49 results on '"M, Maestri"'
Search Results
2. Comparing surgery versus sorafenib in advanced hepatocellular carcinoma: An Italian weighted study
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S. Famularo, M. Donadon, F. Cipriani, F. Giuliante, A. Ferrero, S. Molfino, R. Dalla Valle, M. Chiarelli, M. Maestri, E. Jovine, G.L. Grazi, A. Ruzzenente, R. Memeo, M. Crespi, A. Antonucci, D.P. Bernasconi, F. Romano, G. Griseri, L. Aldrighetti, G. Torzilli, F. Trevisani, and on behalf of ITA.LI.CA. Group and HE.RC.O.LE.S. Group
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Oncology ,Sorafenib ,medicine.medical_specialty ,Hepatology ,business.industry ,Internal medicine ,Hepatocellular carcinoma ,Gastroenterology ,medicine ,business ,medicine.disease ,medicine.drug - Published
- 2021
3. Suivi du déploiement et évaluation de l’emploi accompagné en France
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S. Roussey and M. Maestri
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- 2019
4. TRANSPLANTATION BASIC SCIENCE, ALLOGENIC AND XENOGENIC TOLERANCE
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L. Berthelot, T. Robert, T. Tabary, V. Vuiblet, M. Drame, O. Toupance, P. Rieu, R. C. Monteiro, F. Toure, S. Ferrario, V. Cantaluppi, M. De Lena, S. Dellepiane, S. Beltramo, M. Rossetti, A. M. Manzione, M. Messina, M. Gai, C. Dolla, L. Biancone, G. Camussi, P. Pontrelli, A. R. Oranger, M. Accetturo, F. Rascio, M. Gigante, G. Castellano, A. Schena, M. Fiorentino, A. Zito, G. Zaza, G. Stallone, L. Gesualdo, G. Grandaliano, E. F. Pattonieri, M. Gregorini, V. Corradetti, C. Rocca, S. Milanesi, A. Peloso, J. Ferrario, M. Cannone, F. Bosio, N. Maggi, M. A. Avanzini, P. Minutillo, M. Paulli, M. Maestri, T. Rampino, A. Dal Canton, K. S. T. Wu, O. Coxall, Y. Luque, S. Candon, M. Rabant, L.-H. Noel, E. Thervet, L. Chatenoud, R. Snanoudj, D. Anglicheau, C. Legendre, J. Zuber, P. Hruba, I. Brabcova, E. Krepsova, J. Slatinska, A. Sekerkova, I. Striz, R. Zachoval, O. Viklicky, T. M. Scholbach, H.-K. Wang, C.-C. Loong, A.-H. Yang, T.-H. Wu, H. Guberina, V. Rebmann, P. Dziallas, S. Dolff, J. Wohlschlaeger, F. M. Heinemann, O. Witzke, Y. M. Zoet, F. H. J. Claas, P. A. Horn, A. Kribben, I. I. N. Doxiadis, N. Prasad, B. Yadav, V. Agarwal, A. Jaiswal, M. Rai, C. M. Hope, P. T. Coates, P. S. Heeger, R. Carroll, V. Masola, M. F. Secchi, M. Onisto, G. Gambaro, A. Lupo, M. Matsuyama, T. Kobayashi, Y. Yoneda, J. Chargui, J. L. Touraine, R. Yoshimura, D. Vizza, A. Perri, S. Lupinacci, G. Toteda, D. Lofaro, F. Leone, P. Gigliotti, A. La Russa, T. Papalia, R. Bonofilgio, A. Sentis Fuster, J. Kers, U. Yapici, N. Claessen, F. J. Bemelman, I. J. M. Ten Berge, S. Florquin, D. Glotz, L. Rostaing, J.-P. Squifflet, P. Merville, C. Belmokhtar, G. Le Ny, Y. Lebranchu, D. A. Papazova, M. Friederich-Persson, M. P. Koeners, J. A. Joles, M. C. Verhaar, H. L. Trivedi, A. V. Vanikar, S. D. Dave, B. Suarez Alvarez, S. Garcia Melendreras, R. Carvajal Palao, C. Diaz Corte, M. Ruiz Ortega, C. Lopez-Larrea, A. K. Yadav, D. Bansal, V. Kumar, M. Minz, V. Jha, D. Kaminska, K. Koscielska-Kasprzak, P. Chudoba, O. Mazanowska, M. Banasik, M. Zabinska, M. Boratynska, A. Lepiesza, K. Korta, M. Klinger, R. Csohany, A. Prokai, D. Pap, N. Balicza-Himer, A. Vannay, A. Fekete, K. Kis-Petik, J. Peti-Peterdi, A. Szabo, A. Masajtis-Zagajewska, K. Muras, M. Niewodniczy, M. Nowicki, J. Pascual, T. R. Srinivas, S. Chadban, F. Citterio, M. Henry, F. Oppenheimer, P.-C. Lee, H. Tedesco-Silva, M. Zeier, Y. Watarai, G. Dong, M. Hexham, P. Bernhardt, F. Vincenti, M. T. Rocchetti, J. Su owicz, A. Wojas-Pelc, E. Ignacak, K. Janda, M. Krzanowski, W. Su owicz, M. Mitsuhashi, T. Murakami, A. Benso, D. Leuning, M. Reinders, E. Lievers, J. Duijs, A. J. Van Zonneveld, C. Van Kooten, M. Engelse, T. Rabelink, A. Assounga, S. Omarjee, Z. Ngema, A. Ersoy, A. Gultepe, E. Isiktas Sayilar, H. Akalin, F. Coskun, M. Oner Torlak, Y. Ayar, M. Riegersperger, M. Plischke, C. Steinhauser, A. Jallitsch-Halper, G. Sengoelge, W. C. Winkelmayer, G. Sunder-Plassmann, M. Foedinger, M. Kaziuk, M. Kuz'Niewski, A. B Tkowska- Prokop, K. Pa Ka, P. Dumnicka, W. Kolber, and W. Su Owicz
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Transplantation ,medicine.medical_specialty ,Nephrology ,business.industry ,Basic science ,medicine ,Intensive care medicine ,business - Published
- 2014
5. Highly efficient organic electroluminescent devices based on cyclometallated platinum complexes as new phosphorescent emitters
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Jan Kalinowski, D. Virgili, M. Maestri, Massimo Cocchi, P. Di Marco, C. Sabatini, Valeria Fattori, M. Cocchi, D. Virgili, C. Sabatini, V. Fattori, P. Di Marco, M. Maestri, and J. Kalinowski
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Materials science ,Mechanical Engineering ,Metals and Alloys ,chemistry.chemical_element ,Quantum yield ,Electroluminescence ,Condensed Matter Physics ,Photochemistry ,Electronic, Optical and Magnetic Materials ,chemistry.chemical_compound ,chemistry ,Mechanics of Materials ,Pyridine ,Materials Chemistry ,OLED ,Platinum complex ,Chromaticity ,Platinum ,Phosphorescence - Abstract
High efficiency electroluminescence (EL) in organic light emitting diodes (OLED) was achieved using cyclometallated platinum(II) complexes as new phosphorescent emitters. OLEDs containing bis[2-(2-thienyl)pyridine]platinum(II) [Pt(thpy)2] or bis[2-(5-trimethylsilanyl-2-thienyl)-pyridine]platinum(II) [Pt(thpy-SiMe3)2] show a high external EL quantum yield reaching 5.4 and 11.5% photon/electron, respectively. Both electroluminescent spectra fall in the “amber” color region defined by the automotive lighting standards; specifically the CIE coordinates are (0.58; 0.42) for Pt(thpy)2 and (0.60; 0.39) for Pt(thpy-SiMe3)2.
