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Transport and Gas Sensing Properties of Cadmium Titanate Nanofibers

Thesis Info

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Author

Imran, Zahid

Program

PhD

Institute

Pakistan Institute of Engineering and Applied Sciences

City

Islamabad

Province

Islamabad

Country

Pakistan

Thesis Completing Year

2014

Thesis Completion Status

Completed

Subject

Applied Sciences

Language

English

Link

http://prr.hec.gov.pk/jspui/bitstream/123456789/2083/1/2360S.pdf

Added

2021-02-17 19:49:13

Modified

2024-03-24 20:25:49

ARI ID

1676727631348

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In this work AC & DC transport and sensing properties of cadmium titanate (CdTiO3) nanofibers have been investigated. Study of AC transport properties were explored using temperature dependent impedance spectroscopy. DC transport measurements were carried out using temperature dependent current-voltage (I-V) characterization. Cadmium titanate/polyvinyl-pyrrolidone composite nanofibers were prepared using an electrospinning technique. When temperature increased from 600 °C to 1200 °C the phase changes in CdTiO3 nanofibers were observed. The nanofibers annealed at 600 °C had ilmenite phase with a very small amount of CdO. Pure ilmenite phase was obtained at 950 °C. Annealing at 1000 °C yielded pure perovskite phase. Further increase in annealing temperature resulted in rutile TiO2 phase. The average diameters of nanofibers annealed at 600 °C and 1000 °C were found to be ~150 nm and ~600 nm, respectively. The length of nanofibers was ~100 μm. Analysis of frequency dependent AC conductivity in ilmenite phase revealed correlated barrier hoping (CBH) conduction from 318 K – 498 K. In perovskite phase, thermally activated small polaron hopping (SPH) conduction played dominant role from 320 K – 420 K. In DC transport, Ohmic behavior was observed at low voltages followed by space charge limited current (SCLC) with traps at higher voltages at all temperatures (200 K – 420 K). Humidity sensing characteristics of ilmenite phase were investigated. Fast response time and recovery time of 4 seconds and 6 seconds was observed, respectively. The sensor was highly sensitive and showed a reversible response with small hysteresis of less than 7%. Long term stability of the sensor was confirmed during 30 days test. Oxygen sensing using ilmenite and perovskite phase CdTiO3 nanofibers was also performed. The gas response of the ilmenite nanofibers sensor to oxygen gas was twice as high as that of the perovskite phase. The response and recovery times were 120 seconds and 23 seconds, respectively for ilmenite phase, whereas response and recovery times were 156 seconds and 50 seconds, respectively for the perovskite phase. Better oxygen sensing characteristics of ilmenite phase were attributed to large surface area ~9.41 m2/g and porosity.
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پرنس کائتانی

پرنس کائتانی ؍ پروفیسر گویدی ؍ پروفیسر اسنوک ہرخردنئے
امسال مرحوم مارما ڈیوک پکتھال کے علاوہ ن کو ہم سب جانتے تھے، کئی نامور مستشرقین نے وفات پائی، اٹلی کے پرنس کائتانی اور پروفیسر گویدی اور لائڈن کے پروفیسر اسنوک ہر خردنئے نے امسال ہماری دنیا کو الوداع کیا، پرنس کائتانی تاریخ اسلام کے عالم اور گویدی عربوں کے ریاضیات اور جغرافیہ کے ماہر اور اسنوک ہر خردنئے ’محمڈنزم‘ نامی کتاب کے مصنف ہیں جس کو انھوں نے خطبہ کی صورت میں امریکہ کی ’’مجلسِ تاریخِ مذاہب‘‘ میں پیش کیا تھا اور بھی دوسری کتابیں اور مضامین ان کے قلم سے نکلے تھے۔ (سید سلیمان ندوی، اکتوبر ۱۹۳۶ء)

Comparative Effect Of Tetrapack Juices And Fresh Fruit Juices On Blood Glucose Level Among Healthy Individuals Comparative Effect of Juices on Blood Glucose Level

