Extra-long and taper-free germanium nanowires: use of an alternative Ge precursor for longer nanostructures.

One of the challenges in the development of germanium nanowires (Ge NWs) is to increase their length beyond the 10 µm limit without enlarging the NW diameter, i.e. minimizing the tapering. Here we report how it is possible to overcome this hurdle by using isobutyl germane (iBuGe) as a metal organic precursor during MOCVD growth, instead of the commonly used germane. We have grown and characterized by transmission electron microscopy, scanning electron microscopy and Raman various samples and we have analyzed the effect of growth time, precursor flux and growth temperature on the NW length. The use of iBuGe coupled to optimized growth conditions permitted to obtain Ge NWs with lengths up to 30 µm with minimal tapering. To explain why a new precursor has this impact on the morphology of the NWs we consider two possible causes: (i) the role of carbon radicals produced by isobutyl decomposition and (ii) the reduced growth rate of Ge on the sidewalls. On the basis of Raman characterization and temperature-dependence of tapering, we conclude that the reduced tapering is probably due to lower growth rates on the sidewalls.

Built-in tensile strain dependence on the lateral size of monolayer MoS2 synthesized by liquid precursor chemical vapor deposition.

Strain engineering is an efficient tool to tune and tailor the electrical and optical properties of 2D materials. The built-in strain can be tuned during the synthesis process of a two-dimensional semiconductor, such as molybdenum disulfide, by employing different growth substrates with peculiar thermal properties. In this work, we demonstrate that the built-in strain of MoS2 monolayers, grown on a SiO2/Si substrate by liquid precursor chemical vapor deposition, is mainly dependent on the size of the monolayer. In fact, we identify a critical size equal to 20 µm, from which the built-in strain increases drastically. The built-in strain is the maximum for a 60 µm sized monolayer, leading to 1.2% tensile strain with a partial release of strain close to the monolayer triangular vertexes due to the formation of nanocracks. These findings also imply that the standard method for evaluation of the number of layers based on the Raman mode separation can become unreliable for highly strained monolayers with a lateral size above 20 µm.

Air pollution and related respiratory diseases: the experience of a local health authority in Liguria (north Italy).

BACKGROUND: Numerous epidemiological studies have shown that air pollution due to both industry and heavy traffic has short- and long-term effects on health. The study was carried out in an industrial area with heavy urban and motorway traffic in the Province of Genoa (Italy). METHODS: The study was carried out from June 2005 to July 2008. An epidemiologic study was conducted by monitoring an elementary/middle school situated in an area of recent industrial development and an elementary/middle school located in an area free from sources of industrial pollution. Furthermore, we conducted an investigation of workers in commercial premises situated in one area of heavy vehicular traffic. In the study areas, environmental monitoring campaigns were carried out in order to determine the association between indoor and outdoor pollution and respiratory disorders. RESULTS AND DISCUSSION: The study did not bring to light any specific health problems attributable with certainty to industrial emissions. The impact of pollution caused by motor traffic proved to be greater than that due to industrial emissions. More exhaustive sampling campaigns should be implemented in order to quantify the effects of specific sources of emissions and to correlate these sources with pollutants (industry, urban traffic, motorway traffic).

Gold nanoparticle assisted synthesis of MoS2 monolayers by chemical vapor deposition.

The use of metal nanoparticles is an established paradigm for the synthesis of semiconducting one-dimensional nanostructures. In this work we study their effect on the synthesis of two-dimensional semiconducting materials, by using gold nanoparticles for chemical vapor deposition growth of two-dimensional molybdenum disulfide (MoS2). In comparison with the standard method, the employment of gold nanoparticles allows us to obtain large monolayer MoS2 flakes, up to 20 µm in lateral size, even if they are affected by the localized overgrowth of MoS2 bilayer and trilayer islands. Important modifications of the optical and electronic properties of MoS2 triangular domains are reported, where the photoluminescence intensity of the A exciton is strongly quenched and a shift to a positive threshold voltage in back-gated field effect transistors is observed. These results indicate that the use of gold nanoparticles influences the flake growth and properties, indicating a method for possible localized synthesis of two-dimensional materials, improving the lateral size of monolayers and modifying their properties.