- Published
- 2004
6. Incidence of HIV Type 1 Infection, Antiretroviral Drug Resistance, and Molecular Characterization in Newly Diagnosed Individuals in Argentina: A Global Fund Project
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M. Vila, Rubén Marone, M.S. dos Ramos Farias, G. Ralón, J Sosa, M. Maestri, Andrea E. Rubio, María M. Avila, María A. Pando, Horacio Salomón, Manuel Gómez-Carrillo, Moira Vignoles, Elena Reynaga, D. Rossi, and Oscar B. Torres
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Adult ,Male ,medicine.medical_specialty ,Genotype ,Epidemiology ,Substance-Related Disorders ,Immunology ,Population ,Argentina ,Human immunodeficiency virus (HIV) ,Sex workers ,HIV Infections ,Drug resistance ,Newly diagnosed ,medicine.disease_cause ,Men who have sex with men ,Serology ,Pregnancy ,Virology ,Internal medicine ,Drug Resistance, Viral ,Cluster Analysis ,Humans ,Medicine ,Homosexuality, Male ,Pregnancy Complications, Infectious ,education ,Phylogeny ,education.field_of_study ,Reverse Transcriptase Polymerase Chain Reaction ,business.industry ,Incidence ,Incidence (epidemiology) ,virus diseases ,Sequence Analysis, DNA ,Sex Work ,Infectious Diseases ,Anti-Retroviral Agents ,pol Gene Products, Human Immunodeficiency Virus ,HIV-1 ,RNA, Viral ,Female ,business - Abstract
An HIV incidence estimation was performed among men who have sex with men (MSM), drug users (DUs), sex workers (SWs), and pregnant women (PW) from Argentina. Volunteers older than 18 years old without a previous HIV-positive diagnosis were included. HIV-positive samples were analyzed by the Serological Testing Algorithm for Recent HIV Seroconversion (STARHS) to estimate incidence. By partial RT-PCR and sequencing of the HIV pol gene, an HIV subtype and resistance profile were determined. A total of 12,192 volunteers were recruited from October 2006 to September 2008. A higher HIV prevalence was detected among trans SWs (33.9%, 38/112), male SWs (10.8%, 12/111), and MSM 10.4% (161/1549). HIV incidence estimates by STARHS was also higher on trans SWs (11.31 per 100 person-years), male SWs (6.06 per 100 person-years), and MSM (6.36 per 100 person-years). Antiretroviral primary resistant mutations were detected in 8.4% of the study group, with a higher frequency in female DUs (33.3%). Phylogenetic analysis showed that 124 (57.9%) samples were subtype B, 84 (39.3%) intersubtype BF recombinants, 5 (2.3%) subtype C, and 1 (0.5%) subtype F in the pol region. Subtype B was most commonly found in MSM and male SWs whereas the intersubtype BF recombinant was more prevalent in female DUs, female SWs, and PW. Given the high HIV prevalence and incidence found in most of these groups, monitoring the continuing spread of the HIV epidemic is essential for determining public health priorities, assessing the impact of interventions, and estimating current and future health care needs.
- Published
- 2011
7. Walnut and almond oil screw-press extraction at industrial scale: Effects of process parameters on oil yield and quality
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M. L. Martínez, M. G. Bordón, R. M. Bodoira, M. C. Penci, P. D. Ribotta, and D. M. Maestri
- Subjects
business.product_category ,Screw-press extraction ,Aceite de nuez ,Almond oil ,Rendimiento de aceite ,Walnut oil ,Parámetros de calidad química ,Oil recovery ,Chemical quality parameters ,Aceite de almendra ,Extracción por prensado ,lcsh:TX341-641 ,0404 agricultural biotechnology ,Screw press ,TX341-641 ,Solid content ,Water content ,ALMOND OIL ,Mathematics ,Nutrition. Foods and food supply ,Organic Chemistry ,Industrial scale ,Extraction (chemistry) ,04 agricultural and veterinary sciences ,Pulp and paper industry ,040401 food science ,Yield (chemistry) ,business ,lcsh:Nutrition. Foods and food supply ,Food Science - Abstract
Walnut and almond kernels are highly nutritious mainly due to their high oil contents. In this study, 32 factorial experimental designs were used to optimize processes for oil extraction by screw-pressing at industrial scale. Experimental designs included seed moisture content (SMC), and restriction die (RD) as the main processing parameters. Theoretical models were scanned against experimental data in order to optimize oil extraction conditions. The response variables analyzed were oil yield (OY), fine solid content (FC) in oil, and oil quality parameters. Fitted models for OY indicated maximum predicted values similar to the highest experimental values. Walnut oil extractions showed a maximum OY (84.5 ± 2.3 %) at 7.21% SMC, and 10 mm RD. For almond kernels, maximum OY (71.9 ± 3.5%) was obtained at 9.42% SMC, and 12 mm RD. Chemical quality parameters from both oils were in the ranges stated in Codex (FAO/WHO) standards for virgin (non-refined) oils. Extracción de aceite de nuez y almendra a escala industrial: efecto de parámetros del proceso sobre el rendimiento y la calidad del aceite. La nuez y almendra son frutos sumamente nutritivos debido a su alto contenido de aceite. Mediante un diseño experimental de tipo factorial 32 se optimizó el proceso de extracción de estos aceites con prensa de tornillo a escala industrial. Las variables de proceso analizadas fueron el contenido de humedad de la semilla (CHS) y el diámetro de reducción (DR). Los modelos ajustados para rendimiento de aceite (RA) indicaron valores máximos predichos similares a los valores experimentales. Las extracciones de aceite de nuez mostraron un RA máximo (84,5 ± 2,3%) a 7,21% CHS, y 10 mm DR. Para almendra, se obtuvo un máximo de RA (71,9 ± 3,5%) con 9,42% de CHS y 12 mm de DR. Los parámetros de calidad química de ambos aceites se encontraban en los rangos establecidos en las normas del Codex (FAO / OMS) para aceites vírgenes (no refinados).
- Published
- 2018
- Full Text
- View/download PDF
8. Lipoxygenase-1 Activity of Soybean Genotypes Grown in Argentina
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J. M. Meriles, D. M. Maestri, and C. A. Guzmán
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Organic Chemistry ,Pharmaceutical Science ,Biology ,Analytical Chemistry ,lcsh:QD241-441 ,Crop ,Lipoxygenase ,n/a ,lcsh:Organic chemistry ,Agronomy ,Chemistry (miscellaneous) ,Drug Discovery ,Genotype ,biology.protein ,Molecular Medicine ,Cultivar ,Physical and Theoretical Chemistry - Abstract
The lipoxygenase-1 (LOX-1) activity of 19 soybean genotypes was quantified in two consecutive years. The LOX-1 activity produced by any cultivar was essentially the same in both, 1995 and 1996 crop years. The lowest values of LOX-1 activity were found in NK 555 cultivar whereas Asgrow 5409 cultivar had the highest values.
- Published
- 2000
9. Photosynthetic oxygen evolution by fourCoffea arabicagenotypes subjected to a dehydration/rehydration cycle
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A.-A. F. De Almeida and M. Maestri
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AMAX ,Coffea arabica ,Carbon fixation ,Oxygen evolution ,Plant Science ,Biology ,medicine.disease ,Photosynthesis ,Horticulture ,Dehydration rehydration ,Botany ,medicine ,Dehydration ,Hybrid - Abstract
SummaryPhotosynthetic oxygen evolution by eight month old plants of the Coffea arabica hybrids H-421 (cv. Yellow Catuai × cv. Timor Hybrid) and H-430 (cv. Red Catuai × cv. Timor Hybrid), a Catimor progeny, and one line of cv. Red Catuai was followed polarographically during a dehydration/rehydration cycle. Fully hydrated plants showed a maximum photosynthetic rate (Amax) in the range of 20.6 to 34.6 µmol m−2 s−1 and an apparent quantum yield of 0.074 to 0.086. During dehydration Amax steadily decreased as the water potential declined. Changes were not found among the slope and the intercept values, with the exception of the slope value of hybrid H-421. The recovery was regained 96.0, 96.5, 85.0 and 78.0 h after rehydration for the genotypes Catimor, H-430, Catuai and H-421, respectively. In response to stress, the mesophyll resistance restricts carbon dioxide fixation, with after-effects of variable duration.
- Published
- 1997
10. [Obstructive sleep apnea syndrome in bus drivers: clinical and polysomnographic study]
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M, Maestri, F, Cosentino, E, Di Coscio, E, Iacopini, L, Carnicelli, R, Buselli, S, Garbarino, A, Cristaudo, and E, Bonanni
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Adult ,Male ,Automobile Driving ,Sleep Apnea, Obstructive ,Polysomnography ,Humans ,Female ,Occupational Health - Abstract
A Questionnaire on sleep and vigilance disorders has been developed by the Italian Association of Sleep Medicine to help the occupational health physicians in screening for sleep disorders. Aim of this study was to compare the Questionnaire with standardized questionnaires for sleepiness and sleep apnea and with a polysomnographic evaluation. Four hundred sixty-three (463#) commercial bus drivers (454M, 9F; mean age +/- S.D. 41.6 +/- 8.1 yrs; mean body mass index 26.2 +/- 3.6 kg/m2) underwent clinical evaluation that included the Italian Association of Sleep Medicine Questionnaire on sleep and vigilance disorders and two standardized questionnaires (Berlin Questionnaire and Epworth Sleepiness Scale). According to the Italian Association of Sleep Medicine Questionnaire on sleep and vigilance disorders 40 subjects presented an high risk for sleep disturbance and in 28 subject the questionnaires were concordant. Preliminary results (16 patients) showed an high rate of concordance between questionnaire and PSG. These data strongly suggest that sleep disorders and symptoms, that are frequent in a population of professional bus drivers, should be better evaluated during occupational health visit.
