Origin of the Felkin-Anh(-Eisenstein) model: a quantitative rationalization of a seminal concept.

Quantum chemical calculations were carried out to quantitatively understand the origin of the Felkin-Anh(-Eisenstein) model, widely used to rationalize the π-facial stereoselectivity in the nucleophilic addition reaction to carbonyl groups directly attached to a stereogenic center. To this end, the possible approaches of cyanide to both ()-2-phenylpropanal and ()-3-phenylbutan-2-one have been explored in detail. With the help of the activation strain model of reactivity and the energy decomposition analysis method, it is found that the preference for the Felkin-Anh addition is mainly dictated by steric factors which manifest in a less destabilizing strain-energy rather than, as traditionally considered, in a lower Pauli repulsion.

Exploring the Role of Central Metals in Bulky Phthalocyanines for Dye-Sensitized Solar Cells.

Two series of metallo-(Zn(II), Mg(II), and Ru(II)) and free-base phthalocyanines (Pcs) with a carboxyl anchoring group and well-established bulky peripheral substituents (either tert-butyl or bulky 2,6-diisopropylphenoxy) were synthesized and tested as sensitizers in dye-sensitized solar cells (DSSCs). The trend of photovoltaic efficiencies (PCEs) for free-base and metallo Pcs followed the order Zn(II)Pc>Mg(II)Pc≫H2Pc ≈ Ru(II)Pc regardless of the peripheral substitution. Higher efficiencies (4.

What defines electrophilicity in carbonyl compounds.

The origin of the electrophilicity of a series of cyclohexanones and benzaldehydes is investigated using the activation strain model and quantitative Kohn-Sham molecular orbital (MO) theory. We find that this electrophilicity is mainly determined by the electrostatic attractions between the carbonyl compound and the nucleophile (cyanide) along the entire reaction coordinate. Donor-acceptor frontier molecular orbital interactions, on which the current rationale behind electrophilicity trends is based, appear to have little or no significant influence on the reactivity of these carbonyl compounds.

Supramolecular Block Copolymers from Tricarboxamides. Biasing Co-assembly by the Incorporation of Pyridine Rings.

The synthesis of a series of triangular-shaped tricarboxamides endowed with three picoline or nicotine units (compounds 2 and 3, respectively) or just one nicotine unit (compound 4) is reported, and their self-assembling features investigated. The pyridine rings make compounds 2-4 electronically complementary with our previously reported oligo(phenylene ethynylene)tricarboxamides (OPE-TA) 1 to form supramolecular copolymers. C -symmetric tricarboxamide 2 forms highly stable intramolecular five-membered pseudocycles that impede its supramolecular polymerization into poly-2 and the co-assembly with 1 to yield copolymer poly-1-co-2.

Understanding the Reactivity of Diazaborinines towards the Activation of σ-Bonds.

The poorly understood factors governing the small molecule activation reactions mediated by diazaborinines have been computationally explored in detail using quantum chemical tools. To this end, the activation of E-H σ-bonds (E = H, C, Si, N, P, O, S) has been investigated. These reactions, which proceed in a concerted manner, are exergonic and, in general, associated with relatively low activation barriers.

Top-down and bottom-up effects modulate species co-existence in a context of top predator restoration.

Mesopredators abundance is often limited by top-order predators and also by key food resources. However, the contribution of these bidirectional forces to structure carnivore community is still unclear. Here, we studied how the presence and absence of an apex predator which is currently recovering its former distribution range, the Iberian lynx (Lynx pardinus), determined the absolute abundance and fine-scale spatiotemporal avoidance mechanisms of two sympatric mesocarnivores (stone marten Martes foina and common genet Genetta genetta) with different dietary plasticity.

Consistent histories through pragmatist lenses.

This article adopts a bottom-up approach to theory interpretation, following the slogan "meaning is use", and applies it to quantum mechanics. I argue that it fits very well with the Consistent Histories formulation of quantum mechanics, interpreted in a particular way that is not the interpretation favoured by original proponents of the formulation. I examine the difficulties and advantages of this interpretation.

