Showing papers by "Government College published in 2002"

Studies on antioxidant activity of pomegranate (Punica granatum) peel extract using in vivo models.

Abstract: Pomegranate (Punica granatum) peel extracts have been shown to possess significant antioxidant activity in various in vitro models. Dried pomegranate peels were powdered and extracted with methanol for 4 h. The dried methanolic extract was fed to albino rats of the Wistar strain, followed by carbon tetrachloride (CCl4), and the levels of various enzymes, such as catalase, peroxidase, and superoxide dismutase (SOD), and lipid peroxidation were studied. Treatment of rats with a single dose of CCl4 at 2.0 g/kg of body weight decreases the levels of catalase, SOD, and peroxidase by 81, 49, and 89% respectively, whereas the lipid peroxidation value increased nearly 3-fold. Pretreatment of the rats with a methanolic extract of pomegranate peel at 50 mg/kg (in terms of catechin equivalents) followed by CCl4 treatment causes preservation of catalase, peroxidase, and SOD to values comparable with control values, wheres lipid peroxidation was brought back by 54% as compared to control. Histopathological studies of the liver were also carried out to determine the hepatoprotection effect exhibited by the pomegranate peel extract against the toxic effects of CCl4. Histopathological studies of the liver of different groups also support the protective effects exhibited by the MeOH extract of pomegranate peel by restoring the normal hepatic architecture.

Antioxidant Activities of Grape (Vitis vinifera) Pomace Extracts

Abstract: Antioxidant-rich fractions were extracted from grape (Vitis vinifera) pomace using ethyl acetate, methanol, and water. The extracts were screened for their potential as antioxidants in different models. The ethyl acetate, methanol, and water extracts showed 76, 87.1, and 21.7% antioxidant activities at 100 ppm, respectively, using the 1,1-diphenyl-2-picrylhydrazyl model system. As the methanol extract of grape pomace showed maximum antioxidant activity among all of the extracts, it was selected to determine its effect on lipid peroxidation, hydroxyl radical scavenging activity, and human low-density lipoprotein (LDL) oxidation. The methanol extract showed 71.7, 73.6, and 91.2% inhibition using the thiobarbituric acid method, hydroxyl radical scavenging activity, and LDL oxidation, respectively, at 200 ppm. Treatment of albino rats of the Wistar strain with a single dose of CCl(4) at 1.25 mL/kg of body weight decreases the activities of catalase, superoxide dismutase (SOD), and peroxidase by 81, 49, and 89%, respectively, whereas the lipid peroxidation value increased nearly 3-fold. Pretreatment of the rats with the methanolic extract of grape pomace at 50 mg/kg (in terms of catechin equivalents) followed by CCl(4) treatment causes restoration of catalase, SOD, and peroxidase by 43.6, 73.2, and 54%, respectively, as compared with control, whereas lipid peroxidation was restored to values comparable with the control. Histopathological studies of the liver of different groups also support the protective effects exhibited by the methanol extract of grape pomace by restoring the normal hepatic architecture. Owing to this property, the studies on grape pomace can be further extended to exploit its possible application for the preservation of food products as well as a health supplement and neutraceutical.

Soft X-Ray Emission in the (1.0-1.5 keV) Window with Nitrogen Filling in a Low Energy Plasma Focus

Abstract: A study of soft X-ray emission in the 1.0–1.5 keV energy range from a low energy (1.15 kJ) plasma focus has been conducted. X-rays are detected with the combination of Quantrad Si PIN-diodes masked with Al (50 μm), Mg (100 μm) and Ni (17.5 μm) filters and with a pinhole camera. The X-ray flux is found to be measurable within the pressure range of 0.1–1.0 mbar nitrogen. In the 1.0–1.3 keV and 1.0–1.5 keV windows, the X-ray yield in 4π-geometry is 1.03 J and 14.0-J, respectively, at a filling pressure of 0.25 mbar and the corresponding efficiencies are 0.04% and 1.22%. The total X-ray emission in 4π-geometry is 21.8 J, which corresponds to the system efficiency of about 1.9%. The X-ray emission is found dominantly as a result of the interaction of energetic electrons in the current sheath with the anode tip. Images recorded by the pinhole camera confirm the emission of X-rays from the tip of the anode.

Food Habits and Nutrient Density of Diets of Pakistani Children Living in Different Urban and Rural Settings

Abstract: Food habits and nutrient density of diets of six groups of rural and urban school children aged 10-12 years were compared. Data were collected from three-day food records. In the UK, data were collected during October-November 1994 and in Pakistan during April-May 1995. Based on the apparent level of urbanism, the six groups were arbitrarily assigned urbanization rank 1-6. Patterns of their food and intake of nutrients were different from each other in various aspects and were not always associated with the apparent level of urbanism of the group. With urbanization, the intake of fat and sugar increased steadily. The intake of carbohydrate, fibre, riboflavin, and vitamin E decreased with urbanization. The intake of vitamin C, vitamin B12, and folates was higher among group 4, 5, and 6 than other groups. Due to various factors, in terms of micronutrient density, diets of various urban groups could have more differences than similarities. While these differences point toward the need for comprehensive nutrition education and community nutrition surveys, they also indicate the possibility of having healthy diets in urban settings.