Influence of organic promoter gradient on the MoS2 growth dynamics.

Chemical vapor deposition has been demonstrated to be the most efficient, versatile and reliable technique for the synthesis of monolayers of transition metal dichalcogenides. The use of organic promoters during the growth process was a turning point in order to increase the monolayer lateral size or to obtain complete coverage of the growth substrate. In this work we clarify the influence of the promoter gradient on the growth dynamics of MoS2. In particular, we place a sacrificial substrate covered with a promoter (a low sublimation-temperature perylene-based compound) downstream with respect to the growth substrate in order to maximize its gradient on the growth substrate through upstream diffusion. We demonstrate that the morphology and the number of layers of MoS2 are drastically affected by the distance of the growth substrate from the promoter sacrificial substrate. The farthermost area from the promoter substrate presents micrometric MoS2 triangular monolayers and large low hierarchy dendritic multi-layer structures. On the contrary the closest area reveals an almost continuous polycrystalline MoS2 monolayer, with bilayer terraces, with a lateral dimension up to hundreds of micrometers.

Polymorphic MAO-A and 5-HT-transporter genes: analysis of interactions in panic disorder.

Recurrent panic attacks, anticipatory anxiety and phobic avoidance characterise panic disorder. The influence of genetic factors on liability to the disease has been the object of several linkage and association studies and appears to relate to an oligo- or polygenic rather than a monogenic mode of inheritance. Recently, an excess of high activity monoamine oxidase A (MAO-A) gene promoter alleles was found in female patients with panic disorder. An analysis of possible synergistic effects of the MAO-A gene promoter variant and the short serotonin transporter (5-HTT) gene promoter variant in panic disorder was performed in a German and an Italian sample (combined panic disorder n = 144, combined controls n = 175). There was no significant difference in odds ratios, suggesting that the observed increase of genetic liability by the long MAO-A gene promoter allele is not modified by the 5-HTT gene promoter polymorphism.

[Citizenship, community participation, and health as seen by health care professionals: a case study in public health services]. / Cidadania, participação popular e saúde na visão dos profissionais do setor: um estudo de caso na rede pública de serviços.

This paper deals with the subject of citizenship and people's participation in the health area through an analysis of ideas pertaining to a specific group: health care professionals working in Basic Health Care Clinics in the 3.1 Programmatic Area of the City of Rio de Janeiro (Brazil). The article analyzes their views on the subject and presents them in light of health-related legislation in the Brazilian constitution. It also analyzes the professionals' role vis-à-vis users in raising community awareness that health care is one of their basic rights. Field data from qualitative social research methodology showed a significant heterogeneity in the professionals' conceptions, dividing them into two groups: those belonging to teaching institutions and those working in institutions providing health care. This analysis shows the strategic role that day-to-day relationships between professionals and the community can play in the social change process and the establishment of social rights. It also discusses the viability of this process in view of the discovery of the subjective involvement of the health professionals who promote this process.

Hypokalemic thyrotoxic paralysis: a rare cause of tetraparesis with acute onset in Europeans.

We describe a 21-year-old Italian male affected by hypokalemic tetraparesis with acute onset. In the emergency ward, the patient was agitated, with tachycardia (140/min) and systolic hypertension (180/70 mm Hg). He was not able to flex the lower extremities against a light resistance and furthermore, he was hypotonic and without tendon reflexes. One hour later he developed strength deficit of the upper extremities as well. Biochemical analyses revealed severe hypopotassemia (2.1 meg/l). After administration of 140 meq potassium phosphate, the patient began to improve, and 12 h after the onset he was able to walk normally. Successive investigations documented an undiagnosed case of Graves' disease. Thyrotoxic hypokalemic paralysis has been observed almost only in Asians, however, with this case and others reported, we believe that it should be considered as a cause of muscular paralysis also in Caucasians.

Ocular abnormalities occurring with alopecia areata.

This study was carried out on 83 patients with alopecia areata. Ophthalmological examinations showed lens changes in 65 patients and alterations in the retinal epithelium in 28 patients. The relationships between pigment cells and hair cycle are discussed.