Uses of tetra pack juices enhances the risk of diabetes and obesity. People were unaware of impact of fresh fruit juices on health. Objective: To compare the effect of tetra pack juices and fresh fruit juices on blood glucoselevels among healthy individuals Methods: 10 participants were selected using an internationalstandard Glycemic Index (GI) test protocol. After getting their fasting blood sample theywereinstructed to consume all the juice served in a period of 5 min. Further blood samples were takenat different intervals of time that is 0, 30, 60, 90, 120 and 150 minutes after consumption. Participants wereremained sedentaryduring each session. Blood was obtained by finger-prick and tested by the glucometer. Results: The glycemic index of Apple juice Nestle has the glycemic index of 95.87, Orangejuice Nestle has the GI value 93.78, Apple juice fresh has the GI value of 92.17 and Orangejuice fresh has the glycemic index value of 99.07, respectively Conclusions: Detailed study of glycemic index of tetrapack juices (Nestle Apple and Orangejuice) and fresh fruit juices (Apple and Orange juice) showed similar impact on the blood glucose level of healthy individual. In the study, both types of juices were found to be equally hyperglycemic (GI 70+) causing a fast rise in blood-sugarlevels, hence should not be given to diabetic patients

Exogenous Use of Some Potential Organic Osmolytes in Enhancing Drought Tolerance in Maize Zae Mays L.

In the present study, a series of experiments were conducted in the Botanic Gardens of the Department of Botany, University of Agriculture, Faisalabad to test the relative effectivness of the three osmolytes in alleviating the adverse effects of drought stress on maize plants. The osmolytes were applied through different modes at different growth stages of maize plants under non-stress or water stress conditions. In the first experiment, varying levels (0, 30 and 60 mM) of each of the osmolytes were applied as foliar spray and presowing treatment of seeds of two cultivars (Agaiti-2002 and EV-1098). The plants raised from the treated seeds were grown in plastic pots filled with sandy loam soil under greenhouse conditions. After two weeks of the imposition of water stress, different levels (0, 30, and 60 mM) of each of the osmolytes were exogenously applied as a foliar spray to maize plants at the seedling, vegetative or both seedling and vegetative stages when grown under non-stress or water stress conditions (60% field capacity). Tween-20 (0.1%) was used as a surfactant for foliar spray. It was found that 30 mM of GB, or proline or trehalose was the most effective in promoting seedling growth under water stress conditions. However, GB and proline were more effective than trehalose in ameliorating the adverse effects of water stress on growth of both maize cultivars. It was found that effective concentration of exogenously applied osmolytes through seed soaking or through foliar application is 30 mM. During the 2 nd experiment the effective concentrations of these osmolytes (GB, proline and trehalose) as estimated from the 1 st experiment were applied as pre-sowing seed treatment and as foliar spray at different growth stages (seedling, vegetative and seedling+vegetative) as in the 1 st experiment to observe their effects in inducing drought tolerance maize plants in relation to various physiological and biochemical attributes. Exogenous application of osmolytes as presowing seed treatment or as foliar spray at different growth stages increased the photosynthetic rate of the plants of both cultivars that was associated with stomatal as well as non-stomatal factors. Plant water status as reflected by leaf water potential and leaf relative water content (RWC) was improved by the exogenously applied organic solutes and it was associated with leaf osmotic potential, endogenous GB and proline, which suggests the role of these osmolytes in osmotic adjustment. Exogenous application of these osmolytes increased the accumulation of nutrients particularly K, and shoot nutrient use efficiency in maize plants under water stress conditions. Exogenous application of compatible solutes enhanced the antioxidant capacity of drought stressed maize plants by increasing the activities of antioxidant enzymes (SOD, POD and CAT) and non-enzymatic compounds (phenolics, tocopherols and ascorbic acid) which is evident from the reduced MDA contents determined in the present study. Exogenously applied different osmolytes enhanced the seed and seed oil quality of both maize cultivars. Seed sugar, seed oil, seed protein, seed macro- and micronutriets increased due to exogenous application of these osmolytes. Moreover, improved seed oil quality was associated with enhanced oil unsaturation in terms of increased in oleic and linoleic acid contents as well as the oil lipophilic antioxidants (tocopherols, phenolics, flavonoids) which in-turn enhanced the oil antioxidant activity. Overall, exogenously applied different compatible solutes as a seed treatment or foliar application improved growth and yield of maize pants. Osmolyte-induced enhancement in growth and yield under water stress conditions was associated with increase in net CO 2 assimilation rate, plant water status, antioxidant capacity and nutrient accumulation, particularly of K. However, further studies are required to explicitly elucidate the mechanism of organic osmolytes influx through epidermis and target enzymes or metabolites to induce stress tolerance in plants. Moreover, further studies are important to work out cost-benefit ratios of the use of different organic osmolytes used in this study. This information will be undoubtedly beneficial for stakeholders, particularly the farmers.