Rotatable crucible for rapid solidification process

This invention relates to an apparatus for producing filament, fiber, ribbon or film from a molten material, comprising a preferably heat extracting crucible which contains a pool of molten material at a selected horizontal level in the pool. The crucible has an opening extending from above the free surface level to a bottom edge of the opening, the bottom edge being sufficiently below the free surface level so that the molten material cannot form and hold a meniscus by surface tension between the edge and the level of the free surface and further comprises a heat extracting substrate laterally disposed with respect to the crucible and which rotates about an axis of rotation. The substrate is positioned adjacent the edge of the opening which confines the molten material and prevents it from overflowing downwardly out of the crucible. The invention features rotating means which includes a first drive means for tiltably rotating the crucible about an axis of rotation which is coaxial with the axis of rotation of the substrate, so the crucible edge can be maintained a predetermined constant distance from the substrate. The distance chosen is suitable for depositing molten material on the substrate and the apparatus also has a second drive means which is drivingly connected to the substrate for continuously moving the surface of the substrate upwardly past the edge and a melt front formed at the interface of the molten material and the substrate surface

Rapidly solidified titanium alloys by melt overflow

A pilot plant scale furnace was designed and constructed for casting titanium alloy strips. The furnace combines plasma arc skull melting techniques with melt overflow rapid solidification technology. A mathematical model of the melting and casting process was developed. The furnace cast strip of a suitable length and width for use with honeycomb structures. Titanium alloys Ti-6Al-4V and Ti-14Al-21 Nb were successfully cast into strips. The strips were evaluated by optical metallography, microhardness measurements, chemical analysis, and cold rolling

Beyond relativistic Lagrangian perturbation theory. I. An exact-solution controlled model for structure formation

We develop a new nonlinear method to model structure formation in general relativity from a generalization of the relativistic Lagrangian perturbation schemes, controlled by Szekeres (and LTB) exact solutions. The overall approach can be interpreted as the evolution of a deformation field on an inhomogeneous reference model, obeying locally Friedmann-like equations. In the special case of locally one-dimensional deformations, the new model contains the entire Szekeres family of exact solutions. As thus formulated, this approach paraphrases the Newtonian and relativistic Zel'dovich approximations, having a large potential for applications in contexts where relativistic degrees of freedom are relevant. Numerical simulations are implemented to illustrate the capabilities and accuracy of the model.Comment: 19 pages, 3 figures, submitted to PR

On general-relativistic Lagrangian perturbation theory and its non-perturbative generalization

The Newtonian Lagrangian perturbation theory is a widely used framework to study structure formation in cosmology in the nonlinear regime. We review a general-relativistic formulation of such a perturbation approach, emphasizing results on already developed extensive formalism including among other aspects: the non-perturbative modeling of Ricci and Weyl curvatures, gravitational waves and pressure-supported fluids. We discuss subcases of exact solutions related to Szekeres Class II and, as exact average model, Ricci-flat LTB models. This latter forms the basis of a generalization that we then propose in terms of a scheme that goes beyond the relativistic Lagrangian perturbation theory on a global homogeneous-isotropic background cosmology. This new approximation does not involve a homogeneous reference background and it contains Szekeres class I (and thus general LTB models) as exact subcases. Most importantly, this new approximation allows for the interaction of structure with an evolving `background cosmology', conceived as a spatial average model, and thus includes cosmological backreaction.Comment: 26 pages, 4 figures, matches published version in Univers

Multi-objective ant colony optimization for the twin-screw configuration problem

The Twin-Screw Configuration Problem (TSCP) consists in identifying the best location of a set of available screw elements along a screw shaft. Due to its combinatorial nature, it can be seen as a sequencing problem. In addition, different conflicting objectives may have to be considered when defining a screw configuration and, thus, it is usually tackled as a multi-objective optimization problem. In this research, a multi-objective ant colony optimization (MOACO) algorithm was adapted to deal with the TSCP. The influence of different parameters of the MOACO algorithm was studied and its performance was compared with that of a previously proposed multi-objective evolutionary algorithm and a two-phase local search algorithm. The experimental results showed that MOACO algorithms have a significant potential for solving the TSCP.This work has been supported by the Portuguese Fundacao para a Ciencia e Tecnologia under PhD grant SFRH/BD/21921/2005. Thomas Stutzle acknowledges support of the Belgian F.R.S-FNRS of which he is a research associate, the E-SWARM project, funded by an ERC Advanced Grant, and by the Meta-X project, funded by the Scientific Research Directorate of the French Community of Belgium

