O efeito “dominó” na Interacção Homem-Computador

A colaboração multidisciplinar é essencial para uma interacção homem-computador (IHC) efectiva. Historicamente a ciência dos computadores, a psicologia e as ciências sociais actuavam como disciplinas independentes, mas com o aumento da frequência na utilização das tecnologias da informação e comunicação em vários aspectos do dia-a-dia, a funcionalidade e acessibilidade assumiram uma importância cada vez maior. Neste artigo é apresentada uma reflexão sobre a multidisciplinaridade e transversalidade da IHC em termos tecnológicos e tendências futuras

Influence of the synthetic procedure on the properties of three Ziegler-Natta catalysts with the same 1,3-diether internal donor

Being the main responsible for the huge production of polyolefins, heterogeneous Ziegler-Natta catalysts are among the most important catalysts in the chemical industry and they have been optimized over the years since their discovery in 1953 crossing many different generations. Lastly, catalysts of the 5th generation are characterized by the introduction in the pre-catalyst of 1,3-diether compounds as internal electron donors, which are stable in the presence of AlR3 activators and do not require the further addition of external donors during the following steps of the catalytic process to control the activity and selectivity. In this work, we synthetized and systematically investigated by a multi-technique approach three Ziegler-Natta catalysts characterized by the same 1,3-diether donor, but differing in the synthesis route. We found that the synthetic route influences the MgCl2 particle size, as well as the properties of the Ti species. In particular, the reprecipitation method brings the smallest MgCl2 particles and the most positive Ti4+ sites in the pre-catalyst, but also the largest amount of accessible Ti3+ sites after TEAl activation. These structural and spectroscopic data correlate pretty well with the kinetic of gas-phase propylene polymerization in very mild conditions

Foramen caróticoclinoideo en cráneos humanos: incidencia, morfometría y sus implicaciones clínicas

