I semiconduttori sono utilizzati per una grande varietà di applicazioni elettroniche, come circuiti integrati (microprocessori, microcontrollori, ecc.) rilevatori ottici e sorgenti di radiazioni (es. emettitori di luce), ma in modo particolare per i fotovoltaici, tramite i quali l’energia solare viene trasformata in potenza elettrica. Per la maggior parte delle applicazioni, il silicio è il materiale semiconduttore scelto.
From cell disruption to homogenization and pulverization of a great variety of biological samples
Biological samples exist in all shapes and sizes: hard bones, tough and fibrous plants, tough and viscous sputum, soft muscles, tumor or liver tissue. Not to mention the millions of cells such as yeast, bacteria or algae, which have to be disrupted for applications such as DNA or RNA isolation or protein extraction. For research in genomics, transcriptomics or metabolomics, all kinds of biological samples are prepared. Sample preparation is the first step of every analytical process. Retsch offers a range of mills and grinders for easy and reproducible pulverization of solid sample materials some of which are also suitable for cell disruption and homogenization of biological sample materials.
The most common types of coal (lignite, bituminous and anthracite) are distinguished by their different chemical and physical properties. The calorific value of coal can be determined by analyzing its carbon content, for example with combustion analyzers. In addition, efficient management of the desulfurization plant requires control of the sulfur content. Compared to the large amount of coal a typical laboratory sample consists of - a 10 liter bucket or even more - the sample volume required for analysis is fairly low, only approx. 1 g. The standard DIN 51701 defines the sample amount to be tested as this relates to the particle size: The bigger the particles are, the more sample material is required.
Reliable and accurate analysis results can only be guaranteed by reproducible sample preparation. This consists of transforming a laboratory sample into a representative part sample with homogeneous analytical fineness. Retsch offers a comprehensive range of the most modern mills and crushers for coarse, fine and ultra-fine size reduction of almost any material. The product range also comprises a wide choice of grinding tools and accessories which helps to ensure contamination-free preparation of a great variety of sample materials. The selection of the correct grinding tool depends on the sample material and the subsequent method of analysis. Different grinding tools have different characteristics, such as required energy input, hardness or wear-resistance.
Use of laboratory grinders for size reduction of human bones and bioceramics
Bone implants and substances for bone regeneration are used in surgery to replace degenerated bone material by implants or to “re-build” it with specific substances. The material used in implants varies from autogeneic (supplied by the patient) through allogeneic (supplied by a donor) bones to replacement materials such as hydroxylapatite (HA) and tricalcium phosphate (TCP). Bovine bones and corals are used in conjunction with synthetically produced foamed materials to form a basis for the regeneration of bone substance. Various RETSCH mills are suitable for the preliminary and fine grinding of human bones as well as bioceramic materials.
A variety of methods can be used to analyze solid materials. What they all have in common is the necessity to use a representative, homogeneous analysis sample which needs to have a particular fineness, depending on the analytical method used. The size reduction and homogenization of solids is usually carried out with laboratory crushers and grinders.
A faultless and comparable analysis is closely linked to an accurate sample handling. Only a sample representative of the initial material can provide meaningful analysis results. Rotating dividers and rotary tube dividers are an important means to ensure the representativeness of a sample and thus the reproducibility of the analysis. Correct sample handling consequently minimizes the probability of a production stop due to incorrect analysis results. Thus correct sample handling is the key to effective quality control.
Quality control is an important aspect of cement production. Sample preparation is an essential part of it, because only a representative and reproducible processing of the sample material ensures reliable and meaningful analysis results. RETSCH offers a range of instruments for dividing, crushing, grinding and sizing all materials which are involved in the production process of cement, including secondary fuels. To ensure the right choice of instrument for the right sample material, Retsch offers free-of-charge sample testing in application laboratories all over the world. Elemental analysers based on combustion technology are a useful addition to XRF analysis for the quality control of cement and related products, ensuring fast, precise and reliable determination of carbon and sulphur. With its offering of analyzers using resistance or induction furnaces or both, ELTRA covers a wide range of applications for C and S determination in organic and inorganic samples. The product range is ideally suited to the variety of analytical applications in a cement plant.
The preparation of a mixture of organic and inorganic samples holds some difficulties: whereas sand, clay and stones can usually be ground to homogeneous samples with suitable laboratory mills, the high energy input can cause samples with organic components such as fat or starch to cake. Carsten Bunn, a laboratory technician at the waste water treatment laboratory BRW, has to deal with this problem every day. He treats samples which are taken from the sand traps of the wastewater treatment plants and consist of exactly that mixture. The sediments of household and industry waste water not only contain sand, clay or leaves but anything that people nowadays dispose of through the sewer system: cellulose, hair and especially food residues.