Large magnetic gap at the Dirac point in Bi2Te3/MnBi2Te4 heterostructures.

Magnetically doped topological insulators enable the quantum anomalous Hall effect (QAHE), which provides quantized edge states for lossless charge-transport applications1-8. The edge states are hosted by a magnetic energy gap at the Dirac point2, but hitherto all attempts to observe this gap directly have been unsuccessful. Observing the gap is considered to be essential to overcoming the limitations of the QAHE, which so far occurs only at temperatures that are one to two orders of magnitude below the ferromagnetic Curie temperature, TC (ref. 8). Here we use low-temperature photoelectron spectroscopy to unambiguously reveal the magnetic gap of Mn-doped Bi2Te3, which displays ferromagnetic out-of-plane spin texture and opens up only below TC. Surprisingly, our analysis reveals large gap sizes at 1 kelvin of up to 90 millielectronvolts, which is five times larger than theoretically predicted9. Using multiscale analysis we show that this enhancement is due to a remarkable structure modification induced by Mn doping: instead of a disordered impurity system, a self-organized alternating sequence of MnBi2Te4 septuple and Bi2Te3 quintuple layers is formed. This enhances the wavefunction overlap and size of the magnetic gap10. Mn-doped Bi2Se3 (ref. 11) and Mn-doped Sb2Te3 form similar heterostructures, but for Bi2Se3 only a nonmagnetic gap is formed and the magnetization is in the surface plane. This is explained by the smaller spin-orbit interaction by comparison with Mn-doped Bi2Te3. Our findings provide insights that will be crucial in pushing lossless transport in topological insulators towards room-temperature applications.

Response surface methodology and Taguchi approach to assess the combined effect of formulation factors on minocycline delivery from collagen sponges.

An important aspect to be considered in the healing of acute or chronic cutaneous wounds is the associated potential infection management. Collagen, the most abundant protein of the extracellular matrix, with proven properties in wounds healing and tissues regeneration, is one of the most widely used biopolymers as carrier matrix for controlled drug delivery systems. For this reason, the purpose of the current paper is the development of some minocycline-loaded collagen topical sponges uncross-linked and cross-linked with glutaraldehyde, obtained by lyophilization of appropriate hydrogels prepared according to the 3-factor, 3-level face-centered central composite design. The determination of drug delivery from the sponges was performed by assessment of some physicochemical parameters involved in this complex process: sponges surface wettability, swelling ratio and the percentage of minocycline released from the sponges. The application of the response surface methodology allowed the setting of the formulation parameters optimum ranges, which ensure an adequate minocycline release to the application site. The design robustness was checked using the signal-to-noise ratio performance indicator. The optimum collagen-minocycline sponges determined based on the statistical screening technique could be suitable for topical drug delivery in infected wounds healing with moderate to high exudate.

The value of serum bilirubin level and of white blood cell count as severity markers for acute appendicitis.

Discussions regarding the correlations between elevated white blood cell levels and clinical and pathological stages of acute appendicitis are well known. Recent studies show that a high level of serum bilirubin could emerge as a prognostic marker for gangrenous or perforated stages of acute appendicitis. We studied the correlations between anatomical and pathological stages of acute appendicitis and white blood cell count, serum total bilirubin, and indirect serum bilirubin on a large series of cases, in the course of one year, in our department. Although there being a correlation between severe forms of acute appendicitis (gangrenous, perforated), elevated white blood cell count, elevated serum bilirubin (mostly the indirect fraction), none of the indicators proved to have a definitive diagnostic value. Cases with perforation and localized generalized peritonitis are more frequently associated with elevated bilirubin levels.

Magnetically interacting low dimensional Ni-nanostructures within porous silicon.

Electrodeposition of ferromagnetic metals, a common method to fabricate magnetic nanostructures, is used for the incorporation of Ni structures into the pores of porous silicon templates. The porous silicon is fabricated in various morphologies with average pore-diameters between 40 and 95 nm and concomitant pore-distances between 60 and 40 nm. The metal nanostructures are deposited with different geometries as spheres, ellipsoids or wires influenced by the deposition process parameters. Furthermore small Ni-particles with diameters between 3 and 6 nm can be deposited on the walls of the porous silicon template forming a metal tube. Analysis of this tube-like arrangement by transmission electron microscopy (TEM) shows that the distribution of the Ni-particles is quite narrow, which means that the distance between the particles is smaller than 10 nm. Such a close arrangement of the Ni-particles assures magnetic interactions between them. Due to their size these small Ni-particles are superparamagnetic but dipolar coupling between them results in a ferromagnetic behavior of the whole system. Thus a semiconducting/ferromagnetic hybrid material with a broad range of magnetic properties can be fabricated. Furthermore this composite is an interesting candidate for silicon based applications and the compatibility with today's process technology.