- Published
- 2013
11. The effect of beta-blockade therapy on the response to exercise training in postmyocardial infarction patients
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G Orlando, Jonathan Myers, C Rusconi, M Maestri, and Pavia L
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Adult ,Male ,medicine.medical_specialty ,Adrenergic beta-Antagonists ,Myocardial Infarction ,Infarction ,Physical exercise ,Angina ,Electrocardiography ,Internal medicine ,medicine ,Humans ,Myocardial infarction ,Aged ,Metoprolol ,medicine.diagnostic_test ,business.industry ,Hemodynamics ,General Medicine ,Middle Aged ,medicine.disease ,Exercise Therapy ,Respiratory Function Tests ,Surgery ,Blockade ,Cardiology ,Female ,Cardiology and Cardiovascular Medicine ,Ventilatory threshold ,business ,medicine.drug - Abstract
Cardiac rehabilitation after a myocardial infarction has been shown to improve exercise capacity. Beta blockade has been shown to be effective in treating angina and reducing mortality, but studies are controversial as to whether beta-blockade therapy attenuates the effects of training. We attempted to study the effects of beta blockade (metoprolol) on the response to training in patients enrolled in a cardiac rehabilitation program after an uncomplicated myocardial infarction. We studied 27 patients with a recent uncomplicated myocardial infarction who were subdivided in two groups: Group 1 (13 patients) not taking a beta blocker, and Group 2 (14 patients) taking metoprolol (mean 142 +/- 57 mg daily). All patients underwent a maximal cardiopulmonary exercise test before and after a 3-month training program. The training intensity was designed to approximate the ventilatory threshold. Results showed an increase in peak VO2 in both Group 1 (27%, p < 0.01) and Group 2 (33%, p < 0.001), and an increase in VO2 at the ventilatory threshold (39% in Group 1 and 28% in Group 2, p < 0.01). The mean changes in exercise capacity were not different between groups. It was concluded that metoprolol did not influence the beneficial effects of a cardiac rehabilitation program in postmyocardial infarction patients.
- Published
- 1995
12. Effect of age and body weight of Greater Rhea (Rhea americana) females on egg number, size and composition
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Joaquin Luis Navarro, D. M. Maestri, María Lábaque, Mónica B. Martella, and L. Hoyos
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Time Factors ,Greater rhea ,Linoleic acid ,media_common.quotation_subject ,Population ,Rheiformes ,Palmitic Acid ,Body weight ,Fatty Acids, Monounsaturated ,Linoleic Acid ,chemistry.chemical_compound ,Animal science ,Seasonal breeder ,Animals ,education ,media_common ,Ovum ,education.field_of_study ,biology ,Reproduction ,Body Weight ,Age Factors ,General Medicine ,Anatomy ,biology.organism_classification ,Clutch Size ,chemistry ,Female age ,Fatty Acids, Unsaturated ,Animal Science and Zoology ,Composition (visual arts) ,Female ,Food Science - Abstract
1. A study was conducted to evaluate how body weight and age of each female are related to the number and physical and chemical characteristics of the eggs produced throughout a breeding season in a captive-bred population of Greater Rheas (Rhea americana). 2. Reproductive performance of 15 females of three age classes (5 individuals per class) was monitored; female body weight was recorded before laying-onset. All the eggs laid were collected and identified, and different morphometric variables, percentage of components and fatty acid composition were determined. 3. The earlier the female started egg-laying, the longer the laying period and the greater the overall number of eggs produced. The onset of egg-laying in turn seemed to be related to the attainment of a high body weight. 4. Except for length, the values of the morphometric variables of the egg and unsaturated fatty acids (palmitoleic, oleic and linoleic) increased with female age. 5. High body weight was associated with low palmitic and palmitoleic fatty acids and high linoleic, linolenic and total unsaturated fatty acids. 6. Live weight and age of females can determine several physical and chemical characteristics of eggs.
- Published
- 2010
13. ChemInform Abstract: Concave Macrobicycles: Absorption Spectra, Luminescence Properties, and Endocavital Complexation of Neutral Organic Guests
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K. Rissanen, V. Balzani, I. Michel, Martin Nieger, Ralf Berscheid, S. Kotila, F. Voegtle, M. Maestri, K. Airola, and Nicola Armaroli
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Absorption spectroscopy ,Chemistry ,General Medicine ,Luminescence ,Photochemistry - Published
- 2010
14. Shock III
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D. Siebenlist, W. Gattenlöhner, W. Lingnau, Ch Hörmann, Ch. Putensen, N. Mutz, L. Jacquet, J. C. Jouret, P. Henin, M. Goenen, H. Tohmo, M. Karanko, K. Korpilahti, M. Scheinin, O. Viinamäki, P. Neuvonen, A. Sabatè, R. Sopena, R. Ramòn, E. Barcelò, C. Roqueta, A. Abad, L. Garcia, X. Garcia, P. Plaisance, E. Vicaut, S. Beloucif, D. Payen, L. Pasini, G. Ortalli, C. Sorbara, D. Lagonidis, S. Magder, J. J. Guardiola, X. Sarmiento, S. Alonso, J. Nigond, C. Arich, J. P. Bertinchant, C. Bengler, J. M. Stordeur, I. M. Chandler, K. L. Stein, T. A. Gasior, R. L. Kormos, M. R. Pinsky, M. Fortuna, M. Horvat, K. Szabò, P. Burtin, M. Clavey, P. M. Mertès, B. Levy, N. Bischoff, P. Mathieu, J. P. Villemot, J. P. Haberer, A. El-Banayosy, H. Posival, K. Minami, M. M. Korner, D. Hartmann, R. Korfer, H. Kortke, G. G. Corbucci, B. Pohar, J. Osredkar, S. Kladnik, G. Bellinzona, S. Noli, A. Giordano, S. Zlzzi, M. Maestri, M. Spada, M. Raimondi, F. Albertario, R. V. Dionigi, V. D’Orio, C. Martinez, G. Saad, P. Mendes, R. Marcelle, K. H. Staupach, M. R. Losser, F. Lenfant, B. Teisseire, P. E. Bollaert, P. F. Laterre, G. Audibert, M. Evenepoel, Ph. Lelarge, A. Larcan, Ph. Bauer, L. Nace, M. C. Laprevote-Heully, M. N. Smithies, Tai Hwei Yee, L. Jackson, R. Beale, D. J. Bihari, C. Cisneros Alonso, J. Gutierrez Rodriguez, F. SAnchez Ramirez, J. Prados Varela, P. Arribas Lòpez, A. Martinez de la Gàndara, R. Boiteau, A. Tenaillon, T. Lherm, F. Chamieh, D. Perrin-Gachadoat, M. Burdin, A. M. Masquelier, M. H. Capron, A. Dougnac, M. Andresen, O. Deckers, H. Evenepoel, D. Henin, M. S. Reynaert, C. Müller, S. Probst, V. Lischke, V. Nicovani, G. Hemàndez, L. Bavestrello, L. Castillo, H. Zhang, H. Sparen, M. Benlabed, N. Nuuyen, J. L. Vincent, O. Kunitz, T. Hillermann, P. Glöckner, F. G. Müller, and G. Kalff
- Subjects
Critical Care and Intensive Care Medicine - Published
- 1992
15. Detection of arteriolar narrowing in fundoscopic examination: evidence of a low performance of direct ophthalmoscopy in comparison with a microdensitometric method
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Miguel Gus, Helena Messinger Pakter, Gerson Luis da Silva Nunes, Sandra C. Fuchs, Leila Beltrami Moreira, Ruy S. Moraes, Elton L. Ferlin, Marcelo M. Maestri, and Flávio Danni Fuchs
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Adult ,Male ,medicine.medical_specialty ,Fundus Oculi ,Direct examination ,Retinography ,Sensitivity and Specificity ,Direct Ophthalmoscopy ,Ophthalmoscopy ,Ophthalmology ,Internal Medicine ,medicine ,Photography ,Humans ,medicine.diagnostic_test ,business.industry ,Fundi examination ,Microangiopathy ,Retinal Vessels ,Middle Aged ,medicine.disease ,Predictive value ,Capillaries ,Clinical Practice ,Cardiovascular Diseases ,Hypertension ,Female ,business - Abstract
Background Retinal abnormalities, particularly arteriolar narrowing, are powerful predictors of cardiovascular events. The precision of internists and ophthalmologists in the assessment of retinal vessels widths has been disputed but not evaluated against a technology of edge detection. Methods Fifty-two patients with hypertension had optic fundi examination done by an internist and an ophthalmologist, and had retinographies taken and digitized to determine vessel diameters by a new technology of edge detection (microdensitometric method). Physicians asserted the presence of arteriolar narrowing (≤0.67) through direct ophthalmoscopy and projected retinography. The microdensitometric method measures automatically the vessel widths based on the subpixel resolution of the edge of vessel walls. Sensitivity (SE), specificity (SP), positive (PPV) and negative predictive values (NPV), and kappa statistics were calculated, taken the microdensitometric method as reference. Results The performance of the direct examination by the internist to detect arteriolar narrowing was SE: 68.7 (67.0–70.4); SP: 72.7 (68.0–77.4); PPV: 88.0 (85.9–90.0); and NPV: 44.4 (41.5–47.4). For the ophthalmologist the figures were: SE: 74.4 (72.9–75.7); SP: 53.8 (49.8–57.8); PPV: 82.9 (81.3–84.4); and NPV: 41.2 (38.0–44.3). Kappa statistics were 0.34 (0.07–0.62) for the internist, and 0.26 (−0.03–0.53) for the ophthalmologist. Conclusions The performance of internists and ophthalmologists to detect hypertensive microangiopathy based on low arteriolar venous ratio is low and casts doubt about the usefulness of this examination in clinical practice.