Effectiveness of Neuromuscular Electrical Stimulation and Dynamic Mobilization Exercises on Equine Multifidus Muscle Cross-Sectional Area.

Equine back pain can potentially initiate an unstable intervertebral situation that results in atrophy and dysfunction of the epaxial muscles even after back pain has resolved. Several physiotherapy approaches are advocated to promote the strengthening of the multifidus muscle. This study aimed to asses and compare the effect of dynamic mobilization exercises (DME) and neuromuscular electrical stimulation (NMES) in 8 adult horses (4 individuals by group) to increase the cross-sectional area (CSA) of this muscle after a 7-weeks period treatment.

Supramolecular polymerization of electronically complementary linear motifs: anti-cooperativity by attenuated growth.

Anti-cooperative supramolecular polymerization by attenuated growth exhibited by self-assembling units of two electron-donor benzo[1,2-:4,5-']dithiophene (BDT) derivatives (compounds 1a and 1b) and the electron-acceptor 4,4-difluoro-4-bora-3,4-diaza--indacene (BODIPY) (compound 2) is reported. Despite the apparent cooperative mechanism of 1 and 2, AFM imaging and SAXS measurements reveal the formation of small aggregates that suggest the operation of an anti-cooperative mechanism strongly conditioned by an attenuated growth. In this mechanism, the formation of the nuclei is favoured over the subsequent addition of monomeric units to the aggregate, which finally results in short aggregates.

How proton transfer affects the helical parameters in DNA:DNA microhelices.

Proton transfer reactions are a widespread phenomenon in many areas of the life sciences and it is one of the origins of the spontaneous point mutations during DNA replication. Because of its importance, many studies have been reported on these reactions. However, the present work is the first one focused on the structural geometrical changes by double proton transfer (DPT).

Unveiling the Role of Hydrogen Bonds in Luminescent N-Annulated Perylene Liquid Crystals.

We report the liquid-crystalline (LC) and luminescent properties of a series of N-annulated perylenes (1-4) in whose molecular structures amide and ester groups alternate. We found that the LC properties of these compounds not only depend on the number of hydrogen-bonding units, but also on the relative position of the amide linkers in the molecule. The absence of amide groups in compound 1 leads to no LC properties, whereas four amide groups induce the formation of a wide temperature range columnar hexagonal phase in compound 4.

Perinatal undernourishment provokes long-lasting alterations of clusterin and fumarate hydratase expression in the rat nucleus accumbens.

Background: Background: Perinatal malnutrition seems to provoke important neurochemical alterations in the brain that lead to higher vulnerability to develop neuropsychiatric disorders in the adulthood.

Objectives: We have examined the persistence and reversibility of the changes induced by perinatal undernourishment on the expression of fumarate hydratase in the rat nucleus accumbens, bearing in mind that this expression has been previously linked with addictive disorders. Clusterin, a multifunctional protein known to be neuroprotective and possibly related to addiction in humans, was studied in parallel.

Synthesis, Neuroprotection, and Antioxidant Activity of 1,1'-Biphenylnitrones as α-Phenyl--butylnitrone Analogues in In Vitro Ischemia Models.

Herein, we report the neuroprotective and antioxidant activity of 1,1'-biphenyl nitrones () - as α-phenyl---butylnitrone analogues prepared from commercially available [1,1'-biphenyl]-4-carbaldehyde and [1,1'-biphenyl]-4,4'-dicarbaldehyde. The neuroprotection of - has been measured against oligomycin A/rotenone and in an oxygen-glucose deprivation in vitro ischemia model in human neuroblastoma SH-SY5Y cells. Our results indicate that - have better neuroprotective and antioxidant properties than α-phenyl---butylnitrone (), and they are quite similar to -acetyl-L-cysteine (), which is a well-known antioxidant agent.

Three Bis-BODIPY Analogous Diruthenium Redox Series: Characterization and Electronic Structure Analysis.

