Simulation for Neutron Transport in PWR Reactor Moderator and Evaluation for Proper Thickness of Light Water Reflector

Monte Carlo calculation method can be used for resolving particle transport in matter, and particularly the transport of neutrons in environment of reactor core. The method has become more efficiently because of high accuracy of updated nuclear data and fast development of advanced super-computing system. In this work, we would like to present calculations for kinematical characteristics of neutron transport in a typical configuration of the pressurized water reactor (PWR) fuel assembly based on the Monte-Carlo simulation method. We concentrate in two main results: (1) neutron energy spectrum at fuel rod and (2) optimal thickness of light water reflector

Theoretical and Experimental Studies of Thermodynamic Properties, Anharmonic Effects and Structural Determination of HCP Crystals

Thermodynamic properties, anharmonic effects and structural determination of hcp crystals have been studied based on their theoretical and experimental Debye-Waller factor presented in terms of cumulant expansion up to the third order in X-ray absorption fine structure (XAFS). The results have been achieved based on the present advanced method using that the calculations and measurements are necessary only for the second cumulants from which all the considered XAFS quantities have been provided. This advantage has resulted based on the description of XAFS quantities in terms of second cumulants. The many-body effects included in the present one-dimensional model have been taken into account based on the first shell near neighbor contributions to the vibration between absorber and backscaterer atoms. Morse potential is assumed to describe the single-pair atomic interaction included in the anharmonic interatomic effective potential. Numerical and experimental results for Zn in hcp phase obtained by the present advanced method are found to be in good agreement with one another and with those measured at HASYLAB (DESY, Germany)

HYDROGEN-PLASMA-TREATED NANO TIO2 FOR PHOTOCATALYTIC OXIDATION OF VOCS IN AIR STREAM

Unlike water treatment processes, the photocatalytic oxidation of VOCs in air stream exhibits many challenges. This study will develop the hydrogen-plasma-treated TiO2 with improvement in photocatalytic activity. The hydrogen-plasma-treatment was carried out in the non-thermal atmospheric pressure reactor at room temperature or above. The catalysts were prepared and analyzed by advanced techniques such as X-ray diffraction (XRD), scanning electro-microscopy (SEM) and transmission electro-microscopy (TEM). The photocatalytic activity of the catalyst has been investigated under UV light with various reaction conditions such as different initial toluene/formaldehyde concentrations and water content. Significantly, the conversion of toluene by a plasma-treated sample was 1.5 times higher than the bare TiO2 in a similar reaction condition

