Search results for "Shield"
showing 10 items of 177 documents
Coil overlap in moderately concentrated polyelectrolyte solutions: effects of self-shielding as compared with salt-shielding as a function of chain l…
2016
The generalized intrinsic viscosity {η} (hydrodynamic volume of the solute at arbitrary polymer concentration c) – introduced by analogy to the intrinsic viscosity [η] – provides access to the degree of coil overlap Ω for polyelectrolyte solutions in pure water or in saline water. The experimental basis of this investigation consists in viscosity measurements as a function of c for a large number of sodium polystyrene sulfonate (Na-PSS) samples covering the molecular weight range from 0.91 to 1000 kg mol−1. The accurate modeling of these dependencies with a maximum of three parameters yields detailed information on Ω as a function of (c[η]) in the absence and in the presence of extra salt. …
Crystal structure of two N′-(1-phenylbenzylidene)-2-(thiophen-3-yl)acetohydrazides
2019
Two N′-(1-(phenylethylidene)-2-(thiophen-3-yl)acetohydrazides containing –OH and –OCH3 at the para-position of the phenyl ring have been synthesized and their molecular and crystal structures are reported.
Estimation of isotropic nuclear magnetic shieldings in the CCSD(T) and MP2 complete basis set limit using affordable correlation calculations
2013
A linear correlation between isotropic nuclear magnetic shielding constants for seven model molecules (CH2O, H2O, HF, F2, HCN, SiH4 and H2S) calculated with 37 methods (34 density functionals, RHF, MP2 and CCSD(T)), with affordable pcS-2 basis set and corresponding complete basis set results, estimated from calculations with the family of polarization-consistent pcS-n basis sets is reported. This dependence was also supported by inspection of profiles of deviation between CBS estimated nuclear shieldings and shieldings obtained with the significantly smaller basis sets pcS-2 and aug-cc-pVTZ-J for the selected set of 37 calculation methods. It was possible to formulate a practical approach o…
Benzen i metan jako wzorce przesunięcia chemicznego 1 H i 13 C NMR w obliczeniach teoretycznych
2020
NMR spectroscopy belongs to the most versatile techniques used in chemical laboratory for testing the presence of various compounds and elucidation of their structure. In case of more complex natural products chemical intuition and experience applied to analysis of experimental spectra is often supported by theoretical modeling of NMR spectra. However, theoretical predictions should be reliable and the errors associated with the approximations inherent to the existing methods minimized. In this respect, systematic errors, present in calculation of isotropic nuclear magnetic shieldings of the studied molecule need to be minimized. Conversion of nuclear shieldings of the studied molecule to t…
On the distribution of lightning current among interconnected grounding systems in medium voltage grids
2018
This paper presents the results of a first investigation on the effects of lightning stroke on medium voltage installations' grounding systems, interconnected with the metal shields of the Medium Voltage (MV) distribution grid cables or with bare buried copper ropes. The study enables us to evaluate the distribution of the lightning current among interconnected ground electrodes in order to estimate if the interconnection, usually created to reduce ground potential rise during a single-line-to-ground fault, can give place to dangerous situations far from the installation hit by the lightning stroke. Four different case studies of direct lightning stroke are presented and discussed: (1) two …
Failure Rate, Marginal Bone Loss, and Pink Esthetic with Socket-Shield Technique for Immediate Dental Implant Placement in the Esthetic Zone. A Syste…
2021
Simple Summary The socket-shield technique has been proposed for preserving the bone ridge and surrounding soft tissues with immediate implantation in the extraction socket, maintaining the buccal wall fragment of the dental root. However, the socket-shield technique has not been compared with the conventional technique for immediate dental implant placement in the esthetic zone regarding the failure rate, marginal bone loss, and pink esthetic. Therefore, it is necessary to develop a systematic review and meta-analysis that provides evidence associated with the prognosis when using the socket-shield technique compared to the conventional technique. Abstract Aim: To compare the failure rate,…
Tube Housing Leakiness Radiation and Patient Related Radiation Protective Measures – Gonads Radiation Exposure from Panoramic Radiography
2009
The purpose of this study was to compare patient- and apparatus related radiation protective measures considering gonad radiation exposure at panoramic radiography. The local dose (yGv) in the region of the gonads of a male Alderson-Rando-Phantom was measured by the dosimeter Tol-F (Berthold Technology, Germany) during panoramic radiography (PR) by the digital Orthophos XG plus®(Sirona / Bensheim, Germany). Different radiation protective measures was investigated during constant exposure parameters. In the second part of the survey the same ionisation chamber recorded the scattered radiation at the gonads level of the none protected phantom at various case shielding. Without protection apro…
Radiation transmission data for radionuclides and materials relevant to brachytherapy facility shielding
2008
To address the limited availability of radiation shielding data for brachytherapy as well as some disparity in existing data, Monte Carlo simulation was used to generate radiation transmission data for 60Co, 137CS, 198Au, 192Ir 169Yb, 170Tm, 131Cs, 125I, and 103pd photons through concrete, stainless steel, lead, as well as lead glass and baryte concrete. Results accounting for the oblique incidence of radiation to the barrier, spectral variation with barrier thickness, and broad beam conditions in a realistic geometry are compared to corresponding data in the literature in terms of the half value layer (HVL) and tenth value layer (TVL) indices. It is also shown that radiation shielding calc…
Radiologische Veränderungen nach Implantation zweier unterschiedlicher zementfreier Hüftschaftsysteme
1997
PURPOSE: Of the study was to evaluate radiological alterations of the femoral bone after implantation of two different prostheses. METHODS: 81 patients with 87 hips underwent total hip arthroplasty by using the Zweymuller-stem fixating in the medullary canal, and 175 patients with 182 ABG-stems with a proximally fixating, anatomical design were followed up clinically and radiologically. RESULTS: Adaptive bone remodelling in Zweymuller-stems showed in some patients thickening of the cortex of the femur and proximal bone-stock loss; reactive lines were seen in the proximal areas surrounding the prosthesis. Radiographs of patients with ABG-stems showed these lines in the distal, smooth part of…