- Published
- 2006
16. Physical characteristics and chemical composition of Lesser Rhea (Pterocnemia pennata) eggs from farmed populations
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D. M. Maestri, Fernando Rafael Barri, Joaquin Luis Navarro, Mónica B. Martella, and D.O. Labuckas
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food.ingredient ,Ovalbumin ,Eggs ,Oviposition ,Rheiformes ,Argentina ,Biology ,chemistry.chemical_compound ,food ,Pterocnemia ,Species Specificity ,Yolk ,Botany ,Animals ,Food science ,Chemical composition ,Monounsaturated fatty acid ,chemistry.chemical_classification ,Lesser rhea ,film.editor ,Cholesterol ,Fatty Acids ,General Medicine ,Egg Yolk ,Whole egg ,chemistry ,film ,Animals, Domestic ,Fatty Acids, Unsaturated ,lipids (amino acids, peptides, and proteins) ,Animal Science and Zoology ,Female ,Food Science ,Polyunsaturated fatty acid - Abstract
1. Eggs from 4 farmed populations of Lesser Rhea (Pterocnemia pennata) were studied to determine their physical and chemical characteristics. 2. None of the physical variables (weight of whole egg, yolk, albumen and shell; proportion of yolk based on egg content; proportion of shell based on entire egg weight; volume; density) showed significant differences between populations. 3. Among chemical variables, moisture, both saturated fatty acids (palmitic 16 : 0 and stearic 18 : 0), one monounsaturated fatty acid (palmitoleic 16:1), and one polyunsaturated fatty acid (arachidonic 20 : 4), did not differ between populations, whereas other variables (protein, lipid and ash contents; fatty acids: oleic 18 : 1, linoleic 18 : 2, linolenic 18 : 3; PUFA; PUFA/SFA; cholesterol) differed significantly.
- Published
- 2003
17. Physical characteristics and chemical composition of Greater Rhea (Rhea americana) eggs from wild and captive populations
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María L. López, Joaquin Luis Navarro, D. M. Maestri, and D.O. Labuckas
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Greater rhea ,biology ,Ecology ,Linolenic acid ,Eggs ,Egg Proteins ,Rheiformes ,Egg protein ,Zoology ,Animals, Wild ,General Medicine ,biology.organism_classification ,Lipids ,Egg Shell ,Cholesterol ,Animals, Domestic ,Animals ,Animal Science and Zoology ,Eggshell ,Chemical composition ,Food Science - Abstract
1. Eggs from wild and captive populations of Greater Rhea (Rhea americana) were studied to determine their physical and chemical characteristics. 2. Significant differences were found among populations in almost all chemical parameters studied, whereas within physical parameters only shell weight (as a proportion of the entire egg) and density showed differences. 3. Eggs from wild populations had the highest protein and linolenic acid and the lowest total lipid contents, while cholesterol levels of these eggs and of those from the largest captive area were the lowest.
- Published
- 2002
18. Oxygen Delivery and Oxygen Tension in Cerebral Tissue During Global Cerebral Ischaemia: A Swine Model
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G. Bellinzona, M. Maestri, M. Balestreri, Diego Spagnoli, Nino Stocchetti, P. Bruzzone, Sandra Rossi, and V. Valeriani
- Subjects
business.industry ,medicine.medical_treatment ,chemistry.chemical_element ,Laser Doppler velocimetry ,Oxygen ,Oxygen tension ,medicine.anatomical_structure ,nervous system ,Cerebral blood flow ,chemistry ,Ventricle ,Anesthesia ,cardiovascular system ,medicine ,Arterial line ,Cerebral perfusion pressure ,business ,Saline ,circulatory and respiratory physiology - Abstract
Interest in tissue oxygen (PtiO2) monitoring is increasing. However the exact interactions between ptiO2, systemic and cerebral variables are a matter of debate. Particularly, the relationship between ptiO2, cerebral oxygen supply and consumption needs to be clarified. We designed a model to achieve progressive Cerebral Blood Flow (CBF) reduction through 3 steps: 1. baseline, 2. CBF between 50–60% of the baseline, 3. CBF < 30% of the baseline. In 7 pigs, under general anaesthesia, Cerebral Perfusion Pressure (CPP) and CBF were reduced through the infusion of saline in a lateral ventricle. PtiO2 and CBF were monitored respectively through a Clark electrode (Licox, GMS) and laser doppler (Peri-Flux). Blood from superior sagittal sinus and from an arterial line was simultaneously drawn to calculate the artero-venous difference of oxygen (AVD02). Brain oxygen supply was calculated by multiplying relative CBF change and arterial oxygen content. Pti02 reflected CBF reductions, as it was 27.95 (±10.15) mmHg during the first stage of intact CBF, declined to 14.77 (±3.58) mmHg during the first CBF reduction, declined to 3.45 (±2.89) mmHg during the second CBF reduction and finally fell to 0 mmHg when CBF was completely abolished. CBF changes were also followed by a decline in 02 supply and a parallel increase in AVD02. Conclusion: this model allows stable and reproducible steps of progressive CBF reduction in which ptiO2 changes can be studied together with oxygen supply and consumption.
- Published
- 2000
19. Insulin-like growth factor-I ameliorates delayed kidney graft function and the acute nephrotoxic effects of cyclosporine
- Author
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M, Maestri, D C, Dafoe, G A, Adams, A, Gaspari, F, Luzzana, F, Innocente, J, Rademacher, P, Dionigi, A, Barbieri, F, Zonta, A, Zonta, and R, Rabkin
- Subjects
Graft Rejection ,Rats, Inbred Lew ,Cyclosporine ,Animals ,Rats, Inbred WF ,Transplantation, Homologous ,Drug Synergism ,Kidney Diseases ,Insulin-Like Growth Factor I ,Kidney Transplantation ,Peptide Fragments ,Rats - Abstract
Delayed graft function (DGF) is a relatively common complication after cadaveric renal transplantation. The adverse effect of DGF on long-term graft survival has lead to intensive efforts to reduce ischemic graft injury. In this study we examined the effects of a new protective treatment based on insulin growth factor (IGF)-I. We evaluated the impact of the treatment on renal recovery and on the nephrotoxicity that is a common side effect of mainstream immunosuppressants. Because therapy with IGF-I or the analog des(1-3)IGF-I is effective in treating experimental ischemic renal failure, these peptides may be useful as perspective clinical treatments.We have addressed three areas relating to the potential use of IGF-I and its analog des(1-3)IGF-I. First, because of the immunogenic properties of IGF-I, we assessed the effect of des(1-3)IGF-I on the rejection of skin allografts in Lewis rats. Next we determined whether treatment with des(1-3)IGF-I influences the early function of transplanted kidneys in a model of DGF induced by a combination of warm and cold ischemia. Finally we tested whether IGF-I protects against acute cyclosporine nephrotoxicity.Des(1-3)IGF-I did not accelerate the rejection of the skin grafts (P=0.57). The administration of this peptide in a model of syngenic renal transplant improved the early function of the graft. Postoperative values of creatinine and blood urea nitrogen were significantly better (P0.05) in treated animals. IGF-I also ameliorated the nephrotoxicity of cyclosporine, with better values of creatinine and blood urea nitrogen (P0.05).In evaluating this study it should be recognized that the animal models studied, although widely used, differ from the human condition. However, IGF-I and des(1-3)IGF-I exhibit properties that strongly suggest their value in preventing clinical DGF, and they deserve further studies.
