Las alamedas en la España Moderna. Interpretación histórica de un espacio urbano

This work offers an historiographical synthesis about the origin and historical and urbanistic significance represented by the creation and spreading of the alamedas in Early Modern Spain. Through an exhaustive bibliographical survey about the most important alamedas, the author pays special attention to the reasons behind their creation and the evolution that they experimented all along the studied period.El presente trabajo constituye una síntesis historiográfica sobre el origen y el significado histórico y urbanístico que representa el surgimiento y difusión de las alamedas en la España moderna. En él se realiza un exhaustivo recorrido bibliográfico sobre las alamedas más importantes, prestando especial atención a las causas de su creación y la evolución que fueron experimentando a lo largo del periodo de estudio

Influence of feeding time on sexual maturity and carcass composition in female broiler breeders

One thousand two hundred and ninety six Arbor Acres females and 144 males were used to study the influence of feeding time on sexual maturity and carcass composition. Treatments were: T1 = feeding at 6:30 am, T2 = 50% feeding at 6:30 am and 50% at 3:30 pm (dual), T3 = feeding at 11:00 am, T4 = feeding at 3:30 pm. Nutrition and management were as recommended to the commercial line. Variables studied were: sexual maturity at 5% production (SM), mean egg production percentage (PEP) body weight (BW), carcass composition, tibia weight (TIBW) and tibia calcium (Ca) and phosphorus (P) contents. Analysis of variance was used, and the means were compared using Student's t test. T2 females reached SM at 25.92 weeks, which was earlier (p<0.01) than the other treatments. PEP was greater (p<0.01) for T1 and T2 than for the other treatments. BW was greater in T1 and smaller in T4 (p<0.05) than in the other treatments. TIBW was greater in T3 than in T1 and T2 (p<0.05), with no effect (p>0.10) on carcass dry matter (DM), ether extract (EE), crude protein (CP) and ash (ASH). DM, EE, TIBW, Ca and P increased (p<0.05) whereas CP and ASH decreased with age. Time of feeding influenced body weight, but not carcass composition. Hens fed twice a day had earlier sexual maturity and similar egg production compared to those fed once at 6:30 am

Spectroscopic studies of enantiomeric discrimination in jet-cooled chiral complexes

Van der Waals complexes formed between chiral molecules in the isolated gas phase were studied by combining supersonic expansion techniques with laser spectroscopy. The weakly bound diastereoisomers formed between a chiral secondary alcohol, butan-2-ol, and a chiral aromatic derivative such as 2-naphthyl-1-ethanol or 1-phenylethanol used as a resolving agent were discriminated on the basis of the spectral shifts of the UV S0-S1 transition of the chromophore. Ground-state depletion spectroscopy (hole burning) has shown that, while only one structure was detected for the 1-phenylethanol/butan-2-ol homochiral complex, the heterochiral complex is trapped in the jet under two different conformations. Two isomers have also been shown for each diastereoisomeric pair of the 2-naphthyl-1-ethanol/butan-2-ol complexes. Using a semiempirical potential model, these isomeric forms were related to calculated structures which exhibit a folded or extended geometry depending on the solvent conformation (anti or gauche). The relative binding energy of the complexes involving R-1-phenylethanol and R- or S-butan-2-ol were obtained from fragmentation threshold measurements following two-color photoionization. Comparison of the diastereoisomers exhibiting a similar spectral signature shows that the homochiral pair is more stable than the heterochiral one by about 0.7 kcal/mol. The fragmentation threshold has been shown to depend on the jet-cooled isomer and this result addresses the role of conformational control in enantioselective interactions

Enantiodiscrimination of Chiral alfa-Aminophosphonic Acids by Mass Spectrometry

Diastereomeric clusters between first-group metal ions (M+) and chiral .alpha.-aminophosphonic acids (A and B) have been readily generated in the gas phase by electrospray ionization (ESI) and their fragmentation investigated by mass spectrometry. The complexes studied had the general formula [MASB2]+ and [MARB2]+, where M = H, Li, Na, or K, AS and AR are the two enantiomers of a given acid A, and B is a ref. .alpha.-aminophosphonic acid of defined configuration. Collision-induced decompn. (CID) of [MASB2]+ and [MARB2]+ leads to fragmentation patterns characterized by [MAB]+/[MB2] abundance ratios which depend on the configuration of ligand A. These different spectral features were correlated to the different stability of the diastereomeric [MASB2]+ and [MARB2]+ complexes in the gas phase. The results have been discussed in the light of MM2 Mol. Mechanics Force Field calcns