[Immunoscintigraphy in the diagnosis of choroid melanoma]. / L'immunoscintigrafia nella diagnosi dei melanomi della coroide.

This study was aimed at evaluating the role of 99mTc-labelled anti-melanoma antibodies as in vivo tumor markers in the diagnosis of uveal melanomas. Usually, neither conventional semeiological techniques nor more recent diagnostic imaging methods allow a differential diagnosis to be made of benign and malignant intra-ocular tumors. Immunoscintigraphy was employed to examine 9 patients with monolateral reduction of sight, and photopsy. All patients were previously submitted to funduscopy, fluorescein angiography, and US. Four hours after iv injection of 370 MBq of 99mTc F(ab1)2, we obtained 500,000-count images of skull, abdomen, and thorax, with a computerized gamma camera equipped with a general-purpose collimator. A SPET of the head followed the conventional examination. Our first results seem promising enough for further study to be carried out to assess immunoscintigraphy specificity in the diagnosis of uveal melanoma.

Excess of high activity monoamine oxidase A gene promoter alleles in female patients with panic disorder.

A genetic contribution to the pathogenesis of panic disorder has been demonstrated by clinical genetic studies. Molecular genetic studies have focused on candidate genes suggested by the molecular mechanisms implied in the action of drugs utilized for therapy or in challenge tests. One class of drugs effective in the treatment of panic disorder is represented by monoamine oxidase A inhibitors. Therefore, the monoamine oxidase A gene on chromosome X is a prime candidate gene. In the present study we investigated a novel repeat polymorphism in the promoter of the monoamine oxidase A gene for association with panic disorder in two independent samples (German sample, n = 80; Italian sample, n = 129). Two alleles (3 and 4 repeats) were most common and constituted >97% of the observed alleles. Functional characterization in a luciferase assay demonstrated that the longer alleles (3a, 4 and 5) were more active than allele 3. Among females of both the German and the Italian samples of panic disorder patients (combined, n = 209) the longer alleles (3a, 4 and 5) were significantly more frequent than among females of the corresponding control samples (combined, n = 190, chi2 = 10.27, df = 1, P = 0.001). Together with the observation that inhibition of monoamine oxidase A is clinically effective in the treatment of panic disorder these findings suggest that increased monoamine oxidase A activity is a risk factor for panic disorder in female patients.

La enseñanza de la investigación cualitativa en salud: voces desde Iberoamérica / Teaching qualitative health research: voices from Iberoamerica

La investigación cualitativa se difunde en el área de la salud en Iberoamérica en las últimas décadas. Numerosos programas de enseñanza y capacitación se han organizado en la región; pero son inexistentes los trabajos cuyo objetivo sea evaluar los avances y dificultades en su enseñanza. Este artículo presenta el diálogo de cinco académicos iberoamericanos sobre la enseñanza de la investigación cualitativa en salud. La reflexión gira en torno a cuatro temas: su acercamiento al campo y a su enseñanza; las fortalezas,logros de las iniciativas educativas en que han participado; las dificultades y obstáculos enfrentados, y los retos y prioridades de su enseñanza en el futuro. Los académicos participantes fueron elegidos por su experiencia en el tema y por su procedencia geográfica. El diálogo se estableció vía Internet, empleando una variante del método FODA y la técnica Delphi.Los participantes, separados geográficamente, con diferentes trayectorias profesionales y antecedentes académicos, exponen los motivos por los cuales esta forma de investigación ha tenido éxito: el entusiasmo de la gente joven y las mujeres, el interés creciente, el rigor académico, la interdisciplinariedad y la legitimación que ha ganado como forma válida de hacer ciencia. Entre los problemas y dificultades destacan la poca consolidación y madurez de las propuestas educativas, y un medio que poco le favorece. Los mismos plantean impulsar su enseñanza en diálogo con la orientación cuantitativa, formulan propuestas al interior de los programas educativos y haciendo uso de tecnologías. Sugieren tomar en cuenta las particularidades sociales para la enseñanza de este campo...