- Published
- 1997
20. Empleo de aceites esenciales como antioxidantes naturales
- Author
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J. A. Zydgalo, A. L. Lamarque, D. M. Maestri, and N. R. Grosso
- Subjects
Aceite esencial ,Nutrition. Foods and food supply ,soybean oil ,antioxidant effect ,TX341-641 ,Efecto antioxidante ,Antioxidant effect ,Aceite de soja ,essential oil ,Essential oil ,Soybean oil - Abstract
The aims of this study were to determine and compare the antioxidant effect of essential oils from Thymus vulgaris, Laurus nobilis, Foeniculum vulgare, Eucalyptus globules, Tagetes minuta, Satureja parvifolia and Lippia polystachya in soybean oil. The concentrations of volatile oils in soybean oil were 0.1% and 0.02%. The antioxidant activity was measured by peroxide values. Thymus vulgaris and L. nobilis essential oils exhibited a significant antioxidant activity, followed by F. vulgare and E. globules in a decreasing order. Tagetes minuta, S. parvifolia and L. polystachya had not effect, and their contribution to the stability of soybean oil was negligible. Los objetivos de este estudio fueron determinar y comparar el efecto antioxidante de los aceites esenciales de Thymus vulgaris, Laurus nobilis, Foeniculum vulgare, Eucalyptus globulus, Tagetes minuta, Satureja parvifolia y Lippia polystachya en el aceite de soja. Las concentraciones de las esencias en el aceite de soja fueron 0.1% y 0.02%. La actividad antioxidante fue medida por los valores de peróxido. Los aceites esenciales de T. vulgaris y L nobilis exhibieron una significativa acción antioxidante seguidos, en orden decreciente, por F. vulgare y E. globulus. Las esencias de T. minuta, S. parvifolia y L polystachya no mostraron efecto antioxidante y su contribución a la estabilidad oxidativa del aceite de soja fue despreciable.
- Published
- 1995
- Full Text
- View/download PDF
21. Intermolecular Energy and Electron Transfer Processes
- Author
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M. Maestri and V. Balzani
- Subjects
Electron transfer ,Quenching (fluorescence) ,Materials science ,Excited state ,Intermolecular force ,Proton-coupled electron transfer ,Absorption (electromagnetic radiation) ,Luminescence ,Photochemistry ,Photoinduced electron transfer - Abstract
The first act of any photochemical and photophysical process is the absorption of a photon by a molecule (equation (1)). The excited state that $$A+hv\to*A$$ (1) is formed in this way is a high energy, unstable species which must undergo some type of deactivation [1]. As shown in figure 1, excited state deactivation can occur via (i) disappearance of the original molecule and formation of products (photochemical reaction), (ii) emission of light (radiative deactivation, also called luminescence), (iii) degradation of excess energy into heat (nonradiative deactivation), and (iv) some type of interaction with other species present in the solution (quenching processes).
- Published
- 1993
22. Luminescence of ortho-metallated platinum(II) complexes
- Author
-
M Maestri
- Subjects
chemistry ,chemistry.chemical_element ,Platinum ,Luminescence ,Photochemistry - Published
- 1985
23. Reactivity of trans-β-styrylnaphthalene photosensitized by tris(2,2′-bipyridine)chromium(III)
- Author
-
D. Sandrini, L. Moggi, and M. Maestri
- Subjects
Singlet oxygen ,General Chemical Engineering ,Radical ,Cationic polymerization ,General Physics and Astronomy ,General Chemistry ,Photochemistry ,Cis trans isomerization ,2,2'-Bipyridine ,chemistry.chemical_compound ,Electron transfer ,chemistry ,Reactivity (chemistry) ,Isomerization - Abstract
On photosensitization by tris(2,2′-bipyridine)chromium(III), trans -β-styrylnaphthalene undergoes geometrical isomerization and (in the presence of dioxygen) oxidation to benzaldehyde and naphthaldehyde. Whereas oxidation seems to be due to attack by singlet oxygen, isomerization originates from a cationic radical of the olefin, formed in an electron transfer to be excited complex. The reactivity of such a radical is compared with those of triplet excited states and anionic radicals of stilbene derivatives.
- Published
- 1984
24. Water stress and dormancy release in flower buds ofCoffea arabicaL. : Water movement into the buds
- Author
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M. de M. Estevao, E. D. Astegiano, and M. Maestri
- Subjects
genetic structures ,Tritiated water ,Bud ,Coffea arabica ,fungi ,Water stress ,food and beverages ,chemistry.chemical_element ,Plant Science ,Calcium ,Biology ,chemistry.chemical_compound ,chemistry ,Botany ,Dormancy - Abstract
SummaryUsing tritiated water and 45Ca as tracers, the effect of the subtending leaf and of water stress on the movement of water and calcium to flower buds of coffee during dormancy release was studied. Either the subtending leaf or water stress enhanced the mobilization of water and calcium towards the flower buds. The mobilization of water and calcium to buds was greater in plants that had experienced a drought period. A water stress period is apparently essential to release the buds from dormancy, but neither the subtending leaf nor the water potential gradient from the leaf subtending the flower bud clearly affected the phenomenon.
