88,453 research outputs found
L'arsenal thérapeutique des Druides : F. Parenti et F. Fiorenzola, in Pagine di storia délia medicina
No full textGuitard Eugène-Humbert. L'arsenal thérapeutique des Druides : F. Parenti et F. Fiorenzola, in Pagine di storia délia medicina. In: Revue d'histoire de la pharmacie, 52ᵉ année, n°180, 1964. p. 43
Interaction studies of a β-cysteine functionalized polythiophene with biomolecules
No full textPolythiophenes are an important representative class of conjugated and thermally stable polymers that can be used in alternative to inorganic semiconductors in optical and electronic devices [1]. Recently, they have been studied as biological sensors [2], thanks to the presence of the electroconducting backbone together with β-substituents able to interact with biological species. The interaction between the polymer side chain functionalities and the analyte can be of different type (hydrogen bonds, ionic interactions ...) depending on the analyte, or the backbone itself can directly interact with the biomolecule through π-π stacking.In this study, a previously synthesized β-cysteine functionalized polythiophene (PTCys, Fig 1) [3] was investigated as folic acid [4] and cytochrome C (horse heart) biosensor.[1] Skotheim Ed. T., Reynolds J., Elsenbamer R., Dekker Marcel, Inc., New York, NY, USA, Handbook of conducting polymers 2nd Edition, 1998; Skotheim Ed. T., Dekker Marcel, Inc., New York, NY, USA, Handbook of conducting polymers 1986[2] Berggren, M.; Inganas, O.; Gustafsson, G.; Nature,1994, 372, 444-446[3] Cagnoli R., Lanzi M., Mucci A., Parenti F., Schenetti L., Polymer, 2005, 46(11), 3588-3596[4] Zhiyi Yao, Chun Li and Gaoquan Shi, Langmuir,2008, 24, 12829-1283
Archeologia preistorica e analisi del DNA mitocondriale nella questione del popolamento delle Americhe
No full textNative Americans belong to one of the few extant human groups whose ancestors entered a vast uninhabited area and then apparently remained isolated from other human contacts for thousands of years. They are descendants of peoples, who, after their expansion to the Americas, underwent through a rapid process of tribal radiation and isolation, localised genetic and cultural differentiation, and adaptation to a variety of different environmental conditions. Although there is consensus that the provenance of the ancestral Native Americans was North-Eastern Asia, the diversity of opinions on the time of the earliest human entry into the Americas, and the number of migratory events has often been accompanied by an acrimonious debate. As a broad generalization, the discussants of the times of human colonization of the New World can be divided into two camps, one favoring an "early" entry [more than approximately 30.000 years before present (YBP)] , the other favoring a "late" arrival (less than approximately 13,000 YBP). As for the number of migratory events, the debate is between those who favor a single migration from Asia, followed by an "in situ" genetic and cultural differentiation, and those who favour multiple migration hypotheses. In this paper, we summarize the data concerning these issues that we have recently obtained through studies affering to two different and interrelated disciplines: molecular genetics and pre-historical archaeology. These data are strongly supportive of an "early" human colonization of the Americas, and indicate that the genetic and cultural heterogeneity of modern Native Americans is partially attributable to multiple migrations from Asia
Stiffness analysis of spatial strip-driven devices
No full textOrthoses and exoskeletons require simple yet accurate devices to assist human joints in their motion. This paper presents the stiffness analysis of a spatial-strip driven device suitable for this application. The device features two cylinders guided by three flexible strips, so that a pure rolling relative motion between the two cylinders is generated. The analysis is conducted by defining analytical models to predict the equilibrium position of the device under different loading conditions. Only axial stiffness of the flexible strips is considered, while the effects of flexural and torsional stiffness are ignored as well as friction
“Chiral Polythiophenes: a promising material for the study of the Chiral Induced Spin Selectivity”
No full textThe synthesis of both the enantiomers of a cysteine substituted thiophene monomer is reported (1). Once polymerized these
molecules gave access to self assembling polythiophenes able to organize itself in chiral superstructures, controlled by the sign
of the cysteine chiral center. These polymers show an interesting behavior due to the inter-chains hydrogen bonding
interactions, that causes the formation of helical architectures in the solid state. The two polymers have been characterized both
in solution and in the solid state.
These chiral polymers have been used as spin filters to investigate the existence of the Chiral Induced Spin Selectivity effect
(2) in the microscale dimension. Micro- and nano-scale multilayered devices based on these chiral polythiophenes were
prepared using different techniques, and characterized with electrical measurements under applied magnetic field.
The alignment of the polymer chains in relation to the substrate surface has been deepened (3), since the orientation of the
helical aggregates in the film influences the magnitude of the spin filtering effect. Studies of the effect of a strong applied
electric field on the alignment of the polymer both in static and dynamic experiments were carried out, and the obtained films
were characterized with various surface analysis techniques.
(1) Mucci, A.; Parenti, F.; Schenetti, L. Macromolecular Rapid Communications. 2003, 24, 9, 547–550.
(2) Göhler, B.; V. Hamelbeck; T. Z. Markus; M. Kettner; G. F. Hanne; Z. Vager; R. Naaman; H. Zacharias. Science. 2011, 331,
6019, 894–897.
(3) Sugita, A.; Tasaka, S. Journal of Polymer Science Part B: Polymer Physics. 2004, 42, 24, 4433–443
Micromilling force prediction through Digital Twins
No full textThe digital twin concept is defined and applied to the case of force prediction in micromilling where it could have a
strong impact as experimental and analytical approaches are complicated by the intrinsic physical pehnomena
taking place in micro chip removal processes. A first assessment is presented in this paper regarding the capability
of a commercial software (VERICUT®) to simulate not only the CNC machines in terms of geometry, kinematics
and control, but also the milling force. Typical micromilling conditions have been experimentally tested and
compared with the corresponding simulated conditions in terms of force components in the time domain. Results
point out how the prediction performance is not acceptable where micro chip removal phenomena as minimum chip
thickness take place, but promising improvements are foreseen in case of the implementation of micromilling
specific models in the software
A fast ligament model with scalable accuracy for multibody simulations
No full textMultibody musculoskeletal models are important tools to perform kinematic, kinetostatic, and dynamic analyses of the whole human body. In these models, bones are regarded as rigid bodies, while different strategies are used to model structures such as muscles and ligaments. In this context, ligaments are often represented using a finite set of spring-like elements to compute the wrench applied to the bones (multibundle model). While this model is fast and easy to be implemented, it can suffer from inaccuracies due to the limited number of fibers and their positioning. In this study, a ligament model is proposed to overcome these limitations, representing the ligament as an infinite distribution of fibers from which the wrench on the bones can be obtained. The model takes advantage of thin-plate spline mapping to model the fiber structure of the ligament by defining a correspondence between the points of the two ligament insertions. The accuracy and the performances of the model are verified on a ligament and compared to the standard multibundle model. Results indicate that the model is faster and more accurate than the multibundle model. Moreover, accuracy can be modified according to the application in order to decrease the computational time
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