Análise exploratória rápida e não destrutiva (screening) da presença de elementos químicos tóxicos em material escolar por fluorescência de raios x

Compulsory in Brazil, toy certification aims to prevent possible risks in toy use. The Brazilian National Institute of Metrology (INMETRO) establishes the maximum concentration of toxic elements (TE) that may be present in toys. This study evaluates the presence of TE in different crayons, gouache and modeling clays using X-ray fluorescence. This technique is fast, has low operating cost and minimum sample pretreatment, resulting in a clean procedure without reagent consumption and waste generation. Bromine (in gouache) and Barium (in crayons) were the only potentially TE identified in the samples studied.

Síntesis química, estudios de caracterización y reactividad de un material catalítico a base de ZrO2-H3PW12O40

In this work, the preparation and characterization of materials such as zirconium oxide (ZrO2) and phosphotungstic acid promoted zirconium oxide (ZrO2-H3PW12O40) is presented. Physico-chemical characterization results showed that addition of H3PW12O40 acted as both a textural and chemical promoter of zirconium oxide. The incorporation of phosphotungstic acid into the ZrO2 matrix delayed the sintering of the material and stabilized ZrO2 in the tetragonal phase. ZrO2 acidity was also enhanced, developing strong acid sites on its surface. The Pt/ZrO2-H3PW12O40 catalyst was active for n-pentane isomerization at 250 °C, exhibiting high selectivity to iso-pentane (95%). This result is probably due to its suitable acidity.

Síntese do material mesoporoso MCM-41 usando esponja de água-doce como fonte de sílica

Fresh water sponge was used as a silica source for the synthesis of MCM-41 via the hydrothermal process. The silica was extracted from the sponge by washing with nitric acid and piranha solution. Synthesis of MCM-41 was performed at 100 °C for 5 days and the procedure was optimized, with modifications made to the leaching temperature of the silica and the synthesis of mesoporous material, which was characterized by XRD, FT-IR, SEM and adsorption of N2. The optimal result was achieved at a temperature of 135 °C for 3 days, showing ordered mesoporous material with a surface area of 1080 m² g-1.

Bateria de métricas para avaliação da verdura material de reações de síntese

The use of a battery of three mass metrics (atomic economy - AE, reaction mass efficiency - RME, and mass intensity - MI) for systemic evaluation of the material greenness of synthesis reactions is presented. Material greenness is discussed in terms of materialization/dematerialization of the reaction system and also according to the first two Principles of Green Chemistry, and is shown to involve two components: atomic greenness (incorporation of the atoms provided by reagents into the product, evaluated by AE and RME); and massic greenness (global mass of reagents and non-stoichiometric materials, evaluated by MI, related to the production of residues).

Theoretical investigations of the bulk modulus in the tetra-cubic transition of PbTiO3 material

Resulting from ion displacement in a solid under pressure, piezoelectricity is an electrical polarization that can be observed in perovskite-type electronic ceramics, such as PbTiO3, which present cubic and tetragonal symmetries at different pressures. The transition between these crystalline phases is determined theoretically through the bulk modulus from the relationship between material energy and volume. However, the change in the material molecular structure is responsible for the piezoelectric effect. In this study, density functional theory calculations using the Becke 3-Parameter-Lee-Yang-Parr hybrid functional were employed to investigate the structure and properties associated with the transition state of the tetragonal-cubic phase change in PbTiO3 material.

Dissulfeto de molibdênio, um material multifuncional e surpreendente: doze anos depois

In 2002, a review article was published in which molybdenum disulfide properties were discussed. The last sentence of the article read as follows: "Based on that described above, we can conclude that in spite of the vast applications of molybdenum disulfide in several industrial branches, many of the potential applications need to be investigated in the future". Since 2002, novel properties of molybdenum disulfide have been described which promise to revolutionize science. The objective of the present review paper was to provide an overview of the processes of 2H-MoS2 exfoliation and properties of the single layers, reported mainly in the last decade.

Sedimentação de nutrientes e material particulado em reservatório sob influência de atividades de piscicultura no semiárido do Rio Grande do Norte

Nutrient levels in water reservoirs have been increasing over the years worldwide and fish farming is one of the activities with the potential to cause negative impacts on these environments. Thus, the sedimentation of the main nutrients was evaluated in a reservoir as well as the contribution of aquaculture in raising these rates. The results indicated a significant difference for all nutrients, with higher concentrations in areas near the fish farming, and lower levels in more distant regions. Therefore, assessments that focus only on the water column do not reflect the true impact of this activity.

