In this study, the stability of trinitroglycerin (TNG) in polyethylene (PEG) 400 was investigated according to Arrhenius approach. The reaction rate constant (k) for the thermal disintegration of TNG in PEG 400 at various temperatures was counted based on the percents of remaining TNG at different intervals of time at a specific temperature. The results showed that “k” at 40, 50, 60, 70, 80 and 90 ºC were 6.5×10- 4, 3.57×1 0- 3, 4.7×1 0- 3, 3×1 0- 2, 6.2×10- 2 and 6.5×1 0- 2, respectively. By plotting “log k” against temperature (1/T), “k” was obtained at 5 and 20 oC which was 1.47×10- 5 and 7.94×10-5, respectively. The results showed the time required to attend 90, 80, 70, and 50 percent of the original TNG at 5 oC was 9.76, 20.7, 33, and 64.2 months, respectively. The results assist in the calculation of the expiration time of TNG/ PEG 400.

Polymer coating is an effective way for modifying he particle surface. Polymer adsorption by nanoparticles improves the stability of the suspension against aggregation. In order to prevent nanoparticles from aggregation, in this work, zinc oxide nanoparticles and polyethylene glycol (PEG) are used as nano-sized metal oxide powder and adsorbed polymer, respectively. The adsorption process is analyzed by the infrared spectroscopy (IR) technique. The size and structure of zinc oxide nanoparticles have been characterized by X-ray diffraction (XRD). The amount of the adsorbed polymer was measured by thermogravimetry analysis (TGA) method. Moreover, the aggregation and accumulation of the nanoparticles was studied using scanning electron microscopy (SEM). We found that, using the polymers with lower average molecular weight made nanoparticles with higher adsorption, lower size, and a more spherical shape. Our results show that the coating process is an effective way of avoiding aggregation, sticking, and clumping of nanoparticles.

Introduction: Colonoscopy and bowel preparation caused a number of serum electrolytes changes that may be dangerous in heart and kidney diseases and elderly patients.Objective: To determine the effect of serum electrolytes in patients who underwent colonoscopy and bowel preparation with PEG (Polyethylene Glycol) in Tehran Imam Khomeini hospital in 2008.Materials and Methods: Fifty nine patients who had been selected for elective colonoscopy after the detection of exclusion criteria were assessed prospectively. Serum level of sodium and potassium were analysed before bowel preparation with PEG (To), before colonoscopy (T1) and immediately after it (T2). Serum calcium and phosphorus levels were measured just before and after PEG.Results: Four patients (6.8%) did not follow the research protocol and were excluded. Four patients (6.8%) developed hyponatremia in T1 that continued in T2. There were no significant differences in prevalence of Hyponatremia and means of sodium serum levels in To, T1 and T2. Although there was a significant trend to decreased means of potassium levels of T2 versus T1 (P<0.01), but the maximum prevalence of Hypakalemia was in T1 (10.9%) with only 3.8% new Hypokaliemia in T2 and there was no significant difference. The prevalence of Hypocalcemia after PEG was 24% but there was no significant decrease.36% of patients developed Hypophosphatemia after PEG preparation with a significant decrease in mean of serum Phosphorus level (P<0.05). There was no significant relationship between electrolytes changes with age and sex.Conclusion: The serum electrolyte changes showed that preparation with PEG is a risk factor for development of Hypophosphatemia Colonoscopy and preparation with PEG may cause a significant decrease in potassium serum level.

The inorganic salt which is formed during the acid treatment of alkaline catalysis, used for the preparation of polyethylene glycol is removed by filtration process. Although such treatment is expected to remove most of the inorganic salts some remain which are generally finely dispersed in the compound. This remaining salt is known as ash and may be present in proportions of up to 0.3% by weight. Although this is not troublesome in many applications, for example, when the compound is used as a lubricant, the inorganic salt may sediment out during use and the sedimentation may cause serious problems. In this research, for preparation of PEG with low ash content, after completion of the first stage of the reaction the product was treated with on acid to neutralize the alkali catalyst and subsequently treating with a lower aliphatic alcohol on glycol to remove the suspended solid material and the alcohol or glycol from compound and determined the ash content and selected solvent as well. The results show that 10% by weight of methanol reduce the ash content to 0.01%.

Introduction: Constipation is one of the most prevalent causes of abdominal pain in pediatrics, with no underlying pathology. It is defined as functional constipation in 95% of cases evaluated. This study was designed to compare the therapeutic effect of polyethylene glycol (PEG) and lactulose in treating chronic functional constipation in children.Materials and Methods: In this randomized, double blind clinical trial, patients were classified into two groups: lactulose (n=65) and PEG (n=63). During an eight week period, patients were either treated with an average of 3.5 g/day (PEG) or 7 g/day (lactulose). Successful treatment was defined as defecation (painless and soft, or normal) three times or more per week. Analysis was performed by calculation and comparison of the success rate in both groups, followed by reporting the relative risk and number needed to treat (NNT).Results: Response to treatment in the second week was significantly higher in the PEG group when compared with the lactulose group (P<0.0001). There was a significant difference in the response rate between both groups in the 4th and 6th weeks (P<0.0001). In the 8th week all patients in the PEG group were treated successfully, whereas there were five (7.7%) cases who did not respond in the lactulose group.Conclusion: These results have shown that a four week treatment period with PEG (3 g/day) lead to a response rate of 87% in children, in comparison with lactulose (7 g/day) which needed at least eight weeks of treatment.