809 research outputs found
Digital Fingerprinting of Coffee Blending by Sensitive Crystallization
No full textThe authenticity and quality of productions is an area of priority interest that involves safety of consumers and potential economic damages deriving from frauds on origin, adulteration and labeling of products. Several investigation techniques are currently used to characterize food matrices from physical-chemical-biological point of view using different methods in order to limit possible adulterations. In this work, we have developed an experimental and computational framework to improve the potentialities of sensitive crystallization: an experimental technique known since 1936, but never used for quantitative assessment of food quality. As a test case, it has been applied to investigate the geographical traceability and quality of coffee samples. An extensive statistical analysis associated with a careful choice of advanced image descriptors allows gathering quantitative information about the samples, which can constitute a digital fingerprint of their composition. With this new tool we are able to distinguish with blind tests high-quality coffee brands from low-quality mixtures, different coffee species, green from toasted condition of beans and, to a lesser extent, the macro-geographical provenience. A powder X-ray diffraction analysis reinforces the results obtained by sensitive crystallization for the case where crystalline domains are present in the coffee sample.</jats:p
Multivariate Analysis Applications in X-ray Diffraction
No full text: Multivariate analysis (MA) is becoming a fundamental tool for processing in an efficient
way the large amount of data collected in X-ray diffraction experiments. Multi-wedge data
collections can increase the data quality in case of tiny protein crystals; in situ or operando setups
allow investigating changes on powder samples occurring during repeated fast measurements;
pump and probe experiments at X-ray free-electron laser (XFEL) sources supply structural
characterization of fast photo-excitation processes. In all these cases, MA can facilitate the extraction
of relevant information hidden in data, disclosing the possibility of automatic data processing even
in absence of a priori structural knowledge. MA methods recently used in the field of X-ray
diffraction are here reviewed and described, giving hints about theoretical background and possible
applications. The use of MA in the framework of the modulated enhanced diffraction technique is
described in detail
Data for: Improved modelling and critical analysis of future electrification pathways: the case of Tanzania
No full textSupplementary material accompanying the paper:Improved modelling and critical analysis of future electrification pathways: the case of TanzaniaMatteo V. Rocco, Elena Fumagalli, Chiara Vigone, Ambrogio Miserocchi, Emanuela ColomboDepartment of Energy, Politecnico di MilanoCopernicus Institute of Sustainable Development, Utrecht UniversityCorresponding author: Via Lambruschini 4, 21056 Milan, Italy. E-mail: [email protected]
Multivariate versus traditional quantitative phase analysis of X-ray powder diffraction and fluorescence data of mixtures showing preferred orientation and microabsorption
No full textIn materials and earth science, but also in chemistry, pharmaceutics and engineering, the quantification of elements and crystal phases in solid samples is often essential for a full characterization of materials. The most frequently used techniques for this purpose are X-ray fluorescence (XRF) for elemental analysis and X-ray powder diffraction (XRPD) for phase analysis. In both methods, relations between signal and quantity do exist but they are expressed in terms of complex equations including many parameters related to both sample and instruments, and the dependence on the active element or phase amounts to be determined is convoluted among those parameters. Often real-life samples hold relations not suitable for a direct quantification and, therefore, estimations based only on the values of the relative intensities are affected by large errors. Preferred orientation (PO) and microabsorption (MA) in XRPD cannot usually be avoided, and traditional corrections in Rietveld refinement, such as the Brindley MA correction, are not able, in general, to restore the correct phase quantification. In this work, a multivariate approach, where principal component analysis is exploited alone or combined with regression methods, is used on XRPD profiles collected on ad hoc designed mixtures to face and overcome the typical problems of traditional approaches. Moreover, the partial or no known crystal structure (PONKCS) method was tested on XRPD data, as an example of a hybrid approach between Rietveld and multivariate approaches, to correct for the MA effect. Particular attention is given to the comparison and selection of both method and pre-process, the two key steps for good performance when applying multivariate methods to obtain reliable quantitative estimations from XRPD data, especially when MA and PO are present. A similar approach was tested on XRF data to deal with matrix effects and compared with the more classical fundamental-parameter approach. Finally, useful indications to overcome the difficulties of the general user in managing the parameters for a successful application of multivariate approaches for XRPD and XRF data analysis are given
Gabriel García Márquez and the cinema : life and works / Alessandro Rocco.