Design and optimization of some collagen-minocycline based hydrogels potentially applicable for the treatment of cutaneous wound infections.

Topical delivery systems for the treatment of different infected cutaneous wounds based on natural biopolymers are widely studied. The development of some topical hydrogels with type I collagen and minocycline by the experimental design technique, based on response surface methodology and Taguchi's approach, and the evaluation of their kinetic properties is presented. The concentrations of polymer, drug and cross-linking agent were selected as independent variables for the face centered composite design and low, medium and high concentration as variation levels for each factor. Minocycline kinetic release was investigated using a modified Franz diffusion cell. The drug release followed the Higuchi model. Three formulations having optimal minocycline release profiles were selected. They can be used as potential drug topical release systems for the treatment of infected cutaneous tissue.

Mechanical behavior of in-situ alloyed Ti6Al4V(ELI)-3 at.% Cu lattice structures manufactured by laser powder bed fusion and designed for implant applications.

In the present study, cellular lattice structures for implant applications are reported for the first-time incorporating copper directly by in-situ alloying in the laser powder bed fusion process. The aim to incorporate 3 at.% Cu into Ti6Al4V(ELI) is selected for improved antibacterial properties while maintaining appropriate mechanical properties. Previously, topologically optimized Ti6Al4V(ELI) lattice structures were successfully designed, manufactured and studied for implant applications. The development of a new alloy produced by in-situ alloying of elemental powder mixture of Ti6Al4V(ELI) and pure Cu powders was used here for the production of identical lattice structures with improved antibacterial properties. One of the same as-designed CAD models was used for the manufacturing of these lattices compared to previous work on pure Ti6Al4V(ELI) lattices, making direct comparison of mechanical properties possible. Similar manufacturability highlights the applicability of this alloying technique to other lattice designs. Microstructural characterization was performed by optical and electron microscopies, as well as microCT. Mechanical characterization was performed by means of compression tests and hardness measurements. Results showed that in-situ alloying with copper leads to the formation of localized Cu-rich regions, refinement of martensitic phase and the formation of CuTi2 intermetallic precipitates, which increased the hardness and strength of the material. Deviations in wall thickness between the as-designed and as-manufactured lattices led to anisotropy of the mechanical properties of the lattices. Higher compressive strength values were obtained when thicker walls were oriented along the loading direction. Nevertheless, alloying with Cu had a higher impact on the compressive strength of lattice structure than the wall thickness deviations. The direct in-situ alloying of copper in Ti6Al4V(ELI) is a promising route for direct manufacturing of antibacterial implants.

Self-organized Sr leads to solid state twinning in nano-scaled eutectic Si phase.

A new mechanism for twin nucleation in the eutectic Al-Si alloy with trace Sr impurities is proposed. Observations made by sub-angstrom resolution scanning transmission electron microscopy and X-ray probing proved the presence of <110> Sr columns located preferentially at twin boundaries. Density functional theory simulations indicate that Sr atoms bind in the Si lattice only along the <110> direction, with preferential positions at first and second nearest neighbors for interstitial and substitutional Sr, respectively. Density functional theory total energy calculations confirm that twin nucleation at Sr columns is energetically favorable. Hence, twins may nucleate in Si precipitates after solidification, which provides a different perspective to the currently accepted mechanism which suggests twin formation during precipitate growth.

A quantitative analysis of a multi-phase polycrystalline cubic boron nitride tool material using DualEELS.

This paper presents a quantitative analysis of a polycrystalline cubic boron nitride tool material by electron energy-loss spectroscopy spectrum imaging acquired in dual range mode. Having both the low-loss and core-loss regions acquired nearly simultaneously provides the advantage of accurate corrections for thickness effects and thus the possibility to perform quantification calculations. This has resulted in extracted bonding maps with areal (atoms/nm(2)) or volumetric (atoms/nm(3)) densities. Spectroscopic signatures in the low-loss and core-loss energy ranges, of the elements (Al, B, C, N, Ti and O) present in the existing phases, were studied and used when extracting the element specific bonding maps by the multiple linear least squares fitting procedure. Variations of elemental concentrations across the investigated area were determined, despite of phase overlap in the beam direction or energy overlaps in the EELS spectrum. Moreover, the surface oxidation of Ti(C,N) and AlN as well as the amorphisation of α-Al(2)O(3) is discussed.

