ESEM-EDS: In vivo characterization of the Ni hyperaccumulator Noccaea caerulescens.

Environmental scanning electron microscopy (ESEM) permits to analyze samples in their native-hydrated state, allowing a broad spectrum of biological applications. In this study, ESEM equipped with energy dispersive X-ray spectrometer (EDS) was used as a fast method to analyze tissue morphology and to investigate metal distribution in the Ni hyperaccumulator Noccaea caerulescens, an established model to study the adaptation of plants to metalliferous soils. The low vacuum and wet mode operative conditions required the proper choice of experimental parameters both for morphological and compositional characterization of plant tissues. The calibration strategy for semi-quantitative analysis involved the use of Ni fortified agar as standard and signal normalization respect to endogenous carbon, chosen as internal standard. The obtained results are in accordance with present literature, showing a preferential Ni distribution in the epidermal cells respect to near the stomata for leaves and in the cotyledon epidermidis respect to cotyledon parenchyma area for seeds. Thanks to the absence of any time consuming sample treatment steps, ESEM-EDS technique can be proposed as valid strategy for in vivo high-throughput analysis of plant tissues and for a rapid screening and identification of other hyperaccumulator plants in a selected contaminated area.

The use of environmental scanning electron microscopy for imaging wet and insulating materials.

The environmental scanning electron microscope (ESEM) is a direct descendant of the conventional SEM, but also permits wet and insulating samples to be imaged without prior specimen preparation. A low pressure (up to around 10 torr) of a gas can be accommodated around the sample. When this gas is water, hydrated samples can be maintained in their native state. Whether the gas is water or some other gas, ions formed on collisions between electrons emitted from the sample and the gaseous molecules drift back towards the sample surface helping to reduce charge build up. This eliminates the need for insulators to be subjected to a conductive surface coating. These two key advantages of ESEM open up a wide range of materials to the power of scanning electron microscopy.

Aplicaciones biomédicas de la microscopia electrónica y el análisis elemental con espectrómetro de rayos x / Biomedical applications of the electroc mycroscopi and the elementary analysis with spectrometer of X-ray

La microscopia electrónica ha avanzado mucho desde su invención hace 60 años y su aplicación en las ciencias biomédicas ha sido muy grande. Paralelo al desarrollo de nueva tecnología en este campo y que ha permitido alcanzar una resolución de 1,4 A para el microscopio de transmisión y de 30 a 70 A para el microscopio de rastreo, se le han adaptado a estos microscopios otros aparatos que permiten realizar un análisis elemental de la muestra que está siendo examinada en el microscopio. La ventaja de este procedimiento es que la muestra que está siendo observada en tiempo real puede ser analizada en su composición química sin ser destruida. Adicionalmente es posible realizar un análisis de la distribución de sus elementos en toda la muestra. La aplicación de este nuevo método en las ciencias biológicas es muy amplia. Podemos detectar materiales inorgánicos como el plomo, arsénico, calcio, mercurio, alumnio, etc, en diferentes tejidos del cuerpo, obtenidos de biopsia o autopsia. Una aplicación práctica es el análisis de la composición de cálculos vesiculares o urinarios determinando de esta manera la fisiopatogenia del proceso. Palabras clave: Microscopia electrónica de rastreo, espectrómetro de rayos X, nefrolitiasis, cálculos urinarios.

Emprego da microscopia na análise dos materiais odontológicos / The microscopy use in the dental materials analysis

A microscopia eletrônica de ponta vem revolucionando as pesquisas sobre materiais dentais, trazendo ao cirurgiäo-dentista mais segurança na aplicabilidade de determinados produtos. A partir das análises laboratoriais, é possível identificar, dentre outros, a qualidade de acabamento superficial e a resistência mecânica dos materiais odontológicos. Saiba um pouco mais, neste artigo, a respeito dos três tipos de microscópicos modernos (óptico, de varredura e de transmissäo) utilizados para estes fins