In-plane structure and ordering at liquid sodium surfaces and interfaces from ab initio molecular dynamics

Atoms at liquid metal surfaces are known to form layers parallel to the surface. We analyze the two-dimensional arrangement of atoms within such layers at the surface of liquid sodium, using ab initio molecular dynamics (MD) simulations based on density functional theory. Nearest neighbor distributions at the surface indicate mostly 5-fold coordination, though there are noticeable fractions of 4-fold and 6-fold coordinated atoms. Bond angle distributions suggest a movement toward the angles corresponding to a six-fold coordinated hexagonal arrangement of the atoms as the temperature is decreased towards the solidification point. We rationalize these results with a distorted hexagonal order at the surface, showing a mixture of regions of five and six-fold coordination. The liquid surface results are compared with classical MD simulations of the liquid surface, with similar effects appearing, and with ab initio MD simulations for a model solid-liquid interface, where a pronounced shift towards hexagonal ordering is observed as the temperature is lowered

Stable nitrile oxide dipolar cycloadditions in pure water

A systematic study on the behaviour of stable 2,4,6-trimethyl-3,5-dichlorobenzonitrile oxide versus a number of mono-, bi- and trisubstituted dipolarophiles in water was pursued obtaining simple as well as annulated isoxazolines. Reaction conditions changed with the dipolarophilic species, according to their solubility in water and the degree of substitution of the reactive carbon\u2013carbon multiple bond. The presence of sodium dodecylsulfate was also tested as potential micellar catalyst

Trans-nasal endoscopic and intra-oral combined approach for odontogenic cysts

Maxillary cysts are a common finding in maxillofacial surgery, dentistry and otolaryngology. Treatment is surgical; a traditional approach includes Caldwell-Luc and other intra-oral approaches. In this article, we analyse the outcomes of 9 patients operated on using a combined intra-oral and trans-nasal approach to the aforementioned disease. Although the number of patients is small, the good results of this study suggest that the combined approach might be a reliable treatment option

The Roles of External Forcings and Internal Variabilities in the Northern Hemisphere Atmospheric Circulation Change from the 1960s to the 1990s

Abstract The Northern Hemisphere atmospheric circulation change from the 1960s to the 1990s shows a strong positive North Atlantic Oscillation (NAO) and a deepening of the Aleutian low. The issue regarding the contributions of external forcings and internal atmospheric variability to this circulation change has not been resolved satisfactorily. Previous studies have found the importance of tropical SST forcing. Here, this hypothesis is examined again using relatively large ensembles of atmospheric general circulation model simulations of the twentieth-century climate forced only by historically varying SST. The resulting ensemble-mean amplitude underestimates the observed change by at least 70%, although the spatial pattern is reproduced well qualitatively. Furthermore, AGCM experiments are performed to investigate other driving factors, such as the greenhouse gases, sea ice, the stratospheric ozone, as well as the contribution from atmospheric internal variability. The increase in ensemble-mean trend amplitude induced by these additional drivers was not enough to substantially improve the agreement with the observed trend. However, the full distribution of simulated trends reveals that the ensemble members at the upper tail are much closer to the observed amplitude. In the "best" ensemble, the 95th percentile of the simulated NAO trend amplitude remains at about 80% of the observed trend amplitude, with nearly equal contributions from external forcings and internal variability. The results also indicate that a complete set of driving factors and a correct simulation of stratospheric trends are important in bridging the gap between observed and modeled interdecadal variability in the North Atlantic winter circulation

A rare cause of dysphagia due to retropharyngeal foregut duplication cyst: case report and review of the literature

