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A Facile Way to Prolong Service Life of Double Base Propellant.

ABSTRACT: The safe storage time for double base propellant (DBP or DB propellant) with stabilizers could usually be calculated to be greater than 40 years. However, the actual service life is far below that, which is largely caused by the decline of propellant mechanical performance. In this work polytetrafluoroethylene (PTFE) was introduced into the double base propellant formula as an additive. The tensile properties of this propellant before and after artificial aging were determined. The evaporation and diffusion characteristics of nitroglycerin (NG) in propellant were evaluated by thermogravimetry analysis (TGA). The results showed that mechanical properties of propellant were improved due to PTFE, especially for elongation at -40 °C, which was greatly increased by 115%. Moreover, the results of TGA showed that NG migration was reduced due to PTFE, which delayed the decline of propellant mechanical performance during aging. The reduction in elongation at -40 °C caused by aging was decreased by 68.5% for PTFE modified DBP. Enhanced mechanical properties and reduced NG migration could potentially prolong propellant service life.

SUBMITTER: Sun S

PROVIDER: S-EPMC6266550 | biostudies-literature | 2018 Nov

REPOSITORIES: biostudies-literature

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A Facile Way to Prolong Service Life of Double Base Propellant.

Sun Shixiong S Ma Song S Zhao Benbo B Zhang Guangpu G Luo Yunjun Y

Materials (Basel, Switzerland) 20181110 11

The safe storage time for double base propellant (DBP or DB propellant) with stabilizers could usually be calculated to be greater than 40 years. However, the actual service life is far below that, which is largely caused by the decline of propellant mechanical performance. In this work polytetrafluoroethylene (PTFE) was introduced into the double base propellant formula as an additive. The tensile properties of this propellant before and after artificial aging were determined. The evaporation a ...[more]

PMID: 30423838

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Project description:BackgroundBreast cancer screening is essential in detecting breast tumors, however, the examination is stressful. In this study we analyzed whether humor enhances patient satisfaction.MethodsIn this prospective randomized study 226 patients undergoing routine breast cancer screening at a single center during October 2020 to July 2021 were included. One hundred thirty-two were eligible for the study. Group 1 (66 patients) received an examination with humorous intervention, group 2 (66 patients) had a standard breast examination. In the humor group, the regular business card was replaced by a self-painted, humorous business card, which was handed to the patient at the beginning of the examination. Afterwards, patients were interviewed with a standardized questionnaire. Scores between the two study groups were compared with the Mann-Whitney U test or Fisher's exact test. P-values were adjusted with the Holm's method. Two-sided p-values < 0.05 were considered significant.ResultsOne hundred thirty-two patients, 131 female and 1 male, (mean age 59 ± 10.6 years) remained in the final study cohort. Patients in the humor group remembered the radiologist's name better (85%/30%, P < .001), appreciated the final discussion with the radiologist more (4.67 ± 0.73-5;[5, 5] vs. 4.24 ± 1.1-5;[4, 5], P = .017), felt the radiologist was more empathetic (4.94 ± 0.24-5;[5, 5] vs.4.59 ± 0.64-5;[4, 5], P < .001), and rated him as a humorous doctor (4.91 ± 0.29-5;[5, 5] vs. 2.26 ± 1.43-1;[1, 4], P < .001). Additionally, patients in the humor group tended to experience less anxiety (p = 0.166) and felt the doctor was more competent (p = 0.094).ConclusionHumor during routine breast examinations may improve patient-radiologist relationship because the radiologist is considered more empathetic and competent, patients recall the radiologist's name more easily, and value the final discussion more.Trial registrationWe have a general approval from our ethics committee because it is a retrospective survey, the patient lists for the doctors were anonymized and it is a qualitative study, since the clinical processes are part of the daily routine examinations and are used independently of the study. The patients have given their consent to this study and survey.

Dataset Information

A Facile Way to Prolong Service Life of Double Base Propellant.

Publications

A Facile Way to Prolong Service Life of Double Base Propellant.

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