- Published
- 1988
25. Temperature dependence of electronic energy transfer to chromium(III) complexes. Evidence for the rate-determining effect of the preexponential factor
- Author
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D. Sandrini and M. Maestri
- Subjects
Chromium ,chemistry ,Radiochemistry ,General Engineering ,Physical chemistry ,chemistry.chemical_element ,Electronic energy transfer ,Physical and Theoretical Chemistry - Published
- 1981
26. Assessment of left ventricular filling in patients with systemic hypertension. A Doppler echocardiographic study
- Author
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P, Faggiano, C, Rusconi, G, Orlando, L, Pavia, G, Ghizzoni, M, Maestri, A, Gardini, U, Simoncelli, and A, Sorgato
- Subjects
Adult ,Male ,Diastole ,Heart Ventricles ,Hypertension ,Humans ,Female ,Middle Aged ,Myocardial Contraction ,Echocardiography, Doppler ,Aged - Abstract
To assess left ventricular (LV) diastolic function in patients with hypertension, a Doppler echocardiographic study of transmitral blood flow (TBF) was performed in 46 hypertensive patients (H), 18 without (H1) and 28 with (H2) left ventricular hypertrophy and in 25 age-matched normal subjects (N). All patients showed normal systolic function. The following indices of Doppler TBF were measured: peak flow velocity during early filling (Evel), atrial systole (Avel) and their ratio (E/Avel); area under early filling phase (Earea), area under atrial systole (Aarea), expressed as a percentage of total diastolic area and their ratio (E/Aarea); deceleration half-time (DHT) of early filling phase. When compared with N, H1 and H2 showed significant reductions in early filling indices and an increase in atrial contribution parameters. (Evel = 0.62 +/- 0.1(N), 0.52 +/- 0.1(H1) P less than 0.01, 0.44 +/- 0.1(H2) P less than 0.001; Earea = 56 +/- 5(N), 48 +/- 5(H1) P less than 0.001, 43 +/- 6(H2) P less than 0.001; Avel = 0.49 +/- 0.1(N), 0.59 +/- 0.1(H1) P less than 0.01, 0.69 +/- 0.14(H2) P less than 0.001; Aarea = 26 +/- 5(N), 41 +/- 4(H1) P less than 0.001, 47 +/- 7(H2) P less than 0.001). Also DHT was significantly prolonged, compared with N (80 +/- 12 msec), in H1 (90 +/- 12 msec, P less than 0.01) and H2 (105 +/- 20 msec, P less than 0.001).(ABSTRACT TRUNCATED AT 250 WORDS)
- Published
- 1989
27. ChemInform Abstract: NON-ADIABATIC ELECTRONIC ENERGY TRANSFER FROM THE (3CT)RU(BPY)2(CN)2 EXCITED STATE TO CHROMIUM(III) COMPLEXES
- Author
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F. BOLLETTA, M. MAESTRI, and D. SANDRINI
- Subjects
General Medicine - Published
- 1984
28. ChemInform Abstract: THE 530 NM-LASER PHOTOLYSIS STUDIES OF THE PHOTOREDUCTION OF TRIS(2,2-BIPYRIDINE)RUTHENIUM(II) BY ORGANIC DONORS
- Author
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M. Graetzel and M. Maestri
- Subjects
Tris ,chemistry.chemical_compound ,Laser photolysis ,Chemistry ,chemistry.chemical_element ,General Medicine ,Photochemistry ,2,2'-Bipyridine ,Ruthenium - Published
- 1977
29. ChemInform Abstract: BIMOLECULAR ELECTRON TRANSFER REACTIONS OF THE EXCITED STATES OF TRANSITION METAL COMPLEXES
- Author
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V. BALZANI, F. BOLLETTA, M. T. GANDOLFI, and M. MAESTRI
- Subjects
General Medicine - Published
- 1978
30. ChemInform Abstract: LUMINESCENCE QUENCHING OF TRIS(2,2′-BIPYRIDINE) COMPLEXES OF CHROMIUM(III), RUTHENIUM(II), AND OSMIUM(II) BY CYANIDE COMPLEXES
- Author
-
A. JURIS, M. F. MANFRIN, M. MAESTRI, and N. SERPONE
- Subjects
General Medicine - Published
- 1978
31. ChemInform Abstract: PHOTOCHEMICAL, PHOTOPHYSICAL, AND THERMAL BEHAVIOR OF THE TRIS(1,10-PHENANTHROLINE)CHROMIUM(III) ION IN AQUEOUS SOLUTION
- Author
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F. BOLLETTA, M. MAESTRI, L. MOGGI, M. A. JAMIESON, N. SERPONE, M. S. HENRY, and M. Z. HOFFMAN
- Subjects
General Medicine - Published
- 1983
32. The characterization of plasma-modified polydimethylsiloxane interfaces with media of different surface energy
- Author
-
R. Bianchi, Marco Morra, A. Zonta, E. Occhiello, M. Maestri, and F. Garbassi
- Subjects
Chromatography ,Materials science ,Polydimethylsiloxane ,Contact time ,Surface Properties ,Swine ,Biophysics ,Albumin ,chemistry.chemical_element ,Fibrinogen ,Plasma ,Oxygen ,Surface energy ,chemistry.chemical_compound ,Chemical engineering ,chemistry ,Hydrophobic surfaces ,Materials Testing ,Wettability ,Animals ,Humans ,Dimethylpolysiloxanes ,Layer (electronics) ,Blood Chemical Analysis ,Serum Albumin - Abstract
The effect of interfacing fresh pig blood wth polydimethylsiloxane (PDMS) samples of different surface energies and chemistries is presented. PDMS-treated surfaces were obtained using oxygen plasmas. Aging in air produced rather hydrophobic surfaces, although less hydrophobic than the untreated one, due to hydrophobic recovery. Aging in water hindered it, therefore the surface remained hydrophilic. The concentration of albumin and fibrinogen was measured as a function of contact time with fresh pig blood with untreated, treated and aged in air, and treated and aged in water surfaces. The albumin concentration changed in a constant fashion. Fibrinogen depletion was observed for both treated surfaces. In the case of most hydrophobic surface a ‘passivating layer’ was formed. The same effect was not possible for the hydrophilic surface, due to the low albumin/fibrinogen-treated surface fracture energy.
- Published
- 1989
33. ChemInform Abstract: LIGAND AND GEOMETRY EFFECTS IN THE QUENCHING OF THE TRIS(2,2′-DIPYRIDYL)RUTHENIUM(II) PHOSPHORESCENCE BY SOME CHROMIUM(III) COMPLEXES
- Author
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F. BOLLETTA, M. MAESTRI, L. MOGGI, and V. BALZANI
- Subjects
General Medicine - Published
- 1974
34. Observations on some cases of parapneumatoriac empyema treated locally with streptomycin
- Author
-
L, PANCOTTO and M, MAESTRI
- Subjects
Streptomycin ,Empyema - Published
- 1949
35. CONSUMER WRIST-WORN SMARTBANDS AND OSAS SCREENING: PERFORMANCE OF SUPERVISED MACHINE-LEARNING ALGORITHMS
- Author
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Benedetti, D., Olcese, U., Bruno, S., Barsotti, M., Tassoni, M. Maestri, Bonanni, E., Siciliano, G., and UGO FARAGUNA
- Subjects
General Medicine
36. SLEEP MODULATION IN PARKINSON'S DISEASE PATIENTS WITH DEEP BRAIN STIMULATION: THE ROLE OF FREQUENCY VARIATIONS
- Author
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Del Prete, E., Tassoni, M. Maestri, Carnicelli, L., Barsotti, M., Gemignani, A., Menicucci, D., Piarulli, A., UGO FARAGUNA, Banfi, T., Siciliano, G., Ceravolo, R., and Bonanni, E.
- Subjects
General Medicine
37. Investigation of the efficiency of some colloidal platinum catalyst in a photochemical hydrogen-producing cycle
- Author
-
M. Maestri and D. Sandrini
- Subjects
Hydrogen ,Chemistry ,General Chemical Engineering ,Inorganic chemistry ,General Physics and Astronomy ,chemistry.chemical_element ,General Chemistry ,Platinum nanoparticles ,Photochemistry ,Catalysis - Published
- 1981
38. Bimolecular electron transfer reactions of electronically excited states of co-ordination compounds
- Author
-
Vincenzo Balzani, Fabrizio Bolletta, M. Maestri, and L. Moggi
- Subjects
Electron transfer reactions ,Electron transfer ,Quenching (fluorescence) ,Computational chemistry ,Chemistry ,Excited state ,Molecular Medicine ,Photochemistry - Abstract
The quenching of (3CT)-[Ru(bipy3)]2+ by [Cr(bipy)3]3+ and of (2MC)-[Cr(bipy)3]3+ by [Ru(bipy)3]2+ takes place by an electron transfer mechanism.
- Published
- 1975
39. Untersuchung der 530 nm-Laserphotolyse der Photoreduktion von Tris-(2,2′Bipyridin)-Ru(II) durch organische Donatoren
- Author
-
M Maestri and M. Grätzel
- Subjects
Colloid and Surface Chemistry ,Polymers and Plastics ,Chemistry ,Materials Chemistry ,Physical and Theoretical Chemistry ,Medicinal chemistry - Published
- 1978
40. Rates of virtually self-exchange energy transfer processes of ruthenium (II) polypyridine comlexes
- Author
-
M. Maestri, D. Sandrini, V. Balzani, P. Belser, and A. von Zelewsky
- Subjects
General Physics and Astronomy ,Physical and Theoretical Chemistry - Published
- 1984
41. Molecular Photochemionics
- Author
-
R. Ballardini, CERONI, PAOLA, CREDI, ALBERTO, GANDOLFI, MARIA TERESA, MAESTRI, MAURO, SEMERARO, MONICA, VENTURI, MARGHERITA, BALZANI, VINCENZO, R. Ballardini, P. Ceroni, A. Credi, M.T. Gandolfi, M. Maestri, M. Semeraro, M. Venturi, and V. Balzani.