The caroticoclinoid foramen is an inconstant structure, formed by the union of the anterior and middle clinoid processes. The aim of this study was to perform an incidence and morphometry of the caroticoclinoid foramen in Brazilian human skulls and discuss its clinical implications. Eighty dry human skulls with sex distinction were used, and 3 groups of incidence were determined: General, sex, and sides. The morphometry was performed using a manual caliper and the major diameter of the foramina was measured; the values were also divided in general, according to sex and sides. The incidence of skulls with at least one foramen was 8.5%. According to the sides, 8.5% of the skulls showed foramen on the right side and 2.5% on the left. We found 2.5% of the skulls with bilateral foramen and 6.25% with unilateral foramen. In relation to sex, the foramens were found in 5% of male skulls and 12.5% of female skulls. The major diameter of this structure presented on mean, values of 5.23 mm on general, 5.18 mm on the right side and 5.35 mm on the left, 5.30 mm in male skulls and 5.18 mm in female skulls. The anatomical characteristics of this foramen should be considered in view of its clinical implications associated with neurosurgery as clinoid process removal, and symptoms as headache due to internal carotid artery alterations in this region. In conclusion knowledge of this structure supports the diagnosis and treatment of clinical complications related to this variation.The caroticoclinoid foramen is an inconstant structure, formed by the union of the anterior and middle clinoid processes. The aim of this study was to perform an incidence and morphometry of the caroticoclinoid foramen in Brazilian human skulls and discuss its clinical implications. Eighty dry human skulls with sex distinction were used, and 3 groups of incidence were determined: General, sex, and sides. The morphometry was performed using a manual caliper and the major diameter of the foramina was measured; the values were also divided in general, according to sex and sides. The incidence of skulls with at least one foramen was 8.5%. According to the sides, 8.5% of the skulls showed foramen on the right side and 2.5% on the left. We found 2.5% of the skulls with bilateral foramen and 6.25% with unilateral foramen. In relation to sex, the foramens were found in 5% of male skulls and 12.5% of female skulls. The major diameter of this structure presented on mean, values of 5.23 mm on general, 5.18 mm on the right side and 5.35 mm on the left, 5.30 mm in male skulls and 5.18 mm in female skulls. The anatomical characteristics of this foramen should be considered in view of its clinical implications associated with neurosurgery as clinoid process removal, and symptoms as headache due to internal carotid artery alterations in this region. In conclusion knowledge of this structure supports the diagnosis and treatment of clinical complications related to this variation292427431Das, S., Suri, R., Kapur, V., Ossification of caroticoclinoid ligament and its clinical importance in skull-based surgery (2007) São Paulo Med. J, 125, pp. 351-353Dodo, Y., Ishida, H., Incidence of nonmetric cranial variant in several population samples from East Asia and North America (1987) J. Anthrop. Soc. Nippon, 95, pp. 161-167Dolenc, V.V., A combined epi and subdural direct approach to carotidophthalmic artery aneurysms (1985) J. Neurosurg, 5, pp. 667-672Donald, P.J., (1998) Surgery of the Skull Base, , Philadelphia, Lippincott- RavenErturk, M., Kayalioglu, G., Govsa, F., Anatomy of the clinoidal region with special emphasis on the caroticoclinoid foramen and interclinoid osseous brid- ge in a recent Turkish population (2004) Neurosurg. Rev, pp. 22-26Gupta, N., Ray, B., Ghosh, S., A study on anterior clinoid process and optic strut with emphasis on variations of caroticoclinoid foramen (2005) Nep. Med. Coll. J, 7, pp. 140-144Hochstetter, F., Über die Taenia interclinoidea,die Commissura alicochlearis und die Cartilago supracochlearis des menschlichen Primordialkraniums.Gegenbaurs Morph (1940) Jahrb, 84, pp. 220-243Inoue, T., Rhoton Jr., A.L., Theele, D., Barry, M.E., Surgical approaches to the cavernous sinus:A microsurgical study (1990) Neurosurg, 6, pp. 903-932Kier, E.L., Embryology of the normal optic canal and its anomalies.An anatomic and roentgenographic stud (1966) Invest. Radiol, 1, pp. 346-362Kobayashi, S., Kyoshima, K., Gibo, H., Hedge, S.A., Takemae, T., Sugita, K., Carotid cave aneurysms of the internal carotid artery (1989) J. Neurosurg, 70, p. 216Lee, H.Y., Chung, I.H., Choi B., Y., Anterior, C., (1997) Yonsei Med. J, 38, pp. 151-154Narolewski, R., Significance of anatomic variants of bony surroundings of the internal carotid artery and their significance for lateral surgical approaches to the cavernous sinus (2003) Ann. Acad. Med. Stetin, 49, pp. 205-229Saka, E., Ozdoǧmus, O., Tulay, C., Gürdal, E., Uzün, I., The anatomy of the carotico-clinoid foramen and its relation with the internal carotid artery (2003) Surg. Radiol. Anat, 25, pp. 241-246Reisch, R., Vutskits, L., Filippi, R., Patonay, L., Fries, G., Perneczky, A., Topographic microsurgical anatomy of the paraclinoid carotid artery (2002) Neurosurg Rev, 25, pp. 177-183Sekhar, L.N., Akin, O., Anatomical study of the cavernous sinus emphasizing operative approaches and related vascular and neural reconstruction (1987) Neurosurg, 21, pp. 806-816Seoane, E., Rhoton, A.L., Oliveira, E., Microsurgical anatomy of the dural collar (carotid collar) and rings around the clinoid segment of the internal carotid artery (1998) Neurosurg, 42, pp. 869-886Sicher, H., du Brul, E.L., (1977) Oral Anatomy, , 6ed. Rio de Janeiro, Guanabara KooganStandring, S., Overview of the Development of the Head and Neck Head: Skull and Mandible Gray's anatomy: The anatomical basis of clinical practice, p. 2005. , New York, ElsevierEl foramen caróticoclinoideo es una estructura inconstante formada por la unión de la procesos clinoides anterior y medio. El objetivo de este estudio fue revisar la incidencia y la morfometría del foramen caróticoclinoideo en cráneos humanos brasileños y discutir sus implicaciones clínicas. Se utilizaron 80 cráneos humanos secos, de ambos sexos, determinando tres variables: sexo y lados derecho e izquierdo. La morfometría se realizó con un cáliper manual midiéndose el diámetro máximo del foramen. La incidencia de cráneos con al menos un foramen fue de 8,5%. El 8,5% de los cráneos presentó un foramen en el lado derecho y el 2,5% en el izquierdo. El 2,5% de los cráneos presentó un foramen bilateral y el 6,25% un foramen unilateral. En relación al sexo, los forámenes se encontraron en el 5% de los cráneos de hombres y el 12,5% de los cráneos de mujeres. El diámetro máximo de esta estructura presentó en promedio, valores de 5,23 mm; 5,18 mm en el lado derecho y 5,35 mm en el izquierdo; 5,30 mm en cráneos de hombres y 5.18 mm en cráneos de mujeres. Las características anatómicas de este foramen deben ser consideradas debido a las implicaciones clínicas asociadas a la neurocirugía, como la eliminación del proceso clinoides y a síntomas como cefaleas producto de alteraciones en la arteria carótida interna en esta región. En conclusión, el conocimiento de esta estructura mejora el diagnóstico y tratamiento de las complicaciones clínicas relacionadas con esta variació