The dianion derived from (2Z,6Z)-3,7-diphenyl-N2,N6-di(pyridin-2-yl)pyrrolo[2,3-f]indole-2,6(1H,5H)-diimine (H BL), a modified BODIPY ligand precursor, is shown to be capable of bridging two metal complex fragments RuL , L=2,4-pentanedionato (acac ), 2,2'-bipyridine (bpy) or 2-phenylazopyridine (pap) in [Ru(acac) Ru(μ-BL)Ru(acac) ] (1/2), [Ru(bpy) Ru(μ-BL)Ru(bpy) ](ClO ) ([3](ClO ) ) and [Ru(pap) Ru(μ-BL)Ru(pap) ](ClO ) ([4](ClO ) ). The compounds, including a diastereoisomeric pair 1 (meso) and 2 (rac) were spectroscopically and structurally characterized. Reversible electron transfers as revealed by cyclic and differential pulse voltammetry allowed for an EPR and UV-vis-NIR spectroelectrochemical investigation of several neighboring charge states.

Flavonoids of Tripodanthus acutifolius inhibit TNF-α production in LPS-activated THP-1 and B16-F10 cells.

Ethnopharmacological Relevance: T. acutifolius is an endemic species from South America which has been used in traditional medicine since ancient times due to its biological properties, including its anti-inflammatory effects.

Aim Of The Study: The aim of the article is to investigate the inhibitory activity of T.

Rapid Communication: Maternal melatonin implants improve fetal oxygen supply and body weight at term in sheep pregnancies.

Fetal hypoxia, resulting in oxidative stress in pregnancies, contributes to reduced fetal growth. Melatonin, a potent antioxidant, has been associated with improved oxidative status. Maternal oral melatonin supplementation in sheep from day 50 of gestation ameliorates the consequences of fetal growth restriction in sheep.

New Tacrines as Anti-Alzheimer's Disease Agents. The (Benzo)Chromeno- PyranoTacrines.

Tacrine was the first drug approved by FDA (US) for the treatment of Alzheimer's disease suffering patients. Nowadays, this agent has been withdrawn from the clinics due to secondary effects, which, most importantly, include hepatotoxicity. However, the research on new tacrine analogues devoid of these therapeutically undesirable effects, but benefiting of their high and well known positive cholinergic power, has produced a number of new non-hepatotoxic tacrines.

Reproductive long-term effects, endocrine response and fatty acid profile of rabbit does fed diets supplemented with n-3 fatty acids.

The effect of a diet enriched with polyunsaturated n-3 fatty acids (PUFA) on endocrine, reproductive, and productive responses of rabbit females and the litters has been studied. Nulliparous does (n=125) were fed ad libitum from rearing to second weaning two diets supplemented with different fat sources: 7.5g/kg lard for the control diet (group C; n=63) or 15g/kg of a commercial supplement containing a 50% ether extract and 35% of total fatty acids (FAs) as PUFA n-3 (Group P; n=62).

Invariant grating pseudoimaging using polychromatic light and a finite extension source.

The Talbot effect is a well studied phenomenon by which grating pseudoimages appear at certain periodic distances when monochromatic light is used. Recently, numerical simulations have shown a new phenomenon; when a polychromatic light beam is used in a double grating system, the intensity of the pseudoimages presents a transverse-profile that remains unaffected over a wide range of propagation distances. This effect can be used to increase the tolerances of gratings based optical devices, such as displacement measurement systems, interferometers, and spectrometers.

[Failure in the control of the number of traffic accident victims in Spain. Is this a result of the correct answer to the wrong question?].

Although various measures have been implemented in Spain with the aim to modifying the behavior of motor vehicle users, it has not been observed a descending trend in traffic accident and injuries from traffic accident. This article considers the question of whether the measures taken to reduce motor vehicle crash-related injuries in Spain have targeted the causes that are truly responsible for this trend. Using several sources of data, beginning in 1990 it has been observed a significant reduction in traffic accidents and their consequences, but in the second half of the 90s the growth in motor vehicle crash-related injuries was similar to the increase observed in the 80s.