- Subjects
Biomaterials ,Electrochemistry ,General Medicine ,Condensed Matter Physics ,Electronic, Optical and Magnetic Materials - Published
- 2007
42. Multistate/Multifunctional Behaviour of 4′-Hydroxy-6-nitroflavylium: A Write-Lock/Read/Unlock/Enable-Erase/Erase Cycle Driven by Light and pH Stimulation
- Author
-
Vincenzo Balzani, A. Jorge Parola, Mauro Maestri, Fernando Pina, Margarida C. Moncada, Carlos Lodeiro, M. C. MONCADA, A. J. PAROLA, C. LODEIRO, F. PINA, M. MAESTRI, and V. BALZANI
- Subjects
Light ,Molecular Structure ,Photochemistry ,Chemistry ,Stereochemistry ,Organic Chemistry ,Acetophenones ,Stereoisomerism ,General Chemistry ,Alkenes ,Hydrogen-Ion Concentration ,Nitro Compounds ,Chemical reaction ,Catalysis ,Chemical kinetics ,Kinetics ,Photochromism ,Ultraviolet visible spectroscopy ,Reaction rate constant ,Molecule ,Oxidation-Reduction ,Isomerization ,Equilibrium constant - Abstract
We have investigated the network of reactions observed for the photochromic 4'-hydroxy-6-nitroflavylium compound in aqueous solutions upon pH changes (including pH jump and stopped flow experiments) and light excitation. The changes observed in the NMR and UV/Vis spectra allowed identification of ten different forms in which this compound can be transformed depending on the experimental conditions. Equilibrium and kinetic constants have been determined. Compared with other members of the flavylium family, 4'-hydroxy-6-nitroflavylium is characterized by a large cis--trans isomerization barrier, and a very efficient hydration reaction. These peculiar features allow writing, reading, storing and erasing photonic information on 4'-hydroxy-6-nitroflavylium by a novel cyclic process that involves the following steps: write-lock/read/unlock/enable-erase/erase.
- Published
- 2004
43. The chemistry of 6-hydroxyflavylium: zwitterionic base and p-quinoidal chalcones. A multiswitchable system operated by proton, electron and photon inputs
- Author
-
Mauro Maestri, Fernando Pina, A. Jorge Parola, Antonio Jimenez, Carlos Pinheiro, A. Jimenez, C. Pinheiro, A.J. Parola, M. Maestri, and F. Pina
- Subjects
chemistry.chemical_classification ,Perchlorate ,chemistry.chemical_compound ,Base (chemistry) ,chemistry ,Proton ,Absorption spectroscopy ,Metastability ,Physical and Theoretical Chemistry ,Electrochemistry ,Photochemistry ,Chemical reaction ,Redox - Abstract
The complex network of chemical reactions of the compound 6-hydroxyflavylium perchlorate was studied by different techniques including UV-vis absorption spectrophotometry, stopped-flow, electrochemistry, and photochemistry. The network is characterized by the formation of a very reactive zwitterionic base as well as by p-quinoidal chalcones. The trans-chalcone is metastable in very acidic solutions and exhibits reversible redox reactions, allowing to introduce for the first time in the flavylium network an electrochemical input.
- Published
- 2007
44. Forward (singlet-singlet) and backward (triplet-triplet) energy transfer in a dendrimer with peripheral naphthalene units and a benzophenone core
- Author
-
Sang-Kyu Lee, Paola Ceroni, Mauro Maestri, Vincenzo Balzani, Giacomo Bergamini, Fritz Vögtle, G. Bergamini, P. Ceroni, M. Maestri, V. Balzani, S.-K. Lee, and F. Vögtle
- Subjects
chemistry.chemical_compound ,Intersystem crossing ,chemistry ,Absorption band ,Excited state ,Benzophenone ,Singlet state ,Physical and Theoretical Chemistry ,Triplet state ,Luminescence ,Photochemistry ,Naphthalene - Abstract
The photochemical and photophysical behaviour of two dendrimers consisting of a benzophenone core and branches that contain four (4) and eight (5) naphthalene units at the periphery has been investigated in CH(2)Cl(2) solution (298 K) and in CH(2)Cl(2)/CHCl(3) 1:1 v/v rigid matrix (77 K). For comparison purposes, the photophysical properties of dimethoxybenzophenone (1), 2-methylnaphthalene (2) and of a dendron containing four naphthalene units (3) have also been studied. In both dendrimers 4 and 5, excitation of the peripheral naphthalene units is followed by fast (1.1 x 10(9) s(-1) at 298 K, > 2.5 x 10(9) s(-1) at 77 K for 5; 2.9 x 10(8) s(-1) at 298 K, 7 x 10(5) s(-1) at 77 K for 5) singlet-singlet energy transfer to the benzophenone core. On a longer time scale (>1 x 10(6) s(-1) at 298 K, >6 x 10(3) s(-1) at 77 K for 4; 3.1 x 10(7) s(-1) at 298 K, ca. 3 x 10(2) s(-1) at 77 K for 5) a back energy transfer process takes place from the triplet state of the benzophenone core to the triplet state of the peripheral naphthalene units. Selective excitation of the benzophenone unit is followed by intersystem crossing and triplet-triplet energy transfer to the peripheral naphthalene units. In hydrogen donating solvents, the benzophenone core is protected from degradation by the presence of the naphthalene units. In solutions containing Tb(CF(3)SO(3))(3), sensitization of the green Tb(3+) luminescence is observed on excitation of both the peripheral naphthalene units and the benzophenone core of 5. Upon excitation of the naphthalene absorption band (266 nm) with a laser source, intradendrimer triplet-triplet annihilation of naphthalene excited states leads to delayed naphthalene fluorescence (lambda(max)= 335 nm), that can also be obtained upon excitation at 355 nm (benzophenone absorption band). The results obtained show that preorganization of photoactive units in a dendritic structure can be exploited for a variety of useful functions, including photosensitized emission, protection from undesired photoreactions, and energy up-conversion.
- Published
- 2004
45. Cyclam-based dendrimers as ligands for lanthanide ions
- Author
-
Paola Ceroni, Mauro Maestri, Marius Gorka, Fritz Vögtle, Christophe Saudan, Sang-Kyu Lee, Jeroen van Heyst, Veronica Vicinelli, Vincenzo Balzani, C. Saudan, P. Ceroni, V. Vicinelli, M. Maestri, V. Balzani, M. Gorka, S.-K lee, J. van Heyst, and F. Vögtle
- Subjects
Inorganic Chemistry ,Lanthanide ,chemistry.chemical_compound ,Crystallography ,chemistry ,Ligand ,Dendrimer ,Metal ions in aqueous solution ,Excited state ,Cyclam ,Singlet state ,Photochemistry ,Fluorescence - Abstract
We have investigated the complexation of lanthanide ions (Nd3+, Eu3+, Gd3+, Tb3+, Dy3+) with three cyclam-based ligands (cyclam = 1,4,8,11-tetraazacyclotetradecane), namely 1,4,8,11-tetrakis(naphthylmethyl)cyclam (1), and two dendrimers consisting of a cyclam core appended with four dimethoxybenzene and eight naphthyl units (2) and twelve dimethoxybenzene and sixteen naphthyl units (3). In the free ligands the fluorescence of the naphthyl units is strongly quenched by exciplex formation with the cyclam nitrogens. Complexation with the metal ions prevents exciplex formation and revives the intense naphthyl fluorescence. Fluorescence and NMR titration experiments have revealed the formation of complexes with different metal/ligand stoichiometries in the case of 1, 2 and 3. Surprisingly, the large dendrimer 3 gives rise to a stable [M(3)3]3+ species. Energy transfer from the lowest singlet and triplet excited states of the peripheral naphthyl units to the lower lying excited states of Nd3+, Eu3+, Tb3+, Dy3+ coordinated to the cyclam core does not take place.
