The analysis of the electronic properties of strained or lattice deformed graphene combines ideas from classical condensed matter physics, soft matter, and geometrical aspects of quantum field theory ...(QFT) in curved spaces. Recent theoretical and experimental work shows the influence of strains in many properties of graphene not considered before, such as electronic transport, spin-orbit coupling, the formation of Moiré patterns, optics, ... There is also significant evidence of anharmonic effects, which can modify the structural properties of graphene. These phenomena are not restricted to graphene, and they are being intensively studied in other two dimensional materials, such as the metallic dichalcogenides. We review here recent developments related to the role of strains in the structural and electronic properties of graphene and other two dimensional compounds.
We study the surface resistivity of a three-dimensional topological insulator when the boundaries exhibit a non trivial curvature. We obtain an analytical solution for a spherical topological ...insulator, and we show that a non trivial quantum spin connection emerges from the three dimensional band structure. We analyze the effect of the spin connection on the scattering by a bump on a flat surface. Quantum effects induced by the geometry lead to resonances when the electron wavelength is comparable to the size of the bump.
Five important magnesite mines and small occurrences in the state of Ceará form a sequence of lenses that extend, discontinuously, for over 140km. The magnesite rocks are hosted by metadolomites with ...lutecite, sulphate nodules pseudomorphosed by fiber-radiated quartz, scapolite and dissolution breccias. This metacarbonate sequence is more voluminous and more calcic in the southwestern extremity of the belt, but less voluminous and more magnesian towards the northeastern portion of the belt, the highest Mg contents being observed in the Alencar-Orós region. Magnesite deposits pass gradually into metadolomites and then to almost pure calcitic marbles westward the belt. This group is hosted in a greenschists to amphibolite-facies metavolcanic-sedimentary sequence crosscut by basic sills and granitic intrusions of variable size, form, composition and age (middle to late Proterozoic ∼550Ma).Two types of magnesite marble may be distinguished: (1) medium-grained (1 to 9mm) and (2) sparry-magnesite marble (1 to 15cm). The latter displays wide textural variation (porphyric, rosette, layered and palisadic types) and exhibits remnants of the original sedimentary features. The sparry crystals, in spite of their deformation, are hypidiomorphic and pinolitic. The colors vary from white to light or dark gray, or even red. The dark banded term presents traces of microfossils and stromatolites structures. The medium-grained magnesite marble, on the other hand, shows more homogeneous texture and color and anhedral crystals are more abundant.The sparry-magnesite marble is less enriched in SiO2, Fe2O3, Al2O3 and CaO and richer in MgO than the medium-grained ones. The magnesitic marbles display positive Ce, and negative Eu anomalies. This suggests a shallow marine platform environment with continental, reduced influence (lagunar). These magnesitic marbles also show positive Ce and Eu anomalies in relation to the present seawater, suggesting compositional differences, materialized mainly by an enrichement of these elements in the past seawater.Fluid inclusions in the medium-grained magnesites of the Riacho Fundo deposit are aqueous inclusions, while in the sparry magnesite deposits, particularly in Cabeça de Negro, aquo-carbonic inclusions dominate. Hydrocarbons, however, are found in both cases.The calcitic marble, deposited on open-marine environment, displays positive13C (+0.5 to 2.1 ‰ PDB), while dolomitic to dolostone marbles, deposited on less open marine environment, display negative shift (0.7 to −3.2‰ PDB). This13C fluctuation is within the range for carbonates deposited around 1.8Ga.The depositional environment of these carbonates is close to a paralic system, lagoon, with strong evaporitic conditions. The depressions were of variable depth and lengths and could be isolated, in particular by stromatolitic barriers, dried and flooded by seawater with continental inflows. The largest and deepest ones correspond to the sparry magnesite deposits. These magnesites are located in a lateral way to almost pure calcitic marbles, through dolomitic marbles. This points to a process of chemical differentiation within a paralic system, from open sea to landwards, more calcic in the first to more magnesian in the confined environment, in which lagoon waters are progressively purified from Ca through preferential precipitation of calcic carbonates and secondly of gypsum/anhydrite, which increases the Mg/Ca ratio, and lead carbonate deposits towards the magnesite pole. These metacarbonates also reveal a fractionation of the light REE, starting from the calcitic, through the dolomitic to magnesitic marbles. In the calcitic marbles, REE are in association with the clay fraction, while in magnesitic marbles, they seem to be in association with organic and/or soluble complexes. The magnesitic marbles are of sedimentary origin and underwent important diagenetic evolution before being metamorphosed during the Brasiliano orogenic cycle.
The pregnant teenager is considered at nutritional risk specially due to the fact that most of them still growing and developing. Therefore the demands of pregnancy compete with those of growth ...causing an extra need for her and the fetus (1). Iron, zinc and folate are essential nutrients that are frequently low on the teenagers diet. Besides that there is not much specific information available about these nutrient recommendations and their interaction among each other. The data available is limited and demands more investigation. This study was conducted at a Public Maternity Hospital located at Teresina, Piauf, Brazil. The main objective of this study was to investigate the effect of different concentrations of iron supplementation (80 and 120 mg of ferrous sulfate) together with folate (250 micrograms) and zinc (5 mg) on the hemoglobin concentration and iron stores (plasma ferritin) of pregnant adolescents. The supplementation was done from the 16th to 20th weeks of gestation until delivery. The data founded proved that either 80 mg or 120 mg of iron supplements had similar effect on the improvement of hemoglobin concentration although results showed no statistical significance.
Thesis (M.A.)--Boston University
In this paper, several numerical methods, instructive for the calculation of the approximate solutions of differential equations, are exhibited to be convergent. In ...the first two methods (Picard's Method and the Cauchy-Euler method), the theoretical importance of numerical solutions is demonstrated by establishing existence and uniqueness theorems for the linear differential equation of the first order dy/dx = f(x,y) subject to the following conditions: The equation is considered in some region of xy space containing a point (xo,yo) and in addition to being continuous, f(x,y) is assumed to satisfy a Lipschitz condition with respect to y, i.e. |f(x,y1)-f(x,y2)| < k|y1 - y2| where k is called the Lipschitz constant TRUNCATED
The aim of this study was to determine the effect of cottonseed hull (CH) in the diets of rams on intake, digestibility, nitrogen balance, ingestive behaviour, and blood metabolites. Twenty males, ...uncastrated with an average body weight of 29.08 ± 4.18 kg, were distributed in a completely randomized design with four treatment diets and five replicates. The diet contained a forage to concentrate ratio of 50 : 50 (ground corn, soybean meal, corn silage, and CH), and the experimental treatments were inclusion of 0, 10, 20, and 30% CH (dry matter basis). Inclusion of CH linearly increased water intake, effective intake of ethereal extract and non-fibrous carbohydrates, and crude protein digestibility. Dry matter (DM) and neutral detergent fiber (NDF) digestibility, nitrogen faecal losses, and nitrogen balance reduced linearly with CH inclusion in the diet. Inclusion of CH in rams' diet reduces intake, nutrient digestibility, and intake and rumination efficiencies. Thus, it is not recommended to add this by-product to the diet of high-performance rams, but for nurture that does not aim at high performance, inclusion of up to 5% of this by-product is recommended.
The copper/polymer interface has been studied by VUV photoemission for poly-3-hexylthiophene (P3HT) as a model of conjugated polymers, at low metal coverage.
