Density Functional Theory Study of the Oligomerization of Carboxylic Acids

D.D.T. thanks the U.K.’s Royal Society for the award of a Royal Society Industry Fellowship. This research utilized Queen Mary’s MidPlus computational facilities, supported by QMUL Research-IT and funded by EPSRC grant EP/K000128/1. Via our membership of the U.K.’s HPC Materials Chemistry Consortium, which is funded by EPSRC (EP/L000202), this work made use of the facilities of HECToR and ARCHER, the U.K.’s national high-performance computing service, which is funded by the Office of Science and Technology through EPSRC’s High End Computing Programme.publisher pdf not permitted, withdraw

Genomic approaches to unveil the physiological pathways activated in Arabidopsis treated with plant-derived raw extracts

DNA microarrays can be used to obtain a fingerprint of the transcriptional status of the plant or cell under a given condition and may be useful for characterising which genes respond, either by induction or repression, to novel stimuli or specific treatments. An in-depth bioinformatical analysis of all the data produced by microarrays can further highlight the metabolic or functional pathways most affected by the treatment. This approach has been used to investigate the effects induced by the treatment of different plant-derived raw materials, provided by Valagro SpA, on Arabidopsis seedlings. A clear example is represented by treatment with a raw plant-derived protein extract (VAL-P01). In this case the treatment induced genes related to ABA and osmotic stress treatment. We therefore demonstrated that VAL-P01 was able to mimic in planta the same pattern of responses linked to ABA treatment or osmotic stress, making the plant stronger against possible further stresses. Another plant extract, VAL-P02, was shown to be significantly altering the transcription of senescence genes, making it an ideal candidate adjuvant for the prolonged shelf-life of vegetal products

Analysis of stranded sea turtles in the Gargano coast: has the Gargano promontory an importance for the ecology of the turtle Caretta caretta (Linnaeus, 1758) in the Adriatic Sea?

During the period 2001-2004, 89 stranded individuals of Caretta caretta (Linnaeus, 1758) have been recorded along the Gargano coast, 58 of which were alive, and 31 dead; in particular, 57% of these former animals have been rescued along two thin strips of land at the Lesina and Varano Lakes. The greatest number of strandings (n=48), has been recorded during the 2002, in particular in January (n=31), a fact which seems to correspond to an abrupt drop of water temperature. The great number of stranded turtles reported in this area depends on its geographical position: the northern shore of Gargano entraps objects carried by the sea currents from the northern and the middle Adriatic Sea to the southern one

Stochastic Turing patterns in the Brusselator model

A stochastic version of the Brusselator model is proposed and studied via the system size expansion. The mean-field equations are derived and shown to yield to organized Turing patterns within a specific parameters region. When determining the Turing condition for instability, we pay particular attention to the role of cross diffusive terms, often neglected in the heuristic derivation of reaction diffusion schemes. Stochastic fluctuations are shown to give rise to spatially ordered solutions, sharing the same quantitative characteristic of the mean-field based Turing scenario, in term of excited wavelengths. Interestingly, the region of parameter yielding to the stochastic self-organization is wider than that determined via the conventional Turing approach, suggesting that the condition for spatial order to appear can be less stringent than customarily believed.Comment: modified version submitted to Phys Rev. E. 5. 3 Figures (5 panels) adde

Modelling the structural evolution of ternary phosphate glasses from melts to solid amorphous materials

The local and medium-range structural properties of phosphate-based melts and glasses have been characterized by means of first principles (density functional theory) and classical (shell-model) molecular dynamics simulations. The structure of glasses with biomedically active molecular compositions, (P2O5)0.45(CaO)x(Na2O)0.55−x (x = 0.30, 0.35 and 0.40), have been generated using first principles molecular dynamics simulations for the full melt-and-quench procedure and the changes in the structural properties as the 3000 K melt is cooled down to room temperature have been compared extensively with those of the final glasses. The melts are characterized by a significant fraction of threefold (P3c) and fivefold (P5c) phosphorus atoms, but structural defects rapidly decrease during the cooling phase and for temperatures lower than 1800 K the system is free of under- and over-coordinated species. The analysis of the structures of the glasses at 300 K shows a prevalence of the metaphosphate Q2 and pyrophosphate Q1 species, whereas the number of Q3 units, which constitute the three-dimensional phosphate network, significantly decreases with the increase of calcium content in the glass. The radial and angular distribution functions indicate that higher calcium concentration in the glass leads to an increase of the rigidity of the phosphate tetrahedral network, which has been explained in terms of the calcium's higher field strength compared to that of sodium. The structural characterization of the melts and glasses obtained from first principles simulations was used to assess and validate a recently developed interatomic shell-model forcefield for phosphate-based materials. For all three compositions, our potential model is in good agreement with the first principles data. In the glass network, the forcefield provides a very good description of the split between the shorter distances of phosphorus to non-bonded oxygen and the longer distances of the phosphorus to bonded oxygen; the phosphorus–phosphorus medium-range distribution; and the coordination environment around the Na and Ca glass modifiers. Moreover, the distribution of the Qn species in the melts and glasses is in excellent agreement with the values extracted from the first principles simulations. In contrast, simulations using standard rigid ion potentials do not provide a satisfactory description of the local short-range structure of phosphate-based glasses and are therefore less suitable to model this class of multicomponent amorphous system

Type-1 (CB1) cannabinoid receptor promotes neuronal differentiation and maturation of neural stem cells .

