectonic models of the region proposed in previous studies. A regional frequency-dependent relation using all 1944 values of shear-wave quality factor is obtained at 18 different frequencies in all blocks can be approximated by a function of the form Qs (f) = 20 f1.2. This relation is typical in a tectonically active region with high S-wave attenuation and is similar to attenuation relations reported by other authors for the Imperial Valley, California region.

Resumen Se aplicó un esquema de inversión iterativo, inicialmente desarrollado por Hashida y Shimazaki (1984) y posteriormente modificado por Joshi et al., (2010), para estimar el factor de calidad de onda corta tridimensional, Qs (f), del centro-sur del Golfo de California, México. Es un área de 230 x 288 km que se divide en 108 bloques rectangulares de diferentes Qs (f). Se utilizó 25 terremotos bien ubicados registrados en tres estaciones de banda ancha de la red regional RESBAN operada por CICESE (Centro de Investigación Científica y de Educación Superior de Ensenada, Baja California) y tres Sismógrafos de Fondo Oceánico (OBS, por sus siglas en inglés) de un conjunto del Experimento del Fondo Oceánico del Mar de Cortés (SCOOBA, por sus siglas en inglés). Este conjunto de datos permitió obtener estimaciones de Qs (f) de diferentes bloques, utilizando el algoritmo de inversión modificado. El Qs (f) se obtuvo a varias frecuencias en el rango de 0,16 ~ 8,0 Hz. Se encontró que la estructura Qs estimada se correlaciona con los modelos geológicos y tectónicos de la región propuestos en estudios previos. Se obtuvo una relación regional dependiente de la frecuencia que utiliza todos los valores de 1944 del factor de calidad de la onda de corte a 18 frecuencias diferentes en todos los bloques y se puede aproximar mediante una función de la forma Qs (f) = 20 f 1.2 . Esta relación es típica en una región tectónicamente activa con alta atenuación de onda S y es similar a las relaciones de atenuación reportadas por otros autores para la región del Valle Imperial, California.

https://doi.org/10.22201/igeof.00167169p.2021.60.2.2053 3 downloads

26/11 Mumbai terrorist attack revisited: Lessons learnt and novel disaster model for future
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Sonawane, Dhiraj V.

; Garg, Bipul K.

; Chandanwale, Ajay

; Mathesul, Ambarish A.

; Shinde, Omkar R.

; Singh, Shravan

Jàmbá: Journal of Disaster Risk Studies

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2020, Volume 12 N. 1 Pages 1 - 4

Abstract: En | Text: En | PDF: En

https://doi.org/10.4102/jamba.v12i1.915 101 downloads

Machine tool vibration on dimensional accuracy and surface roughness during milling operation of Al6082 with indexable carbide inserts
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Chamble, Paramesh

; Bharath, M. R.

; Lokesha, K.

; Ezhil Singh, S. Christopher

Journal of applied research and technology

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2020, Volume 18 N. 2 Pages 69 - 76

Abstract: En | Text: En | PDF: En

Abstract In this research paper, machining tool vibration occurs because of relative motion between the work piece and the cutting tool, which influences the surface finish of the machined part and the lifespan of the cutting tool. Some of the parameters that influence machining tool vibration include feed rate, depth of cut and spindle speed. In this study, experimentation is carried out on a conventional vertical milling machine to investigate the influence of machining tool vibration on surface roughness during face milling operation of Al6082 alloy with indexable carbide inserts. The eutectic phase for joint of Al6082 is β-Al5FeSi eutectic phase. The machining is done in dry condition under the different combinations of Machining parameters designed through Taguchi L9 orthogonal array. The machining tool vibrations are captured with the help of tri-axial accelerometer. Analysis of variance (ANOVA) technique used to formulate the experimental data to analyze the effect of each parameter and machining tool vibration on surface roughness.

33 downloads

Parametric resonance in concrete beam-columns
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Sharma, Mamta R.

; Singh, Arbind K.

; Benipal, Gurmail S.

