86,716 research outputs found
Kinetics of the Reaction between Carbon and Oxygen on Ni(111), Studied by Auger Electron Spectroscopy
No full textComputer simulation of experimental surface charge for isomorphous oxides
No full textThe interfacial electrification behaviokr of cobalt ferrite samples kith different dekrees of skbstitktion, is analyzed; the experimental charke vs. pH ckrves are compared kith charke ckrves calcklated on the basis of the model of Davis et al. [8,9]. The extent of akreement betkeen calcklated and experimental resklts varies kith varyink the concentration of the base electrolyte; fkrther, in the case of the fklly skbstitkted CoFe2O4, charke vs. pH ckrves are reprodkced ksink very hikh and markedly different inner capacitance valkes in the positive and nekative rekions of charke. © 1988
Cardio-respiratory adjustments and cost of locomotion in school children during backpack walking
No full textThe use of a school backpack is one of the possible causes of back pain in children. Oxygen consumption ((V)over dotO(2)), pulmonary ventilation, and heart rate (f(c)) were measured in 35 pre-pubertal subjects [17 girls and 18 boys, mean (SID) age 11.3 (0.6) years]. They took part in a four-step experiment: (1) standing for 5 min, (2) walking at 3 km.h(-1) for 7 min, (3) walking at 3 km.h(-1) for 7 min carrying a school backpack weighing 8 kg, and (4) walking at 7 km.h(-1) for 5 min with no load. The occurrence of back pain in the last 2-3 years and during the last 15 days was assessed for the subjects by means of a questionnaire. Mean (SID) standing (V)over dotO(2) was 215 (45) ml-min(-1) during walking at 3 km.h(-1), 503 (101) ml.min(-1) during walking without a load, and increased to 541 (98) ml.min(-1) during walking with a load (P<0.01). Carrying a backpack increased f(c) only minimally. The energy cost of walking at 3 km.h(-1) without the backpack was 10.0 (2.0) ml O-2.m(-1) and with the backpack was 10.8 (1-9) ml O-2.m(-1) (P<0.01). The net energy cost of locomotion was 0.129 (0.032) ml.kg body mass(-1).m(-1) for the unloaded condition and slightly lower, at 0.123 (0.025) ml.kg body mass(-1).m(-1) during loaded walking (P<0.05). Ventilation did not change significantly between unloaded and loaded conditions. When the data were assessed according to the occurrence of back pain, the f(c)/(V)over dotO(2) slope was significantly lower in children without back pain, even though the net energy cost of locomotion was similar. Overall, these data suggest that the cardiovascular effort required for locomotion while carrying a backpack is minimal. However, fatigability and back pain are more likely to take place in less physical performing subjects. Thus, the occurrence of back pain in schoolchildren during locomotion while carrying a backpack may improve with an improvement in their level of fitness
Effects of short term cast wearing on respiratory and cardiac responses to submaximal and maximal exercise in adolescents with idiopathic scoliosis
No full textAIM: Bracing is widely used to treat adolescent scoliosis. However, bracing may also affect respiratory and cardiovascular function. In this thirteen-weeks longitudinal study we evaluated the effect of brace wearing on maximal and submaximal cardiorespiratory capacity in adolescents with moderate idiopathic scoliosis. METHODS: Eight boys and 8 girls (12-18 years) with scoliosis of the thoracic spine (Cobb angle range 32 degrees - 42 degrees in boys and 32 degrees - 60 degrees in girls) were enrolled. Respiratory basal function (forced vital capacity, FVC, and forced expired volume in 1 s, FEV(1)) and cardiorespiratory adjustments to submaximal and maximal cycle ergometer exercise (heart rate, HR, pulmonary ventilation, VE, and oxygen consumption, VO(2)) were measured a week before fitting a brace, after 1 and 12 weeks of brace wearing, and a week after brace removal. RESULTS: With respect to pretreatment values: a) after 1 week of brace wearing FVC and FEV(1) were significantly reduced in both genders; b) after 12 weeks of bracing the amount of oxygen consumed per heart beat was reduced during maximal and submaximal exercises in females only; c) ventilatory efficiency was unchanged in both genders in each condition; d) oxygen uptake during maximal exercise was decreased (by about 10-20%) in females only; e) after brace removal all variables tended to regress to pretreatment values. CONCLUSIONS: Although data are preliminary and need to be confirmed on larger samples of patients, the brace appears to limit maximal exercise performance especially in girls, where it affects the cardiopulmonary efficiency. Thus, moderate physical exercise during brace wearing is advised to counteract respiratory, cardiovascular and muscle inefficiency due to ribcage movement limitations
Produzione di salmerino alpino Salvelinus alpinus (L.): incubazione e primi stadi di sviluppo
No full textIl salmerino alpino Salvelinus alpinus (L.) è una specie di interesse per l’acquacoltura fino dagli anni ’70, con esperienze di
allevamento documentate soprattutto per il nord Europa ed il Canada, ma assenti in Italia. Sostanziali differenze tra le
esigenze fisiologiche del salmerino alpino ed i salmonidi normalmente utilizzati in acquacoltura (trota iridea, salmone, trota
fario) suggeriscono la necessità di definire specifici protocolli di allevamento. È stata pertanto attivata una linea sperimentale
triennale di produzione di salmerino alpino, atta ad approfondire gli aspetti impiantistici e gestionali connessi con
l’allevamento di questa specie nel versante meridionale dell’arco alpino. I primi risultati evidenziano il buon adattamento
del salmerino alpino ai sistemi ricircolati, dallo stadio di uovo fecondato al termine del riassorbimento del sacco vitellino.
Alla temperatura media di 4 °C lo stadio di uovo embrionato viene raggiunto in 184 gradi giorno (GG) mentre il riassorbimento del sacco vitellino viene completato a 631 GG dalla fecondazione; le larve all’inizio della fase alimentare misurano 19,2 ± 0,3 m
1,3-Dipolar cycloadditions of azomethine ylides with dipolarophiles. II. Synthesis of pyrrolizidines
No full textThe G1456 to T mutation in the thrombomodulin gene is not frequent in patients with venous thrombosis
No full textOxazol-5(4H)-ones. Part 7. New synthesis of oxazolo[5,4-b]pyridines
No full textOxazolo[5,4-b]pyridines 4 are synthesized by heating the iminophosphoranes 1 and alkylideneoxazol-5(4H)-ones 2. At room temperature the reaction of 4-ethoxymethyleneoxazol-5(4H)-one 2f with iminophosphorane 1a yields the enamino lactone 6, which is, in turn, transformed by heating in acetic acid into the 2(1H)-pyridone 7
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