Search

Magnetic nanoparticles (MNPs) are used extensively across numerous disciples, with applications including Magnetic Particle Imaging (MPI), targeted hyperthermia, deep brain stimulation, immunoassays, and thermometry. The assessment of MNPs, especially those being designed for MPI, is performed with magnetic particle spectrometers, relaxometers, loop tracers, or similar devices. Despite the many applications and the need for particle assessment, there are few consolidated resources for designing or building such a MNP assessment system. Here, we describe the design and performance of an open-source device capable of spectroscopy, relaxometry, and loop tracing. We show example measurements from the device and quantify the detection sensitivity by measuring a dilution series of Synomag-D 70 nm (from 0.5 mg Fe/ml to 7 ng Fe/ml) with a 10 mT drive field at 23.8 kHz. The device measures 260 pg Fe with SNR = 1 and 1.3 ng at SNR = 5 in spectroscopy mode in under one second of measurement time. The system has a dynamic range of 60 μg to 260 pg Fe without changing the hardware configuration. As an example application, we characterize Synomag-D's relaxation time constant for drive fields 2–18 mT and compare the magnetization responses of two commonly used MNPs. [ABSTRACT FROM AUTHOR]

This paper explores the capabilities of a combination of the reduced data set ISCCP-B2 from the Meteosat satellites and the recently developed method Heliosat-2 to assess the daily mean of the surface solar irradiance at any geographical site in Europe and Africa. Firstly, we discuss the implementation of the method Heliosat-2. Secondly, B2-derived irradiances are compared to coincident measurements made in meteorological networks for 90 stations from 1994 to 1997. Bias is less than 1 W [m.sup.-2] for the whole set. Larger bias may be observed at individual sites, ranging from -15 to +32 W [m.sup.-2]. For the whole set, the root mean square difference is 35 W [m.sup.2] (17%) for daily mean irradiance and 25 W [m.sup.-2] (12%) for monthly mean irradiance. These accuracies are close to those of similar data sets of irradiance, such as Medias and NASA Surface Radiation Budget. It is concluded that B2 data can be used in a reliable way to produce longterm time-series of irradiance for Europe, Africa and the Atlantic Ocean. Keywords: Satellite; Radiation; Fluxes; Climatology; Africa; Europe; Atlantic Ocean

This article presents the method Heliosat-2 that converts observations made by geostationary meteorological satellites into estimates of the global irradiation at ground level. This new version integrates the knowledge gained by various exploitations of the original method Heliosat and its varieties in a coherent and thorough way. It is based upon the same physical principles but the inputs to the method are calibrated radiances, instead of the digital counts output from the sensor. This change opens the possibilities of using known models of the physical processes in atmospheric optics, thus removing the need for empirically defined parameters and of pyranometric measurements to tune them. The ESRA models are used for modeling the clear-sky irradiation. The assessment of the ground albedo and the cloud albedo is based upon explicit formulations of the path radiance and the transmittance of the atmosphere. The method Heliosat-2 is applied to Meteosat images of Europe for the months of January 1995, April 1995 and July 1994. Pyranometric measurements performed by thirty-five meteorological stations are used to assess the performances that are close to those of Heliosat-1 found in the literature. Possible improvements are discussed. Keywords: Turbidity; Atmosphere optics; Radiation; Image processing; Meteorology; Mapping; Albedo; Cloud; Clearness index; Software: Meteosat

This work is a first attempt to propose a map of the solar radiation climate in Africa. Such a map is very useful for preliminary assessment and modeling of solar energy systems. Following the approach adopted for Europe, a data set of monthly means of the daily clearness index has been assembled for 62 sites. A cluster analysis was applied to create 20 classes that were reported on a map of Africa. These classes were geographically extended, thus creating a solar radiation climate map, comprising 20 climates. Known features and other atlases, global or local, were used in this mapping. This map and its companion tables permit to perform elementary energy calculations. Further improvements are discussed. Keywords: Clearness index; Atmosphere optics; Clustering; Interpolation; Map; Solar energy systems

The Linke turbidity factor (TL) has been estimated at 16 locations in Africa (9 stations in Egypt, 2 in Mozambique and Zimbabwe, 1 in Algeria, Tunisia and Zambia). An appropriate processing of time-series of measurements of daily sums of solar global radiation spanning several years provides mean values of TL for each month with a sufficient accuracy. Though limited to the Mediterranean area, Egypt and sub-tropical Southeastern part, this work greatly extends the knowledge on the clearness of the atmosphere in Africa, an area not much addressed in the literature. The relationship between TL and the climate is evidenced. TL is almost constant throughout the year close to the Mediterranean basin with values around 3.5. Stations located in the sub-tropical Southeastern part exhibit large variations of TL.

The control of the quality of irradiation data is often a prerequisite to their further processing. Though data are usually controlled by meteorological offices, the sources are so numerous that the user often faces time-series of measurements containing questionable values. As customers of irradiation data, we established our own procedures to screen time-series of measurements. Since this problem of quality control is of concern to many researchers and engineers and since it is often a lengthy and tedious task, we decided to make this screening procedure available to everyone as a web service. This service is the purpose of this paper. The objective is not to perform a precise and fine control, an objective out of reach without details on the site and instruments, but to perform a likelihood control of the data and to check their plausibility. This is achieved by comparing observations with some expectations based upon the extraterrestrial irradiation and a simulation of the irradiation for clear skies. This service is available to everyone on the Web site www.helioclim.net. It offers a very convenient means to check time-series of irradiation: data are input in a HTML page by a copy and paste procedure and the return is also a HTML page that can be analyzed in detail for the data flagged as suspicious.