Defeitos superficiais em 2H-WS2 observados por microscopia de tunelamento

Scanning tunnelling microscopy (STM) was used to characterise the basal surface of fresh cleaved crystals of 2H-WS2. Although no impurity or stacking faults could be detected by X-ray diffraction, STM images obtained with negative bias voltage showed two kinds of defects. These defects were attributed to an iodine derivative used as transport agent. In a flat surface free of defects, an image with atomic resolution was achieved with sulphur distances and angles as expected for hexagonal symmetry of 2H-WS2.

Identificação por microscopia Raman de pigmentos da pintura a óleo "Retrato de Murilo Mendes" de Cândido Portinari

In the present work "ex situ"Raman microscopy was employed in the identification of some of the pigments present in the painting "Portrait of Murilo Mendes" by Cândido Portinari. In the investigated samples it was possible to identify unambiguously two pigments: Prussian blue and lapis-lazuli (or its synthetic analogue, ultramarine blue) - the former is observed together with organic substances, possibly used as dispersants, what suggests a further use of a mass for recover the painting.

¿Animales...?: 'No nada'. Reflexiones de ética animal

Article sobre l'ètica animal i la situació general a nivell espanyol

Esquizofrenia: quarenta anos da hipótese dopaminérgica sob a ótica da Química Medicinal

Schizophrenia is a devastating psychiatric illness that affects 1-2% of the world population and continues as a challenge to neuroscience. In this work, we describe an account about the historical evolution of the dopaminergic hypothesis of schizophrenia discussing, from the medicinal chemistry point of view all different classes of antipsychotic drugs, emphasizing the rational design, structure activity relationships (SAR) and physico-chemical properties related with its molecular mechanism of action.

Microscopia de força atômica aplicada em imunoensaios

Affinity reactions have been used for specific detection of their complementary partners and an enormous variety of enzyme-linked immunosorbent assay (ELISA) formats are used in research and in routine serological tests. With the advent of the atomic force microscopy (AFM) technique, the immune reactions have been monitored by these devices. In the present article we focus on applications of AFM to immunoassays. After introducing the basic concepts of AFM, a brief discussion on the monitoring of the interactions between antigens and antibodies through both topographic image and biosensor systems is presented.

Ètica per aixecar la Moral : Problemes ètics als serveis socials bàsics en temps de crisi

Els riscos ètics als serveis socials en temps de crisi es multipliquen i s’intensifiquen, però en essència no es tracta de riscos nous ni diferents dels que es podien produir en temps de bonança econòmica i social. No obstant, la cruesa del context dels serveis socials bàsics (freqüència de les situacions límit que s'han d'atendre, les qüestions internes i externes de la pràctica professional, el malestar i desencant dels professionals) pot suposar una oportunitat de visibilitat i prendre consciència d'aquests riscos ètics. A la vegada, l'anàlisi i l'abordatge d'aquest nou context des d'una perspectiva ètica pot suposar un antídot que permeti ressituar la pràctica professional (amb els seus límits, però també amb les seves possibilitats), millorar-ne la qualitat i la transparència, i, de retruc, trencar amb la dinàmica de cronificació de la insatisfacció i queixa professional. És a dir, la perspectiva ètica pot ajudar a aixecar la moral dels professionals. Així doncs, amb aquesta recerca pretenem assolir els següents objectius: Identificar els riscos ètics de la intervenció als serveis socials bàsics en relació als efectes i l'impacte de la crisi econòmica; analitzar els diferents riscos ètics identificats i efectuar propostes d'abordatge i minimització d'aquests riscos ètics

Identificação de microcistina LR ao nível molecular empregando microscopia de força atômica

Microcystins are non-ribosomal peptides that must be detected for its health concern. Here, microcystin LR and its specific antibody were respectively tethered to the substrate and to the tip of an atomic force microscope, after surface functionalization using 3-aminopropyltriethoxysilane and glutaraldehyde. Functionalization was confirmed comparing topographic images taken on bare and modified tips. Force versus distance curves were successfully used to measure the specific antibody-antigen interactions comparing with a control in which microcystin was initially blocked by incubation with free antibodies. The results showed unequivocally the specific recognition of MLR, suggesting that this method could be useful for biosensor development.

Um exemplo de aplicação da Microscopia Raman na autenticação de obras de arte

In the present work, Raman Microscopy was employed in the characterization of the pigments used in a drawing assigned to Tarsila do Amaral, one of the most important Brazilian artists. The work (colored pencil on paper), supposedly produced in the 1920 decade, is of a very simple composition, where blue, green and brown were the colors used. Prussian Blue was found as the blue pigment, whereas green was a mixture of copper phthalocyanine and a yellow dye, probably a diarylide; the brown pigment was a carbonaceous compound. Prussian Blue was replaced by phthalocyanine as pigment since the end of the 1930's and the possibility that it could have been used as pigment in the 1920's can be ruled out.

Análise de pinturas rupestres do Abrigo do Janelão (Minas Gerais) por microscopia raman

Rock art paintings from Abrigo do Janelão (Minas Gerais, Brazil) were non-destructively investigated by Raman Microscopy, aiming at the identification of materials used, their interaction and degradation. This technique is particularly tailored for heterogeneous samples and allows unequivocal identification of the substances present in the investigated sample. Pigments, were identified together with products of microbiological degradation; no binders were detected. White pigment was identified as calcite (CaCO3), whereas charcoal was used as black, goethite (α-FeOOH) as yellow and hematite (α-Fe2O3) as red. Whewellite (CaC2O4.H2O) and weddelite (CaC2O4.2H2O) were detected and their origin was assigned to degradation products from microbiological activity.

CARACTERIZAÇÃO E ATIVIDADE CATALÍTICA DE K2CO3/AL2O3 NA TRANSESTERIFICAÇÃO DO ÓLEO DE GIRASSOL COM AQUECIMENTO CONVENCIONAL E MICRO-ONDAS

Commercial and synthetic mesoporous aluminas impregnated with potassium carbonate were characterized by X-ray diffraction (XRD), nitrogen physisorption, infrared spectroscopy and 27Al MAS NMR. The activities in the transesterification reaction of sunflower oil with methanol for biodiesel production were evaluated. 27Al MAS NMR spectra evidenced the presence of AlIV and AlVI in the samples, and also of AlV sites in the mesoporous synthesized alumina, which disappeared after impregnation with potassium salt followed by calcination. All aluminas containing potassium were active for biodiesel production from sunflower seed oil, with high conversions by both conventional heating and microwave irradiation.

Zingiber officinale (GENGIBRE) COMO FONTE ENZIMÁTICA NA REDUÇÃO DE COMPOSTOS CARBONÍLICOS

Various vegetables as biological catalysts were evaluated in enantioselective reduction of carbonyl compounds. The stereoselectivity of the process was in agreement with Prelog's rule for twelve of the vegetables, whereas okra and green peppers formed anti-Prelog products. Zingiber officinale exhibited the best results with 30% conversion and 89% ee. The parameters of the reaction such as time, solvent and other substrates investigated, as well as the specie, showed good chemo- and enantioselectivity.