No full textRocco focuses on Gabriel GarciÌa MaÌrquez's relations with the world of cinema and gives us the first detailed study of the author's wide-ranging filmography. A unique and indeed indispensable addition to the critical literature on a writer of world importance. Gerald Martin, author of Gabriel GarciÌa MaÌrquez: A Life Far from being an occasional occupation, GarciÌa MaÌrquez's film work forms an intrinsic part of his overall aesthetic and literary poetics. The book's primary aim is to present a detailed study of GarciÌa MaÌrquez's wide-ranging filmography, which has never received a comprehensive,systematic analysis. Rocco argues that it should be recognised as an integral part of the author's narrative output, and brought into the mainstream of studies concerning his literary activity. The first part of the book reconstructs the trajectory of GarciÌa MaÌrquez's career in cinema and his connections with the world of film. The second part looks at all his screenplays on which actual films have been based. These are examined chronologically, but also analysed according to thematic and aesthetic concerns and placed in relation to the novels and short stories with which they are 'twinned'. Alessandro Rocco is Researcher in Latin American Literature and Culture at the University of Bari, ItalyTitle from publisher's bibliographic system (viewed on 24 Feb 2023).Rocco focuses on Gabriel GarciÌa MaÌrquez's relations with the world of cinema and gives us the first detailed study of the author's wide-ranging filmography. A unique and indeed indispensable addition to the critical literature on a writer of world importance. Gerald Martin, author of Gabriel GarciÌa MaÌrquez: A Life Far from being an occasional occupation, GarciÌa MaÌrquez's film work forms an intrinsic part of his overall aesthetic and literary poetics. The book's primary aim is to present a detailed study of GarciÌa MaÌrquez's wide-ranging filmography, which has never received a comprehensive,systematic analysis. Rocco argues that it should be recognised as an integral part of the author's narrative output, and brought into the mainstream of studies concerning his literary activity. The first part of the book reconstructs the trajectory of GarciÌa MaÌrquez's career in cinema and his connections with the world of film. The second part looks at all his screenplays on which actual films have been based. These are examined chronologically, but also analysed according to thematic and aesthetic concerns and placed in relation to the novels and short stories with which they are 'twinned'. Alessandro Rocco is Researcher in Latin American Literature and Culture at the University of Bari, Ital
Chemical selectivity in structure determination by the time dependent analysis of in situ XRPD data: a clear view of Xe thermal behavior inside a MFI zeolite
No full textNew features of the RootProf program for model-free analysis of unidimensional profiles
No full textThe RootProf computer program applies multivariate model-free analysis to crystallographic data and to any x, y experimental data in general. It has been enhanced with several new features, including a graphical user interface, multithreading implementation and additional pre-processing options. The program also includes novel qualitative analysis methods, such as semiquantitative estimates derived from principal component analysis (PCA) and restrained PCA to extract the diffraction signal from active atoms. Additional quantitative analysis methods have been included, involving the combination of different datasets or the application of the standard addition method as well as tools for crystallinity analysis, kinetic analysis and extraction of free crystal cell parameters from a pair distribution function profile. The ROOT data analysis framework supports the program and can be installed on the current major platforms such as Windows, Linux and Mac OSX with detailed user documentation included. Applications of the new developments are presented and discussed in the paper, and related command files are provided as supporting information
Quantifying API polymorphs in formulations using X-ray powder diffraction and multivariate standard addition method combined with net analyte signal analysis