Latin American Journal of Solids and Structures

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nov 2014, Volume 11 N. 6 Pages 925 - 945

Abstract: En | Text: En | PDF: En

A dynamic instability, called parametric resonance, is exhibited by undampedelastic beam-columns when under the action of pulsating axial force. The scope of the existing theory of parametric resonance is restricted to physically linear beam-columns undergoing finite lateral displacements. In this Paper, the dynamic behaviour of physically nonlinear elastic cracked concrete beam-columns under pulsating axial force and constant lateral force is investigated. The constitutive equations derived earlier by Authors in the form of force-displacement relations are employed here to formulate equations of motion of the SDOF cantilever with mass lumped at its free end. The expected phenomenon of parametric resonance is exhibited in the form of regular subharmonic resonance at about the frequency ratio of two. Resonance peaks broaden with increase in pulsating force. Like damping, physical nonlinearity is also predicted to stabilize the dynamic response at resonance frequencies. In some particular statically unstable conditions, the loss of dynamic stability is shown to occur by divergence. Unexpectedly, similar phenomenon of parametric resonance is exhibited by these physically nonlinear beam-columns undergoing even small lateral displacements. The contribution made to the theory of parametric resonance and the potential relevance of the proposed theory to design of concrete beam-columns is discussed.

2243 downloads

Stability of concrete beam-columns under follower forces
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Sharma, Mamta R.

; Singh, Arbind K.

; Benipal, Gurmail S.

Latin American Journal of Solids and Structures

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oct 2014, Volume 11 N. 5 Pages 790 - 809

Abstract: En | Text: En | PDF: En

An axial follower force acting on the free end of a beam-column is known to remain tangential to its elastica at that point. Elastic beam-columns exhibit infinitely high buckling resistance to static compressive follower load. Loss of their dynamic stability is known to occur at critical follower loads, by flutter characterized by vanishing lateral displacement and infinitely high natural frequency. Classical theory deals with physically linear nonconservative beam-columns. Physical nonlinearity exhibited by concrete beam-columns under service loads is caused by the closing and reopening of the extant transverse cracks. In this Paper, analytical expressions for the lateral displacement and lateral stiffness of such concrete beam-columns are derived. Using these expressions, the stability of physically nonlinear elastic flanged concrete beam-columns under the action of a follower compressive axial force and a lateral force is investigated. The significance of the analytical approach and the theoretical predictions is discussed.

6395 downloads

10.

Chemical and genetic diversity among some wild stands of Calligonum polygonoides (Polygonaceae) from the Thar Desert of Rajasthan
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K. Vyas, Govind

; Kumar, Vinod

; Sharma, R.

; Sharma, R.A.

; Sharma, S.

; Singh, J.P.

; Kumar, Sushil

Revista de Biología Tropical

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sep 2012, Volume 60 N. 3 Pages 1097 - 1108

Abstract: Es En | Text: Es En | PDF: Es | PDF: En

El árido Rajastán occidental, en donde está inmerso el desierto de Thar en la India, está cubierto principalmente por dunas de arena, un paisaje común. La región ha enfrentado la fragilidad de los recursos naturales, las lluvias escasas, irregulares y mala distribución, y está cubierta con muchos arbustos resistentes perennes. Calligonum polygonoides, el arbusto perenne más común, se encuentra ampliamente en algunas localidades del desierto de Thar. En este estudio, se evaluó la diversidad presente entre 54 plantas silvestres de Calligonum polygonoides, de ocho localidades diferentes del desierto de Thar. Nuestros métodos incluyen características químicas/nutricionales y ADN polimórfico amplificado (RAPD) al azar. Ambos métodos químicos y moleculares producen un amplio rango de la diversidad, sin embargo, RAPD detectó comparativamente mayor diversidad. Un total de 163 posiciones de la banda fueron producidos por diez cebadores RAPD, de los cuales 147 se encontraron polimórficos con un 90.18% de polimorfismo. El coeficiente de RAPD basado en la similitud de Jaccard varió desde 0.43 hasta 0.89. El análisis de varios constituyentes químicos y minerales reveló que Calligonum polygonoides es una excelente fuente de calcio, potasio y fósforo mientras que es relativamente pobre en zinc. Entre los minerales, el contenido de potasio promedio se encontró como máximo (2 430mg/100g), con 0.14 CV. El zinc se observó comparativamente menor en cantidad, pero presentó la mayor variabilidad con CV 0.73. El valor del coefficente de disimilitud de Manhattan varió en un rango de 0.01 hasta 0.22 con un promedio de 0.12. La comparación de los grupos obtenidos según los parámetros químicos y minerales con las de los datos de RAPD mostró que los grupos formados en ambos casos mostraron patrones diferentes de relaciones entre las muestras. Una gama más amplia de la diversidad podría ser debido al comportamiento reproductivo C polygonoides e indica la buena adaptabilidad de las plantas en la región estudiada. Sin embargo, la baja diversidad observada en la provincia de Bikaner es alarmante, y sugiere que las actividades antropogénicas que conducen a disturbios excesivos en la población pueden afectar la composición genética de la especie de una manera considerable