[Fruit consumption in a group of teenagers from Iasi]. / Consumul de fructe la un grup de adolescenti din municipiul Iasi.

UNLABELLED: A goal for the national nutritional education program is represented by the increase of fruit consumption. MATERIAL AND METHOD: Using specially designed questionaries a group of 127 teenagers from two different Iasi high schools provided date related to thei daily fruit intake. RESULTS: Almost 40% of the teenagers use fresh fruits as part of their breakfast and a greater number use them as snacks (57.5%) or dessert (80.5%), with statistically insignificant differences between the two high schools. CONCLUSION: The fruit intake is adequate in the studied group and the programs that promote certain food habits must take into account the existing situation.

Investigation of a Mesoporous Silicon Based Ferromagnetic Nanocomposite.

A semiconductor/metal nanocomposite is composed of a porosified silicon wafer and embedded ferromagnetic nanostructures. The obtained hybrid system possesses the electronic properties of silicon together with the magnetic properties of the incorporated ferromagnetic metal. On the one hand, a transition metal is electrochemically deposited from a metal salt solution into the nanostructured silicon skeleton, on the other hand magnetic particles of a few nanometres in size, fabricated in solution, are incorporated by immersion. The electrochemically deposited nanostructures can be tuned in size, shape and their spatial distribution by the process parameters, and thus specimens with desired ferromagnetic properties can be fabricated. Using magnetite nanoparticles for infiltration into porous silicon is of interest not only because of the magnetic properties of the composite material due to the possible modification of the ferromagnetic/superparamagnetic transition but also because of the biocompatibility of the system caused by the low toxicity of both materials. Thus, it is a promising candidate for biomedical applications as drug delivery or biomedical targeting.

[Specifics of food intake by schoolchildren in the rural areas of Moldova]. / Particularitatile alimentatiei elevilor din mediul rural în zona Moldovei.

149 schoolchildren, 14-15 years old, from 4 rural communities pending on 4 different Moldova counties have been investigated using the one day questionnaire technique. From the entire studied group, only 7.4% are do not eat breakfast before attending school. 35.5% of the schoolchildren consider their sugar intake to be excessive, without taking into account the sugar major role in nervous cell function. The average daily intake for fresh fruits, vegetables and milk is in most cases adequate, but significant differences are present between the communities, related with the socio-economic status of the families and, also, with nutritional.

[Professional guidance problems in spastic hemiparesis school children]. / Probleme ale orientarii profesionale la elevii cu hemipareza spastica.

People with physical handicap adapt themselves with more difficulties to professions that require manual abilities. For these youngsters, the professional guidance plays a major role. Their desire is to become independent from the social point of view, independent which is linked with a professional activity. If the youngsters with physical handicaps are correctly orientated, they become socially independent and they perform their professional duties with great correctness. In order to fulfill this goal we must understand the nature of the motric problems. This knowledge is obtained by using a series of tests that allows us to evaluate the degree of motric handicap. The physical difficiency, followed by the integration in a special school, may result in personality problems. Briefly, the motric handicap problem must be discussed in a complex, following medical aspects but also professional, psychic and social aspects.

[Effect of environmental factors on high school children's health ]. / Evaluarea actiunii unor factori de mediu asupra sanatatii elevilor din ultimele clase de liceu.

We studied 78 teenagers from Iasi Pedagogic High School. Body mass index values are mainly (83.3%) normal. 60.3% of the teenagers are coming from rural areas, but there are no significant differences between children coming from urban and rural areas. The frequency of families with more than 5 children in the urban areas is very small (1.3%), but in the rural areas this frequency is more than 10 times higher (15.4%). Due to this factor, the per capita income is reduced in the rural areas. Nutrition is a major problem in both urban and rural areas, due to unbalances food intake.

Effects of thymectomy on blood neutrophils phagocytic activity and phagocytic response in mice.