Estimating soil carbon content using easily obtainable parameters.

Introduction Among the many strategies adopted to mitigate climate change is the reduction of atmospheric carbon in a process called carbon sequestration, which consists of the transfer of carbon dioxide from the atmosphere to other global pools, such as the soil [1]. Therefore, quantifying the soil carbon is of great importance for successfully measuring the efficiency of carbon sequestration practices and providing accurate reports [2]. The correct measurement of soil carbon is a costly and cumbersome process requiring shipping of samples from the field to laboratories, greatly limiting its applicability [3]. In order to reduce the cost and time required for analyses, several techniques have been developed, such as laser-induced breakdown spectroscopy [4] and online visible and near-infrared spectroscopy with random forests [5]. Even though these new techniques are faster and less expensive, samples still are required to be collected in the field. Developing a method that could provide estimates of the carbon content of farms, using easily obtained variables such as soil texture and practices, would contribute to understanding the relationship between these variables and soil carbon, facilitating carbon sequestration initiatives [6]. Thus, the aim of this project was to train a model on the data available and verify its validity

Electronic Properties of Ti Sites in Ziegler-Natta Catalysts

Although Ziegler-Natta (ZN) catalysts play a major role in the polyolefin market, a true understanding of their properties at the molecular level is still missing. In particular, there is a lack of knowledge on the electronic properties of Ti sites. Theoretical calculations predict that the electron density of the Ti sites in the precatalysts correlates with the activation energy for olefin insertion in the Ti-alkyl bond generated at these sites after activation by Al-alkyls. It is also well known that the effective charge on the Ti sites in the activated catalysts affects the olefin π-complexation. In this contribution, we exploit two electronic spectroscopies, UV-vis and Ti L2,3-edge near-edge X-ray absorption fine structure (NEXAFS), complemented with theoretical simulation to investigate three ZN precatalysts of increasing complexity (up to an industrial system) and the corresponding catalysts activated by triethylaluminum (TEAl). We provide compelling evidence for the presence of monomeric 6-fold-coordinated Ti4+ species in all of the precatalysts, which however differ in the effective charge on the Ti sites. We also unambiguously demonstrate that these sites are reduced by TEAl to two types of monomeric 5-coordinated Ti3+, either alkylated or not, and that the former are involved in ethylene polymerization. In addition, small TiCl3 clusters are formed in the industrial catalyst, likely due to the occurrence of severe reducing conditions within the catalyst pores. These data prove the potential of these two techniques, coupled with simulation, in providing an accurate description of the electronic properties of heterogeneous ZN catalysts