The arid Western Rajasthan, where the Thar Desert of India is immersed, is mostly covered by sand dunes, a common landscape. The region has confronted with fragilities of natural resources, low, erratic and ill-distributed rainfall, and is covered up with many perennial hardy shrubs. Calligonum polygonoides, the most common perennial shrub, is widely present in some localities of this Thar Desert. In this study, we evaluated the diversity present among 54 wild Calligonum polygonoides plants, sampled from eight different locations within the Thar Desert. Our methods included chemical/nutritional characteristics and random amplified polymorphic DNA (RAPD). Both chemical and molecular methods produced wider range of diversity, however, RAPD detected comparatively more diversity. A total of 163 band positions were produced by ten RAPD primers, of which 147 were found polymorphic with 90.18% polymorphism. RAPD-based Jaccard’s similarity coefficients ranged from 0.43-0.89. The analysis of various chemical and mineral constituents revealed that phog is an excellent source of calcium, potassium and phosphorous while relatively poor in zinc. Among minerals, average potassium content was found maximum (2 430mg/100g) with 0.14 CV. Zinc was observed comparably less in quantity while highest variable with CV 0.73. The chemical-based Manhattan dissimilarity coefficient values ranged from 0.01-0.22 with an average of 0.12. The comparison of the clusters obtained based on the chemical and mineral parameters with those of the RAPD data showed that the groups formed in both cases showed different patterns of relationships among the samples. Broader range of diversity might be due to the out breeding behavior of C. polygonoides and indicates the good adaptability of the plants in the region studied. However, low diversity observed in the Bikaner province is alarming and suggests that anthropogenic activities leading to heavy population disturbances can affect the genetic composition of the species in a considerable way.

1687 downloads

11.

Recovery of hydrocarbon liquid from waste high density polyethylene by thermal pyrolysis
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Kumar, Sachin

; Singh, R. K.

Brazilian Journal of Chemical Engineering

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dec 2011, Volume 28 N. 4 Pages 659 - 667

Abstract: En | Text: En | PDF: En

Thermal degradation of waste plastics in an inert atmosphere has been regarded as a productive method, because this process can convert waste plastics into hydrocarbons that can be used either as fuels or as a source of chemicals. In this work, waste high-density polyethylene (HDPE) plastic was chosen as the material for pyrolysis. A simple pyrolysis reactor system has been used to pyrolyse waste HDPE with the objective of optimizing the liquid product yield at a temperature range of 400ºC to 550ºC. Results of pyrolysis experiments showed that, at a temperature of 450ºC and below, the major product of the pyrolysis was oily liquid which became a viscous liquid or waxy solid at temperatures above 475ºC. The yield of the liquid fraction obtained increased with the residence time for waste HDPE. The liquid fractions obtained were analyzed for composition using FTIR and GC-MS. The physical properties of the pyrolytic oil show the presence of a mixture of different fuel fractions such as gasoline, kerosene and diesel in the oil.

23940 downloads

12.

Genetic analysis of scattered populations of the Indian eri silkworm, Samia cynthia ricini Donovan: differentiation of subpopulations
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Pradeep, Appukuttannair R.

; Jingade, Anuradha H.

; Singh, Choba K.

; Awasthi, Aravind K.

; Kumar, Vikas

; Rao, Guruprasad C.

; Prakash, N.B. Vijaya

Genetics and Molecular Biology

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2011, Volume 34 N. 3 Pages 502 - 510

Abstract: En | Text: En | PDF: En

Deforestation and exploitation has led to the fragmentation of habitats and scattering of populations of the economically important eri silkworm, Samia cynthia ricini, in north-east India. Genetic analysis of 15 eri populations, using ISSR markers, showed 98% inter-population, and 23% to 58% intra-population polymorphism. Nei's genetic distance between populations increased significantly with altitude (R² = 0.71) and geographic distance (R² = 0.78). On the dendrogram, the lower and upper Assam populations were clustered separately, with intermediate grouping of those from Barpathar and Chuchuyimlang, consistent with geographical distribution. The Nei's gene diversity index was 0.350 in total populations and 0.121 in subpopulations. The genetic differentiation estimate (Gst) was 0.276 among scattered populations. Neutrality tests showed deviation of 118 loci from Hardy-Weinberg equilibrium. The number of loci that deviated from neutrality increased with altitude (R² = 0.63). Test of linkage disequilibrium showed greater contribution of variance among eri subpopulations to total variance. D'2IS exceeded D'2ST, showed significant contribution of random genetic drift to the increase in variance of disequilibrium in subpopulations. In the Lakhimpur population, the peripheral part was separated from the core by a genetic distance of 0.260. Patchy habitats promoted low genetic variability, high linkage disequilibrium and colonization by new subpopulations. Increased gene flow and habitat-area expansion are required to maintain higher genetic variability and conservation of the original S. c. ricini gene pool.

