High-spin structures of 51 121, 123, 125, 127Sb nuclei: Single proton and core-coupled states

The ^{121,123,125,127}Sb nuclei have been produced as fission fragments in three reactions induced by heavy ions: ¹²C + ²³⁸U at 90 MeV bombarding energy, ¹⁸O + ²⁰⁸Pb at 85 MeV, and ³¹P + ¹⁷⁶Yb at 152 MeV. Their level schemes have been built from gamma rays detected using the EUROBALL III and IV arrays. High-spin states of ^123,125,127Sb nuclei have been identified for the first time. Moreover isomeric states lying around 2.3 MeV have been established in ^123,125,127Sb from the delayed coincidences between the fission fragment detector SAPhIR and the gamma array. All the observed states can be described by coupling a d_5/2 or g_7/2 proton to an excited Sn core involving either vibrational states or broken neutron pairs.     

On the rapid increase of intermittency in the near-dissipation range of fully developed turbulence

Intermittency, measured as , where F(r) is the flatness of velocity increments at scale r, is found to rapidly increase as viscous effects intensify, and eventually saturate at very small scales. This feature defines a finite intermediate range of scales between the inertial and dissipation ranges, that we shall call near-dissipation range. It is argued that intermittency is multiplied by a universal factor, independent of the Reynolds number Re, throughout the near-dissipation range. The (logarithmic) extension of the near-dissipation range varies as . As a consequence, scaling properties of velocity increments in the near-dissipation range strongly depend on the Reynolds number.     

Detection and quantification of insoluble particles by ultrasound spectroscopy

The Ultrafood system, a custom-built diagnostic ultrasound device, is used to accurately measure the concentration of particulate matter in a fluctuating high temperature liquid system. The two main problems, of thermal expansion and thermal variation in ultrasonic outputs were tackled by multi-distance measurement and low frequency spectroscopy, respectively. The resulting techniques have application at laboratory, scale for investigation of particulate suspensions and for online process monitoring.     

Total syntheses of (+)-bernumidine and its unnatural enantiomer

Total syntheses of (+)-bernumidine and its unnatural enantiomer were accomplished through chemoenzymatic dynamic kinetic resolution and ruthenium(II)-catalyzed enantioselective hydrogenation, which provided (R)-salsolidine propyl carbamate and N-acetyl (S)-salsolidine in high yields and enantiomeric excesses, respectively. Both enantiomers of salsolidine were accessed and converted into (+)- and (?)-bernumidine via simple and efficient transformations.     

Thermal behaviour of sericite clays as precursors of mullite materials

Thermal analysis of some sericite clays, from several deposits in Spain, which are not exploited at this time, has been studied. The samples have been previously characterized by mineralogical and chemical analysis. Sericite clays have interesting properties, with implications in ceramics and advanced materials, in particular concerning the formation of mullite by heating. According to this investigation by differential thermal and thermogravimetric analysis (DTA-TG), the sericite clay samples can be classified as: Group (I), sericite–kaolinite clays, with high or medium sericite content, characterized by an endothermic DTA peak of dehydroxylation of kaolinite with mass loss, which overlapped with dehydroxylation of sericite, and Group (II), sericite–kaolinite–pyrophyllite clays, with broader endothermic DTA peaks, in which kaolinite is dehydroxylated first and later sericite and pyrophyllite with the main mass loss, appearing the peaks overlapped. X-ray diffraction analysis of the heated sericite clay samples evidenced the decomposition of dehydroxylated sericite and its disappearance at 1050 °C, with formation of mullite, the progressive disappearance of quartz and the formation of amorphous glassy phase. The vitrification temperature is ~ 1250 °C in all these samples, with slight variations in the temperatures of maximum apparent density (2.41–2.52 g mL^?1) in the range 1200–1300 °C. The fine-grained sericite content and the presence of some mineralogical components contribute to the formation of mullite and the increase in the glassy phase by heating. Mullite is the only crystalline phase detected at 1400 °C with good crystallinity. SEM revealed the dense network of rod-shaped and elongated needle-like mullite crystals in the thermally treated samples. These characteristics are advantageous when sericite clays are applied as ceramic raw materials.     

Electroanalytical methods for determination of the metal content and acetic-acid-available metal fractions in soils

The pseudo-total and available arsenic, cadmium, and lead content of soils have been determined by stripping voltammetry with a hanging-mercury-drop electrode and by atomic absorption spectrometry with electrothermal atomization. For determination of pseudo-total metals microwave digestion with a mixture of HNO3 and HClO4, with and without addition of HF, was investigated. The single-extraction procedure with 0.43 mol L-1 CH3COOH, proposed by BCR, was used to assess the availability of metals in soils. The results obtained were validated by analysis of a certified reference material.     

A fast and easy computational method to calculate the (13)C NMR chemical shift of organic species adsorbed on the zeolite surface

Calculations of the 13C NMR chemical shifts for the methoxy and ethoxy groups adsorbed on Y and ZSM-5 zeolites were computed at GIAO/B3LYP/6-31+G*//MM+ level of theory, using a cluster representing a real part of the zeolites. The Y zeolite was represented by a cluster with 168 atoms, while ZSM-5 was represented by a cluster with 144 atoms. The calculated chemical shifts agreed well with reported experimental values, showing that the difference in chemical shifts is associated with differences in the geometry of the alkoxides on the two zeolites.     

Structure, bonding, and solvation of lithium vinylcarbenoids

[reaction: see text] Molecular modeling was used to determine the structure of lithium vinylcarbenoids in the gas phase and in THF solution. Solvent effects were modeled by microsolvation with explicit THF ligands on each of the lithium atoms. The carbenoid geometries are dependent on the heteroatom and on solvation. The calculations predict 1-chlorovinyllithium and 1-bromovinyllithium to be a mixture of monomer and dimer at 200 K and mostly monomer at higher temperatures, whereas the 1-fluoro-, 1-methoxy-, and 1-dimethylaminovinyllithium are predicted to be dimeric in solution.