- Published
- 2004
46. Luminescent ruthenium(II) bipyridine-calix[4]arene complexes as receptors for lanthanide cations
- Author
-
Paolo Passaniti, Mauro Maestri, Paul D. Beer, Fridrich Szemes, P. D. Beer, F. Szeme, P. Passaniti, and M. Maestri
- Subjects
Lanthanide ,Quenching ,Chemistry ,chemistry.chemical_element ,Photochemistry ,Adduct ,Ion ,Ruthenium ,Inorganic Chemistry ,Bipyridine ,chemistry.chemical_compound ,Excited state ,Physical and Theoretical Chemistry ,Luminescence - Abstract
The synthesis and photophysical properties of novel luminescent ruthenium(II) bipyridyl complexes containing one, two, or six lower rim acid-amide-modified calix[4]arene moieties covalently linked to the bipyridine groups are reported which are designed to coordinate and sense luminescent lanthanide ions. All the Ru-calixarene complexes synthesized in this work are able to coordinate Nd(3+), Eu(3+), and Tb(3+) ions with formation of adducts of variable stoichiometry. The absorbance changes allow the evaluation of association constants whose magnitudes depend on the nature of the complexes as well as on the nature of the lanthanide cation. Lanthanide cation complex formation affects the ruthenium luminescence which is strongly quenched by Nd(3+) ion, moderately quenched by the Eu(3+) ion, and poorly or moderately increased by the Tb(3+) ion. In the case of Nd(3+), the excitation spectra show that (i) the quenching of the Ru luminescence occurs via energy transfer and (ii) the electronic energy of the excited calixarene is not transferred to the Ru(bpy)(3) but to the neodymium cation. In the case of Tb(3+), the adduct's formation leads to an increase of the emission intensities and lifetimes. The reason for this behavior was ascribed to the electric field created around the Ru calix[4]arene complexes by the Tb(3+) ions by comparison with the Gd(3+) ion, which behaves identically and can affect ruthenium luminescence only by its charge. However, especially for compounds 1 and 3, it cannot be excluded that some contribution comes from the decrease of vibrational motions (and nonradiative processes) due to the rigidification of the structure upon Tb(3+) complexation. In the case of Eu(3+), compounds 1, 2, and 4 were quenched by the lanthanide addition but the quenching of the ruthenium luminescence is not accompanied by europium-sensitized emission which suggests that an electron-transfer mechanism is responsible for the quenching. On the contrary, compound 3 exhibits enhanced emission upon addition of Eu(3+) (as nitrate salt); it is suggested that the lack of quenching in the [3.2Eu(3+)] adduct is due to kinetic reasons because the electron-transfer quenching process is thermodynamically allowed.
- Published
- 2004
47. Dendrimers as ligands: an investigation into the stability and kinetics of Zn2+ complexation by dendrimers with 1,4,8,11-tetraazacyclotetradecane (cyclam) cores
- Author
-
Sang-Kyu Lee, Paola Ceroni, Mauro Maestri, Christophe Saudan, Jeroen van Heyst, Vincenzo Balzani, Veronica Vicinelli, Marius Gorka, Fritz Vögtle, C. SAUDAN, BALZANI V., M. GORKA, S-K. LEE, J. VAN HEYST, M. MAESTRI, P. CERONI, V. VICINELLI, and F. VOEGTLE
- Subjects
Chemistry ,Ligand ,Organic Chemistry ,Kinetics ,General Chemistry ,Photochemistry ,Fluorescence ,Catalysis ,Crystallography ,chemistry.chemical_compound ,Dendrimer ,Cyclam ,Titration ,Chelation ,Luminescence - Abstract
We have investigated the complexation of Zn 2 + with 1,4,8,11-tetrakis(naphthylmethyl) cyclam (1; cyclam = 1,4,8,11-tetraazacyclotetradecane) and with two dendrimers consisting of a cyclam core with four dimethoxybenzene and eight naphthyl appendages (2), and twelve dimethoxybenzene and sixteen naphthyl appendages (3). An important, common feature of model compound 1 and dendrimers 2 and 3 is that their potentially fluorescent naphthyl units are quenched by exciplex formation with the cyclam nitrogen atoms. Complexation with Zn 2 + , however, prevents exciplex formation and results in the appearance of an intense naphthyl fluorescence signal that can be used for monitoring the complexation process. Luminescence titration, together with competition experiments and 'H NMR titration, have shown that 1:1 and 1:2 (metal/ligand) complexes are formed in the cases of 2 and 3, whereas model compound 1 gives only a 1:1 complex. We have also investigated the 1:1 complexation kinetics by the stopped-flow technique. In the case of 1, a second-order process (k 1 = 44 × 10 5 M - 1 s - 1 ) is followed by two consecutive first-order steps (k 2 = 0.53 s - 1 and k 3 = 0.10 s - 1 ). For 2, a slower second-order process (k 1 =4.9×10 5 M - 1 s - 1 ) is followed by a slow first-order step (k 2 =0.40 s - 1 ). In the case of 3, only a very slow second-order process was observed (k 1 = 1.2× 10 5 M - 1 s - 1 ). The different metal-ion incorporation rates for model compound 1 and dendrimers 2 and 3 have been discussed in terms of conformational changes of the dendron subunits affecting the chelating properties of the cyclam core. This work reports the first kinetic study on metal-ion coordination by dendrimers with a well-defined coordination site.
- Published
- 2004
48. Photophysical, photochemical, and electrochemical properties of dendrimers with a dimethoxybenzil core
- Author
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Sang-Kyu Lee, Carlo Giansante, Mauro Maestri, Vincenzo Balzani, Fritz Vögtle, Paola Ceroni, C. Giansante, P. Ceroni, V. Balzani, M. Maestri, S.-K. Lee, F. Vögtle, Giansante, Carlo, Ceroni, Paola, Balzani, Vincenzo, Maestri, Mauro, Lee, Sang Kyu, and Vögtle, Fritz
- Subjects
Absorption spectroscopy ,Chemistry ,General Chemistry ,Chromophore ,Electrochemistry ,Photochemistry ,Catalysis ,chemistry.chemical_compound ,Dendrimer ,Excited state ,Materials Chemistry ,Ground state ,Phosphorescence ,Naphthalene - Abstract
Three dendrimers consisting of a dimethoxybenzil core and branches that contain two (G0), four (G1), and eight (G2) naphthalene units at the periphery and zero (G0), two (G1), and six (G2) dimethoxybenzene units in the branches have been synthesized and their photophysical, photochemical, and electrochemical properties have been investigated. For comparison purposes, the properties of dimethoxybenzil (MB) and of a dendron containing four naphthalene and three dimethoxybenzene units (D2) have also been studied. The properties of the dendrimers in the ground state (absorption spectra and electrochemical behavior) are those expected for their noninteracting component units. The excited state properties, however, are substantially controlled by electronic interactions between the dimethoxybenzil core and the naphthalene units contained in the branches. In dichloromethane–chloroform 1 : 1 (v/v) solution at 298 K, energy transfer from the lowest excited state (S1) of the naphthalene units to the lower lying S1 excited state of the dimethoxybenzil core takes place with high efficiency. In a rigid matrix at 77 K, selective excitation of the dimethoxybenzil chromophore yields an emission band that exhibits a spectral evolution: in the millisecond time scale it shows a spectral profile very similar to the dimethoxybenzil phosphorescence, whereas in the second time scale it is very similar to the naphthalene-type phosphorescence. Energy transfer from the T1 excited state of the dimethoxybenzil core to the T1 excited state of the naphthalene units takes place at 77 K, but not at 298 K, because the T1 excited state of the dimethoxybenzil core moves to energy lower than that of the naphthalene chromophore. The photochemical results show that the dimethoxybenzil core maintains its intrinsic photoreactivity toward dioxygen, and that on increasing dendrimer generation a photoreaction between core and branches predominates.
- Published
- 2007
49. Tuning the Photochromic Properties of a Flavylium Compound by pH
- Author
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Margarida C. Moncada, Ana C. A. Roque, A. Jorge Parola, Mauro Maestri, Fernando Pina, Vincenzo Balzani, M.C. Moncada, F. Pina, A. Roque, A.J. Parola, M. Maestri, and V. Balzani
- Subjects
chemistry.chemical_classification ,Chalcone ,Base (chemistry) ,Photoisomerization ,Thermodynamic equilibrium ,Organic Chemistry ,Nuclear magnetic resonance spectroscopy ,Photochemistry ,chemistry.chemical_compound ,Photochromism ,chemistry ,Flash photolysis ,Physical and Theoretical Chemistry ,Cis–trans isomerism - Abstract
We studied the intricate pH- and light-dependent network of the thermal and photochemical reactions of the 4′-(dimethylamino)-7-hydroxyflavylium ion by continuous irradiation, flash photolysis, 1H NMR spectroscopy, and stopped flow analysis. The distribution of the various forms at the pH-dependent thermodynamic equilibrium and the rates of several interconversion processes were measured. The most interesting feature of this multistate/multifunctional system is related to the possibility of pH-tuning the colour change caused by photoirradiation, because the cis-chalcone isomer, obtained from the photoisomerization of the trans-chalcone form, is spontaneously transformed into coloured species (flavylium cation and quinoidal base) at low values of pH, but reverts back to the uncoloured trans-chalcone at high values of pH because of the low energy barrier between the cis and trans chalcone isomers. (© Wiley-VCH Verlag GmbH & Co. KGaA, 69451 Weinheim, Germany, 2004)
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