Potentiometric determination of Nickel (II) ion using 2-hydroxy-1-naphthylidene-N-cyanoacetohydrazone as electroactive material

A potentiometric Nickel sensor was prepared using 2-hydroxy-1-naphthylidene-N-cyanoacetohydrazone as electro-active material and epoxy resin as a binding material. A membrane composed of 40% Schiff's base and 60% epoxy resin exhibited the best performance. The membrane showed excellent response in the concentration range of 0.15 ppm to 0.1 mol L- 1 Ni+2 ions with non-Nernstian slope of 22.0 mV/decade, had a rapid response time (less than 10 s), and can be used for three months without any considerable loss of potential. The sensor was useful within the pH range of 1.3 to 9.6, and was able to discriminate between Ni2+ and a large number of alkaline earth and transition metal ions. The practical utility of the sensor has been demonstrated by using it successfully as an indicator electrode in the potentiometric titration of Ni2+ with EDTA and oxalic acid.

OBTENÇÃO E CARACTERIZAÇÃO DE MATERIAL HÍBRIDO ENTRE SÍLICA E CICLODEXTRINAS

The obtention of silica and cyclodextrin hybrid materials was accomplished by refluxing them in xylol using citric acid as a binding agent. The materials were characterized by infrared spectroscopy, X-ray diffraction, thermogravimetric analysis, scanning electron microscopy, and elemental analysis. Evidence for the docking of cyclodextrins α and γ was substantiated based on the variation in band intensity for groups such as ≡Si-OH. Additional docking evidence includes the displacement of some of the bands that are related to cyclodextrin such as the deformation of the C-H axial bond. The α and γ-CDSi materials were characterized as amorphous compounds. The products obtained in the synthesis showed changes in the decomposition temperatures of their isolated constituents, in which the mass of α and γ-CD docked to the silica surface gave the estimated values of 41% and 47%, respectively. The elemental constituents were shown to be consistent and close to their relative theoretical values. ​Thermogravimetric analysis showed that a reduction in the percentage of the hybrids was proportional to the amount of lost mass. This new material is an improvement over synthesized organosilane materials because the operator and the environment benefit from a less toxic methodology. In addition, the material has several potential applications in complexation systems with cyclodextrin.

Resources and capabilities approach to online strategy – Multiple-case study of Finnish magazines' online services

Most Finnish periodical magazines have a website, often an online service. The objective of this thesis is to understand the magazines’ resources and capabilities and match them with online strategies’ goals and objectives. The thesis’ theoretical part focuses on explaining and classifying resources, capabilities, goals and objectives, and applying everything into Finnish magazine publishing context. In the empirical part, there is a comparative case study of four magazines. The findings indicate that with cooperating, advertising and community hosting capabilities magazines may utilize their human, brand, content and customer base resources. The resources can be further addressed to reach profitability, customer-centricity and brand congruency goals.

Maksullisen verkkopalvelun konsepti mediayhtiölle

Mediayhtiöt miettivät keinoja joilla saataisiin lukijat maksamaan myös verkkopalveluihin julkaistavista sisällöistä. Tässä tutkimuksessa selvitettiin tilaajapohjaisen maksullisen verkkopalvelu-mallin soveltuvuutta Talentum Media Oy:lle sekä kehitettiin yritykselle maksavia asiakkaita houkuttelevan sisältötuotteen konsepti. Tutkimuksessa ei ilmennyt syitä, joiden takia yrityksen olisi syytä lykätä maksullisen verkkopalvelun kehittämistä. Perinteistä lehteä ja sen verkkopalvelua ei kannata nähdä toistensa kilpailijoina. Käyttäjät ovat yhä valmiimpia maksamaan sisällöstä verkossa, kun se on järjestelty houkutteleviksi kokonaisuuksiksi ja paketoitu oikein, sekä kun he säästävät aikaa tai vaivaa verkkopalvelun käytöllä. Verkkopalvelun muuntaminen maksulliseksi on kuitenkin suunniteltava erittäin tarkkaan, muuten käyttäjät saattavat siirtyä ilmaisiin palveluihin. Talentumin verkkopalveluiden käyttäjille tehdyn kyselytutkimuksen mukaan yrityksen verkkopalveluiden käyttäjät maksaisivat mieluiten verkkokoulutuksista, erityisraporteista ja tutkivasta journalismista, ammattikirjojen tiivistelmistä, opastavista tietopaketeista, pörssi- ja yritystiedosta sekä näköislehdistä. Tutkimuksessa kehitettiin maksullisen verkkopalvelun konsepti, joka tarjoaa lukijoille itsensä kehittämisen välineitä sekä informaatiota nopeasti ja vaivattomasti heidän haluamaansa aikaan ja valitsemallaan päätelaitteella. Konseptia seuraavan tuotekehityshankkeen tuloksena syntyvästä verkkopalvelusta odotetaan saatavan merkittävää lisäliikevaihtoa yrityksen online-toiminnoille.

The relationship between first-order capabilities and online innovations. A comparative case study on the publishing sector.

The objective of this thesis was to study the relationship between firstorder capabilities and online innovations. First-order capabilities can be divided into market and technology capabilities, and they play an important role in the production of innovations. The study was carried out in publishing industry, where many changes have taken place in the online environment during the last few years. In the empirical research, four companies were studied, two magazine publishers and two newspaper publishers. The analysis was done in two phases; first every case was analyzed alone and then the cases were compared in cross-case analysis. The most important finding was the positive impact of market capability to the production of online innovations. The study also increased understanding about the relationship between market and technology capabilities and online innovations in general.