Neural stem cells (NSCs) are self-renewing cells that can differentiate into multiple neural lineages and repopulate regions of the brain after injury. We have investigated the role of endocannabinoids (eCBs), endogenous cues that modulate neuronal functions including neurogenesis, and their receptors CB1 and CB2 in mouse NSCs. Real-time PCR and Western blot analyses indicated that CB1 is present at higher levels than CB2 in NSCs. The eCB anandamide (AEA) or the CB1-specific agonist ACEA enhanced NSC differentiation into neurons, but not astrocytes and oligodendrocytes, whereas the CB2-specific agonist JWH133 was ineffective. Conversely, the effect of AEA was inhibited by CB1, but not CB2, antagonist, corroborating the specificity of the response. CB1 activation also enhanced maturation of neurons, as indicated by morphometric analysis of neurites. CB1 stimulation caused long-term inhibition of the ERK1/2 pathway. Consistently, pharmacological inhibition of the ERK1/2 pathway recapitulated the effects exerted by CB1 activation on neuronal differentiation and maturation. Lastly, gene array profiling showed that CB1 activation augmented the expression of genes involved in neuronal differentiation while decreasing that of stemness genes. These results highlight the role of CB1 in the regulation of NSC fate and suggest that its activation may represent a pro-neuronal differentiation signal

Modelling the effects of salt solutions on the hydration of calcium ions

Classical molecular dynamics simulations of several aqueous alkali halide salt solutions have been used to determine the effect of electrolytes on the structure of water and the hydration properties of calcium ions. Compared with the simulations of Ca2+ ions in pure liquid water, the frequency of water exchange in the first hydration shell of calcium, which is a fundamental process in controlling the reactivity of calcium(II) aqua-ions, is drastically reduced in the presence of other electrolytes in solution. The strong stabilization of the hydration shell of Ca2+ occurs not only when the halide anions are directly coordinated to calcium, but also when the alkali and halide ions are placed at or outside the second coordination shell of Ca2+, suggesting that the reactivity of the first solvation shell of the calcium ion can be influenced by the specific affinity of other ions in solution for the water molecules coordinated to Ca2+. Analysis of the hydrogen-bonded structure of water in the vicinity of the calcium ion shows that the average number of hydrogen bonds per water molecules, which is 1.8 in pure liquid water, decreases as the concentration of alkali–halide salts in solution increases, and that the temporal fluctuations of hydrogen bonds are significantly larger than those obtained for Ca2+ in pure liquid water. This effect has been explained in terms of the dynamics of reorganization of the O–H X (X = F, Cl and Br) hydrogen bond. This work shows the importance of solution composition in determining the hydrogen-bonding network and ligand-exchange dynamics around metal ions, both in solution and at the mineral–water interfaces, which in turn has implications for interactions occurring at the mineral–water interface, ultimately controlling the mobilization of ions in the environment as well as in industrial processes

Treatment of a rapidly expanding thoracoabdominal aortic aneurysm after endovascular repair of descending thoracic aortic aneurysm in an old patient.

Background: Aortic pathology progression and/or procedure related complications following endovascular repair should always be considered mostly in older patients. We herein describe a hybrid procedure for treatment of rapidly expanding thoracoabdominal aneurysm following endovascular treatment of a descending thoracic aortic aneurysm in an older patient. Case presentation: A 82-year-old man at 18 months after endovascular surgery for a contained rupture of descending thoracic aortic aneurysm revealed a type IV thoracoabdominal aneurysm with significant increase of the aortic diameters at superior mesenteric and renal artery levels. A hybrid approach consisting of preventive visceral vessel revascularization and endovascular repair of entire abdominal aorta was performed. Under general anaesthesia and by xyphopubic laparotomy, the infrarenal aneurysmatic aorta and common iliac arteries were replaced by a bifurcated woven prosthetic graf. From each of the prosthetic branches two reverse 14x7 mm bifurcated PTFE prosthetic grafts were anastomized to both renal arteries and to the celiac axis and superior mesenteric artery, respectively. Vessel ischemia was restricted to the time required for anastomosis. Three 10 cm Gore endovascular stent-grafts for a total length of 15 cm, were used. The overlapping of the stent-grafts was carried out from the bottom upwards, starting from the aorto-iliac prosthetic body up to the healthy segment of thoracic aorta, 40 mm from the previous stent-grafts. The patient was discharged on the 9th postoperative day. Conclusion: This technique offers the advantage of a less invasive treatment, reducing the risk of paraplegia, visceral ischaemia and pulmonary complications, mostly in older patients