Background: The retropharyngeal space is a deep compartment of the head and neck region which extends from the base of the skull to the mediastinum, between the posterior pharyngeal wall and vertebral muscles, delimited laterally by carotid sheaths. Pathological processes of the retropharyngeal space are rarely encountered, generally are isolated and painless masses often cystic, and they usually originate from branchial arch anomalies, but only in rare cases, they turn out to be foregut duplication cysts. Foregut duplication cyst is rare congenital malformations arising along primitively derived alimentary tract during the first trimester in the developing embryo, mostly seen in the thorax and abdomen, with just few cases reported in the head and neck region. We report an extremely rare case of a foregut duplication cyst lined with respiratory epithelium located in the retropharyngeal space, at the level of the oropharynx, of an adult patient with dysphagia surgically treated, and we also made an analysis of the published literature about this very uncommon condition. Case presentation: A 63-year-old male patient with chronic dysphagia was diagnosed with a retropharyngeal cystic lesion, which was surgically treated. Final pathologic evaluation confirmed the diagnosis of a rare foregut duplication cyst lined with respiratory epithelium. A review of the pertaining published literature about the head and neck foregut duplication cysts was made, with a particular emphasis on retropharyngeal ones. Conclusions: Retropharyngeal foregut duplication cysts are a very rare congenital cyst of the head and neck. Clinical symptoms such as dysphagia and dyspnea should be evaluated with fibrolaryngoscopy, and CT and MRI scans are of great significance for definitive diagnosis, which should include the possibility of a foregut duplication cyst in the differential diagnosis. Surgical excision is the elective treatment for this lesion, in order to prevent complications including infection and compression symptoms or eventually malignant transformation

Structural relaxations in electronically excited poly(para-phenylene)

Structural relaxations in electronically excited poly(para-phenylene) are studied using many-body perturbation theory and density-functional-theory methods. A sophisticated description of the electron-hole interaction is required to describe the energies of the excitonic states, but we show that the structural relaxations associated with exciton formation can be obtained quite accurately within a constrained density-functional-theory approach. We find that the structural relaxations in the low-energy excitonic states extend over about 8 monomers, leading to an energy reduction of 0.22 eV and a Stokes shift of 0.40 eV.Comment: 4 pages, 3 figure

Critical assessment of thermal conductivity models for Miscibility Gap Alloy-based composite Phase Change Materials for high temperature Thermal Energy Storage

Miscibility Gap Alloys (MGAs), such as Al-Sn-based systems, provide a viable solution for the development of composite Phase Change Materials (PCMs) for Thermal Energy Storage (TES) purposes. Their successful production depends on the cooling rate imposed to the melt. Finite Element Analyses (FEA), which relies also on thermal conductivity values, represent a powerful tool for the design of the production process. Thermal conductivity, which depends on the arrangement of the phases in the system, also affects the thermal response of the alloy. In the view of evaluating the impact of the phase morphology, the authors adapted some of the models developed for composites and solutions to Al-Sn and Al-Sn-Si-Mg alloys, characterized by broad solidification ranges in terms of composition and temperature and by significantly different phases thermal conductivity. In the fully-liquid range, Filippov and Novoselova model was selected for the description of both alloys. Models that consider sphere-like dispersions give values quite close to the theoretical upper Wiener bound when the high-melting phase is solid. The phase morphology impact is relevant when the solidification range is considered. The resulting arrangement-related thermal conductivity curves are compared to those supplied by CALPHAD-based software and to available literature data

Folded Radial Forearm Free Flap for the Reconstruction of Total Soft Palate Defects: Operative Technique

Background: The surgical plan to reconstruct the palate must be carefully prepared given the morphological peculiarity of the soft palate forming both the roof of the mouth and the floor of the nasal cavity. This article focuses on the use of folded radial forearm free flaps to manage isolated defects of the soft palate in the absence of tonsillar pillar involvement. Methods: Three patients affected by squamous cell carcinoma of the palate underwent resection of the soft palate and immediate reconstruction with a folded radial forearm free flap. Results: All three patients showed good short-term morphological-functional outcomes as far as swallowing, breathing, and phonation were concerned. Conclusions: The folded radial forearm free flap seems to be an efficacious way to manage localized defects of the soft palate, given the positive outcomes of the three patients treated, and in accordance with other authors. In general, the radial forearm free flap was confirmed to be a versatile solution for those intraoral defects of the soft tissue requiring a limited quantity of volume as in the case of the soft palate

Trans-nasal endoscopic and intra-oral combined approach for odontogenic cysts

Maxillary cysts are a common finding in maxillofacial surgery, dentistry and otolaryngology. Treatment is surgical; a traditional approach includes Caldwell-Luc and other intra-oral approaches. In this article, we analyse the outcomes of 9 patients operated on using a combined intra-oral and trans-nasal approach to the aforementioned disease. Although the number of patients is small, the good results of this study suggest that the combined approach might be a reliable treatment option