Evaluating Web Content Management Systems Compatibility for Implementing Online Communities

The purpose of this study is to study whether a Web CMS can be used to implement and host an online community. The study is divided into two parts. The theoretical part contains the definition of Web CMS and clarifies the relation between an online community and a social software. The first part also defines the parameters, which must be taken account when choosing a Web CMS for hosting an online community. The practical part of the study contains analyses of three Web CMSs, Drupal, Liferay and Plone. All the three Web CMSs were analyzed using the technical and social parameters discovered in the theoretical part of the study. The primary objective is to investigate whether the selected Web CMS can be used to implement and host an online community. If hosting is possible, the secondary objective is to investigate whether the selected Web CMS have an effect to the online community.

Virtuaalinen yhteisöllisyys ja siihen vaikuttavat tekijät

Virtuaalista yhteisöllisyyttä ja virtuaaliyhteisöissä tapahtuvaa osallistumista yhdistävää empiiristä tutkimusta ei ole toistaiseksi raportoitu tieteellisessä tutkimuksessa. Tässä tutkimuksessa tutkittiin ja analysoitiin virtuaalisen yhteisöllisyyden ja virtuaalisen osallistumisen sekä virtuaaliseen osallistumiseen vaikuttavien tekijöiden suhteita yksilön näkökulmasta virtuaaliyhteisössä. Tutkimuksen tavoitteena oli selvittää yksilön virtuaalisen yhteisöl-lisyyden kokemusta ja siihen vaikuttavia tekijöitä. Toisena keskeisenä tutkimustavoitteena oli tarkastella yksilön odottamien etujen vaikutusta yksilön osallistumiseen virtuaaliyhteisössä. Tutkimus toteutettiin tapaustutkimuksena ja tutkimuskohteena oli erään mediayrityksen ylläpitämä virtuaaliyhteisö. Tutkimuksen empiirinen osa toteutettiin strukturoituna verkkokyselynä, josta saatu aineisto analysoitiin kvantitatiivisia menetelmiä käyttäen. Tärkeimpänä tutkimuksellisena havaintona todettiin yksilön viestejä lukemalla tapahtuvan virtuaalisen osallistumisen vaikuttavan voimakkaammin yksilön kokemaan virtuaalisen yhteisöllisyyden tunteeseen kuin yksilön viestejä kirjoittamalla tapahtuvan osallistumisen. Yksilön odottamien etujen havaittiin myös poikkeavan lukemalla tai kirjoittamalla osallistuvien kohdalla. Henkilöt jotka osallistuivat virtuaaliyhteisöön viestejä lukemalla, toivoivat kognitiivisia, sosiaalisia ja hedonistisia etuja. Henkilöt jotka osallistuivat viestejä kirjoittamalla, toivoivat henkilökohtaisia, sosiaalisia ja hedonistia etuja. Henkilön sukupuolella, virtuaaliyhteisöstä saadun tiedon tarpeella ja sanomalehden tilaustottumuksilla havaittiin olevan vaikutusta yksilön osallistumisestaan toivomiin etuihin, virtuaalisen yhteisöllisyyden kokemukseen ja osallistumiseen virtuaaliyhteisöissä.

Desenvolvimento e aplicação de método GC-MS/MS para análise simultânea de 17 HPAs em material particulado atmosférico

Os hidrocarbonetos policíclicos aromáticos (HPAs) estão associados ao aumento da incidência de diversos tipos de cânceres no homem. Essas moléculas são formadas principalmente na queima incompleta de matéria orgânica, sendo encontradas em todos os compartimentos ambientais. Órgãos regulamentadores das áreas ambiental e de saúde ocupacional consideram 17 HPAs como contaminantes atmosféricos prioritários. Este trabalho apresenta um método para análise simultânea destes HPAs utilizando-se a cromatografia a gás acoplada à espectrometria de massas operando no modo tandem (GC-MS/MS). Os limites de detecção e quantificação do método mostraram-se até 5 vezes inferiores aos obtidos no método GC-MS (SCAN). O método mostrou-se seletivo para análise de HPAs em extratos de amostras de material particulado atmosférico. Uma análise comparativa de dois sistemas de solventes (diclorometano/metanol 4:1 v/v e hexano/acetona 1:1 v/v) para a extração de HPAs, utilizando amostras de material particulado atmosférico, revelou que ambas as misturas de solventes possuem poder de extração semelhante. Os resultados sugerem que é possível realizar extração de HPAs de material particulado atmosférico em ultra-som com a mistura hexano/acetona (1:1), que é menos tóxica em relação à mistura diclorometano/metanol (4:1), bastante utilizada nestas análises, sem perdas significativas na exatidão do método.