Study of the effect of thermal annealing on the optical and electrical properties of vacuum evaporated amorphous thin films in the system Ge20Te80-xBix

Abstract: We systematically studied the effect of thermal annealing on the optical and electrical properties of amorphous semiconducting thin films in the system Ge20Te80−xBix (x = 0, 0.19, 2.93, 7.35) prepared by flash evaporation in a vacuum of 1 × 10−6 Torr. The films are characterized by x-ray diffraction (XRD) and electron probe micro analysis. The annealing temperature is kept at 150 °C, 180 °C and 220 °C. No crystallization of the thin films is achieved on annealing up to the temperature of 150 °C. At a higher temperature of annealing, microcrystals of Te, Bi2Te3, Ge–Te, etc, are observed along with an amorphous phase as indicated by XRD analysis. The fundamental optical absorption edge and reflection spectra of as-prepared and annealed films are determined. Optical interband transitions are observed for various films (as-prepared and annealed). The presence of crystalline Bi2Te3 in films annealed at 220 °C is also supported by the reflection spectrum. The optical energy gap (Eg), the slope parameter (Δ) of the absorption edge and the tailing parameter (B−1) of the energy band tails are computed from the optical data. The dc electrical conductivity (σdc) of various films is studied in the temperature range of 150–450 K. We observe that two types of conduction take place: conduction through extended states in the higher temperature region, and conduction through localized states in the band tails and at the Fermi level by the hopping process assisted by phonons at lower temperatures. The data at higher temperatures have been fitted with the expression σdc = σ0exp(−ΔE/kT) and the electrical parameters, ΔE and σ0, are also determined. It is observed that the bismuth concentration and annealing temperature dependences of the optical and electrical parameters are different in the two regions of compositions, x ≤ 2.93 and x > 2.93, indicating structural differences in the two sets of compositions. It is pointed out that the bulk form of these amorphous semiconductors exhibits a carrier sign reversal at a bismuth concentration of about 3.5 at%. However, the thin-film form of these amorphous semiconductors does not show such a carrier sign reversal in the electrical transport.

Urbanisation and activity pattern of south Asian children.

Abstract: OBJECTIVE To compare the physical activity level and total energy expenditure of 10-12 year old school children living at different levels of urbanization. METHOD All the participating children kept a three-day record of their activities, for every fifteen-minutes, in specially designed diaries. Activities were grouped according to intensity that was determined on the basis of Physical Activity Ratio (PAR). After calculating the average time spent in a day, in activities of varying intensity, overall Physical Activity Level (PAL) of each subject was calculated by factorization method. After measuring bodyweight using a standard equation Basal Metabolic Rate (BMR) of the subjects was calculated. Total Energy Expenditure (TEE) was assessed on the basis of PAL and BMR of each child. SUBJECTS Physical activity level of six groups of 10-12 year old children, representing various urbanization categories, was studied. Three groups of children were recruited from Punjab, Pakistan: rural, middle income urban and high income urban, and they were assigned urbanization rank (UR) 1, 2 and 3. Another three groups of children were recruited from Slough, UK: British Pakistani, British Indian, and British Caucasian and they were assigned urbanization rank 4, 5 and 6 respectively. RESULTS Physical activity level decreased significantly with the urbanization rank only among girls of Pakistani origin (UR 1-4). Pattern of gender differences in activity level was different in rural and urban children. Rural girls were slightly more active than rural boys, whereas in urban areas boys were significantly more active than girls. Because of lower bodyweight the less urbanized children in spite of having higher PAL had a lower mean TEE as compared to the more urbanized groups. CONCLUSION The activity level of rural children having access to formal education and television could not be expected to be very different from their urban counterparts. Inactivity of urban girls needs particular attention. Because of lower caloric requirements, on similar diets, less urbanized groups may succumb to overweight more easily than the urbanized groups. Participation in active games may present a substitute to decreased involvement in moderately active work and play activities.

Quantitative property-property relationship (QPPR) approach in predicting flotation efficiency of chelating agents as mineral collectors

Abstract: The QPPR approach has been used to model cupferrons as mineral collectors. Separation efficiencies (Es) of these chelating agents have been correlated with property parameters namely, log P , log K oc , substituent-constant † , Mullikan and ESP derived charges using multiple regression analysis. Es of substituted-cupferrons in the flotation of a uranium ore could be predicted within experimental error either by log P or log K oc and an electronic parameter. However, when a halo , methoxy or phenyl substituent was in para to the chelating group, experimental Es was greater than the predicted values. Inclusion of a Boolean type indicative parameter improved significantly the predictability power. This approach has been extended to 2-aminothiophenols that were used to float a zinc ore and the correlations were found to be reasonably good.

