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1.
Anal Bioanal Chem ; 406(1): 201-11, 2014 Jan.
Artigo em Inglês | MEDLINE | ID: mdl-24253407

RESUMO

A major challenge regarding the characterization of multilayer films is to perform high-resolution molecular depth profiling of, in particular, organic materials. This experimental work compares the performance of C60(+) and Ar1700(+) for the depth profiling of model multilayer organic films. In particular, the conditions under which the original interface widths (depth resolution) were preserved were investigated as a function of the sputtering energy. The multilayer samples consisted of three thin δ-layers (~8 nm) of the amino acid tyrosine embedded between four thicker layers (~93 nm) of the amino acid phenylalanine, all evaporated on to a silicon substrate under high vacuum. When C60(+) was used for sputtering, the interface quality degraded with depth through an increase of the apparent width and a decay of the signal intensity. Due to the continuous sputtering yield decline with increasing the C60(+) dose, the second and third δ-layers were shifted with respect to the first one; this deterioration was more pronounced at 10 keV, when the third δ-layer, and a fortiori the silicon substrate, could not be reached even after prolonged sputtering. When large argon clusters, Ar1700(+), were used for sputtering, a stable molecular signal and constant sputtering yield were achieved throughout the erosion process. The depth resolution parameters calculated for all δ-layers were very similar irrespective of the impact energy. The experimental interface widths of approximately 10 nm were barely larger than the theoretical thickness of 8 nm for the evaporated δ-layers.


Assuntos
Argônio/química , Fulerenos/química , Fenilalanina/química , Tirosina/química , Silício/química , Propriedades de Superfície , Termodinâmica , Volatilização
2.
Comp Biochem Physiol A Physiol ; 110(1): 47-56, 1995 Jan.
Artigo em Inglês | MEDLINE | ID: mdl-7866774

RESUMO

The purpose of this study was to determine the effects of programmed intravenous infusion of chicken growth hormone (cGH) on growth and metabolism of young broiler chickens (4-7 weeks of age). Four-week-old broiler cockerels, fitted with indwelling jugular catheters, were randomly assigned to three treatment groups (6 birds/group): pulsatile infusion of buffer (phosphate buffer, pH 7.4)[PB-P] at 3 hr intervals, pulsatile infusion of cGH (15 micrograms/kg at 3 hr intervals)[GH-P], or continuous infusion of cGH (120 micrograms/kg-day)[GH-C]. Birds were bled 5 min before (0-min) and 5 min post-infusion (relative to the pulses of PB and cGH) at 5, 6, and 7 weeks of age. Pulsatile infusion of cGH increased (P < 0.05) feed consumption by 24% and reduced (P < 0.05) feed efficiency by 14% without affecting body weight (BW) gain. The relative weights (%BW) of liver, abdominal fat, and bursa of Fabricius were not affected by the pattern of cGH infusion. However, the body fat content of cGH-infused chickens was increased (P < 0.05) by 13% (GH-C) and 17% (GH-P), while body protein and water contents were slightly reduced. Body ash content was not affected by pattern of cGH infusion. When compared with the PB-P controls, the GH-P treatment depressed (P < 0.05) hepatic GH-binding activity by 52% without affecting plasma insulin-like growth factor-I (IGF-I) levels. Continuous infusion of cGH increased (P < 0.05) plasma IGF-I by 16%, thyroxine (T4) by 31%, and glucagon levels by 55%, although plasma GH levels were only 47% higher than those of the PB-P group. However, the GH-P treatment was only half as effective as the GH-C pattern in elevating plasma levels of T4 and glucagon. This study shows that programmed intravenous infusion of cGH increases deposition of body fat in young rapidly-growing broiler chickens.


Assuntos
Tecido Adiposo/efeitos dos fármacos , Galinhas/crescimento & desenvolvimento , Galinhas/metabolismo , Hormônio do Crescimento/farmacologia , Tecido Adiposo/crescimento & desenvolvimento , Ração Animal , Animais , Composição Corporal/efeitos dos fármacos , Galinhas/sangue , Hormônios/sangue , Infusões Intravenosas , Masculino , Fatores de Tempo
3.
Comp Biochem Physiol Comp Physiol ; 107(4): 665-72, 1994 Apr.
Artigo em Inglês | MEDLINE | ID: mdl-7911411

RESUMO

This study was conducted to determine the effects of programmed intravenous infusion of growth hormone-releasing factor (GRF) on the growth and metabolism of young broiler chickens (4-7 weeks of age). Twelve 4-week-old chickens, fitted with jugular catheters, were randomly assigned to three treatment groups (four birds/group): pulsed infusion of saline [SAL-P] at 3 hr intervals, pulsed infusion of GRF1-44 (5 micrograms/kg at 3 hr intervals)[GRF-P], or continuous infusion of GRF (40 micrograms/kg-day)[GRF-C]. The GRF-P treatment depressed (P < 0.05) average daily gain by 32%, average daily feed consumption by 24%, and final body weight by 17% when compared with the SAL-P group. Pulsatile infusion of GRF (GRF-P) reduced (P < 0.05) abdominal fat weight by 39% and body fat content by 28% when compared to the SAL-P group. Plasma GH levels were elevated (P < 0.05) 2.1-fold in the GRF-P group at 15 min-post-infusion, while GH levels in the GRF-C group were maintained about 70% higher than those in the SAL-P group. Plasma levels of insulin-like growth factor-I (IGF-I) were consistently lower in the GRF-P group at all ages. There were no significant differences in plasma levels of triiodothyronine (T3), thyroxine (T4), insulin, or glucose among treatment groups. This study shows that pulsatile infusion of GRF, designed to enhance plasma GH levels, does not improve growth rate, feed efficiency, or body composition of young broiler chickens.


Assuntos
Galinhas/crescimento & desenvolvimento , Hormônio Liberador de Hormônio do Crescimento/administração & dosagem , Crescimento/efeitos dos fármacos , Tecido Adiposo/anatomia & histologia , Tecido Adiposo/efeitos dos fármacos , Animais , Composição Corporal , Galinhas/sangue , Ingestão de Alimentos/efeitos dos fármacos , Hormônio do Crescimento/sangue , Infusões Intravenosas , Fator de Crescimento Insulin-Like I/metabolismo , Masculino , Distribuição Aleatória , Tiroxina/sangue , Tri-Iodotironina/sangue , Aumento de Peso/efeitos dos fármacos
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