The role of the thymus in maintenance of the basal phagocytosis of blood neutrophils and eliciting the phagocytic response, induced by i.v. Escherichia coli, was studied in 9 NMRI thymectomized and in 12 control mice. Thymectomy depresses the percentage of phagocyting neutrophils from 70.91 +/- 0.9 (mean +/- SEM) in controls, to 61.49 +/- 2.33 in the thymectomized rats. Phagocytic activity, as assessed by the number of bacteria engulfed by 100 neutrophils, was also lower in thymectomized mice (114.42 +/- 7.52) than in controls (163.71 +/- 4.53). A phagocytic response to i.v. Escherichia coli could nevertheless be noted in thymectomized mice, their phagocytic activity rising from the basal activity of 114.42 +/- 7.52 to 142.19 +/- 5.40 three hours after injection of Escherichia coli, while in control animals this activity rose from 163.71 +/- 4.53 to 216.46 +/- 12.91. These results may, at least partially, explain the recurrent infections and the septicemia occurring in children with Down's syndrome. It is suggested that the thymus, as an endocrine organ, may be involved in maintaining the basal phagocytic activity of blood neutrophils, while the phagocytic response is modulated by extrathymic mechanisms.

[Assessment of food intake in rural area school children]. / Aprecierea alimentatiei elevilor din mediul rural.

Children food intake is influenced by family nutritional habits and economic status. According to the results of our survey, only 54.8% of the children have taken their breakfast, although all of them recognize the importance of this meal. 9.6% of the children are not using fresh fruits and vegetables in their diets, even if these are the main sources of vitamin C. Regarding the milk consumption, most of the children use this food item once (35.5%) or twice (19.4%) a day and only 16.1% occasionally. Although most of the children (93.5%) know that excessive salt intake represents a risk factor for their health, 87.1% have preferences for salted and spiced foods. Under the influence of advertising, certain changes in the nutritional habits have been noticed; instead of traditional snacks, children are more attracted to fast-food type snacks.

[Comparative evolution of the incidence of bronchopulmonary tuberculosis and bronchopulmonary cancer (data of the TB dispensary No. 1 in Galati)]. / Evolutia comparativa a incidentei prin tuberculoza bronhopulmonara si cancer bronhopulmonar (date ale dispensarului TBC nr. 1 Galati).

Over a period of 10 years a decrease was noted in the area of the Tuberculosis Dispensary of the Galatzi District, of the incidence through tuberculosis of the adult by approximately 50%, and an increase of the pulmonary cancer incidence three fold. The incidence curves of these two diseases, which were far apart 10 years ago, are much nearer now, and it may be presumed that in a not too remote future they will cross each other. The pneumophysiology network should be prepared further to face the increasing flow of patients with non-tuberculous diseases. With this view physicians should be re-cycled, and various types of specialists should be trained for cytologic diagnosis, and the technical equipment of antituberculous hospitals should be updated.

Reticulin-M, an antianaphylactic peptide secreted by reticulo-endothelial system.

I. Moldovan (1923) demonstrated in the blood ultrafiltrate from anaphylactically prepared guinea pigs, which believed to anaphylactic shock, or which were previously injected with coloidal substances as India ink to stimulate the RES, an antianaphylactic principle named Reticulin-M(R). Authors extracted R from organs rich in RES with acetone, established their, peptidic nature and tested it on anaphylactic prepared guinea pig uterine horns in vitro. The peptides were fractioned by high voltage paper electrophoresis. The fractions were cut up in four groups, eluted and tested. The second basic group was identified as active and concentrated by acetone, recipitation. In conclusion several techniques were used to obtain, to test, to isolate and to concentrate R, a natural antianaphylactic peptidic factor, which may be a cytokine.

[The problems of self-image formation in children with motor deficiencies]. / Probleme legate de formarea imaginii de sine la copii cu deficiente motorii.

Self-image is a representation that each person has on its own body. The personality of an individual develops through progressive knowledge of its own body. Children with motor deficiencies have a modified self-image. For the evaluation of self-image a 1 to 10 self-assessment scale for three items (smart, resourceful, beautiful), and two time periods (now and in the future) was used. As to the dynamic components, the area "locus of control" showed significant positive differences between present and future situations (an increase from 22.1% to 56.5% for smart item, from 35.9% to 65.5% for resourceful item and only a small variation from 30.5% to 37.4% for handsome item, regarding the high marks self-assentiment).