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Non-harmonic resonance of viscoelastic structures subjected to time-dependent exponentially decreasing transverse distributed loads

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Earthquake Engineering and Engineering Vibration 2023年第3期22卷 825-840页

作者： nasrin jafari Department of Civil Engineering Isfahan University of TechnologyIsfahan 84156-83111Iran

In this paper,the non-harmonic resonance of Bernoulli viscoelastic beams,Kirchhoff viscoelastic plates,Timoshenko viscoelastic beams,and Mindlin viscoelastic plates subjected to time-dependent exponentially decreasing transverse distributed load is investigated for the first *** constitutive equations are expressed utilizing Boltzmann integral law with a constant bulk *** displacement vector is approximated by employing the separation of variables *** Laplace transformation is used to transfer equations from the time domain to the Laplace domain and vice *** novel point of the proposed method is to express,prove and calculate the critical time in which the displacement will be several times the displacement at time *** addition,this new method calculates the maximum deflection at the critical time,explicitly and exactly,without any need to follow the time-displacement curve with a low computational ***,the proposed method introduces the critical range of time so that the responses are greater than the responses at time zero.

关键词： Bernoulli and Timoshenko viscoelastic beams critical time non-harmonic resonance time-dependent decreasing exponential load Kirchhoff and Mindlin viscoelastic plates

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Geochemistry of Host and Altered Rocks in the Nahran Area, Tarom Zone (NW Iran): Implication for Determining of Mineralization Processes in the Alteration Environment

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Open Journal of Geology 2017年第3期7卷 374-394页

作者： nasrin Bayrami Tosanloo Hamid Reza Peyrowan Seyed Jamal Sheikhzakariee Ali Reza jafari Rad Department of Geology Science and Research Branch Islamic Azad University Tehran Iran Soil Conservation and Watershed Management Research Institute Tehran Iran

The Nahran area is located in the Northeast of Zanjan in the Northwest of Iran. This area with 20,000 km2 is part of the Tarom volcanic-plutonic zone which lies between the longitudes 49°7'7.8"E and 36°41'25.74"E near to the Nahran village. The Nahran altered zone is part of large-scale syncline, which is oriented from Sirdan to Altinkosh with an axial length of 9 km. A systematic study of petrographical and geochemical data of Nahran samples reveals they are andesite, trachyandesite to dacite composition and have metaluminous to peraluminous and calc-alkaline affinity. Four alteration zones of propylitic, medium and advanced argillic and silicific zones could be identified in the area. According to our finding, combination of both supergene and hypogene process has an effective role in the development of alteration in the Nahran alteration zone.

关键词： Tarom Nahran Alteration Hypogene Supergene

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Synbiotic for Prevention of SARS-Cov2 Infection in High Risk Hospital Staffs: A Randomized Controlled Trial

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Open Journal of Nursing 2021年第5期11卷 281-290页

作者： Hamid Ahanchian Alireza Ranjbar Hamidreza Reihani Arash Peivandi Yazdi Seyed Ali jafari Mohammad Ali Kiani Rana Tafrishi nasrinsadat Motevalli Haghi nasrin Moazzen Ali Khalshour Faezeh Mirzaei Zahra Abbasi Shaye Sadegh Ebrahimi Hamidreza Kianifar Child Health Research Centre University of Queensland South Brisbane Australia Allergy Research Center Faculty of Medicine Mashhad University of Medical Sciences Mashhad Iran Institute for Interventional Allergology and Immunology Cologne/Bonn Germany Department of Emergency Medicine Faculty of Medicine Mashhad University of Medical Sciences Mashhad Iran Lung Disease Research Center Faculty of Medicine Mashhad University of Medical Sciences Mashhad Iran Department of Pediatrics Faculty of Medicine Mashhad University of Medical Sciences Mashhad Iran Faculty of Medicine M.V. Lomorosov Moscow State University (MSU) Moscow Russia

Introduction: COVID-19 pandemic caused by the novel coronavirus SARS-CoV-2 increasingly involves people worldwide. Probiotics can improve immune system functions via different mechanisms. We proposed that Synbiotic Lactocare? may also reduce SARS-Cov2 infection in high-risk medical staff working in COVID-19 hospital wards. Method: In a randomized, controlled trial, 60 hospital staff without any history of clinical or laboratory evidence of SARS-Cov2 infection were received either once-daily oral synbiotic capsule (Lactocare?) that contains 1 billion CFU/Cap of L. (Lactobacillus) casei, L. rhamnosus, Streptococcus thermophilus, Bifidobacterium breve, L. acidophilus, Bifidobacterium infantis, L. bulgaricus, and Fructooligosacharide (Zist Takhmir, Tehran, Iran) or placebo with the same appearance for 30 days. They were followed for two months. Result: During the two-month period of this study, SARS-COV-2 RT-PCR test results were positive in three participants (9.67%) in placebo group compared to zero positive tests in synbiotic group. The differences were not statistically significant (p = 0.238). During the study, two persons (7 %) of placebo group had respiratory complaints such as cough, rhinorrhea and/or dyspnea, compared with one in synbiotic group (p = 0.492). Conclusion: This study showed that overall frequency of SARS-COV2 infection in participants receiving synbiotic and those receiving placebo did not differ significantly. However, 3 hospital staff in placebo group compared to no one in synbiotic group had SARS-COV2 infection. Further studies with greater power and alternative pro

关键词： COVID-19 Synbiotic Prevention Lactocare SARS-Cov2

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