2714 downloads

13.

Histological Changes in Ovaries of Mice Exposed to Butea monosperma: Preliminary Study
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Gupta, Neelam

; Singh, Gajendra

; Singh, S. M

; Reddy, K. R. C

International Journal of Morphology

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dec 2010, Volume 28 N. 4 Pages 1309 - 1314

Abstract: En Es | Text: En Es | PDF: En | PDF: Es

In Ayurvedic practice Butea monosperma (Palash) is in clinical use for hundreds of years as a contraceptive. Seeds of Butea monosperma are also used as an anthelmitic (Ansani et al., 1979) and antimicrobial (Avirutnant & Pongpan, 1983). Butea monosperma (Fabaceae family) locally known as Palash (Dhak) if given for 3 consecutive days acts as an antifertility agent for which it has been is traditionally used since time immemorial. The objective of the present study was to search the effect of Butea monosperma seeds on the ovary of mice. Observations in the present study were massive degeneration of ova in almost all the follicles, irrespective of the stage of their development. The ova from treated animals showed different stages of necrotic process. Moreover, the arrangement of follicular cells was also disturbed. The Palash seeds in the form of powder when administered orally with distilled water, according to the body weight i.e.2g/Kg, of female mice, for three consecutive days showed notable changes in ovaries. The animals were sacrificed on day next to the last day of treatment and ovaries were extirpated. Ovaries studied histologically after Haematoxylin & Eosin staining showed most of the follicle in immature state with undefined nucleus and nucleoli in the ovum. Others showed degenerative changes in the ovum. Follicles had lost their normal shape and arrangement and organization of granulosa cells. It was conspicuous to find that almost all follicles including graafian follicles of treated ovaries were undergoing degenerative changes simultaneously. The rate of apoptosis in the granulosa cells when studied was found increased in treated cases as compared with control. The study suggests that the disintegration of ova in the ovaries is a specific effect of Butea monosperma seed administration.

En la práctica Ayurvédica Butea monosperma (Palash) se encuentra en uso clínico durante cientos de años como método anticonceptivo. Semillas de Butea monosperma también se utilizan como un antihemético y antimicrobiano. Butea monosperma (familia Fabaceae) conocida localmente como Palash (Dhak) si se administra durante 3 días consecutivos actúa como un agente anticonceptivo que se utiliza tradicionalmente desde tiempos inmemoriales. El objetivo del presente estudio fue buscar el efecto de las semillas de Butea monosperma en ovarios de ratones.Se obsevó degeneración masiva de los óvulos en casi todos los folículos, independientemente de la fase de su desarrollo. Los óvulos de los animales tratados mostraron las diferentes etapas del proceso necrótico. Por otra parte, la disposición de las células foliculares se mostró alterada. El polvo de semillas de Palash, cuando se administra a los ratones, por vía oral en agua destilada, i.e. 2g/Kg peso corporal, durante tres días produce cambios en los ovarios. Los animales se sacrificaron al día siguiente terminado el tratamiento y fueron extirpados los ovarios. Los ovarios se estudiaron histológicamente con HE mostrándose la mayoría de los folículos en estado inmaduro, con núcleo definido y nucléolos en el óvulo. Otros mostraron cambios degenerativos en los óvulos. Los folículos habían perdido su forma normal y la disposición y organización de células de la granulosa. Se encontró que casi todos los folículos incluyendo los folículos mostraban cambios degenerativos de manera simultánea. En los casos tratados, la tasa de apoptosis en las células de la granulosa estaba aumentada, en comparación con el grupo control. El estudio sugiere que la desintegración de los óvulos en los ovarios es un efecto específico de la administración de las semillas de Butea monosperma.

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14.

Synthesis and characterization of rice husk silica, silica-carbon composite and H3PO4 activated silica
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Singh, D.

; Kumar, R.

; Kumar, A.

; Rai, K. N.