No full textThe direct quantification of Active Pharmaceutical Ingredients in solid formulations is a challenging open issue. A consolidated analytical technique based on X-ray Powder Diffraction is available, being the definitive test for the identification of polymorphs and crystal phases. However, its application for quantitative analysis is hindered by matrix effects: refinement methods (e.g. Rietveld method) require a complete knowledge of samples’ composition, while univariate calibration methods require the matrix effect to be studied and severely suffer from the co-presence of crystalline and amorphous phases in the sample. Multivariate analysis is the only way to bypass problems affecting refinements procedures and univariate calibration. In particular, the multivariate standard addition method (SAM) is promising; however, it is straightforward only when the analytical blank (matrix devoid of analyte) is available: in that case SAM is applied by simply extrapolating the SAM model to the matrix experimental signal. In this work, the quantitative analysis of polymorphic forms of Active Pharmaceutical Ingredients based on X-ray Powder Diffraction is performed for the first time by a method based on multivariate standard addition method combined with net analyte signal procedure; it allows for reliable quantification of polymorphs of active principles in solid formulations, which are rapidly analyzed without any sample pre-treatment. Two test cases are presented: quantification of two polymorphs of piracetam in binary mixtures (forms II and III), and quantification of paracetamol (form I) in Tachifludec®
Mechanistic and structural basis for inhibition of copper trafficking by platinum anticancer drugs
No full textCopper (Cu) is required for maturation of cuproenzymes, cell proliferation, and angiogenesis and its transport entails highly specific protein-protein interactions. In humans, the Cu chaperone Atox1 mediates Cu(I) delivery to P-type ATPases Atp7a and Atp7b (the Menkes and Wilson disease proteins, respectively), which are responsible for Cu release to the secretory pathway and excess Cu efflux. Cu(I) handover is believed to occur through the formation of three-coordinate intermediates where the metal ion is simultaneously linked to Atox1 and to a soluble domain of Cu-ATPases, both sharing a CxxC dithiol motif. The ultra-high thermodynamic stability of chelating S-donor ligands secures the redox-active and potentially toxic Cu(I) ion, while their kinetic lability allows facile metal transfer. The same CxxC motifs can interact with and mediate the biological response to antitumor platinum drugs, which are among the most used chemotherapeutics. We show that cisplatin and an oxaliplatin analogue can specifically bind to the heterodimeric complex Atox1-Cu(I)-Mnk1 (Mnk1 is the first soluble domain of Atp7a), thus leading to a kinetically stable adduct that has been structurally characterized by solution NMR and X-ray crystallography. Of the two possible binding configurations of the Cu(I) ion in the cage made by the CxxC motifs of the two proteins, one (bidentate Atox1 and monodentate Mnk1) is less stable and more reactive toward cis-Pt(II) compounds, as shown by using mutated proteins. A Cu(I) ion can be retained at the Pt(II) coordination site, but can be released to glutathione (a physiological thiol) or to other complexing agents. The Pt(II)-supported heterodimeric complex does not form if Zn(II) is used in place of Cu(I) and transplatin instead of cisplatin. The results indicate that Pt(II) drugs can specifically affect Cu(I) homeostasis by interfering with the rapid exchange of Cu(I) between Atox1 and Cu-ATPases, with consequences on cancer cell viability and migration
The Vitruvian Man of Leonardo Symbol of Western Civilization
No full textABSTRACT: THE VITRUVIAN MAN by Rocco Sinisgalli,
Federighi Editori, Certaldo, Florence, 2006.
ISBN 978-88-89159-22-4
9 788889 159224
The famous drawing of Leonardo (Vinci 1452, Amboise 1519) has become the symbol of western civilization. The author wrote The man is named Minor World by
the ancients. As Plato had bound fire and earth, the components with which God created the universe (the macrocosm), through the proportional mean, which was
named Divine, thus Leonardo bound man (the microcosm) which Vitruvius dissected in a circle and a square using the Golden Section. The Vitruvian man of Leonardo dates 1490 circa and measures 344x245 mm; the author was inspired by Vitruvius in the relationship between proportions, as he himself reports. We restrain ourselves to delineate how the square becomes the circle, or how from the circle one passes to the square, applying what we will discuss in Applied problems and in How to graphically obtain the
Golden Section.
Paragraphs: Leonardo's man, The man of Vitruvius, The Golden Section, Applied problems, How to graphically obtain the Golden Section, From the square to the circle, From the circle to the square, The bidimensionality within space, What Leonardo says about his drawing, Chronological summary of Leonardo's life
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