The HR 4796A Debris System: Discovery of Extensive Exo-Ring Dust Material

The optically and IR bright, and starlight-scattering, HR 4796A ring-like debris disk is one of the most (and best) studied exoplanetary debris systems. The presence of a yet-undetected planet has been inferred (or suggested) from the narrow width and inner/outer truncation radii of its r = 1.05" (77 au) debris ring. We present new, highly sensitive, Hubble Space Telescope (HST) visible-light images of the HR 4796A circumstellar debris system and its environment over a very wide range of stellocentric angles from 0.32" (23 au) to ~ 15" (1100 au). These very high contrast images were obtained with the Space Telescope Imaging Spectrograph (STIS) using 6-roll PSF-template subtracted coronagraphy suppressing the primary light of HR 4796A and using three image plane occulters and simultaneously subtracting the background light from its close angular proximity M2.5V companion. The resulting images unambiguously reveal the debris ring embedded within a much larger, morphologically complex, and bi-axially asymmetric exoring scattering structure. These images at visible wavelengths are sensitive to, and map, the spatial distribution, brightness, and radial surface density of micron size particles over 5 dex in surface brightness. These particles in the exo-ring environment may be unbound from the system and interacting with the local ISM. Herein we present a new morphological and photometric view of the larger than prior seen HR 4796A exoplanetary debris system with sensitivity to small particles at stellocentric distances an order of magnitude greater than has previously been observed.Comment: 28 pages, 17 figures, accepted for publication in the Astronomical Journal 21 December 201

Clearing up the photochemistry of resveratrol: Effect of the solvent

Polyphenolic substances synthesized by plants are generally involved in protection against UV radiation and the attack of pathogenic microorganisms. Resveratrol (3,5,4′-trihydroxystilbene, RSV) is synthesized in its trans-form (trans-RSV) in plants under stress conditions like infections or UV exposure and has attracted attention as an antioxidant agent. Trans-RSV was irradiated with both UV-A (λMAX = 365 nm) and UV-B (λMAX = 300 nm) radiation in aqueous and ethanolic solutions at room temperature. The reactions were followed by UV–Vis spectrophotometry, HPLC with UV and fluorescence detection, and UPLC coupled to mass spectrometry detection. In both solvents the irradiation caused the fast isomerization of trans-RSV to cis-RSV. In ethanolic solutions, a strong fluorescent compound, identified as resveratrone (RSVT) was detected independently on the irradiation wavelength. In aqueous solutions, RSVT was not detected in both irradiation conditions. However, in aqueous/ethanol mixtures the amount RSVT was found to be proportional to the amount of ethanol in the solution. Under UV-B irradiation, both in ethanolic or water solutions other products were detected. Our results demonstrated that RSV is photosensitive and its photochemistry depends on the solvent nature and on the irradiation wavelength.Fil: Gaspar Tosato, Maira. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - La Plata. Instituto de Investigaciones Fisicoquímicas Teóricas y Aplicadas. Universidad Nacional de La Plata. Facultad de Ciencias Exactas. Instituto de Investigaciones Fisicoquímicas Teóricas y Aplicadas; ArgentinaFil: Vicendo, Patricia. Université Toulouse III - Paul Sabatier; FranciaFil: Thomas, Andrés Héctor. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - La Plata. Instituto de Investigaciones Fisicoquímicas Teóricas y Aplicadas. Universidad Nacional de La Plata. Facultad de Ciencias Exactas. Instituto de Investigaciones Fisicoquímicas Teóricas y Aplicadas; ArgentinaFil: Lorente, Carolina. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - La Plata. Instituto de Investigaciones Fisicoquímicas Teóricas y Aplicadas. Universidad Nacional de La Plata. Facultad de Ciencias Exactas. Instituto de Investigaciones Fisicoquímicas Teóricas y Aplicadas; Argentin

