Short-range charge-order in RRNiO3_{3} perovskites (RR=Pr,Nd,Eu) probed by X-ray absorption spectroscopy

The short-range organization around Ni atoms in orthorhombic $R$NiO$_{3}$ ($R$=Pr,Nd,Eu) perovskites has been studied over a wide temperature range by Ni K-edge x-ray absorption spectroscopy. Our results demonstrate that two different Ni sites, with different average Ni-O bond lengths, coexist in those orthorhombic compounds and that important modifications in the Ni nearest neighbors environment take place across the metal-insulator transition. We report evidences for the existence of short-range charge-order in the insulating state, as found in the monoclinic compounds. Moreover, our results suggest that the two different Ni sites coexists even in the metallic state. The coexistence of two different Ni sites, independently on the $R$ ion, provides a common ground to describe these compounds and shed new light in the understanding of the phonon-assisted conduction mechanism and unusual antiferromagnetism present in all $R$NiO$_{3}$ compounds.Comment: 4 pages, 3 figures, accepted PRB - Brief Report Dec.200

Macro and microelements, lead, cadmium, functional compounds, antioxidant capacity in fresh, dry cocoa beans and cocoa paste

The cocoa bean and its by-products are widely consumed in the world, due to their mineral content, functional compounds and antioxidant capacity, which vary according to how its processed. Fresh dried cocoa beans (FDB), dry fermented beans (FB) and cocoa paste (CP) were investigated, 31 samples in each case. Phosphorus, sodium, calcium, magnesium, copper, iron, zinc, manganese, cadmium lead, total polyphenols, anthocyanins, antioxidant capacity (ABTS, DPPH) expressed in Trolox equivalents (TE) were determined. Principal component analysis (PCA) was used. The mineral analysis established that 12 samples influenced CP1 and CP2. There was more calcium in the M26 sample of FDB, with 3.14%; potassium in the FDB, in M13, with 2.44%. Zinc in the FDB, was found in greater quantity in M30, M22, M23 and M9; with 90.46 ± 0.19 ppm in M30. Twenty-five samples reached values ≤ 0.61 ± 0.01 ppm of cadmium. There was a higher lead content in the FDB, in the M20 sample with 3.44 ± 0.05 ppm. The M10 sample, from FDB, presented the highest antioxidant capacity, with values of 591.50 ± 3.76 (ABTS) and 513.68 ± 0.84 (DPPH) μM TE/g.The cocoa bean and its by-products are widely consumed in the world, due to their mineral content, functional compounds and antioxidant capacity, which vary according to how its processed. Fresh dried cocoa beans (FDB), dry fermented beans (FB) and cocoa paste (CP) were investigated, 31 samples in each case. Phosphorus, sodium, calcium, magnesium, copper, iron, zinc, manganese, cadmium lead, total polyphenols, anthocyanins, antioxidant capacity (ABTS, DPPH) expressed in Trolox equivalents (TE) were determined. Principal component analysis (PCA) was used. The mineral analysis established that 12 samples influenced CP1 and CP2. There was more calcium in the M26 sample of FDB, with 3.14%; potassium in the FDB, in M13, with 2.44%. Zinc in the FDB, was found in greater quantity in M30, M22, M23 and M9; with 90.46 ± 0.19 ppm in M30. Twenty-five samples reached values ≤ 0.61 ± 0.01 ppm of cadmium. There was a higher lead content in the FDB, in the M20 sample with 3.44 ± 0.05 ppm. The M10 sample, from FDB, presented the highest antioxidant capacity, with values of 591.50 ± 3.76 (ABTS) and 513.68 ± 0.84 (DPPH) μM TE/g

BrExit and foreign investment in the UK

We explore the likely effect of Brexit on inward foreign direct investment (FDI) through its possible effect on the benchmark variables that characterize the macroeconomy. For this we propose the use of a Markov regime switching structural vector auto-regression to distinguish between the volatile and stable states of the economy and account, among other effects, for the contemporaneous effects that the frequency of FDI innately generates. Our findings suggest that, if Brexit triggers a sterling depreciation in the current economic climate, this will fuel a prolonged negative effect on FDI. FDI flows may be positively affected (at most) by a sterling depreciation after Brexit only if this event drives the UK economy to a period of highly volatile growth, inflation, interest and exchange rates: a scenario that is rather unlikely. And, even then, the sterling depreciation benefits would last for only a short period of time

Spin-orbit induced mixed-spin ground state in RRNiO3_3 perovskites probed by XAS: new insight into the metal to insulator transition