Footprint of increased anthropogenic disturbance elevates termite pest status

Tese de doutoramento em Ciências Farmacêuticas, na especialidade de Farmacognosia e Fitoquímica, apresentada à Faculdade de Farmácia da Universidade de CoimbraCymbopogon citratus (DC). Stapf (Poaceae), commonly known as lemongrass, is a tropical perennial shrub originated from the Southeast Asia. This plant is reported to possess antifungal, insecticidal, anti-diabetic, anti-septic, anti-mutagenic, anti-carcinogenic activities as well as anti-inflammatory. In fact, aqueous extracts of dried leaves are used all over the year in folk medicine for the treatment of peptic ulcers and inflammatory conditions. Recently, some phenolic compounds, such as luteolin and apigenin glycosides and condensed tannins, were identified and related to both antioxidant and anti-inflammatory properties. The purposes of this work were to i) validate an analytical method for quantification of phenolic compounds of C. citratus; ii) study the influence of harvest time and plant quality on the phenolic composition and antioxidant activity; iii) characterize the tannins; iv) validate the traditional uses of lemongrass infusion as anti-inflammatory in vivo; v) obtain a topical formulation to evaluate the phenolic compounds permeation and their anti-inflammatory activity; vi) trace the pharmacokinetic profile of the main phenolic compounds in rats. Three different extracts: infusion (CcI), 50% aqueous ethanol (CcM50%) and ethanol (CcM100%) extracts were prepared and a simple and efficient RP-HPLC-PDA method was successfully validated for simultaneous identification and quantification of phenolic acids and flavonoids. Infusions were also obtained from different harvest dates (April, June, July, August and September) and quality grades (High, Medium and Low). It was verified that the content on polyphenols and the antioxidant capacity of CcI is strongly related with the quality of the plant. The total phenols assay showed a substantial loss from August to September. It was possible to find out the best month to harvest the plant to get the most of each phenolic group: April and June for hydroxycinnamic acids; June and September for flavonoids; June, July and August for tannins. Regardless the group of phenolic compound addressed, its content was always inversely proportional to the degree of leaves ageing. For all tested oxidant species, the high-quality samples exhibited the best antioxidant results. CcI was fractionated by column chromatography and polyphenol-rich fractions, namely phenolic acids (CcPA), flavonoids (CcF) and tannins (CcT) were obtained. CcT was characterized by HPLC-PDA-ESI/MSn, revealing the presence of proanthocyanidin hetero-dimers, along with some common procyanidin dimers. These hetero-dimeric flavan structures have been described for the first time in lemongrass and consist of apigeniflavan or luteoliflavan units linked to a flavanone, either naringenin or eriodictyol, and may occur as aglycone or glycosylated forms. For the in vivo assays, CcI, CcF and CcT were tested. CcI administered before and after ethanol stimulus, significantly reduced the incidence and severity of gastric lesions and, consequently, the ulcer index, corroborating the traditional medicinal use of this plant to ameliorate gastritis and/or peptic ulcers symptoms. On the other hand, CcI, CcF and CcT were orally administered to rats, in order to evaluate the anti-inflammatory effect at the carrageenan-induced paw edema assay. The observed effect by CcI (68.24 mg/kg), 82.30% of edema inhibition, was very similar to that obtained by the reference NSAID used (diclofenac, 10 mg/kg), 84.00%. On the other hand, flavonoid (7.42 mg/kg) and the tannin-rich (5.96 mg/kg) fractions significantly contributed for the anti-inflammatory activity on the edema volume (59 and 61%, respectively). The topical anti-inflammatory activity of CcI was also addressed. The results suggest that flavonoids, mainly, luteolin 7-O-neohesperidoside, cassiaoccidentalin B, carlinoside and cynaroside, may contribute to the topical anti-inflammatory effect. CcF (0.6%), CcT (0.3%) and CcF+CcT (0.66%+0.34%) topical formulations were also tested, and the results obtained suggest that tannins and flavonoids also possess a significant activity and that a synergistic mechanism of action may occur. In fact, edema inhibitions of 43%, 47% and 59% were respectively verified, being CcF+CcT effect very close to that of 1% diclofenac (65.9%). Pharmacokinetic analysis was performed in plasma, liver and kidney and showed that the compounds present in CcI are not detected in vivo after a single-dose oral administration. In contrary, the metabolites, luteolin 7-O-glucuronide and luteolin 3’-O-sulfate, present at the highest bioavailability, are probably the main responsible for the anti-inflammatory activity previously reported. In conclusion, this work has developed a method to quantify the phenolic compounds contained in C. citratus; pointed the importance of harvesting and storing the plant material, in order to take the maximum advantages from the phenolic compounds use; and demonstrated, in safe doses, its anti-inflammatory activity, using an in vivo approach, which supports the traditional use of lemongrass infusion. Furthermore, C. citratus leaves flavonoids and tannins were highlighted as bioactive compounds, encouraging the development of new anti-inflammatory drugs or nutraceuticals

Enantioselective separation of ofloxacin by ligand exchange chromatography

A ligand exchange HPLC method for enantioseparation of ofloxacin enantiomers was developed by a using C8 stationary phase. Chromatographic separation was performed on a Zorbax-300SB-C8 column eluted with the mobile phase consisting of 15 % methanol in water containing 10mM phenylalanin and 5 mM CuSO4 at flow rate of 0.8 mL/min. The method was simple, rapid and suitable for routine analytical studies of ofloxacin enantiomers

Physicochemical and Biological Characteristics of Shrimp Pond Sludge in the Thua Thien Hue Province, Vietnam

This study has been carried out to analyze the physical and biological indicators of shrimp pond sludge samples obtained from the Phu Vang and Phu Loc districts of the Thua Thien Hue Province, Vietnam. All standard methodologies have been used to analyze the selected parameters like pH, organic carbon, total nitrogen, total phosphate, and microbial density.  The results of the study revealed that the sludge was characterized by a neutral to alkaline pH (6.9 - 7.5), and the total organic carbon content was in the range of 103.8–173.5 mg/kg. The sludge was rich in organic matter (17.8–29.9%), total nitrogen (13.5–32.5 g/kg), and total phosphate (7.9-20.1 g/kg). Further, in the case of the microbial density of pathogenic microorganisms, the density of total bacteria, coliform, E.coli, Salmonella spp., Vibrio spp., and Clostridium spp. was also estimated at two opposing weather conditions (spring, February to March; summer, June to July). The microbial community increased rapidly during the cool spring months. The total bacterial levels were recorded as 8.77 log10 CFU/mL in the Phu Loc district and 9.11 log10 CFU/mL in the Phu Vang district. The levels decreased during the hot summer months, and the level of total bacteria, Coliform, E.coli, Salmonella spp., and Vibrio was reported 2.57, 1.49, 1.06, 0.56, and l2.54 log10 CFU/mL respectively from the Phu Loc district of Vietnam. The results obtained using the anaerobic decomposition model showed that on the 60th day, the amount of CH4 generated at the high output value for the Phu Vang district was 22385 ppm. The results reported here revealed that CH4 gas can be potentially produced from shrimp waste sludge in this province