Increasing fluid intake and reducing dehydration risk in older people living in long-term care: a systematic review

Objective: To assess the efficacy of interventions and environmental factors on increasing fluid intake or reducing dehydration risk in older people living in long-term care facilities. Design: Systematic review of intervention and observational studies. Data Sources: Thirteen electronic databases were searched from inception until September 2013 in all languages. References of included papers and reviews were checked. Eligibility criteria: Intervention and observational studies investigating modifiable factors to increase fluid intake and/or reduce dehydration risk in older people (≥65 years) living in long-term care facilities who could drink orally. Review methods: Two reviewers independently screened, selected, abstracted data and assessed risk of bias from included studies, narrative synthesis was performed. Results: 4328 titles and abstracts were identified, 325 full-text papers obtained and 23 included in the review. Nineteen intervention and 4 observational studies from 7 countries investigated factors at resident, institutional or policy level. Overall the studies were at high risk of bias due to selection and attrition bias and lack of valid outcome measures of fluid intake and dehydration assessment. Reported findings from six of the nine intervention studies investigating the effect of multi-component strategies on fluid intake or dehydration described a positive effect. Components included greater choice and availability of beverages, increased staff awareness, increased staff assistance with drinking and toileting. Implementation of the US Resident Assessment Instrument reduced dehydration prevalence from 3% to 1%, p=0.01. Two smaller studies reported positive effects, one on fluid intake in 9 men with Alzheimer's Disease using high-contrast red cups, the other involved supplementing 13 mildly dehydrated residents with oral hydration solution over 5 days to reduce dehydration. Modifications to the dining environment, advice to residents, presentation of beverages and mode of delivery (straw vs beaker; pre-thickened drinks vs those thickened at the bedside) were inconclusive. Two large observational studies with good internal validity investigated effects of ownership; in Canada, for-profit ownership was associated with increased hospital admissions for dehydration; no difference was seen in dehydration prevalence between US for-profit and not-for-profit homes, although chain facilities were associated with lower odds of dehydration. This US study did not suggest any effect of staffing levels on dehydration prevalence. Conclusions: A wide range of interventions and exposures were identified, but the efficacy of many strategies remains unproven due to the high risk of bias present in many studies. Reducing dehydration prevalence in long-term care facilities is likely to require multiple strategies involving policymakers, management and care staff, but these require further investigation using more robust study methodologies. Systematic review registration: The review protocol was registered with the International Prospective Register of Systematic Reviews (http://www.crd.york.ac.uk/PROSPERO/display_record.asp? ID=CRD42012003100)

Special symposium: In vitro plant recalcitrance loss of plant organogenic totipotency in the course of In vitro neoplastic progression

Summary: The aptitude for organogenesis from normal hormone-dependent cultures very commonly decreases as the tissues are serially subcultured. The reasons for the loss of regenerative ability may vary under different circumstances: genetic variation in the cell population, epigenetic changes, disappearance of an organogenesis-promoting substance, etc. The same reasons may be evoked for the progressive and eventually irreversible loss of organogenic totipotency in the course of neoplastic progressions from hormone-independent tumors and hyperhydric teratomas to cancers. As in animal cells, plant cells at the end of a neoplastic progression have probably undergone several independent genetic accidents with cumulative effects. They indeed are characterized by atypical biochemical cycles from which they are apparently unable to escape. The metabolic changes are probably not the primary defects that cause cancer, rather they may allow the cells to survive. How these changes, namely an oxidative stress, affect organogenesis is not known. The literature focuses on somatic mutations and epigenetic changes that cause aberrant regulation of cell cycle genes and their machiner