Morphological, optical and electromagnetic characterization of polybutylene terephthalate/silica nanocomposites

Polybutylene terephthalate (PBT) composites containing 1 %, 3 % and 5 % silica nanoparticles were prepared by melt compounding method. The characteristics of the nanocomposites were investigated by X-ray diffraction (XRD), scanning electron microscopy (SEM), differential scanning calorimetry (DSC), thermal gravimetric analysis (TGA), tensile strength test (TST), reflectance spectroscopy (RS), electromagnetic transition test (ETT) and atomic force microscopy (AFM). XRD method showed successful incorporation of silica into the polymer matrix. SEM and AFM results showed the presence of silica aggregates on the surface of PBT sheets. Thermal analysis results demonstrated some changes in crystallinity of PBT after addition of silica. The PBT/silica nanocomposites were found to have higher electromagnetic reflection compared with the pure PBT. Silica nanoparticle is thus suggested as a good candidate for electromagnetic shielding purposes.     

The role of fruit consumption in the prevention of obesity

Summary

The global obesity epidemic is associated with a sedentary lifestyle and diets rich in high-fat, high-energy foods. The potential role of fruit in preventing overweight and obesity is related to their relatively low energy density, high content of dietary fibre, and associated increasing satiety effect. The physical disruption of fruit is of considerable importance for satiety, as shown in studies in which fruit juices were less satisfying compared to sugar-equivalent intakes of purées and whole fruits. The potential role of fruit in the prevention of overweight and obesity may be connected to the dietary pattern of fruit intake, and with the possibility that fruit intake may substitute for other, more energy-dense foods. The majority of human prospective cohort studies in adults suggest a preventive effect of increased fruit intake on body weight gain; whereas a few studies have suggested the opposite, in the case of fruit juices. Prospective studies on children are few and inconclusive, but suggest associations between fruit intake and body weight that are related to the initial nutritional status. In behavioural intervention studies, subjects are often advised to undergo several changes towards a healthy diet and lifestyle, making it impossible to quantify the specific effect of fruit intake on body weight. In the few available intervention studies in adults, the study period was often too short to allow measures of body weight changes, and studies on overweight or obese subjects may not apply to subjects of normal weight. Intervention studies targeted at school children showed that such schemes can be effective in increasing fruit intake, but a convincing role for increased fruit intake in the prevention of overweight and obesity in children still needs to be established. The present evidence suggests that fruit consumption has a potential role in the prevention of overweight and obesity.     

Polycyclic Aromatic Hydrocarbons in Seawater, Sediment, and Rock Oyster Saccostrea cucullata from the Northern Part of the Persian Gulf (Bushehr Province)

The concentration of polycyclic aromatic hydrocarbons (PAHs) was determined in seawater, sediment, and Rock oyster Saccostrea cucullata collected from four sampling sites in the inter-tidal areas of Bushehr province. The total concentrations of 14 PAHs varied from 1.5 to 3.6 ng/L in seawater, 41.7 to 227.5 ng/g dry weight in surface sediment, and 126 to 226.1 ng/g dry weight in oyster tissue. In comparing PAH concentrations among the three matrices in Bushehr province, data showed that the pattern of individual PAHs in seawater, oyster, and sediment were different. The oysters tended to accumulate the lower molecular weight and the more water-soluble PAHs. Sediment samples were distinguished from the sea water and oyster samples by the presence of high molecular weight PAHs, especially six-ring PAHs. Three- and four-ring PAHs were the most abundant compounds among the 14 PAHs investigated in surface seawater, sediment, and oyster samples. As expected, differences in octanol/water partition coefficient among individual PAHs and the greater persistence of the higher molecular weight PAHs contributed to the accumulation patterns in oyster and sediment. The results of the study suggested that the main sources of PAHs in the seawater and sediment in the region were mixed pyrolitic and petrogenic inputs.     

Relationship between rice grain amylose and pasting properties for breeding better quality rice varieties

One hundred and sixty‐seven rice varieties/laudraces from 23 different rice‐growing countries were used for studying the relationship between the amylose content (AC %) and paste viscosity parameters (RVU) through Pearson correlation. AC and paste viscosity parameters were measured using Auto Analyser and Rapid Visco Analysers respectively. Based on all five RVA pasting properties, i.e. peak viscosity (PV), minimum viscosity (MV), breakdown (BD), final viscosity (FV) and setback (SB), the simple paired t‐test (at P = 0.05) was carried out to identify varieties that showed non‐significant differences (similar) from the check variety, separately for each of the four AC groups, e.g. Waxy rice AC (0–8%, n = 21) –‘IR29’ (Philippines); Low AC (8.1–16%, n = 58) –‘Koshihikari’ (Japan); Intermediate AC (16.1–24%, n = 64) –‘Local Sadri’ (Iran); high AC (>24.1%, n = 24) –‘Kasalath’ (India). Significant variation among the rice varieties for AC and pasting properties were observed. Means of the AC and the viscosity parameters including PV, MV, BD, FV and SB were 15.8, 416.1, 180.3, 235.8, 380.9 and 200.6 RVU respectively. Significant correlations existed between AC and paste viscosity parameters at AC group level. The paste viscosity parameters, i.e. PV, BD and SB are important within an AC group as far as cooking quality is concerned. In the low AC group, ‘Koshihikari’ (check) was most preferred by Japanese consumers, which was used for identifying 16 varieties that showed non‐significant differences for pasting properties with it. Some of the important Japanese varieties were ‘Todorokiwase’, ‘Owarihatamochi’, ‘Sasanishiki’, ‘Reimei’ and ‘Kinuhikari’. These varieties had good cooking quality with low AC, high PV and BD with low SB. In contrast, the Iranian cultivar ‘Local Sadri’ with good cooking quality had intermediate levels of AC and SB while recording high PV and BD. The varietal diversity for pasting properties available within each AC group may allow the breeder to make effective selections for improving the cooking quality according to consumer choice.