172,373 research outputs found
Swelling process induced by Focused Ion Beam on magnetic layers
No full textThe ability to prepare ordered arrays of micro/nano sized magnetic elements offers the chance to investigate magnetic properties at length scales previously inaccessible. Bi-dimensional ordered array of magnetic dots can be obtained through a number of different techniques.
Patterning of extended magnetic layers or multilayers by Focused Ion Beam (FIB) is one of the most powerful approaches for nano-structuration on a large variety of materials due to the high spatial resolution, good process control and elevated flexibility. This enables a very high accuracy to be achieved in the refinement (shape, sharpness, orientation and dimension) of each individual element and of the separation between the elements. On the other hand ion interactions with solids produce several damage effects. These effects can be very severe in the case of crystalline solids and of nano-sized elements, and can influence magnetic properties of the systems (magneto-crystalline and configurational anisotropy).
We studied by AFM and Depth Profile Auger analysis the ions effect on a submicron scale dots array obtained on a 10nm Fe/10nm NiO/MgO(001) multilayer capped with 10nm of MgO. Ion-induced local damage leads to a significant swelling effect on the nano-structures [1]. Our measurements suggest that swelling observed on the multilayer originates from substrate ion irradiation.
Transmission Electron Microscopy and diffraction technique measurements should give structural information and clarify the relations between ion induced damage and swelling effect.
[1] G. C. Gazzadi, P. Luches, S. F. Contri, A. di Bona, S. Valeri, Nucl. Instr. Meth. B 230 (2005) 512
Famiglia e comunità a Cento in età moderna
No full textNel territorio di Cento, come in altre parti della pianura bolognese, l'istituto della Partecipanza, che prevedeva il godimento collettivo della terra e la periodica assegnazione a sorte ai membri delle famiglie che originariamente avevano partecipato alla bonifica, ha influito in età moderna sulle strutture e sulle stesse relazioni della famiglia contadina. Mentre infatti in aree limitrofe non comprese dalla Partecipanza era predominante il contratto di mezzadria e la classica famiglia-azienda, complessa in senso orizzontale e verticale, che formava un'unica grande unità di coresidenza, nelle aree di Partecipanza non solo prevaleva la famiglia nucleare ma si praticava l'allontanamento dei figli e il loro insediamento presso altri nuclei familiari. Alla radice di quella che sembra una scarsa coesione dei legami famigliari ci sono le modalità di accesso al godimento dei beni collettivi, assegnati in capita e non in stirpes: conveniva quindi ai maschi separarsi per poter moltiplicare l'assegnazione delle quote. Sul piano dei legami affettivi supplivano le donne e tutta la parentela per via femminile: in quanto escluse dal diritto di partecipare, zie e sorelle potevano coabitare con i loro congiunti senza mettere a rischio i loro diritti
Lysyl oxidase activity and elastin/glycosaminoglycan interactions in growing chick and rat aortas
No full textHydrophobic tropoelastin molecules aggregate in vitro in physiological conditions and form fibers very similar to natural ones (Bressan, G.M., I. Pasquali Ronchetti, C. Fornieri, F. Mattioli, I. Castellani, and D. Volpin, 1986, J. Ultrastruct. Molec. Struct. Res., 94:209-216). Similar hydrophobic interactions might be operative in in vivo fibrogenesis. Data are presented suggesting that matrix glycosaminoglycans (GAGs) prevent spontaneous tropoelastin aggregation in vivo, at least up to the deamination of lysine residues on tropoelastin by matrix lysyl oxidase. Lysyl oxidase inhibitors beta-aminopropionitrile, aminoacetonitrile, semicarbazide, and isonicotinic acid hydrazide were given to newborn rats, and the ultrastructural alterations of the aortic elastic fibers were analyzed and compared with the exent of the enzyme inhibition. When inhibition was >65% all chemicals induced alterations of elastic fibers in the form of lateral aggregates of elastin, which were always permeated by cytochemically and immunologically recognizable GAGs. The number and size of the abnormal elastin/GAGs aggregates were proportional to the extent of lysyl oxidase inhibition. The phenomenon was independent of the animal species. All data suggest that, upon inhibition of lysyl oxidase, matrix GAGs remain among elastin molecules during fibrogenesis by binding to positively charged amino groups on elastin. Newly synthesized and secreted tropoelastin has the highest number of free epsilon amino groups, and, therefore, the highest capability of binding to GAGs. These polyanions, by virtue of their great hydration and dispersing power, could prevent random spontaneous aggregation of hydrophobic tropoelastin in the extracellular space
