جستجوی مقالات مرتبط با کلیدواژه « Polyethylene » در نشریات گروه « پزشکی »

High-energy beams, such as gamma rays and X-rays, have many applications in nuclear power plants, healthcare, aerospace, and medicine. Therefore, appropriate radiation protection of living bodies in nuclear science and industries is essential to shield humans against the aforementioned radiation. Utilizing shielding materials is a practical method to protect individuals from harmful radiation.

High-density polyethylene (HDPE)-based nanocomposites were prepared to perform as a shield against X-ray radiation by using various weight fractions of the tungsten oxide, barium sulfate, and bismuth trioxide (10, 15, 20, and 25% wt). Samples’ shielding properties were experimentally studied with an X-ray tube at 50, 60, 80, and 120 kVp.

The recorded results showed that with increasing the number of nanoparticles, the transmission factor and HVL values were decreased and the linear attenuation coefficient was increased significantly. SEM, EDX analysis, and TEM evaluated the morphological properties of the fabricated samples. Results revealed that the particle size of the used nanoparticles was in the 25-50 nm range. Thermal study of the prepared nanocomposites including ΔHm, crystalline percentage (Xc), melting point (Tm) as well as the thermal stability of the nanocomposites were determined by using DSC, and TGA, respectively.

Samples including 20% ​​and 25% wt of Bismuth trioxide, and Tungsten trioxide loaded on graphene oxide reached 12% and 10% transmission factor values, respectively.

Hypothermia appears predominant among low birth weight (LBW) newborns. This condition tends to instigate severe medical complications, including acidosis, cerebral hemorrhage, hypoglycemia, and hyaline membrane disease.

The purpose of this study was to examine the effectiveness of swaddling technique in hypothermia prevention among LBW neonates.

This randomized controlled trial was conducted on 40 recent babies (20 controls and 20 interventions), using a pre‑ and post‑test design. In the intervention group, a polyethylene swaddling was used, and in the control group, a cloth swaddling was used. Digital axillary thermometer was used to detect the body temperature. Mann–Whitney U‑test and Wilcoxon test were employed to examine the temperature difference between the two groups.

This observation showed a trend toward improvement in average temperature in the intervention group (pre 34.8°C, post 36.4°C) compared to the control group (pre 33.3°C, post 34.9°C). There were significant within‑group changes in both groups (P < 0.05) although no significant difference was found between the two groups (P = 0.267).

Both polyethylene and cloth swaddling methods showed improvement in neonate temperature. These methods are therefore highly recommended as alternatives in hypothermia prevention among LBW infants.

In order to measure the effect of antibacterial nano-covers, the direct contact of covers with meat products mixture was used as a control. Samples were contaminated with standard strains of gram-negative Escherichia coli and gram-positive bacteria Staphylococcus aureus. The samples were compared at specified times (0, 24, 48, and 72 hours). Despite the samples had large number of Staphylococcus aureus, except for one case, the confirmatory tests were found no other positive Staphylococcus aureus coagulase bacteria. This absence, despite the manual infection of two sections out of seven, raised the possibility that the domination of Escherichia coli bacteria prevented the growth of Staphylococcus aureus bacteria in the broth. The hypothesis was tested using a standard method (spot-on-lawn method), and no growth of positive staphylococci coagulase was observed on the Escherichia coli plate. However, the control plates, became turbid due to the growth of bacteria. Lack of growth can be attributed to the use of unsuitable bacteria.

Today nanopackaging has been applied in order to increase the quality and safety of foods. In this study the possibility of using silver nanocomposite as food packaging is investigated. Silver nanoparticles were prepared by chemical reduction and to approve the presence of silver nanoparticles, UV-VS spectroscopy was used. The mentioned test showed the formation of silver nanoparticles by exhibiting the typical surface Plasmon absorption at a wavelength of 380 nm as observed. Coating on LDPE was carried out after the formation of nanoparticles. The nanostructure and particle size of silver nanoparticles were confirmed by scanning electron microscopy (SEM). The average of particle size was 48 nm. In addition, the distribution of silver nanoparticles and their crystalline structure are characterised by SAXS and XRD respectively. The X-ray diffraction pattern showed five intense peaks (38.2°, 44.3°, 64.5°, 78.1° and 81.8°) in the whole spectrum of 2θ values ranging from 10° to 90°. The antibacterial activity of the prepared nanocomposite film was evaluated. The results showed favourable antibacterial efficiency against Escheria Coli (ATCC 8739) and staphylococcus aureus (ATCC 6538).

Due to its taste and nutritional properties, pistachio (Pistacia vera) is one of the most popular nuts in the world. One of the problems regarding the storage of fresh pistachios is hull browning. The phenomenon is the result of the formation of complex compounds and colored polymers caused by enzyme reactions, which damage the texture, aroma, taste and even the appearance of the fruit.

A study was conducted to investigate the effects of citric acid (0, 1, 1.5 and 2%) and ascorbic acid (0 ,15, 25 and 35 ppm), as well as two types of polyethylene (LDPE) and polystyrene coatings on the shelf life (day zero, 25 and 45) of Ahmad Aghaei pistachio cultivar. The samples were prepared from a pistachio orchard located in gardens in the area of Hozdagh in Kerman province. This experiment was performed with three factors in a factorial design based on a completely random design. Each value is the average of four replications (200-gr in each replicate). Sources of variation were treatment (Ascorbic and Citric acid), polymer coatings (polyethylene and polystyrene) and storage period (0, 25 and 45).

The results indicated significant effects of the treatments, polymer coatings and storage periods on some quantitative and qualitative characteristics of the pistachios. Slight weight loss during storage was observed in samples which were higher in polyethylene (0.45%) coatings compared to polystyrene (0.22%). Treatments did not have a significant effect on the pistachio firmness as compared with the effect of shelf life and coating. The hull firmness decreased (30.5%) during storage, but it first decreased and then increased in the kernel. In addition, the samples in the polystyrene coatings had more rigidity (3.5%) than the pistachios in the polyethylene package. In terms of browning, the appearance of the pistachios in the packaging of polystyrene coatings was more desirable than that of polyethylene coatings

In general, weight loss, firmness, apparent quality, and color indices were better in polystyrene coatings than polyethylene ones.