Chemistry
Mostrando 37-48 de 2733 artigos, teses e dissertações.
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37. In silico Evaluation of Cucurbit[6]uril as a Potential Detector for Cocaine and Its Adulterants Lidocaine, Caffeine, and Procaine
Illicit drugs and their trafficking require worldwide efforts in investigation, detection, and control. Colorimetric tests are often applied to identify drugs. Cocaine has some well-known adulterants that can provide a false positive response. Cucurbit[6]uril (CB[6]) has been suggested as a potential detector for cocaine and other illicit drugs. This work us
J. Braz. Chem. Soc.. Publicado em: 2021-04
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38. ORBITALS IN GENERAL CHEMISTRY, PART III: CONSEQUENCES FOR TEACHING
In Part III of this series, we undertake a critique of the nature of application of orbitals to describe or to explain the structure and the binding within molecules and materials. Teaching orbitals in introductory chemistry presents five dilemmas that cannot be easily resolved. We thus conclude, based on mathematical realties, that orbitals are not essentia
Quím. Nova. Publicado em: 2021-03
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39. COVID-19 in Brazil: A Message to the World
In Part III of this series, we undertake a critique of the nature of application of orbitals to describe or to explain the structure and the binding within molecules and materials. Teaching orbitals in introductory chemistry presents five dilemmas that cannot be easily resolved. We thus conclude, based on mathematical realties, that orbitals are not essentia
Rev. Bras. Ginecol. Obstet.. Publicado em: 2021-03
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40. ORBITALS IN GENERAL CHEMISTRY, PART II: MATHEMATICAL REALITIES
In Part II of a three-part series, we discuss two factors absent from textbooks of general chemistry that are important in a discussion of teaching orbitals. First, atomic orbitals are shown systematically to comprise algebraic formulae in coordinates of not one but four sets (spherical polar, paraboloidal, ellipsoidal, spheroconical coordinates). Each formu
Quím. Nova. Publicado em: 2021-03
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41. Síntese verde de 1,3-diariltriazenos simétricos e assimétricos em vinagre
An adaptation on the classical synthesis methodology for 1,3-diaryltriazenes for a 4-hour experimental class has been proposed with green chemistry principles in mind by using commercial vinegar as a source for diazotization with NaNO2 and keeping the reaction workup to simple vacuum filtration. Several anilines with different substituent groups were used to
Quím. Nova. Publicado em: 2021-03
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42. Estudo e validação de uma progressão de aprendizagem em cinética química de estudantes de nível superior
This work aims to study the learning progression of students from two federal universities in Rio de Janeiro within the scope of Chemical Kinetics. For the elaboration of the research questionnaire, 46 professors from eleven Brazilian universities were consulted and from the collected data, a questionnaire was elaborated and applied to 452 students of Pharma
Quím. Nova. Publicado em: 2021-03
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43. HPV infection - Screening, diagnosis and management of HPV-induced lesions
In Part II of a three-part series, we discuss two factors absent from textbooks of general chemistry that are important in a discussion of teaching orbitals. First, atomic orbitals are shown systematically to comprise algebraic formulae in coordinates of not one but four sets (spherical polar, paraboloidal, ellipsoidal, spheroconical coordinates). Each formu
Rev. Bras. Ginecol. Obstet.. Publicado em: 2021-03
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44. Different scales determine the occurrence of aquatic macrophyte species in a tropical stream
ABSTRACT Distributions of aquatic macrophyte species are commonly associated with water chemistry characteristics. However, other environmental factors that can lead to the occurrence of aquatic plants in lotic ecosystems, such as dynamic habitats linked to the surrounding landscape, have been underestimated. This study aims to evaluate landscape features th
Acta Bot. Bras.. Publicado em: 2021-03
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45. TITULADOR AUTOMÁTICO EM FLUXO-BATELADA UTILIZANDO UM HARDWARE DE CÓDIGO FONTE ABERTO ARDUINO
This work describes the development of an automatic titrometric method in flow-batch with potentiometric detection using alternative and easily accessible materials. Arduino board and its modules, solenoid valves to control the flow rate, peristaltic pump to propel and suction fluids and tubes of inert material to connect the different parts of the Flow-Batc
Quím. Nova. Publicado em: 2021-03
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46. ORBITALS IN GENERAL CHEMISTRY, PART I: THE GREAT DEBATE
In Part I of a three-part series, we present an objective survey of the technical literature discussing the inclusion of orbitals in high-school and post-secondary general chemistry. We start with the definition of orbitals. The presentation of orbitals in secondary (high) school is presented with arguments for and against. The content of orbitals in the cur
Quím. Nova. Publicado em: 2021-02
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47. WILHELM OSTWALD PARA ALÉM DO ANTIATOMISMO
The Baltic German chemist Wilhelm Ostwald (1853-1932) had his scientific prestige eclipsed in the history of chemistry due to his rejection to atomic theory, which suggests the permanence of the whig interpretation on history of chemistry in the narratives about him. In this paper, we intend to present elements on Ostwald’s biography far from his role in t
Quím. Nova. Publicado em: 2021-02
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48. INTRODUÇÃO ÀS REDES NEURAIS PARA REGRESSÕES NÃO-LINEARES: AJUSTE DE SUPERFÍCIES DE ENERGIA POTENCIAL
The present work demonstrates how neural networks are used to do non-linear regressions. The technique is presented in a simple and didactic manner and applied to fit potential energy surfaces for the FeC molecule and for the reaction H + H2. It shows how to do the fitting for single- and multi-variable system providing examples and code that can be easily e
Quím. Nova. Publicado em: 2021-02