143 research outputs found
Cavitazione acustica in soluzioni di acqua e sale
No full textIn questa memoria si è applicata la tecnica della cavitazione ultrasonora impulsata per studiare la dipendenza dell’emissione acustica di sub armonica 1⁄2 e di sono luminescenza dalla concentrazione di NaCl in acqua. Le misure di sono luminescenza sono state condotte a temperatura ambiente con concentrazioni di NaCl fino al valore di saturazione (circa 270 g/l) e in corrispondenza a diversi valori della tensione di trasduttore. Il comportamento dei campioni esaminati mostra che le soglie per i due fenomeni crescono con la concentrazione di sale. L’efficienza dell’emissione di sub armonica decresce, mentre quella di sono luminescenza cresce
Ultrasonic Cavitation Threshold in Very Dilute NaCl-Water Solutions
No full textThe pulsed ultrasonic cavitation technique was employed to measure the dependence of the thresholds for emission of subharmonic and light on the concentration of dilute solutions of NaCl in distilled water. The concentration was varied from 10-9 d/cm3 to saturation, for different values of the inverse duty ratio. Preceeding results indicate an increase of both thresholds with concentration. In the case of very low values of concentration (10-9 to 10-3 g/cm3) the trend is reversed. Possible mechanisms that can explain the presence of the minimum, based on the dynamics of nuclei and bubbles population are indicated
A response surface-based approach to predict spinal rod contouring parameters
No full textRod contouring can be intraoperatively performed
by surgeons to obtain bent spinal rods that better fit the
physiological curvature of the spine. However, this procedure
exploits the material plastic deformation, which is known to affect
fatigue behavior in vivo.
Numerical models allow the assessment of the residual stress
field due to contouring, but at a high computational cost, which
is not compatible with the extensive use of in silico models in
preoperative clinical planning.
For this reason, after preparing a finite element analysis of
titanium rod contouring, a response surface-based approach is
proposed to correlate contouring-related parameters with
residual stress field and rod curvature
Effects of N-chlorobenzyl analogues of amiloride on myocardial contractility, Na-Ca-exchange carrier and other cardiac enzymatic activities.
No full text1. In electrically driven guinea pig left atria, micromolar concentrations (2 mumol/l to 80 mumol/l) of N-chlorobenzyl derivatives of amiloride (o-chlorobenzamil and 3',4'-dichlorobenzamil) produced quantitatively similar positive inotropic effects. Contracture developed with 3',4'-dichlorobenzamil. Endogenously released catecholamines contributed 30% to the positive inotropic effect of o-chlorobenzamil but did not contribute at all to the effect of 3',4'-dichlorobenzamil. When tested in the presence of the inhibitor of phosphodiesterase isobutylmethylxanthine, o-chlorobenzamil antagonized its positive inotropic effect, whereas 3',4'-dichlorobenzamil potentiated it. o-Chlorobenzamil also antagonized the positive inotropic effect of ouabain in that it shifted its concentration-effect curve to the right. Moreover, o-chlorobenzamil prevented the appearance of ouabain toxicity in terms of a rise in the resting force. 2. Also, in electrically driven guinea pig papillary muscle, micromolar concentrations (5 mumol/l to 30 mumol/l) of both N-chlorobenzyl derivatives of amiloride produced a positive inotropic effect. This effect was more marked with 3',4'-dichlorobenzamil than with o-chlorobenzamil and was associated for both compounds with lengthening of relaxation time. 3. o-Chlorobenzamil and 3',4'-dichlorobenzamil influenced, though not to the same extent, several systems involved in the onset and in the control of cardiac contractility. 3',4'-Dichlorobenzamil inhibited with the same potency Na-K-ATPase, sarcotubular Ca-ATPase, Na-Ca-exchange carrier, cAMP-dependent phosphodiesterase isolated from bovine heart and oxidative phosphorylation of mitochondria isolated from rat liver. Low micromolar concentrations of o-chlorobenzamil mainly inhibited Na-Ca-exchange carrier and cAMP-dependent phosphodiesterase.(ABSTRACT TRUNCATED AT 250 WORDS
Soglia di cavitazione ultrasonora in soluzioni diluite di NaCl
No full textSi sono misurate le soglie di emissione di sono luminescenza e sub armonica in soluzioni dilutite di NaCl in presenza di un campo ultrasonoro impulsato. Si è visto che, mentre per concentrazioni medio-alte entrambe le soglie crescono con la concentrazione della soluzione, per soluzioni molto diluite si ha una diminuzione della soglia di sub armonica al crescere della concentrazione
Modulation of the Kynurenine Pathway in Search for New Neuroprotective Agents. Synthesis and Preliminary Evaluation of (m-Nitrobenzoyl)alanine, a Potent Inhibitor of Kynurenine-3-hydroxylase
No full textThe synthesis of (o-nitrobenzoyl)-, (m-nitrobenzoyl)-, and (p-nitrobenzoyl)alanine (o-, m-, and p-NBA), three new kynurenine analogues, and their evaluation as inhibitors of kynureninase and kynurenine-3-hydroxylase are reported. The most potent of these compounds, m-NBA, has an IC50 of 0.9 +/- 0.1 microM as an inhibitor of kynurenine-3-hydroxylase and of 100 +/- 12 microM as an inhibitor of kynureninase. When administered to rats, m-NBA significantly increases the concentration of kynurenine and kynurenic acid in the brain as well as in blood and in the liver. m-NBA has also been shown to increase the concentration of kynurenic acid in hippocampal extracellular fluid. This increase is associated with sedative and anticonvulsant activities, thus confirming the possibility of antagonizing L-glutamate-mediated effects by modulating the kynurenine pathway of L-tryptophan metabolism
Concentração foliar de nutrientes em mudas de mirtilo em função de diferentes substratos.
No full text
Substratos para o enraizamento de microestacas de mirtileiro cultivar georgiagem
No full textO objetivo do trabalho foi verificar a viabilidade e definir um substrato adequado para o enraizamento de microestaquia e o crescimento de mudas de mirtileiro cultivar Georgiagem. Foram avaliados diferentes substratos para a técnica de microestaquia mantida em condições de microambiente úmido, com temperatura e luz controladas. As microestacas foram acondicionadas em caixas de politereftalato de etileno, durante 48 dias. Os substratos turfa de musgo Sphagnum sp. e as misturas turfa + perlita, turfa + perlita + fibra de coco, turfa + perlita + serragem permitiram a obtenção de maior percentual de enraizamento
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