We report on a Ni L$_{2,3}$ edges x-ray absorption spectroscopy (XAS) study in $R$NiO$_3$ perovskites. These compounds exhibit a metal to insulator ($MI$) transition as temperature decreases. The L$_{3}$ edge presents a clear splitting in the insulating state, associated to a less hybridized ground state. Using charge transfer multiplet calculations, we establish the importance of the crystal field and 3d spin-orbit coupling to create a mixed-spin ground state. We explain the $MI$ transition in $R$NiO$_3$ perovskites in terms of modifications in the Ni$^{3+}$ crystal field splitting that induces a spin transition from an essentially low-spin (LS) to a mixed-spin state.Comment: 4 pages, 4 figures, accepted as PRB - Rapid Comm. Dez. 200

Compartmentalized PDE4A5 signaling impairs hippocampal synaptic plasticity and long-term memory

Alterations in cAMP signaling are thought to contribute to neurocognitive and neuropsychiatric disorders. Members of the cAMP-specific phosphodiesterase 4 (PDE4) family, which contains >25 different isoforms, play a key role in determining spatial cAMP degradation so as to orchestrate compartmentalized cAMP signaling in cells. Each isoform binds to a different set of protein complexes through its unique N-terminal domain, thereby leading to targeted degradation of cAMP in specific intracellular compartments. However, the functional role of specific compartmentalized PDE4 isoforms has not been examined in vivo. Here, we show that increasing protein levels of the PDE4A5 isoform in mouse hippocampal excitatory neurons impairs a long-lasting form of hippocampal synaptic plasticity and attenuates hippocampus-dependent long-term memories without affecting anxiety. In contrast, viral expression of a truncated version of PDE4A5, which lacks the unique N-terminal targeting domain, does not affect long-term memory. Further, overexpression of the PDE4A1 isoform, which targets a different subset of signalosomes, leaves memory undisturbed. Fluorescence resonance energy transfer sensor-based cAMP measurements reveal that the full-length PDE4A5, in contrast to the truncated form, hampers forskolin-mediated increases in neuronal cAMP levels. Our study indicates that the unique N-terminal localization domain of PDE4A5 is essential for the targeting of specific cAMP-dependent signaling underlying synaptic plasticity and memory. The development of compounds to disrupt the compartmentalization of individual PDE4 isoforms by targeting their unique N-terminal domains may provide a fruitful approach to prevent cognitive deficits in neuropsychiatric and neurocognitive disorders that are associated with alterations in cAMP signaling

Gender Differences in VO2 and HR Kinetics at the Onset of Moderate and Heavy Exercise Intensity in Adolescents

The majority of the studies on VO2 kinetics in pediatric populations investigated gender differences in prepubertal children during submaximal intensity exercise, but studies are lacking in adolescents. The purpose of this study was to test the hypothesis that gender differences exist in the VO2 and heart rate (HR) kinetic responses to moderate (M) and heavy (H) intensity exercise in adolescents. Twenty-one healthy African-American adolescents (9 males, 15.8 ± 1.1 year; 12 females, 15.7 ± 1 year) performed constant work load exercise on a cycle ergometer at M and H. The VO2 kinetics of the male group was previously analyzed (Lai et al., Appl. Physiol. Nutr. Metab. 33:107–117, 2008b). For both genders, VO2 and HR kinetics were described with a single exponential at M and a double exponential at H. The fundamental time constant (τ1) of VO2 was significantly higher in female than male at M (45 ± 7 vs. 36 ± 11 sec, P \u3c 0.01) and H (41 ± 8 vs. 29 ± 9 sec, P \u3c 0.01), respectively. The functional gain (G1) was not statistically different between gender at M and statistically higher in females than males at H: 9.7 ± 1.2 versus 10.9 ± 1.3 mL min−1 W−1, respectively. The amplitude of the slow component was not significantly different between genders. The HR kinetics were significantly (τ1, P \u3c 0.01) slower in females than males at M (61 ± 16 sec vs. 45 ± 20 sec, P \u3c 0.01) and H (42 ± 10 sec vs. 30 ± 8 sec, P = 0.03). The G1 of HR was higher in females than males at M: 0.53 ± 0.11 versus 0.98 ± 0.2 bpm W−1 and H: 0.40 ± 0.11 versus 0.73 ± 0.23 bpm W−1, respectively. Gender differences in the VO2 and HR kinetics suggest that oxygen delivery and utilization kinetics of female adolescents differ from those in male adolescents. © 2016 The Authors