s. babaee

One of the most widely used propellants is nitrocellulose (NC) based propellant, which is divided into three general groups including single base propellant (SBP), double base propellant (DBP), and triple base propellant (TBP). In this paper, the life time of three types of NC-based propellants has been examined by using the vacuum stability test (VST). In this method, kinetic equations have been used in a semi-continuous manner. Accordingly, the activation energy for three propellant samples has been calculated by using the model-free and model-fitting kinetic methods. The kinetic model of three propellants is related to the zero-order (F0) model. Berthelot life time equations of propellants are calculated based on the gas evolution in the thermal decomposition at different percentages of reaction progress (α) under VST conditions. Based on the Berthelot equations, under the similar α and the storage temperature, the life time of propellants is as follows: SBP>DBP>TBP. But, because of the differences between parameters in the determination of critical α for these propellants, the comparison of a lifetime by using the Berthelot equation is not the only reason for having a short or long life time.

Due to the widespread prevalence of COVID-19, clinicians should be aware of even the rare symptoms of the disease to help the patients with the proper clinical procedure. In this study, a new case related to COVID-19 induced tinnitus was reported.

The patient was 27 years old with a chief complaint of a sudden transient change in her chronic vascular tinnitus (loud pulsatile tinnitus) repeated several times a day during the illness period. Because the other symptoms were similar to those of COVID-19, she was referred for a PCR test.

The PCR test for Covid19 was positive. Audiology examinations revealed intact tympanic membrane and normal hearing levels. Impedance audiometry and acoustic reflexes were standard. Tinnitus evaluations confirmed a change of tinnitus quality to higher pitch tinnitus with a louder loudness. HRCT scan did not show lung involvement. 

In our case, tinnitus change is possibly due to a change in the blood flow caused by vasculitis, a confirmed manifestation of viral infectious including Coronavirus. Patients with sudden audio-vestibular symptoms should be further evaluated for the COVID-19 rule out. More detailed investigations are required to determine the involved mechanisms.

In this research a new type of magnetic Pb(II) and Cr(VI) ion-imprinted polymers were synthesized using Fe3O4@SiO2 magnetic particles as supporter, benzoyl phenyl hydroxylamine and dithizone as ligands for Pb and Cr ions respectively, 4vinyl pyridine as functional monomer, ethylene glycol dimethacrylate as crosslinker and 2,2′-azobis(isobutyronitrile) as the initiator. The ionic templates were achieved using HCl 2M as an eluent solution. The chemical structure, morphology, thermal behavior and magnetic properties of the sorbent polymers were evaluated using Fourier-transform infrared spectroscopy, scanning electron microscopy, thermal gravimetric analysis and vibrating sample magnetometry methods. Optimization of affecting parameters of the adsorption of analytes (adsorption time, pH, kind and concentration of the eluent solution, elution time and temperature) were performed using flame atomic absorption spectroscopy method. The results showed that the maximum adsorption capacities for lead and chromium at 40 ◦C were 92.3 and 96.8 milligrams per gram at pH of 6 and 3 respectively. The synthesized sorbents had high selectivity and were successfully applied for these pollutants removing from waste waters in vdifferent stages of ammonium perchlorate production process.

Pain and fatigue are common among patients following CABG (Coronary artery bypass graft) surgery. The aim of this study was to determine the effectiveness of massage therapy on pain and fatigue of patients after coronary artery bypass surgery.

In this clinical trial study، 72 patients (from 165 patients)، who were underwent coronary artery bypass surgery، were selected. This study performed from December 2010 to May 2011 in Isfahan Chamran hospital. Then، the patients were randomly assigned in two case and control groups. The patients of the case group (n= 36) received light pressure stroking massage for 20 minutes in 4 sessions in 4 consecutive days، 3 to 6 days after the surgery. The patients in control group received only the routine care. Variables pain and fatigue before and after the intervention was recorded by the use of the visual analogue scale.

Results showed that there was a significant differences in pain levels before and after the intervention between case and control groups (P<0. 001). Also، a significant differences in fatigue levels before and after the intervention between case and control groups (P<0. 001).

The use of Light Pressure Stroking massage therapy can decrease pain and fatigue of patients after coronary artery bypass surgery and due to low cost and simplicity of this method، it can perhaps be used as a complement to drug therapy and postoperative interventions used in these patients.