نتایج جستجو برای: shielding

تعداد نتایج: 9087  

Journal: :Journal of the American Chemical Society 2002
Kristofer Modig Bertil Halle

The nuclear magnetic shielding tensor is a sensitive probe of the local electronic environment, providing information about molecular structure and intermolecular interactions. The magnetic shielding tensor of the water proton has been determined in hexagonal ice, but in liquid water, where the tensor is isotropically averaged by rapid molecular tumbling, only the trace of the tensor has been m...

ژورنال: سلامت کار ایران 2015

Background and aims:  X-band microwave with 8-12.5 frequency range has various applications such as air control traffic, navy communication and etc. Uncontrolled exposure with microwave can lead to adverse effect on workers. Application of the shielding is superior control for prevention of microwave exposure.The aim of this study is production a new electromagnetic shielding for exposure contr...

2008
E. Kozlova K. H. Behr G. Fehrenbacher H. Geissel T. Radon K. Sümmerer H. Weick M. Winkler

Progress of the shielding calculation of the Super-FRS is reported here. At least as important as the shielding of the target area is the determination of the shielding in the region of the first dipoles as the part of the primary beam that will not interact in the target will be stopped here. The Monte-Carlo-method with FLUKA [1] used for the shielding assessment here has already been describe...

2013
R. Grosescu

Using solid state multiple pulse techniques the magnetic shielding tensors a of the F nuclei in a single crystal of KZnF 3 have been measured. The F~-site symmetry in KZnF3 , D 4 h , allows axial anisotropy of a and determines fully the principal shielding directions. Using CaF 2 as the reference compound, the average shielding is + 85 ppm and the shielding anisotropy is + 18.4 ppm. These resul...

2011
Chen-Ching Ting Chien-Chih Chen

This article presents some new experimental data for study the shielding effect of electromagnetic wave. The frequencies of electromagnetic wave are mainly focused on emission of daily electrical equipments, which are normally called “low frequency electromagnetic waves”. In this work, a water pump with maximum magnetic field intensity of ca. 2300 mG was applied as emission source of the electr...

2013
Ekkasit Tharavichitkul Somsak Wanwilairat Anirut Watcharawipha Damrongsak Tippanya Rungtip Jayasvasti Somvilai Chakrabandhu Pitchayaponne Klunklin Wimrak Onchan Razvan Galalae Imjai Chitapanarux

PURPOSE To evaluate the cumulative dose at point A for three and four centimeters central shielding. MATERIAL AND METHODS The plans of external beam radiotherapy plus conventional intracavitary brachytherapy were performed. Three or four centimeters central shieldings (after 44 Gy) were applied to the standard whole pelvis irradiation. Additional intracavitary brachytherapy 4 × 7 Gy at point ...

2013
Karol Jackowski

Gas-phase multinuclear magnetic resonance (MR) spectra allow the total elimination of intermolecular effects from magnetic shielding in molecules. Consequently, the resonance frequencies of isolated atoms and molecules are also available for reading from MR spectra. Following the connectivity between nuclear magnetic moments, resonance frequencies of two different nuclei in the same MR experime...

ژورنال: سلامت کار ایران 2016

Background and aims: X-band with 8-12.5 frequencies range has various applications such as air control traffic, navy communication and etc. Uncontrolled exposure with microwave can lead to adverse effect on workers. Application of the shielding is superior control for prevention of microwave exposure, now. This study investigated the effect of dispersion on shielding effectiveness improvement a...

Introduction: Development of higher energy modalities such as positron emission tomography/computed tomography (PET/CT), has led to more complex shielding problems. This is due to several factors, such as the radiopharmaceutical relatively high-administered activity, high patient throughput, and high energies of 511 kilo-electron volt (keV) positron annihilation photon...

Journal: :iranian journal of radiation research 0
f. bouzarjomehri shahid sadoughi university of medical sciences, yazd, iran m. kiani tabriz university of medical sciences, medical physics, tabriz, iran a.r. farajollahi tabriz university of medical sciences, medical physics, tabriz, iran

background: the shielding methods in radiotherapy due to delivering an accurate radiation dose to cancer tissues and avoiding unnecessary dose to normal tissues are very important. these methods include lead standard blocks, individual molding and multi leaf collimator (mlc). the mlc method is not still common in iran radiotherapy centers. individual molding is better than the lead block shield...

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