Cerâmica

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jun 2008, Volume 54 N. 330 Pages 203 - 212

Abstract: Pt En | Text: Pt En | PDF: Pt | PDF: En

A síntese e a caracterização de nanosílica obtida da palha de arroz, compósitos nanosílica-carbono e cinza de sílica ativada com ácido fosfórico são apresentadas. Esses materiais foram produzidos pela queima de palha de arroz ao ar, em hidrogênio e por ativação da cinza da palha de arroz com ácido fosfórico, respectivamente. Análise de difração de raios X destes produtos mostram aumento da largura dos picos (amorfização) com a diminuição da temperatura de queima. A sílica da palha de arroz ativada transforma a produto cristalino quando a temperatura é maior que 1000 ºC. A variação da área de superfície específica e do volume de poro com a temperatura de queima mostra comportamento diferente quando a queima é feita ao ar ou sob hidrogênio. A energia de ativação associada com a mudança na área de superfície específica após queima ao ar e sob hidrogênio também foi estudada. A taxa de variação da área de superfície específica com a temperatura mostra diferente tendência. A avaliação dos produtos foi feita por meio da capacidade de descolorimento em soluções de melaço e de iodo. Foi verificado que a capacidade de absorção dos produtos é maior para a sílica ativada e menor para a cinza hidrogenada.

This paper discusses synthesis and characterization of (i) rice husk based nanosilica, (ii) nanosilica carbon composite granules and (iii) phosphoric acid activated ash silica. These have been produced by burning husk in air, charring husk in hydrogen and activating husk silica with H3PO4 respectively. X-ray diffraction studies of these products reveal increasing peak width (amorphosity) with decreasing burning temperature. The activated rice husk silica transforms to crystalline product when burnt above 1000 ºC. The variation of surface area and pore volume with burning temperature show different behavior for air fired and hydrogen charred products. Activation energy associated with change in surface area for air fired and hydrogen charred samples have also been studied. Rate of variation in surface area with temperature indicate different trend. The validations of these products have been evaluated by decolorizing capacity of standard molasses and iodine solution. The adsorptive powers of these products have been found to be highest for activated silica and lowest for hydrogenated ash.

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15.

Radio detection of cosmic rays with LOPES (LOPES Collaboration)
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Grupen, C.

; Apel, W.D.

; Asch, T.

; Badea, A.F.

; Bähren, L.

; Bekk, K.

; Bercuci, A.

; Bertaina, M.

; Biermann, P.L.

; Blümer, J.

; Bozdog, H.

; Brancus, I.M.

; Buitink, S.

; Brüggemann, M.

; Buchholz, P.

; Butcher, H.

; Chiavassa, A.

; Cossavella, F.

; Daumiller, K.

; Di Pierro, F.

; Doll, P.

; Engel, R.

; Falcke, H.

; Gemmeke, H.

; Ghia, P.L.

; Glasstetter, R.

; Haungs, A.

; Heck, D.

; Hörandel, J.R.

; Horneffer, A.

; Huege, T.

; Kampert, K.H.

; Kolotaev, Y.

; Krömer, O.

; Kuijpers, J.

; Lafebre, S.

; Mathes, H.J.

; Mayer, H.J.

; Meurer, C.

; Milke, J.

; Mitrica, B.

; Morello, C.

; Navarra, G.

; Nehls, S.

; Nigl, A.

; Obenland, R.

; Oehlschläger, J.

; Ostapchenko, S.

; Over, S.

; Petcu, M.

; Petrovic, J.

; Pierog, T.

; Plewnia, S.

; Rebel, H.

; Roth, M.

; Schieler, H.

; Sima, O.

; Singh, K.

; Stümpert, M.

; Toma, G.

; Trinchero, G.C.

; Ulrich, H.

; van Buren, J.

; Walkowiak, W.

; Weindl, A.

; Wochele, J.

; Zabierowski, J.

; Zensus, J.A.

; Zimmermann, D.

Brazilian Journal of Physics

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dec 2006, Volume 36 N. 4a Pages 1157 - 1164

Abstract: En | Text: En | PDF: En

Data taken with a radio antenna array in combination with the ground-level air shower experiment KASCADE-Grande at the Forschungszentrum Karlsruhe open up the possibility to measure large extensive air showers with this new technique. The pulse height of the observed radio signals scales with the primary energy of the particles initiating the air shower. The dependence of the radio signal on the angle of the shower axis with respect to the Earth's geomagnetic field and the coherence of the radiation suggest that the radio signal generation is due to the geosynchrotron mechanism.

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