A new method for the cytofluorometric analysis of mitochondrial membrane potential using the J-aggregate forming lipophilic cation 5,5’,6,6’-tetrachloro-1,1’,3,3’-tetraethylbenzim idazolcarbocyanine iodide (JC-1)
No full textA new method for the cytofluorimetric analysis of mitochondrial membrane potential in intact cells has been developed by using the lipophilic cationic probe 5,5’,6,6’-tetrachloro-1,1’,3,3’-tetraethylbenzim idazolcarbocyanine iodide (JC-1), whose monomer emits at 527 nm after excitation at 490 nm. Depending on the membrane potential, JC-1 is able of forming J-aggregates that are associated with a large shift in emission (590 nm). The color of the dye changes reversibly from green to greenish orange as the mitochondrial membrane becomes more polarized. In two human cell lines (K562 and U937), we have studied by flow cytometry the changes in membrane potential provoked by the K+ ionophor valinomycin, a drug known to affect mitochondrial membrane potential, while the K+/H+ ionophor nigericin, known to affect intracellular pH but not mitochondrial membrane potential, was used as control. The incubation with valinomycin for 10 min. at 37°C in a low K+ medium provoked a marked and dose-dependent reduction in JC-1 greenish orange fluorescence, while nigericin had no effect. © 1993 Academic Press, Inc
Going Beyond Counting First Authors in Author Co-citation Analysis
No full textThe present study examines one of the fundamental aspects of author co-citation analysis (ACA) - the way co-citation
counts are defined. Co-citation counting provides the data on which all subsequent statistical analyses and mappings
are based, and we compare ACA results based on two different types of co-citation counting - the traditional type that
only counts the first one among a cited work's authors on the one hand and a non-traditional type that takes into
account the first 5 authors of a cited work on the other hand. Results indicate that the picture produced through this non-traditional author co-citation counting contains more coherent author groups and is therefore considerably clearer. However, this picture represents fewer specialties in the research field being studied than that produced through the traditional first-author co-citation counting when the same number of top-ranked authors is selected and analyzed. Reasons for these effects are discussed
Technical Note: Artificial insemination in rabbits: laboratory and field trial with three different semen extenders
No full text[EN] Today a great deal of research is focused on the development of new extenders that allow the refrigeration and maintenance of rabbit semen for a longer period of time. In this study, semen diluted with 3 different extenders (A, B, and C) and stored at two different temperatures (4°C and 38°C) were evaluated using both laboratory and in vivo tests. The best results were obtained with extender C (INRA 96) which, in the first 10 h of the test at 4°C, displayed about 80% higher motility compared to the other two extenders and preserved optimal seminal fluid motility for over 34 h after dilution. In the test at 38 °C, the motility of semen diluted with extender C was 52% in the fifth h vs 21% of the semens diluted with extenders A (Lepus) and B (Verdunnungsmischung). Another test involved artificial insemination (AI) of 1800 lactating does using refrigerated semen diluited with the extenders under study. The fertility rate and litter size obtained with semen diluted with extender C was higher (78.1% and 8.65, respectively) than those obtained with extenders A (71.2% and 8.15, respectively) and B (71.05% and 8.13, respectively) in both parallel and sequential tests. In conclusion, extender C offers greater vitality and motility to rabbit spermatozoa, thus higher fertility rates to rabbits does.Carluccio, A.; Robbe, D.; De Amicis, I.; Contri, A.; Tosi, U.; Russo, F.; Paoletti, M. (2004). Technical Note: Artificial insemination in rabbits: laboratory and field trial with three different semen extenders. World Rabbit Science. 12(2):65-79. https://doi.org/10.4995/wrs.2004.580SWORD657912
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