Quantitative Structure-Activity Relationship Study of 2-arylsulfonyl-6-substituted Benzonitriles as Non-nucleoside Reverse Transcriptase Inhibitors of HIV-1

Abstract: The reverse transcriptase inhibition of HIV-1, the most common form of HIV, by non-nucleoside 2-arylsulfonyl-6-substituted benzonitriles is analysed through Fujita-Ban and Hansch approaches. The analyses have helped to ascertain the role of different substituents in explaining the observed inhibitory actions of these compounds. From both approaches it appeared that SO 2 instead of SO or S at X; and NH 2 instead of F at Y (see Figure 1) are advantageous to improving the activity of a compound against HIV-1. This in turn leads to the suggestion that the 2-arylsulfonyl-6-aminobenzonitrile scaffold is the only appropriate structural entity that may further result into potential compounds. Further, the compounds having a OMe substituent at the ortho -position, the bulkier substituents at meta -positions and "no" substituent at para -position of 2-arylsulfonyl moiety are beneficial in raising the activity. The two quantitative structure-activity relationship (QSAR) analyses, differing in parametric approach, th...

Bounds on neutrino mixing with exotic singlet neutrinos

Abstract: We examine the effects of mixing induced non-diagonal light-heavy neutrino weak neutral currents on the amplitude for the process \(v_a \overline v _a \to ZZ\) (with a=e, μ or τ). By imposing constraint that the amplitude should not exceed the perturbative unitarity limit at high energy \(\left( {\sqrt s = \Lambda } \right)\), we obtain bounds on light-heavy neutrino mixing parameter sin2\(\theta _L^{v_a } \) where \(\theta _L^{v_a } \) is the mixing angle. In the case of one heavy neutrino (mass mξ) or mass degenerate heavy neutrinos, for Λ=1 TeV, no bound is obtained for mξ<0.50 TeV. However, sin2\(\theta _L^{v_a } \)≤3.8 × 10−6 for mξ=5 TeV and sin \(\theta _L^{v_a } \)≤6.0 × 10−8 for mξ=10 TeV. For Λ=∞, no constraint is obtained for mξ<0.99 TeV and sin2\(\theta _L^{v_a } \)≤3.8 × 10−2 (for mξ=5 TeV) and sin2\(\theta _L^{v_a } \)≤9.6 × 10−3 (for mξ=10 TeV).

Quantitative structure-activity relationship study on N-(pyridin-4-yl)-(indol-3-yl) alkylamides as antiallergic agents.

Abstract: The antihistamine activity of N-(pyridin-4-yl)-(indol-3-yl) alkylamides has been analyzed using Fujita-Ban and Hansch approaches. The analyses have helped to ascertain the role of different substituents in explaining the antiallergic actions of these analogues. From both approaches it is revealed that the small size substituents at R and R 2 and non-hydrogen bond acceptor substituent at R improve histamine antagonist activity of a compound. Likewise, a small incision such as -CH 2 CONH-serving as the spacer between pyridinyl and indolyl rings and a bigger substituent like 4-FBn at R, are also desirable for inhibitory activity.

Sensitized up-conversion luminescence of Ho3+ in Nd3+-Yb3+-Ho3+ co-doped ZrF4-based glass

Abstract: Up-conversion processes for the blue, green and red emissions were found two-photon phenomenon, known as the cooperative phenomenon. This phenomenon was assisted by Nd3+ → Yb3+ → Ho3+ energy transfer. The strong green emission due to the Ho3+ : (5F4, 5S2)→ 5I8 transitions was observed in Nd3+-Ho3+ co-doped ZrF4-based fluoride glasses under 800 nm excitation. As an attempt to enhance Ho3+ up-conversion luminescences in the Nd3+ – Ho3+ co-doped ZrF4-based glasses, Yb3+ ions were added to the glasses. As a result it was found that, in 800 nm excitation of 60 ZrF4. 30BaF2. (8-x)LaF3. lNdF3. xYbF3. 1HoF3 glasses (x=0 to 7), sensitized up-conversion luminescences are observed at around 490 nm (blue), 545 nm (green), and 650 nm (red), which correspond to the Ho3+ : 5F3 → 5I8, ( 5F4, 5S2)→5I8 and 5F5→ 5I8 transitions respectively. The intensities of the green and red emissions in a 3 mol % YbF3-containing glass were about 50 times stronger than those glasses without YbF3. This is based on sensitization due to Yb3+ ions. In particular, the green emission was extremely strong and the Nd3+-Yb3+-Ho3+ co-doped ZrF4-based glasses have a high possibility of realizing a green up-conversion laser glass. In this paper the up-conversion mechanism in the glasses is discussed in detail.